JP2014128816A - Touch start control method of non-consumable electrode arc welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a damage when an electrode contacts a base material to shorten time required for arc start in a touch start control method of non-consumable electrode arc welding.SOLUTION: When a welding torch reaches a welding start position Sp corrected in the previous time at time t2, the welding torch is moved forward at second advance speed W2 until it reaches high speed advance distance Lh at time t3, after that, the welding torch is moved forward until an electrode contacts a base material at first advance speed W1, after that, the welding torch is moved backward, the electrode is separated from the base material, and arc is generated. Time T1 of forward movement at the first advance speed W1 is simultaneously measured, and the next welding start position Sp is corrected so that an initial distance calculation value Lic=T1×W1+Lh equals to a predetermined initial distance setting value Lir. Thus, since forward movement speed of the electrode becomes high at first, and becomes low from the middle, a damage due to contact with the base material is suppressed, and the total time of the forward movement can be shortened.

Description

  In the present invention, when the welding torch on which the electrode is mounted by the movement of the robot arrives at the welding start position, the welding torch is moved forward to contact the electrode with the base material, and then the welding torch is moved backward to move the electrode to the base material. The present invention relates to a touch start control method of non-consumable electrode arc welding in which an arc is generated by being separated from the touch.

  Non-consumable electrode arc welding includes TIG welding, plasma arc welding, and the like. In these non-consumable electrode arc welding, a method of igniting a high frequency high voltage between an electrode and a base material is commonly used to ignite the arc. However, in the arc start method using such a high frequency high voltage, strong electromagnetic noise is generated, which may cause a malfunction to a peripheral device and sometimes cause a failure. In addition, the arc start method using a high frequency high voltage has a problem that when the welding cable becomes as long as several tens of meters, the voltage value is attenuated, resulting in poor arc start performance.

  In order to solve these problems, a method called touch start control is used. In this touch start control method, when the welding torch arrives at the welding start position due to the movement of the robot, the welding torch is moved forward to bring the electrode into contact with the base material. An initial current having a value is applied, and then the welding torch is moved backward to separate the electrode from the base material to generate an arc. When the arc is generated, a predetermined steady current is applied. The initial current is set to a value at which the electrode and the base material are not welded, for example, about 1 to 10A. In this touch start control method, no electromagnetic noise is generated, and good arc start performance can be obtained even when the welding cable is long.

  In the invention of Patent Document 1, in the touch start control, when the arc is generated by separating the electrode from the base material, in order to suppress the arc from being extinguished without being able to maintain the arc, When the arc is generated, a current larger than the steady current is applied for a certain period. Further, in the invention of Patent Document 2, in the touch start control method, when the electrode and the base material are in contact with each other, a transient large current is applied to suppress the electrode and the base material from being welded. Therefore, an initial current energizing power source that does not energize a large current is provided independently of the welding power source.

Japanese Patent No. 2640313 JP 2000-176640 A

  As described above, in the touch start control method, no high frequency high voltage is applied, so that electromagnetic wave noise does not occur, and good arc start performance can be obtained even when the welding cable is long. When touch start control is performed with a welding torch attached to the robot, the welding torch is moved forward by moving the robot forward to bring the electrode into contact with the base material, and then the robot is moved backward to move the welding torch. Retract and move the electrode away from the base material to generate an arc. At this time, if the speed of forward movement of the robot is high, the electrode tip will come into violent contact with the base material, and the electrode tip may be deformed or lost. When the electrode tip is in such a state, the steady-state arc becomes a non-target shape or an excessively wide shape, resulting in poor welding results. For this reason, the electrode is frequently ground or replaced. Conversely, when the speed of forward movement by the robot is slow, deformation or loss of the electrode tip during contact can be prevented, but the time required for the electrode to contact the base material becomes longer. In the case of repeatedly welding a welding portion having a short welding length, the time required for each arc start becomes long, so that the tact time becomes long and the production efficiency decreases.

  Therefore, according to the present invention, in the touch start control method, it is possible to suppress the electrode tip from being deformed or missing when the electrode comes into contact with the base material, and to suppress an increase in the time required for the arc start. An object of the present invention is to provide a touch start control method for non-consumable electrode arc welding.

