Robot control device and plasma cutting method

Abstract

The invention provides a robot control device and a plasma cutting method which can keep the distance between the front end of a cutting torch and the surface of a workpiece constant and appropriately cut at the cutting position of the workpiece. This robot control device is provided with: a robot control unit (120) that controls the operation of a plasma cutting robot (20) in accordance with a demonstration program; a distance calculation unit (130) that calculates the distance between the cutting torch (21) and the cutting position of the cutting target; a posture calculation unit (140) that calculates the posture of the cutting torch with respect to a cutting surface to which the cutting position of the cutting target belongs; and a correction unit (150) that, on the basis of the distance calculated by the distance calculation unit and the orientation calculated by the orientation calculation unit, corrects at least the position of the cutting torch in a profiling direction orthogonal to the cutting surface so as to maintain a cutting distance at which plasma cutting is performed on 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 cutting torch by the correction unit.

Description

Technical Field

[0001] This invention relates to a robot control device and a plasma cutting method. Background Technology

[0002] A plasma cutting robot performs plasma cutting by moving a torch along a pre-set cutting line, which is taught to the user, thereby cutting the workpiece. Here, for the plasma cutting robot, it is important to move the torch while maintaining a constant distance between the tip of the torch and the cutting surface of the workpiece.

[0003] Patent document 1 discloses the following: measuring the arc voltage and comparing the measured arc voltage with a set reference arc voltage, thereby keeping the distance between the cutting torch and the cutting surface of the workpiece constant.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2012-110966 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, in the technology disclosed in Patent Document 1, the method for correcting the position of the torch during plasma cutting of a bevel while the torch is tilted relative to the workpiece's cutting surface is not considered. In order to keep the distance between the tip of the torch and the workpiece's cutting surface constant, if the torch is moved directly towards or away from the workpiece's cutting surface, the cutting position on the workpiece's cutting surface pointed to by the tip of the torch may shift if the torch is tilted relative to the workpiece's cutting surface.

[0009] Therefore, the object of the present invention is to provide a robot control device and a plasma cutting method capable of maintaining a constant distance between the tip of the cutting torch and the cutting surface of the workpiece and performing cutting at an appropriate cutting position on the cutting surface of the workpiece.

[0010] Solution for solving the problem

[0011] One aspect of the present invention relates to a robot control device that is a teach-and-playback type robot control device that controls the movement of a plasma cutting robot according to a demonstration program programmed by demonstration. The robot control device includes: a robot control unit that controls the movement of the plasma cutting robot according to the demonstration program; a distance calculation unit that calculates the distance between the cutting torch mounted on the plasma cutting robot and the cutting position of the object being cut; a posture calculation unit that calculates the posture of the cutting torch relative to the cutting surface to which the cutting position of the object being cut belongs; and a correction unit that corrects the position of the cutting torch at least in a contouring direction orthogonal to the cutting surface based on the distance calculated by the distance calculation unit and the posture calculated by the posture calculation unit, so as to maintain the cutting distance for plasma cutting of the object. The robot control unit controls the movement of the plasma cutting robot while correcting the position of the cutting torch at least by the correction unit.

[0012] According to this scheme, the distance calculation unit calculates the distance between the cutting torch and the cutting position of the object being cut, the posture calculation unit calculates the posture of the cutting torch relative to the cutting surface to which the cutting position belongs, and the correction unit corrects the position of the cutting torch at least in a contouring direction orthogonal to the cutting surface based on the distance calculated by the distance calculation unit and the posture calculated by the posture calculation unit, so as to maintain the cutting distance for plasma cutting of the object. Furthermore, the robot control unit controls the motion of the plasma cutting robot while correcting the position of the cutting torch at least by the correction unit, thus maintaining a constant distance between the tip of the cutting torch and the cutting surface of the object being cut, and appropriately cutting at the cutting position on the cutting surface of the object being cut.

[0013] In the above scheme, the robot control device may also include a cutting surface setting unit that sets a reference coordinate system based on the cutting surface.

[0014] According to this scheme, the position of the cutting surface can be properly controlled, thus the distance between the cutting torch and the cutting position, as well as the posture of the cutting torch relative to the cutting surface, can be properly controlled, thereby allowing for appropriate correction of the position of the cutting torch in the contouring direction.

