JP2008200725A - Controller for welding robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a welding robot that actualizes automatic welding, not relying on manual welding, of a welding section where welding defect possibly occurs due to excess welding current attributed to a variation in heat capacity of a base material occurring in performing boxing and the like and yet constant deposited bead width is required, thereby welding work for obtaining the constant deposited bead width can be performed at high efficiency of work by suppressing the welding defects due to the excess welding current. <P>SOLUTION: With the purpose of causing no welding defects due to excess welding current between welding the sections P102-P103, the controller 30 gradually varies a feeding speed F of a welding wire 21 and an inter-welding electrode voltage V between these welding sections P102-P103. At the same time, for the purpose of making a deposited bead width W constant between the welding sections P102-P103, the tip end moving speed S of the welding torch 17 is controlled to be gradually varied, in accordance with the variation in the feeding speed F of the welding wire 21 and in the inter-welding electrode voltage V between the welding sections P102-P103. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for a welding robot.

(Prior art 1)
As shown in FIG. 1, the welding robot control device includes a welding power source device 20 in which the feed speed of the welding wire 21 and the voltage between the welding electrodes are adjusted, and the welding torch 17 moves along the welding line of the base material. Thus, the welding robot 10 that drives each of the axes 11 to 16, and a controller 30 that controls the feed speed of the welding wire 21, the voltage between the welding electrodes, and the moving speed of the welding torch tip are configured.

FIG. 9 shows a state where the plate members 51 and 52 are joined by arc welding to manufacture the structure 50 of the T joint. In this case, the joint portion of the plate material 51 and the plate material 52 is continuously fillet welded linearly. However, the feed rate of the welding wire 21 and the voltage between the welding electrodes gradually decrease in order to prevent the base metal from being melted down by an excessive welding current in the welding sections P102 'to P103' at the end of the welding line. To be adjusted. As a result, the end welding section P102 '
From the start point P102 'to the end point P103' of P103 ', the welding amount per unit time gradually decreases and the weld bead width gradually decreases.

(Prior art 2)
In Patent Document 1, when the welding torch tip is rotated and moved along the corner portion to perform welding, the rotation of the welding torch tip at the corner portion is different even when the radius of the corner portion differs due to manufacturing errors. An invention is described in which the welding speed is adjusted so that the angular velocity is constant, and the welding current is adjusted according to the adjusted welding speed so that the amount of welding in the corner portion is constant. According to the present invention, the welding bead width in the corner portion can be made constant when performing turn welding.
JP 2003-334659 A

FIG. 3A shows how the structure 40 is manufactured by joining the members 41 and 42 by arc welding. The member 41 has an edge portion 41a. The member 41 and the plate material 42 are
After the continuous fillet welding is performed linearly along the linear welding sections P101 to P102, the member 4
It is turned and welded so as to change its direction by 90 degrees at a point P103 corresponding to one edge portion 41a.

However, the turn welding must be performed so that an excessive welding current does not cause a welding defect such as melting of the edge portion 41a of the member 41 or occurrence of an undercut in a joint portion around the edge portion 41a. Moreover, in order to prevent stress concentration around the edge portion 41a and to improve the appearance and appearance, in the welding sections P102 to P104 around the edge portion 41a, the previous welding sections P101 to P101 are used. It is necessary to make the welding bead width W the same as P102.

When the prior art 1 is applied to the rotary welding of the member 41 having the edge portion 41a shown in FIG. 3A, the burn-out due to an excessive welding current can be suppressed. However, the edge portion 41a
In the welding sections P102 to P104 around, the welding bead width W is not the same as the previous welding sections P101 to P102, but the welding bead width gradually decreases.

Further, when the conventional technique 2 is applied to the rotary welding of the member 41 having the edge portion 41a shown in FIG. 3A, the welding bead width W is constant in the welding sections P102 to P104 around the edge portion 41a. Become. However, since the welding speed and welding current in the welding sections P102 to P104 around the edge portion 41a are determined only by manufacturing errors, there is a gap between the welding speed and welding current in the previous welding sections P101 to P102. May occur.

For this reason, when the welding torch tip moves from the welding sections P101 to P102 to the welding sections P102 to P104 around the edge portion, the welding speed and the welding current change suddenly, whereby the welding bead does not change smoothly. May occur.

As described above, when turning and welding the member 41 having the edge portion 41a shown in FIG. 3, the welding bead width is made constant while the welding current is suppressed by a skilled worker by switching from automatic welding to manual welding. It is the actual situation. However, with manual welding, work efficiency is poor,
There is a request to automate this work.

The present invention has been made in view of such circumstances, and when welding a welding section that may cause a welding defect due to an excessive welding current and that requires a constant weld bead width, such as when turning welding, Solved the problem that it is possible to perform this work automatically without relying on manual welding to suppress welding defects due to excessive welding current and to perform welding work with a constant weld bead width. It is to be an issue.

