JP6648162B2 - TIG welding equipment - Google Patents

Description

  The present invention relates to a touch start type TIG welding device.

  2. Description of the Related Art Conventionally, a TIG welding method using a non-consumable torch electrode (tungsten electrode rod) is often used for joining terminal members of a small electric component or joining a terminal member and a conductor.

  In the TIG welding method using a non-consumable torch electrode, the method of starting arc discharge is a high frequency generation method that causes dielectric breakdown by high frequency discharge at the start and shifts to an arc, and a torch electrode and base material only at the start In other words, a DC high voltage application method that normally applies a high voltage of 10 kV or more between the material to be welded to cause dielectric breakdown and shift to an arc, and energization by contacting the torch electrode with the material to be welded without using high frequency There are three types of touch-start (or lift-start) systems in which the arc discharge is generated by being separated after the start. The high-frequency generation method and the direct-current high-voltage application method require a high-voltage power supply that generates a high-frequency or high-voltage, so that the cost of the welding machine is high. Negative effects on surrounding electronics are disliked at many welding sites. In this regard, the touch start method does not use a high-frequency power supply or a high-voltage power supply, so that the cost of the welding machine can be reduced and there is no problem of high-frequency noise (Patent Document 1).

JP 2000-71074 A JP 2015-128787 A JP-A-2015-208751

  However, in the touch start method, when the torch electrode comes into contact with the material to be welded from above, not only the own weight of the torch electrode, but also the own weight of the torch body holding the torch electrode, and further, the power connected to the torch body (Welding current, gas) The weight of the supply cable also adds to the material to be welded, and it is not uncommon for the total weight (hereinafter referred to as "torch load") to exceed 500 g weight. Therefore, a material having a low physical strength, such as a terminal member of a small precision electronic component, may be bent or damaged by a torch load received at the time of touch start.

  To solve this problem, conventionally, a coil spring is interposed between a torch body and a linear drive unit that moves up and down while supporting the torch body, so that the torch load is absorbed by the coil spring. The torch load applied to the welding material is reduced (see FIGS. 7 and 8 of Patent Document 2).

  However, in the above-described prior art, when the torch is moved up and down, the torch (particularly, the tip of the torch electrode) is likely to sway up and down due to the repulsion of the coil spring to absorb the torch load, thereby increasing the spring load of the coil spring. The greater the degree of shaking, the greater the degree of shaking. Therefore, in reality, the torch load can only be reduced to about 100 g weight without setting the spring load of the coil spring to be relatively low. In addition, the weight of the utility supply cable in the torch load fluctuates according to the state of the wiring near the torch body of the cable, whereby the torch load tends to fluctuate each time the touch start is repeated. Was a point.

  In the touch start method, if the torch load applied to the material to be welded is not sufficiently small, some materials with low physical strength will bend significantly without bending or breakage. Also, the quality of the arc welding is likely to be affected. In other words, when the material to be welded is largely bent by the torch load, when the torch electrode is pulled up after the energization is started by the touch start, the optimum separation distance between the tip of the torch electrode and the material to be welded returning from the bending. Is very difficult to control, and it becomes more and more difficult when the torch load varies. In applications where fine arc welding is required, it is necessary to secure an appropriate separation distance or arc length between the tip of the torch electrode and the workpiece, and if this requirement is not met, arc concentration or Heat input becomes unstable, which causes the quality of arc welding to deteriorate.

  In an automatic TIG welding apparatus, a fixing jig serving also as a torch electrode constituting one of the electrodes and a clamp electrode (also referred to as a “chuck”) also serving as the other electrode are the same or a common elevating body or a robot. An electric current is caused to flow between the torch electrode and the clamped electrode while being attached to an arm or the like and clamping the material to be welded (for example, two terminal members) by the clamp electrode, and is generated between the torch electrode and the material to be welded. A TIG welding method in which a material to be welded is melted by the heat of an arc is also performed.

  Regarding this point, in the conventional TIG welding apparatus in which the torch electrode and the clamp electrode are in a fixed positional relationship on the robot arm (Patent Document 2), when an error occurs in the positioning of the material to be welded, a subsequent error occurs. It is difficult to correct the positioning error by the clamp operation of the clamp electrode performed, and it is difficult to stably and surely generate an arc between the torch electrode and the workpiece to be welded. There is a possibility that the clamp electrode or the material to be welded may be damaged by the excessive stress generated.

  Regarding this problem, the present applicant discloses a TIG welding apparatus in which a passive type compliance device is incorporated in a movable stage for positioning a workpiece to be welded just below a welding head (Patent Document 1). 3). According to this TIG welding apparatus, when the clamp electrode performs the clamping operation, the stage-side compliance device slides following the direction in which the clamping force acts, thereby causing an error in the positioning of the workpiece. Therefore, the tip of the torch electrode always accurately faces the center or the contact portion of the material to be welded, so that the touch-start type TIG welding using the clamp electrode can be stably performed with high quality.

  However, in a TIG welding apparatus that incorporates a passive type compliance device into a movable stage, the compliance of the compliance device greatly changes depending on the weight of the workpiece. In particular, when the weight of the material to be welded is so large that the compliance device cannot smoothly follow the movement, the clamp electrode cannot complete the clamping operation, and thus TIG welding becomes substantially infeasible. There is also.

  The present invention solves the above-mentioned problems of the prior art, and greatly improves the reduction and stability of a torch load applied to a material to be welded in a touch start method. Provided is a TIG welding apparatus that can always perform a stable and accurate clamping operation irrespective of the weight or bulkiness of a material side and improve the quality of TIG welding.

