End effector

Abstract

To provide an end effector which contributes to improvement in process tolerance.SOLUTION: An end effector (1) comprises: a base member (21) fixed to a robot arm; a drill unit (3); and an elastic connection member (24). The drill unit (3) includes: a drill (31); a drill support (32) for supporting the drill (31); a power device (34) which moves the drill (31) forward and backward and rotates the same with respect to the drill support (32); and a pressure foot (33) which projects toward a work-piece (W) from the drill support (32). The elastic connection member (24) has such a structure that a plurality of rubber plates and a plurality of rigid plates are laminated between the base member (21) and the drill support (32), and connects the base member (21) and the drill support (32) to each other. A compressive load is applied to the elastic connection member (24) by a compression mechanism (23).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an end effector attached to a robotic arm for processing a workpiece.

Background Art

[0002] As an example of an end effector, the one disclosed in Patent Document 1 below is known. Specifically, Patent Document 1 discloses providing a mechanical compliance mechanism made of an elastic body such as a coil spring between the tip of a robotic arm and the end effector, or in the end effector itself.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When using a mechanical compliance mechanism made of an elastic body as in Patent Document 1 above, depending on the posture of the end effector, for example, the elastic body may deform in an undesirable direction, which may reduce the processing accuracy by the end effector.

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide an end effector that contributes to improving processing accuracy.

Means for Solving the Problems

[0006] As a solution to the above problems, an end effector according to an aspect of the present disclosure is an end effector attached to a robot arm for processing a workpiece, and includes a base member fixed to the robot arm, a drill, a drill support for supporting the drill, a power device for advancing, retracting, and rotating the drill with respect to the drill support, and a pressure foot that protrudes from the drill support toward the workpiece and contacts the workpiece during processing by the drill. A drill unit including: a structure in which a plurality of rubber plates and a plurality of rigid plates having higher rigidity than the rubber plates are laminated in a drill axis direction parallel to the central axis of the drill; an elastic connection member that connects the base member and the drill support to each other; and a compression mechanism that applies a compressive load in the drill axis direction to the elastic connection member.

Effect of the Invention

[0007] According to the present disclosure, it is possible to provide an end effector that contributes to improving processing accuracy.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

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Figure 3B

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Mode for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the end effector of the present disclosure will be described in detail with reference to the drawings. The end effector of the present disclosure is attached to a robot arm for processing a workpiece. The robot arm movably supports the end effector so that the end effector can approach any processing position on the workpiece. The robot arm may be of any type as long as it has such a function, and for example, an articulated robot is suitable.

[0010] (1) First Embodiment FIG. 1 is a schematic diagram showing a working robot including an end effector 1 according to the first embodiment of the present disclosure. The working robot includes a robot arm 100 composed of an articulated robot, and an end effector 1 attached to the tip of the robot arm 100. In the present embodiment, the robot arm 100 includes a first arm portion 101 and a second arm portion 102. The second arm portion 102 is rotatably connected to the tip 101a of the first arm portion 101 via a joint 103. The first arm portion 101 is further rotatably connected to an upstream arm portion via a joint or the like. The end effector 1 is attached to the tip 102a of the second arm portion 102 via a bracket 105. Hereinafter, the tip 102a of the second arm portion 102 is referred to as the arm tip 102a. The arm tip 102a is one end on one side in the arm axis direction Dx, which is the extending direction of the second arm portion 102, and is the end opposite to the joint 103.

[0011] [Configuration of End Effector] FIG. 2 is a front sectional view showing the detailed structure of the end effector 1. The end effector 1 shown in this figure is a tool for performing drilling to form a hole in the workpiece W. The end effector 1 includes a support mechanism 2 attached to the arm tip 102a, and a drill unit 3 supported by the support mechanism 2. The workpiece W is not particularly limited as long as it is an object that requires drilling. For example, it can be a constituent material of a structure such as an aircraft, a railway vehicle, or an automobile. In the present embodiment, the case where the workpiece W is a curved plate is exemplified.

[0012] In the present embodiment, the end effector 1 is attached to the arm tip portion 102a in a posture coaxial with the second arm portion 102. That is, assuming that a straight line including the central axis of the end effector 1, that is, the central axis of the drill 31 described later in the drill unit 3 is the drill axis X1, this drill axis X1 is parallel to the arm axis direction Dx shown in FIG. 1. Therefore, hereinafter, the direction parallel to the drill axis X1 will be referred to as the "drill axis direction Dx" using the same symbol as the arm axis direction Dx. Further, one end side of the drill axis direction Dx and the side close to the arm tip portion 102a is referred to as the "base end side", and the other end side of the drill axis direction Dx and the side far from the arm tip portion 102a is referred to as the "tip side".

[0013] The support mechanism 2 includes a first outer plate 21, a second outer plate 22, a compression mechanism 23, a first elastic connection member 24, and a second elastic connection member 25. The first outer plate 21 and the second outer plate 22 of the present embodiment are plate-like bodies. The first outer plate 21 is fixed to the arm tip portion 102a via a bracket 105. The second outer plate 22 is disposed at a position separated from the first outer plate 21 in the drill axis direction Dx. The first outer plate 21 and the second outer plate 22 are arranged to face each other in the drill axis direction Dx in such a relationship that the second outer plate 22 is located on the tip side of the first outer plate 21. The compression mechanism 23 connects the first outer plate 21 and the second outer plate 22 in a manner that allows the distance between them to be changed. The first elastic connection member 24 elastically connects the first outer plate 21 and the drill unit 3. The second elastic connection member 25 elastically connects the second outer plate 22 and the drill unit 3. Note that the first outer plate 21 corresponds to the "base member" in the present disclosure, the second outer plate 22 corresponds to the "tip side member" in the present disclosure, the first elastic connection member 24 corresponds to the "elastic connection member" in the present disclosure, and the second elastic connection member 25 corresponds to the "tip side elastic connection member" in the present disclosure.

[0014] The compression mechanism 23 includes a plurality of threaded rods 231 extending in the drill axis direction Dx, and a plurality of nuts 232 screwed onto both ends of the threaded rods 231. The number of the threaded rods 231 is not particularly limited as long as it is two or more, but for example, three or four are preferable. The threaded rods 231 are arranged to be distributed at equal intervals along a circle centered on the drill axis X1 in a plan view seen from one side in the drill axis direction Dx. Each threaded rod 231 is attached so as to penetrate through each peripheral edge of the first outer plate 21 and the second outer plate 22. The nuts 232 are respectively screwed onto both ends of the threaded rods 231 located outside the two outer plates 21, 22.

[0015] The nut 232 is a configuration for adjusting the axial force of the threaded rod 231. That is, when the nut 232 is rotated in the tightening direction, the axial force of the threaded rod 231 increases, and when the nut 232 is rotated in the loosening direction, the axial force of the threaded rod 231 decreases. Such adjustment of the axial force of the threaded rod 231 leads to adjustment of the compression load applied to the first elastic connection member 24 and the second elastic connection member 25.

[0016] The first elastic connection member 24 includes a plurality of columnar first laminated rubbers 241. The first laminated rubbers 241 are arranged at equal intervals along a circle centered on the drill axis X1 in a plan view seen from one side in the drill axis direction Dx. Note that the first laminated rubber 241 corresponds to the "first element elastic body" in the present disclosure.

[0017] FIG. 3A is a cross-sectional view showing the structure of the first laminated rubber 241. As shown in this figure, the first laminated rubber 241 has a plurality of rubber plates 245 and a plurality of rigid plates 246 laminated alternately. In the example of FIG. 3A, five rubber plates 245 and six rigid plates 246 are laminated alternately. Each rubber plate 245 is a disc-shaped body made of rubber having a certain thickness. Each rigid plate 246 is a disc-shaped body made of metal or resin having a certain thickness. In other words, the rubber plate 245 is made of a material that is more easily elastically deformed than the rigid plate 246, and the rigid plate 246 is made of a material that is more rigid than the rubber plate 245. The thickness of the rubber plate 245 can be set as appropriate, but it is preferably larger than the thickness of the rigid plate 246. The rubber plate 245 and the rigid plate 246 are bonded to each other via an adhesive or the like.

[0018] Let the lamination direction of the rubber plate 245 and the rigid plate 246 be the longitudinal direction D1, and the direction orthogonal to the longitudinal direction D1 be the lateral direction D2. The first laminated rubber 241 having the above structure has high rigidity in the longitudinal direction D1 and low rigidity in the lateral direction D2. This means that, as shown in FIG. 3B, the first laminated rubber 241 is difficult to deform in the longitudinal direction D1 and is easy to deform in the lateral direction D2. In other words, the first laminated rubber 241 has a selective compliance structure that is easy to deform only in a specific direction, here the lateral direction D2. Note that the longitudinal direction D1 of the first laminated rubber 241 corresponds to the drill axis direction Dx in the usage state of the end effector 1 shown in FIG. 2.