The first invention is
A welding robot in which each axis is driven so that the welding torch moves along the welding line of the base material;
A welding power supply for supplying electric power to the welding robot to feed the welding wire and applying a voltage between the welding electrodes, and a controller for controlling the feeding speed of the welding wire, the voltage between the welding electrodes, and the moving speed of the welding torch tip A welding robot control device comprising:
The controller is
In order to prevent welding defects due to excessive welding current in the welding section where the base metal heat capacity changes, the welding wire feed rate and the voltage between the welding electrodes are gradually changed in the welding section,
Control is performed to gradually change the welding torch tip moving speed in accordance with changes in the welding wire feed speed and welding electrode voltage in the welding section so that the welding bead width is constant in the welding section. And

The second invention is the first invention,
The constant weld bead width in the weld zone is the same as the weld bead width in the previous weld zone, the rear weld zone, or the front and rear weld zones of the weld zone.

As shown in FIG. 1, the welding robot control apparatus of the present invention includes a welding robot 10 in which the axes 11 to 16 are driven so that a welding torch 17 moves along a welding line of a base material, and the welding robot 10. A welding power source device 20 for supplying a power to the welding wire 21 and applying a voltage V between the welding electrodes, a feeding speed F of the welding wire 21, a voltage V between the welding electrodes, and a moving speed S of the welding torch tip. And a controller 30 for controlling the above.

As shown in FIGS. 4 and 5, the controller 30 performs welding with an excessive welding current in the welding sections P102 to P103 in which the base metal heat capacity changes, such as a thickness change portion of the base material or a corner portion when performing turn welding. In order to prevent defects, the feed speed F of the welding wire 21 and the voltage V between the welding electrodes are gradually changed in the welding sections P102 to P103, and the welding section P10.
2 to P103, the welding torch 17 according to changes in the feed speed F of the welding wire 21 and the voltage V between the welding electrodes in the welding sections P102 to P103 so that the welding bead width W is constant.
Control to gradually change the tip moving speed S is performed.

According to the present invention, since the feed rate F of the welding wire 21 and the voltage V between the welding electrodes are adjusted so as to gradually change, it is possible to prevent the base metal from being melted by an excessive welding current in the welding sections P102 to P103. Is done. Since the welding torch 17 tip moving speed S is adjusted to change gradually according to changes in the feed speed F of the welding wire 21 and the welding electrode voltage V in the welding sections P102 to P103, the welding section P102. The welding bead width W becomes constant at P103.

In the second invention, as shown in FIG. 4, the constant weld bead width W in the welding sections P102 to P103 is adjusted to the same width as the welding sections P101 to P102 before the welding sections P102 to P103. Moreover, as shown to Fig.3 (a), the fixed welding bead width W in welding area P102-P104 is the following welding area P104-P105 or front welding area P101.
It is adjusted to the same width as the weld bead width of P102 and the subsequent welding sections P104 to P105.

As described above, according to the present invention, there is a risk that a welding defect due to an excessive welding current may occur due to a change in the base material heat capacity, such as when performing turn welding, and the welding bead width W needs to be constant. When welding the welding section, this can be done automatically without relying on manual welding. As a result, welding defects caused by excessive welding current can be suppressed, and welding work for keeping the welding bead width W constant can be performed with high work efficiency.

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

In the embodiment, a welding robot that performs arc welding work is assumed as the welding robot.

As shown in FIG. 1, the welding robot control apparatus according to the embodiment includes a welding robot 10 in which the axes 11 to 16 are driven so that a welding torch 17 moves along a welding line of a base material, and the welding robot 10. A welding power source device 20 for supplying a power to the welding wire 21 and applying a voltage V between the welding electrodes, a feeding speed F of the welding wire 21, a voltage V between the welding electrodes, and a moving speed S of the welding torch tip. And a controller 30 for controlling the above.

The welding robot 10 has an arm 10a, and a welding torch 17 is attached to the tip of the arm 10a. The welding robot 10 is provided with a welding wire feeding device 18. A welding wire delivery unit 90 is provided outside the welding robot 10. The welding wire 21 is accommodated in a reel shape in the welding wire delivery part 90. The welding wire feeder 18 feeds the welding wire 21 from the welding wire delivery unit 90 at a feed rate F corresponding to the wire feed rate command by driving the wire feed motor in accordance with the wire feed rate command, and the welding torch. 17 is fed to an electrode chip (not shown). The electrode tip and the base material constitute a welding electrode. A voltage V corresponding to the voltage command is applied between the welding electrodes. As a result, an arc discharge is generated between the tip of the welding wire 21 and the base material, and the joint of the base material is heated and melted by the heat generated by the arc discharge, and the welding wire 21 as a filler material is heated. After being melted, the welding wire 21 becomes a weld metal and the joint portion of the base material is joined.

The welding robot 10 is, for example, a 6-axis work robot having the axes 11, 12, 13, 14, 15, and 16 and includes a drive unit 19. The drive unit 19 includes a servo amplifier and a robot motor. The drive unit 19 is configured so that the axes 11, 12, 1
3, 14, 15, 16 are driven. By driving each of the axes 11, 12, 13, 14, 15, 16, the coordinate position P (X, X) of the tip 17a (tip of the welding wire 21) of the welding torch 17 on the robot coordinate system XYZ. Y, Z) and torch attitude angles (A, B, C) are changed. Note that the torch posture angles (A, B, C) are defined by Euler angles.

