JP7245935B2 - TIG welding method and TIG welding equipment - Google Patents

Description

The present invention relates to a touch-start TIG welding method and TIG welding apparatus.

Conventionally, the TIG welding method using a non-consumable torch electrode has been widely used for joining terminal members of small electric parts together or joining a terminal member and a conductor wire.

In the TIG welding method that uses a non-consumable torch electrode, there are two methods for starting arc discharge: In other words, there is a direct current high voltage application method in which a high voltage of 10 kV or more is normally applied between the material to be welded to cause dielectric breakdown and shift to an arc, and a method in which the torch electrode is brought into contact with the material to be welded without using high frequency to energize. There are three types of touch-start (or lift-start) methods in which arc discharge is generated by pulling apart after starting. The high-frequency generation method and direct current high-voltage application method require a high-voltage power source that generates high-frequency or high-voltage, which makes the cost of the welding machine high. A bad influence on surrounding electronic equipment may be objectionable at the welding site. In this regard, since the touch start method does not use a high frequency power source or a high voltage power source, the cost of the welding machine can be reduced and there is no problem of high frequency noise. The touch start method is a method in which an arc is generated instantly when the torch electrode and the material to be welded separate. Since contact is an essential condition, takt time is required. If the welding current is simply increased to shorten the tact time, there is a possibility that welding will occur between the torch electrode and the material to be welded when an arc is generated.

For this reason, in the conventional touch start method, after the torch electrode is brought into contact with the material to be welded and energization is started, the tip of the torch electrode is pulled away from the material to be welded while the start current or initial current is flowing, and the initial current is applied. At the set separation position, the arc is generated, and the separation distance is increased under the initial current.

More specifically, in the conventional touch start method, the welding power source is turned on while the torch electrode and the material to be welded are in contact with each other, and the initial current for initial energization is applied to the closed circuit including the torch electrode and the material to be welded. flow. At this time, since the torch electrode is in contact with the material to be welded, no arc is generated yet regardless of the magnitude of the initial current. In this case, the initial current is not only during the short-circuit condition when the torch electrode is in contact with the material to be welded, but also after the torch electrode is separated from the material to be welded and an arc is generated. The current is continuously supplied to the arc and the material to be welded until the distance reaches a certain value or more, and is usually set to about 5 to 20 A (amperes).

After the initial energization for touch start is started as described above and the initial current is stabilized, the tip of the torch electrode is moved away from the material to be welded by the set separation distance. This separating operation is carried out by calculating backward from the moving distance during forward movement (downward movement) and moving the rectilinear moving part upward by a predetermined distance (extension amount of downward movement + set separation distance), or by locking means such as a plunger to hold the torch. The body is fixed to the rectilinear movable part, the rectilinear movable part is lifted by a predetermined distance corresponding to the set separation distance, and the torch electrode is stopped at the stop position of the upward movement destination. Normally, the separation operation takes 100 ms (milliseconds) or more, and from the moment the separation operation starts, a weak arc corresponding to the initial current is generated in the gap between the torch electrode and the material to be welded. be.

Thus, the torch electrode is pulled up to the set separation position, and the current flowing through the torch electrode and the material to be welded is switched from the initial current to the main current for main energization. The current amount of the main current is set to be much larger than the current amount of the start current, usually 30 A or more, so as to generate an arc of sufficient power or energy to reliably melt the material to be welded.

In this way, the torch electrode is separated from the material to be welded by a set separation distance, and the material to be welded is exposed to an arc of power or energy corresponding to the main current for main energization under an optimum arc length for a predetermined time. The desired welding quality (joint strength, appearance finish) is obtained.

In addition, the principle of the touch start method is that an arc is generated by separating the tip of the torch electrode and the material to be welded after forming a closed circuit between the tip of the torch electrode and the material to be welded. is intended to be stably formed for use in welding, but in touch-start type welding equipment, generally, the formation and separation of a closed circuit between the tip of the torch electrode and the material to be welded A weak current is applied to the torch electrode itself, and the arc generation is recognized by the change in the voltage value or current value when the torch electrode and the material to be welded are separated (for example, Patent Documents 3 and 4). It is done by

JP 2014-172071 A JP 2015-128787 A JP-A-2000-176641 JP-A-6-55269

In recent years, the miniaturization of electronic components has progressed remarkably, and along with this, even in TIG welding equipment, small materials to be welded with small heat capacity (for example, plate materials with a cross-sectional shape of 3 mm × 1 mm or less, wire rods with a wire diameter of 1 mm or less) are being used. The number of cases to be handled is increasing. Welding quality is usually controlled based on the amount of energy received by the material to be welded by welding with the main current (main energization). However, in a conventional TIG welding apparatus, when the touch-start type arc welding as described above is performed on a very small material to be welded with a small heat capacity, how to adjust or control the initial current of the initial energization and the main current of the main energization. However, due to the influence of the initial current, the material to be welded is undesirably melted excessively and good welding quality cannot be obtained, or the material to be welded itself melts down due to the influence of the initial current immediately after the arc starts. Welding quality could not be properly controlled. In addition, the current of the initial current is If the value is decreased, the phenomenon that the arc does not occur easily occurs. These are real problems.

In the conventional touch start method, the arc formed from the material to be welded toward the tip of the torch electrode crosses the tip (tapered portion) of the torch electrode and climbs up to the upper side surface (columnar body). phenomenon may occur. This phenomenon is considered to be one of the reasons why welding fumes generated from the material to be welded cling around the torch electrode and adhere to the torch electrode, that is, shorten the life of the torch electrode. For this reason, when the creeping phenomenon is conspicuously observed, it is avoided at the welding site because the welding result is more likely to be defective. The present inventors have studied a method for suppressing the phenomenon of the arc creeping up to the body side surface of the torch electrode in touch-start type arc welding.

The present invention has been made in view of the above-mentioned problems of the prior art. To provide a TIG welding method and a TIG welding apparatus capable of stably and reliably performing arc welding without causing a crack, performing appropriate arc welding even on a material to be welded having a particularly small heat capacity, and obtaining excellent welding quality.

The TIG welding method of the present invention comprises a first step of driving a rectilinear movable portion that supports a torch electrode in a downward direction to move the torch electrode downward toward a material to be welded; a second step of stopping the driving of the rectilinear movable portion immediately after contact with the material to be welded; For the initial energization of the closed circuit including the A third step of applying a current, a fourth step of driving the rectilinear movable portion in an upward direction to move the torch electrode upward, and a separation timing at which the tip of the torch electrode separates from the material to be welded. , a fifth step of detecting the timing at which the light receiving element receives or not to receive the light beam emitted from the light emitting element as the torch electrode moves upward; or a sixth step of immediately switching the current flowing through the closed circuit from the first current to a second current for main energization.

