Robot control device and plasma cutting method

Abstract

The present invention provides a robot control device and a plasma cutting method that enable cutting at the appropriate cutting position on a workpiece while maintaining a constant distance between the torch tip and the workpiece surface. [Solution] The robot control device includes a robot control unit 120 that controls the operation of the plasma cutting robot 20 according to a teaching program, a distance calculation unit 130 that calculates the distance between the torch 21 and the cutting position on the object to be cut, a posture calculation unit 140 that calculates the posture of the torch 21 with respect to the cutting surface to which the cutting position on the object to be cut belongs, and a correction unit 150 that corrects the position of the torch 21 in a tracing direction perpendicular to the cutting surface based on the distance calculated by the distance calculation unit 130 and the posture calculated by the posture calculation unit 140 in order to maintain the cutting distance for plasma cutting of the object to be cut, and the robot control unit 120 controls the operation of the plasma cutting robot 20 while correcting the position of the torch 21 with respect to the correction unit 150.

Description

Technical Field

[0001] The present invention relates to a robot control device and a plasma cutting method.

Background Art

[0002] A plasma cutting robot that performs plasma cutting moves a torch along a cutting line preset by teaching to cut a workpiece to be cut. Here, it is important for the plasma cutting robot to move the torch while keeping the distance between the tip of the torch and the cutting surface of the workpiece constant.

[0003] In Patent Document 1, it is disclosed that the distance between the torch and the cutting surface of the workpiece is kept constant by measuring the arc voltage and comparing the measured arc voltage with a set reference arc voltage.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technique disclosed in Patent Document 1, in bevel cutting in which plasma cutting is performed with the torch inclined with respect to the cutting surface of the workpiece, no consideration is given to how to correct the position of the torch. In order to keep the distance between the tip of the torch and the cutting surface of the workpiece constant, if the torch is directly moved in the direction approaching or away from the cutting surface of the workpiece, if the torch is inclined with respect to the cutting surface of the workpiece, there is a risk that the cutting position on the cutting surface of the workpiece pointed by the tip of the torch will be displaced.

[0006] Therefore, the present invention aims to provide a robot control device and a plasma cutting method that can appropriately cut a workpiece at a specific cutting position on the cutting surface while maintaining a constant distance between the tip of the torch and the cutting surface of the workpiece. [Means for solving the problem]

[0007] A robot control device according to one aspect of the present invention is a teaching playback type robot control device that controls the operation of a plasma cutting robot according to a teaching program programmed by teaching, comprising: a robot control unit that controls the operation of the plasma cutting robot according to the teaching program; a distance calculation unit that calculates the distance between a torch attached to the plasma cutting robot and a cutting position on the object to be cut; a posture calculation unit that calculates the posture of the torch with respect to the cutting surface to which the cutting position on the object to be cut belongs; and a correction unit that corrects at least the position of the torch in a tracing direction perpendicular to the cutting surface based on the distance calculated by the distance calculation unit and the posture calculated by the posture calculation unit, in order to maintain the cutting distance for plasma cutting of the object to be cut, wherein the robot control unit controls the operation of the plasma cutting robot while correcting at least the position of the torch with the correction unit.

[0008] In this embodiment, the distance calculation unit calculates the distance between the torch and the cutting position on the object to be cut, the attitude calculation unit calculates the attitude of the torch with respect to the cutting surface to which the cutting position belongs, and the correction unit corrects the position of the torch at least in a tracing direction perpendicular to the cutting surface, based on the distance calculated by the distance calculation unit and the attitude calculated by the attitude calculation unit, in order to maintain the cutting distance for plasma cutting the object to be cut. The robot control unit then controls the operation of the plasma cutting robot while correcting the position of the torch at least by the correction unit, so that the distance between the tip of the torch and the cutting surface of the object to be cut remains constant, and cutting can be performed appropriately at the cutting position on the cutting surface of the object to be cut.

[0009] In the above embodiment, a cutting surface setting unit may be further provided for setting a reference coordinate system based on the cutting surface.

