JP6302343B2 - TIG welding apparatus and TIG welding method - Google Patents

Description

  The present invention relates to a TIG welding apparatus and a TIG welding method for welding while holding two members butted against each other with a clamp.

  An electric circuit consists of a power source that supplies electricity and electric parts that perform a certain function using electricity. Wiring connection or connection work is always required to build an electric circuit. I need it. In general, arc welding using an electric discharge phenomenon (arc discharge) is often used for welding discrete terminal members. In particular, a TIG welding method using a non-consumable torch electrode (tungsten electrode rod) is often used for welding terminal members constituting an electric circuit.

  2. Description of the Related Art Conventionally, a TIG welding apparatus mounted on an automatic working machine such as a robot has the same or the same fixing jig such as a clamp (also referred to as a “chuck”) that serves as one electrode and the other electrode. Attach the tip of the torch electrode to the welded part while holding the welded part of the two terminal members (base material) with the clamp attached to the tip of the common robot arm, and between the electrodes (torch electrode and clamp) A voltage is applied to the electrode to generate an arc between the torch electrode and the welded portion, and the welded portion is melted by the heat of the arc.

  In this case, since the torch electrode and the clamp are always in a fixed positional relationship on the robot arm, the clamp clamping position and the torch electrode approaching position (arc discharge position) are constantly managed with respect to a large number of workpieces or welded parts. (For example, see Patent Document 1).

JP 2010-82674 A

  However, in the conventional TIG welding apparatus in which the torch electrode and the clamp are always in a fixed positional relationship as described above, it is difficult to stably and reliably generate an arc between the torch electrode and the welded part. An arc may occur between the torch electrode and the clamp, causing the clamp to melt or burn.

  Such an undesired sparking of the arc can be avoided by arranging the clamp at a position sufficiently far from the torch electrode. However, if the position to clamp the welded part of the clamp is moved away from the torch electrode, the adhesion is not guaranteed near the tip of the welded part, that is, the function of the clamp is weakened, resulting in the desired arc welding quality. It becomes impossible.

  The present invention has been made in view of the above-described problems of the prior art, and can perform high-quality and stable arc welding performed by holding two members (base materials) butted against each other with a clamp. A TIG welding apparatus and a TIG welding method are provided.

  The TIG welding apparatus of the present invention includes a stage parallel to the XY plane, a passive compliance device provided on the stage and slidable in any direction within the XY plane, and the compliance device. A clamp electrode capable of holding the first and second members placed as base materials in close contact with each other at a welded portion, a torch body for detachably mounting and holding the torch electrode, the torch electrode, A welding power source for flowing current in a closed circuit including the welded portion, applying pressure to the welded portion by the clamp electrode, and bringing the tip of the torch electrode into contact with the welded portion. In this state, the welding power source applies a voltage between the torch electrode and the welded part to start energization in the closed circuit, and pressurization to the welded part and energization in the closed circuit While continuing away the tip of the torch electrode from the welded portion, thereby generating an arc between the torch electrode and the welded part, welding the welded portion by the heat of the arc.

  The TIG welding method of the present invention includes a step of placing the first and second terminal members as a base material on a passive compliance device that can slide in an arbitrary direction within the XY plane, A step of bringing the first and second terminal members placed on the device into close contact with each other at the welded portion, a step of bringing a tip of a torch electrode into contact with the welded portion, and the welded portion Applying a voltage between the torch electrode and the welded part in a state where a pressing force for tightly fixing the part is applied and the tip of the torch electrode is in contact with the welded part, the torch A step of starting energization in a closed circuit including an electrode and the welded portion, and applying a pressure to the welded portion and energizing the closed circuit while continuing the tip of the torch electrode from the welded portion. Release the torch A step of generating an arc between the pole and the welded portion, and melting the welded portion by the heat of the arc; a step of stopping energization in the closed circuit and releasing the pressure on the welded portion; Have

  In the present invention, the energization is started in a state where the tip of the torch electrode is in contact with the welded portion while applying the pressure for tightly fixing the welded portions of both terminal members (base materials), and then the torch electrode is pulled apart. To generate arc discharge. As a result, it is possible to reliably concentrate the arc on the welded portion, and the desired welding quality can be stably and reliably obtained by bringing the clamp electrode as close as possible to the torch electrode. Further, the compliance device slides following the direction in which the clamping force acts during the operation (clamping operation) in which the first and second members are held in close contact with each other at the welded portion. As a result, the tip of the torch electrode is accurately opposed to the center of the welded portion or the contact position of both terminal members. For this reason, even if an alignment error occurs, the tip of the torch electrode contacts the center of the welded portion or the vicinity thereof or the contact position of the two terminal members or the vicinity thereof in the touch start method, so that the welding is reliably performed. The arc can be concentrated near the center of the part or near the contact position of both terminal members. As a result, the center portion of the welded portion can be reliably melted with arc heat to obtain good welding strength.

  The compliance device used in a preferred embodiment of the present invention has a base portion fixed to the stage and a movable portion slidably mounted on the base portion via a ball guide.

  As a preferred embodiment of the present invention, the clamp electrode is a clamp for fixing the first and second members by electromagnetic force, pneumatic pressure or hydraulic pressure in the vicinity of the portion of the welded portion facing the torch electrode. Have

  According to another preferred embodiment, in the step of holding the first and second terminal members in close contact with each other at the welded portion, the first and second terminal members are clamped by the clamp electrode, and the torch The central axis of the electrode and the contact position of the first and second terminal members are opposed to each other, or the central axis of the torch electrode and the central part of the overlapping direction of the first and second terminal members are opposed to each other.