A TIG welding apparatus according to the present invention comprises a torch body that detachably mounts and holds a torch electrode, a straight moving part that supports the torch body and is provided so as to be able to move straight in a direction parallel to the axial direction of the torch body, To apply a predetermined current to a closed circuit including the linear driving section that drives the linear movable section to move the torch electrode downward or upward with respect to the material to be welded, and the torch electrode and the material to be welded. When the welding power source and the torch electrode are moved upward from the state where the tip of the torch electrode is in contact with the material to be welded, the tip of the torch electrode is separated from the material to be welded. A separation detection unit that detects the timing at which the light receiving element changes whether or not the light beam emitted by the light emitting element is received and outputs a separation timing detection signal, and a control for controlling the linear driving unit and the welding power source. wherein the control unit turns on the switch of the welding power source, which has been in the OFF state, for initial energization of the closed circuit while the tip of the torch electrode is in contact with the material to be welded. The welding power source is controlled so as to apply a first current with the voltage applied between the torch electrode and the material to be welded set to zero volts, and after a predetermined time has passed from the start of the initial energization. and, upon receiving the separation timing detection signal from the separation detection section , the current flowing through the closed circuit is changed to the second The welding power source is controlled to switch from current No. 1 to current No. 2 for main energization.

In the TIG welding method and the TIG welding apparatus of the present invention , after the initial energization is started by the touch start method and the first current for the initial energization is supplied to the closed circuit including the torch electrode and the material to be welded, the The timing at which the torch electrode is separated from the material to be welded when the part is moved upward is assumed to be the timing of the start of arc welding, and at the same time or immediately after the separation timing is detected, the first current is applied for main energization. After the arc is generated, the material to be welded is exposed to the first current for initial energization as much as possible, and the material to be welded is exposed to the arc by the second current for main energization. can be controlled as follows.

According to the TIG welding method or the TIG welding apparatus of the present invention, with the above configuration and action, TIG welding by the touch start method can be performed stably and reliably, and in particular, a material to be welded with a small heat capacity (for example, a cross-sectional shape of 3 mm × 1 mm) For the following plate materials and wire materials with a wire diameter of 2 mm or less), since the generation of arc due to initial energization is reduced or disabled as much as possible, undesired penetration of the weld material due to arc due to initial energization and to the side of the torch electrode Appropriate arc welding is performed in which the phenomenon of arc creeping is eliminated, and good welding quality can be obtained.

1 is a block diagram showing the overall configuration of a TIG welding device according to one embodiment of the present invention; FIG. FIG. 4 is a partial cross-sectional view showing the configuration of the welding head portion in the TIG welding apparatus and the state of each part at one stage (when the torch is at the standby position) in the TIG welding operation; FIG. 4 is a partial cross-sectional side view showing a state of the TIG welding operation at one stage (immediately before the tip of the torch electrode comes into contact with the material to be welded). FIG. 4 is a partial cross-sectional side view showing the state of each part at one stage (when the tip of the torch electrode is in contact with the material to be welded) in the TIG welding operation; FIG. 4 is a partial cross-sectional side view showing the state of each part at one stage (immediately after the tip of the torch electrode is separated from the material to be welded) in the TIG welding operation; FIG. 4 is a partial cross-sectional side view showing the state of each part in one stage (just before the end) of the TIG welding operation; FIG. 4 is a partial cross-sectional side view showing the state of each part in one stage (immediately after completion) of the TIG welding operation; 4 is a timing chart showing the sequence of each control method in the embodiment; FIG. It is a flowchart figure which shows the control procedure in the 1st control method of embodiment. It is a flowchart figure which shows the control procedure in the 2nd control method of embodiment. It is a flowchart figure which shows the control procedure in the 3rd control method of embodiment. FIG. 5 is a timing chart showing a sequence of a control method of a comparative example; FIG. 4 is a partial perspective view showing an example of a torch electrode; FIG. 10 is a partial cross-sectional front view showing the configuration of a touch/separation detection unit in another embodiment; FIG. 11 is a partial cross-sectional front view showing the configuration of a touch/separation detection section in still another embodiment; FIG. 10 is a diagram showing an arc generation state (with an arc creeping phenomenon) in a control method of a comparative example; FIG. 5 is a diagram showing an arc generation state (no arc creeping phenomenon) in the control method of the embodiment;

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.
[Configuration of entire device and each part]

FIG. 1 shows a block diagram of the overall configuration of a TIG welding apparatus according to one embodiment of the present invention. This TIG welding apparatus is systematically composed of a torch body 12 holding a torch electrode 10, a utility supply system 14 for supplying a required utility to the torch electrode 10 or torch body 12, and a welder directly below the torch body 12. A positioning mechanism 16 for positioning the material W, a linear movement mechanism 18 for linearly moving the torch electrode 10 or the torch body 12 in its axial direction (generally in the vertical or vertical direction), and a torch electrode in the touch start method. 10 touches the material to be welded W and the timing when the torch electrode 10 is separated from the material to be welded W; and a control unit 20 for controlling the rectilinear movement mechanism 18).

The torch body 12 is configured as a cylindrical body made of a conductor such as copper or brass or an insulating material such as resin. The torch electrode 10 is held by protruding the tip of the torch electrode 10 .

The utility supply system 14 includes a welding power supply 22 that supplies a current for generating an arc AC between the torch electrode 10 and the material W to be welded, and a shielding gas or an assist gas near the material W to be welded during generation of the arc AC. and a gas supply unit 24 for supplying gas.

The welding power source 22 comprises a direct current constant current source, preferably an inverter controlled constant current source with high speed current switching capability. The positive output terminal (+) of the welding power source 22 is electrically connected to the material to be welded W on the stage 28 via an electric cable 26 and a contact 27, and the negative output terminal (-) is connected via an electric cable 30. is electrically connected to the torch electrode 10 in the torch body 12 at the bottom. When the torch electrode 10 and the material W to be welded are in physical contact, or when arc discharge is occurring between the torch electrode 10 and the material W to be welded, the welding power source 22, the torch electrode 10 and the material W are A closed circuit is formed between the welding materials W.

