WO2018207392A1 - Tig welding method and tig welding device - Google Patents

Tig welding method and tig welding device Download PDF

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Publication number
WO2018207392A1
WO2018207392A1 PCT/JP2017/042888 JP2017042888W WO2018207392A1 WO 2018207392 A1 WO2018207392 A1 WO 2018207392A1 JP 2017042888 W JP2017042888 W JP 2017042888W WO 2018207392 A1 WO2018207392 A1 WO 2018207392A1
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WIPO (PCT)
Prior art keywords
torch
torch electrode
current
separation
tip
Prior art date
Application number
PCT/JP2017/042888
Other languages
French (fr)
Japanese (ja)
Inventor
正行 阿部
日吉 石川
Original Assignee
株式会社アマダミヤチ
株式会社アマダホールディングス
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Application filed by 株式会社アマダミヤチ, 株式会社アマダホールディングス filed Critical 株式会社アマダミヤチ
Priority to JP2019516885A priority Critical patent/JP7019680B2/en
Publication of WO2018207392A1 publication Critical patent/WO2018207392A1/en
Priority to JP2022013262A priority patent/JP7245935B2/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/06—Arrangements or circuits for starting the arc, e.g. by generating ignition voltage, or for stabilising the arc
    • B23K9/067—Starting the arc
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/16—Arc welding or cutting making use of shielding gas
    • B23K9/167—Arc welding or cutting making use of shielding gas and of a non-consumable electrode

Definitions

  • the present invention relates to a touch start type TIG welding method and a TIG welding apparatus.
  • a TIG welding method using a non-consumable torch electrode is often used for joining terminal members of small electrical components or joining a terminal member and a conductive wire.
  • the arc discharge is started by a high-frequency generation method in which dielectric breakdown is caused by high-frequency discharge at the start and the arc is transferred to the arc, and the torch electrode and base material only at the start
  • a high voltage of 10 kV or higher is normally applied between the welding material and a DC high voltage application method that causes dielectric breakdown and transitions to an arc
  • the torch electrode is brought into contact with the welding material without using a high frequency.
  • touch start or lift start
  • the high frequency generation method and the DC high voltage application method require a high voltage power source that generates high frequency or high voltage, which increases the cost of the welding machine, and high frequency or high voltage noise causes electrical components of the electric circuit or The negative impact on surrounding electronic equipment may be disliked at the welding site.
  • the touch start method does not use a high frequency power source or a high voltage power source, the cost of the welding machine can be reduced and there is no problem of high frequency noise.
  • the touch start method is a method in which an arc is generated instantaneously when the torch electrode and the work piece are separated from each other, and there is an advantage that the arc is stably generated. Since contact is an indispensable condition, tact time is required. If the welding current is simply increased to shorten the tact time, there is a possibility that welding occurs between the torch electrode and the material to be welded when an arc occurs.
  • the welding power source is turned on with the torch electrode and the material to be welded in contact with each other, and the initial current of the initial energization is applied to the closed circuit including the torch electrode and the material to be welded. Shed. At this time, since the torch electrode is in contact with the material to be welded, no arc is generated yet regardless of the magnitude of the initial current.
  • the initial current in this case is not only during the short-circuit state in which the torch electrode is in contact with the workpiece, but also after the torch electrode is separated from the workpiece and an arc is generated, the torch electrode is separated from the workpiece. It is continuously supplied to the arc and the material to be welded until the distance reaches a certain value or more, and is usually set to about 5 to 20 A (ampere).
  • the operation of pulling the tip of the torch electrode away from the material to be welded by the set separation distance is performed.
  • This pulling-off operation is performed by calculating backward from the moving distance during forward movement (downward movement), and moving the linearly movable portion upward by a predetermined distance (downward movement extension amount + set separation distance), or by a torch by a locking means comprising a plunger or the like.
  • the body is fixed to the linearly movable part, and the linearly movable part is lifted and moved by a predetermined distance corresponding to the set separation distance, and the torch electrode is stopped at the stop position of the lifted movement destination.
  • the separation operation takes 100 ms (milliseconds) or more, and a weak arc corresponding to the initial current is generated in the gap between the torch electrode and the material to be welded from the moment when the separation operation is started.
  • the torch electrode is pulled up to the set separation position, and the current flowing through the torch electrode and the workpiece is switched from the initial current so far to the main current for main energization.
  • the amount of main current is usually set to 30 A or more, much higher than the amount of start current so as to generate an arc of sufficient power or energy necessary to reliably melt the material to be welded.
  • the torch electrode is separated from the work piece by a set separation distance, and the work piece is exposed to a power or energy arc corresponding to the main current for main energization under an optimum arc length for a predetermined time.
  • the desired welding quality jointing strength, appearance finish
  • the principle of the touch start method is that an arc generated when the tip of the torch electrode and the workpiece are separated after the closed circuit is formed between the tip of the torch electrode and the workpiece.
  • a touch start type welding apparatus in general, a closed circuit is formed and separated from the tip portion of the torch electrode and the material to be welded.
  • a weak current is applied to the torch electrode itself, and the generation of an arc is recognized by a change in voltage value or current value when the torch electrode and the workpiece are separated (for example, Patent Documents 3 and 4). It is done by.
  • JP 2014-172071 A JP2015-128787A JP 2000-176661 A JP-A-6-55269
  • a TIG welding apparatus also uses a small welded material having a small heat capacity (for example, a plate material having a cross-sectional shape of 3 mm ⁇ 1 mm or less, or a wire material having a wire diameter of 1 mm or less).
  • a small welded material having a small heat capacity for example, a plate material having a cross-sectional shape of 3 mm ⁇ 1 mm or less, or a wire material having a wire diameter of 1 mm or less.
  • the number of scenes handled is increasing.
  • the management of the welding quality is performed with the amount of energy received by the workpiece to be welded by the main current welding (main energization).
  • the initial current of the initial energization and the main current of the main energization are adjusted or controlled in any way. Even so, the welded material melts undesirably due to the influence of the initial current, and good welding quality cannot be obtained, or the welded material itself melts down due to the influence of the initial current immediately after the arc start, Welding quality was not properly managed.
  • the current of the initial current is used to prevent the arc from jumping (a phenomenon in which the arc jumps to other nearby workpieces) and the arc misfire (a phenomenon in which a fine workpiece is melted by the arc generated under the initial current). If the value is decreased, a phenomenon in which an arc is not generated easily occurs.
  • an arc formed from the material to be welded toward the tip of the torch electrode crawls up to the side surface (columnar body) above the tip portion (taper portion) of the torch electrode.
  • a phenomenon may occur.
  • This phenomenon is also considered to be a factor that welding fume generated from the material to be welded clings around the torch electrode and adheres to the torch electrode, that is, a factor that shortens the life of the torch electrode. For this reason, when the creeping phenomenon is noticeably observed, there is an increased possibility that the welding result will be poor, and this is avoided at the welding site.
  • the inventors of the present invention have studied a method for suppressing the phenomenon of the arc creeping up on the body side surface of the torch electrode in the touch start type arc welding.
  • the present invention has been made in view of the above-described problems of the prior art, and an undesired phenomenon (such as an undesired creeping of an arc on a torch electrode) that causes TIG welding by a touch start method to cause poor welding.
  • an undesired phenomenon such as an undesired creeping of an arc on a torch electrode
  • a TIG welding method and a TIG welding apparatus which can be stably and reliably performed without causing any arc, and particularly suitable arc welding can be performed even on a material to be welded having a small heat capacity to obtain good welding quality.
  • a TIG welding method includes a first step of driving a linearly movable portion supporting a torch electrode in a downward direction to move the torch electrode downward toward a workpiece, and the torch.
  • a third step of flowing a first current for initial energization through a closed circuit including the material to be welded and a fourth step of driving the linearly movable portion in the upward direction in order to move the torch electrode upward
  • a TIG welding apparatus includes a torch body that detachably mounts and holds a torch electrode, and a straight travel that is supported so as to be linearly movable in a direction parallel to the axial direction of the torch body.
  • a predetermined circuit in a closed circuit including a movable part, a rectilinear drive part for driving the rectilinearly movable part in order to move the torch electrode downward or upward relative to the material to be welded, and the torch electrode and the material to be welded;
  • a welding power source for passing an electric current, and a separation in which the tip of the torch electrode is separated from the material to be welded when the torch electrode is moved up from a state in which the tip of the torch electrode is in contact with the material to be welded
  • a control unit for controlling the linear drive unit and the welding power source, wherein the control unit is configured to generate the separation timing detection signal.
  • the welding power source is controlled to flow a first current for initial energization to the closed circuit under a state where the tip of the electrode is in contact with the workpiece, and the control unit performs the initial energization.
  • the linear drive unit is controlled to start the upward movement of the torch electrode, and when the control unit receives the separation timing detection signal from the separation detection unit, Immediately, the welding power source is controlled to switch the current flowing through the closed circuit from the first current to the second current for main energization.
  • the linearly movable portion is moved upward.
  • the timing at which the torch electrode is separated from the workpiece is simulated as the arc welding start timing, and at the same time or immediately after the separation timing is detected, the second current for main energization from the first current. Therefore, it is possible to reduce the time that the workpiece is exposed to the first current for initial energization after the occurrence of the arc as much as possible, and to control the material to be exposed to the arc by the second current for main energization. Can do.
  • a TIG welding apparatus includes a torch body that detachably mounts and holds a torch electrode, and a linear motion that is supported so as to be linearly movable in a direction parallel to the axial direction of the torch body.
  • a predetermined circuit in a closed circuit including a movable part, a rectilinear drive part for driving the rectilinearly movable part in order to move the torch electrode downward or upward relative to the material to be welded, and the torch electrode and the material to be welded;
  • a welding power source for supplying a current, and a touch timing detection signal by detecting a touch timing at which the tip of the torch electrode contacts the material to be welded in the downward movement of the torch electrode at a location away from the tip of the torch electrode
  • the torch electrode is moved up from a state in which the tip of the torch electrode is in contact with the material to be welded, and the torch electrode
  • a separation detection unit for detecting a separation timing at which the tip of the electrode is separated from the workpiece to be welded at a location away from the tip of the torch electrode and generating a separation timing detection signal; and for controlling the linear drive unit and the welding power source
  • the control unit controls the welding power source so as to
  • control unit controls the welding power source to flow a first current for initial energization to the closed circuit under a state in which a tip of the torch electrode is in contact with the workpiece. And a predetermined time after starting the initial energization, the linear drive unit is controlled to start the upward movement of the torch electrode, and the control unit controls the separation timing from the separation detection unit. Upon receiving the grayed detection signal, therewith simultaneously or immediately controls the welding power source to switch the current applied to the closed circuit to a second current for the energization from said first current.
  • the linearly movable portion is moved upward.
  • the timing at which the torch electrode is separated from the workpiece is simulated as the start timing of arc welding, and the main current is switched to the main energization simultaneously or immediately. It is possible to control the exposure to the arc by the second current for main energization as much as possible.
  • the touch detection and separation detection between the torch electrode and the material to be welded are performed by the touch detection unit and the separation detection unit located away from the tip of the torch electrode, respectively, so that the torch electrode and the welding target are generated from the heat generated at the welding location. It is possible to protect and precisely control the detection system of touch and separation with the material and the control system accompanied by these.
  • TIG welding by the touch start method is stably and surely performed by the above-described configuration and operation, and particularly a welded material having a small heat capacity (for example, a cross-sectional shape of 3 mm ⁇ 1 mm).
  • a welded material having a small heat capacity for example, a cross-sectional shape of 3 mm ⁇ 1 mm.
  • FIG. 1 is a block diagram showing the overall configuration of a TIG welding apparatus according to an embodiment of the present invention.
  • This TIG welding apparatus is systematically connected to a torch body 12 that holds the torch electrode 10, a power supply system 14 that supplies required power to the torch electrode 10 or the torch body 12, and a workpiece to be welded directly under the torch body 12.
  • An alignment mechanism 16 that aligns the material W
  • a rectilinear movement mechanism 18 that linearly moves the torch electrode 10 or the torch body 12 in its axial direction (generally in the vertical or vertical direction), and a torch electrode in the tapping system.
  • the touch / separation detection unit 15 that detects the timing at which the workpiece 10 touches the workpiece W and the timing at which the torch electrode 10 is separated from the workpiece W, the entire system and each component (particularly the utility supply system 14, the alignment mechanism 16 and And a controller 20 for controlling the linear movement mechanism 18).
  • the torch body 12 is configured as a cylindrical body made of a conductor such as copper or brass or an insulator such as a resin, for example, and a torch electrode 10 made of, for example, a rod-like tungsten electrode is detachably inserted, and the torch is inserted from the nozzle portion 12a.
  • the torch electrode 10 is held by protruding the tip of the electrode 10.
  • the utility supply system 14 includes a welding power source 22 that supplies a current for generating an arc AC between the torch electrode 10 and the workpiece W, and a shield gas or assist near the workpiece W during the generation of the arc AC. And a gas supply unit 24 for supplying gas.
  • the welding power source 22 has a DC constant current source, preferably an inverter controlled constant current source having a high-speed current switching function.
  • the positive output terminal (+) of the welding power source 22 is electrically connected to the workpiece W on the stage 28 via the electric cable 26 and the contact 27, and the negative output terminal ( ⁇ ) is connected via the electric cable 30.
  • the torch electrode 10 in the torch body 12 is electrically connected.
  • the gas supply unit 24 is configured to supply shield gas or assist gas such as nitrogen gas and oxygen gas to the torch body 12 at a constant flow rate through a gas pipe 33 such as a flexible hose.
  • the shield gas supplied to the torch body 12 is ejected from the nozzle portion 12a of the torch body 12 toward the workpiece W.
  • the alignment mechanism 16 is provided in or around the stage 28 on which the workpiece W is placed, and moves the stage 28 in the four axial directions of the horizontal direction (X direction and Y direction), the vertical direction, and the rotation direction. And a stage moving mechanism (not shown). Further, the positioning mechanism 16 or the stage 28 is provided with a fixing means for fixing the workpiece W on the stage 28 mechanically or by a vacuum suction force, and a clamp electrode (not shown) when clamping the workpiece W. 1), a compliance device or the like for sliding the workpiece W on the stage 28 in accordance with the clamping operation can be provided.
  • the rectilinear movement mechanism 18 supports the torch body 12, a rectilinear movable section 32 as a welding head provided so as to be movable up and down (straight movement) in a direction (vertical direction) parallel to the axial direction of the torch body 12, and the workpiece W
  • a rectilinear drive section 34 that linearly drives the rectilinear movable section 32 in the same direction to move the torch electrode 10 downward (advance) or ascend (retreat).
  • the linear drive unit 34 includes a drive source such as an electric motor, a motion conversion mechanism that converts the rotational drive force of the electric motor into a linear lift drive force, and the drive force of the lift motion linearly. And a transmission mechanism for transmitting to the movable portion 32.
  • the touch / separation detection unit 15 is preferably mounted on the rectilinear drive unit 34 and is located at a location away (or isolated) from the tip of the torch electrode 10, It is comprised so that the timing of the touch and isolation
  • the specific configuration and operation of the touch / separation detection unit 15 will be described in detail later.
  • FIG. 2A shows the configuration of the rectilinearly movable portion 32 in this embodiment.
  • the rectilinearly movable portion 32 has a rigid L-shaped plate body or base member 40 made of, for example, resin or metal, and the rectilinear drive portion 34 (see FIG. 1) behind the vertical flat plate portion 40a of the base member 40. ) Is coupled to the transmission mechanism via a connecting member 42.
  • a multi-purpose support portion 44 having a substantially rectangular parallelepiped shape made of an insulator such as a resin is fixed to the front surface (the surface facing the torch body 12) of the vertical flat plate portion 40a.
  • a utility relay portion 46 having a hollow block structure made of a conductor such as copper is attached to the upper surface of the multipurpose support portion 44.
  • a pair of left and right balance arms 50 are attached to both side surfaces of the multipurpose support portion 44 via a fulcrum shaft 48 so as to be rotatable in a vertical plane. The configuration around the utility relay section 46 and the balance arm 50 will be described in detail later.
  • a cylindrical torch guide 52 for guiding the torch body 12 in the vertical direction is provided at the tip of the horizontal flat plate portion 40b (the end opposite to the vertical flat plate portion 40a). Yes. Inside the torch guide 52, two linear bushings 54H and 54L are provided with a certain space or intermediate portion in the vertical direction. The torch body 12 can accurately move straight in the vertical direction by the guidance of the linear bushes 54H and 54L.
  • an opening 56 is formed at a position facing the versatile support part 44. Then, on the side surface of the intermediate portion of the torch body 12, a force introduction portion 58 having a hollow block structure made of a conductor such as copper is attached so as to be exposed to the outside through the opening 56.
  • the utility introducing portion 58 is electrically connected to the torch electrode 10 through a conductive path in the torch body 12.
  • a pair of upstream gas introduction ports 60 are provided on the upper surface of the utility introduction portion 58. Further, a downstream side gas introduction port (not shown) connected to the gas flow path in the torch body 12 is provided on the back surface (surface facing the torch body 12) of the utility introduction portion 58.
  • the inside of the utility introduction portion 58 is a hollow gas chamber or gas passage, and the upstream side gas introduction port 60 and the downstream side gas introduction port communicate with each other.
  • the utility relay section 46 on the multipurpose support section 44 is provided with a pair of downstream gas relay ports 62 on both side surfaces thereof.
  • a bridge-type tube 64 made of a resin that can be displaced or deformed and extends in an arch shape in the air is hung.
  • a bridge-like conductor 66 of a strip-like sheet that extends in an arch shape and can be deformed or deformed in the air is suspended.
  • the band-shaped sheet bridging conductor 66 is formed by stacking a plurality of (for example, nine) ultra-thin copper sheets having a thickness of 0.05 mm, for example.
  • a conductive upstream gas relay port 68 is provided on the upper surface of the utility relay section 46.
  • the port 68 is detachably connected to a terminal connector 72 of a power supply cable 70 that accommodates the electric cable 30 from the welding power source 22 (FIG. 1) and the gas pipe 33 from the gas supply unit 24 (FIG. 1). .
  • the gas supply line (gas pipe) 33 in the utility power supply cable 70 is connected to the gas passage of the upstream gas relay port 68 but also the welding current supply line (electric cable) 30 in the utility power supply cable 70.
  • the inside of the utility relay section 46 is a hollow gas chamber or gas passage, and the upstream gas relay port 68 and the downstream gas relay port 62 communicate with each other.
  • the utility power supply cable 70 is a relatively heavy cable, since it terminates at the utility relay section 46 as described above, its weight is applied to the base member 40, and the torch 13 including the torch electrode 10 and the torch body 12 is not at all. It does not take.
  • the weight of the bridging tube 64 and the bridging conductor 66 is applied to the torch 13.
  • the bridge type tube 64 and the bridge type conductor 66 are much lighter than the utility power supply cable 70, and the aerial postures of the bridge type tube 64 and the bridge type conductor 66 are arched and constant, so that the torch load hardly changes.
  • the shield gas sent from the gas supply portion 24 is the utility power supply.
  • Cable 70 gas pipe 33
  • utility relay section 46 upstream gas relay port 68 ⁇ downstream gas relay port 62
  • bridge tube 64 utility introduction section 58 (upstream gas introduction port 60 ⁇ downstream gas introduction port) )
  • Torch body 12 ⁇ Torch nozzle 12a is configured to flow in the order described above through the gas flow path connected to the torch nozzle 12a.
  • the welding current sent from the welding power source 22 is the power supply cable 70 (electric cable 30) ⁇ the power relay section 46 (conductive block) ⁇ the bridging conductor 66 ⁇ the power introduction section 58 (conductive block) ⁇ the torch body. 12 ⁇
  • the current path connected to the torch electrode 10 flows in the above order or the reverse order (reverse direction).
  • the balance arm 50 is made of a rigid body such as stainless steel, and has a bent portion 50a, a first arm portion 50b, and a second arm portion 50c, and the whole is formed in a “f” shape.
  • the bent portion 50a is rotatably attached to the front portions on both side surfaces of the multi-purpose support portion 44 by a fulcrum shaft 48.