In order to solve the above-described problem, the invention according to claim 1 is configured to move the welding torch forward when the welding torch equipped with the electrode arrives at the welding start position by the movement of the robot to bring the electrode into contact with the base material. Then, in the touch start control method of non-consumable electrode arc welding in which the welding torch is moved backward to separate the electrode from the base material to generate an arc,
The welding start position, an initial distance set value that is a target distance between the electrode and the base material at the welding start position, a high-speed advance distance that is smaller than the initial distance set value, a first advance speed, and the first advance Preset a second forward speed that is faster than the speed,
At the time of the first arc start, when the welding torch arrives at the welding start position, the welding torch is moved forward at a first forward speed until the electrode contacts the base material, and the time for this forward movement is set. Measuring, and then moving the welding torch backward to separate the electrode from the base material to generate an arc, multiplying the forward movement time and the first forward speed to calculate an initial distance calculation value, Correct the welding start position so that the initial distance calculation value is equal to the initial distance setting value,
At the time of the second or subsequent arc start, when the welding torch reaches the corrected welding start position, the welding torch is moved forward at the second forward speed until the high speed forward distance is reached, and thereafter Switching to the first forward speed and moving the electrode forward until it contacts the base material, and then moving the welding torch backward to pull the electrode away from the base material to generate an arc;
This is a touch start control method for non-consumable electrode arc welding.

According to a second aspect of the present invention, at the second or subsequent arc start, when the welding torch arrives at the welding start position corrected at the previous arc start, the welding torch is moved until the high-speed advance distance is reached. 2 advance forward at a forward speed, then switch to the first forward speed until the electrode is in contact with the base material, and then move the welding torch backward to remove the electrode from the base material. An arc is generated by pulling apart, the forward movement time at the first forward speed at the start of the arc is measured as the first forward movement time, and the value obtained by multiplying the first forward movement time and the first forward speed is the high speed Adding the advance distance to calculate the initial distance calculated value, and correcting the welding start position so that the initial distance calculated value is equal to the initial distance set value;
The touch start control method for non-consumable electrode arc welding according to claim 1.

According to a third aspect of the present invention, when there are a plurality of welding locations, the welding start position, the initial distance setting value, the high-speed advance distance, the first advance speed, and the second advance speed are determined for each weld location. Set independently,
The touch start control method of non-consumable electrode arc welding according to claim 1 or 2.

  According to the present invention, since the first advance speed when the electrode contacts the base material is low, it is possible to suppress deformation or loss of the tip of the electrode. Furthermore, at the second and subsequent arc starts, the forward movement speed is the second forward speed that is high to the middle, so the time required for forward movement can be reduced and the total time required for arc start can be reduced. . Further, since the welding start position is corrected so that the initial distance calculation value becomes equal to the initial distance setting value, even if the initial distance fluctuates due to polishing or replacement of the electrode, adjustment of the workpiece fixing position, etc., the welding start position is It is automatically corrected. For this reason, the electrode deformation or defect countermeasure effect and the arc start time shortening effect can always be exhibited even if the initial distance varies.

It is a block diagram of the welding apparatus for enforcing the touch start control method of the non-consumable electrode arc welding which concerns on Embodiment 1 of this invention. 3 is a timing chart of each signal in the welding apparatus of FIG. 1 showing an operation at the first arc start in the touch start control method of non-consumable electrode arc welding according to Embodiment 1 of the present invention. 2 is a timing chart of each signal in the welding apparatus of FIG. 1 showing an operation at the second and subsequent arc start in the non-consumable electrode arc welding touch start control method according to Embodiment 1 of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
FIG. 1 is a configuration diagram of a welding apparatus using a robot for carrying out a touch start control method for non-consumable electrode arc welding according to Embodiment 1 of the present invention. Hereinafter, each component will be described with reference to FIG.

  The short-circuit determination circuit SD receives the welding voltage Vw applied between the electrode 1 and the base material 2 as input, determines that the short-circuit state is present when the value of the welding voltage Vw is less than the threshold value, and sets the high level. The short circuit determination signal Sd is output. The threshold is set to about 10V. When the short circuit determination signal Sd is at a low level, a state in which a no-load voltage of about 70 V is applied between the electrode 1 and the base material 2 or an arc generation state in which an arc voltage of about 15 to 40 V is applied. Is the time. This short circuit determination circuit SD is often built in the robot controller RC or the welding power source PS.

