Processing head module, multi-axis robot, and method for adjusting rotation axis of processing head

Abstract

The present invention achieves a time reduction in a step for adjusting a rotation axis of a processing head so as to be perpendicular to a drilling target surface.　A processing head module (16) comprises: a drill (33) that is attached to a multi-joint arm (12) and that drills a workpiece (W) while rotating; a processing head (17) that has a foot (40) which has a cylindrical shape concentric with the drill (33) and which brings an opening edge part (41) at the tip end into contact with a drilling target surface (S) of the workpiece (W); a control device (46) that controls the processing head (17); a force sensor (45) that detects a reaction force when the opening edge part (41) presses the drilling target surface (S); and a robot control unit (50) that equalizes the reaction force from the drilling target surface (S). The robot control unit (50), on the basis of detection information from the force sensor (45), controls the movement of the multi-joint arm (12) such that a pressing portion (43) of the opening edge part (41) against the drilling target surface (S) is displaced in the circumferential direction and such that a region of the pressing portion (43) expands in the circumferential direction.

Description

Processing Head Module, Multi-Axis Robot, and Method for Adjusting the Rotation Axis of a Processing Head

[0001] The present disclosure relates to a processing head module, a multi-axis robot, and a method for adjusting the rotation axis of a processing head.

[0002] Patent Document 1 discloses a robot having a robotic arm, a drilling device attached to the tip of the robotic arm, and a robot control unit that controls the robotic arm. The drilling device has a drill for forming a through hole in a workpiece. The drill is rotationally driven while being held by a spindle, and the spindle strokes in the advancing and retreating directions with respect to the workpiece. When forming a through hole, the robot control unit controls the robotic arm to determine the orientation of the spindle with respect to the workpiece. A force sensor is used as a means for adjusting the stroke direction of the spindle with respect to the workpiece. The force sensor measures the moment around two axes on a two-dimensional plane orthogonal to the stroke direction as the reaction force from the workpiece to the drill, and the robot control unit controls the robotic arm so that the moment around these two axes becomes zero.

[0003] Japanese Patent Application Laid-Open No. 2023-137762

[0004] When the orientation of the spindle is inclined in an oblique direction with respect to both one axis and the other axis, in order to make the moments around both axes zero, it is necessary to repeatedly perform the process of tilting the spindle in a seesaw shape around one axis and the process of tilting the spindle in a seesaw shape around the other axis many times. Therefore, the robot described in Patent Document 1 has a problem that it takes time to adjust the orientation of the spindle.

[0005] The present disclosure has been completed based on the above circumstances, and aims to shorten the time in the process of adjusting the rotation axis of the processing head to be perpendicular to the drilling target surface.

[0006] The machining head module of the first disclosure is attached to an articulated arm constituting a multi-axis robot and comprises a machining head having a drill that drills a workpiece while rotating, a cylindrical foot concentric with the drill and having an opening edge at its tip that contacts the surface of the workpiece to be drilled, a control device for controlling the machining head, a force sensor for detecting the reaction force when the opening edge presses against the surface to be drilled, and a robot control unit for leveling the reaction force from the surface to be drilled, wherein the robot control unit controls the movement of the articulated arm based on the detection information of the force sensor such that the pressing portion of the opening edge against the surface to be drilled is displaced in the circumferential direction and the area of ​​the pressing portion expands in the circumferential direction.

[0007] The multi-axis robot of the second disclosure comprises: an articulated arm having multiple arms connected so as to be relatively displaceable; a machining head having a drill that drills a workpiece while rotating, the direction of the rotation axis of the drill changes with the movement of the articulated arm; a foot constituting the machining head, having a cylindrical shape concentric with the drill, and having an opening edge at the tip that contacts the surface of the workpiece to be drilled; a control device for controlling the machining head; a force sensor for detecting the reaction force when the opening edge presses against the surface to be drilled; and a robot control unit for leveling the reaction force from the surface to be drilled. The robot control unit controls the movement of the articulated arm based on the detection information of the force sensor such that the pressing portion of the opening edge against the surface to be drilled is displaced in the circumferential direction and the area of ​​the pressing portion expands in the circumferential direction.