The welding power supply device 20 is a device that supplies electric power to the welding robot 10, and supplies the welding wire 21 to the wire feed motor of the welding wire feed device 18 by supplying a current corresponding to the wire feed speed command to the wire feed speed. While feeding to the welding torch 17 at a feed rate F according to the command,
A voltage V corresponding to the voltage command is applied between the welding electrodes.

  FIG. 2 shows the configuration of the controller 30 in a block diagram.

The controller 30 includes an input unit 31, a storage unit 32, a drive command calculation unit 33, and a feed speed command and voltage command calculation unit 34.

The input unit 31 includes a teaching operation panel 31a. When the teaching operation panel 31a is operated by an operator, a work program for the welding robot 10 is created. An example of the work program is shown in FIG.

  The storage unit 32 stores and stores a work program.

The drive command calculation unit 33 sets the target position P (X, Y, Z) of the tip 17a (tip of the welding wire 21) of the welding torch 17 of the welding robot 10 to each robot axis 11, 12, 13, 14, 15,
16 angles J1, J2, J3, J4, J5, J6 are converted into the respective shaft angles J1, J
A drive command for changing to 2, J3, J4, J5, and J6 is generated and output to the drive unit 19 of the welding robot 10. As will be described later, the drive command calculator 33 of the controller 30.
Then, the drive command is generated so that the moving speed S of the welding torch tip 17a of the welding robot 10 gradually changes in the welding section in which the base material heat capacity changes described in the work program.

The target position P (X, Y, Z) is obtained at a predetermined sampling interval Δt, and the target position P (X,
Each time Y, Z) is determined, the moving speed S is determined. When a drive command is output from the controller 30 to the drive unit 19 of the welding robot 10, the axes 11 to 16 of the welding robot 10 are driven. As a result, the welding torch tip 17a is moved along the weld line where the base material heat capacity on the base material to be welded changes.

The feed rate command and voltage command calculation unit 34 generates a wire feed rate command and a voltage command for the welding power source device 20 and outputs them to the welding power source device 20. As will be described later, in the feed rate command and voltage command calculation unit 34 of the controller 30, the feed rate F of the welding wire 21 is gradually changed in the welding section described in the work program and in which the base material heat capacity changes. , A feed speed command is generated, and the voltage V applied between the welding electrodes is
To change gradually in the welding section where the base material heat capacity changes as described in the work program,
A voltage command is generated.

FIG. 4 is a perspective view showing an example of work performed by the welding robot 10. FIG. 5 shows a feed speed F (current) of the welding wire 21 during welding work, a voltage V between welding electrodes, and a welding torch tip 17a.
The time chart shows how the moving speed S of the vehicle changes with time. FIG.
An example of the work program of the welding robot 10 is shown.

FIG. 4 shows a state in which the structure 60 of the T joint is manufactured by joining the plate members 61 and 62 by arc welding. The tip 17a of the welding torch 17 of the welding robot 10 starts from the standby point and sequentially moves to each point P101, P102, P103, P104 (retraction point). P101 to P103 correspond to weld lines. The joint between the plate member 61 and the plate member 62 is continuously fillet welded linearly along the welding sections P101 to P103. However, the standing plate 61 is low in the latter welding sections P102 to P103. For this reason, in the latter half welding sections P102 to P103, a change in the thickness of the base material occurs, and the base material heat capacity changes. Therefore, in order to prevent the base metal from being melted down by an excessive welding current in the welding sections P102 to P103 and the joint portion being undercut, the feed speed F of the welding wire 21 and the voltage V between the welding electrodes are gradually increased. Adjusted to decrease. Furthermore, the second half welding section P102 ~ P
In 103, the welding amount per unit time is kept the same as that of the first half welding sections P101 to P102, and the welding bead width W is kept the same constant width as the first half welding sections P101 to P102.
The tip moving speed S of the welding torch 17 is adjusted to be gradually reduced according to the decrease in the feed speed F of the welding wire 21 and the voltage V between the welding electrodes in the second half welding sections P102 to P103.

As shown in FIG. 6, the work program includes steps S1, S2, S3, S4, S5, and S.
6 and S7, and for each step, a “movement command” command, a “welding command” command,
Commands of “other instructions” are associated with each other.

“MOVL P101” in step S1 is “welding torch tip 17a of welding robot 10”.
"Move command" from the standby point to the welding line start point P101.

In step S2, “ARCON AC = 420 AV = 38.0 V = 30 TS = 0”
"At the start point P101, the feed speed F (current) is set to 420 instantaneously (slope time TS = 0).
A, the welding electrode voltage V is set to 38.0 V, and the torch tip moving speed S is set to 30 cm.
This is a “welding command” with the content of “set welding to / min and start welding”.
“MOVL P102” in step S3 is “welding torch tip 17a of welding robot 10”.
To the end point of the first half welding section P101 to P102 from the start point P101 of the weld line (second half start point)
“Move to P102” is a “move command”.