The gas supply unit 24 is configured to supply shield gas or assist gas such as nitrogen gas or oxygen gas to the torch body 12 at a constant flow rate through a gas pipe 33 such as a flexible hose. The shielding gas supplied to the torch body 12 is jetted from the torch nozzle 12a of the torch body 12 toward the workpiece W to be welded.

The alignment mechanism 16 is provided inside or around a stage 28 on which the material to be welded W is placed, and moves the stage 28 in four axial directions: horizontal (X direction, Y direction), vertical direction, and rotational direction. It has a stage moving mechanism (not shown) capable of Further, the positioning mechanism 16 or the stage 28 includes fixing means for fixing the material W to be welded on the stage 28 mechanically or by a vacuum suction force, and a clamp electrode (not shown) when clamping the material W to be welded. It is also possible to provide a compliance device or the like for sliding the material W to be welded on the stage 28 following the clamping operation of (1).

The rectilinear movement mechanism 18 includes a rectilinear movable part 32 as a welding head which supports the torch body 12 and is capable of vertical movement (straight movement) in a direction (vertical direction) parallel to the axial direction of the torch body. On the other hand, it includes a rectilinear drive section 34 for linearly driving the rectilinear movable section 32 in the same direction to move the torch electrode 10 downward (forward) or upward (backward). Although not shown, the rectilinear drive unit 34 includes a drive source such as an electric motor, a motion conversion mechanism that converts the rotary drive force of the electric motor into a drive force for linear up-and-down movement, and a linear driving force for up-and-down movement. and a transmission mechanism for transmitting to the movable portion 32 .

The touch/separation detection unit 15 is preferably mounted on the rectilinear driving unit 34 as described later, and is located at a location separated (or isolated) from the tip of the torch electrode 10, and is located in a position separate from the torch electrode 10 in the touch start method. It is configured to detect the timing of touch and separation from the material W to be welded. A specific configuration and operation of the touch/separation detection unit 15 will be described later in detail.

FIG. 2A shows the configuration of the rectilinear movable section 32 in this embodiment. The rectilinear movable portion 32 has a rigid plate or base member 40 made of resin or metal and having an L-shaped cross section. ) through a connecting member 42 .

On the base member 40, on the front surface of the vertical flat plate portion 40a (the surface facing the torch body 12), a substantially rectangular parallelepiped multipurpose support portion 44 made of an insulating material such as resin is fixed. On the upper surface of the multipurpose support 44, a utility relay 46 having a hollow block structure made of a conductor such as copper is attached. A pair of left and right balance arms 50 are attached to both side surfaces of the multipurpose support portion 44 via a fulcrum shaft 48 so as to be rotatable in a vertical plane. The configuration around the utility relay portion 46 and the balance arm 50 will be described later in detail.

On the base member 40, a cylindrical torch guide 52 for guiding the torch body 12 in the vertical direction is provided at the tip of the horizontal flat plate portion 40b (the end opposite to the vertical flat plate portion 40a). there is Inside the torch guide 52, two linear bushes 54H and 54L are provided with a certain space or an intermediate portion interposed therebetween in the vertical direction. The torch body 12 can be accurately moved straight in the vertical direction by the guidance of both linear bushes 54H and 54L.

An opening 56 is formed in the middle of the torch guide 52 at a position facing the multipurpose support 44 . On the side surface of the intermediate portion of the torch body 12, a utility force introducing portion 58 having a hollow block structure made of a conductor such as copper is attached so as to be exposed to the outside through an opening 56. As shown in FIG. The utility force introducing portion 58 is electrically connected to the torch electrode 10 via a conductive path inside the torch body 12 .

A pair of upstream gas introduction ports 60 are provided on the upper surface of the utility introduction portion 58 . Further, a downstream side gas introduction port (not shown) connected to the gas flow path in the torch body 12 is provided on the rear surface of the utility introduction portion 58 (the surface facing the torch body 12). The interior of the utility introduction part 58 is a hollow gas chamber or gas passage, and the upstream gas introduction port 60 and the downstream gas introduction port communicate with each other.

On the other hand, the utility relay portion 46 on the multipurpose support portion 44 is provided with a pair of downstream side gas relay ports 62 on both side surfaces thereof. Between the downstream gas relay port 62 and the upstream gas introduction port 60 of the power introduction portion 58, a displaceable or deformable resin-made bridging tube 64 extending in an arch shape in the air is provided. Furthermore, a displaceable or deformable belt-shaped sheet bridge-type conductor 66 extending in an arch shape in the air is hung between the facing surfaces (front surfaces) of the utility relay portion 46 and the utility force introduction portion 58 . The band-shaped sheet bridging conductor 66 is formed by laminating a plurality of (for example, nine) extremely thin copper sheets having a thickness of 0.05 mm, for example.

A conductive upstream gas relay port 68 is provided on the upper surface of the utility relay portion 46 . A terminating connector 72 of a utility supply cable 70 accommodating an electric cable 30 from the welding power source 22 (FIG. 1) and a gas pipe 33 from the gas supply section 24 (FIG. 1) can be detachably attached to the upstream gas relay port 68. Connected. In this case, not only is the gas supply line (gas pipe) 33 in the utility supply cable 70 connected to the gas passage of the upstream gas relay port 68, but also the welding current supply line (electrical cable) 30 in the utility supply cable 70 is connected. is electrically connected to the main body of the utility relay portion 46 . The utility relay portion 46 has a hollow gas chamber or gas passage inside, and the upstream gas relay port 68 and the downstream gas relay port 62 communicate with each other.

The utility power supply cable 70 is a relatively heavy cable, but because it terminates at the utility power relay portion 46 as described above, the weight of the utility power supply cable 70 is applied to the base member 40 and does not affect the torch 13, which is the combination of the torch electrode 10 and the torch body 12. It doesn't take. Torch 13 bears the weight of bridging tube 64 and bridging conductor 66 . The bridging tube 64 and the bridging conductor 66 are much lighter than the utility supply cable 70, and their postures in the air are arch-shaped and constant, so that the torch load hardly varies.

In the utility supply system around the utility relay section 46 on the multipurpose support section 44 and the utility introduction section 58 on the torch body 12 side as described above, the shielding gas delivered from the gas supply section 24 (FIG. 1) Cable 70 (gas pipe 33)→utility relay portion 46 (upstream gas relay port 68→downstream gas relay port 62)→bridge type tube 64→utility introduction portion 58 (upstream gas introduction port 60→downstream gas introduction port )→torch body 12→torch nozzle 12a. Welding current sent out from the welding power source 22 is divided into the following order: utility supply cable 70 (electric cable 30) → utility relay portion 46 (conductive block) → bridging type conductor 66 → utility introduction portion 58 (conductive block) → torch body 12→The current path connected to the torch electrode 10 is designed to flow in the above order or in the reverse order (reverse direction).

