Machining head, machining head module, and multi-axis robot

Abstract

The present invention shortens the time required for returning to a cutting operation.　A machining head (21) attached to an arm (12) of a multi-axis robot (R) comprises: an implement (64) that cuts a workpiece (W) while, due to the movement of the arm (12), moving relative to the workpiece (W) in a cutting direction (C); and an actuator (30) that moves the implement (64) relative to the arm (12). When a reaction force from the workpiece (W) to the implement (64) exceeds a threshold value in a cutting step with respect to the workpiece (W), the implement (64) is, at a speed higher than the movement speed in the cutting direction (C) caused by the movement of the arm (12), separated from the workpiece (W) by the actuator (30).

Description

Processing head, processing head module, multi-axis robot

[0001] The present disclosure relates to a processing head, a processing head module, and a multi-axis robot.

[0002] Patent Document 1 discloses a control method for deburring a workpiece using a multi-axis robot having a plurality of arms connected so as to be relatively displaceable. A deburring tool is attached to the tip of the arm via an overload detection sensor. In the deburring process, the tool is moved by controlling the movement of the arm. When an overload is applied to the tool during the deburring process, the axis control means stops the movement of the arm, and then the axis control means controls the movement of the arm to move the tool in a direction to retreat from the workpiece.

[0003] Japanese Patent Laid-Open No. 9-011079

[0004] Since there is a clearance between the gears that mesh with each other in the shaft structure part that connects the arms, it is inevitable that the arms can be slightly displaced relative to each other. Therefore, even when the axis control means stops the movement of the arm when an overload is applied to the tool, due to the clearance between the gears and the inertia caused by the weight of the arm, the tip side of the arm overshoots, so the movement of the tool cannot be instantaneously stopped. Also, when retreating the tool in a direction away from the workpiece, for the same reason as above, the retreat operation of the tool cannot be instantaneously started. Furthermore, in order to temporarily stop the rotation of the tool, there is a time loss until the tool reaches the rotational speed required for cutting, and the time required to resume the cutting operation becomes long.

[0005] The present disclosure has been completed based on the above circumstances, and an object thereof is to shorten the time required to resume the cutting operation.

[0006] The machining head of the first disclosure is a machining head attached to an arm constituting a multi-axis robot, comprising: a tool that cuts a workpiece while moving relative to the workpiece in the cutting direction by the movement of the arm; and an actuator that moves the tool relative to the arm, wherein when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process, the tool is moved away from the workpiece by the actuator at a speed faster than the speed of movement in the cutting direction by the movement of the arm.

[0007] The machining head module of the second disclosure includes: a machining head attached to an arm constituting a multi-axis robot; a tool constituting the machining head that cuts the workpiece while moving relative to the workpiece in the cutting direction by the movement of the arm; an actuator constituting the machining head that moves the tool relative to the arm; and a control device that controls the movement of the actuator, wherein the control device controls the actuator when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process, thereby moving the tool away from the workpiece at a speed faster than the speed of movement in the cutting direction by the movement of the arm.

[0008] The multi-axis robot of the third disclosure comprises: a plurality of arms connected so as to be displaceable relative to each other; a robot control unit that controls the movement of the arms; a machining head attached to the arms; a tool that constitutes the machining head and cuts the workpiece while moving relative to the workpiece in the cutting direction by the movement of the arms; an actuator that constitutes the machining head and moves the tool relative to the arms; and a control device that controls the movement of the actuator, wherein the control device controls the actuator when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process on the workpiece, thereby moving the tool away from the workpiece at a speed faster than the speed of the relative movement by the movement of the arms.

[0009] According to the first to third disclosures, it is possible to shorten the time required to return to the cutting operation.

