CN118232753A - Motor control device and molding machine - Google Patents

Abstract

The present invention relates to a motor control device that suppresses degradation of any one or more of a three-phase motor and a control unit that controls the three-phase motor. The motor control device according to one embodiment includes a control unit configured to acquire a current value flowing between a power supply and a three-phase motor from a detection unit, and to control a current output from the power supply to the three-phase motor so as to include a current flowing due to an induced electromotive force based on a change in a magnetic field between a rotor and a stator of the three-phase motor generated by rotation of the three-phase motor when stop control is performed on the rotating three-phase motor, and the current value detected by the detection unit is approximately '0' ampere.

Description

Motor control device and molding machine

Technical Field

The present application claims priority based on japanese patent application No. 2022-203456 filed on day 20 of 12 in 2022. The entire contents of this japanese application are incorporated by reference into the present specification.

The present invention relates to a motor control device and a molding machine.

Background

Conventionally, as a driving source for various devices, a three-phase motor has been used. When it is difficult to grasp the magnetic pole position of the rotor in the three-phase motor at the time of stopping the three-phase motor, the rotor is stopped by flowing a direct current in the stationary phase of the stator coil. In the stop control, during the period when the rotational speed of the rotor is reduced, there is a possibility that the increase and decrease in the rotational speed of the rotor are alternately generated by the magnetic field generated in the stator.

In recent years, various techniques have been proposed for controlling a motor. For example, in the technique described in patent document 1, there is proposed a technique for controlling dc power supplied to a servo amplifier in accordance with a process of injection molding. Patent document 1 proposes a technique in which, in a power storage circuit that supplies power to a servo amplifier, electromagnetic energy of surplus power stored in a coil of the power storage circuit is consumed to gradually attenuate a current flowing through the coil to zero.

Patent document 1: japanese patent application laid-open No. 2010-58317

The technique described in patent document 1 is a technique for performing power control in a power storage circuit that supplies power to a servo amplifier, and is not a technique for adjusting a direct current flowing through a stator coil when a three-phase motor is stopped. That is, in the technique described in patent document 1, it is difficult to adjust the current flowing through the stator coil so as to suppress the increase and decrease in the rotational speed of the rotor from occurring alternately when the rotor is stopped.

Disclosure of Invention

One embodiment of the present invention provides a technique for suppressing degradation of a three-phase motor by adjusting current flowing through the three-phase motor when the three-phase motor is stopped.

The motor control device according to one aspect of the present invention includes a control unit configured to acquire a current value flowing between a power supply and a three-phase motor from a detection unit, and to control a current output from the power supply to the three-phase motor so as to include a current flowing due to an induced electromotive force based on a change in a magnetic field between a rotor and a stator of the three-phase motor caused by rotation of the three-phase motor when stopping control of the rotating three-phase motor, and the current value detected by the detection unit is approximately '0' ampere.

ADVANTAGEOUS EFFECTS OF INVENTION

According to one aspect of the present invention, there is provided a technique for controlling degradation of at least one of a three-phase motor and a control unit (e.g., a motor driver) that controls the three-phase motor by adjusting a current flowing through the three-phase motor when the three-phase motor is stopped.

Drawings

Fig. 1 is a diagram showing a state at the end of mold opening of an injection molding machine according to one embodiment.

Fig. 2 is a diagram showing a state at the time of mold closing of the injection molding machine according to the embodiment.

Fig. 3 is a diagram showing a connection structure of a cylinder, a metering motor, and an injection motor provided in the injection device according to embodiment 1 from above.

Fig. 4 is a diagram showing constituent elements for controlling the control device and the injection motor of the injection molding machine according to embodiment 1, with functional blocks.

Fig. 5 is a diagram showing a change in rotational speed when an operation command indicating an abnormal stop is received in a conventional injection molding machine.

Fig. 6 is a diagram showing a change in rotational speed when an operation command indicating an abnormal stop is received in the injection molding machine according to embodiment 1.

Description of symbols

10-Injection molding machine, 300-injection device, 301-slide base, 302-fixed plate, 303-movable plate, 310-cylinder, 350-injection motor, 351-injection motor encoder, 352-motor driver, 353-three-phase inverter, 354-1 st current sensor, 355-2 nd current sensor, 356-power supply, 357-inverter, 700-control device, 701-CPU, 711-acquisition part, 712-determination part, 713-motor control part.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are not limited to the embodiments of the invention, but are merely examples, and all the features and combinations described in the embodiments are not necessarily essential to the invention. In the drawings, the same or corresponding structures may be denoted by the same or corresponding symbols, and description thereof may be omitted.

Fig. 1 is a diagram showing a state at the end of mold opening of the injection molding machine according to embodiment 1. Fig. 2 is a diagram showing a state at the time of mold closing of the injection molding machine according to embodiment 1. In the present specification, the X-axis direction, the Y-axis direction, and the Z-axis direction are directions perpendicular to each other. The X-axis direction and the Y-axis direction represent horizontal directions, and the Z-axis direction represents vertical directions. When the mold clamping device 100 is horizontal, the X-axis direction is the mold opening/closing direction, and the Y-axis direction is the width direction of the injection molding machine 10. The negative side in the Y-axis direction is referred to as the operation side, and the positive side in the Y-axis direction is referred to as the opposite side to the operation side.

As shown in fig. 1 to 2, the injection molding machine 10 includes: a mold clamping device 100 for opening and closing the mold device 800; an ejector 200 for ejecting the molded article molded by the mold device 800; an injection device 300 injecting a molding material to the mold device 800; a moving device 400 for advancing and retreating the injection device 300 with respect to the mold device 800; a control device 700 for controlling the respective constituent elements of the injection molding machine 10; and a frame 900 for supporting the components of the injection molding machine 10. The frame 900 includes a clamping device frame 910 that supports the clamping device 100 and an injection device frame 920 that supports the injection device 300. The mold clamping device frame 910 and the injection device frame 920 are respectively provided on the floor 2 via horizontal adjustment casters 930. The control device 700 is disposed in the internal space of the injection device frame 920. The following describes the respective constituent elements of the injection molding machine 10.

(Mold clamping device)

In the description of the mold clamping apparatus 100, the moving direction (for example, the positive X-axis direction) of the movable platen 120 during mold closing is set to the front, and the moving direction (for example, the negative X-axis direction) of the movable platen 120 during mold opening is set to the rear.

The mold clamping device 100 performs mold closing, pressure increasing, mold clamping, pressure releasing, and mold opening of the mold device 800. The mold apparatus 800 includes a stationary mold 810 and a movable mold 820. The mold clamping device 100 is, for example, horizontal, and the mold opening/closing direction is horizontal. The mold clamping device 100 includes a fixed platen 110 to which a fixed mold 810 is attached, a movable platen 120 to which a movable mold 820 is attached, and a moving mechanism 102 that moves the movable platen 120 relative to the fixed platen 110 in a mold opening/closing direction.

The stationary platen 110 is fixed relative to the clamp frame 910. A stationary mold 810 is mounted on a surface of the stationary platen 110 opposite to the movable platen 120.

The movable platen 120 is disposed so as to be movable in the mold opening/closing direction with respect to the mold clamping device frame 910. A guide 101 for guiding the movable platen 120 is laid on the mold clamping device frame 910. The movable mold 820 is mounted on a surface of the movable platen 120 facing the fixed platen 110.

The moving mechanism 102 performs mold closing, pressure increasing, mold closing, pressure releasing, and mold opening of the mold apparatus 800 by advancing and retracting the movable platen 120 relative to the fixed platen 110. The moving mechanism 102 includes a toggle base 130 disposed at a distance from the fixed platen 110, a link 140 connecting the fixed platen 110 and the toggle base 130, a toggle mechanism 150 moving the movable platen 120 relative to the toggle base 130 in the mold opening/closing direction, a mold clamping motor 160 operating the toggle mechanism 150, a motion conversion mechanism 170 converting the rotational motion of the mold clamping motor 160 into a linear motion, and a mold thickness adjustment mechanism 180 adjusting the distance between the fixed platen 110 and the toggle base 130.

