Interference avoidance method for welding equipment and control device for welding equipment

Abstract

The present invention includes: a reference parallel line generation process, generating a pair of parallel lines, wherein the pair of parallel lines are located on an extended plane of a workpiece cross section and are tangent to the outer edge of the workpiece cross section without passing through the workpiece cross section; a first judgment process, comparing the width of the pair of parallel lines generated in the reference parallel line generation process with the maximum separation threshold of the welding electrode to determine whether the maximum separation threshold is greater than the width of the parallel lines; and a pulling direction determination process, wherein when the maximum separation threshold is greater than the width of the parallel lines in the first judgment process, the direction of the parallel lines is determined as the pulling direction.

Description

Technical Field

[0001] The present invention relates to an interference avoidance method and a control device for welding equipment, and in particular to an interference avoidance method and a control device for welding equipment that calculate an entry path and a retraction path for the welding equipment to accurately reach a welding point without interfering with a workpiece, wherein the welding equipment is provided with a multi-joint robot including a welding gun unit. Background Art

[0002] In the past, if a welding device equipped with a multi-joint robot installed on a production line is directly operated to teach the working posture, an operator who is familiar with the operation of the multi-joint robot must be present at the production line to perform the operation, which accordingly makes the operation inefficient. In addition, since the operation needs to be performed while the production line is stopped, the operation rate of the production line is also reduced.

[0003] Therefore, in order to achieve the efficiency of the above teaching or to improve the operation rate of the above production line, offline teaching (offline teaching) has been carried out recently. That is, a model of a multi-joint robot, a workpiece as a working object, and surrounding structures is constructed on a computer, and after the teaching data is generated using the model, if the teaching data is provided to the multi-joint robot on site, the production line does not need to be stopped during the generation of the teaching data.

[0004] In addition, in the working path of a multi-joint robot, especially in the case of offline teaching of a pulling path that does not interfere with the workpiece when the welding gun unit is pulled out from the welding point, the following interference avoidance method for a multi-joint robot is known: the interior of the welding gun unit is filled with a grid-shaped entity, and the overlapping part of the entity and the workpiece is extracted as a workpiece model and interference judgment is performed, so that the process of determining the pulling path is automated, and teaching data can be generated in a short time without the need for skill (for example, refer to Japanese Patent Gazette No. 3715537).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 3715537 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] In the conventional interference avoidance method of welding equipment, the overlapping portion between the solid and the workpiece is used as the workpiece model, so the gap between the welding electrode and the workpiece is ensured to be larger than necessary, and sometimes the welding equipment is judged to be unable to retreat from the welding point even if it is actually possible.

[0010] The object of the present invention is to provide an interference avoidance method and control device for a multi-joint robot, which can more appropriately automate the process of determining the path in the working path of the multi-joint robot, especially when performing offline teaching of a pulling path that does not interfere with a workpiece when pulling a welding gun unit from a welding point, and can generate more appropriate teaching data in a short time without the need for proficiency.

[0011] Means used to solve problems

[0012] [1] In order to achieve the above-mentioned object, the present invention provides a method for avoiding interference of welding equipment, which avoids interference between the welding electrodes and the workpiece when the welding equipment having a pair of welding electrodes is pulled out from the workpiece, and is characterized in that:

[0013] The workpiece cross section is composed of a plane, the plane including: an electrode straight line connecting the ends of a pair of welding electrodes separated from each other; and a pulling straight line intersecting the electrode straight line and extending in a direction in which the welding device is pulled out from the workpiece, and the interference avoidance method of the welding device includes:

[0014] A reference parallel line generating step, generating a pair of parallel lines, the pair of parallel lines are located on an extended plane of the workpiece cross section, are tangent to the outer edge of the workpiece cross section but do not pass through the workpiece cross section;

[0015] a first determination step of comparing the widths of the pair of parallel lines generated in the reference parallel line generation step with a maximum separation threshold of the welding electrodes to determine whether the maximum separation threshold is greater than the widths of the parallel lines; and

[0016] A pulling direction determining step, when the maximum separation threshold is greater than the width of the parallel lines in the first judging step, determining the direction of the parallel lines as the pulling direction.

[0017] According to the interference avoidance method of the welding equipment of the present invention, the parallel lines are set in a manner that is tangent to the outer edge of the workpiece cross section but does not pass through the workpiece cross section. Therefore, with the workpiece cross section as a reference, a pair of parallel lines that are tangent to the outer edge of the above-mentioned workpiece cross section and are located on the extended plane of the workpiece cross section are generated, and the width of the parallel lines is compared with the maximum separation threshold of the welding electrode to determine whether the maximum separation threshold is larger. Therefore, when the maximum separation threshold is larger, the direction of the reference parallel line can be determined as the pulling direction, and an efficient pulling direction determination operation of the welding equipment from the workpiece can be provided.