[0010] This is a perspective view of the multi-axis robot of Embodiment 1. This is a perspective view of the machining head viewed from diagonally above. This is a perspective view of the machining head viewed from diagonally below. This is a perspective view of the X-axis drive module of the machining head viewed from diagonally below. This is a perspective view of the Y-axis drive module of the machining head viewed from diagonally below. This is a perspective view of the Y-axis movable member of the machining head viewed from diagonally below. This is a schematic plan view showing the state in which cutting is being performed on the workpiece properly. This is a schematic plan view showing the state in which the tool is overloaded during the process of cutting the workpiece. This is a schematic plan view showing the state in which the overloaded tool has moved away from the workpiece during the process of cutting the workpiece. This is a block diagram showing the configuration for controlling the movement of the tool.

[0011] Herein, we present examples of preferred embodiments of this disclosure. Any combination of the following examples of embodiments, provided they do not contradict each other, is also included as an embodiment for carrying out the invention.

[0012] The machining head of the first disclosure is (1) a machining head attached to an arm constituting a multi-axis robot, comprising a tool that cuts the workpiece while moving relative to the workpiece in the cutting direction by the movement of the arm, and an actuator that moves the tool relative to the arm, wherein when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process, the tool is moved away from the workpiece by the actuator at a speed faster than the speed of movement in the cutting direction by the movement of the arm.

[0013] According to the first disclosure, when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process, the actuator separates the tool from the workpiece, thus preventing cutting defects caused by the increase in the reaction force from the workpiece to the tool. In a multi-axis robot with multiple arms connected together, the total weight of the arms is large, so the arms overshoot due to inertia during the process of separating the tool from the workpiece. However, since the speed at which the tool separates from the workpiece is faster than the speed at which the tool moves in the cutting direction due to the movement of the arms, the tool can be reliably separated from the workpiece. According to this disclosure, since it is not necessary to stop the rotation of the tool when the reaction force from the workpiece to the tool exceeds a threshold, the time required to return to the cutting operation can be shortened.

[0014] (2) In (1), the direction in which the actuator separates the tool from the workpiece is preferably a direction away from the cutting surface located in front of the cutting direction on the workpiece. With this configuration, even if the arm continues to overshoot after the tool separation operation by the actuator is completed, it is possible to prevent the tool from colliding with the cutting surface after the separation operation is completed.

[0015] (3) In (2), it is preferable that the direction in which the tool is separated from the workpiece is in the opposite direction to the cutting direction. With this configuration, even if the arm overshoots during the process of separating the tool from the workpiece, the tool can be reliably separated from the workpiece.

[0016] (4) In (2), it is preferable that the direction in which the actuator separates the tool from the workpiece is intersecting with the cutting direction. With this configuration, the tool does not come into contact with the cut surface of the workpiece during the process of separating the tool from the workpiece, so that the cut surface can be kept in good condition.

[0017] (5) In (1) to (4), it is preferable that the actuator has two movable members that move relative to each other in mutually orthogonal directions on a two-dimensional plane, and that the tool is attached to the arm via the two movable members. With this configuration, the tool can be moved away in any direction by changing the movement speed of the two movable members.

[0018] (6) In (1) to (4), it is preferable to determine whether the reaction force from the workpiece to the tool exceeds the threshold based on at least one of the feedback signals from the actuator servo motor for driving the actuator, the arm servo motor for driving the arm, and the spindle servo motor for rotationally driving the tool. With this configuration, it is possible to accurately determine whether the reaction force from the workpiece to the tool exceeds the threshold by comparing it with a command value, etc. At least one of the following can be used as the feedback signal: current value, torque, position, and rotational speed. Among these, the current value is preferred. In particular, from the viewpoint of processing speed, it is preferable to make the determination based on the current value of the actuator servo motor.

[0019] The machining head module of the second disclosure includes: (7) a machining head attached to an arm constituting a multi-axis robot; a tool constituting the machining head that cuts the workpiece while moving relative to the workpiece in the cutting direction by the movement of the arm; an actuator constituting the machining head that moves the tool relative to the arm; and a control device that controls the movement of the actuator, wherein the control device controls the actuator when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process on the workpiece, thereby moving the tool away from the workpiece at a speed faster than the speed of movement in the cutting direction by the movement of the arm.

