Robot control device and spot welding system

Abstract

This invention provides a robot control device and spot welding system capable of roughening the surface of electrodes without the need for additional special equipment or operations. The robot control device controls the movement of a robot equipped with a spot welding gun having a pair of opposing electrodes. The robot control device includes a robot motion control unit that moves the pair of electrodes of the spot welding gun to a grinding position where they are ground by a rotating blade of an electrode grinding device, thereby grinding the surface of the pair of electrodes by the blade. The robot motion control unit also changes the contact position between the pair of electrodes and the blade from the grinding position to create scratches on the surface of the pair of electrodes after grinding by the blade.

Description

Technical Field

[0001] This invention relates to a robot control device and a spot welding system. Background Technology

[0002] Previously, it was known to perform spot welding (resistance welding) using robots equipped with spot welding guns at the front end of their arms. The spot welding gun holds the workpiece, such as a metal plate, which is the object to be welded, by a pair of electrodes, and current flows through the electrodes, thereby performing spot welding at predetermined points.

[0003] In recent years, aluminum alloys have been used as a material for lightweighting automobiles. It is known that aluminum alloys, due to their coated surfaces, require a higher current for spot welding compared to steel sheets. When a high current is applied to the electrodes for spot welding aluminum alloys, molten aluminum adheres to the electrode surface, reducing electrode life. To extend electrode life, frequent grinding of the electrode surface is necessary. However, grinding the electrodes consumes time in moving them to the grinding device and in the grinding process itself, thus posing a challenge to shortening welding operations.

[0004] Conventional methods for extending electrode life include roughening the electrode surface (see, for example, Patent Documents 1 and 2) and forming concentric raised portions on the electrode surface (see, for example, Patent Document 3). These methods prevent molten aluminum alloy from adhering to the electrode surface, thus avoiding the need for frequent grinding of the electrode surface.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: U.S. Patent No. 4,972,047

[0008] Patent Document 2: U.S. Patent No. 6,861,609

[0009] Patent Document 3: U.S. Patent No. 8,436,269 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] However, the aforementioned conventional methods require the use of specialized cutters or files to roughen the electrode surface, necessitating special equipment or work. Therefore, there is a need for a technique that can roughen the electrode surface without requiring additional special equipment or work.

[0012] Solution for solving the problem

[0013] One aspect of the robot control device disclosed herein is a robot control device that controls the movement of a robot equipped with a spot welding gun having a pair of electrodes arranged facing each other. The robot control device includes a robot motion control unit that moves the pair of electrodes of the spot welding gun to a grinding position where they are ground by a rotating blade of an electrode grinding device, so as to grind the surface of the pair of electrodes by the blade. The robot motion control unit also changes the position of the pair of electrodes in contact with the blade from the grinding position to create scratches on the surface of the pair of electrodes after grinding by the blade.

[0014] One aspect of the spot welding system disclosed herein is a spot welding system comprising: a spot welding gun having a pair of electrodes arranged facing each other; a robot that moves the spot welding gun; an electrode grinding device that grinds the surfaces of the pair of electrodes by means of a rotating blade; and a robot control device that controls the actions of the robot and the electrode grinding device, wherein the robot control device has a robot motion control unit that moves the pair of electrodes of the spot welding gun to a grinding position where they are ground by the rotating blade of the electrode grinding device, so as to grind the surfaces of the pair of electrodes by means of the blade, and the robot motion control unit changes the position of the pair of electrodes in contact with the blade from the grinding position to create scratches on the surfaces of the pair of electrodes after being ground by means of the blade.

[0015] The effects of the invention

[0016] According to one approach, a robot control device and spot welding system are available that can roughen the surface of an electrode without the need for additional special devices or work. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a spot welding system according to one implementation method.

[0018] Figure 2 This is a block diagram of a spot welding system according to one implementation method.

[0019] Figure 3 This is a side view showing the cutting edge of the electrode grinding device.