The toggle seat 130 is disposed at a distance from the fixed platen 110, and is mounted on the clamping device frame 910 so as to be movable in the mold opening/closing direction. The toggle mount 130 may be configured to be movable along a guide provided on the clamp frame 910. The guide of the toggle seat 130 may be common to the guide 101 of the movable platen 120.

In the present embodiment, the stationary platen 110 is fixed to the clamping device frame 910, and the toggle mount 130 is disposed so as to be movable in the mold opening and closing direction with respect to the clamping device frame 910, but the toggle mount 130 may be fixed to the clamping device frame 910, and the stationary platen 110 may be disposed so as to be movable in the mold opening and closing direction with respect to the clamping device frame 910.

The connecting rod 140 connects the fixed platen 110 and the toggle base 130 with a space L therebetween in the mold opening and closing direction. Multiple (e.g., 4) connecting rods 140 may be used. The plurality of tie bars 140 are arranged parallel to the mold opening and closing direction and extend according to the mold clamping force. A link strain detector 141 detecting strain of the link 140 may be provided on at least 1 link 140. The link strain detector 141 transmits a signal indicating the detection result to the control device 700. The detection result of the tie bar strain detector 141 is used for detection of the clamping force or the like.

In the present embodiment, the tie bar strain detector 141 is used as a mold clamping force detector for detecting a mold clamping force, but the present invention is not limited thereto. The mold clamping force detector is not limited to the strain gauge type, but may be a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, or the like, and the mounting position thereof is not limited to the tie bar 140.

The toggle mechanism 150 is disposed between the movable platen 120 and the toggle base 130, and moves the movable platen 120 with respect to the toggle base 130 in the mold opening and closing direction. The toggle mechanism 150 has a crosshead 151 that moves in the mold opening and closing direction, and a pair of link groups that are bent and extended by the movement of the crosshead 151. The pair of link groups includes a 1 st link 152 and a 2 nd link 153, which are connected to each other by a pin or the like so as to be freely bendable. The 1 st link 152 is attached to the movable platen 120 by a pin or the like so as to be swingable. The 2 nd link 153 is attached to the toggle base 130 by a pin or the like so as to be swingable. The 2 nd link 153 is attached to the crosshead 151 via the 3 rd link 154. When the crosshead 151 is advanced and retracted relative to the toggle mount 130, the 1 st link 152 and the 2 nd link 153 are extended and retracted to advance and retract the movable platen 120 relative to the toggle mount 130.

The structure of the toggle mechanism 150 is not limited to the structure shown in fig. 1 and 2. For example, in fig. 1 and 2, the number of nodes of each link group is 5, but may be 4, or one end of the 3 rd link 154 may be connected to the node of the 1 st link 152 and the 2 nd link 153.

The clamp motor 160 is mounted to the toggle mount 130 and operates the toggle mechanism 150. The clamp motor 160 advances and retreats the crosshead 151 with respect to the toggle mount 130, and stretches the 1 st link 152 and the 2 nd link 153 to advance and retreat the movable platen 120 with respect to the toggle mount 130. The mold clamping motor 160 is directly connected to the motion conversion mechanism 170, but may be connected to the motion conversion mechanism 170 via a belt, pulley, or the like.

The motion conversion mechanism 170 converts the rotational motion of the clamp motor 160 into a linear motion of the crosshead 151. The motion conversion mechanism 170 includes a screw shaft and a screw nut screwed with the screw shaft. Balls or rollers may be interposed between the screw shaft and the screw nut.

The mold clamping device 100 performs a mold closing process, a pressure increasing process, a mold clamping process, a pressure releasing process, a mold opening process, and the like under the control of the control device 700.

In the mold closing step, the movable platen 120 is advanced by driving the mold clamping motor 160 to advance the crosshead 151 to the mold closing end position at a set movement speed so that the movable mold 820 is brought into contact with the fixed mold 810. For example, the position and the moving speed of the crosshead 151 are detected using a clamp motor encoder 161 or the like. The clamp motor encoder 161 detects the rotation of the clamp motor 160, and transmits a signal indicating the detection result to the control device 700.

The crosshead position detector for detecting the position of the crosshead 151 and the crosshead moving speed detector for detecting the moving speed of the crosshead 151 are not limited to the clamp motor encoder 161, and a conventional detector may be used. The movable platen position detector for detecting the position of the movable platen 120 and the movable platen moving speed detector for detecting the moving speed of the movable platen 120 are not limited to the mold clamping motor encoder 161, and a conventional detector may be used.

In the pressure increasing step, the clamping motor 160 is further driven to further advance the crosshead 151 from the mold closing end position to the clamping position, thereby generating clamping force.

In the mold clamping process, the mold clamping motor 160 is driven to maintain the position of the crosshead 151 at the mold clamping position. In the mold clamping step, the mold clamping force generated in the pressure increasing step is maintained. In the mold clamping step, a cavity space 801 (see fig. 2) is formed between the movable mold 820 and the fixed mold 810, and the injection device 300 fills the cavity space 801 with a liquid molding material. The filled molding material is cured, thereby obtaining a molded article.

The number of cavity spaces 801 may be 1 or more. In the latter case, a plurality of molded articles can be obtained at the same time. An insert may be disposed in a portion of the cavity space 801 and another portion of the cavity space 801 may be filled with molding material. A molded article in which the insert and the molding material are integrated can be obtained.

In the decompression step, the clamping motor 160 is driven to retract the crosshead 151 from the clamping position to the mold opening start position, and the movable platen 120 is retracted to reduce the clamping force. The mold opening start position and the mold closing end position may be the same position.

In the mold opening step, the movable platen 120 is retracted by driving the mold clamping motor 160 to retract the crosshead 151 from the mold opening start position to the mold opening end position at a set movement speed, so that the movable mold 820 is separated from the fixed mold 810. Then, the ejector 200 ejects the molded article from the mold 820.

The setting conditions in the mold closing step, the pressure increasing step, and the mold closing step are set in a unified manner as a series of setting conditions. For example, the moving speed, the position (including the mold closing start position, the moving speed switching position, the mold closing end position, and the mold clamping position) and the mold clamping force of the crosshead 151 in the mold closing step and the pressure increasing step are set in a unified manner as a series of setting conditions. The mold closing start position, the moving speed switching position, the mold closing end position, and the mold closing position are arranged in this order from the rear side to the front side, and indicate the start point and the end point of the section in which the moving speed is set. The movement speed is set for each section. The number of the movement speed switching positions may be 1 or plural. The moving speed switching position may not be set. Only one of the mold clamping positions and the mold clamping forces may be set.

The conditions for setting in the decompression step and the mold opening step are set in the same manner. For example, the moving speed and the position (the mold opening start position, the moving speed switching position, and the mold opening end position) of the crosshead 151 in the decompression step and the mold opening step are set in a unified manner as a series of setting conditions. The mold opening start position, the movement speed switching position, and the mold opening end position are arranged in this order from the front side to the rear side, and indicate the start point and the end point of the section in which the movement speed is set. The movement speed is set for each section. The number of the movement speed switching positions may be 1 or plural. The movement speed switching position may not be set. The mold opening start position and the mold closing end position may be the same position. The mold opening end position and the mold closing start position may be the same position.

In addition, the moving speed, position, etc. of the movable platen 120 may be set instead of the moving speed, position, etc. of the crosshead 151. The clamping force may be set instead of the position of the crosshead (for example, the clamping position) and the position of the movable platen.

However, the toggle mechanism 150 amplifies the driving force of the clamp motor 160 and transmits it to the movable platen 120. Its magnification is also called toggle magnification. The toggle magnification changes according to an angle θ (hereinafter, also referred to as "link angle θ") formed by the 1 st link 152 and the 2 nd link 153. The link angle θ is obtained from the position of the crosshead 151. When the link angle θ is 180 °, the toggle magnification becomes maximum.