[0015] In the above scheme, the cutting surface setting unit may also receive the cutting surface in the robot coordinate system of the plasma cutting robot that is preset.

[0016] According to this scheme, the position of the cutting surface can be properly controlled in the robot coordinate system. Therefore, the distance between the torch and the cutting position and the posture of the torch relative to the cutting surface can be properly controlled, thereby appropriately correcting the position of the torch in the contouring direction.

[0017] In the above scheme, the robot control device may also include a coordinate system control unit, which controls the robot by establishing a correspondence between the reference coordinate system set by the cutting surface setting unit and the robot coordinate system pre-set in the plasma cutting robot and performing the corresponding processing.

[0018] According to this scheme, the coordinate system control unit controls the system by establishing a correspondence between the reference coordinate system and the robot coordinate system and processing the data. Therefore, it can appropriately control the distance between the torch and the cutting position and the torch's posture relative to the cutting surface according to various configurations of the cutting surface, thereby appropriately correcting the torch's position in the contouring direction.

[0019] One aspect of the present invention relates to a plasma cutting method executed by a teach-and-playback robot control device that controls the movement of a plasma cutting robot according to a demonstration program programmed by demonstration. The plasma cutting method includes: a robot control step for controlling the movement of the plasma cutting robot according to the demonstration program; a distance calculation step for calculating the distance between the cutting torch mounted on the plasma cutting robot and the cutting position of the object being cut; a posture calculation step for calculating the posture of the cutting torch relative to the cutting surface of the cutting position of the object being cut; and a correction step for correcting the position of the cutting torch, at least in a contouring direction orthogonal to the cutting surface, based on the distance calculated in the distance calculation step and the posture calculated in the posture calculation step, to maintain the cutting distance for plasma cutting of the object. In the robot control step, the movement of the plasma cutting robot is controlled while at least the position of the cutting torch is corrected in the correction step.

[0020] According to this scheme, in the distance calculation step, the distance between the cutting torch and the cutting position of the object being cut is calculated; in the posture calculation step, the posture of the cutting torch relative to the cutting surface to which the cutting position belongs is calculated; and in the correction step, based on the distance calculated in the distance calculation step and the posture calculated in the posture calculation step, the position of the cutting torch is corrected at least in a contouring direction orthogonal to the cutting surface to maintain the cutting distance for plasma cutting of the object. Furthermore, in the robot control step, the motion of the plasma cutting robot is controlled while the position of the cutting torch is corrected at least in the correction step, thus maintaining a constant distance between the tip of the cutting torch and the cutting surface of the object being cut, and appropriately cutting at the cutting position on the cutting surface of the object being cut.

[0021] Invention Effects

[0022] According to the present invention, a robot control device and a plasma cutting method are provided that can keep the distance between the tip of the cutting torch and the cutting surface of the workpiece constant and perform cutting at a suitable cutting position on the cutting surface of the workpiece. Attached Figure Description

[0023] Figure 1 This is a system schematic diagram illustrating a plasma cutting robot system 10 according to an embodiment of the present invention.

[0024] Figure 2 This is a functional block diagram illustrating the functions of a robot control device 100 according to an embodiment of the present invention.

[0025] Figure 3 This diagram illustrates a situation where the cutting torch 21 is moved along the cutting direction at an angle relative to the cutting surface S of the workpiece W to perform plasma cutting (bevel cutting).

[0026] Figure 4 This diagram illustrates the situation where the position of the cutting torch 21 is corrected while maintaining its tilt relative to the cutting surface of the workpiece, in the case where the position of the workpiece has shifted.

[0027] Figure 5 This 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.

