JP6354702B2 - Arc welding system and arc welding method - Google Patents

Description

  The disclosed embodiments relate to an arc welding system and an arc welding method.

  Conventionally, when arc welding is performed along a line (hereinafter referred to as a “welding line”) where a plurality of base materials are in contact with a workpiece to be welded, an arc welding system that moves the welding wire along the welding line while performing a weaving operation. It has been known. Here, the weaving operation refers to an operation of reciprocating the welding wire with a predetermined amplitude across the welding line.

  Further, in the arc welding with the weaving operation described above, a technique for correcting the deviation of the welding locus from the weld line based on a change in the welding current accompanying the weaving operation has been proposed (for example, see Patent Document 1).

JP 2012-240064 A

  However, when performing arc welding while repeating the operation of moving the welding wire forward and backward with respect to the workpiece, the change in the welding current is not linked to the weaving operation, so the deviation from the welding line is detected based on the change in the welding current. It is not possible.

  Specifically, when the weaving operation is repeated while moving the welding wire forward and backward, the distance between the workpiece and the welding wire constantly changes. Therefore, the center line of the weaving operation (the point where the amplitude is zero) is connected from the current change. This is because it is difficult to find the (line).

  An object of one embodiment is to provide an arc welding system and an arc welding method capable of favorably correcting a deviation of a welding locus from a weld line.

An arc welding system according to an aspect of an embodiment includes a welding power source having constant voltage characteristics, a voltage detection unit, a feeding unit, an articulated robot, an operation control unit, a determination unit, and a correction unit. . A voltage detection part detects the voltage between the welding wire which is a consumable electrode, and the workpiece | work which is welding object. The feeding unit repeats the operation of moving the welding wire forward and backward with respect to the workpiece. The articulated robot is provided with a feeding unit. The motion control unit causes the articulated robot to perform an operation of moving the workpiece along the trajectory while reciprocating at a predetermined amplitude across the predetermined trajectory. The determination unit determines whether or not the trajectory has deviated from a predetermined welding line based on the voltage detected by the voltage detection unit. The correction unit corrects the track when the determination unit determines that the track has deviated from the weld line.

  According to one aspect of the embodiment, it is possible to provide an arc welding system and an arc welding method that can favorably correct a deviation of a welding locus from a weld line.

FIG. 1 is a diagram showing an outline of an arc welding method. FIG. 2 is a diagram illustrating an overall configuration of the arc welding system. FIG. 3 is a block diagram of the arc welding apparatus. FIG. 4 is a block diagram of a control unit and a storage unit in the arc welding apparatus. FIG. 5 is a block diagram of the robot controller. FIG. 6 is a diagram illustrating a relationship between a workpiece and a weaving operation when there is no track deviation with respect to the weld line. FIG. 7 is a diagram showing the relationship between the weaving operation and the welding voltage when there is no track deviation with respect to the weld line. FIG. 8 is a diagram showing the relationship between the workpiece and the weaving operation when there is a track deviation with respect to the weld line. FIG. 9 is a diagram showing the relationship between the weaving operation and the welding voltage when there is a track deviation with respect to the weld line. FIG. 10 is a flowchart (part 1) illustrating a processing procedure executed by the robot controller. FIG. 11 is a flowchart (part 2) illustrating a processing procedure executed by the robot controller.

  Hereinafter, embodiments of an arc welding system and an arc welding method disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

  In the embodiments described below, expressions such as “parallel”, “equivalent”, “same”, and “symmetric” may be used, but it is not necessary to strictly satisfy these conditions. That is, each expression described above allows for deviations in manufacturing accuracy, installation accuracy, processing accuracy, detection accuracy, and the like.

  First, the outline | summary of the arc welding method which concerns on embodiment is demonstrated using FIG. FIG. 1 is a diagram showing an outline of an arc welding method. The workpiece W shown in FIG. 1 is welded along, for example, a weld line 100 where two plate-shaped base materials are in contact. Here, FIG. 1 also shows an enlarged view of the workpiece W as viewed from the negative direction of the Y axis toward the positive direction. In addition, although the following description demonstrates the case where this welding line 100 is a straight line, the welding line 100 may be a curve or the combination of a straight line and a curve.