When the thickness of the mold device 800 changes due to replacement of the mold device 800, temperature change of the mold device 800, or the like, mold thickness adjustment is performed to obtain a predetermined clamping force at the time of clamping. In the die thickness adjustment, for example, the distance L between the fixed platen 110 and the toggle base 130 is adjusted so that the link angle θ of the toggle mechanism 150 becomes a predetermined angle at the time when the movable die 820 contacts the fixed die 810.

The mold clamping device 100 has a mold thickness adjusting mechanism 180. The die thickness adjustment mechanism 180 adjusts the distance L between the fixed platen 110 and the toggle base 130, thereby performing die thickness adjustment. The timing of the mold thickness adjustment is performed, for example, during a period from the end of the molding cycle to the start of the next molding cycle. The die thickness adjusting mechanism 180 includes, for example: a screw shaft 181 formed at a rear end portion of the connection rod 140; a screw nut 182 rotatably held in the toggle seat 130 and being non-retractable; and a die thickness adjusting motor 183 for rotating a screw nut 182 screwed to the screw shaft 181.

A screw shaft 181 and a screw nut 182 are provided for each of the connection rods 140. The rotational driving force of the die thickness adjusting motor 183 may be transmitted to the plurality of lead screw nuts 182 via the rotational driving force transmitting portion 185. A plurality of lead screw nuts 182 can be rotated synchronously. Further, the plurality of lead screw nuts 182 may be individually rotated by changing the transmission path of the rotational driving force transmission unit 185.

The rotational driving force transmitting portion 185 is constituted by a gear or the like, for example. At this time, driven gears are formed on the outer periphery of each screw nut 182, a driving gear is mounted on the output shaft of the die thickness adjusting motor 183, and an intermediate gear engaged with the driven gears and the driving gear is rotatably held at the center portion of the toggle seat 130. The rotational driving force transmitting portion 185 may be formed of a belt, a pulley, or the like instead of a gear.

The operation of the die thickness adjusting mechanism 180 is controlled by the control device 700. The control device 700 drives the die thickness adjustment motor 183 to rotate the lead screw nut 182. As a result, the position of the toggle housing 130 relative to the connecting rod 140 is adjusted, and the interval L between the fixed platen 110 and the toggle housing 130 is adjusted. In addition, a plurality of die thickness adjusting mechanisms may be used in combination.

The interval L is detected using a die thickness adjustment motor encoder 184. The die thickness adjustment motor encoder 184 detects the rotation amount and rotation direction of the die thickness adjustment motor 183, and transmits a signal indicating the detection result to the control device 700. The detection result of the die thickness adjustment motor encoder 184 is used for monitoring and controlling the position and the interval L of the toggle seat 130. The toggle seat position detector for detecting the position of the toggle seat 130 and the interval detector for detecting the interval L are not limited to the die thickness adjusting motor encoder 184, and a conventional detector may be used.

The mold clamping device 100 may have a mold temperature regulator that regulates the temperature of the mold device 800. The die device 800 has a flow path for the temperature control medium therein. The mold temperature regulator regulates the temperature of the temperature regulating medium supplied to the flow path of the mold device 800, thereby regulating the temperature of the mold device 800.

The mold clamping device 100 of the present embodiment is a horizontal mold opening/closing direction, but may be a vertical mold opening/closing direction.

The mold clamping device 100 of the present embodiment has the mold clamping motor 160 as a driving source, but may have a hydraulic cylinder instead of the mold clamping motor 160. The mold clamping device 100 may include a linear motor for mold opening and closing, or may include an electromagnet for mold clamping.

(Ejector device)

In the description of the ejector 200, the moving direction (for example, the positive X-axis direction) of the movable platen 120 at the time of mold closing is set to the front, and the moving direction (for example, the negative X-axis direction) of the movable platen 120 at the time of mold opening is set to the rear, similarly to the description of the mold clamping device 100.

The ejector 200 is attached to the movable platen 120 and advances and retreats together with the movable platen 120. The ejector 200 includes an ejector rod 210 that ejects a molded product from the mold device 800, and a driving mechanism 220 that moves the ejector rod 210 in the moving direction (X-axis direction) of the movable platen 120.

The ejector rod 210 is disposed so as to be movable in and out of the through hole of the movable platen 120. The front end of the ejector rod 210 contacts the ejector plate 826 of the movable mold 820. The tip end of the ejector rod 210 may or may not be connected to the ejector plate 826.

The driving mechanism 220 includes, for example, an ejector motor and a motion conversion mechanism that converts rotational motion of the ejector motor into linear motion of the ejector rod 210. The motion conversion mechanism comprises a screw shaft and a screw nut screwed with the screw shaft. Balls or rollers may be interposed between the screw shaft and the screw nut.

The ejector 200 performs the ejection process under the control of the control device 700. In the ejection step, the ejector rod 210 is advanced from the standby position to the ejection position at a set movement speed, and the ejector plate 826 is advanced to eject the molded article. Then, the ejector motor is driven to retract the ejector rod 210 at a set movement speed, and the ejector plate 826 is retracted to the original standby position.

The position and moving speed of the ejector rod 210 are detected, for example, using an ejector motor encoder. The ejector motor encoder detects the rotation of the ejector motor and transmits a signal indicating the detection result to the control device 700. The ejector rod position detector that detects the position of the ejector rod 210 and the ejector rod movement speed detector that detects the movement speed of the ejector rod 210 are not limited to the ejector motor encoder, and a conventional detector may be used.

(Injection device)

In the description of the injection device 300, the direction of movement of the screw 330 (for example, the negative X-axis direction) during filling is set to the front, and the direction of movement of the screw 330 (for example, the positive X-axis direction) during metering is set to the rear, unlike the description of the mold clamping device 100 and the description of the ejector 200.

The injection device 300 is provided on the slide base 301, and the slide base 301 is disposed so as to be movable relative to the injection device frame 920. The injection device 300 is disposed so as to be movable in and out of the mold device 800. The injection device 300 is in contact with the mold device 800, and fills the cavity space 801 in the mold device 800 with the molding material measured in the cylinder 310. The injection device 300 includes, for example, a cylinder 310 for heating a molding material, a nozzle 320 provided at a distal end portion of the cylinder 310, a screw 330 rotatably disposed in the cylinder 310, a metering motor 340 for rotating the screw 330, an injection motor 350 for advancing and retreating the screw 330, and a load detector 360 for detecting a load transmitted between the injection motor 350 and the screw 330.

The cylinder 310 heats the molding material supplied from the supply port 311 to the inside. The molding material includes, for example, a resin or the like. The molding material is formed into, for example, a pellet shape, and is supplied in a solid state to the supply port 311. The supply port 311 is formed at the rear of the cylinder 310. A cooler 312 such as a water-cooled cylinder is provided on the outer periphery of the rear portion of the cylinder block 310. A heater 313 such as a belt heater and a temperature detector 314 are provided on the outer periphery of the cylinder 310 in front of the cooler 312.

The cylinder 310 is divided into a plurality of regions along an axial direction (e.g., an X-axis direction) of the cylinder 310. The heater 313 and the temperature detector 314 are provided in each of the plurality of regions. The set temperatures are set for the respective plural areas, and the control device 700 controls the heater 313 so that the detected temperature of the temperature detector 314 becomes the set temperature.

The nozzle 320 is provided at the front end of the cylinder 310, and presses the die device 800. A heater 313 and a temperature detector 314 are provided on the outer periphery of the nozzle 320. The control device 700 controls the heater 313 so that the detected temperature of the nozzle 320 becomes the set temperature.

The screw 330 is rotatably disposed in the cylinder 310 and is movable forward and backward. When the screw 330 is rotated, the molding material is conveyed forward along the spiral groove of the screw 330. The molding material is gradually melted by heat from the cylinder 310 while being transferred to the front. As the molding material in the liquid state is conveyed to the front of the screw 330 and accumulated in the front of the cylinder 310, the screw 330 is retracted. Then, when the screw 330 is advanced, the liquid molding material accumulated in front of the screw 330 is injected from the nozzle 320 and filled in the mold device 800.

