WO2018207392A1

WO2018207392A1 - Tig welding method and tig welding device

Info

Publication number: WO2018207392A1
Application number: PCT/JP2017/042888
Authority: WO
Inventors: 正行阿部; 日吉石川
Original assignee: 株式会社アマダミヤチ; 株式会社アマダホールディングス
Priority date: 2017-05-10
Filing date: 2017-11-29
Publication date: 2018-11-15
Also published as: JP2022044837A; JP7245935B2; JPWO2018207392A1; JP7019680B2

Abstract

In this control method, an initial energization is begun with a touch start method and an initial current Io for initial energization is supplied to a circuit while a torch electrode is in contact with the material to be welded, after which the timing (t2) at which the torch electrode is separated from the material being welded while a linear movement unit is moved upward is assumed to be the arc welding start timing, and the current is switched from the initial current Io to a primary current IM for main energization immediately after or simultaneous with the detection of the separation timing.

Description

TIG welding method and TIG welding apparatus

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

Conventionally, a TIG welding method using a non-consumable torch electrode is often used for joining terminal members of small electrical components or joining a terminal member and a conductive wire.

In the TIG welding method using a non-consumable torch electrode, the arc discharge is started by a high-frequency generation method in which dielectric breakdown is caused by high-frequency discharge at the start and the arc is transferred to the arc, and the torch electrode and base material only at the start In other words, a high voltage of 10 kV or higher is normally applied between the welding material and a DC high voltage application method that causes dielectric breakdown and transitions to an arc, and the torch electrode is brought into contact with the welding material without using a high frequency. There are three types of touch start (or lift start) methods in which arc discharge is generated by separating after starting. The high frequency generation method and the DC high voltage application method require a high voltage 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 or The negative impact on surrounding electronic equipment may be disliked at the welding site. In this respect, 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 instantaneously when the torch electrode and the work piece are separated from each other, and there is an advantage that the arc is stably generated. Since contact is an indispensable condition, tact time is required. If the welding current is simply increased to shorten the tact time, there is a possibility that welding occurs between the torch electrode and the material to be welded when an arc occurs.

For this reason, in the touch start method of the prior art, 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 separated from the material to be welded while the start current or the initial current is applied and the initial current An arc is generated below, and the separation distance is increased under the initial current, and control is performed to switch from the initial current to the main energization at the set separation position (Patent Documents 1 and 2).

More specifically, in the conventional touch start method, the welding power source is turned on with the torch electrode and the material to be welded in contact with each other, and the initial current of the initial energization is applied to the closed circuit including the torch electrode and the material to be welded. Shed. 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. The initial current in this case is not only during the short-circuit state in which the torch electrode is in contact with the workpiece, but also after the torch electrode is separated from the workpiece and an arc is generated, the torch electrode is separated from the workpiece. It 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 (ampere).

As described above, after the initial energization of the touch start is started and the initial current is stabilized, the operation of pulling the tip of the torch electrode away from the material to be welded by the set separation distance is performed. This pulling-off operation is performed by calculating backward from the moving distance during forward movement (downward movement), and moving the linearly movable portion upward by a predetermined distance (downward movement extension amount + set separation distance), or by a torch by a locking means comprising a plunger or the like. The body is fixed to the linearly movable part, and the linearly movable part is lifted and moved by a predetermined distance corresponding to the set separation distance, and the torch electrode is stopped at the stop position of the lifted movement destination. Normally, the separation operation takes 100 ms (milliseconds) or more, and a weak arc corresponding to the initial current is generated in the gap between the torch electrode and the material to be welded from the moment when the separation operation is started. The

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

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

The principle of the touch start method is that an arc generated when the tip of the torch electrode and the workpiece are separated after the closed circuit is formed between the tip of the torch electrode and the workpiece. In a touch start type welding apparatus, in general, a closed circuit is formed and separated from the tip portion of the torch electrode and the material to be welded. In the detection of arc, a weak current is applied to the torch electrode itself, and the generation of an arc is recognized by a change in voltage value or current value when the torch electrode and the workpiece are separated (for example, Patent Documents 3 and 4). It is done by.

JP 2014-172071 A JP2015-128787A JP 2000-176661 A JP-A-6-55269

In recent years, downsizing of electronic parts has been remarkably progressed, and accordingly, a TIG welding apparatus also uses a small welded material having a small heat capacity (for example, a plate material having a cross-sectional shape of 3 mm × 1 mm or less, or a wire material having a wire diameter of 1 mm or less). The number of scenes handled is increasing. Usually, the management of the welding quality is performed with the amount of energy received by the workpiece to be welded by the main current welding (main energization). However, in the conventional TIG welding apparatus, when the above-mentioned touch start type arc welding is performed on a minute work material having a small heat capacity, the initial current of the initial energization and the main current of the main energization are adjusted or controlled in any way. Even so, the welded material melts undesirably due to the influence of the initial current, and good welding quality cannot be obtained, or the welded material itself melts down due to the influence of the initial current immediately after the arc start, Welding quality was not properly managed. In addition, the current of the initial current is used to prevent the arc from jumping (a phenomenon in which the arc jumps to other nearby workpieces) and the arc misfire (a phenomenon in which a fine workpiece is melted by the arc generated under the initial current). If the value is decreased, a phenomenon in which an arc is not generated easily occurs. These are real challenges.

Further, in the conventional touch start method, an arc formed from the material to be welded toward the tip of the torch electrode crawls up to the side surface (columnar body) above the tip portion (taper portion) of the torch electrode. A phenomenon may occur. This phenomenon is also considered to be a factor that welding fume generated from the material to be welded clings around the torch electrode and adheres to the torch electrode, that is, a factor that shortens the life of the torch electrode. For this reason, when the creeping phenomenon is noticeably observed, there is an increased possibility that the welding result will be poor, and this is avoided at the welding site. The inventors of the present invention have studied a method for suppressing the phenomenon of the arc creeping up on the body side surface of the torch electrode in the touch start type arc welding.

The present invention has been made in view of the above-described problems of the prior art, and an undesired phenomenon (such as an undesired creeping of an arc on a torch electrode) that causes TIG welding by a touch start method to cause poor welding. Provided are a TIG welding method and a TIG welding apparatus which can be stably and reliably performed without causing any arc, and particularly suitable arc welding can be performed even on a material to be welded having a small heat capacity to obtain good welding quality.