“ARCSET AC = 350 AV = 32.0 V = 25 TS = 5” in step S4
“5 s (slope time TS = 5 from the start point P102 of the second half welding sections P102 to P103)
s) The feed rate F (current) is gradually changed (decreased) to 350 A until the time has elapsed,
The welding electrode voltage V is gradually changed (decreased) to 32.0 V, and the torch tip moving speed S is set to 2
It is a “welding command” with the content of “weld by gradually changing (decreasing) to 5 cm / min”. Here, TS is a slope time, which is a time for gradually changing the feed speed F (current), the welding electrode voltage V, and the torch tip moving speed S from a specified value to a specified value. It is.

“MOVL P103” in step S5 is “welding torch tip 17a of welding robot 10”.
Is a “move command” whose content is “Move from the start point P102 to the end point P103 of the second half welding sections P102 to P103”.

“ARCOF AC = 350 AV = 32.0 T = 1.0” in step S6 is “at the current point P103, the feed speed F (current) is set to 350 A for 1.0 second (T = 1.0). In this state, and with the voltage V between the welding electrodes set to 32.0 V, the “other command” has the content “End welding”.

“MOVL P104” in step S7 is “welding torch tip 17a of welding robot 10”.
"Move command" with the content "Move the welding line from the end point P103 to the retreat point P104"
It is.

FIG. 7 is a flowchart showing a processing procedure performed by the controller 30. In the initial state, it is assumed that slope times TS = 0, Fe = 0, and Ve = 0 are set (step 101A).

The controller 30 takes out the instructions of the work program of FIG. 6 step by step (step 101), determines the type of the instruction (step 102), and moves to step 103 when the instruction type is a movement instruction. When the command type is a welding command, the process proceeds to step 104, and when the command type is another command, the process proceeds to step 105.

Since the first step S1 of the work program of FIG.
From the command content “MOVL P101”, the position “P101” is changed to the welding torch tip 17a.
Is taken out as the position Pe to be moved next, and the movement start position Ps and the movement end position Pe are set so that the welding torch tip 17a is moved from the current standby position (Ps) to the next movement position P101 (Pe). At the same time, the torch tip moving speed S is set to Se (step 103). Next, the process proceeds to step 106, where it is determined whether or not the type of the current command is a movement command (step 106). Since the type of the command in step S1 is a movement command (YES in step 106), the movement tor tip 17a completes the movement to the movement end position Pe after the movement time t is set to 0 (step 107). It is determined whether or not (step 108).

If the welding torch tip 17a has not completed the movement to the movement end position Pe (NO in Step 108), it is determined whether or not the slope time TS = 0 (Step 10).
9). In the initial state, since the slope time TS = 0 is set (YES in Step 109), the process proceeds to Step 116, where the welding wire feed speed F, the welding electrode voltage V, and the welding torch tip moving speed S are set. Initial state values Fe = 0, Ve = 0, and Se are set (step 116). Therefore, in the next step 114, the target position P after the sampling interval Δt when the welding torch tip 17a is moved from the current position at the moving speed Se is calculated. The target position P is obtained by interpolating the locus between the movement start position Ps (standby point) and the movement end position Pe (P101). Then, the obtained target position P (X,
Y, Z) are the angles J1, J2, J3 of the robot axes 11, 12, 13, 14, 15, 16
Converted to J4, J5, and J6, respectively, the shaft angles J1, J2, J3, J4, J5, J6
A drive command for changing to is generated and output to the drive unit 19 of the welding robot 10 (step 114). In the next step 115, a wire feed speed command for feeding the welding wire 21 at the feed speed F and a voltage command for applying the voltage V between the welding electrodes are generated.
In the initial state, since Fe = 0 and Ve = 0 are set (step 116), the wire feed speed command and the voltage command for the welding power source device 20 are turned off (step 115). ). Thereafter, the procedure returns to step 108 again, and the welding torch tip 17
a completes the movement to the movement end position Pe (P101) (YES at step 108).
The robot axes 11 to 16 are controlled so that the welding torch tip 17a is sequentially moved at the predetermined moving speed Se to the sequential target positions P at every sampling interval Δt (step 1).
14). Eventually, when the movement of the welding torch tip 17a to the movement end position Pe (P101) is completed (YES in Step 108), the process returns to Step 101, and the next command is fetched. In this manner, the welding torch tip 17a of the welding robot 10 moves from the standby point to the welding line start point P101.

Since the next step S2 of the work program is a welding command, in step 104,
From the command content “ARCON AC = 420 AV = 38.0 V = 30 TS = 0”, the current wire feed speed Fe, the current welding electrode voltage Ve, and the current welding torch tip moving speed S
e and slope time Ts are set to 420 A, 38.0 V, 30 cm / min, and 0 s, respectively (step 104).

Next, the routine proceeds to step 106, where it is determined whether or not the current command type is a movement command (step 106). However, since the current command type in step S2 is a welding command (determination NO in step 106). ), Returning to step 101 again, the next instruction is fetched.