  According to the TIG welding apparatus or the TIG welding method of the present invention, arc welding performed by holding the two members (base materials) with clamps can be performed with high quality and stability by the above-described configuration.

It is a figure showing the whole TIG welding device composition in one embodiment of the present invention. It is a perspective view which shows the form of the base material and to-be-welded part in embodiment, and the structure of the principal part of the said TIG welding apparatus. It is a figure which shows the specific structural example of the movement stage with which the said TIG welding apparatus is equipped. It is a perspective view which shows the external appearance structure and function of a passive type compliance device used with the said TIG welding apparatus. It is a flowchart which shows the procedure (process to the middle) of TIG welding in embodiment. It is a flowchart which shows the procedure (remaining process) of TIG welding. It is a figure which shows one step of the raising / lowering operation | movement of the torch and clamp electrode in the said TIG welding apparatus. It is a figure which shows one step of the raising / lowering operation | movement of the said torch and a clamp electrode. It is a figure which shows one step of the raising / lowering operation | movement of the said torch and a clamp electrode. It is a figure which shows one step of the raising / lowering operation | movement of the said torch and a clamp electrode. It is a figure which shows one step of the raising / lowering operation | movement of the said torch and a clamp electrode. It is a figure which shows one step of the raising / lowering operation | movement of the said torch and a clamp electrode. It is a figure which shows one step of the clamp operation | movement and electricity supply operation | movement in the said TIG welding apparatus. It is a figure which shows one step of the said clamp operation | movement and electricity supply operation | movement. It is a figure which shows one step of the said clamp operation | movement and electricity supply operation | movement. It is a figure which shows one step of the said clamp operation | movement and electricity supply operation | movement. It is a figure which shows one step of the said clamp operation | movement and electricity supply operation | movement. It is a figure which shows the method of producing | generating arc discharge in the conventional TIG welding apparatus in which the clamp operation position (clamping position) is moved away from the torch electrode. It is a figure which shows one of the subjects when the passive type compliance device is not integrated in the movement stage in the TIG welding apparatus of embodiment. It is a figure which shows one modification around the rectilinear drive member in embodiment. It is a figure which shows another modification around the rectilinear drive member in embodiment. It is a figure which shows the 1st form of the position alignment operation | movement and clamp operation | movement in one modification. It is a figure which shows the 2nd form of the position alignment operation | movement and clamp operation | movement in a modification.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
In FIG. 1, the whole structure of the TIG welding apparatus in one Embodiment of this invention is shown. This TIG welding apparatus has a stationary apparatus configuration that can be suitably adapted to prayer welding (butt welding), and is a unit-type apparatus body incorporating a DC welding power supply circuit, a control circuit, various drive circuits, and the like. 10, a welding head 12 for performing TIG welding on a workpiece (base material) on an electric component support (for example, an assembly or a circuit board) S under supply and control of utility from the apparatus main body 10, and a shielding gas For example, it has a gas cylinder 14 which is a supply source of argon gas.

  In the welding head 12, a stage 18 and a torch stand 20 are provided on a plate-like base 16, and a torch 22 for TIG welding and a clamp electrode 24 are mounted on the torch stand 20 so as to be movable up and down.

  More specifically, the stage 18 has an XY stage 25 that is movable on the base 16 in a horizontal XY plane. On the XY stage 25, the welding head 12 is provided with a horizontal table 28 on which a workpiece is placed via a passive compliance device 26 that can slide in any direction within the XY plane. The configuration and operation of the stage 18 and the compliance device 26 will be described in detail later.

  On the other hand, the torch stand 20 is provided with an elevating tower 30 having a built-in elevating drive unit (not shown) having, for example, a servo motor as a drive source on a fixed base 29. A straight drive member 34 is coupled to the lift drive portion of the lift tower 30 via a lift support shaft 32, and the torch 22 and the clamp electrode 24 are attached to the straight drive member 34 so as to be integrally movable and separable in the vertical direction. Yes. A mechanism for connecting the rectilinear drive member 34 to the torch 22 and the clamp electrode 24 will be described in detail later.

  The torch 22 is fixed in the horizontal direction. The XY stage 26 moves in the XY direction under a control signal sent from the apparatus main body 10 via the cable 36, so that the TIG welding is performed on the electric component support S placed on the table 28. The welded portion WJ of the workpiece to be welded can be positioned directly below the torch 22.

  The torch 22 is supplied with power for TIG welding and shield gas SG from the apparatus main body 10 via a hose 38 with a built-in torch cable. The torch body 40 is formed of an insulator, for example, a cylindrical torch body 40 made of resin. It has a cylindrical or conical torch nozzle 42 attached to the tip (lower end) portion of the torch body 40, and a pencil-shaped torch electrode (tungsten electrode rod) 44 is detachably mounted in the torch body 40 and the torch nozzle 42. The tip of the torch electrode 44 protrudes slightly (usually 2 to 3 mm) from the lower end of the torch nozzle 42.

  The apparatus main body 10 is provided with a display 46, operation buttons 48, a power switch 50 and the like on the front side of the unit, and with external connection terminals or connectors 52 on the side or back side of the unit. The shield gas SG sent from the gas cylinder 14 to the hose 15 is supplied to the torch 22 via the apparatus main body 10 and the hose 38. The hose 15 may be directly connected to the torch 22.

