EP1158557A2 - Ceramic metal halide lamp lead welding system - Google Patents

Ceramic metal halide lamp lead welding system Download PDF

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Publication number
EP1158557A2
EP1158557A2 EP20010304347 EP01304347A EP1158557A2 EP 1158557 A2 EP1158557 A2 EP 1158557A2 EP 20010304347 EP20010304347 EP 20010304347 EP 01304347 A EP01304347 A EP 01304347A EP 1158557 A2 EP1158557 A2 EP 1158557A2
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EP
European Patent Office
Prior art keywords
wire
components
component
supports
wire components
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP20010304347
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German (de)
French (fr)
Inventor
Martin Norman Hassink
Glenn Howard Kuenzler
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General Electric Co
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General Electric Co
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Publication date
Application filed by General Electric Co filed Critical General Electric Co
Publication of EP1158557A2 publication Critical patent/EP1158557A2/en
Withdrawn legal-status Critical Current

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21FWORKING OR PROCESSING OF METAL WIRE
    • B21F15/00Connecting wire to wire or other metallic material or objects; Connecting parts by means of wire
    • B21F15/02Connecting wire to wire or other metallic material or objects; Connecting parts by means of wire wire with wire
    • B21F15/06Connecting wire to wire or other metallic material or objects; Connecting parts by means of wire wire with wire with additional connecting elements or material
    • B21F15/08Connecting wire to wire or other metallic material or objects; Connecting parts by means of wire wire with wire with additional connecting elements or material making use of soldering or welding
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00Gas-discharge or vapour-discharge lamps
    • H01J61/02Details
    • H01J61/36Seals between parts of vessels; Seals for leading-in conductors; Leading-in conductors
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/24Manufacture or joining of vessels, leading-in conductors or bases
    • H01J9/28Manufacture of leading-in conductors

