Robot control method

Abstract

To provide a robot control method capable of suppressing a decrease in processing efficiency per unit time in a production line, processing system, or the like.SOLUTION: A robot control method comprises: a workpiece removal step (S103) of gripping, by an actuator, a middle portion of an unmachined workpiece placed on a pallet so that a workpiece axis of the unmachined workpiece and a sixth axis about which the actuator can rotate are positioned perpendicular to each other, and then moving the workpiece into a machining space to position the workpiece at a predetermined position within the machining space; a workpiece rotation step (S107) of controlling a wrist, a second arm, a first arm, and body so that the actuator gripping the workpiece positioned at the predetermined position rotates together with the wrist around the workpiece axis without rotating about the sixth axis; and a workpiece return step (S111) of moving the machined workpiece machined within a period provided by the workpiece rotation step (S107) to another pallet and placing the machined workpiece there.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a method for controlling a robot, typically a vertically articulated robot. [Background technology]

[0002] Examples of vertically articulated robots include those disclosed in the following Patent Documents 1 and 2. This type of robot has a higher degree of freedom and a wider operating range than horizontally articulated robots and coordinate axis robots. As such, it is used as an industrial robot for a variety of purposes, such as transportation, welding, and painting, in factory production lines and processing systems.

[0003] Incidentally, some workpieces transported by robots have a long, thin rod shape. When a vertically articulated robot transports such a rod-shaped workpiece, the robot hand approaches the workpiece from the axial direction or radial direction of the workpiece axis, for example, to grasp it. The approach of the hand to such a workpiece is often designed in a manner that takes into account the handling conditions of the workpiece at the destination, in order to ensure the smoothest possible transfer of the workpiece to the next process.

[0004] For example, when a workpiece is transferred to the next process lying on its side on a pallet or standing upright in a pocket at the destination, the hand approaches the workpiece from the radial direction of the workpiece axis to grip the middle part of the workpiece or its vicinity. This is because approaching from the radial direction provides a wider grippable range (near the middle part of the workpiece, etc.) than approaching from the axial direction to grip the end part of the workpiece, and it is also easier to place the workpiece lying on its side.

[0005] On the other hand, if it is necessary to rotate the workpiece around its axis at the destination for the convenience of the next process, for example, the hand approaches from the axial direction and grasps the end of the workpiece. Since the wrist to which the robot hand is attached is often configured to be rotatable around its axis, the workpiece can be easily rotated around the workpiece axis by rotating the hand that has grasped the end of the workpiece from the axial direction around the axis of the wrist. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-139762 [Patent Document 2] Japanese Patent Application Publication No. 2024-9167 Summary of the Invention [Problem to be solved by the invention]

[0007] However, even when it is necessary to rotate the workpiece around its axis at the destination for the next process, there are cases where the end of the workpiece cannot be grasped by the robot hand. For example, in cases where the end of the workpiece corresponding to the gripping position is coated with a solvent or chemical that could impair its effectiveness or function if the hand comes into contact with the end, or in cases where the end of the workpiece is set in a non-contact area for quality control purposes, the end cannot be grasped by the hand.

[0008] In such cases, one possible method is to approach the workpiece from the radial direction of the workpiece axis, grip the workpiece near its middle, transport it to the intermediate table, lay it on its side so that the end (one end) does not come into contact with the table surface, and then grip the other end on the opposite side from the axial direction and transport it. This makes it possible to easily rotate the workpiece around the workpiece axis in the next process, just as in cases where gripping the gripping position is permitted.

[0009] However, if a method of using a robot hand to re-grasp the workpiece via such an intermediate table is adopted, the time required to place the workpiece on the intermediate table and the time required to re-grasp it will be added, which will lengthen the time it takes to transport the workpiece by the hand, potentially creating a new problem of reduced processing efficiency per unit time in production lines and processing systems.

[0010] The present invention has been made to solve the above-mentioned problems, and aims to provide a robot control method that can suppress a decrease in processing efficiency per unit time in a production line, processing system, etc. [Means for solving the problem]

[0011] To achieve the above object, the present invention employs the technical means of claim 1. According to this means, a method for controlling a vertically articulated robot includes a first step, a second step, and a third step. The robot includes at least a base placed on an installation surface, a torso supported by the base so as to be rotatable about a first axis perpendicular to the installation surface, a first arm supported at its base end by the torso so as to be swingable about a second axis perpendicular to the first axis, a second arm supported at its base end by the tip of the first arm so as to be swingable about a third axis parallel to the second axis and having a tip end rotatable about a fourth axis perpendicular to the third axis, a wrist offset from the second arm and supported at its base end by the second arm so as to be swingable about a fifth axis perpendicular to the fourth axis, and a gripper provided at the tip of the wrist so as to be rotatable about a sixth axis perpendicular to the fifth axis.

[0012] In the first step, the gripper grips the middle part of the workpiece (the part excluding both ends of the workpiece) of the rod-shaped workpiece placed on the pallet before machining so that the workpiece axis and the sixth axis around which the gripper can rotate are perpendicular, and then the workpiece is moved into the machining space and positioned at a predetermined position within the machining space. In other words, the gripper approaches the workpiece before machining from its radial direction, grips the middle part of the workpiece, and moves it to a predetermined position within the machining space. In the second step, the wrist, second arm, first arm, and torso are controlled so that the gripper gripping the workpiece positioned at the predetermined position rotates around the workpiece axis together with the wrist without rotating on the sixth axis. That is, the wrist is swung about the fifth axis, the second arm is rotated in a predetermined direction about the fourth axis and swung about the third axis, the first arm is swung about the second axis, and the body is rotated about the first axis, thereby rotating the gripper and wrist together so that the workpiece held by the gripper at a predetermined position rotates around the workpiece axis. That is, the gripper and wrist are rotated in the same plane so that the base end of the wrist (the side opposite the tip where the gripper is provided) draws a circle or arc around the workpiece axis. Then, a period is provided during which the workpiece rotated around the workpiece axis at a predetermined position can be subjected to predetermined processing. In the third step, the workpiece processed within the period provided in the second step is moved and placed on a pallet or another pallet. Note that this third step is not necessarily required. In a robot control method, if the second step "provides a period during which the workpiece rotated around the workpiece axis at a predetermined position can be subjected to predetermined processing," the third step is not required for claim 1. However, in this case, it is necessary to add the following to the beginning of claim 3 of the claims: "In the case where, after the second step, the method further includes a third step of moving and placing the processed workpiece held by the gripping portion at the predetermined position on the pallet or another pallet."

[0013] As a result, even if the gripper cannot grip the end of the workpiece, the first step allows the gripper to grip the middle portion of the workpiece before machining, moving the workpiece to a predetermined position within the machining space. Then, in the second step, the gripper and wrist are rotated within the same plane so that the base end of the wrist (the side opposite the tip where the gripper is provided) draws a circle or arc around the workpiece axis, allowing the workpiece to be rotated around the workpiece axis. In other words, the workpiece gripped at its middle portion by the gripper rotates around the workpiece axis while it is still gripped, enabling the desired machining to be performed while the workpiece is rotating. Therefore, as explained in the "Problem to be Solved by the Invention" section, for example, after the workpiece is placed on the relay table, there is no need to re-grasp the other end of the workpiece from the axial direction. This eliminates the time required to place the workpiece on the relay table and re-grasp it. Furthermore, after placing the work on the intermediate table, there is no need to control the gripping unit, wrist, second arm, first arm, or torso, which are required to re-grasp the other end of the work from the axial direction, so control of the robot is less likely to become complicated.

[0014] The technical means of claim 2 is also adopted. According to this means, in the first step, the second arm rotates about the fourth axis in the direction opposite to the predetermined direction between when the workpiece is gripped by the gripper and when it is moved to the predetermined position. As a result, the second arm rotates in the direction opposite to the predetermined direction prior to the second arm rotating in the predetermined direction in the second step.

[0015] The technical means of claim 3 is also adopted. According to this means, in the third step, the second arm rotates about the fourth axis in the direction opposite to the predetermined direction from when the machined workpiece is gripped by the gripper until when it is moved to the pallet or another pallet. As a result, after the second arm rotates in the predetermined direction in the second step, the second arm is rotated in the direction opposite to the predetermined direction in the third step, making it possible to move the workpiece gripped by the gripper to the pallet or another pallet.

[0016] The technical means of claim 4 is also adopted. According to this means, the predetermined position is determined within the machining space within a range from a predetermined angle of 0 degrees, which is coaxial with a predetermined machining reference axis, to a predetermined angle of 90 degrees, which is perpendicular to the machining reference axis. Note that the "predetermined angle" refers to the angle of the workpiece axis relative to the machining reference axis at the predetermined position. This makes it possible to set the predetermined position of the workpiece to be moved and positioned in the first step within the range from a predetermined angle of 0 degrees to a predetermined angle of 90 degrees relative to the machining reference axis.

[0017] The present invention also employs the technical means of claim 5. According to this means, a control program causes a computer that controls a robot to execute the robot control method of any one of claims 1 to 3.