The robot controller RC receives the welding start signal St from the outside and the short-circuit determination signal Sd as described above, and performs the following processing, which will be described in detail with reference to FIGS. 2 and 3, to control the operation of the robot RM. Is output to a servo motor (not shown) of each axis of the robot RM, and a start signal On and a current setting signal Ir are output to the welding power source PS.
1) When the welding start signal St becomes High level, an operation control signal Mc for moving the welding torch 4 mounted on the robot RM to the welding start position Sp taught in advance is output.
2) When the welding torch 4 arrives at the welding start position Sp, the start signal On is set to High level (output start of the welding power source PS), and the current setting signal Ir is set to a predetermined initial current setting value Iir. To do. At the same time, an operation control signal Mc for moving the welding torch 4 forward is output. The forward movement direction is the longitudinal direction of the electrode 1. Details of the forward movement will be described later with reference to FIG.
3) When the electrode 1 comes into contact with the base material 2 by the forward movement, the short circuit determination signal Sd changes to the high level. In response to this, an operation control signal Mc for moving the welding torch 4 backward is output. The direction of the backward movement is opposite to the forward movement.
4) When the electrode 1 and the base material 2 are separated by the backward movement and the arc 3 is generated, the short circuit determination signal Sd changes to the Low level. In response to this change, the current setting signal Ir is switched to a predetermined start current setting value Isr and output. The backward movement continues.
5) When the welding torch 4 returns to the steady welding start position Cp taught in advance by the backward movement, the current setting signal Ir is switched to the predetermined steady current setting value Icr and output. At the same time, the backward movement of the welding torch 4 is stopped, the operation control signal Mc for moving along the welding line is output, and welding is started.

  The robot RM mounts the welding torch 4 and moves the tip position (TCP) of the welding torch 4 along the motion locus taught in advance according to the motion control signal Mc.

  The welding power source PS is a power source having a drooping characteristic or a constant current characteristic. When the starting signal On and the current setting signal Ir are input, the welding power source PS starts outputting when the starting signal On becomes a high level, and the current setting signal Ir The welding current Iw determined by is output.

  An arc 3 is generated between a non-consumable electrode 1 such as tungsten mounted on the welding torch 4 and the base material 2. A welding voltage Vw is applied between the electrode 1 and the base material 2, and a welding current Iw is passed through the arc 3. The distance between the tip of the electrode 1 and the base material 2 is the electrode tip / base material distance Lw (mm). Therefore, this electrode tip / base material distance Lw is the same as the arc length during arc generation.

  FIG. 2 is a timing chart of each signal in the welding apparatus of FIG. 1 showing the operation at the first arc start in the non-consumable electrode arc welding touch start control method according to Embodiment 1 of the present invention. (A) shows the time change of the welding start signal St, (B) shows the time change of the start signal On, (C) shows the time change of the current setting signal Ir, D) shows the time change of the short-circuit determination signal Sd, FIG. 8E shows the time change of the welding current Iw, and FIG. F shows the time change of the electrode tip / base material distance Lw. Hereinafter, a description will be given with reference to FIG.

  The first arc start is an arc start performed first when welding of the same workpiece is repeatedly performed. When the welding is resumed after being paused, this is the first arc start after the resume. Therefore, when welding the same workpiece as the previous day is also performed today, this is the first arc start of today. In addition, when welding is interrupted by electrode polishing, replacement, workpiece fixing position adjustment, welding equipment cleaning, or the like, this is the first arc start after the interruption.

(1) Period from time t1 to time t2 At time t1, as shown in FIG. 5A, when the welding start signal St is input from the outside (High level), the welding torch 4 mounted on the robot RM is moved. At time t2, the welding torch 4 arrives at the welding start position Sp taught in advance and stops.

(2) Period from time t2 to t4 When the welding torch 4 arrives at the welding start position Sp at time t2, the start signal On changes to the high level as shown in FIG. In response to this, the welding power source PS forms a constant current characteristic and starts output. However, during this period, the electrode 1 and the base material 2 are separated from each other and are in an unloaded state. Apply. At the same time, as shown in FIG. 5C, the current setting signal Ir changes from the predetermined steady current setting value Icr to a predetermined initial current setting value Iir having a small value at time t2. The robot RM starts moving forward from time t2, and the welding torch 4 also moves forward. This forward movement method will be described in detail below.