  In the present embodiment, welding is performed from the side where the two base materials are in contact with an acute angle. 1 includes a Z-axis having a positive direction from the workpiece W toward the welding wire 200 so as to divide the acute angle into two equal parts, and a Y-axis parallel to the welding line 100 and having a welding direction as a positive direction. It shows a three-dimensional orthogonal coordinate system. Such an orthogonal coordinate system may be shown in other drawings used in the following description. Note that a weaving operation described later is performed on a plane parallel to the XY plane.

  As shown in FIG. 1, the welding torch 13 causes the welding wire 200 to protrude toward the workpiece W side. The welding wire 200 is used as a so-called consumable electrode that is melted and consumed by an electric current applied between the welding wire 200 and the workpiece W.

  The welding torch 13 moves along the track 110 corresponding to the welding line 100 described above. Here, the welding torch 13 performs a weaving operation that reciprocates in a direction parallel to the X axis shown in the figure while moving along the track 110. For this reason, the movement along the trajectory 110 and the weaving operation are combined, and the welding torch 13 takes the sine curve-shaped weaving locus 111 shown in FIG. Note that a welding trace formed along the weaving locus 111 corresponds to a welding locus.

  Further, in the arc welding method according to the present embodiment, the operation of moving the welding wire 200 forward with respect to the workpiece W (the operation of moving the welding wire 200 forward in the negative direction of the Z axis in FIG. 1) and the operation of moving backward (retracting in the positive direction of the Z axis). Repeat the operation. Thereby, in the arc welding which concerns on this embodiment, the short circuit state which the welding wire 200 and the workpiece | work W short-circuit, and the arc state which generate | occur | produces an arc between both are repeatedly generated.

  In the following description, the operation of moving the welding wire 200 forward and the operation of moving the welding wire 200 together may be referred to as “advance / retreat operation”. In FIG. 1, the direction of the advance / retreat operation is shown as an advance / retreat direction 112 indicated by a double arrow.

  By the way, when the workpiece W having the shape shown in the enlarged view of FIG. 1 is arc-welded while performing a weaving operation, it is preferable that the track 110 is located at a position from the welding line 100 in the positive direction of the Z-axis.

  However, when an error occurs in the relative position with respect to the X axis between the welding torch 13 and the workpiece W, the track 110 is deviated from such an ideal track. In addition, the enlarged view of FIG. 1 shows a case where the track 110 of the welding torch 13 is displaced in the positive direction of the X axis from the welding line 100 for reference.

  Here, if welding is performed without the forward / backward movement of the welding wire 200, the change in the distance between the welding wire 200 and the workpiece W is determined by the shape of the concave portion of the workpiece W as shown in FIG. . For this reason, in such a case, the track 110 is corrected in accordance with a change in the welding current applied between the welding wire 200 and the workpiece W.

  However, as described above, when arc welding is performed by the advance / retreat operation of the welding wire 200, the welding current constantly changes with the advance / retreat operation. For this reason, it is difficult to correct the track 110 based on the welding current.

  Therefore, in the arc welding method according to the present embodiment, it is determined whether or not there is a deviation between the welding line 100 and the track 110 based on the voltage between the welding wire 200 and the workpiece W (hereinafter referred to as “welding voltage”). I decided to judge. When it is determined that there is a difference between the two, the correction is performed so that the track 110 approaches the weld line 100.

  In particular, when current control is performed using a welding power source having a constant voltage characteristic, a change in the welding voltage is not used to determine the deviation between the welding line 100 and the track 110 because the voltage change associated with arc welding is small. It wasn't. However, when performing arc welding with the advance / retreat operation of the welding wire 200, it has been found that the change in the welding voltage is large. Therefore, in the arc welding method according to the present embodiment, determination of deviation based on the welding voltage, It was decided to make corrections.

  Thus, according to the arc welding method according to the present embodiment, the deviation of the track 110 from the weld line 100 can be corrected well. In addition, further specific contents of the arc welding method according to the present embodiment will be described together with the following description of the arc welding system.

  Next, the overall configuration of the arc welding system according to the present embodiment will be described with reference to FIG. FIG. 2 is a diagram showing an overall configuration of the arc welding system 1. As shown in FIG. 2, the arc welding system 1 includes an articulated robot 10, a robot controller 20, and an arc welding apparatus 30.

  In the figure, a work W to be welded, a wire storage unit 201 for supplying the welding wire 200 to the articulated robot 10, and a gas cylinder 202 for supplying a shielding gas used for arc welding are shown together. . Moreover, in the same figure, only the component used for description of the arc welding system 1 is shown, and description about a general component is abbreviate | omitted.