[0008] The third disclosure provides a method for adjusting the rotation axis of a machining head, comprising: a multi-joint arm having a plurality of arms connected so as to be relatively displaceable; a machining head having a drill that drills a workpiece while rotating, the direction of the rotation axis of the drill changing with the movement of the multi-joint arm; a foot constituting the machining head, having a cylindrical shape concentric with the drill, and having an opening edge at its tip that contacts the surface of the workpiece to be drilled; a control device for controlling the machining head; a force sensor for detecting the reaction force when the opening edge presses against the surface to be drilled; and a robot control unit for leveling the reaction force from the surface to be drilled. Based on the detection information from the force sensor, the robot control unit controls the movement of the multi-joint arm so that the pressing portion of the opening edge against the surface to be drilled is displaced in the circumferential direction, and the area of ​​the pressing portion expands in the circumferential direction.

[0009] According to the first, second, and third disclosures, time can be reduced in the process of adjusting the rotation axis of the processing head so that it is perpendicular to the surface to be drilled.

[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 below. This is a side cross-sectional view showing the state in which the rotation axis of the machining head is perpendicular to the surface to be drilled and the foot is in contact with the surface to be drilled. This is a side cross-sectional view showing the state in which the workpiece has been drilled by the drill. This is a plan cross-sectional view of the machining head. This is a side cross-sectional view showing the state in which the rotation axis of the machining head is oblique to the surface to be drilled and the foot is pressing against the surface to be drilled. This is a block diagram showing a configuration for controlling the movement of the multi-joint arm so that the rotation axis of the machining head is perpendicular to the surface to be drilled.

[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 module of the first disclosure comprises: (1) a machining head attached to an articulated arm constituting a multi-axis robot, having a drill that drills a workpiece while rotating, and a foot that is cylindrical in shape concentric with the drill and has an opening edge at its tip that contacts the surface of the workpiece to be drilled; a control device for controlling the machining head; a force sensor for detecting the reaction force when the opening edge presses against the surface to be drilled; and a robot control unit for leveling the reaction force from the surface to be drilled, wherein the robot control unit controls the movement of the articulated arm based on the detection information of the force sensor such that the pressing portion of the opening edge against the surface to be drilled is displaced in the circumferential direction and the area of ​​the pressing portion expands in the circumferential direction.

[0013] According to the first disclosure, when the robot control unit controls the movement of the articulated arm, the machining head changes its posture so as to displace the pressing portion on the drilling target surface at the opening edge of the foot in the circumferential direction, and the rotation axis of the drill rotates in a precessional manner, moving in a conical pattern. During the process in which the pressing portion on the drilling target surface at the opening edge is displaced in the circumferential direction, the robot control unit corrects the movement of the articulated arm based on information detected from the force sensor. As the movement of the articulated arm is corrected, the rotational shape of the rotation axis becomes a spiral motion in which the rotational diameter gradually decreases. As the reaction force is leveled, the area of ​​the pressing portion at the opening edge expands in the circumferential direction. When the reaction force is leveled over the entire circumference of the opening edge, the adjustment of the orientation of the rotation axis is completed, and the rotation axis becomes perpendicular to the drilling target surface. According to the first disclosure, since the direction of the rotation axis is adjusted while the machining head is rotated in a spiral manner, it is possible to shorten the time compared to a system that repeatedly performs a seesaw-like motion to make the moment around two axes with different directions zero.

[0014] (2) In (1), it is preferable that the robot control unit controls the movement of the articulated arm so that the pressing portion is always in contact with the surface to be drilled. With this configuration, the time required for adjustment can be reduced compared to the case in which the operation of moving the pressing portion away from the surface to be drilled and the operation of pressing the pressing portion against the surface to be drilled are repeated.

[0015] (3) In (1) or (2), it is preferable that the robot control unit controls the movement of the articulated arm so that the pressing portion is displaced in only one direction in the circumferential direction of the opening edge. With this configuration, the time required for adjustment can be reduced compared to the case in which the pressing portion is displaced in a reciprocating manner in the circumferential direction of the opening edge.