  An initial distance setting value Lir and a first forward speed W1 that are target distances between the electrode 1 and the base material 2 at the welding start position Sp are preset. At time t2, the welding torch 4 starts moving forward at the first forward speed W1, and continues until the electrode 1 comes into contact with the base material 2 at time t4. The forward movement time Ti at times t2 to t4 is measured. Then, the initial distance calculation value Lic = Ti × W1 is calculated by multiplying the forward movement time Ti and the first forward speed W1. As shown in FIG. 4F, the electrode tip / base material distance Lw gradually decreases during the period from time t2 to time t4 and becomes 0 at time t4.

  Here, the welding start position Sp is corrected so that the initial distance calculation value Lic is equal to the initial distance setting value Lir. For example, when Lic = 8 mm and Lir = 10 mm, the welding start position Sp is corrected to a position away from the base material 2 by 2 mm in the longitudinal direction of the electrode 1. Conversely, when Lic = 13 mm and Lir = 10 mm, the welding start position Sp is corrected to a position that approaches the base material 2 by 3 mm in the longitudinal direction of the electrode 1. The corrected welding start position Sp is a position where the welding torch 4 moves and stops at the second and subsequent arc starts.

  The initial distance setting value Lir is set to a distance longer than the arc length during steady welding. This is to prevent the electrode 1 from coming into violent contact with the base material 2 while moving toward the welding start position Sp due to variations in the protruding length of the electrode 1, the installation state of the base material 2, and the like. . The initial distance setting value Lir is, for example, 10 mm. The first forward speed W1 is set to a speed that does not cause deformation or chipping even when the electrode tip contacts the base material at this speed. The first forward speed W1 is, for example, 5 mm / s.

(3) Period from time t4 to t5 At time t4, as shown in FIG. 4F, when the electrode 1 comes into contact with the base material 2 by the forward movement of the welding torch 4, there is no welding voltage Vw (not shown). The load voltage rapidly decreases to a short-circuit voltage value of several volts, and the short-circuit determination signal Sd changes to the high level as shown in FIG. At the same time, as shown in FIG. 6C, the current setting signal Ir is the initial current setting value Iir, so that the welding current Iw is supplied with the initial current Ii as shown in FIG. In response to the change of the short circuit determination signal Sd to the high level, the welding torch 4 starts the backward movement in the direction opposite to the forward movement. However, since there is a time delay for the robot RM to switch from the forward movement to the backward movement, the electrode 1 and the base material 2 remain short-circuited until time t5. Therefore, as shown in FIG. 4F, the electrode tip / base material distance Lw remains 0 during the period from time t4 to time t5.

(4) Period of Times t5 to t6 When the tip of the electrode 1 is pulled away from the base material 2 by the backward movement of the welding torch 4 at time t5, the arc 3 is generated. When the arc 3 is generated, the welding voltage Vw rapidly increases to an arc voltage value of several tens of volts, so that the short circuit determination signal Sd changes to the low level as shown in FIG. In response to this, the current setting signal Ir changes to a predetermined start current setting value Isr as shown in FIG. Therefore, as shown in FIG. 5E, the start current Is is applied as the welding current Iw. Here, the start current Is is larger than the steady current Ic. The backward movement of the welding torch 4 is continued. As a result, as shown in FIG. 5F, the electrode tip / base material distance Lw gradually increases from 0 at time t5.

(5) Period after time t6 At time t6, when the backward movement distance at times t5 to t6 reaches a predetermined steady distance Lc, the welding torch 4 stops the backward movement. Thus, the welding torch 4 has returned to the steady welding start position Cp. Here, the backward movement distance from time t4 to t5 can be calculated by the backward speed × reverse movement time. When the welding torch 4 returns to the steady welding start position Cp at time t6, the current setting signal Ir changes to a predetermined steady current set value Icr as shown in FIG. For this reason, as shown in FIG. 5E, the steady current Ic is applied as the welding current Iw. The robot RM starts moving along the weld line from time t6. As shown in FIG. 4F, the electrode tip / base material distance Lw becomes equal to the steady distance Lc at time t6, which is shorter than that at time t2, and maintains that value thereafter.

  If the above retraction speed is too high, there is a possibility that an arc will fail to occur when the electrode 1 and the base material 2 are separated. On the other hand, when the reverse speed is low, the time required for arc start becomes long. Therefore, it is desirable to set the reverse speed to the fastest value at which the arc is surely generated and the arc is not extinguished during the reverse movement. The reverse speed is, for example, 20 mm / s. The steady distance Lc is a steady state arc length, and is set in consideration of welding quality. The steady distance Lc is, for example, 5 mm. In the figure, the start current Is is set to a value larger than the steady current Ic. This is because the temperature of the electrode 1 is rapidly increased to lead to a stable arc generation state. The start current Is may be energized for a predetermined period from the time when the arc 3 is generated at time t5.