[0020] Figure 4 This is a top view showing the cutting edge of the electrode grinding device.

[0021] Figure 5 This is a side view showing the electrode being ground by the blade of an electrode grinding device.

[0022] Figure 6This is a flowchart illustrating the grinding action of the electrodes in a spot welding system.

[0023] Figure 7 This is a side view illustrating a method of roughening the surface of an electrode by means of the cutting edge of an electrode grinding device.

[0024] Figure 8 This is a side view illustrating a method of roughening the surface of an electrode by means of the cutting edge of an electrode grinding device.

[0025] Figure 9 This is a diagram showing the surface of an electrode that has undergone surface roughening.

[0026] Figure 10 This is a side view illustrating another method of roughening the surface of an electrode by means of the cutting edge of an electrode grinding device.

[0027] Figure 11 This is a side view illustrating another method of roughening the surface of an electrode by means of the cutting edge of an electrode grinding device.

[0028] Figure 12 This is a side view showing another way the electrodes are positioned. Detailed Implementation

[0029] The robot control device and spot welding system according to one embodiment will now be described in detail with reference to the accompanying drawings. Figure 1 A schematic diagram of a spot welding system according to one embodiment is shown. Figure 2 A block diagram of a spot welding system according to one embodiment is shown.

[0030] The spot welding system 1 includes a robot 2 with a spot welding gun 3, an electrode grinding device 4, a robot control device 5, and a teaching operation panel 6.

[0031] Robot 2 is a vertical jointed robot with multiple joints. Robot 2 has a base 21 mounted on the floor and a rotary table 22 capable of rotating about an axis extending vertically. Robot 2 has: a lower arm 23 supported on the rotary table 22 and capable of rotation; an upper arm 24 supported on the front end of the lower arm 23 and capable of rotation; and a wrist 25 rotatably supported on the front end of the upper arm 24. Robot 2 has multiple robot drive motors 26 that individually drive the rotary table 22, lower arm 23, upper arm 24, and wrist 25. The position and posture of robot 2 are changed by driving each of the robot drive motors 26 individually.

[0032] Furthermore, the robot is not limited to the methods described above. It can also be any robot capable of changing the position and orientation of the spot welding gun 3.

[0033] The spot welding gun 3 is mounted on the wrist 25 of the robot 2. The position and orientation of the spot welding gun 3 are changed by the position and orientation of the robot 2. The spot welding gun 3 has a pair of electrodes consisting of a movable electrode 31 and an opposing electrode 32, and an electrode drive motor 33 for driving the movable electrode 31, wherein the opposing electrode 32 is arranged facing the movable electrode 31.

[0034] In this embodiment, the movable electrode 31 and the opposing electrode 32 are approximately cylindrical. Figure 5 As shown, the movable electrode 31 and the opposing electrode 32 have R-shaped portions 31a and 32a formed by rounding the outer corners, and front end surfaces 31b and 32b formed by flat surfaces. The central axis Y of the movable electrode 31 and the opposing electrode 32 is aligned. The movable electrode 31 moves relative to the opposing electrode 32 in a direction approaching the opposing electrode 32 and in a direction away from the opposing electrode 32, driven by the electrode drive motor 33. The spot welding gun 3 applies voltage between the movable electrode 31 and the opposing electrode 32 while the workpiece (not shown), which is the object to be welded, is clamped between the movable electrode 31 and the opposing electrode 32 to perform spot welding. As the workpiece, aluminum alloy or a metal containing aluminum alloy can preferably be used.