[0018] That is, the present invention is a control program executed by a computer that controls a vertically articulated robot that includes at least: a base that is placed on an installation surface; a torso that is supported by the base so as to be rotatable about a first axis perpendicular to the installation surface; a first arm that has a base end supported by the torso so as to be swingable about a second axis perpendicular to the first axis; a second arm that has a base end supported by the tip of the first arm so as to be swingable about a third axis parallel to the second axis and has a tip end that is rotatable about a fourth axis perpendicular to the third axis; a wrist that is positioned offset from the second arm and has a base end supported by the second arm so as to be swingable about a fifth axis perpendicular to the fourth axis; and a gripper that is provided at the tip of the wrist so as to be rotatable about a sixth axis perpendicular to the fifth axis, and the control program includes the first step, second step, and third step described in the technical means of claim 1 above.

[0019] In a robot controlled by this control program, even if the gripper cannot grip the end of a workpiece, the first step involves gripping the middle portion of the workpiece before machining with the gripper, thereby moving the workpiece to a predetermined position within the machining space. Then, in the second step, the gripper and the wrist are rotated within the same plane so that the base end of the wrist (the side opposite the tip where the gripper is provided) traces a circle or arc around the workpiece axis, thereby enabling the workpiece to be rotated around the workpiece axis. In other words, the workpiece gripped by the gripper at its middle portion rotates around the workpiece axis, enabling the specified machining while the workpiece is rotating. Therefore, as explained in the "Problem to be Solved by the Invention" section, for example, after the workpiece is placed on the relay table, there is no need to re-grasp the other end of the workpiece from the axial direction. This eliminates the time required to place the workpiece on the relay table and re-grasp it. Furthermore, after placing the work on the intermediate table, there is no need to control the gripping unit, wrist, second arm, first arm, or torso, which are required to re-grasp the other end of the work from the axial direction, so control of the robot is less likely to become complicated. [Effects of the Invention]

[0020] In the inventions of claims 1 and 5, the workpiece gripped by the gripper at its middle portion rotates around the workpiece axis while it is still gripped, enabling the specified machining process to be performed while the workpiece is rotating. Therefore, as explained in the "Problem to be Solved by the Invention" section, for example, after placing the workpiece on the relay table, there is no need to re-grasp the other end of the workpiece from the axial direction. This eliminates the time required to place the workpiece on the relay table and to re-grasp it. Furthermore, since there is no need to control the gripper, wrist, second arm, first arm, or torso, which is required to re-grasp the other end of the workpiece from the axial direction after placing it on the relay table, robot control is less complex. Therefore, the time required to transport the workpiece by the gripper is less likely to be long, which can prevent a decrease in machining efficiency per unit time in production lines, machining systems, etc.

[0021] In the invention of claim 2, prior to the second arm rotating in the predetermined direction in the second step, the second arm rotates in the direction opposite to the predetermined direction. Therefore, if the rotatable range of the second arm about the fourth axis is limited and the rotatable range is finite, the rotation range in the predetermined direction in the second step can be expanded by the rotation angle of the second arm rotating in the opposite direction in the first step.

[0022] For example, if the rotation range of the second arm on the fourth axis is -180 degrees to +180 degrees, or 360 degrees, then by rotating the second arm in the opposite direction to -180 degrees (0 degrees) in the first step, it becomes possible to rotate the second arm in the specified direction to +180 degrees (360 degrees) in the second step.

[0023] In the invention of claim 3, after the second arm is rotated in a predetermined direction in the second step, the second arm is rotated in a direction opposite to the predetermined direction in the third step, making it possible to move the workpiece held by the gripper to the pallet or another pallet. Therefore, if the rotatable range of the second arm about the fourth axis is limited and the rotatable range is finite, by rotating the second arm in the predetermined direction in the second step in the opposite direction rather than rotating it in the same predetermined direction, it is possible to move the workpiece held by the gripper to the pallet or another pallet with ample space to move.

[0024] For example, if the rotation range of the second arm on the fourth axis is -180 degrees to +180 degrees, i.e., 360 degrees, after rotating the second arm in a predetermined direction up to +180 degrees (360 degrees) in the second step, the second arm cannot be rotated in the same predetermined direction in the third step. Therefore, by rotating the second arm in the opposite direction in the third step, it becomes possible to move the workpiece held by the gripper to the pallet or another pallet.

[0025] In the invention of claim 4, it is possible to set a predetermined position of the workpiece to be moved and positioned in the first step within a predetermined angle range of 0 degrees to 90 degrees with respect to the machining reference axis. Therefore, the predetermined machining can be performed on the workpiece at an angle within this range during the period provided in the second step. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is an explanatory diagram showing an example of the configuration of one embodiment of a laser processing system including a vertical articulated robot (hereinafter referred to as "the robot" in the "Brief Description of the Drawings" section) controlled by applying the robot control method and control program of the present invention. [Figure 2] FIG. 2 is a block diagram showing an example of a control system of the laser processing system of the present embodiment. [Figure 3] Fig. 3(A) is an explanatory diagram showing an example of the configuration of the robot, and Fig. 3(B) is an explanatory diagram showing a schematic diagram of the link structure of the robot. [Figure 4] 4A and 4B are explanatory diagrams showing an example of the configuration of an actuator corresponding to the hand or end effector of the robot, in which Fig. 4(A) shows the state in which the claws are closed, and Fig. 4(B) shows the state in which the claws are open and gripping a workpiece. [Figure 5] FIG. 2 is an explanatory diagram showing an example of the configuration of a pallet that constitutes the laser processing system of the present embodiment. [Figure 6] 1 is a flowchart showing an example of the flow of laser processing control processing in the laser processing system of this embodiment. Among the processing steps shown in this flowchart, the workpiece loading processing (S103), the workpiece rotation processing (S107), and the workpiece returning processing (S111) are to which the robot control method of the present invention is applied. [Figure 7] 7 is a flowchart showing the processing flow of each subroutine (S103, S107, S111) shown in FIG. 6, where FIG. 7(A) is the workpiece removal processing, FIG. 7(B) is the workpiece rotation processing, and FIG. 7(C) is the workpiece return processing. [Figure 8]This is an explanatory diagram showing an example of the operation of the robot when the workpiece removal process (S201 to S211) shown in Figure 7(A) is performed, and is shown in chronological order (Figure 8(A) → Figure 8(B) → Figure 8(C) → Figure 8(D) → Figure 8(E) → Figure 8(F)). [Figure 9] This is an explanatory diagram showing an example of the robot's operation (at a predetermined angle of 0 degrees relative to the processing reference axis) when the fourth axis reverse rotation process (S213) of the workpiece removal process shown in Figure 7(A) is performed, and is shown in chronological order (Figure 9(G) → Figure 9(H) → Figure 9(I) → Figure 9(J) → Figure 9(K) → Figure 9(L)). [Figure 10] This is an explanatory diagram showing an example of the robot's operation (at a predetermined angle of 0 degrees relative to the processing reference axis) when the workpiece rotation process (S301 to S307) shown in Figure 7(B) is performed, and is shown in chronological order (Figure 10(M) → Figure 10(N) → Figure 10(O) → Figure 10(P) → Figure 10(Q) → Figure 10(R)). [Figure 11] This is an explanatory diagram showing an example of the robot's operation (at a predetermined angle of 0 degrees relative to the processing reference axis) when the workpiece return process (S401 to S409) shown in Figure 7(C) is performed, and is shown in chronological order (Figure 11(S) → Figure 11(T) → Figure 11(U) → Figure 11(V) → Figure 11(W) → Figure 11(X)). [Figure 12] This is an explanatory diagram showing an example of the robot's operation (at a predetermined angle of 45 degrees relative to the processing reference axis) when the fourth axis reverse rotation process (S213) of the workpiece removal process shown in Figure 7(A) is performed, and is shown in chronological order (Figure 12(G) → Figure 12(H) → Figure 12(I) → Figure 12(J) → Figure 12(K) → Figure 12(L)). [Figure 13] This is an explanatory diagram showing an example of the robot's operation (at a predetermined angle of 45 degrees relative to the processing reference axis) when the workpiece rotation process (S301 to S307) shown in Figure 7(B) is performed, and is shown in chronological order (Figure 13(M) → Figure 13(N) → Figure 13(O) → Figure 13(P) → Figure 13(Q) → Figure 13(R)). [Figure 14]This is an explanatory diagram showing an example of the robot's operation (at a predetermined angle of 45 degrees relative to the processing reference axis) when the workpiece return process (S401 to S409) shown in Figure 7(C) is performed, and is shown in chronological order (Figure 14(S) → Figure 14(T) → Figure 14(U) → Figure 14(V) → Figure 14(W) → Figure 14(X)). [Figure 15] This is an explanatory diagram showing an example of the robot's operation (at a predetermined angle of 90 degrees relative to the processing reference axis) when the fourth axis reverse rotation process (S213) of the workpiece removal process shown in Figure 7(A) is performed, and is shown in chronological order (Figure 15(G) → Figure 15(H) → Figure 15(I) → Figure 15(J) → Figure 15(K) → Figure 15(L)). [Figure 16] This is an explanatory diagram showing an example of the robot's operation (at a predetermined angle of 90 degrees relative to the processing reference axis) when the workpiece rotation process (S301 to S307) shown in Figure 7(B) is performed, and is shown in chronological order (Figure 16(M) → Figure 16(N) → Figure 16(O) → Figure 16(P) → Figure 16(Q) → Figure 16(R)). [Figure 17] This is an explanatory diagram showing an example of the robot's operation (at a predetermined angle of 90 degrees relative to the processing reference axis) when the workpiece return process (S401 to S409) shown in Figure 7(C) is performed, and is shown in chronological order (Figure 17(S) → Figure 17(T) → Figure 17(U) → Figure 17(V) → Figure 17(W) → Figure 17(X)). DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, an embodiment of a robot control method and control program of the present invention will be described with reference to the drawings. First, an example configuration of a laser processing system 10 including a vertical articulated robot 30 (hereinafter referred to as "robot 30") controlled by applying the robot control method and control program of the present invention will be described with reference to Figs. 1 to 5. The laser processing system 10 of this embodiment is a system used in a laser processing process in which laser processing is performed in a metal processing factory, for example, and can be used when automating a series of processing steps.