  • a laterally long bearing 76 that fits with a pin 74 fixed to the side surface of the torch body 12 is provided at the distal end of the first arm portion 50b.
  • a vertically long opening (not shown) for passing a pin 74 movable in the vertical direction is formed on the side surface of the torch guide 52.
  • a rectangular parallelepiped-shaped balance weight 80 made of, for example, stainless steel is attached to the tip of the second arm portion 50c by a bolt 82.
  • a plate-like weight addition weight 84 may be detachably attached to the balance weight 80 by a bolt 86.
  • an opening 88 having a size through which the balance weight 80 can pass is formed.
  • the weight of the balance weight 80 is set or adjusted so that the weight moment on the torch side slightly exceeds the weight moment on the balance weight 80 side (for example, 10 to 30 g weight in terms of torch load).
  • the upper surface of the balance weight 98 is the multipurpose support portion 44 as shown in FIG. 2A. It contacts the lower surface (stopper). In this state, the balance arm 50 is stationary, and the torch 13 is held at a constant (reference) height position on the welding head 10.
  • the pin 74 of the torch 13 and the bearing 76 of the first arm portion 50b fitted to the pin 74 are a crank mechanism for mutually converting the vertical movement of the torch 13 and the rotational movement of the balance arm 50 from each other. Is configured.
  • the multipurpose support portion 44 is configured as a hollow casing or block, and an electromagnetic solenoid, for example, a plunger solenoid 90 facing the use force introduction portion 58 of the torch 13 is fixedly attached thereto through an opening (not shown). ing.
  • an electromagnetic solenoid for example, a plunger solenoid 90 facing the use force introduction portion 58 of the torch 13 is fixedly attached thereto through an opening (not shown).
  • the plunger 92 of the plunger solenoid 90 moves forward, the tip of the plunger 92 comes into contact with the side surface (opposing surface) of the working force introduction portion 58 with a large pressing force, and the plunger solenoid 90 and the working force introduction portion 58 are physically integrated (coupled).
  • the torch 13 and the base member 40 are physically integrated (coupled).
  • the rectilinear drive section 34 moves the rectilinear movable section 32 up and down
  • the torch body 12 also moves up and down integrally with the rectilinear movable section 32.
  • the balance arm 50 is attached to the linearly movable portion 32 constituting the welding head via the fulcrum 48 so as to be rotatable in a vertical plane.
  • the balance between the weight moment on the torch 13 side and the weight moment on the balance weight 80 side is adjusted by connecting the torch body 12 to the tip of the arm portion 50b and attaching the balance weight 80 to the tip of the second arm portion 50c.
  • the torch load can be reduced to a very small load (for example, 30 g weight or less).
  • a touch / separation detection unit 15 is provided on the linearly movable portion (welding head) 32. As shown in FIG. 2A, the touch / separation detection unit 15 sandwiches the light shielding member F between a plate-shaped light shielding member F integrally attached to an appropriate portion (for example, the lower end portion) of the balance arm 50.
  • the light emitting element ED and the light receiving element PD are arranged at the same height position so as to face each other. The light emitting element ED and the light receiving element PD cooperate to form an optical sensor.
  • the light emitting element ED emits the light beam P toward the light receiving element PD, and the light receiving element PD receives the light beam P or not.
  • binary signals having different values such as H level / L level, are output.
  • the height positions of the light emitting element ED and the light receiving element PD are configured to be adjustable.
  • the touch / separation detection unit 15 (FIG. 1) has a circuit that processes the output signal of the light receiving element PD, and when the output signal of the light receiving element PD changes from H level to L level, the tip of the torch electrode 10 A touch timing detection signal MS A indicating the timing of touching the workpiece W is output, and the tip of the torch electrode 10 is separated from the workpiece W when the output signal of the light receiving element PD changes from L level to H level. A separation timing detection signal MS B indicating the timing is output.
  • a linear scale 101 as shown in FIG. 2A is provided as a position sensor for measuring the relative height position of the linearly movable portion 32 or the torch 13 with respect to the stage 28 and the vertical movement distance.
  • the linear scale 101 includes a scale portion 103 that is fixed to the stage 28 and extends in the vertical direction, and a scale reading portion 105 that is attached to the base portion 40 for optically reading the scale of the scale portion 103. Yes.
  • the output signal of the scale reading unit 105 is given to the control unit 20.
  • this TIG welding apparatus is provided with a voltage detection circuit 38 (FIG. 1) for detecting a voltage V (particularly the rise) between the torch electrode 10 and the workpiece W.
  • the voltage detection circuit 38 detects the rising edge of the voltage V generated in the gap between the torch electrode 10 when the torch electrode 10 is separated from the workpiece W during energization of the touch start, and the rising edge timing (separation timing). ) Is provided to the control unit 22.
  • the voltage detection circuit 38 preferably includes a differentiation circuit in order to detect the rising edge of the voltage V accurately and at high speed.
  • control unit 20 includes a microcomputer, a memory, various interfaces, and the like, and includes an analog or digital timer built in or externally attached. It is also connected to an input device, a display device, and the like, and controls the operation of each part in the device and the entire sequence according to a predetermined program stored or stored in a memory. [Operation and action of the entire device]
  • FIGS. 2A to 2F the operation of the TIG welding apparatus and the TIG welding method in this embodiment will be described with reference to FIGS. 2A to 2F, FIG. 3, and FIGS. 4A to 4C.
  • FIG. 2A to FIG. 2F show the state of each part in the welding head at each stage of the TIG welding operation according to the embodiment (first control method).
  • FIG. 3 shows a sequence of TIG welding operations by each control method of this embodiment.
  • 4A to 4C show control procedures of the control unit 20 in each control method.
  • a material W to be welded shown as an example is obtained by winding a thin covered wire 104 around a strip-shaped terminal member 102 protruding from a work main body 100 such as a small precision electronic component package, and this winding portion.
  • the welded part In terms of dimensions, for example, the width of the terminal member 102 is about 1 mm, the thickness is about 0.2 mm, and the thickness of the covered wire 104 is about 0.05 mm.
  • a contactor 27 detachably mounted near the base of the terminal member 102 is connected to the positive terminal (+) of the welding power source 22 via an electric cable 26.
  • step S 101 initialization is performed (step S 101), the During initialization, set values of various conditions used for the current TIG welding are read from the memory and set in a predetermined register. These conditions include the current values of the initial current I O and the main current I M , the initial energization time T O, the main energization time T M, and the like.
  • the control unit 20 controls the rectilinear drive unit 34 to start the downward movement of the rectilinear movable unit 32 that has been stationary at the standby position until then (step S 102 ).
  • the balance arm 50 in the initial state, the balance arm 50 is stationary on the linearly movable portion 32 in the state shown in FIG. 2A, and the light shielding member F at the lower end of the balance arm 50 is slightly above the optical path of the light beam P. Evacuated. Thereby, the light beam P from the light emitting element ED passes under the light shielding member F so as to enter the light receiving element PD, and the output signal of the light receiving element PD is at the H level. As shown in FIG. 2B, the state of each part on the linearly movable part 32 is maintained until just before the tip of the torch electrode 10 touches the workpiece W.
  • the welding power source 22 maintains the output switch SW in the OFF state.
  • the gas supply unit 24 starts supplying shield gas in the middle of lowering the linearly movable unit 32 and the torch 12.
  • the shield gas sent from the gas supply unit 24 to the welding head (straight-moving movable unit) 32 via the utility supply cable 70 (gas pipe 33) is the utility relay unit 46 ⁇ the bridge type tube 64 ⁇ the utility force. It is injected toward the workpiece W from the injection port of the torch nozzle 12a through each gas flow path of the introduction part 58 ⁇ the torch body 12 ⁇ the torch nozzle 12a.
  • the torch electrode 10 when the tip of the torch electrode 10 abuts (touches) the workpiece W, the torch electrode 10 receives a reaction from the workpiece W, so that the balance arm 50 rotates in the clockwise direction in the figure. And the light blocking member F enters the optical path of the light beam P, and blocks the light beam P from the light emitting element ED. Then, the output signal of the light receiving element PD changes from the previous H level to the L level, and the touch / separation detection unit 15 (FIG. 1) generates the touch timing detection signal MS A , and receives this signal MS A for control. The unit 20 recognizes or detects the timing at which the tip of the torch electrode 10 touches the workpiece W (time t 1 in FIG. 3) (step S 103 ).
  • the control unit 20 controls the linear drive unit 34 to immediately stop the downward movement of the linearly movable unit 32 (Step S 104 ).
  • the switch SW of the welding power source 22 is switched from the previous OFF state to the ON state, and the welding power source 22 is caused to output a predetermined initial current IO for initial energization (step S 105 ).
  • the set current value of the initial current I 0 is an arbitrary value.
  • the current amount of the initial current I O is set to be considerably small. The As long as it is in the touch state, the torch electrode 10 and the workpiece W are electrically short-circuited, so even if the initial current I 0 flows, the applied voltage V between them is zero volts.
  • Touch start method of this embodiment is for the purpose of Haisuru the penetration of undesired material to be welded due to the initial current I 0, the set value of the initial current I 0 is set to a value smaller than the normal .
  • the set value may be any value as long as a weak arc can be raised between the torch electrode and the material to be welded, and is usually set to about 5A.
  • the initial current I 0 of 5A is a small value for a general touch start method, but the material to be welded is very small, for example, the wire diameter is 1 mm or less, and the material to be welded due to the weak initial current at the time of arc start.
  • the initial current I 0 may be set to a smaller value, for example, 2A.
  • the initial current I 0 may be set to a lower value.
  • the initial current I 0 is preferably set to 1.5 A or more, preferably 2 A or more.
  • the material W to be welded W is prevented from being melted undesirably due to the influence of the initial current I 0 at the start of the arc.
  • the arc can be controlled by the main current I M for main energization that is instantaneously switched.
  • step S 106 When the timer counts up the initial energization set time T 0 (step S 106 ), the control unit 20 starts to move upward to the rectilinear movable unit 32 via the rectilinear drive unit 34 while maintaining the energized state. (Step S107 ).
  • the linearly movable portion 32 starts to move upward, the torch 13 also starts to move upward, and the tip of the torch electrode 10 is separated from the workpiece W. Then, as shown in FIG.
  • the torch electrode 10 is not subjected to the reaction from the workpiece W side, and the balance arm 50 is rotated in the direction returning to the initial state, that is, the counterclockwise direction in the figure, so that the light shielding member F
  • the light beam P is retracted upward from the optical path of the light beam P, and the light beam P from the light emitting element ED reaches the light receiving element PD.
  • touch / separation detector 15 FIG. 1
  • touch / separation detector 15 (FIG. 1) generates a separation timing detection signal MS B
  • the control unit receives this signal MS B 20 recognizes or detects the timing at which the tip of the torch electrode 10 is separated from the workpiece W (time t 2 in FIG. 3) (step S 108 ).
  • the control unit 20 controls the welding power source 22 at the same time or immediately after detecting the separation timing (time point t 2 ), so that the current flowing through the closed circuit is energized from the previous initial current IO. Is switched to the main current I M for use (step S 109 ).
  • the main current I M is supplied to the arc AC and the workpiece W for a preset time (T M ) with a preset current value.
  • T M preset time
  • the current value of the main current I M and the main energization time (T M ) are set depending on the heat capacity of the workpiece W and the like.
  • the current value of the main current I M is the current amount of starting current I O (e.g., 5A) further larger than (e.g., 10A)
  • the energization time T M is set to the number 10ms, for example.
  • the switching from the initial current I O to the main current I M is performed simultaneously or immediately with the detection of the separation timing (time t 2 ) as described above (steps S 108 ⁇ S 109 ).
  • a slight delay for example, 5 ms
  • this type of delay does not particularly affect the operation of TIG welding, and can be brought as close to zero as possible by improving the hardware. It is very important that there is no software or intentional delay.
  • Control unit 20 when the energization time T M is the time is up (step S 110), it stops the energization to turn off the welding power source 22 (step S 111).
  • the main current I M is cut, the arc AC disappears at that moment.
  • the arc AC disappears, the melted portion of the workpiece W is immediately solidified by natural cooling in the atmosphere.
  • control unit 20 turns off the gas supply unit 24, and controls the linear drive unit 34 when the linearly movable unit 32 reaches a predetermined position (for example, an initial position) to stop the ascending operation of the linearly movable unit 32. (Step S112 ).
  • the tip of the torch electrode 10 is separated from the workpiece W when the linearly movable portion 32 is moved upward.
  • time t 2 switching from initial energization to main energization is performed, and arc welding is terminated when a preset main energization time TM has elapsed from the separation timing (t 2 ).
  • a general touch start method after the torch electrode touches the material to be welded, (A1) initial energization is started in a state where the torch electrode is in contact with the material to be welded (short circuit state) ⁇ (A2 ) Start torch lift ⁇ (A3) The torch electrode separates from the work piece ⁇ (A4) Weak arc occurs ⁇ (A5) Torch lift and move while maintaining initial energization and weak arc Continue ⁇ (A6) Establish a certain separation distance ⁇ (A7) A series of steps (A1) to (A7) in which the initial current is switched to the main current of main energization.
  • the first control method described above has its unique control concept in that the process (A4) to (A6) are skipped from the process (A3) and the process proceeds to the process (A7). Is a different special touch start method.
  • the plunger solenoid 90 is operated in the linearly movable portion 32 to integrate the torch body 12 with the base member 40 of the linearly movable portion 32, and the torch electrode 10 is integrated with the linearly movable portion 32 after the touch start. It is also possible to move up. However, if the plunger 92 of the plunger solenoid 90 is applied to the side surface (opposed surface) of the utility force introduction portion 58 with a large pressing force under the touched state, it is unnecessary for the work piece W to be welded via the torch body 12 and the torch electrode 10. Pressure may be applied, which may cause undesirable damage and deformation to the minute workpiece W having a small heat capacity. Furthermore, it is difficult to accurately detect the timing (t 2 ) when the tip of the torch electrode 10 is separated from the workpiece W when the linearly movable portion 32 is moved upward.
  • the touch / separation detection unit 15 optically monitors the relative movement or positional relationship of the torch 13 with respect to the linearly movable unit 32 via the balance arm 50, and the balance arm 50 is
  • the timing when the light shielding member F starts to move clockwise from the stationary state and enters the optical path of the light beam P of the optical sensor (ED / PD) is detected as the touch timing (t 1 ), and the balance arm 50 is counterclockwise from the stationary state.
  • the timing at which the light shielding member F starts to move in the direction and leaves the optical path of the light beam P of the optical sensor (ED / PD) is detected as the separation timing (t 2 ).
  • the relative positional relationship of the torch 13 with respect to the rectilinearly movable portion 32 is set so as to match when the touch timing (t 1 ) is detected and when the separation timing (t 2 ) is detected. Yes.
  • the touch / separation detection unit 15 is provided at a location sufficiently separated (or isolated) from the tip of the torch electrode 10 and operates without receiving any heat from the arc AC, so that precise timing detection operation is accurately performed. be able to.
  • the control unit 20 can also detect the separation timing (t 2 ) via the voltage detection circuit 38.
  • the separation timing (t 2 ) can also detect the separation timing (t 2 ) via the voltage detection circuit 38.
  • the voltage detection circuit 38 includes a differentiating circuit, and the actual separation timing (t 2 ) can be detected without delay by differentiating the rising change of the voltage V.
  • the second control method (FIGS. 3 and 4B) follows the basic control concept of the first control method described above (steps S 201 to S 212 ), and sets the rectilinear movable unit 32 to a set distance after the touch start. It is moved up by H S (step S 210 ), that is, moved up to a position where the tip of the torch electrode 10 is separated from the workpiece W by a set separation distance H S and temporarily stopped (time point t 3 in FIG. 3 ). During this stop period, the main energization time TM is increased (steps S213 to S214 ).
  • This second control method can be suitably applied to TIG welding for a material to be welded having a large heat capacity.
  • the third control method also follows the basic control concept of the first control method (steps S 301 to S 304 , S 308 to S 313 ), and the initial energization is performed by touching. It starts after the elapse of a certain period TF from the timing (t 1 ) and is limited to immediately before the separation timing (t 2 ) (step S 305 ), and the initial energization time (T O ) is set as short as possible. (Steps S 306 to S 307 ) are characteristic.
  • the rising slope of the initial current IO and the rising slope of the main current I M for main energization are made continuous so that the energization current can be raised from the zero ampere to the peak value of the main current I M in the shortest time.
  • the rising up slope control of the main current I M even down slope control the falling be suitably used.
  • This second control method can be suitably applied to TIG welding for a material to be welded having a very small heat capacity.
  • FIG. 5 shows a sequence of a comparative example corresponding to the conventional control method.
  • the control method of the comparative example after the tip of the torch electrode is separated from the material to be welded in the touch start method, typically after being pulled up to the set separation position as shown in FIG.
  • the energizing current is switched from the initial current to the main current for main energization, and the energization time (main energization time) in a state where the torch electrode is stationary at the set separation position is managed.
  • this embodiment and the comparative example have a remarkable difference in operation with respect to the presence or absence of the arc climbing phenomenon.
  • the control method of the comparative example as shown in FIG. 9A, when the tip of the torch electrode is separated from the material to be welded and separated, the arc by the initial current formed from the material to be welded toward the tip of the torch electrode Tends to creep up to the side of the columnar body of the torch electrode. Such an arc creeping phenomenon greatly reduces the concentration and stability of the arc with respect to the workpiece.
  • a torch electrode having a flat tip surface as shown in 6 (b) can be preferably used. In these cases, even if the central axis of the torch electrode 10 is slightly deviated from the center of the workpiece W, the tip surface of the torch electrode 10 abuts the top surface of the workpiece W, so that the workpiece is reliably connected. The arc can be concentrated near the center of W (W 1 , W 2 ).
  • the current is switched to the main energization at the same time or immediately when the separation timing is detected to prevent the arc from rising to the side surface of the torch electrode, and the work piece W (W 1 , W 2 ), the arc can be concentrated near the center.
  • FIG. 7 shows another example of the load balance mechanism and the touch / separation detection unit 15 provided on the rectilinearly movable portion (welding head) 32 in the above-described embodiment.
  • the same reference numerals are used for portions having the same configuration or function as those in FIGS. 2A to 2F.
  • the welding current supply system and the gas supply system are not shown.
  • the compression coil spring 114 and the tension coil spring 116 are arranged in parallel between the main body 110 of the linearly movable portion 32 and the horizontal connecting rod 112 fixed to the torch body 12.
  • the spring load of the compression coil spring 114 can be adjusted by the first torch load adjusting unit 122 including the bar screw 118 and the nut 120
  • the spring load of the tension coil spring 116 includes the bar screw 124 and the nut 126. Adjustment is possible by the second torch load adjusting unit 128.
  • a downward load in the Z direction is applied to the torch body 12, which is the sum of the weight (self-weight) L 13 of the entire torch 13 including accessories such as the connecting rod 112 and the spring load L 114 of the compression coil spring 114.
  • L 13 is because it is substantially constant, by the L 114, L 116 variably adjusted by the first and second torch load adjusting portion 122, 128 as described above, according to the characteristics of workpieces W
  • the total combined load TL can be arbitrarily adjusted.
  • the touch / separation detection unit 15 in this embodiment is provided between the horizontal bar 130 and the main body 110 that extend horizontally on the opposite side (left side in the figure) to the connecting bar 112. More specifically, a light shielding member F extending vertically upward is attached to the tip of the horizontal bar 130. Around the light shielding member F, a light emitting element ED and a light receiving element PD fixed to the main body 110 are arranged to face each other at the same height position.
  • the torch 13 (the torch electrode 10 and the torch body 12) is the main body of the rectilinearly movable portion 32 due to the reaction from the workpiece side.
  • the light shielding member F blocks the light beam P from the light emitting element ED, and the output signal of the light receiving element PD changes from the previous H level to the L level. Changes to.
  • the reaction from the material to be welded is released, so that the torch 13 moves downward relative to the main body 110 of the linearly movable portion 32.
  • the light shielding member F is retracted downward from the optical path of the light beam P, and the output signal of the light receiving element PD changes from the previous L level to the H level.