[0016] (4) In (1) or (2), the force sensor is preferably a 6-axis force sensor. With this configuration, the direction of the rotation axis can be adjusted with higher precision.

[0017] The multi-axis robot of the second disclosure comprises: (5) a multi-joint arm having a plurality of arms connected so as to be relatively displaceable; a machining head having a drill that drills a workpiece while rotating, wherein the direction of the rotation axis of the drill changes with the movement of the multi-joint arm; a foot constituting the machining head, having a cylindrical shape concentric with the drill, and having an opening edge at the tip that contacts the surface to be drilled on the workpiece; a control device for controlling the machining head; a force sensor for detecting the reaction force when the opening edge presses the surface to be drilled; and a robot control unit for leveling the reaction force from the surface to be drilled, wherein the robot control unit controls the movement of the multi-joint arm based on the detection information of the force sensor such that the pressing portion of the opening edge against the surface to be drilled is displaced in the circumferential direction and the area of ​​the pressing portion expands in the circumferential direction. According to the second disclosure, the direction of the rotation axis is adjusted while the machining head is rotated in a spiral manner, so, similar to the first disclosure, time can be reduced in the process of adjusting the rotation axis of the machining head to be perpendicular to the surface to be drilled.

[0018] In (6) and (5), it is preferable that the force sensor is positioned between the tip of the articulated arm and the machining head. In the shaft structure connecting the arms, there is clearance between the gears that mesh with each other, so it is unavoidable that the arms may be slightly displaced relative to each other. Therefore, if the force sensor is positioned anywhere other than the tip of the articulated arm, the reaction force will be transmitted to the force sensor via the shaft structure. As a result, it is unavoidable that the accuracy of the force sensor's detection information will be reduced. To address this, the force sensor is positioned at the tip of the articulated arm. With this configuration, the reaction force from the workpiece is transmitted to the force sensor without going through the shaft structure of the articulated arm, thus improving the detection accuracy of the force sensor.

[0019] The third disclosure's method for adjusting the rotation axis of a machining head includes: (7) a multi-joint arm having a plurality of arms connected so as to be relatively displaceable, a drill that drills a workpiece while rotating, the direction of the rotation axis of the drill changing with the movement of the multi-joint arm, a foot constituting the machining head, having a cylindrical shape concentric with the drill, and having an opening edge at its tip that contacts the surface of the workpiece to be drilled, a control device for controlling the machining head, a force sensor for detecting the reaction force when the opening edge presses the surface to be drilled, and a robot control unit for leveling the reaction force from the surface to be drilled; and the robot control unit controls the movement of the multi-joint arm based on the detection information of the force sensor such that the pressing portion of the opening edge against the surface to be drilled is displaced in the circumferential direction and the area of ​​the pressing portion expands in the circumferential direction. According to the third disclosure, the direction of the rotation axis is adjusted while the machining head is rotated in a spiral manner. Therefore, as with the first and second disclosures, the time required to adjust the rotation axis of the machining head to be perpendicular to the surface to be drilled can be reduced.

[0020] <Embodiment 1> Embodiment 1, which embodies the present disclosure, will be described with reference to Figures 1 to 7. However, the present invention is not limited to these examples, and is intended to be shown by the claims, with all modifications in the meaning and scope of equivalence to the claims being included. In this embodiment 1, the front-to-back direction is defined as the F direction in Figures 1 to 6. The up-and-down direction is defined as the H direction in Figures 1 to 4 and 6. The left-to-right direction is defined as the R direction in Figures 1, 2 and 5.