The balance arm 50 is made of a rigid body such as stainless steel, has a bent portion 50a, a first arm portion 50b and a second arm portion 50c, and is formed in a "F" shape as a whole. The flexure 50a is rotatably mounted to the front of each side of the multi-use support 44 by a fulcrum shaft 48. As shown in FIG. A laterally elongated bearing 76 is provided at the tip of the first arm portion 50b to fit a pin 74 fixed to the side surface of the torch body 12 . The side surface of the torch guide 52 is formed with a vertically long opening (not shown) for passing a vertically movable pin 74 .

On the other hand, a rectangular parallelepiped balance weight 80 made of stainless steel, for example, is attached by a bolt 82 to the tip of the second arm portion 50c. In order to adjust the weight of the balance weight 80 , for example, a plate-shaped weight addition weight 84 may be detachably attached to the balance weight 80 with a bolt 86 . The horizontal flat plate portion 40b of the base member 40 is formed with an opening 88 large enough for the balance weight 80 to pass through.

In the balance arm 50, a counterclockwise weight moment in FIG. A clockwise weight moment in FIG. 2A acts due to the weight of the balance weight 80 attached to the tip.

Here, the weight of the balance weight 80 is set or adjusted so that the weight moment on the torch side slightly exceeds the weight moment on the balance weight 80 side (for example, 10 to 30 g weight in terms of torch load). By setting the moment of weight on the torch side to be larger than the moment of weight on the balance weight 80 side in this way, when no external force is applied to the torch 13, the upper surface of the balance weight 80 is positioned at the multipurpose support portion 44 as shown in FIG. 2A. abuts on the lower surface (stopper) of the In this state, the balance arm 50 remains stationary and the torch 13 is held at a constant (reference) height position above the welding head.

The pin 74 of the torch 13 and the bearing 76 of the first arm portion 50b fitted thereto are a crank mechanism for converting between the vertical straight movement of the torch 13 and the rotational movement of the balance arm 50. constitutes

Multi-use support 44 is constructed as a hollow housing or block in which is fixedly mounted an electromagnetic solenoid, such as plunger solenoid 90, which faces utility lead-in 58 of torch 13 through an opening (not shown). ing. When the plunger 92 of the plunger solenoid 90 moves forward, the tip of the plunger solenoid 90 abuts against the side surface (facing surface) of the utility force introduction portion 58 with a large pressing force, and the plunger solenoid 90 and the utility force introduction portion 58 are physically integrated (combined). ), and thus the torch 13 and the base member 40 are physically integrated (bonded). In this integrated state, when the rectilinear driving section 34 vertically moves the rectilinear movable section 32 , the torch body 12 also moves vertically together with the rectilinear movable section 32 .

As described above, in the TIG welding apparatus of this embodiment, the balance arm 50 is rotatably attached in the vertical plane to the rectilinear movable portion 32 that constitutes the welding head via the fulcrum shaft 48. The torch body 12 is coupled to the tip of the first arm portion 50b, and the balance weight 80 is attached to the tip of the second arm portion 50c. The torch load can be reduced to a very small load (for example, 30 gf or less) simply by adjusting .

Further, in this TIG welding apparatus, on the rectilinear movable part (welding head) 32, a sensor for detecting the timing of touch and the timing of separation between the tip of the torch electrode 10 and the material to be welded W in the touch start method. A touch/separation detection unit 15 is provided. As shown in FIG. 2A, the touch/separation detection unit 15 is composed of a plate-like light shielding member F integrally attached to an appropriate portion (for example, the lower end) of the balance arm 50 and has a light-emitting element ED and a light-receiving element PD arranged at the same height position facing each other. The light-emitting element ED and the light-receiving element PD cooperate to form an optical sensor. The light-emitting element ED emits a light beam P toward the light-receiving element PD. For example, H level/L level binary signals having different values are output. The height positions of the light emitting element ED and the light receiving element PD are configured to be adjustable.

The touch/separation detection unit 15 (FIG. 1) has a circuit for processing the output signal of the light receiving element PD, and when the output signal of the light receiving element PD changes from H level to L level, the tip of the torch electrode 10 is A touch timing detection signal _MSA indicating the timing of touching the material W to be welded is output, and the tip of the torch electrode 10 is separated from the material W to be welded when the output signal of the light receiving element PD changes from the L level to the H level. A separation timing detection signal _MSB indicating the timing is output.

In this embodiment, a linear scale 101 as shown in FIG. 2A, for example, is provided as a position sensor for measuring the relative height position and vertical movement distance of the rectilinear movable portion 32 or torch 13 with respect to the stage 28. . The linear scale 101 has a vertically extending scale portion 103 fixed to the stage 28, and a scale reading portion 105 attached to the base member 40 for optically reading the scale of the scale portion 103. there is An output signal from the scale reading section 105 is given to the control section 20 .

Furthermore, this TIG welding apparatus is provided with a voltage detection circuit 38 (FIG. 1) for detecting the voltage V (especially the rising edge) between the torch electrode 10 and the material W to be welded. This voltage detection circuit 38 detects the rising edge of the voltage V generated in the gap between the torch electrode 10 and the material to be welded W when the torch electrode 10 is separated from the material to be welded W during touch start energization, and detects the timing of the rising edge (separation timing). ) to the control unit 20 . The voltage detection circuit 38 preferably includes a differentiating circuit in order to detect the rising edge of the voltage V accurately and quickly.

In FIG. 1, the control unit 20 includes a microcomputer, memory, various interfaces, etc., and also has an internal or external analog or digital timer. It is also connected to an input device, a display device, etc., and controls the operation of each part in the device and the overall sequence according to a predetermined program accumulated or stored in the memory.
[Operation and action of the entire device]

2A to 2F, 3, and 4A to 4C, the operation of the TIG welding apparatus and TIG welding method in this embodiment will be described below.

2A to 2F show states of parts in the welding head at each stage of the TIG welding operation according to the embodiment (first control scheme). FIG. 3 shows the sequence of TIG welding operations according to each control method of this embodiment. 4A to 4C show control procedures of the control section 20 in each control method.