[0019] The structure of the second elastic connection member 25 is also the same as that of the first elastic connection member 24. That is, the second elastic connection member 25 includes a plurality of columnar second laminated rubbers 251 distributed at equal intervals along a circle centered on the drill axis X1. As shown in FIGS. 3A and 3B, each second laminated rubber 251 has a plurality of rubber plates 245 and a plurality of rigid plates 246 laminated alternately, and is easy to deform in the lateral direction D2. Note that the second laminated rubber 251 corresponds to the "second element elastic body" in the present disclosure.

[0020] The number of each of the first laminated rubbers 241 and the second laminated rubbers 251 may be two or more, preferably three or four. In the present embodiment, as shown in FIG. 4, three first laminated rubbers 241 and three second laminated rubbers 251 are respectively prepared. That is, the first elastic connection member 24 is composed of three first laminated rubbers 241 arranged at positions that trisect a circle centered on the drill shaft X1, and the second elastic connection member 25 is composed of three second laminated rubbers 251 arranged at positions that trisect the same circle.

[0021] As shown in FIG. 2, the drill unit 3 includes a drill 31, a drill support 32, a pressure foot 33, and a power device 34. The drill 31 is a tool for cutting the workpiece W during the drilling process of the workpiece W. The drill support 32 supports the drill 31 so as to be movable forward and backward and rotatable. In the present embodiment, the pressure foot 33 is a cylindrical body that surrounds the drill 31 and is pressed against the workpiece W when the drill processes the workpiece W. Note that the shape of the pressure foot 33 is not limited to this. The pressure foot 33 may have, for example, a shape having a plurality of protrusions arranged to surround the drill 31. The power device 34 is a device for moving the drill 31 forward and backward and rotating it with respect to the drill support 32.

[0022] The drill support 32 has a first inner plate 321 arranged on the tip side of the first outer plate 21, a second inner plate 322 arranged on the base end side of the second outer plate 22, and a plurality of guide shafts 323 provided between both inner plates 321 and 322.

[0023] The first inner plate 321 is a plate-like body. The first inner plate 321 of the present embodiment is smaller than the first outer plate 21 and fits inside a plurality of threaded rods 231. Note that the shape of the first inner plate 321 and the size relationship between the first inner plate 321 and the first outer plate 21 are not particularly limited. The first inner plate 321 may have a shape that does not interfere with the plurality of threaded rods 231. This also applies to the second inner plate 322.

[0024] The first inner plate 321 is arranged to face the first outer plate 21 from the tip side with the first elastic connection member 24 interposed therebetween. The three first laminated rubbers 241 constituting the first elastic connection member 24 connect the first inner plate 321 and the first outer plate 21 to each other at positions that trisect a circle centered on the drill axis X1, that is, at three positions corresponding to the vertices of an equilateral triangle in plan view. That is, at the above three positions, the most proximal rigid plate 246 in each first laminated rubber 241 is joined to the first outer plate 21, and the most distal rigid plate 246 in each first laminated rubber 241 is joined to the first inner plate 321. As a result, the first outer plate 21 and the first inner plate 321 separated in the drill axis direction Dx are elastically connected via the first elastic connection member 24. In other words, the first elastic connection member 24 or each first laminated rubber 241 has a structure in which a plurality of rubber plates 245 and a plurality of rigid plates 246 are laminated between the first outer plate 21 and the first inner plate 321. Note that the rigid plate 246 and each plate 21, 321 can be joined by an appropriate method such as welding, adhesion, or bolt fastening. This also applies to the second elastic connection member 25 or the second laminated rubber 251.

[0025] The second inner plate 322 is a plate-like body. The second inner plate 322 is slightly smaller than the second outer plate 22 and fits inside a plurality of threaded rods 231. The second inner plate 322 is arranged to face the second outer plate 22 from the base end side with the second elastic connection member 25 interposed therebetween. The three second laminated rubbers 251 constituting the second elastic connection member 25 connect the second inner plate 322 and the second outer plate 22 to each other at three locations that trisect a circle centered on the drill axis X1, that is, at three locations corresponding to the vertices of an equilateral triangle in plan view. That is, at the above three locations, the most base-end rigid plate 246 in each second laminated rubber 251 is coupled to the second inner plate 322, and the most tip-end rigid plate 246 in each second laminated rubber 251 is coupled to the second outer plate 22. Thereby, the second outer plate 22 and the second inner plate 322 separated in the drill axis direction Dx are elastically connected via the second elastic connection member 25. In other words, the second elastic connection member 25 or each second laminated rubber 251 has a structure laminated between the second outer plate 22 and the second inner plate 322. In this embodiment, the second inner plate 322 has a stepped shape in which the region inside the second elastic connection member 25 or the second laminated rubber 251 protrudes toward the tip end side more than the outer region.

[0026] In this embodiment, a plurality of first laminated rubbers 241 are interposed between the first outer plate 21 and the first inner plate 321, and a plurality of second laminated rubbers 251 are interposed between the second outer plate 22 and the second inner plate 322. A compressive load in the drill axis direction Dx caused by the compression mechanism 23 acts on each of the first laminated rubber 241 and the second laminated rubber 251. That is, the compression mechanism 23 pulls the second outer plate 22 toward the side closer to the first outer plate 21, that is, the proximal end side, by the axial force of the screw rod 231 according to the tightening force of the nut 232. As a result, a compressive load in the drill axis direction Dx acts on the first laminated rubber 241 between the first outer plate 21 and the first inner plate 321, and a compressive load in the drill axis direction Dx acts on the second laminated rubber 251 between the second outer plate 22 and the second inner plate 322. In this embodiment, the compressive load in the drill axis direction Dx is a load that compresses each laminated rubber 241, 251 in the lamination direction of the rubber plate 245 and the rigid plate 246. In other words, the compression mechanism 23 is configured to compress each laminated rubber 241, 251 in the lamination direction via the drill support 32 by connecting the two outer plates 21, 22 so that a load in the direction of pulling the second outer plate 22 toward the first outer plate 21 is generated. Such a compressive load on each of the laminated rubbers 241, 251 can be adjusted by adjusting the tightening force of the nut 232.

[0027] The plurality of guide shafts 323 are each a rod-shaped body extending in the drill axis direction Dx, and connect the first inner plate 321 and the second inner plate 322 to each other. A slide plate 349 of a spindle motor 341, which will be described later, is slidably externally inserted into each guide shaft 323. The guide shaft 323 guides the forward and backward movement of the drill 31 with respect to the drill support 32.

[0028] The power unit 34 includes a spindle motor 341, a feed motor 342, and a ball screw shaft 343. The spindle motor 341 rotationally drives the drill 31. The feed motor 342 drives the drill 31 to move forward and backward together with the spindle motor 341. The ball screw shaft 343 converts the rotation of the feed motor 342 into the forward and backward movement of the spindle motor 341.

[0029] FIG. 5 is a front view showing the power unit 34 enlarged. As shown in this figure, the spindle motor 341 includes a motor case 345, a spindle 346, a stator 347, and a rotor 348. The motor case 345 is a cylindrical body extending in the drill axis direction Dx. The spindle 346 is disposed at the center of the motor case 345. The stator 347 is fixed to the inner peripheral surface of the motor case 345. The rotor 348 is rotatably accommodated inside the stator 347.

[0030] The spindle 346 is rotatably supported inside the motor case 345 via bearings or the like. The drill 31 is integrally coupled to the tip of the spindle 346. The spindle 346 and the drill 31 are coaxially arranged along the drill axis X1.

[0031] The rotor 348 is arranged to surround the spindle 346 and is fixed to the spindle 346. The rotor 348 rotates relative to the stator 347 in response to energization. When the rotor 348 rotates, the spindle 346 and the drill 31 rotate together with the rotor 348 around the drill axis X1.

[0032] A pair of ring-shaped slide plates 349 are fixed to the motor case 345. Both slide plates 349 are provided so as to project radially from two locations in the drill axis direction Dx of the motor case 345. As shown in FIG. 2, guide shafts 323 are inserted through a plurality of locations in the circumferential direction of each slide plate 349. The spindle motor 341 including the slide plate 349 is slidably supported along the guide shaft 323 in the drill axis direction Dx.