In FIG. 2, the structure of the principal part of the welding head 12 in this embodiment and an example of a to-be-welded material (base material) are shown. In the example shown in the drawing, for example, two elongated rod-shaped or plate-shaped metal members made of copper, for example, bus bars W ₁ and W ₂ are used as base materials, and upper end surfaces of both metal members W ₁ and W ₂ ( The top surfaces of the top surfaces are substantially flush with each other, and the upper ends of the top surfaces are integrated together. The upper ends of the metal members W ₁ and W ₂ combined together form a welded portion WJ. The other end (not shown) of each metal member W ₁ , W ₂ communicates with an electrical component (not shown) mounted on the electrical component support S, for example. Alternatively, one metal member W ₁ is mounted on an electrical component support S, and the other end of the other metal member W ₂ is mounted on another electrical component support (not shown). (Not shown).

In a normal welded portion WJ, there is always some gap (for example, about 0.1 mm) at the contact interface between the metal members W ₁ and W ₂ . In addition, it is preferable that the upper end surfaces or top surfaces of the metal members W ₁ and W ₂ are exactly flush with each other, but in general, an error or a level difference of 0.1 mm or less is sufficient for practical use. .

In FIG. 1 and FIG. 2, one welded portion WJ (W ₁ , W ₂ ) on the electrical component support S is exaggerated and enlarged for easy illustration. In general, an electrical component support that uses bus bars for electrical wiring has welded portions WJ (W ₁ , W ₂ ) at a plurality of locations, for example, 10 locations.

As shown in FIGS. 1 and 2, the clamp electrode 24 is attached to a lower end portion of a lifting / lowering rod 56 that can be moved and separated integrally with the rectilinear drive member 34 in the vertical direction, and drives a motor, plunger, cylinder, or the like. It has a clamp body 58 that houses or equips a source (not shown) and a pair of openable and closable clamp arms 60 that project from and extend in parallel with the clamp body 58. The drive source in the clamp body 58 is supplied with a required working force (electric power, compressed air or hydraulic oil) from the apparatus body 10 via a cable or a pipe 62, and has a required clamping force based on electromagnetic force or air pressure or hydraulic pressure. Generates force or pressure. The clamp arm 60 is coupled to the driving source so that the welded portion WJ can be clamped and fixed in the thickness direction of the terminal members W ₁ and W ₂ . The position of the clamp electrode 24 on the elevating rod 56 or a connecting portion to be described later so that the clamp arm 60 can clamp and fix the welded portion WJ at the optimum height position, that is, the operating position of the clamp electrode 24 can be adjusted. A mechanism (not shown) for adjusting the position of (68) can be provided.

  The clamp arm 60 is made of a conductor such as brass, and is electrically connected to a welding power source in the apparatus main body 10 via an earth cable 64. In this embodiment, the clamp arm 60 is electrically connected to the positive electrode of the welding power source. A torch electrode 44 is electrically connected to the negative electrode of the welding power source via a torch cable built in the hose 38.

  FIG. 3 shows a specific configuration of the stage 18. The XY stage 25 of the stage 18 is mounted on the X stage 25X that is movable in one horizontal direction, that is, the X direction on the base 16, and one horizontal direction that is orthogonal to the X direction, that is, the Y direction. And a movable Y stage 25Y. The X stage 25X and the Y stage 25Y include a linear drive mechanism using a motor 90X, 90Y as a drive source, for example, a ball screw mechanism. In the figure, 92X and 92Y are cable carriers.

  The compliance device 26 has a disc-shaped base portion 26a fixed to the upper surface of the Y stage 25Y of the stage 18, and a shape (disc shape) substantially the same as the base portion 26a, and a ball guide on the base portion 26a. And a movable portion 26b that is slidably attached via (not shown).

  As shown in FIG. 4, this compliance device 26 introduces compressed air of a constant pressure from a compressed air generation source (not shown) through a pipe 94, and is in an arbitrary horizontal direction (XY direction) to the movable portion 26b. When the external force F in the torsional direction) is applied, the movable portion 26b slides in the direction in which the external force F acts, and when the external force F is released, the movable portion 26b is moved to the origin position by the pressure of the compressed air. It returns to (a position coaxial with the base portion 26a). In this embodiment, since the table 28 is fixed on the movable portion 26b, when an external force F in any horizontal direction (XY direction or twist direction) is applied to the table 28, the external force F acts. The movable part 26b slides integrally with the table 28 in the direction. A passive type compliance device having such a configuration and function is available on the market, and for example, an ultra-low sliding quick adjuster (trade name) manufactured by Kondo Seisakusho can be suitably used.

  Next, a mechanism for connecting the linear drive member 34, the torch 22 and the clamp electrode 24 in the TIG welding apparatus of this embodiment will be described with reference to FIGS. 6A to 6F. As shown in the figure, the torch body 40 and the lifting bar 56 are respectively passed through the through holes 34a and 34b of the plate-like linearly-driven drive member 34, and are fixed to the upper part or the middle part of the torch body 40 and the lifting bar 56. The torch body 40 and the lifting / lowering rod 56 are connected to the rectilinear drive member 34 such that the flange-shaped connecting members 66 and 68 are placed on the upper surface of the rectilinear drive member 34. As described above, the clamp electrode 24 is attached to the lower end portion of the lifting rod 56.

