End effector

Abstract

To provide an end effector capable of suppressing sagging due to its own weight while using an elastic body.SOLUTION: An end effector (1) includes a base member (21) fixed to a robot arm (100), a drill unit (3), a power device (4), an elastic connection member (24), and a load transmission mechanism (28). The drill unit (3) includes a drill (31) that is advanced and retracted and / or rotated by the power unit (4), a drill support (33) that supports the drill (31), and a pressure foot (34) that protrudes from the drill support (33) toward the workpiece (W). The elastic connection member (24) connects the base member (21) and the drill support (33) to each other. The load transmission mechanism (28) converts the weight of the counterweight (41) into a load in a direction of lifting the drill unit (3) and transmits the load to the drill unit (3).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an end effector attached to a robot arm for machining a workpiece. [Background technology]

[0002] One known example of an end effector is that disclosed in Patent Document 1. Specifically, Patent Document 1 discloses providing a mechanical compliance mechanism made of an elastic body such as a coil spring between the tip of the robot arm and the end effector, or in the end effector itself. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-231925 Summary of the Invention [Problem to be solved by the invention]

[0004] When a mechanical compliance mechanism made of an elastic body is used as in Patent Document 1, for example, when the central axis of the end effector is oriented in a substantially horizontal direction, the end effector may be displaced downward relative to the tip of the robot arm due to its own weight, that is, the end effector may sag. Such sagging of the end effector is undesirable because it may cause problems such as the machining position of the end effector being shifted from its original position, that is, it may lead to a decrease in machining accuracy.

[0005] The present disclosure has been made in consideration of the above circumstances, and aims to provide an end effector that uses an elastic body yet is capable of preventing sagging due to its own weight. [Means for solving the problem]

[0006] In order to solve the above problem, an end effector according to one aspect of the present disclosure is an end effector attached to a robot arm for machining a workpiece, and includes: a drill unit including a drill, a drill support supporting the drill, and a pressure foot protruding from the drill support toward the workpiece and coming into contact with the workpiece when the drill is machining; a base member fixed to the robot arm and spaced from the drill support in an X direction parallel to a central axis of the drill; a power unit for moving the drill back and forth relative to and / or rotating the drill support; an elastic connecting member including an elastic body for connecting the base member and the drill support to each other; a counterweight; and a load transmission mechanism for converting the weight of the counterweight into a load in a direction lifting the drill unit and transmitting the load to the drill unit, when the direction of the weight of the drill unit has a component in a Z direction perpendicular to the X direction. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide an end effector that can prevent sagging due to its own weight while using an elastic body. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating a schematic diagram of a work robot including an end effector according to an embodiment of the present disclosure. [Figure 2] FIG. 4 is a side cross-sectional view showing the detailed structure of the end effector. [Figure 3] FIG. 2 is an enlarged cross-sectional view showing the drill unit. [Figure 4] FIG. 3 is a view equivalent to FIG. 2 showing a situation in which a workpiece is drilled. [Figure 5] FIG. 3 is a view equivalent to FIG. 2 showing a state in which the drill has penetrated the workpiece. [Figure 6A] FIG. 3 is a cross-sectional view showing the structure of a first laminated rubber. [Figure 6B] FIG. 4 is a cross-sectional view showing a state in which the first laminated rubber is deformed. [Figure 7] FIG. 3 is a cross-sectional view showing the structure of a second laminated rubber. [Figure 8] FIG. 10 is a diagram showing the positional relationship between the second laminated rubber and the drill unit. [Figure 9] FIG. 2 is a perspective view conceptually showing the layout of the main components of the end effector. [Figure 10] 3 is a view equivalent to FIG. 2 showing a state in which the first laminated rubber is shear-deformed during drilling. FIG. [Figure 11] FIG. 10 is a schematic diagram illustrating sagging of the drill unit that can occur when the end effector is positioned sideways. [Figure 12] 10 is a schematic diagram showing how the sagging of the drill unit is prevented by balancing with the power motor. FIG. [Figure 13] 5A and 5B are schematic diagrams showing types of displacement modes of the drill unit. [Figure 14] FIG. 10 is a schematic diagram showing how the action of the second laminated rubber achieves uniform contact of the pressure foot. DETAILED DESCRIPTION OF THE INVENTION

[0009] A preferred embodiment of the end effector of the present disclosure will be described in detail below with reference to the drawings. The end effector of the present disclosure is attached to a robot arm for machining a workpiece. The robot arm movably supports the end effector so that the end effector can approach any machining position on the workpiece. Any type of robot arm may be used as long as it has the above-mentioned functions, but an articulated robot, for example, is preferred.