The TIG welding apparatus according to the present invention provides a tubular torch body which detachably mounts and holds a torch electrode, and conducts electricity between the tip of the torch electrode and a workpiece to be welded in a touch start method, or generates an arc. A welding power source for causing a current to flow in a closed circuit including the torch electrode and the material to be welded, and a linearly movable body around the torch body in a first direction parallel to an axis of the torch body. A straight-moving section provided, a straight-moving drive section for moving the straight-moving section straight in the first direction, and a straight-moving section provided between the straight-moving section and the torch body; A first spring member for applying a spring load toward the workpiece in a first direction; and a first spring member provided between the linearly movable portion and the torch body, the first torch body being welded to the torch body in the first direction. Lumber A second spring member for applying a spring load in a direction opposite to that of the first movable member, and a lock portion for arbitrarily fixing the torch body to the linearly movable portion against the first and second spring members. And a torch load adjusting unit for variably adjusting a total combined load obtained by subtracting a spring load of the second spring member from a sum of a weight of the torch body and a spring load of the first spring member. Having.

In the above device configuration, the spring load of the first spring member and the spring load of the second spring member are made to oppose each other with respect to the torch body, and the total combination of the first and second spring members is performed by the torch load adjustment unit . By making the load adjustable, the touch operation for touch start and the torch electrode lifting (arc generation) operation immediately after touch start can be performed quickly and stably, and the total synthesis of the torch body added to the material to be welded The load can be arbitrarily adjusted to a small load.

  ADVANTAGE OF THE INVENTION According to the TIG welding apparatus of this invention, the reduction and stability of the torch load added to a to-be-welded material in a touch start system are greatly improved by the above structure and effect | action, and when using a clamp electrode, a to-be-welded material The quality of the TIG welding can be improved by always performing a stable and accurate clamping operation regardless of the side weight or bulkiness.

It is a perspective view showing a welding head of a TIG welding device in one embodiment of the present invention. It is a perspective view which shows the main body unit of the said TIG welding apparatus. It is a longitudinal cross-sectional view which shows the structure around the torch and the utility relay part in the said welding head. It is a longitudinal section showing the composition of the torch connection part in the above-mentioned welding head. FIG. 3 is a schematic plan view showing a configuration and a basic operation of a clamp electrode in the welding head. FIG. 3 is a schematic plan view showing a configuration and a basic operation of a clamp electrode in the welding head. It is a figure showing a state of one stage (completion of work position alignment / start of welding head lowering operation) in a TIG welding method in an embodiment. It is a figure showing the state of one stage (completion of welding head descent operation / start of clamp operation) in the TIG welding method in an embodiment. It is a figure showing the state of one stage (during the clamp operation) of the TIG welding method in an embodiment. It is a figure showing the state of one stage (completion of clamp operation / start of touch operation) of the TIG welding method in an embodiment. It is a figure showing the state of one stage (completion of a touch operation / start of energization) of the TIG welding method in an embodiment. It is a figure showing the state of one stage (pulling up of the torch electrode / during arc welding) in the TIG welding method in the embodiment. It is a figure showing the state of one stage (end of arc welding) of the TIG welding method in an embodiment. It is a figure showing a modification of the TIG welding device in an embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[Configuration of the entire device]
1 and 2 show the configurations of a welding head and a main unit of a TIG welding apparatus according to an embodiment of the present invention, respectively.

  In FIG. 1, a welding head 10 includes, as main components, a rigid rectilinear movable portion 12 made of, for example, resin or metal, and a lifting drive arm 14 coupled to the rectilinear movable portion 12 via a horizontal guide portion 13. And a torch 22 and a clamp electrode 24 which are connected to the rectilinear movable portion 12 via a torch connecting portion 18 and a clamp connecting portion 20, respectively.

  The lift drive arm 14 is a robot arm that constitutes a part of the lift drive unit 16 and extends from a main body (not shown) of the lift drive unit 16. The main body of the lifting drive unit 16 includes a drive source, for example, a servomotor, and a transmission mechanism that converts the rotational driving force of the servomotor into a linear motion in the vertical direction (Z direction) and transmits the linear movement to the lifting drive arm 14. I have.

  The horizontal guide portion 13 is configured by using a linear guide such as an LM guide (trademark), fixes the rectilinear movable portion 12 to the lifting drive arm 14 in the Z direction, and applies an external force to the rectilinear movable portion 12 in one horizontal direction, that is, the X direction. It is supported so that it can move or move freely in accordance with.

  The rectilinear movable portion 12 is configured as a block or a plate having a horizontal mounting surface 12a, and a utility relay unit 26 and a horizontal support plate 28 are mounted on the mounting surface 12a via a manual XY table 25. The torch guide 80 and the torch connecting portion 18 are attached to the horizontal support plate 28. The configuration around the utility relay section 26 and the torch connecting section 18 will be described later in detail.

  The torch 22 includes a cylindrical torch body 30 made of a conductor such as copper or brass, and a cylindrical or conical torch nozzle 32 detachably attached to a lower end of the torch body 30. A rod-shaped torch electrode (tungsten electrode rod) 34 is detachably mounted in the torch nozzle 32, and the lower end of the torch electrode 34 projects from the lower end of the torch nozzle 32. The torch electrode 34 is coupled or connected to a threaded cap 36 which is screwed to the top of the torch body 30 via an electrode holder (not shown).

  A movable stage 40 on which a work body S having a workpiece W (W1, W2) to be processed is placed just below the welding head 10. The stage 40 includes an XY stage 42 for moving the work body S in an arbitrary direction in a horizontal plane (XY plane), and a θ stage 44 for moving the work body S in an azimuthal direction (θ direction) in the horizontal plane. And Further, in order to fix the work body S on the stage 40, for example, a chuck mechanism (not shown) of a vacuum suction type or a mechanical type may be provided.