In the torch and clamp raising / lowering mechanism having such a configuration, while the lower end (tip) of the torch electrode 44 and the lower end of the raising / lowering rod 56 are floating in the air (FIGS. 6A and 6B), the raising / lowering tower 30 (FIG. 1) When the rectilinear drive member 34 is lowered, the torch 22 and the clamp electrode 24 move downward together with the rectilinear drive member 34 in a state where the connecting members 66 and 68 are placed on the upper surface of the rectilinear drive member 34. When the clamp electrode 24 arrives at the operating position, the clamping operation is started immediately, and the welded portion WJ of the base material (W ₁ , W ₂ ) is clamped. When the rectilinear drive member 34 is further lowered, the connecting member 68 of the elevating rod 56 is separated from the rectilinear drive member 34 (FIG. 6C). Then, after the lower end of the torch electrode 44 comes into contact with the upper surface of the welded portion WJ of the base material (W ₁ , W ₂ ), the connecting portion 66 of the torch body 40 is separated from the rectilinear drive member 34, and the torch body 40 comes to stand on the welded portion WJ independently of the rectilinear drive member 34 (FIG. 6D). At this time, the weight of the torch 22 is applied to the welded portion WJ.

In the illustrated configuration example, when the connecting member 68 of the elevating bar 56 is separated from the rectilinear drive member 34, the weights of the elevating bar 56 and the clamp electrode 24 are applied to the base material (W ₁ , W ₂ ). . However, as will be described later, the load applied to the base material (W ₁ , W ₂ ) is reduced as much as possible by interposing the compression coil spring (86) between the connecting member 68 and the rectilinear drive member 34. be able to.

Further, when the linear drive member 34 is moved up to the original height position from the state where the lower end of the torch electrode 44 is in contact with the welded portion WJ of the base material (W ₁ , W ₂ ) (FIG. 6E), On the way, first, the connecting member 66 of the torch body 40 rests on the rectilinear drive member 34 and the torch body 40 also moves upward together with the rectilinear drive member 34, and then the connecting member 68 of the elevating bar 56 moves to the rectilinear drive member 34. The lifting rod 56 and the clamp electrode 24 are also moved upward together with the rectilinear drive member 34 (FIG. 6F).

  In this embodiment, the sensor 70 for detecting the connection or separation state between the connection member 66 of the torch body 40 and the rectilinear drive member 34 is provided. The illustrated sensor 70 is composed of a vertical linear scale, and a scale portion 72 extending in the vertical direction attached to the side surface of the connecting member 66, and the scale portion 72 according to the relative height position of the rectilinear drive member 34. And a scale reading unit 74 attached to the linear drive member 34 so as to be optically read at a level. The scale reading unit 74 is composed of a reflective optical sensor, and is electrically connected to a control circuit in the apparatus main body 10 via an electric cable (not shown).

In this sensor 70, as long as the connecting member 66 of the torch body 40 is placed on the rectilinear drive member 34, the output signal of the scale reading unit 74 (even if the rectilinear drive member 34 moves up and down at an arbitrary height position ( (Reading value) is kept constant. However, when the rectilinear drive member 34 is separated from the connecting member 66 of the torch body 40, the relative position between the scale portion 72 and the scale reading portion 74 changes, and the output signal (read value) of the scale reading portion 74 changes. The control unit in the apparatus main body 10 can monitor the relative positional relationship between the rectilinear drive member 34 and the torch body 40 based on the output signal from the scale reading unit 74, and the rectilinear drive member 34 moves forward (downward movement). When the lower end of the torch electrode 44 comes into contact with the welded portion WJ of the base material (W ₁ , W ₂ ) during the process, this can be detected. It should be noted that other types of sensors such as proximity sensors may be used instead of the optical sensors using such scales.

  Next, the operation and action (TIG welding method) of the TIG welding apparatus in this embodiment will be described with reference to FIGS. 5A to 5B, FIGS. 6A to 6F, and FIGS. 7A to 7E. In addition, the flowchart of FIG. 5A and FIG. 5B shows the procedure of the TIG welding method in this embodiment. 7A to 7E show each stage of the clamping operation and the energization operation in the TIG welding apparatus.

First, the electric component support S on which the base materials (W ₁ , W ₂ ) are mounted is placed on the table 28 of the welding head 12 by a work transfer device such as a robot hand (not shown) or manually. (step S _1). Thereafter, alignment in the horizontal plane by the stage 18 is performed under the control of the control unit in the apparatus main body 10 (step S ₂ ). By this positioning operation, the welded portion WJ of the base material (W ₁ , W ₂ ) comes to be positioned directly below the torch electrode 44. However, when a large number of welded parts WJ are mounted on the electric component support S and the above-described alignment operation is performed at a high speed in order to shorten the tact time, the torch electrode 44 and the welded part WJ The center axis Z ₄₄ of the torch electrode 44 is somewhat displaced from the center of the welded portion WJ (particularly, the gap g between the metal members W ₁ and W ₂ ). There is.

  Apart from the alignment in the horizontal plane as described above, the start position of the torch 22 is adjusted to an appropriate height position by the elevating tower 30 under the control of the control unit in the apparatus main body 10 also in the height direction. However, when arc welding under the same conditions is continuously performed on a plurality of workpieces of the same type, the torch 22 is returned to the same start position as the previous time after the end of arc welding, so that the next arc welding can be performed. Initial height position adjustment can also be omitted.