Since the next step S3 of the work program is a movement command, the position “P102” is extracted from the command content “MOVL P102” in step 103 as the position Pe where the welding torch tip 17a is to be moved next, and welding is performed. The torch tip 17a is moved to the current position P101 (P
The movement start position Ps and the movement end position Pe are set so as to move from s) to the next movement position P102 (Pe), and the torch tip moving speed S is set to Se (step 103). Next, the process proceeds to step 106, where it is determined whether or not the type of the current command is a movement command (step 106). Since the type of the command in step S3 this time is a movement command (determination YES in step 106), after the movement time t is set to 0 (step 107), the welding torch tip 17a moves to the movement end position Pe. It is determined whether or not it is completed (step 1
08).

If the welding torch tip 17a has not completed the movement to the movement end position Pe (NO in Step 108), it is determined whether or not the slope time TS = 0 (Step 10).
9). Since the slope time TS = 0 is set at step 104 (YES at step 109), the process proceeds to step 116, where the welding wire feed speed F, the welding electrode voltage V, and the welding torch tip moving speed S are respectively Fe, Ve, and Se set in step 104 are set (step 116). For this reason, at the start point P101 of the welding line (slope time TS = 0), the feed rate F (current) is set to Fe (420A), and the voltage V between the welding electrodes is V.
e (38.0 V) is set, the torch tip moving speed S is set to Se (30 cm / min), and welding is started.

In the next step 114, the welding torch tip 17a is moved from the current position to the moving speed Se (30
The target position P after the sampling interval Δt when moving at cm / min) is calculated. The target position P is obtained by interpolating the locus between the movement start position Ps (P101) and the movement end position Pe (P102). Then, the obtained target position P (X,
Y, Z) are the angles J1, J2, J3 of the robot axes 11, 12, 13, 14, 15, 16
Converted to J4, J5, and J6, respectively, the shaft angles J1, J2, J3, J4, J5, J6
A drive command for changing to is generated and output to the drive unit 19 of the welding robot 10 (step 114). In the next step 115, a wire feed speed command for feeding the welding wire 21 at a feed speed Fe (420A) and a voltage command for applying the voltage Ve (38.0 V) between the welding electrodes are generated and output. (Step 115). Thereafter, the procedure returns to Step 108 again, and the welding torch tip 17a is moved at the moving speed Se (3) until the welding torch tip 17a completes the movement to the movement end position Pe (P102) (YES in Step 108).
Each axis of the robot is controlled so as to sequentially move to the target position P at every sampling interval Δt at 0 cm / min) (step 114). During this time, the feed rate Fe (42
0A), the welding wire 21 is fed, and the voltage Ve (38.0 V) is applied between the welding electrodes (step 115).

Eventually, when the movement of the welding torch tip 17a to the movement end position Pe (P102) is completed (determination YES in step 108), the process returns to step 101 and the next command is taken out. In this manner, the welding torch tip 17a of the welding robot 10 moves from the start point P101 of the first half welding section of the welding line to the end point P102 of the first half welding section, and welding is performed.

Since the next step S4 of the work program is a welding command, the command content “ARCSET AC = 350 AV = 32.0 V = 25 TS = 5” in step 104,
The current wire feed speed Fe, the current welding electrode voltage Ve, the current welding torch tip moving speed Se, and the slope time Ts are set to 350 A, 32.0 V, 25 cm / min, and 5 s, respectively. On the other hand, the previously set feed speed Fe (current) is set to Fs (420A),
The previously set welding electrode voltage Ve is set to Vs (38.0 V), and the previously set torch tip moving speed Se is set to Ss (30 cm / min) (step 104).

Next, the routine proceeds to step 106, where it is determined whether or not the current command type is a movement command (step 106), but since the current command type in step S4 is a welding command (determination NO in step 106). ), Returning to step 101 again, the next instruction is fetched.

Since the next step S5 of the work program is a movement command, the position “P103” is extracted from the command content “MOVL P103” in step 103 as the position Pe where the welding torch tip 17a is to be moved next, and welding is performed. The torch tip 17a is moved to the current position P102 (P
The movement start position Ps and the movement end position Pe are set so as to move from s) to the next movement position P103 (Pe), and the torch tip moving speed S is set to Se (step 103). Next, the process proceeds to step 106, where it is determined whether or not the type of the current command is a movement command (step 106). Since the type of the command in step S5 is a movement command (YES in step 106), after the movement time t is set to 0 (step 107), the welding torch tip 17a reaches the movement end position Pe (P103). It is determined whether or not the movement has been completed (step 108).

If the welding torch tip 17a has not completed the movement to the movement end position Pe (P103) (determination NO in step 108), it is determined whether TS = 0 (step 10).
9). Since the slope time TS is set to 5 in step 104 (determination YES in step 109), the process proceeds to step 110.

In the next step 110, it is determined whether or not the current travel time t is equal to or less than the slope TS (t ≦ TS) (step 110).

As long as it is determined that the current movement time t is equal to or less than the slope TS (t ≦ TS) (determination YES in step 110), the current wire feed speed Fe set in step 104 and the previously set wire feed Using the speed Fs and the slope time TS, the wire feed speed F for each successive movement time t when the wire feed speed Fe is gradually changed from the previous wire feed speed Fs during the slope time TS. Is obtained by the following equation.