A check ring 331 is attached to the front of the screw 330 so as to be movable forward and backward, and the check ring 331 serves as a check valve to prevent backflow of the molding material from the front to the rear of the screw 330 when the screw 330 is pushed forward.

When the screw 330 is advanced, the check ring 331 is pushed rearward by the pressure of the molding material in front of the screw 330, and retreats relatively to the screw 330 to a closed position (refer to fig. 2) blocking the flow path of the molding material. This prevents the molding material accumulated in front of the screw 330 from flowing backward.

On the other hand, when the screw 330 is rotated, the check ring 331 is pushed forward by the pressure of the molding material conveyed forward along the spiral groove of the screw 330, and relatively advances to an open position (refer to fig. 1) where the flow path of the molding material is opened with respect to the screw 330. Thereby, the molding material is conveyed to the front of the screw 330.

Check ring 331 may be either a co-rotating type that rotates with screw 330 or a non-co-rotating type that does not rotate with screw 330.

In addition, the injection device 300 may have a driving source that advances and retreats the check ring 331 with respect to the screw 330 between the open position and the closed position.

The metering motor 340 rotates the screw 330. The driving source for rotating the screw 330 is not limited to the metering motor 340, and may be, for example, a hydraulic pump. The specific structure of the metering motor 340 will be described later.

Injection motor 350 advances and retracts screw 330. A motion conversion mechanism or the like for converting the rotational motion of injection motor 350 into the linear motion of screw 330 is provided between injection motor 350 and screw 330. The motion conversion mechanism includes, for example, a screw shaft and a screw nut screwed to the screw shaft. Balls, rollers, etc. may be provided between the screw shaft and the screw nut. The driving source for advancing and retreating the screw 330 is not limited to the injection motor 350, and may be, for example, a hydraulic cylinder or the like. The specific structure of the injection motor 350 will be described later.

The load detector 360 detects a load transmitted between the injection motor 350 and the screw 330. The detected load is converted into pressure by the control device 700. The load detector 360 is provided in a transmission path of the load between the injection motor 350 and the screw 330, and detects the load acting on the load detector 360.

The load detector 360 transmits a signal of the detected load to the control device 700. The load detected by the load detector 360 is converted into a pressure acting between the screw 330 and the molding material, and is used for controlling and monitoring the pressure received by the screw 330 from the molding material, the back pressure on the screw 330, the pressure acting on the molding material from the screw 330, and the like.

The pressure detector for detecting the pressure of the molding material is not limited to the load detector 360, and a conventional detector can be used. For example, a nozzle pressure sensor or an in-mold pressure sensor may be used. The nozzle pressure sensor is provided to the nozzle 320. The mold internal pressure sensor is provided inside the mold device 800.

The injection device 300 performs a metering process, a filling process, a pressure maintaining process, and the like under the control of the control device 700. The filling step and the pressure maintaining step may be collectively referred to as an injection step.

In the metering step, the metering motor 340 is driven to rotate the screw 330 at a set rotational speed, and the molding material is conveyed forward along the spiral groove of the screw 330. Thereby, the molding material is gradually melted. As the molding material in the liquid state is conveyed to the front of the screw 330 and accumulated in the front of the cylinder 310, the screw 330 is retracted. The rotational speed of screw 330 is detected, for example, using a metering motor encoder 341 (see fig. 4). The metering motor encoder 341 detects the rotation of the metering motor 340 and transmits a signal indicating the detection result to the control device 700. The screw rotation speed detector for detecting the rotation speed of the screw 330 is not limited to the metering motor encoder 341, and a conventional detector can be used.

In the metering step, the injection motor 350 may be driven to apply a set back pressure to the screw 330 in order to limit the rapid backward movement of the screw 330. The back pressure on the screw 330 is detected, for example, using a load detector 360. When the screw 330 is retracted to the metering end position and a predetermined amount of molding material is accumulated in front of the screw 330, the metering process ends.

The position and rotation speed of the screw 330 in the metering step are set uniformly as a series of setting conditions. For example, a measurement start position, a rotation speed switching position, and a measurement end position are set. These positions are arranged in order from the front side to the rear side, and indicate the start point and the end point of the section in which the rotational speed is set. The rotational speed is set for each section. The number of rotational speed switching positions may be 1 or a plurality of rotational speed switching positions. The rotational speed switching position may not be set. Back pressure is set for each section.

In the filling step, the injection motor 350 is driven to advance the screw 330 at a set moving speed, and the cavity space 801 in the mold apparatus 800 is filled with the liquid molding material stored in front of the screw 330. The position and moving speed of the screw 330 are detected, for example, using the injection motor encoder 351. The injection motor encoder 351 detects the rotation of the injection motor 350 and transmits a signal indicating the detection result thereof to the control device 700. When the position of the screw 330 reaches the set position, the filling process is switched to the pressure maintaining process (so-called V/P switching). The position where the V/P switch is performed is also referred to as a V/P switch position. The set moving speed of the screw 330 may be changed according to the position, time, etc. of the screw 330.

The position and the moving speed of the screw 330 in the filling process are set uniformly as a series of setting conditions. For example, a filling start position (also referred to as an "injection start position"), a moving speed switching position, and a V/P switching position are set. These positions are arranged in this order from the rear side to the front side, and indicate the start point and the end point of the section in which the movement speed is set. The movement speed is set for each section. The number of the movement speed switching positions may be 1 or plural. The moving speed switching position may not be set.

An upper limit value of the pressure of the screw 330 is set for each section in which the moving speed of the screw 330 is set. The pressure of the screw 330 is detected by a load detector 360. When the pressure of the screw 330 is below the set pressure, the screw 330 advances at the set moving speed. On the other hand, when the pressure of the screw 330 exceeds the set pressure, the screw 330 is advanced at a movement speed slower than the set movement speed so that the pressure of the screw 330 becomes equal to or lower than the set pressure in order to protect the mold.

In the filling step, after the position of the screw 330 reaches the V/P switching position, the screw 330 may be suspended at the V/P switching position and then V/P switching may be performed. Instead of stopping the screw 330, the screw 330 may be advanced at a slight speed or retracted at a slight speed immediately before the V/P switching. The screw position detector for detecting the position of the screw 330 and the screw movement speed detector for detecting the movement speed of the screw 330 are not limited to the injection motor encoder 351, and a conventional detector may be used.

In the pressure maintaining step, the injection motor 350 is driven to push the screw 330 forward, and the pressure of the molding material at the tip end portion of the screw 330 (hereinafter, also referred to as "holding pressure") is maintained at a set pressure, so that the molding material remaining in the cylinder 310 is pushed to the mold device 800. An insufficient amount of molding material caused by cooling shrinkage in the mold device 800 can be replenished. The holding pressure is detected, for example, using a load detector 360. The set value of the holding pressure may be changed according to the elapsed time from the start of the pressure-maintaining process. The holding pressure and the holding time for holding the holding pressure in the plurality of holding pressure steps may be set individually or may be set collectively as a series of setting conditions.

In the pressure maintaining step, the molding material in the cavity space 801 in the mold device 800 is gradually cooled, and at the end of the pressure maintaining step, the inlet of the cavity space 801 is blocked by the solidified molding material. This state is called gate sealing, and prevents backflow of molding material from the cavity space 801. After the pressure maintaining process, a cooling process is started. In the cooling step, solidification of the molding material in the cavity space 801 is performed. The metering step may be performed in the cooling step in order to shorten the molding cycle time.

The injection device 300 of the present embodiment is of a coaxial screw type, but may be of a pre-molding type or the like. The injection device of the pre-molding method supplies the molding material melted in the plasticizing cylinder to the injection cylinder, and injects the molding material from the injection cylinder into the mold device. In the plasticizing cylinder, the screw is rotatably disposed so as not to advance and retreat, or the screw is rotatably disposed so as to advance and retreat. On the other hand, in the injection cylinder, the plunger is disposed so as to be movable forward and backward.