  First, the configuration of the articulated robot 10 will be described. The articulated robot 10 includes a robot arm 11, a joint part 12, a welding torch 13, and a feeding part 14. The multi-joint robot 10 is a multi-joint robot having a plurality of robot arms 11 and joints 12 to which robot arms 11 are respectively connected via joints 12. A welding torch 13 is attached to the robot arm 11 on the distal end side, and the robot arm 11 on the proximal end side is fixed to the grounding surface via a base or the like.

  The joint unit 12 is equipped with an actuator such as a servo motor and a speed reducer that decelerates the rotation of the actuator, and the position and posture of the robot arm 11 are changed by driving the actuator based on a command from the robot controller 20. To perform the operation.

  That is, the articulated robot 10 changes the position and posture of the welding torch 13 based on a command from the robot controller 20. Thereby, the articulated robot 10 causes the welding torch 13 to perform a weaving operation along the trajectory 110 (see the weaving trajectory 111 in FIG. 1).

  The welding torch 13 has a through hole through which the welding wire 200 fed through the feeding unit 14 passes, and causes the welding wire 200 to protrude from the opening at the tip. Further, the welding torch 13 provides the welding wire 200 with electric power supplied from the arc welding device 30 via a contact tip (not shown) that abuts the welding wire 200.

  The feeding unit 14 performs an operation of feeding the welding wire 200 to the welding torch 13 side and an operation of drawing from the welding torch 13 side based on a command from the arc welding apparatus 30. Thereby, the feeding unit 14 moves the welding wire 200 forward and backward (refer to the forward / backward direction 112 in FIG. 1). In the following, the operation of feeding the welding wire 200 to the welding torch 13 side may be referred to as “forward feeding”, and the operation of drawing it from the welding torch 13 side may be referred to as “reverse feeding”.

  Next, the structure of the arc welding apparatus 30 is demonstrated using FIG. 3 and FIG. FIG. 3 is a block diagram of the arc welding apparatus 30.

  As shown in FIG. 3, the arc welding apparatus 30 includes a primary rectifier circuit 30a, a switching circuit 30b, a transformer 30c, a secondary rectifier circuit 30d, and a reactor 30e. Further, the arc welding apparatus 30 includes a control unit 31, a storage unit 32, a voltage detection unit 33, and a current detection unit 34. The arc welding apparatus 30 supplies power for welding to the welding torch 13 and the workpiece W.

  In addition, the control part 31 and the memory | storage part 32 can be comprised using a computer or a storage device similarly to the control part 21 and the memory | storage part 22 of the robot controller 20 mentioned later.

  In FIG. 3, for easy understanding of the connection relationship with the arc welding apparatus 30, a commercial power supply 40 that supplies AC power to the arc welding apparatus 30, the robot controller 20, the welding torch 13, and a feeding unit 14, welding wire 200, and workpiece W are shown together.

  The primary rectifier circuit 30 a is connected to the commercial power source 40 and rectifies AC power supplied from the commercial power source 40. Then, the primary rectifier circuit 30a supplies the rectified power to the switching circuit 30b.

  The switching circuit 30b performs PWM (Pulse Width Modulation) control on the power supplied from the primary rectifier circuit 30a, and generates an arbitrary current waveform and an arbitrary voltage waveform. Then, the switching circuit 30b outputs the generated current waveform or voltage waveform to the transformer 30c.

  The transformer 30c transforms the power supplied from the switching circuit 30b and outputs the transformed power to the secondary rectifier circuit 30d. The secondary rectifier circuit 30d rectifies the supply power output from the transformer 30c. One of the two output terminals of the secondary rectifier circuit 30d is connected to the work W.

  Reactor 30e is connected to the other of the two output terminals of secondary rectifier circuit 30d, and smoothes the supply power rectified by secondary rectifier circuit 30d. A welding torch 13 is connected to the downstream side of the reactor 30e.

  The control unit 31 performs overall control of the arc welding apparatus 30 while communicating with the robot controller 20 and controls the feeding speed of the feeding unit 14. The specific contents of the control unit 31 will be described later with reference to FIG. The storage unit 32 is, for example, a nonvolatile memory, and stores information used by the control unit 31. The specific contents stored in the storage unit 32 will be described later with reference to FIG.

  The voltage detector 33 is connected to each of the two output terminals of the secondary rectifier circuit 30d, and detects a voltage between the welding torch 13 and the workpiece W (hereinafter referred to as “welding voltage”). The voltage detection unit 33 outputs the detection result to the control unit 31.