  The workpiece W shown in FIG. 1 has two elongated rod-shaped or plate-shaped metal members made of copper, for example, bus bars W1 and W2 as the workpieces (base materials), and upper end surfaces of both metal members W1 and W2. The (top) surfaces are substantially flush with each other, and their upper ends are integrally combined. The upper end portions of the metal members W1 and W2 combined together form a welded portion. The other end (not shown) of each of the metal members W1 and W2 communicates with, for example, an electric component (not shown) mounted on the work body S.

  In FIG. 1, for easy illustration, the work body S is schematically shown as a block or a box, and one workpiece W (W1, W2) of the work body S is typically shown. ing. In general, a work body S using a bus bar for electric wiring has a workpiece W at a plurality of locations, for example, at ten or more locations.

  A control box 46 is located on or near the welding head 10. The control box 46 houses a local control circuit for interfacing a part or all of various electric components provided in the welding head 10 to a main control unit in the main unit 50 (FIG. 2).

  In FIG. 2, the main unit 50 has a touch panel display 52, a power switch 54, an operation button 56, and the like disposed on the front of the unit housing, and external connection terminals or connectors 60 disposed on the side surface or the rear surface of the unit. The shielding gas delivered from the gas cylinder 62 is supplied to the torch 22 via the hose 64 and a control valve or an on-off valve in the main unit 50.

  In FIGS. 1 and 2, a plurality of cables or pipes 66, 68, 70, 75, 78... Are drawn between the main unit 50 and the welding head 10 and the stage 40. In the illustrated example, a part of the cable or the piping serves as a relay point of the control circuit in the control box 46, and the other part is connected to the control circuit or the power supply circuit in the main unit 50 and the welding head 10 without passing through the control box 46. Are directly connected to each other. In particular, in this embodiment, between the main unit 50 and the utility relay section 26 on the welding head 10, a utility supply cable 70 that houses the welding current supply line and the shielding gas supply line together is laid or suspended. . Further, between the main body unit 50 and the clamp electrode 24 on the welding head 10, a power supply line 75 for driving a clamping operation and the workpiece W are electrically connected to a ground terminal of a welding power source. Cable 78 is laid or suspended.

  Hereinafter, the configuration of each part on the welding head 10 of the TIG welding apparatus, particularly the configuration around the torch connecting part 18, the clamp electrode 24, and the utility relay part 26, which are main characteristic parts, will be described in detail.

[Configuration around torch and utility relay section]
The configuration around the torch 22 and the utility relay section 26 in this TIG welding apparatus will be described in detail with reference to FIGS.

  As shown in FIG. 1, in the welding head 10, a horizontal support plate 28 fixed on the rectilinearly movable portion 12 via a manual XY table 25 has a guide direction of the horizontal guide portion 13 with the elevation drive arm 14 as a back. It extends in a horizontal direction orthogonal to (X direction), that is, forward in the Y direction. A cylindrical torch guide 80 for guiding the torch body 30 in the Z direction is fixed to a distal end portion of the horizontal support plate 28 in a vertical posture.

  Inside the torch guide 80, two linear bushes 82H and 82L are provided with a certain space in the vertical direction or an intermediate portion therebetween (FIG. 3). By the guidance of the two linear bushes 82H, 82L, the torch body 30 can move straight and accurately in the Z direction.

  An opening 84 is formed in the middle of the torch guide 80 at a position facing the utility relay 26 (FIG. 3). A utility introduction portion 86 having a hollow block structure made of a conductor such as copper is attached to a side surface of an intermediate portion of the torch body 80 so as to be exposed to the outside through an opening 84. The utility introduction section 86 is electrically connected to the torch electrode 34 via a conductive path in the torch body 80.

  A pair of upstream gas introduction ports 88 are provided on the upper surface of the utility introduction section 86. Further, a downstream gas introduction port (not shown) connected to a gas flow path in the torch body 30 is provided on a back surface (a surface facing the torch body 30) of the utility introduction unit 86. The inside of the utility introduction section 86 is a hollow gas chamber or gas passage, and the upstream gas introduction port 88 and the downstream gas introduction port communicate with each other.

  On the other hand, the utility relay unit 26 directly fixed on the manual XY table 25 is provided with a pair of downstream gas relay ports 90 on both sides. Between the downstream gas relay port 90 and the gas introduction port 88 of the utility introduction section 86, a bridge tube 92 made of a resin that can be displaced or deformed and extends in an arch in the air. Further, a bridge-type conductor 94 of a displaceable or deformable strip-shaped sheet that extends in an arch shape in the air is bridged between mutually facing surfaces (front surfaces) of the utility relay unit 26 and the utility introduction unit 86. The crosslinked conductor 94 of the strip-shaped sheet is formed by stacking a plurality of (eg, nine) ultra-thin copper sheets having a thickness of, for example, 0.05 mm.

  A conductive upstream gas relay port 96 is provided on the upper surface of the utility relay section 26 (FIG. 3). The terminal of the utility supply cable 70 from the main unit 50 is detachably connected to the port 96. In this case, not only is the gas supply line in the utility supply cable 70 connected to the gas passage of the upstream gas relay port 96, but also the welding current supply line in the utility supply cable 70 is electrically connected to the main body of the utility relay unit 26. Connected to. The inside of the utility relay unit 26 is a hollow gas chamber or gas passage, and the upstream gas relay port 96 and the downstream gas relay port 90 communicate with each other.

  Although the utility supply cable 70 is a considerably heavy cable, since it terminates at the utility relay section 26 as described above, its weight is applied to the rectilinear movable section 12 and is not applied to the torch 22 at all. The weight of the bridge type tube 92 and the bridge type conductor 94 is applied to the torch 22. The bridge-type tube 92 and the bridge-type conductor 94 are much lighter than the utility supply cable 70, and their respective aerial postures are arched and constant, so that the torch load hardly fluctuates.