  • the touch / separation detection unit 15 in this embodiment is a relative between the main body 110 of the linearly movable unit 32 and the torch 13 coupled to the main body 110 via the compression coil spring 114 and the tension coil spring 116.
  • the movement or positional relationship is optically monitored to detect touch timing and separation timing in the touch start method.
  • an optical sensor for detecting the touch timing and an optical sensor for detecting the separation timing may be separately provided.
  • FIG. 8 shows still another embodiment related to the touch / separation detection unit 15.
  • the light shielding member F of the touch / separation detection unit 15 is interposed via the arm-shaped support member 140 in the above-described embodiment (FIGS. 2A to 2F) in which the balance arm 50 and the balance weight 80 are used for the load balance mechanism.
  • the optical sensor (light emitting element ED / light receiving element PD) is disposed on the base member 40 (horizontal flat plate portion 40b) immediately below the light shielding member F.
  • the tip of the light shielding member F is from the light beam P that propagates horizontally between the light emitting element ED and the light receiving element PD.
  • the output signal of the light receiving element PD is at the H level.
  • the tip of the light shielding member F is retracted upward from the optical path of the light beam P almost simultaneously with this.
  • the output signal of the element PD changes from L level to H level.
  • two sets of photosensors (ED 1 / PD 1 ) and (ED 2 / PD 2 ) are arranged at different height positions, and the first photosensor having a higher arrangement (detection) position.
  • the touch and separation timing is detected by (ED 1 / PD 1 ), and the initial energization start timing is acquired by the second photosensor (ED 2 / PD 2 ) having the lower arrangement (detection) position.
  • This method is suitable when initial energization is performed by further lowering the torch body 12 and applying a sufficiently large pressing force to the workpiece W even after the tip of the torch electrode 10 contacts the workpiece W.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
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  • Arc Welding Control (AREA)
  • Arc Welding In General (AREA)

Abstract

In this control method, an initial energization is begun with a touch start method and an initial current Io for initial energization is supplied to a circuit while a torch electrode is in contact with the material to be welded, after which the timing (t2) at which the torch electrode is separated from the material being welded while a linear movement unit is moved upward is assumed to be the arc welding start timing, and the current is switched from the initial current Io to a primary current IM for main energization immediately after or simultaneous with the detection of the separation timing.

Description

ＴＩＧ溶接方法及びＴＩＧ溶接装置TIG welding method and TIG welding apparatus
　本発明は、タッチスタート方式のＴＩＧ溶接方法およびＴＩＧ溶接装置に関する。 The present invention relates to a touch start type TIG welding method and a TIG welding apparatus.
　従来より、小型電気部品の端子部材同士の接合あるいは端子部材と導線との接合には、非消耗型のトーチ電極を使用するＴＩＧ溶接法が多く用いられている。 Conventionally, a TIG welding method using a non-consumable torch electrode is often used for joining terminal members of small electrical components or joining a terminal member and a conductive wire.
　非消耗型のトーチ電極を使用するＴＩＧ溶接法において、アーク放電を開始する手法には、スタート時に高周波放電により絶縁破壊を起こしてアークに移行させる高周波発生方式と、スタート時だけトーチ電極と母材つまり被溶接材との間に通常１０ｋＶ以上の高電圧を印加して絶縁破壊を起こしアークに移行させる直流高電圧印加方式と、高周波を使わずにトーチ電極を被溶接材に接触させて通電を開始した後に引き離してアーク放電を発生させるタッチスタート（またはリフトスタート）方式の３種類がある。高周波発生方式や直流高電圧印加方式は、高周波または高電圧を発生する高圧電源を必要とするために溶接機のコストが高くつくことや、高周波または高電圧のノイズが当該電気回路の電気部品や周囲の電子機器に悪い影響を及ぼすことが、溶接現場で嫌がられる場合がある。この点、タッチスタート方式は、高周波電源や高圧電源を使用しないため、溶接機のコストを下げることができるうえ、高周波ノイズの問題がない。タッチスタート方式は、トーチ電極と被溶接材が離れる際に瞬時にアークが発生する方式で、アークが安定して発生するメリットがあるが、一方ではアークスタートに際してトーチ電極が被溶接材に対して接触することが必須条件となるため、タクトタイムがかかる。タクトタイム短縮のために単純に溶接電流を上げると、アーク発生時にトーチ電極と被溶接材との間で溶着が生じてしまう可能性がある。 In the TIG welding method using a non-consumable torch electrode, the arc discharge is started by a high-frequency generation method in which dielectric breakdown is caused by high-frequency discharge at the start and the arc is transferred to the arc, and the torch electrode and base material only at the start In other words, a high voltage of 10 kV or higher is normally applied between the welding material and a DC high voltage application method that causes dielectric breakdown and transitions to an arc, and the torch electrode is brought into contact with the welding material without using a high frequency. There are three types of touch start (or lift start) methods in which arc discharge is generated by separating after starting. The high frequency generation method and the DC high voltage application method require a high voltage power source that generates high frequency or high voltage, which increases the cost of the welding machine, and high frequency or high voltage noise causes electrical components of the electric circuit or The negative impact on surrounding electronic equipment may be disliked at the welding site. In this respect, since the touch start method does not use a high frequency power source or a high voltage power source, the cost of the welding machine can be reduced and there is no problem of high frequency noise. The touch start method is a method in which an arc is generated instantaneously when the torch electrode and the work piece are separated from each other, and there is an advantage that the arc is stably generated. Since contact is an indispensable condition, tact time is required. If the welding current is simply increased to shorten the tact time, there is a possibility that welding occurs between the torch electrode and the material to be welded when an arc occurs.
　このため、従来技術のタッチスタート方式は、トーチ電極を被溶接材に接触させて通電を開始した後に、スタート電流または初期電流を流したままトーチ電極の先端を被溶接材から引き離して初期電流の下でアークを生成し、かつ初期電流の下で離間距離を増大させ、設定離間位置で初期電流から本通電に切り換えるように制御している（特許文献１，２）。 For this reason, in the touch start method of the prior art, after the torch electrode is brought into contact with the material to be welded and energization is started, the tip of the torch electrode is separated from the material to be welded while the start current or the initial current is applied and the initial current An arc is generated below, and the separation distance is increased under the initial current, and control is performed to switch from the initial current to the main energization at the set separation position (Patent Documents 1 and 2).
　より詳しくは、従来のタッチスタート方式においては、トーチ電極と被溶接材とが接触した状態の下で、溶接電源をオンにして、トーチ電極および被溶接材を含む閉回路に初期通電の初期電流を流す。この時、トーチ電極が被溶接材に接触しているので、初期電流の大きさに関係なくアークはまだ発生しない。この場合の初期電流は、トーチ電極が被溶接材に接触している短絡状態の間はもちろん、トーチ電極が被溶接材から分離してアークが発生した後もトーチ電極と被溶接材との離間距離が一定値以上に達するまで継続的にアークおよび被溶接材に供給されるもので、通常５～２０Ａ（アンペア）程度に設定されている。 More specifically, in the conventional touch start method, the welding power source is turned on with the torch electrode and the material to be welded in contact with each other, and the initial current of the initial energization is applied to the closed circuit including the torch electrode and the material to be welded. Shed. At this time, since the torch electrode is in contact with the material to be welded, no arc is generated yet regardless of the magnitude of the initial current. The initial current in this case is not only during the short-circuit state in which the torch electrode is in contact with the workpiece, but also after the torch electrode is separated from the workpiece and an arc is generated, the torch electrode is separated from the workpiece. It is continuously supplied to the arc and the material to be welded until the distance reaches a certain value or more, and is usually set to about 5 to 20 A (ampere).
　上記のようにしてタッチスタートの初期通電を開始して初期電流が安定してから、トーチ電極の先端を被溶接材から設定離間距離だけ引き離す動作を行う。この引き離し動作は、往動（下降移動）時の移動距離から逆算して直進可動部を所定距離（下降移動延長量＋設定離間距離）だけ上昇移動させるか、あるいはプランジャ等からなるロック手段によりトーチボディを直進可動部に固定して設定離間距離に相当する所定距離だけ直進可動部を上昇移動させて完了し、その上昇移動先の停止位置でトーチ電極を静止させる。通常、引き離し動作には１００ｍｓ（ミリ秒）以上の時間を要しており、この引き離し動作が開始された瞬間からトーチ電極と被溶接材のギャップには初期電流に応じた微弱なアークが生成される。 As described above, after the initial energization of the touch start is started and the initial current is stabilized, the operation of pulling the tip of the torch electrode away from the material to be welded by the set separation distance is performed. This pulling-off operation is performed by calculating backward from the moving distance during forward movement (downward movement), and moving the linearly movable portion upward by a predetermined distance (downward movement extension amount + set separation distance), or by a torch by a locking means comprising a plunger or the like. The body is fixed to the linearly movable part, and the linearly movable part is lifted and moved by a predetermined distance corresponding to the set separation distance, and the torch electrode is stopped at the stop position of the lifted movement destination. Normally, the separation operation takes 100 ms (milliseconds) or more, and a weak arc corresponding to the initial current is generated in the gap between the torch electrode and the material to be welded from the moment when the separation operation is started. The
　こうしてトーチ電極を設定離間位置まで引き上げ、トーチ電極および被溶接材に流す電流をそれまでの初期電流から本通電用の主電流に切り換える。主電流の電流量は、被溶接材を確実に溶かすのに必要十分なパワーないしエネルギーのアークを生成するように、スタート電流の電流量よりも一段と多めに、通常３０Ａ以上に設定されている。 Thus, the torch electrode is pulled up to the set separation position, and the current flowing through the torch electrode and the workpiece is switched from the initial current so far to the main current for main energization. The amount of main current is usually set to 30 A or more, much higher than the amount of start current so as to generate an arc of sufficient power or energy necessary to reliably melt the material to be welded.
　このようにトーチ電極を設定離間距離だけ被溶接材から引き離し、最適なアーク長の下で本通電用の主電流に応じたパワーないしエネルギーのアークに所定時間に亘り被溶接材を晒すことにより、所望の溶接品質（接合強度、外観仕上がり）を得るようにしている。 In this way, the torch electrode is separated from the work piece by a set separation distance, and the work piece is exposed to a power or energy arc corresponding to the main current for main energization under an optimum arc length for a predetermined time. The desired welding quality (joining strength, appearance finish) is obtained.
　また、タッチスタート方式の原理は、トーチ電極の先端部と被溶接材との間での閉回路形成をした上で、トーチ電極の先端部と被溶接材とが離間されることにより発生するアークを溶接に用いるために安定的に形成することを狙ったものであるが、タッチスタート方式の溶接装置において、一般的には、トーチ電極の先端部と被溶接材との閉回路の形成と離間の検出とを、トーチ電極自体に微弱電流をかけておき、トーチ電極と被溶接材が離間する際の電圧値又は電流値の変化によりアークの発生を認識する方法（例えば特許文献３，４）により行われている。 The principle of the touch start method is that an arc generated when the tip of the torch electrode and the workpiece are separated after the closed circuit is formed between the tip of the torch electrode and the workpiece. In a touch start type welding apparatus, in general, a closed circuit is formed and separated from the tip portion of the torch electrode and the material to be welded. In the detection of arc, a weak current is applied to the torch electrode itself, and the generation of an arc is recognized by a change in voltage value or current value when the torch electrode and the workpiece are separated (for example, Patent Documents 3 and 4). It is done by.
特開２０１４－１７２０７１号公報JP 2014-172071 A 特開２０１５－１２８７８７号公報JP2015-128787A 特開２０００－１７６６４１号公報JP 2000-176661 A 特開平６－５５２６９号公報JP-A-6-55269
　近年における電子部品の小型化の進展は著しく、それに伴ってＴＩＧ溶接装置においても、熱容量の小さい微小な被溶接材（たとえば断面形状が３ｍｍ×１ｍｍ以下の板材や、線径１ｍｍ以下の線材）を扱う場面が増えてきている。通常、溶接品質の管理は、主電流による溶接（本通電）により被溶接材が受けるエネルギー量をもって行われる。ところが、従来のＴＩＧ溶接装置において、熱容量の小さい微小な被溶接材について上記のようなタッチスタート方式のアーク溶接を行うと、初期通電の初期電流および本通電の主電流を如何様に調整または制御しても、初期電流の影響により被溶接材が不所望に溶けすぎて良好な溶接品質が得られない、あるいは、アークスタート直後の初期電流の影響により被溶接材自体が溶け落ちてしまうため、溶接品質の管理を適切に行うことができなかった。さらには、アークの横飛び（アークが近傍の他のワークに飛び火する現象）、アークの失火（初期電流の下で発生するアークによって微細なワークが溶け落ちる現象を防止するために初期電流の電流値を小さくするとアークが発生しなくなる現象）等も起こりやすい。これらのことが現実の課題となっている。 In recent years, downsizing of electronic parts has been remarkably progressed, and accordingly, a TIG welding apparatus also uses a small welded material having a small heat capacity (for example, a plate material having a cross-sectional shape of 3 mm × 1 mm or less, or a wire material having a wire diameter of 1 mm or less). The number of scenes handled is increasing. Usually, the management of the welding quality is performed with the amount of energy received by the workpiece to be welded by the main current welding (main energization). However, in the conventional TIG welding apparatus, when the above-mentioned touch start type arc welding is performed on a minute work material having a small heat capacity, the initial current of the initial energization and the main current of the main energization are adjusted or controlled in any way. Even so, the welded material melts undesirably due to the influence of the initial current, and good welding quality cannot be obtained, or the welded material itself melts down due to the influence of the initial current immediately after the arc start, Welding quality was not properly managed. In addition, the current of the initial current is used to prevent the arc from jumping (a phenomenon in which the arc jumps to other nearby workpieces) and the arc misfire (a phenomenon in which a fine workpiece is melted by the arc generated under the initial current). If the value is decreased, a phenomenon in which an arc is not generated easily occurs. These are real challenges.
　また、従来のタッチスタート方式においては、被溶接材からトーチ電極の先端に向かって形成されるアークがトーチ電極の先端部（テーパ部）を越えてその上方の側面（柱状胴部）まで這い上がる現象が生じることがある。この現象は、被溶接材から生じた溶接ヒュームがトーチ電極の周囲にまとわりついてトーチ電極に溶接ヒュームが付着する一因とも考えられ、すなわち、トーチ電極の寿命を縮める要因であるとも考えられる。このため、這い上がり現象が顕著に観察される場合には、溶接結果が不良になる可能性が高まるため、溶接現場では忌避されている。本発明者らは、タッチスタート方式のアーク溶接においてトーチ電極の胴体側面へのアークの這い上がり現象を抑止する方法を検討してきた。 Further, in the conventional touch start method, an arc formed from the material to be welded toward the tip of the torch electrode crawls up to the side surface (columnar body) above the tip portion (taper portion) of the torch electrode. A phenomenon may occur. This phenomenon is also considered to be a factor that welding fume generated from the material to be welded clings around the torch electrode and adheres to the torch electrode, that is, a factor that shortens the life of the torch electrode. For this reason, when the creeping phenomenon is noticeably observed, there is an increased possibility that the welding result will be poor, and this is avoided at the welding site. The inventors of the present invention have studied a method for suppressing the phenomenon of the arc creeping up on the body side surface of the torch electrode in the touch start type arc welding.
　本発明は、上記従来技術の問題点に鑑みてなされたものであり、タッチスタート方式によるＴＩＧ溶接を、溶接不良の原因となる望ましくない現象（トーチ電極へのアークの不所望な這い上がり等）を起こさずに安定確実に行い、特に熱容量の小さな被溶接材に対しても適切なアーク溶接を施し、良好な溶接品質を得ることができるＴＩＧ溶接方法およびＴＩＧ溶接装置を提供する。 The present invention has been made in view of the above-described problems of the prior art, and an undesired phenomenon (such as an undesired creeping of an arc on a torch electrode) that causes TIG welding by a touch start method to cause poor welding. Provided are a TIG welding method and a TIG welding apparatus which can be stably and reliably performed without causing any arc, and particularly suitable arc welding can be performed even on a material to be welded having a small heat capacity to obtain good welding quality.
　本発明の第１の観点におけるＴＩＧ溶接方法は、トーチ電極を支持する直進可動部を下降方向に駆動して、前記トーチ電極を被溶接材に向けて下降移動させる第１の工程と、前記トーチ電極の先端が前記被溶接材に接触した直後に前記直進可動部の駆動を停止する第２の工程と、前記トーチ電極の先端が前記被溶接材に接触している状態の下で前記トーチ電極および前記被溶接材を含む閉回路に初期通電のための第１の電流を流す第３の工程と、前記トーチ電極を上昇移動させるために前記直進可動部を上昇方向に駆動する第４の工程と、前記トーチ電極の先端が前記被溶接材から離れる分離のタイミングを検出する第５の工程と、前記分離のタイミングを検出するのと同時または即時に前記閉回路を流れる電流を前記第１の電流から本通電のための第２の電流に切り換える第６の工程とを有する。 A TIG welding method according to a first aspect of the present invention includes a first step of driving a linearly movable portion supporting a torch electrode in a downward direction to move the torch electrode downward toward a workpiece, and the torch. A second step of stopping the drive of the linearly movable portion immediately after the tip of the electrode contacts the workpiece, and the torch electrode under a state where the tip of the torch electrode is in contact with the workpiece And a third step of flowing a first current for initial energization through a closed circuit including the material to be welded, and a fourth step of driving the linearly movable portion in the upward direction in order to move the torch electrode upward And a fifth step of detecting a separation timing at which the tip of the torch electrode separates from the workpiece, and a current flowing through the closed circuit at the same time or immediately after the separation timing is detected. From current to main And a sixth step of switching to the second current for.
　本発明の第１の観点におけるＴＩＧ溶接装置は、トーチ電極を着脱自在に装着して保持するトーチボディと、前記トーチボディを支持してその軸方向と平行な方向で直進移動可能に設けられる直進可動部と、被溶接材に対して前記トーチ電極を下降移動または上昇移動させるために前記直進可動部を駆動する直進駆動部と、前記トーチ電極と前記被溶接材とを含む閉回路に所定の電流を流すための溶接電源と、前記トーチ電極の先端が前記被溶接材に接触している状態から前記トーチ電極を上昇移動させたときに、前記トーチ電極の先端が前記被溶接材から離れる分離のタイミングを検出して分離タイミング検出信号を発生する分離検出部と、前記直進駆動部および前記溶接電源を制御するための制御部とを有し、前記制御部が、前記トーチ電極の先端が前記被溶接材に接触している状態の下で前記閉回路に初期通電のための第１の電流を流すように前記溶接電源を制御し、前記制御部が、前記初期通電を開始してから所定時間後に、前記トーチ電極の上昇移動を開始するように前記直進駆動部を制御し、前記制御部が、前記分離検出部からの前記分離タイミング検出信号を受け取ると、それと同時または即時に、前記閉回路に流す電流を前記第１の電流から本通電のための第２の電流に切り換えるように前記溶接電源を制御する。 A TIG welding apparatus according to a first aspect of the present invention includes a torch body that detachably mounts and holds a torch electrode, and a straight travel that is supported so as to be linearly movable in a direction parallel to the axial direction of the torch body. A predetermined circuit in a closed circuit including a movable part, a rectilinear drive part for driving the rectilinearly movable part in order to move the torch electrode downward or upward relative to the material to be welded, and the torch electrode and the material to be welded; A welding power source for passing an electric current, and a separation in which the tip of the torch electrode is separated from the material to be welded when the torch electrode is moved up from a state in which the tip of the torch electrode is in contact with the material to be welded And a control unit for controlling the linear drive unit and the welding power source, wherein the control unit is configured to generate the separation timing detection signal. The welding power source is controlled to flow a first current for initial energization to the closed circuit under a state where the tip of the electrode is in contact with the workpiece, and the control unit performs the initial energization. After a predetermined time from the start, the linear drive unit is controlled to start the upward movement of the torch electrode, and when the control unit receives the separation timing detection signal from the separation detection unit, Immediately, the welding power source is controlled to switch the current flowing through the closed circuit from the first current to the second current for main energization.