[0028] Note that Fig. 1 shows an explanatory diagram illustrating an example of the configuration of one embodiment of laser processing system 10, and Fig. 2 shows a block diagram illustrating an example of a control system for laser processing system 10. Furthermore, Fig. 3(A) shows an explanatory diagram illustrating an example of the configuration of robot 30, and Fig. 3(B) shows an explanatory diagram that schematically illustrates the link structure of robot 30. Furthermore, Fig. 4 shows an explanatory diagram illustrating an example of the configuration of actuators that correspond to the hands of robot 30, and Fig. 5 shows an explanatory diagram illustrating an example of the configuration of pallet 73 and the like that constitute laser processing system 10.

[0029] In addition, in this specification, in the coordinate axis representations shown in Figures 1, 3, and 8 to 17, the tip direction of the X axis may be referred to as the "forward direction" or "forward," the base end direction of the X axis may be referred to as the "rear direction" or "rear," the tip direction of the Y axis may be referred to as the "left direction," the base end direction of the Y axis may be referred to as the "right direction," the tip direction of the Z axis may be referred to as the "upward direction" or "upward," and the base end direction of the Z axis may be referred to as the "downward direction" or "downward."

[0030] 1 and 2, the laser processing system 10 of this embodiment is capable of performing predetermined laser processing by irradiating a workpiece W held by a robot 30 with laser light in the laser processing step as described above, and is mainly composed of a controller 20, a laser sensor 25, a robot 30, a laser unit 50, and a pallet unit 70. In this embodiment, the laser sensor 25, the robot 30, the laser unit 50, and the pallet unit 70 are provided on a stand 11, and the controller 20 is housed within the stand 11. Therefore, it should be noted that the controller 20 is not shown in FIG. 1. The laser sensor 25 is also not shown in FIG. 1.

[0031] The workpiece W to be laser processed in the laser processing system 10 is a metal rod member having a long, thin rod shape, and one end Wx of the workpiece W has been coated with a solvent, chemical, or the like in advance in a previous process. If the robot 30 or the like touches the end Wx of the workpiece W coated with the solvent, the effect or function of the solvent may be impaired. Therefore, as will be described later, in the laser processing system 10, the workpiece Wa before processing, which has been coated with the solvent, is placed on the pallet 73 or the like of the pallet unit 70 so that the end Wx of the workpiece Wa faces upward.

[0032] The controller 20 is composed of a control unit 21 and an operation panel 23. The control unit 21 is a device that has the function of generating control information for the robot 30 and the laser oscillator 51 and galvanometer mirror 53 of the laser unit 50 based on operation information input from the operation panel 23 and outputting it to them, and receiving operation information sent from the laser oscillator 51 and galvanometer mirror 53 of the robot 30 and the laser unit 50, performing predetermined information processing on the information and outputting it to the operation panel 23. The controller 20 is typically an FA computer or an industrial computer, and is configured to be connectable to the robot 30, the laser oscillator 53 of the laser unit 50, etc. via a predetermined communication interface.

[0033] In this embodiment, the robot 30 is controlled, for example, by a robot computer housed in the body 32 of the robot 30. Specifically, this includes attitude control of the body 32, first arm 33, second arm 34, and wrist 37 that constitute the robot 30, and position control and opening / closing control of the actuator 40, which corresponds to a hand or end effector. Position information of each part of the robot 30, including the tip (claw portions 48, 49) of the actuator 40 that grips the workpiece W, is expressed in three-dimensional coordinates and managed by the controller 20. Therefore, coordinate information for the positions of the pallet 73 of the pallet unit 70, the positions of each workpiece W placed thereon, as well as a predetermined position, standby position P, and predetermined range (tip detection area), which will be described later, is stored in advance in the control unit 21 of the controller 20.

[0034] The operation panel 23 is typically a liquid crystal display with a touch panel whose surface is covered with a transparent touch panel, and has the function of sending information input by the operator via the touch panel to the control unit 21 and displaying information sent from the control unit 21 on the liquid crystal display. The operation panel 23 is configured to be connectable to the control unit 21 via, for example, a USB interface or a LAN interface. Note that a notebook or tablet computer having the functions of both the control unit 21 and the operation panel 23 may also be used as the controller 20.

[0035] The laser sensor 25 is configured to detect the presence of an object to be detected and the distance to the object, for example, by irradiating it with pulsed laser light for detection and detecting the light reflected back from the object, and is connected to the control unit 21. In this embodiment, as will be described later, the laser sensor 25 is used to detect the tip position of the workpiece Wa gripped by the actuator 40. For this reason, the laser sensor 25 is provided in a predetermined range (tip detection area) near the top of the pallet unit 70 on the stand 11.

[0036] The robot 30 is a vertical articulated industrial robot configured with six axes, a first axis J1 to a sixth axis J6, and is mainly configured with a base 31, a body 32, a first arm 33, a second arm 34, a wrist 37, an actuator 40, etc. In this embodiment, the base 31 of the robot 30 is fixed to a base plate 12 provided in the right region of the upper surface of a stand 11. The configuration of the robot 30 is shown in detail in Figures 3(A) and (B), and will be described below with reference to these figures.

[0037] 3(A), the base 31 of the robot 30 is fixed to the base plate 12, thereby allowing the robot 30 to be installed on the stand 11. The base end of the body 32 is supported by the base 31 so as to be rotatable about a first axis J1 perpendicular to the base plate 12, and the body 32 houses a robot computer (not shown) that can control and learn the operation of the robot 30. The tip (upper end) of the body 32 has an L-shape due to the first arm 33 being offset from the body 32.

[0038] The first arm 33 has a base end supported by the body 32 so as to be swingable about a second axis J2 perpendicular to the first axis J1. In this embodiment, the first arm 33 is disposed offset in the direction of the second axis J2 relative to the body 32, and therefore both the base end and the tip end have an L shape. In other words, the first arm 33 has the shape of "[" (square brackets).

[0039] The second arm 34 is composed of an angle portion 35 and a straight portion 36. The base end of the angle portion 35 of the second arm 34 is supported on the tip portion of the first arm 33 so as to be swingable about a third axis J3 parallel to the second axis J2, and the base end of the straight portion 36 is supported on the tip portion of the angle portion 35 so as to be rotatable about a fourth axis J4 perpendicular to the third axis J3. The angle portion 35 has an L-shape because the first arm 33 is disposed offset in the direction of the second axis J2 with respect to the body 32.

[0040] The wrist 37 is composed of an angle portion 38 and a straight portion 39. The angle portion 38 is disposed offset from the second arm 34, and its base end is supported by the tip of the straight portion 36 so as to be swingable about a fifth axis J5 perpendicular to the fourth axis J4. The straight portion 39, connected to the tip of the angle portion 38, is configured to support an actuator 40 so as to be rotatable about a sixth axis J6 perpendicular to the fifth axis J5. In other words, the base end of the straight portion 39 is supported by the tip of the angle portion 38 so as to be rotatable about the sixth axis J6, and the base end is configured so that the actuator 40 can be attached. The configuration of the actuator 40, which corresponds to the hand or end effector of the robot 30, will be described later with reference to FIG. 4.

[0041] Figure 3(B) schematically shows the link structure of the robot 30. In the robot 30 in a posture that can adopt the link structure shown in Figure 3(B), the first axis J1 can be conceptualized as a rotary joint that can rotate the body 32 relative to the base plate 12 within the XY plane, the second axis J2 can be conceptualized as a rotary joint that can rotate the first arm 33 within the YZ plane, the third axis J3 can be conceptualized as a rotary joint that can rotate the angle portion 35 of the second arm 34 within the YZ plane, the fourth axis J4 can be conceptualized as a rotary joint that can rotate the straight portion 36 of the second arm 34 about the Y axis, the fifth axis J5 can be conceptualized as a rotary joint that can rotate the angle portion 38 of the wrist 37 within the XY plane, and the sixth axis J6 can be conceptualized as a rotary joint that can rotate the straight portion 39 of the wrist 37 about the Y axis.