[0035] The electrode grinding device 4 is generally referred to as an electrode tip dresser. In the electrode grinding device 4, "grinding" is interpreted broadly; for example, the scope of "grinding" in the electrode grinding device 4 includes grinding (removal processing) performed by a cutting tool (cutting edge 42). The electrode grinding device 4 is positioned on the floor surface on which the robot 2 is mounted, within the movable range of the robot 2. The electrode grinding device 4 has a main body 41 and a support member 43 erected vertically. The main body 41 is provided with a cutting edge 42 for grinding the movable electrode 31 and the opposing electrode 32 of the spot welding gun 3. The support member 43 supports the main body 41 in a predetermined position. A bracket 44 is fixed to the support member 43. Springs 45 are respectively arranged on the upper and lower sides of the main body 41. The springs 45 are configured to extend and retract in the vertical direction. The main body 41 is supported by the bracket 44 via the springs 45. The main body 41 can move freely in the vertical direction due to the elastic force of the springs 45.

[0036] The main body 41 of the electrode grinding device 4 is provided such that it protrudes laterally from the bracket 44 toward the support member 43. The cutting edge 42 is located at the end of the main body 41 furthest from the bracket 44. The cutting edge 42 is a tool used to grind the surfaces of the movable electrode 31 and the opposing electrode 32 of the spot welding gun 3. Figures 3-5As shown, the cutting edge 42 is supported by a cutter holder 420. The cutter holder 420, which has the cutting edge 42, is disposed inside a through hole through which the main body 41 passes in the vertical direction.

[0037] In this embodiment, the cutting edge 42 is arranged from the upper shoulder 421 and lower shoulder 422 of the tool holder 420 to the rotation axis X. In the tool holder 420, one cutting edge 42 is provided corresponding to each of the movable electrode 31 and the opposing electrode 32. The cutting edge 42 has a curved shape that mimics the front end shape of the movable electrode 31 and the opposing electrode 32. Figure 5 As shown, when the cutting edge 42 contacts the surfaces of the movable electrode 31 and the opposing electrode 32 for grinding, it extends radially from the central axis Y of the movable electrode 31 and the opposing electrode 32 along the front end faces 31b, 32b and the R-section 31a. The tool holder 420 rotates about the vertically extending rotation axis X, driven by the cutting edge drive motor 46 provided in the main body 41. During grinding, the central axis Y of the movable electrode 31 and the opposing electrode 32 coincides with the rotation axis X. Figure 5 As shown, the cutting edge 42 grinds the surfaces of the opposing movable electrode 31 and the opposing electrode 32 simultaneously by rotating the tool holder 420.

[0038] The robot control device 5 controls the movements of the robot 2, the spot welding gun 3 mounted on the robot 2, and the electrode grinding device 4. The robot control device 5 consists of a processing unit, which includes a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory) interconnected via a bus. The robot 2, spot welding gun 3, and electrode grinding device 4 are electrically connected to the robot control device 5 via a communication device.

[0039] like Figure 2 As shown, the robot control device 5 has a storage unit 51 that stores information related to the control of the robot 2, the spot welding gun 3, and the electrode grinding device 4. Action programs related to the actions of the robot 2, the spot welding gun 3, and the electrode grinding device 4 are stored in the storage unit 51. The actions of the robot 2, the spot welding gun 3, and the electrode grinding device 4 include electrode grinding actions and electrode surface roughening actions, which will be described later.

[0040] The robot control device 5 includes a robot control unit 52 for controlling the robot 2. The robot control unit 52 includes a robot motion control unit 521, which controls multiple robot drive motors 26 of the robot 2. The robot motion control unit 521 sends motion commands based on the motion program to the robot drive circuit 53. The robot drive circuit 53 supplies drive current based on the motion commands to the robot drive motors 26 respectively.

[0041] Robot 2 has a robot position detector 27 for detecting the position and orientation of robot 2. In this embodiment, the robot position detector 27 has a rotational position detector (not shown) mounted on each robot drive motor 26. Robot control unit 52 receives a signal related to the rotational position output from robot position detector 27. Thus, robot control unit 52 can detect the position and orientation of spot welding gun 3 based on the position and orientation of robot 2.