[0010] According to this embodiment, the position of the cut surface can be appropriately determined, so the distance between the torch and the cutting position and the orientation of the torch relative to the cut surface can be appropriately determined, and the position of the torch can be appropriately corrected in the tracing direction.

[0011] In the above embodiment, the cutting surface setting unit may accept the cutting surface in a robot coordinate system that has been set in advance for the plasma cutting robot.

[0012] According to this embodiment, the position of the cutting surface can be appropriately determined in the robot coordinate system, so the distance between the torch and the cutting position and the orientation of the torch relative to the cutting surface can be appropriately determined, and the position of the torch can be appropriately corrected in the tracing direction.

[0013] In the above embodiment, the system may further include a coordinate system control unit that controls the system to process a reference coordinate system set by the cutting surface setting unit in association with a robot coordinate system that has been set in advance on the plasma cutting robot.

[0014] According to this embodiment, the coordinate system control unit controls the system to process the reference coordinate system and the robot coordinate system in correspondence. This allows the system to appropriately determine the distance between the torch and the cutting position and the orientation of the torch relative to the cutting surface, depending on the various arrangements of the cutting surface, and to appropriately correct the position of the torch in the tracing direction.

[0015] A plasma cutting method according to one aspect of the present invention is a plasma cutting method performed by a teaching playback type robot control device that controls the operation of a plasma cutting robot according to a teaching program programmed by teaching, and includes: a robot control step of controlling the operation of a plasma cutting robot according to a teaching program; a distance calculation step of calculating the distance between a torch attached to the plasma cutting robot and a cutting position on a target to be cut; a posture calculation step of calculating the posture of the torch with respect to the cutting plane to which the cutting position on the target to be cut belongs; and a correction step of correcting the position of the torch in a tracing direction perpendicular to the cutting plane, based on the distance calculated in the distance calculation step and the posture calculated in the posture calculation step, in order to maintain a cutting distance for plasma cutting the target, wherein the robot control step controls the operation of the plasma cutting robot while correcting the position of the torch in the correction step.

[0016] In this embodiment, the distance calculation step calculates the distance between the torch and the cutting position on the object to be cut, the attitude calculation step calculates the attitude of the torch relative to the cutting surface to which the cutting position belongs, and the correction step corrects the position of the torch at least in a tracing direction perpendicular to the cutting surface, based on the distance calculated in the distance calculation step and the attitude calculated in the attitude calculation step, in order to maintain the cutting distance for plasma cutting the object to be cut. Then, in the robot control step, the operation of the plasma cutting robot is controlled while correcting the position of the torch at least in the correction step, so that the distance between the tip of the torch and the cutting surface of the object to be cut is kept constant, and cutting can be performed appropriately at the cutting position on the cutting surface of the object to be cut. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a robot control device and a plasma cutting method that can appropriately cut a workpiece at a specific cutting position on the cutting surface while maintaining a constant distance between the tip of the torch and the cutting surface of the workpiece. [Brief explanation of the drawing]

[0018] [Figure 1] It is a system schematic diagram showing a plasma cutting robot system 10 according to an embodiment of the present invention. [Figure 2] It is a functional block diagram showing each function of a robot control device 100 according to an embodiment of the present invention. [Figure 3] It is a diagram showing a state where plasma cutting (bevel cutting) is performed by moving the torch 21 in the cutting direction while being inclined with respect to the cutting surface S on the workpiece W. [Figure 4] It is a diagram showing a state where the position of the torch 21 is corrected while maintaining the inclination of the torch 21 with respect to the cutting surface of the workpiece when the position of the workpiece is displaced. [Figure 5] It is a diagram showing the relationship between the robot coordinate system of the plasma cutting robot 20 and the reference coordinate system based on the cutting surface S of the workpiece W. [Figure 6] It is a flowchart showing the flow of processing of a plasma cutting method M100 executed by a robot control device 100 according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. Note that the embodiments described below are merely specific examples for carrying out the present invention and do not limit the interpretation of the present invention. Also, for ease of understanding of the description, the same reference numerals are attached to the same components in each drawing as much as possible, and redundant descriptions may be omitted.