Definitions

  • the present invention concerns a system for fabricating a lead wire for a Ceramic Metal Halide Lamp constructed of three constituent wire components.
  • FIG. 1 is a depiction of a prior art Ceramic Metal Halide Lamp 10.
  • a metal base 11 defines circumferentially extending threads for connecting the lamp 10 to a socket which supplies an energizing voltage to the lamp.
  • the lamp includes a clear outer jacket 12 coupled to the base and having an interior that has been evacuated to a specified pressure and may optionally include nitrogen gas as an added component.
  • Mounted to the base in a generally central position is an arc tube 13 filled with an ionizable metal halide material.
  • a voltage difference is applied between two electrodes or leads 14, 16 which extend into the arc tube.
  • the arc tube 13 is a ceramic material and for example may be molded from an aluminum oxide so that necked down regions 13a, 13b of the tube form a seal about the leads 14, 16.
  • Each of the leads 14, 16 includes a tungsten tip T having an encircling coil end T' ( Figure 3).
  • the tungsten tip T is attached at one end to a molybdenum wire segment M having an outer coiled winding, which in turn is attached to a Niobium wire segment N.
  • the three segments or components T, M, N together make up a wire lead which when energized with an appropriate signal ignites and maintains light emission from the ionizable material inside the arc tube 13.
  • Figure 3 is a depiction on an enlarged scale of such a lead 16.
  • the diameter of the niobium wire component having uniform cross section is about 0.025 inches but can be varied depending on the lamp into which it is mounted.
  • the present invention includes apparatus for manufacturing a wire lead having at least two wire components which are welded at facing ends of the wire components.
  • the apparatus includes a first support for supporting a first wire component and a second support for supporting a second component.
  • the supports are positioned to axially align the two wire components for welding.
  • a drive moves the first support with its first wire component along a travel path until facing ends of the first and second axially aligned wire components contact each other.
  • the drive maintains a force of engagement between the facing ends of the first and second wire components as the two wire components are welded together to form a two component wire lead.
  • Figures 4A - 4G, 5A - 5G and 6A - 6G depict a system for forming a lead wire having at least two wire components which are welded together.
  • Alternate embodiments of the first station 110 are depicted in the workstation 110a of Figures 5A - 5G.
  • the workstation 110 includes two supports or fixtures 112, 114.
  • One fixture 112 supports a first wire component N and a second, stationary fixture 114 that supports a second wire component M in an axially aligned arrangement with respect to the first wire component.
  • a drive 120 moves the first fixture with its first wire component N in a direction indicated by an arrow 121 in Figure 4D of the common axis until facing ends of the first and second axially aligned wire components contact each other.
  • the drive 120 maintains a force of engagement between the facing ends of the first and second wire components M, N as the facing ends are welded together to form a wire lead from the first and second wire components.
  • a cam actuated lever or a pneumatic cylinder can be used to secure the fixture 112 while the wire is moved into place. Such a mechanism would release the fixture 112 and allow the drive 120 to provide follow through during welding.
  • the fixtures 112, 114 have V grooves 115 extending along the length of each fixture to align the centerlines of their respective components N, M loaded into the supports 112, 114 concentric to one another within an accuracy of 0.0005 inch.
  • One 'V' fixture 112 is attached to a linear slide 122 having low inertia that allows it to move toward and away from the stationary 'V' fixture 114 with low friction.
  • a niobium wire component N is fed onto the left hand 'V' fixture while the molybdenum component is fed onto the right hand 'V' fixture.
  • the two wire components are fed via vibratory linear inline feeders, which are schematically depicted by two arrows 128, 129 having tracks leading to the fixtures so that an endmost wire component is pushed into a fixture by a next succeeding wire component in the feeder. It should be apparent to those skilled in the art that alternate structure for feeding the wire components into the fixtures can be used.
  • the vibratory in line feeders 128, 129 move the wire components into the 'V' shaped support until the wire components contact a moveable stop 130 so that facing ends of the wire components engage opposite sides 130a, 130b of the moveable stop.
  • two sets of hold down fingers 132, 134 are activated to hold the wire components in place within their respective 'V' shaped supports.
  • the hold down fingers 132, 134 ( Figure 4B) engage a top surface of the wire components to create a three point contact.
  • the hold down fingers are most preferably either knurled or serrated on their contact surfaces to prevent axial movement of the components N, M relative to the 'V' shaped fixtures.
  • Alternate wire component hold down means may utilize a clamp that extends the length of the fixture instead of spaced apart fingers.
  • a second alternate embodiment of the invention may have a clam shell pivoting type hold down structure.
  • the vertical stop 130 is retracted out of the way ( Figure 4C).
  • the left hand fixture 112 and the niobium wire component N that is secured to the left hand fixture are moved to the right until an overhanging right end of the niobium wire component contacts the exposed end of the molybdenum wire component.
  • the fixture to the right that supports the molybdenum moves to the left so that the two wire components abut each other at ends that face each other.
  • the fixture 112 is held in such a manner that sufficient contact force is applied between the abutting ends of the wire components.
  • this force to the fixture is applied by a compression spring that constitutes the drive 120 interposed between a fixed stop 140 and the left hand side of the 'V' support 112.
  • the force is applied by a linear motor.
  • the contact force is applied by a moving coil actuator or voice coil actuator.
  • One suitable source for a moving coil actuator is SMAC of Carlsbad, California.
  • the force is applied to the "V" support is by a pneumatic drive. In the embodiment that uses a spring, the force of engagement can be adjusted by means of a manual spring compression control.
  • the welding of the molybdenum wire component M to the niobium wire component N is preferably performed by two ND:YAG lasers beams 142 (only one of which is shown in the Figure 4E depiction) spaced from the fixtures so that laser beams emanating from the lasers merge at the weld region "X" where the wire components abut each other.
  • the laser beams form an angle of from about 135 degrees to 170 degrees to each other and are normal to the axial axis of the wire components. In an alternate embodiment of the invention, there are three laser beams and they are equally spaced about the region of wire component abutment so that their included angle is 120 degrees.
  • a relatively short pulse (approx 7 milliseconds) of laser energy is concentrated in the region where the wires abut one another to weld the wires together.
  • the laser beams 142 are aligned to the Molybdenum side 130b of the reference stop 130.
  • a cover gas is applied to the weld junction region by a conduit 144 positioned between the angled laser beams 142 to prevent oxidation of the weld region and resulting embrittlement of that junction.
  • a 1 ⁇ 4" ID stainless steel tube/pipe with an exit end held about 3/8 -1/2" above weld junction is suitable.
  • the cover gas can be either pure argon or a forming gas that is a mixture of nitrogen and hydrogen. The cover gas flows long enough after welding to cool the weld junction to prevent oxidation, typically between 1 and 2 seconds.
  • a hard stop 150 limits the overall travel of the fixture 112 to a displacement gap of between 0.001 inch and 0.002 inch from the point the two wire components first contact each other.
  • a linear motor can be used to limit travel to no more than 0.001- 0.002 inches past the region of wire components first come into contact.
  • a moving coil actuator would be programmed not to exceed specified (0.001-0.002 inch) displacement limits once melting occurs during welding.
  • a dial indicator with a sufficiently adequate spring is preset to the displacement desired, with the niobium and molybdenum wire components in contact end to end.
  • the moveable fixture can only move to the preset tension (or less), as no more linear force can be applied (spring fully relaxed or limited).