[0020] According to the second disclosure, when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process, the control device controls the actuator to separate the tool from the workpiece, thereby preventing cutting defects caused by the increase in the reaction force from the workpiece to the tool. In a multi-axis robot with multiple arms connected together, the total weight of the arms is large, so the arms overshoot due to inertia during the process of separating the tool from the workpiece. However, since the speed at which the tool separates from the workpiece is faster than the speed at which the tool moves in the cutting direction due to the movement of the arms, the tool can be reliably separated from the workpiece. According to this disclosure, since it is not necessary to stop the rotation of the tool when the reaction force from the workpiece to the tool exceeds a threshold, the time required to return to the cutting operation can be shortened.

[0021] The multi-axis robot of the third disclosure comprises (8) a plurality of arms connected so as to be displaceable relative to each other, a robot control unit that controls the movement of the arms, a machining head attached to the arms, a tool that constitutes the machining head and cuts the workpiece while moving relative to the workpiece in the cutting direction by the movement of the arms, an actuator that constitutes the machining head and moves the tool relative to the arms, and a control device that controls the movement of the actuator, wherein the control device controls the actuator when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process for the workpiece, thereby moving the tool away from the workpiece at a speed faster than the speed of the relative movement by the movement of the arms.

[0022] According to the third disclosure, when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process, the control device controls the actuator to separate the tool from the workpiece, thereby preventing cutting defects caused by the increase in the reaction force from the workpiece to the tool. In a multi-axis robot with multiple arms connected together, the total weight of the arms is large, so the arms overshoot due to inertia during the process of separating the tool from the workpiece. However, since the speed at which the tool separates from the workpiece is faster than the speed at which the tool moves in the cutting direction due to the movement of the arms, the tool can be reliably separated from the workpiece. According to this disclosure, since it is not necessary to stop the rotation of the tool when the reaction force from the workpiece to the tool exceeds a threshold, the time required to return to the cutting operation can be shortened.

[0023] In (9) and (8), when the reaction force from the workpiece to the tool exceeds the threshold, it is preferable for the robot control unit to reduce the speed of the arm's movement to move the tool in the cutting direction. If the arm continues to overshoot even after the tool separation operation by the actuator is completed, there is a concern that the time required for the tool to return from the separation position to the intended cutting target position will be extended. With the above configuration, by reducing the speed of the arm's movement in the cutting direction, the overshoot distance can be shortened, and thus the time required for the tool to return to the intended cutting target position can be shortened.

[0024] [Embodiment 1] A multi-axis robot R, a machining head module 20, and a machining head 21 according to Embodiment 1 of the present disclosure will be described with reference to Figures 1 to 10. The present invention is not limited to these examples and is shown by the claims, with all modifications in the meaning and scope equivalent to the claims.

[0025] The multi-axis robot R comprises a base 10, a robot control unit 66 (see Figure 10), a multi-joint arm 11, multiple arm servo motors 14, and a machining head module 20. The base 10 is fixed to the floor. The robot control unit 66 is located in a separate component or device (position) from the multi-axis robot R and the control device 65. The robot control unit 66 has a servo amplifier (not shown) that receives commands from the control device 65 and supplies the necessary power to the arm servo motors 14 to execute the task. The multi-joint arm 11 is constructed by connecting multiple arms 12 and multiple joints 16 in series. The connected arms 12 can be displaced (rotated) relative to each other by the arm servo motors 14. The base end 11B of the multi-joint arm 11 is supported on the upper surface of the base 10 so as to be able to rotate horizontally.

[0026] The three-dimensional position, movement speed, and orientation of the tip 11T of the articulated arm 11 are controlled by the operation of the arm servo motors 14. The operating status of each arm servo motor 14 is detected by a detection unit such as an encoder built into each arm servo motor 14 and returned as a feedback signal to the servo amplifier in the robot control unit 66. Based on this feedback signal, the robot control unit 66 controls each arm servo motor. For convenience, the number of arm servo motors 14 in the block diagram of Figure 10 is shown as six.