[0033] The feed motor 342 is coaxially arranged on the proximal end side of the spindle motor 341 and is supported on the first inner plate 321. In the present embodiment, an insertion hole H1 for receiving the proximal end portion of the feed motor 342 protruding toward the proximal end side from the first outer plate 21 is formed in the central portion of the first outer plate 21.

[0034] The ball screw shaft 343 extends from the feed motor 342 toward the distal end side and is arranged so as to penetrate the first inner plate 321 and reach the spindle motor 341. As shown in FIG. 5, a ball screw nut 344 that engages with the ball screw shaft 343 is built into the proximal end portion of the spindle motor 341.

[0035] When the ball screw shaft 343 is rotationally driven in the forward rotation direction by the feed motor 342, the ball screw nut 344 is screw-fed toward the distal end side by the ball screw shaft 343 rotating in the same direction, and thereby the spindle motor 341 moves toward the distal end side, that is, advances. Conversely, when the ball screw shaft 343 is rotationally driven in the reverse rotation direction by the feed motor 342, the ball screw nut 344 is screw-fed toward the proximal end side by the ball screw shaft 343 rotating in the same direction, and thereby the spindle motor 341 moves toward the proximal end side, that is, retreats.

[0036] As shown in FIG. 2, the pressure foot 33 is fixed to the second inner plate 322 and protrudes from the central portion of the second inner plate 322 toward the distal end side. The distal end portion of the spindle motor 341 and the drill 31 are accommodated inside the pressure foot 33. An insertion hole H2 for receiving the distal end portion of the spindle motor 341 and the pressure foot 33 protruding toward the distal end side from the second outer plate 22 is formed in the central portion of the second outer plate 22.

[0037] Here, as shown in FIG. 4, a polyhedron formed by connecting the centers of gravity C1 of the plurality of first laminated rubbers 241 constituting the first elastic connection member 24 and the centers of gravity C2 of the plurality of second laminated rubbers 251 constituting the second elastic connection member 25 with virtual straight lines is defined as a virtual polyhedron PH1. Specifically, the centers of gravity C1 of the first laminated rubbers 241 are connected annularly around the drill axis X1, the centers of gravity C2 of the second laminated rubbers 251 are connected annularly around the drill axis X1, and a straight line is extended from each center of gravity C1 of the first laminated rubbers 241 along the drill axis X1 to connect with the corresponding centers of gravity C2 of the second laminated rubbers 251 to form the virtual polyhedron PH1. In this embodiment, three first laminated rubbers 241 and three second laminated rubbers 251 are respectively prepared. Therefore, the virtual polyhedron PH1 is a triangular prism. In this embodiment, the center of gravity C0 of the drill unit 3 is located inside this virtual polyhedron PH1. That is, in this embodiment, the laminated rubbers 241 and 251 are dispersedly arranged such that the center of gravity C0 of the drill unit 3 is included inside the virtual polyhedron PH1 determined by the centers of gravity C1 and C2 of all the laminated rubbers 241 and 251. Note that the center of gravity C0 of the drill unit 3 is the combined center of gravity of the drill 31, the drill support 32, the pressure foot 33, and the power unit 34, which are the components of the drill unit 3.

[0038] More specifically, in this embodiment, the center of gravity C0 of the drill unit 3 is located at the geometric center of the virtual polyhedron PH1. Since the structures of the three first laminated rubbers 241 and the three second laminated rubbers 251 are all the same, the geometric center of the virtual polyhedron PH1 is equivalent to the combined center of gravity of all the laminated rubbers 241 and 251. That is, in this embodiment, the center of gravity C0 of the drill unit 3 coincides with the combined center of gravity of the first elastic connection member 24 and the second elastic connection member 25. Note that the coincidence of the centers of gravity here includes not only the case where the two centers of gravity completely coincide but also the case where there is a deviation caused by manufacturing errors or the like between the two centers of gravity.

[0039] FIG. 6 is a view corresponding to FIG. 2 showing a situation where a drilling process is performed on a workpiece W using the end effector 1 as described above. As shown in this figure, during the drilling process, the drill 31 is rotationally driven with the tip of the pressure foot 33 pressed against the workpiece W. Specifically, the robot arm 100 moves the end effector 1 toward the workpiece W so that the tip of the pressure foot 33 contacts, that is, abuts around the target machining position Pa of the workpiece W. Further, the robot arm 100 holds the end effector 1 so that the pressure foot 33 is pressed against the workpiece W with a desired pressing force. Thereby, the drill 31 is positioned so that its tip abuts on the target machining position Pa. Further, the drill 31 is rotationally driven by a spindle motor 341.

[0040] In the above state, an operation of pushing out the drill 31 toward the tip side is performed. That is, as shown in FIG. 7, the feed motor 342 is driven in the forward rotation direction and the spindle motor 341 is screw-fed toward the tip side, whereby the drill 31 is pushed out toward the tip side. This operation is performed until the drill 31 penetrates the workpiece W. Thereby, a hole having a diameter corresponding to the outer diameter of the drill 31 is formed at the target machining position Pa of the workpiece W.

[0041] [Function and Effect] As described above, the end effector 1 of the first embodiment includes a support mechanism 2 including a first outer plate 21 fixed to the arm tip portion 102a of the robot arm 100 and a second outer plate 22 facing the first outer plate 21, and a drill unit 3 including a drill support 32 disposed between both outer plates 21 and 22 and a drill 31 supported by the drill support 32. Further, a first elastic connection member 24 that elastically connects both is disposed between the first outer plate 21 and the first inner plate 321 of the drill support 32. In addition, a second elastic connection member 25 that elastically connects both is disposed between the second outer plate 22 and the second inner plate 322 of the drill support 32. Furthermore, the support mechanism 2 has a compression mechanism 23 that applies a compressive load in the drill axis direction Dx to the first elastic connection member 24 and the second elastic connection member 25. According to such a configuration, the machining accuracy when performing drilling on the workpiece W using the end effector 1 can be improved.

[0042] Specifically, the first elastic connection member 24 and the second elastic connection member 25 are each composed of a plurality of laminated rubbers 241 and 251, and each laminated rubber 241 and 251 has a structure in which a plurality of rubber plates 245 and a plurality of rigid plates 246 are laminated in the drill axis direction Dx. Such elastic connection members 24 and 25 or laminated rubbers 241 and 251 are likely to deform only in a direction orthogonal to the drill axis direction Dx, that is, in the shear direction. Therefore, according to the first embodiment in which these elastic connection members 24 and 25 are interposed between the support mechanism 2 and the drill support 32, when the pressure foot 33 is brought into contact with the workpiece W and pressurized during the hole drilling process of drilling a hole in the workpiece W with the drill 31, even if the robot arm 100 receives a reaction force and bends and deforms, the influence due to the bending deformation can be absorbed by the deformation of the elastic connection members 24 and 25. Thereby, it is possible to prevent the relative position between the drill 31 and the workpiece W from shifting, and the positional relationship between the drill 31 and the workpiece W can be maintained well.

[0043] Suppose that the elastic connection members 24 and 25 do not exist. For example, when the pressure foot 33 is brought into contact with the workpiece W and pressed, the reaction force from the workpiece W acts on the robot arm 100 via the end effector 1. When the robot arm 100 deflects and deforms accordingly, the behavior of the drill 31 becomes unstable, and the center position of the drill 31 may shift with respect to the workpiece W. That is, due to the deflection and deformation of the robot arm 100, a load is generated that attempts to shift the relative position between the drill 31 and the workpiece W, and as a result, the center position of the drill 31 may deviate from the target machining position Pa. On the other hand, according to the first embodiment in which the elastic connection members 24 and 25 exist, even if the robot arm 100 deflects and deforms as described above, the elastic connection members 24 and 25 deform in the shear direction as shown in FIG. 8, so that the above-described load can be released while maintaining the positional relationship between the drill 31 and the workpiece W. Thereby, problems due to the positional deviation of the drill 31 described above, such as a problem that the hole diameter expands, can be suppressed, and the accuracy of the hole drilling process by the drill 31 can be improved.

[0044] Further, the elastic connection members 24 and 25 are difficult to deform in the drill axis direction Dx and receive a compressive load in the drill axis direction Dx from the compression mechanism 23. Therefore, it is difficult for a tensile force to be generated in the elastic connection members 24 and 25 regardless of the posture of the end effector 1. Thereby, the axial position accuracy of the drill 31 can be ensured favorably, and the workability can be improved. Further, this also makes it possible to prevent the elastic connection members 24 and 25 from being worn due to receiving a tensile force.