  In the utility supply system around the utility relay section 26 on the rectilinear movable section 12 and the utility introduction section 86 of the torch 22 as described above, the shielding gas sent out from the main unit 50 (FIG. 2) uses the utility supply cable 70 (gas (Supply line) → utility relay section 26 (upstream gas relay port 96 → downstream gas relay port 90) → crosslinked tube 92 → utility introduction section 86 (upstream gas introduction port 88 → downstream gas introduction port) → torch body 30 → flow through the gas flow path connected to the torch nozzle 32 in the above order. The welding current sent from the main unit 50 is supplied to the utility supply cable 70 (welding current supply line) → the utility relay section 26 (conductive block) → the bridging conductor 94 → the utility introduction section 86 (conductive block) → torch. The current flows from the body 30 to the torch electrode 34 in the above order or in the reverse order (reverse direction).

[Configuration around torch connection]
Next, a configuration around the torch body 30 and the torch connecting portion 18 in the TIG welding apparatus will be described in detail with reference to FIGS.

  The torch connecting portion 18 is provided on one side of the torch body 30 in the X direction (the right side in FIGS. 1 and 4). In the torch connecting portion 18, a rigid connecting rod 102 fixed to the torch body 30 extends horizontally to the right in the X direction in a housing 100 fixed to the horizontal support plate 28. A compression coil spring 104, a tension coil spring 106, and a lock portion 108 are provided in a horizontal line as connection means between the 102 and the ceiling of the housing 100.

  More specifically, the compression coil spring 104 extends in a vertical direction between the spring bar 112 attached to the lower end of the bar screw 110 penetrating the ceiling of the housing 100 and the connection bar 102. By turning the bar screw 110 through a nut 114 disposed outside (upper) of the housing 100, the spring receiver 112 is moved up and down according to the rotation direction, and the amount of deflection of the compression coil spring 104, that is, the spring load Can be adjusted arbitrarily. In this manner, the first torch load adjusting unit 117 for adjusting the spring load acting vertically downward on the torch body 30 is constituted by the compression coil spring 104, the bar screw 110, and the nut 114.

  The extension coil spring 106 extends in the vertical direction between the spring bar 113 attached to the lower end of the bar screw 111 penetrating the ceiling of the housing 100 and the connection bar 102. By turning the bar screw 111 via a nut 115 disposed outside (upper) of the housing 100, the spring receiver 113 is moved up and down according to the rotation direction, and the amount of deflection of the tension coil spring 106, that is, the spring load Can be adjusted arbitrarily. As described above, the tension coil spring 106, the bar screw 111, and the nut 115 constitute the second torch load adjusting unit 119 for adjusting the spring load acting vertically upward on the torch body 30.

  The lock portion 108 has any pressing means such as an air cylinder or a solenoid which can apply a constant pressing force to an object abutting on the tip of the vertically movable pressing rod 108a, that is, the connecting rod 102. A reference block 116 having a horizontal upper surface (reference surface) K is fixedly arranged at a position opposed to the pressing rod 108a with the interposition therebetween. When the lock portion 108 presses the distal end of the pressing rod 108 a against the connecting rod 102 and presses the connecting rod 102 against a fixed reference block 116 against the compression coil spring 104 and the extension coil spring 106, the torch body 30 As a result, it is fixed or integrated with the horizontal support plate 28. In this integrated state, when the elevation drive unit 16 moves the rectilinear moving unit 12 in the Z direction, the torch body 30 moves up and down integrally with the rectilinear moving unit 12.

  The torch body 30 receives a vertical downward load, which is the sum of the weight (self-weight) L30 of the entire torch body 30 including accessories such as the connecting rod 102 and the spring load L104 of the compression coil spring 104. As a result, the spring load L106 of the tension coil spring 106 is applied vertically upward. Assuming that the vertical downward load is the positive direction and the total combined load applied to the torch body 30 is TL, TL = L30 + L104−L106. Since L30 is substantially constant, L104 and L106 are variably adjusted by the first and second torch load adjusting units 117 and 119 as described above, so that total synthesis is performed in accordance with the characteristics of the workpiece W. The load TL can be adjusted arbitrarily.

  For example, when L30 is about 300 g weight, the total combined load TL is about 50 g by adjusting the L104 and L106 to about 100 g weight and about 350 g weight by the first and second torch load adjusting units 117 and 119, respectively. Can be set or adjusted heavily. Alternatively, first, the second torch load adjusting section 119 adjusts L106 so as to cancel the own weight L30 of the torch body 30, and then the first torch load adjusting section 117 adjusts the total combined load TL to a desired value or a set value. It is also a preferable adjustment method to adjust L104 such that

  FIG. 4 shows a state in which the connecting rod 102 floats from the reference block 116 when the lock portion 108 is not pressed against the connecting rod 102 for ease of illustration. However, since the total combined load TL is normally set to TL> 0 as described above, when the tip of the torch electrode 34 is not placed on the object, that is, the work to be welded, the connecting rod 102 is placed on the upper surface of the reference block 116 (stopper). ), The torch body 30 remains stationary.

  A horizontal bar 118 extending horizontally or in the X direction on the opposite side (left side in the drawing) of the connecting rod 102 is also fixedly attached to the torch body 30. The torch guide 80 has openings 115 and 117 through which the connecting bar 102 and the horizontal bar 118 pass, respectively.