[0010] FIG. 1 is a diagram schematically illustrating a working robot including an end effector 1 according to an embodiment of the present disclosure. The working robot includes a robot arm 100 formed of an articulated robot and an end effector 1 attached to the tip of the robot arm 100. In this embodiment, the robot arm 100 includes a first arm unit 101 and a second arm unit 102. The second arm unit 102 is rotatably connected to the tip 101a of the first arm unit 101 via a joint 103. The first arm unit 101 is rotatably connected to an arm unit further upstream via a joint or the like. The end effector 1 is attached to the tip 102a of the second arm unit 102 via a bracket 105. Note that, hereinafter, the tip 102a of the second arm unit 102 will be referred to as the arm tip 102a. The arm tip 102a is an end on one axial side of the second arm unit 102, opposite the joint 103.

[0011] [Overall structure of the end effector] FIG. 2 is a side cross-sectional view showing the detailed structure of the end effector 1. The end effector 1 shown in this figure is a tool for drilling to open holes in a workpiece W. The end effector 1 includes a support mechanism 2 attached to the arm tip 102a, a drill unit 3 supported by the support mechanism 2, and a power unit 4 that drives the drill unit 3. The workpiece W can be of any type as long as it is an object that requires drilling, but it can be, for example, a component material of a structure such as an aircraft, a railway vehicle, or an automobile. In this embodiment, the workpiece W is illustrated as a curved plate material.

[0012] In this embodiment, the central axis of the end effector 1, i.e., a line including the central axis of a drill 31 (described later) in the drill unit 3, is referred to as the drill axis AX1. The end effector 1 is attached to the arm tip 102a in a coaxial orientation with the second arm unit 102. That is, the end effector 1 is attached in a orientation in which the drill axis AX1 is parallel to the axial direction of the second arm unit 102. Hereinafter, the direction parallel to the drill axis AX1 will be referred to as the X direction. Furthermore, one end side in the X direction that is closer to the arm tip 102a will be referred to as the "base end side," and the other end side in the X direction that is farther from the arm tip 102a will be referred to as the "tip side." Furthermore, the direction perpendicular to the X direction and perpendicular to the plane of the paper in FIG. 2 will be referred to as the Y direction, and the directions perpendicular to both the X direction and the Y direction will be referred to as the Z direction.

[0013] The support mechanism 2 includes a first base member 21, a second base member 22, a first elastic connecting member 24, a second elastic connecting member 25, a first compression member 26, a second compression member 27, and a load transmission mechanism 28. The first base member 21 is fixed to the arm tip 102a via a bracket 105. The second base member 22 is disposed closer to the tip than the first base member 21. The first elastic connecting member 24 elastically connects the first base member 21 and the second base member 22, which are spaced apart in the X direction. The second elastic connecting member 25 elastically connects the second base member 22, which are spaced apart in the X direction, to the drill unit 3. The first compression member 26 applies a compressive load to the first elastic connecting member 24. The second compression member 27 applies a compressive load to the second elastic connecting member 25. The load transmission mechanism 28 transmits the weight of a power motor 41 (described later) of the power unit 4 to the drill unit 3. The first base member 21 corresponds to the "base member" in this disclosure.

[0014] The drill unit 3 includes a drill 31, a drill housing 32, a drill support 33, and a pressure foot 34. The drill 31 is a tool that cuts the workpiece W when drilling the workpiece W. The drill housing 32 rotatably holds the drill 31. The drill support 33 is disposed at a position spaced apart from the second base member 22 in the X direction and supports the drill 31 so that it can move back and forth and rotate. The pressure foot 34 has a structure that surrounds the periphery of the drill 31 and is pressed against the workpiece W when the drill drills the workpiece W. The pressure foot 34 may be any protrusion that can press against the workpiece W during drilling. In this embodiment, as shown in FIG. 9 (described later), the pressure foot 34 is composed of multiple rod-shaped bodies arranged around the drill 31. Note that the pressure foot may be, for example, a cylindrical body that surrounds the periphery of the drill 31.

[0015] The drill support 33 has an outer plate 331, an inner plate 335, and multiple guide shafts 337. The outer plate 331 is disposed closer to the tip than the second base member 22 and is supported by the second base member 22 via a second elastic connecting member 25. The inner plate 335 is disposed further closer to the tip than the outer plate 331. The multiple guide shafts 337 connect the outer plate 331 and the inner plate 335 in the X direction.