[0045] Also, in the first embodiment, the compression mechanism 23 includes a threaded rod 231 that penetrates both the first outer plate 21 and the second outer plate 22, and nuts 232 that are screwed onto the threaded rod 231 on the outer sides of both outer plates 21 and 22. According to such a configuration, an axial force that draws the second outer plate 22 toward the first outer plate 21 is generated in the threaded rod 231 when the nuts 232 are tightened. By means of this axial force, a compressive load can be applied to the elastic connection members 24 and 25, respectively. In other words, in the first embodiment, between the first outer plate 21 and the second outer plate 22 connected via the compression mechanism 23, the first elastic connection member 24 on the proximal side and the second elastic connection member 25 on the distal side are sandwiched via the drill support 32. Therefore, these two elastic connection members 24 and 25 can be collectively compressed using the same compression mechanism 23.

[0046] Also, in the first embodiment, the center of gravity C0 of the drill unit 3 is included inside a virtual polyhedron PH1 formed by connecting the centers of gravity C1 of the plurality of first laminated rubbers 241 constituting the first elastic connection member 24 and the centers of gravity C2 of the plurality of second laminated rubbers 251 constituting the second elastic connection member 25. According to such a configuration, for example, as shown in FIG. 9, even when pressurization is performed on the workpiece W via the pressure foot 33 in a posture where the drill axis X1 is inclined with respect to the vertical line Z, each laminated rubber 241, 251 bears only the load in the drill axis direction Dx and does not bear a bending load. Also, in this case, the load in the drill axis direction Dx is evenly distributed to each laminated rubber 241, 251. In other words, for example, it is less likely that a load input in the drill axis direction Dx will concentrate and occur in a specific one of each of the laminated rubbers 241, 251. Due to these actions, it is possible to prevent problems such as peeling from occurring in each laminated rubber 241, 251, and the performance of each laminated rubber 241, 251 can be maintained over a long period. Note that FIG. 9 shows an example of performing drilling in a posture where the drill axis X1 is orthogonal to the vertical line Z, that is, a posture where the drill axis X1 faces the horizontal direction. However, the same effect as described above can be similarly obtained, for example, when performing drilling in a posture where the drill axis X1 intersects the vertical line Z at an angle of less than 90 degrees.

[0047] In particular, in the first embodiment, the center of gravity C0 of the drill unit 3 coincides with the centroid of the virtual polyhedron PH1. That is, the combined center of gravity of the total six laminated rubbers 241 and 251 that make up the first elastic connection member 24 and the second elastic connection member 25 coincides with the center of gravity C0 of the drill unit 3. Therefore, the above-described effects can be enhanced more, and the performance of each laminated rubber 241 and 251 can be maintained well.

[0048] [Modification Example] In the first embodiment, an example in which the first elastic connection member 24 and the second elastic connection member 25 are each composed of a plurality of laminated rubbers 241 and 251 separated from each other has been described. However, the shape of the elastic connection member is not limited to this. For example, as shown in FIG. 10, the first elastic connection member 64 and the second elastic connection member 65 may each be formed in a cylindrical shape. Specifically, the first elastic connection member 64 and the second elastic connection member 65 each have a ring-shaped cross section centered on the drill axis X1 and exhibit a short cylindrical shape having a predetermined thickness in the drill axis direction Dx. In this case, the center of gravity C0 of the drill unit 3 is included inside a virtual cylinder PH2 defined between the first elastic connection member 64 and the second elastic connection member 65. Here, the virtual cylinder PH2 is a cylinder formed by connecting a pitch circle PC that bisects the ring-shaped end face of the first elastic connection member 64 in the radial direction and a similar pitch circle of the second elastic connection member 65.

[0049] In the above-described first embodiment, a compression mechanism 23 including a screw rod 231 and a nut 232 is used to apply a compression load to each elastic connection member 24 and 25. However, similar to the compression mechanism 43 of the second embodiment described later, a mechanism including a spring may be used to apply a compression load to each elastic connection member 24 and 25.

[0050] (2) Second Embodiment In the first embodiment, the drill support 32 is supported via the first elastic connection member 24 and the second elastic connection member 25 inside the support mechanism 2 including the first outer plate 21 and the second outer plate 22 facing the drill axis direction Dx. However, the structure for supporting the drill support 32 is not limited to this. Hereinafter, an example in which the support structure of the drill support is changed will be described as the second embodiment.

[0051] FIG. 11 is a front cross-sectional view showing the end effector 1A according to the second embodiment of the present disclosure. The end effector 1A shown in this figure includes a support mechanism 4 attached to the arm tip portion 102a and a drill unit 5 supported by the support mechanism 4.

[0052] The support mechanism 4 includes a base plate 41, an elastic connection member 44, and a compression mechanism 43. The base plate 41 is fixed to the arm tip portion 102a via a bracket 105. The elastic connection member 44 elastically connects the base plate 41 and the drill unit 5. The compression mechanism 43 applies a compressive load to the elastic connection member 44. Note that the base plate 41 corresponds to the "base member" in the present disclosure.

[0053] The base plate 41 has a flat plate portion 411 coupled to the bracket 105 and a peripheral convex portion 412 protruding from the peripheral edge portion of the flat plate portion 411 toward the tip side.

[0054] The elastic connection member 44 is composed of a plurality of cylindrical laminated rubbers 441. Each laminated rubber 441 connects the peripheral convex portion 412 of the base plate 41 and the peripheral edge portion of a first plate 521 (to be described later) of the drill unit 5 to each other. The laminated rubber 441 has the same structure as the first laminated rubber 241 or the second laminated rubber 251 of the first embodiment. That is, the laminated rubber 441 has a structure in which a plurality of rubber plates 245 and a plurality of rigid plates 246 shown in FIGS. 3A and 3B are laminated between the base plate 41 and the first plate 521. Such a laminated rubber 441 has the characteristics that the rigidity in the longitudinal direction D1 parallel to the drill axis direction Dx, that is, the lamination direction, is high, and the rigidity in the lateral direction D2 orthogonal to the drill axis direction Dx is low. The number of the laminated rubbers 441 can be set as appropriate, but in the second embodiment, as shown in FIG. 12, three laminated rubbers 441 are prepared. These three laminated rubbers 441 are arranged at positions that trisect a circle centered on the drill axis X1 in a plan view seen from one side in the drill axis direction Dx. Note that the laminated rubber 441 corresponds to the "element elastic body" in the present disclosure.

[0055] The compression mechanism 43 includes a plurality of first protrusion pieces 431, a plurality of second protrusion pieces 432, and a plurality of springs 433. The plurality of first protrusion pieces 431 are fixed to the outer peripheral surface of the base plate 41. The plurality of second protrusion pieces 432 are fixed to the outer peripheral surface of the first plate 521 of the drill unit 5. The plurality of springs 433 are respectively attached between the plurality of first protrusion pieces 431 and the plurality of second protrusion pieces 432. The spring 433 is attached in a tension state to generate a load in a direction that reduces the distance between the first protrusion piece 431 and the second protrusion piece 432. In the second embodiment, corresponding to the three laminated rubbers 441 described above, three sets of combinations of the protrusion pieces 431, 432 and the springs 433 are prepared.

[0056] The drill unit 5 includes a drill 51, a drill support 52, a pressure foot 53, and a power unit 54. The drill 51 is a tool for cutting a workpiece W. The drill support 52 supports the drill 51 so as to be movable forward and backward and rotatable. The pressure foot 53 is, for example, a cylindrical body provided around the drill 51. The power unit 54 moves the drill 51 forward and backward and rotates it.

[0057] The drill support 52 has a first plate 521, a second plate 522, and a plurality of guide shafts 523. The first plate 521 is supported by the base plate 41 via an elastic connection member 44 at a position away from the base plate 41 in the drill axis direction Dx. The second plate 522 is disposed on the tip side with respect to the first plate 521. The plurality of guide shafts 523 connect the first plate 521 and the second plate 522 in the drill axis direction Dx.

[0058] The pressure foot 53 is fixed to the second plate 522 and protrudes from the central portion of the second plate 522 toward the tip side.

[0059] The power unit 54 has a spindle motor 541, a feed motor 542, and a conversion mechanism 543. The spindle motor 541 rotationally drives the drill 51. The feed motor 542 drives the drill 51 forward and backward together with the spindle motor 541. The conversion mechanism 543 converts the rotation of the feed motor 542 into the forward and backward movement of the spindle motor 541.

[0060] The spindle motor 541 has the same structure as the spindle motor 341 of the first embodiment. That is, the spindle motor 541 has a cylindrical motor case extending in the drill axis direction Dx, a spindle disposed at the center thereof, and a rotating element such as a rotor that rotates the spindle. The drill 51 is integrally coupled to the tip of the spindle.