[0027] In the joints 16 that connect the arms 12, the driving force of the arm servo motor 14 is transmitted to the arms 12 and joints 16 via reduction gears (not shown). A small clearance (play) is necessary between the reduction gears to ensure smooth rotation of the reduction gears. As a result, a slight relative displacement may occur between the arms 12 even when the articulated arms 11 are not being driven. Therefore, it is difficult to control the position, movement speed, and direction of the tip 11T of the articulated arms 11 with high precision.

[0028] The machining head module 20 comprises a machining head 21 and a control device 65. The machining head 21 is attached to the tip 11T of the articulated arm 11. As shown in Figures 2 and 3, the machining head 21 comprises a support member 22 fixed to the tip 11T of the articulated arm 11, an actuator 30 attached to the support member 22, a spindle 60 attached to the actuator 30, and a cutting tool 64 that is rotationally driven by the spindle 60.

[0029] The structure of the machining head 21 will now be described assuming the axis of the tool 64 is oriented in the vertical direction. The support member 22 has a horizontal base plate portion 23 and a support plate portion 24 that rises from the outer peripheral edge of the base plate portion 23. The support plate portion 24 is fixed to the tip portion 11T of the articulated arm 11. The base plate portion 23 has a through hole 25 that opens in a circular shape when viewed from above in a plan view of the machining head 21.

[0030] As shown in Figures 2 and 3, the actuator 30 includes an X-axis drive module 31, a Y-axis drive module 40, and a Y-axis movable member 50. As shown in Figure 4, the X-axis drive module 31 includes a fixed plate 32 fixed to the lower surface of the base plate 23, an X-axis servo motor 34, and a pair of X-axis guide rails 37. The fixed plate 32 has a first communication hole 33 that is circular, concentric with and the same diameter as a through hole 25. The X-axis servo motor 34 has an X-axis male screw member 35 whose axis is oriented in the X-axis direction and is fixed to the outer edge of the fixed plate 32. The X-axis servo motor 34 rotates the X-axis male screw member 35 in both forward and reverse directions. The operating status of the X-axis servo motor 34 is detected by a detection unit such as an encoder built into the X-axis servo motor 34 and returned as a feedback signal to the actuator servo amplifier 36 in the control device 65. The X-axis guide rail 37 is a member that extends in the X-axis direction and is positioned on the lower surface of the fixing plate 32.

[0031] As shown in Figure 5, the Y-axis drive module 40 includes a plate-shaped X-axis movable member 41 positioned opposite the lower surface of the fixed plate 32, an X-axis sliding member 43, an X-axis female thread member 44, a Y-axis servo motor 45, and a pair of Y-axis guide rails 48. The X-axis movable member 41 has a through hole 25 and a second communication hole 42 which is circular and has the same diameter as the first communication hole 33. When the X-axis movable member 41 is in the origin position, the first communication hole 33 is positioned concentrically with the through hole 25. The X-axis sliding member 43 is fixed to the upper surface of the X-axis movable member 41 and fitted to the X-axis guide rail 37 so that it can slide in the X-axis direction. The X-axis female thread member 44 is fixed to the outer edge of the X-axis movable member 41 and is screwed into the X-axis male thread member 35.

[0032] The Y-axis servo motor 45 has a Y-axis male threaded member 46 whose axis is oriented in the Y-axis direction (a direction perpendicular to the X-axis in a plan view), and is fixed to the outer edge of the X-axis movable member 41. The Y-axis servo motor 45 rotates the Y-axis male threaded member 46 in both forward and reverse directions. The operating status of the Y-axis servo motor 45 is detected by a detection unit such as an encoder built into the Y-axis servo motor 45, and is returned as a feedback signal to the actuator servo amplifier 36 in the control device 65. The Y-axis guide rail 48 is a member that extends in the Y-axis direction and is located on the lower surface of the X-axis movable member 41.