　上記第１の観点においては、タッチスタート方式で初期通電を開始してトーチ電極と被溶接材とを含む閉回路に初期通電用の第１の電流を流した後に、直進可動部を上昇移動させるときにトーチ電極が被溶接材から分離したタイミングをアーク溶接の開始のタイミングと擬制したうえで、分離のタイミングを検出するのと同時または即時に第１の電流から本通電用の第２の電流に切り換えるので、被溶接材がアーク発生後に初期通電用の第１の電流に晒される時間を可及的に低減させて、本通電用の第２の電流によるアークに晒されるように制御することができる。 In the first aspect, after the initial energization is started by the touch start method and the first current for initial energization is supplied to the closed circuit including the torch electrode and the material to be welded, the linearly movable portion is moved upward. Sometimes, the timing at which the torch electrode is separated from the workpiece is simulated as the arc welding start timing, and at the same time or immediately after the separation timing is detected, the second current for main energization from the first current. Therefore, it is possible to reduce the time that the workpiece is exposed to the first current for initial energization after the occurrence of the arc as much as possible, and to control the material to be exposed to the arc by the second current for main energization. Can do.
　本発明の第２の観点におけるＴＩＧ溶接装置は、トーチ電極を着脱自在に装着して保持するトーチボディと、前記トーチボディを支持してその軸方向と平行な方向で直進移動可能に設けられる直進可動部と、被溶接材に対して前記トーチ電極を下降移動または上昇移動させるために前記直進可動部を駆動する直進駆動部と、前記トーチ電極と前記被溶接材とを含む閉回路に所定の電流を流すための溶接電源と、前記トーチ電極の下降移動において前記トーチ電極の先端が前記被溶接材に接触するタッチのタイミングを前記トーチ電極の先端から離れた場所で検出してタッチタイミング検出信号を発生するタッチ検出部と、前記トーチ電極の先端が前記被溶接材に接触している状態から前記トーチ電極を上昇移動させたときに、前記トーチ電極の先端が前記被溶接材から離れる分離のタイミングを前記トーチ電極の先端から離れた場所で検出して分離タイミング検出信号を発生する分離検出部と、前記直進駆動部および前記溶接電源を制御するための制御部とを有し、前記制御部が、前記タッチ検出部からの前記タッチタイミング検出信号を受け取ると、直ちにまたは所定時間後に前記初期通電を開始するように前記溶接電源を制御し、前記制御部が、前記トーチ電極の先端が前記被溶接材に接触している状態の下で前記閉回路に初期通電のための第１の電流を流すように前記溶接電源を制御し、前記制御部が、前記初期通電を開始してから所定時間後に、前記トーチ電極の上昇移動を開始するように前記直進駆動部を制御し、前記制御部が、前記分離検出部からの前記分離タイミング検出信号を受け取ると、それと同時または即時に、前記閉回路に流す電流を前記第１の電流から本通電のための第２の電流に切り換えるように前記溶接電源を制御する。 A TIG welding apparatus according to a second aspect of the present invention includes a torch body that detachably mounts and holds a torch electrode, and a linear motion that is supported so as to be linearly movable in a direction parallel to the axial direction of the torch body. A predetermined circuit in a closed circuit including a movable part, a rectilinear drive part for driving the rectilinearly movable part in order to move the torch electrode downward or upward relative to the material to be welded, and the torch electrode and the material to be welded; A welding power source for supplying a current, and a touch timing detection signal by detecting a touch timing at which the tip of the torch electrode contacts the material to be welded in the downward movement of the torch electrode at a location away from the tip of the torch electrode When the torch electrode is moved up from a state in which the tip of the torch electrode is in contact with the material to be welded, and the torch electrode A separation detection unit for detecting a separation timing at which the tip of the electrode is separated from the workpiece to be welded at a location away from the tip of the torch electrode and generating a separation timing detection signal; and for controlling the linear drive unit and the welding power source And when the control unit receives the touch timing detection signal from the touch detection unit, the control unit controls the welding power source so as to start the initial energization immediately or after a predetermined time. And the control unit controls the welding power source to flow a first current for initial energization to the closed circuit under a state in which a tip of the torch electrode is in contact with the workpiece. And a predetermined time after starting the initial energization, the linear drive unit is controlled to start the upward movement of the torch electrode, and the control unit controls the separation timing from the separation detection unit. Upon receiving the grayed detection signal, therewith simultaneously or immediately controls the welding power source to switch the current applied to the closed circuit to a second current for the energization from said first current.
　上記第２の観点においては、タッチスタート方式で初期通電を開始してトーチ電極と被溶接材とを含む閉回路に初期通電用の第１の電流を流した後に、直進可動部を上昇移動させるときにトーチ電極が被溶接材から分離したタイミングをアーク溶接の開始のタイミングとして擬制した上で、同時又は即時に本通電に切り換えるので、被溶接材がアーク発生後に初期通電用の第１の電流に晒される時間を可及的に低減して、本通電用の第２の電流によるアークに晒されるように制御することができる。さらに、トーチ電極と被溶接材との間のタッチおよび分離の検出をトーチ電極の先端から離れて位置するタッチ検出部および分離検出部でそれぞれ行うので、溶接箇所で生じる熱からトーチ電極と被溶接材とのタッチおよび分離の検出系並びにこれらを伴う制御系を保護して精緻に制御することができる。 In the second aspect, after starting the initial energization by the touch start method and supplying the first current for initial energization to the closed circuit including the torch electrode and the material to be welded, the linearly movable portion is moved upward. Sometimes, the timing at which the torch electrode is separated from the workpiece is simulated as the start timing of arc welding, and the main current is switched to the main energization simultaneously or immediately. It is possible to control the exposure to the arc by the second current for main energization as much as possible. Furthermore, the touch detection and separation detection between the torch electrode and the material to be welded are performed by the touch detection unit and the separation detection unit located away from the tip of the torch electrode, respectively, so that the torch electrode and the welding target are generated from the heat generated at the welding location. It is possible to protect and precisely control the detection system of touch and separation with the material and the control system accompanied by these.
　本発明のＴＩＧ溶接方法またはＴＩＧ溶接装置によれば、上記のような構成および作用により、タッチスタート方式によるＴＩＧ溶接を安定確実に行い、特に熱容量の小さな被溶接材（たとえば断面形状が３ｍｍ×１ｍｍ以下の板材や線径２ｍｍ以下の線材）については、初期通電によるアークの発生を可及的に低減ないし無効にするので、初期通電によるアークによる不所望の被溶接材の溶け込みおよびトーチ電極側面へのアークの這い上がり現象が排除された適切なアーク溶接が施され、良好な溶接品質を得ることができる。 According to the TIG welding method or the TIG welding apparatus of the present invention, TIG welding by the touch start method is stably and surely performed by the above-described configuration and operation, and particularly a welded material having a small heat capacity (for example, a cross-sectional shape of 3 mm × 1 mm). For the following plate materials and wires having a wire diameter of 2 mm or less, the occurrence of arcs due to initial energization is reduced or eliminated as much as possible, so undesired welding of the welded material due to arcs due to initial energization and to the side of the torch electrode Appropriate arc welding in which the arc creeping phenomenon is eliminated is performed, and good welding quality can be obtained.
本発明の一実施形態におけるＴＩＧ溶接装置の全体構成を示すブロック図である。It is a block diagram which shows the whole structure of the TIG welding apparatus in one Embodiment of this invention. 上記ＴＩＧ溶接装置における溶接ヘッド部の構成およびＴＩＧ溶接動作における一段階（トーチが待機位置にある時）の各部の状態を示す部分断面図である。It is a fragmentary sectional view which shows the structure of the welding head part in the said TIG welding apparatus, and the state of each part of one step (when a torch is in a standby position) in TIG welding operation. 上記ＴＩＧ溶接動作における一段階（トーチ電極の先端が被溶接材に接触する直前）の状態を示す一部断面側面図である。It is a partial cross section side view which shows the state of the one stage in the said TIG welding operation (just before the front-end | tip of a torch electrode contacts a to-be-welded material). 上記ＴＩＧ溶接動作における一段階（トーチ電極の先端が被溶接材に接触している時）の各部の状態を示す一部断面側面図である。It is a partial cross section side view which shows the state of each part of the one stage (when the front-end | tip of a torch electrode is contacting the to-be-welded material) in the said TIG welding operation. 上記ＴＩＧ溶接動作における一段階（トーチ電極の先端が被溶接材から分離した直後）の各部の状態を示す一部断面側面図である。It is a partial cross section side view which shows the state of each part of the said 1st step in TIG welding operation (immediately after the front-end | tip of the torch electrode isolate | separated from the to-be-welded material). 上記ＴＩＧ溶接動作における一段階（終了間際）の各部の状態を示す一部断面側面図である。It is a partial cross section side view which shows the state of each part of the one stage (just before completion | finish) in the said TIG welding operation. 上記ＴＩＧ溶接動作における一段階（終了直後）の各部の状態を示す一部断面側面図である。It is a partial cross section side view which shows the state of each part of the one step (immediately after completion | finish) in the said TIG welding operation. 実施形態における各制御方式のシーケンスを示すタイミング図である。It is a timing diagram which shows the sequence of each control system in embodiment. 実施形態の第１の制御方式における制御手順を示すフローチャート図である。It is a flowchart figure which shows the control procedure in the 1st control system of embodiment. 実施形態の第２の制御方式における制御手順を示すフローチャート図である。It is a flowchart figure which shows the control procedure in the 2nd control system of embodiment. 実施形態の第３の制御方式における制御手順を示すフローチャート図である。It is a flowchart figure which shows the control procedure in the 3rd control system of embodiment. 比較例の制御方式のシーケンスを示すタイミング図である。It is a timing diagram which shows the sequence of the control system of a comparative example. トーチ電極の一例を示す部分斜視図である。It is a fragmentary perspective view which shows an example of a torch electrode. 別の一実施例におけるタッチ／分離検出部の構成を示す一部断面正面図である。It is a partial cross section front view which shows the structure of the touch / separation detection part in another one Example. 更に別の実施例におけるタッチ／分離検出部の構成を示す一部断面正面図である。It is a partial cross section front view which shows the structure of the touch / separation detection part in another Example. 比較例の制御方式におけるアーク発生状態（アーク這い上がり現象あり）を示す図である。It is a figure which shows the arc generation | occurence | production state (there is an arc climbing phenomenon) in the control system of a comparative example. 実施形態の制御方式におけるアーク発生状態（アーク這い上がり現象なし）を示す図である。It is a figure which shows the arc generation state (there is no arc creeping phenomenon) in the control system of the embodiment.
　以下、添付図を参照して本発明の好適な実施形態を説明する。
［装置全体及び各部の構成］ Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[Entire device and configuration of each part]
　図１に、本発明の一実施形態におけるＴＩＧ溶接装置の全体構成をブロック図で示す。このＴＩＧ溶接装置は、システム的には、トーチ電極１０を保持するトーチボディ１２と、トーチ電極１０ないしトーチボディ１２に所要の用力を供給する用力供給系１４と、トーチボディ１２の直下で被溶接材Ｗの位置合わせを行う位置合わせ機構１６と、トーチ電極１０ないしトーチボディ１２をその軸方向（一般的には鉛直または縦方向）で直進移動させる直進移動機構１８と、タッスタート方式においてトーチ電極１０が被溶接材Ｗにタッチしたタイミングおよびトーチ電極１０が被溶接材Ｗから分離したタイミングを検出するタッチ・分離検出部１５と、システム全体および各部（特に用力供給系１４、位置合わせ機構１６および直進移動機構１８）を制御する制御部２０とを有している。 FIG. 1 is a block diagram showing the overall configuration of a TIG welding apparatus according to an embodiment of the present invention. This TIG welding apparatus is systematically connected to a torch body 12 that holds the torch electrode 10, a power supply system 14 that supplies required power to the torch electrode 10 or the torch body 12, and a workpiece to be welded directly under the torch body 12. An alignment mechanism 16 that aligns the material W, a rectilinear movement mechanism 18 that linearly moves the torch electrode 10 or the torch body 12 in its axial direction (generally in the vertical or vertical direction), and a torch electrode in the tapping system. The touch / separation detection unit 15 that detects the timing at which the workpiece 10 touches the workpiece W and the timing at which the torch electrode 10 is separated from the workpiece W, the entire system and each component (particularly the utility supply system 14, the alignment mechanism 16 and And a controller 20 for controlling the linear movement mechanism 18).
　トーチボディ１２は、たとえば銅または真鍮等の導体または樹脂等の絶縁体からなる筒状体として構成され、たとえば棒状のタングステン電極からなるトーチ電極１０を着脱自在に挿入し、そのノズル部１２ａよりトーチ電極１０の先端部を突出させてトーチ電極１０を保持する。 The torch body 12 is configured as a cylindrical body made of a conductor such as copper or brass or an insulator such as a resin, for example, and a torch electrode 10 made of, for example, a rod-like tungsten electrode is detachably inserted, and the torch is inserted from the nozzle portion 12a. The torch electrode 10 is held by protruding the tip of the electrode 10.
　用力供給系１４は、トーチ電極１０と被溶接材Ｗとの間にアークＡＣを生成するための電流を供給する溶接電源２２と、アークＡＣの生成中に被溶接材Ｗ付近にシールドガスまたはアシストガスを供給するガス供給部２４とを含んでいる。 The utility supply system 14 includes a welding power source 22 that supplies a current for generating an arc AC between the torch electrode 10 and the workpiece W, and a shield gas or assist near the workpiece W during the generation of the arc AC. And a gas supply unit 24 for supplying gas.
　溶接電源２２は、直流の定電流源、好ましくは高速の電流切り替え機能を有するインバータ制御の定電流源を有している。溶接電源２２の正極の出力端子（＋）は電気ケーブル２６および接触子２７を介してステージ２８上の被溶接材Ｗに電気的に接続され、負極の出力端子（－）は電気ケーブル３０を介してトーチボディ１２内のトーチ電極１０に電気的に接続される。トーチ電極１０と被溶接材Ｗとが物理的に接触している時、あるいはトーチ電極１０と被溶接材Ｗとの間でアーク放電が生じている時は、溶接電源２２、トーチ電極１０および被溶接材Ｗの間に閉回路が形成される。 The welding power source 22 has a DC constant current source, preferably an inverter controlled constant current source having a high-speed current switching function. The positive output terminal (+) of the welding power source 22 is electrically connected to the workpiece W on the stage 28 via the electric cable 26 and the contact 27, and the negative output terminal (−) is connected via the electric cable 30. Thus, the torch electrode 10 in the torch body 12 is electrically connected. When the torch electrode 10 and the workpiece W are in physical contact, or when an arc discharge is generated between the torch electrode 10 and the workpiece W, the welding power source 22, the torch electrode 10, and the workpiece A closed circuit is formed between the welding materials W.
　ガス供給部２４は、窒素ガス、酸素ガス等のシールドガスまたはアシストガスを可撓ホース等のガス管３３を介して一定の流量でトーチボディ１２に供給するように構成されている。トーチボディ１２に供給されたシールドガスは、トーチボディ１２のノズル部１２ａより被溶接材Ｗに向けて噴出するようになっている。 The gas supply unit 24 is configured to supply shield gas or assist gas such as nitrogen gas and oxygen gas to the torch body 12 at a constant flow rate through a gas pipe 33 such as a flexible hose. The shield gas supplied to the torch body 12 is ejected from the nozzle portion 12a of the torch body 12 toward the workpiece W.
　位置合わせ機構１６は、被溶接材Ｗを載置するステージ２８の内部または周囲に設けられ、ステージ２８を水平方向（Ｘ方向，Ｙ方向）、鉛直方向および回転方向の４軸方向で移動させることができるステージ移動機構（図示せず）を有している。また、位置合わせ機構１６またはステージ２８は、ステージ２８上で被溶接材Ｗをメカニカルにあるいはバキューム吸引力によって固定するための固定手段や、被溶接材Ｗをクランプする場合は、クランプ電極（図示せず）のクランプ動作に追従して被溶接材Ｗをステージ２８上で摺動させるためのコンプライアンス・デバイス等を備えることもできる。 The alignment mechanism 16 is provided in or around the stage 28 on which the workpiece W is placed, and moves the stage 28 in the four axial directions of the horizontal direction (X direction and Y direction), the vertical direction, and the rotation direction. And a stage moving mechanism (not shown). Further, the positioning mechanism 16 or the stage 28 is provided with a fixing means for fixing the workpiece W on the stage 28 mechanically or by a vacuum suction force, and a clamp electrode (not shown) when clamping the workpiece W. 1), a compliance device or the like for sliding the workpiece W on the stage 28 in accordance with the clamping operation can be provided.
　直進移動機構１８は、トーチボディ１２を支持してその軸方向と平行な方向（縦方向）で昇降移動（直進移動）可能に設けられる溶接ヘッドとしての直進可動部３２と、被溶接材Ｗに対してトーチ電極１０を下降（前進）移動または上昇（後退）移動させるために直進可動部３２を同方向に直進駆動する直進駆動部３４とを含んでいる。直進駆動部３４は、図示省略するが、駆動源たとえば電気モータと、この電気モータの回転駆動力を直線的な昇降移動の駆動力に変換する運動変換機構と、その昇降移動の駆動力を直進可動部３２に伝える伝動機構とを備えている。 The rectilinear movement mechanism 18 supports the torch body 12, a rectilinear movable section 32 as a welding head provided so as to be movable up and down (straight movement) in a direction (vertical direction) parallel to the axial direction of the torch body 12, and the workpiece W On the other hand, it includes a rectilinear drive section 34 that linearly drives the rectilinear movable section 32 in the same direction to move the torch electrode 10 downward (advance) or ascend (retreat). Although not shown in the drawings, the linear drive unit 34 includes a drive source such as an electric motor, a motion conversion mechanism that converts the rotational drive force of the electric motor into a linear lift drive force, and the drive force of the lift motion linearly. And a transmission mechanism for transmitting to the movable portion 32.
　タッチ・分離検出部１５は、後述するように好ましくは直進駆動部３４に搭載され、トーチ電極１０の先端から離れた（または隔離された）場所に位置して、タッチスタート方式におけるトーチ電極１０と被溶接材Ｗとの間のタッチおよび分離のタイミングを検出するように構成されている。タッチ・分離検出部１５の具体的な構成および作用は、後に詳しく説明する。 As will be described later, the touch / separation detection unit 15 is preferably mounted on the rectilinear drive unit 34 and is located at a location away (or isolated) from the tip of the torch electrode 10, It is comprised so that the timing of the touch and isolation | separation with the to-be-welded material W may be detected. The specific configuration and operation of the touch / separation detection unit 15 will be described in detail later.
　図２Ａに、この実施形態における直進可動部３２の構成を示す。この直進可動部３２は、たとえば樹脂または金属からなる剛性の断面Ｌ形の板体またはベース部材４０を有しており、このベース部材４０の垂直平板部４０ａの背後で直進駆動部３４（図１）の伝動機構に連結部材４２を介して結合されている。 FIG. 2A shows the configuration of the rectilinearly movable portion 32 in this embodiment. The rectilinearly movable portion 32 has a rigid L-shaped plate body or base member 40 made of, for example, resin or metal, and the rectilinear drive portion 34 (see FIG. 1) behind the vertical flat plate portion 40a of the base member 40. ) Is coupled to the transmission mechanism via a connecting member 42.
　ベース部材４０上で、垂直平板部４０ａの前面（トーチボディ１２と対向する面）には、たとえば樹脂等の絶縁体からなる略直方体形状の多用途支持部４４が固着されている。多用途支持部４４の上面には、たとえば銅等の導体からなる中空ブロック構造の用力中継部４６が取り付けられている。多用途支持部４４の両側面には、支点の軸４８を介して左右一対のバランスアーム５０が鉛直面内で回転可能に取り付けられている。用力中継部４６およびバランスアーム５０回りの構成については、後に詳しく説明する。 On the base member 40, a multi-purpose support portion 44 having a substantially rectangular parallelepiped shape made of an insulator such as a resin is fixed to the front surface (the surface facing the torch body 12) of the vertical flat plate portion 40a. A utility relay portion 46 having a hollow block structure made of a conductor such as copper is attached to the upper surface of the multipurpose support portion 44. A pair of left and right balance arms 50 are attached to both side surfaces of the multipurpose support portion 44 via a fulcrum shaft 48 so as to be rotatable in a vertical plane. The configuration around the utility relay section 46 and the balance arm 50 will be described in detail later.