A TIG welding method according to a first aspect of the present invention includes a first step of driving a linearly movable portion supporting a torch electrode in a downward direction to move the torch electrode downward toward a workpiece, and the torch. A second step of stopping the drive of the linearly movable portion immediately after the tip of the electrode contacts the workpiece, and the torch electrode under a state where the tip of the torch electrode is in contact with the workpiece And a third step of flowing a first current for initial energization through a closed circuit including the material to be welded, and a fourth step of driving the linearly movable portion in the upward direction in order to move the torch electrode upward And a fifth step of detecting a separation timing at which the tip of the torch electrode separates from the workpiece, and a current flowing through the closed circuit at the same time or immediately after the separation timing is detected. From current to main And a sixth step of switching to the second current for.

A TIG welding apparatus according to a first aspect of the present invention includes a torch body that detachably mounts and holds a torch electrode, and a straight travel that is supported so as to be linearly movable in a direction parallel to the axial direction of the torch body. A predetermined circuit in a closed circuit including a movable part, a rectilinear drive part for driving the rectilinearly movable part in order to move the torch electrode downward or upward relative to the material to be welded, and the torch electrode and the material to be welded; A welding power source for passing an electric current, and a separation in which the tip of the torch electrode is separated from the material to be welded when the torch electrode is moved up from a state in which the tip of the torch electrode is in contact with the material to be welded And a control unit for controlling the linear drive unit and the welding power source, wherein the control unit is configured to generate the separation timing detection signal. The welding power source is controlled to flow a first current for initial energization to the closed circuit under a state where the tip of the electrode is in contact with the workpiece, and the control unit performs the initial energization. After a predetermined time from the start, the linear drive unit is controlled to start the upward movement of the torch electrode, and when the control unit receives the separation timing detection signal from the separation detection unit, Immediately, the welding power source is controlled to switch the current flowing through the closed circuit from the first current to the second current for main energization.

In the first aspect, after the initial energization is started by the touch start method and the first current for initial energization is supplied to the closed circuit including the torch electrode and the material to be welded, the linearly movable portion is moved upward. Sometimes, the timing at which the torch electrode is separated from the workpiece is simulated as the arc welding start timing, and at the same time or immediately after the separation timing is detected, the second current for main energization from the first current. Therefore, it is possible to reduce the time that the workpiece is exposed to the first current for initial energization after the occurrence of the arc as much as possible, and to control the material to be exposed to the arc by the second current for main energization. Can do.

A TIG welding apparatus according to a second aspect of the present invention includes a torch body that detachably mounts and holds a torch electrode, and a linear motion that is supported so as to be linearly movable in a direction parallel to the axial direction of the torch body. A predetermined circuit in a closed circuit including a movable part, a rectilinear drive part for driving the rectilinearly movable part in order to move the torch electrode downward or upward relative to the material to be welded, and the torch electrode and the material to be welded; A welding power source for supplying a current, and a touch timing detection signal by detecting a touch timing at which the tip of the torch electrode contacts the material to be welded in the downward movement of the torch electrode at a location away from the tip of the torch electrode When the torch electrode is moved up from a state in which the tip of the torch electrode is in contact with the material to be welded, and the torch electrode A separation detection unit for detecting a separation timing at which the tip of the electrode is separated from the workpiece to be welded at a location away from the tip of the torch electrode and generating a separation timing detection signal; and for controlling the linear drive unit and the welding power source And when the control unit receives the touch timing detection signal from the touch detection unit, the control unit controls the welding power source so as to start the initial energization immediately or after a predetermined time. And the control unit controls the welding power source to flow a first current for initial energization to the closed circuit under a state in which a tip of the torch electrode is in contact with the workpiece. And a predetermined time after starting the initial energization, the linear drive unit is controlled to start the upward movement of the torch electrode, and the control unit controls the separation timing from the separation detection unit. Upon receiving the grayed detection signal, therewith simultaneously or immediately controls the welding power source to switch the current applied to the closed circuit to a second current for the energization from said first current.

In the second aspect, after starting the initial energization by the touch start method and supplying the first current for initial energization to the closed circuit including the torch electrode and the material to be welded, the linearly movable portion is moved upward. Sometimes, the timing at which the torch electrode is separated from the workpiece is simulated as the start timing of arc welding, and the main current is switched to the main energization simultaneously or immediately. It is possible to control the exposure to the arc by the second current for main energization as much as possible. Furthermore, the touch detection and separation detection between the torch electrode and the material to be welded are performed by the touch detection unit and the separation detection unit located away from the tip of the torch electrode, respectively, so that the torch electrode and the welding target are generated from the heat generated at the welding location. It is possible to protect and precisely control the detection system of touch and separation with the material and the control system accompanied by these.

According to the TIG welding method or the TIG welding apparatus of the present invention, TIG welding by the touch start method is stably and surely performed by the above-described configuration and operation, and particularly a welded material having a small heat capacity (for example, a cross-sectional shape of 3 mm × 1 mm). For the following plate materials and wires having a wire diameter of 2 mm or less, the occurrence of arcs due to initial energization is reduced or eliminated as much as possible, so undesired welding of the welded material due to arcs due to initial energization and to the side of the torch electrode Appropriate arc welding in which the arc creeping phenomenon is eliminated is performed, and good welding quality can be obtained.

It is a block diagram which shows the whole structure of the TIG welding apparatus in one Embodiment of this invention. It is a fragmentary sectional view which shows the structure of the welding head part in the said TIG welding apparatus, and the state of each part of one step (when a torch is in a standby position) in TIG welding operation. It is a partial cross section side view which shows the state of the one stage in the said TIG welding operation (just before the front-end | tip of a torch electrode contacts a to-be-welded material). It is a partial cross section side view which shows the state of each part of the one stage (when the front-end | tip of a torch electrode is contacting the to-be-welded material) in the said TIG welding operation. It is a partial cross section side view which shows the state of each part of the said 1st step in TIG welding operation (immediately after the front-end | tip of the torch electrode isolate | separated from the to-be-welded material). It is a partial cross section side view which shows the state of each part of the one stage (just before completion | finish) in the said TIG welding operation. It is a partial cross section side view which shows the state of each part of the one step (immediately after completion | finish) in the said TIG welding operation. It is a timing diagram which shows the sequence of each control system in embodiment. It is a flowchart figure which shows the control procedure in the 1st control system of embodiment. It is a flowchart figure which shows the control procedure in the 2nd control system of embodiment. It is a flowchart figure which shows the control procedure in the 3rd control system of embodiment. It is a timing diagram which shows the sequence of the control system of a comparative example. It is a fragmentary perspective view which shows an example of a torch electrode. It is a partial cross section front view which shows the structure of the touch / separation detection part in another one Example. It is a partial cross section front view which shows the structure of the touch / separation detection part in another Example. It is a figure which shows the arc generation | occurence | production state (there is an arc climbing phenomenon) in the control system of a comparative example. It is a figure which shows the arc generation state (there is no arc creeping phenomenon) in the control system of the embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[Entire device and configuration of each part]