[0028] Figure 6 This is a flowchart illustrating the process of plasma cutting method M100 executed by robot control device 100 according to an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached figures

[0030] 10…Plasma cutting robot system, 20…Plasma cutting robot, 21…Cutting torch, 30…Teach pendant, 40…Plasma power supply device, 100…Robot control device, 110…Storage unit, 120…Robot control unit, 130…Distance calculation unit, 140…Attitude calculation unit, 150…Correction unit, M100…Plasma cutting method, S110~S150…Steps in plasma cutting method M100, S, S1, S2…Cutting surfaces, P, P1, P2…Cutting positions, W, W1, W2…Workpiece (workpiece position), D…Following direction Detailed Implementation

[0031] Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. It should be noted that the embodiments described below are merely specific examples for implementing the present invention and are not intended to limit the scope of the invention. Furthermore, to facilitate understanding, the same reference numerals will be used as much as possible to denote the same constituent elements in the drawings, and sometimes repeated descriptions will be omitted.

[0032] <One Implementation Method>

[0033] [Overview of the Plasma Cutting Robot System]

[0034] Figure 1 This is a system schematic diagram illustrating a plasma cutting robot system 10 according to an embodiment of the present invention. Figure 1 As shown, 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.

[0035] The plasma cutting robot 20 is connected to the robot control device 100 via a cable and performs plasma cutting based on the motion commands from the robot control device 100. The plasma cutting robot 20 has a cutting torch 21 at the front end of its arm, and performs plasma cutting by generating an electric arc between the tip of the cutting torch 21 and the metal material (workpiece) to be cut.

[0036] The cutting torch 21 is connected to the plasma power supply device 40 via a cable, receiving voltage and current. In plasma cutting, when the cutting torch 21 comes into instantaneous contact with the metal material and is energized, an electric arc discharge is generated between the tip of the cutting torch 21 and the metal material. The heat generated by the electric arc is used to melt the metal material, thereby performing plasma cutting.

[0037] The teach pendant 30 receives input from the operator performing the plasma cutting operation regarding plasma cutting associated demonstration information of the plasma cutting robot 20. The operator confirms the state of the electric arc and uses the teach pendant 30 to input the optimal plasma cutting associated demonstration information.

[0038] Here, the plasma cutting demonstration information refers to information related to plasma cutting performed by the plasma cutting robot 20, including demonstration information illustrating the movements of the plasma cutting robot 20 and plasma cutting conditions. The demonstration information for the plasma cutting robot 20 includes information related to the movements of the arm of the plasma cutting robot 20, information related to the position and posture of the plasma cutting robot 20, and information related to the tip of the cutting torch 21. Furthermore, the plasma cutting conditions include the arc voltage applied to the cutting torch 21, the arc current flowing through the cutting torch 21, and the cutting speed, which indicates the speed at which the cutting torch 21 moves in the cutting direction.

[0039] The robot control device 100 is a device for controlling the plasma cutting robot 20. The robot control device 100 is connected to the teach pendant 30 and can acquire plasma cutting-related demonstration information input to the teach pendant 30. Based on this plasma cutting-related demonstration information, the robot control device 100 controls the plasma cutting robot 20 and the plasma power supply device 40.

[0040] The plasma power supply device 40 is connected to the plasma cutting robot 20 via a cable and supplies arc voltage and arc current to the cutting torch 21 in the plasma cutting robot 20 based on instructions from the robot control device 100.

[0041] It should be noted that, in Figure 1 In this setup, the teach pendant 30 is connected to the robot control device 100 via a cable, but it can also be connected wirelessly. That is, the teach pendant 30 and the robot control device 100 can be equipped with a communication unit for wireless communication. By wirelessly connecting the robot control device 100 and the teach pendant 30, the operator does not need to worry about the presence of cables or be limited by the range of movement based on the length of the cables, and can input plasma cutting-related demonstration information while moving freely.

[0042] [Structure of the robot control device]

[0043] Figure 2 This is a functional block diagram illustrating the functions of a robot control device 100 according to an embodiment of the present invention. For example... Figure 2 As shown, the robot control device 100 includes a storage unit 110, a robot control unit 120, a distance calculation unit 130, an attitude calculation unit 140, and a correction unit 150.

[0044] The storage unit 110 stores pre-generated demonstration programs. For example, an operator can use an operating device (demonstration device) such as a teach pendant 30 to set plasma cutting conditions, or register demonstration points while operating the plasma cutting robot 20, thereby generating a demonstration program.

