Apparatus, control device, and method for correcting welding gun pressure command

Abstract

There is a need to optimize the number of attitudes in which a welding gun is positioned in an operation for acquiring a pressure force for correcting a pressure force command of a welding gun, and to simplify that operation.　A device 70 comprises: an operation execution unit 62 that causes a robot 12 to operate so as to position a welding gun 14 at a teaching attitude defined in a welding work program; a pressure force acquisition unit 64 that acquires a pressure force from when the welding gun 14 is positioned at the teaching attitude by the operation execution unit 62 and is driven by a first pressure force command; and a command correction unit 66 that corrects the first pressure force command on the basis of the pressure force acquired by the pressure force acquisition unit 64, thereby calculating a second pressure force command for driving the welding gun 14 at the teaching attitude at the time of execution of the welding work program.

Description

[Technical Field]

[0001] The present disclosure relates to an apparatus, a control device, and a method for correcting a pressure command that defines the pressure of a welding gun. [Background technology]

[0002] BACKGROUND ART There is known a device that corrects a pressure command that defines the pressure applied by a welding gun in accordance with the attitude of the welding gun (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-47249 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, there has been a demand for a technique for correcting a pressure command with high accuracy and simplifying the work involved in the correction. [Means for solving the problem]

[0005] In one aspect of the present disclosure, an apparatus for correcting a pressure command that determines the pressure applied by a welding gun that is moved by a robot and applies pressure to a workpiece to weld it, in accordance with the posture of the welding gun, includes an operation execution unit that operates the robot to position the welding gun in a teaching posture defined in a welding work program that causes the robot and welding gun to perform welding work, a pressure acquisition unit that acquires the pressure applied when the welding gun is driven with a first pressure command when the operation execution unit positions the welding gun in the teaching posture, and a command correction unit that corrects the first pressure command based on the pressure acquired by the pressure acquisition unit, thereby determining a second pressure command to be used when driving the welding gun in the teaching posture during execution of the welding work program.

[0006] In another aspect of the present disclosure, a method for correcting a pressure command that determines the pressure applied by a welding gun that is moved by a robot and applies pressure to a workpiece to weld it, based on the posture of the welding gun, involves a processor operating the robot to position the welding gun in a teaching posture defined in a welding work program that causes the robot and welding gun to perform welding work, obtaining the pressure applied when the welding gun is driven with a first pressure command when positioned in the teaching posture, and correcting the first pressure command based on the obtained pressure, thereby determining a second pressure command to be used when driving the welding gun in the teaching posture during execution of the welding work program. [Effects of the Invention]

[0007] According to the present disclosure, by correcting the pressure command using a taught posture that positions the welding gun in actual welding work, it is possible to accurately determine a second pressure command that can generate a constant pressure in the welding gun regardless of the posture. Also, since there is no need to teach the robot a new posture for correcting the pressure command, the work of correcting the pressure command can be simplified. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a welding robot system according to an embodiment. [Figure 2] FIG. 2 is a block diagram of the welding robot system shown in FIG. [Figure 3] FIG. 2 is an enlarged view of the welding gun shown in FIG. [Figure 4] This shows the state in which the attitude of the welding gun shown in Figure 3 has been changed. [Figure 5] 4 is a flowchart showing an example of a method for correcting a pressure command, which is executed by the welding robot system shown in FIG. [Figure 6] An example of a welding work program is shown below. [Figure 7] 1 shows an example of a position data table. [Figure 8] 1 shows an example of a data table of welding conditions. [Figure 9]10 shows an enlarged view of a welding gun according to another embodiment. [Figure 10] FIG. 10 is a schematic diagram of a welding robot system according to another embodiment. [Figure 11] FIG. 11 is a block diagram of the welding robot system shown in FIG. [Figure 12] 11 is a flowchart showing an example of a method for correcting a pressure command, which is executed by the welding robot system shown in FIG. 10. [Figure 13] FIG. 12 is a block diagram showing other functions of the welding robot system shown in FIG. 11. [Figure 14] 14 is a flowchart showing an example of a method for correcting a pressure command, which is executed by the welding robot system shown in FIG. 13. [Figure 15] FIG. 3 is a block diagram showing other functions of the welding robot system shown in FIG. 2. [Figure 16] 16 is a flowchart showing an example of a method for correcting a pressing force command, which is executed by the welding robot system shown in FIG. 15. [Figure 17] 17 is a flowchart showing an example of the process of step S35 in FIG. 16. [Figure 18] 10 shows another example of a position data table. [Figure 19] An example of a posture reproduction program is shown below. [Figure 20] 10 shows yet another example of the position data table. [Figure 21] FIG. 12 is a block diagram showing still another function of the welding robot system shown in FIG. 11. [Figure 22] 22 is a flowchart showing an example of a method for correcting a pressing force command, which is executed by the welding robot system shown in FIG. 21. [Figure 23] 23 is a flowchart showing an example of the process of step S54 in FIG. 22. [Figure 24] 10 shows yet another example of the position data table. [Figure 25] Another example of a posture reproduction program is shown below. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In various embodiments described below, similar elements will be designated by the same reference numerals, and duplicated explanations will be omitted. First, a welding robot system 10 according to one embodiment will be described with reference to FIGS. 1 and 2. The welding robot system 10 includes a robot 12, a welding gun 14, a welding force sensor 16, and a control device 18.

[0010] In this embodiment, the robot 12 is a vertically articulated robot and includes a robot base 20, a rotating body 22, a lower arm 24, an upper arm 26, and a wrist 28. The robot base 20 is fixed to the floor of a work cell. The rotating body 22 is mounted on the robot base 20 so as to be rotatable about a vertical axis.

[0011] Lower arm 24 is attached to rotating body 22 so as to be rotatable around a horizontal axis. Upper arm 26 is rotatably attached to the distal end of lower arm 24. Wrist 28 has wrist base 28a rotatably attached to the distal end of upper arm 26, and wrist flange 28b attached to wrist base 28a so as to be rotatable around wrist axis A1.

[0012] A plurality of servo motors 30 (FIG. 2) are provided on each of the robot base 20, the rotating body 22, the lower arm 24, the upper arm 26, and the wrist 28. These servo motors 30 rotate each movable component of the robot 12 (i.e., the rotating body 22, the lower arm 24, the upper arm 26, the wrist 28, and the wrist flange 28b) in response to commands from the control device 18, thereby moving the welding gun 14.

[0013] Welding gun 14 is detachably attached to wrist flange 28b. As shown in Fig. 3, in this embodiment, welding gun 14 is a so-called C-type spot welding gun, and includes a base 32, a fixed arm 34, a fixed welding tip 36, a movable arm 38, a servo motor 40, a motion conversion mechanism 42, and a movable welding tip 44.

[0014] The base portion 32 is connected to the wrist flange 28b. The fixed arm 34 has a base end 34a fixed to the base portion 32 and extends in a generally L-shaped curve from the base end 34a to a tip end 34b. The fixed welding tip 36 is fixed to the tip end 34b of the fixed arm 34.

[0015] The movable arm 38 is mounted on the base 32 so as to be reciprocatable along the gun axis A2. In this embodiment, the movable arm 38 is a rod-shaped member extending linearly along the gun axis A2. The movable welding tip 44 is fixed to the tip 38a of the movable arm 38 so as to be aligned with the fixed welding tip 36 on the gun axis A2. The gun axis A2 may be arranged parallel to the wrist axis A1.

[0016] The servo motor 40 has an output shaft (not shown) and is fixed to the base portion 32. The motion conversion mechanism 42 has, for example, a ball screw mechanism or a mechanism consisting of a timing belt and pulley, and converts the rotational motion of the output shaft of the servo motor 40 into reciprocating motion of the movable arm 38 along the gun axis A2.

[0017] The control device 18 controls the operations of the robot 12 and the welding gun 14. As shown in Fig. 2, the control device 18 is a computer having a processor 50, a memory 52, and an I / O interface 54. The processor 50 has a CPU or a GPU, etc., and is communicatively connected to the memory 52 and the I / O interface 54 via a bus 56, and performs arithmetic processing for the function of correcting a pressing force command, which will be described later, while communicating with these components.

[0018] The memory 52 has a RAM, a ROM, or the like, and temporarily or permanently stores various data used in the arithmetic processing executed by the processor 50 and various data generated during the arithmetic processing. The I / O interface 54 has, for example, an Ethernet (registered trademark) port, a USB port, an optical fiber connector, or an HDMI (registered trademark) terminal, and communicates data with external devices via a wired or wireless connection under instructions from the processor 50. In this embodiment, the servo motors 30 and 40 and the pressure sensor 16 are connected to the I / O interface 54 so as to be able to communicate via a wired or wireless connection.

[0019] The control device 18 is further provided with an input device 58 and a display device 60. The input device 58 has a keyboard, a mouse, a touch panel, or the like, and receives data input from an operator. The display device 60 has a liquid crystal display, an organic EL display, or the like, and displays various data.

[0020] The input device 58 and the display device 60 are communicatively connected to the I / O interface 54 via a wired or wireless connection. The input device 58 and the display device 60 may be integrated into the housing of the control device 18, or may be provided as a single computer (such as a PC) separate from the housing of the control device 18.

[0021] 1, a robot coordinate system C1 is set for the robot 12. The robot coordinate system C1 is a coordinate system for automatically controlling each movable component of the robot 12. In this embodiment, the robot coordinate system C1 is set for the robot 12 so that its origin is located at the center of the robot base 20 and its z axis coincides with the rotation axis of the rotating body 22.

[0022] 3, a tool coordinate system C2 is set for the welding gun 14. The tool coordinate system C2 is a coordinate system that defines the position and posture of the welding gun 14 in the robot coordinate system C1. In this embodiment, the tool coordinate system C2 is set for the welding gun 14 so that its origin (so-called TCP) is located on the fixed welding tip 36 (for example, the center of the tip face) and its z-axis coincides with (or is parallel to) the gun axis A2.

[0023] When moving the welding gun 14, the processor 50 first sets a tool coordinate system C2 in the robot coordinate system C1, and generates commands (position commands, speed commands, torque commands, etc.) to each servo motor 30 of the robot 12 so as to position the welding gun 14 at the position and orientation represented by the set tool coordinate system C2. In this way, the welding gun 14 is moved by the operation of the robot 12, and is positioned at any position and orientation in the robot coordinate system C1.

[0024] The welding gun 14 applies pressure to a workpiece (not shown) to weld it. Specifically, the processor 50 sends a pressure command F C and moves the movable arm 38 along the gun axis A2, thereby moving the movable welding tip 44 toward the fixed welding tip 36. As a result, the workpiece is clamped between the movable welding tip 44 and the fixed welding tip 36. At this time, the movable welding tip 44 applies a pressure command F C A pressure F according to the pressure is applied.

[0025] Next, the processor 50 activates the fixed welding tip 36 and the movable welding tip 44, and energizes the fixed welding tip 36 and the movable welding tip 44. As a result, the workpiece held between the fixed welding tip 36 and the movable welding tip 44 is welded. C is a command that defines the welding force F to be generated by the welding gun 14, and represents a target value of the welding force F (for example, 2 [kN]).

[0026] The welding force sensor 16 has a piezoelectric element, a strain gauge, or the like, and measures the welding force F of the welding gun 14. Specifically, the welding force sensor 16 is configured to be able to be held by an operator with one hand, and is manually set between the fixed welding tip 36 and the movable welding tip 44 by the operator when measuring the welding force F. The welding force sensor 16 is held between the movable welding tip 44 driven by the servo motor 40 and the fixed welding tip 36, and measures the welding force F applied to the welding force sensor 16 at this time. The welding force sensor 16 supplies detection data of the measured welding force F to the control device 18.

[0027] Here, the predetermined pressure command F C The welding force F generated by the welding gun 14 when the welding gun 14 is driven can vary depending on the attitude of the welding gun 14. For example, in the example shown in Figure 3, the welding gun 14 is positioned in an attitude OR0 in which the gun axis A2 is parallel to the vertical direction and the movable welding tip 44 is aligned vertically above the fixed welding tip 36.

[0028] In such a posture OR0, if the processor 50 controls the servo motor 40 to apply a predetermined pressure command F C_0 (For example, F C_0 =1 [kN]), and the welding gun 14 is driven by the welding force command F C_0 Assume that the movable welding tip 44 pressurizes an object to be pressed (for example, the fixed welding tip 36) in accordance with the above.