The base material (W ₁ , W ₂ ) on the table 28 under the control of the control unit in the apparatus main body 10 from the state where the above alignment or the initial height position has been adjusted (FIG. 6A). TIG welding is performed on the welding head 12.

First, the control unit operates the elevating drive unit of the elevating tower 30 to start the downward movement of the rectilinear drive member 34 (step S ₃ ). Since the lower end (tip) of the torch electrode 44 and the lower end of the lifting / lowering rod 56 are floating in the air (FIG. 6A), when the downward movement of the linear drive member 34 is started, the connecting members 66 and 68 are moved to the linear drive member 34. The torch 22 and the clamp electrode 24 also move downward together with the rectilinear drive member 34 while being placed on the upper surface.

Shortly after the linear drive member 34 starts to move downward, the clamp electrode 24 arrives at a preset position in the vertical direction, that is, an operating position (step S ₄ ). At this operating position, the clamp electrode 24 starts a clamping operation (step S ₅ ), and drives the clamp arm 60 in the closing direction to sandwich the upper end portion of the welded portion WJ of the base material (W ₁ , W ₂ ). Wear (FIG. 7A).

In this case, if the central axis Z ₄₄ of the torch electrode 44 is shifted from the center of the welded portion WJ (especially the gap g between the two metal members W _1, W _2), the welded portion WJ clamping electrodes 24 The applied clamping force (clamping force) acts as an external force F in the XY direction or torsional direction on the movable portion 26b of the compliance device 26 via the base material (W ₁ , W ₂ ), the electrical component support S, and the table 28. To do. Then, as a result of the movable part 26b of the compliance device 26 sliding on the base part 26a following the direction in which the external force F acts, the tip of the torch electrode 44 (center axis Z ₄₄ ) through the clamping operation of the clamp electrode 24. Comes to face the center of the welded part WJ. As described above, even if an error (positional deviation) occurs in the alignment between the torch electrode 44 and the welded portion WJ by the stage 18, the positional deviation is corrected in the subsequent clamping operation of the clamp electrode 24. Is done.

On the other hand, the torch 22 is moved downward together with the linear drive member 34 even after the lifting and lowering rod 56 has been lowered (step S ₆ ), and the lower end (tip) of the torch electrode 44 is the base material (W ₁ , W ₂ ). Asymptotically approach the welded part WJ. When the lower end of the torch electrode 44 comes into contact with the upper surface of the welded portion WJ (step S ₇ ), the downward movement of the torch 22 ends (FIG. 6C), and immediately after that, the rectilinear drive member 34 connects the torch body 40. The controller 66 is separated from the member 66 (FIG. 6D), and the controller stops the downward movement of the rectilinear drive member 34 in response to the output signal of the sensor 70 (step S ₈ ).

  Note that the control unit starts supplying the shield gas SG in the middle of the downward movement of the torch 22 or immediately after the end of the downward movement. The shield gas SG is supplied from the cylinder 14 to the torch 22 via the apparatus main body 10 and the hose 38. The torch 22 introduces the shield gas SG into the upper portion of the torch body 40 and ejects the introduced shield gas SG from the opening of the torch nozzle 42.

Thus, the control unit starts energization under the state where the tip of the torch electrode 44 is in contact with the welded portion WJ of the base material (W ₁ , W ₂ ) (step S ₉ ). In other words, the switch SW of the welding power supply circuit E _DC is switched from the previous OFF state to the ON state in the apparatus main body 10. Then, a direct current voltage is applied between the torch electrode 44 and the welded portion WJ from the welding power supply circuit E _DC . As a result, the positive terminal of the welding power supply circuit E _DC → the switch SW in the ON state → the ground cable 64 → the clamp arm 60 → the welded portion WJ → the torch electrode 44 → the torch cable 39 in the hose 38 → the negative electrode of the welding power circuit E _DC A DC current for starting energization, that is, a start current i ₁ flows through the terminal path (closed circuit) 96 (FIG. 7C).

At this time, since the tip of the torch electrode 44 is in contact with the welded portion WJ of the base material (W ₁ , W ₂ ), no arc is generated regardless of the magnitude of the current i ₁ . However, in this embodiment, the current value of the start current i ₁ is controlled within a certain range by controlling the output voltage or output current of the welding power supply circuit E _DC . That is, in order to extend the life of the torch electrode 44, a small current value (usually 20 A or less) that causes only weak discharge that does not melt the welded portion WJ when the tip of the torch electrode 44 is pulled away from the welded portion WJ as it is. preferable. On the other hand, in order to stably generate a high-temperature arc discharge suitable for arc welding by separating the tip of the torch electrode 44 from the welded portion WJ, a Joule equivalent to the welded portion WJ is energized at this stage (contact state). It is necessary to generate heat. In this embodiment, the current value of the start current i ₁ is controlled within a range of 10 to 20 A from the viewpoints of both sides.

Thus, the start current i ₁ flows at a predetermined current value in the closed circuit 96 with the tip of the torch electrode 44 being in contact with the welded portion WJ of the base material (W ₁ , W ₂ ). Considerable Joule heat is generated (particularly near the tip) and the welded portion WJ.