F = Fs + (Fe−Fs) · t / TS (1)
In addition, the current welding electrode voltage Ve set in step 104, the previously set welding electrode voltage Vs, and the slope time TS are used to calculate the current welding electrode voltage Vs from the previous welding electrode voltage Vs during the slope time TS. When the voltage is gradually changed to the interelectrode voltage Ve, the welding electrode voltage V for each successive movement time t is obtained by the following equation.

V = Vs + (Ve-Vs) .t / TS (2) (Step 111)
Next, using the current welding torch tip movement Se set in step 104, the welding torch tip movement speed Ss set last time, and the slope time TS, between the slope times TS,
The welding torch tip moving speed S for each successive moving time t when the welding torch tip moving speed Ss is gradually changed from the previous welding torch tip moving speed Se to the current welding torch tip moving speed Se is obtained by the following equation.

S = Ss + (Se−Ss) · t / TS (3) (Step 112)
Next, the sampling time Δt is added to the current travel time t, and the next travel time t
(T = t + Δt) is obtained (step 113).

In the next step 114, the target position P after the sampling interval Δt when the welding torch tip 17a is moved from the current position at the movement speed S calculated in step 112 or the movement speed S set in step 116. Is calculated. The target position P is obtained by interpolating the locus between the movement start position Ps (P102) and the movement end position Pe (P103). The obtained target position P (X, Y, Z) is the robot axis 11, 1
Drive commands for changing to angles J1, J2, J3, J4, J5, and J6 are converted into angles J1, J2, J3, J4, J5, and J6 of 2, 13, 14, 15, and 16, respectively. It is produced | generated and it outputs to the drive part 19 of the welding robot 10 (step 114). In the next step 115, a wire feed speed command for feeding the welding wire 21 at the feed speed F calculated in step 111 or the feed speed F set in step 116 is generated and output s.
It is. Further, a voltage command for applying the voltage V calculated in step 111 or the voltage V set in step 116 between the welding electrodes is generated and output (step 115).

As long as the current movement time t is equal to or less than the slope TS (t ≦ TS) (YES at step 110), the welding torch tip 17a is sampled up to successive target positions P at the movement speed S sequentially calculated at step 112. Each axis 11 to 1 of the robot is moved sequentially at intervals Δt.
6 is controlled (step 114). During this time, the welding wire 21 is fed at the feed rate F sequentially calculated in step 111, and the voltage V sequentially calculated in step 111 is applied between the welding electrodes (step 115). In this way, the second half welding section P102
From the start point P102 of P103 to 5s (slope time TS = 5s),
The feed rate F (current) is gradually changed (decreased) from Fs (420A) to Fe (350A), and the welding electrode voltage V is gradually changed from Vs (38.0 V) to Ve (32.0 V) ( The torch tip moving speed S is changed from Ss (30 cm / min) to Se (25c).
m / min), welding is performed while gradually changing (decreasing).

If the current travel time t exceeds the slope TS (t> TS) (NO in Step 110), the process proceeds to Step 116, where F = Fe, V = Ve, and S = Se are set. The robot axes 11 to 16 are controlled such that the welding torch tip 17a is sequentially moved at the moving speed Ss set in step 116 to the sequential target positions P at every sampling interval Δt (step 114). During this time, the welding wire 21 is fed at the feed speed Fs set in step 116, and the voltage Ve set in step 116 is applied between the welding electrodes (step 115). In this way, the starting point P of the second half welding sections P102 to P103.
After 102 seconds, the feed speed F (current) is F after 5 seconds (slope time TS = 5 seconds).
e (350 A) is set, welding electrode voltage V is set to Ve (32.0 V), and torch tip moving speed S is set to Se (25 cm / min).

Eventually, when the movement of the welding torch tip 17a to the movement end position Pe (P103) is completed (determination YES in step 108), the process returns to step 101 and the next command is taken out.

Since the next step S6 of the work program is another command, step 105A
In step 105, the slope time TS = 0, Fe = 0, and Ve = 0 are set (step 105A). In step 105, the instruction content “ARCOF AC = 350 AV” is set.
= 32.0 T = 1.0 ”, that is,“ current position P103, 1.0
During the second (T = 1.0), the process of “ending the welding with the feed rate F (current) set to 350 A and the voltage V between the welding electrodes set to 32.0 V” is executed. (Step 1
05).

Next, the process proceeds to step 106, where it is determined whether or not the type of the current command is a movement command (step 106), but since the type of the command in step S6 is another command (determination in step 106). NO), returning to step 101 again, the next instruction is fetched.

Since the next step S7 of the work program is a movement command, the position “P104” is extracted from the command content “MOVL P104” in step 103 as the position Pe where the welding torch tip 17a is to be moved next, and welding is performed. The torch tip 17a is moved to the current position P103 (P
The movement start position Ps and movement end position Pe are set so as to move from s) to the next retracted position P104 (Pe), and the torch tip moving speed S is set to Se (step 103). Next, the process proceeds to step 106, where it is determined whether or not the type of the current command is a movement command (step 106). Since the type of the command in step S7 is a movement command (YES in step 106), after the movement time t is set to 0 (step 107), the welding torch tip 17a reaches the movement end position Pe (P104). It is determined whether or not the movement has been completed (step 108).