[0042] The robot control unit 5 includes a welding torch control unit 54 for controlling the spot welding torch 3. The welding torch control unit 54 includes a welding torch motion control unit 541, which controls the electrode drive motor 33 of the spot welding torch 3 and the voltage applied to the electrodes (movable electrode 31, opposing electrode 32). The welding torch motion control unit 541 sends motion commands based on the motion program to the electrode drive circuit 55 and the voltage supply circuit 56. The electrode drive circuit 55 supplies drive current to the electrode drive motor 33 based on the motion command to move the movable electrode 31. The voltage supply circuit 56 supplies voltage based on the motion command for spot welding to the movable electrode 31 and the opposing electrode 32.

[0043] The welding torch control unit 54 includes a position detection unit 542 for detecting the position of the movable electrode 31 relative to the opposing electrode 32. The spot welding torch 3 includes an electrode position detector 34 for detecting the position of the movable electrode 31. In this embodiment, the electrode position detector 34 includes a rotational position detector (not shown) mounted on the electrode drive motor 33. The position detection unit 542 detects the position of the movable electrode 31 relative to the opposing electrode 32 based on the output of the electrode position detector 34.

[0044] The welding torch control unit 54 includes a torque detection unit 543 that detects the torque output by the electrode drive motor 33. The torque detection unit 543 can detect the torque output by the electrode drive motor 33 based on, for example, an operation command controlling the electrode drive motor 33. Alternatively, a current detector that detects the current value supplied to the electrode drive motor 33 can be disposed on the spot welding torch 3. The torque detection unit 543 can also detect the torque based on the current value detected by the current detector. Thus, the torque detection unit 543 can detect the pushing force of the movable electrode 31 towards the opposing electrode 32.

[0045] The robot control unit 5 includes a grinding control unit 57 for controlling the electrode grinding device 4. The grinding control unit 57 includes a grinding action control unit 571 for controlling the blade drive motor 46 of the electrode grinding device 4. The grinding action control unit 571 sends action commands based on the action program for the grinding action to the blade drive circuit 572. The blade drive circuit 572 supplies drive current based on the action commands to the blade drive motor 46.

[0046] like Figure 1 and Figure 2 As shown, the robot control device 5 has a teach pendant 6 connected via a communication device. The teach pendant 6 has an input section 61 for inputting information related to the robot 2, the spot welding gun 3, and the electrode grinding device 4. The operator can input motion programs related to the position and posture of the spot welding gun 3 based on the position and posture of the robot 2 shown in the teach pendant, as well as motion programs related to the movement of the electrode grinding device 4, into the robot control device 5 via the input section 61. The input section 61 consists of a keyboard, a dial, etc. The teach pendant 6 also has a display section 62 for displaying information related to the robot 2, the spot welding gun 3, and the electrode grinding device 4.

[0047] Next, use Figure 6 The flowchart shown illustrates the grinding operation of the movable electrode 31 and the opposing electrode 32 of the spot welding gun 3 in the spot welding system 1. In this embodiment, the spot welding system 1 uses a cutting edge 42 to grind the surfaces of the movable electrode 31 and the opposing electrode 32 of the spot welding gun 3, and then roughens the surfaces of the movable electrode 31 and the opposing electrode 32. The spot welding system 1 uses the same cutting edge 42 as when grinding the movable electrode 31 and the opposing electrode 32 to perform surface roughening processing on the surfaces of the movable electrode 31 and the opposing electrode 32.

[0048] During the prescribed welding operation performed by the spot welding gun 3, the robot control device 5, under the control of the robot motion control unit 521, changes the position and posture of the robot 2 from the welding position, thereby moving the spot welding gun 3 to the position of the electrode grinding device 4 predetermined by the motion program (step S1).