[0018] Furthermore, since the parallel lines are set to be tangent to the outer edge of the workpiece cross section and not to pass through the workpiece cross section, the gap between the welding electrode and the workpiece can be set more appropriately than in the conventional case where the overlapping portion of a grid-like solid and the workpiece is used as the workpiece model.

[0019] [2] In addition, in the present invention, it is preferred that:

[0020] The area including the entire cross section of the workpiece is used as an interference avoidance area to avoid the intrusion of the welding electrode of the welding equipment during the pulling movement.

[0021] When it is determined in the first judgment process that the maximum separation threshold is not greater than the width of the parallel line, the interference avoidance area is divided, and for each interference avoidance area after division, the parallel line tangent to the outer edge of the workpiece cross section is regenerated through the reference parallel line generation process, and then the first judgment process is performed.

[0022] According to the present invention, an interference avoidance region is set, the interference avoidance region is divided, and parallel lines are set for each of the divided interference avoidance regions. Therefore, even if the interference avoidance region is not divided and the direction of the parallel lines is changed, the maximum separation threshold is not greater than the width of the parallel lines, and the interference avoidance region can be divided, and parallel lines can be appropriately set for each of the divided interference avoidance regions, and the welding electrode can be appropriately retracted from the workpiece.

[0023] [3] In addition, in the present invention, it is preferred that:

[0024] The area including the entire cross section of the workpiece is used as an interference avoidance area to avoid the intrusion of the welding electrode of the welding equipment during the pulling movement.

[0025] When it is determined in the first determination step that the maximum separation threshold is not greater than the width of the parallel lines, the directions of the parallel lines are changed, and the reference parallel line generation step is restarted in the interference avoidance region.

[0026] According to the present invention, even when it is determined in the first determination step that the maximum separation threshold is not larger than the width of the parallel lines, it is possible to set appropriate parallel lines by changing the directions of the parallel lines and performing the determination again.

[0027] [4] In addition, in the present invention, it is preferred that:

[0028] A second determination step is provided in which it is determined whether an outer edge of a portion of the welding device other than the welding electrode interferes with the workpiece cross section during an operation of pulling the welding electrode out from the workpiece cross section.

[0029] According to the present invention, it is possible to prevent the outer edges of parts of the welding equipment other than the welding electrodes of the multi-joint robot or the like from interfering with the cross section of the workpiece.

[0030] [5] In addition, the control device of the welding equipment of the present invention is characterized in that when the welding equipment having a pair of welding electrodes is pulled out from the workpiece, the welding electrodes are prevented from interfering with the workpiece,

[0031] The workpiece cross section is composed of a plane, the plane including: an electrode straight line connecting the ends of a pair of welding electrodes separated from each other; and a pulling straight line intersecting the electrode straight line and extending in a direction in which the welding device is pulled out from the workpiece, and the control device of the welding device includes:

[0032] A reference parallel line generating step, generating a pair of parallel lines, the pair of parallel lines are located on an extended plane of the workpiece cross section, are tangent to the outer edge of the workpiece cross section but do not pass through the workpiece cross section;

[0033] a first determination step of comparing the widths of the pair of parallel lines generated in the reference parallel line generation step with a maximum separation threshold of the welding electrodes to determine whether the maximum separation threshold is greater than the widths of the parallel lines; and

[0034] A pulling direction determining step, when the maximum separation threshold is greater than the width of the parallel lines in the first judging step, determining the direction of the parallel lines as the pulling direction.

[0035] According to the control device of the welding equipment of the present invention, the parallel lines are set in a manner tangent to the outer edge of the workpiece cross section. Therefore, based on the workpiece cross section formed by the direction of connecting the welding electrodes and the pulling direction, a pair of parallel lines tangent to the workpiece cross section and located on the extended plane of the workpiece cross section are generated, and the width of the reference parallel lines and the maximum separation threshold of the welding electrodes are compared to determine whether the maximum separation threshold is larger. Thus, in the case where the maximum separation threshold is larger, the direction of the reference parallel lines can be determined as the pulling direction, and an efficient pulling direction determination operation of the welding equipment from the workpiece can be provided.

[0036] Furthermore, since the parallel lines are set to be tangent to the outer edge of the workpiece cross section and not to pass through the workpiece cross section, the gap between the welding electrode and the workpiece can be set more appropriately than in the conventional case where the overlapping portion of a grid-like solid and the workpiece is used as the workpiece model.

[0037] [6] In addition, in the present invention, it is preferred that:

[0038] The area including the entire cross section of the workpiece is used as an interference avoidance area to avoid the intrusion of the welding electrode of the welding equipment during the pulling movement.