[0021] The multi-axis robot A of this embodiment 1 comprises a robot body 10, a control device 46, and a robot control unit 50. The robot body 10 includes a base 11, a multi-joint arm 12, a plurality of arm servo motors 15, and a machining head module 16. The base 11 is fixed to the floor surface. The multi-joint arm 12 is constructed by connecting a plurality of arms 13 in series via joints 14. The connected arms 13 can be displaced (rotated) relative to each other by the arm servo motors 15. The base end of the multi-joint arm 12 is supported on the upper surface of the base 11 so as to be rotated horizontally. The position, movement speed, and orientation of the tip 12A of the multi-joint arm 12 in three dimensions are controlled by the operation of at least one arm servo motor 15. The operating status of each arm servo motor 15 is detected by a detection part such as an encoder built into each arm servo motor 15.

[0022] The joints 14 connecting the arms 13 are equipped with reduction gears (not shown) for transmitting the driving force of the arm servo motors 15 to each arm 13. A small clearance (play) is necessary between the meshing reduction gears to ensure smooth rotation of the reduction gears. As a result, even when the articulated arms 12 are not being driven, a slight relative displacement may occur between the arms 13. Therefore, it is difficult to control the position, movement speed, and direction of the tip portion 12A of the articulated arms 12 with high precision.

[0023] The machining head module 16 comprises a machining head 17 and a force sensor 45. The machining head 17 is attached to the tip 12A of the articulated arm 12. The machining head 17 comprises a frame 18 attached to the tip 12A of the articulated arm 12, an actuator 24 attached to the frame 18, a spindle 30 attached to the actuator 24, and a drill 33 for drilling that is rotationally driven by the spindle 30.

[0024] The structure of the machining head 17 will now be described assuming that the rotation axis 34 of the drill 33 is facing in the vertical direction. The frame 18 has a horizontal bottom plate portion 19 that forms a rectangle in a plan view when the machining head 17 is viewed from above, four vertical plate portions 20 rising from the outer edge of the bottom plate portion 19 on the front, back, left, and right sides, and a top plate portion 21 that is rectangular in plan view and connected to the upper edges of the four vertical plate portions 20. The frame 18 is fixed to the tip portion 12A of the articulated arm 12 via a force sensor 45 fixed to the upper surface of the top plate portion 21.

[0025] The actuator 24 is attached to the rear plate portion 20R of the four vertical plate portions 20. The actuator 24 comprises a male threaded rod 25 whose axis is oriented parallel to the rotation axis 34, a guide groove 26 extending parallel to the male threaded rod 25, an actuator servo motor 27 that rotates the male threaded rod 25 in both forward and reverse directions, and a lifting member 28 having a female threaded hole 29. The lifting member 28 is fitted into the guide groove 26 in a non-rotatable state with the female threaded hole 29 fitted to the male threaded rod 25. When the actuator servo motor 27 is driven to rotate the male threaded rod 25, the lifting member 28 slides in a direction parallel to the rotation axis 34 of the drill 33 (up and down direction) while sliding against the guide groove 26. The operating status of the actuator servo motor 27 is detected by a detection part such as an encoder built into the actuator servo motor 27.

[0026] A spindle 30 is attached to the lifting member 28. The spindle 30 is driven to move up and down by an actuator servo motor 27. The spindle 30 includes a spindle servo motor 31, a chuck 32, and a drill 33. The spindle servo motor 31 is fixed to the lifting member 28 and moves up and down together with the lifting member 28. A chuck 32, which is rotationally driven by the spindle servo motor 31, is provided at the lower end of the spindle servo motor 31. A drill 33 is detachably attached to the chuck 32. The drill 33 is an elongated member with its rotation axis 34 oriented vertically and protrudes downward from the chuck 32. When forming a through hole H in the workpiece W, the tip (lower end) of the drill 33 is abutted against the surface of the workpiece W opposite to the drill 33. The surface of the workpiece W opposite to the drill 33 is defined as the surface to be drilled S. The operating status of the spindle servo motor 31 is detected by a detection part such as an encoder built into the spindle servo motor 31.

[0027] A communication hole 35, which opens in a circular shape in plan view, is formed in the bottom plate portion 19 of the frame 18. A duct member 36 is fixed to the lower surface of the bottom plate portion 19. The duct member 36 has a cylindrical portion 37 with its axis oriented in the vertical direction, and a discharge portion 38 that extends diagonally upward and forward from the outer circumferential surface of the cylindrical portion 37. The upper end of the cylindrical portion 37 is in coaxial communication with the communication hole 35. A cylindrical foot 40 is detachably attached to the lower end edge of the cylindrical portion 37.