[0049] After the spot welding torch 3 moves to the designated position of the electrode grinding device 4, the robot control device 5, under the control of the welding torch motion control unit 541, drives the electrode drive motor 33 to make the movable electrode 31 and the opposing electrode 32 move as follows: Figure 5The tool holder 420 is moved to the designated grinding position where the cutting edge 42 is clamped, as shown. Then, under the control of the grinding action control unit 571, the robot control device 5 drives the cutting edge drive motor 46 to rotate the tool holder 420, and the cutting edge 42, rotating around the rotation axis X, begins grinding the surfaces of the movable electrode 31 and the opposing electrode 32 (step S2). The rotating cutting edge 42 grinds and removes the molten metal adhering to the surfaces of the movable electrode 31 and the opposing electrode 32.

[0050] The grinding of the electrodes is performed by clamping the rotating cutting edge 42 between the movable electrode 31 and the opposing electrode 32 with a predetermined pushing force. The robot control unit 5 controls the drive of the electrode drive motor 33 through the welding torch control unit 54, so that the pushing force of the movable electrode 31 toward the opposing electrode 32 detected by the torque detection unit 543 of the welding torch control unit 54 becomes the predetermined pushing force required for grinding based on the action program.

[0051] The grinding performed by the rotating blade 42 on the movable electrode 31 and the opposing electrode 32 is continuously executed for a predetermined time based on the action program. The robot control device 5 monitors whether the grinding has ended (step S3) based on the action program, and continues grinding if it determines that the grinding has not ended (if "no" is indicated in step S3).

[0052] When the robot control device 5 determines that the grinding has ended (in the case of "yes" in step S3), it changes the position and posture of the robot 2 under the control of the robot motion control unit 521, so that the movable electrode 31 and the opposing electrode 32 of the spot welding gun 3 move to the surface roughening position predetermined by the motion program, and the surface roughening process begins (step S4).

[0053] When the surface roughening process begins, the robot control unit 5, through the control of the welding torch motion control unit 541 and the robot motion control unit 521, performs the following... Figure 7 As shown, the movable electrode 31 is moved away from the opposing electrode 32, and both the movable electrode 31 and the opposing electrode 32 are separated from the cutting edge 42 to release the clamping of the cutting edge 42. Furthermore, the robot control device 5 changes the position and posture of the robot 2 under the control of the robot motion control unit 521, changing the position and posture of the spot welding gun 3 so that the front end faces 31b and 32b of the movable electrode 31 and the opposing electrode 32 contact the corner 42a of the cutting edge 42. The corner 42a of the cutting edge 42 are respectively disposed at the corners of the cutting edge 42 along the rotation axis X (upper and lower ends). The corner 42a are disposed at the ends of the cutting edge 42 that are adjacent to the upper shoulder 421 and lower shoulder 422 of the tool holder 420, respectively. Furthermore, after the surface roughening process begins, the cutting edge 42 continues to rotate.

[0054] In this embodiment, the movable electrode 31 and the opposing electrode 32 to be surface roughened are as follows: Figure 7 The movable electrodes 31 and 32 are positioned at a distance from each other, roughly equivalent to the distance between the upper shoulder 421 and the lower shoulder 422 along the rotation axis X of the tool holder 420. The movable electrodes 31 and 32, separated from each other, move parallel to each other with their central axis Y offset from the rotation axis X, so that their front end faces 31b and 32b contact the corner 42a of the cutting edge 42. At this time, the movable electrodes 31 and 32 apply only a smaller pushing force to the cutting edge 42 than the pushing force applied during grinding. Alternatively, the movable electrodes 31 and 32 do not apply any pushing force to the cutting edge 42. The front end faces 31b and 32b of the movable electrodes 31 and 32 only slightly contact the corner 42a of the cutting edge 42.

[0055] The movable electrode 31 and the opposing electrode 32 contact the front end faces 31b and 32b of the corner 42a of the blade portion 42, creating linear scratches through the rotation of the blade portion 42. This forms fine linear grooves on the front end faces 31b and 32b. The robot control device 5, controlled by the robot motion control unit 521, performs the following actions: Figure 8 As shown, the positions of the movable electrode 31 and the opposing electrode 32 relative to the corner 42a of the blade portion 42 can be changed in various directions within a plane parallel to the front end faces 31b and 32b. Thus, as... Figure 9 As shown, multiple fine linear grooves G extending in multiple directions are formed on the front end faces 31b and 32b of the movable electrode 31 and the opposing electrode 32 by the corner 42a of the blade portion 42, thereby roughening the surface of the movable electrode 31 and the opposing electrode 32.