In FIGS. 2A to 2F, the material to be welded W shown as an example is obtained by winding a thin covered wire 104 around a strip-shaped terminal member 102 projecting from a work body 100 such as a small precision electronic component package, and then winding the wound portion. It is the part to be welded. In terms of dimensions, for example, the terminal member 102 has a width of approximately 1 mm and a thickness of approximately 0.2 mm, and the coated wire 104 has a thickness of approximately 0.05 mm. A contactor 27 detachably mounted near the base of the terminal member 102 is connected to the positive terminal (+) of the welding power source 22 via an electric cable 26 .

According to the first control method (FIGS. 3 and 4A) of this embodiment, when the control unit 20 receives the activation signal at time _t0 in FIG. Set values for various conditions used in the current TIG welding are read out from the memory and set in predetermined registers. These conditions include the current values of the initial current _I0 and the main current _IM , the initial energization time _T0 and the main energization time _TM .

Next, the control unit 20 controls the rectilinear drive unit 34 to cause the rectilinear movable unit 32, which has been stationary at the standby position until then, to start downward movement (step _S102 ). In this case, in the initial state, the balance arm 50 is stationary on the rectilinear movable portion 32 as shown in FIG. are evacuating. As a result, the light beam P from the light emitting element ED passes under the light shielding member F so as to graze and enters the light receiving element PD, and the output signal of the light receiving element PD is at the H level. As shown in FIG. 2B , the state of each part on the rectilinear movable part 32 is maintained until just before the tip of the torch electrode 10 touches the material W to be welded.

On the other hand, under the control of the control unit 20, the welding power source 22 keeps the output switch SW in the OFF state. The gas supply unit 24 starts supplying the shield gas while the rectilinear movable unit 32 and the torch 13 are being lowered. As described above, the shielding gas sent from the gas supply section 24 to the welding head (straight movable section) 32 via the utility supply cable 70 (gas pipe 33) is transferred from the utility relay section 46 to the bridge tube 64 to the utility. The gas is injected toward the workpiece W from the injection port of the torch nozzle 12a through each gas flow path of the introduction portion 58→torch body 12→torch nozzle 12a.

Then, as shown in FIG. 2C, when the tip of the torch electrode 10 abuts (touches) the material W to be welded, the torch electrode 10 receives a reaction from the material W to be welded, causing the balance arm 50 to move clockwise in the figure. , the light blocking member F enters the optical path of the light beam P and blocks the light beam P from the light emitting element ED. Then, the output signal of the light receiving element PD changes from H level to L level, _{and the touch/separation detection unit 15 (FIG. 1) generates the touch timing detection signal MSA .} The part 20 recognizes or detects the timing (time t ₁ in FIG. 3) when the tip of the torch electrode 10 touches the workpiece W (step S ₁₀₃ ).

When the touch timing (time point t ₁ ) is detected as described above, the control unit 20 controls the rectilinear drive unit 34 to immediately stop the downward movement of the rectilinear movable unit 32 (step S ₁₀₄ ). Next, the switch SW of the welding power source 22 is switched from the off state to the on state to cause the welding power source 22 to output a predetermined initial current _I0 for initial energization (step _S105 ). In this initial energization, the positive electrode output terminal of the DC voltage source E of the welding power source 22→the electric cable 26→the material to be welded W→the torch electrode 10→the torch body 12→the power introduction portion 58→the bridging conductor 66→the power relay portion 46→ In the current path (closed circuit) from utility cable 77 (electric cable 30) to the negative output terminal of DC voltage source E, an initial DC current _I0 flows.

The set current value of the initial current _I0 is an arbitrary value, and when the workpiece W to be welded is a minute work with a small heat capacity as in this embodiment, the current amount of the initial current _I0 is set to be considerably small. be. Since the torch electrode 10 and the material to be welded W are electrically short-circuited as long as they are in the touch state, the voltage V applied between them is zero volt even if the initial current _I0 flows.

The touch start method in this embodiment aims to eliminate undesired penetration of the material to be welded by the initial current _I0 , and the set value of the initial current _I0 is set to a value smaller than usual. . The set value may be any value that allows a weak arc to rise between the torch electrode and the material to be welded, and is usually set to about 5A. The initial current _I0 of 5 A is a small value for a general touch start method, but if the material to be welded is minute, for example, the wire diameter is 1 mm or less, the weak initial current at the time of arc start will not affect the material to be welded. If the effect of penetration is considered to be large, the initial current _I0 may be set to a smaller value, for example 2A. On the other hand, the initial current _I0 may be set to a lower value, but if it is set to, for example, about 1 A, the initial current _I0 will be too small even if the material to be welded is very small. In many cases, a strong arc does not occur stably. Therefore, the initial current _I0 is preferably set to 1.5A or more, preferably 2A or more.

In this first control method, even with such a small initial current _I0 , it is possible to avoid undesirably excessive melting of the material to be welded W due to the influence of the initial current _I0 when the arc rises. Then, the arc can be controlled by the instantaneously switched main current _IM .

When the timer counts the set time _T0 for the initial energization and times up (step _S106 ), the control section 20 starts upward movement of the linear movable section 32 via the linear driving section 34 while maintaining the energized state. (Step S ₁₀₇ ). When the rectilinear movable part 32 starts to move upward, the torch 13 also starts to move upward, and the tip of the torch electrode 10 separates from the workpiece W to be welded. Then, as shown in FIG. 2D, the torch electrode 10 is no longer subject to reaction from the workpiece W side, the balance arm 50 rotates in the direction to return to the initial state, that is, counterclockwise in the drawing, and the light shielding member F It retreats upward from the optical path of the light beam P, and the light beam P from the light emitting element ED reaches the light receiving element PD. Then, the output signal of the light receiving element PD changes from L level _to H level, and the touch/separation detection unit 15 (FIG. 1) generates the separation timing detection signal _MSB . 20 recognizes or detects the timing (time t ₂ in FIG. 3) when the tip of the torch electrode 10 is separated from the material to be welded W (step S ₁₀₈ ).

At the same time or immediately after detecting the separation timing (time point t ₂ ), the control unit 20 controls the welding power source 22 to change the current flowing through the closed circuit from the initial current _I0 until then to the main energization. (step S _{109 )} . In this main energization, the main current I _M is supplied to the arc AC and the material to be welded W at a preset current value for a preset time (T _M ). In this case, as soon as the tip of the torch electrode 10 is separated from the material to be welded W in an energized state, an arc AC is immediately generated in the gap formed between the two, and this arc AC becomes a conductive path and part of the closed circuit. Form.