[0039] When it is determined in the first judgment process that the maximum separation threshold is not greater than the width of the parallel line, the interference avoidance area is divided, and for each interference avoidance area after division, the parallel line tangent to the outer edge of the workpiece cross section is regenerated through the reference parallel line generation process, and then the first judgment process is performed.

[0040] According to the present invention, an interference avoidance region is set, the interference avoidance region is divided, and parallel lines are set for each of the divided interference avoidance regions. Therefore, even if the direction of the parallel lines is changed without dividing the interference avoidance region, the maximum separation threshold is not greater than the width of the parallel lines, and the interference avoidance region can be divided, and parallel lines can be appropriately set for each of the divided interference avoidance regions, and the welding electrode can be appropriately retracted from the workpiece.

[0041] [7] In addition, in the present invention, it is preferred that:

[0042] The area including the entire cross section of the workpiece is used as an interference avoidance area to avoid the intrusion of the welding electrode of the welding equipment during the pulling movement.

[0043] When it is determined in the first determination step that the maximum separation threshold is not greater than the width of the parallel lines, the directions of the parallel lines are changed, and the reference parallel line generation step is restarted in the interference avoidance region.

[0044] According to the present invention, even when it is determined in the first determination step that the maximum separation threshold is not larger than the width of the parallel lines, appropriate parallel lines can be set by changing the directions of the parallel lines and performing the determination again.

[0045] [8] In addition, in the present invention, it is preferred that:

[0046] A second determination step is provided in which, when the welding electrode is pulled out from the workpiece cross section, it is determined whether an outer edge of a portion of the welding device other than the welding electrode interferes with the workpiece cross section.

[0047] According to the present invention, it is possible to prevent the outer edges of parts of the welding equipment other than the welding electrodes of the multi-joint robot or the like from interfering with the cross section of the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a diagram showing the configuration of an off-line teaching device and a robot device used in an embodiment of a welding electrode interference avoidance method and a welding electrode control device of the present invention.

[0049] Figure 2This is a block diagram showing a circuit configuration of a control unit in an off-line teaching device.

[0050] Figure 3 This is an explanatory diagram showing the structure of a multi-joint robot.

[0051] Figure 4 This is an explanatory diagram showing a welding gun unit.

[0052] Figure 5 This is an explanatory diagram showing an X-type welding gun.

[0053] Figure 6 This is a flowchart showing an embodiment of a welding electrode interference avoidance method and a welding electrode control device according to the present invention.

[0054] Figure 7 : is a flowchart showing the first determination step of this embodiment.

[0055] Figure 8 : is a flowchart showing the process of dividing the interference avoidance area according to the present embodiment.

[0056] Fig. 9 : is a flowchart showing the second determination step of this embodiment.

[0057] Fig.10 It is an explanatory diagram showing parallel lines and the maximum opening degree which serves as a reference for the maximum separation threshold.

[0058] Fig.11 It is an explanatory diagram showing a first dividing plane and a second dividing plane.

[0059] Fig.12 It is an explanatory diagram showing a state in which the second divided surface is further divided.

[0060] Fig.13 This is an explanatory diagram showing a state where the welding gun unit is pulled out from a workpiece cross section divided into a plurality of parts. DETAILED DESCRIPTION

[0061] Embodiments of an interference avoiding method for welding equipment and a control device for welding equipment according to the present invention will be described with reference to the drawings.

[0062] Figure 1 The diagram shows an off-line teaching device 10 used in the present embodiment and a robot device 12 that performs a desired operation on an object to be operated based on teaching data generated by the off-line teaching device 10 .

[0063] The off-line teaching device 10 includes a control unit 14 , a monitor 16 , a keyboard 18 for issuing input and output instructions to the control unit 14 , and a mouse 20 . The off-line teaching device 10 teaches the motion of the multi-joint robot 50 .

[0064] The robot device 12 includes a multi-joint robot 50 as welding equipment and a robot control unit 22 that performs motion control of the multi-joint robot 50 based on the teaching data.

[0065] like Figure 3 and Figure 4 As shown, the multi-joint robot 50 is composed of a first base 54 as a mounting platform, a second base 56, a first link 58, a second link 60 and a third link 62, and a cylindrical welding gun loading and unloading portion 64, and the welding gun unit 52 is connected to the welding gun loading and unloading portion 64.