[0056] The spacing between adjacent grooves G is adjusted by appropriately adjusting the rotational speed of the blade portion 42 and the moving speed of the movable electrode 31 and the opposing electrode 32. The intersection angle of intersecting grooves G is adjusted by appropriately adjusting multiple moving directions of the movable electrode 31 and the opposing electrode 32. When multiple grooves G are formed by the corner portion 42a of the blade portion 42, the movement of the movable electrode 31 and the opposing electrode 32 is not limited to linear movement, but can also be curved movement.

[0057] When machining the front end faces 31b and 32b of the movable electrode 31 and the opposing electrode 32 into linear scratches, the robot control device 5 can also control the axial movement of the movable electrode 31 and the opposing electrode 32 via the robot motion control unit 521. Figure 7 and Figure 8 The movement in the vertical direction and along the direction orthogonal to the axis (in the middle) Figure 7 and Figure 8The movement is in the left and right directions. Thus, for curved surfaces such as the R portions 31a and 32a of the movable electrode 31 and the opposing electrode 32, multiple linear grooves G can be formed by the corner 42a of the rotating blade portion 42.

[0058] During surface roughening processing, the robot control device 5 can also be used as follows: Figure 10 and Figure 11 As shown, the robot motion control unit 521 controls the position and posture of the spot welding gun 3 by tilting the central axis Y of the movable electrode 31 and the opposing electrode 32 relative to the rotation axis X. In this case, the corner 42a of the blade 42 contacts the front end face 31b or 32b of either the movable electrode 31 or the opposing electrode 32. The robot control device 5, under the control of the robot motion control unit 521, performs the following control: Figure 11 As shown, the position of the movable electrode 31 or the opposing electrode 32 relative to the corner 42a of the blade portion 42 is changed in various directions within a plane parallel to the front end surfaces 31b and 32b to roughen the surface of the front end surfaces 31b or 32b.

[0059] In this method, the movable electrode 31 and the opposing electrode 32 need to be surface roughened separately. However, since the corner 42a of the cutting edge 42 can be made to contact the front end surfaces 31b and 32b sharply, a clear groove G can be formed on the front end surfaces 31b and 32b.

[0060] The robot control device 5 monitors whether the surface roughening process has ended based on the action program (step S5). If it is determined that the surface roughening process has not ended (if it is "no" in step S5), the surface roughening process continues.

[0061] When the robot control device 5 determines that the surface roughening process has been completed (if "yes" is indicated in step S5), it changes the position and posture of the robot 2 through the robot motion control unit 521, so that the spot welding gun 3 moves to the welding operation position predetermined by the motion program and begins the next welding operation (step S6). Thus, the grinding operation for the movable electrode 31 and the opposing electrode 32 is completed.

[0062] The robot control device 5 according to this embodiment achieves the following effects. The robot control device 5 controls the movement of a robot 2 equipped with a spot welding gun 3, which has a pair of movable electrodes 31 and opposing electrodes 32 arranged facing each other. The robot control device 5 has a robot motion control unit 521, which moves the movable electrodes 31 and opposing electrodes 32 of the spot welding gun 3 to a grinding position where they are ground by the rotating blade 42 of the electrode grinding device 4, so that the surfaces of the movable electrodes 31 and opposing electrodes 32 are ground by the blade 42. The robot motion control unit 521 changes the position where the movable electrodes 31 and opposing electrodes 32 contact the blade 42 from the grinding position, so as to create scratches on the front end faces 31b and 32b of the movable electrodes 31 and opposing electrodes 32 after grinding by the blade 42. Therefore, the same blade 42 can be used to roughen the surfaces of the movable electrodes 31 and opposing electrodes 32 after grinding by the rotating blade 42. The surfaces of the movable electrode 31 and the opposing electrode 32 can be roughened without the need for additional special devices or operations to roughen them.