　ベース部材４０上で、その水平平板部４０ｂの先端部（垂直平板部４０ａと反対側の端部）には、トーチボディ１２を鉛直方向で案内するための円筒状のトーチガイド５２が設けられている。このトーチガイド５２の内側には、上下方向に一定のスペースまたは中間部を挟んで２つのリニアブッシュ５４Ｈ，５４Ｌが設けられている。トーチボディ１２は、両リニアブッシュ５４Ｈ，５４Ｌの案内により正確に鉛直方向で直進移動することができる。 On the base member 40, a cylindrical torch guide 52 for guiding the torch body 12 in the vertical direction is provided at the tip of the horizontal flat plate portion 40b (the end opposite to the vertical flat plate portion 40a). Yes. Inside the torch guide 52, two linear bushings 54H and 54L are provided with a certain space or intermediate portion in the vertical direction. The torch body 12 can accurately move straight in the vertical direction by the guidance of the linear bushes 54H and 54L.
　トーチガイド５２の中間部には、多用途支持部４４と対向する位置に開口部５６が形成されている。そして、トーチボディ１２の中間部の側面には、開口部５６を介して外に露出するように、たとえば銅等の導体からなる中空ブロック構造の用力導入部５８が取り付けられている。この用力導入部５８は、トーチボディ１２内の導電路を介してトーチ電極１０に電気的に接続されている。 In the middle part of the torch guide 52, an opening 56 is formed at a position facing the versatile support part 44. Then, on the side surface of the intermediate portion of the torch body 12, a force introduction portion 58 having a hollow block structure made of a conductor such as copper is attached so as to be exposed to the outside through the opening 56. The utility introducing portion 58 is electrically connected to the torch electrode 10 through a conductive path in the torch body 12.
　用力導入部５８の上面には一対の上流側ガス導入ポート６０が設けられている。さらに、用力導入部５８の背面（トーチボディ１２と向き合う面）には、トーチボディ１２内のガス流路に接続する下流側ガス導入ポート（図示せず）が設けられている。用力導入部５８の内部は中空のガス室またはガス通路になっており、上流側ガス導入ポート６０と下流側ガス導入ポートとは連通している。 A pair of upstream gas introduction ports 60 are provided on the upper surface of the utility introduction portion 58. Further, a downstream side gas introduction port (not shown) connected to the gas flow path in the torch body 12 is provided on the back surface (surface facing the torch body 12) of the utility introduction portion 58. The inside of the utility introduction portion 58 is a hollow gas chamber or gas passage, and the upstream side gas introduction port 60 and the downstream side gas introduction port communicate with each other.
　一方、多用途支持部４４上の用力中継部４６には、その両側面に一対の下流側ガス中継ポート６２が設けられている。この下流側ガス中継ポート６２と用力導入部５８のガス導入ポート６０との間には、空中でアーチ形に延びる変位または変形可能な樹脂製の架橋型チューブ６４が架けられている。さらに、用力中継部４６および用力導入部５８の互いに向き合う面（正面）の間に、空中でアーチ形に延びる変位または変形可能な帯状シートの架橋型導体６６が架けられている。この帯状シートの架橋型導体６６は、たとえば厚さ０．０５ｍｍの極薄の銅シートを複数枚（たとえば９枚）重ねて構成されている。 Meanwhile, the utility relay section 46 on the multipurpose support section 44 is provided with a pair of downstream gas relay ports 62 on both side surfaces thereof. Between the downstream side gas relay port 62 and the gas introduction port 60 of the utility introduction portion 58, a bridge-type tube 64 made of a resin that can be displaced or deformed and extends in an arch shape in the air is hung. Further, between the mutually facing surfaces (front surfaces) of the utility relay portion 46 and the utility introduction portion 58, a bridge-like conductor 66 of a strip-like sheet that extends in an arch shape and can be deformed or deformed in the air is suspended. The band-shaped sheet bridging conductor 66 is formed by stacking a plurality of (for example, nine) ultra-thin copper sheets having a thickness of 0.05 mm, for example.
　用力中継部４６の上面には、導電性の上流側ガス中継ポート６８が設けられている。このポート６８には、溶接電源２２（図１）からの電気ケーブル３０およびガス供給部２４（図１）からのガス管３３を収容する用力供給ケーブル７０の終端コネクタ７２が着脱可能に接続される。この場合、用力供給ケーブル７０内のガス供給ライン（ガス管）３３が上流側ガス中継ポート６８のガス通路に接続されるだけでなく、用力供給ケーブル７０内の溶接電流供給ライン（電気ケーブル）３０が用力中継部４６の本体に電気的に接続される。用力中継部４６の内部は中空のガス室またはガス通路になっており、上流側ガス中継ポート６８と下流側ガス中継ポート６２とは連通している。 On the upper surface of the utility relay section 46, a conductive upstream gas relay port 68 is provided. The port 68 is detachably connected to a terminal connector 72 of a power supply cable 70 that accommodates the electric cable 30 from the welding power source 22 (FIG. 1) and the gas pipe 33 from the gas supply unit 24 (FIG. 1). . In this case, not only the gas supply line (gas pipe) 33 in the utility power supply cable 70 is connected to the gas passage of the upstream gas relay port 68 but also the welding current supply line (electric cable) 30 in the utility power supply cable 70. Is electrically connected to the main body of the utility relay unit 46. The inside of the utility relay section 46 is a hollow gas chamber or gas passage, and the upstream gas relay port 68 and the downstream gas relay port 62 communicate with each other.
　用力供給ケーブル７０は比較的重いケーブルであるが、上記のように用力中継部４６で終端するので、その重量はベース部材４０にかかり、トーチ電極１０およびトーチボディ１２を合わせたトーチ１３には全くかからない。トーチ１３には架橋型チューブ６４および架橋型導体６６の重量がかかる。これら架橋型チューブ６４および架橋型導体６６は、用力供給ケーブル７０に比して格段に軽量であり、しかもそれぞれの空中姿勢がアーチ形で一定なので、トーチ荷重に変動を来たすことは殆どない。 Although the utility power supply cable 70 is a relatively heavy cable, since it terminates at the utility relay section 46 as described above, its weight is applied to the base member 40, and the torch 13 including the torch electrode 10 and the torch body 12 is not at all. It does not take. The weight of the bridging tube 64 and the bridging conductor 66 is applied to the torch 13. The bridge type tube 64 and the bridge type conductor 66 are much lighter than the utility power supply cable 70, and the aerial postures of the bridge type tube 64 and the bridge type conductor 66 are arched and constant, so that the torch load hardly changes.
　上記のような多用途支持部４４上の用力中継部４６およびトーチボディ１２側の用力導入部５８回りの用力供給系統において、ガス供給部２４（図１）より送出されるシールドガスは、用力供給ケーブル７０（ガス管３３）→用力中継部４６（上流側ガス中継ポート６８→下流側ガス中継ポート６２）→架橋型チューブ６４→用力導入部５８（上流側ガス導入ポート６０→下流側ガス導入ポート）→トーチボディ１２→トーチノズル１２ａと繋がるガス流路を上記の順に流れるようになっている。また、溶接電源２２より送出される溶接電流は、用力供給ケーブル７０（電気ケーブル３０）→用力中継部４６（導電性ブロック）→架橋型導体６６→用力導入部５８（導電性ブロック）→トーチボディ１２→トーチ電極１０と繋がる電流経路を上記の順または逆の順（逆方向）に流れるようになっている。 In the utility power supply system around the utility relay portion 46 on the multi-purpose support portion 44 and the utility introduction portion 58 on the torch body 12 side as described above, the shield gas sent from the gas supply portion 24 (FIG. 1) is the utility power supply. Cable 70 (gas pipe 33) → utility relay section 46 (upstream gas relay port 68 → downstream gas relay port 62) → bridge tube 64 → utility introduction section 58 (upstream gas introduction port 60 → downstream gas introduction port) ) → Torch body 12 → Torch nozzle 12a is configured to flow in the order described above through the gas flow path connected to the torch nozzle 12a. Further, the welding current sent from the welding power source 22 is the power supply cable 70 (electric cable 30) → the power relay section 46 (conductive block) → the bridging conductor 66 → the power introduction section 58 (conductive block) → the torch body. 12 → The current path connected to the torch electrode 10 flows in the above order or the reverse order (reverse direction).
　バランスアーム５０は、剛体たとえばステンレス鋼からなり、屈曲部５０ａ、第１アーム部５０ｂおよび第２アーム部５０ｃを有し、全体が“ヘ”字状に形成されている。屈曲部５０ａは、支点の軸４８により多用途支持部４４の両側面の前部に回転可能に取り付けられる。第１アーム部５０ｂの先端部には、トーチボディ１２の側面に固着されているピン７４と嵌合する横長の軸受７６が設けられている。トーチガイド５２の側面には、上下方向に移動可能なピン７４を通すための縦長の開口部（図示せず）が形成されている。 The balance arm 50 is made of a rigid body such as stainless steel, and has a bent portion 50a, a first arm portion 50b, and a second arm portion 50c, and the whole is formed in a “f” shape. The bent portion 50a is rotatably attached to the front portions on both side surfaces of the multi-purpose support portion 44 by a fulcrum shaft 48. A laterally long bearing 76 that fits with a pin 74 fixed to the side surface of the torch body 12 is provided at the distal end of the first arm portion 50b. On the side surface of the torch guide 52, a vertically long opening (not shown) for passing a pin 74 movable in the vertical direction is formed.
　一方、第２アーム部５０ｃの先端部には、たとえばステンレス鋼からなる直方体形状のバランスウエイト８０がボルト８２によって取り付けられている。このバランスウエイト８０の重量を調整するために、たとえば板片状の重量加算用ウエイト８４をボルト８６によってバランスウエイト８０に着脱可能に取り付けてもよい。ベース部材４０の水平平板部４０ｂには、バランスウエイト８０が通れる大きさの開口部８８が形成されている。 On the other hand, a rectangular parallelepiped-shaped balance weight 80 made of, for example, stainless steel is attached to the tip of the second arm portion 50c by a bolt 82. In order to adjust the weight of the balance weight 80, for example, a plate-like weight addition weight 84 may be detachably attached to the balance weight 80 by a bolt 86. In the horizontal flat plate portion 40b of the base member 40, an opening 88 having a size through which the balance weight 80 can pass is formed.
　バランスアーム５０においては、第１アーム部５０ｂの先端部に取り付けられているトーチ１３回りの総重量つまりトーチ荷重により図２Ａにおいて反時計方向の重量モーメントが作用する一方で、第２アーム部５０ｃの先端部に取り付けられているバランスウエイト８０の重量により図２Ａにおいて時計方向の重量モーメントが作用する。 In the balance arm 50, while the total weight around the torch 13 attached to the tip of the first arm portion 50b, that is, the torch load, a counterclockwise weight moment acts in FIG. 2A, while the second arm portion 50c A weight moment in the clockwise direction acts in FIG. 2A due to the weight of the balance weight 80 attached to the tip.
　ここで、トーチ側の重量モーメントがバランスウエイト８０側の重量モーメントを少し（たとえばトーチ荷重に換算して１０～３０ｇ重）だけ上回るように、バランスウエイト８０の重量が設定ないし調整される。このようにトーチ側の重量モーメントをバランスウエイト８０側の重量モーメントより大きく設定することで、トーチ１３に外力が加わらないときは、図２Ａに示すようにバランスウエイト９８の上面が多用途支持部４４の下面（ストッパ）に当接する。この状態で、バランスアーム５０は静止し、溶接ヘッド１０上でトーチ１３が一定（基準）の高さ位置に保持される。 Here, the weight of the balance weight 80 is set or adjusted so that the weight moment on the torch side slightly exceeds the weight moment on the balance weight 80 side (for example, 10 to 30 g weight in terms of torch load). Thus, by setting the weight moment on the torch side to be larger than the weight moment on the balance weight 80 side, when no external force is applied to the torch 13, the upper surface of the balance weight 98 is the multipurpose support portion 44 as shown in FIG. 2A. It contacts the lower surface (stopper). In this state, the balance arm 50 is stationary, and the torch 13 is held at a constant (reference) height position on the welding head 10.
　なお、トーチ１３のピン７４とこれに嵌合している第１アーム部５０ｂの軸受７６は、トーチ１３の鉛直方向の直進移動とバランスアーム５０の回転移動とを相互に変換するためのクランク機構を構成している。 The pin 74 of the torch 13 and the bearing 76 of the first arm portion 50b fitted to the pin 74 are a crank mechanism for mutually converting the vertical movement of the torch 13 and the rotational movement of the balance arm 50 from each other. Is configured.
　多用途支持部４４は中空の筐体またはブロックとして構成され、その中に開口（図示せず）を介してトーチ１３の用力導入部５８と対向する電磁ソレノイドたとえばプランジャソレノイド９０が固定して取り付けられている。このプランジャソレノイド９０のプランジャ９２が前進移動すると、その先端が用力導入部５８の側面（対向面）に大きな押圧力で当接して、プランジャソレノイド９０と用力導入部５８が物理的に一体化（結合）し、ひいてはトーチ１３とベース部材４０とが物理的に一体化（結合）するようになっている。この一体化の状態で、直進駆動部３４が直進可動部３２を昇降移動させると、トーチボディ１２も直進可動部３２と一体に昇降移動するようになっている。 The multipurpose support portion 44 is configured as a hollow casing or block, and an electromagnetic solenoid, for example, a plunger solenoid 90 facing the use force introduction portion 58 of the torch 13 is fixedly attached thereto through an opening (not shown). ing. When the plunger 92 of the plunger solenoid 90 moves forward, the tip of the plunger 92 comes into contact with the side surface (opposing surface) of the working force introduction portion 58 with a large pressing force, and the plunger solenoid 90 and the working force introduction portion 58 are physically integrated (coupled). As a result, the torch 13 and the base member 40 are physically integrated (coupled). In this integrated state, when the rectilinear drive section 34 moves the rectilinear movable section 32 up and down, the torch body 12 also moves up and down integrally with the rectilinear movable section 32.
　上記のように、この実施形態のＴＩＧ溶接装置においては、溶接ヘッドを構成する直進可動部３２に支点４８を介してバランスアーム５０を鉛直な面内で回転可能に取り付け、バランスアーム５０の第１アーム部５０ｂの先端部にトーチボディ１２を結合し、第２アーム部５０ｃの先端部にバランスウェイト８０を取り付ける構成により、トーチ１３側の重量モーメントとバランスウエイト８０側の重量モーメントとのバランスを調整するだけで、トーチ荷重を非常に小さい荷重（たとえば３０ｇ重以下）に軽減することができる。 As described above, in the TIG welding apparatus of this embodiment, the balance arm 50 is attached to the linearly movable portion 32 constituting the welding head via the fulcrum 48 so as to be rotatable in a vertical plane. The balance between the weight moment on the torch 13 side and the weight moment on the balance weight 80 side is adjusted by connecting the torch body 12 to the tip of the arm portion 50b and attaching the balance weight 80 to the tip of the second arm portion 50c. By simply doing, the torch load can be reduced to a very small load (for example, 30 g weight or less).
　さらに、このＴＩＧ溶接装置においては、直進可動部（溶接ヘッド）３２上に、タッチスタート方式においてトーチ電極１０の先端と被溶接材Ｗとの間のタッチのタイミングおよび分離のタイミングを検出するためのタッチ／分離検出部１５を設けている。このタッチ／分離検出部１５は、図２Ａに示すように、バランスアーム５０の適当な箇所（たとえば下端部）に一体に取り付けられた板片状の遮光部材Ｆと、この遮光部材Ｆを挟むように対向して同一の高さ位置に配置される発光素子ＥＤおよび受光素子ＰＤとを有している。発光素子ＥＤおよび受光素子ＰＤは協働して光センサを構成し、発光素子ＥＤが受光素子ＰＤに向けて光ビームＰを射出し、受光素子ＰＤが光ビームＰを受光するか否かに応じて値の異なるたとえばＨレベル／Ｌレベルの２値信号を出力するようになっている。発光素子ＥＤおよび受光素子ＰＤの高さ位置は調整可能に構成されている。 Further, in this TIG welding apparatus, on the linearly movable portion (welding head) 32, a touch timing and a timing of separation between the tip of the torch electrode 10 and the workpiece W are detected in a touch start method. A touch / separation detection unit 15 is provided. As shown in FIG. 2A, the touch / separation detection unit 15 sandwiches the light shielding member F between a plate-shaped light shielding member F integrally attached to an appropriate portion (for example, the lower end portion) of the balance arm 50. The light emitting element ED and the light receiving element PD are arranged at the same height position so as to face each other. The light emitting element ED and the light receiving element PD cooperate to form an optical sensor. The light emitting element ED emits the light beam P toward the light receiving element PD, and the light receiving element PD receives the light beam P or not. For example, binary signals having different values, such as H level / L level, are output. The height positions of the light emitting element ED and the light receiving element PD are configured to be adjustable.
　タッチ／分離検出部１５（図１）は、受光素子ＰＤの出力信号を信号処理する回路を有し、受光素子ＰＤの出力信号がＨレベルからＬレベルに変化した時に、トーチ電極１０の先端が被溶接材Ｗにタッチしたタイミングを示すタッチタイミング検出信号ＭＳＡを出力し、受光素子ＰＤの出力信号がＬレベルからＨレベルに変化した時に、トーチ電極１０の先端が被溶接材Ｗから分離したタイミングを示す分離タイミング検出信号ＭＳＢを出力するようになっている。 The touch / separation detection unit 15 (FIG. 1) has a circuit that processes the output signal of the light receiving element PD, and when the output signal of the light receiving element PD changes from H level to L level, the tip of the torch electrode 10 A touch timing detection signal MS A indicating the timing of touching the workpiece W is output, and the tip of the torch electrode 10 is separated from the workpiece W when the output signal of the light receiving element PD changes from L level to H level. A separation timing detection signal MS B indicating the timing is output.
　この実施形態では、ステージ２８に対する直進可動部３２またはトーチ１３の相対的な高さ位置および昇降移動距離を測定するための位置センサとして、たとえば図２Ａに示すようなリニアスケール１０１が設けられている。このリニアスケール１０１は、ステージ２８に固定された鉛直方向に延びる目盛部１０３と、この目盛部１０３の目盛を光学的に読み取るためにベース部４０に取り付けられた目盛読取部１０５とを有している。目盛読取部１０５の出力信号は、制御部２０に与えられる。 In this embodiment, for example, a linear scale 101 as shown in FIG. 2A is provided as a position sensor for measuring the relative height position of the linearly movable portion 32 or the torch 13 with respect to the stage 28 and the vertical movement distance. . The linear scale 101 includes a scale portion 103 that is fixed to the stage 28 and extends in the vertical direction, and a scale reading portion 105 that is attached to the base portion 40 for optically reading the scale of the scale portion 103. Yes. The output signal of the scale reading unit 105 is given to the control unit 20.
　さらに、このＴＩＧ溶接装置は、トーチ電極１０と被溶接材Ｗとの間の電圧Ｖ（特にその立ち上がり）を検出するための電圧検出回路３８（図１）を備えている。この電圧検出回路３８は、タッチスタートの通電中にトーチ電極１０が被溶接材Ｗから分離した時に両者間のギャップに生じる電圧Ｖの立ち上がりのエッジを検出し、その立ち上がりエッジのタイミング（分離のタイミング）を表す出力信号ＫＳを制御部２２に与えるように構成されている。電圧検出回路３８は、電圧Ｖの立ち上がりのエッジを正確かつ高速に検出するために、好ましくは微分回路を備えている。 Furthermore, this TIG welding apparatus is provided with a voltage detection circuit 38 (FIG. 1) for detecting a voltage V (particularly the rise) between the torch electrode 10 and the workpiece W. The voltage detection circuit 38 detects the rising edge of the voltage V generated in the gap between the torch electrode 10 when the torch electrode 10 is separated from the workpiece W during energization of the touch start, and the rising edge timing (separation timing). ) Is provided to the control unit 22. The voltage detection circuit 38 preferably includes a differentiation circuit in order to detect the rising edge of the voltage V accurately and at high speed.