The current value of the main current I _M and the main energization time (T _M ) are set depending on the heat capacity of the material W to be welded and the like. As in this embodiment, for a minute workpiece W having a small heat capacity, the current value of the main current IM is set to a value (eg, ₁₀ A) much larger than the current amount (eg, 5 A) of the initial current I0. set. Further, the main energization time _TM is set to several 10 ms, for example.

In this embodiment, the initial current _I0 is switched to the main current _IM at the same time or immediately after the separation timing (time _t2 ) is detected as described above (steps _S108 → _S109 ). , a slight delay (for example, 5 ms) may occur in switching depending on the response speed of hardware such as the welding power source 22 . However, this kind of delay does not particularly affect the operation of TIG welding and can be made as close to zero as possible through hardware improvements. It is very important not to introduce software or intentional delays.

As soon as the tip of the torch electrode 10 is separated from the material to be welded W in this manner, an arc AC is generated by the main current _IM for main energization in the gap formed between the two, and while the torch electrode 10 is moving upward, The material W to be welded is exposed to the arc AC of power or energy corresponding to the current amount of the main current _IM , and is melted as expected. In this case, the arc length changes as the torch electrode 10 moves upward, that is, as the _separation distance increases. , less impact on welding quality.

When the main energization time T _M expires (step S ₁₁₀ ), the control unit 20 turns off the welding power source 22 to stop the energization (step S ₁₁₁ ). When the main current _IM is cut off, the arc AC is extinguished at that moment. When the arc AC is extinguished, the melted portion of the material to be welded W immediately solidifies due to natural cooling in the atmosphere.

After that, the control unit 20 turns off the gas supply unit 24, and when the rectilinear movable unit 32 reaches a predetermined position (for example, the initial position), the control unit 20 controls the rectilinear drive unit 34 to stop the upward movement of the rectilinear movable unit 32. (Step _S112 ).

As described above, in the first control method, after the initial energization is started by the touch start method, the tip of the torch electrode 10 is separated from the material W to be welded when the straight movable portion 32 is moved upward. At the same time (time t ₂ ), the initial energization is switched to the main energization, and the arc welding is finished when a preset main energization time T _M has elapsed from the separation timing (t ₂ ). With such a technique, it is possible to perform appropriate arc welding even on the material to be welded W, which is easily melted by a weak arc having a small heat capacity, and obtain good welding quality. In addition, it is possible to effectively prevent welding defects such as arc crawling, arc side jumping (a phenomenon in which an arc sparks to another work in the vicinity), and arc misfire.

Regarding this point, in the general touch start method, after the torch electrode touches the material to be welded, (A1) initial energization is started in a state in which the torch electrode is in contact with the material to be welded (short-circuited state) → (A2 (A3) The torch electrode separates from the material to be welded. (A4) A weak arc is generated. (A5) The torch is moved upward while maintaining the initial energization and the weak arc. It consists of a series of steps (A1) to (A7) of continuing→(A6) establishing a constant separation→(A7) switching the initial current to the main current for main energization. The first control method described above has a unique control concept in that it skips steps (A4) to (A6) from step (A3) and shifts to step (A7). can be said to be a different special touch start method.

Under the touch state, the plunger solenoid 90 is operated in the rectilinear movable portion 32 to integrate the torch body 12 with the base member 40 of the rectilinear movable portion 32, and after the touch start, the torch electrode 10 is integrated with the rectilinear movable portion 32. It is also possible to move upward. However, if the plunger 92 of the plunger solenoid 90 hits the side surface (opposing surface) of the utility force introduction portion 58 with a large pressing force under the touch state, an unnecessary amount of pressure is applied to the workpiece W through the torch body 12, the torch electrode 10, and the like. The pressure is applied, and there is a risk of undesirably damaging or deforming the minute welded material W having a small heat capacity. Furthermore, it is also difficult to accurately detect the timing (t ₂ ) at which the tip of the torch electrode 10 separates from the material to be welded W when the rectilinear movable portion 32 is moved upward.

In this embodiment, as described above, the touch/separation detection unit 15 optically monitors the relative movement or positional relationship of the torch 13 with respect to the rectilinear movable unit 32 via the balance arm 50, and the balance arm 50 The timing (t 1 ) when the light shielding member F enters the optical path of the light beam P of the optical sensor (ED/PD) after starting to move clockwise from the stationary state is detected as the touch timing (t ₁ ), and the balance arm 50 moves counterclockwise from the stationary state. The timing (t 2 ) when the light shielding member F starts to move in the direction and exits the optical path of the light beam P of the optical sensor (ED/PD) is detected as the separation timing (t ₂ ). That is, the relative positional relationship of the torch 13 with respect to the rectilinear movable part 32 is set so as to match when the touch timing (t ₁ ) is detected and when the separation timing (t ₂ ) is detected. there is The touch/separation detection unit 15 is provided at a location sufficiently distant (or isolated) from the tip of the torch electrode 10, and operates without receiving any heat from the arc AC, so precise timing detection is performed accurately. be able to.

In this embodiment, the control section 20 can also detect the separation timing (t ₂ ) via the voltage detection circuit 38 . When the torch electrode 10 is separated from the material to be welded W during touch start energization, a gap is generated between the two, and the applied voltage V between them changes from zero volts until then to a peak corresponding to the output of the welding power source 22. Rise at a constant or variable rate to a value. Therefore, according to the method of detecting the point in time when the voltage V rises to a certain reference value, the timing considerably delayed from the actual separation timing (t ₂ ) is detected. In this embodiment, the voltage detection circuit 38 has a differentiating circuit, and by differentiating the rising change of the voltage V, the actual separation timing (t ₂ ) can be detected without delay.

The second control method (FIGS. 3 and 4B) follows the basic control concept of the above-described first control method (steps S ₂₀₁ to S ₂₁₂ ), and moves the straight movable portion 32 to the set distance after the touch start. The tip of the torch electrode 10 is moved upward by H _S (step S ₂₁₀ ), that is, moved upward to a position where the tip of the torch electrode 10 is separated from the material to be welded W by the set separation distance H _S and is temporarily stopped (time t ₃ in FIG. 3). , the main energization time T _M is increased during the stop period (steps S ₂₁₃ to S ₂₁₄ ). This second control method can be suitably applied to TIG welding of materials to be welded having a large heat capacity.