[0029] At this time, the pressure force F0 applied to the workpiece from the movable welding tip 44 is a force component F obtained by converting the torque of the servo motor 40 in the direction of the gun axis A2 by the motion conversion mechanism 42. τ and the gravity component F of the moving part of the welding gun 14, which is made up of the motion conversion mechanism 42, the movable arm 38, and the movable welding tip 44. g The resultant force F0 (=F τ +F g )

[0030] Next, the welding gun 14 is rotated from the orientation OR0 shown in FIG. 3 by an angle θ around the y axis of the tool coordinate system C2 to the orientation OR shown in FIG. θIn this state, the processor 50 controls the servo motor 40 to generate the same pressure command F C_0 The movable welding tip 44 is driven by the force F , and the workpiece is pressed by the movable welding tip 44. θ is the force component F τ and the above-mentioned gravitational component F g Force component F multiplied by cosθ g Resultant force F with cosθ θ (=F τ +F g cosθ).

[0031] Therefore, this posture OR θ The applied force F θ is compared with the applied force F0 in the orientation OR0 shown in Fig. 3. g The applied pressure F decreases by (1-cosθ). In this way, the applied pressure F changes depending on the attitude OR of the welding gun 14. Such a variation in the applied pressure F depending on the attitude OR affects the welding quality.

[0032] Therefore, in this embodiment, the processor 50 determines the welding force command F in accordance with the attitude OR of the welding gun 14. C Hereinafter, referring to FIG. 5, the pressure command F C 5 is started when the processor 50 receives a correction start command from an operator, a higher-level controller, or the like.

[0033] In step S1, processor 50 acquires welding operation program 200. This welding operation program 200 is a computer program for causing robot 12 and welding gun 14 to perform welding operation. An example of welding operation program 200 is shown schematically in FIG.

[0034] In the welding operation program 200 shown in FIG. 6, for example, the code "MOVE[TP1] VELOCITY[V1]" on the first line is a positioning command IN for moving the welding gun 14 by the robot 12 at a velocity V=V1 [mm / sec] and positioning it at the first taught position TP1 and taught attitude OR1 indicated by the identifier [TP1]. P is.

[0035] Meanwhile, a position data table 202 is created in advance as data separate from the welding operation program 200 and stored in memory 52. ​​An example of the position data table 202 is shown in FIG. 7. In the position data table 202 shown in FIG. 7, coordinate data each assigned with an identifier "TP1," "TP2," "TP3," and "TP4" is stored.

[0036] For example, the identifier "TP1" is assigned to the coordinates (X1, Y1, Z1, W1, P1, R1). Of these coordinates (X1, Y1, Z1, W1, P1, R1), (X1, Y1, Z1) are coordinates in the robot coordinate system C1 where the welding gun 14 (specifically, TCP) should be positioned, and represent the first taught position TP1. On the other hand, (W1, P1, R1) are coordinates in the tool coordinate system C1 in the robot coordinate system C1. 2 The coordinates define the axial directions (so-called yaw, pitch, and roll) of the robot, and represent the first teaching attitude OR1.

[0037] When executing the welding operation program 200, the processor 50 executes the positioning instruction IN "MOVE[TP1] VELOCITY[V1]" on the first line. P When the coordinates are read, the position data table 202 is referenced, and the coordinates (X1, Y1, Z1, W1, P1, R1) represented by the identifier "TP1" are obtained from the position data table 202.

[0038] Then, the processor 50 sets the origin position represented by the coordinates (X1, Y1, Z1, W1, P1, R1) and the tool coordinate system C2 for each axis direction in the robot coordinate system C1, and generates commands (position command, speed command, torque command, etc.) to each servo motor 30 of the robot 12 so as to move the welding gun 14 at a speed V1 to the first taught position TP1 and taught attitude OR1 represented by the set tool coordinate system C2. In this way, the processor 50 generates a positioning command IN P By operating the robot 12 in accordance with the above, the welding gun 14 is positioned at the first taught position TP1 and taught attitude OR1.

[0039] In this manner, in this embodiment, the welding operation program 200 includes the n-th teaching position TP n and teaching posture OR n (n=1,2,3,4) is specified. nth teaching position TP n and teaching posture OR n Each of the above is taught to the robot 12 in advance by an operator using a teaching device (teaching pendant, tablet terminal device, etc.).

[0040] In addition, each positioning command IN P In the code "MOVE[TPn] VELOCITY[Vn]" (n=1,2,3,4), the code "[Vn]" that specifies the velocity V contains the velocity V n Alternatively, the maximum velocity V at which the robot 12 moves the welding gun 14 may be written in "[Vn]". MAX The percentage may be stated (e.g., "80%").

[0041] Or, similar to the position data table 202 described above, the velocity V n A velocity data table storing the velocity data together with the identifier "Vn" may be prepared in advance as data separate from the welding operation program 200. In this case, the processor 50 executes the positioning instruction IN "MOVE[TPn] VELOCITY[Vn]" on the 2i-1th line (i=1, 2, 3, 4). PWhen the speed data table is referenced, the speed V with the identifier "Vn" is read. n The speed V defined in the welding operation program 200 is obtained from the speed data table. n : "VELOCITY[Vn]" may be different from each other, or at least two (for example, all) velocities V n may be the same.

[0042] Referring again to FIG. 6, in welding operation program 200, the code "GUN[ON] CONDITION[1]" in the 2ith line (i=1, 2, 3, 4) is a welding command IN for starting welding gun 14 and welding a workpiece in accordance with welding condition 1 assigned identifier [1]. W is.

[0043] Here, multiple types of workpieces having various thicknesses and materials can be welded. In this embodiment, multiple different welding conditions m (m=1, 2, 3, . . .) are set in advance for each type of workpiece. Figure 8 shows an example of welding condition 1 assigned with identifier [1].

[0044] The welding condition 1 has parameters set as follows: welding pressure F1=2 [kN], welding current I1=8 [kA], and welding time t1=10 [sec]. The data table of welding condition m (pressure F1) is shown in FIG. m , welding current I m , welding time t m ) are prepared in advance for each type of workpiece (i.e., thickness, material) and stored in the memory 52. ​​The welding conditions m include the pressure F m , welding current I m , and welding time t m Any other parameters (for example, welding voltage, etc.) may be set.

[0045] When the welding operation program 200 is executed, the processor 50 executes the welding instruction IN "GUN [ON] CONDITION [1]" on the 2i-th line. WWhen this is read, the data table for welding condition 1, which has been assigned identifier [1], is referenced, and the parameters for welding condition 1, namely, welding force F1=2 [kN], welding current I1=8 [kA], and welding time t1=10 [sec], are obtained.

[0046] Then, the processor 50 calculates the welding force command F corresponding to the welding force F1 specified in the welding condition 1. C_1 (=2[kN]) is generated, and the pressure command F C_1 The servo motor 40 of the welding gun 14 is driven in accordance with the command, and the workpiece is clamped between the movable welding tip 44 and the fixed welding tip 36.

[0047] On the other hand, the servo motor 40 of the welding gun 14 is provided with a load detection sensor LS (not shown) that detects the load torque, feedback current, etc. of the servo motor 40. The processor 50 obtains feedback FB1 (i.e., the load torque, feedback current, etc.) from the load detection sensor LS.

[0048] Here, the pressure command F to the servo motor 40 C and the pressure command F C A calibration operation is performed in advance to match the welding force F generated by the welding gun 14 driven according to the welding force F. This calibration operation is performed, for example, with the welding gun 14 placed in a predetermined reference position OR0 by the robot 12. This reference position OR0 is, for example, the position shown in FIG.

[0049] In this calibration operation, the operator sets the welding force sensor 16 between the movable welding tip 44 and the fixed welding tip 36 of the welding gun 14 placed in the reference position OR0, and issues a welding force command F C The welding force F when the welding gun 14 is driven in accordance with the above is measured by the welding force sensor 16. The operator obtains the correlation between the feedback FB1 from the load detection sensor LS at this time and the measured welding force F, and determines the welding force command F C The correlation is calibrated so that the pressure F and the pressure V coincide with each other.

[0050] The processor 50 receives the welding command IN W According to the pressure command F C_1 While the servo motor 40 is being driven, a feedback FB1 is obtained from the load detection sensor LS, and the feedback FB1 corresponds to the pressure command F C_1 When the value corresponding to the value of the servo motor 40 is reached, the servo motor 40 is stopped.

[0051] Next, processor 50 energizes fixed welding tip 36 and movable welding tip 44 in accordance with welding current I1 (=8 kA) specified in welding condition 1, and welds the workpiece for welding time t1 (=10 seconds). W By executing the above, welding work is performed on the workpiece.

[0052] In step S1, the processor 50 executes the positioning command IN P and welding instructions IN W For example, the welding operation program 200 is stored in advance in the memory 52, and the processor 50 acquires the welding operation program 200 by reading it from the memory 52.

[0053] Alternatively, welding operation program 200 may be stored in another computer (such as a host controller, a production control server, or a teaching device). The other computer may be communicatively connected to I / O interface 54 of control device 18 via a communication network (such as the Internet or a LAN). Processor 50 may obtain welding operation program 200 by downloading it from the other computer.

[0054] In step S2, the processor 50 executes the positioning instruction IN of the welding operation program 200. P In this embodiment, in step S2, the processor 50 executes the positioning instruction IN "MOVE [TP1] VELOCITY [V1]" specified in the first line of the welding operation program 200. Pis read out, and the robot 12 moves the welding gun 14 at a speed V1 to position it at the first taught position TP1 and taught attitude OR1. The processor 50 The teaching posture OR specified in the welding work program 200 n The robot 12 functions as an operation execution unit 62 (FIG. 2) that operates the robot 12 to position the welding gun 14.

[0055] In step S3, the processor 50 moves the welding gun 14 to the n-th teaching position TP n and teaching posture OR n Specifically, the processor 50 determines whether the welding gun 14 has been positioned to the n-th teaching position TP based on feedback FB2 (for example, position feedback, velocity feedback, or acceleration feedback of the servo motor 30) from a rotation detection sensor RS1 (encoder, Hall element, or the like) provided on each servo motor 30 of the robot 12. n and teaching posture OR n It can be determined whether or not the positioning has been completed.

[0056] For example, when step S3 is executed after step S2, processor 50 determines whether welding gun 14 has been positioned to the first taught position TP1 and taught attitude OR1. n and teaching posture OR n If it is determined that the welding gun 14 has been positioned at the n-th teaching position TP (i.e., YES), the operation of the robot 12 is stopped and the process proceeds to step S4. n and teaching posture OR n On the other hand, if the processor 50 determines that the answer is NO, it loops step S3.

[0057] When the determination in step S3 is YES, the processor 50 executes the positioning command IN executed in step S2 (or the most recently executed step S8 described below) in the welding operation program 200. P The welding instructions specified in the next line of INW However, in the flow of FIG. 5, the processor 50 reads out this welding instruction IN W Instead, the pressure acquisition operation FO is performed.

[0058] In this embodiment, the control device 18 receives the welding command IN W Instead of the flag FL, a flag FL is set to execute a welding force acquisition operation FO, which will be described later. When the flag FL is enabled, the processor 50 executes the welding command IN that was read out when the determination in step S3 is YES. W Instead, steps S4 to S7, which will be described later, are executed as the pressure obtaining operation FO.

[0059] For example, the operator or the upper controller may be configured to send a flag setting signal to the control device 18, and the processor 50 may be configured to switch the flag FL between enabled and disabled in response to the flag setting signal. When executing the flow of FIG. 5, the operator or the upper controller may provide the control device 18 with a flag setting signal for enabling the flag FL, and the processor 50 sets the flag FL to enabled in response to the flag setting signal. Therefore, when the determination in step S3 during execution of the flow of FIG. 5 is YES, the processor 50 issues a welding command IN W Instead, steps S4 to S7 are executed as the pressure obtaining operation FO.

[0060] In step S4, processor 50 determines whether a command to start the welding force acquisition operation has been received from the operator. For example, processor 50 generates an image or audio notification signal SG1 stating, "Please set the welding force sensor between the movable welding tip and the fixed welding tip," and displays the notification signal SG1 as an image on display device 60 or outputs it as audio from a speaker (not shown) provided in control device 18.