[0016] FIG. 3 is an enlarged cross-sectional view of the drill unit 3. As shown in this figure, the outer plate 331 has a central portion 332 that is U-shaped and opens toward the tip end in the cross-sectional view of FIG. 3, and a flange portion 333 that extends from the periphery of the central portion 332 while sloping toward the tip end and radially outward. The flange portion 333 has an inclined outer peripheral surface 333a that faces a later-described inclined inner peripheral surface 222a of the second base member 22 at a distance. The inclined outer peripheral surface 333a is an inclined surface that is not parallel to the X direction in FIG. 3, in other words, an inclined surface that intersects with the drill axis AX1 when viewed in the Y direction. The inclined outer peripheral surface 333a is inclined so as to move away from the drill axis AX1 as it approaches the tip end.

[0017] The inner plate 335 is formed in a flat plate shape and is disposed on the tip side of the center portion 332 of the outer plate 331 and radially inward of the flange portion 333. The pressure feet 34 are provided on the inner plate 335 so as to protrude from multiple locations around the drill 31 toward the tip side.

[0018] The guide shafts 337 are each a rod-shaped body extending in the X direction, and connect the central portion 332 of the outer plate 331 to the inner plate 335. The guide shafts 337 are arranged so as to penetrate through the peripheral portion of the slide plate 321 (described later) at multiple points.

[0019] The drill housing 32 is formed in a cylindrical shape coaxial with the drill 31 extending in the X direction. The drill 31 protrudes from the drill housing 32 toward its tip end and is supported by the drill housing 32 so as to be rotatable about its central axis. The drill housing 32 penetrates the inner plate 335 and is supported by the inner plate 335 so as to be slidable in the X direction.

[0020] A slide plate 321 that protrudes radially outward from the drill housing 32 is attached to the drill housing 32. The slide plate 321 is formed in a disk shape that is concentric with the drill housing 32, and is fixed to the drill housing 32 while being fitted onto the drill housing 32. The slide plate 321 is slidable in the X direction along a guide shaft 337 that passes through the slide plate 321. In other words, the guide shaft 337 has the function of guiding the forward and backward movement of the drill housing 32 or the drill 31.

[0021] As shown in Figures 2 and 3, the power unit 4 moves the drill 31 forward and backward and rotates it relative to the drill support 33. Specifically, the power unit 4 includes a power motor 41, a flexible shaft 42, and a conversion mechanism 43. The power motor 41 is a drive source that moves the drill 31, and has a rotation motor 41A that drives the drill 31 to rotate, and a feed motor 41B that drives the drill 31 forward and backward. The flexible shaft 42 is a bendable, long rotation transmission member that transmits the rotation of the rotation motor 41A to the drill 31. The conversion mechanism 43 converts the rotation of the feed motor 41B into forward and backward movement of the drill 31.

[0022] The rotation motor 41A and the feed motor 41B are arranged side by side in the Z direction. Each of the motors 41A, 41B is attached to the first base member 21 via a slide support portion 281, which will be described later. In addition, each of the motors 41A, 41B is arranged on the opposite side of the drill unit 3 in the X direction, with the first base member 21 in between.

[0023] Like a typical flexible shaft, the flexible shaft 42 has a rotatable, flexible inner wire and a flexible outer tube that covers the inner wire. One end or tip of the inner wire passes through the inside of the drill housing 32 and is connected to the drill 31. The other end or base end of the inner wire is connected to the output shaft of the rotary motor 41A.

[0024] The conversion mechanism 43 has a rotating shaft 431, a transmission member 432, and a plurality of ball screw shafts 433. The rotating shaft 431 extends in the X direction and rotates integrally with the output shaft of the feed motor 41B. A universal joint or the like is appropriately applied to the rotating shaft 431 so that the angle of the rotating shaft 431 can be changed. Each ball screw shaft 433 is a screw shaft that extends in the X direction for screw-feeding the slide plate 321, and is respectively screwed into the slide plate 321. The transmission member 432 interlocks and connects the rotating shaft 431 and each ball screw shaft 433. The type of the transmission member 432 is not particularly limited, and for example, a combination of a belt and a pulley or the like can be used as the transmission member 432.