  FIG. 3 is a timing chart of each signal in the welding apparatus of FIG. 1 showing the operation at the second and subsequent arc start in the non-consumable electrode arc welding touch start control method according to Embodiment 1 of the present invention. . (A) shows the time change of the welding start signal St, (B) shows the time change of the start signal On, (C) shows the time change of the current setting signal Ir, D) shows the time change of the short-circuit determination signal Sd, FIG. 8E shows the time change of the welding current Iw, and FIG. F shows the time change of the electrode tip / base material distance Lw. This figure corresponds to FIG. 2 described above, and only the operation during the period from time t1 to t4 is different, and the operation during the other periods is the same. Hereinafter, different operation periods will be described with reference to FIG.

(1) Period from time t1 to time t2 At time t1, as shown in FIG. 5A, when the welding start signal St is input from the outside (High level), the welding torch 4 mounted on the robot RM is moved. At time t2, the welding torch 4 arrives at the corrected welding start position Sp described above with reference to FIG. 2 and stops. The welding start Sp at the time of the first arc start described above with reference to FIG. 2 was a previously taught position, but the welding start position Sp at the time of the second and subsequent arc starts is at the time of the first arc start. This is the corrected position.

(2) Period of Times t2 to t4 When the welding torch 4 arrives at the corrected welding start position Sp at time t2, the start signal On changes to the high level as shown in FIG. In response to this, the welding power source PS forms a constant current characteristic and starts output. However, during this period, the electrode 1 and the base material 2 are separated from each other and are in an unloaded state. Apply. At the same time, as shown in FIG. 3C, the current setting signal Ir changes from the steady current setting value Icr to the initial current setting value Iir having a small value at time t2. The robot RM starts moving forward from time t2, and the welding torch 4 also moves forward. The direction of forward movement of the welding torch 4 is the longitudinal direction of the electrode 1. This forward movement method will be described in detail below.

  A high-speed forward distance Lh that is smaller than the initial distance setting value Lir and a second forward speed W2 that is faster than the first forward speed W1 are set in advance. At time t2, the welding torch 4 is moved forward at the second forward speed W2. As shown in FIG. 5F, when the forward movement distance at time t2 to t3 becomes equal to the high-speed forward distance Lh at time t3, the forward movement speed is switched to the first forward speed W1, and the electrode 1 becomes the base material 2 The forward movement is continued until time t4 when it comes into contact. The forward movement distance at times t2 to t3 can be calculated by measuring the second forward movement time T2 at times t2 to t3 and calculating T2 × W2. As shown in FIG. 6F, the electrode tip / base material distance Lw decreases rapidly during the period of time t2 to t3, gradually decreases during the period of time t3 to t4, and becomes 0 at time t4. It becomes.

  The second forward speed W2 is set to about 10 times the first forward speed W1 in order to reduce the time required for the arc start to the maximum. The second forward speed W2 is, for example, 50 mm / s. The high-speed forward distance Lh is a distance that can converge to the first forward speed W1 before the electrode 1 and the base material 2 come into contact with each other when the second forward speed W2 is switched to the first forward speed W1. Set to The high speed advance distance Lh is, for example, 5 mm.

  The operation in the period after time t4 is the same as that in FIG.

The non-consumable electrode touch start control method according to the first embodiment described above includes the following two steps.
(1) At the time of the first arc start, when the welding torch arrives at a preset welding start position, the welding torch is moved forward at a low first advance speed to bring the electrode and the base material into contact with each other, Perform touch start control. At the same time, the time for forward movement is measured and multiplied by the first forward speed to calculate the initial distance calculation value. The welding start position is corrected so that the initial distance calculation value becomes equal to a predetermined initial distance setting value.
(2) At the second or subsequent arc start, when the welding torch arrives at the corrected welding start position, the welding torch is moved forward at a high second advance speed until reaching a predetermined high speed advance distance. Thereafter, the touch start control is performed by switching to a low first forward speed and moving forward until the electrode contacts the base material.