[0061] The operator manually sets the welding force sensor 16 between the movable welding tip 44 and the fixed welding tip 36, and operates the input device 58 to give a command to start the welding force acquisition operation to the processor 50. If the processor 50 receives the command to start the welding force acquisition operation, it determines YES and proceeds to step S5, but if it determines NO, it loops back to step S4.

[0062] In step S5, the processor 50 calculates the welding pressure F specified in the welding condition m. m The pressure command F corresponding to C_m Specifically, the processor 50 drives the welding gun 14 in accordance with the welding command IN (first pressure command) read out when the determination in the most recent step S3 is YES. W In response to the code "CONDITION[1]" in the above, the welding force F1 (=2 [kN]) specified in the welding condition 1 to which the identifier [1] is assigned is acquired. Then, the processor 50 acquires the welding force command F1 corresponding to the welding force F1 acquired from the welding condition 1. C_1 (=2[kN]) is generated, and the pressure command F C_1 The servo motor 40 of the welding gun 14 is driven in accordance with the above.

[0063] On the other hand, while the servo motor 40 is being driven, the processor 50 acquires a feedback FB1 from the load detection sensor LS, and the feedback FB1 is used to generate a pressure command F C_1 As a result, the welding force sensor 16 is clamped between the movable welding tip 44 and the fixed welding tip 36, and the welding force command F C_1 A pressure F according to the pressure is applied.

[0064] In step S6, the pressure force F is acquired. Specifically, the processor 50 acquires the pressure force F measured by the pressure force sensor 16 at the end of step S5 (i.e., when the servo motor 40 is stopped) from the pressure force sensor 16 and stores it in the memory 52. ​​In this manner, in this embodiment, the processor 50 acquires the pressure force F measured by the pressure force sensor 16 at the most recent step S2 (or step S8 described later) at the n-th taught position TPn and teaching posture OR n The welding gun 14 positioned at the pressure command F C_1 The pressure sensor 16 acquires the pressure F actually measured when the actuator is driven at this speed.

[0065] Therefore, processor 50 functions as a pressure acquisition unit 64 (FIG. 2) that acquires the pressure F. Even if the above-described calibration work is performed, the pressure F acquired in step S6 is not necessarily the same as the pressure F acquired in the nth taught posture OR at which welding gun 14 is positioned. n According to the pressure command F C_1 (That is, it may differ from the applied pressure F1=2 [kN] specified in welding condition 1).

[0066] In step S7, the processor 50 calculates all teaching positions TP defined in the welding operation program 200. n and teaching posture OR n If the determination is YES, the processor 50 ends the flow shown in FIG. 5, whereas if the determination is NO, the processor 50 proceeds to step S8.

[0067] In step S8, the processor 50 executes the positioning instruction IN P For example, when executing step S8 for the first time, the processor 50 executes the positioning instruction IN P "MOVE [TP2] VELOCITY [V2]" is executed to move the welding gun 14 at a velocity V2 to position it at the second taught position TP2 and taught attitude OR2.

[0068] Then, processor 50 returns to step S3. In this manner, processor 50 repeatedly executes the loop of steps S3 to S8 until determining YES in step S7, and executes step S8 to move welding gun 14 to the n-th taught position TP n and teaching posture OR n Each time positioning is performed, the applied pressure F is acquired in step S6.

[0069] After the flow shown in Fig. 5 is completed, processor 50 executes welding operation program 200 and performs actual welding on the workpiece. When performing actual welding, an operator or a higher-level controller provides control device 18 with a flag setting signal for invalidating flag FL, and processor 50 invalidates flag FL in response to the flag setting signal. As a result, processor 50 invalidates welding command IN of welding operation program 200 during the actual welding. W By executing the above, welding work is performed on the workpiece.

[0070] In this embodiment, when the welding operation program 200 is executed for the actual welding operation, the processor 50 determines the welding force command F based on the welding force F acquired in step S6. C_1 For example, in step S2 or S8, the positioning instruction IN P Execute the above to move the welding gun 14 to the nth teaching position TP n and teaching posture OR n It is assumed that the applied pressure F obtained in step S6 immediately after positioning is 1.5 kN.

[0071] In this case, the processor 50 executes the positioning instruction IN 2i-1 in the actual welding operation. P The welding instruction in the 2ith line after W The welding force command F for driving the servo motor 40 of the welding gun 14 when C_1 (=2[kN]), the correction amount ΔF is calculated by, for example, calculating the obtained pressure F and the pressure command F C_1 The difference between these is calculated as ΔF (=0.5 kN).

[0072] Then, the processor 50 calculates the pressure command F C_1 is corrected by adding a correction amount ΔF, and a new pressure command F C_1 ' = 2.5 [kN] (second pressure command). The correction amount ΔF is calculated by subtracting the pressure F from the pressure command F C_1 The difference between the pressure force F and the pressure force command F may be a value obtained by multiplying the difference by a predetermined coefficient, for example.C_1 It may be obtained by any other calculation using

[0073] Then, the processor 50 executes the welding instruction IN W When executing, the corrected pressure command F C_1 ' (=2.5 [kN]) to drive the servo motor 40. n Therefore, the welding gun 14 positioned at the welding position can apply a pressure F to the workpiece to substantially match the pressure F1 specified in the welding condition 1.

[0074] In this manner, in this embodiment, the processor 50 determines the first pressure force command F based on the pressure force F acquired in step S6. C_1 By correcting the above, the teaching posture OR n The second pressure command F when driving the welding gun 14 is C_1 '.

[0075] As described above, in this embodiment, the processor 50 functions as the operation execution unit 62, the pressure acquisition unit 64, and the command correction unit 66 to obtain the pressure command F that defines the pressure F of the welding gun 14. C is corrected in accordance with the attitude OR of the welding gun 14. Therefore, the operation execution unit 62, the welding force acquisition unit 64, and the command correction unit 66 correct the welding force command F C The present invention provides a device 70 (FIG. 2) for correcting the above.

[0076] In this device 70, the operation execution unit 62 executes the teaching posture OR defined in the welding operation program 200. n The robot 12 is operated so as to position the welding gun 14 at the teaching position (steps S2 and S8), and the pressure acquisition unit 64 receives the pressure from the operation execution unit 62 and performs the teaching operation. n When the welding gun 14 is positioned at the first pressure command F C_1The pressure F when driven at the pressure F is acquired (step S6). Then, the command corrector 66 calculates a first pressure command F based on the pressure F acquired by the pressure acquisition unit 64. C_1 By correcting the above, the teaching posture OR n The second pressure command F when driving the welding gun 14 is C_1 ' is required.

[0077] According to this configuration, the teaching posture OR for positioning the welding gun 14 in the actual welding work is n Based on the pressure F obtained in C_1 This allows the second welding force command F to be corrected, which can generate a constant welding force F in the welding gun 14 regardless of the position of the welding gun 14 in the actual welding operation. C_1 ' can be calculated with high accuracy. C_1 Since it is not necessary to newly teach the robot 12 a posture for correcting the force command F C_1 This simplifies the process of correcting the above.

[0078] In addition, in the apparatus 70, the welding operation program 200 operates the robot 12 to move the welding gun 14 to the n-th teaching position TP n and teaching posture OR n Positioning instruction IN P and a welding command IN to start the welding gun 14 and weld the workpiece. W The operation execution unit 62 then executes the positioning command IN of the welding operation program 200. P By executing the above, the robot 12 moves the welding gun 14 to the n-th teaching position TP n and teaching posture OR n (Steps S2, S8) Meanwhile, the welding command IN W is not executed (steps S4 to S7).

[0079] Then, the pressing force acquisition unit 64 receives the pressing force from the operation execution unit 62 and moves the welding gun 14 to the n-th teaching position TP n and teaching posture OR nAccording to this configuration, the pressing force F when the robot 12 is positioned at the position indicated by the arrow is acquired (step S6). C_1 Therefore, at the welding site, the operation of acquiring the pressing force F can be performed while avoiding interference between the robot 12 and peripheral equipment.

[0080] In the apparatus 70, the pressure acquisition unit 64 acquires the n-th teaching posture OR n The welding gun 14 positioned at the first pressure command F C_1 According to this configuration, the pressure sensor 16 can measure the pressure F with high accuracy, so the second pressure command F C_1 ' can be calculated with higher accuracy.

[0081] In the above-described embodiment, an operation program PG1 for executing the pressing force acquisition operation FO (steps S4 to S7) may be prepared separately from welding operation program 200. In this case, when processor 50 determines YES in step S3, it executes operation program PG1 and executes steps S4 to S7 as the pressing force acquisition operation FO.

[0082] In the above embodiment, the flag FL is set in the control device 18. However, the present invention is not limited to this. In the welding operation program 200 acquired in step S1, each welding command IN W The code: "GUN[ON] CONDITION[1]" may be assigned a flag FL for alternatively executing the welding force acquisition operation FO. Then, the processor 50 reads out the welding command IN when the determination in step S3 is YES. W The welding command IN is executed by referring to the flag FL assigned to the W Instead, steps S4 to S7 may be executed as the pressure obtaining operation FO.

[0083] Then, when executing welding operation program 200 to perform an actual welding operation, flag FL may be deleted from welding operation program 200. Alternatively, processor 50 may delete the welding instruction IN of welding operation program 200. W When executing the welding command IN, the flag FL is ignored. W may be executed.

[0084] Furthermore, in the above-described embodiment, the case has been described in which the pressure sensor 16 is connected to the I / O interface 54 of the control device 18 and supplies the measured pressure F to the control device 18. However, this is not limiting, and the pressure sensor 16 does not have to be connected to the control device 18. In this case, the operator may manually input the pressure F measured by the pressure sensor 16 at the end of the above-described step S5 into the control device 18 by operating the input device 58.

[0085] In the above embodiment, the welding robot system 10 is provided with a pressure sensor 16 that is independent of the welding gun 14, and an operator manually sets the pressure sensor 16. However, the pressure sensor 16 may be integrally incorporated into the welding gun 14.

[0086] Such a configuration is shown in Fig. 9. In the welding robot system 10' shown in Fig. 9, the pressing force sensor 16' is fixed integrally to the movable arm 38 together with the movable welding tip 44. When the movable welding tip 44, driven by the servo motor 40, presses the object to be pressed (e.g., the fixed welding tip 36), the pressing force sensor 16' is configured to measure the pressing force F applied to the object to be pressed by detecting the force acting on the pressing force sensor 16' as a reaction force.

[0087] According to this welding robot system 10', step S4 can be omitted from the flow of Fig. 5. Specifically, when the determination in step S3 is YES, the processor 50 executes step S5 and issues a pressure command F C_1The servo motor 40 of the welding gun 14 is driven in accordance with the load command F. As a result, the movable welding tip 44 is pressed against the fixed welding tip 36, which is the object to be pressed, and presses the fixed welding tip 36. Then, the processor 50 calculates the force command F based on the feedback FB1 obtained from the load detection sensor LS. C_1 When the value corresponding to the value of the servo motor 40 is reached, the servo motor 40 is stopped.

[0088] When performing step S5, an object to be pressed (such as a steel plate) separate from the welding gun 14 may be inserted between the movable welding tip 44 and the fixed welding tip 36, and the movable welding tip 44 may pressurize the object. Next, in step S6, the processor 50 acquires the applied pressure F measured by the applied pressure sensor 16' at this time. The applied pressure sensor 16' may be fixed between the fixed welding tip 36 and the fixed arm 34.

[0089] Next, a welding robot system 80 according to another embodiment will be described with reference to Figures 10 and 11. The welding robot system 80 differs from the above-described welding robot system 10 in the following configuration. Specifically, the welding robot system 80 does not include the above-described pressure sensor 16, but the welding gun 14 includes a position sensor 68.

[0090] Position sensor 68 detects position PS of movable welding tip 44. As an example, position sensor 68 has a rotation detection sensor RS2 (encoder, Hall element, etc.) provided on servo motor 40 of welding gun 14, and detects the rotational position (or rotation angle) of servo motor 40. Since the rotational position of servo motor 40 correlates with the positions of movable arm 38 and movable welding tip 44 in the direction of gun axis A2, position sensor 68 in this example can detect position PS of movable welding tip 44 by detecting the rotational position of servo motor 40.

[0091] As another example, position sensor 68 is provided on welding gun 14 (e.g., base 32) and has a linear scale SC that can directly detect the position PS of movable arm 38 or movable welding tip 44 in the direction of gun axis A2. Position sensor 68 (rotation detection sensor RS2 or linear scale SC) supplies detection data of the detected position PS to control device 18.