[0066] Furthermore, the first base 54 and the second base 56 are connected by an axis J1 that rotates around the vertical axis L0. The second base 56 and the base end of the first link 58 are connected by an axis J2 that rotates in a vertical plane, the end of the first link 58 and the base end of the second link 60 are connected by an axis J3 that rotates in a vertical plane, and the end of the second link 60 and the base end of the third link 62 are connected by an axis J4 that rotates in a vertical plane. The end of the third link 62 is connected to the welding gun mounting and dismounting portion 64 by an axis J5 that rotates around the central axis L of the third link 62.

[0067] The welding gun unit 52 connected to the welding gun attachment portion 64 is a so-called C-type welding gun, and includes a pair of electrodes 70 and 72 that are opened and closed along the central axis L. The electrodes 70 and 72 are in contact with a workpiece 80 at a welding operation point (hereinafter referred to as TCP (Tool Center Point)) on the central axis L in a closed state.

[0068] The direction from the TCP that coincides with the axis of the electrode 72 on the main body side is defined as the electrode vector Zr (the welding gun unit reference vector), and the direction perpendicular to the electrode vector Zr and directed to the opposite side of the arm 74 is defined as the arm vector Xr. In addition, the direction perpendicular to the arm vector Xr and the electrode vector Zr is defined as the transverse vector Yr (refer to Figure 4 ).

[0069] The driving mechanisms of axes J1, J2, J3, J4 and J5 and the opening and closing mechanisms of electrodes 70 and 72 are respectively driven by actuators not shown in the figure, and TCP is determined by the rotation angle θ1 of axis J1, the rotation angle θ2 of axis J2, the rotation angle θ3 of axis J3, the rotation angle θ4 of axis J4, the rotation angle θ5 of axis J5 and the dimensions of each part of the multi-joint robot 50.

[0070] In the present embodiment, the articulated robot 50 is described as a 5-axis robot, but a robot with 6 or more axes may also be applied. The axes mentioned here include not only rotational motion but also telescopic motion or translation motion.

[0071] In addition, the welding gun unit 52 is not limited to a C-type welding gun, and may be, for example, Figure 5 An X-type welding gun (a welding gun having a pair of opening and closing gun arms pivotally supported on a common support shaft) 52a is shown.

[0072] like Figure 2 As shown, the control unit 14 constituting the off-line teaching device 10 includes: a CPU 26 for overall control of the off-line teaching device 10; a ROM 28 as a non-volatile storage unit; a RAM 29 as a volatile storage unit; a hard disk drive (HDD) 34; a drawing control circuit 30 for drawing control on the screen of the monitor 16; an interface circuit 32 for connecting the keyboard 18 and the mouse 20; a recording medium drive 36 for controlling an external recording medium 36a; a data generation circuit 38 for generating teaching data; and a simulation circuit 40 for performing simulation on the screen of the monitor 16 based on the teaching data. The simulation circuit 40 has a function of generating the above-mentioned model based on the three-dimensional CAD or investigating the interference (contact, etc.) between the models.

[0073] Next, the interference avoiding method of the multi-joint robot according to the present embodiment will be described.

[0074] In the present embodiment, three main methods are used to determine the path for pulling the welding gun unit 52 out of the welding portion of the workpiece 80 .

[0075] The first method is to move directly from the welding position to the pulling point; the second method is to move from the welding position to the center of gravity of the workpiece 80; the third method is to extract only the portion of the workpiece 80 close to the opening of the welding gun unit 52 and preferentially determine the pulling path for the extracted portion.

[0076] In addition, although a projection model is used for the workpiece 80, since a pair of parallel lines tangent to the outer edge (vertex) of the workpiece 80 are used to avoid interference, the processing speed can be increased.

[0077] In the present embodiment, the articulated robot 50 , the workpiece 80 , and the peripheral structures thereof are treated as virtual models in the off-line teaching device 10 , but are denoted by the same reference numerals as those of actual devices in the following description.

[0078] First, in Figure 6 In step S101 , the welding gun unit 52 of the multi-joint robot 50 is set at the position of the welding work point Pn of the welding workpiece 80 .

[0079] The welding work point Pn (n represents the order of postures taken by the multi-joint robot 50. The same applies below) is composed of a total of 6 coordinate values, namely, 3 coordinate values ​​in each direction of height (H), width (W), and depth (D) representing the position in space, the arm vector Xr, the horizontal vector Yr, and the electrode vector Zr.

[0080] Furthermore, since the welding work point P0 is the initial position, it is written into a path table which is a table indicating the order of postures taken by the multi-joint robot 50 and initialized.

[0081] The path table is composed of a column of "direction of welding gun unit", a column of "position of TCP", and a column of "posture of multi-joint robot". The column of "posture of multi-joint robot" is composed of rotation angles θ1 to θ5.

[0082] The path table is recorded in the RAM 29 or the HDD 34 , but may be displayed on the screen of the monitor 16 or printed as necessary.

