JP2015202505A - Tig welding method and tig welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and surely execute a touch-start system TIG welding method even if a more or less error is caused in positioning between a torch electrode and a welding object part, by reducing deformation of the tip of the torch electrode.SOLUTION: In this TIG welding method, a tip surface 42b of a torch electrode 42 having a minus shape or a paper-strip shape is applied to a top face of a welding joint WJ (terminal members W, W), and while supplying shield gas SG, electric conduction is started in this state, and then, the tip surface 42b of the torch electrode 42 is separated from a welding object part WJ, so that an arc is generated in a gap space between the tip surface 42b of the torch electrode 42 and the welding joint WJ. Even if the central axis of the torch electrode is dislocated from the center (particularly, a clearance (g)) of the welding object part by positioning operation, since the tip surface 42b of the torch electrode 42 abuts on the welding object part by straddling the clearance (g), the arc is surely concentrated in the central part vicinity of the welding object part WJ, and excellent welding strength can be provided.

Description

  The present invention relates to a TIG welding method and apparatus for welding a terminal member used for wiring connection of an electric circuit or the like.

  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, welding, soldering, pressure bonding, pressure welding, or the like is used for connection between discrete terminal members. Among these connection methods, welding is most excellent in stability, reliability and permanentness.

  Conventionally, arc welding, resistance welding, and YAG laser welding are often used for welding of this type of terminal member. However, when the material of the terminal member is copper or a copper alloy, it is difficult to apply resistance welding because the resistivity of copper is low (thus, the resistance heat generation is low), and for the fundamental wavelength (1064 nm) of the YAG laser. Since it is difficult to apply a YAG laser because of the high reflectivity of copper (and therefore, the absorption of laser energy is small), an arc welding method using an electric discharge phenomenon (arc discharge) is often used. In particular, in terminal member welding of an electric circuit including a small electric component, a TIG welding method using a non-consumable torch electrode (tungsten electrode rod) is often used.

International Publication WO2010 / 018778

  In the TIG welding method using a non-consumable torch electrode, the main methods for starting arc discharge are a high-frequency generation method in which dielectric breakdown is caused by high-frequency discharge at the start, and a torch electrode is used only at the start. A DC high voltage application method in which a high voltage of DC of 10 kV or more is applied to the base material to cause dielectric breakdown and shift to an arc, and energization was started by contacting the torch electrode with the base material without using a high frequency. There are three types of touch start (or lift start) methods that generate arc discharge by pulling back. The high frequency generation method and the DC high voltage application method require a power source that generates high frequency or high voltage, which increases the cost of the welding machine, and high frequency or high voltage noise causes electrical components of the electric circuit and surroundings. The negative impact on electronic equipment is hated at many welding sites. In this respect, since the touch start method does not use a high frequency power source or a high voltage DC power source, the cost of the welding machine can be reduced and there is no problem of high frequency noise.

  However, in the conventional TIG welding method using the touch start method, the tip of the torch electrode having a sharp conical shape tends to be rounded and deformed while repeatedly touching (contacting) with the base material or the welded portion. When the tip of the torch electrode is deformed to a round shape, the concentration of the arc is deteriorated, the penetration depth of the welded portion is reduced, and the welding quality is deteriorated. Therefore, at the welding site, a dedicated electrode polisher is provided to polish the tip shape of the torch electrode into a pre-defined sharp conical shape, and this electrode polisher is used to polish the electrode tip at a short cycle. We carry out frequently. However, frequent polishing of the torch electrode consumes the torch electrode (tungsten electrode rod) quickly, increasing the running cost and interrupting the welding operation every time the electrode is polished, resulting in a decrease in production efficiency. This is a real challenge.

  Further, in the touch start method, prior to arc welding, alignment is performed so that the tip of the torch electrode is opposed to the vicinity of the center of the welded portion, that is, the vicinity of the gap between the two terminal members. However, when the terminal member is a thin wire or rod, or when a large number of welded parts are welded by the TIG welding method in a short tact time, an error tends to occur in the alignment between the torch electrode and the welded part. For example, a bus bar, which is an elongated bar-like or plate-like conductor metal used to supply power to a large number of integrated circuits on an on-vehicle circuit board, is mounted on the circuit board and in many places. Receives joint processing. When the TIG welding method is used for such a bus bar joining process, the alignment operation between the torch electrode and each welded portion on the circuit board is performed at a high speed in order to shorten the tact time, that is, to improve the productivity. During the process, the tip of the torch electrode may be displaced from the center of the welded part.