　図１において、制御部２０は、マイクロコンピュータ、メモリおよび各種インタフェース等を含むほか、アナログ式またはディジタル式のタイマを内蔵または外付けで備えており、図示の各部だけでなく不図示の起動スイッチ、入力装置および表示装置等とも接続されており、メモリに蓄積または格納した所定のプログラムにしたがって装置内の各部の動作および全体のシーケンスを制御する。
［装置全体の動作及び作用］ In FIG. 1, the control unit 20 includes a microcomputer, a memory, various interfaces, and the like, and includes an analog or digital timer built in or externally attached. It is also connected to an input device, a display device, and the like, and controls the operation of each part in the device and the entire sequence according to a predetermined program stored or stored in a memory.
[Operation and action of the entire device]
　以下、図２Ａ～図２Ｆ、図３、図４Ａ～図４Ｃを参照して、この実施形態におけるＴＩＧ溶接装置およびＴＩＧ溶接方法の作用を説明する。 Hereinafter, the operation of the TIG welding apparatus and the TIG welding method in this embodiment will be described with reference to FIGS. 2A to 2F, FIG. 3, and FIGS. 4A to 4C.
　図２Ａ～図２Ｆは、実施形態（第１の制御方式）によるＴＩＧ溶接動作の各段階における溶接ヘッド内の各部の状態を示す。図３は、この実施形態の各制御方式によるＴＩＧ溶接動作のシーケンスを示す。図４Ａ～図４Ｃは、各制御方式における制御部２０の制御手順を示す。 FIG. 2A to FIG. 2F show the state of each part in the welding head at each stage of the TIG welding operation according to the embodiment (first control method). FIG. 3 shows a sequence of TIG welding operations by each control method of this embodiment. 4A to 4C show control procedures of the control unit 20 in each control method.
　なお、図２Ａ～図２Ｆにおいて、一例として示す被溶接材Ｗは、小型精密電子部品パッケージ等のワーク本体１００から突出する短冊状の端子部材１０２に細い被覆線１０４を巻き付けて、この巻き付け部を被溶接部としている。寸法的には、たとえば、端子部材１０２の幅が約１ｍｍ、厚さが約０．２ｍｍであり、被覆線１０４の太さは約０．０５ｍｍである。端子部材１０２の根元付近に着脱可能に装着される接触子２７は、電気ケーブル２６を介して溶接電源２２の正極端子（＋）に接続されている。 2A to 2F, a material W to be welded shown as an example is obtained by winding a thin covered wire 104 around a strip-shaped terminal member 102 protruding from a work main body 100 such as a small precision electronic component package, and this winding portion. The welded part. In terms of dimensions, for example, the width of the terminal member 102 is about 1 mm, the thickness is about 0.2 mm, and the thickness of the covered wire 104 is about 0.05 mm. A contactor 27 detachably mounted near the base of the terminal member 102 is connected to the positive terminal (+) of the welding power source 22 via an electric cable 26.
　この実施形態の第１の制御方式（図３、図４Ａ）によれば、制御部２０は、図３の時点ｔ０で起動信号を入力すると、先ず初期化を行い（ステップＳ１０１）、その初期化の中で今回のＴＩＧ溶接に用いる各種条件の設定値をメモリから読み出して所定のレジスタにセットする。これらの条件には、初期電流ＩＯおよび主電流ＩＭの電流値、初期通電時間ＴＯおよび本通電時間ＴＭ等が含まれる。 First control scheme (FIG. 3, FIG. 4A) of this embodiment according to, the control unit 20, by entering the start signal at time t 0 in FIG. 3, first, initialization is performed (step S 101), the During initialization, set values of various conditions used for the current TIG welding are read from the memory and set in a predetermined register. These conditions include the current values of the initial current I O and the main current I M , the initial energization time T O, the main energization time T M, and the like.
　次いで、制御部２０は、直進駆動部３４を制御して、それまで待機位置で静止していた直進可動部３２に下降移動を開始させる（ステップＳ１０２）。この場合、初期状態では、直進可動部３２上でバランスアーム５０は図２Ａに示すような状態で静止しており、バランスアーム５０の下端の遮光部材Ｆは光ビームＰの光路からわずかに上方に退避している。これにより、発光素子ＥＤからの光ビームＰは遮光部材Ｆの下をかすめるように通過して受光素子ＰＤに入射し、受光素子ＰＤの出力信号はＨレベルになっている。図２Ｂに示すように、直進可動部３２上の各部の状態は、トーチ電極１０の先端が被溶接材Ｗにタッチする寸前まで維持される。 Next, the control unit 20 controls the rectilinear drive unit 34 to start the downward movement of the rectilinear movable unit 32 that has been stationary at the standby position until then (step S 102 ). In this case, in the initial state, the balance arm 50 is stationary on the linearly movable portion 32 in the state shown in FIG. 2A, and the light shielding member F at the lower end of the balance arm 50 is slightly above the optical path of the light beam P. Evacuated. Thereby, the light beam P from the light emitting element ED passes under the light shielding member F so as to enter the light receiving element PD, and the output signal of the light receiving element PD is at the H level. As shown in FIG. 2B, the state of each part on the linearly movable part 32 is maintained until just before the tip of the torch electrode 10 touches the workpiece W.
　一方、制御部２０の制御の下で、溶接電源２２は出力のスイッチＳＷをオフ状態に維持している。ガス供給部２４は、直進可動部３２およびトーチ１２を下ろす途中で、シールドガスの供給を開始する。上記のように、ガス供給部２４より用力供給ケーブル７０（ガス管３３）を介して溶接ヘッド（直進可動部）３２に送られてきたシールドガスは、用力中継部４６→架橋型チューブ６４→用力導入部５８→トーチボディ１２→トーチノズル１２ａの各ガス流路を通ってトーチノズル１２ａの噴射口より被溶接材Ｗに向けて噴射される。 On the other hand, under the control of the control unit 20, the welding power source 22 maintains the output switch SW in the OFF state. The gas supply unit 24 starts supplying shield gas in the middle of lowering the linearly movable unit 32 and the torch 12. As described above, the shield gas sent from the gas supply unit 24 to the welding head (straight-moving movable unit) 32 via the utility supply cable 70 (gas pipe 33) is the utility relay unit 46 → the bridge type tube 64 → the utility force. It is injected toward the workpiece W from the injection port of the torch nozzle 12a through each gas flow path of the introduction part 58 → the torch body 12 → the torch nozzle 12a.
　そして、図２Ｃに示すように、トーチ電極１０の先端が被溶接材Ｗに当接（タッチ）すると、トーチ電極１０が被溶接材Ｗから反作用を受けることにより、バランスアーム５０が図の時計方向に回動して、遮光部材Ｆが光ビームＰの光路に進入し、発光素子ＥＤからの光ビームＰを遮断する。すると、受光素子ＰＤの出力信号がそれまでのＨレベルからＬレベルに変わって、タッチ／分離検出部１５（図１）がタッチタイミング検出信号ＭＳＡを発生し、この信号ＭＳＡを受けて制御部２０はトーチ電極１０の先端が被溶接材Ｗにタッチしたタイミング（図３の時点ｔ１）を認識または検出する（ステップＳ１０３）。 As shown in FIG. 2C, when the tip of the torch electrode 10 abuts (touches) the workpiece W, the torch electrode 10 receives a reaction from the workpiece W, so that the balance arm 50 rotates in the clockwise direction in the figure. And the light blocking member F enters the optical path of the light beam P, and blocks the light beam P from the light emitting element ED. Then, the output signal of the light receiving element PD changes from the previous H level to the L level, and the touch / separation detection unit 15 (FIG. 1) generates the touch timing detection signal MS A , and receives this signal MS A for control. The unit 20 recognizes or detects the timing at which the tip of the torch electrode 10 touches the workpiece W (time t 1 in FIG. 3) (step S 103 ).
　制御部２０は、上記のようにしてタッチのタイミング（時点ｔ１）を検出すると、直進駆動部３４を制御して、即時に直進可動部３２の下降移動を停止させる（ステップＳ１０４）。次いで、溶接電源２２のスイッチＳＷをそれまでのオフ状態からオン状態に切り換え、溶接電源２２に初期通電のための所定の初期電流ＩＯを出力させる（ステップＳ１０５）。この初期通電では、溶接電源２２の直流電圧源Ｅの正極出力端子→アースケーブル２６→被溶接材Ｗ→トーチ電極１０→トーチボディ１２→用力導入部５８→架橋型導体６６→用力中継部４６→用力ケーブル７７（電気ケーブル３０）→直流電圧源Ｅの負極出力端子の電流経路（閉回路）で、直流の初期電流Ｉ０が流れる。 When detecting the touch timing (time point t 1 ) as described above, the control unit 20 controls the linear drive unit 34 to immediately stop the downward movement of the linearly movable unit 32 (Step S 104 ). Next, the switch SW of the welding power source 22 is switched from the previous OFF state to the ON state, and the welding power source 22 is caused to output a predetermined initial current IO for initial energization (step S 105 ). In this initial energization, the positive output terminal of the DC voltage source E of the welding power source 22 → the ground cable 26 → the material to be welded W → the torch electrode 10 → the torch body 12 → the force introducing portion 58 → the bridging conductor 66 → the power relay portion 46 → In the current path (closed circuit) of the negative output terminal of the utility voltage 77 (electric cable 30) → DC voltage source E, a DC initial current I 0 flows.
　初期電流Ｉ０の設定電流値は任意の値であり、この実施形態のように被溶接材Ｗが熱容量の小さい微小なワークである場合は、初期電流ＩＯの電流量はかなり少なめに設定される。タッチ状態にある限り、トーチ電極１０と被溶接材Ｗは電気的に短絡しているので、初期電流Ｉ０が流れても、両者間の印加電圧Ｖは零ボルトである。 The set current value of the initial current I 0 is an arbitrary value. When the workpiece W is a small work having a small heat capacity as in this embodiment, the current amount of the initial current I O is set to be considerably small. The As long as it is in the touch state, the torch electrode 10 and the workpiece W are electrically short-circuited, so even if the initial current I 0 flows, the applied voltage V between them is zero volts.
　この実施形態におけるタッチスタート方式は、初期電流Ｉ０による被溶接材の不所望な溶け込みを排することを目的とするもので、初期電流Ｉ０の設定値は通常よりも小さい値に設定される。その設定値はトーチ電極と被溶接材との間で微弱なアークが立ち上がらせるものであればよく、通常は５Ａ程度に設定される。５Ａの初期電流Ｉ０は一般的なタッチスタート方式としては小さい値であるが、被溶接材が微小、例えば線径が１ｍｍ以下であって、アークスタート時の微弱な初期電流による被溶接材の溶け込みの影響が大きいと考えられる場合には、初期電流Ｉ０をさらに小さな値、たとえば２Ａに設定してもよい。一方で、初期電流Ｉ０をさらに低い値にしてもよいが、たとえば１Ａ程度に設定した場合には、被溶接材が微小な場合であっても、初期電流Ｉ０が小さすぎて初期の微弱なアークも安定的に発生しない場合が多い。したがって、初期電流Ｉ０は１．５Ａ以上、好ましくは２Ａ以上に設定することが好ましい。 Touch start method of this embodiment is for the purpose of Haisuru the penetration of undesired material to be welded due to the initial current I 0, the set value of the initial current I 0 is set to a value smaller than the normal . The set value may be any value as long as a weak arc can be raised between the torch electrode and the material to be welded, and is usually set to about 5A. The initial current I 0 of 5A is a small value for a general touch start method, but the material to be welded is very small, for example, the wire diameter is 1 mm or less, and the material to be welded due to the weak initial current at the time of arc start. When it is considered that the influence of the penetration is large, the initial current I 0 may be set to a smaller value, for example, 2A. On the other hand, the initial current I 0 may be set to a lower value. For example, when the current is set to about 1 A, the initial current I 0 is too small even if the material to be welded is very small. Many arcs do not occur stably. Therefore, the initial current I 0 is preferably set to 1.5 A or more, preferably 2 A or more.
　この第１の制御方式においては、このような微小な初期電流Ｉ０による場合であっても、アークの立ち上がり時における初期電流Ｉ０の影響により被溶接材Ｗが不所望に溶け過ぎることを回避した上で、瞬時に切り替えられた本通電用の主電流ＩＭによってアークを制御することが可能である。 In this first control method, even if such a small initial current I 0 is used, the material W to be welded W is prevented from being melted undesirably due to the influence of the initial current I 0 at the start of the arc. In addition, the arc can be controlled by the main current I M for main energization that is instantaneously switched.
　タイマが初期通電の設定時間Ｔ０を計時してタイムアップすると（ステップＳ１０６）、制御部２０は、通電状態を維持したまま、直進駆動部３４を介して直進可動部３２に上昇移動を開始させる（ステップＳ１０７）。直進可動部３２が上昇移動を開始すると、トーチ１３も一緒に上昇移動を開始し、トーチ電極１０の先端が被溶接材Ｗから分離する。そうすると、図２Ｄに示すように、トーチ電極１０が被溶接材Ｗ側からの反作用を受けなくなり、バランスアーム５０が初期状態に戻る方向すなわち図の反時計方向に回動して、遮光部材Ｆが光ビームＰの光路から上方に退避し、発光素子ＥＤからの光ビームＰが受光素子ＰＤに届くようになる。そうすると、受光素子ＰＤの出力信号がそれまでのＬレベルからＨレベルに変わり、タッチ／分離検出部１５（図１）が分離タイミング検出信号ＭＳＢを発生し、この信号ＭＳＢを受けて制御部２０はトーチ電極１０の先端が被溶接材Ｗから分離したタイミング（図３の時点ｔ２）を認識または検出する（ステップＳ１０８）。 When the timer counts up the initial energization set time T 0 (step S 106 ), the control unit 20 starts to move upward to the rectilinear movable unit 32 via the rectilinear drive unit 34 while maintaining the energized state. (Step S107 ). When the linearly movable portion 32 starts to move upward, the torch 13 also starts to move upward, and the tip of the torch electrode 10 is separated from the workpiece W. Then, as shown in FIG. 2D, the torch electrode 10 is not subjected to the reaction from the workpiece W side, and the balance arm 50 is rotated in the direction returning to the initial state, that is, the counterclockwise direction in the figure, so that the light shielding member F The light beam P is retracted upward from the optical path of the light beam P, and the light beam P from the light emitting element ED reaches the light receiving element PD. Then, changes to H level from L level of the output signal to that of the light receiving element PD, touch / separation detector 15 (FIG. 1) generates a separation timing detection signal MS B, the control unit receives this signal MS B 20 recognizes or detects the timing at which the tip of the torch electrode 10 is separated from the workpiece W (time t 2 in FIG. 3) (step S 108 ).
　そして、制御部２０は、この分離のタイミング（時点ｔ２）を検出するのと同時または即時に、溶接電源２２を制御して上記閉回路を流れる電流をそれまでの初期電流ＩＯから本通電用の主電流ＩＭに切り換える（ステップＳ１０９）。この本通電では、主電流ＩＭがあらかじめ設定された電流値であらかじめ設定された時間（ＴＭ）だけアークＡＣおよび被溶接材Ｗに供給される。この場合、通電状態でトーチ電極１０の先端が被溶接材Ｗから分離するや否や両者間に生じるギャップに即時にアークＡＣが発生し、このアークＡＣが導電路となって閉回路の一部を形成する。 Then, the control unit 20 controls the welding power source 22 at the same time or immediately after detecting the separation timing (time point t 2 ), so that the current flowing through the closed circuit is energized from the previous initial current IO. Is switched to the main current I M for use (step S 109 ). In this main energization, the main current I M is supplied to the arc AC and the workpiece W for a preset time (T M ) with a preset current value. In this case, as soon as the tip of the torch electrode 10 is separated from the workpiece W in the energized state, an arc AC is immediately generated in the gap generated between the two, and this arc AC becomes a conductive path and forms a part of the closed circuit. Form.
　主電流ＩＭの電流値および本通電時間（ＴＭ）は、被溶接材Ｗの熱容量等に依存して設定される。この実施例のように熱容量の小さい微小な被溶接材Ｗに対しては、主電流ＩＭの電流値は、スタート電流ＩＯの電流量（たとえば５Ａ）よりも一段と大き目の値（たとえば１０Ａ）に設定される。また、本通電時間ＴＭはたとえば数１０ｍｓに設定される。 The current value of the main current I M and the main energization time (T M ) are set depending on the heat capacity of the workpiece W and the like. For small small workpieces W heat capacity as in this embodiment, the current value of the main current I M is the current amount of starting current I O (e.g., 5A) further larger than (e.g., 10A) Set to Further, the energization time T M is set to the number 10ms, for example.
　この実施形態では、上記のようにして分離のタイミング（時点ｔ２）を検出するのと同時または即時に初期電流ＩＯから主電流ＩＭへの切り換えを行うが（ステップＳ１０８→Ｓ１０９）、溶接電源２２等のハードウェア上の応答速度に応じて切換えに若干（たとえば５ｍｓ）のディレイが生じることもある。しかし、この種のディレイは、ＴＩＧ溶接の作用に特に影響を来すものではなく、ハードウェアの改良によって可及的に零に近づけられる。ソフトウェア的または意図的なディレイを設けないことが非常に重要である。 In this embodiment, the switching from the initial current I O to the main current I M is performed simultaneously or immediately with the detection of the separation timing (time t 2 ) as described above (steps S 108 → S 109 ). Depending on the response speed on hardware such as the welding power source 22, a slight delay (for example, 5 ms) may occur in switching. However, this type of delay does not particularly affect the operation of TIG welding, and can be brought as close to zero as possible by improving the hardware. It is very important that there is no software or intentional delay.
　こうしてトーチ電極１０の先端が被溶接材Ｗから分離するや否や両者間に生じるギャップに本通電用の主電流ＩＭによるアークＡＣが発生し、トーチ電極１０の上昇移動している最中に、被溶接材Ｗは主電流ＩＭの電流量に応じたパワーないしエネルギーのアークＡＣに晒されて、期待通りに溶ける。この場合、トーチ電極１０の上昇移動つまり離間距離の増大に伴ってアーク長が変化するが、被溶接材Ｗの熱容量ないしサイズが小さいので、主電流ＩＭの電流量が適切に制御される限り、溶接品質への影響は少ない。 As soon as the tip of the torch electrode 10 is separated from the workpiece W, an arc AC due to the main current I M for main energization is generated in the gap formed between them, and the torch electrode 10 is moving upward. the workpieces W are exposed to the power or the energy of the arc AC in accordance with the current amount of the main current I M, dissolved as expected. In this case, the arc length with increasing upward movement that is the distance of the torch electrode 10 is changed, since the heat capacity or size of the material to be welded W is small, as long as the amount of current of the main current I M is appropriately controlled There is little effect on welding quality.
　制御部２０は、本通電時間ＴＭがタイムアップすると（ステップＳ１１０）、溶接電源２２をオフして通電を止める（ステップＳ１１１）。主電流ＩＭが切られると、その瞬間にアークＡＣは消滅する。アークＡＣが消滅すると、被溶接材Ｗの溶け込み部分が大気中の自然冷却によってすぐに凝固する。 Control unit 20, when the energization time T M is the time is up (step S 110), it stops the energization to turn off the welding power source 22 (step S 111). When the main current I M is cut, the arc AC disappears at that moment. When the arc AC disappears, the melted portion of the workpiece W is immediately solidified by natural cooling in the atmosphere.
　この後、制御部２０は、ガス供給部２４をオフし、直進可動部３２が所定位置（たとえば初期位置）に到達したところで直進駆動部３４を制御して直進可動部３２の上昇動作を停止させる（ステップＳ１１2）。 Thereafter, the control unit 20 turns off the gas supply unit 24, and controls the linear drive unit 34 when the linearly movable unit 32 reaches a predetermined position (for example, an initial position) to stop the ascending operation of the linearly movable unit 32. (Step S112 ).