[0092] Next, referring to FIG. 12, in the welding robot system 80, a pressure command F C 12, the same processes as those in the flow shown in FIG. 5 are denoted by the same step numbers, and duplicated explanations will be omitted. After the flow shown in FIG. 12 starts, processor 50 executes step S1 and acquires welding operation program 200.

[0093] In this embodiment, the processor 50 analyzes the acquired welding operation program 200 and W Processor 50 then refers to the code "CONDITION[1]" in the data table for welding condition 1. Processor 50 then retrieves information on welding pressure F1 (=2 [kN]) included in welding condition 1 to which identifier [1] in the code is assigned from the data table for welding condition 1 (FIG. 8).

[0094] After step S1, in step S11, processor 50 positions welding gun 14 in reference position OR0. Specifically, processor 50 operates robot 12 to position welding gun 14 in reference position OR0 shown in Fig. 3. As a result, gun axis A2 of welding gun 14 becomes parallel to the vertical direction, and movable welding tip 44 is aligned vertically above fixed welding tip 36.

[0095] In step S12, the processor 50 calculates the welding pressure F m The pressure command F corresponding to C_mSpecifically, based on the information on the welding pressure F1 included in the welding condition 1 acquired in step S1, the processor 50 determines the welding pressure command F corresponding to the welding pressure F1. C_1 (=2[kN]) is generated, and the pressure command F C_1 The servo motor 40 of the welding gun 14 is driven in accordance with the above.

[0096] As a result, the movable welding tip 44 is pressed against the fixed welding tip 36 as the object to be pressed. Then, the processor 50 determines whether the feedback FB1 from the load detection sensor LS is equal to the welding force command F C_1 When the value corresponding to the welding force F1 is reached, the servo motor 40 is stopped. As a result, the welding force F1 is applied from the movable welding tip 44 to the welding force sensor 16.

[0097] Here, by the above-described calibration work, the welding gun 14 placed in the reference posture OR0 is adjusted to the welding force command F C The pressure F when driven and the pressure command F C Therefore, the pressure F applied to the pressure sensor 16 in step S12 is the pressure command F C_1 The welding pressure F1 (= 2 kN) of welding condition 1 corresponds to the above.

[0098] In step S13, processor 50 acquires the first position PS1 of the movable welding tip 44. Specifically, processor 50 acquires from position sensor 68 the first position PS1 (or the rotational position) detected by position sensor 68 at the end of step S12 (i.e., when servo motor 40 is stopped).

[0099] In this manner, in this embodiment, the processor 50 controls the welding gun 14 positioned in the reference posture OR0 to move in accordance with the first pressure command F C_1 The movable welding tip 44 is driven by the movable welding tip 44 and functions as a position acquisition unit 72 (FIG. 11) that acquires a first position PS1 detected by the position sensor 68 when the movable welding tip 44 presses an object to be pressed (specifically, the fixed welding tip 36).

[0100] After step S13, the processor 50 sequentially executes steps S2, S3, and S5 described above. As a result, the n-th teaching position TP n and teaching posture OR n The welding gun 14 positioned at the welding pressure command F C_1 (=2 kN) so that the movable welding tip 44 applies a pressure force F to the fixed welding tip 36 as the object to be pressed. The pressure force F at this time is n According to the pressure command F C_1 (That is, the applied pressure F1 of welding condition 1 = 2 [kN]) may be different.

[0101] In step S14, the processor 50 functions as the position acquisition unit 72 and acquires the second position PS2 of the movable welding tip 44. Specifically, the processor 50 acquires from the position sensor 68 the second position PS2 (or the rotational position) detected by the position sensor 68 at the end of step S5 (i.e., when the servo motor 40 is stopped).

[0102] As described above, the welding force F with which the movable welding tip 44 presses the fixed welding tip 36 when step S14 is performed may differ from the welding force F1 when step S13 is performed. Therefore, the second position PS2 obtained in step S14 may differ from the first position PS1 obtained in step S13.

[0103] In this way, the processor 50 functions as the position acquisition unit 72 and acquires the n-th teaching posture OR n The welding gun 14 positioned at the first pressure command F C_1 When the movable welding tip 44 is driven by the welding motor 62 and pressurizes the workpiece (specifically, the fixed welding tip 36), the second position PS2 detected by the position sensor 68 is acquired.

[0104] In step S15, processor 50 functions as pressure acquisition unit 64 and acquires pressure F. Here, there is a relationship shown in the following formula 1 among first position PS1 acquired in step S13, second position PS2 acquired in step S14, pressure F1 defined in welding condition 1 acquired in step S1, and pressure F acquired in step S15. PS1 / PS2=F1 / F (Formula 1)

[0105] By the above-mentioned calibration work, the pressure force F1 in the formula 1 is calculated as the pressure force command F C_1 = 2 [kN] and is known. Therefore, from Equation 1, the applied pressure F can be calculated by the formula F = F1 · PS2 / PS1. The processor 50 stores the calculated applied pressure F in the memory 52.

[0106] After step S15, the processor 50 sequentially executes the above-described steps S7 and S8, and repeatedly executes the loop of steps S3, S5, S14, S15, S7, and S8 until the determination in step S7 is YES. In step S8, the processor 50 moves the welding gun 14 to the n-th teaching position TP n and teaching posture OR n Each time positioning is performed, the applied pressure F is acquired in step S15.

[0107] After the flow shown in FIG. 12 is completed, processor 50 executes welding operation program 200 for the actual welding operation, as in the above-described embodiment, and during the execution of welding operation program 200, functions as command corrector 66 to correct each teaching posture OR based on welding force F acquired in step S15. n Pressure command F C_1 By correcting the force command F C_1 ' is required.

[0108] As described above, in this embodiment, the processor 50 functions as the operation execution unit 62, the pressure acquisition unit 64, the command correction unit 66, and the position acquisition unit 72, thereby determining the pressure command F in accordance with the attitude OR of the welding gun 14. CTherefore, the operation execution unit 62, the welding force acquisition unit 64, the command correction unit 66, and the position acquisition unit 72 correct the welding force command F in accordance with the attitude OR of the welding gun 14. C The present inventors have constructed a device 90 (FIG. 11) for correcting the above.

[0109] In this apparatus 90, the position acquisition unit 72 adjusts the welding gun 14 positioned in the reference posture OR0 to the first pressure force command F C_1 When the movable welding tip 44 is driven by the welding motor 64 and presses the workpiece (fixed welding tip 36), a first position PS1 detected by the position sensor 68 is obtained (step S13).

[0110] In addition, the position acquisition unit 72 acquires the n-th teaching posture OR n The welding gun 14 positioned at the first pressure command F C_1 The welding force acquisition unit 64 then acquires the second position PS2 detected by the position sensor 68 when the workpiece is pressed by the movable welding tip 44 (step S14). Then, the welding force acquisition unit 64 determines the n-th teaching posture OR based on the first position PS1 and the second position PS2. n The applied pressure F at this point is calculated by a predetermined calculation (specifically, calculation using the above-mentioned formula (1)) (step S15).

[0111] According to this configuration, the teaching posture OR can be obtained without using a physical sensor such as the pressure sensor 16 described above. n Therefore, the operator does not have to manually set the pressure sensor 16, and the flow of FIG. 12 can be effectively automated, so the work of obtaining the pressure F can be simplified.

[0112] In the above-described embodiment, the processor 50 executes step S2 or S8 to move the welding gun 14 to all teaching positions TP n and teaching posture OR n and acquires the applied force F in step S6 or S15. However, the present invention is not limited to this. The processor 50 may also function as the command corrector 66 to n and teaching posture ORn Pressure command F C_1 When the pressure command F C_1 ' and the nth teaching position TP n and k (k≠n) teaching position TP k Based on this, the kth teaching position TP k and teaching posture OR k Pressure command F C_1 ' can also be estimated.

[0113] For example, in step S2, processor 50 positions welding gun 14 at first taught position TP1 and taught attitude OR1, and acquires welding force F in the above-described step S6 or S15. Then, during actual welding work, processor 50 generates a first welding force command F based on the acquired welding force F. C_1 By correcting the above, the pressure command F C_1 Suppose we ask for '.

[0114] In this case, the processor 50 calculates the calculated pressure command F C_1 ' and the first taught position TP1 and the second taught position TP2 (specifically, the coordinates of the robot coordinate system C1) defined in the welding operation program 200, a predetermined calculation is performed using a predetermined approximation formula to calculate a second pressing force command F at the second taught position TP2 and the second taught attitude OR2. C_1 This approximate expression is, for example, an expression that represents the change (for example, linear change) of the applied pressure F from the first taught position TP1 to the second taught position TP2, and is determined in advance by the operator.

[0115] In this case, processor 50, as operation execution unit 62, does not execute the operation of positioning welding gun 14 at second taught position TP2 and second taught attitude OR2 in step S8. With this configuration, it is possible to cancel the positioning operation in step S8 and the operation of acquiring welding force F in step S15 for second taught attitude OR2. friend , the second pressure command F in the second teaching posture OR2 C_1 ' can be estimated with high accuracy.

[0116] Next, other functions of welding robot system 80 will be described with reference to Figures 13 and 14. Welding robot system 80 further executes the flow shown in Figure 14. In the flow shown in Figure 14, the same processes as in Figure 12 are assigned the same step numbers, and duplicated explanations will be omitted.

[0117] 14, when the determination in step S7 is NO, the processor 50 executes step S21. In step S21, the processor 50 executes the positioning instruction IN P The teaching postures OR1, OR2, ... OR n and the next positioning instruction to be executed is IN P The teaching posture specified in OR n+1 Calculate the difference φ between

[0118] For example, in step S2, the processor 50 executes the positioning instruction IN P After positioning the welding gun 14 at the first teaching position TP1 and teaching attitude OR1 by the above steps, steps S3, S5, S14, S15 and S7 are executed, and step S Let's say you go to 21.

[0119] In this case, in step S21, the processor 50 executes the positioning instruction IN P The first teaching posture OR1 defined in and the positioning command IN of the third line to be executed next. P The difference φ between the second teaching posture OR2 defined in 1_2 Specifically, the processor 50 calculates the positioning instruction IN P : The code "MOVE[TP2] VELOCITY[V2]" is referenced, and the coordinates (X2, Y2, Z2, W2, P2, R2) represented by the identifier "TP2" are obtained from the position data table 202.

[0120] Then, the processor 50 executes the most recently executed positioning instruction INP and the coordinates (W2, P2, R2) of the second teaching orientation OR2 obtained from the position data table 202. 1_2 Ask for.

[0121] Below, the difference φ 1_2 An example of a method for calculating the coordinates (W1, P1, R1) of the first teaching attitude OR1 will be described. First, the processor 50 expresses the coordinates (W1, P1, R1) of the first teaching attitude OR1 as a 3×3 matrix M1. In this matrix M1, a vector V 1_1 is a unit vector that indicates the rotation component around the x-axis of the tool coordinate system C2, and is the vector V 1_2 is a unit vector that indicates the rotation component around the y-axis of the tool coordinate system C2, and is the vector V 1_3 is a unit vector indicating the rotation component around the z-axis of the tool coordinate system C2.

[0122] Similarly, the processor 50 expresses the coordinates (W2, P2, R2) of the second teaching orientation OR2 as a 3×3 matrix M2. Then, the processor 50 calculates the vector V in the first column of the matrix M1. 1_1 and the vector V in the first column of matrix M2 2_1 This dot product IP1 is the vector V 1_1 and vector V 2_1 The angle with x Then, cosφ x This angle φ x is the difference φ between the first teaching attitude OR1 and the second teaching attitude OR2 in the direction around the x-axis of the tool coordinate system C2. 1_2 The processor 50 calculates the calculated inner product IP1=cosφ. x From this, angle φ x =cos -1 (IP1) can be calculated.

[0123] Similarly, the processor 50 calculates the vector V in the second column of the matrix M1. 1_2and the vector V in the second column of the matrix M2 2_2 This dot product IP2 is the vector V 1_2 and vector V 2_2 The angle with y Then, cosφ y This angle φ y is the difference φ between the first teaching attitude OR1 and the second teaching attitude OR2 in the direction around the y axis of the tool coordinate system C2. 1_2 The processor 50 calculates the calculated inner product IP2=cosφ. y From this, angle φ y =cos -1 (IP2) can be calculated.