[0028] The foot 40 is a cylindrical component made of synthetic resin. The foot 40 is positioned concentrically with the rotation axis 34 of the drill 33, with its axis oriented vertically. The lower end edge of the foot 40 functions as a circular opening edge 41 to receive the reaction force when the foot 40 is pressed against the drilling surface S of the workpiece W. The lower surface of the opening edge 41 functions as a contact surface 42 consisting of a plane perpendicular to the axis of the foot 40, i.e., the rotation axis 34 of the drill 33.

[0029] The chuck 32 of the spindle 30 is positioned at a height that penetrates the communication hole 35. When the spindle 30 is at its uppermost position in its lifting stroke, the lower end of the drill 33 is above the lower end of the foot 40. When the spindle 30 is at its lowermost position in its lifting stroke, the lower end of the drill 33 is below the lower end of the foot 40.

[0030] The force sensor 45 consists of a 6-axis force sensor 45 that simultaneously detects the loads in the X, Y, and Z axes, and the moments around each of the X, Y, and Z axes. The force sensor 45 is installed such that the X and Y axes are perpendicular to the rotation axis 34 of the drill 33, and the Z axis is coaxial with the rotation axis 34 of the drill 33. The force sensor 45 is mounted between the tip 12A of the articulated arm 12 and the machining head 17. The force sensor 45 detects the reaction force acting on the foot 40 from the drilling surface S of the workpiece W when the foot 40 of the machining head 17 is pressed against the drilling surface S of the workpiece W. The detected reaction force values ​​are input to the robot control unit 50 as loads in each axial direction and moments around each axis, or are input to the control device 46, which will be described later, via the robot control unit 50.

[0031] The control device 46 is located separately from the robot body 10. The control device 46 includes a PLC (Programmable Logic Controller) 47, an actuator servo amplifier 48, and a spindle servo amplifier 49. The actuator servo amplifier 48 receives commands from the PLC 47 and supplies the necessary power to the actuator servo motor 27 to execute the task. The spindle servo amplifier 49 supplies the necessary power to the spindle servo motor 31 to execute the task of the command received from the PLC 47.

[0032] The actuator servo amplifier 48 receives feedback signals indicating the operating status of the actuator servo motor 27. The spindle servo amplifier 49 receives feedback signals indicating the operating status of the spindle servo motor 31. The control device 46 controls the actuator servo motor 27 of the actuator 24 and the spindle servo motor 31 based on the feedback signals returned to the actuator servo amplifier 48 and the spindle servo amplifier 49.

[0033] The control device 46 controls the actuator servo motor 27 and the spindle servo motor 31 based on detection information input from the force sensor 45 via the robot control unit 50, and also sends commands to the robot control unit 50. When the contact surface 42 of the opening edge 41 of the foot 40 comes into contact with the drilling target surface S of the workpiece W, the control device 46 controls the movement of the articulated arm 12 based on detection information output from the force sensor 45 so that the rotation axis 34 of the drill 33 is oriented perpendicular to the drilling target surface S.

[0034] The robot control unit 50 is located in a separate component or device (position) from the robot body 10 and the control device 46. The robot control unit 50 has a servo amplifier (not shown). This servo amplifier receives commands from the control device 46 and data from the force sensor 45, and supplies the necessary power to the arm servo motors 15 to perform tasks. The operating status of each arm servo motor 15 is returned to the servo amplifier of the robot control unit 50 as a feedback signal. Based on this feedback signal, the robot control unit 50 controls each arm servo motor 15.