　上記のように、この第１の制御方式においては、タッチスタート方式で初期通電を開始した後、直進可動部３２を上昇移動させる際にトーチ電極１０の先端が被溶接材Ｗから分離するのと同時（時点ｔ２）に初期通電から本通電への切換えを行い、分離のタイミング（ｔ２）からあらかじめ設定された本通電時間ＴＭが経過した時点でアーク溶接を終了する。かかる技法により、熱容量が小さくて微弱なアークでも溶けやすい被溶接材Ｗに対しても適切なアーク溶接を施し、良好な溶接品質を得ることができる。また、アーク這い上がり、アーク横飛び（アークが近傍の他のワークに飛び火する現象）、アーク失火等の溶接不良を効果的に防止することができる。 As described above, in the first control method, after starting the initial energization by the touch start method, the tip of the torch electrode 10 is separated from the workpiece W when the linearly movable portion 32 is moved upward. At the same time (time t 2 ), switching from initial energization to main energization is performed, and arc welding is terminated when a preset main energization time TM has elapsed from the separation timing (t 2 ). By such a technique, it is possible to perform appropriate arc welding even on a workpiece W having a small heat capacity and easily melted even with a weak arc, and to obtain good welding quality. Further, it is possible to effectively prevent welding defects such as arc creeping, arc side jump (a phenomenon in which the arc jumps to other nearby workpieces), arc misfire, and the like.
　この点に関して、一般的なタッチスタート方式は、トーチ電極が被溶接材にタッチした後に、（Ａ１）トーチ電極を被溶接材に接触させた状態（短絡状態）で初期通電を開始する→（Ａ２）トーチの上昇移動を開始する→（Ａ３）トーチ電極が被溶接材から分離する→（Ａ４）微弱なアークが発生する→（Ａ５）初期通電および微弱なアークを維持したままトーチの上昇移動を継続する→（Ａ６）一定の離間距離を確立する→（Ａ７）初期電流を本通電の主電流に切り換える、という一連の工程（Ａ１）～（Ａ７）からなっている。上述した第１の制御方式は、工程（Ａ３）から工程（Ａ４）～（Ａ６）をスキップして工程（Ａ７）に移行するところにその特異な制御思想があり、従来一般のタッチスタート方式とは異なる特殊なタッチスタート方式といえる。 In this regard, in a general touch start method, after the torch electrode touches the material to be welded, (A1) initial energization is started in a state where the torch electrode is in contact with the material to be welded (short circuit state) → (A2 ) Start torch lift → (A3) The torch electrode separates from the work piece → (A4) Weak arc occurs → (A5) Torch lift and move while maintaining initial energization and weak arc Continue → (A6) Establish a certain separation distance → (A7) A series of steps (A1) to (A7) in which the initial current is switched to the main current of main energization. The first control method described above has its unique control concept in that the process (A4) to (A6) are skipped from the process (A3) and the process proceeds to the process (A7). Is a different special touch start method.
　なお、タッチ状態の下で直進可動部３２においてプランジャソレノイド９０を作動させてトーチボディ１２を直進可動部３２のベース部材４０と一体化し、タッチスタートの後にトーチ電極１０を直進可動部３２と一体に上昇移動させることも可能である。しかし、タッチ状態の下でプランジャソレノイド９０のプランジャ９２を用力導入部５８の側面（対向面）に大きな押圧力で当てると、トーチボディ１２、トーチ電極１０等を介して被溶接材Ｗに余計な圧力が加わり、熱容量の小さい微小な被溶接材Ｗに対して望ましくない損傷、変形を与えるおそれがある。さらに、直進可動部３２を上昇移動させた時にトーチ電極１０の先端が被溶接材Ｗから分離したタイミング（ｔ２）を正確に検出することも困難である。 Under the touch state, the plunger solenoid 90 is operated in the linearly movable portion 32 to integrate the torch body 12 with the base member 40 of the linearly movable portion 32, and the torch electrode 10 is integrated with the linearly movable portion 32 after the touch start. It is also possible to move up. However, if the plunger 92 of the plunger solenoid 90 is applied to the side surface (opposed surface) of the utility force introduction portion 58 with a large pressing force under the touched state, it is unnecessary for the work piece W to be welded via the torch body 12 and the torch electrode 10. Pressure may be applied, which may cause undesirable damage and deformation to the minute workpiece W having a small heat capacity. Furthermore, it is difficult to accurately detect the timing (t 2 ) when the tip of the torch electrode 10 is separated from the workpiece W when the linearly movable portion 32 is moved upward.
　この実施形態では、上記のように、タッチ／分離検出部１５が、直進可動部３２に対するトーチ１３の相対的な動きまたは位置関係をバランスアーム５０を介して光学的に監視し、バランスアーム５０が静止状態から時計方向に動き始めて遮光部材Ｆが光学センサ（ＥＤ/ＰＤ）の光ビームＰの光路に入ったタイミングをタッチのタイミング（ｔ１）として検出し、バランスアーム５０が静止状態から反時計方向に動き始めて遮光部材Ｆが光学センサ（ＥＤ/ＰＤ）の光ビームＰの光路から抜けたタイミングを分離のタイミング（ｔ２）として検出するようにしている。つまり、直進可動部３２に対するトーチ１３の相対的位置関係が、タッチのタイミング（ｔ１）が検出されるときと分離のタイミング（ｔ２）が検出されるときとで一致するように設定されている。タッチ／分離検出部１５は、トーチ電極１０の先端から十分離れた（または隔離された）場所に設けられ、アークＡＣの熱をまったく受けずに動作するので、精緻なタイミング検出動作を正確に行うことができる。 In this embodiment, as described above, the touch / separation detection unit 15 optically monitors the relative movement or positional relationship of the torch 13 with respect to the linearly movable unit 32 via the balance arm 50, and the balance arm 50 is The timing when the light shielding member F starts to move clockwise from the stationary state and enters the optical path of the light beam P of the optical sensor (ED / PD) is detected as the touch timing (t 1 ), and the balance arm 50 is counterclockwise from the stationary state. The timing at which the light shielding member F starts to move in the direction and leaves the optical path of the light beam P of the optical sensor (ED / PD) is detected as the separation timing (t 2 ). That is, the relative positional relationship of the torch 13 with respect to the rectilinearly movable portion 32 is set so as to match when the touch timing (t 1 ) is detected and when the separation timing (t 2 ) is detected. Yes. The touch / separation detection unit 15 is provided at a location sufficiently separated (or isolated) from the tip of the torch electrode 10 and operates without receiving any heat from the arc AC, so that precise timing detection operation is accurately performed. be able to.
　この実施形態では、制御部２０が、電圧検出回路３８を介して分離のタイミング（ｔ２）を検出することも可能となっている。タッチスタートの通電中にトーチ電極１０が被溶接材Ｗから分離した時に両者の間にギャップが生じることにより、両者間の印加電圧Ｖがそれまでの零ボルトから溶接電源２２の出力に応じたピーク値まで一定または不定のレートで立ち上がる。このため、電圧Ｖが一定の基準値まで立ち上がった時点を検出する方法によれば、実際の分離のタイミング（ｔ２）から相当遅れたタイミングを検出することになる。この実施形態では、電圧検出回路３８が微分回路を有し、電圧Ｖの立ち上がりの変化を微分することにより、実際の分離のタイミング（ｔ２）を遅延なく検出することができる。 In this embodiment, the control unit 20 can also detect the separation timing (t 2 ) via the voltage detection circuit 38. When the torch electrode 10 is separated from the workpiece W during energization of the touch start, a gap is generated between the two, so that the applied voltage V between the two peaks from the previous zero volt to the output of the welding power source 22. It rises at a constant or indefinite rate up to the value. For this reason, according to the method of detecting the time point when the voltage V rises to a certain reference value, a timing considerably delayed from the actual separation timing (t 2 ) is detected. In this embodiment, the voltage detection circuit 38 includes a differentiating circuit, and the actual separation timing (t 2 ) can be detected without delay by differentiating the rising change of the voltage V.
　第２の制御方式（図３、図４Ｂ）は、上述した第１の制御方式の基本的な制御思想を踏襲しつつ（ステップＳ２０１～Ｓ２１２）、タッチスタート後に直進可動部３２を設定距離ＨＳだけ上昇移動させ（ステップＳ２１０）、つまりトーチ電極１０の先端が被溶接材Ｗから設定離間距離ＨＳだけ離れる位置まで上昇移動させて一時的に停止させ（図３の時点ｔ３）、その停止期間中に本通電時間ＴＭをタイムアップさせる（ステップＳ２１３～Ｓ２１４）。この第２の制御方式は、熱容量の大きい被溶接材に対するＴＩＧ溶接に好適に適用することができる。 The second control method (FIGS. 3 and 4B) follows the basic control concept of the first control method described above (steps S 201 to S 212 ), and sets the rectilinear movable unit 32 to a set distance after the touch start. It is moved up by H S (step S 210 ), that is, moved up to a position where the tip of the torch electrode 10 is separated from the workpiece W by a set separation distance H S and temporarily stopped (time point t 3 in FIG. 3 ). During this stop period, the main energization time TM is increased (steps S213 to S214 ). This second control method can be suitably applied to TIG welding for a material to be welded having a large heat capacity.
　第３の制御方式（図３、図４Ｃ）も、上記第１の制御方式の基本的な制御思想を踏襲しつつ（ステップＳ３０１～Ｓ３０４，Ｓ３０８～Ｓ３１３）、初期通電をタッチのタイミング（ｔ１）から一定期間ＴＦの経過後に開始して分離のタイミング（ｔ２）の直前に限定し（ステップＳ３０５）、初期通電時間（ＴＯ）を可及的に短い時間に設定する（ステップＳ３０６～Ｓ３０７）点に特徴がある。この場合は、初期電流ＩＯの立ち上がりのスロープと本通電の主電流ＩＭの立ち上がりのスロープとを連続させ、通電電流を零アンペアから主電流ＩＭのピーク値まで最短に立ち上げることができる。この場合、主電流ＩＭの立ち上がりにアップスロープ制御をかけてよく、立ち下がりにダウンスロープ制御も好適に用いてよい。この第２の制御方式は、熱容量のきわめて小さい被溶接材に対するＴＩＧ溶接に好適に適用することができる。 The third control method (FIGS. 3 and 4C) also follows the basic control concept of the first control method (steps S 301 to S 304 , S 308 to S 313 ), and the initial energization is performed by touching. It starts after the elapse of a certain period TF from the timing (t 1 ) and is limited to immediately before the separation timing (t 2 ) (step S 305 ), and the initial energization time (T O ) is set as short as possible. (Steps S 306 to S 307 ) are characteristic. In this case, the rising slope of the initial current IO and the rising slope of the main current I M for main energization are made continuous so that the energization current can be raised from the zero ampere to the peak value of the main current I M in the shortest time. . In this case, well over the rising up slope control of the main current I M, even down slope control the falling be suitably used. This second control method can be suitably applied to TIG welding for a material to be welded having a very small heat capacity.
　図５に、従来の制御方式に相当する比較例のシーケンスを示す。図示のように、比較例の制御方式は、タッチスタート方式においてトーチ電極の先端が被溶接材から分離した後しばらくしてから、典型的には図５に示すように設定離間位置まで引き上げてから通電電流を初期電流から本通電の主電流に切り換え、トーチ電極を設定離間位置に静止させた状態での通電時間（本通電時間）を管理するものである。しかしながら、このような制御方式によれば、被溶接材の熱容量が小さい場合には、本通電に移行する前に初期電流のアークによって被溶接材Ｗが不所望かつ不定に溶けてしまい、結果的にも所期の溶接品質が得られない。 FIG. 5 shows a sequence of a comparative example corresponding to the conventional control method. As shown in the figure, in the control method of the comparative example, after the tip of the torch electrode is separated from the material to be welded in the touch start method, typically after being pulled up to the set separation position as shown in FIG. The energizing current is switched from the initial current to the main current for main energization, and the energization time (main energization time) in a state where the torch electrode is stationary at the set separation position is managed. However, according to such a control method, when the heat capacity of the material to be welded is small, the material W to be welded melts undesirably and indefinitely by the arc of the initial current before shifting to the main energization. However, the desired welding quality cannot be obtained.
　さらには、この実施形態と比較例とは、図９Ａおよび図９Ｂに示すように、アーク這い上がり現象の有無に関して作用上の顕著な相違がある。比較例の制御方式によれば、図９Ａに示すように、トーチ電極の先端が被溶接材から分離して離間する際に被溶接材からトーチ電極の先端に向かって形成される初期電流によるアークがトーチ電極の柱状胴部の側面まで這い上がる現象が生じやすい。このようなアーク這い上がり現象は、被溶接材に対するアークの集中性および安定性を大きく低下させる。これに対して、この実施形態（たとえば上記第１の制御方式）によれば、アークが最初から本通電の主電流の下で生成されるため、図９Ｂに示すように、アークの這い上がりが発生せず、トーチ電極の先端と被溶接材の端部との間に集中性のよいアークが安定に生じる。
［他の実施形態又は変形例］ Furthermore, as shown in FIG. 9A and FIG. 9B, this embodiment and the comparative example have a remarkable difference in operation with respect to the presence or absence of the arc climbing phenomenon. According to the control method of the comparative example, as shown in FIG. 9A, when the tip of the torch electrode is separated from the material to be welded and separated, the arc by the initial current formed from the material to be welded toward the tip of the torch electrode Tends to creep up to the side of the columnar body of the torch electrode. Such an arc creeping phenomenon greatly reduces the concentration and stability of the arc with respect to the workpiece. On the other hand, according to this embodiment (for example, the first control method described above), since the arc is generated from the beginning under the main current of main energization, as shown in FIG. It does not occur, and a highly concentrated arc is stably generated between the tip of the torch electrode and the end of the workpiece.
[Other Embodiments or Modifications]
　以上、本発明の好適な実施形態について説明したが、上述した実施形態は本発明を限定するものではない。当業者にあっては、具体的な実施態様において本発明の技術思想および技術範囲から逸脱せずに種々の変形・変更を加えることが可能である。 The preferred embodiments of the present invention have been described above, but the above-described embodiments do not limit the present invention. Those skilled in the art can make various modifications and changes in specific embodiments without departing from the technical idea and technical scope of the present invention.
　たとえば、微小サイズの被溶接材Ｗ（Ｗ１，Ｗ２）に対しては、図６の（ａ）に示すようなマイナス（－）形状または長方形状の先端面を有するトーチ電極１０や、図６の（ｂ）に示すようなフラット状の先端面を有するトーチ電極を好適に使用することができる。これらの場合、トーチ電極１０の中心軸が被溶接材Ｗの中心部から少し横にずれても、トーチ電極１０の先端面が被溶接材Ｗの頂面に当接するので、確実に被溶接材Ｗ（Ｗ１，Ｗ２）の中心部付近にアークを集中させることができる。また、タッチスタート方式において、分離のタイミングを検出するのと同時または即時に電流を本通電に切り替えることでトーチ電極への側面へのアークの這い上がりを防ぎ、確実に被溶接材Ｗ（Ｗ１，Ｗ２）の中心部付近にアークを集中させることができる。 For example, for a to-be-welded material W (W 1 , W 2 ) having a small size, a torch electrode 10 having a minus (−) shape or a rectangular tip surface as shown in FIG. A torch electrode having a flat tip surface as shown in 6 (b) can be preferably used. In these cases, even if the central axis of the torch electrode 10 is slightly deviated from the center of the workpiece W, the tip surface of the torch electrode 10 abuts the top surface of the workpiece W, so that the workpiece is reliably connected. The arc can be concentrated near the center of W (W 1 , W 2 ). In the touch start method, the current is switched to the main energization at the same time or immediately when the separation timing is detected to prevent the arc from rising to the side surface of the torch electrode, and the work piece W (W 1 , W 2 ), the arc can be concentrated near the center.
　図７に、上記した実施形態において直進可動部（溶接ヘッド）３２上に設けられる荷重バランス機構およびタッチ／分離検出部１５の別の実施例を示す。図中、図２Ａ～図２Ｆのものと同様の構成または機能を有する部分には、同一の参照符号を用いている。なお、溶接電流供給系およびガス供給系は図示省略している。 FIG. 7 shows another example of the load balance mechanism and the touch / separation detection unit 15 provided on the rectilinearly movable portion (welding head) 32 in the above-described embodiment. In the figure, the same reference numerals are used for portions having the same configuration or function as those in FIGS. 2A to 2F. The welding current supply system and the gas supply system are not shown.
　この実施例における荷重バランス機構は、直進可動部３２の本体１１０とトーチボディ１２に固定された水平の連結棒１１２との間に圧縮コイルばね１１４と引張コイルばね１１６とを並列に配置する。ここで、圧縮コイルばね１１４のばね荷重は、棒ねじ１１８およびナット１２０を含む第１のトーチ荷重調整部１２２によって調整可能であり、引張コイルばね１１６のばね荷重は棒ねじ１２４およびナット１２６を含む第２のトーチ荷重調整部１２８によって調整可能である。 In the load balance mechanism in this embodiment, the compression coil spring 114 and the tension coil spring 116 are arranged in parallel between the main body 110 of the linearly movable portion 32 and the horizontal connecting rod 112 fixed to the torch body 12. Here, the spring load of the compression coil spring 114 can be adjusted by the first torch load adjusting unit 122 including the bar screw 118 and the nut 120, and the spring load of the tension coil spring 116 includes the bar screw 124 and the nut 126. Adjustment is possible by the second torch load adjusting unit 128.
　トーチボディ１２には、連結棒１１２等の付属物も含めたトーチ１３全体の重量（自重）Ｌ１３と、圧縮コイルばね１１４のばね荷重Ｌ１１４とが足し合わさったＺ方向の下向きの荷重が加わる一方で、引張コイルばね１１６のばね荷重Ｌ１１６がＺ方向の上向きに加わる。Ｚ方向の下向きの荷重を正方向とし、トーチボディ１２に加わる全合成荷重をＴＬとすると、ＴＬ＝Ｌ１３＋Ｌ１１４－Ｌ１１６である。ここで、Ｌ１３は略一定であるから、上記のように第１および第２のトーチ荷重調整部１２２，１２８によりＬ１１４，Ｌ１１６を可変調整することにより、被溶接材Ｗの特性に合わせて全合成荷重ＴＬを任意に調整することができる。 A downward load in the Z direction is applied to the torch body 12, which is the sum of the weight (self-weight) L 13 of the entire torch 13 including accessories such as the connecting rod 112 and the spring load L 114 of the compression coil spring 114. On the other hand, the spring load L 116 of the tension coil spring 116 is applied upward in the Z direction. Assuming that the downward load in the Z direction is the positive direction and the total combined load applied to the torch body 12 is TL, TL = L 13 + L 114 −L 116 . Here, L 13 is because it is substantially constant, by the L 114, L 116 variably adjusted by the first and second torch load adjusting portion 122, 128 as described above, according to the characteristics of workpieces W Thus, the total combined load TL can be arbitrarily adjusted.
　この実施例におけるタッチ／分離検出部１５は、連結棒１１２と反対側（図の左側）で水平に延びる横棒１３０と本体１１０との間に設けられる。より詳細には、横棒１３０の先端部には、鉛直上方に延びる遮光部材Ｆが取り付けられている。この遮光部材Ｆの周囲には、本体１１０に固定された発光素子ＥＤおよび受光素子ＰＤが同一の高さ位置で対向して配置されている。 The touch / separation detection unit 15 in this embodiment is provided between the horizontal bar 130 and the main body 110 that extend horizontally on the opposite side (left side in the figure) to the connecting bar 112. More specifically, a light shielding member F extending vertically upward is attached to the tip of the horizontal bar 130. Around the light shielding member F, a light emitting element ED and a light receiving element PD fixed to the main body 110 are arranged to face each other at the same height position.