[0025] The power unit 4 as described above advances and retreats and rotates the drill 31 in the following manner. For example, when the rotary motor 41A is operated to rotate its output shaft, the rotation of the output shaft is transmitted to the drill 31 via the inner wire of the flexible shaft 42, causing the drill 31 to rotate. When the feed motor 41B is operated to rotate its output shaft, the rotation is transmitted to the ball screw shaft 433 via the rotary shaft 431 and the transmission member 432, causing the ball screw shaft 433 to rotate. When the ball screw shaft 433 rotates, the slide plate 321 is screw-fed, and accordingly, the drill housing 32 and the drill 31 move in the X direction, i.e., advance and retreat.

[0026] The advancement or retraction of the drill 31 can be switched depending on the rotation direction of the feed motor 41B. For example, when the feed motor 41B operates in the forward direction, the ball screw shaft 433 rotated by the feed motor 41B screws the slide plate 321 toward the tip end, thereby moving the drill 31 toward the tip end, i.e., advancing. Conversely, when the feed motor 41B operates in the reverse direction, the ball screw shaft 433 rotated by the feed motor 41B screws the slide plate 321 toward the base end, thereby moving the drill 31 toward the base end, i.e., retracting.

[0027] FIG. 4 is a view equivalent to FIG. 2 showing a situation in which a workpiece W is drilled using the end effector 1 of this embodiment. As shown in this figure, during drilling, the drill 31 is rotationally driven with the tip of the pressure foot 34 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 34 abuts around the target machining position Pa of the workpiece W. The robot arm 100 also holds the end effector 1 so that the pressure foot 34 is pressed against the workpiece W with a desired pressing force. This positions the drill 31 so that its tip abuts against the target machining position Pa. The drill 31 is also rotationally driven by a rotary motor 41A.

[0028] In the above state, an operation is performed to push the drill 31 toward the tip end. That is, as shown in Fig. 5, the feed motor 41B is driven in the forward direction to screw the slide plate 321 toward the tip end, thereby pushing the drill 31 toward the tip end. This operation is performed, for example, until the drill 31 penetrates the workpiece W. As a result, 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.

[0029] [Support mechanism details] Next, we will explain the detailed structure of the support mechanism 2. As already mentioned, the support mechanism 2 includes the first and second base members 21, 22, the first and second elastic connecting members 24, 25, the first and second compression members 26, 27, and the load transmission mechanism 28. Details of each element are as follows.

[0030] As shown in FIGS. 2 and 3, the first base member 21 has a flat plate portion 211 coupled to the bracket 105, and an extension portion 212 extending from the end of the flat plate portion 211 in the Z direction toward the base end side.

[0031] As shown in Fig. 3, the second base member 22 has a flat plate portion 221 connected to the flat plate portion 211 of the first base member 21 via the first elastic connecting member 24, and a peripheral convex portion 222 protruding from the peripheral edge of the flat plate portion 221 toward the tip side. The inner peripheral surface of the peripheral convex portion 222 is an inclined inner peripheral surface 222a that is non-parallel to the X direction when viewed in the direction shown in Fig. 3 that is perpendicular to the drill axis AX1. The inclined inner peripheral surface 222a is inclined so as to move away from the drill axis AX1 toward the tip side. In other words, the inclined inner peripheral surface 222a is inclined so as to extend from the peripheral edge of the flat plate portion 221 toward the tip side and radially outward.

[0032] The first elastic connecting member 24 includes a plurality of cylindrical first laminated rubbers 241. For example, in a plan view seen from one side in the X direction, the first laminated rubbers 241 are arranged at equal intervals along a circle centered on the drill axis AX1. The number of first laminated rubbers 241 may be two or more, and is preferably three or four.

[0033] FIG. 6A 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 that are alternately stacked. Each rubber plate 245 is a disc-shaped body made of rubber and has a uniform thickness. Each rigid plate 246 is a disc-shaped body made of metal or resin and has a uniform thickness. In other words, the rubber plate 245 is made of a material that is more elastically deformable 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 desirable that it be 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.

[0034] The first laminated rubber 241 having the above-described structure has high rigidity in the lamination direction, i.e., the direction in which the rubber plates 245 and the rigid plates 246 are laminated, and low rigidity in a direction perpendicular to the lamination direction. In this embodiment, the lamination direction of the first laminated rubber 241 when applied to the end effector 1 corresponds to the direction parallel to the drill axis AX1, i.e., the X direction. Therefore, the first laminated rubber 241 has high rigidity in the X direction and low rigidity in the Y direction or Z direction. This means that, as shown in FIG. 6B , the first laminated rubber 241 is difficult to deform in the X direction but is easy to deform in the Y direction or Z direction. In other words, the first laminated rubber 241 has a selective compliance structure in which it is easy to deform only in a specific direction, in this case, the Y direction or the Z direction.