[0061] A ring-shaped slide plate 549 is attached to the spindle motor 541. Guide shafts 523 are inserted through a plurality of circumferential locations on the slide plate 549. The spindle motor 541 including the slide plate 549 is slidably supported along the guide shaft 523 in the drill axis direction Dx. Further, a ball screw nut that engages with a ball screw shaft 544 described later is built into the slide plate 549.

[0062] The feed motor 542 is attached to the outer peripheral surface of the base plate 41. The feed motor 542 has a rotatable motor shaft 542a that protrudes toward the tip side.

[0063] The conversion mechanism 543 includes, for example, a plurality of ball screw shafts 544 extending in the drill axis direction Dx for screw-feeding the slide plate 549, and a transmission member 545 that interlocks and connects each ball screw shaft 544 and the motor shaft 542a. The type of the transmission member 545 is not particularly limited, and examples thereof include a combination of a belt and a pulley, a universal joint, and the like.

[0064] As shown in FIG. 13, when the feed motor 542 is driven and the motor shaft 542a rotates, the rotation is transmitted to the ball screw shaft 544 via the transmission member 545, and the ball screw shaft 544 rotates. When the ball screw shaft 544 rotates, the slide plate 549 is screw-fed, and accordingly, the spindle motor 541 and the drill 51 move forward and backward.

[0065] In the plan view shown in FIG. 12, a polygon formed by connecting the centers of gravity C3 of the plurality of laminated rubbers 441 that constitute the elastic connection member 44 is defined as a virtual polygon PG. Specifically, the centers of gravity C3 of the plurality of laminated rubbers 441 are annularly connected around the drill axis X1 to form the virtual polygon PG. In the second embodiment, three laminated rubbers 441 are provided. Therefore, the virtual polygon PG is a triangle. In the second embodiment, the center of gravity C0 of the drill unit 5 is located inside the virtual polygon PG. That is, in the second embodiment, in the plan view, the laminated rubbers 441 are dispersedly arranged so that the center of gravity C0 of the drill unit 5 is included inside the virtual polygon PG determined from the centers of gravity C3 of the respective laminated rubbers 441.

[0066] As described above, in the second embodiment, the base plate 41 and the drill support 52 are elastically connected via the elastic connection member 44, and a compressive load in the drill axis direction Dx is applied to the elastic connection member 44 from the compression mechanism 43. Thereby, similarly to the first embodiment, the accuracy of the hole drilling process by the drill 51 can be improved. Also, in the configuration of the second embodiment, it is possible to prevent the elastic connection members 24 and 25 from being damaged by receiving a tensile force.

[0067] In particular, in the second embodiment, the elastic connection member 44 is disposed between the base plate 41 and the first plate 521 of the drill support 52, and the two plates 41 and 521 are connected by the compression mechanism 43 so that a load in the direction of pulling the first plate 521 toward the base plate 41 is generated. According to such a configuration, it is possible to apply a compressive load to the elastic connection member 44 while shortening the dimension of the end effector 1A in the drill axis direction Dx.

[0068] Further, in the second embodiment, in a plan view seen from one side in the drill axis direction Dx, the center of gravity C0 of the drill unit 3 is included inside a virtual polygon PG formed by connecting the centers of gravity C3 of the plurality of laminated rubbers 441 constituting the elastic connection member 44. According to such a configuration, when pressure is applied to the workpiece W via the pressure foot 33 during drilling, the laminated rubber 441 bears only the load in the drill axis direction Dx and does not bear the bending load. Also, in this case, the load in the drill axis direction Dx is evenly distributed to each laminated rubber 441. In other words, for example, it is less likely that the load input in the drill axis direction Dx will concentrate and occur specifically in each of the laminated rubbers 441. Due to these actions, it is possible to prevent problems such as peeling from occurring in the laminated rubber 441.

[0069] In the second embodiment, an example in which the elastic connection member 44 is composed of a plurality of laminated rubbers 441 separated from each other has been described. However, the elastic connection member 44 may be an integral elastic connection member having a short cylindrical shape similar to the modified example shown in FIG. 10.

[0070] Also, in the second embodiment, the ball screw shaft 544 for advancing and retracting the drill 51 and the spindle motor 541 and the motor shaft 542a of the feed motor 542 attached to the base plate 41 are interlocked and connected via the transmission member 545. However, the method of transmitting the driving force to the ball screw shaft 544 is not limited to this. For example, a motor that directly rotationally drives the ball screw shaft 544 may be attached to the first plate 521 of the drill support 52.

[0071] (3) Third Embodiment The plurality of laminated rubbers 241, 251 constituting the elastic connection members 24, 25 of the first embodiment and the plurality of laminated rubbers 441 constituting the elastic connection member 44 of the second embodiment all had a structure including a plurality of rubber plates 245 and a plurality of rigid plates 246 laminated in the drill axis direction Dx. However, the lamination direction of the rubber plates and the rigid plates does not necessarily have to be parallel to the drill axis direction Dx. Hereinafter, an example in which the lamination direction of the rubber plates and the rigid plates is non-parallel to the drill axis direction Dx will be described as the third embodiment.

[0072] FIG. 14 is a front cross-sectional view showing the end effector 1B according to the third embodiment of the present disclosure. The end effector 1B shown in this figure includes a support mechanism 6 attached to the arm tip portion 102a, and a drill unit 7 supported by the support mechanism 6.

[0073] The support mechanism 6 includes a first base member 61, a second base member 62, a first elastic connection member 64, a second elastic connection member 65, a first compression mechanism 66, and a second compression mechanism 67. The first base member 61 is fixed to the arm tip portion 102a via a bracket 105. The second base member 62 is disposed on the tip side of the first base member 61. The first elastic connection member 64 elastically connects the first base member 61 and the second base member 62. In other words, the second base member 62 is fixed to the arm tip portion 102a or the robot arm 102 via the first elastic connection member 64 and the first base member 61. The second elastic connection member 65 elastically connects the second base member 62 and the drill unit 7. The first compression mechanism 66 applies a compression load to the first elastic connection member 64. The second compression mechanism 67 applies a compression load to the second elastic connection member 65. Note that the second base member 62 corresponds to the "base member" in the present disclosure.

[0074] The drill unit 7 includes a drill 71, a drill support 72, a pressure foot 73, and a power unit 74. These elements respectively correspond to the drill 51, the drill support 52, the pressure foot 53, and the power unit 53 in the second embodiment. In particular, since the drill 71 and the pressure foot 73 of the third embodiment are the same as the drill 51 and the pressure foot 53 of the second embodiment, the other elements, that is, the drill support 72 and the power unit 74, will be described below.

[0075] The drill support 72 supports the drill 71 so that it can move forward and backward and rotate. Specifically, the drill support 72 has a first plate 721, a second plate 724, and a plurality of guide shafts 725. The first plate 721 is supported by the second base member 62 via an elastic connecting member 65 at a position away from the second base member 62 in the drill axis direction Dx. The first plate 721 has a central portion 722 that is U-shaped with an opening toward the tip side in the cross-sectional view of FIG. 14, and a flange portion 723 that extends from the periphery of the central portion 722 while inclining toward the tip side and radially outward. The second plate 724 is formed in a flat plate shape and is disposed on the tip side of the central portion 722 of the first plate 721. The plurality of guide shafts 725 connect the central portion 722 of the first plate 721 and the second plate 724 in the drill axis direction Dx.

[0076] The flange portion 723 of the first plate 721 has an inclined outer peripheral surface 723a. The inclined outer peripheral surface 723a faces, with a distance therebetween, an inclined inner peripheral surface 622a (described later) of the second base member 62. The inclined outer peripheral surface 723a is an inclined surface that is not parallel to the drill axis direction Dx when viewed in a direction shown in FIG. 14 that is perpendicular to the drill axis X1, in other words, an inclined surface that intersects with the drill axis X1 when viewed in the same direction. The inclined outer peripheral surface 723a is inclined so as to move away from the drill axis X1 as it approaches the tip side.

[0077] The power unit 74 advances and retreats the drill 71 and rotates it relative to the drill support 72. Specifically, the power unit 74 has a spindle motor 741 that rotates the drill 71, a feed motor 742 that drives the drill 71 to advance and retreat together with the spindle motor 741, and a conversion mechanism 743 that converts the rotation of the feed motor 742 into the advance and retreat movement of the spindle motor 741. The conversion mechanism 743 has a plurality of ball screw shafts 744 extending in the drill axial direction Dx, and a transmission member 745 that interlocks and connects each ball screw shaft 744 to a motor shaft 742a of the feed motor 742. Each ball screw shaft 744 is screwed into a slide plate 749 attached to the spindle motor 741 so that the slide plate 749 can be screwed. A plurality of guide shafts 725 are inserted into the peripheral portion of the slide plate 749.