[0020] <One Embodiment> [Overview of Plasma Cutting Robot System] FIG. 1 is a system schematic diagram showing a plasma cutting robot system 10 according to an embodiment of the present invention. As shown in FIG. 1, the plasma cutting robot system 10 includes a plasma cutting robot 20, a teach pendant 30, a plasma power supply device 40, and a robot control device 100.

[0021] The plasma cutting robot 20 is connected to the robot control device 100 via a cable and performs plasma cutting based on operation commands from the robot control device 100. The plasma cutting robot 20 is equipped with a torch 21 at the tip of its arm, and performs plasma cutting by generating an arc between the tip of the torch 21 and the metal material (workpiece) to be cut.

[0022] The torch 21 is connected to the plasma power supply unit 40 via a cable and receives voltage and current. In plasma cutting, when the torch 21 is momentarily brought into contact with a metal material and current is applied, an arc discharge is generated between the tip of the torch 21 and the metal material, and the heat of the generated arc melts the metal material, thereby performing plasma cutting.

[0023] The teach pendant 30 receives input from the operator performing the plasma cutting operation regarding plasma cutting-related teaching information for the plasma cutting robot 20. The operator uses the teach pendant 30 to input the optimal plasma cutting-related teaching information while checking the state of the arc.

[0024] Here, plasma cutting-related teaching information refers to information related to plasma cutting performed by the plasma cutting robot 20, and includes teaching information that teaches the operation of the plasma cutting robot 20 and plasma cutting conditions. The teaching information for the plasma cutting robot 20 includes information related to the operation of the plasma cutting robot 20's arm, information related to the position and orientation of the plasma cutting robot 20, and information related to the tip of the torch 21. The plasma cutting conditions include the arc voltage applied to the torch 21, the arc current flowing through the torch 21, and the cutting speed, which represents the speed at which the torch 21 moves in the cutting direction during cutting.

[0025] The robot control device 100 is a device that controls the plasma cutting robot 20. The robot control device 100 is connected to the teach pendant 30 and can acquire plasma cutting-related teaching information input to the teach pendant 30. Based on the plasma cutting-related teaching information, the robot control device 100 controls the plasma cutting robot 20 and the plasma power supply unit 40.

[0026] The plasma power supply unit 40 is connected to the plasma cutting robot 20 via a cable and supplies arc voltage and arc current to the torch 21 in the plasma cutting robot 20 based on commands from the robot control unit 100.

[0027] In Figure 1, the teach pendant 30 is connected to the robot control device 100 via a cable, but it may also be connected wirelessly. That is, the teach pendant 30 and the robot control device 100 may be equipped with a communication unit for wireless communication. By connecting the robot control device 100 and the teach pendant 30 wirelessly, the operator can input plasma cutting-related teaching information while moving freely without being bothered by the presence of cables or having their range of movement limited by the length of the cables.

[0028] [Robot control system configuration] Figure 2 is a functional block diagram showing the functions of a robot control device 100 according to one embodiment of the present invention. As shown in Figure 2, the robot control device 100 includes a storage unit 110, a robot control unit 120, a distance calculation unit 130, a posture calculation unit 140, and a correction unit 150.

[0029] The memory unit 110 stores pre-generated teaching programs. For example, a teaching program is generated when an operator uses an operating device (teaching device) such as a teach pendant 30 to set plasma cutting conditions or register teaching points while operating the plasma cutting robot 20.

[0030] The robot control unit 120 operates the plasma cutting robot 20 (including the torch 21) according to a teaching program. The robot control device 100 is a teaching playback type robot control device that controls the operation of the plasma cutting robot 20 as programmed by teaching.

[0031] Furthermore, when the robot control unit 120 operates the plasma cutting robot 20 (including the torch 21) according to the teaching program, the distance between the tip of the torch 21 and the cutting surface of the workpiece may change, for example, due to a shift in the position of the workpiece to be cut or unevenness on the cutting surface of the workpiece.