FIG. 1 is a block diagram showing the overall configuration of a TIG welding apparatus according to an embodiment of the present invention. This TIG welding apparatus is systematically connected to a torch body 12 that holds the torch electrode 10, a power supply system 14 that supplies required power to the torch electrode 10 or the torch body 12, and a workpiece to be welded directly under the torch body 12. An alignment mechanism 16 that aligns the material W, a rectilinear movement mechanism 18 that linearly moves 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 tapping system. The touch / separation detection unit 15 that detects the timing at which the workpiece 10 touches the workpiece W and the timing at which the torch electrode 10 is separated from the workpiece W, the entire system and each component (particularly the utility supply system 14, the alignment mechanism 16 and And a controller 20 for controlling the linear movement mechanism 18).

The torch body 12 is configured as a cylindrical body made of a conductor such as copper or brass or an insulator such as a resin, for example, and a torch electrode 10 made of, for example, a rod-like tungsten electrode is detachably inserted, and the torch is inserted from the nozzle portion 12a. The torch electrode 10 is held by protruding the tip of the electrode 10.

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

The welding power source 22 has a DC constant current source, preferably an inverter controlled constant current source having a high-speed current switching function. The positive output terminal (+) of the welding power source 22 is electrically connected to the workpiece W on the stage 28 via the electric cable 26 and the contact 27, and the negative output terminal (−) is connected via the electric cable 30. Thus, the torch electrode 10 in the torch body 12 is electrically connected. When the torch electrode 10 and the workpiece W are in physical contact, or when an arc discharge is generated between the torch electrode 10 and the workpiece W, the welding power source 22, the torch electrode 10, and the workpiece 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 and oxygen gas to the torch body 12 at a constant flow rate through a gas pipe 33 such as a flexible hose. The shield gas supplied to the torch body 12 is ejected from the nozzle portion 12a of the torch body 12 toward the workpiece W.

The alignment mechanism 16 is provided in or around the stage 28 on which the workpiece W is placed, and moves the stage 28 in the four axial directions of the horizontal direction (X direction and Y direction), the vertical direction, and the rotation direction. And a stage moving mechanism (not shown). Further, the positioning mechanism 16 or the stage 28 is provided with a fixing means for fixing the workpiece W on the stage 28 mechanically or by a vacuum suction force, and a clamp electrode (not shown) when clamping the workpiece W. 1), a compliance device or the like for sliding the workpiece W on the stage 28 in accordance with the clamping operation can be provided.

The rectilinear movement mechanism 18 supports the torch body 12, a rectilinear movable section 32 as a welding head provided so as to be movable up and down (straight movement) in a direction (vertical direction) parallel to the axial direction of the torch body 12, and the workpiece W On the other hand, it includes a rectilinear drive section 34 that linearly drives the rectilinear movable section 32 in the same direction to move the torch electrode 10 downward (advance) or ascend (retreat). Although not shown in the drawings, the linear drive unit 34 includes a drive source such as an electric motor, a motion conversion mechanism that converts the rotational drive force of the electric motor into a linear lift drive force, and the drive force of the lift motion linearly. And a transmission mechanism for transmitting to the movable portion 32.

As will be described later, the touch / separation detection unit 15 is preferably mounted on the rectilinear drive unit 34 and is located at a location away (or isolated) from the tip of the torch electrode 10, It is comprised so that the timing of the touch and isolation | separation with the to-be-welded material W may be detected. The specific configuration and operation of the touch / separation detection unit 15 will be described in detail later.

FIG. 2A shows the configuration of the rectilinearly movable portion 32 in this embodiment. The rectilinearly movable portion 32 has a rigid L-shaped plate body or base member 40 made of, for example, resin or metal, and the rectilinear drive portion 34 (see FIG. 1) behind the vertical flat plate portion 40a of the base member 40. ) Is coupled to the transmission mechanism via a connecting member 42.

On the base member 40, a multi-purpose support portion 44 having a substantially rectangular parallelepiped shape made of an insulator such as a resin is fixed to the front surface (the surface facing the torch body 12) of the vertical flat plate portion 40a. A utility relay portion 46 having a hollow block structure made of a conductor such as copper is attached to the upper surface of the multipurpose support portion 44. 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 section 46 and the balance arm 50 will be described in detail later.

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). Yes. Inside the torch guide 52, two

linear bushings

54H and 54L are provided with a certain space or intermediate portion in the vertical direction. The torch body 12 can accurately move straight in the vertical direction by the guidance of the

linear bushes

54H and 54L.

In the middle part of the torch guide 52, an opening 56 is formed at a position facing the versatile support part 44. Then, on the side surface of the intermediate portion of the torch body 12, a force introduction 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 the opening 56. The utility introducing portion 58 is electrically connected to the torch electrode 10 through a conductive path in 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 back surface (surface facing the torch body 12) of the utility introduction portion 58. The inside of the utility introduction portion 58 is a hollow gas chamber or gas passage, and the upstream side gas introduction port 60 and the downstream side gas introduction port communicate with each other.

Meanwhile, the utility relay section 46 on the multipurpose support section 44 is provided with a pair of downstream gas relay ports 62 on both side surfaces thereof. Between the downstream side gas relay port 62 and the gas introduction port 60 of the utility introduction portion 58, a bridge-type tube 64 made of a resin that can be displaced or deformed and extends in an arch shape in the air is hung. Further, between the mutually facing surfaces (front surfaces) of the utility relay portion 46 and the utility introduction portion 58, a bridge-like conductor 66 of a strip-like sheet that extends in an arch shape and can be deformed or deformed in the air is suspended. The band-shaped sheet bridging conductor 66 is formed by stacking a plurality of (for example, nine) ultra-thin copper sheets having a thickness of 0.05 mm, for example.