The injection device 300 of the present embodiment is a horizontal type in which the axial direction of the cylinder 310 is horizontal, but may be a vertical type in which the axial direction of the cylinder 310 is vertical. The mold clamping device combined with the vertical injection device 300 may be either vertical or horizontal. Similarly, the mold clamping device combined with the horizontal injection device 300 may be either horizontal or vertical.

(Mobile device)

In the description of the moving device 400, the moving direction of the screw 330 (for example, the X-axis negative direction) during filling is set to the front, and the moving direction of the screw 330 (for example, the X-axis positive direction) during metering is set to the rear, as in the description of the injection device 300.

The movement device 400 advances and retracts the injection device 300 relative to the mold device 800. The moving device 400 presses the nozzle 320 against the die device 800 to generate a nozzle contact pressure. The traveling apparatus 400 includes a hydraulic pump 410, a motor 420 as a driving source, a hydraulic cylinder 430 as a hydraulic actuator, and the like.

The hydraulic pump 410 has a1 st port 411 and a 2 nd port 412. The hydraulic pump 410 is a pump capable of rotating in both directions, and generates hydraulic pressure by switching the rotation direction of the motor 420 so that a working fluid (for example, oil) is sucked from one of the 1 st port 411 and the 2 nd port 412 and discharged from the other port. The hydraulic pump 410 may suck the working fluid from the tank and discharge the working fluid from any one of the 1 st port 411 and the 2 nd port 412.

The motor 420 operates the hydraulic pump 410. The motor 420 drives the hydraulic pump 410 by a rotation direction and a torque corresponding to a control signal from the control device 700. The motor 420 may be an electric motor or an electric servo motor.

Hydraulic cylinder 430 has a cylinder body 431, a piston 432, and a piston rod 433. Cylinder body 431 is fixed relative to injection device 300. Piston 432 divides the interior of cylinder body 431 into a front chamber 435 that is a1 st chamber and a rear chamber 436 that is a 2 nd chamber. The piston rod 433 is fixed with respect to the fixed platen 110.

The front chamber 435 of the hydraulic cylinder 430 is connected to the 1 st port 411 of the hydraulic pump 410 via the 1 st flow path 401. The working fluid discharged from the 1 st port 411 is supplied to the front chamber 435 via the 1 st flow path 401, and the injection device 300 is pushed forward. The injection device 300 is advanced and the nozzle 320 is pressed against the stationary mold 810. The front chamber 435 functions as a pressure chamber that generates a nozzle contact pressure of the nozzle 320 by the pressure of the working fluid supplied from the hydraulic pump 410.

On the other hand, the rear chamber 436 of the hydraulic cylinder 430 is connected to the 2 nd port 412 of the hydraulic pump 410 via the 2 nd flow path 402. The working fluid discharged from the 2 nd port 412 is supplied to the rear chamber 436 of the hydraulic cylinder 430 via the 2 nd flow path 402, whereby the injection device 300 is pushed rearward. The injection device 300 is retracted and the nozzle 320 is separated from the stationary mold 810.

In the present embodiment, the moving device 400 includes the hydraulic cylinder 430, but the present invention is not limited to this. For example, instead of the hydraulic cylinder 430, an electric motor and a motion conversion mechanism that converts the rotational motion of the electric motor into the linear motion of the injection device 300 may be used.

(Control device)

As shown in fig. 1 to 2, the control device 700 is configured by a computer, for example, and includes a CPU (Central Processing Unit: central processing unit) 701, a storage medium 702 such as a memory, an input interface 703, an output interface 704, and a communication interface 705. The control device 700 performs various controls by causing the CPU701 to execute a program stored in the storage medium 702. The control device 700 receives a signal from the outside through the input interface 703 and transmits a transmission signal to the outside through the output interface 704. The control device 700 transmits information to an external device via the communication interface 705.

The control device 700 repeatedly performs a metering process, a mold closing process, a pressure increasing process, a mold closing process, a filling process, a pressure maintaining process, a cooling process, a pressure releasing process, a mold opening process, an ejection process, and the like, to thereby repeatedly produce a molded product. A series of operations for obtaining a molded product, for example, from the start of a metering process to the start of the next metering process is also referred to as "injection" or "molding cycle". The time required for one shot is also referred to as "molding cycle time" or "cycle time".

The one-shot molding cycle includes, for example, a metering step, a mold closing step, a pressure increasing step, a mold closing step, a filling step, a pressure maintaining step, a cooling step, a pressure releasing step, a mold opening step, and an ejection step in this order. The sequence here is the sequence in which the respective steps are started. The filling step, the pressure maintaining step, and the cooling step are performed during the mold clamping step. The start of the mold clamping process may be coincident with the start of the filling process. The end of the decompression step corresponds to the start of the mold opening step.

In order to shorten the molding cycle time, a plurality of steps may be performed simultaneously. For example, the metering step may be performed in the cooling step of the previous molding cycle, or may be performed during the mold clamping step. In this case, the mold closing step may be performed at the beginning of the molding cycle. The filling process may be started in the mold closing process. The ejection step may be started in the mold opening step. When an opening/closing valve for opening/closing the flow path of the nozzle 320 is provided, the mold opening process may be started in the metering process. This is because, even if the mold opening process is started in the metering process, the molding material does not leak from the nozzle 320 as long as the opening/closing valve closes the flow path of the nozzle 320.

The one-shot molding cycle may include steps other than the metering step, the mold closing step, the pressure increasing step, the mold closing step, the filling step, the pressure maintaining step, the cooling step, the pressure releasing step, the mold opening step, and the ejection step.

For example, the pre-metering suck-back step of retracting the screw 330 to a preset metering start position may be performed after the end of the pressure maintaining step and before the start of the metering step. The pressure of the molding material accumulated in front of the screw 330 can be reduced before the start of the metering process, and the screw 330 can be prevented from rapidly backing up when the metering process is started.

After the completion of the metering step and before the start of the filling step, the post-metering suck-back step of retracting the screw 330 to a preset filling start position (also referred to as "injection start position") may be performed. The pressure of the molding material accumulated in front of the screw 330 can be reduced before the start of the filling process, and leakage of the molding material from the nozzle 320 can be prevented before the start of the filling process.

The control device 700 is connected to an operation device 750 that receives an input operation from a user and a display device 760 that displays a screen. The operation device 750 and the display device 760 are constituted by, for example, a touch panel 770, and may be integrated. The touch panel 770 as the display device 760 displays a screen under the control of the control device 700. On the screen of the touch panel 770, information such as the setting of the injection molding machine 10, the current state of the injection molding machine 10, and the like can be displayed, for example. The touch panel 770 can accept an operation in the displayed screen area. In the screen region of the touch panel 770, an operation unit such as a button or an input field for receiving an input operation by a user may be displayed. The touch panel 770 as the operation device 750 detects an input operation of a user on a screen, and outputs a signal corresponding to the input operation to the control device 700. Thus, for example, the user can perform setting (including input of a set value) of the injection molding machine 10 by operating the operation unit provided on the screen while checking information displayed on the screen. The user can operate the operation unit provided on the screen, and thereby operate the injection molding machine 10 corresponding to the operation unit. The operation of the injection molding machine 10 may be, for example, the operations (including stopping) of the mold clamping device 100, the ejector 200, the injection device 300, the moving device 400, and the like. The operation of the injection molding machine 10 may be, for example, switching of a screen displayed on the touch panel 770 serving as the display device 760.

The operation device 750 and the display device 760 according to the present embodiment are integrated into the touch panel 770, but may be provided independently. Further, a plurality of operation devices 750 may be provided. The operation device 750 and the display device 760 are disposed on the operation side (Y-axis negative direction) of the mold clamping device 100 (more specifically, the stationary platen 110).

(Structure of injection device)

Next, a specific configuration of the injection device 300 will be described.

Fig. 3 is a top view showing the connection structure of a cylinder 310, a metering motor 340, and an injection motor 350 provided in an injection device 300 according to the present embodiment.