[0032] In such cases, the robot control unit 120 performs so-called tracing control, which involves moving the torch 21 while correcting its position to maintain a constant distance between the tip of the torch 21 and the cutting surface of the workpiece, thereby performing plasma cutting. This tracing control is achieved by the distance calculation unit 130, attitude calculation unit 140, and correction unit 150, which will be described later.

[0033] The distance calculation unit 130 calculates the distance between the torch 21 attached to the plasma cutting robot 20 and the cutting position on the workpiece to be cut. For example, the distance calculation unit 130 calculates the distance between the tip of the torch 21 and the cutting position on the workpiece in the direction in which the tip of the torch 21 extends.

[0034] More specifically, the distance calculation unit 130 may monitor the voltage applied between the tip of the torch 21 and the cutting position (cutting surface) on the workpiece, and calculate the distance between the tip of the torch 21 and the cutting position (cutting surface) on the workpiece by comparing the voltage with a reference voltage.

[0035] Here, the reference voltage is a voltage corresponding to the cutting distance between the tip of the torch 21 and the cutting position (cutting surface) on the workpiece when performing plasma cutting. For example, a sensor may be provided at the tip of the torch 21 to determine the voltage corresponding to the cutting distance in advance. The voltage applied between the tip of the torch 21 and the cutting position (cutting surface) on the workpiece becomes greater than the reference voltage when the distance between the tip of the torch 21 and the cutting position (cutting surface) on the workpiece is greater than the cutting distance, and becomes less than the reference voltage when the distance between the tip of the torch 21 and the cutting position (cutting surface) on the workpiece is less than the cutting distance. As a result, the distance calculation unit 130 can calculate the distance between the tip of the torch 21 and the cutting position (cutting surface) on the workpiece.

[0036] The posture calculation unit 140 calculates the posture (tilt) of the torch 21 with respect to the cutting surface to which the cutting position on the workpiece belongs. For example, the position of the workpiece to be cut is set in advance for the plasma cutting robot 20. Then, the posture calculation unit 140 may calculate the posture (tilt) of the torch 21 with respect to the cutting surface of the workpiece from the position and posture of the torch 21 based on the axis angles of the plasma cutting robot 20.

[0037] Here, regarding the placement of the workpiece on the plasma cutting robot 20, typically, the workpiece may be set so that its cutting surface is horizontal (parallel) to the mounting surface of the plasma cutting robot 20, or perpendicular to the mounting surface of the plasma cutting robot 20.

[0038] Furthermore, the operator may pre-set how the cutting surface of the workpiece is positioned relative to the plasma cutting robot 20, or the plasma cutting robot 20 may be equipped with sensors (such as a camera, touch sensor, and optical sensor) and the cutting surface of the workpiece may be determined by these sensors. Alternatively, sensors (such as a camera, touch sensor, and optical sensor) may be separately placed to determine the cutting surface of the workpiece relative to the plasma cutting robot 20.

[0039] The correction unit 150 corrects the position of the torch 21 in a tracing direction perpendicular to the cutting surface of the workpiece, based on the distance calculated by the distance calculation unit 130 and the orientation calculated by the orientation calculation unit 140, in order to maintain the cutting distance for plasma cutting of the workpiece. For example, in bevel cutting, where plasma cutting is performed with the torch 21 tilted relative to the cutting surface of the workpiece, the correction unit 150 maintains the tilt of the torch 21 relative to the cutting surface of the workpiece and corrects (moves) the torch 21 in the tracing direction, thereby keeping the distance between the tip of the torch 21 and the cutting surface of the workpiece constant in the direction in which the tip of the torch 21 extends.

[0040] [Details of copy control] The following describes in detail the copy control performed by the robot control device 100 according to one embodiment of the present invention.

[0041] Figure 3 shows how plasma cutting (grooving) is performed by moving the torch 21 in the cutting direction while it is tilted relative to the cutting surface S of the workpiece W. As shown in Figure 3, the torch 21 is tilted, and the tip of the torch 21 is pointing to the cutting position P on the cutting surface S of the workpiece W in the direction in which it extends.

[0042] When plasma cutting is performed by the plasma cutting robot 20, the workpiece W is cut by moving the tilted torch 21 in the cutting direction while maintaining a constant distance between the tip of the tilted torch 21 and the cutting surface S (cutting position P) of the workpiece in the direction in which the tip of the tilted torch 21 extends.