  A light-shielding plate 120 for detecting the amount of torch movement extending vertically upward is attached to the tip of the horizontal bar 118. Right above the light shielding plate 120, an optical movement amount detection sensor 122 fixed to the horizontal support plate 28 is arranged. The movement detection sensor 122 has the light emitting element ED and the light receiving element PD facing each other at the same height. As described later, at the time of touch start, the torch body 30 moves relatively upward with respect to the horizontal support plate 28, and the connecting rod 102 moves upward from the reference block 116. At this time, the top of the light shielding plate 120 blocks (shields) the light beam P connecting between the two elements ED and PD, thereby moving the torch body 30 relative to the horizontal support plate 28 by the amount of movement (that is, the torch). After the tip of the electrode 34 abuts on the workpiece W, it is possible to detect that the linearly movable portion 12 and the portions fixed to the movable portion 12 further move down have reached the set value.

  The left horizontal bar 118 is attached to the torch body 30 at the same height as the right connecting bar 102 with the same thickness as the right connecting bar 102, and below the horizontal bar 118 is the upper surface (the same height as the right reference block 116). A left reference block (not shown) having a reference surface (reference surface) may be provided, and a similar left fixing unit (not shown) interlocking with the fixing unit 108 may be provided directly above the left reference block. is there. Similarly, a plurality of compression coil springs 104 and extension coil springs 106 and a plurality of first and second torch load adjusting units 117 and 119 can be provided in parallel. Further, the compression coil spring 104 and / or the extension coil spring 106 can be configured by combining a plurality of coil springs alone.

[Configuration around clamp electrode and clamp connection part]
Next, with reference to FIGS. 1 and 3 and FIGS. 5A and 5B, a configuration around the clamp connecting portion 20 and the clamp electrode 24 in the TIG welding apparatus will be described in detail.

  In FIGS. 1 and 3, the clamp connecting portion 20 is composed of a rigid plate body 124 having a U-shaped vertical cross section, and a vertical guide portion 124 a extending in the Z direction. It has a flange portion 124b extending horizontally from the upper end so as to cover the upper surface of the linearly movable portion 12, and a base portion 124c extending horizontally from the lower end of the vertical guide portion 124a toward the torch 22 side.

  The clamp electrode 24 is fixedly arranged on the base portion 124c of the clamp connecting portion 20. On a surface of the vertical guide portion 124a facing the linearly movable portion 12, a linear guide 130 made of, for example, an LM guide (trademark) extending in the Z direction is provided. When the clamp electrode 24 or the clamp connecting portion 20 is fixed in the Z direction by the linear guide 130 (that is, when the clamp arms 76 (1) and 76 (2) hold the workpiece W), The linearly movable portion 12 can be arbitrarily moved up and down under the flange portion 124b. When the clamp electrode 24 or the clamp connecting portion 20 is not fixed in the Z direction (that is, when the clamp arms 76 (1) and 76 (2) do not hold the workpiece W), the clamp connecting portion 20 and the clamp connecting portion 20 are not fixed. The clamp electrode 24 also moves up and down integrally with the rectilinear movable portion 12 via the flange portion 124b.

  As shown in FIGS. 5A and 5B, the clamp electrode 24 includes a clamp body 74 that accommodates or is equipped with a drive source (not shown) such as a motor, a plunger, or a cylinder, and extends parallel to and protrudes from the clamp body 74. And a pair of openable and closable clamp arms 76 (1) and 76 (2). The drive source in the clamp body 74 is supplied with required power (electric power, compressed air or hydraulic oil) from the apparatus body 10 via a cable or a pipe 75 (FIG. 1), and is driven based on electromagnetic force or pneumatic or hydraulic pressure. Then, the clamp arms 76 (1) and 76 (2) are opened and closed in the X direction.

  The two clamp arms 76 (1) and 76 (2) always have a symmetrical positional relationship, that is, an equal interval (d1 = d2) with respect to a clamp center line C extending in the Y direction through the center of the clamp body 74. It keeps open and close movement. In order to perform such a symmetrical arm opening and closing movement, for example, a rack and pinion mechanism 132 can be used.

  The rectilinear movable portions 134 (1) and 134 (2) of the rack and pinion mechanism 132 are connected to the clamp arms 76 (1) and 76 (2) via an insulator 136. A locking (fixed) air cylinder 138 can be coupled to the member supporting the clamp electrode 24, for example, the rectilinear movable portion 12 or the clamp connecting portion 20 on both left and right sides. The entire X-direction movable portion can be locked (fixed) at any time in the X-direction.

  Further, in the welding head 10, the relative positional relationship between the clamp electrode 24 and the torch body 30 in the XY plane can be arbitrarily determined by the manual XY table 25 (FIG. 1) provided on the linearly movable section 12. Can be adjusted. Normally, the XY table 25 is adjusted such that the clamp center line C of the clamp electrode 24 intersects the center axis N of the torch electrode 34 mounted on the torch 22. However, when the thicknesses of the workpieces W1 and W2 are different, it may be better to positively shift the center axis N of the torch electrode 34 from the clamp center line C by a predetermined amount.

[Structure of torch]
In FIG. 3, a cylindrical collet 140 for holding a rod-shaped torch electrode 34 made of tungsten or a tungsten alloy at the axis of the torch body 30 is integrated with the torch body 34 inside the torch body 34. Is housed inside. The upper end of the collet 140 is held by a cylindrical electrode holder (not shown) extending to the cap 36 (FIG. 1) inside the collet body. When the cap 36 is screwed into the collet body 142 at the top of the torch 22, the electrode holder is pressed downward by the tightening of the screw, and the slit portion of the collet 140 is pressed downward by the electrode holder. As a result, the slit portion of the collet 140 is deformed in a direction to reduce the diameter, and the torch electrode 34 is narrowly attached (held).