[0042] In the figure, the first axis J1 and the fourth axis J4 to the sixth axis J6 are represented by rotary joints with rectangular symbols that rotate around the Z axis or the Y axis, and the second axis J2 and the third axis J3 are represented by rotary joints with circular symbols that rotate around the X axis. However, when viewed from a position rotated 90 degrees around the Z axis, the second axis J2 and the third axis J3 are represented by rotary joints with rectangular symbols, and the fourth axis J4 and the sixth axis J6 are represented by rotary joints with circular symbols. In other words, the second axis J2 to the sixth axis J6 can be represented as rotary joints with either rectangular symbols or circular symbols because their positions can be rotated within a 360-degree range around the first axis J1.

[0043] The rotatable range of the first axis J1 to the sixth axis J6 is set to approximately -180 degrees to +180 degrees, or approximately 360 degrees, due to the specifications of the internal mechanisms that make up the body 32, first arm 33, second arm 34, and wrist 37. Therefore, in this embodiment, as will be described later, the movement of the actuator 40 can be controlled within the limited rotatable range by performing a fourth axis reverse rotation process in the workpiece release process (S103) and the workpiece return process (S111).

[0044] The actuator 40 corresponds to the hand or end effector of the robot 30, and in this embodiment is attached to the straight portion 39 of the wrist 37, which is rotatable about the sixth axis J6. The configuration of the actuator 40 is shown in detail in Figures 4(A) and (B), so from here on, the explanation will also refer to Figure 4.

[0045] 4(A), the actuator 40 is mainly composed of a connection part 41, a movable part 44, a drive mechanism part 45, support parts 46 and 47, and claw parts 48 and 49, and is connected to the straight part 39 of the wrist 37 via the connection part 41. This allows the actuator 40 to rotate about the sixth axis J6 of the robot 30. The drive mechanism part 43 is a mechanical unit that can slide the movable parts 44 and 45 so as to widen or narrow the gap distance α between the movable parts 44 and 45, and houses the drive mechanism inside.

[0046] The support portions 46, 47 are bracket members attached to the movable portions 44, 45. In this embodiment, the support portion 46 is fixed to the movable portion 44, and the support portion 47 is fixed to the movable portion 45. Claw portions 48, 49 are attached to these support portions 46, 47. The support portions 46, 47 and the claw portions 48, 49 have specifications that match the dimensions and shape of the workpiece W, which is a round bar member. Therefore, the shapes of the support portions 46, 47 and the claw portions 48, 49 shown in FIG. 4 are only examples, and they can be customized to various shapes and dimensions to suit the individual specific dimensions and shape of the workpiece W to be transported.

[0047] The claws 48, 49 are pinch members that can grip the workpiece W by pinching it from its radial direction, and are formed in an L-shape that protrudes forward, in the opposite direction to the connecting part 41, relative to the support parts 46, 47 to which they are attached. That is, the vertical line part of the L-shape is attached to the support parts 46, 47, and the workpiece W can be pinched at the tip of the horizontal line part of the L-shape.

[0048] In this embodiment, grooves 48a, 49a having semicircular radial cross sections are formed at the tips of the claws 48, 49, respectively, to facilitate gripping of the workpiece W, which is a round bar member, without slipping. One of the claws 49 also has a recess 49b formed at its tip. By forming such a recess 49b, two upper and lower protrusions are arranged facing each other across the groove within the recess. As a result, when the workpiece W is clamped between the claws 48, 49 from the radial direction, contact with the workpiece W can be achieved at three locations: one near the groove 48a of the claw 48 and two at the two protrusions near the groove 49a of the claw 49. In other words, when the workpiece W is clamped between the claws 48, 49, contact with the workpiece W can be achieved at these three locations. This allows for more stable gripping of the workpiece W than when such a recess 49b is not formed, which would result in contact at two locations.

[0049] As shown in FIG. 4(B), the actuator 40 configured in this manner moves the movable parts 44, 45 in a direction separating them (actuator 40'), widening the gap α' (>α (FIG. 4(A))) between them (open state). Conversely, moving the movable parts 44, 45 in a direction approaching them narrows the gap α (<α' (FIG. 4(B))) between them (closed state). This makes it possible for the claws 48, 49 to grip the workpiece W. Note that FIG. 4(B) shows how the middle part of the workpiece W can be gripped, avoiding the end part Wx on which a solvent or the like is applied.

[0050] The laser unit 50 is an industrial laser device capable of emitting laser light, and is mainly composed of a laser oscillator 51, a galvanometer mirror 53, a condenser lens 55, etc. In this embodiment, the laser oscillator 51 and the like of the laser unit 50 are fixed on an apparatus stand 14 provided in an area on the left side of the upper surface of the stand 11. The workpiece W is subjected to laser processing in a processing space on the stand 11, which is a space sandwiched between the robot 30 and the laser unit 50 and in which the actuator 40 attached to the robot 30 can be positioned.

[0051] The laser oscillator 51 is a laser light source device that generates laser light that can be irradiated onto the workpiece W, and the type, wavelength, and output of the laser light are selected appropriately depending on the application of the laser processing. In this embodiment, the laser light is irradiated to one end Wx of the workpiece W with a predetermined width. For this reason, the laser oscillator 51 is configured to be able to control the irradiation position of the laser light via the galvanometer mirror 53. The laser light emitted from the galvanometer mirror 53 is condensed and irradiated by the condenser lens 55 so that a focal point can be formed at a predetermined position within the processing space.

[0052] 1 is a reference line used to determine the machining position and a predetermined position to be machined on the workpiece W, and in this embodiment, coincides with the optical axis of the laser light. Such machining reference axis K is a virtual line, and is actually given to the robot 30 from the controller 20 as coordinate information within the machining space.

[0053] Pallet unit 70 is capable of placing unmachined workpieces Wa and machined workpieces Wb upright on stand 11, and is composed of set plate 71 and pallets 73 to 75. Set plate 71 is a metal plate that enables three pallets 73 to 75 to be attached to predetermined attachment positions, and is fixed to stand 11. Positioning pins (not shown) are provided on set plate 71, which determine the installation positions of pallets 73 to 75.

[0054] The configuration of the pallets 73 to 75 is shown in detail in FIG. 5, and from here on, the description will also refer to this figure. Note that FIG. 5 shows pallet 73 as a representative of the three pallets 73 to 75, but pallets 74 and 75 are configured similarly to pallet 73. Therefore, a description of pallets 74 and 75 will be omitted. In FIG. 5, the state in which an unmachined workpiece Wa is placed on pallet 73 with one end Wx thereof facing upward is shown by a two-dot chain line. Therefore, as will be described later, the robot 30 is controlled so that the claws 48 and 49 of the actuator 40 grip the middle portion of the workpiece Wa, avoiding the one end Wx to which a solvent or the like has been applied.

[0055] The pallet 73 is a thick metal plate with a thickness that allows the workpieces W to stand on their own, and has a predetermined number of mounting holes 73a formed therein so that a predetermined number of workpieces W can be placed on it. In the example of FIG. 5, 40 workpieces W can be placed on it. The width and depth dimensions of the pallet 73 are predetermined, so the number of workpieces W that can be placed on it is determined based on the shaft diameter of the workpieces W. In other words, the smaller the shaft diameter, the more workpieces W can be placed on it, and the larger the shaft diameter, the fewer workpieces can be placed on it. A positioning groove 73b is formed on a predetermined side of the pallet 73. The aforementioned positioning pin engages with this positioning groove 73b, thereby determining the mounting position of the pallet 73 on the set plate 71.

[0056] In the laser processing system 10 configured as above, the controller 20 executes a laser processing control process, which will be described next with reference to Figures 6 and 7, whereby one end Wx of the workpiece W (workpiece Wa) held by the robot 30 is irradiated with laser light to perform laser processing. This laser processing control process is performed by the MPU or GPU of the controller 20 executing a computer program (control program) capable of processing information by the controller 20. This control program is stored in the HDD or SSD of the controller 20.

[0057] Note that Fig. 6 shows a flowchart illustrating an example of the flow of laser processing control processing in the laser processing system 10. Fig. 7 shows a flowchart illustrating the processing flow of each subroutine (S103, S107, S111) constituting the laser processing control processing of Fig. 6, in which Fig. 7(A) shows the workpiece ejection processing, Fig. 7(B) shows the workpiece rotation processing, and Fig. 7(C) shows the workpiece return processing.

[0058] As shown in FIG. 6, the laser processing control process begins with a predetermined initialization process in step S101. This process, for example, clears the work area in the storage space set in the memory device of the controller 20 and sets flags and the like to their initial values. The controller 20 also sends control commands to the robot 30, laser oscillator 51, and galvanometer mirror 53 connected to the controller 20 to set them to their initial states. As a result, for example, the robot 30 moves the actuator 40 to a predetermined standby position P (described later) and waits there. Furthermore, as described later, predetermined processing flags are associated with the multiple workpieces Wa placed on the pallet 73 before machining. Therefore, these processing flags are set to "0," which indicates the workpieces are not yet machined, as their initial values.