  When touch-start TIG welding is performed in such a state that the tip of the torch electrode is displaced from the center of the welded portion, the portion that is displaced from the center of the welded portion (the portion where the tip of the torch electrode contacts) ) And the center of the welded portion (near the gap) is not sufficiently melted, so that the desired welding strength cannot be obtained, and the reproducibility and reliability of the welding quality cannot be guaranteed.

The present invention solves the problems of the prior art as described above, can reduce the deformation of the tip of the torch electrode, and causes a slight error in alignment between the torch electrode and the welded portion. However, a TIG welding method and a TIG welding apparatus capable of stably and surely implementing a touch start type TIG welding method are provided.
[Means for solving problems]

  The TIG welding method of the present invention includes a first step of forming a welded portion by combining the first and second metal members, and a tip surface of a torch electrode having a minus shape or a rectangular shape contacting the welded portion. And the second step of the step, and while the tip of the torch electrode is in contact with the welded portion, while supplying a shielding gas around the torch electrode, between the torch electrode and the welded portion A third step of starting energization by applying a voltage; and while continuing the supply of the shield gas and the energization, the tip surface of the torch electrode is separated from the welded portion, and the torch electrode and the welded And a fourth step of melting the welded portion by the heat of the arc and a fifth step of extinguishing the arc and solidifying the molten portion of the welded portion. .

  The TIG welding apparatus according to the present invention includes a torch body that detachably mounts and holds a rod-like torch electrode, and energizes between the tip of the torch electrode and the welded part in a touch start method, or generates an arc. A welding power source for passing a current in a closed circuit including the torch electrode and the welded portion, and a relative contact and separation between the tip of the torch electrode and the welded portion in a touch start method. And a tip end surface of the torch electrode has a negative shape or a rectangular shape.

  In the present invention, the front end surface of the torch electrode having a minus shape or a rectangular shape is applied to the welded portion, and the energization is started in this state while supplying the shielding gas, and then the front end surface of the torch electrode is applied to the welded portion. An arc is generated in the gap space between the torch electrode and the welded part by pulling away from the torch. According to such a touch start method, even if the center axis of the torch electrode is slightly deviated from the center of the welded part (especially the gap between the two metal members) in the alignment operation between the torch electrode and the welded part, the torch electrode Since the front end surface of the steel plate contacts the welded portion across the gap, the arc can be reliably concentrated near the center of the welded portion. As a result, the center of the welded portion can be reliably melted with arc heat, and good welding strength can be obtained.

  Furthermore, since the tip surface of the torch electrode is in contact with the welded part not by point contact but by line contact, the electrode tip is not easily crushed even if the touch start is repeated (without being rounded). The elongated tip surface shape can be maintained for a long time. This can reduce the consumption of the torch electrode and reduce the running cost.

  In the present invention, the torch electrode is preferably such that the longitudinal direction of the front end surface of the torch electrode is orthogonal to or obliquely intersects with the direction in which the gap between the first and second metal members extends on the surface of the welded portion. The tip surface of the electrode is applied to the surface of the welded part.

  In the present invention, the longitudinal size of the tip surface of the torch electrode is preferably 2/3 or more of the thickness of the welded portion including the first and second metal members, and more preferably the welded portion. Or more.

  According to the TIG welding method and the TIG welding apparatus of the present invention, it is possible to reduce the deformation of the tip of the torch electrode and to align the torch electrode and the welded portion by having the above-described configuration and action. Even if some errors occur, the touch start type TIG welding method can be stably and reliably performed.