When the predetermined time T ₁ has elapsed from the start of energization (step S ₁₀ ), the control unit moves the linear drive member 34 up by a certain amount, and the tip of the torch electrode 44 is set at a set separation distance (for example, 1 mm) from the welded portion WJ. Only upward (step S ₁₁ ), it is stopped at that height position. Then, after simultaneously pulling away the torch electrode 44, or the pull-off is completed, raise one step the output voltage of the welding power source circuit E _DC, more greater than the start current i ₁ of the current flowing in the closed circuit until it Switching to the regular direct current or main current i ₂ for arc discharge (step S ₁₂ ). The current value of the main current i ₂ is selected to a value (usually 30 A or more) that generates a high-heat arc sufficient to melt the welded portion WJ.

While the main current i ₂ is flowing in this way, the arc AC is maintained between the torch electrode 44 (particularly near its tip) and the welded portion WJ, and the welded portion WJ is melted by the heat of the arc AC (FIG. 7D). The current value of the main current i ₂ may be kept constant throughout, but in order to promote melting of the welded portion WJ, the current value of the main current i ₂ is further increased stepwise or gradually. It is also possible to use such current waveform control (or, conversely, down-slope current waveform control).

When a predetermined time T ₂ (usually _{2 to 3} seconds) has elapsed since the start of energization (step S ₁₃ ), the control unit switches the switch SW to an off state and stops energization (step S ₁₄ ). Immediately after that, the supply of the shielding gas SG is also stopped. When the energization is stopped and the main current i ₂ is turned off, the arc disappears at that moment. When the arc disappears, the molten portion of the welded portion WJ is immediately solidified by natural cooling in the atmosphere. In this way, the welded portions WJ of the base materials (W ₁ , W ₂ ) are welded and joined together or in one piece.

Thereafter, the control unit moves the clamp electrode 24 backward to release the pressurization or the clamping and fixing to the welded portion WJ (step S ₁₅ , FIG. 7E). Next, the straight drive member 34 is moved upward through the lift drive unit of the lift tower 30 to return the torch 22 and the clamp electrode 24 to the start position (step S ₁₆ ).

As described above, in this embodiment, the tip of the torch electrode 44 is applied to the clamp electrode 24 while applying a pressure for contact and fixation near the tip of the welded portion WJ of the base material (W ₁ , W ₂ ). Since the arc discharge is generated after starting energization while being in contact with the welded portion WJ (touch start method or lift start method), the arc AC is stably and reliably applied to the welded portion WJ (particularly the central portion thereof). By concentrating, it is possible to obtain desired welding quality (joining strength, appearance finish).

  In this regard, in this type of conventional TIG welding apparatus, since the torch electrode and the clamp are always in a fixed positional relationship, the touch start method cannot be taken, and the tip of the torch electrode is initially taken from the welded portion WJ. Energization was started in the separated state to generate arc discharge. However, in that case, not only an expensive high-frequency power supply or high-voltage DC power supply is required, but it is also very difficult to generate arc discharge so that the arc is always concentrated on the welded part (particularly the central part) On the positive electrode side, the arc is ignited at an indefinite position, and in some cases, the clamp arm 60 may be ignited as indicated by a virtual line (dashed line) AC ′ in FIG. 7D. For this reason, as shown in FIG. 8A, there is no other way to cope with this by setting the operating position of the clamp (the clamping and fixing position) to a position sufficiently far from the torch electrode. However, if the operating position (clamping fixing position) of the clamp is moved away from the torch electrode in this way, the adhesion is not guaranteed near the tip of the welded part WJ, and the desired arc welding quality can be obtained stably and reliably. It was difficult. In this embodiment, the problem of this prior art is solved as described above.

In addition, even when the touch start method is used, if a passive compliance device is not incorporated in the moving stage, if an error occurs in alignment by the moving stage, the clamping operation of the clamp electrode 24 performed thereafter is performed. However, it is difficult to correct the alignment error. As a result, touch start type TIG welding is performed in a state where the tip of the torch electrode 44 (center axis Z ₄₄ ) is displaced from the center of the welded portion WJ. As a result, as shown in FIG. 8B, the arc concentrates on a portion shifted from the central portion of the welded portion WJ (a portion where the tip of the torch electrode 44 abuts), and the central portion of the welded portion WJ (near the gap g) ) Does not melt sufficiently, the desired welding strength cannot be obtained, and the reproducibility and reliability of welding quality are low. In this embodiment, by incorporating the passive compliance device 26 into the stage 18 as described above, such a problem of the touch start method is also solved.

In particular, the TIG welding apparatus in this embodiment includes a rectilinear drive member 34 that is connected to the clamp electrode 24 and the torch body 40 and can move linearly in parallel with the axial direction of the torch electrode 44, and the clamp electrode 24 and the torch electrode 44 are connected to each other. A first position (FIG. 6A) for moving the base material (W ₁ , W ₂ ) away from the welded portion WJ and a second position (FIG. 6B) for placing the clamp electrode 24 in the operating position. A third position (FIG. 6D) for bringing the tip of the torch electrode 44 into contact with the welded portion WJ and a third position for separating the tip of the torch electrode 44 from the welded portion WJ by a predetermined distance suitable for arc generation. 4 (FIG. 6E), the rectilinear drive member 34 is configured to linearly move, so that the torch electrode and the clamp are efficiently coordinated and moved relative to the welded portion WJ by the uniaxial rectilinear drive mechanism. Rukoto are possible, and the problems of the prior art and efficient solution at a low cost. Of course, an expensive high-frequency power source or a high-voltage DC power source is unnecessary, and the welding power source circuit E _DC can be an inexpensive DC voltage source or DC current source with a low output.