[0035] Next, the process of forming a through hole H perpendicular to the drilling target surface S in a workpiece W made of metal or synthetic resin, with the workpiece W positioned with its drilling target surface S (plane) facing horizontally upward, will be described. First, the actuator servo motor 27 is started to move the drill 33 upward, and the lower end (tip) of the drill 33 is moved to a position above the opening edge 41 (contact surface 42) of the foot 40. Next, the arm servo motor 15 is driven to bring the contact surface 42 (opening edge 41) of the foot 40 into contact with the drilling target surface S from above in a pressing state.

[0036] In this case, as shown in Figure 6, if the rotation axis 34 of the drill 33 (the central axis of the foot 40) is oblique to the normal (not shown) perpendicular to the surface to be drilled S, then only a portion of the circumferential part of the opening edge 41 (contact surface 42) of the foot 40 will contact the surface to be drilled S. In this state, the reaction force acting from the workpiece W (surface to be drilled S) on the foot 40 is not uniform over the entire circumference of the foot 40. Therefore, the force sensor 45 detects the reaction force in at least one of the X-axis and Y-axis directions, and also detects the moment around at least one of the X-axis and Y-axis directions.

[0037] When detection information from the force sensor 45 is input to the control device 46, the control device 46 controls the servo motor 15 for the arm based on the detection information from the force sensor 45, thereby controlling the movement of each arm 13 of the articulated arm 12. By controlling the movement of the articulated arm 12, the direction of the rotation axis 34 is corrected while the processing head 17 (foot 40) is rotated. Specifically, the rotation axis 34 of the drill 33 is rotated like the precession of a spinning top, while the detection values ​​from the force sensor 45 are leveled. Since the foot 40 is made of synthetic resin, it is slightly elastically deformed by the reaction force from the surface to be drilled S. In this correction process (leveling process), the pressing portion 43 on the contact surface 42 of the foot 40 against the surface to be drilled S is displaced in the circumferential direction, and the contact area of ​​the pressing portion 43 against the surface to be drilled S expands in the circumferential direction.

[0038] When the rotation axis 34 becomes perpendicular to the surface to be drilled S, the force (load) applied to the surface to be drilled S becomes symmetrical in the X and Y axes with respect to the center point of the rotation axis 34 in a plan view perpendicular to the surface to be drilled S, and at the same time, the moment around the X axis and the moment around the Y axis become zero. When the force (load) applied in the X and Y axes becomes symmetrical, with respect to the center point of the rotation axis 34, the load on the positive coordinate side of each axis becomes equal to the load on the negative coordinate side of each axis. As a result, the opening edge 41 (contact surface 42) contacts the foot 40 with a uniform force over its entire circumference, and the correction process for the rotation axis 34 is completed. After this, if necessary, the drilling position is adjusted by moving the machining head 17 by controlling the articulated arm 12 with the control device 46. The machining head 17 maintains the orientation of its rotation axis 34 relative to the drilling target surface S, and after moving away from the workpiece W (drilling target surface S), it moves so that, in a plan view, the rotation axis 34 coincides with a predetermined drilling position on the drilling target surface S. When adjusting the drilling position, it is preferable to correct the spatial coordinate position using external equipment (laser tracker or stereo camera).

[0039] With the above steps completed, the process of correcting the orientation of the rotation axis 34 of the drill 33 relative to the workpiece W (the surface to be drilled S) and the preparation for the drilling process are completed. Next, the servo motor 27 for the actuator and the servo motor 31 for the spindle are started to rotate the drill 33 and lower the actuator 24. As a result, the drill 33 forms a through hole H in the workpiece W with its rotation axis 34 oriented perpendicular to the surface to be drilled S.

[0040] The multi-axis robot A of this embodiment 1 comprises a multi-joint arm 12, a machining head module 16 attached to the tip 12A of the multi-joint arm 12, a control device 46, and a robot control unit 50. The machining head module 16 comprises a machining head 17 and a force sensor 45. The machining head 17 has a drill 33 that drills into the workpiece W while rotating, and a foot 40. The foot 40 is cylindrical and concentric with the drill 33, and its opening edge 41 contacts the drilling target surface S of the workpiece W. The force sensor 45 detects the reaction force when the opening edge 41 presses against the drilling target surface S. The control device 46 controls the machining head 17. The robot control unit 50 has a function to equalize the reaction force from the drilling target surface S. The robot control unit 50 controls the movement of the multi-joint arm 12 based on the detection information from the force sensor 45. By controlling the movement of the articulated arm 12, the pressing portion 43 on the opening edge 41 against the surface S to be drilled is displaced in the circumferential direction, and the area of ​​the pressing portion 43 expands in the circumferential direction.