  At the lower end of the torch 22, a cylindrical gas passage is formed between the collet 140 and the collet body 142 to guide the shield gas introduced into the intermediate portion of the torch body 30 from the utility introduction unit 86 downward. ing. A plurality of through holes are formed at a lower end of the collet body 142 at predetermined intervals in the circumferential direction. The shielding gas that has passed down the gas passage passes through the through-hole and exits into the space between the torch electrode 34 and the torch nozzle 32 or the nozzle chamber 144, and is ejected from the outlet at the lower end of the nozzle chamber 144, that is, the ejection port 146. It is supposed to. The torch nozzle 32 is preferably made of ceramic (for example, alumina).

[Operation of device (action)]
Next, the operation of the TIG welding device in this embodiment will be described with reference to FIGS. 6A to 6G.

  First, under the control of the main control unit in the main unit 50, the stage 40 (the XY stage 42 and the θ stage 44) on which the workpiece W to be welded is mounted performs a positioning operation in a horizontal plane. . With this positioning operation, the workpiece W (W1, W2) of the work body S is positioned substantially directly below the torch electrode 34. However, when a large number of workpieces W are mounted on the work body S and the above-described positioning operation is performed at high speed in order to shorten the tact time, the torch electrode 34 and the workpiece W (W1 , W2), the workpiece W (W1, W2) may be shifted laterally from a position immediately below the torch electrode 34, for example, as shown in FIG. 6A. On the other hand, in the height direction, the start position of the torch 22 is adjusted in advance by the elevation drive of the elevation drive unit 16 under the control of the main control unit in the main unit 50.

  When the positioning of the workpieces W (W1, W2) on the stage 40 is completed as described above, the elevation drive unit 16 operates under the control of the main control unit in the main unit 50, and the linearly moving unit 12, the torch 22 and the clamp electrode 24 are integrally moved down, and as shown in FIG. 6B, the clamp arms 76 (1) and 76 (2) are suitable for clamping the workpiece W (W1, W2). The clamp electrode 24 is lowered to the predetermined height position HC. In this case, since the fixing portion 108 of the torch connecting portion 18 presses the connecting rod 102 against the reference block 116 against the compression coil spring 104 and the extension coil spring 106, the torch body 30 It moves down integrally with the rectilinear movable portion 12 via the housing 100 and the horizontal support plate 28.

  After descending to the set height position HC, the clamp electrode 24 closes both clamp arms 76 (1) and 76 (2) in the X direction under the control of the main controller, that is, the work piece W (W1). , W2) (clamp operation). In the illustrated example, the workpiece W (W1, W2) of the work body S is relatively displaced toward the one (right) side of the clamp arm 76 (2). First, the right clamp arm 76 (2) comes into contact with the welding material W (W1, W2). After this, since the operation of driving the clamp arms 76 (1) and 76 (2) in the direction to close each other is continued, as shown in FIG. The guide 13 (FIG. 1) guides the rectilinear movable portion 12 of the welding head 10 and the torch 22 and the clamp electrode 24 integrally connected to the movable portion 12 to the right in the X direction.

  Thus, as shown in FIG. 6D, the other (left) clamp arm 76 (1) comes into contact with the workpiece W (W1, W2) with a delay, and the clamping operation is completed. The movement of the direction movable part (the straight movable part 12, the torch 22, the clamp electrode 24, etc.) also stops. Immediately thereafter, the lifting drive unit 16 starts an operation (touch operation) of lowering the linearly movable unit 12 and the torch 22. In this case, in the torch connecting portion 18, prior to the start of the touch operation, the locking portion 108 retracts the pressing bar 108 a upward to release the pressing and fixing (locking) to the connecting bar 102. Accordingly, the connecting rod 102 can be moved or displaced upward from the upper surface (reference surface) of the reference block 116.

  In this touch operation, since the clamped arms 76 (1) and 76 (2) sandwich the workpiece W, the clamp electrode 24 or the clamp connecting portion 20 is fixed or integrated with the work body S. By the elevation drive of the elevation drive unit 16, the linearly movable unit 12 and the torch 22 descend while being guided by the vertical linear guide 130 of the clamp connecting unit 20, and the tip of the torch electrode 34 contacts the workpiece W (W 1, W 2). Touch

  Even after the tip of the torch electrode 34 abuts on the workpiece W (W1, W2), the elevation drive unit 16 continues the downward movement of the linearly movable unit 12. Then, when the light beam P of the optical sensor unit 122 descending integrally with the rectilinear movable portion 12 or the horizontal support plate 28 descends to the light shielding plate 120 on the torch body 30 side, the main control portion stops the descending drive of the lifting drive portion 16. . FIG. 6E shows the state at this time.

  In the touch operation as described above, after the lock unit 108 releases the pressing and fixing (locking) of the connecting rod 102, the torch body 30 is provided with its (own weight) L30 and a vertically upward direction by the extension coil spring 106. And the vertical downward spring load (elastic force) L104 by the compression coil spring 104 act simultaneously, that is, in opposition to each other. As described above, since the tension coil spring 106 and the compression coil spring 104 act on the torch body 30 in opposition to each other, the torch body 30 does not sway up and down even if the connecting rod 102 floats from the reference block 116. In addition, the touch operation is performed smoothly, at high speed, and stably.

  Moreover, the torch load applied to the workpiece W (W1, W2) after the completion of the touch operation is the total combined load TL that can be adjusted to an arbitrary load (especially as small as possible) as described above. Thereby, it is not necessary to damage the workpiece W (W1, W2).

  In this manner, the switch SW (FIG. 3) of the welding power source is switched from the OFF state to the ON state in the main unit 50 under the state where the tip of the torch electrode 34 is in pressure contact with the workpiece W. Then, DC voltage E is applied between torch electrode 34 and workpiece W from the welding power source. Thereby, the positive terminal of the DC voltage source of the welding power source → the earth cable 77 → the clamp arms 76 (1) and 76 (2) → the workpiece W → the torch electrode 34 → the torch body 30 → the power introduction section 86 → the bridge type conductor 94 → the utility relay section 26 → the utility cable 70 (welding current supply line) → a current path (closed circuit) of the negative terminal of the DC voltage source E, a DC current at the start of energization, that is, a start current.