[0124] In this way, the processor 50 calculates the difference φ between the first taught attitude OR1 and the second taught attitude OR2. 1_2 As the angle φ x and φ y Therefore, the processor 50 calculates the difference φ between the first taught attitude OR1 and the second taught attitude OR2. 1_2 The method for calculating the difference φ described above is just an example, and the processor 50 may calculate the difference φ by any other method.

[0125] In step S22, the processor 50 determines whether the difference φ calculated in step S21 is equal to or smaller than a predetermined threshold φ th For example, if the processor 50 determines in the immediately preceding step S21 that the difference φ between the first taught attitude OR1 and the second taught attitude OR2 is smaller than 1_2 As the angle φ x and φ y Suppose we ask for

[0126] In this case, the processor 50 calculates the angle φ x is a predetermined threshold φ th_x is smaller than (i.e., φ x <φ th_x ) and the angle φ y is a predetermined threshold φ th_y is smaller than (i.e., φy <φ th_y ) or not. x <φ th_x , and φ y <φ th_y If the above condition is satisfied, the difference φ between the first teaching posture OR1 and the second teaching posture OR2 is 1_2 is the threshold φ th (i.e., YES). On the other hand, x ≧φ th_x , or φ y ≧φ th_y If the above condition is satisfied, the processor 50 calculates the difference φ between the first taught attitude OR1 and the second taught attitude OR2. 1_2 is the threshold φ th It is determined that the answer is equal to or greater than this (i.e., NO).

[0127] In this manner, in this embodiment, the processor 50 calculates the difference φ 1_2 is a predetermined threshold value φ th If the result of the determination in step S22 is NO, the processor 50 proceeds to step S8. Then, in step S8, the processor 50 determines whether the positioning instruction IN P is executed to move the welding gun 14 to the second taught position TP2 and the second taught attitude OR2, and the process returns to step S3.

[0128] On the other hand, if the determination in step S22 is YES, the processor 50 returns to step S7. That is, in this embodiment, the processor 50 calculates the difference φ between the first teaching attitude OR1 and the second teaching attitude OR2. 1_2 If is small (in other words, if the two orientations OR1 and OR2 are similar), the positioning command IN P and the operation of acquiring the pressing force F at the second taught position TP2 and the second taught attitude OR2 in step S15 are not performed. Then, in step S7, the processor 50 regards the pressing force F as having been acquired for the second taught position TP2 and the taught attitude OR2.

[0129] In this way, in this embodiment, the positioning command IN P The teaching postures OR1, OR2...OR n and the next positioning instruction to be executed, IN P The teaching posture specified in OR n+1 If the difference φ is small, the next positioning command IN P The operation to obtain the applied pressure F is canceled without executing the above.

[0130] For example, the four teaching postures shown in Fig. 7 n Among these, the difference φ between the first teaching posture OR1 and the second teaching posture OR2 1_2 However, as mentioned above, the threshold φ th In this case, the processor 50 executes the positioning instruction IN P After positioning the welding gun 14 at the third taught position TP3 and taught attitude OR3, steps S3, S5, S14, S15 and S7 are executed, and the process proceeds to step S21.

[0131] In this case, in step S21, the processor 50 executes the positioning instruction IN P The first teaching posture OR1 defined in the 7th line of the positioning command IN P The difference φ between the fourth teaching posture OR4 defined in 1_4 , and the already executed positioning instruction IN on the third line P As stipulated in The The difference φ between the third teaching posture OR3 and the fourth teaching posture OR4 3_4 are calculated respectively.

[0132] Then, in step S22, the processor 50 calculates the difference φ 1_4 and the difference φ 3_4 At least one of the thresholds φ th In this case, the processor 50 determines that the value is YES in accordance with the positioning instruction IN PIn other words, in this embodiment, the processor 50 does not execute the above process, and cancels step S15 of acquiring the applied force F in the fourth teaching posture OR4. th (That's all) Teaching posture OR n In step S15, the applied pressure F is acquired only for the above.

[0133] After the flow of FIG. 14, processor 50 executes welding operation program 200 for the actual welding operation, and during the execution of welding operation program 200, processor 50 functions as command corrector 66 to correct each teaching posture OR based on welding force F acquired in step S15. n Pressure command F C_1 By correcting the force command F C_1 ' is required.

[0134] In this embodiment, the processor 50 selects a plurality of teaching postures OR that have small differences φ (i.e., are similar) from each other. n For example, in step S22, the difference φ between the first teaching attitude OR1 and the second teaching attitude OR2 is 1_2 Since the value of F is small, the answer is YES, and the operation of acquiring the applied pressure F in step S15 is canceled.

[0135] In this case, the processor 50 functions as a command corrector 66 and calculates a pressure command F for driving the welding gun 14 in the second taught attitude OR2 using the correction amount ΔF calculated for the first taught attitude OR1. C_1 For example, it is assumed that the correction amount ΔF obtained in the first teaching posture OR1 is ΔF=0.5 [kN] as described above.

[0136] In this case, the processor 50 executes the welding instruction IN W When the above is executed, a pressure command F for driving the welding gun 14 in the second teaching posture OR2 is C_1 (= 2 [kN]) is calculated by the correction amount ΔF (= 0.5 [kN]) to correct the force command F C_1Then, the processor 50 calculates the welding command IN ' on the fourth line. W When the above is executed, the welding gun 14 positioned in the second teaching posture OR2 is moved in accordance with the new pressure force command F C_1 '(=2.5[kN]) is driven.

[0137] Furthermore, in step S22, the difference φ between the first teaching attitude OR1 and the fourth teaching attitude OR4 is calculated. 1_4 Since the correction amount ΔF (=0.5 kN) obtained for the first teaching attitude OR1 is small, the determination is YES, and the operation of acquiring the welding force F in step S15 is canceled. In this case, the processor 50 functions as the command corrector 66, and calculates the welding force command F for driving the welding gun 14 in the fourth teaching attitude OR4 using the correction amount ΔF (=0.5 kN) obtained for the first teaching attitude OR1. C By correcting this, a new pressure command F C_1 '(=2.5[kN]) Ask for .

[0138] Then, the processor 50 executes the welding command IN W When the fourth teaching posture OR4 is executed, the welding gun 14 is moved to the fourth teaching posture OR4 in accordance with the new pressure force command F C_1 That is, in this case, the processor 50 uses a common correction amount ΔF (=0.5 [kN]) in the first teaching posture OR1, the second teaching posture OR2, and the fourth teaching posture OR4 to correct the original pressure force command F C_1 will be corrected.

[0139] In this embodiment, all teaching postures OR n The same pressure command F C_1 (That is, the welding force F1=2 [kN] of the welding condition 1 shown in FIG. 8) is predetermined. However, this is not limiting, and the teaching posture OR n Each time, a different pressure command F C_1 In this case, the teaching posture OR may be set in the data table of welding condition 1 shown in FIG. n Each pressure command F C_1 may be stored.

[0140] As described above, in this embodiment, the processor 50 functions as the operation execution unit 62, the pressure acquisition unit 64, the command correction unit 66, the position acquisition unit 72, the attitude difference calculation unit 74, and the difference determination unit 76, thereby determining the pressure command F in accordance with the attitude OR of the welding gun 14. C Therefore, the operation execution unit 62, the welding force acquisition unit 64, the command correction unit 66, the position acquisition unit 72, the attitude difference calculation unit 74, and the difference determination unit 76 correct the welding force command F in accordance with the attitude OR of the welding gun 14. C The present invention provides a device 100 (FIG. 13) for correcting the above.

[0141] In this apparatus 100, when the operation execution unit 62 positions the welding gun 14 in the first teaching attitude OR1, the pressing force acquisition unit 64 Kino The first pressing force F is acquired (step S15), and the command corrector 66 calculates a first pressing force command F for driving the welding gun 14 in the first teaching attitude OR1 based on the first pressing force F. C_1 (=2[kN]) is the second pressure command F C_1 Calculate the correction amount ΔF (=0.5 [kN]) to correct to ' (=2.5 [kN]).

[0142] On the other hand, the attitude difference calculation unit 74 calculates the difference φ between the first teaching attitude OR1 and the second teaching attitude OR2. 1_2 (step S21), and the difference determination unit 76 calculates the difference φ 1_2 is a predetermined threshold value φ th Then, the difference determining unit 76 determines whether the difference φ 1_2 is the threshold φ th If it is determined that the difference is smaller than the first teaching attitude OR2 (that is, YES in step S22), operation execution unit 62 does not execute the operation of positioning welding gun 14 in second teaching attitude OR2 (step S8).

[0143] Then, the command corrector 66 uses the correction amount ΔF calculated in the first teaching attitude OR1 to calculate a first pressing force command F for driving the welding gun 14 in the second teaching attitude OR2. C (=2 [kN]) is corrected to obtain the second pressure command FC_1 '(=2.5[kN]) is calculated.

[0144] According to this configuration, a plurality of teaching postures OR with small differences φ between them can be n 14. Therefore, the positioning operation in step S8 and the operation for obtaining the applied pressure F in step S15 can be canceled. This makes it possible to reduce the cycle time of the flow in FIG.

[0145] The difference determination unit 76 and the attitude difference calculation unit 74 of the device 100 can also be applied to the device 70 shown in Fig. 2. In this case, when the processor 50 determines NO in step S7 in Fig. 5, it executes steps S21 and S22 in Fig. 14, and when it determines YES in step S22, it returns to step S7, whereas when it determines NO, it proceeds to step S8.

[0146] In this embodiment, the processor 50 selects a plurality of teaching postures OR that have small differences φ (i.e., are similar) from each other. n However, the present invention is not limited to this. The processor 50 may be configured to use a common correction amount ΔF between a plurality of teaching postures OR where the difference φ is small. n If there is one teaching posture OR n The second pressure command F C_1 Based on the difference φ, other teaching postures OR n+1 Second pressure command F C_1 ' may be required.

[0147] For example, when the processor 50 determines the first pressure force command F C_1 By correcting the second pressure command F C_1 ' is obtained, and the difference φ between the first teaching posture OR1 and the second teaching posture OR2 is obtained. 1_2 (i.e., angle φ x and φ y ) is small. In this case, the processor 50 calculates the difference φ 1_2 Among these, the angle φ around the y-axis of the tool coordinate system C2, which is perpendicular to the gun axis A2 yIn response to this, the second pressure command F C_1 By linearly changing ', the second pressure command F C_1 ' may be required.

[0148] For example, if the second teaching orientation OR2 is the orientation shown in FIG. 4, and the first teaching orientation OR1 is rotated from the second teaching orientation OR2 to the orientation shown in FIG. 3 by an angle φ y In this case, the processor 50 functions as the command corrector 66 to correct the second pressure force command F C_1 ', angle φ y to In response, the second pressure command F C_1 ' may be linearly increased.

[0149] On the other hand, the first teaching attitude OR1 is the attitude shown in FIG. 4, and the second teaching attitude OR2 is the attitude shown in FIG. 3, which is changed from the first teaching attitude OR1 around the y axis of the tool coordinate system C2 by an angle φ y In this case, the processor 50 functions as the command corrector 66 to correct the second pressure force command F C_1 ', angle φ y In response, the second pressure command F C_1 ' may be linearly decreased to obtain the value.

[0150] In this manner, in this embodiment, the command corrector 66 calculates the second pressure command F C_1 ' and the difference φ (e.g., angle φ y ) and the second pressure command F C_1 According to this configuration, for the second teaching orientation OR2, the positioning operation in step S8 and the operation for obtaining the applied force F in step S15 can be canceled. friend , the second pressure command F in the second teaching posture OR2 C_1 ' can be calculated with high accuracy according to the difference φ.

[0151] The processor 50 selects a plurality of teaching postures OR whose difference φ is small. n If there is one teaching posture OR n Based on the correction amount ΔF and the difference φ obtained in step 2, other teaching postures OR n+1 For example, the correction amount ΔF may be calculated at the first teaching attitude OR1 as described above, and the difference φ between the first teaching attitude OR1 and the second teaching attitude OR2 may be calculated. 1_2 In this case, the processor 50 calculates the angle φ about the y-axis of the tool coordinate system C2 that is orthogonal to the gun axis A2. y By linearly changing the correction amount ΔF calculated in the first teaching posture OR1 in accordance with the above, the first pressure force command F C_1 A correction amount ΔF for correcting the above may be calculated.