[0045] The robot control unit 120 operates the plasma cutting robot 20 (including the cutting torch 21) according to a demonstration procedure. The robot control device 100 is a teach-and-playback robot control device that is programmed through demonstration to control the actions of the plasma cutting robot 20.

[0046] Furthermore, when the robot control unit 120 moves the plasma cutting robot 20 (including the cutting torch 21) according to the demonstration procedure, the distance between the tip of the cutting torch 21 and the cutting surface of the workpiece may sometimes change due to factors such as the positional shift of the workpiece being cut or the presence of unevenness on the cutting surface of the workpiece.

[0047] In this situation, the robot control unit 120 performs so-called contour control, that is, while correcting the position of the cutting torch 21 in a way that keeps the distance between the tip of the cutting torch 21 and the cutting surface of the workpiece constant, it moves the cutting torch 21 to perform plasma cutting. Contour control is achieved by the distance calculation unit 130, the posture calculation unit 140, and the correction unit 150, which will be described later.

[0048] The distance calculation unit 130 calculates the distance between the cutting torch 21 mounted on the plasma cutting robot 20 and the cutting position of the workpiece. For example, the distance calculation unit 130 calculates the distance between the front end of the cutting torch 21 and the cutting position of the workpiece in the direction extending from the front end of the cutting torch 21.

[0049] More specifically, the distance calculation unit 130 can monitor the voltage applied to the front end of the cutting torch 21 and the cutting position (cutting surface) of the workpiece, and calculate the distance between the front end of the cutting torch 21 and the cutting position (cutting surface) of the workpiece by comparing the voltage with a reference voltage.

[0050] Here, the reference voltage is the voltage corresponding to the cutting distance between the tip of the torch 21 and the cutting position (cutting surface) of the workpiece during plasma cutting. For example, a sensor can be installed at the tip of the torch 21 to pre-determine the voltage corresponding to this cutting distance. When the distance between the tip of the torch 21 and the cutting position (cutting surface) of the workpiece is greater than the cutting distance, the voltage applied to the tip of the torch 21 and the cutting position (cutting surface) of the workpiece is greater than the reference voltage. When the distance between the tip of the torch 21 and the cutting position (cutting surface) of the workpiece is less than the cutting distance, the voltage applied to the tip of the torch 21 and the cutting position (cutting surface) of the workpiece is less than the reference voltage. Thus, the distance calculation unit 130 can calculate the distance between the tip of the torch 21 and the cutting position (cutting surface) of the workpiece.

[0051] The posture calculation unit 140 calculates the posture (tilt) of the cutting torch 21 relative to the cutting surface of the workpiece to be cut. For example, the cutting surface of the workpiece to be cut is preset for the plasma cutting robot 20. Furthermore, the posture calculation unit 140 can also calculate the posture (tilt) of the cutting torch 21 relative to the cutting surface of the workpiece based on the position and posture of the cutting torch 21 based on the angles of each axis of the plasma cutting robot 20.

[0052] Here, regarding the setting of the workpiece relative to the plasma cutting robot 20, typically, the workpiece can be set such that the cutting surface of the workpiece is horizontal (parallel) to the setting surface of the plasma cutting robot 20, or perpendicular to the setting surface of the plasma cutting robot 20.

[0053] Furthermore, regarding how to set the cutting surface of the workpiece for the plasma cutting robot 20, it can be preset by the operator, or the plasma cutting robot 20 can be equipped with sensors (cameras, contact sensors, and optical sensors, etc.) to determine the cutting surface of the workpiece for setting. Alternatively, additional sensors (cameras, contact sensors, and optical sensors, etc.) can be configured to set the cutting surface of the workpiece relative to the plasma cutting robot 20.

[0054] The correction unit 150 corrects the position of the cutting torch 21 at least in the contouring direction orthogonal to the cutting surface of the workpiece based on the distance calculated by the distance calculation unit 130 and the posture calculated by the posture calculation unit 140, so as to maintain the cutting distance for plasma cutting of the workpiece. For example, in bevel cutting of plasma cutting with the cutting torch 21 tilted relative to the cutting surface of the workpiece, the correction unit 150 corrects (moves) the cutting torch 21 in the contouring direction while maintaining the tilt of the cutting torch 21 relative to the cutting surface of the workpiece, thereby keeping the distance between the tip of the cutting torch 21 and the cutting surface of the workpiece in the direction extending from the tip of the cutting torch 21 constant.