[Other Embodiments or Modifications]

  As mentioned above, although preferred embodiment of this invention was described, embodiment mentioned above does not limit this invention. Those skilled in the art can make various modifications and changes in specific embodiments without departing from the technical idea and technical scope of the present invention.

For example, in the above-described embodiment, before the tip of the torch electrode 44 comes into contact with the welded portion WJ of the base material (W ₁ , W ₂ ), the clamp electrode 24 is pressed against the welded portion WJ (fixed). Like to start. In this case, since the lower end of the torch electrode 44 comes into contact with the welded portion WJ after the position of the welded portion WJ is corrected by the clamp electrode 24, the contact position can be accurately controlled. The tip of the torch electrode 44 can be accurately inserted into the gap between the base materials (W ₁ , W ₂ ). However, as a modified example, after the tip of the torch electrode 44 comes into contact with the welded portion WJ of the base material (W ₁ , W ₂ ), the clamp electrode 24 starts to pressurize (fix and fix) the welded portion WJ. It is also possible to do.

As another example (modification), as shown in FIG. 9, between the rectilinear drive member 34 and a part of the torch body 40 (for example, a hook-shaped spring receiving portion 80 fixed to the torch body 40), It is also possible to provide a spring member that can be elastically deformed in the direction in which the linear drive member 34 moves, such as a coil spring 82. In this case, by using a compression coil spring for the coil spring 82, the load received by the welded portion WJ when the torch electrode 44 comes into contact with the welded portion WJ can be arbitrarily reduced from the own weight of the torch body 40. This is an advantageous form when the base material (W ₁ , W ₂ ) is a terminal member of a small precision electronic component. Alternatively, by using a tension coil spring for the coil spring 82, the load received by the welded portion WJ when the torch electrode 44 contacts the welded portion WJ can be arbitrarily increased from the own weight of the torch body 40. In addition, the spring force of the coil spring 82 can also be adjusted by providing a mechanism (not shown) for adjusting the position of the spring receiving portion 80.

Similarly, a spring that can be elastically deformed in the direction in which the rectilinear drive member 34 moves between the rectilinear drive member 34 and a part of the elevating rod 56 (for example, a hook-shaped spring receiving portion 84 fixed to the elevating rod 56). It is also possible to provide a member, for example a coil spring 86. In particular, by using a compression coil spring for the coil spring 86, the load received by the base material (W ₁ , W ₂ ) when the clamp electrode 24 sandwiches the welded portion WJ is reduced as much as possible. Damage to the materials (W ₁ , W ₂ ) can be prevented.

  In the configuration in which the torch body 40 and the lifting rod 56 are attached to the rectilinear drive member 34 via the coil springs 82 and 86 as described above, the rectilinear drive member 34 is moved linearly in an oblique direction or a horizontal direction, and the torch electrode 44 and the clamp electrode are moved. It is also possible to move 24 straight in the same direction.

  The plate-like form of the rectilinear drive member 34 in the above-described embodiment is an example, and the rectilinear drive member 34 can take a plate, block, cylinder, or housing structure having an arbitrary shape. Similarly, the connecting members 66 and 68 can take any form.

  In the above-described embodiment, the torch 22 is directly attached to the rectilinear drive member 34. However, as shown in FIG. 10, a rectilinear movable member 88 such as an elevating rod is attached to the rectilinear drive member 34 so as to be integrally movable and separable in the vertical direction, and a torch is attached to a holder 89 coupled to the rectilinear movable member 88. The structure which attaches 22 so that attachment or detachment is possible is also possible.

In the above embodiment, since the thickness of the base metal members W ₁ and W ₂ is substantially the same, as shown in FIG. 7B, the tip of the torch electrode 44 or the central axis Z ₄₄ is the metal member W ₁ , The central axis Z ₄₄ of the torch electrode ₄₄ and the welded portion WJ are opposed to the central portion of W _{2 in} the thickness direction (overlapping direction), that is, the gap g (contact position of the metal members W ₁ and W ₂ ). Alignment between them is performed. In this case, the central axis Z ₄₄ of the torch electrode 44 and the center of the clamp 60 substantially overlap. However, when the metal members W ₁ and W ₂ have different plate thicknesses, the central axis Z ₄₄ of the torch electrode 44 is shifted from the central portion (the gap g) of the metal members W ₁ and W _{2 in} the plate thickness direction (overlapping direction). position) and so as to face (FIG. 11A), or such that the center axis Z ₄₄ of the torch electrode 44 facing the metal member W _1, W ₂ of clearance g (contact position of the metal member W _1, W ₂₎ (Figure 11B), the alignment between the central axis Z ₄₄ of the torch electrode 44 and the welded portion WJ is performed. According to the present invention, in the latter case (FIG. 11B), the center axis Z ₄₄ of the torch electrode 44 and the center of the clamp 60 can be set to be shifted.

  Although the TIG welding apparatus in the above embodiment is a stationary type, a form mounted on a robot is also possible. In that case, the linear drive member 34 or the lifting support shaft 32 may be coupled to the robot arm.

  The stage 18 of the welding head 12 in the above embodiment has an XY stage 25 that is movable on the base 16 in a horizontal XY plane. However, the stage 18 may include a θ stage movable in the rotation (θ) direction in addition to the XY stage 25, and may further include a Z stage movable in the vertical (Z) direction.