[0043] Figure 4 shows how the position of the torch 21 is corrected while maintaining the inclination of the torch 21 with respect to the cut surface of the workpiece when the workpiece position is shifted. As shown in Figure 4, the workpiece has shifted from the position of workpiece W1 to the position of workpiece W2.

[0044] In this manner, if the position of the workpiece is shifted in a direction perpendicular to the cutting surface of the workpiece, the robot control unit 120 performs plasma cutting by correcting the position of the torch 21 using tracing control, so as to maintain a constant distance between the tip of the torch 21 and the cutting surface of the workpiece.

[0045] Specifically, when the workpiece is located at workpiece W1, d1 is the distance between the tip of the inclined torch 21 and the cut surface S1 (cutting position P1) of the workpiece in the direction in which the tip of the torch 21 extends.

[0046] Furthermore, if the workpiece is misaligned with workpiece W2, unless the position of the torch 21 is corrected at least in the direction from workpiece W1 to workpiece W2, it is not possible to maintain a constant distance between the tip of the tilted torch 21 and the cutting surface (cutting position) of the workpiece in the direction in which the tip of the torch 21 extends.

[0047] Therefore, the position of the tilted torch 21 is corrected. The direction in which the torch 21 is corrected is perpendicular to the cutting surface S1 (S2) of the workpiece W1 (W2) (following direction). The distance for correcting the torch 21 is the distance h such that the distance d2 between the tip of the tilted torch 21 and the cutting surface S2 (cutting position P2) of the workpiece is the same as the above distance d1, in the direction in which the tip of the tilted torch 21 is extended.

[0048] In other words, if the workpiece is shifted from the position of workpiece W1 to the position of workpiece W2, the tracking control corrects the position of the torch 21, which is tilted by a distance h in the tracking direction, which is perpendicular to the cutting surface S1(S2) of the workpiece. As a result, the tilted torch 21 maintains its tilt (angle) and keeps the distance between the tip of the torch 21 and the cutting position P1(P2) on the cutting surface S1(S2) of workpiece W1(W2) constant in the direction in which the tip of the torch 21 extends, so that the tip of the torch 21 appropriately points to the cutting position P1(P2) on the cutting surface S1(S2) of workpiece W1(W2), enabling plasma cutting.

[0049] Figure 5 shows the relationship between the robot coordinate system of the plasma cutting robot 20 and the reference coordinate system based on the cutting surface S of the workpiece W. As shown in Figure 5, the reference coordinate system (XYZ coordinate system) based on the cutting surface S of the workpiece W is set to match the robot coordinate system based on the plasma cutting robot 20.

[0050] The robot control device 100 may include a cutting surface setting unit that sets a reference coordinate system based on the cutting surface S of the workpiece W. The cutting surface setting unit accepts settings from an operator or sets the cutting surface S of the workpiece W using sensors or the like, as described above.

[0051] For example, if the workpiece W is positioned such that its cutting surface S is horizontal (parallel) to the mounting surface of the plasma cutting robot 20, the robot coordinate system will be configured to align the cutting surface S (XY plane) of the workpiece W with the robot coordinate system based on the plasma cutting robot 20.

[0052] When the cutting surface S (XY plane) of the workpiece W is set to match the robot coordinate system based on the plasma cutting robot 20, in tracing control, the tracing direction D of the torch 21, which is perpendicular to the cutting surface S of the workpiece W, will coincide with the Z-axis direction.

[0053] In this example, the workpiece W was positioned so that its cutting surface S was horizontal (parallel) to the mounting surface of the plasma cutting robot 20, but this is not the only option. For example, if the workpiece W is positioned so that its cutting surface S is perpendicular to the mounting surface of the plasma cutting robot 20, or if the workpiece W is an H-beam and its cutting surface S is perpendicular to the mounting surface of the plasma cutting robot 20, the robot coordinate system is set to align the cutting surface S of the workpiece W (YZ plane or ZX plane) with the robot coordinate system based on the plasma cutting robot 20. In this case, during tracing control, the tracing direction D of the torch 21, which is perpendicular to the cutting surface S of the workpiece W, will coincide with the Y-axis direction or the X-axis direction.