  • FIGS 5A - 5G illustrate a work station 110a constructed with an alternate embodiment of the invention.
  • like reference characters are used for components also depicted above with reference to Figures 4A - 4G.
  • the fixtures 112,114 define 'V' shaped grooves to accommodate the wire components M, N.
  • the fixtures 112, 114 move vertically down in the direction indicated by the arrows 160, 161 such that the completed welded wire component (N-M) is placed upon a pair of transfer wheels 170, 171, having spaced notches around its periphery. The wheels rotate the lead (N-M) out of the work area and drop it onto a separate conveyor.
  • the completed lead is transferred out of the fixtures via a walking beam transfer system.
  • a walking beam has a box pattern motion. For example, two vertical fingers would move up (vertical) to pick the lead wire out of the fixtures, then it would move horizontally, away from the fixture, a set distance and then move down. (vertically to the starting level) Then it would move horizontally back to the starting position.
  • the two part lead wire can now be inspected prior to delivery to a second weld station 111 depicted in Figures 6A - 6G.
  • the steps in forming the weld between the tungsten tip T and the molybdenum portion of the already completed two part lead (N-M) are depicted in Figures 6A - 6G.
  • This second weld step takes place after the first weld joint between the wire components N, M has been inspected and two part components having malformed weld joints are discarded.
  • the exemplary embodiment of the invention has a third V groove fixture 212 for the two part component (N-M) and a clam shell support fixture 214 for the tungsten tip T.
  • the clamshell has two internally nesting "V"s that accurately hold/align the tip T.
  • the two fixtures 212, 214 are aligned such that the centerlines of the respective components loaded into the support fixtures 212, 214 are held concentric to one other within an accuracy of 0.0005 inch.
  • the two component wire (N-M) is fed via vibratory linear inline feeders having tracks leading to the fixture 212. Alternate structure for feeding the wire components into the fixtures can be used.
  • the vibratory feeder moves the wire component into the 'V' shaped support until the wire component contact a moveable stop 230.
  • the support fixture 214 moves the tip T so that an exposed end of the tip T engages an opposite side of the moveable stop 230.
  • hold down fingers 232 are activated to hold the component (N-M) in place within the V groove 215 of its support fixture 212.
  • the hold down fingers ( Figure 6B) engage a top surface of the wire components to create a three point contact.
  • the hold down fingers are most preferably either knurled or seriated on their contact surfaces to prevent the components axial movement relative to the 'V' shaped fixtures.
  • Alternate wire component hold down means may utilize a clamp that extends the length of the fixture instead of spaced apart fingers.
  • the second support fixture 214 includes a clamshell pivoting type hold down structure.
  • the vertical stop 230 is retracted out of the way ( Figure 6C).
  • the tungsten tip T that is secured to the right hand fixture 214 is moved to the left until its exposed end contacts the overhanging molybdenum wire of the two part lead component N-M.
  • this fixture is held in such a manner that sufficient contact force is applied between the abutting ends of the wire components T, N-M.
  • the interface between the molybdenum and tungsten wire melts during welding by two or more laser beams 242 but a consistent force is applied to the fixture to avoid neckdown of the weld region formed as the ends melt.
  • this force to the moveable fixture 214 is applied by a spring, or linear motor (not shown).
  • a hard stop 250 limits the overall travel of the fixture 214 to between 0.001 inch and 0.002 inch from the point the two wire components T, N-M first contact each other.
  • the motion of the clamshell fixture 214 to make contact with the molybdenum can be cam lever, pneumatic cylinder or linear motor/voice coil.
  • a spring with hard stop and helper spring dial indicator can also be used to limit movement.
  • the tip T is welded to the Molybdenum part of the two part component N-M and the displacement during this process is limited in a similar manner to the movement depicted in Figures 4A - 4G.
  • the hold down fingers 232 are opened and the fixture 214 is opened by pivoting one half 214a of the clam shell open to release the tip T.
  • the completed three part electrode 16 is removed via a pair of notched rollers 270, 271 that are moved up to engage the electrode 16. Once a completed electrode has been contacted the rollers are rotated so that the completed electrode 16 is moved to a separate conveyor. In alternate embodiments the completed electrode is removed with a walking beam mechanism. In either embodiment a visual inspection of the now completed lead is performed so that faulty welds of the tip to the molybdenum can be performed.
  • FIGS 7A - 7G depict an alternative system for forming a lead wire having at least two wire components which are welded together.
  • a workstation 310 includes two supports or fixtures 312, 314.
  • One fixture 312 supports a first wire component N and a second, stationary fixture 314 that supports a second wire component M in an axially aligned arrangement with respect to the first wire component.
  • a first drive moves the first fixture with its first wire component N in a direction indicated by a first arrow 321 in Figure 7A and a second drive moves the second fixture 314 in the direction of an arrow 322 along the common axis until facing ends of the first and second axially aligned wire components contact each other.
  • the fixtures 312, 314 have V grooves extending along the length of each fixture to align the centerlines of their respective components N, M loaded into the supports 312, 314 concentric to one another within an accuracy of 0.0005 inch. Both fixtures are attached to linear slides having low inertia that allows it to move toward a weld zone between the fixtures with low friction.
  • a second alternate embodiment of the invention may have a clam shell pivoting type hold down structure.
  • the vertical stops 330, 331 are retracted out of the way ( Figure 4C).
  • the left hand fixture 312 and the niobium wire component N that is secured to the left hand fixture are moved to the right.
  • the molybdenum fixture 314 is moved to the left toward the fixture 312 and is held in place with a hard stop 315 positioned such that the molybdenum wire end facing the niobium wire is aligned to the laser beam or laser beams.
  • the interface between the molybdenum and niobium wire components melts during welding but a consistent force is applied to the two fixtures to avoid neckdown of the weld region formed as the ends melt.
  • the force is applied by a linear motor.
  • the contact force is applied by a moving coil actuator or voice coil actuator.
  • a moving coil actuator is SMAC of Carlsbad, California.
  • Another means would be to employ a spring and hard stop mechanism.
  • the molybdenum fixture 314 is held fast against its hard stop 315 by a cam lever, pneumatic cylinder or linear motor. As shown in Figure 7E the parts are then laser welded as a cover gas is sent to the region prior to and after welding for two seconds. Once the weld is complete the gripper jaws 332, 334 open and the fixtures 312, 314 rotate 180 degrees to unload the two part lead wire onto a conveyor.
  • Figure 8 discloses delivery stations for moving the wire to a weld station 110 such as the weld station of Figure 4A - 4G.
  • a niobium wire feeder bowl 350 and a molybdenum wire feeder bowl 352 are supported to deliver lengths of wire to respective in line vibrabory feeders 360, 362 which push an endmost portion of their respective wires against a stop 354, 356.
  • the niobium wire is placed on a first conveyor 370 and the molybdenum wire is placed on a second conveyor 372. These conveyors deliver the wire components to the work station 110 for welding.
  • a pusher assembly (rather than a vibratory feeder) delivers the wire components N, M to the work station 110 by pushing individual wires onto their respective fixtures 112, 114.
  • Walking beams 410, 411 deliver welded two component leads N-M to a single conveyor 420 for inspection.
  • the disclosed process of forming a lead wire can be modified to use resistive welding to join the components provided that sufficient insulation is provided to insulate the fixtures and bearing for supporting the moveable fixture from welding flux needed at the weld region between wire components.
  • Plasma welding and ultrasonic welding are other alternative welding processes that can be used in conjunction with the invention.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Wire Processing (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)