[0035] The first laminated rubber 241 has both ends in the lamination direction coupled to the first base member 21 and the second base member 22, respectively, thereby elastically connecting the two. That is, the rigid plate 246 closest to the base end of the first laminated rubber 241 is coupled to the first base member 21, and the rigid plate 246 closest to the tip end of the first laminated rubber 241 is coupled to the second base member 22. As a result, the first base member 21 and the second base member 22, which are spaced apart in the X direction, are elastically connected via the first laminated rubber 241. In other words, each first laminated rubber 241 of the first elastic connecting member 24 has a structure in which multiple rubber plates 245 and multiple rigid plates 246 are layered between the first base member 21 and the second base member 22. The rigid plates 246 and the base members 21 and 22 can be coupled by any appropriate method, such as welding, adhesive bonding, or bolting. The same applies to the second laminated rubber 251, which will be described later.

[0036] As shown in FIGS. 2 and 3, the second elastic connecting member 25 includes a plurality of cylindrical second laminated rubbers 251. For example, in a plan view seen from one side in the X direction, the second laminated rubbers 251 are arranged at equal intervals along a circle centered on the drill axis AX1. Unlike the first laminated rubber 241 described above, the second laminated rubbers 251 are arranged at an angle with respect to the drill axis AX1. The number of second laminated rubbers 251 may be two or more, and is preferably three or four. The second laminated rubbers 251 correspond to the "element elastic body" in this disclosure.

[0037] 7 is a cross-sectional view of the second laminated rubber 251. As shown in this figure, the second laminated rubber 251 has a plurality of rubber plates 255 and a plurality of rigid plates 256 that are alternately laminated. The materials of the rubber plates 255 and the rigid plates 256 are the same as those of the rubber plates 245 and the rigid plates 246 of the first laminated rubber 241 described above. The second laminated rubber 251 having such a structure has the same properties as the first laminated rubber 241, in that it has high rigidity in the lamination direction and low rigidity in the direction perpendicular to the lamination direction.

[0038] The second laminated rubber 251 has both ends coupled to the second base member 22 and the outer plate 331 of the drill support 33, respectively, thereby elastically connecting the two. That is, the rigid plate 256 closest to the base end of the second laminated rubber 251 is coupled to the peripheral convex portion 222 of the second base member 22, and the rigid plate 256 closest to the tip end of the second laminated rubber 251 is coupled to the flange portion 333 of the outer plate 331. As a result, the second base member 22 and the outer plate 331, which are spaced apart in the X direction, are elastically connected via the second laminated rubber 251. In other words, the second laminated rubber 251 of the second elastic connecting member 25 has a structure in which a plurality of rubber plates 255 and a plurality of rigid plates 256 are layered between the peripheral convex portion 222 and the flange portion 333. The stacking direction of the rubber plate 255 and the rigid plate 256 is perpendicular to the inclined inner peripheral surface 222a of the peripheral convex portion 222 and the inclined outer peripheral surface 333a of the flange portion 333, and is non-parallel to the drill axis AX1 or X direction.

[0039] Here, a line passing through the center of gravity C1 of the second laminated rubber 251 and extending in the lamination direction is defined as a laminated rubber center line AX2. As shown in Fig. 8 (described later), the laminated rubber center line AX2 is inclined so that it approaches the drill axis AX1 toward the tip end, opposite the arm tip portion 102a. In other words, the second laminated rubber 251 is disposed with an inclination such that the laminated rubber center line AX2 extends toward the tip end and radially inward toward the drill axis AX1.

[0040] 8 is a diagram showing the positional relationship between the plurality of second laminated rubbers 251 arranged at an angle as described above and the drill unit 3. As shown in this figure, the plurality of second laminated rubbers 251 are arranged so that their respective laminated rubber center lines AX2 intersect at a single intersection J on the drill axis AX1. Specifically, when a plane including the tip surface of the pressure foot 34 is defined as a reference plane Rs, in this embodiment, the second laminated rubbers 251 are arranged so that the respective laminated rubber center lines AX2 of the plurality of second laminated rubbers 251 intersect with the drill axis AX1 on the reference plane Rs.