  The current detector 34 is connected to the downstream side of the reactor 30 e and detects a current between the welding torch 13 and the workpiece W (hereinafter referred to as “welding current”). The current detection unit 34 outputs the detection result to the control unit 31.

  Next, details of the control unit 31 and the storage unit 32 in the arc welding apparatus 30 will be described with reference to FIG. FIG. 4 is a block diagram of the control unit 31 and the storage unit 32 in the arc welding apparatus 30.

  As shown in FIG. 4, the control unit 31 includes a detection unit 31a, an instruction unit 31b, a feed adjustment unit 31c, and a power adjustment unit 31d. The storage unit 32 stores feed speed information 32a and welding information 32b. In FIG. 4, the robot controller 20, the feeding unit 14, the voltage detection unit 33, the current detection unit 34, and the switching circuit 30 b are combined for easy understanding of the connection relationship with the control unit 31. It shows.

  The detection unit 31a detects whether the welding wire 200 and the workpiece W are in a short circuit state or an arc state. Specifically, the detection unit 31a detects a short circuit state when the voltage value detected by the voltage detection unit 33 is equal to or less than a predetermined value, and detects an arc state while the voltage value is larger than the predetermined value. And the detection part 31a outputs a detection result to the instruction | indication part 31b.

  The instruction unit 31b instructs the feeding adjustment unit 31c to adjust the feeding state of the welding wire 200 based on the detection result of the detection unit 31a. Specifically, the instruction unit 31b instructs the feed adjustment unit 31c to forward the welding wire 200 when the detection unit 31a detects an arc state. On the other hand, the instruction unit 31b instructs the feeding adjustment unit 31c to reversely feed the welding wire 200 when the detection unit 31a detects a short-circuit state.

  Further, the instruction unit 31b instructs the power adjustment unit 31d to adjust the power between the welding wire 200 and the workpiece W based on the detection result of the detection unit 31a. Specifically, the instruction unit 31b instructs the power adjustment unit 31d to gradually increase the welding current when the detection unit 31a detects a short circuit state. On the other hand, when the detection unit 31a detects the arc state, the instruction unit 31b instructs the power adjustment unit 31d to gradually decrease the welding current having the maximum current value over a predetermined period.

  The feeding adjustment unit 31c adjusts the feeding direction and the feeding speed of the feeding unit 14 based on the feeding speed information 32a in the storage unit 32 and the instruction from the instruction unit 31b. Here, the feeding speed information 32a is information that predetermines, for example, changes with time in the feeding speed for normal feeding and the feeding speed for reverse feeding. The forward feeding speed may be a constant speed, or the reverse feeding speed may be a constant speed.

  When instructed to forward the welding wire 200 from the instruction unit 31b, the feeding adjustment unit 31c sends a feeding speed instruction based on information on the feeding speed in the feeding speed information 32a. To the unit 14. On the other hand, when instructed to reversely feed the welding wire 200 from the instructing unit 31b, the feed adjusting unit 31c issues a feed rate instruction based on information on the reverse feed rate in the feed rate information 32a. Output to the feeding unit 14.

  The power adjustment unit 31d adjusts the current and voltage between the welding wire 200 and the workpiece W based on the welding information 32b in the storage unit 32 and the instruction from the instruction unit 31b. Here, the welding information 32b is information including various parameters in which a profile of current change or voltage change is determined in advance. The power adjustment unit 31d outputs the generated current adjustment signal and voltage adjustment signal to the switching circuit 30b. At this time, the power adjustment unit 31d can output a signal for keeping the voltage at a constant voltage to the switching circuit 30b.

  Next, the configuration of the robot controller 20 will be described with reference to FIG. FIG. 5 is a block diagram of the robot controller 20. As shown in FIG. 5, the robot controller 20 includes a control unit 21 and a storage unit 22.

  The control unit 21 includes an operation control unit 21a, a determination unit 21b, and a correction unit 21c, and the storage unit 22 stores teaching information 22a. In FIG. 5, the articulated robot 10 and the arc welding apparatus 30 are shown together for easy understanding of the connection relationship with the robot controller 20.

  Here, the robot controller 20 includes, for example, a computer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a hard disk drive (HDD), and an input / output port, and various circuits. Including.

  The CPU of the computer functions as the operation control unit 21a, the determination unit 21b, and the correction unit 21c of the control unit 21, for example, by reading and executing a program stored in the ROM.