[0059] In the next step S103, a workpiece removal process is performed. The details of this process are shown in Figure 7(A), so from here on, we will also refer to this figure. In addition, Figures 8 and 9 are explanatory diagrams showing an example of the operation of the robot 30 when this process is performed, so we will also refer to these figures for our explanation.

[0060] 7(A), in the workpiece removal process, a workpiece information acquisition process is performed in step S201. In this process, information about the unmachined workpiece Wa to be removed from the pallet 73 is read and acquired from, for example, a collection of workpiece information sent in advance from the operation panel 23 and stored in a memory device.

[0061] The work information includes, for example, the total number of unprocessed workpieces Wa placed on the pallet 73, and for individual workpieces W whether they have been processed or not, the lot number, the current placement position (coordinate information) of the pallet 73 before processing, the planned placement position (coordinate information) of the pallet 74 after processing, the shaft length dimension, the shaft diameter dimension, the type of solvent, etc., the application range of the solvent, etc. (application width dimension), the application thickness, etc.

[0062] Based on the workpiece information acquired in step S201, for example, information on the target position to which the actuator 40 is to be moved in order to remove the workpiece Wa from the pre-machining pallet 73, and information on the target position to which the actuator 40 is to be moved in order to return the workpiece Wb to the post-machining pallet 74, are obtained as three-dimensional coordinate information.In addition, information such as the output (W), irradiation time (seconds), and pulse duty ratio (%) of the laser light generated by the laser oscillator 51, and information on the irradiation width (mm) of the laser light controlled by the galvanometer mirror 53 are also obtained.

[0063] In the next step S203, a pallet approach process is performed. In this process, the claws 48, 49 of the actuator 40 are moved from the standby position P to the target position based on the target position information obtained in step S201 (see FIGS. 8A and 8B). During or before this movement, the claws 48, 49 of the actuator 40 are spread wider than the axial diameter of the workpiece Wa (open state). Then, the claws 48, 49 are moved closer to the middle portion of the unmachined workpiece Wa placed on the pallet 73 so that the workpiece axis Jw is perpendicular to the sixth axis J6 of the actuator 40. The middle portion refers to the area excluding one end Wx of the workpiece Wa and the other end on the opposite side, and is calculated based on the axial length of the workpiece Wa. Note that the white circles shown in FIGS. 8A to 8F and 9G to 9L indicate the standby position P of the actuator 40. 8(B) to 8(F) and 9(G) to 9(L) indicate the movement trajectories of the claws 48, 49 caused by the movement of the actuator 40. The same applies to FIGS. 10 to 17.

[0064] In the next step S205, a workpiece gripping process is performed. In this process, when it is determined in step S203 based on coordinate information and the like that the workpiece Wa has been approached and positioned between the claws 48, 49 of the actuator 40, the actuator 40 is controlled to close the claws 48, 49. As a result, the central portion of the workpiece Wa is gripped by the claws 48, 49 (FIG. 8(C)), and the actuator 40 is moved upward in the workpiece removal process of the following step S207, whereby the workpiece Wa is lifted upward (see FIG. 8(D)). As a result, the workpiece Wa is removed from the pallet 73.

[0065] When the workpiece Wa is removed from the pallet 73, a tip position detection process is performed in step S209. The workpiece Wa gripped by the actuator 40 in the workpiece gripping process (S205) described above is not necessarily gripped at a constant position by the claws 48, 49. Therefore, an error may occur in the length of the gripped workpiece Wa from the gripping position to the tip (tip of one end Wx). On the other hand, since the laser light is irradiated at a nearly pinpoint (focal point) at a predetermined position set in advance in the machining space, it is necessary to align the focal point with the position of one end Wx of the workpiece Wa transported to the predetermined position.

[0066] Therefore, in this embodiment, before the workpiece Wa is transported to a predetermined position in the machining space, the length from the gripping position of the workpiece Wa gripped by the actuator 40 to the tip of one end Wx is detected in a tip position detection process in step S209, thereby making it possible to position the workpiece Wa held at a predetermined position during laser machining with high accuracy, as will be described later. The length from the gripping position of the workpiece Wa to the tip of one end Wx is found, for example, using the laser sensor 25 described above.

[0067] That is, the workpiece Wa held by the actuator 40 is moved to a detectable position (tip detection area) of the laser sensor 25, and the tip of the one end Wx is detected by the laser sensor 25. Then, detection coordinate data at the detection position of the tip and control coordinate data at the gripping position of the workpiece Wa (tip position of the claws 48, 49) at the detection timing are acquired. This makes it possible to calculate the length from the gripping position of the workpiece Wa to the tip of the one end Wx based on both three-dimensional coordinate data. In other words, the tip position of the one end Wx of the workpiece Wa held by the actuator 40 can be accurately obtained, and the position of the one end Wx of the workpiece Wa held at a predetermined position by the actuator 40 can be positioned with high precision.

[0068] In the next step S211, a workpiece transfer process is performed. In this process, the workpiece Wa removed in step S207 is transferred to a standby position P of the actuator 40 before being transferred to a predetermined position set in advance in the machining space (see FIGS. 8(E) and (F)). Note that transfer to the predetermined position in the machining space is performed in the fourth axis reverse rotation process in the next step S213.

[0069] As described above, the second arm 34 constituting the robot 30 has a rotatable range of the straight portion 36 about the fourth axis J4 set to approximately -180 degrees to +180 degrees, i.e., approximately 360 degrees. Therefore, in the fourth-axis reverse rotation process in step S213, the straight portion 36 of the second arm 34 is first rotated in a predetermined direction Rn (see FIGS. 9(G) and (H)), and then rotated in the opposite direction Rr to approximately -180 degrees (0 degrees) (see FIGS. 9(I) to (K)), while moving the workpiece Wa to a predetermined position set in advance within the machining space (see FIG. 9(L)). At this time, the sixth axis J6 is also rotated at approximately the same time, so that one end Wx of the workpiece Wa faces the laser unit 50, i.e., faces leftward, and the orientation of the workpiece Wa is turned sideways. This makes it possible to rotate the straight portion 36 up to approximately +180 degrees (360 degrees) in the predetermined direction Rn by the workpiece rotation process (S107) described later.

[0070] During the same period as the movement of the workpiece Wa, the straight portion 39 of the wrist 37 is also rotated to position the workpiece Wa so that it is coaxial with the machining reference axis K at a predetermined position, i.e., so that the predetermined angle is 0 degrees. Furthermore, based on the length from the gripping position of the workpiece Wa to the tip of one end Wx, the tip of one end Wx is positioned so that it can be present in the focus of the laser light.

[0071] The "predetermined position" refers to a position where one end Wx of the workpiece Wa is positioned at a predetermined angle with respect to the machining reference axis K, and where the one end Wx can be irradiated with laser light. The "predetermined angle" refers to the angle of the workpiece axis Jw of the workpiece Wa with respect to the machining reference axis K at the predetermined position; when the workpiece axis Jw is positioned coaxially with the machining reference axis K at the predetermined position, the predetermined angle is 0 degrees (predetermined angle 0 degrees), and when the workpiece axis Jw is positioned perpendicular to the machining reference axis K, the predetermined angle is 90 degrees (predetermined angle 90 degrees).

[0072] After the workpiece removal process (FIG. 6; S103) shown in FIG. 7(A) is completed, the process returns to the control process of FIG. 6, and the processing start process is performed in the next step S105. In this embodiment, this process starts the irradiation of laser light. That is, the controller 20 sends information about the laser light output source (laser light output (W), irradiation time (seconds), pulse duty ratio (%), etc.) determined based on information acquired in the workpiece information acquisition process (S201), such as the type of solvent, the application range (application width dimension), and the application thickness of the solvent, to the laser oscillator 51, and also sends information about the laser light irradiation width (mm) to the galvanometer mirror 53. As a result, the laser oscillator 51 and the galvanometer mirror 53 start irradiating the workpiece Wa, which is held by the actuator 40 and held at a predetermined position, with laser light suitable for laser processing of the workpiece Wa.

[0073] When irradiation of the laser beam begins, in this embodiment, since it is necessary to perform laser processing on the entire circumference of one end Wx of the workpiece Wa, the workpiece Wa is rotated in a predetermined direction Rn about its workpiece axis Jw. Therefore, the workpiece rotation process is performed in the following step S107. Details of this process are shown in FIG. 7(B), and from here on, this figure will also be referred to. Also, FIG. 10 shows an explanatory diagram showing an example of the operation of the robot 30 when this process is performed, and this will also be referred to in the description. Note that in this embodiment, the processing start process (S105) is performed before the workpiece rotation process in step S107, but the processing start process (S105) may also be performed during the workpiece rotation process.