The third control method (FIGS. 3 and 4C) also follows the basic control concept of the first control method (steps S ₃₀₁ to S ₃₀₄ , S ₃₀₈ to S ₃₁₃ ), while the initial energization is performed by touch. Start after a certain period of time TF has passed from the timing (t ₁ ) and limit it to just before the separation timing (t ₂ ) (step S ₃₀₅ ), and set the initial energization time (TO) as short as possible ( It is characterized by steps S ₃₀₆ to S ₃₀₇ ). In this case, the slope of the rise of the initial current _I0 and the slope of the rise of the main current _IM for main energization are made continuous, and the energization current can be raised from 0 amperes to the peak value of the main current _IM in the shortest possible time. . In this case, up-slope control may be applied to the rise of the main current _IM , and down-slope control may be preferably used to fall. This second control method can be suitably applied to TIG welding of materials to be welded having extremely small heat capacities.

FIG. 5 shows a sequence of a comparative example corresponding to the conventional control method. As shown in the figure, the control method of the comparative example is a short time after the tip of the torch electrode is separated from the material to be welded in the touch start method. The energization time (main energization time) is managed in a state in which the energization current is switched from the initial current to the main current for the main energization, and the torch electrode is kept stationary at the set separation position. However, according to such a control method, when the heat capacity of the material to be welded is small, the material to be welded W is undesirably and indefinitely melted by the arc of the initial current before the current is shifted to the main current. However, the desired welding quality cannot be obtained.

Furthermore, as shown in FIGS. 9A and 9B, there is a significant operational difference between this embodiment and the comparative example regarding the presence or absence of the arc crawling phenomenon. According to the control method of the comparative example, as shown in FIG. 9A, when the tip of the torch electrode separates from the material to be welded, an arc generated by the initial current is formed toward the tip of the torch electrode from the material to be welded. tends to creep up to the side surface of the columnar body of the torch electrode. Such an arc crawl-up phenomenon greatly reduces the concentration and stability of the arc on the material to be welded. On the other hand, according to this embodiment (for example, the first control method), since the arc is generated under the main current of main energization from the beginning, as shown in FIG. A highly concentrated arc is stably generated between the tip of the torch electrode and the end of the material to be welded.
[Other embodiments or modifications]

Although the preferred embodiments of the present invention have been described above, the above-described embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and changes to the specific embodiments without departing from the spirit and scope of the present invention.

For example, a torch electrode ₁₀ having a minus (-) shape or _a rectangular tip surface as shown in FIG. A torch electrode having a flat tip surface as shown in 6(b) can be preferably used. In these cases, even if the central axis of the torch electrode 10 is slightly shifted laterally from the center of the material W to be welded, the tip surface of the torch electrode 10 contacts the top surface of the material W to be welded. The arc can be concentrated near the center of W( _W1 , _W2 ). In addition, in the touch start method, by switching the current to main energization at the same time as or immediately after the separation timing is detected, the arc creeping up to the side of the torch electrode is prevented, and the workpiece W (W ₁ , W ₂ ) can be concentrated.

FIG. 7 shows another example of the load balance mechanism and the touch/separation detection section 15 provided on the straight moving section (welding head) 32 in the above-described embodiment. In the drawings, the same reference numerals are used for parts having the same configuration or function as those in FIGS. 2A to 2F. A welding current supply system and a gas supply system are omitted from the drawing.

The load balance mechanism in this embodiment arranges a compression coil spring 114 and an extension coil spring 116 in parallel between the main body 110 of the rectilinear moving part 32 and a horizontal connecting rod 112 fixed to the torch body 12 . Here, the spring load of the compression coil spring 114 is adjustable by a first torch load adjuster 122 including a bar screw 118 and a nut 120, and the spring load of the extension coil spring 116 includes a bar screw 124 and a nut 126. It can be adjusted by the second torch load adjuster 128 .

A downward load in the Z direction is applied to the torch body 12, which is the sum of the weight (self weight) _L13 of the entire torch 13 including attachments such as the connecting rod 112 and the spring load _L114 of the compression coil spring 114. On the other hand, the spring load L ₁₁₆ of the extension coil spring 116 is applied upward in the Z direction. If the downward load in the Z direction is positive and the total combined load on the torch body 12 is TL, then TL=L ₁₃ +L ₁₁₄ −L ₁₁₆ . Here, since _L13 is substantially constant, by variably adjusting _L114 and _L116 with the first and second torch load adjusting units 122 and 128 as described above, , the total combined load TL can be arbitrarily adjusted.

The touch/separation detection unit 15 in this embodiment is provided between the main body 110 and a horizontal bar 130 extending horizontally on the side opposite to the connecting bar 112 (on the left side in the drawing). More specifically, a light blocking member F extending vertically upward is attached to the tip of the horizontal bar 130 . Around the light shielding member F, a light emitting element ED and a light receiving element PD fixed to the main body 110 are arranged facing each other at the same height position.

In such a configuration, when the tip of the torch electrode 10 touches the material to be welded (not shown), the reaction from the material to be welded causes the torch 13 (the torch electrode 10 and the torch body 12) to move toward the main body of the rectilinear movable part 32. 7, the light blocking member F blocks the light beam P from the light emitting element ED, and the output signal of the light receiving element PD changes from the H level to the L level. turns into After that, when the tip of the torch electrode 10 is separated from the material to be welded, the reaction from the material to be welded is released, so that the torch 13 moves downward relative to the main body 110 of the rectilinear movable part 32. , the light blocking member F retreats downward from the optical path of the light beam P, and the output signal of the light receiving element PD changes from the L level up to that point to the H level.

In this manner, the touch/separation detection unit 15 in this embodiment detects relative motion between the main body 110 of the rectilinear movable unit 32 and the torch 13 coupled thereto via the compression coil spring 114 and the extension coil spring 116 . These movements or positional relationships are optically monitored to detect touch timing and separation timing in the touch start method.

In addition, in the touch/separation detection unit 15, a configuration is also possible in which an optical sensor for detecting touch timing and an optical sensor for detecting separation timing are separately provided.

FIG. 8 shows still another embodiment of the touch/separation detection unit 15 . In this embodiment, the light shielding member F of the touch/separation detection unit 15 is placed via an arm-shaped support member 140 in the above-described embodiment (FIGS. 2A to 2F) using the balance arm 50 and the balance weight 80 for the load balance mechanism. An optical sensor (light-emitting element ED/light-receiving element PD) is arranged on the base member 40 (horizontal plate portion 40b) immediately below the light-shielding member F. As shown in FIG.