  At this time, since the tip of the torch electrode 34 is in contact with the workpiece W, no arc is generated regardless of the magnitude of the current. Of course, the current value of the start current may be controlled within a certain range by controlling the output of the welding power supply circuit.

  The supply of the shielding gas is started during the lowering of the torch 22 or after the tip of the torch electrode 34 contacts the workpiece W. As described above, the shielding gas sent from the main unit 50 (FIG. 2) to the welding head 10 via the utility supply cable 70 (gas supply line) is supplied to the utility relay unit 26 → the cross-linking tube 92 → the utility introduction unit. 86 → the torch body 30 → the gas is injected toward the workpiece W from the injection port 142 of the torch nozzle 32 through each gas flow path of the torch nozzle 32.

  In this way, while the start current is flowing, the straight drive unit 16 starts ascending drive under the control of the main control unit, and the torch body 30 via the straight movable unit 12 is equal to the optimal set distance for arc discharge. Move upward by the stroke amount. Also at this time, the compression coil spring 104 and the tension coil spring 106 act on the torch body 30 in opposition to each other, so that the elastic vibrations of both coil springs 104 and 106 are canceled each other, and the torch body 30 does not swing up and down. Then, the tip of the torch electrode 34 is smoothly pulled up to the set height position (FIG. 6F).

  When the tip of the torch electrode 34 is pulled upward from the workpiece W as described above, an arc is generated between the two (space). The main control unit raises the output voltage of the welding power supply circuit by one step at the same time as or after the separation of the torch electrode 34, and reduces the current flowing in the closed circuit to an arc discharge that is much larger than the start current up to that time. Switch to the regular DC current or main current. The current value of the main current is selected to be a value (usually 30 A or more) that generates an arc of high heat enough to melt the workpiece W.

  While the main current is flowing in this manner, the arc AC continues between the torch electrode 34 (particularly near the tip) and the workpiece W, and the workpiece W is melted by the heat of the arc AC. Note that the current value of the main current may be kept constant all the time, but in order to promote the melting of the workpiece W, a current value such that the current value of the main current is further increased stepwise or gradually on the way. Waveform control (or conversely, downslope current waveform control) can also be used.

  When a predetermined time (usually 2 to 3 seconds) has elapsed from the start of energization, the main control unit switches the switch SW to the off state to stop energization. Immediately after that, the supply of the shielding gas is stopped. When the energization stops and the main current is cut off, the arc disappears at that moment. When the arc disappears, the molten portion of the material to be welded W solidifies immediately due to natural cooling in the atmosphere. As shown in FIG. 6G, the clamp electrode 24 opens the clamp arms 76 (1) and 76 (2) to release the clamp on the workpiece W. Thus, the two metal members W1 and W2 of the workpiece W are welded and joined together.

  As described above, in the TIG welding apparatus according to this embodiment, the torch body 30 is attached to the rectilinear movable portion 12 of the welding head 10 via the torch connecting portion 18, and the compression coil spring 104 and the extension coil spring 106 are attached to the torch connecting portion 18. And a lock portion 108. By making the spring loads of the two coil springs 104 and 106 relatively to the torch body 30, the touch operation for touch start and the torch electrode lifting immediately after touch start ( Arc generation) operation can be performed quickly and stably, and the total combined load TL of the torch body 30 applied to the workpiece W can be adjusted to an arbitrarily small load. Breakage and the like can be reliably prevented.

  Further, in the TIG welding apparatus of this embodiment, the heavy utility supply cable 70 from the main unit 50 is terminated at the utility relay section 26 on the linearly movable section 12 of the welding head 10, and the subsequent stage (downstream side) of the utility relay section 24. In this configuration, the bridge-type tube 92 and the bridge-type conductor 94 that can be displaced or deformed in an air-shaped stable posture are connected to the torch body 30, so that the torch load itself is effectively reduced and stability is effectively realized. can do. As described above, the torch load applied to the material to be welded W in the touch start method is very small, and the variation in the torch load is small, so that the quality of arc welding is improved.

  In the TIG welding apparatus of this embodiment, when the clamp electrode 24 is used, each part of the welding head 10 (the linearly movable part 12, the torch body 22, the clamp electrode 24) while the workpiece W is fixed on the stage 40. , Etc.) in the opening and closing direction (X direction) of the clamp arm by the guidance of the horizontal guide portion 13 (FIG. 1), thereby performing the clamping operation. Since such a clamping operation is not affected at all by the weight or bulkiness of the material W to be welded, high quality and accurate operation can be performed without any problem with any material or application using the clamp in the TIG welding of the touch start method. TIG welding can be guaranteed.

[Other Embodiments or Modifications]
The device configuration in which the clamp electrode 24 is mounted on the welding head 10 as in the above embodiment is suitable for use in so-called butt welding (butt welding) as described above. As another work form, for example, there is a workpiece WJ as shown in FIG. In the material to be welded WJ, a thin conductive wire 152 is wound around a strip-shaped terminal member 150 protruding from a work body SJ such as a small precision electronic component package, and the wound portion is used as a portion to be welded. Dimensionally, for example, the width s of the terminal member 150 is about 1 mm, the thickness t is about 0.2 mm, and the thickness of the conductive wire 152 is about 0.05 mm. In order to perform TIG welding, a contact 154 is detachably mounted near the base of the terminal member 150. The contact 154 is connected to a welding power source in the main unit 50 via an earth cable 78.