[0055] [Details on contour control]

[0056] The following is a detailed description of the contour control performed by the robot control device 100 according to an embodiment of the present invention.

[0057] Figure 3 This diagram illustrates a situation where the cutting torch 21 is moved along the cutting direction at an angle relative to the cutting surface S of the workpiece W to perform plasma cutting (bevel cutting). Figure 3 As shown, the cutting torch 21 is tilted and points to the cutting position P on the cutting surface S of the workpiece W in the direction of extending the front end of the cutting torch 21.

[0058] When performing plasma cutting using the plasma cutting robot 20, the distance between the front end of the extended inclined cutting torch 21 and the cutting surface S (cutting position P) of the workpiece is kept constant, while the inclined cutting torch 21 is moved in the cutting direction to cut the workpiece W.

[0059] Figure 4 This diagram illustrates how the position of the cutting torch 21 is corrected while maintaining its tilt relative to the cutting surface of the workpiece, even when the workpiece's position has shifted. (See diagram for example.) Figure 4 As shown, the workpiece shifts from the position of workpiece W1 to the position of workpiece W2.

[0060] In this way, when the position of the workpiece is offset in a direction orthogonal to the cutting surface of the workpiece, the robot control unit 120 moves the torch 21 to perform plasma cutting by correcting the position of the torch 21 in a way that keeps the distance between the tip of the torch 21 and the cutting surface of the workpiece constant through contour control.

[0061] Specifically, when the workpiece is positioned as workpiece W1, it is the distance d1 between the front end of the cutting torch 21 in the direction of its extended inclined state and the cutting surface S1 (cutting position P1) of the workpiece.

[0062] Furthermore, if the position of the workpiece is shifted towards workpiece W2, the distance between the front end of the cutting torch 21 and the cutting surface (cutting position) of the workpiece cannot be kept constant in the direction of the front end of the cutting torch 21 in the extended inclined state unless the position of the cutting torch 21 is not corrected at least from workpiece W1 to workpiece W2.

[0063] Therefore, the position of the cutting torch 21 in the tilted state is corrected. The direction of the corrected cutting torch 21 is a direction orthogonal to the cutting surface S1 (S2) of the workpiece W1 (W2) (the contouring direction). The distance of the corrected cutting torch 21 is the same as the distance d2 between the front end of the cutting torch 21 and the cutting surface S2 (cutting position P2) of the workpiece in the direction extending from the front end of the cutting torch 21 in the tilted state.

[0064] That is, when the workpiece shifts from the position of workpiece W1 to the position of workpiece W2, the position of the inclined cutting torch 21 is corrected by a distance h in the contouring direction orthogonal to the cutting surface S1 (S2) of the workpiece through contouring control. As a result, the inclined cutting torch 21 can maintain its tilt (angle) while keeping the distance between the tip of the cutting torch 21 and the cutting position P1 (P2) on the cutting surface S1 (S2) of the workpiece W1 (W2) constant in the direction extending from the tip of the cutting torch 21, and the tip of the cutting torch 21 is appropriately pointed to the cutting position P1 (P2) on the cutting surface S1 (S2) of the workpiece W1 (W2), thereby performing plasma cutting.

[0065] Figure 5 This 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. (See diagram for example.) Figure 5 As shown, the reference coordinate system (XYZ coordinate system) based on the cutting surface S of the workpiece W is set to be consistent with the robot coordinate system based on the plasma cutting robot 20.

[0066] 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. As described above, the cutting surface setting unit accepts settings based on the operator or using sensors, etc.

[0067] For example, when the workpiece W is set up so that the cutting surface S of the workpiece W is horizontal (parallel) to the setting surface of the plasma cutting robot 20, the cutting surface S (XY plane) of the workpiece W is set to be consistent with the robot coordinate system based on the plasma cutting robot 20.