If the welding torch tip 17a has not completed the movement to the movement end position Pe (P104) (NO in Step 108), it is determined whether or not the slope time TS = 0 (Step 109). Since the initial state is restored and the slope time TS = 0 is set (YES in Step 109), the process proceeds to Step 116, where the welding wire feed speed F,
The welding electrode voltage V and the welding torch tip moving speed S are initial values Fe = 0, Ve = 0, Se.
(Step 116). Therefore, in the next step 114, the target position P after the sampling interval Δt when the welding torch tip 17a is moved from the current position at the moving speed Se is calculated. The target position P is a movement start position Ps (P103) and a movement end position P.
It is obtained by interpolating the locus between e (P104). The obtained target position P (X, Y, Z) is converted into angles J1, J2, J3, J4, J5, J6 of the robot axes 11, 12, 13, 14, 15, 16 respectively. Each axis angle J1, J2, J3,
A drive command for changing to J4, J5, and J6 is generated and output to the drive unit 19 of the welding robot 10 (step 114). In the next step 115, a wire feed speed command for feeding the welding wire 21 at the feed speed F and a voltage command for applying the voltage V between the welding electrodes are generated and output. Then, since Fe = 0 and Ve = 0 are set (step 116), the wire feed speed command and the voltage command for the welding power source apparatus 20 are turned off (step 115). Thereafter, the procedure returns to Step 108 again, and the welding torch tip 17a completes the movement to the movement end position Pe (P104) (Step 1).
The robot axes 11 to 16 are controlled so as to sequentially move the welding torch tip 17a to the sequential target positions P at each sampling interval Δt at a predetermined moving speed Se until the determination at 08 is YES (step 114). Eventually, the welding torch tip 17a moves to the movement end position Pe (P104).
(Step 108: YES), the process returns to Step 101 again.
The next instruction is fetched, but if the next instruction of the work program is the end, the process is terminated.

In this way, the welding torch tip 17a of the welding robot 10 moves from the end point P103 of the welding line to P104, which is a retreat point.

As described above, according to the first embodiment, since the feed rate F of the welding wire 21 and the voltage V between the welding electrodes are adjusted so as to gradually change (decrease), the base material is excessive in the welding sections P102 to P103. The occurrence of welding defects such as undercut and burn-out due to a large welding current is suppressed. Then, the tip moving speed S of the welding torch 17 is adjusted to gradually change (decrease) in accordance with the change (decrease) in the feed speed F of the welding wire 21 and the voltage V between the welding electrodes in the welding sections P102 to P103. Therefore, the weld bead width W is constant in the welding sections P102 to P103.

Thereby, according to this 1st Example, as shown in FIG. 4, welding area P102-P103.
A constant weld bead width W in the welding section P1 before the welding sections P102 to P103.
It is adjusted to the same width as 01 to P102.

(Second embodiment)
As shown in FIGS. 3A and 3B, the present invention is applied to the rotary welding of the member 41 having the edge portions 41a and 41b, and the welding sections P102 to P104 around the edge portion 41a, and the edge portion. Similarly, in the welding sections P105 to P107 around 41b, it is possible to similarly adjust the feed speed F, the welding electrode voltage V, and the welding torch tip moving speed S so as to gradually change. Here, the welding sections P102 to P104 and P105 to P107 are corner sections when rotating welding, and are welding sections in which the base material heat capacity changes.

FIGS. 3A and 3B show how the structure 40 is manufactured by joining the members 41 and 42 by arc welding. The member 41 has edge portions 41a and 41b. The member 41 and the plate member 42 are continuously fillet welded linearly along the linear welding sections P101 to P102, and then turned so as to turn 90 degrees at a point P103 corresponding to the edge portion 41a of the member 41. Welded. Further, after continuous fillet welding is performed linearly along the linear welding sections P104 to P105, the welding is performed by turning 90 degrees at a point P106 corresponding to the edge portion 41b of the member 41.

FIG. 8 shows how the feed rate F (current) of the welding wire 21 during the welding operation, the voltage V between the welding electrodes, and the moving speed S of the welding torch tip 17a change over time as in FIG. This is shown in the chart.

In the second embodiment, the controller 30 controls the welding robot 10 and the welding power source device 20 as in the first embodiment. For this reason, as shown in FIG.
When 7a reaches the point P102 before the edge part 41a, the point P before the edge part 41a
In the welding section from 102 to the point P103 corresponding to the edge portion 41a, the feed speed F of the welding wire 21 and the voltage V between the welding electrodes are adjusted so as to gradually decrease, and the welding wire in the welding sections P102 to P103 is adjusted. The tip moving speed S of the welding torch 17 is adjusted so as to gradually decrease in accordance with the decrease in the feed speed F of 21 and the voltage V between the welding electrodes. When the welding torch tip 17a reaches the point P103 corresponding to the edge portion 41a, the feed speed of the welding wire 21 in the welding section from the point P103 corresponding to the edge portion 41a to the point P104 after turning around the edge portion 41a. F and the welding electrode voltage V are adjusted so as to gradually increase, and the tip of the welding torch 17 is moved according to the feed rate F of the welding wire 21 and the welding electrode voltage V in the welding sections P103 to P104. The speed S is adjusted so as to gradually increase.