[0074] As shown in Figure 7(B), the workpiece rotation process begins with step S301, where a sixth-axis rotation prohibition process is performed. This process prohibits the straight portion 39 of the wrist 37 from rotating about the sixth axis J6, thereby preventing the actuator 40 from turning. In other words, the straight portion 39 of the wrist 37 and the actuator 40 are integrated, and in the subsequent rotation process of steps S303 to S309, the angle portion 38, straight portion 39, and actuator 40 are controlled so that they behave like a single continuous rod.

[0075] In the following steps S303 to S307, a fourth axis forward rotation process is performed. In these processes, the workpiece Wa, which is gripped by the actuator 40 and held at a predetermined position, is rotated about the workpiece axis Jw. The workpiece Wa is rotated about the workpiece axis Jw on the machining reference axis K, as if the workpiece Wa were fixed in place while being held at a predetermined position. Therefore, in this embodiment, the second arm 34, the first arm 33, and the body 32 are controlled so that the actuator 40 gripping the workpiece Wa at a predetermined position does not rotate about the sixth axis J6, but rather the wrist 37, i.e., the single rod-like wrist 37 (angle portion 38, straight portion 39) and the actuator 40, can rotate about the workpiece axis Jw together (see FIGS. 10(M) to 10(R)).

[0076] In this embodiment, the wrist 37 and actuator 40 are rotated clockwise as viewed from the laser unit 50 (the tip of the Y-axis) that emits the laser light. Note that in Figures 10(M) to 10(R), the trajectory (circle Cr) drawn by the base end of the angle portion 38 of the wrist 37 due to this rotation is shown by a two-dot chain line. Note that, when the predetermined angle is 0 degrees, the machining reference axis K and the workpiece axis Jw are coaxial (on the same line), so the workpiece axis Jw is not shown in these figures. Also, although the laser unit 50 is not shown in these figures, it is located outside the figures to the left along the machining reference axis K.

[0077] The wrist 37 and the actuator 40 are rotated in this manner so as to complete one rotation (360 degrees), and the start and end coordinates of the rotation in the rotation control are the same. Therefore, in this embodiment, 360 degrees (-180 degrees to +180 degrees) is divided into three, and the rotation control process is performed every 120 degrees in three steps (S303, S305, S307).

[0078] That is, step S303 rotates from -180 degrees to -60 degrees, step S305 rotates from -60 degrees to +60 degrees, and step S307 rotates from +60 degrees to +180 degrees. The number of divisions can be four or five as long as it is three or more, but the control processing time may increase as the number of divisions increases. Note that a two-division method cannot be adopted because it is not possible to determine whether the rotation direction is clockwise (-180 degrees → 0 degrees → +180 degrees) or counterclockwise (+180 degrees → 0 degrees → -180 degrees).

[0079] When the fourth axis forward rotation process (steps S303 to S307) is completed, the sixth axis rotation permission process is performed in step S309. This process permits the rotation of the straight portion 39 about the sixth axis J6, which was prohibited in step S301, thereby enabling the actuator 40 to rotate.

[0080] In this embodiment, the fourth axis forward rotation process in steps S303 to S307 rotates the actuator 40 and wrist 37 together so that the workpiece Wa gripped by the actuator 40 at a predetermined position rotates about the workpiece axis Jw, and the angle portion 38 and straight portion 39 of the wrist 37 and the actuator 40 behave like a single continuous rod and rotate in the same plane to describe a circle Cr about the workpiece axis Jw, but this does not necessarily have to be a circle Cr. In other words, the wrist 37 and actuator 40 may rotate within a predetermined angle range about the workpiece axis Jw like a single rod, describing an arc about the workpiece axis Jw.

[0081] That is, in the workpiece rotation process shown in FIG. 7(B), for example, the fourth-axis forward rotation process in steps S303 and S307 may be deleted, and the algorithm may be modified to execute the control process in the following order: sixth-axis rotation prohibition process (S301), fourth-axis forward rotation process (S305), and sixth-axis rotation permission process (S309). In this modified workpiece rotation process, the wrist 37 and actuator 40 rotate from -60° to +60° around the workpiece axis Jw, enabling them to rotate within the same plane to describe an arc with a central angle of 120°. Furthermore, since the start and end coordinates of an arc are not the same, unlike the case of a circle, the rotation process does not need to be divided into three steps. The central angle δ of such an arc can be set within the range of 0°<δ<360° and is individually and specifically determined based on the length (angle) of the circumferential range to be rotated on the workpiece W.

[0082] When the workpiece rotation process (FIG. 6; S107) shown in FIG. 7(B) is completed, the process returns to the control process of FIG. 6, and the processing stop process is performed in the next step S109. In this embodiment, this process stops the irradiation of the laser light. That is, since the laser unit 50 continued to irradiate the laser light while the workpiece Wa was rotating 360 degrees around the workpiece axis Jw in the workpiece rotation process (S107), the laser processing of the one end Wx of the workpiece Wa is completed. Therefore, since there is no need to irradiate the laser light thereafter, the irradiation is stopped.

[0083] When laser processing is completed and the irradiation of the laser light is stopped, the processed workpiece Wb must be returned to the pallet 74 for processed workpieces, so the workpiece Wb held by the actuator 40 is transported to the pallet 74. For this reason, the workpiece return process is performed in the following step S111. The details of this process are shown in FIG. 7(C), and from here on, this figure will also be referred to. Also, FIG. 11 shows an explanatory diagram showing an example of the operation of the robot 30 when this process is performed, and this will also be referred to in the description. Note that in this embodiment, the processing stop process (S109) is performed after the workpiece rotation process in step S107, but the processing stop process (S109) may also be performed during the workpiece rotation process.

[0084] As shown in FIG. 7(C), in the workpiece return process, first, a fourth-axis reverse rotation process is performed in step S401. When the workpiece rotation process (S107) is completed, the robot 30 returns to the orientation it had when rotation began (see FIGS. 10(M) and 10(R)). However, the straight section 36 of the second arm 34 is likely to have rotated in the predetermined direction Rn about the fourth axis J4 and stopped near the maximum angle within the rotational range of the forward rotation (approximately +180 degrees (360 degrees)). Therefore, in this process, while rotating the straight section 36 in the opposite direction Rr (reverse rotation) (see FIGS. 11(S) to 11(U)), the workpiece Wb is moved to the standby position P of the actuator 40 by the workpiece transfer process in step S403 (see FIG. 11(V)). At this time, the sixth axis J6 is also rotated at approximately the same time, so that one end Wx of the workpiece Wb is upward, and the orientation of the workpiece Wb is vertical. This makes it possible to return the workpiece Wb to the pallet 74 by the workpiece return process in the next step S405 without being affected by the limitations on the rotational range.

[0085] In the workpiece returning process of step S405, the actuator 40 is moved to the pallet 74 in order to return the workpiece Wb from the standby position P of the actuator 40 to the pallet 74. Information on the target position to which the actuator 40 is to be moved (position coordinates in the XY plane, position coordinates in the Z-axis direction) is obtained based on the workpiece information acquired in the workpiece information acquisition process (S201) described above. As a result, the actuator 40, having gripped the workpiece Wb, moves from the standby position P to the pallet 74 with the workpiece Wb standing upright (see FIG. 11(V)). Then, the actuator 40 approaches the pallet 74 and arrives at the intended placement position of the workpiece Wb (see FIG. 11(W)).

[0086] In the next step S407, a workpiece release process is performed. This process is performed when it is determined based on coordinate information, etc. that the actuator 40 has reached the intended placement position of the workpiece Wb, and the actuator 40 controls the claws 48, 49 to open. This releases the workpiece Wb that had been gripped by the claws 48, 49, and the workpiece Wb is inserted and placed upright in the placement hole 73a of the pallet 74. Thereafter, a pallet separation process is performed in step S409, and the actuator 40 moves away from the pallet 74 and then returns to the standby position P (see FIG. 11(X)).

[0087] As a result, since the workpiece Wb placed on the pallet 74 has already been processed, the information of that workpiece W is updated. This process is performed by the workpiece information update process in step S411. In this embodiment, for example, a predetermined processing flag associated with each workpiece W is stored in the control unit 21 of the controller 20, so the initial value of "0" before processing is updated to "1" after processing. As a result, it is known from the management data, etc. that laser processing of that workpiece W by the laser processing system 10 has been completed.

[0088] When the workpiece return process (FIG. 6; S111) shown in FIG. 7(C) is completed, the process returns to the control process of FIG. 6, and the process of determining whether or not there is an unmachined workpiece is performed in the next step S113. This process is performed, for example, based on the machining flag stored in the control unit 21. As described above, a machining flag set to "0" is associated with the workpiece Wa before machining. Therefore, a machining flag set to "0" is searched for, and if it is found to exist, an unmachined workpiece is "present" (S113; Yes), so the process proceeds to step S103 and the workpiece removal process is performed again. On the other hand, if it does not exist, an unmachined workpiece is not "present" ("not present") (S113; No), so this series of laser machining control processes is terminated (END).