[0068] When the cutting surface S (XY plane) of the workpiece W is set to be consistent with the robot coordinate system based on the plasma cutting robot 20, in the contour control, the contouring direction D of the torch 21 orthogonal to the cutting surface S of the workpiece W is aligned with the Z-axis direction.

[0069] It should be noted that, here, the workpiece W is set up so that its cutting surface S is horizontal (parallel) to the setting surface of the plasma cutting robot 20, but this is not a limitation. For example, if the workpiece W is set up so that its cutting surface S is perpendicular to the setting surface of the plasma cutting robot 20, or if the workpiece W is an H-shaped steel and its cutting surface S is located perpendicular to the setting surface of the plasma cutting robot 20, the cutting surface S (YZ plane or ZX plane) of the workpiece W is set to be consistent with the robot coordinate system based on the plasma cutting robot 20. In this case, in contour control, the contouring direction D of the torch 21, orthogonal to the cutting surface S of the workpiece W, is aligned with either the Y-axis or X-axis direction.

[0070] Furthermore, when the cutting surface S of the workpiece W is not horizontal (parallel) or perpendicular to the mounting surface of the plasma cutting robot 20, for example, considering the tilt of the plane constituting the workpiece W (cutting surface S) or other complex shapes, 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 establishes a correspondence between 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 and processes it. This coordinate system control unit can calculate and process the position and posture of the cutting surface S of the workpiece W and the cutting torch 21 while calibrating in the reference coordinate system and the robot coordinate system.

[0071] [Plasma cutting method]

[0072] Next, a detailed explanation will be given of the method of performing plasma cutting while the robot control device 100 moves the plasma cutting robot 20 according to the demonstration procedure.

[0073] Figure 6 This is a flowchart illustrating the processing flow of a plasma cutting method M100 executed by a robot control device 100 according to an embodiment of the present invention. Figure 6 As shown, the plasma cutting method M100 includes steps S110 to S150, each step being executed by a processor included in the robot control device 100.

[0074] In step S110, the robot control device 100 operates the plasma cutting robot 20 (including the cutting torch 21) according to a demonstration program (robot control step) to begin plasma cutting. As a specific example, the robot control unit 120 operates the plasma cutting robot 20 (including the cutting torch 21) according to a demonstration program stored in the storage unit 110.

[0075] In step S120, the robot control device 100 calculates the distance between the cutting torch 21 and the workpiece W (distance calculation step). Specifically, the distance calculation unit 130 calculates the distance in the direction extending from the tip of the cutting torch 21 to the cutting position P on the cutting surface S of the workpiece W. The distance calculation unit 130 can monitor the voltage applied to the tip of the cutting torch 21 and the workpiece W, and calculate the distance by comparing this voltage with a reference voltage.

[0076] In step S130, the robot control device 100 determines whether the distance calculated in step S120 is the cutting distance between the front end of the torch 21 and the cutting position P (cutting surface S) of the workpiece W during plasma cutting. As a specific example, if the distance calculated in step S120 is kept constant as the cutting distance during plasma cutting by moving the torch 21 in the cutting direction ("Yes" in step S130), the robot control device 100 returns to the processing in step S120 and continues processing directly.

[0077] On the other hand, when the robot control device 100 moves the cutting torch 21 in the cutting direction to perform plasma cutting, if the distance calculated in step S120 changes and deviates from the cutting distance (No in step S130), it proceeds to the processing of steps S140 and S150 to perform contour control.

[0078] It should be noted that, here, the determination of whether the distance calculated in step S120 is the cutting distance is not only based on whether the distance is exactly the same as the cutting distance, but also on whether the distance is within a specified range relative to the cutting distance (e.g., within ±10%). Furthermore, if the distance deviates significantly from the cutting distance (e.g., more than ±10%), the contour control will not proceed to steps S140 and S150, and an anomaly will be determined. The robot control device 100 may then stop the plasma cutting robot 20 (including the cutting torch 21).

[0079] In step S140, the robot control device 100 calculates the posture of the cutting torch 21 relative to the workpiece W (posture calculation step). As a specific example, the cutting surface setting unit is used to set how to set the cutting surface S of the workpiece W in the positional relationship with the plasma cutting robot 20, and the posture calculation unit 140 calculates the posture (tilt) of the cutting torch 21 relative to the cutting surface S of the workpiece W.