[0152] For example, if the second teaching orientation OR2 is the orientation shown in FIG. 4, and the first teaching orientation OR1 rotates from the second teaching orientation OR2 toward the orientation shown in FIG. 3 at an angle φ y In this case, the processor 50 functions as the command corrector 66 and corrects the first pressure force command F C_1 The correction amount ΔF is calculated by the angle φ y The correction amount ΔF in the first teaching attitude OR1 may be obtained by linearly increasing the correction amount ΔF in accordance with the change in the first teaching attitude OR1.

[0153] On the other hand, the first teaching attitude OR1 is the attitude shown in FIG. 4, and the second teaching attitude OR2 is a position at an angle φ y In this case, the processor 50 functions as the command corrector 66 and corrects the first pressure force command F C_1 The correction amount ΔF is calculated by the angle φ y The correction amount ΔF in the first teaching attitude OR1 may be obtained by linearly decreasing the correction amount ΔF in accordance with the change in the first teaching attitude OR1.

[0154] Next, other functions of the welding robot system 10 will be described with reference to Figs. 15 to 17. The welding robot system 10 further executes the flow shown in Fig. 16. In this embodiment, the processor 50 executes the teaching posture OR defined in the welding operation program 200. n and reproduce each teaching posture OR n The posture reproduction program 204 for obtaining the applied force F is generated.

[0155] 16 starts, processor 50 executes step S1 to acquire welding operation program 200. In step S31, processor 50 acquires a teaching posture OR from welding operation program 200. n Specifically, the processor 50 analyzes the welding operation program 200 and extracts all the positioning instructions IN P Extract.

[0156] Then, the processor 50 executes the positioning command IN P The identifier [TPn] included in the code is extracted, and the teaching posture OR indicated by the identifier [TPn] is n from the position data table 202 (FIG. 7). As a result, the processor 50 extracts the coordinates (W1, P1, R1) representing the first taught posture OR1, the coordinates (W2, P2, R2) representing the second taught posture OR2, the coordinates (W3, P3, R3) representing the third taught posture OR3, and the coordinates (W4, P4, R4) representing the fourth taught posture OR4. In this way, in this embodiment, the processor 50 extracts the coordinates (W1, P1, R1) representing the first taught posture OR1, the coordinates (W2, P2, R2) representing the second taught posture OR2, the coordinates (W3, P3, R3) representing the third taught posture OR3, and the coordinates (W4, P4, R4) representing the fourth taught posture OR4 from the welding operation program 200. n It functions as a posture extractor 78 (FIG. 15) that extracts the

[0157] In step S32, processor 50 determines whether or not input of a posture reproduction position OP has been accepted. This posture reproduction position OP is a position (specifically, coordinates (X, Y, Z)) in robot coordinate system C1 that positions welding gun 14 (in other words, TCP) when a posture reproduction program 204 (FIG. 19) described later is executed.

[0158] For example, the processor 50 generates an input image IM for inputting the posture reproduction position OP, and displays it on the display device 60. While viewing the input image IM, the operator operates the input device 58 to provide an input specifying the coordinates of the posture reproduction position OP to the processor 50. Below, a case will be described in which the operator specifies the coordinates (X0, Y0, Z0) of the robot coordinate system C1 as the posture reproduction position OP.

[0159] The coordinates (X0, Y0, Z0) of this posture reproduction position OP are set to at least one (for example, all) of the teaching positions TP defined in the welding operation program 200. n (X n ,Y n ,Z n ) and the at least one teaching position TP n The coordinates are specified by the operator as coordinates closer to the origin of the robot coordinate system C1 (i.e., the robot base 20) than the coordinates of the robot base 20.

[0160] When the processor 50 receives the input of the attitude reproduction position OP from the operator, it determines YES and proceeds to step S33, whereas when it determines NO, it loops step S32. n 15. The input receiving unit 84 (FIG. 15) receives an input of a posture reproduction position OP different from the above.

[0161] In step S33, the processor 50 selects the teaching posture OR extracted in step S31. n Specifically, the processor 50 first generates the posture reproduction program 204 based on the teaching posture OR extracted in step S31. n and the posture reproduction position OP received in step S32, a position data table 206 for the posture reproduction program 204 is generated.

[0162] An example of the position data table 206 is shown in Fig. 18. In the position data table 206 shown in Fig. 18, coordinate data to which identifiers "OP1", "OP2", "OP3", and "OP4" are respectively assigned are stored. As shown in Fig. 18, the coordinates of the identifier "OPn" (n = 1, 2, 3, 4) share the coordinates (X0, Y0, Z0) of the posture reproduction position OP accepted in step S32, while the coordinates of the taught posture OR extracted in step S31 are also shared. n coordinates (W n ,P n ,R n ) respectively. The processor 50 extracts the teaching posture OR n and the posture reproduction position OP received in step S32, a position data table 206 as shown in FIG. 18 is created.

[0163] Next, processor 50 generates posture reproduction program 204 based on the created position data table 206. An example of posture reproduction program 204 is shown in FIG. 19. In posture reproduction program 204 shown in FIG. 19, for example, the code "MOVE[OP3] VELOCITY[V13]" on the fifth line causes robot 12 to move welding gun 14 at a velocity V=V 13 [mm / sec] and positioning to the posture reproduction position OP and teaching posture OR3 indicated by the identifier [OP3]. O is.

[0164] The velocity V n : "VELOCITY[Vn]" (n=11, 12, 13, 14) is the velocity V specified in the welding work program 200 n (n=1, 2, 3, 4) may be set to a different (specifically, lower) speed (e.g., V 11 =V 12 =V 13 =V 14 <V1=V2=V3=V4)。

[0165] When the posture reproduction program 204 is executed, the processor 50 executes the positioning command INO When this command is read, the coordinates (X0, Y0, Z0, W3, P3, R3) represented by the identifier "OP3" are obtained from the position data table 206. Then, the processor 50 functions as the operation execution unit 62, and operates the robot 12 in the robot coordinate system C1 to position the welding gun 14 at the coordinates (X0, Y0, Z0, W3, P3, R3).

[0166] On the other hand, the code "PRESSURIZE CONDITION[1]" on the 2ith line (i=1, 2, 3, 4) of the posture reproduction program 204 is a pressure command IN that drives the servo motor 40 of the welding gun 14 in accordance with the welding condition 1 assigned the identifier [1], and causes the welding gun 14 to pressurize the object to be pressed. R In this way, the posture reproduction program 204 performs the welding command IN W Does not include.

[0167] The processor 50 issues a pressure command IN during execution of the posture reproduction program 204. R When the welding condition 1 is read, the welding force F1=2 [kN] is acquired by referring to the data table of the welding condition 1 to which the identifier [1] is assigned, and the welding force command F corresponding to the welding force F1 is obtained. C_1 (=2 [kN]) to drive the servo motor 40 of the welding gun 14.

[0168] In this manner, in this embodiment, the processor 50 extracts the teaching posture OR n and the posture reproduction position OP received in step S32, a position data table 206 is generated, and a posture reproduction program 204 is generated based on the position data table 206. Therefore, the processor 50 generates the posture reproduction program 204 based on the taught posture OR n It also functions as a program generating unit 82 (FIG. 15) that generates a posture reproduction program 204 based on the posture reproduction position OP.

[0169] 16 again, in step S34, processor 50 determines whether or not a posture reproduction program start command has been received from the operator or the upper controller. If processor 50 determines YES, it proceeds to step S35, whereas if it determines NO, it loops step S34.

[0170] In step S35, processor 50 executes a pressure acquisition process. Step S35 will be described with reference to Fig. 17. In the flow shown in Fig. 17, the same processes as those in the flow of Fig. 5 are assigned the same step numbers, and overlapping descriptions will be omitted.

[0171] In step S41, the processor 50 executes the positioning command IN of the posture reproduction program 204. O Specifically, the processor 50 functions as the motion execution unit 62 and executes the positioning command IN "MOVE [OP1] VELOCITY [V11]" defined in the first line of the posture reproduction program 204. O is read out, and the robot 12 is used to position the welding gun 14 at the posture reproduction position OP and the teaching posture OR1 (i.e., the coordinates (X0, Y0, Z0, W1, P1, R1) of the identifier "OP1"), and the speed V 11 Move it with .

[0172] In step S42, the processor 50 moves the welding gun 14 between the posture reproduction position OP and the nth teaching posture OR n (That is, the coordinates of the identifier "OPn" (X0, Y0, Z0, W n ,P n ,R n Specifically, the processor 50 determines whether the welding gun 14 has been positioned to the attitude reproduction position OP and the nth taught attitude OR based on the feedback FB2 from the rotation detection sensor RS1. n It is determined whether the positioning has been completed.

[0173] The processor 50 moves the welding gun 14 to the posture reproduction position OP and the nth teaching posture OR nIf it is determined that the welding gun 14 has been positioned to the posture reproduction position OP and the nth teaching posture OR, the operation of the robot 12 is stopped, and the process proceeds to step S4. n On the other hand, if the result of the determination is NO, the processor 50 loops step S42.

[0174] After step S4, in step S43, the processor 50 calculates the welding pressure F specified in the welding condition m. m The pressure command F corresponding to C_m Specifically, the processor 50 drives the welding gun 14 in accordance with the pressure command IN (first pressure command) on the 2ith line in the posture reproduction program 204. R Read out.

[0175] Then, in step S43, the processor 50 reads out the pressurizing command IN R In response to the code "CONDITION[1]" in the above, the welding force F1 (=2 [kN]) specified in the welding condition 1 to which the identifier [1] is assigned is acquired. Then, the processor 50 acquires the welding force command F1 corresponding to the welding force F1 acquired from the welding condition 1. C_1 (=2[kN]) is generated, and the pressure command F C_1 The servo motor 40 of the welding gun 14 is driven in accordance with the above.

[0176] Then, the processor 50 calculates the pressure command F C_1 When the value of the welding force F reaches a value corresponding to the welding force F, the servo motor 40 is stopped. As a result, the welding force sensor 16 is clamped between the movable welding tip 44 and the fixed welding tip 36. Next, the processor 50 executes step S6 and functions as the welding force acquisition unit 64 to acquire from the welding force sensor 16 the welding force F measured by the welding force sensor 16 at the end of step S43 (i.e., when the servo motor 40 is stopped).

[0177] In step S44, the processor 50 selects all the teaching postures OR defined in the posture reproduction program 204.n If the determination is YES, the processor 50 ends the flow shown in Fig. 17, thereby ending the flow of Fig. 16. On the other hand, if the determination is NO, the processor 50 proceeds to step S45.

[0178] In step S45, the processor 50 executes the positioning command IN O For example, when executing step S45 for the first time, the processor 50 executes the positioning instruction IN O Execute "MOVE [OP2] VELOCITY [V12]" to move the welding gun 14 at a velocity V 12 Move it with .

[0179] Then, the processor 50 returns to step S42. In this manner, the processor 50 repeatedly executes the loop of steps S42, S4, S43, S6, S44, and S45 until it determines YES in step S44, and in step S45, it moves the welding gun 14 between the attitude reproduction position OP and the nth taught attitude OR n Each time positioning is performed, the applied pressure F is acquired in step S6.

[0180] That is, according to the posture reproduction program 204, the processor 50 executes steps S41 and S45 to change only the posture of the welding gun 14 to the taught posture OR without changing the position of the welding gun 14 (that is, the posture reproduction position OP) (that is, while maintaining the welding gun 14 at the posture reproduction position OP). n , and the applied pressure F is acquired in step S6.

[0181] 17 ends, processor 50 executes welding operation program 200 to perform actual welding on the workpiece. While executing welding operation program 200 for the actual welding, processor 50 functions as command corrector 66 to correct each taught posture OR based on welding force F acquired in step S6 of step S35. n Pressure command FC_1 By correcting the force command F C_1 ' is required.

[0182] As described above, in this embodiment, the processor 50 functions as the operation execution unit 62, the welding force acquisition unit 64, the command correction unit 66, the attitude extraction unit 78, the program generation unit 82, and the input reception unit 84, thereby determining the welding force command F in accordance with the attitude OR of the welding gun 14. C Therefore, the operation execution unit 62, the welding force acquisition unit 64, the command correction unit 66, the attitude extraction unit 78, the program generation unit 82, and the input reception unit 84 correct the welding force command F in accordance with the attitude OR of the welding gun 14. C The apparatus 110 (FIG. 15) for correcting the above is constructed.