[0083] Then, in Figure 6 In step S102, a cross section 80a of the welding gun unit 52 and the workpiece 80 is obtained, and the TCP of the welding gun unit 52 located at the welding operation point P0 is set as the investigation start position Ps. The workpiece cross section 80a is defined as a cross section obtained by cutting with a plane, and the plane includes: an electrode straight line L70 connecting the ends of a pair of welding electrodes 70 and 72 separated from each other; and a pulling straight line L50 intersecting the electrode straight line L70 and extending in the direction of pulling the welding gun unit 52 and the multi-joint robot 50 as welding equipment from the workpiece 80.

[0084] Next, in step S103, a pair of parallel lines L1 and L2 are set, and the width between the parallel lines L1 and L2 (the distance in the direction perpendicular to the parallel lines L1 and L2) is calculated. In addition, the value obtained by subtracting the minimum gap required when the welding electrodes 70 and 72 are pulled out from the workpiece 80 from the distance between the ends of the welding electrodes 70 and 72 when the distance between the ends of the welding electrodes 70 and 72 is expanded to the maximum is stored as the maximum separation threshold.

[0085] Next, in step S104 , it is determined whether the width of the parallel lines L1 and L2 is smaller than the maximum separation threshold.

[0086] When the width of the parallel lines L1 and L2 is smaller than the maximum separation threshold value (YES in S104 ), the process proceeds to step S105 , and a retraction teaching point is generated.

[0087] Then, in step S106, a process of confirming whether the arm of the multi-joint robot 50 interferes with the workpiece 80, etc. is executed, and this process is terminated. In confirming the interference of the multi-joint robot 50, the posture of the multi-joint robot 50, that is, the rotation angles θ1 to θ5, is obtained based on the position and posture of the welding gun unit 52 specified by the pull-out position. This calculation method can apply a known matrix calculation method (hereinafter referred to as inverse calculation) based on the position coordinates (H, W, D) of the pull-out position in space, the arm vector Xr, the horizontal vector Yr, and the electrode vector Zr indicating the posture of the welding gun unit 52, and the dimensions of each part of the multi-joint robot 50.

[0088] Thus, in the present embodiment, the workpiece 80 is not judged by a block model using a grid-like entity, but a projection model of the workpiece 80 is used, so that the gap between the ends of the welding electrodes 70 and 72 and the workpiece 80 can be managed more appropriately than before. In addition, since the interference avoidance judgment of the welding electrodes 70 and 72 is judged using a pair of parallel lines L1 and L2, the processing becomes easy, similar to the judgment using the block model in the past.

[0089] In step S104 , when the width of the parallel lines L1 , L2 is not less than the maximum separation threshold, the process branches to step S107 , and the “rotation and shift concession path search process” is executed.

[0090] Then, the process proceeds to step S108. When a retreat path, i.e., an interference avoidance path, is found, the process returns to step S105 to create a retreat teaching point. In addition, in the present embodiment, the retreat is described, but the same can also be applied when the welding gun unit 52 is moved to the welding operation point without interfering with the workpiece 80.

[0091] In step S108 , if no retreat path, ie, interference avoidance path, is found, the process proceeds to step S109 , notifying that the welding gun unit 52 cannot retreat from the workpiece 80 , and the current process ends.

[0092] In the following steps S8 to S12, if Fig.13 As shown, when the linear motion is performed from the investigation start position Ps to the pull-out position (investigation end position) Pe, whether or not there is interference is investigated.

[0093] Figure 7 Yes means Figure 6 Flowchart of “rotation and shifting concession path search processing” of step S107.

[0094] First, in step S110, the workpiece 80 or the welding gun unit 52 is rotated by a predetermined angle (for example, ±5 degrees) with the welding operation point as the center. Then, in step S111, it is determined whether the multi-joint robot 50 can cope with the rotation to the set rotation angle in S110, and whether the welding gun unit 52 and the multi-joint robot 50 will not interfere with the workpiece 80.

[0095] When the rotation is possible and there is no interference, the process proceeds to step S112 to determine whether the maximum separation threshold is greater than the width of the parallel lines L1 and L2.

[0096] When the maximum separation threshold is not greater than the width of the parallel lines L1 , L2 , the process returns to step S110 , and the workpiece 80 or the welding gun unit 52 is further rotated.

[0097] When the maximum separation threshold is greater than the width of the parallel lines L1 and L2 in step S112 , the process proceeds to step S113 to generate a retraction teaching point.

[0098] Then, the process proceeds to step S114 , and it is determined whether the welding gun unit 52 and the multi-joint robot 50 will not interfere with the workpiece 80 when the welding gun unit 52 is moved through the evacuation teaching point.