  Further, at least one or all of the operation control unit 21a, the determination unit 21b, and the correction unit 21c may be configured by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

  The storage unit 22 corresponds to, for example, a RAM or an HDD. The RAM and HDD can store the teaching information 22a. Note that the robot controller 20 may acquire the above-described program and various information via another computer or a portable recording medium connected via a wired or wireless network.

  The control unit 21 performs overall control of the robot controller 20 and operation control of the articulated robot 10. In the present embodiment, the case where the arc welding apparatus 30 performs control of the feeding unit 14 has been described. However, the robot controller 20 may perform control of the feeding unit 14. That is, the feeding adjustment unit 31 c of the arc welding apparatus 30 may be provided in the control unit 21 of the robot controller 20.

  The operation control unit 21 a controls the operation of the articulated robot 10 based on the teaching information 22 a stored in the storage unit 22. Specifically, the motion control unit 21 a causes the multi-joint robot 10 to move the welding torch 13 (see FIG. 2) attached to the multi-joint robot 10 while moving the welding torch 13 along the welding line 100. Instructs arc welding to be performed.

  Here, the teaching information 22 a is information including a “job” that is a program that is created at the stage of teaching the operation to the articulated robot 10 and that defines the operation path of the articulated robot 10. The operation control unit 21a moves the welding torch 13 by operating the articulated robot 10 based on the teaching information 22a, and executes arc welding.

  The determination unit 21b determines that the track 110 (see FIG. 1) of the welding torch 13 is the weld line 100 (see FIG. 1) based on the operation status of the weaving operation received from the operation control unit 21a and the detection result of the voltage detection unit 33. It is determined whether or not the deviation has occurred.

  Specifically, the determination unit 21b shifts the track 110 to the low voltage side of the right side (X-axis positive direction) and the left side (X-axis negative direction) of the track 110 in the weaving operation along the track 110. It is determined that The details of the determination process performed by the determination unit 21b will be described later with reference to FIGS.

  When the determination unit 21b determines that the track 110 (see FIG. 1) of the welding torch 13 has deviated from the welding line 100 (see FIG. 1), the correction unit 21c returns the track 110 to the direction opposite to the shifted direction. The operation control unit 21a is instructed as described above.

  Specifically, the correction unit 21c determines that the trajectory 110 is shifted to the lower voltage side, and thus corrects the correction unit 21c to return the trajectory 110 to the higher voltage side. For example, as shown in FIG. 1, when the track 110 is shifted to the right side (X-axis positive direction) of the welding line 100, the correction unit 21c returns the track 110 to the left side (X-axis negative direction). To the operation control unit 21a.

  Here, the correction unit 21c performs correction of the trajectory 110 by a predetermined correction amount. Note that by appropriately determining the magnitude of the correction amount, it is possible to prevent a situation where the trajectory 110 is excessively corrected by the correction and undulates. That is, the correction of the trajectory 110 can be performed smoothly by correcting the trajectory 110 by a predetermined correction amount.

  Next, details of the determination process performed by the determination unit 21b will be described with reference to FIGS. Hereinafter, the case where there is no deviation of the track 110 with respect to the weld line 100 will be described with reference to FIGS. 6 and 7, and the case where there is a deviation between them will be described with reference to FIGS. 8 and 9.

  First, the case where there is no shift of the track 110 with respect to the weld line 100 will be described with reference to FIGS. FIG. 6 is a diagram illustrating the relationship between the workpiece W and the weaving operation when there is no deviation of the track 110 with respect to the weld line 100. FIG. 7 is a diagram showing the relationship between the weaving operation and the welding voltage when there is no deviation of the track 110 with respect to the welding line 100.

  As shown in FIG. 6, it is assumed that the welding torch 13 performs a weaving operation with an amplitude A on a plane parallel to the XY plane. In this case, the center C of the weaving operation exists on a straight line from the welding line 100 in the positive direction of the Z axis.

  The center C corresponds to the trajectory 110. Moreover, in the same figure, while showing the right end R and the left end L of a weaving operation | movement, the position of the welding torch 13 in each end is shown with the broken line. Further, as already described with reference to FIG. 1, the welding wire 200 protruding from the welding torch 13 advances and retreats along the advance / retreat direction 112 with respect to the workpiece W.

  Thus, when there is no shift of the track 110 with respect to the weld line 100, the distance between the welding torch 13 and the workpiece W is the same at the right end R and the left end L. For this reason, as shown in FIG. 7, the minimum peak value 71 of the welding voltage on the right end R side in the weaving operation and the minimum peak value 72 of the welding voltage on the left end L side are the same value.