Furthermore, when the welding torch tip 17a reaches a point P105 in front of the edge portion 41b, the feed speed F of the welding wire 21 in the welding section from the point P105 in front of the edge portion 41a to the point P106 corresponding to the edge portion 41b. The voltage V between the welding electrodes is adjusted so as to gradually decrease, and the tip moving speed S of the welding torch 17 according to the decrease in the feed speed F of the welding wire 21 and the voltage V between the welding electrodes in the welding sections P105 to P106. Is adjusted to gradually decrease. And point P where welding torch tip 17a corresponds to edge part 41b
When 106 is reached, the feed speed F of the welding wire 21 and the voltage V between the welding electrodes gradually increase in the welding section from the point P106 corresponding to the edge portion 41b to the point P107 after turning around the edge portion 41b. In addition to the adjustment, the tip moving speed S of the welding torch 17 is adjusted to gradually increase according to the increase in the feed speed F of the welding wire 21 and the voltage V between the welding electrodes in the welding sections P106 to P107.

As described above, according to the second embodiment, the feed speed F of the welding wire 21 is the same as in the first embodiment.
And the voltage V between the welding electrodes is adjusted so as to gradually change (decrease and increase), so that the base material is in the welding sections P102 to P104 around the edge portion 41a or the welding sections P105 to P107 around the edge portion 41b. Occurrence of welding defects such as melting by excessive welding current is suppressed. And this welding section P102-P104 or P105
Because the tip moving speed S of the welding torch 17 is adjusted to gradually change (decrease and increase) according to changes (decrease and increase) in the feed speed F of the welding wire 21 and the welding electrode voltage V in P107. The welding bead width W is constant in the welding sections P102 to P104 around the edge portion 41a or the welding sections P105 to P107 around the edge portion 41b.

As a result, according to the second embodiment, as shown in FIG. 3A, the constant weld bead width W in the welding sections P102 to P104 around the edge portion 41a is equal to the welding section P102.
To the same width as the welding sections P101 to P102 before P104, and to the same width as the welding sections P104 to P105 after the welding sections P102 to P104 around the edge portion 41a. Similarly, the constant welding bead width W in the welding sections P105 to P107 around the edge portion 41b is the welding sections P104 to P1 before the welding sections P105 to P107.
Is adjusted to the same width as 05, and the welding sections P105 to P10 around the edge portion 41b.
7 is adjusted to the same width as the subsequent welding section P107.

As described above, according to the present embodiment, there is a possibility that a welding defect due to an excessive welding current may occur due to a change in the base material heat capacity, such as when rotating welding, and the welding bead width W needs to be constant. When welding the welding section, this can be done automatically without relying on manual welding. As a result, welding defects caused by excessive welding current can be suppressed, and welding work for keeping the welding bead width W constant can be performed with high work efficiency.

FIG. 1 is a diagram illustrating a control apparatus for a welding robot that is common to the related art and the embodiment. FIG. 2 is a diagram illustrating a control block diagram of the embodiment. FIG. 3A is a diagram showing that the welding bead width is obtained in the same manner as manual welding when performing turn welding by the control of the present embodiment, and FIG. 3B is the tip of the welding arc of the present embodiment. FIG. FIG. 4 is a perspective view showing an example of work performed by the welding robot. FIG. 5 is a diagram for explaining the first embodiment, and is a time chart showing how the feed rate (current) of the welding wire during welding work, the voltage between the welding electrodes, and the moving speed of the welding torch tip change with time. It is the figure shown by. FIG. 6 is a diagram showing an example of a work program for the welding robot. FIG. 7 is a flowchart showing a procedure of processing performed by the controller. FIG. 8 is a diagram for explaining the second embodiment, and is a time chart showing how the feed rate (current) of the welding wire during welding work, the voltage between welding electrodes, and the moving speed of the welding torch tip change over time. It is the figure shown by. FIG. 9 is a diagram illustrating a technique applied to conventional arc welding.

Explanation of symbols

10 welding robot, 17 welding torch, 20 welding power supply, 21 welding wire, 3
0 controller

Claims (2)

A welding robot in which each axis is driven so that the welding torch moves along the welding line of the base metal, and a welding power source that supplies electric power to the welding robot to feed the welding wire and applies a voltage between the welding electrodes A welding robot control device comprising a device and a controller for controlling a welding wire feed rate, a voltage between welding electrodes, and a moving speed of a welding torch tip,
The controller is
In order to prevent welding defects due to excessive welding current in the welding section where the base metal heat capacity changes, the welding wire feed rate and the voltage between the welding electrodes are gradually changed in the welding section,
Control is performed to gradually change the welding torch tip moving speed in accordance with changes in the welding wire feed speed and welding electrode voltage in the welding section so that the welding bead width is constant in the welding section. Control device for welding robot. 2. The welding robot according to claim 1, wherein the constant welding bead width in the welding section is the same as the welding bead width of the preceding welding section, the subsequent welding section, or the preceding and following welding sections of the welding section. Control device.

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