Abstract

Method and apparatus for forming a wire lead of a ceramic metal halide lamp. At least two wire components (N, M) are welded together to form the lead. Most preferably a three wire component is formed from tungsten, niobium, and molybdenum wires. A weld junction is formed by supporting first and second wire components in first and second wire supports (112, 114) that axially align the wire components along a common axis. A moveable wire (112) support is moved in a direction of the common axis until facing ends of the first and second wire components contact each other. While maintaining a force of engagement between the facing ends of the first and second wire components, a weld joint is formed to join the first and second wire components. After inspecting the first such joint, a second joint is formed to produce the three wire lead. This last joint is most preferably used to add a tungsten tip to an already formed niobium-molybdenum wire component (NM).

Description

  • The present invention concerns a system for fabricating a lead wire for a Ceramic Metal Halide Lamp constructed of three constituent wire components.
  • Figure 1 is a depiction of a prior art Ceramic Metal Halide Lamp 10. A metal base 11 defines circumferentially extending threads for connecting the lamp 10 to a socket which supplies an energizing voltage to the lamp. The lamp includes a clear outer jacket 12 coupled to the base and having an interior that has been evacuated to a specified pressure and may optionally include nitrogen gas as an added component. Mounted to the base in a generally central position is an arc tube 13 filled with an ionizable metal halide material. In order to initiate and sustain light emission from the arc tube 13 a voltage difference is applied between two electrodes or leads 14, 16 which extend into the arc tube. The arc tube 13 is a ceramic material and for example may be molded from an aluminum oxide so that necked down regions 13a, 13b of the tube form a seal about the leads 14, 16.
  • Each of the leads 14, 16 (Figure 3) includes a tungsten tip T having an encircling coil end T' (Figure 3). The tungsten tip T is attached at one end to a molybdenum wire segment M having an outer coiled winding, which in turn is attached to a Niobium wire segment N. The three segments or components T, M, N together make up a wire lead which when energized with an appropriate signal ignites and maintains light emission from the ionizable material inside the arc tube 13. Figure 3 is a depiction on an enlarged scale of such a lead 16. The diameter of the niobium wire component having uniform cross section is about 0.025 inches but can be varied depending on the lamp into which it is mounted.
  • Currently Ceramic Metal Halide Lamp lead wires are manufactured on a turret style machine that has twelve fixtures. The machine loads three wire components T,M,N axially into the fixtures and attaches them at two weld junctions between the lead wire components. Due to variations from fixture to fixture, component length tolerance stack up and lack of controlled displacement means, a percentage of the molybdenum and niobium welds exceed a maximum allowable width. Since all three wire components T, M, N are welded in a single fixture, the relatively expensive tungsten tip of this defectively formed lead must be discarded along with the molybdenum and niobium components.
  • The present invention includes apparatus for manufacturing a wire lead having at least two wire components which are welded at facing ends of the wire components. The apparatus includes a first support for supporting a first wire component and a second support for supporting a second component. The supports are positioned to axially align the two wire components for welding.
  • A drive moves the first support with its first wire component along a travel path until facing ends of the first and second axially aligned wire components contact each other. In the exemplary embodiment of the invention the drive maintains a force of engagement between the facing ends of the first and second wire components as the two wire components are welded together to form a two component wire lead.
  • Practice of the invention negates component length variation due to the way the components are accurately positioned when they are loaded into their respective alignment fixtures. In accordance with the exemplary process, the less expensive molybdenum-niobium weld is first made and inspected prior to welding the more expensive tungsten tip. The fixture provides a means to limit axial displacement or follow through during welding which helps control the diameter of a weld knot formed during welding.
  • These and other advantages and features of the invention are explained in further detail in the accompanying detailed description of a preferred embodiment of the invention which is described in conjunction with the accompanying drawings, in which:
  • Figure 1 is a perspective view of a metal halide lamp;
  • Figure 2 is section view of a ceramic metal halide arc tube having electrodes or leads that extend into an interior of the arc tube;
  • Figure 3 is a plan view of a electrode or lead wire constructed in accordance with the present invention;
  • Figures 4A - 4G are a sequence of depictions showing the fabrication of part of a lead wire;
  • Figures 5A - 5G are an alternative sequence of depictions showing the fabrication of part of a lead wire;
  • Figures 6A - 6G are a sequence of depictions showing a completion of the lead wire that is partially formed by the steps depicted in Figures 4A - 4G and 5A - 5G;
  • Figures 7A - 7G are a further alternative sequence of depictions showing the fabrication of part of a lead wire; and
  • Figure 8 is a schematic depiction of lead wire components as they are fed to a welding station.
  • Figures 4A - 4G, 5A - 5G and 6A - 6G depict a system for forming a lead wire having at least two wire components which are welded together. In accordance with the presently preferred embodiment of the invention there are two workstations 110, 111 for manufacturing a three component lead wire such as the lead depicted in Figure 3. Alternate embodiments of the first station 110 are depicted in the workstation 110a of Figures 5A - 5G.
  • As illustrated in Figure 4A the workstation 110 includes two supports or fixtures 112, 114. One fixture 112 supports a first wire component N and a second, stationary fixture 114 that supports a second wire component M in an axially aligned arrangement with respect to the first wire component. A drive 120 moves the first fixture with its first wire component N in a direction indicated by an arrow 121 in Figure 4D of the common axis until facing ends of the first and second axially aligned wire components contact each other. The drive 120 maintains a force of engagement between the facing ends of the first and second wire components M, N as the facing ends are welded together to form a wire lead from the first and second wire components. A cam actuated lever or a pneumatic cylinder can be used to secure the fixture 112 while the wire is moved into place. Such a mechanism would release the fixture 112 and allow the drive 120 to provide follow through during welding.