  Specifically, as shown in FIG. 7, the welding voltage takes a maximum peak value at timings t0, t1, t2, t3, and t4 when the welding torch 13 passes through the center C. This is because the distance between the welding torch 13 and the workpiece W is the maximum at the center C as shown in FIG.

  On the other hand, as shown in FIG. 7, when the welding torch 13 passes the right end R and the left end L, the welding voltage takes the minimum peak value. There is no difference between the minimum peak value 71 corresponding to the right end R and the minimum peak value 72 corresponding to the left end L.

  As shown in FIG. 6, since the shape of the workpiece W is symmetric with respect to the line connecting the center C and the welding line 100, when the center C is located at the center of the recess of the workpiece W, the welding torch This is because the distance between 13 and the workpiece W is the smallest and the same at the right end R and the left end L.

  Here, as shown in FIG. 6, the welding wire 200 repeats the advancing / retreating operation with respect to the workpiece W. For this reason, the actual welding voltage changes along the welding voltage fluctuation curve shown in FIG. 7 while repeating the fine fluctuations. However, in FIG. 7, such fine fluctuations are omitted for easy understanding. ing. Further, FIG. 7 illustrates a case where the change with time of the position of the welding torch 13 is a so-called sine curve shape, but it may be an arbitrary shape.

  Next, the case where the track 110 is displaced with respect to the weld line 100 will be described with reference to FIGS. FIG. 8 is a diagram illustrating the relationship between the workpiece W and the weaving operation when there is a shift of the track 110 with respect to the weld line 100. FIG. 9 is a diagram showing the relationship between the weaving operation and the welding voltage when there is a shift of the track 110 with respect to the welding line 100. 8 and 9 show the case where the track 110 is displaced in the positive direction of the X axis from the weld line 100. The position of the center C in FIGS. 6 and 7 is set as an intermediate position 100a for reference. Show.

  As shown in FIG. 8, when the track 110 is displaced in the positive direction of the X axis from the welding line 100, the distance between the welding torch 13 and the workpiece W is smaller at the right end R than at the left end L. For this reason, as shown in FIG. 9, the minimum peak value 91 of the welding voltage on the right end R side is smaller than the minimum peak value 92 of the welding voltage on the left end L side.

  Therefore, the determination unit 21b (see FIG. 5) of the robot controller 20 compares the minimum peak value 91 on the right end R side with the minimum peak value 92 on the left end L side in the weaving operation, and performs welding based on the comparison result. It was decided whether or not the line 100 and the trajectory 110 were shifted.

  For example, as shown in FIG. 9, when the difference d between the minimum peak value 91 and the minimum peak value 92 is larger than a predetermined threshold value, the determination unit 21b is displaced from the weld line 100 and the track 110. Is determined. The determination unit 21b determines that the trajectory 110 is shifted to the smaller of the minimum peak value 91 and the minimum peak value 92.

  For example, as shown in FIG. 9, when the minimum peak value 92 is larger than the minimum peak value 91, it is determined that the trajectory 110 is shifted to the right end R side in the weaving operation. Conversely, when the minimum peak value 91 is larger than the minimum peak value 92, it is determined that the trajectory 110 is shifted to the left end L side in the weaving operation.

  Note that the determination unit 21b may perform determination using a ratio between the minimum peak value 91 and the minimum peak value 92. For example, when the absolute value of a value obtained by subtracting 1 from the minimum peak value 91 divided by the minimum peak value 92 is larger than a predetermined threshold value, the determination unit 21b determines that the weld line 100 and the track 110 are Judge that it is shifted.

  When the value obtained by dividing the minimum peak value 91 by the minimum peak value 92 is larger than 1, the determination unit 21b determines that the trajectory 110 is shifted to the left end L side in the weaving operation, and is smaller than 1. In this case, it is determined that the trajectory 110 is shifted to the right end R side.

  By the way, the case where the determination part 21b determined the shift | offset | difference of the welding line 100 and the track | orbit 110 based on the comparison with the minimum peak value 91 and the minimum peak value 92 was demonstrated so far. However, the present invention is not limited to this, and the determination unit 21b may perform the determination based on a comparison between the integrated value of the welding voltage on the right end R side and the integrated value of the welding voltage on the left end L side in the weaving operation.