It is a perspective view which shows the whole structure of the TIG welding apparatus in one Embodiment of this invention. It is a perspective view which shows an example of the to-be-welded part in embodiment. It is a figure which shows the ideal position alignment between the shape of the front end surface of the torch electrode in an embodiment, and a torch electrode and a to-be-welded part. It is a fragmentary sectional view which shows the structure of the principal part of the torch in embodiment. It is a partial cross section side view which shows the structure and effect | action of the torch support mechanism in embodiment. It is a partial cross section side view which shows the structure and effect | action of the torch support mechanism in one modification. It is a timing diagram for demonstrating operation | movement of each part of the TIG welding apparatus in embodiment. It is a figure which shows typically the example in case the center axis | shaft of a torch electrode shift | deviates greatly from the center of a to-be-welded part by the alignment in embodiment. It is a figure which shows the procedure of the terminal member welding method in embodiment, and the state of each step. It is a figure which shows the procedure of the terminal member welding method in embodiment, and the state of each step. It is a figure which shows the structure of the front-end | tip part of the torch electrode in the modification of embodiment. It is a figure which shows the structure of the front-end | tip part of the torch electrode in another modification. It is a figure which shows the structure of the front-end | tip part of the torch electrode in another modification. It is a figure which shows the structure of the front-end | tip part of the torch electrode in another 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 machine in one Embodiment of this invention is shown.

  This TIG welding machine includes a unit-type apparatus main body 10 incorporating a DC welding power supply circuit, a control circuit, and the like, and an electric component support (for example, an assembly or circuit) under the supply and control of utility force from the apparatus main body 10. The welding head 12 which performs TIG welding to the to-be-welded material or the base material WJ on the board | substrate S, and the supply source, for example, gas cylinder 14, of shielding gas or inert gas (for example, 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 is mounted on the torch stand 20 so as to be movable up and down. More specifically, the stage 18 is used to move the electric component support S in the XY direction in the horizontal plane and the electric component support S in the azimuth direction (θ direction) in the horizontal plane. θ stage 26. An elevating tower 30 having a built-in elevating mechanism (not shown) is provided on a base 28 fixed to the torch stand 20, and a rod-like torch is provided on the elevating tower 30 via an elevating drive shaft 32 and a torch support 34. 22 is attached to be vertically movable in an upright posture.

The position of the torch 22 is fixed in the horizontal direction. The XY stage 24 and the θ stage 26 perform a movement operation in the XY direction and a movement (rotation) operation in the θ direction under the control signal sent from the apparatus main body 10 via the cable 25, respectively. The welded portion WJ (W ₁ , W ₂ ) to be subjected to TIG welding on the placed electrical component support S can be positioned with high accuracy directly under the torch 22.

  The torch 22 is supplied with electric power and inert gas for TIG welding from the apparatus main body 10 via a hose 36 with a built-in torch cable, and a cylindrical torch body 38 made of an insulator, for example, resin, and this The torch body 40 has a cylindrical or conical torch nozzle 40 that is detachably attached to the lower end of the torch body 38, and a torch electrode (tungsten electrode rod) 42 is detachably mounted in the torch body 38 and torch nozzle 40. The tip of the torch electrode 42 protrudes from the lower end of 40.

  In the apparatus main body 10, a display 44, operation buttons 46, a power switch 48, and the like are arranged in a touch panel form on the front side of the unit, and external connection terminals or connectors 50 are arranged on the side surface or rear surface of the unit. The shield gas sent from the gas cylinder 14 to the hose 15 is supplied to the torch 22 via the apparatus main body 10.

FIG. 2 shows an example of a workpiece (base material) to which TIG welding can be applied in this embodiment. 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).

It should be noted that a pair of contacts (contacts) C ₁ and C ₂ constituting a ground electrode are detachably contacted with the metal members W ₁ and W ₂ from both the left and right sides, avoiding the welded portion WJ. These contacts C ₁ and C ₂ are electrically connected to the positive electrode of the power supply circuit in the apparatus main body 10 via the ground cable 54.

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 this embodiment, as shown in FIG. 2, the tip 42a of the torch electrode 42 is tapered in one direction (Y direction in the figure) perpendicular to the axial direction (Z direction in the figure) of the torch electrode. The shape of the front end surface 42b of the torch electrode 42 is a minus (−) shape or a rectangular shape. Such a configuration of the tip 42a of the torch electrode 42 is formed by machining such as cutting or grinding.