  When such a light, thin and small material to be welded WJ is subjected to a strong load (for example, 100 g weight or more) from above on the portion to be welded, it easily bends or breaks near the root of the terminal member 150, or becomes large. Easy to bend. According to the TIG welding apparatus of this embodiment, the spring load of the compression coil spring 104 and / or the tension coil spring 106 of the torch connecting member 18 is simply adjusted by the first and second torch load adjusting units 117 and 119, In the touch start method, it is possible to reduce the torch load applied to the workpiece W to a very small load, whereby the bending or breakage of the workpiece WJ can be reliably prevented. Even if WJ is flexible, the amount of deflection when receiving a torch load can be made as small as possible.

  In the TIG welding for the workpiece WJ as described above, the clamp electrode 24 becomes unnecessary. Therefore, as one configuration example, a configuration in which the clamp electrode 24 is detachably mounted on the base 124c of the clamp connection portion 124 can be adopted. Alternatively, a configuration is also possible in which the clamp connection part 124 is detachably attached to the welding head 10 (the linearly movable part 12) while the clamp electrode 24 is fixed to the clamp connection part 124.

  In the embodiment described above, the supply of the welding current and the supply of the shielding gas from the main unit 50 side to the welding head 10 are performed using one utility supply cable 70. However, it is also possible to use a separate current supply line and a separate gas supply line. Further, a configuration in which the utility relay section 26 and / or the utility introduction section 86 are divided into a welding current supply system relay section and a gas supply system relay section is also possible.

  Although not shown, a configuration in which a compression coil spring 104 and a tension coil spring 106 are provided in parallel between the connecting rod 102 and the bottom surface of the housing 100 in the torch connecting portion 18 as in the above embodiment is also possible. In this case, the operations of the compression coil spring 104 and the extension coil spring 106 are opposite to those of the above-described embodiment. That is, the compression coil spring 104 applies a spring load acting vertically upward to the torch body 30, and the extension coil spring 106 applies a spring load acting vertically downward.

  A modification in which the compression coil spring 104 and / or the tension coil spring 106 is replaced with another form of a spring member such as a leaf spring is also possible.

DESCRIPTION OF SYMBOLS 10 Welding head 12 Linearly movable part 14 Elevation drive arm 16 Elevation drive part 18 Torch connection part 20 Clamp connection part 22 Torch 24 Clamp electrode 26 Force relay part 28 Horizontal support plate 30 Torch body 34 Torch electrode 40 Stage 86 Force introduction part 92 Bridge Mold tube 94 Bridge type conductor 102 Connecting rod 104 Compression coil spring 106 Tension coil spring 108 Lock part

Claims (7)

A cylindrical torch body that detachably mounts and holds the torch electrode,
In the touch start method, a current is supplied between the tip of the torch electrode and the material to be welded, or a welding power source that causes a current to flow in a closed circuit including the material to be welded to generate an arc. ,
A linearly movable portion provided to be able to linearly move in a first direction parallel to the axis of the torch body around the torch body;
A linear drive unit for linearly moving the linear moving unit in the first direction;
A first spring member that is provided between the linearly movable portion and the torch body, and applies a spring load to the torch body in the first direction toward the material to be welded;
A second spring member that is provided between the rectilinear movable portion and the torch body, and applies a spring load to the torch body in the first direction in a direction opposite to a material to be welded;
A lock portion for arbitrarily fixing the torch body to the linearly movable portion against the first and second spring members ;
A torch load adjusting unit for variably adjusting a total combined load obtained by subtracting a spring load of the second spring member from a sum of a weight of the torch body and a spring load of the first spring member;
A TIG welding device having: The torch load adjusting unit is configured to adjust a spring load of one or both of the first and second spring members so that the total combined load applied to the workpiece through the torch electrode at the time of touch start has a desired value. The TIG welding device according to claim 1 , wherein the TIG welding device is adjusted. One of the first and second spring members has a compression coil spring,
The other of the first and second spring members has a tension coil spring.
The TIG welding device according to claim 1 . A pair of clamp arms that can be opened and closed in a second direction orthogonal to the first direction to physically hold the workpiece and electrically connect to the welding power source; and the pair of clamps. A clamp drive unit for opening and closing the arm, and a clamp electrode connected to the linearly movable unit so as to be movable in the first direction relative to the torch body;
The TIG welding device according to claim 1, further comprising: a guide portion provided between the straight-moving drive portion and the straight-moving portion to guide the straight-moving portion movably in the second direction. The TIG welding apparatus according to claim 4 , further comprising: an XY stage for adjusting a relative positional relationship between the clamp electrode and the torch body in a plane orthogonal to the first direction. An external terminal attached to a side surface or an upper end of the torch body and electrically connected to the torch electrode via a conductive path in the torch body;
A first current relay terminal provided on the linearly movable portion and terminating a welding current supply line from the welding power supply, and a first current relay terminal electrically connected to the first current relay terminal via a fixed conductor; A current relay section having two current relay terminals;
The TIG welding apparatus according to claim 1, further comprising: a displaceable or deformable bridge-type conductor bridged between the second current relay terminal of the current relay unit and the external terminal of the torch body. A torch nozzle attached to a lower end of the torch body to eject a shielding gas toward the workpiece;
A gas introduction port attached to a side surface or an upper end of the torch body, and communicating with the torch nozzle via a gas flow path in the torch body;
A first gas relay port that is provided on the linearly movable portion and terminates a gas supply line from a shield gas supply unit that supplies the shield gas; and a gas chamber or a gas passage fixed to the first gas relay port. A gas relay section having a second gas relay port communicating with the gas relay section;
2. The TIG welding apparatus according to claim 1, further comprising: a displaceable or deformable cross-linkable tube that is bridged between the second gas relay port of the gas relay unit and the gas introduction port of the torch body. 3.

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