[0033] The Y-axis movable member 50 is a plate-shaped member positioned opposite the lower surface of the X-axis movable member 41. As shown in Figure 6, the Y-axis movable member 50 has a circular mounting hole 51 that penetrates the Y-axis movable member 50 vertically. The mounting hole 51 is positioned concentrically with the through hole 25, the first communication hole 33, and the second communication hole 42 when both the X-axis movable member 41 and the Y-axis movable member 50 are at their origin positions. A Y-axis sliding member 53 is fixed to the upper surface of the Y-axis movable member 50. The Y-axis sliding member 53 is fitted to the Y-axis guide rail 48 so that it can slide in the Y-axis direction. A Y-axis female thread member 52 is fixed to the outer periphery of the Y-axis movable member 50. The Y-axis female thread member 52 is screwed into the Y-axis male thread member 46.

[0034] As shown in Figures 2 and 3, the spindle 60 has a spindle servo motor 61 with its axis oriented vertically and a drive shaft 63 that protrudes downward from the spindle servo motor 61. The spindle 60 is fixed concentrically with respect to the mounting hole 51 of the Y-axis movable member 50. The spindle servo motor 61 is positioned to pass through the through hole 25, the first communication hole 33, and the second communication hole 42 in a non-contact manner and protrude above the base plate portion 23. The drive shaft 63 protrudes downward from the Y-axis movable member 50. A tool 64 is coaxially and detachably attached to the lower end of the drive shaft 63. The spindle servo motor 61 rotates the tool 64. The operating status of the spindle servo motor 61 is detected by a detection unit such as an encoder built into the spindle servo motor 61 and returned as a feedback signal to the spindle servo amplifier 62 in the control device 65.

[0035] The control device 65 is located separately from the multi-axis robot R. The control device 65 includes a PLC (Programmable Logic Controller) 67, an actuator servo amplifier 36, and a spindle servo amplifier 62. The actuator servo amplifier 36 receives commands from the PLC 67 and supplies the necessary power to the X-axis servo motor 34 and Y-axis servo motor 45 to execute the task. The spindle servo amplifier 62 supplies the necessary power to the spindle servo motor 61 to execute the task of the command received from the PLC 67. The control device 65 then controls the X-axis servo motor 34 and Y-axis servo motor 45 of the actuator 30 and the spindle servo motor 61 based on the feedback signals returned to the actuator servo amplifier 36 and the spindle servo amplifier 62.

[0036] When the control device 65 drives the X-axis servo motor 34, the X-axis male screw member 35 rotates, causing the Y-axis drive module 40 and spindle 60 to move in the X-axis direction along the X-axis guide rail 37. When the control device 65 drives the Y-axis servo motor 45, the Y-axis male screw member 46 rotates, causing the Y-axis movable member 50 and spindle 60 to move in the Y-axis direction along the Y-axis guide rail 48. When both the X-axis servo motor 34 and the Y-axis servo motor 45 are driven, the spindle 60 moves in a direction oblique to both the X-axis and Y-axis directions.

[0037] The components of the actuator 30 (X-axis drive module 31, Y-axis drive module 40, and Y-axis movable member 50) and the spindle 60 attached to the actuator 30 are lighter than the arm 12 and joint 16 that make up the articulated arm 11. Therefore, the speed at which the actuator 30 moves the spindle 60 in the X-axis direction and the speed at which it moves in the Y-axis direction are faster than the speed at which the tip 11T of the articulated arm 11 moves.

[0038] Furthermore, since the X-axis male threaded member 35 and the X-axis female threaded member 44 are fitted together by a helical screw-in structure, there is almost no clearance between the X-axis male threaded member 35 and the X-axis female threaded member 44 that would cause relative displacement between the X-axis drive module 31 and the Y-axis drive module 40. Similarly, since the Y-axis male threaded member 46 and the Y-axis female threaded member 52 are fitted together by a helical screw-in shape, there is also almost no clearance between the Y-axis male threaded member 46 and the Y-axis female threaded member 52 that would cause relative displacement between the Y-axis drive module 40 and the Y-axis movable member 50. Therefore, the speed and direction when the actuator 30 moves the spindle 60 in the X-axis and Y-axis directions can be controlled with higher precision than the tip portion 11T of the articulated arm 11.