  • In accordance with the exemplary embodiment of the invention, the fixtures 112, 114 have V grooves 115 extending along the length of each fixture to align the centerlines of their respective components N, M loaded into the supports 112, 114 concentric to one another within an accuracy of 0.0005 inch. One 'V' fixture 112 is attached to a linear slide 122 having low inertia that allows it to move toward and away from the stationary 'V' fixture 114 with low friction. A niobium wire component N is fed onto the left hand 'V' fixture while the molybdenum component is fed onto the right hand 'V' fixture. The two wire components are fed via vibratory linear inline feeders, which are schematically depicted by two arrows 128, 129 having tracks leading to the fixtures so that an endmost wire component is pushed into a fixture by a next succeeding wire component in the feeder. It should be apparent to those skilled in the art that alternate structure for feeding the wire components into the fixtures can be used.
  • The vibratory in line feeders 128, 129 move the wire components into the 'V' shaped support until the wire components contact a moveable stop 130 so that facing ends of the wire components engage opposite sides 130a, 130b of the moveable stop. While the back pressure from the respective linear feeders pushes the two components against the vertical stop, two sets of hold down fingers 132, 134 are activated to hold the wire components in place within their respective 'V' shaped supports. The hold down fingers 132, 134 (Figure 4B) engage a top surface of the wire components to create a three point contact. The hold down fingers are most preferably either knurled or serrated on their contact surfaces to prevent axial movement of the components N, M relative to the 'V' shaped fixtures. Alternate wire component hold down means may utilize a clamp that extends the length of the fixture instead of spaced apart fingers. A second alternate embodiment of the invention may have a clam shell pivoting type hold down structure.
  • To allow facing ends of the wire components to be brought into engagement for welding, the vertical stop 130 is retracted out of the way (Figure 4C). The left hand fixture 112 and the niobium wire component N that is secured to the left hand fixture are moved to the right until an overhanging right end of the niobium wire component contacts the exposed end of the molybdenum wire component. In an alternate embodiment of the invention the fixture to the right that supports the molybdenum moves to the left so that the two wire components abut each other at ends that face each other.
    In the exemplary embodiment wherein the left hand fixture moves, the fixture 112 is held in such a manner that sufficient contact force is applied between the abutting ends of the wire components. The interface between the molybdenum and niobium wire components melts during welding but a consistent force is applied to the fixture to avoid neckdown of the weld region formed as the ends melt. In the exemplary embodiment of the invention, this force to the fixture is applied by a compression spring that constitutes the drive 120 interposed between a fixed stop 140 and the left hand side of the 'V' support 112. In an alternate embodiment of the invention the force is applied by a linear motor. In another alternate embodiment of the invention the contact force is applied by a moving coil actuator or voice coil actuator. One suitable source for a moving coil actuator is SMAC of Carlsbad, California. In another alternate embodiment of the invention the force is applied to the "V" support is by a pneumatic drive. In the embodiment that uses a spring, the force of engagement can be adjusted by means of a manual spring compression control.
  • The welding of the molybdenum wire component M to the niobium wire component N is preferably performed by two ND:YAG lasers beams 142 (only one of which is shown in the Figure 4E depiction) spaced from the fixtures so that laser beams emanating from the lasers merge at the weld region "X" where the wire components abut each other. The laser beams form an angle of from about 135 degrees to 170 degrees to each other and are normal to the axial axis of the wire components. In an alternate embodiment of the invention, there are three laser beams and they are equally spaced about the region of wire component abutment so that their included angle is 120 degrees. A relatively short pulse (approx 7 milliseconds) of laser energy is concentrated in the region where the wires abut one another to weld the wires together. The laser beams 142 are aligned to the Molybdenum side 130b of the reference stop 130.
  • A cover gas is applied to the weld junction region by a conduit 144 positioned between the angled laser beams 142 to prevent oxidation of the weld region and resulting embrittlement of that junction. A ¼" ID stainless steel tube/pipe with an exit end held about 3/8 -1/2" above weld junction is suitable. The cover gas can be either pure argon or a forming gas that is a mixture of nitrogen and hydrogen. The cover gas flows long enough after welding to cool the weld junction to prevent oxidation, typically between 1 and 2 seconds. As the weld junction melts during application of energy from the lasers, the left "V" fixture continues to be pushed by the drive 120 toward the right (molybdenum) fixture to produce a good weld that does not neck down in the weld region. A hard stop 150 limits the overall travel of the fixture 112 to a displacement gap of between 0.001 inch and 0.002 inch from the point the two wire components first contact each other. In another embodiment of the present invention, a linear motor can be used to limit travel to no more than 0.001- 0.002 inches past the region of wire components first come into contact. In an alternate embodiment of the invention, a moving coil actuator would be programmed not to exceed specified (0.001-0.002 inch) displacement limits once melting occurs during welding. In another alternate embodiment a dial indicator with a sufficiently adequate spring is preset to the displacement desired, with the niobium and molybdenum wire components in contact end to end. During welding, the moveable fixture can only move to the preset tension (or less), as no more linear force can be applied (spring fully relaxed or limited). There may be other embodiments of limiting the follow through or displacement, which are based on the aforementioned examples.
  • After the weld is made the hold down fingers are moved out of contact with their respective leads (See Figure 4F). Next, the two fixtures 112, 114 simultaneously rotate about an axis of rotation and drop the completed two-part lead onto a transfer device (Figure 4G).
  • Figures 5A - 5G illustrate a work station 110a constructed with an alternate embodiment of the invention. In Figures 5A - 5G like reference characters are used for components also depicted above with reference to Figures 4A - 4G. In this alternate embodiment the fixtures 112,114 define 'V' shaped grooves to accommodate the wire components M, N. In this embodiment the fixtures 112, 114 move vertically down in the direction indicated by the arrows 160, 161 such that the completed welded wire component (N-M) is placed upon a pair of transfer wheels 170, 171, having spaced notches around its periphery. The wheels rotate the lead (N-M) out of the work area and drop it onto a separate conveyor. In an alternate embodiment of the invention, the completed lead is transferred out of the fixtures via a walking beam transfer system. A walking beam has a box pattern motion. For example, two vertical fingers would move up (vertical) to pick the lead wire out of the fixtures, then it would move horizontally, away from the fixture, a set distance and then move down. (vertically to the starting level) Then it would move horizontally back to the starting position. The two part lead wire can now be inspected prior to delivery to a second weld station 111 depicted in Figures 6A - 6G.