On the upper surface of the utility relay section 46, a conductive upstream gas relay port 68 is provided. The port 68 is detachably connected to a terminal connector 72 of a power supply cable 70 that accommodates the electric cable 30 from the welding power source 22 (FIG. 1) and the gas pipe 33 from the gas supply unit 24 (FIG. 1). . In this case, not only the gas supply line (gas pipe) 33 in the utility power supply cable 70 is connected to the gas passage of the upstream gas relay port 68 but also the welding current supply line (electric cable) 30 in the utility power supply cable 70. Is electrically connected to the main body of the utility relay unit 46. The inside of the utility relay section 46 is a hollow gas chamber or gas passage, and the upstream gas relay port 68 and the downstream gas relay port 62 communicate with each other.

Although the utility power supply cable 70 is a relatively heavy cable, since it terminates at the utility relay section 46 as described above, its weight is applied to the base member 40, and the torch 13 including the torch electrode 10 and the torch body 12 is not at all. It does not take. The weight of the bridging tube 64 and the bridging conductor 66 is applied to the torch 13. The bridge type tube 64 and the bridge type conductor 66 are much lighter than the utility power supply cable 70, and the aerial postures of the bridge type tube 64 and the bridge type conductor 66 are arched and constant, so that the torch load hardly changes.

In the utility power supply system around the utility relay portion 46 on the multi-purpose support portion 44 and the utility introduction portion 58 on the torch body 12 side as described above, the shield gas sent from the gas supply portion 24 (FIG. 1) is the utility power supply. Cable 70 (gas pipe 33) → utility relay section 46 (upstream gas relay port 68 → downstream gas relay port 62) → bridge tube 64 → utility introduction section 58 (upstream gas introduction port 60 → downstream gas introduction port) ) → Torch body 12 → Torch nozzle 12a is configured to flow in the order described above through the gas flow path connected to the torch nozzle 12a. Further, the welding current sent from the welding power source 22 is the power supply cable 70 (electric cable 30) → the power relay section 46 (conductive block) → the bridging conductor 66 → the power introduction section 58 (conductive block) → the torch body. 12 → The current path connected to the torch electrode 10 flows in the above order or the reverse order (reverse direction).

The balance arm 50 is made of a rigid body such as stainless steel, and has a bent portion 50a, a first arm portion 50b, and a second arm portion 50c, and the whole is formed in a “f” shape. The bent portion 50a is rotatably attached to the front portions on both side surfaces of the multi-purpose support portion 44 by a fulcrum shaft 48. A laterally long bearing 76 that fits with a pin 74 fixed to the side surface of the torch body 12 is provided at the distal end of the first arm portion 50b. On the side surface of the torch guide 52, a vertically long opening (not shown) for passing a pin 74 movable in the vertical direction is formed.

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

In the balance arm 50, while the total weight around the torch 13 attached to the tip of the first arm portion 50b, that is, the torch load, a counterclockwise weight moment acts in FIG. 2A, while the second arm portion 50c A weight moment in the clockwise direction acts in FIG. 2A 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). Thus, by setting the weight moment on the torch side to be larger than the weight moment on the balance weight 80 side, when no external force is applied to the torch 13, the upper surface of the balance weight 98 is the multipurpose support portion 44 as shown in FIG. 2A. It contacts the lower surface (stopper). In this state, the balance arm 50 is stationary, and the torch 13 is held at a constant (reference) height position on the welding head 10.

The pin 74 of the torch 13 and the bearing 76 of the first arm portion 50b fitted to the pin 74 are a crank mechanism for mutually converting the vertical movement of the torch 13 and the rotational movement of the balance arm 50 from each other. Is configured.

The multipurpose support portion 44 is configured as a hollow casing or block, and an electromagnetic solenoid, for example, a plunger solenoid 90 facing the use force introduction portion 58 of the torch 13 is fixedly attached thereto through an opening (not shown). ing. When the plunger 92 of the plunger solenoid 90 moves forward, the tip of the plunger 92 comes into contact with the side surface (opposing surface) of the working force introduction portion 58 with a large pressing force, and the plunger solenoid 90 and the working force introduction portion 58 are physically integrated (coupled). As a result, the torch 13 and the base member 40 are physically integrated (coupled). In this integrated state, when the rectilinear drive section 34 moves the rectilinear movable section 32 up and down, the torch body 12 also moves up and down integrally with the rectilinear movable section 32.

As described above, in the TIG welding apparatus of this embodiment, the balance arm 50 is attached to the linearly movable portion 32 constituting the welding head via the fulcrum 48 so as to be rotatable in a vertical plane. The balance between the weight moment on the torch 13 side and the weight moment on the balance weight 80 side is adjusted by connecting the torch body 12 to the tip of the arm portion 50b and attaching the balance weight 80 to the tip of the second arm portion 50c. By simply doing, the torch load can be reduced to a very small load (for example, 30 g weight or less).

Further, in this TIG welding apparatus, on the linearly movable portion (welding head) 32, a touch timing and a timing of separation between the tip of the torch electrode 10 and the workpiece W are detected in a touch start method. A touch / separation detection unit 15 is provided. As shown in FIG. 2A, the touch / separation detection unit 15 sandwiches the light shielding member F between a plate-shaped light shielding member F integrally attached to an appropriate portion (for example, the lower end portion) of the balance arm 50. The light emitting element ED and the light receiving element PD are arranged at the same height position so as to face 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 the light beam P toward the light receiving element PD, and the light receiving element PD receives the light beam P or not. For example, binary signals having different values, such as H level / L level, 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 that processes 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 _A touch timing detection signal MS _A indicating the timing of touching the workpiece W is output, and the tip of the torch electrode 10 is separated from the workpiece W when the output signal of the light receiving element PD changes from L level to H level. A separation timing detection signal MS _B indicating the timing is output.

In this embodiment, for example, a linear scale 101 as shown in FIG. 2A is provided as a position sensor for measuring the relative height position of the linearly movable portion 32 or the torch 13 with respect to the stage 28 and the vertical movement distance. . The linear scale 101 includes a scale portion 103 that is fixed to the stage 28 and extends in the vertical direction, and a scale reading portion 105 that is attached to the base portion 40 for optically reading the scale of the scale portion 103. Yes. The output signal of the scale reading unit 105 is given to the control unit 20.