[0183] In this apparatus 110, the operation execution unit 62 operates the robot 12 to move the welding gun 14 to the teaching position TP n The posture reproduction position OP and teaching posture OR are different from n Positioning instruction IN O Meanwhile, welding instructions W By executing the posture reproduction program 204 that does not include the posture reproduction position OP, the welding gun 14 is moved by the robot 12 to the posture reproduction position OP and the teaching posture OR. n (Steps S41 and S45).

[0184] The pressure acquisition unit 64 then receives the pressure data from the operation execution unit 62, and transfers the welding gun 14 to the posture reproduction position OP and the teaching posture OR. n In this configuration, the welding force F when the welding position is set to the teaching posture OR defined in the welding operation program 200 is acquired (step S6). n By executing the posture reproduction program 204 that reproduces the posture, the welding gun 14 is set to the teaching posture OR n Positioning is performed in the teaching posture OR n Pressure command F C The applied pressure F for correcting the above can be obtained effectively.

[0185] In the welding device 110, the posture extraction unit 78 extracts the teaching posture OR from the welding operation program 200. n(step S31), and the program generating unit 82 extracts the teaching posture OR extracted by the posture extracting unit 78. n Based on this, the posture reproduction program 204 is generated. According to this configuration, the posture reproduction program 204 can be automatically generated by the computer, thereby reducing the operator's workload.

[0186] Furthermore, in the device 110, the input receiving unit 84 receives input of the posture reproduction position OP (step S32), and the program generation unit 82 generates the posture reproduction program 204 further based on the posture reproduction position OP received by the input receiving unit 84. With this configuration, the operator can arbitrarily specify the posture reproduction position OP as, for example, a coordinate close to the origin (robot base 20) of the robot coordinate system C1. As a result, the operating range of the robot 12 when the posture reproduction program 204 is being executed can be reduced, thereby reliably preventing the robot 12 from interfering with peripheral devices when the posture reproduction program 204 is being executed.

[0187] In step S32 described above, the processor 50 may function as the input receiving unit 84 and receive input of the allowable operation range RG of the robot 12 instead of the posture reproduction position OP. For example, the processor 50 generates an input image IM for inputting the allowable operation range RG and displays it on the display device 60. While viewing the input image IM, the operator may operate the input device 58 to provide the processor 50 with an input specifying the allowable operation range RG (for example, an input specifying a radius R from the origin of the robot coordinate system C1).

[0188] In this case, after determining YES in step S32, the processor 50 performs the following in step S33: n and the allowable operating range RG received in step S32, a position data table 206' is generated. An example of this position data table 206' is shown in FIG.

[0189] In the example shown in FIG. 20, the coordinates stored in the position data table 206′ and assigned with the identifier “OPn” (n=1, 2, 3, 4) are the coordinates (X j ,Y j ,Z j ) (j=11, 12, 13, 14). The coordinates of the posture reproduction position OP (X j ,Y j ,Z j ) indicates at least one (for example, all) teaching position TP defined in the welding operation program 200. n (X n ,Y n ,Z n ) and is automatically generated by the processor 50 as coordinates that are within the allowable operating range RG accepted in step S32.

[0190] Then, in step S33, the processor 50 functions as the program generator 82 and generates the posture reproduction program 204 based on the position data table 206'. That is, in this case, the processor 50 functions as the program generator 82 and generates the posture reproduction program 204 based on the teaching posture OR extracted by the posture extractor 78 in step S31. n Then, the posture reproduction program 204 is generated based on the allowable movement range RG received by the input receiving unit 84 in step S32.

[0191] Next, further functions of welding robot system 80 will be described with reference to Figures 21 to 23. Welding robot system 80 further executes the flow shown in Figure 22. In the flow shown in Figure 22, the same processes as those in the flow of Figure 16 are given the same step numbers, and duplicated explanations will be omitted.

[0192] After the flow of FIG. 22 starts, processor 50 executes step S1 to acquire welding operation program 200, and then executes step S31 to function as posture extraction unit 78 to extract a teaching posture OR from welding operation program 200. n Next, the processor 50 executes step S32 and determines whether or not an input of the posture reproduction position OP(X0, Y0, Z0) has been accepted.

[0193] When the determination in step S32 is YES (i.e., when the input of the posture reproduction position OP(X0, Y0, Z0) is accepted), in step S51, the processor 50 functions as the posture difference calculation unit 74 and calculates the posture OR of the plurality of teaching postures extracted from the welding operation program 200 in step S31. n Find the difference φ between

[0194] Specifically, the processor 50 calculates the difference φ between the first taught orientation OR1 (W1, P1, R1) and the second taught orientation OR2 (W2, P2, R2) by the method described in step S21 above. 1_2 , the difference φ between the first teaching posture OR1 (W1, P1, R1) and the third teaching posture OR3 (W3, P3, R3) 1_3 , and the difference φ between the first teaching orientation OR1 (W1, P1, R1) and the fourth teaching orientation OR4 (W4, P4, R4) 1_4 are calculated respectively.

[0195] The processor 50 also calculates a difference φ between the second teaching orientation OR2 (W2, P2, R2) and the third teaching orientation OR3 (W3, P3, R3). 2_3 , the difference φ between the second teaching posture OR2 (W2, P2, R2) and the fourth teaching posture OR4 (W4, P4, R4) 2_4 , and the difference φ between the third teaching orientation OR3 (W3, P3, R3) and the fourth teaching orientation OR4 (W4, P4, R4) 3_4 are calculated respectively.

[0196] In step S52, the processor 50 functions as the difference determining unit 76 and determines whether each difference φ calculated in step S51 is equal to or smaller than a predetermined threshold value φ th Specifically, the processor 50 determines whether the difference φ 1_2 , difference φ 1_3 , difference φ 1_4 , difference φ 2_3 , difference φ 2_4 , and the difference φ 3_4 and the threshold φ th Compare with φ 1_2 <φ th , φ 1_3<φ th , φ 1_4 <φ th , φ 2_3 <φ th , φ 2_4 <φ th , or φ 3_4 <φ th It is determined whether or not each of them is true.

[0197] As described in the above embodiment, if the difference φ between the first teaching orientation OR1, the second teaching orientation OR2, and the fourth teaching orientation OR4 is equal to or smaller than the threshold φ th If φ is smaller than φ, the processor 50 1_2 <φ th , φ 1_4 <φ th , and φ 2_4 <φ th It is determined that the above condition is satisfied.

[0198] In step S53, the processor 50 functions as the program generator 82 to generate the posture reproduction program 204. Specifically, the processor 50 generates the posture reproduction program 204 by extracting the plurality of taught postures OR extracted in step S31. n Among them, the difference φ is the threshold φ th Orientation OR n and the posture reproduction position OP received in step S32, a position data table 206" for the posture reproduction program 204 is generated.

[0199] In this embodiment, in step S52 described above, the difference φ among the first teaching attitude OR1, the second teaching attitude OR2, and the fourth teaching attitude OR4 is set to a threshold value φ th is smaller than (i.e., φ 1_2 <φ th , φ 1_4 <φ th , φ 2_4 <φ th Therefore, processor 50 generates position data table 206″ shown in FIG. 24 based on the first taught orientation OR1, the third taught orientation OR3, and the orientation reproduction position OP received in step S32.

[0200] Then, the processor 50 generates a posture reproduction program 204' shown in FIG. 25 based on the position data table 206'. The posture reproduction program 204' includes the positioning instruction IN O and the pressure command IN on the 2ith line R Thereafter, the processor 50 executes step S34, and if determined as YES, proceeds to step S54.

[0201] In step S54, the processor 50 executes a pressure force acquisition process. This pressure force acquisition process is shown in Fig. 23. In the flow shown in Fig. 23, the same processes as those in the flow of Fig. 12 or 17 are given the same step numbers, and redundant explanations will be omitted.

[0202] The processor 50 executes the above-described steps S41 to S43, S14, S15, S44, and S45 in accordance with the posture reproduction program 204′ generated in step S53, thereby acquiring the pressure force F. As a result, the processor 50 acquires the pressure force F in the first taught posture OR1 and the pressure force F in the third taught posture OR3.

[0203] After the flow of FIG. 23 ends, processor 50 executes welding operation program 200 for the actual welding operation, and during the execution of welding operation program 200, processor 50 functions as command corrector 66 to calculate correction amounts ΔF for the first teaching posture OR1 and the third teaching posture OR3 based on the welding force F obtained in step S15 of step S54, and corrects the original welding force command F by the correction amounts ΔF. C_1 By correcting these, the pressure force command F C_1 ' are obtained respectively.

[0204] On the other hand, for the second teaching attitude OR2 and the fourth teaching attitude OR4, the processor 50 uses the correction amount ΔF calculated for the first teaching attitude OR1 to correct the original pressure force command F C_1In this way, the processor 50 corrects the pressure force commands F C_1 That is, the processor 50 calculates the original pressure command F' by using a common correction amount ΔF in the first taught attitude OR1, the second taught attitude OR2, and the fourth taught attitude OR4 which are close to each other. C_1 will be corrected.

[0205] As described above, in this embodiment, the processor 50 functions as the operation execution unit 62, the pressure acquisition unit 64, the command correction unit 66, the position acquisition unit 72, the attitude difference calculation unit 74, the difference determination unit 76, the attitude extraction unit 78, the program generation unit 82, and the input reception unit 84, thereby determining the pressure command F in accordance with the attitude OR of the welding gun 14. C Correct the following.

[0206] Therefore, the operation execution unit 62, the welding force acquisition unit 64, the command correction unit 66, the position acquisition unit 72, the attitude difference calculation unit 74, the difference determination unit 76, the attitude extraction unit 78, the program generation unit 82, and the input reception unit 84 generate the welding force command F in accordance with the attitude OR of the welding gun 14. C The apparatus 120 (FIG. 21) for correcting the above is constructed.

[0207] In this device 120, a plurality of teaching postures OR defined in the welding work program 200 are n Among them, the difference φ between the postures OR is the threshold φ th or more (i.e., posture OR is different) n The posture reproduction program 204' is generated using only the above-mentioned parameters. According to this configuration, the number of postures OR for positioning the welding gun 14 in the posture reproduction program 204' can be optimized.

[0208] In this embodiment, the processor 50 may generate the posture reproduction program 204 shown in Fig. 19 in place of the posture reproduction program 204' in step S53. In this case, steps S51 and S52 can be omitted from the flow in Fig. 22. Then, the processor 50 may execute steps S21 and S22 shown in Fig. 14 after determining NO in step S44 in Fig. 23.

[0209] 15 and 21, the processor 50 functions as the program generator 82 to generate the posture reproduction programs 204 and 204'. However, this is not limiting, and in the embodiment of FIG. 15 or 21, the processor 50 may acquire the posture reproduction program 204 or 204' by downloading it from another computer (such as a host controller or a production management server). hand Good too.

[0210] In this case, the posture extraction unit 78, the program generation unit 82, and the input reception unit 84 can be omitted from the device 110 or 120. In this case, the processor 50 executes step S35 shown in Fig. 17 or step S54 shown in Fig. 23 in accordance with the downloaded posture reproduction program 204 or 204'.

[0211] In the above embodiment, the processor 50 outputs the welding force command F C_1 However, the processor 50 may correct the pressure command F during the execution of the flow of FIG. C_1 may be corrected.

[0212] For example, in the flow of FIG. 5, FIG. 12, or FIG. 14, when the determination in step S7 is YES, the processor 50 calculates each teaching posture OR based on the applied force F collected in step S6 or S15. n Pressure command F C_1 By correcting the force command F C_1Then, the processor 50 may obtain the teaching posture OR n The pressure command F C_1 ' to the teaching posture OR n A data table DT may be created that stores the data in association with the above.

[0213] In this case, the processor 50 executes the welding instruction IN of the welding operation program 200 in the actual welding operation. W When the teaching posture OR is read, the welding gun 14 is positioned at this time. n (i.e., the welding instruction IN W Positioning instruction on the line before IN P The teaching posture specified in OR n ) corresponding to the pressure command F C_1 ' is retrieved from the data table DT.

[0214] In the flow of FIG. 16 or FIG. 22, the processor 50, at the end of step S35 or S54 (that is, when it is determined as YES in step S44), calculates the pressure F of each teaching posture OR based on the pressure F collected in step S6 or S15. n Pressure command F C_1 By correcting the force command F C_1 ' may be required.