[0039] Next, the process of cutting the side surface of a metal workpiece W with a tool 64 will be described. In the cutting process, the robot control unit 66 controls the movement of the articulated arm 11, causing the tool 64 (spindle 60) to move forward in the X-axis direction in Figure 7. The direction in which the articulated arm 11 moves the tool 64 in the cutting process is defined as the cutting direction C. The cutting direction C is parallel to the side edge of the workpiece W. In the process of moving in the cutting direction C, the tool 64 rotates at a predetermined rotational speed by the spindle servo motor 61, cutting the side edge of the workpiece W. While the cutting is being performed properly, the movable member 41 for the X-axis and the movable member 50 for the Y-axis do not operate.

[0040] If there is a projection P that protrudes excessively from the side edge of the workpiece W in front of the cutting direction C, as shown in Figure 8, the tool 64 will abut against the projection P, causing the reaction force from the workpiece W to the tool 64 to become greater than when cutting is being performed properly, resulting in an overload on the tool 64. When the load (reaction force) on the tool 64 increases and becomes overloaded, the feedback signals from at least one of the servo motors 14, 34, 45, or 61 among the actuator 30's X-axis servo motor 34, Y-axis servo motor 45, spindle servo motor 61, and multiple arm servo motors 14 will exceed a preset threshold.

[0041] The control device 65, based on the detection of an abnormality (exceeding a threshold) in the feedback signal returned to at least one of the servo amplifiers among the actuator servo amplifier 36, the spindle servo amplifier 62, and the servo amplifier in the robot control unit 66, determines that the reaction force on the tool 64 has exceeded a preset threshold, and drives the X-axis servo motor 34 and Y-axis servo motor 45 of the actuator 30 to move the tool 64 away from the workpiece W.

[0042] The direction in which the tool 64 is moved is, for example, a direction away from the cutting target surface S located in front of the tool 64 in the cutting direction C among the work W (the left direction in FIGS. 7 to 9). The direction in which the tool 64 is separated from the work W may be a direction opposite to the cutting direction C, or a direction intersecting the cutting direction C (the direction of the arrow E in FIG. 9, or a direction oblique to both the cutting direction C and the direction of the arrow E).

[0043] During the retraction of the tool 64 from the work W, it is inevitable that the tip 11T of the multi-joint arm 11 overshoots in the cutting direction C. As a countermeasure, the control device 65 retracts the tool 64 from the work W by the actuator 30, and at the same time, controls the arm servo motor 14 via the robot control unit 66 to reduce the moving speed of the arm 12 in the cutting direction C. By controlling the arm servo motor 14, it is possible to prevent the tool 64 from being pressed against the cutting target surface S of the work W.

[0044] By retracting the tool 64 from the work W, the reaction force from the work W to the tool 64 decreases. Therefore, the robot control unit 66 approaches the tool 64 to the work W again and resumes cutting. After resuming cutting, when the reaction force exceeds the threshold value, the control to separate the tool 64 from the work W is repeated as described above. Incidentally, when resuming cutting after once retracting the tool 64 from the work W, it is preferable to change the cutting conditions such as reducing the feed speed of the tool 64 by the arm 12.

[0045] While retracting the tool 64 in the direction of separating it from the work W, the spindle 60 maintains the rotational speed of the tool 64 at the same rotational speed as during cutting. If the rotational speed of the tool 64 is reduced or the rotation of the tool 64 is stopped while the tool 64 is in contact with the work W, there is a risk of cutting defects such as uneven cutting surfaces or cutting marks remaining. Also, if the rotation of the tool 64 is temporarily stopped, the time required to resume the cutting operation becomes longer. In the first embodiment, since the rotational speed (rotation speed) of the tool 64 is maintained at the same speed as during cutting, cutting defects are prevented and the time required to resume cutting is shortened.

[0046] The multi-axis robot R of the first embodiment includes a plurality of arms 12 connected so as to be relatively displaceable, a robot control unit 66, and a machining head module 20. The robot control unit 66 controls the movement of the arms 12. The machining head module 20 includes a machining head 21 and a control device 65. The machining head 21 is attached to the tip 11T of the arm 12 that constitutes the articulated arm 11. The machining head 21 includes a tool 64 and an actuator 30.