  Therefore, according to the first embodiment, since the first forward speed when the electrode contacts the base material is low, it is possible to suppress deformation or loss of the tip of the electrode. Furthermore, at the second and subsequent arc starts, the forward movement speed is the second forward speed that is high to the middle, so the time required for forward movement can be reduced and the total time required for arc start can be reduced. . Further, since the welding start position is corrected so that the initial distance calculation value becomes equal to the initial distance setting value, even if the initial distance fluctuates due to polishing or replacement of the electrode, adjustment of the workpiece fixing position, etc., the welding start position is It is automatically corrected. For this reason, the electrode deformation or defect countermeasure effect and the arc start time shortening effect can always be exhibited even if the initial distance varies.

  The above shortening effect is shown by numerical examples. The desired distance setting value Lir = 10 mm, the high speed forward distance Lh = 5 mm, the first forward speed W1 = 5 mm / s, and the second forward speed W2 = 50 mm / s. When the initial distance Li is moved forward at the first forward speed W1 as in the prior art, the time until contact is Li / W1 = 2 seconds. On the other hand, at the time of the arc start after the second time in the present embodiment, the time to contact is L2 / W2 + L1 / W1 = 0.1 + 1 = 1.1 seconds. Therefore, it is shortened to about half. For this reason, the production efficiency is greatly improved in welding in which arc start is frequently repeated.

[Embodiment 2]
The invention of Embodiment 2 is
1) At the first arc start, the same touch start control as that of the first embodiment described above with reference to FIG. 2 is performed. Then, the welding start position Sp is corrected so that the initial distance calculation value Lic becomes equal to the initial distance setting value Lir.
(2) At the time of the second or subsequent arc start, when the welding torch arrives at the welding start position Sp corrected at the previous arc start, the touch start control of the first embodiment described above with reference to FIG. 3 is performed. The forward movement time at the first forward speed W1 at the time of the arc start is measured as the first forward movement time T1, and the high speed forward distance Lh is added to the value obtained by multiplying the first forward movement time T1 and the first forward speed W1. Then, the initial distance calculation value Lic is calculated, and the welding start position Sp is corrected so that the initial distance calculation value Lic becomes equal to the initial distance setting value Lir.

  A welding apparatus for carrying out the touch start control method of non-consumable electrode arc welding according to the second embodiment is the same as that in FIG. 1 described above. However, the operation of the robot controller RC is different. The operation of item 1) is the same as that of the first embodiment described above with reference to FIG.

The operation of the above item 2) is the first forward movement from the time t3 when the forward speed changes to the first forward speed W1 to the time t4 when the electrode 1 contacts the base material 2 in the touch start control method described above with reference to FIG. The time T1 is measured, and the initial distance calculation value Lic is calculated by the following equation.
Lic = T1 × W1 + Lh
Here, W1 is the first forward speed, and Lh is the high speed forward distance.
The welding start position Sp at the time of the current arc start is further corrected so that the initial distance calculation value Lic becomes equal to the initial distance setting value Lir. The corrected welding start position Sp is used at the next arc start.

  According to the second embodiment described above, in addition to the effects of the first embodiment, the following effects are provided. In the first embodiment, the welding start position corrected at the first arc start is used at the second and subsequent arc starts. However, as the number of arc starts increases, the tip of the electrode 1 gradually wears and the initial distance changes. In the second embodiment, the initial distance calculation value is calculated for each arc start to correct the welding start position, and the touch start control is performed using the welding start position corrected at the next arc start. For this reason, touch start control can always be performed based on the initial distance according to the set value, so that the electrode deformation or defect countermeasure effect and the arc start time reduction effect can be maximized.

[Embodiment 3]
In the invention of the third embodiment, when there are a plurality of welding locations, the welding start position, the initial distance setting value, the high-speed advance distance, the first advance speed, and the second advance speed are independently set for each weld location. To do.

  A welding apparatus for carrying out the touch start control method for non-consumable electrode arc welding according to the third embodiment is the same as that in FIG. 1 described above. However, the operation of the robot controller RC is different. This different operation will be described below.

  A case is assumed in which there are first to third welding locations with different welding conditions in one workpiece. Welding is performed in the order of the first welding location, the second welding location, and the third welding location, and is performed repeatedly by exchanging the workpiece.