Furthermore, this TIG welding apparatus is provided with a voltage detection circuit 38 (FIG. 1) for detecting a voltage V (particularly the rise) between the torch electrode 10 and the workpiece W. The voltage detection circuit 38 detects the rising edge of the voltage V generated in the gap between the torch electrode 10 when the torch electrode 10 is separated from the workpiece W during energization of the touch start, and the rising edge timing (separation timing). ) Is provided to the control unit 22. The voltage detection circuit 38 preferably includes a differentiation circuit in order to detect the rising edge of the voltage V accurately and at high speed.

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

Hereinafter, the operation of the TIG welding apparatus and the TIG welding method in this embodiment will be described with reference to FIGS. 2A to 2F, FIG. 3, and FIGS. 4A to 4C.

FIG. 2A to FIG. 2F show the state of each part in the welding head at each stage of the TIG welding operation according to the embodiment (first control method). FIG. 3 shows a sequence of TIG welding operations by each control method of this embodiment. 4A to 4C show control procedures of the control unit 20 in each control method.

2A to 2F, a material W to be welded shown as an example is obtained by winding a thin covered wire 104 around a strip-shaped terminal member 102 protruding from a work main body 100 such as a small precision electronic component package, and this winding portion. The welded part. In terms of dimensions, for example, the width of the terminal member 102 is about 1 mm, the thickness is about 0.2 mm, and the thickness of the covered wire 104 is about 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.

First control scheme (FIG. 3, FIG. 4A) of this embodiment according to, the control unit 20, by entering the start signal at time t ₀ in FIG. 3, first, initialization is performed (step S _101), the During initialization, set values of various conditions used for the current TIG welding are read from the memory and set in a predetermined register. These conditions include the current values of the initial current I _O and the main current I _M , the initial energization time T _{O, the} main energization time T _{M, and the} like.

Next, the control unit 20 controls the rectilinear drive unit 34 to start the downward movement of the rectilinear movable unit 32 that has been stationary at the standby position until then (step S ₁₀₂ ). In this case, in the initial state, the balance arm 50 is stationary on the linearly movable portion 32 in the state shown in FIG. 2A, and the light shielding member F at the lower end of the balance arm 50 is slightly above the optical path of the light beam P. Evacuated. Thereby, the light beam P from the light emitting element ED passes under the light shielding member F so as to enter 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 linearly movable part 32 is maintained until just before the tip of the torch electrode 10 touches the workpiece W.

On the other hand, under the control of the control unit 20, the welding power source 22 maintains the output switch SW in the OFF state. The gas supply unit 24 starts supplying shield gas in the middle of lowering the linearly movable unit 32 and the torch 12. As described above, the shield gas sent from the gas supply unit 24 to the welding head (straight-moving movable unit) 32 via the utility supply cable 70 (gas pipe 33) is the utility relay unit 46 → the bridge type tube 64 → the utility force. It is injected toward the workpiece W from the injection port of the torch nozzle 12a through each gas flow path of the introduction part 58 → the torch body 12 → the torch nozzle 12a.

As shown in FIG. 2C, when the tip of the torch electrode 10 abuts (touches) the workpiece W, the torch electrode 10 receives a reaction from the workpiece W, so that the balance arm 50 rotates in the clockwise direction in the figure. And 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 the previous H level to the L level, and the touch / separation detection unit 15 (FIG. 1) generates the touch timing detection signal MS _A , and receives this signal MS _A for control. The unit 20 recognizes or detects the timing at which the tip of the torch electrode 10 touches the workpiece W (time t _{1 in} FIG. 3) (step S ₁₀₃ ).

When detecting the touch timing (time point t ₁ ) as described above, the control unit 20 controls the linear drive unit 34 to immediately stop the downward movement of the linearly movable unit 32 (Step S ₁₀₄ ). Next, the switch SW of the welding power source 22 is switched from the previous OFF state to the ON state, and the welding power source 22 is caused to output a predetermined initial current _IO for initial energization (step S ₁₀₅ ). In this initial energization, the positive output terminal of the DC voltage source E of the welding power source 22 → the ground cable 26 → the material to be welded W → the torch electrode 10 → the torch body 12 → the force introducing portion 58 → the bridging conductor 66 → the power relay portion 46 → In the current path (closed circuit) of the negative output terminal of the utility voltage 77 (electric cable 30) → DC voltage source E, a DC initial current I ₀ flows.

The set current value of the initial current I ₀ is an arbitrary value. When the workpiece W is a small work having a small heat capacity as in this embodiment, the current amount of the initial current I _O is set to be considerably small. The As long as it is in the touch state, the torch electrode 10 and the workpiece W are electrically short-circuited, so even if the initial current I ₀ flows, the applied voltage V between them is zero volts.

Touch start method of this embodiment is for the purpose of Haisuru the penetration of undesired material to be welded due to the initial current I _0, the set value of the initial current I ₀ is set to a value smaller than the normal . The set value may be any value as long as a weak arc can be raised between the torch electrode and the material to be welded, and is usually set to about 5A. The initial current I _{0 of} 5A is a small value for a general touch start method, but the material to be welded is very small, for example, the wire diameter is 1 mm or less, and the material to be welded due to the weak initial current at the time of arc start. When it is considered that the influence of the penetration is large, the initial current I ₀ may be set to a smaller value, for example, 2A. On the other hand, the initial current I ₀ may be set to a lower value. For example, when the current is set to about 1 A, the initial current I ₀ is too small even if the material to be welded is very small. Many arcs do not occur stably. Therefore, the initial current I ₀ is preferably set to 1.5 A or more, preferably 2 A or more.

In this first control method, even if such a small initial current I ₀ is used, the material W to be welded W is prevented from being melted undesirably due to the influence of the initial current I ₀ at the start of the arc. In addition, the arc can be controlled by the main current I _M for main energization that is instantaneously switched.

When the timer counts up the initial energization set time T ₀ (step S ₁₀₆ ), the control unit 20 starts to move upward to the rectilinear movable unit 32 via the rectilinear drive unit 34 while maintaining the energized state. (Step _S107 ). When the linearly movable portion 32 starts to move upward, the torch 13 also starts to move upward, and the tip of the torch electrode 10 is separated from the workpiece W. Then, as shown in FIG. 2D, the torch electrode 10 is not subjected to the reaction from the workpiece W side, and the balance arm 50 is rotated in the direction returning to the initial state, that is, the counterclockwise direction in the figure, so that the light shielding member F The light beam P is retracted 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, changes to H level from L level of the output signal to that of the light receiving element PD, touch / separation detector 15 (FIG. 1) generates a separation timing detection signal MS _B, the control unit receives this signal MS _B 20 recognizes or detects the timing at which the tip of the torch electrode 10 is separated from the workpiece W (time t _{2 in} FIG. 3) (step S ₁₀₈ ).