[0078] The feeding operation of the drill 71 by the power unit 74 as described above is the same as that of the power unit 54 in the second embodiment. That is, when the feeding motor 742 is driven and the motor shaft 742a rotates, the rotation is transmitted to the ball screw shaft 744 via the transmission member 745, and the ball screw shaft 744 rotates. When the ball screw shaft 744 rotates, the slide plate 749 is screw-fed, and accordingly, the spindle motor 741 and the drill 71 move forward and backward.

[0079] Next, a more detailed structure of the support mechanism 6 will be described. As described above, the support mechanism 6 includes the first and second base members 61, 62, the first and second elastic connection members 64, 65, and the first and second compression mechanisms 66, 67. The details of each element are as follows.

[0080] The first base member 61 has a flat plate portion 611 coupled to the bracket 105 and a peripheral convex portion 612 protruding from the peripheral edge of the flat plate portion 611 toward the tip side.

[0081] The second base member 62 has a flat plate portion 621 connected to the peripheral convex portion 612 of the first base member 61 via the first elastic connection member 64 and a peripheral convex portion 622 protruding from the peripheral edge of the flat plate portion 621 toward the tip side. The inner peripheral surface of the peripheral convex portion 622 is an inclined inner peripheral surface 622a that is non-parallel to the drill axis direction Dx in the direction view shown in FIG. 14 perpendicular to the drill axis X1. The inclined inner peripheral surface 622a is inclined so as to be farther from the drill axis X1 toward the tip side. In other words, the inclined inner peripheral surface 622a is inclined so as to extend from the peripheral edge of the flat plate portion 621 toward the tip side and in the radially outward direction.

[0082] The first elastic connection member 64 has the same structure as the elastic connection members 24 and 25 of the first embodiment or the elastic connection member 44 of the second embodiment. That is, the first elastic connection member 64 is composed of a plurality of columnar first laminated rubbers 641. Each first laminated rubber 641 has a structure in which a plurality of rubber plates 245 and a plurality of rigid plates 246 shown in FIGS. 3A and 3B are laminated between the first base member 61 and the second base member 62. Such a first laminated rubber 641 has the characteristic that it has high rigidity in the longitudinal direction D1 parallel to the drill axis direction Dx, that is, the lamination direction, and low rigidity in the lateral direction D2 orthogonal to the drill axis direction Dx. The number of the first laminated rubbers 641 may be two or more, preferably three or four.

[0083] The second elastic connection member 65 is composed of a plurality of columnar second laminated rubbers 651. Each second laminated rubber 651 connects the peripheral convex portion 622 of the second base member 62 and the flange portion 723 of the first plate 721 of the drill support 72 to each other. FIG. 15 is a cross-sectional view of the second laminated rubber 651. As shown in this figure, the second laminated rubber 651 has a structure in which a plurality of rubber plates 655 and a plurality of rigid plates 656 are laminated between the peripheral convex portion 622 and the flange portion 723. The lamination direction of the rubber plate 655 and the rigid plate 656 is a direction orthogonal to the inclined inner peripheral surface 622a of the peripheral convex portion 622 and the inclined outer peripheral surface 723a of the flange portion 723, and is a direction non-parallel to the drill axis direction Dx. The number of the second laminated rubbers 651 may be two or more, preferably three or four.

[0084] Here, a line extending in the lamination direction through the centroid C5 of the second laminated rubber 651 is defined as the laminated rubber center line X2. As also shown in FIG. 16 to be described later, the laminated rubber center line X2 is inclined so as to approach the drill axis X1 toward the tip side opposite to the arm tip portion 102a. In other words, the second laminated rubber 651 is inclined and arranged such that the laminated rubber center line X2 extends toward the tip side and the radially inner side with respect to the drill axis X1. Note that the second laminated rubber 651 corresponds to the "element elastic body" in the present disclosure, and the laminated rubber center line X2 corresponds to the "elastic body center line" in the present disclosure.

[0085] FIG. 16 is a diagram showing the positional relationship between a plurality of second laminated rubbers 651 arranged obliquely as described above and the drill unit 7. As shown in this figure, the plurality of second laminated rubbers 651 are arranged such that their respective laminated rubber center lines X2 intersect at one intersection J on the drill axis X1. In the third embodiment, the intersection J coincides with the tip center of the pressure foot 73, that is, the center of the circular ring formed by the tip surface of the cylindrical pressure foot 73. In other words, when the plane including the tip surface of the pressure foot 73 is defined as the reference plane Rs, in the third embodiment, each second laminated rubber 651 is arranged such that each laminated rubber center line X2 of the plurality of second laminated rubbers 651 and the drill axis X1 intersect on the reference plane Rs. In this case, the drill axis X1, that is, the drill axis X1 which is a straight line including the central axis of the drill 71, corresponds to the "drill center line" in the present disclosure.

[0086] The distances between the respective centers of gravity C5 of the plurality of second laminated rubbers 651 and the intersection J are all the same. Also, in the third embodiment, the structures and shapes of the plurality of second laminated rubbers 651 are all the same. That is, the plurality of second laminated rubbers 651 have the same length in the lamination direction, that is, in the direction parallel to the laminated rubber center line X2, and are arranged such that the distances between the center of gravity C5 of each second laminated rubber 651 and the intersection J are equal to each other.

[0087] Each rubber plate 655 and each rigid plate 656 of the second laminated rubber 651 have an arc shape curved along a reference circle Rc having the same center in a cross-sectional view of FIG. 15 or FIG. 14 along the drill axis direction Dx, that is, in a cross-sectional view cut by a plane parallel to the drill axis direction Dx. The reference circle Rc is a circle with various radii centered at the intersection J shown in FIG. 16. In other words, the second laminated rubber 651 has a structure in which rubber plates 655 and rigid plates 656 having a cross-sectional arc shape curved along concentric circles are laminated.

[0088] As shown in FIG. 15, the plurality of rigid plates 656 in the second laminated rubber 651 include a first end rigid plate 656a, a second end rigid plate 656b, and a plurality of intermediate rigid plates 656c. The first end rigid plate 656a is disposed at one end in the lamination direction and is coupled to the inclined inner peripheral surface 622a of the second base member 62. The second end rigid plate 656b is disposed at the other end in the lamination direction and is coupled to the inclined outer peripheral surface 723a of the first plate 721. The plurality of intermediate rigid plates 656c are disposed between the first end rigid plate 656a and the second end rigid plate 656b. In the example of FIG. 15, three intermediate rigid plates 656c are provided, but the number of intermediate rigid plates 656c may be two or four or more. Both surfaces of all the intermediate rigid plates 656c and all the rubber plates 655 in the thickness direction parallel to the laminated rubber center line X2 are formed in a cross-sectional arc shape or spherical shape that curves along concentric circles. On the other hand, the first rigid plate 656a has a coupling surface with the inclined inner peripheral surface 622a formed in a planar shape, and the opposite surface is formed in a cross-sectional arc shape or spherical shape. The second rigid plate 656b has a coupling surface with the inclined outer peripheral surface 723a formed in a planar shape, and the opposite surface is formed in a cross-sectional arc shape or spherical shape.

[0089] As shown in FIG. 14, the first compression mechanism 66 includes a plurality of protruding pieces 661 fixed to the outer periphery of the tip of the peripheral convex portion 612 of the first base member 61, and a plurality of springs 662 attached in a tension state between each protruding piece 661 and the peripheral edge of the second base member 62. In the third embodiment, the number of the springs 662 is set to be the same as the number of the plurality of first laminated rubbers 641 constituting the first elastic connection member 64. Each spring 662 is disposed so as to be adjacent to the radially outer side of each first laminated rubber 641, and generates a load in a direction to reduce the distance between the protruding piece 661 and the second base member 62. Thereby, a compressive load acts on each first laminated rubber 641.

[0090] The second compression mechanism 67 includes a plurality of springs 671 attached in a tensioned state between the inclined inner peripheral surface 622a of the second base member 62 and the inclined outer peripheral surface 723a of the first plate 721. In the third embodiment, the number of the springs 671 is set to be the same as the number of the plurality of second laminated rubbers 651 that constitute the second elastic connection member 65. Each spring 671 is arranged so as to be adjacent to the radially outer side of each second laminated rubber 651, and generates a load in a direction to reduce the distance between the inclined inner peripheral surface 622a and the inclined outer peripheral surface 723a. Thereby, a compressive load acts on each second laminated rubber 651.