[0054] Furthermore, if the cutting surface S of the workpiece W is not horizontal (parallel) or perpendicular to the installation surface of the plasma cutting robot 20, for example, the plane (cutting surface S) constituting the workpiece W may be inclined, or it may have other complex shapes. In this case, the reference coordinate system (XYZ axes) based on the cutting surface S of the workpiece W is different from the robot coordinate system based on the plasma cutting robot 20. The robot control device 100 includes a coordinate system control unit that processes the reference coordinate system (XYZ axes) based on the cutting surface S of the workpiece W and the robot coordinate system based on the plasma cutting robot 20 in correspondence, and the coordinate system control unit may calculate and process the position and orientation of the cutting surface S of the workpiece W and the torch 21 while calibrating between the reference coordinate system and the robot coordinate system.

[0055] [Plasma cutting method] Next, we will specifically and in detail describe a method in which the robot control device 100 operates the plasma cutting robot 20 according to the teaching program while performing plasma cutting with imitation control.

[0056] Figure 6 is a flowchart showing the processing flow of a plasma cutting method M100 performed by a robot control device 100 according to one embodiment of the present invention. As shown in Figure 6, the plasma cutting method M100 includes steps S110 to S150, each step being performed by a processor included in the robot control device 100.

[0057] In step S110, the robot control device 100 operates the plasma cutting robot 20 (including the torch 21) according to the teaching program to start plasma cutting (robot control step). Specifically, the robot control unit 120 operates the plasma cutting robot 20 (including the torch 21) according to the teaching program stored in the memory unit 110.

[0058] In step S120, the robot control device 100 calculates the distance between the torch 21 and the workpiece W (distance calculation step). Specifically, the distance calculation unit 130 calculates the distance between the tip of the torch 21 and the cutting position P on the cutting surface S of the workpiece W in the direction in which the tip of the torch 21 is extended. The distance calculation unit 130 may also calculate the distance by monitoring the voltage applied between the tip of the torch 21 and the workpiece W and comparing the voltage with a reference voltage.

[0059] In step S130, the robot control device 100 determines whether the distance calculated in step S120 is the cutting distance between the tip of the torch 21 and the cutting position P (cutting surface S) on the workpiece W when performing plasma cutting. Specifically, if the robot control device 100 is performing plasma cutting by moving the torch 21 in the cutting direction and the distance calculated in step S120 remains constant as the cutting distance ("Yes" in step S130), it returns to the process in step S120 and continues the process.

[0060] On the other hand, while the robot control device 100 is moving the torch 21 in the cutting direction and performing plasma cutting, if the distance calculated in step S120 changes and deviates from the cutting distance ("No" in step S130), it proceeds to the processes in steps S140 and S150 and performs imitation control.

[0061] Furthermore, the determination of whether the distance calculated in step S120 is the cutting distance does not only depend on whether the distance is an exact match to the cutting distance, but may also be made if the distance is within a predetermined range relative to the cutting distance (for example, within ±10%). In addition, if the distance deviates significantly from the cutting distance (for example, by more than ±10%), the robot control device 100 may not perform the follow-up control to proceed to steps S140 and S150, determine that it is an abnormality, and stop the plasma cutting robot 20 (including the torch 21).

[0062] In step S140, the robot control device 100 calculates the posture of the torch 21 relative to the workpiece W (posture calculation step). Specifically, the cutting surface setting unit sets how the cutting surface S of the workpiece W is set in relation to the plasma cutting robot 20, and the posture calculation unit 140 calculates the posture (tilt) of the torch 21 relative to the cutting surface S of the workpiece W.

[0063] In step S150, the robot control device 100 corrects the position of the torch 21 in the tracing direction based on the distance calculated in step S120 and the orientation calculated in step S140 (correction step). Specifically, the correction unit 150 corrects (moves) the torch 21 in the tracing direction while maintaining the inclination of the torch 21 with respect to the cutting surface S of the workpiece W, so as to keep the distance between the tip of the torch 21 and the cutting surface S of the workpiece W constant in the direction in which the tip of the torch 21 is extended.