  When the touch start control according to the first embodiment is performed for the above-described welding, the welding start position Sp and the high-speed advance distance Lh are independently provided for each of the first welding point, the second welding point, and the third welding point. The first forward speed W1 and the second forward speed W2 are set in advance. In addition, at the time of the first arc start for the first welding point, the touch start control described above with reference to FIG. 2 is performed and the welding start position Sp is corrected. Similarly, at the time of the first arc start with respect to the second welding point and the third welding point, the welding start position Sp of the second welding point and the welding start position Sp of the third welding point are respectively corrected. At the time of the second and subsequent arc start with respect to the first welding point, the touch start control described above with reference to FIG. 3 is performed using the corrected welding start position Sp. The same applies to the second and subsequent arc starts for the second welding point and the third welding point.

  When the touch start control according to the second embodiment is performed for the above-described welding, the welding start position Sp and the high-speed advance distance Lh are independently provided at each of the first welding point, the second welding point, and the third welding point. The first forward speed W1 and the second forward speed W2 are set in advance. In addition, at the time of the first arc start for the first welding location, the touch start control described above with reference to FIG. 2 is performed and the welding start position Sp of the first welding location is corrected. Similarly, at the time of the first arc start with respect to the second welding point and the third welding point, the welding start position Sp of the second welding point and the welding start position Sp of the third welding point are respectively corrected. At the time of the second and subsequent arc start with respect to the first welding location, the touch start control described above with reference to FIG. 3 is performed using the welding start position Sp of the first welding location corrected at the previous arc start, and welding is performed. The start position Sp is further corrected. The same applies to the second and subsequent arc starts for the second welding point and the third welding point.

  According to the third embodiment described above, the touch start control according to the first or second embodiment can be applied to a case where welding at a plurality of welding locations is repeatedly performed.

1 Electrode 2 Base material 3 Arc 4 Welding torch Cp Steady welding start position Ic Steady current Icr Steady current set value Ii Initial current Iir Initial current set value Ir Current set signal Is Start current Isr Start current set value Iw Welding current Lc Steady distance Lh High-speed forward distance Li Initial distance Lic Initial distance calculation value Lir Initial distance setting value Lw Electrode tip / base material distance Mc Operation control signal On Start signal PS Welding power supply RC Robot controller RM Robot SD Short circuit determination circuit Sd Short circuit determination signal Sp Welding Start position St Welding start signal T2 Second forward movement time Ti Forward movement time Vw Welding voltage W1 First forward speed W2 Second forward speed

Claims (3)

When the welding torch equipped with the electrode arrives at the welding start position by the movement of the robot, the welding torch is moved forward to contact the electrode with the base material, and then the welding torch is moved backward to move the electrode to the base. In the non-consumable electrode arc welding touch start control method that generates an arc separated from the material,
The welding start position, an initial distance set value that is a target distance between the electrode and the base material at the welding start position, a high-speed advance distance that is smaller than the initial distance set value, a first advance speed, and the first advance Preset a second forward speed that is faster than the speed,
At the time of the first arc start, when the welding torch arrives at the welding start position, the welding torch is moved forward at a first forward speed until the electrode contacts the base material, and the time for this forward movement is set. Measuring, and then moving the welding torch backward to separate the electrode from the base material to generate an arc, multiplying the forward movement time and the first forward speed to calculate an initial distance calculation value, Correct the welding start position so that the initial distance calculation value is equal to the initial distance setting value,
At the time of the second or subsequent arc start, when the welding torch reaches the corrected welding start position, the welding torch is moved forward at the second forward speed until the high speed forward distance is reached, and thereafter Switching to the first forward speed and moving the electrode forward until it contacts the base material, and then moving the welding torch backward to pull the electrode away from the base material to generate an arc;
A touch start control method for non-consumable electrode arc welding. At the second or subsequent arc start, when the welding torch reaches the welding start position corrected at the previous arc start, the welding torch is moved forward at the second forward speed until the high speed forward distance is reached. Then, the first forward speed is switched to move the electrode forward until it contacts the base material, and then the welding torch is moved backward to separate the electrode from the base material to generate an arc, The forward movement time due to the first forward speed at the start of the arc is measured as the first forward movement time, and the high-speed forward distance is added to the value obtained by multiplying the first forward movement time and the first forward speed. An initial distance calculation value is calculated, and the welding start position is corrected so that the initial distance calculation value is equal to the initial distance setting value.
The touch start control method of non-consumable electrode arc welding according to claim 1. When there are a plurality of welding locations, the welding start position, the initial distance setting value, the high-speed advance distance, the first advance speed and the second advance speed are independently set for each weld location.
The touch start control method for non-consumable electrode arc welding according to claim 1 or 2.

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