[0041] Each rubber plate 255 and each rigid plate 256 of the second laminated rubber 251 has an arc shape curved along a reference circle Rc with the same center in the cross section of Fig. 7 taken along the X direction, that is, in the cross section taken along a plane parallel to the drill axis AX1. The reference circle Rc is a circle of various radii centered at the intersection J shown in Fig. 8. In other words, the second laminated rubber 251 has a structure in which the rubber plate 255 and each rigid plate 256, each having an arc-shaped cross section curved along concentric circles, are stacked.

[0042] As shown in FIG. 7 , the multiple rigid plates 256 in the second laminated rubber 251 include a first end rigid plate 256a, a second end rigid plate 256b, and multiple intermediate rigid plates 256c. The first end rigid plate 256a is disposed at one end in the stacking direction and is connected to the inclined inner circumferential surface 222a of the second base member 22. The second end rigid plate 256b is disposed at the other end in the stacking direction and is connected to the inclined outer circumferential surface 333a of the outer plate 331. The multiple intermediate rigid plates 256c are disposed between the first end rigid plate 256a and the second end rigid plate 256b. In the example shown in FIG. 7 , three intermediate rigid plates 256c are provided, but the number of intermediate rigid plates 256c may be two, four, or more. All of the intermediate rigid plates 256c and all of the rubber plates 255 have cross sections that are arc-shaped or spherical, curved along concentric circles, on both sides in the thickness direction parallel to the laminated rubber center line AX2. On the other hand, the first rigid plate 256a has a flat surface that joins with the inclined inner peripheral surface 222a, and the opposite surface has an arc-shaped or spherical cross section. The second rigid plate 256b has a flat surface that joins with the inclined outer peripheral surface 333a, and the opposite surface has an arc-shaped or spherical cross section.

[0043] 2 and 3, the first compression member 26 includes a plurality of springs 261 attached in a tensioned state between the flat plate portion 211 of the first base member 21 and the second base member 22. In this embodiment, the number of springs 261 is set to be the same as the number of the plurality of first laminated rubbers 241 constituting the first elastic connecting member 24. Each spring 261 is disposed adjacent to the radially outer side of each first laminated rubber 241, and generates a load in a direction that shortens the distance between the first base member 21 and the second base member 22. This causes a compressive load to act on each first laminated rubber 241. Due to this compressive load, tensile force is less likely to be generated in the first laminated rubber 241 regardless of the posture of the end effector 1, and the thickness of the first laminated rubber 241 is stabilized.

[0044] The second compression member 27 includes a plurality of springs 271 attached in a tensioned state between the inclined inner circumferential surface 222a of the second base member 22 and the inclined outer circumferential surface 333a of the outer plate 331. In this embodiment, the number of springs 271 is set to be the same as the number of the plurality of second laminated rubbers 251 constituting the second elastic connecting member 25. Each spring 271 is disposed adjacent to the radially outer side of each second laminated rubber 251, and generates a load in a direction that shortens the distance between the inclined inner circumferential surface 222a and the inclined outer circumferential surface 333a. This causes a compressive load to act on each second laminated rubber 251. This compressive load makes it difficult for a tensile force to be generated in the second laminated rubber 251 regardless of the posture of the end effector 1, thereby stabilizing the thickness of the second laminated rubber 251.

[0045] As shown in FIG. 2, the load transmission mechanism 28 includes a slide support portion 281 that supports the power motor 41 so that it can slide in the Z direction, and a connecting mechanism 285 that connects the power motor 41 and the drill support 33 so that they can move relative to each other in the Z direction.

[0046] The slide support portion 281 may be of any type as long as it can slidably support the power motor 41, but in this embodiment, a so-called linear guide is used as the slide support portion 281. That is, the slide support portion 281 has a guide member 282 that extends in the Z direction and is fixed to the base end of the extension portion 212 of the first base member 21, and a slider 283 that is slidable in the Z direction along the guide member 282. The rotation motor 41A and the feed motor 41B that constitute the power motor 41 are fixed to the slider 283 while being adjacent to each other in the Z direction. In other words, the rotation motor 41A and the feed motor 41B are fixed to the slider 283, and thereby supported by the first base member 21 while being slidable in the Z direction.

[0047] FIG. 9 is a perspective view that schematically illustrates the end effector 1 of this embodiment. This figure conceptually illustrates the layout of the main components of the end effector 1, and does not necessarily match the previously described drawings in detail. In the following, the plus and minus sides of the X, Y, and Z directions are defined as shown in FIG. 9. For example, in this embodiment, the +X side is synonymous with the tip side of the end effector 1, and the -X side is synonymous with the base side of the end effector 1.