  Specifically, as illustrated in FIG. 9, the determination unit 21 b compares the integrated value 93 of the welding voltage on the right end R side with the integrated value 94 of the welding voltage on the left end L side in the weaving operation. When the difference between the integrated value 93 and the integrated value 94 is larger than a predetermined threshold value, the determination unit 21b determines that the weld line 100 and the track 110 are shifted. Then, the determination unit 21b determines that the trajectory 110 is shifted to the smaller of the integrated value 93 and the integrated value 94.

  In the case shown in FIG. 9, since the integrated value 93 is smaller than the integrated value 94, the determination unit 21b determines that the trajectory 110 is shifted to the right end R side. Conversely, when the integrated value 93 is larger than the integrated value 94, the determination unit 21b determines that the trajectory 110 is shifted to the left end L side.

  As described above, the determination unit 21b determines that the trajectory 110 is shifted to the lower voltage side of the voltage on the right end R side and the voltage on the left end L side in the weaving operation. And the correction | amendment part 21c correct | amends so that the track | orbit 110 may be returned to the side with a high voltage. Here, the expression “the voltage is high” includes the meaning of “the minimum peak value of the welding voltage is high”, “the integrated value of the welding voltage is high”, or “the welding voltage at the corresponding timing is high”. .

  The correction unit 21c may perform the correction every time it receives a notification that there is a deviation of the trajectory 110 from the determination unit 21b, or when it receives a notification that it has shifted to the same side for a predetermined number of times. Corrections may be performed. For example, the correction unit 21c performs the correction when the notification that the trajectory 110 has shifted to the right end R side is received twice from the determination unit 21b. By doing so, the trajectory 110 can be corrected while suppressing the influence of noise and the like.

  Next, a processing procedure executed by the robot controller 20 shown in FIG. 5 will be described with reference to FIGS. 10 and 11. FIG. 10 is a flowchart (part 1) showing a processing procedure executed by the robot controller 20, and FIG. 11 is a flowchart (part 2) showing a processing procedure executed by the robot controller 20.

  In addition, in FIG. 10, when the determination part 21b determines based on the minimum peak value of a welding voltage, in FIG. 11, about the case where the determination part 21b determines based on the integrated value of a welding voltage, respectively. explain.

  First, the case where the determination part 21b determines based on the minimum peak value of a welding voltage is demonstrated. As illustrated in FIG. 10, the determination unit 21b determines whether or not the difference between adjacent minimum peak values is greater than a threshold value (step S101). When the difference is larger than the threshold (Yes in step S101), the determination unit 21b notifies the correction unit 21c including which of the right end R side and the left end L side is larger in the weaving operation.

  Receiving the notification, the correction unit 21c corrects the trajectory 110 of the welding torch 13 to the side having the smallest minimum peak value (either the right end R side or the left end L side) (step S102), and ends the process.

  Here, the correction unit 21c corrects the trajectory 110 by a predetermined correction value. If the determination condition in step S101 is not satisfied (No in step S101), the process ends without performing the process in step S102. As already described with reference to FIG. 9, the determination unit 21 b may compare the ratio between the minimum peak values with a threshold value.

  Next, the case where the determination part 21b determines based on the integrated value of a welding voltage is demonstrated. As shown in FIG. 11, the determination unit 21b calculates the integrated value of the welding voltage on each side of the center C (each on the right end R side and the left end L side) in the weaving operation (step S201).

  Subsequently, the determination unit 21b determines whether or not the difference between the integrated values is greater than a threshold value (step S202). When the difference is larger than the threshold value (Yes at Step S202), the determination unit 21b notifies the correction unit 21c including which of the right end R side and the left end L side is larger in the weaving operation.

  Receiving the notification, the correction unit 21c corrects the trajectory 110 of the welding torch 13 to the side with the larger integrated value (either the right end R side or the left end L side) (step S203), and ends the process.

  Here, the correction unit 21c corrects the trajectory 110 by a predetermined correction value. If the determination condition in step S202 is not satisfied (No in step S202), the process ends without performing the process in step S203. Further, as already described with reference to FIG. 9, the determination unit 21b may compare the ratio between the integrated values with a threshold value.

  As described above, the arc welding system 1 according to the present embodiment includes the voltage detection unit 33, the feeding unit 14, the articulated robot 10, the operation control unit 21a, the determination unit 21b, and the correction unit 21c. Is provided. The voltage detection unit 33 detects a voltage between the welding wire 200 that is a consumable electrode and the workpiece W that is a welding target. The feeding unit 14 repeats an operation (advance / retreat operation) for moving the welding wire 200 forward and backward relative to the workpiece W.