Then, the control unit 20 controls the welding power source 22 at the same time or immediately after detecting the separation timing (time point t ₂ ), so that the current flowing through the closed circuit is energized from the previous initial current _IO. Is switched to the main current I _M for use (step S ₁₀₉ ). In this main energization, the main current I _M is supplied to the arc AC and the workpiece W for a preset time (T _M ) with a preset current value. In this case, as soon as the tip of the torch electrode 10 is separated from the workpiece W in the energized state, an arc AC is immediately generated in the gap generated between the two, and this arc AC becomes a conductive path and forms a 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 workpiece W and the like. For small small workpieces W heat capacity as in this embodiment, the current value of the main current I _M is the current amount of starting current I _O (e.g., 5A) further larger than (e.g., 10A) Set to Further, the energization time _{T M} is set to the number 10ms, for example.

In this embodiment, the switching from the initial current I _O to the main current I _M is performed simultaneously or immediately with the detection of the separation timing (time t ₂ ) as described above (steps S ₁₀₈ → S ₁₀₉ ). Depending on the response speed on hardware such as the welding power source 22, a slight delay (for example, 5 ms) may occur in switching. However, this type of delay does not particularly affect the operation of TIG welding, and can be brought as close to zero as possible by improving the hardware. It is very important that there is no software or intentional delay.

As soon as the tip of the torch electrode 10 is separated from the workpiece W, an arc AC due to the main current I _M for main energization is generated in the gap formed between them, and the torch electrode 10 is moving upward. the workpieces W are exposed to the power or the energy of the arc AC in accordance with the current amount of the main current I _M, dissolved as expected. In this case, the arc length with increasing upward movement that is the distance of the torch electrode 10 is changed, since the heat capacity or size of the material to be welded W is small, as long as the amount of current of the main current I _M is appropriately controlled There is little effect on welding quality.

Control unit 20, when the energization time _{T M} is the time is up (step _{S 110),} it stops the energization to turn off the welding power source 22 (step _{S 111).} When the main current I _M is cut, the arc AC disappears at that moment. When the arc AC disappears, the melted portion of the workpiece W is immediately solidified by natural cooling in the atmosphere.

Thereafter, the control unit 20 turns off the gas supply unit 24, and controls the linear drive unit 34 when the linearly movable unit 32 reaches a predetermined position (for example, an initial position) to stop the ascending operation of the linearly movable unit 32. (Step _S112 ).

As described above, in the first control method, after starting the initial energization by the touch start method, the tip of the torch electrode 10 is separated from the workpiece W when the linearly movable portion 32 is moved upward. At the same time (time t ₂ ), switching from initial energization to main energization is performed, and arc welding is terminated when a preset main energization time _TM has elapsed from the separation timing (t ₂ ). By such a technique, it is possible to perform appropriate arc welding even on a workpiece W having a small heat capacity and easily melted even with a weak arc, and to obtain good welding quality. Further, it is possible to effectively prevent welding defects such as arc creeping, arc side jump (a phenomenon in which the arc jumps to other nearby workpieces), arc misfire, and the like.

In this regard, in a general touch start method, after the torch electrode touches the material to be welded, (A1) initial energization is started in a state where the torch electrode is in contact with the material to be welded (short circuit state) → (A2 ) Start torch lift → (A3) The torch electrode separates from the work piece → (A4) Weak arc occurs → (A5) Torch lift and move while maintaining initial energization and weak arc Continue → (A6) Establish a certain separation distance → (A7) A series of steps (A1) to (A7) in which the initial current is switched to the main current of main energization. The first control method described above has its unique control concept in that the process (A4) to (A6) are skipped from the process (A3) and the process proceeds to the process (A7). Is a different special touch start method.

Under the touch state, the plunger solenoid 90 is operated in the linearly movable portion 32 to integrate the torch body 12 with the base member 40 of the linearly movable portion 32, and the torch electrode 10 is integrated with the linearly movable portion 32 after the touch start. It is also possible to move up. However, if the plunger 92 of the plunger solenoid 90 is applied to the side surface (opposed surface) of the utility force introduction portion 58 with a large pressing force under the touched state, it is unnecessary for the work piece W to be welded via the torch body 12 and the torch electrode 10. Pressure may be applied, which may cause undesirable damage and deformation to the minute workpiece W having a small heat capacity. Furthermore, it is difficult to accurately detect the timing (t ₂ ) when the tip of the torch electrode 10 is separated from the workpiece W when the linearly 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 linearly movable unit 32 via the balance arm 50, and the balance arm 50 is The timing when the light shielding member F starts to move clockwise from the stationary state and enters the optical path of the light beam P of the optical sensor (ED / PD) is detected as the touch timing (t ₁ ), and the balance arm 50 is counterclockwise from the stationary state. The timing at which the light shielding member F starts to move in the direction and leaves 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 rectilinearly movable portion 32 is set so as to match when the touch timing (t ₁ ) is detected and when the separation timing (t ₂ ) is detected. Yes. The touch / separation detection unit 15 is provided at a location sufficiently separated (or isolated) from the tip of the torch electrode 10 and operates without receiving any heat from the arc AC, so that precise timing detection operation is accurately performed. be able to.

In this embodiment, the control unit 20 can also detect the separation timing (t ₂ ) via the voltage detection circuit 38. When the torch electrode 10 is separated from the workpiece W during energization of the touch start, a gap is generated between the two, so that the applied voltage V between the two peaks from the previous zero volt to the output of the welding power source 22. It rises at a constant or indefinite rate up to the value. For this reason, according to the method of detecting the time point when the voltage V rises to a certain reference value, a timing considerably delayed from the actual separation timing (t ₂ ) is detected. In this embodiment, the voltage detection circuit 38 includes a differentiating circuit, and the actual separation timing (t ₂ ) can be detected without delay by differentiating the rising change of the voltage V.