An example of the structure of an injection device 300 according to the present embodiment will be described with reference to fig. 3. The injection device 300 includes a fixed plate 302 that holds the rear end of a cylinder 310 (an example of an output member), and a movable plate 303 that is provided behind the fixed plate 302. The fixed plate 302 is fixed with respect to the slide base 301. The movable plate 303 is provided to be movable forward and backward with respect to the slide base 301. A guide (not shown) for guiding the movable plate 303 may be laid on the slide base 301.

The injection device 300 includes a drive shaft 380 coaxially provided with the screw 330 and a coupling 381 connecting the screw 330 and the drive shaft 380. The drive shaft 380 extends rearward from the screw 330 and penetrates the penetration hole of the movable plate 303. A bearing, not shown, is provided in the through hole, and rotatably supports the drive shaft 380. The drive shaft 380 advances and retreats together with the movable plate 303.

The metering motor 340 rotates the screw 330 by rotating the drive shaft 380. The metering motor 340 is fixed to the movable plate 303, for example. The rotational motion of the metering motor 340 is transmitted to the drive shaft 380 through the rotation transmission mechanism 390. The rotation transmission mechanism 390 includes, for example, a drive pulley 391 provided on an output shaft of the metering motor 340, a driven pulley 392 provided on a rear end of the drive shaft 380, and a belt 393 bridging the drive pulley 391 and the driven pulley 392. The rotation transmission mechanism 390 may include gears instead of pulleys and belts.

The injection motor 350 advances and retracts the movable plate 303 to advance and retract the screw 330 together with the drive shaft 380. The rotational movement of the injection motor 350 is converted into a linear movement of the movable plate 303 by the movement conversion mechanism 370. The motion conversion mechanism 370 includes a screw shaft 371 and a screw nut 372 screwed to the screw shaft 371. The motion conversion mechanism 370 is, for example, a ball screw, and has a ball not shown between the screw shaft 371 and the screw nut 372. Instead of the balls, rollers may be used.

The injection motor 350 is fixed, for example, with respect to the fixed plate 302. At this time, the lead screw nut 372 is fixed to the movable plate 303. The injection motor 350 rotates the screw shaft 371, thereby advancing and retreating the screw nut 372. Thereby, the movable plate 303 is advanced and retracted.

The arrangement of the injection motor 350 and the screw nut 372 may be reversed, or the injection motor 350 may be fixed to the movable plate 303 and the screw nut 372 may be fixed to the fixed plate 302. At this time, when the injection motor 350 rotates the screw shaft 371, the screw shaft 371 is rotated and simultaneously advanced and retracted. As a result, the movable plate 303 advances and retreats together with the injection motor 350. The lead screw nut 372 neither rotates nor advances or retreats.

The injection motor 350 and the motion conversion mechanism 370 are arranged symmetrically (for example, in a pair) with respect to the screw 330. Thus, the screw 330 can be pushed straight by the plurality of injection motors 350, and bending of the screw 330 can be suppressed. The number of the injection motors 350 and the motion conversion mechanisms 370 may be 1, and the injection motors 350 and the motion conversion mechanisms 370 may be disposed on the same line as the screw 330.

In the example shown in fig. 3, 2 injection motors 350 are connected to the movable plate 303 via a motion conversion mechanism 370, respectively. Therefore, in order to advance and retreat the movable plate 303, 2 injection motors 350 need to be driven simultaneously. Similarly, when the movable plate 303 is stopped, 2 injection motors 350 need to be stopped simultaneously.

That is, when the screw 330 is stopped, if the rotational speed of one injection motor 350 varies from the rotational speed of the other injection motor 350, the position of the injection motor 350 relative to the movable plate 303 varies. When the time in which the deviation occurs in the rotation speed is long, the positional difference of the injection motor 350 with respect to the movable plate 303 becomes large. At this time, there is a possibility that strain or inclination occurs in the movable plate 303 due to the deviation of the positional difference, and abnormality such as strain or inclination occurs in the screw shaft 371 of the motion conversion mechanism 370 or the drive shaft 380 of the movable plate 303 and the like.

Therefore, in the present embodiment, the following stop control is performed in the injection molding machine 10. Next, a configuration for performing stop control will be described.

(Embodiment 1)

Fig. 4 is a diagram showing constituent elements for controlling the control device 700 and the injection motor 350 of the injection molding machine 10 according to embodiment 1, with functional blocks. The functional blocks of the control device 700 illustrated in fig. 4 are conceptual functional blocks, and are not necessarily physically configured as illustrated. All or part of the functional blocks may be functionally or physically distributed and integrated in arbitrary units. All or any part of the processing functions performed in the respective functional blocks are realized by programs executed by the CPU 701. Or the functional blocks may be implemented as hardware based wired logic. As shown in fig. 4, the CPU701 of the control device 700 includes an acquisition unit 711, a determination unit 712, and a motor control unit 713.

In the present embodiment, as an example of the motor control device, the injection motor 350 is controlled by a configuration in which the control device 700 and 2 motor drivers 352 are combined. The structure of the present embodiment is an example. For example, 1 device may have a function of combining the control device 700 and 2 motor drivers 352, and the injection motor 350 may be controlled by the 1 device. Also, the injection motor 350 may be controlled by a configuration in which 2 motor drivers 352 are combined into one.

The acquisition unit 711 acquires signals (an example of information) indicating the detection results from various sensors provided in the injection molding machine 10. For example, the acquisition unit 711 acquires a signal related to the operation from the operation device 750. The acquisition unit 711 acquires a signal related to the rotation of the injection motor 350 from the injection motor encoder 351.

The determination unit 712 determines whether or not an abnormality has occurred in the injection molding machine 10 based on the signal acquired by the acquisition unit 711. For example, when the rotation state of the rotor 350a of the injection motor 350 cannot be recognized based on the signal from the injection motor encoder 351, the determination unit 712 determines that an abnormality has occurred in the injection motor encoder 351. When the operation device 750 performs an interesting operation of stopping the injection molding machine abnormally, the determination unit 712 determines that an abnormality has occurred in the injection molding machine 10. The present embodiment shows an example of determination as to whether or not an abnormality has occurred in the injection molding machine 10, and any determination as to an abnormality may be made based on signals from various sensors or the operation device 750.

The motor controller 713 generates an operation command for rotating the injection motor 350 and outputs the operation command. The operation command may include, for example, a command to stop the injection motor 350, or may include a rotation speed that is a target of the injection motor 350.

Next, a structure associated with the injection motor 350 will be described. In the present embodiment, 2 injection motors 350, injection motor encoder 351, three-phase inverter 353, 1 st current sensor (an example of a detection unit) 354, and 2 nd current sensor (an example of a detection unit) 355 are provided. The above-described structures each provided with 2 are assumed to be the same. Also, electric power from the power source 356 is supplied to each of the injection motors 350 via the three-phase inverter 353. The injection motor 350, the injection motor encoder 351, the three-phase inverter 353, the 1 st current sensor 354, and the 2 nd current sensor 355 will be described below.

The injection motor 350 according to the present embodiment is a three-phase motor including a rotor 350a and a stator 350 b. The injection motor 350 is provided with a U-phase terminal, a V-phase terminal, and a W-phase terminal, and rotates the rotor 350a by three-phase ac power supplied from the U-phase terminal, the V-phase terminal, and the W-phase terminal.

The rotor 350a is a magnet having an S-pole and an N-pole, for example, and rotates together with a screw shaft 371 connected to the injection motor 350.

The stator 350b is configured to generate a force for rotating the rotor 350a, and includes a U-phase coil, a V-phase coil, and a W-phase coil of three phases, not shown, and the poles and magnetic fields generated in the coils are changed by three-phase ac supplied from the three-phase inverter 353. The rotor 350a rotates by the voltage change caused by the three-phase alternating current.