FIG. 3A shows a tip surface 42b when the torch electrode 42 is viewed from vertically below. Also, in FIG. 3B, the relative position between the tip surface 42b of the torch electrode 42 and the surface (top surface) of the welded portion WJ that overlaps with each other in an ideal alignment. And size relationship. Here, the ideal alignment between the torch electrode 42 and the welded portion WJ, overlap the center O _WJ or substantially the vicinity of the central axis N ₄₂ is the top surface of the welded portion WJ of the torch electrode 42, And the relative position where the longitudinal direction (X direction of a figure) of the front end surface 42b of the torch electrode 42 is substantially orthogonal to the direction (Y direction of a figure) where the clearance gap g extends on the top face of the to-be-welded part WJ. This is a case where a relationship is established between the two.

The size L _{42 in} the longitudinal direction of the tip surface 42b of the torch electrode 42 is preferably 2/3 or more of the thickness D _WJ of the welded portion WJ in which the two metal members W ₁ and W ₂ are combined, and more preferably FIG. As shown in (b), the thickness D _WJ or more of the welded portion WJ. Accordingly, the thickness (diameter) φ ₄₂ of the torch electrode ₄₂ is selected so that such a condition (L ₄₂ ≧ 2D _WJ / 3 or L ₄₂ ≧ D _WJ ) is satisfied. As an example, when the thickness of each of the metal members (bus bars) W ₁ and W ₂ is 1 mm (when the thickness D _WJ of the welded portion _WJ is about 2 mm), the thickness φ ₄₂ of the torch electrode 42, that is, the tip surface The longitudinal direction size L ₄₂ of 42b is selected to be 3.2 mm, and the lateral direction size S ₄₂ of the tip surface 42b of the torch electrode ₄₂ is selected to be 1 mm.

  In FIG. 4, the structure of the principal part (lower end part) of the torch 22 is shown. In the torch body 38, there is provided a collet 56 with a slot for holding a rod-like torch electrode 42 made of tungsten or a tungsten alloy at the center, that is, the axis of the torch 22. The collet 56 is surrounded by a collet body 58 with a large slit having a thread 58a formed on the outer peripheral surface. The thread 58 a of the collet body 58 is screwed with the thread 40 a formed on the inner peripheral surface of the torch nozzle 40. For example, when the torch nozzle 40 is rotated clockwise so as to be sent to the torch body 38 side, the lower end portion of the collet body 58 is deformed in the direction of narrowing the diameter, and the torch electrode 42 is sandwiched (held) via the collet 56. It has become.

  A cylindrical gas passage 60 is formed between the collet 56 and the collet body 58 to guide the shield gas SG introduced into the upper part of the torch body 38 from the hose 36 (FIG. 1) downward. A plurality of through holes 58b are formed in the lower end portion of the collet body 58 at predetermined intervals in the circumferential direction. The shield gas SG that has come down the gas passage 60 passes through the through hole 58 b and exits to the space between the torch electrode 42 and the torch nozzle 40 or the nozzle chamber 62, and exits from the lower end of the nozzle chamber 62, that is, the jet port 64. It comes to erupt outside. The torch nozzle 40 is preferably made of ceramic (for example, alumina), and a thin plate-like or foil-like conductor 66 for preventing misfire is stuck on the inner peripheral surface thereof.

  In the torch 22 of this embodiment, as shown in FIGS. 1 and 5, the torch body 38 is passed through the through hole 34 a of the plate-like torch support 34, and the upper part or the middle part of the torch body 38. The torch body 38 is attached to the torch support 34 so that the fixed flange-shaped flange 68 is placed on the upper surface of the support 34. According to such a torch support structure, when the elevating tower 30 moves the torch support 34 up and down while the tip surface 42b of the torch electrode 42 is floating in the air, the torch 22 is integrated with the torch support 34. Move up and down (FIG. 1). However, when the torch support 34 is lowered after the front end surface 42b of the torch electrode 42 reaches the base material W, the flange 68 of the collet body 58 is separated from the torch support 34 as shown in FIG. 22 stands on the base material W independently of the torch support 34. At this time, the weight of the torch 22 is applied to the base material W side. This torch self-weight pressurization method is advantageous when the torch 22 is moved in the vertical direction as in this embodiment.