[0048] As shown in FIGS. 2 and 9, the connecting mechanism 285 has a balance member 286, a first suspending member 287, and a second suspending member 288.

[0049] The balance member 286 is made of a plate-like body extending in the X direction, and is tiltably supported on the flat plate portion 211 of the first base member 21. More specifically, the balance member 286 is tiltably supported on the end of the flat plate portion 211 on the +Z side, i.e., the end of the flat plate portion 211 opposite the power motor 41, via a support shaft P1 extending in the Y direction.

[0050] The first hanging member 287 connects one end of the balance member 286 to the drill support 33. More specifically, the first hanging member 287 connects the +X side end, which is the end of the balance member 286 closer to the drill support 33, to the outer plate 331 of the drill support 33.

[0051] The second suspending member 288 connects the other end of the balance member 286 to the power motor 41. More specifically, the second suspending member 288 connects the −X side end of the balance member 286, which is the end closer to the power motor 41, to the power motor 41.

[0052] As shown in FIG. 9, the first hanging member 287 includes a pair of joint arms 287a arranged in the Y direction with the drill axis AX1 between them. Each joint arm 287a is a rod-shaped body extending in the Z direction. The +Z side end of each joint arm 287a is connected to the +X side end of the balance member 286 via a first ball joint 287b shown in FIG. 2. Similarly, the −Z side end of each joint arm 287a is connected to the outer plate 331 of the drill support 33 via a second ball joint 287c. The first ball joint 287b connects the +Z side end of the joint arm 287a to the balance member 286 so as to be rotatable in any direction, and the second ball joint 287c connects the −Z side end of the joint arm 287a to the outer plate 331 so as to be rotatable in any direction. In other words, the first hanging member 287 has a pair of joint arms 287a, a first ball joint 287b that rotatably connects one end of each joint arm 287a to the balance member 286, and a second ball joint 287c that rotatably connects the other end of each joint arm 287a to the drill support 33.

[0053] The second hanging member 288 includes a pair of joint arms 288a arranged in the Y direction with the drill axis AX1 between them. Each joint arm 288a is a rod-shaped body extending in the Z direction. The +Z side end of each joint arm 288a is rotatably connected to the −X side end of the balance member 286 via a third ball joint 288b shown in FIG. 2. Meanwhile, the −Z side end of each joint arm 288a is directly connected to the power motor 41.

[0054] The load transmission mechanism 28 configured as described above has a function of transmitting the weight of the power motor 41 to the drill unit 3 when the direction of the weight of the power motor 41, i.e., the vertical direction, has a Z-direction component. Here, the state in which the vertical direction has a Z-direction component refers to a state in which the vertical direction is not perpendicular to the Z direction, typically a state in which the vertical direction is approximately parallel to the Z direction. For example, when the end effector 1 is positioned in a sideways orientation with the drill axis AX1 oriented approximately horizontally, i.e., when the +Z side is up and the −Z side is down in FIG. 2 , the vertical direction is approximately parallel to the Z direction. In this state, the weight of the power motor 41, which is supported by the slide support part 281 so as to be slidable in the Z direction, acts as a force pulling the −X side end of the balance member 286 downward, i.e., toward the −Z side, via the second hanging member 288. This pulling force is converted into a force lifting the +X side end of the balance member 286 upward. Furthermore, this lifting force acts as a force to lift the drill support 33 upward, i.e., toward the +Z side, via the first hanging member 287. In this way, when the vertical direction has a Z-direction component, the load transmission mechanism 28 has the function of converting the weight of the power motor 41 into an upward force and transmitting it to the drill support 33 or the drill unit 3. In this case, the power motor 41 functions as a counterweight to balance out the drill unit 3.

[0055] [Action and effect] As described above, in this embodiment, the drill unit 3 is supported on the first base member 21 fixed to the arm tip portion 102a via the multiple elastic connecting members 24, 25 and the second base member 22. More specifically, the first base member 21 and the second base member 22 are connected via the first elastic connecting member 24, and the second base member 22 and the drill support 33 of the drill unit 3 are connected via the second elastic connecting member 25. Furthermore, the power motor 41 for driving the drill 31 and the drill support 33 are connected via the load transmission mechanism 28 so as to be relatively movable in the Z direction. This configuration has the advantage that sagging of the drill unit 3 due to its own weight can be prevented while using elastic bodies such as the elastic connecting members 24, 25.