[0041] According to the multi-axis robot A, machining head module 16, and method for adjusting the rotation axis of the machining head 17 disclosed in this embodiment 1, the following effects can be obtained. When the robot control unit 50 controls the movement of the articulated arm 12, the machining head 17 changes its posture so as to displace the pressing portion 43 on the opening edge 41 of the foot 40 against the surface to be drilled S in the circumferential direction, and the rotation axis 34 of the drill 33 rotates in a precessional manner, moving in a conical pattern. During the process in which the pressing portion 43 on the opening edge 41 against the surface to be drilled S is displaced in the circumferential direction, the robot control unit 50 corrects the movement of the articulated arm 12 based on the detection information from the force sensor 45. As the movement of the articulated arm 12 is corrected, the rotational shape of the rotation axis 34 becomes a spiral motion in which the rotational diameter gradually decreases, the reaction force is leveled, and the area of ​​the pressing portion 43 on the opening edge 41 expands in the circumferential direction.

[0042] When the reaction force is leveled over the entire circumference of the opening edge portion 41, the adjustment of the direction of the rotation axis 34 is completed, and the rotation axis 34 becomes perpendicular to the drilling target surface S. According to the multi-axis robot A and the processing head module 16 of the first embodiment, since the direction of the rotation axis 34 is adjusted while the processing head 17 is rotated in a spiral shape, compared with repeating a seesaw-like movement to make the moments around two axes with different directions zero, time can be shortened.

[0043] The robot control unit 50 controls the movement of the multi-joint arm 12 so that the pressing portion 43 always remains in contact with the drilling target surface S. According to this configuration, compared with the case of repeating the operation of separating the pressing portion 43 from the drilling target surface S and the operation of pressing the pressing portion 43 against the drilling target surface S, the time required for adjustment can be shortened. The robot control unit 50 controls the movement of the multi-joint arm 12 so that the pressing portion 43 is displaced only in one direction in the circumferential direction of the opening edge portion 41. According to this configuration, compared with the case where the pressing portion 43 is displaced so as to reciprocate in the circumferential direction of the opening edge portion 41, the time required for adjustment can be shortened. Since the force sensor 45 is a six-axis force sensor, the direction of the rotation axis 34 can be adjusted with higher accuracy.

[0044] In the shaft structure portion that connects the arms 13 of the robot body 10, since there is a clearance between the gears that mesh with each other, it is inevitable that the arms 13 can be slightly displaced relative to each other. Therefore, when the force sensor 45 is arranged at a position closer to the base end side than the tip end portion 12A of the multi-joint arm 12, the reaction force from the workpiece W (drilling target surface S) is transmitted to the force sensor 45 via the shaft structure portion. As a result, it is inevitable that the detection accuracy of the detection information of the force sensor 45 becomes low. As a countermeasure against this, in the first embodiment, the force sensor 45 is arranged at the tip end portion 12A of the multi-joint arm 12. According to this configuration, the reaction force from the workpiece W is transmitted to the force sensor 45 without passing through the shaft structure portion that connects the arms 13 to each other, so the detection accuracy of the force sensor 45 is improved.

[0045] <Other Embodiments> The present invention is not limited to the embodiments described above and in the drawings, and the following embodiments are also included in the technical scope of the present invention. In the adjustment process of the rotation axis of the drill, the operation of moving the pressing part of the foot away from the surface to be drilled and the operation of pressing the pressing part against the surface to be drilled may be repeated. In the adjustment process of the rotation axis of the drill, the pressing part of the foot may be displaced to reciprocate in the circumferential direction of the opening edge. The force sensor may be positioned closer to the base end than the tip end of the articulated arm. The force sensor may be a sensor other than a 6-axis force sensor (for example, a 3-axis force sensor). As shown in Figure 7, the detection data from the force sensor may be input to the control device via a separately provided PC, rather than to the robot control unit.