The second control method (FIGS. 3 and 4B) follows the basic control concept of the first control method described above (steps S ₂₀₁ to S ₂₁₂ ), and sets the rectilinear movable unit 32 to a set distance after the touch start. It is moved up by H _S (step S ₂₁₀ ), that is, moved up to a position where the tip of the torch electrode 10 is separated from the workpiece W by a set separation distance H _S and temporarily stopped (time point t _{3 in} FIG. ₃ ). During this stop period, the main energization time _TM is increased (steps _S213 to _S214 ). This second control method can be suitably applied to TIG welding for a material 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 ), and the initial energization is performed by touching. It starts after the elapse of a certain period _TF from the timing (t ₁ ) and is limited to immediately before the separation timing (t ₂ ) (step S ₃₀₅ ), and the initial energization time (T _O ) is set as short as possible. (Steps S ₃₀₆ to S ₃₀₇ ) are characteristic. In this case, the rising slope of the initial current _{IO and} the rising slope of the main current I _M for main energization are made continuous so that the energization current can be raised from the zero ampere to the peak value of the main current I _{M in} the shortest time. . In this case, well over the rising up slope control of the main current I _M, even down slope control the falling be suitably used. This second control method can be suitably applied to TIG welding for a material to be welded having a very small heat capacity.

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

Furthermore, as shown in FIG. 9A and FIG. 9B, this embodiment and the comparative example have a remarkable difference in operation with respect to the presence or absence of the arc climbing phenomenon. According to the control method of the comparative example, as shown in FIG. 9A, when the tip of the torch electrode is separated from the material to be welded and separated, the arc by the initial current formed from the material to be welded toward the tip of the torch electrode Tends to creep up to the side of the columnar body of the torch electrode. Such an arc creeping phenomenon greatly reduces the concentration and stability of the arc with respect to the workpiece. On the other hand, according to this embodiment (for example, the first control method described above), since the arc is generated from the beginning under the main current of main energization, as shown in FIG. It does not occur, and a highly concentrated arc is stably generated between the tip of the torch electrode and the end of the workpiece.
[Other Embodiments or Modifications]

The preferred embodiments of the present invention have been described above, but the above-described embodiments do not limit the present 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, for a to-be-welded material W (W ₁ , W ₂ ) having a small size, 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 deviated from the center of the workpiece W, the tip surface of the torch electrode 10 abuts the top surface of the workpiece W, so that the workpiece is reliably connected. The arc can be concentrated near the center of W (W ₁ , W ₂ ). In the touch start method, the current is switched to the main energization at the same time or immediately when the separation timing is detected to prevent the arc from rising to the side surface of the torch electrode, and the work piece W (W ₁ , W ₂ ), the arc can be concentrated near the center.

FIG. 7 shows another example of the load balance mechanism and the touch / separation detection unit 15 provided on the rectilinearly movable portion (welding head) 32 in the above-described embodiment. In the figure, the same reference numerals are used for portions having the same configuration or function as those in FIGS. 2A to 2F. The welding current supply system and the gas supply system are not shown.

In the load balance mechanism in this embodiment, the compression coil spring 114 and the tension coil spring 116 are arranged in parallel between the main body 110 of the linearly movable portion 32 and the horizontal connecting rod 112 fixed to the torch body 12. Here, the spring load of the compression coil spring 114 can be adjusted by the first torch load adjusting unit 122 including the bar screw 118 and the nut 120, and the spring load of the tension coil spring 116 includes the bar screw 124 and the nut 126. Adjustment is possible by the second torch load adjusting unit 128.

A downward load in the Z direction is applied to the torch body 12, which is the sum of the weight (self-weight) L _{13 of the} entire torch 13 including accessories such as the connecting rod 112 and the spring load L ₁₁₄ of the compression coil spring 114. On the other hand, the spring load L ₁₁₆ of the tension coil spring 116 is applied upward in the Z direction. Assuming that the downward load in the Z direction is the positive direction and the total combined load applied to the torch body 12 is TL, TL = L ₁₃ + L ₁₁₄ −L ₁₁₆ . _{Here, L 13} is because it is substantially constant, by the _L _{114, L 116} variably adjusted by the first and second torch

load adjusting portion

122, 128 as described above, according to the characteristics of workpieces W Thus, the total combined load TL can be arbitrarily adjusted.

The touch / separation detection unit 15 in this embodiment is provided between the horizontal bar 130 and the main body 110 that extend horizontally on the opposite side (left side in the figure) to the connecting bar 112. More specifically, a light shielding 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 to face each other at the same height position.

In such a configuration, when the tip of the torch electrode 10 touches the workpiece (not shown), the torch 13 (the torch electrode 10 and the torch body 12) is the main body of the rectilinearly movable portion 32 due to the reaction from the workpiece side. As shown in FIG. 7, the light shielding 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 previous H level to the L level. Changes to. Thereafter, 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 linearly movable portion 32. Then, the light shielding member F is retracted downward from the optical path of the light beam P, and the output signal of the light receiving element PD changes from the previous L level to the H level.

In this way, the touch / separation detection unit 15 in this embodiment is a relative between the main body 110 of the linearly movable unit 32 and the torch 13 coupled to the main body 110 via the compression coil spring 114 and the tension coil spring 116. The movement or positional relationship is optically monitored to detect touch timing and separation timing in the touch start method.

In the touch / separation detection unit 15, an optical sensor for detecting the touch timing and an optical sensor for detecting the separation timing may be separately provided.

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

In this case, at the touch start, until the tip of the torch electrode 10 descends and comes into contact with the workpiece W, the tip of the light shielding member F is from the light beam P that propagates horizontally between the light emitting element ED and the light receiving element PD. The output signal of the light receiving element PD is at the H level. When the tip of the torch electrode 10 comes into contact with the workpiece W, the light beam P is blocked or shielded by the tip of the light shielding member F substantially simultaneously with this, and the output signal of the light receiving element PD changes from H level to L level. . Thereafter, when the initial energization is completed and the tip of the torch electrode 10 is separated from the material to be welded by the ascending of the linearly movable portion 32, the tip of the light shielding member F is retracted upward from the optical path of the light beam P almost simultaneously with this. The output signal of the element PD changes from L level to H level.