    The steps in forming the weld between the tungsten tip T and the molybdenum portion of the already completed two part lead (N-M) are depicted in Figures 6A - 6G. This second weld step takes place after the first weld joint between the wire components N, M has been inspected and two part components having malformed weld joints are discarded.
  • The exemplary embodiment of the invention has a third V groove fixture 212 for the two part component (N-M) and a clam shell support fixture 214 for the tungsten tip T. The clamshell has two internally nesting "V"s that accurately hold/align the tip T. The two fixtures 212, 214 are aligned such that the centerlines of the respective components loaded into the support fixtures 212, 214 are held concentric to one other within an accuracy of 0.0005 inch. The two component wire (N-M) is fed via vibratory linear inline feeders having tracks leading to the fixture 212. Alternate structure for feeding the wire components into the fixtures can be used.
  • The vibratory feeder moves the wire component into the 'V' shaped support until the wire component contact a moveable stop 230. The support fixture 214 moves the tip T so that an exposed end of the tip T engages an opposite side of the moveable stop 230. While the back pressure from the respective linear feeder pushes the two component wire (N-M) against the vertical stop230, hold down fingers 232 are activated to hold the component (N-M) in place within the V groove 215 of its support fixture 212. The hold down fingers (Figure 6B) engage a top surface of the wire components to create a three point contact. The hold down fingers are most preferably either knurled or seriated on their contact surfaces to prevent the components axial movement relative to the 'V' shaped fixtures. Alternate wire component hold down means may utilize a clamp that extends the length of the fixture instead of spaced apart fingers. The second support fixture 214 includes a clamshell pivoting type hold down structure.
  • To allow facing ends of the wire components to be brought into engagement for welding, the vertical stop 230 is retracted out of the way (Figure 6C). The tungsten tip T that is secured to the right hand fixture 214 is moved to the left until its exposed end contacts the overhanging molybdenum wire of the two part lead component N-M.
  • In the exemplary embodiment wherein the right hand fixture 214 moves, this fixture is held in such a manner that sufficient contact force is applied between the abutting ends of the wire components T, N-M. The interface between the molybdenum and tungsten wire melts during welding by two or more laser beams 242 but a consistent force is applied to the fixture to avoid neckdown of the weld region formed as the ends melt. In the exemplary embodiment of the invention, this force to the moveable fixture 214 is applied by a spring, or linear motor (not shown). A hard stop 250 limits the overall travel of the fixture 214 to between 0.001 inch and 0.002 inch from the point the two wire components T, N-M first contact each other. The motion of the clamshell fixture 214 to make contact with the molybdenum can be cam lever, pneumatic cylinder or linear motor/voice coil. A spring with hard stop and helper spring dial indicator can also be used to limit movement.
  • The tip T is welded to the Molybdenum part of the two part component N-M and the displacement during this process is limited in a similar manner to the movement depicted in Figures 4A - 4G. After the weld is made the hold down fingers 232 are opened and the fixture 214 is opened by pivoting one half 214a of the clam shell open to release the tip T. The completed three part electrode 16 is removed via a pair of notched rollers 270, 271 that are moved up to engage the electrode 16. Once a completed electrode has been contacted the rollers are rotated so that the completed electrode 16 is moved to a separate conveyor. In alternate embodiments the completed electrode is removed with a walking beam mechanism. In either embodiment a visual inspection of the now completed lead is performed so that faulty welds of the tip to the molybdenum can be performed.
  • Figures 7A - 7G depict an alternative system for forming a lead wire having at least two wire components which are welded together. In this embodiment as illustrated in Figure 7A a workstation 310 includes two supports or fixtures 312, 314. One fixture 312 supports a first wire component N and a second, stationary fixture 314 that supports a second wire component M in an axially aligned arrangement with respect to the first wire component. A first drive moves the first fixture with its first wire component N in a direction indicated by a first arrow 321 in Figure 7A and a second drive moves the second fixture 314 in the direction of an arrow 322 along the common axis until facing ends of the first and second axially aligned wire components contact each other.
  • In accordance with the exemplary embodiment of the invention, the fixtures 312, 314 have V grooves extending along the length of each fixture to align the centerlines of their respective components N, M loaded into the supports 312, 314 concentric to one another within an accuracy of 0.0005 inch. Both fixtures are attached to linear slides having low inertia that allows it to move toward a weld zone between the fixtures with low friction.
  • In line feeders move the wire components into the 'V' shaped support until the wire components contact moveable stops 330, 331 so that facing ends of the wire components engage opposite sides of the moveable stops 330, 331. While the back pressure from the respective linear feeders pushes the two components against the vertical stop, two sets of hold down fingers 332, 334 are activated to hold the wire components in place within their respective 'V' shaped supports. The hold down fingers 332, 334 (Figure 7B) engage a top surface of the wire components to create a three point contact. The hold down fingers are most preferably either knurled or serrated on their contact surfaces to prevent axial movement of the components N, M relative to the 'V' shaped fixtures. Alternate wire component hold down means may utilize a clamp that extends the length of the fixture instead of spaced apart fingers. A second alternate embodiment of the invention may have a clam shell pivoting type hold down structure.
  • To allow facing ends of the wire components to be brought into engagement for welding, the vertical stops 330, 331 are retracted out of the way (Figure 4C). The left hand fixture 312 and the niobium wire component N that is secured to the left hand fixture are moved to the right. The molybdenum fixture 314 is moved to the left toward the fixture 312 and is held in place with a hard stop 315 positioned such that the molybdenum wire end facing the niobium wire is aligned to the laser beam or laser beams. The interface between the molybdenum and niobium wire components melts during welding but a consistent force is applied to the two fixtures to avoid neckdown of the weld region formed as the ends melt.
  • Several methods of displacement control can be used. In one embodiment of the invention the force is applied by a linear motor. In another alternate embodiment of the invention the contact force is applied by a moving coil actuator or voice coil actuator. One suitable source for a moving coil actuator is SMAC of Carlsbad, California. Another means would be to employ a spring and hard stop mechanism. The molybdenum fixture 314 is held fast against its hard stop 315 by a cam lever, pneumatic cylinder or linear motor.