Alternatively, the stage 18 is constituted by a fixed stage fixed in a horizontal plane in place of the moving stage, and a work (electrical component support S or metal members W ₁ , W ₂ ) is placed on the fixed stage, and the torch Position alignment between the electrode 44 and the clamp electrode 24 and the welded portion WJ can be performed on the torch stand 20 that supports the torch electrode 44 and the clamp electrode 24 or on the robot side. Again, a passive compliance device is provided between the fixed stage and the table 28.

In the welded portion WJ, material of the metal member or terminal members W _1, W ₂ is not limited to copper or a copper alloy, for example it may be a conductor of aluminum or an aluminum alloy case and brass, of the terminal member W ₁ The material and the material of the terminal member W ₂ may be different. The shape of the terminal members W ₁ and W ₂ may be arbitrary. For example, the terminal members W ₁ and W ₂ are not limited to a rod or plate having a rectangular cross section, and may be a rod or plate having a circular cross section.

DESCRIPTION OF SYMBOLS 10 Apparatus main body 12 Welding head 18 Stage 22 Torch 24 Clamp electrode 26 Passive type compliance device 28 Table 30 Lifting tower 34 Straight drive member 40 Torch body 44 Torch electrode 56 Lifting bar 66, 68 Connecting member 70 Sensor 80, 84 Spring receiving part 82, 86 Coil spring W ₁ , W ₂ terminal member (base material)
WJ welded part

Claims (11)

A stage parallel to the XY plane;
A passive compliance device provided on the stage and slidable in any direction within the XY plane;
A clamp electrode capable of holding the first and second members placed on the compliance device as a base material in close contact with each other at a welded portion; and
A torch body that detachably attaches and holds a torch electrode; and
A welding power source for flowing current in a closed circuit including the torch electrode and the welded portion;
Have
A voltage is applied between the torch electrode and the welded portion by the welding power source in a state where a pressure is applied to the welded portion by the clamp electrode and the tip of the torch electrode is in contact with the welded portion. Applying and starting energization in the closed circuit, while continuing to pressurize the welded portion and energize in the closed circuit, the tip of the torch electrode is separated from the welded portion, and the torch electrode and the A TIG welding apparatus that generates an arc with a welded portion and welds the welded portion with the heat of the arc.   The TIG welding apparatus according to claim 1, wherein the compliance device includes a base portion fixed to the stage and a movable portion slidably mounted on the base portion via a ball guide.   The TIG welding apparatus according to claim 1, wherein the stage is a moving stage that is movable at least in an XY plane.   The clamp electrode includes a clamp that clamps and fixes the first and second members with electromagnetic force, pneumatic pressure, or hydraulic pressure near a portion of the welded portion that faces the torch electrode. The TIG welding apparatus as described in any one of 1-3.   The portion of the clamp electrode that contacts the welded portion is a conductor that is electrically connected to the welding power source, and the conductor forms part of the closed circuit when the current flows in the closed circuit. The TIG welding apparatus as described in any one of Claims 1-4. A rectilinear drive member that supports the clamp electrode and the torch body and can move linearly parallel to the axial direction of the torch electrode;
A first position for moving the clamp electrode and the torch electrode away from the welded part, a second position for placing the clamp electrode in an operating position, and a tip of the torch electrode at the welded part The rectilinear drive member is linearly moved between a third position for contact and a fourth position for separating the tip of the torch electrode from the welded portion by a predetermined distance suitable for arc generation. ,
The TIG welding apparatus as described in any one of Claims 1-5.   The welding power source controls the current flowing in the closed circuit to be equal to or lower than a first current value when the tip of the torch electrode is in contact with the welded portion, and the tip of the torch electrode is The TIG welding apparatus according to any one of claims 1 to 6, wherein the TIG welding apparatus is controlled to be equal to or greater than a second current value larger than the first current value after being separated from a portion.   The TIG welding apparatus according to claim 7, wherein the first current value is 20A or less, and the second current value is 30A or more. Placing the first and second terminal members as the base material on a passive compliance device that can slide in any direction within the XY plane;
The first and second terminal members placed on the compliance device are held in close contact with the welded portion; and
Bringing the tip of the torch electrode into contact with the welded part;
A voltage is applied between the torch electrode and the welded part in a state where a pressing force for tightly fixing the welded part is applied and the tip of the torch electrode is in contact with the welded part. Starting energization in a closed circuit including the torch electrode and the welded portion;
While continuing the pressurization to the welded part and energization in the closed circuit, the tip of the torch electrode is separated from the welded part, and an arc is generated between the torch electrode and the welded part, Melting the welded portion by the heat of the arc;
Stopping energization in the closed circuit and releasing pressure on the welded part;
A TIG welding method having:   In the step of holding the first and second terminal members in close contact with each other at the welded portion, the first and second terminal members are clamped by a clamp electrode, whereby the central axis of the torch electrode and the first The TIG welding method according to claim 9, wherein the contact positions of the first and second terminal members are opposed to each other.   In the step of holding the first and second terminal members in close contact with each other at the welded portion, the first and second terminal members are clamped by a clamp electrode, whereby the central axis of the torch electrode and the first The TIG welding method according to claim 9, wherein the central portion of the first and second terminal members in the overlapping direction is opposed to each other.

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