  As another configuration example, as shown in FIG. 6, a pair of parallel support plates, that is, an upper support plate 34U and a lower support plate 34L, which are elastically displaced in a vertical direction via a compression coil spring 70, are supported by a torch support. 34 may be configured. In this case, the upper support plate 34U is fixed to the lift drive shaft 32, and the flange 68 of the torch body 38 is fixed to the lower support plate 34L. In such a torch support structure, the torch 22 remains coupled to the torch support 34 (lower support 34L) even after the tip surface 42b of the torch electrode 42 reaches the base material W, and the torch tower 30 side When a downward pressing force is applied, the spring force of the compression coil spring 70 is applied to the base material W via the torch 22. This spring pressing method can be used not only when the torch 22 is moved in the vertical direction but also when it is moved in the oblique direction or the lateral direction.

Next, with reference to FIGS. 7-9, operation | movement and an effect | action (TIG welding method) of the TIG welding apparatus in this embodiment are demonstrated. In FIG. 8, “0” at the height position of the tip of the torch electrode corresponds to the height position of the top surface of the welded portion WJ (W ₁ , W ₂ ).

First, the XY stage 24 and the θ stage 26 are mounted on the apparatus main body as described above in a state where the electric component support S on which the welded portion WJ (W ₁ , W ₂ ) is mounted is placed on the stage 18. The alignment operation is performed under the control of 10. By this positioning operation, the welded portion WJ (W ₁ , W ₂ ) is positioned directly below the torch electrode 42. However, when a large number of welded parts WJ are mounted on the electric component support S and the above alignment operation is performed at a high speed in order to shorten the tact time, the torch electrode 42 and the welded part WJ As shown in FIG. 3B, an ideal alignment in which the centers (N ₄₂ , O _WJ ) of each other coincide with each other or are close to each other is not always achieved. As shown in (a) and (b), the mutual center (N ₄₂ , O _WJ ) may deviate greatly.

After completion of the alignment, as described above, under the control of the apparatus main body 10, the lifting mechanism of the lifting tower 30 is operated, the height position for waiting the torch 22 (the initial position) down from H _C vertically downward ( t = t ₀ -t ₂ ). Then, supply of the shield gas SG is started while the torch 22 is being lowered (t = t ₁ ). Eventually, when the tip surface 42b of the torch electrode 42 touches the top surface of the welded portion WJ, the torch support 34 is further lowered by a certain distance, so that the torch 22 is separated from the support 34 and becomes the welded portion WJ. Add your own weight. Thereby, the front end surface 42b of the torch electrode 42 comes into contact with or comes into contact with the top surface of the welded portion WJ.

Thus, after the front end surface 42b of the torch electrode 42 hits the top surface of the welded portion WJ, the switch SW of the output of the DC welding power supply circuit E _DC is switched from the previous OFF state to the ON state in the apparatus main body 10 ( t = t ₃ ). Then, the output voltage of the DC welding power supply circuit E _DC is applied between the torch electrode 42 and the welded portion WJ. Thus, the welding power supply circuit E _DC positive terminal → switch SW → grounding cable 54 → the contact C ₁ in the ON state, C ₂ → welded portion WJ (bus bar W _1, W ₂₎ → torch electrode 42 → hose 36 The torch cable 37 → the welding power supply circuit E _DC flows through the negative electrode terminal path (closed circuit) 72, and a DC current (start current) i _DC for starting energization flows ((c) in FIG. 8). However, since the front end surface 42b of the torch electrode 42 is in contact with the top surface of the welded portion WJ, no arc is generated even if a DC current i _{DC of} about 15 A, for example, flows in the closed circuit 72.

Thus, the direct current i _DC flows at a predetermined current value I ₁ (for example, 15 A) in the closed circuit 70 with the tip surface 42b of the torch electrode 42 being in contact with the top surface of the welded portion WJ. Considerable Joule heat is generated at the electrode 42 (particularly in the vicinity of the tip 42a) and the welded portion WJ.