[0099] Then, the process proceeds to step S115, where the welding gun unit 52 and the workpiece 80 are rotated a plurality of times, and when there are a plurality of retracting paths, the time required for movement on each retracting path is compared.

[0100] Then, the process proceeds to step S116, in which the escape path with the shortest travel time is selected from among the escape paths, and the current processing ends.

[0101] In step S114, when interference occurs during the movement of the retraction teaching point, the process branches to step S117, reports the occurrence of interference, and ends the current processing.

[0102] In step S111, when the workpiece 80 and the welding gun unit 52 cannot be rotated, or when the workpiece 80 and the welding gun unit 52 are rotated, interference with the workpiece 80 will occur, the process branches to step S118, and after executing the "retreat path search process through continuous rotation", it returns to step S114, and when the welding gun unit 52 is moved through the retreat teaching point, it is determined whether the welding gun unit 52 and the multi-joint robot 50 will not interfere with the workpiece 80.

[0103] Figure 8 Yes means Figure 7 Flowchart of “evacuation path search process by continuous rotation” of step S118 of FIG.

[0104] In the "continuous rotation retreat path search process", first, in step S120, an interference avoidance area is set. Fig.10 The interference avoidance region is set to be located between the parallel lines L1 and L2 and include all vertices of the workpiece 80 (for example, as a rectangular space). In addition, as long as the interference avoidance region is between the parallel lines L1 and L2 and is an area including all vertices of the workpiece cross section 80a, it is not limited to a rectangular space.

[0105] Then, if Fig.11 As shown, the interference avoidance region is divided into two, a first dividing plane and a second dividing plane, along the pulling direction.

[0106] Then, enter step S121, rotate the welding gun unit 52 and the workpiece section 80a on the first dividing plane, set parallel lines L1 and L2, and search whether there is a path with a maximum separation threshold greater than the width of the parallel lines L1 and L2 and capable of pulling the welding gun unit 52 from the workpiece 80.

[0107] Next, the process proceeds to step S122 , and it is determined whether there is a retreat path, that is, a retreat path that allows the welding gun unit 52 to be pulled out from the workpiece 80 , on the first divided plane.

[0108] When there is an escape path, proceed to step S123, rotate the welding gun unit 52 and the workpiece section 80a on the second dividing plane, set parallel lines L1 and L2, and search whether there is a path in which the maximum separation threshold is greater than the width of the parallel lines L1 and L2 and the welding gun unit 52 can be pulled out from the workpiece 80.

[0109] Next, the process proceeds to step S124 , where it is determined whether there is a retreat path, that is, a retreat path that allows the welding gun unit 52 to be pulled out from the workpiece 80 , on the second divided plane.

[0110] If there is an escape path, the current processing ends.

[0111] In step S122, if there is no escape path on the first dividing surface, the process branches to step S126 to determine whether the first dividing surface is large enough to set multiple teaching points. If the first dividing surface is not large enough to set multiple teaching points, the process ends immediately.

[0112] In step S126, when the first dividing surface is large enough to set multiple teaching points, the process proceeds to step S125, where the first dividing surface is further divided into two, and the process returns to step S121. According to each further divided area, the welding gun unit 52 and the workpiece cross section 80a are rotated, and parallel lines L1 and L2 are set to search whether there is a path in which the maximum separation threshold is greater than the width of the parallel lines L1 and L2 and the welding gun unit 52 can be pulled out from the workpiece 80.

[0113] In step S124, if there is no escape path on the second divided surface, the process branches to step S128 to determine whether the second divided surface is large enough to set multiple teaching points. If the second divided surface is not large enough to set multiple teaching points, the process ends immediately.

[0114] In step S128, when the second dividing surface is large enough to set multiple teaching points, the process proceeds to step S127, where the second dividing surface is further divided into two, and the process returns to step S123. According to each further divided area, the welding gun unit 52 and the workpiece cross section 80a are rotated, and parallel lines L1 and L2 are set to search whether there is a path in which the maximum separation threshold is greater than the width of the parallel lines L1 and L2 and the welding gun unit 52 can be pulled out from the workpiece 80.

[0115] Fig. 9 Yes means Figure 6 This is a flowchart of the “gun arm interference check process” of step S106.

[0116] First, in step S130 , the welding gun unit 52 is placed at the teaching point.

[0117] Then, the process proceeds to step S131 to confirm whether the arm of the multi-joint robot 50 will interfere with the workpiece 80 .

[0118] Then, when the multi-joint robot 50 may interfere with the workpiece 80 or other components, the process proceeds to step S132 to calculate the retraction direction and distance of the multi-joint robot 50 .

[0119] Then, the process proceeds to step S133, in which the multi-joint robot 50 is parallel-displaced or rotated to generate a retraction point.