[0063] In this embodiment, the robot motion control unit 521 moves the movable electrode 31 and the opposing electrode 32 by creating scratches on their surfaces while changing the positions of the movable electrode 31 and the opposing electrode 32 in contact with the cutting edge 42. This forms multiple fine, linear grooves extending in multiple directions on the movable electrode 31 and the opposing electrode 32. Therefore, surface roughening of the movable electrode 31 and the opposing electrode 32 can be easily achieved.

[0064] In this embodiment, the robot motion control unit 521 can move the movable electrode 31 and the opposing electrode 32 axially and in a direction orthogonal to the axial direction when scratches are made on the surfaces of the movable electrode 31 and the opposing electrode 32. Therefore, linear grooves G can be formed to roughen the surface of curved surfaces such as the R-sections 31a and 32a of the movable electrode 31 and the opposing electrode 32.

[0065] In this embodiment, when the robot motion control unit 521 scratches the surfaces of the movable electrode 31 and the opposing electrode 32, it moves the movable electrode 31 and the opposing electrode 32 such that their surfaces come into contact with the corner 42a of the cutting edge 42. Therefore, without modifying the cutting edge 42 used for grinding, the surfaces of the movable electrode 31 and the opposing electrode 32 can be easily roughened using the cutting edge 42.

[0066] In this embodiment, the process of creating scratches on the surfaces of the movable electrode 31 and the opposing electrode 32 is a surface roughening process. Therefore, by using the grinding blade 42 to create scratches on the surfaces of the movable electrode 31 and the opposing electrode 32, the surfaces of the movable electrode 31 and the opposing electrode 32 can be easily roughened.

[0067] The spot welding system 1 of this embodiment includes: a spot welding gun 3 having a pair of movable electrodes 31 and opposing electrodes 32 arranged in opposite directions; a robot 2 that moves the spot welding gun 3; an electrode grinding device 4 that grinds the surfaces of the pair of movable electrodes 31 and opposing electrodes 32 by means of a rotating blade 42; and a robot control device 5 that controls the actions of the robot 2 and the electrode grinding device 4. The robot control device 5 has a robot motion control unit 521 that moves the pair of movable electrodes 31 and opposing electrodes 32 of the spot welding gun 3 to a grinding position where they are ground by the rotating blade 42 of the electrode grinding device 4, so that the surfaces of the movable electrodes 31 and opposing electrodes 32 are ground by means of the blade 42. The robot motion control unit 521 changes the position where the movable electrodes 31 and opposing electrodes 32 contact the blade 42 from the grinding position, so as to create scratches on the surfaces of the movable electrodes 31 and opposing electrodes 32 after grinding by means of the blade 42. Therefore, the same cutting edge 42 can be used to roughen the surfaces of the movable electrode 31 and the opposing electrode 32, which have been ground by the rotating cutting edge 42. The surfaces of the movable electrode 31 and the opposing electrode 32 can be roughened without the need for additional special devices or work to roughen them.

[0068] The movable electrode 31 and the opposing electrode 32 in this embodiment have R-sections 31a and 32a obtained by machining the outer peripheral corners into rounded corners, but are not limited to this method. The movable electrode 31 and the opposing electrode 32 may also be, for example, as shown in... Figure 12 As shown, it has chamfered portions 31c and 32c formed by tilting the outer corner.

[0069] In the spot welding gun 3 of this embodiment, the movable electrode 31 is provided in a manner that allows it to move relative to the opposing electrode 32 in a direction approaching the opposing electrode 32 and in a direction away from the opposing electrode 32, but it is not limited to this manner. It is also possible to configure both electrodes of the spot welding gun to be movable.