[0046] 10... Multi-axis robot 11... Base 12... Multi-joint arm 12A... Tip of the multi-joint arm 13... Arm 14... Joint 15... Servo motor for arm 16... Machining head module 17... Machining head 18... Frame 19... Bottom plate 20... Upright plate 20R... Rear plate 21... Top plate 24... Actuator 25... Male threaded rod 26... Guide groove 27... Servo motor for actuator 28... Lifting member 29... Female threaded hole 30... Spindle 31... Servo motor for spindle 32... Chuck 33... Drill 34... Rotating shaft 35... Communication hole 36... Duct member 37... Cylindrical part 38... Discharge part 40... Foot 41... Opening edge 42... Contact surface 43... Pressing part 45... Force sensor 46... Control device 47... PLC 48... Servo amplifier for actuator 49... Servo amplifier for spindle 50... Robot control unit H... Through hole S... Surface to be drilled W... Workpiece

Claims

1. A machining head module comprising: a drill attached to a multi-joint arm constituting a multi-axis robot, which drills a workpiece while rotating; a foot that is cylindrical in shape concentric with the drill and has an opening edge at its tip that contacts the surface of the workpiece to be drilled; a control device for controlling the machining head; a force sensor for detecting the reaction force when the opening edge presses against the surface to be drilled; and a robot control unit for leveling the reaction force from the surface to be drilled, wherein the robot control unit controls the movement of the multi-joint arm based on the detection information from the force sensor such that the pressing portion of the opening edge against the surface to be drilled is displaced in the circumferential direction and the area of ​​the pressing portion expands in the circumferential direction.

2. The processing head module according to claim 1, wherein the robot control unit controls the movement of the articulated arm so that the pressing portion is always in contact with the surface to be drilled.

3. The machining head module according to claim 1 or 2, wherein the robot control unit controls the movement of the articulated arm so that the pressing portion is displaced in only one direction in the circumferential direction of the opening edge.

4. The machining head module according to claim 1 or claim 2, wherein the force sensor is a 6-axis force sensor.

5. A multi-axis robot comprising: a multi-joint arm having multiple arms connected so as to be relatively displaceable; a drill that drills a workpiece while rotating, the direction of the rotation axis of the drill changes with the movement of the multi-joint arm; a foot that constitutes the machining head, is cylindrical in shape concentric with the drill, and has an opening edge at its tip that contacts the surface of the workpiece to be drilled; a control device that controls the machining head; a force sensor that detects the reaction force when the opening edge presses against the surface to be drilled; and a robot control unit that equalizes the reaction force from the surface to be drilled, wherein the robot control unit controls the movement of the multi-joint arm based on the detection information of the force sensor such that the pressing portion of the opening edge against the surface to be drilled is displaced in the circumferential direction and the area of ​​the pressing portion expands in the circumferential direction.

6. The multi-axis robot according to claim 5, wherein the force sensor is positioned between the tip of the articulated arm and the processing head.

7. A method for adjusting the rotation axis of a machining head, comprising: a multi-joint arm having multiple arms connected so as to be relatively displaceable; a machining head having a drill that drills a workpiece while rotating, wherein the direction of the rotation axis of the drill changes with the movement of the multi-joint arm; a foot constituting the machining head, having a cylindrical shape concentric with the drill, and having an opening edge at its tip that contacts the surface of the workpiece to be drilled; a control device for controlling the machining head; a force sensor for detecting the reaction force when the opening edge presses against the surface to be drilled; and a robot control unit for leveling the reaction force from the surface to be drilled, wherein the robot control unit controls the movement of the multi-joint arm based on the detection information of the force sensor, such that the pressing portion of the opening edge against the surface to be drilled is displaced in the circumferential direction and the area of ​​the pressing portion expands in the circumferential direction.

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