[0080] In step S150, the robot control device 100 corrects the position of the cutting torch 21 in the contouring direction (correction step) based on the distance calculated in step S120 and the posture calculated in step S140. As a specific example, the correction unit 150 corrects (moves) the cutting torch 21 in the contouring direction while maintaining the cutting torch 21 at an inclination relative to the cutting surface S of the workpiece W, so as to keep the distance between the front end of the cutting torch 21 and the cutting surface S of the workpiece W in the direction extending from the front end of the cutting torch 21 constant.

[0081] As described above, according to an embodiment of the present invention, the robot control device 100 and the plasma cutting method M100 involve a distance calculation unit 130 calculating the distance between the cutting torch 21 and the cutting surface S (cutting position P) of the workpiece W, a posture calculation unit 140 calculating the posture (tilt) of the cutting torch 21 relative to the cutting surface S of the workpiece W, and a correction unit 150 correcting the position of the cutting torch 21 in a contouring direction orthogonal to the cutting surface S of 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, so as to maintain the cutting distance when plasma cutting the workpiece W. Furthermore, the robot control unit 120 controls the operation of the plasma cutting robot 20 while correcting the position of the cutting torch 21 (performing contouring control) using the correction unit 150, thus maintaining a constant distance between the tip of the cutting torch 21 and the cutting surface S of the workpiece W, and appropriately cutting at the cutting position P on the cutting surface S of the workpiece W.

[0082] The embodiments described above are for the purpose of facilitating understanding of the present invention and are not intended to limit the interpretation of the present invention. The elements, their configurations, materials, conditions, shapes, and dimensions included in the embodiments are not limited to the illustrated elements, their configurations, materials, conditions, shapes, and dimensions, and can be appropriately modified. Furthermore, the structures shown in different embodiments can be partially substituted or combined with each other.

Claims

1. A robot control device that controls an action of a plasma cutting robot in accordance with a demonstration program programmed by demonstration, wherein the robot control device comprises: a robot control section that controls an action of the plasma cutting robot in accordance with the demonstration program; a distance calculation section that calculates a distance from a cutting torch mounted to the plasma cutting robot to a cutting position of a cutting object; a posture calculation section that calculates a posture of the cutting torch with respect to a cutting surface to which the cutting position of the cutting object belongs; and a correction section that corrects at least a position of the cutting torch in a profiling direction orthogonal to the cutting surface based on the distance calculated by the distance calculation section and the posture calculated by the posture calculation section to maintain a cutting distance of plasma cutting of the cutting object, the robot control section controls the action of the plasma cutting robot while correcting at least the position of the cutting torch by the correction section.

2. The robot control device according to claim 1, wherein the robot control device further comprises a cutting surface setting section that sets a reference coordinate system with reference to the cutting surface.

3. The robot control device according to claim 2, wherein the cutting surface setting section receives the cutting surface in a robot coordinate system set in advance to the plasma cutting robot.

4. The robot control device according to claim 2, wherein the robot control device further comprises a coordinate system control section that controls in a manner that a reference coordinate system set by the cutting surface setting section and a robot coordinate system set in advance to the plasma cutting robot are in a corresponding relationship and are processed.

5. A plasma cutting method that is performed by a robot control device that controls an action of a plasma cutting robot in accordance with a demonstration program programmed by demonstration, wherein the plasma cutting method comprises: a robot control step that controls an action of the plasma cutting robot in accordance with the demonstration program; a distance calculation step that calculates a distance from a cutting torch mounted to the plasma cutting robot to a cutting position of a cutting object; a posture calculation step that calculates a posture of the cutting torch with respect to a cutting surface to which the cutting position of the cutting object belongs; and a correction step that corrects at least a position of the cutting torch in a profiling direction orthogonal to the cutting surface based on the distance calculated in the distance calculation step and the posture calculated in the posture calculation step to maintain a cutting distance of plasma cutting of the cutting object, in the robot control step, an action of the plasma cutting robot is controlled while the position of the cutting torch is corrected at least in the correction step. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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