[0091] As described above, in the third embodiment, the first base member 61 and the second base member 62 are connected via the first elastic connection member 64 and the first compression mechanism 66, and the second base member 62 and the first plate 721 of the drill support 72 are connected via the second elastic connection member 65 and the second compression mechanism 67. According to such a configuration, it is possible to improve the accuracy of the hole drilling process by the drill 71 and to evenly bring the tip of the pressure foot 73 into contact with the workpiece W.

[0092] That is, in the third embodiment, the first base member 61 and the second base member 62 are elastically connected via the first elastic connection member 64 composed of a plurality of first laminated rubbers 641, and a compressive load in the drill axis direction Dx is applied to each first laminated rubber 641 from the first compression mechanism 66. Thereby, similar to the first embodiment and the second embodiment, the load that attempts to shift the relative position between the drill 71 and the workpiece W that can be brought about by the reaction force from the workpiece W can be released by the shear deformation of each first laminated rubber 641, and the axial position accuracy of the drill 71 can be ensured well by the compressive load applied to each first laminated rubber 641. As a result, the accuracy of the hole drilling process by the drill 71 can be improved.

[0093] Moreover, in the third embodiment, the second elastic connection member 65 that elastically connects the second base member 62 and the drill support 72 is composed of a plurality of second laminated rubbers 651 including rubber plates 655 and rigid plates 656 laminated in a direction non-parallel to the drill axis direction Dx. Specifically, the plurality of second laminated rubbers 651 are arranged such that their center lines, that is, the laminated rubber center lines X2, are inclined so as to approach the drill axis X1 toward the tip side. According to such a configuration, in response to the shear deformation of each second laminated rubber 651, the drill support 72 can tilt with respect to the second base member 62 in the direction of view shown in FIG. 16 orthogonal to the drill axis X1. That is, when the laminated rubber center line X2 is inclined with respect to the drill axis X1, the deformation mode when the second laminated rubber 651 is sheared becomes a two-dimensional deformation mode in a coordinate system having the direction axis parallel to the drill axis X1 as one axis. That is, the deformation mode when the second laminated rubber 651 is sheared becomes a two-dimensional deformation mode having a displacement component in the drill axis direction Dx parallel to the drill axis X1 and a displacement component orthogonal to the drill axis X1. The deformation mode is, for example, a two-dimensional deformation mode having a displacement component in the drill axis direction Dx and a displacement component in the left-right direction in FIG. 16. Therefore, when the second laminated rubbers 651 at a plurality of locations sandwiching the drill axis X1 are sheared, an operation is allowed in which the drill support 72 rotates slightly about the intersection point J where the respective laminated rubber center lines X2 intersect. As a result, the drill support 72 tilts with respect to the second base member 62. Such tilting of the drill support 72 facilitates the uniform contact of the tip of the pressure foot 73 with the workpiece W.

[0094] FIG. 17 is a schematic view showing a state in which even contact of the pressure foot 73 is achieved by tilting the drill support 72. The left view of FIG. 17 shows a state of single contact in which only the tip of one side of the pressure foot 73 is in contact with the work W. Even if such single contact of the pressure foot 73 occurs, according to the configuration of the third embodiment in which each second laminated rubber 651 is inclined with respect to the drill axis X1, as shown in the right view of FIG. 17, as a result of the shear deformation of each second laminated rubber 651 causing the drill support 72 to tilt autonomously, the tip of the pressure foot 73 comes into contact with the work W as a whole, and even contact of the pressure foot 73 is achieved. In other words, the end effector 1B of the third embodiment has a self-alignment function of adjusting the posture of the drill support 72 so that even contact of the pressure foot 73 is achieved.

[0095] More specifically, in the third embodiment, the center lines of the second laminated rubbers 651, that is, the laminated rubber center lines X2, intersect at one intersection J on the drill axis X1. According to such a configuration, the drill support 72 can be appropriately and slightly rotated about the intersection J on the drill axis X1, and the above-described self-alignment function can be enhanced.

[0096] Furthermore, in the third embodiment, the lengths of the second laminated rubbers 651 in the lamination direction, that is, the lengths along the laminated rubber center lines X2, are equal, and the distances between the centers of gravity C5 of the second laminated rubbers 651 and the above-described intersection J are equal to each other. Such a configuration makes it easier to slightly rotate the drill support 72 about the intersection J, so a high self-alignment function is achieved.

[0097] Also, in the third embodiment, the rubber plates 655 and the rigid plates 656 in each second laminated rubber 651 are formed in an arc shape that curves along a plurality of reference circles Rc, that is, concentric circles, centered on the same intersection J in the cross-sectional view of FIG. 15. According to such a configuration, the second laminated rubber 651 can be accurately shear-deformed so as to cause a slight rotation of the drill support 72 about the intersection J.

[0098] In the third embodiment, as shown in FIG. 16, an example is shown in which the intersection J where the laminated rubber center lines X2 of the second laminated rubbers 651 intersect coincides with the tip center of the pressure foot 73. However, the position of the intersection J is not limited to this. For example, the intersection J may be set at a position on the drill axis X1 that is somewhat away from the tip side or the base end side from the reference plane Rs corresponding to the tip of the pressure foot 73, or may be set at a position somewhat radially away from the drill axis X1. Further, each laminated rubber center line X2 only needs to be inclined so as to approach the drill axis X1 at least on the tip side, and does not necessarily have to intersect.

[0099] (4) Summary The above-described embodiments and their modifications include the following disclosures.

[0100] The end effector according to the first aspect of the present disclosure is an end effector attached to a robot arm for processing a workpiece, and includes a drill, a drill support for supporting the drill, a power device for advancing, retracting, and rotating the drill with respect to the drill support, a pressure foot that protrudes from the drill support toward the workpiece and contacts the workpiece during processing by the drill, a drill unit including the pressure foot, a base member fixed to the robot arm and spaced apart from the drill support in the drill axis direction parallel to the central axis of the drill, a structure in which a plurality of rubber plates and a plurality of rigid plates having higher rigidity than the rubber plates are laminated in the central axis of the drill between the base member and the drill support, an elastic connection member for connecting the base member and the drill support to each other, and a compression mechanism for applying a compressive load in the lamination direction of the rubber plates and the rigid plates to the elastic connection member.

[0101] According to this first aspect, an elastic connection member in which a plurality of rubber plates and a plurality of rigid plates are laminated is interposed between a base member fixed to the robot arm and a drill support that supports the drill. The elastic connection member having such a structure has the property of being easily deformed only in a direction orthogonal to the lamination direction. Therefore, according to this aspect in which such an elastic connection member is interposed between the base member and the drill support, even if the robot arm receives a reaction force and bends and deforms during the hole drilling process of drilling a hole in the workpiece with the drill, the influence caused by the bending deformation can be absorbed by the elastic connection member, and the positional relationship between the drill and the workpiece can be maintained well. Thereby, problems due to displacement of the drill, such as an increase in the hole diameter, can be suppressed, and the accuracy of the hole drilling process by the drill can be improved.

[0102] Further, since the elastic connection member is difficult to deform in the drill axis direction and receives a compressive load from the compression mechanism, it is difficult for a tensile force to be generated in the elastic connection member regardless of the posture of the end effector. Thereby, the positional accuracy in the axial direction of the drill can be ensured well, and the workability can be improved.

[0103] The end effector according to the second aspect further includes a tip-side member disposed on the opposite side of the base member with the drill support interposed therebetween in the first aspect, and the compression mechanism connects the tip-side member and the base member so that a load in a direction of pulling the tip-side member toward the base member is generated, thereby compressing the elastic connection member via the drill support.

[0104] According to this second aspect, a compression mechanism for applying a compressive load to the elastic connection member can be easily constructed.

[0105] The end effector according to the third aspect further includes a tip-side elastic connection member having the same structure as the elastic connection member and connecting the tip-side member and the drill support to each other in the second aspect.

[0106] According to this third aspect, a compression load can be collectively applied to each of the proximal-side and distal-side elastic connection members using the same compression mechanism.

[0107] In the end effector according to the fourth aspect, in the third aspect, the elastic connection member includes three or more first element elastic bodies separated from each other, the distal-side elastic connection member includes three or more second element elastic bodies separated from each other, and the first element elastic bodies and the second element elastic bodies are arranged such that the center of gravity of the drill unit is included inside a virtual polyhedron formed by connecting the center of gravity of each first element elastic body and the center of gravity of each second element elastic body.