[0215] In the flow of FIG. 5, in step S2 or S8, the processor 50 causes the robot 12 to move the welding gun 14 in accordance with the positioning command IN of the welding operation program 200. P (code "Vn") n However, in step S2 or S8 of FIG. 5, the processor 50 moves the welding gun 14 at the speed V n (e.g., velocity V n (lower than) speed V n In this case, the welding gun 14 may be moved at a speed V nA flag FL' for moving the welding position by ' may be set in the control device 18. Alternatively, in the welding operation program 200 acquired in step S1 described above, a positioning command IN P The flag FL' may be added to the code.

[0216] In the above embodiment, the processor 50 determines in steps S5 and S43 whether the feedback FB1 from the load detection sensor LS is equal to the pressure command F C_1 However, the present invention is not limited to this. In step S5 or S43, the processor 50 may stop the servo motor 40 when the movable welding tip 44 comes into contact with the non-pressurized object (fixed welding tip 36) and is forcibly stopped.

[0217] In this case, the processor 50 executes the welding instruction IN of the welding operation program 200 in the actual welding operation. W Even when the above operation is performed, the servo motor 40 may be stopped when the movable welding tip 44 comes into contact with the workpiece and is forced to stop. The object to be pressurized is not limited to the fixed welding tip 36, but any object (e.g., an iron plate) fixed to the fixed arm 34 can be used.

[0218] 5, 12, 14, 16, or 22 in accordance with a computer program PG2 pre-stored in memory 52. ​​Furthermore, the functions of the devices 70, 90, 100, 110, or 120 executed by the processor 50 (i.e., the operation execution unit 62, the pressure acquisition unit 64, the command correction unit 66, the position acquisition unit 72, the attitude difference calculation unit 74, the difference determination unit 76, the attitude extraction unit 78, the program generation unit 82, and the input reception unit 84) may be functional modules realized by the computer program PG.

[0219] 6, the posture reproduction program 204 shown in Fig. 19, and the posture reproduction program 204' shown in Fig. 25 are merely examples, and any other types of commands may be included. For example, in the welding operation program 200 shown in Fig. 6, a positioning command IN P is specified, and the welding command IN W However, in the welding operation program 200, the positioning instruction IN P and welding instructions IN W It may be specified that:

[0220] Similarly, in the posture reproduction program 204 or 204', the positioning command IN O and pressure command IN R In addition, the teaching position TP defined in the welding operation program 200 may be n and teaching posture OR n The number of the teaching postures OR defined in the posture reproduction program 204 or 204′ is not limited to four, but may be one, or may be five or more. n The same applies to the number of .

[0221] In the welding operation program 200 shown in FIG. P In the above description, the identifier "TPn" (n=1, 2, 3, 4) is defined in the position data table 202 shown in Fig. 7, and the position data table 202 is created separately. However, the present invention is not limited to this. P Instead of the identifier "TPn", use the coordinates (X n ,Y n ,Z n ,W n ,P n ,R n ) may be written directly as a code. O The same is true for .

[0222] In the welding operation program 200 shown in FIG. WIn the above description, an identifier [m] (m=1 in the example of FIG. 6) corresponding to the welding condition m is written in the welding command IN, and a data table of the welding condition m as shown in FIG. 8 is prepared separately. However, the present invention is not limited to this. W Instead of the identifier "m", the value of welding condition m (i.e., welding force F m , welding current I m , welding time t m ) may be directly written as a code. R The same is true for .

[0223] The operator may input a positioning command IN to the welding operation program 200 acquired in step S1. P (Specifically, teaching posture OR n ) may be modified to create welding operation program 200'. Then, processor 50 may execute the modified welding operation program 200' during actual welding work to perform the welding work.

[0224] For example, before performing an actual welding operation, the operator may change the program name of the welding operation program 200 (FIG. 6) acquired in step S1, or may change the program name of the positioning command IN P Codes other than the above may be edited or added, or the above-mentioned flag FL may be added.

[0225] In addition, the operator may select the welding command IN of the welding work program 200 acquired in step S1. W with an instruction to execute welding force acquisition operation FO, and processor 50 may execute the flow of Fig. 5, 12 or 14 in accordance with welding operation program 200' after the replacement. Both welding operation program 200 acquired in step S1 and welding operation program 200' after such a change can be regarded as welding operation programs that cause robot 12 and welding gun 14 to perform welding operation.

[0226] Furthermore, welding operation program 200 or 200' may include multiple programs. For example, welding operation program 200 shown in Fig. 6 may be composed of first program 200A including command codes from lines 1 to 4 and second program 200B including command codes from lines 5 to 8. Similarly, posture reproduction program 204 or 204' may also include multiple programs.

[0227] In addition, in the above embodiment, the welding operation program 200 and the posture reproduction programs 204 and 204' use the welding condition 1 assigned with the identifier [1] (i.e., the code "CONDITION[1]"), but other welding conditions m may also be used.

[0228] In the above embodiment, the processor 50 calculates the correction amount ΔF when an actual welding operation is performed, and calculates the first welding force command F C_1 By correcting the second pressure command F C_1 However, the present invention is not limited to this. The processor 50 may calculate each teaching posture OR based on the applied force F obtained in step S6 or S15. n Second pressure command F C_1 ' may be determined prior to the actual welding operation.

[0229] At this time, the processor 50 uses the correction amount ΔF calculated as described above to calculate the second pressure command F C_1 Alternatively, the first pressure command F C_1 and the pressure F, and the second pressure command F C_1 Then, the processor 50 may determine the first welding force command F C_1 is set to a predetermined second pressure command F C_1 This can be corrected by replacing it with '.

[0230] In addition, in the above-mentioned embodiment, the functions of the devices 70, 90, 100, 110 and 120 (the operation execution unit 62, the pressure acquisition unit 64, the command correction unit 66, the position acquisition unit 72, the attitude difference calculation unit 74, the difference determination unit 76, the attitude extraction unit 78, the program generation unit 82, and the input reception unit 84) are described as being implemented in the control device 18.

[0231] However, without being limited to this, at least one of the functions of the device 70, 90, 100, 110, or 120 (for example, the movement execution unit 62, the posture extraction unit 78, the program generation unit 82, and the input reception unit 84) may be implemented in a teaching device (a teaching pendant, a tablet terminal device, or the like) that teaches the robot 12 a movement, or in another computer such as a PC. In this case, the processor of the other computer functions as the device 70, 90, 100, 110, or 120.

[0232] Furthermore, the robot 12 is not limited to a vertical articulated robot, but may be any other type of robot, such as a horizontal articulated robot or a parallel link robot. Furthermore, the concept of the present invention is not limited to a C-type spot welding gun, but may be applied to any other type of welding gun, such as an X-type spot welding gun. While the present disclosure has been described above through the embodiments, the above-described embodiments do not limit the scope of the invention claimed. [Explanation of symbols]

[0233] 10,10',80 Welding Robot System 12. Robot 14 Welding gun 16,16' pressure sensor 18 Control Device 62 Action execution unit 64 Pressure acquisition unit 66 Command correction section 70,90,100,110,120 equipment 72 Position acquisition part 74 Posture difference calculation section 76 Difference judgment part 78 Posture extraction part 82 Program Generation Unit 84 Input reception section 200 welding work programs 204,204' Posture Reproduction Program

Claims

1. A device that corrects a pressure command that defines the pressure of a welding gun that is moved by a robot and presses and welds a workpiece, in accordance with the attitude of the welding gun, an operation execution unit that operates the robot so as to position the welding gun in a teaching posture defined in a welding operation program that causes the robot and the welding gun to perform welding operation; a pressure acquisition unit that acquires the pressure applied when the welding gun is driven by the first pressure command when the operation execution unit positions the welding gun in the taught attitude; a command correction unit that corrects the first pressure command based on the pressure acquired by the pressure acquisition unit, thereby determining a second pressure command when the welding gun is driven in the taught attitude during execution of the welding operation program.

2. the welding operation program includes a positioning command for operating the robot to position the welding gun at a taught position and at the taught attitude, and a welding command for starting the welding gun to weld a workpiece, the operation execution unit executes the positioning command of the welding operation program to position the welding gun at the taught position and the taught attitude by the robot, while not executing the welding command; The apparatus according to claim 1 , wherein the pressure acquisition unit acquires the pressure when the operation execution unit positions the welding gun at the taught position and the taught attitude.

3. the operation execution unit executes an attitude reproduction program that includes a positioning command for operating the robot to position the welding gun at a position and the taught attitude different from a taught position defined in the welding work program, but does not include a welding command for starting the welding gun to weld a workpiece, thereby positioning the welding gun at the different position and the taught attitude by the robot; The apparatus according to claim 1 , wherein the pressure acquisition unit acquires the pressure when the operation execution unit positions the welding gun at the different positions and the taught attitude.

4. a posture extraction unit that extracts the teaching posture from the welding operation program; The apparatus according to claim 3 , further comprising: a program generation unit that generates the posture reproduction program based on the teaching posture extracted by the posture extraction unit.

5. further comprising an input receiving unit that receives input of the different positions, The apparatus according to claim 4 , wherein the program generation unit generates the posture reproduction program further based on the different positions accepted by the input acceptance unit.

6. an input receiving unit that receives an input of an allowable movement range of the robot when the posture reproduction program is executed; The apparatus according to claim 4 , wherein the program generation unit generates the posture reproduction program further based on the allowable movement range accepted by the input acceptance unit.

7. the pressing force acquisition unit acquires the first pressing force when the operation execution unit positions the welding gun in the first taught attitude, the command corrector calculates a correction amount for correcting the first pressing force command to the second pressing force command for driving the welding gun in the first teaching attitude based on the first pressing force; The device comprises: an attitude difference calculation unit that calculates a difference between the second teaching attitude and the first teaching attitude; a difference determination unit that determines whether the difference calculated by the attitude difference calculation unit is smaller than a predetermined threshold value, When the difference determination unit determines that the difference is smaller than the threshold value, the operation execution unit does not execute an operation to position the welding gun in the second taught attitude, The device according to any one of claims 1 to 6, wherein the command correction unit uses the correction amount determined in the first teaching posture to correct the first pressing force command for driving the welding gun in the second teaching posture, thereby determining the second pressing force command in the second teaching posture.

8. the welding operation program defines a first taught position and a first taught posture for positioning the welding gun, and a second taught position and a second taught posture; the pressing force acquisition unit acquires the first pressing force when the operation execution unit positions the welding gun at the first taught position and the first taught attitude, The command correction unit correcting the first pressure force command based on the first pressure force to obtain the second pressure force command at the first teaching position and the first teaching attitude; estimating the second pressing force command at the second taught position and the second taught attitude based on the obtained second pressing force command and the first taught position and the second taught position defined in the welding operation program; The apparatus according to any one of claims 1 to 6, wherein the operation execution unit does not execute an operation to position the welding gun in the second taught attitude.

9. The device according to any one of claims 1 to 6, wherein the pressure acquisition unit acquires the pressure measured by a pressure sensor when the welding gun positioned in the taught attitude by the operation execution unit is driven by the first pressure command.

10. the welding gun has a movable welding tip and a position sensor that detects the position of the movable welding tip; the device further includes a position acquisition unit that acquires the first position detected by the position sensor when the welding gun, positioned in a predetermined reference attitude, is driven by the first pressing force command to pressurize the workpiece with the movable welding tip, and the second position detected by the position sensor when the welding gun, positioned in the taught attitude by the operation execution unit, is driven by the first pressing force command to pressurize the workpiece with the movable welding tip, The device according to any one of claims 1 to 6, wherein the pressure acquisition unit determines the pressure in the teaching posture by a predetermined calculation based on the first position and the second position acquired by the position acquisition unit.

11. A control device for a robot, comprising the device according to any one of claims 1 to 6.

12. A method for correcting a pressure command that defines a pressure applied by a welding gun that is moved by a robot and applies pressure to a workpiece to weld it, in accordance with the attitude of the welding gun, comprising: The processor: operating the robot to position the welding gun in a teaching posture defined in a welding operation program that causes the robot and the welding gun to perform a welding operation; acquiring the pressing force when the welding gun is driven by the first pressing force command when the welding gun is positioned in the taught attitude; A method for determining a second pressure command when driving the welding gun in the taught attitude during execution of the welding operation program by correcting the first pressure command based on the acquired pressure.

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