[0120] Then, the process proceeds to step S134 to determine whether the interference has been eliminated.

[0121] If the interference is eliminated, the process proceeds to step S135 to move the welding gun unit 52 to the next teaching point, and in step S136 it is confirmed whether the welding gun unit 52 and the multi-joint robot 50 will not interfere with the workpiece 80 or other equipment, etc. If there is no interference, the current process ends directly.

[0122] If the multi-joint robot 50 does not interfere in step S131, the process proceeds to step S135, and the welding gun unit 52 is moved to the next teaching point.

[0123] If interference occurs in step S136, the process branches to step S137 to determine whether the interval between teaching points is large enough to generate teaching points at the midpoint. Whether it is large enough is determined based on the size, type, number of joints, etc. of the welding gun unit 52 or the multi-joint robot 50.

[0124] When the interval between the teaching points is large enough, the process proceeds to step S138 to generate a new teaching point at the midpoint between the teaching points, and the process returns to step S130 to place the welding gun unit 52 at the teaching point before the movement.

[0125] In step S137, when the intervals between the teaching points are not sufficiently large, the process proceeds to step S139, and a notification is given to the operator or the like that a new teaching point cannot be generated.

[0126] In step S134, when an appropriate retraction point cannot be set even by parallel displacement or rotation of the multi-joint robot 50 and interference cannot be eliminated, the process branches to step S140 to notify the operator or the like that interference cannot be eliminated.

[0127] According to the interference avoidance method and control device of the welding equipment of the present embodiment, the parallel lines are set in a manner that is tangent to the outer edge of the workpiece cross section but does not pass through the workpiece cross section. Therefore, with the workpiece cross section as a reference, a pair of parallel lines that are tangent to the outer edge of the workpiece cross section and are located on the extended plane of the workpiece cross section are generated, and the width of the parallel lines is compared with the maximum separation threshold of the welding electrode to determine whether the maximum separation threshold is larger. Thus, when the maximum separation threshold is larger, the direction of the reference parallel line can be determined as the pulling direction, and an efficient pulling direction determination operation of the welding equipment from the workpiece can be provided.

[0128] Furthermore, since the parallel lines are set to be tangent to the outer edge of the workpiece cross section without passing through the workpiece cross section, the gap between the welding electrode and the workpiece can be set more appropriately than in the conventional case where the overlapping portion of a grid-like solid and the workpiece is used as the workpiece model.

[0129] According to the present embodiment, the interference avoidance region is set, the interference avoidance region is divided, and parallel lines are set for each of the divided interference avoidance regions. Therefore, even if the interference avoidance region is not divided and the direction of the parallel lines is changed, the maximum separation threshold is not greater than the width of the parallel lines, and the interference avoidance region can be divided, and parallel lines can be appropriately set for each of the divided interference avoidance regions, and the welding electrode can be appropriately retracted from the workpiece.

[0130] In addition, in this embodiment,

[0131] In the first judgment process of judging whether the maximum separation threshold is greater than the width of the parallel lines, if it is judged that the maximum separation threshold is not greater than the width of the parallel lines, the direction of the parallel lines is changed (rotated), and in the interference avoidance area after the segmentation, the reference parallel line generation process is restarted, in which a pair of parallel lines are generated, and the pair of parallel lines are located on the extended plane of the workpiece cross section, tangent to the outer edge of the workpiece cross section without passing through the workpiece cross section. Therefore, in the first judgment process, even if it is judged that the maximum separation threshold is not greater than the width of the parallel lines, it is possible to set appropriate parallel lines by changing the direction of the parallel lines and restarting.

[0132] In addition, in this embodiment, a second determination step (for example, Figure 6 Step S106, Fig. 9 ), in the second judgment step, when the welding electrode is pulled out from the workpiece cross section, it is judged whether the outer edge of the other part of the welding equipment (for example, the multi-joint robot 50) other than the welding electrode interferes with the workpiece cross section. According to this embodiment, it is possible to prevent the outer edge of the other part of the welding equipment other than the welding electrode of the multi-joint robot from interfering with the workpiece cross section.

[0133] Description of symbols

[0134] 10: Offline teaching device;

[0135] 12: Robotic device;

[0136] 16: Monitor;

[0137] 50: Multi-joint robot;

[0138] 52: welding gun unit;

[0139] 70, 72: electrodes;

[0140] 80: Workpiece.