    As shown in Figure 7E the parts are then laser welded as a cover gas is sent to the region prior to and after welding for two seconds. Once the weld is complete the gripper jaws 332, 334 open and the fixtures 312, 314 rotate 180 degrees to unload the two part lead wire onto a conveyor.
  • Figure 8 discloses delivery stations for moving the wire to a weld station 110 such as the weld station of Figure 4A - 4G. A niobium wire feeder bowl 350 and a molybdenum wire feeder bowl 352 are supported to deliver lengths of wire to respective in line vibrabory feeders 360, 362 which push an endmost portion of their respective wires against a stop 354, 356. The niobium wire is placed on a first conveyor 370 and the molybdenum wire is placed on a second conveyor 372. These conveyors deliver the wire components to the work station 110 for welding. In the embodiment shown in figure 8 a pusher assembly (rather than a vibratory feeder) delivers the wire components N, M to the work station 110 by pushing individual wires onto their respective fixtures 112, 114. Walking beams 410, 411 deliver welded two component leads N-M to a single conveyor 420 for inspection.
  • The disclosed process of forming a lead wire can be modified to use resistive welding to join the components provided that sufficient insulation is provided to insulate the fixtures and bearing for supporting the moveable fixture from welding flux needed at the weld region between wire components. Plasma welding and ultrasonic welding are other alternative welding processes that can be used in conjunction with the invention.
  • For completeness, various aspects of the invention are set out in the following numbered clauses:
  • 1. A method of forming a wire lead having at least two wire components which are welded together to form the lead comprising the steps of:
  • a) supporting first and second wire components (N, M) in first and second wire supports (112, 114) that axially align the wire components along a common axis;
  • b) moving a moveable wire support (112) of at least one of the first and second wire supports in a direction of the common axis until facing ends of the first and second wire components (N, M) contact each other;
  • c) maintaining a force of engagement between the facing ends of the first and second wire components (N, M) ; and
  • d) welding the facing ends together to form a wire lead from the first and second wire components.
  • 2. The method of clause 1 wherein energy is provided to a weld region (X) where the first and second wire components are maintained in contact.
  • 3. The method of clause 1 wherein the moveable wire support (112) is coupled to a bearing (122) and wherein the step of maintaining the force of engagement between facing ends of said wire components is performed by biasing the moveable wire support.
  • 4. The method of clause 1 additionally comprising the step of feeding at least one of the wire components to the first and second wire supports by an automated feeder (128) and wherein movement of the at least one wire component within a travel path through its support is limited by an end of travel stop (130).
  • 5. The method of clause 4 wherein the automated feeder is a vibratory feeder.
  • 6. The method of clause 4 additionally comprising the step of clamping the wire components in place within a concave region (115) of the supports once the wire components have engaged the end of travel stop.
  • 7. The method of clause 6 wherein one side of the end of travel stop (130) precisely positions one end of a stationary wire component to define a weld region (X) once the second wire component moves into engagement with the first.
  • 8. The method of clause 7 wherein one side of the travel stop (130) defines a position for directing a laser beam (142) for forming the weld.
  • 9. The method of clause 1 additionally comprising the step of forming a junction between a third wire component (T) and the combination (N-M) of said first and second wire components.
  • 10. The method of clause 9 wherein before forming the junction with the third wire component, a weld junction between the first and second wire components is inspected.
  • 11. The method of clause 9 wherein the first wire component (N) comprises niobium, the second wire component comprises molybdenum (M), and the third wire component comprises tungsten (T).
  • 12. The method of clause 1 wherein during the step of maintaining the force of engagement an extent of movement of the moveable wire support is limited to help maintain the weld junction.
  • 13. Apparatus for forming a wire lead having at least two wire components which are welded together comprising:
  • a) two supports (112, 114), one support for supporting a first wire component (N) and a second support for supporting a second wire component (M) in an axially aligned arrangement with respect to the first wire component;
  • b) a drive (120) for moving the first support with its first wire component in a direction of the common axis until facing ends of the first and second axially aligned wire components contact each other wherein said drive maintains a force of engagement between the facing ends of the first and second wire components; and
  • c) structure (142) for welding the facing ends together to form a wire lead from the first and second wire components.
  • 14. The apparatus of clause 13 additionally comprising a conduit (144) for routing a gas into a region of a weld.
  • 15. The apparatus of clause 13 wherein the drive comprises a drive motor for moving the first support relative to a stationary support.
  • 16. The apparatus of clause 13 additionally comprising a hold down clamp (132, 134) for holding the first and second wire components in place within the first and second supports (112, 114).
  • 17. The apparatus of clause 13 wherein the drive (120) comprises a spring for moving the first support relative to the stationary support.
  • 18. The apparatus of clause 13 additionally comprising a transfer device (170, 171) for moving the wire lead away from the workstation.
  • 19. The apparatus of clause 13 wherein the structure for welding comprises one or more lasers.
  • 20. The apparatus of clause 13 wherein one of said two supports comprises a pivotal member (214) for holding an associated wire component during welding and for then releasing the wire component after welding.
  • 21. The apparatus of clause 13 comprising a component delivery structure for moving the first and second wire components into the respective supports and a spacer stop (130) for limiting movement of the wire components by the component delivery structure.
  • 22. The apparatus of clause 21 wherein one side of the spacer stop defines a weld junction (X).
  • 23. The apparatus of clause 13 further comprising a limit stop (150) for limiting movement of the wire component during a process of welding.
  • 24. The apparatus of clause 13 wherein both supports (312, 314) are mounted for movement along respective travel paths and further including first and second drives for moving the supports toward each other along their respective travel paths for welding two wire components carried by the supports.
  • 25. The apparatus of clause 24 further including first and second reference stops (330, 331) for positioning the wire components within the supports.
  • 26. The apparatus of clause 25 further including a hard stop (315) for positioning one of the first and second supports with respect to the laser beams to define a laser weld position.