[0064] As described above, according to the robot control device 100 and plasma cutting method M100 of one embodiment of the present invention, the distance calculation unit 130 calculates the distance between the torch 21 and the cutting surface S (cutting position P) on the workpiece W, the posture calculation unit 140 calculates the posture (tilt) of the torch 21 with respect to the cutting surface S on the workpiece W, and the correction unit 150 corrects the position of the torch 21 in a tracing direction perpendicular to the cutting surface S on the workpiece W, based on the distance calculated by the distance calculation unit 130 and the posture (tilt) calculated by the posture calculation unit 140, in order to maintain the cutting distance when plasma cutting the workpiece W. Then, the robot control unit 120 controls the operation of the plasma cutting robot 20 while correcting the position of the torch 21 by the correction unit 150 (tracing control), so that the distance between the tip of the torch 21 and the cutting surface S on the workpiece W is kept constant, and the workpiece W can be cut appropriately at the cutting position P on the cutting surface S.

[0065] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The elements, arrangement, materials, conditions, shapes, and sizes of the embodiments are not limited to those exemplified and can be modified as appropriate. Furthermore, it is possible to partially substitute or combine the configurations shown in different embodiments. [Explanation of Symbols]

[0066] 10…Plasma cutting robot system, 20…Plasma cutting robot, 21…Torch, 30…Teach pendant, 40…Plasma power supply unit, 100…Robot control unit, 110…Memory unit, 120…Robot control unit, 130…Distance calculation unit 130, 140…Attitude calculation unit, 150…Correction unit, M100…Plasma cutting method, S110~S150…Each step in plasma cutting method M100, S, S1, S2…Cutting surface, P, P1, P2…Cutting position, W, W1, W2…Workpiece (workpiece position), D…Tracing direction

Claims

1. A teaching playback type robot control device that controls the operation of a plasma cutting robot according to a teaching program programmed by teaching, A robot control unit that controls the operation of the plasma cutting robot according to the teaching program, A distance calculation unit that calculates the distance between the torch attached to the plasma cutting robot and the cutting position on the object to be cut, A posture calculation unit that calculates the posture of the torch with respect to the cutting surface to which the cutting position in the object to be cut belongs, The system includes a correction unit that corrects the position of the torch in a tracing direction perpendicular to the cutting surface, based on the distance calculated by the distance calculation unit and the attitude calculated by the attitude calculation unit, in order to maintain the cutting distance for plasma cutting the object to be cut. The robot control unit controls the operation of the plasma cutting robot while correcting at least the position of the torch using the correction unit. Robot control device.

2. The system further includes a section setting unit for setting a reference coordinate system based on the aforementioned section. The robot control device according to claim 1.

3. The cutting surface setting unit receives the cutting surface in a robot coordinate system that has been set in advance for the plasma cutting robot. The robot control device according to claim 2.

4. The system further includes a coordinate system control unit that controls the processing of a reference coordinate system set by the cutting surface setting unit and a robot coordinate system pre-set on the plasma cutting robot, in correspondence with each other. The robot control device according to claim 2.

5. A plasma cutting method performed by a teaching playback type robot control device that controls the operation of a plasma cutting robot according to a teaching program programmed by teaching, A robot control step that controls the operation of the plasma cutting robot according to the teaching program, A distance calculation step for calculating the distance between the torch attached to the plasma cutting robot and the cutting position on the object to be cut, A posture calculation step for calculating the posture of the torch with respect to the cutting surface to which the cutting position in the object to be cut belongs, The correction step includes correcting the position of the torch in a tracing direction perpendicular to the cutting surface, based on the distance calculated in the distance calculation step and the attitude calculated in the attitude calculation step, in order to maintain the cutting distance for plasma cutting the object to be cut, The robot control step controls the operation of the plasma cutting robot while correcting at least the position of the torch in the correction step. Plasma cutting method.

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