Claims

1. A method for avoiding interference of welding equipment, wherein when a welding equipment having a pair of welding electrodes whose ends are capable of changing the distance between them is pulled out from a workpiece, the method avoids interference between the welding electrodes and the workpiece, characterized in that: The workpiece cross section is composed of a plane, the plane including: an electrode straight line connecting the ends of a pair of welding electrodes separated from each other; and a pulling straight line intersecting the electrode straight line and extending in a direction in which the welding device is pulled out from the workpiece, and the interference avoidance method of the welding device includes: A reference parallel line generating step, generating a pair of parallel lines parallel to the drawing straight line, the pair of parallel lines being located on an extended plane of the workpiece cross section, being tangent to an outer edge of the workpiece cross section but not passing through the workpiece cross section; a first judging step of comparing the width of the pair of parallel lines generated in the reference parallel line generating step with a maximum separation threshold of the welding electrodes to judge whether the maximum separation threshold is greater than the width of the parallel lines, wherein the maximum separation threshold of the welding electrodes is a value obtained by subtracting a minimum gap required when the pair of welding electrodes is pulled out from the workpiece from a maximum distance between the ends; and A pulling direction determining step, when the maximum separation threshold is greater than the width of the parallel lines in the first judging step, determining the direction of the parallel lines as the pulling direction.

2. The interference avoidance method of welding equipment according to claim 1, characterized in that: The area including the entire cross section of the workpiece is used as an interference avoidance area to avoid the intrusion of the welding electrode of the welding equipment during the pulling movement. When it is determined in the first judgment process that the maximum separation threshold is not greater than the width of the parallel line, the interference avoidance area is divided, and for each interference avoidance area after division, the parallel line tangent to the outer edge of the workpiece cross section is regenerated through the reference parallel line generation process, and then the first judgment process is performed.

3. The interference avoidance method of welding equipment according to claim 1, characterized in that: The area including the entire cross section of the workpiece is used as an interference avoidance area to avoid the intrusion of the welding electrode of the welding equipment during the pulling movement. When it is determined in the first determination step that the maximum separation threshold is not greater than the width of the parallel lines, the directions of the parallel lines are changed, and the interference avoidance method of the welding equipment is re-performed in the interference avoidance area starting from the reference parallel line generation step.

4. The interference avoidance method of welding equipment according to claim 1, characterized in that: The welding equipment interference avoidance method includes a second determination step of determining whether an outer edge of a portion of the welding equipment other than the welding electrode interferes with the workpiece cross section when the welding electrode is pulled out from the workpiece cross section.

5. A control device for welding equipment, which prevents interference between the welding electrodes and the workpiece when the welding equipment having a pair of welding electrodes whose ends are capable of changing the distance between the electrodes is pulled out from the workpiece, characterized in that: The workpiece cross section is composed of a plane, the plane including: an electrode straight line connecting the ends of a pair of welding electrodes separated from each other; and a pulling straight line intersecting the electrode straight line and extending in a direction in which the welding device is pulled out from the workpiece, and the control device of the welding device includes: A reference parallel line generating step, generating a pair of parallel lines parallel to the drawing straight line, the pair of parallel lines being located on an extended plane of the workpiece cross section, being tangent to an outer edge of the workpiece cross section but not passing through the workpiece cross section; a first judging step of comparing the width of the pair of parallel lines generated in the reference parallel line generating step with a maximum separation threshold of the welding electrodes to judge whether the maximum separation threshold is greater than the width of the parallel lines, wherein the maximum separation threshold of the welding electrodes is a value obtained by subtracting a minimum gap required when the pair of welding electrodes is pulled out from the workpiece from a maximum distance between the ends; and A pulling direction determining step, when the maximum separation threshold is greater than the width of the parallel lines in the first judging step, determining the direction of the parallel lines as the pulling direction.

6. The control device of welding equipment according to claim 5, characterized in that: The area including the entire cross section of the workpiece is used as an interference avoidance area to avoid the intrusion of the welding electrode of the welding equipment during the pulling movement. When it is determined in the first judgment process that the maximum separation threshold is not greater than the width of the parallel line, the interference avoidance area is divided, and for each interference avoidance area after division, the parallel line tangent to the outer edge of the workpiece cross section is regenerated through the reference parallel line generation process, and then the first judgment process is performed.

7. The control device of welding equipment according to claim 5, characterized in that: The area including the entire cross section of the workpiece is used as an interference avoidance area to avoid the intrusion of the welding electrode of the welding equipment during the pulling movement. When it is determined in the first determination step that the maximum separation threshold is not greater than the width of the parallel lines, the directions of the parallel lines are changed, and the reference parallel line generation step is restarted in the interference avoidance region.

8. The control device of welding equipment according to claim 5, characterized in that: The control device of the welding equipment includes a second determination step of determining whether an outer edge of a portion of the welding equipment other than the welding electrode interferes with the workpiece cross section when the welding electrode is pulled out from the workpiece cross section.

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