Claims (10)

  1. A method of forming a wire lead having at least two wire components which are welded together to form the lead comprising the steps of:
    a) supporting first and second wire components (N, M) in first and second wire supports (112, 114) that axially align the wire components along a common axis;
    b) moving a moveable wire support (112) of at least one of the first and second wire supports in a direction of the common axis until facing ends of the first and second wire components (N, M) contact each other;
    c) maintaining a force of engagement between the facing ends of the first and second wire components (N, M); and
    d) welding the facing ends together to form a wire lead from the first and second wire components.
  2. The method of claim 1 wherein energy is provided to a weld region (X) where the first and second wire components are maintained in contact.
  3. The method of claim 1 wherein the moveable wire support (112) is coupled to a bearing (122) and wherein the step of maintaining the force of engagement between facing ends of said wire components is performed by biasing the moveable wire support.
  4. The method of claim 1 additionally comprising the step of feeding at least one of the wire components to the first and second wire supports by an automated feeder (128) and wherein movement of the at least one wire component within a travel path through its support is limited by an end of travel stop (130).
  5. The method of claim 1 additionally comprising the step of forming a junction between a third wire component (T) and the combination (N-M) of said first and second wire components.
  6. Apparatus for forming a wire lead having at least two wire components which are welded together comprising:
    a) two supports (112, 114), one support for supporting a first wire component (N) and a second support for supporting a second wire component (M) in an axially aligned arrangement with respect to the first wire component;
    b) a drive (120) for moving the first support with its first wire component in a direction of the common axis until facing ends of the first and second axially aligned wire components contact each other wherein said drive maintains a force of engagement between the facing ends of the first and second wire components; and
    c) structure (142) for welding the facing ends together to form a wire lead from the first and second wire components.
  7. The apparatus of claim 6 additionally comprising a hold down clamp (132, 134) for holding the first and second wire components in place within the first and second supports (112, 114).
  8. The apparatus of claim 6 wherein one of said two supports comprises a pivotal member (214) for holding an associated wire component during welding and for then releasing the wire component after welding.
  9. The apparatus of claim 6 comprising a component delivery structure for moving the first and second wire components into the respective supports and a spacer stop (130) for limiting movement of the wire components by the component delivery structure.
  10. The apparatus of claim 6 wherein both supports (312, 314) are mounted for movement along respective travel paths and further including first and second drives for moving the supports toward each other along their respective travel paths for welding two wire components carried by the supports.
EP20010304347 2000-05-16 2001-05-16 Ceramic metal halide lamp lead welding system Withdrawn EP1158557A2 (en)

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US571838 2000-05-16

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003058674A1 (en) * 2002-01-08 2003-07-17 Koninklijke Philips Electronics N.V. High-pressure discharge lamp and method of manufacturing an electrode feedthrough for such a lamp
US7018260B2 (en) * 2001-08-09 2006-03-28 Matsushita Electric Industrial Co., Ltd. Electrode, manufacturing method thereof, and metal vapor discharge lamp
EP2239761A2 (en) 2009-03-19 2010-10-13 Osram-Melco Toshiba Lighting Ltd. High-intensity discharge lamp and lighting device
CN103286244A (en) * 2012-02-24 2013-09-11 上海亚尔光源有限公司 Method for manufacturing H-shaped sodium lamp niobium tube
CN109471542A (en) * 2018-11-07 2019-03-15 合肥禾斗技汇科技有限公司 Positioning system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4569455B2 (en) * 2005-12-02 2010-10-27 パナソニック株式会社 Electrode body manufacturing method and high-pressure discharge lamp manufacturing method

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7018260B2 (en) * 2001-08-09 2006-03-28 Matsushita Electric Industrial Co., Ltd. Electrode, manufacturing method thereof, and metal vapor discharge lamp
US7057347B2 (en) * 2001-08-09 2006-06-06 Matsushita Electric Industrial Co., Ltd. Electrode, manufacturing method thereof, and metal vapor discharge lamp
WO2003058674A1 (en) * 2002-01-08 2003-07-17 Koninklijke Philips Electronics N.V. High-pressure discharge lamp and method of manufacturing an electrode feedthrough for such a lamp
EP2239761A2 (en) 2009-03-19 2010-10-13 Osram-Melco Toshiba Lighting Ltd. High-intensity discharge lamp and lighting device
EP2239761A3 (en) * 2009-03-19 2011-04-13 Osram-Melco Toshiba Lighting Ltd. High-intensity discharge lamp and lighting device
CN103286244A (en) * 2012-02-24 2013-09-11 上海亚尔光源有限公司 Method for manufacturing H-shaped sodium lamp niobium tube
CN103286244B (en) * 2012-02-24 2016-05-11 上海亚尔光源有限公司 The manufacture method of H type sodium vapor lamp niobium pipe
CN109471542A (en) * 2018-11-07 2019-03-15 合肥禾斗技汇科技有限公司 Positioning system
CN109471542B (en) * 2018-11-07 2022-08-26 合肥禾斗技汇科技有限公司 Positioning system

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