Although not shown in the drawing, two sets of photosensors (ED ₁ / PD ₁ ) and (ED ₂ / PD ₂ ) are arranged at different height positions, and the first photosensor having a higher arrangement (detection) position. The touch and separation timing is detected by (ED ₁ / PD ₁ ), and the initial energization start timing is acquired by the _second photosensor (ED ₂ / PD ₂ ) having the lower arrangement (detection) position. It is also possible. This method is suitable when initial energization is performed by further lowering the torch body 12 and applying a sufficiently large pressing force to the workpiece W even after the tip of the torch electrode 10 contacts the workpiece W.

DESCRIPTION OF SYMBOLS 10 Torch electrode 12 Torch body 15 Touch / separation detection part 20 Control part 22 Welding power supply 18 Straight movement mechanism 32 Straight movement part 34 Straight drive part 38 Voltage detection circuit W Welded material

Claims

A first step of driving the linearly movable portion supporting the torch electrode in the downward direction to move the torch electrode downward toward the workpiece; and
A second step of stopping the drive of the linearly movable portion immediately after the tip of the torch electrode contacts the material to be welded;
A third step of flowing a first current for initial energization to a closed circuit including the torch electrode and the material to be welded under a state in which a tip of the torch electrode is in contact with the material to be welded;
A fourth step of driving the linearly movable portion in the upward direction to move the torch electrode upward;
A fifth step of detecting the separation timing at which the tip of the torch electrode separates from the material to be welded;
And a sixth step of switching the current that flows through the closed circuit from the first current to the second current for main energization simultaneously or immediately with the detection of the separation timing.
2. The TIG welding method according to claim 1, wherein an energization time for supplying the second current is completed during the fourth step.
A seventh step of stopping driving of the rectilinear drive unit at a set separation position in which the tip of the torch electrode is separated from the workpiece by a set separation distance in the fourth step;
And an eighth step of temporarily stopping the torch electrode at the set separation position,
The energization time for passing the second current is terminated during the eighth step;
The TIG welding method according to claim 1.
The TIG welding method according to claim 1, wherein the third step is started immediately before the start of 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 made continuous.
A torch body that detachably attaches and holds a torch electrode; and
A rectilinearly movable portion that supports the torch body and is provided so as to be linearly 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 relative to the workpiece,
A welding power source for causing a predetermined current to flow in a closed circuit including the torch electrode and the material to be welded;
Separation timing detection by detecting the separation timing at which the tip of the torch electrode moves away from the material to be welded when the torch electrode is moved up from the state where the tip of the torch electrode is in contact with the material to be welded A separation detection unit for generating a signal;
And a controller for controlling the linear drive unit and the welding power source,
The control unit controls the welding power source to flow a first current for initial energization to the closed circuit under a state in which a tip of the torch electrode is in contact with the workpiece.
The controller controls the linear drive unit to start the upward movement of the torch electrode after a predetermined time from the start of the initial energization,
When the control unit receives the separation timing detection signal from the separation detection unit, simultaneously or immediately, the current flowing through the closed circuit is switched from the first current to the second current for main energization. So as to control the welding power source,
TIG welding equipment.
When the torch body is not subjected to external force on the linearly movable part, it is supported so as to be movable in the axial direction with a load balanced.
The separation detection unit monitors a relative movement or positional relationship of the torch body with respect to the linearly movable portion, and detects the separation timing according to a relative downward movement of the torch body.
The TIG welding apparatus according to claim 6.
The separation detection unit monitors an applied voltage between the torch electrode and the workpiece, and detects a rising edge when the applied voltage rises from zero volts toward a peak value as the separation timing. The TIG welding apparatus according to claim 6, comprising a detection circuit.
The TIG welding apparatus according to claim 8, wherein the voltage detection circuit has a differentiation circuit.
A touch detection unit for detecting a touch timing when a tip of the torch electrode touches the workpiece to be welded in a downward movement of the torch electrode and generating a touch timing detection signal;
The control unit, when receiving the touch timing detection signal from the touch detection unit, controls the welding power source to start the initial energization immediately or after a predetermined time,
The TIG welding apparatus according to claim 6.
When the torch body is not subjected to external force on the linearly movable part, it is supported so as to be movable in the axial direction with a load balanced.
The touch detection unit monitors a relative movement or positional relationship of the torch body with respect to the rectilinear movable unit, and detects a timing of the touch according to a relative upward movement of the torch body.
The TIG welding apparatus according to claim 10.
A torch body that detachably attaches and holds a torch electrode; and
A rectilinearly movable portion that supports the torch body and is provided so as to be linearly 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 relative to the workpiece,
A welding power source for causing a predetermined current to flow in a closed circuit including the torch electrode and the material to be welded;
A touch detection unit that detects a touch timing at which the tip of the torch electrode contacts the material to be welded in a downward movement of the torch electrode at a location away from the tip of the torch electrode, and generates a touch timing detection signal;
When the torch electrode is moved upward from a state in which the tip of the torch electrode is in contact with the workpiece, the separation timing at which the tip of the torch electrode is separated from the workpiece is separated from the tip of the torch electrode. A separation detection unit for detecting a separation timing detection signal at a remote location;
And a controller for controlling the linear drive unit and the welding power source,
When the control unit receives the touch timing detection signal from the touch detection unit, the welding power source is controlled to start the initial energization immediately or after a predetermined time,
The control unit controls the welding power source to flow a first current for initial energization to the closed circuit under a state in which a tip of the torch electrode is in contact with the workpiece.
The controller controls the linear drive unit to start the upward movement of the torch electrode after a predetermined time from the start of the initial energization,
When the control unit receives the separation timing detection signal from the separation detection unit, simultaneously or immediately, the current flowing through the closed circuit is switched from the first current to the second current for main energization. So as to control the welding power source,
TIG welding equipment.
When the torch body is not subjected to external force on the linearly movable part, it is supported so as to be movable in the axial direction with a load balanced.
The touch detection unit monitors a relative movement or positional relationship of the torch body with respect to the rectilinear movable unit, detects a timing of the touch according to a relative upward movement of the torch body,
The separation detection unit monitors a relative movement or positional relationship of the torch body with respect to the rectilinear movable unit, and detects a timing of the touch according to a relative downward movement of the torch body;
The TIG welding apparatus according to claim 12.
The TIG welding apparatus according to claim 13, wherein the touch detection unit and the separation detection unit have a common optical sensor for monitoring a relative movement or positional relationship of the torch body with respect to the rectilinear movable unit.
The TIG welding apparatus according to claim 6 or 12, wherein the torch electrode has a tip surface of any one of a minus (-) shape, a rectangular shape, and a flat shape.