  Further, the articulated robot 10 is provided with a feeding unit 14. The operation control unit 21a performs many operations for moving the welding wire 200 fed from the feeding unit 14 with respect to the workpiece W along the track 110 while reciprocating at a predetermined amplitude A across the predetermined track 110. Let the joint robot 10 perform this. The determination unit 21 b determines whether or not the track 110 has deviated from the predetermined welding line 100 based on the voltage detected by the voltage detection unit 33. The correction unit 21c corrects the track 110 when the determination unit 21b determines that the track 110 has shifted from the weld line 100.

  Therefore, according to the arc welding system 1 according to the present embodiment, even when arc welding is performed while performing the advance / retreat operation and the weaving operation of the welding wire 200, the deviation of the track 110 from the weld line 100 is corrected well. can do.

  In the above-described embodiment, the case where the welding torch 13 is moved relative to the workpiece W has been described. However, it is sufficient to move the welding torch 13 relative to the workpiece W. For example, the workpiece W may be moved by operating a device such as a positioner that holds the workpiece W, or both the welding torch 13 and the workpiece W may be moved.

  Moreover, although embodiment mentioned above demonstrated the case where the correction | amendment part 21c correct | amends the track | orbit 110 according to the determination result by the determination part 21b, it is good also as omitting the correction | amendment part 21c. That is, instead of correcting the trajectory 110, error notification may be performed or welding may be stopped.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

DESCRIPTION OF SYMBOLS 1 Arc welding system 10 Articulated robot 11 Robot arm 12 Joint part 13 Welding torch 14 Feeding part 20 Robot controller 21 Control part 21a Operation control part 21b Judgment part 21c Correction part 22 Memory | storage part 22a Teaching information 30 Arc welding apparatus 30a Primary rectification Circuit 30b Switching circuit 30c Transformer 30d Secondary rectifier circuit 30e Reactor 31 Control unit 31a Detection unit 31b Instruction unit 31c Feeding adjustment unit 31d Power adjustment unit 32 Storage unit 32a Feeding speed information 32b Welding information 33 Voltage detection unit 34 Current detection Part 40 Commercial power supply 100 Welding line 110 Orbit 111 Weaving locus 200 Welding wire 201 Wire storage part 202 Gas cylinder W Workpiece C Center R Right end L Left end

Claims (6)

A welding power source having constant voltage characteristics;
A voltage detection unit that detects a voltage between a welding wire that is a consumable electrode and a workpiece that is a welding target;
A feeding section that repeats the operation of moving the welding wire forward and backward with respect to the workpiece;
An articulated robot provided with the feeding section;
Operation control for causing the articulated robot to perform an operation of moving the welding wire fed from the feeding unit with respect to the workpiece along the trajectory while reciprocating at a predetermined amplitude across a predetermined trajectory. And
A determination unit that determines whether or not the trajectory has deviated from a predetermined weld line based on the voltage detected by the voltage detection unit;
An arc welding system comprising: a correction unit that corrects the track when the determination unit determines that the track has deviated from the weld line. The determination unit
The determination as to whether or not the trajectory has deviated from the weld line is made based on a comparison result between adjacent minimum peak values in the change with time of the voltage detected by the voltage detection unit. Arc welding system. The determination unit
The track based on a comparison result between an integrated value of the voltage in a section where the welding wire is positioned on one side of the track and an integrated value of the voltage in a section positioned on the other side in the operation of reciprocating the welding wire. 2. The arc welding system according to claim 1, wherein it is determined whether or not is deviated from the weld line. The correction unit is
4. The arc welding system according to claim 1, wherein correction is performed to shift the track to a side where the voltage detected by the voltage detection unit is higher on both sides of the track. The correction unit is
5. The arc welding system according to claim 4, wherein when performing correction for shifting the track, the track is shifted by a predetermined correction amount. 6. Using a welding power source with constant voltage characteristics,
A moving step of moving the welding wire fed while repeating forward and backward movements relative to the workpiece along the trajectory while reciprocating at a predetermined amplitude across the predetermined trajectory;
A determination step of determining whether or not the track has deviated from a predetermined welding line based on a voltage between the welding wire and the workpiece;
An arc welding method comprising: a correction step of correcting the track when it is determined in the determination step that the track has deviated from the weld line.

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