Next, at a predetermined timing (t = t ₄ ), the elevating mechanism of the elevating tower 30 raises the torch electrode 42 vertically upward. As a result, when the torch electrode 42 is raised and the tip surface 42b is separated from the top surface of the welded portion WJ to form a gap (t = t ₆ ), an arc (discharge) AC is generated at the gap. As the torch electrode 42 is raised, that is, as the gap increases, the arc AC expands to the surroundings. When the tip surface 42b of the torch electrode 42 is pulled up to a height position H _S that separates a certain distance (usually 1 mm to 3 mm) from the welded portion WJ (t = t ₆ ), the torch electrode 42 is stopped at that position.

Thus, the arc is maintained between the tip 42a of the torch electrode 42 (particularly near the tip surface 42b) and the welded portion WJ, and the welded portion WJ is melted by the heat of the arc AC. Here, the current value of the direct current i _DC that flows in the closed circuit 72 may be maintained at a constant value I ₁ throughout, but in order to promote melting of the welded portion WJ (t = t _7). ) To control the current waveform such that the current value of the direct current, that is, the arc current i _DC is increased stepwise from the _first set value I ₁ (15A) to the second set value I ₂ (for example, 100 to 200 A). It can be used suitably.

When a predetermined energization time (usually 100 to 200 msec) elapses, the switch SW is switched off in the apparatus main body 10 (t = t ₈ ), and when the arc current i _DC is turned off, the arc is instantaneously generated. Disappear. Immediately after that, the supply of the shielding gas SG is also stopped (t = t ₉ ). Thereafter, in the welding head 12, the lifting mechanism of the lifting tower 30 returns the torch electrode 42 to the standby height position H _C (t = t _{10 to} t ₁₁ ).

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 terminal members W ₁ and W ₂ are welded and joined together or in one piece at the welded portion WJ.

In this embodiment, as described above, the front end surface 42b of the torch electrode 42 having a minus (−) shape or a rectangular shape is applied to the top surface of the welded portion WJ, and the shield gas SG is supplied while this state is maintained. Then, energization is started, and then the tip surface 42b of the torch electrode 42 is separated from the welded portion WJ, thereby generating an arc AC in the gap space between the tip surface 42b of the torch electrode 42 and the welded portion WJ. ing. According to such a touch start method, the center axis N42 of the torch electrode 42 is, for example, shown in FIGS. 7A and 7B in the alignment operation between the torch electrode 42 and the welded portion WJ (W ₁ , W ₂ ). As shown in FIG. 3, even if the center O _WJ (particularly the gap g) of the welded portion WJ (W ₁ , W ₂ ) is greatly deviated, the tip surface 42b of the torch electrode 42 straddles the gap g and the welded portion WJ (W ₁ , W ₂ ), the arc can be reliably concentrated near the center of the welded portion WJ (W ₁ , W ₂ ). As a result, it is possible to reliably melt the center portion of the welded portion WJ (W ₁ , W ₂ ) with arc heat to obtain a good welding strength, and to guarantee the reproducibility and reliability of the welding quality. be able to.

Furthermore, since the tip surface 42b of the torch electrode 42 is in pressure contact with the welded portion WJ (W ₁ , W ₂ ) by line contact instead of point contact, the electrode tip can be maintained even if touch start is repeated. The shape of the elongated tip surface can be maintained for a long time without being easily crushed (without being deformed into a round shape). As a result, the consumption of the torch electrode 42 can be reduced and the running cost can be reduced. Further, since it is not necessary to frequently polish the tip 42a of the torch electrode 42, the number of times that the welding operation is interrupted for electrode polishing is reduced, and the efficiency of terminal member welding or connection work can be improved.

[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, as a modification regarding the configuration of the tip end portion 42a of the torch electrode 42, as shown in FIG. 10A, a configuration in which the cross-sectional shape of the torch electrode 42 extends straight in the axial direction while maintaining a constant negative shape or rectangular shape. Is possible. Alternatively, as another modification, as shown in FIG. 10B, the taper is tapered in one direction perpendicular to the axial direction halfway toward the tip, and then the cross-sectional shape is a constant negative shape or rectangular shape. A configuration that extends straight to the tip while keeping it is also possible. Further, according to the thickness of the welded part (not shown), it is possible to cut both ends of the tip part 42a as shown by a dotted line 75 in FIG. 10B to shorten the longitudinal size of the tip surface 42b. . Alternatively, at the tip of the torch electrode, a configuration in which the taper TP _Y is formed only in one direction (Y direction) as shown in FIG. 10C, or a large taper TP _Y in one direction (Y direction) as shown in FIG. 10D. A configuration is also possible in which a small taper TP _X is formed in a direction (X direction) that is formed and orthogonal thereto.