[0070] The electrode polishing apparatus 4 of this embodiment is configured to simultaneously polish and roughen the surfaces of both the movable electrode 31 and the opposing electrode 32, but it is not limited to this configuration. The electrode polishing apparatus may also be configured to polish and roughen the surfaces of each pair of electrodes individually.

[0071] The spot welding system 1 in this embodiment is configured such that a robot 2, a spot welding gun 3, and an electrode grinding device 4 are controlled by a robot control device 5, but it is not limited to this configuration. Alternatively, the electrode grinding device 4 may be controlled by a dedicated control device different from the robot control device 5.

[0072] Explanation of reference numerals in the attached figures

[0073] 1: Spot welding system; 2: Robot; 3: Spot welding gun; 31: Movable electrode; 32: Opposing electrode; 4: Electrode grinding device; 42: Blade part; 42a: Corner part; 5: Robot control device; 521: Robot motion control unit.

Claims

1. A robot control device for controlling the movement of a robot equipped with a spot welding gun, the spot welding gun having a pair of electrodes arranged facing each other, wherein, The robot control device includes a robot motion control unit that moves the pair of electrodes of the spot welding gun to a grinding position where they are ground by the rotating blade of the electrode grinding device, so as to grind the surfaces of the pair of electrodes by the blade. The robot motion control unit changes the position where the pair of electrodes contacts the cutting edge from the grinding position to the surface roughening position, so as to use the same cutting edge as during grinding to create scratches on the surface of the pair of electrodes after grinding by the cutting edge to roughen the surface.

2. The robot control device according to claim 1, wherein, The robot motion control unit moves the pair of electrodes located at the roughened surface position by creating scratches on the surface of the pair of electrodes while changing the position of the pair of electrodes in contact with the cutting edge.

3. The robot control device according to claim 1 or 2, wherein, When the robot motion control unit creates scratches on the surface of the pair of electrodes located at the surface roughening position, it moves the pair of electrodes along the axial direction and in a direction orthogonal to the axial direction.

4. The robot control device according to claim 1 or 2, wherein, When the robot motion control unit scratches the surface of the pair of electrodes located at the surface roughening position, it moves the pair of electrodes in such a way that the surface of the pair of electrodes contacts the corner of the blade portion.

5. The robot control device according to claim 3, wherein, When the robot motion control unit scratches the surface of the pair of electrodes located at the surface roughening position, it moves the pair of electrodes in such a way that the surface of the pair of electrodes contacts the corner of the blade portion.

6. A spot welding system, comprising: A spot welding gun having a pair of electrodes facing each other; A robot that moves the spot welding gun; An electrode grinding apparatus that grinds the surfaces of the pair of electrodes by means of a rotating blade; and A robot control device controls the actions of the robot and the electrode grinding device. wherein The robot control device includes a robot motion control unit that moves the pair of electrodes of the spot welding gun to a grinding position where they are ground by the rotating blade of the electrode grinding device, so as to grind the surfaces of the pair of electrodes by the blade. The robot motion control unit changes the position where the pair of electrodes contacts the cutting edge from the grinding position to the surface roughening position, so as to use the same cutting edge as during grinding to create scratches on the surface of the pair of electrodes after grinding by the cutting edge to roughen the surface.

7. A spot welding system, comprising: A spot welding gun having a pair of electrodes facing each other; A robot that moves the spot welding gun; An electrode grinding apparatus that grinds the surfaces of the pair of electrodes by means of a rotating blade; and A robot control device controls the actions of the robot and the electrode grinding device. in, The robot control device includes a robot motion control unit that moves the pair of electrodes of the spot welding gun to a grinding position where they are ground by the rotating blade of the electrode grinding device, so as to grind the surfaces of the pair of electrodes by the blade. The robot motion control unit changes the contact position between the pair of electrodes and the blade from the grinding position by creating scratches on the surface of the pair of electrodes after grinding by the blade, so that the surface of the pair of electrodes contacts the corner of the blade.

Images