The injection motor encoder 351 detects rotation of the injection motor 350, generates a predetermined number of pulses per rotation, and outputs the pulses to the control device 700. The control device 700 can determine the rotational speed of the injection motor 350 from the number of pulses input per unit time, and determine the rotational amount of the injection motor 350 from the total number of pulses.

The 1 st current sensor 354 detects a driving current supplied from the three-phase inverter 353 to the U-phase terminal of the injection motor 350, and outputs the detected value to the motor driver 352.

The 2 nd current sensor 355 detects a driving current supplied from the three-phase inverter 353 to the V-phase terminal of the injection motor 350, and outputs the detected value to the motor driver 352.

The motor driver 352 generates a control signal for rotating the injection motor 350 based on the detection values from the 1 st current sensor 354 and the 2 nd current sensor 355, the rotation speed of the injection motor 350, and the like, and an operation command from the control device 700, and outputs the control signal to the three-phase inverter 353. Regarding the actual rotational speed and the like (rotational speed and rotational amount) of the injection motor 350, the motor driver 352 may be obtained from the control device 700 or may be obtained directly from the injection motor encoder 351.

The three-phase inverter 353 is configured by a converter 357, a plurality of (not shown) power transistors, and a plurality of (not shown) diodes. The structures of the plurality of power transistors and the plurality of diodes are the same as the conventional structure.

The converter 357 converts the voltage of the electric power supplied from the power source 356 in accordance with the control signal from the motor driver 352, and outputs a dc current.

Then, the three-phase inverter 353 controls a plurality of power transistors and a plurality of diodes according to a control signal from the motor driver 352, converts the direct current input from the converter 357 into three-phase alternating current, and supplies electric power to the injection motor 350 with the three-phase alternating current. Thereby, the injection motor 350 rotates.

Next, specific control of the motor driver 352 will be described.

For example, when the rotational speed is included in the input operation command, the motor driver 352 generates a control signal such as the rotational speed included in the operation command in consideration of the acquired rotational speed and the drive currents input from the 1 st current sensor 354 and the 2 nd current sensor 355, and outputs the control signal to the three-phase inverter 353. By this control signal, the drive current supplied from the three-phase inverter 353 to the injection motor 350 is changed, and the torque, the speed, and the like of the injection motor 350 are controlled so as to be the rotational speed shown in the operation command.

When the command for the operation includes an abnormal stop interest (rotational speed '0'), the motor driver 352 generates a control signal for stopping the injection motor encoder 351 based on the drive currents input from the 1 st current sensor 354 and the 2 nd current sensor 355, and outputs the control signal to the three-phase inverter 353.

Specifically, when the abnormal stop control of the injection motor 350 is performed, the motor driver 352 controls the current output from the power source 356 to the injection motor 350 so that the current values flowing in the three phases become '0A (ampere)'. That is, when the injection motor 350 is abnormally stopped, even if the supply of power to the injection motor 350 from the three-phase inverter 353 is stopped, the rotor 350a rotates in the injection motor 350, and thus, a current flows due to an induced electromotive force generated between the rotor 350a and the stator 350 b.

Therefore, the motor driver 352 according to the present embodiment controls the three-phase inverter 353 so that the currents flowing in the three phases are "0A" (so as to cancel the induced currents) even when the currents flow due to the induced electromotive force. For example, the motor driver 352 controls the converter 357 to apply a voltage such as to cancel the induced electromotive force. That is, by applying a voltage substantially equal to the induced electromotive force, the flow of current can be suppressed. The induced electromotive force can be calculated from the detected current value and the like. The motor driver 352 controls the power transistors in the three-phase inverter 353 to control the output destination of the electric power so as to correspond to the current values flowing in the three phases due to the induced electromotive force. Thus, the motor driver 352 controls the current output to the injection motor 350 via the three-phase inverter 353 so as to include the current flowing due to the induced electromotive force, and the currents flowing in the three phases respectively become '0A'. In other words, the motor driver 352 controls the current output from the power source 356 to the injection motor 350 (one example of a three-phase motor) so as to cancel the current flowing (induced) due to the induced electromotive force. The present embodiment shows one embodiment of control for setting the current values of the currents flowing in the three phases to '0A', but is not limited to this method. For example, a circuit for setting the current flowing in each of the three phases to '0A' may be separately provided, and all the methods may be used regardless of whether they are known methods.

In the present embodiment, when the current value flowing in the U phase and the current value flowing in the V phase are obtained from the 1 st current sensor 354 and the 2 nd current sensor 355, the motor driver 352 calculates the current value flowing in the W phase from the current value flowing in the U phase and the current value flowing in the V phase. Then, the motor driver 352 controls the current output from the three-phase inverter 353 to the injection motor 350 so that the current values flowing in the three phases become '0A'.

The control method of the current may use all methods regardless of whether it is a known method. In the present embodiment, an example of controlling the current values flowing in the three phases to be "0A" is described, but the present invention is not limited to a method of controlling the current values to be "0A" at all, and the current values may be values close to "0A". In other words, by making the current values of the three phases flowing through the injection motor 350 approximately equal to "0A", the burden on the injection motor 350 can be reduced.

The stop control according to the present embodiment is useful when abnormality is detected from the signal acquired from the injection motor encoder 351. That is, when an abnormality is detected from the signal acquired from the injection motor encoder 351, it becomes difficult to consider stop control of the magnetic poles of the rotor 350 a. In contrast, in the present embodiment, when abnormality is detected from the signal acquired from the injection motor encoder 351 and stop control of the injection motor 350 is performed, the motor driver 352 controls the current output from the three-phase inverter 353 to the injection motor 350 so that the current values flowing in the three phases become '0A'. Thus, even in the case where the signal acquired from the injection motor encoder 351 is abnormal, the motor driver 352 can realize stop control in consideration of the magnetic pole of the rotor 350 a.

< Description of speed change >

Next, a change in the rotational speed of the injection motor when the injection molding machine is abnormally stopped in the conventional injection molding machine will be described.

Fig. 5 is a diagram showing a change in rotational speed when an operation command indicating an abnormal stop is received in a conventional injection molding machine. In the example shown in fig. 5, as in the present embodiment, an example is provided in which 2 injection motors are provided in an injection molding machine. The horizontal axis of fig. 5 represents time, and the vertical axis of fig. 5 represents rotational speed and position.

In the example shown in fig. 5, the operation command 1501 indicates a command value for the rotational speed of one injection motor. Action command 1502 indicates a command value for the rotational speed of the other injection motor.

The rotational speed 1503 represents the rotational speed of one injection motor and the rotational speed 1504 represents the rotational speed of the other injection motor.

The positional deviation 1505 indicates a deviation between the position in the X-axis direction of the lead screw nut connected to one injection motor and the position in the X-axis direction of the lead screw nut connected to the other injection motor.

Further, operation instructions 1501 and 1502 output from the control device to the 2 motor drivers are shown. The operation commands 1501 and 1502 are commands for increasing the rotation speed up to time t1, and commands for performing an abnormal stop (setting the rotation speed to '0') are set after time t 1.

Accordingly, the 2 motor drivers respectively make direct currents flow in the U-phase, V-phase and W-phase coils of the stator of the connected injection motor, respectively, on the basis of the fixed voltages. The voltage value may be any value, and the sum of voltages flowing through the coils of the U phase, V phase, and W phase becomes '0'. For example, the motor driver may control the U-phase to supply electric power at a positive predetermined voltage. At this time, the motor driver controls the V-phase and W-phase to supply power to 1/2 of the negative predetermined voltage. The predetermined voltage may be any value, for example, 1/2 of the voltage value that can be output. Further, the motor driver stops the application of the voltage after the rotation of the injection motor is stopped.

At this time, the rotational speeds 1503, 1504 gradually decrease while repeatedly decreasing and increasing by the magnetic poles and the magnetic field generated in the coils of the stator. In the example shown in fig. 5, the decrease and increase in the rotation speed are repeated in the period from time t1 to time t 5. If the rotor position state is different between one injection motor and the other injection motor, a deviation occurs in the rotational speed between the one injection motor and the other injection motor.