  Further, the TIG welding apparatus in the above embodiment includes an automatic alignment mechanism (XY stage 24, θ stage 26) on the stage 18 of the welding head 12. However, the stage 18 can be configured as a manually movable stage, or the workpiece or the electrical component support S can be manually positioned on the fixed stage 18.

In the welded portion WJ, the material of the terminal member or a metal member 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, a metal member W ₁ The material and the material of the terminal member W ₂ may be different. Further, the shape of the metal members W ₁ and W ₂ may be arbitrary, and for example, the metal member W ₁ or W ₂ is not limited to a rod or plate having a rectangular cross section, and may be a rod or plate having a circular cross section.

10 apparatus main body 12 the welding head 14 the cylinder 18 the stage 22 torch 30 lift tower 38 torch body 40 torch nozzle 42 torch electrode 42a tip surface WJ welded portion W of the tip portion 42b torch electrode of the torch electrode _1, W ₂ bus bar (metal member)

Claims (10)

A first step of combining the first and second metal members to form a welded portion;
A second step of applying a tip surface of a torch electrode having a negative shape or a rectangular shape to the welded portion;
Under the state where the tip surface of the torch electrode is in contact with the welded part, a voltage is applied between the torch electrode and the welded part while supplying a shielding gas around the torch electrode. A third step of starting
While continuing the supply of the shielding gas and the energization, the tip of the torch electrode is separated from the welded portion, an arc is generated between the torch electrode and the welded portion, and the arc heat causes the A fourth step of melting the welded part;
A fifth step of extinguishing the arc and solidifying the molten part of the welded part;
A TIG welding method having:   In the second step, the longitudinal direction of the tip surface of the torch electrode is orthogonal to the direction in which the gap between the first and second metal members extends on the surface of the welded portion, or crosses diagonally. The TIG welding method according to claim 1, wherein a front end surface of the torch electrode is applied to a surface of the welded portion.   3. The TIG according to claim 1, wherein a size in a longitudinal direction of a front end surface of the torch electrode is 2/3 or more of a thickness of the welded portion including the first and second metal members. Welding method.   3. The TIG welding method according to claim 1, wherein a size in a longitudinal direction of a distal end surface of the torch electrode is equal to or greater than a thickness of the welded portion in which the first and second metal members are combined. A torch body that detachably attaches and holds a rod-shaped torch electrode;
A welding power source for supplying a current in a closed circuit including the torch electrode and the welded part in order to conduct an electric current between the tip of the torch electrode and the welded part in a touch start method, or to generate an arc;
A moving mechanism for performing relative contact and separation between the tip of the torch electrode and the welded part in a touch start method;
Have
A TIG welding apparatus, wherein a tip surface of the torch electrode has a negative shape or a rectangular shape.   The TIG welding apparatus according to claim 5, wherein a tip portion of the torch electrode is tapered in a direction perpendicular to the axial direction of the torch electrode.   6. The TIG welding apparatus according to claim 5, wherein the tip portion of the torch electrode extends straight in the axial direction of the torch electrode while maintaining a cross-sectional shape of the torch electrode in a certain negative shape or strip shape.   The size of the longitudinal direction of the front end surface of the torch electrode is 2/3 or more of the thickness of the welded portion in which the first and second metal members are combined. The TIG welding apparatus as described.   The TIG welding as described in any one of Claims 5-7 whose size of the longitudinal direction of the front end surface of the said torch electrode is more than the thickness of the said to-be-welded part which match | combined the said 1st and 2nd metal member. apparatus.   The welding power source controls the current flowing in the closed circuit to be equal to or less than a first current value when the tip surface of the torch electrode is in contact with the workpiece, and the tip of the torch electrode is The TIG welding apparatus according to any one of claims 5 to 9, wherein the TIG welding apparatus is controlled to be not less than a second current value larger than the first current value after being separated from the welding material.

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