In this case, in the touch start, until the tip of the torch electrode 10 descends and abuts on the material to be welded W, the tip of the light shielding member F is exposed from the light beam P horizontally propagating between the light emitting element ED and the light receiving element PD. It is at a high position, and the output signal of the light receiving element PD is at H level. When the tip of the torch electrode 10 comes into contact with the material to be welded W, the light beam P is blocked or blocked by the tip of the light shielding member F at substantially the same time, and the output signal of the light receiving element PD changes from H level to L level. . After that, when the initial energization is completed and the tip of the torch electrode 10 is separated from the material to be welded by the upward movement of the rectilinearly movable part 32, substantially simultaneously with this, the tip of the light shielding member F retreats upward from the optical path of the light beam P and receives the light. The output signal of element PD changes from L level to H level.

Although not shown, two sets of optical sensors (ED ₁ /PD ₁ ) and (ED ₂ /PD ₂ ) are arranged at different height positions, and the first optical sensor whose arrangement (detection) position is higher (ED ₁ /PD ₁ ) detects the timing of touch and separation, and the second optical sensor (ED ₂ /PD ₂ ) having a lower arrangement (detection) position acquires the timing of initial energization start. is also possible. This method is suitable for initial energization by lowering the torch body 12 further after the tip of the torch electrode 10 contacts the material W to be welded and applying a sufficiently large pressure to the material W to be welded.

REFERENCE SIGNS LIST 10 torch electrode 12 torch body 15 touch/separation detection unit 20 control unit 22 welding power source 18 rectilinear movement mechanism 32 rectilinear movable unit 34 rectilinear drive unit 38 voltage detection circuit W material to be welded

Claims (10)

a first step of moving the torch electrode downward toward the material to be welded by driving the rectilinear movable portion supporting the torch electrode in the downward direction;
a second step of stopping the driving of the rectilinear movable portion immediately after the tip of the torch electrode contacts the material to be welded;
In a state where the tip of the torch electrode is in contact with the material to be welded, the switch of the welding power source in the off state is switched to the on state for initial energization of the closed circuit including the torch electrode and the material to be welded. a third step of applying a first current with the voltage applied between the torch electrode and the material to be welded set to zero volts;
a fourth step of driving the rectilinear movable portion in an upward direction to move the torch electrode upward;
As the separation timing for the tip of the torch electrode to separate from the material to be welded, the timing at which whether or not the light receiving element receives the light beam emitted by the light emitting element changes as the torch electrode moves upward is detected. a fifth step;
a sixth step of switching the current flowing through the closed circuit from the first current to a second current for main energization simultaneously with or immediately upon detecting the separation timing;
A TIG welding method having 2. The TIG welding method according to claim 1, wherein the energization time for passing said second current ends during said fourth step. a seventh step of stopping the driving of the rectilinear drive portion that drives the rectilinear movable portion at a set separation position where the tip of the torch electrode is separated from the workpiece by a set separation distance in the fourth step;
an eighth step of temporarily resting the torch electrode at the set spaced position;
further having
The TIG welding method according to claim 1, wherein the energization time for passing the second current ends during the eighth step. 2. The TIG welding method according to claim 1, wherein said third step is started immediately before starting the fourth step. The TIG welding method according to claim 4, wherein the rising slope of the first current and the rising slope of the second current are continuous. a torch body that detachably attaches and holds a torch electrode;
a rectilinear movable part that supports the torch body and is provided so as to be rectilinearly movable in a direction parallel to the axial direction thereof;
a rectilinear drive section for driving the rectilinear movable section to move the torch electrode downward or upward with respect to the material to be welded;
a welding power source for applying a predetermined current to a closed circuit including the torch electrode and the material to be welded;
When the tip of the torch electrode is moved upward from the state in which the tip of the torch electrode is in contact with the material to be welded, the light emitting element emits light at the separation timing when the tip of the torch electrode separates from the material to be welded. a separation detection unit that detects the timing at which the light receiving element changes whether or not the light beam is received, and outputs a separation timing detection signal;
a control unit for controlling the rectilinear driving unit and the welding power source;
with
The control unit
In a state where the tip of the torch electrode is in contact with the material to be welded, the switch of the welding power source in the off state is switched to the on state for initial energization of the closed circuit, and the torch electrode and the work to be welded are turned on. controlling the welding power source to apply a first current with the applied voltage between the material and the material being zero volts;
controlling the linear drive unit to start upward movement of the torch electrode after a predetermined time from the start of the initial energization;
When the separation timing detection signal is received from the separation detection section , the welding power source switches the current flowing through the closed circuit from the first current to the second current for main energization at the same time or immediately. control TIG welding equipment. The torch body has a first arm portion having a bearing that engages with a pin provided on the torch body and a second arm portion to which a balance weight is attached without receiving an external force. A balance arm rotatable about a rotation shaft provided between the first arm portion and the second arm portion enables movement in the axial direction while the load is balanced on the rectilinear movable portion . supported by
When the balance arm rotates with the upward movement of the torch body, the separation detection unit detects a state in which the light beam emitted from the light emitting element is blocked by the light shielding member and the light receiving element does not receive the light beam. and a state in which the light beam emitted by the light emitting element is not blocked by the light shielding member and the light beam is received by the light receiving element. Detect when to separate
The TIG welding device according to claim 6. further comprising a touch detection unit that detects touch timing at which the tip of the torch electrode contacts the material to be welded during the downward movement of the torch electrode and generates a touch timing detection signal;
7. The TIG welding device according to claim 6, wherein the control section controls the welding power source so as to start the initial energization immediately or after a predetermined period of time upon receiving the touch timing detection signal from the touch detection section. The torch body has a first arm portion having a bearing that engages with a pin provided on the torch body and a second arm portion to which a balance weight is attached without receiving an external force. A balance arm rotatable about a rotation shaft provided between the first arm portion and the second arm portion enables movement in the axial direction while the load is balanced on the rectilinear movable portion. supported by
The touch detection unit detects a light beam emitted from the light emitting element by rotating the balance arm in accordance with a touch operation in which the torch body descends and the tip of the torch electrode comes into contact with the material to be welded. A state where the light blocking member blocks the light and the light receiving element does not receive the light beam and a state where the light blocking member does not block the light beam emitted by the light emitting element and the light receiving element receives the light beam are changed. Based on the timing, the tip of the torch electrode is detected to touch the material to be welded.
The TIG welding device according to claim 8 . In the touch detection section, the tip of the torch electrode comes into contact with the material to be welded, and a reaction received from the material to be welded raises the torch body and rotates the balance arm. 10. The TIG welding device according to claim 9, wherein the touch timing at which the tip of the torch electrode contacts the material to be welded is detected based on the timing at which the beam is not received and the light beam is received. .

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