[0089] Here, an example will be described in which the predetermined angle of the workpiece Wa relative to the machining reference axis K is not 0 degrees (predetermined angle 0 degrees). For example, if the predetermined angle is 45 degrees (predetermined angle 45 degrees), the robot 30' operates as shown in Figure 12 in the fourth axis reverse rotation process (S213) of the workpiece unloading process (S103), operates as shown in Figure 13 in the workpiece rotation process (S107), and further operates as shown in Figure 14 in the workpiece returning process (S111). In these Figures 12 to 14, the robot is represented by "30'", the predetermined angle is represented by "θ", and the workpiece axis is represented by "Jw".

[0090] Furthermore, for example, when the predetermined angle of the workpiece Wa relative to the machining reference axis K is 90 degrees (predetermined angle 90 degrees), the robot 30" operates as shown in Figure 15 in the fourth axis reverse rotation process (S213) of the workpiece removal process (S103), operates as shown in Figure 16 in the workpiece rotation process (S107), and further operates as shown in Figure 17 in the workpiece return process (S111). In these Figures 15 to 17, the robot is represented by "30", the predetermined angle is represented by "θ", and the workpiece axis is represented by "Jw".

[0091] In addition, when the specified angle is 45 degrees and 90 degrees, in the pallet approach process (S203), workpiece gripping process (S205), workpiece removal process (S207), tip position detection process (S209), and workpiece transport process (S211) of the workpiece removal process (S103), the robot 30 operates as shown in Figure 8, in the same way as when the specified angle is 0 degrees.

[0092] 9 to 17, comparing the cases where the predetermined angle is 0 degrees, 45 degrees, and 90 degrees, it can be seen that although the individual movements of the body 32, first arm 33, second arm 34, and wrist 37 differ in terms of the details of the operations, the basic operations of robots 30′, 30″ are the same as the basic operations of robot 30 when the predetermined angle is 0 degrees. Therefore, it can be seen that the control processes described with reference to FIGS. 6 and 7 can be applied as they are when the predetermined angle is 45 degrees or 90 degrees.

[0093] As described above, the control method for the robot 30 included in the laser processing system 10 of this embodiment includes a workpiece placement process (S103), a workpiece rotation process (S107), and a workpiece return process (S111). The control program for the robot 30 causes the controller 20 that controls the robot 30 to execute this control method. In other words, the control program is executed by the controller 20 that controls the robot 30, and includes the workpiece placement process (S103), the workpiece rotation process (S107), and the workpiece return process (S111).

[0094] The robot 30 includes at least a base 31 mounted on the base plate 12, a body 32 supported by the base 31 so as to be rotatable about a first axis J1 perpendicular to the base plate 12, a first arm 33 supported at its base end by the body 32 so as to be swingable about a second axis J2 perpendicular to the first axis J1, a second arm 34 having an angle portion 35 supported at the tip end of the first arm 33 so as to be swingable about a third axis J3 parallel to the second axis J2 and having a straight portion 36 which is rotatable about a fourth axis J4 perpendicular to the third axis J3, a wrist 37 which is offset from the second arm 34 and has an angle portion 38 supported by the second arm 34 so as to be swingable about a fifth axis J5 perpendicular to the fourth axis J4, and an actuator 40 provided on the straight portion 39 of the wrist 37 so as to be rotatable about a sixth axis J6 perpendicular to the fifth axis J5.

[0095] (1) In the workpiece removal process (S103), the actuator 40 (claws 48, 49) grips the middle portion of the unmachined workpiece Wa placed on the pallet 73 so that the workpiece axis Jw and the sixth axis J6 about which the actuator 40 can rotate are perpendicular to each other, and then the workpiece Wa is moved into the machining space and positioned at a predetermined position within the machining space. In other words, the actuator 40 approaches the unmachined workpiece Wa from its radial direction, grips the middle portion of the workpiece Wa, and moves it to a predetermined position within the machining space. (2) In the workpiece rotation process (S107), the wrist 37, second arm 34, first arm 33, and body 32 are controlled so that the actuator 40, which has gripped the workpiece Wa positioned at the predetermined position, rotates around the workpiece axis Jw together with the wrist 37 without rotating about the sixth axis J6. That is, the wrist 37 is swung about the fifth axis J5, the second arm 34 is rotated in the predetermined direction Rn about the fourth axis J4 and swung about the third axis J3, the first arm 33 is swung about the second axis J2, and the body 32 is rotated about the first axis J1, so that the actuator 40 and the wrist 37 (the angle portion 38 and the straight portion 39) are rotated together so that the workpiece Wa gripped by the actuator 40 (the claw portions 48, 49) rotates about the workpiece axis Jw at a predetermined position. In other words, the actuator 40 and the wrist 37 (the angle portion 38 and the straight portion 39) are rotated in the same plane so that the angle portion 38 of the wrist 37 draws a circle or an arc about the workpiece axis Jw. This provides a period during which the workpiece Wa rotating about the workpiece axis Jw at a predetermined position can be machined. (3) In the workpiece returning process (S111), the machined workpiece Wb that has been machined within the period provided in the workpiece rotating process (S107) is moved and placed on another pallet 74. The machined workpiece Wb may also be moved and placed on the pallet 73 on which the unmachined workpiece Wa is placed.

[0096] It should be noted that the workpiece return process (S111) in (3) above is not necessarily required. For example, in the flowchart shown in Fig. 6, after the machining stop process (S109), if the machined workpiece Wb is handed over directly to a robot in another process without using a pallet 74 or the like, the workpiece return process (S111) is not required. In this case, the workpiece return process (S111) in Fig. 6 can be replaced with, for example, a "workpiece transfer process" that hands over the workpiece Wb to a robot in another process.

[0097] As a result, even if, for example, one end Wx of the workpiece Wa cannot be grasped by the actuator 40 (the claws 48, 49), in the workpiece release process (S103), the actuator 40 (the claws 48, 49) can grasp the middle portion of the workpiece Wa before machining, thereby making it possible to move the workpiece Wa to a predetermined position within the machining space. Then, in the workpiece rotation process (S107), the actuator 40 and the wrist 37 (the angle portion 38 and the straight portion 39) are rotated in the same plane so that the angle portion 38 of the wrist 37 describes a circle or an arc around the workpiece axis Jw, making it possible to rotate the workpiece Wa around the workpiece axis Jw. In other words, the workpiece Wa, whose middle portion is grasped by the actuator 40, rotates around the workpiece axis Jw in that state, and predetermined machining is possible while the workpiece Wa is rotating.

[0098] Therefore, as explained in the section "Problems to be Solved by the Invention," for example, after the workpiece Wa is placed on the relay table, there is no need to re-grapple the other end of the workpiece Wa opposite to the one end Wx from the axial direction, so there is no time required to place the workpiece Wa on the relay table and to re-grapple it. Furthermore, there is no need to control the actuator 40, wrist 37, second arm 34, first arm 33, or body 32, which are required to re-grapple the other end of the workpiece Wa from the axial direction after it has been placed on the relay table, so control of the robot 30 is unlikely to become complicated. Therefore, the time required to transport the workpiece Wa by the actuator 40 is unlikely to be long, which makes it possible to suppress a decrease in processing efficiency per unit time in a production line, processing system, etc.

[0099] Furthermore, in the control method for the robot 30 included in the laser processing system 10 described above, during the workpiece loading process (S103), the straight portion 36 of the second arm 34 rotates about the fourth axis J4 in the opposite direction Rr to the predetermined direction Rn, from the time the workpiece Wa is gripped by the actuator 40 (the claws 48, 49 thereof) until the workpiece Wa is moved to a predetermined position. As a result, prior to the rotation of the straight portion 36 of the second arm 34 in the predetermined direction Rn by the workpiece rotation process (S107), the straight portion 36 of the second arm 34 rotates in the opposite direction Rr. Therefore, even if a limit is set on the rotatable range of the straight portion 36 of the second arm 34 about the fourth axis J4, the rotation range in the predetermined direction Rn in the workpiece rotation process (S107) can be expanded by the rotation angle of the straight portion 36 of the second arm 34 rotated in the opposite direction Rr by the workpiece loading process (S103).

[0100] For example, if the rotation range of the fourth axis J4 in the straight portion 36 of the second arm 34 is -180 degrees to +180 degrees (360 degrees), the workpiece removal process (S103) rotates the second arm 34 in the opposite direction Rr to -180 degrees (0 degrees), and the workpiece rotation process (S107) makes it possible to rotate the second arm 34 in the specified direction Rn to +180 degrees (360 degrees).

[0101] Furthermore, in the control method for the robot 30 included in the above-described laser processing system 10, in the workpiece return process (S111), the second arm 34 rotates about the fourth axis J4 in the opposite direction Rr to the predetermined direction Rn during the period from when the workpiece Wa is gripped by the actuator 40 (the claws 48, 49) until when the workpiece Wa is moved to another pallet 74 or the like. As a result, after the straight portion 36 of the second arm 34 has rotated in the predetermined direction Rn by the workpiece rotation process (S107), the straight portion 36 of the second arm 34 is rotated in the opposite direction Rr to the predetermined direction Rn by the workpiece return process (S111), making it possible to move the workpiece Wb gripped by the actuator 40 (the claws 48, 49) to another pallet 74 or the like. Therefore, if there is a limit to the rotation range of the straight portion 36 of the second arm 34 on the fourth axis J4, after the straight portion 36 of the second arm 34 has rotated in the predetermined direction Rn in the work rotation process (S107), instead of rotating in the same predetermined direction Rn, the straight portion 36 of the second arm 34 is rotated in the opposite direction Rr, so that the work Wb grasped by the actuator 40 (claw portions 48, 49) can be moved with ease to another pallet 74, etc.