[0108] According to this fourth aspect, even when machining is performed in a posture in which the central axis of the drill is inclined with respect to the vertical line, it is difficult for a bending load to occur in the elastic connection member and the distal-side elastic connection member, and only the load in the drill axis direction can be mainly borne. In addition, it is possible to prevent the load input from concentrating on a specific elastic body among the plurality of first element elastic bodies and second element elastic bodies. By these actions, it is possible to suppress the occurrence of problems such as peeling in each elastic connection member, and the performance of each elastic connection member can be maintained over a long period.

[0109] In the end effector according to the fifth aspect, in the first aspect, the compression mechanism compresses the elastic connection member by connecting the drill support and the base member so that a load in a direction of pulling the drill support toward the base member is generated.

[0110] According to this fifth aspect, it is possible to apply a compression load to the elastic connection member while shortening the dimension of the end effector in the drill axis direction.

[0111] In the end effector according to the sixth aspect, in the fifth aspect, the elastic connection member includes three or more element elastic bodies separated from each other, and the element elastic bodies are arranged such that the center of gravity of the drill unit is included inside a virtual polygon formed by connecting the centers of gravity of the element elastic bodies when viewed along the drill axis direction.

[0112] According to this sixth aspect, it becomes difficult for a bending load to occur in the elastic connection member, and only the load in the drill axis direction can be mainly borne. Further, among the plurality of element elastic bodies, it is possible to prevent the load input from concentrating on a specific element elastic body. By these actions, it is possible to suppress the occurrence of defects such as peeling in each elastic connection member, and the performance of each elastic connection member can be maintained over a long period.

[0113] The end effector according to the seventh aspect is the same as that in the fifth aspect, wherein the elastic connection member includes a plurality of element elastic bodies having a structure in which the rubber plate and the rigid plate are laminated, and the plurality of element elastic bodies are inclined and arranged such that the lamination direction of the rubber plate and the rigid plate is non-parallel to the drill axis direction when viewed in a direction orthogonal to the drill axis direction.

[0114] According to this seventh aspect, since the lamination direction of the rubber plate and the rigid plate in the element elastic body is non-parallel to the drill axis direction, the deformation mode when the element elastic body is sheared becomes a two-dimensional deformation mode in a coordinate system having a direction axis parallel to the central axis of the drill as one axis. Therefore, when the plurality of element elastic bodies are sheared, a minute rotation of the drill support is allowed, and thereby the drill support tilts with respect to the base member. Such tilting of the drill support is automatically performed when the pressure foot contacts the work, so that the tip of the pressure foot easily contacts the work evenly. That is, according to the seventh aspect, it is possible to achieve a self-alignment function for adjusting the posture of the drill support so that the pressure foot contacts evenly.

[0115] The end effector according to the eighth aspect is the same as that in the seventh aspect, wherein the plurality of element elastic bodies are inclined and arranged such that the elastic body center line extending in the lamination direction through the center of gravity of each element elastic body approaches the central axis of the drill toward the tip side opposite to the robot arm.

[0116] According to this eighth aspect, when the pressure foot contacts the workpiece, the drill support can be appropriately micro-rotated or tilted so that the self-alignment function described above is achieved.

[0117] In the end effector according to the ninth aspect, in the eighth aspect, the plurality of the element elastic bodies are inclined and arranged so that the respective elastic body center lines intersect at one intersection on the drill center line which is a straight line including the central axis of the drill.

[0118] According to this ninth aspect, the drill support can be appropriately micro-rotated around the intersection on the drill center line, and the self-alignment function described above can be enhanced.

[0119] In the end effector according to the tenth aspect, in the ninth aspect, the plurality of the element elastic bodies have the same length in the stacking direction, and are arranged so that the distances between the centers of gravity of the respective element elastic bodies and the intersection are equal to each other.

[0120] According to this tenth aspect, the micro-rotation of the drill support around the intersection becomes easier, so that a high self-alignment function is achieved.

[0121] In the end effector according to the eleventh aspect, in the seventh to tenth aspects, the rubber plate and the rigid plate in each of the element elastic bodies are in an arc shape curved along concentric circles in a cross-sectional view along the drill axis direction.

[0122] According to this eleventh aspect, the element elastic body can be accurately shear-deformed so as to cause the above-described micro-rotation or tilt of the drill support.

Explanation of Reference Numerals

[0123] 1 End effector 21 First outer plate (base member) 22 Second outer plate (tip-side member) 23 Compression mechanism 24 First elastic connection member (elastic connection member) 241 First laminated rubber (first element elastic body) 245 Rubber plate 246 Rigid plate 25 Second elastic connection member (tip-side elastic connection member) 251 Second laminated rubber (second element elastic body) 3 Drill unit 31 Drill 32 Drill support 33 Pressure foot 34 Power device 100 Robot arm C0 Center of gravity (of the drill unit) C1 Center of gravity (of the first laminated rubber) C2 Center of gravity (of the second laminated rubber) PH Virtual polyhedron W Workpiece 1A End effector 41 Base plate (base member) 43 Compression mechanism 44 Elastic connection member 441 Laminated rubber (element elastic body) 5 Drill unit 51 Drill 52 Drill support 53 Pressure foot 54 Power device C3 Center of gravity (of the laminated rubber) PG Virtual polygon 1B End effector 62 Second base member (base member) 65 Second elastic connection member (elastic connection member) 651 Second laminated rubber (element elastic body) 655 Rubber plate 656 Rigid plate 7 Drill unit 71 Drill 72 Drill support 73 Pressure foot 74 Power device C5 Center of gravity (of the laminated rubber) J intersection point

Claims

1. An end effector attached to a robot arm for machining a workpiece, a drill unit including a drill, a drill support supporting the drill, a power unit for moving the drill forward and backward relative to the drill support and rotating the drill, and a pressure foot protruding from the drill support toward the workpiece and contacting the workpiece during machining by the drill; a base member fixed to the robot arm and spaced apart from the drill support in a drill axial direction parallel to a central axis of the drill; an elastic connecting member having a structure in which a plurality of rubber plates and a plurality of rigid plates having rigidity higher than that of the rubber plates are laminated between the base member and the drill support, the elastic connecting member connecting the base member and the drill support to each other; a compression mechanism that applies a compressive load to the elastic connecting member in a layering direction of the rubber plate and the rigid plate.

2. The end effector of claim 1 , A tip side member is further provided on the opposite side of the base member with the drill support therebetween, The compression mechanism compresses the elastic connecting member through the drill support by connecting the tip side member and the base member so as to generate a load in a direction that pulls the tip side member toward the base member.

3. The end effector according to claim 2, The end effector further includes a distal elastic connecting member having a structure similar to that of the elastic connecting member and connecting the distal member and the drill support to each other.

4. The end effector according to claim 3, The elastic connecting member includes three or more first element elastic bodies spaced apart from one another, The tip side elastic connecting member includes three or more second element elastic bodies spaced apart from each other, An end effector, wherein the first element elastic body and the second element elastic body are arranged so that the center of gravity of the drill unit is included within a virtual polyhedron formed by connecting the centers of gravity of each of the first element elastic bodies and each of the second element elastic bodies.

5. The end effector of claim 1 , The compression mechanism compresses the elastic connecting member by connecting the drill support and the base member so as to generate a load in a direction that pulls the drill support toward the base member.

6. The end effector according to claim 5, The elastic connecting member includes three or more element elastic bodies spaced apart from each other, An end effector in which each of the element elastic bodies is arranged so that, when viewed along the drill axial direction, the center of gravity of the drill unit is included within an imaginary polygon formed by connecting the centers of gravity of each of the element elastic bodies.

7. The end effector according to claim 5, the elastic connection member includes a plurality of elastic elements each having a structure in which the rubber plate and the rigid plate are laminated together, an end effector, wherein the multiple element elastic bodies are arranged at an angle so that the stacking direction of the rubber plate and the rigid plate is non-parallel to the drill axial direction when viewed in a direction perpendicular to the drill axial direction.

8. The end effector of claim 7, An end effector in which the multiple element elastic bodies are arranged at an angle so that the elastic body center line extending in the stacking direction through the center of gravity of each element elastic body approaches the central axis of the drill toward the tip side opposite the robot arm.

9. The end effector of claim 8, An end effector in which the multiple element elastic bodies are arranged at an angle so that the center lines of the respective elastic bodies intersect at a single intersection point on the drill center line, which is a straight line including the central axis of the drill.

10. The end effector of claim 9, An end effector, wherein the multiple elastic elements have the same length in the stacking direction and are arranged so that the distances between the centers of gravity of the respective elastic elements and the intersection points are equal to each other.

11. The end effector according to any one of claims 7 to 10, an end effector, wherein the rubber plate and the rigid plate in each of the element elastic bodies have an arc shape curved along concentric circles when viewed in a cross-sectional view along the drill axial direction;

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