[0047] The tool 64 that constitutes the machining head 21 cuts the workpiece W while relatively moving in the cutting direction C with respect to the workpiece W by the movement of the arm 12. The actuator 30 that constitutes the machining head 21 relatively moves the tool 64 with respect to the arm 12 (the tip 11T of the articulated arm 11). The control device 65 controls the movement of the actuator 30. When the reaction force from the workpiece W to the tool 64 exceeds a threshold value in the cutting process for the workpiece W, the control device 65 controls the actuator 30 to move the tool 64 away from the workpiece W at a speed higher than the relative movement speed due to the movement of the arm 12.

[0048] According to this configuration, when the reaction force from the workpiece W to the tool 64 exceeds the threshold value in the cutting process, the control device 65 controls the actuator 30 to separate the tool 64 from the workpiece W, so that cutting defects caused by an increase in the reaction force from the workpiece W to the tool 64 can be prevented. Since the multi-axis robot R with the plurality of arms 12 connected has a large weight of the entire arm 12, the arm 12 overshoots due to inertia during the process of separating the tool 64 from the workpiece W.

[0049] However, since the speed at which the tool 64 separates from the workpiece W is higher than the moving speed of the tool 64 in the cutting direction C due to the movement of the arm 12, the tool 64 can be surely separated from the workpiece W. According to the multi-axis robot R and the machining head 21 of the first embodiment, when the reaction force from the workpiece W to the tool 64 exceeds the threshold value, it is not necessary to stop the rotation of the tool 64, so that the time required to return to the cutting operation can be shortened.

[0050] The direction in which the actuator 30 separates the tool 64 from the workpiece W is away from the cutting surface S located in front of the cutting direction C on the workpiece W. With this configuration, even if the arm 12 continues to overshoot after the tool 64 separation operation by the actuator 30 is completed, it is possible to prevent the tool 64 from colliding with the cutting surface S after the separation operation is completed. If the direction in which the tool 64 is separated from the workpiece W is the exact opposite direction to the cutting direction C, the tool 64 can be reliably separated from the workpiece W even if the arm 12 overshoots during the process of the tool 64 separating from the workpiece W.

[0051] If the actuator 30 moves the tool 64 away from the workpiece W in a direction intersecting the cutting direction C (such as the direction of arrow E in Figure 9, or the downward-left direction which is oblique to both the cutting direction C and arrow E), the tool 64 will not come into contact with the cut surface of the workpiece W during the process of moving it away from the workpiece W, thus maintaining the cut surface in good condition.

[0052] The actuator 30 has two movable members (X-axis movable member 41 and Y-axis movable member 50) that move relative to each other in mutually orthogonal directions (X-axis direction and Y-axis direction) on a two-dimensional plane. The tool 64 is attached to the arm 12 via the X-axis movable member 41 and the Y-axis movable member 50. With this configuration, the tool 64 can be moved away in any direction on the two-dimensional plane by individually changing the movement speed of the X-axis movable member 41 and the Y-axis movable member 50.

[0053] Whether the reaction force from the workpiece W to the tool 64 exceeds a threshold is determined based on at least one of the following feedback signals: the feedback signal from the actuator servo motors (X-axis servo motor 34 and Y-axis servo motor 45) for driving the actuator 30, the feedback signal from the arm servo motor 14 for driving the arm 12, and the feedback signal from the spindle servo motor 61 for rotationally driving the tool 64. With this configuration, it is possible to accurately determine whether the reaction force from the workpiece W to the tool 64 exceeds a threshold.

[0054] If the arm 12 continues to overshoot even after the actuator 30 has completed the tool 64's separation movement, there is a concern that the time required for the tool 64 to return from the separation position to the intended cutting target position will be prolonged. To address this, when the reaction force from the workpiece W to the tool 64 exceeds a threshold, the robot control unit 66 reduces the speed of the arm 12's movement to move the tool 64 in the cutting direction C. With this configuration, by reducing the speed of the arm 12's movement in the cutting direction C, the overshoot distance can be shortened, thereby reducing the time required for the tool 64 to return to the intended cutting target position.