[0102] For example, if the rotatable range of the straight portion 36 of the second arm 34 on the fourth axis J4 is −180 degrees to +180 degrees (360 degrees), after the straight portion 36 of the second arm 34 is rotated in the predetermined direction Rn to +180 degrees (360 degrees) by the workpiece rotation process (S107), the straight portion 36 of the second arm 34 cannot be rotated in the same predetermined direction Rn by the workpiece return process (S111). Therefore, by rotating the straight portion 36 of the second arm 34 in the opposite direction Rr by the workpiece return process (S111), it becomes possible to move the workpiece Wb gripped by the actuator 40 (the claws 48, 49) to another pallet 74, etc.

[0103] Furthermore, in the control method for the robot 30 included in the laser processing system 10 described above, the predetermined position is determined within the processing space within a range from a predetermined angle of 0 degrees, which is coaxial with a predetermined processing reference axis K, to a predetermined angle of 90 degrees, which is perpendicular to the processing reference axis K. This makes it possible to set the predetermined position of the workpiece Wa, which is moved and positioned by the workpiece release process (S103), within the range from the predetermined angle of 0 degrees to the predetermined angle of 90 degrees with respect to the processing reference axis K. Therefore, the predetermined processing can be performed on the workpiece Wa at an angle within this range during the period provided by the workpiece rotation process (S107).

[0104] In the above-described embodiment, the robot 30 included in the laser processing system 10 has been described as having a configuration in which both ends of the first arm 33 (second arm) are bent at approximately right angles into a U-shape and are offset in the axial directions of the second axis J2 and the third axis J3 at these ends. However, as long as the robot has the second arm 34 (second arm) and wrist 37 (wrist) described above, it is not limited to the first arm 33 having both ends offset in this manner, and may be a robot having a first arm having a typical configuration as the first arm (for example, the "second arm 2" disclosed in Japanese Patent No. 7185065 or the "arm 5" disclosed in Japanese Patent Laid-Open No. 2019-84657, etc.).

[0105] Furthermore, in the above-described embodiment, the robot 30 included in the laser processing system 10 has been described as a six-axis vertical articulated robot, but as long as the robot has the second arm 34 (second arm portion) and wrist 37 (wrist portion) described above, it may also be, for example, a seven-axis vertical articulated robot such as that disclosed in the above-mentioned Patent Document 1 (JP 2012-139762 A).

[0106] Furthermore, in the above-described embodiment, the workpiece W grasped and transported by the robot 30 of the laser processing system 10 has one end coated with a solvent, chemical, or the like, but if it is desired to avoid grasping one end of the workpiece W by the actuator 40 of the robot 30, the workpiece W does not need to be coated with such a solvent. Furthermore, the above-described control method and control program for the robot 30 can also be applied to processing systems in which the actuator 40 of the robot 30 must grasp the middle part of the workpiece W for convenience of approaching the workpiece W or other reasons, and the workpiece W needs to be rotated about the workpiece axis Jw in the processing step.

[0107] In the above-described embodiment, the workpiece W grasped and transported by the robot 30 of the laser processing system 10 has an elongated rod shape. However, the workpiece is not limited to this, and the shape and size of the workpiece are arbitrary. That is, the shape and size of the workpiece are arbitrary as long as it is a workpiece that can be grasped by the actuator 40 of the robot 30 or the like but has a portion that should not be grasped, and the workpiece needs to be rotated around a predetermined axis during the processing process. Furthermore, the above-described control method and control program for the robot 30 can also be applied to processing systems, etc., in which the actuator 40 of the robot 30 or the like must grasp a predetermined portion of a workpiece of arbitrary shape and size due to convenience in approaching the workpiece or other circumstances, and the workpiece needs to be rotated around a predetermined axis during the processing process.

[0108] Furthermore, in the above-described embodiment, the workpiece Wa gripped by the robot 30 of the laser processing system 10 is controlled to rotate in a predetermined direction Rn (forward rotation) by the workpiece rotation process (S107), but the workpiece Wa may also be controlled to rotate in the opposite direction Rr (reverse rotation) by the workpiece rotation process (S107). In this case, the fourth-axis reverse rotation process (S213) in the workpiece unloading process (S103) of Fig. 7(A) must be replaced with a fourth-axis forward rotation process that rotates the straight portion 36 of the second arm 34 in the predetermined direction Rn about the fourth axis J4, and the fourth-axis reverse rotation process (S401) in the workpiece returning process (S111) of Fig. 7(C) must also be replaced with a fourth-axis forward rotation process that rotates the straight portion 36 of the second arm 34 in the predetermined direction Rn about the fourth axis J4.

[0109] Furthermore, in the above-described embodiment, an example has been given of using a laser sensor 25 as a sensor (detection unit) that detects the tip position of one end Wx of the workpiece Wa in the laser processing system 10, but the system may be configured using a sensor that can detect using a method other than the laser method (for example, a sensor that uses infrared reflection, ultrasonic reflection, image information, etc.) as long as it is a sensor that can detect the tip position of one end Wx of the workpiece Wa non-contactly in a predetermined range (tip detection area) near the top of the pallet unit 70 or in the processing space on the stand 11.

[0110] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications or variations of the above-described specific examples. Furthermore, the technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of these objectives alone has technical utility. Note that the description in parentheses in the [Explanation of Symbols] column may clearly indicate the correspondence between the terms used in the above-described embodiments and the terms described in the claims. [Explanation of symbols]

[0111] 10...Laser processing system 11... Mounting stand 12...Base plate (installation surface) 20...Controller 21...Control unit 23...Operation panel 25...Laser sensor 30, 30', 30"...Robot (vertical articulated robot) 31...Base (base) 32...Body (torso) 33...First arm (first arm part) 34...Second arm (second arm part) 35...Angle section (second arm, base end side) 36...Straight section (second arm, tip side) 37...Wrist (wrist area) 38...Angle part (wrist part, base end side) 39...Straight section (wrist, tip) 40...Actuator (gripping part) 50...Laser unit 53...Laser oscillator 55...Galvanometer mirror 57...Condenser lens 70...Pallet unit 73, 74, 75...Palette J1…1st axis J2…2nd axis J3...Third axis J4…4th axis J5…5th axis J6…6th axis Jw...Work axis K...Machining reference axis P…Standby position Rn…Predetermined direction Rr: Opposite direction S103...Workpiece removal process (first step) S107...Workpiece rotation process (second step) S111...Workpiece return process (third step) W, Wa, Wb...Work θ…the angle

Claims

1. a first arm having a base end supported by the base so as to be rotatable about a second axis perpendicular to the first axis; a second arm having a base end supported by the base end of the first arm so as to be rotatable about a third axis parallel to the second axis and a tip end rotatable about a fourth axis perpendicular to the third axis; a wrist having a base end supported by the second arm so as to be rotatable about a fifth axis perpendicular to the fourth axis, the wrist being offset from the second arm; and a gripper provided at the tip of the wrist so as to be rotatable about a sixth axis perpendicular to the fifth axis, a first step of gripping an intermediate portion of a rod-shaped workpiece placed on a pallet before machining with the gripping portion so that the workpiece axis and the sixth axis are perpendicular to each other, and then moving the workpiece into a machining space and positioning it at a predetermined position within the machining space; a second step of swinging the wrist about the fifth axis, rotating the second arm in a predetermined direction about the fourth axis and swinging it about the third axis, swinging the first arm about the second axis, and rotating the body about the first axis so that the gripping portion gripping the workpiece positioned at the predetermined position turns around the workpiece axis together with the wrist without rotating about the sixth axis, thereby providing a period during which predetermined processing can be performed on the workpiece rotating about the workpiece axis at the predetermined position; a third step of moving the processed workpiece held by the gripping unit at the predetermined position to the pallet or another pallet and placing it thereon; A method for controlling a robot, comprising:

2. 2. The robot control method according to claim 1, wherein in the first step, the second arm rotates about the fourth axis in a direction opposite to the predetermined direction from when the workpiece is gripped by the gripping portion until when the workpiece is moved to the predetermined position.

3. 2. The robot control method according to claim 1, wherein in the third step, the second arm rotates about the fourth axis in a direction opposite to the predetermined direction from when the processed workpiece is gripped by the gripping portion until when the processed workpiece is moved to the pallet or the other pallet.

4. The robot control method according to any one of claims 1 to 3, characterized in that the predetermined position is determined within a range from a predetermined angle of 0 degrees located coaxially with a predetermined machining reference axis within the machining space to a predetermined angle of 90 degrees located perpendicular to the machining reference axis.

5. A control program causing a computer that controls a robot to execute the robot control method according to any one of claims 1 to 3.

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