　かかる構成においては、トーチ電極１０の先端が被溶接材（図示せず）にタッチした時に、被溶接材側からの反作用によってトーチ１３（トーチ電極１０およびトーチボディ１２）が直進可動部３２の本体１１０に対して相対的に上方に移動して、図７に示すように遮光部材Ｆが発光素子ＥＤからの光ビームＰを遮断し、受光素子ＰＤの出力信号がそれまでのＨレベルからＬレベルに変わる。その後、トーチ電極１０の先端が被溶接材から分離すると、被溶接材側からの反作用が解除されることによって、トーチ１３が直進可動部３２の本体１１０に対して相対的に下方に移動して、遮光部材Ｆが光ビームＰの光路から下方に退避し、受光素子ＰＤの出力信号がそれまでのＬレベルからＨレベルに変わる。 In such a configuration, when the tip of the torch electrode 10 touches the workpiece (not shown), the torch 13 (the torch electrode 10 and the torch body 12) is the main body of the rectilinearly movable portion 32 due to the reaction from the workpiece side. As shown in FIG. 7, the light shielding member F blocks the light beam P from the light emitting element ED, and the output signal of the light receiving element PD changes from the previous H level to the L level. Changes to. Thereafter, when the tip of the torch electrode 10 is separated from the material to be welded, the reaction from the material to be welded is released, so that the torch 13 moves downward relative to the main body 110 of the linearly movable portion 32. Then, the light shielding member F is retracted downward from the optical path of the light beam P, and the output signal of the light receiving element PD changes from the previous L level to the H level.
　このように、この実施例におけるタッチ／分離検出部１５は、直進可動部３２の本体１１０とこれに圧縮コイルばね１１４および引張コイルばね１１６を介して結合されているトーチ１３との間の相対的な動きまたは位置関係を光学的に監視して、タッチスタート方式におけるタッチのタイミングおよび分離のタイミンングを検出するようにしている。 In this way, the touch / separation detection unit 15 in this embodiment is a relative between the main body 110 of the linearly movable unit 32 and the torch 13 coupled to the main body 110 via the compression coil spring 114 and the tension coil spring 116. The movement or positional relationship is optically monitored to detect touch timing and separation timing in the touch start method.
　なお、タッチ／分離検出部１５において、タッチのタイミングを検出するための光学センサと分離のタイミングを検出するための光学センサとを別個独立に設ける構成も可能である。 In the touch / separation detection unit 15, an optical sensor for detecting the touch timing and an optical sensor for detecting the separation timing may be separately provided.
　図８に、タッチ／分離検出部１５に関する更に別の実施例を示す。この実施例は、荷重バランス機構にバランスアーム５０およびバランスウェイト８０を用いる上述の実施例（図２Ａ～図２Ｆ）において、タッチ／分離検出部１５の遮光部材Ｆをアーム状の支持部材１４０を介してトーチボディ１２に取り付けるとともに、遮光部材Ｆの直下でベース部材４０（水平平板部４０ｂ）上に光学センサ（発光素子ＥＤ／受光素子ＰＤ）を配置する。 FIG. 8 shows still another embodiment related to the touch / separation detection unit 15. In this embodiment, the light shielding member F of the touch / separation detection unit 15 is interposed via the arm-shaped support member 140 in the above-described embodiment (FIGS. 2A to 2F) in which the balance arm 50 and the balance weight 80 are used for the load balance mechanism. The optical sensor (light emitting element ED / light receiving element PD) is disposed on the base member 40 (horizontal flat plate portion 40b) immediately below the light shielding member F.
　この場合、タッチスタートにおいて、トーチ電極１０の先端が下降して被溶接材Ｗに当接するまでは、遮光部材Ｆの先端が発光素子ＥＤと受光素子ＰＤと間で水平に伝搬する光ビームＰより高い位置にあり、受光素子ＰＤの出力信号はＨレベルになっている。そして、トーチ電極１０の先端が被溶接材Ｗに当接すると、これと略同時に光ビームＰが遮光部材Ｆの先端によって遮断または遮光され、受光素子ＰＤの出力信号がＨレベルからＬレベルに変わる。その後、初期通電が終了して直進可動部３２の上昇によりトーチ電極１０の先端が被溶接材から分離すると、これと略同時に遮光部材Ｆの先端が光ビームＰの光路から上方に退避し、受光素子ＰＤの出力信号がＬレベルからＨレベルに変わる。 In this case, at the touch start, until the tip of the torch electrode 10 descends and comes into contact with the workpiece W, the tip of the light shielding member F is from the light beam P that propagates horizontally between the light emitting element ED and the light receiving element PD. The output signal of the light receiving element PD is at the H level. When the tip of the torch electrode 10 comes into contact with the workpiece W, the light beam P is blocked or shielded by the tip of the light shielding member F substantially simultaneously with this, and the output signal of the light receiving element PD changes from H level to L level. . Thereafter, when the initial energization is completed and the tip of the torch electrode 10 is separated from the material to be welded by the ascending of the linearly movable portion 32, the tip of the light shielding member F is retracted upward from the optical path of the light beam P almost simultaneously with this. The output signal of the element PD changes from L level to H level.
　また、図示省略するが、異なる高さ位置に２組の光センサ（ＥＤ１／ＰＤ１），（ＥＤ２／ＰＤ２）を配置し、配置（検出）位置が高い方の第１の光センサ（ＥＤ１／ＰＤ１）によってタッチと分離のタイミングを検出し、配置（検出）位置が低い方の第２の光センサ（ＥＤ２／ＰＤ２）によって初期通電開始のタイミングを取得する構成とすることも可能である。この方式は、トーチ電極１０の先端が被溶接材Ｗに当接した後もさらにトーチボディ１２を下降させて被溶接材Ｗに十分大きな加圧力を加えて初期通電を行う場合に好適である。 Although not shown in the drawing, two sets of photosensors (ED 1 / PD 1 ) and (ED 2 / PD 2 ) are arranged at different height positions, and the first photosensor having a higher arrangement (detection) position. The touch and separation timing is detected by (ED 1 / PD 1 ), and the initial energization start timing is acquired by the second photosensor (ED 2 / PD 2 ) having the lower arrangement (detection) position. It is also possible. This method is suitable when initial energization is performed by further lowering the torch body 12 and applying a sufficiently large pressing force to the workpiece W even after the tip of the torch electrode 10 contacts the workpiece W.
　　１０　　トーチ電極
　　１２　　トーチボディ
　　１５　　タッチ／分離検出部
　　２０　　制御部
　　２２　　溶接電源
　　１８　　直進移動機構
　　３２　　直進可動部
　　３４　　直進駆動部
　　３８　　電圧検出回路
　　　Ｗ　　被溶接材 DESCRIPTION OF SYMBOLS 10 Torch electrode 12 Torch body 15 Touch / separation detection part 20 Control part 22 Welding power supply 18 Straight movement mechanism 32 Straight movement part 34 Straight drive part 38 Voltage detection circuit W Welded material

Claims (15)

  1. 　トーチ電極を支持する直進可動部を下降方向に駆動して、前記トーチ電極を被溶接材に向けて下降移動させる第１の工程と、
    　前記トーチ電極の先端が前記被溶接材に接触した直後に前記直進可動部の駆動を停止する第２の工程と、
    　前記トーチ電極の先端が前記被溶接材に接触している状態の下で、前記トーチ電極および前記被溶接材を含む閉回路に初期通電のための第１の電流を流す第３の工程と、
    　前記トーチ電極を上昇移動させるために前記直進可動部を上昇方向に駆動する第４の工程と、
    　前記トーチ電極の先端が前記被溶接材から離れる分離のタイミングを検出する第５の工程と、
    　前記分離のタイミングを検出するのと同時または即時に前記閉回路に流す電流を前記第１の電流から本通電のための第２の電流に切り換える第６の工程と
    　を有するＴＩＧ溶接方法。     A first step of driving the linearly movable portion supporting the torch electrode in the downward direction to move the torch electrode downward toward the workpiece; and
    A second step of stopping the drive of the linearly movable portion immediately after the tip of the torch electrode contacts the material to be welded;
    A third step of flowing a first current for initial energization to a closed circuit including the torch electrode and the material to be welded under a state in which a tip of the torch electrode is in contact with the material to be welded;
    A fourth step of driving the linearly movable portion in the upward direction to move the torch electrode upward;
    A fifth step of detecting the separation timing at which the tip of the torch electrode separates from the material to be welded;
    And a sixth step of switching the current that flows through the closed circuit from the first current to the second current for main energization simultaneously or immediately with the detection of the separation timing.
  2. 　前記第２の電流を流す通電時間が前記第４の工程中に終了する、請求項１に記載のＴＩＧ溶接方法。 2. The TIG welding method according to claim 1, wherein an energization time for supplying the second current is completed during the fourth step.
  3. 　前記第４の工程において前記トーチ電極の先端が前記被溶接材から設定離間距離だけ離れた設定離間位置で前記直進駆動部の駆動を停止する第７の工程と、
    　前記設定離間位置で前記トーチ電極を一時的に静止させる第８の工程と
    　を有し、
    　前記第２の電流を流す通電時間が前記第８の工程中に終了する、
    　請求項１に記載のＴＩＧ溶接方法。     A seventh step of stopping driving of the rectilinear drive unit at a set separation position in which the tip of the torch electrode is separated from the workpiece by a set separation distance in the fourth step;
    And an eighth step of temporarily stopping the torch electrode at the set separation position,
    The energization time for passing the second current is terminated during the eighth step;
    The TIG welding method according to claim 1.
  4. 　前記第３の工程を第４の工程の開始の直前に開始する、請求項１に記載のＴＩＧ溶接方法。 The TIG welding method according to claim 1, wherein the third step is started immediately before the start of the fourth step.
  5. 　前記第１の電流の立ち上がりのスロープと前記第２の電流の立ち上がりのスロープとを連続させる、請求項４に記載のＴＩＧ溶接方法。 The TIG welding method according to claim 4, wherein the rising slope of the first current and the rising slope of the second current are made continuous.
  6. 　トーチ電極を着脱自在に装着して保持するトーチボディと、
    　前記トーチボディを支持してその軸方向と平行な方向で直進移動可能に設けられる直進可動部と、
    　被溶接材に対して前記トーチ電極を下降移動または上昇移動させるために前記直進可動部を駆動する直進駆動部と、
    　前記トーチ電極と前記被溶接材とを含む閉回路に所定の電流を流すための溶接電源と、
    　前記トーチ電極の先端が前記被溶接材に接触している状態から前記トーチ電極を上昇移動させたときに、前記トーチ電極の先端が前記被溶接材から離れる分離のタイミングを検出して分離タイミング検出信号を発生する分離検出部と、
    　前記直進駆動部および前記溶接電源を制御するための制御部と
    　を有し、
    　前記制御部が、前記トーチ電極の先端が前記被溶接材に接触している状態の下で前記閉回路に初期通電のための第１の電流を流すように前記溶接電源を制御し、
    　前記制御部が、前記初期通電を開始してから所定時間後に、前記トーチ電極の上昇移動を開始するように前記直進駆動部を制御し、
    　前記制御部が、前記分離検出部からの前記分離タイミング検出信号を受け取ると、それと同時または即時に、前記閉回路に流す電流を前記第１の電流から本通電のための第２の電流に切り換えるように前記溶接電源を制御する、
    　ＴＩＧ溶接装置。     A torch body that detachably attaches and holds a torch electrode; and
    A rectilinearly movable portion that supports the torch body and is provided so as to be linearly movable in a direction parallel to the axial direction thereof;
    A rectilinear drive section for driving the rectilinear movable section to move the torch electrode downward or upward relative to the workpiece,
    A welding power source for causing a predetermined current to flow in a closed circuit including the torch electrode and the material to be welded;
    Separation timing detection by detecting the separation timing at which the tip of the torch electrode moves away from the material to be welded when the torch electrode is moved up from the state where the tip of the torch electrode is in contact with the material to be welded A separation detection unit for generating a signal;
    And a controller for controlling the linear drive unit and the welding power source,
    The control unit controls the welding power source to flow a first current for initial energization to the closed circuit under a state in which a tip of the torch electrode is in contact with the workpiece.
    The controller controls the linear drive unit to start the upward movement of the torch electrode after a predetermined time from the start of the initial energization,
    When the control unit receives the separation timing detection signal from the separation detection unit, simultaneously or immediately, the current flowing through the closed circuit is switched from the first current to the second current for main energization. So as to control the welding power source,
    TIG welding equipment.
  7. 　前記直進可動部上で前記トーチボディは外力を受けないときは荷重のバランスがとれた状態で軸方向に移動可能に支持され、
    　前記分離検出部は、前記直進可動部に対する前記トーチボディの相対的な動きまたは位置関係を監視し、前記トーチボディの相対的な下降移動に応じて前記分離のタイミングを検出する、
    　請求項６に記載のＴＩＧ溶接装置。     When the torch body is not subjected to external force on the linearly movable part, it is supported so as to be movable in the axial direction with a load balanced.
    The separation detection unit monitors a relative movement or positional relationship of the torch body with respect to the linearly movable portion, and detects the separation timing according to a relative downward movement of the torch body.
    The TIG welding apparatus according to claim 6.
  8. 　前記分離検出部は、前記トーチ電極と前記被溶接材との間の印加電圧を監視し、前記印加電圧が零ボルトからピーク値に向かって立ち上がる時の立ち上がりエッジを前記分離のタイミングとして検出する電圧検出回路を有する、請求項６に記載のＴＩＧ溶接装置。 The separation detection unit monitors an applied voltage between the torch electrode and the workpiece, and detects a rising edge when the applied voltage rises from zero volts toward a peak value as the separation timing. The TIG welding apparatus according to claim 6, comprising a detection circuit.
  9. 　前記電圧検出回路は微分回路を有する、請求項８に記載のＴＩＧ溶接装置。 The TIG welding apparatus according to claim 8, wherein the voltage detection circuit has a differentiation circuit.
  10. 　前記トーチ電極の下降移動において前記トーチ電極の先端が前記被溶接材に接触するタッチのタイミングを検出してタッチタイミング検出信号を発生するタッチ検出部が備えられ、
    　前記制御部は、前記タッチ検出部からの前記タッチタイミング検出信号を受け取ると、直ちにまたは所定時間後に前記初期通電を開始するように前記溶接電源を制御する、
    　請求項６に記載のＴＩＧ溶接装置。     A touch detection unit for detecting a touch timing when a tip of the torch electrode touches the workpiece to be welded in a downward movement of the torch electrode and generating a touch timing detection signal;
    The control unit, when receiving the touch timing detection signal from the touch detection unit, controls the welding power source to start the initial energization immediately or after a predetermined time,
    The TIG welding apparatus according to claim 6.
  11. 　前記直進可動部上で前記トーチボディは外力を受けないときは荷重のバランスがとれた状態で軸方向に移動可能に支持され、
    　前記タッチ検出部は、前記直進可動部に対する前記トーチボディの相対的な動きまたは位置関係を監視し、前記トーチボディの相対的な上昇移動に応じて前記タッチのタイミングを検出する、
    　請求項１０に記載のＴＩＧ溶接装置。     When the torch body is not subjected to external force on the linearly movable part, it is supported so as to be movable in the axial direction with a load balanced.
    The touch detection unit monitors a relative movement or positional relationship of the torch body with respect to the rectilinear movable unit, and detects a timing of the touch according to a relative upward movement of the torch body.
    The TIG welding apparatus according to claim 10.
  12. 　トーチ電極を着脱自在に装着して保持するトーチボディと、
    　前記トーチボディを支持してその軸方向と平行な方向で直進移動可能に設けられる直進可動部と、
    　被溶接材に対して前記トーチ電極を下降移動または上昇移動させるために前記直進可動部を駆動する直進駆動部と、
    　前記トーチ電極と前記被溶接材とを含む閉回路に所定の電流を流すための溶接電源と、
    　前記トーチ電極の下降移動において前記トーチ電極の先端が前記被溶接材に接触するタッチのタイミングを前記トーチ電極の先端から離れた場所で検出してタッチタイミング検出信号を発生するタッチ検出部と、
    　前記トーチ電極の先端が前記被溶接材に接触している状態から前記トーチ電極を上昇移動させたときに、前記トーチ電極の先端が前記被溶接材から離れる分離のタイミングを前記トーチ電極の先端から離れた場所で検出して分離タイミング検出信号を発生する分離検出部と、
    　前記直進駆動部および前記溶接電源を制御するための制御部と
    　を有し、
    　前記制御部が、前記タッチ検出部からの前記タッチタイミング検出信号を受け取ると、直ちにまたは所定時間後に前記初期通電を開始するように前記溶接電源を制御し、
    　前記制御部が、前記トーチ電極の先端が前記被溶接材に接触している状態の下で前記閉回路に初期通電のための第１の電流を流すように前記溶接電源を制御し、
    　前記制御部が、前記初期通電を開始してから所定時間後に、前記トーチ電極の上昇移動を開始するように前記直進駆動部を制御し、
    　前記制御部が、前記分離検出部からの前記分離タイミング検出信号を受け取ると、それと同時または即時に、前記閉回路に流す電流を前記第１の電流から本通電のための第２の電流に切り換えるように前記溶接電源を制御する、
    　ＴＩＧ溶接装置。     A torch body that detachably attaches and holds a torch electrode; and
    A rectilinearly movable portion that supports the torch body and is provided so as to be linearly movable in a direction parallel to the axial direction thereof;
    A rectilinear drive section for driving the rectilinear movable section to move the torch electrode downward or upward relative to the workpiece,
    A welding power source for causing a predetermined current to flow in a closed circuit including the torch electrode and the material to be welded;
    A touch detection unit that detects a touch timing at which the tip of the torch electrode contacts the material to be welded in a downward movement of the torch electrode at a location away from the tip of the torch electrode, and generates a touch timing detection signal;
    When the torch electrode is moved upward from a state in which the tip of the torch electrode is in contact with the workpiece, the separation timing at which the tip of the torch electrode is separated from the workpiece is separated from the tip of the torch electrode. A separation detection unit for detecting a separation timing detection signal at a remote location;
    And a controller for controlling the linear drive unit and the welding power source,
    When the control unit receives the touch timing detection signal from the touch detection unit, the welding power source is controlled to start the initial energization immediately or after a predetermined time,
    The control unit controls the welding power source to flow a first current for initial energization to the closed circuit under a state in which a tip of the torch electrode is in contact with the workpiece.
    The controller controls the linear drive unit to start the upward movement of the torch electrode after a predetermined time from the start of the initial energization,
    When the control unit receives the separation timing detection signal from the separation detection unit, simultaneously or immediately, the current flowing through the closed circuit is switched from the first current to the second current for main energization. So as to control the welding power source,
    TIG welding equipment.
  13. 　前記直進可動部上で前記トーチボディは外力を受けないときは荷重のバランスがとれた状態で軸方向に移動可能に支持され、
    　前記タッチ検出部は、前記直進可動部に対する前記トーチボディの相対的な動きまたは位置関係を監視し、前記トーチボディの相対的な上昇移動に応じて前記タッチのタイミングを検出し、
    　前記分離検出部は、前記直進可動部に対する前記トーチボディの相対的な動きまたは位置関係を監視し、前記トーチボディの相対的な下降移動に応じて前記タッチのタイミングを検出する、
    　請求項１２に記載のＴＩＧ溶接装置。     When the torch body is not subjected to external force on the linearly movable part, it is supported so as to be movable in the axial direction with a load balanced.
    The touch detection unit monitors a relative movement or positional relationship of the torch body with respect to the rectilinear movable unit, detects a timing of the touch according to a relative upward movement of the torch body,
    The separation detection unit monitors a relative movement or positional relationship of the torch body with respect to the rectilinear movable unit, and detects a timing of the touch according to a relative downward movement of the torch body;
    The TIG welding apparatus according to claim 12.
  14. 　前記タッチ検出部および前記分離検出部は、前記直進可動部に対する前記トーチボディの相対的な動きまたは位置関係を監視するために共通の光センサを有する、請求項１３に記載のＴＩＧ溶接装置。 The TIG welding apparatus according to claim 13, wherein the touch detection unit and the separation detection unit have a common optical sensor for monitoring a relative movement or positional relationship of the torch body with respect to the rectilinear movable unit.
  15. 　前記トーチ電極は、マイナス（－）形状、長方形状、フラット形状のいずれかの先端面を有する、請求項６または請求項１２に記載のＴＩＧ溶接装置。 The TIG welding apparatus according to claim 6 or 12, wherein the torch electrode has a tip surface of any one of a minus (-) shape, a rectangular shape, and a flat shape.
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