[0055] <Other Embodiments> The present invention is not limited to the embodiments described above and in the drawings, and the following embodiments, for example, are also included in the technical scope of the present invention. A force sensor may be used as a means for determining whether the reaction force from the workpiece to the tool exceeds a threshold.

[0056] C: Cutting direction E: Direction intersecting the cutting direction P: Projection R: Multi-axis robot S: Cutting surface W: Workpiece 10: Base 11: Multi-joint arm 11B: Base end of multi-joint arm 11T: Tip end of multi-joint arm 12: Arm 14: Servo motor for arm 16: Joint 20: Machining head module 21: Machining head 22: Support member 23: Base plate 24: Support plate 25: Through hole 30: Actuator 31: X-axis drive module 32: Fixing plate 33: First communication hole 34: X-axis servo motor 35: X-axis male screw member 36: Actuator servo amplifier 37: X-axis guide rail 40: Y-axis drive module 41: X-axis movable member 42: Second communication hole 43: X-axis sliding member 44: X-axis female screw member 45...Servo motor for Y-axis 46...Male threaded member for Y-axis 48...Guide rail for Y-axis 50...Movable member for Y-axis 51...Mounting hole 52...Female threaded member for Y-axis 53...Sliding member for Y-axis 60...Spindle 61...Servo motor for spindle 62...Servo amplifier for spindle 63...Drive shaft 64...Tool 65...Control device 66...Robot control unit 67...PLC

Claims

1. A machining head attached to an arm constituting a multi-axis robot, comprising: a tool that cuts a workpiece while moving relative to the workpiece in the cutting direction by the movement of the arm; and an actuator that moves the tool relative to the arm, wherein when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process, the tool is moved away from the workpiece by the actuator at a speed faster than the speed of movement in the cutting direction by the movement of the arm.

2. The machining head according to claim 1, wherein the direction in which the actuator separates the tool from the workpiece is a direction away from the cutting surface located in front of the cutting direction on the workpiece.

3. The machining head according to claim 2, wherein the direction in which the tool is separated from the workpiece is in the exact opposite direction to the cutting direction.

4. The machining head according to claim 2, wherein the direction in which the actuator separates the tool from the workpiece is a direction intersecting the cutting direction.

5. The machining head according to any one of claims 1 to 4, wherein the actuator has two movable members that move relative to each other in mutually orthogonal directions on a two-dimensional plane, and the tool is attached to the arm via the two movable members.

6. The machining head according to any one of claims 1 to 4, wherein it is determined that the reaction force from the workpiece to the tool exceeds the threshold based on at least one of the feedback signals, which is a feedback signal from an actuator servo motor for driving the actuator, a feedback signal from an arm servo motor for driving the arm, and a feedback signal from a spindle servo motor for rotationally driving the tool.

7. A machining head module comprising: a machining head attached to an arm constituting a multi-axis robot; a tool constituting the machining head, which cuts the workpiece while moving relative to the workpiece in the cutting direction by the movement of the arm; an actuator constituting the machining head, which moves the tool relative to the arm; and a control device that controls the movement of the actuator, wherein the control device controls the actuator when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process, thereby moving the tool away from the workpiece at a speed faster than the speed of movement in the cutting direction by the movement of the arm.

8. A multi-axis robot comprising: a plurality of arms connected so as to be relatively displaceable; a robot control unit for controlling the movement of the arms; a machining head attached to the arms; a tool constituting the machining head for cutting the workpiece while moving relative to the workpiece in the cutting direction by the movement of the arms; an actuator constituting the machining head for moving the tool relative to the arms; and a control device for controlling the movement of the actuator, wherein the control device controls the actuator when the reaction force from the workpiece to the tool exceeds a threshold during the cutting process for the workpiece, thereby moving the tool away from the workpiece at a speed faster than the relative movement caused by the movement of the arms.

9. The multi-axis robot according to claim 8, wherein when the reaction force from the workpiece to the tool exceeds the threshold, the robot control unit reduces the speed of the movement of the arm for moving the tool in the cutting direction.

Images