In the example shown in fig. 5, there is a deviation in the rotational speed between the time t2 and the time t3 and between the time t4 and the time t 5. Therefore, the positional deviation 1505 increases between the time t2 and the time t3 and between the time t4 and the time t 5.

When the positional deviation 1505 becomes large, in other words, when the position of the 2 screw nuts in the X-axis direction is deviated, a load due to the positional deviation occurs in a structure of any one or more of the screw shaft screwed with the screw nuts, the movable plate connected to the 2 screw nuts, and the drive shaft and the screw connected to the movable plate. When the load is large, strain or tilting may occur in the above-described structure.

That is, in order to suppress the strain and inclination of the structure, it is preferable to control so as to avoid occurrence of a deviation in the rotational speeds of the plurality of injection motors. Therefore, the control device 700 and the motor driver 352 according to the present embodiment perform the above-described control.

Fig. 6 is a diagram showing a change in rotational speed when an operation command indicating an abnormal stop is received in the injection molding machine 10 according to the present embodiment. The horizontal axis of fig. 6 represents time, and the vertical axis of fig. 6 represents rotational speed and position.

In the example shown in fig. 6, the operation command 1601 indicates a command value for the rotational speed of one injection motor 350. The operation command 1602 indicates a command value for the rotational speed of the other injection motor 350.

The rotational speed 1603 represents the rotational speed of one injection motor 350 and the rotational speed 1604 represents the rotational speed of the other injection motor 350.

The positional deviation 1605 indicates a deviation between the position in the X-axis direction of the lead screw nut 372 connected to one injection motor 350 and the position in the X-axis direction of the lead screw nut 372 connected to the other injection motor 350.

Further, operation commands 1601 and 1602 are shown, which are output from the control device 700 to the 2 motor drivers 352, respectively. The operation commands 1601 and 1602 are commands for increasing the rotation speed up to time t11, and commands for performing an abnormal stop (setting the rotation speed to '0') after time t 11.

The 2 motor drivers 352 control the respective current values of the 3-phase lines connected to the injection motor 350 from the three-phase inverter 353 (i.e., the mode of canceling the induced current) so as to be '0A', including the current flowing due to the induced electromotive force, based on the current values detected by the 1 st current sensor 354 and the 2 nd current sensor 355, respectively.

When this control is performed, the rotational speeds of the 2 injection motors 350 are reduced without being deviated, as shown by rotational speeds 1603 and 1604.

Therefore, in the example shown in fig. 6, the positional deviation 1605 becomes smaller than the positional deviation 1505 shown in fig. 5.

Therefore, in the present embodiment, the motor driver 352 performs the control described above, and thus can perform control to stop the 2 injection motors 350 without causing a deviation in the rotational speed.

An example in which the injection molding machine 10 according to the present embodiment is provided with 2 injection motors 350 is described. However, the present embodiment is not limited to the example in which 2 injection motors 350 are provided in the injection molding machine 10, and 3 or more injection motors 350 may be provided in the injection molding machine 10.

(Modification)

In the above embodiment, an example in which the injection molding machine 10 is provided with the plurality of injection motors 350 has been described. However, the above-described embodiment is not limited to the example in which the plurality of injection motors 350 are provided in the injection molding machine 10. Accordingly, in the present modification, an example is given in which 1 injection motor 350 is provided in the injection molding machine 10.

Even in the case where 1 injection motor 350 is provided in the injection molding machine 10, the motor driver 352 performs the same control as in the above embodiment when stopping the injection motor 350.

In the present modification, the motor driver 352 performs the same control as in the above embodiment, in other words, controls so that the current values of the 3-phase wires connected to the injection motor 350 become "0A" when the abnormal stop is performed. By performing this control, the motor driver 352 can suppress the repetition of the increase and decrease of the rotational speed of the injection motor 350. Therefore, in this modification, deterioration of the structure including the injection motor 350 can be suppressed, and a longer lifetime can be achieved.

The above embodiment and modification have described a case where the motor driver 352 and the like perform stop control of the injection motor 350 mounted as the injection motor 350 in the injection molding machine 10. However, the above embodiments and modifications do not limit the apparatus for performing the stop control to the injection molding machine. For example, the motor control device may perform the stop control of the three-phase motor mounted in another molding machine such as an extrusion molding machine.

In the above embodiment, the control device 700 and the motor driver 352 (an example of a motor control device) are examples when mounted in an injection molding machine, and the device to which the motor control device is mounted is not limited. That is, the motor control device that performs the above control may be mounted on any device, regardless of whether it is a molding machine, as long as it is a device that mounts a three-phase motor.

< Action >

In the above embodiment and modification, the motor driver 352 and the control device 700 perform the stop control, and thus the repetition of the increase and decrease in the rotational speed of the injection motor 350 can be suppressed. Therefore, in the present modification, deterioration of the structure including the injection motor 350 can be suppressed. Therefore, the structure including the injection motor 350 can be made longer.

In the above embodiment and modification, when the stop control is performed, the current values of the 3-phase lines connected to the injection motor 350 from the three-phase inverter 353 are controlled to be "0A". That is, compared with the conventional stop control, the current flowing at the time of the stop control can be reduced. Therefore, power saving can be achieved, and protection of the three-phase inverter 353 and the like can be achieved.

Further, when the stop control is performed in the plurality of three-phase motors (for example, the injection motor 350), the variation in the rotation speed can be suppressed, and therefore, the generation of the load in the mechanism (for example, the screw shaft 371 screwed with the screw nut 372, the movable plate 303 connected to the 2 screw nuts 372, and the drive shaft 380 and the screw 330 connected to the movable plate 303) connected to the plurality of three-phase motors can be suppressed. Therefore, strain or tilting in the mechanism can be suppressed.

The embodiments of the motor control device and the molding machine according to the present invention have been described above, but the present invention is not limited to the above embodiments and the like. Various changes, modifications, substitutions, additions, deletions and combinations can be made within the scope described in the claims. These are, of course, within the technical scope of the present invention.

Claims (5)

1. A motor control device, wherein,

The control unit is configured to acquire a current value flowing between a power source and a three-phase motor from a detection unit, and to control a current output from the power source to the three-phase motor so as to include a current flowing due to an induced electromotive force that varies based on a magnetic field between a rotor and a stator of the three-phase motor generated by rotation of the three-phase motor when the three-phase motor is stopped, and the current value detected by the detection unit is approximately '0' ampere.

2. The motor control device according to claim 1, wherein,

The control unit is configured to acquire the current values flowing in the two phases of the three-phase motor from the detection unit, calculate a current value flowing in the other phase from the current values flowing in the two phases, and control the current output from the power supply to the three-phase motor so that the current values flowing in the three phases are approximately '0' ampere.

3. The motor control device according to claim 1, wherein,

The control unit is configured to control the current output from the power supply to the three-phase motor so that the current value approaches approximately '0' ampere when the stop control of the three-phase motor is performed by detecting an abnormality based on a signal obtained from an encoder that obtains a positional change of the three-phase motor.

4. A motor control device, wherein,

The control unit is configured to acquire a current value flowing between a power source and a three-phase motor from a detection unit, and to control a current output from the power source to the three-phase motor so as to cancel a current flowing due to an induced electromotive force caused by a change in a magnetic field between a rotor and a stator of the three-phase motor generated by rotation of the three-phase motor when the three-phase motor is stopped.

5. A molding machine is provided with:

An output member that outputs a molding material;

a plurality of three-phase motors to which the output members are movably connected; and

And a control unit configured to acquire current values flowing between a power source and the three-phase motor from detection units provided to the plurality of three-phase motors, respectively, and to control, in stopping control of the plurality of rotating three-phase motors, currents outputted to the plurality of three-phase motors so as to include currents flowing due to induced electromotive forces that vary based on a magnetic field between a rotor and a stator of the three-phase motor generated by rotation, in each of the plurality of three-phase motors, and to approximate the current values acquired from each of the plurality of three-phase motors to approximately '0'.