[0056] Specifically, in this embodiment, the first elastic connecting member 24 is composed of a plurality of first laminated rubbers 241, each including a rubber plate 245 and a rigid plate 246, laminated in the X direction parallel to the drill axis AX1. According to this embodiment in which such a first elastic connecting member 24 is interposed between the first base member 21 and the second base member 22, even if a reaction force acts on the robot arm 100 when the pressure foot 34 comes into contact with and applies pressure to the workpiece W during drilling, and the robot arm 100 is deflected by this reaction force, the effect of the deflection can be absorbed by the deformation of the first elastic connecting member 24, i.e., the shear deformation of each of the first laminated rubbers 241. This makes it possible to prevent the relative position between the drill 31 and the workpiece W from shifting, and to maintain a good positional relationship between the drill 31 and the workpiece W.

[0057] If the first elastic connecting member 24 were not present, for example, when the pressure foot 34 contacts and applies pressure to the workpiece W, a reaction force from the workpiece W acts on the robot arm 100 via the end effector 1. When the robot arm 100 flexes and deforms in response to this reaction force, the behavior of the drill 31 may become unstable, and the center position of the drill 31 may shift relative to the workpiece W. That is, the flexural deformation of the robot arm 100 may generate a load that tends to shift the relative position between the drill 31 and the workpiece W, which may cause the center position of the drill 31 to shift from the target machining position Pa. In contrast, according to the present embodiment using the first elastic connecting member 24, even if the robot arm 100 flexes and deforms as described above, the first laminated rubber 241 of the first elastic connecting member 24 shears as shown in FIG. 10 , and the load can be released while maintaining the positional relationship between the drill 31 and the workpiece W. In this way, in this embodiment, by using an elastic body such as the first elastic connecting member 24, defects caused by the above-mentioned misalignment of the drill 31, such as an increase in the hole diameter, can be prevented, and the accuracy of the hole drilling process using the drill 31 can be improved.

[0058] On the other hand, the use of an elastic body such as the first elastic connecting member 24 may cause the drill unit 3 to be displaced downward relative to the arm tip 102a, i.e., may cause the drill unit 3 to sag. That is, in the present embodiment in which the first elastic connecting member 24 is interposed between the first base member 21 and the second base member 22, when the vertical direction, which is the direction of the weight of the drill unit 3, has a Z-direction component, the weight of the drill unit 3 and the second base member 22 may cause shear deformation of the first elastic connecting member 24, which may cause the drill unit 3 to be displaced downward relative to the arm tip 102a, as shown schematically in FIG. 11 . In contrast, in the present embodiment, the power motor 41 and the drill support 33 of the drill unit 3 are connected to each other via the load transmission mechanism 28, and therefore, the weight of the power motor 41 may be converted into a load in a direction lifting the drill unit 3 and transmitted to the drill unit 3, as shown schematically in FIG. 12 . The transmitted load acts in a direction that cancels out the weight of the drill unit 3, thereby preventing sagging of the drill unit 3. Furthermore, positional deviation of the drill 31 that may occur due to the sagging is prevented, thereby improving the machining accuracy of the drill 31.

[0059] Furthermore, in this embodiment, the power motor 41 is disposed on the -X side of the first base member 21, i.e., on the opposite side of the drill unit 3 with the first base member 21 in the X direction. The load transmission mechanism 28 also includes a slide support portion 281 that supports the power motor 41 slidably in the Z direction relative to the first base member 21, and a connecting mechanism 285 that connects the power motor 41 and the drill support 33 so that they can move relatively in the Z direction. With this configuration, when the direction of the weight of the power motor 41, which is slidable in the Z direction, has a Z-directional component, the weight of the power motor 41 is transmitted to the drill support 33 via the connecting mechanism 285, whereby a load can be appropriately applied to the drill unit 3 in a direction that lifts it.

[0060] Specifically, in this embodiment, the connecting mechanism 285 includes a balance member 286 supported by the first base member 21 so as to be tiltable about a support axis P1 extending in the Y direction, a first hanging member 287 connecting an end of the balance member 286 on the +X side to the drill support 33, and a second hanging member 288 connecting an end of the balance member 286 on the -X side to the power motor 41. With this configuration, the rational structure using the balance member 286 and the two hanging members 287, 288 can convert the weight of the power motor 41 into a load in a direction to lift the drill unit 3 and transmit it to the drill unit 3.

[0061] Furthermore, in this embodiment, the first hanging member 287 includes a pair of joint arms 287a arranged side by side in the Y direction with the drill axis AX1 between them, a first ball joint 287b that connects the +Z side end of each joint arm 287a to the balance member 286 so as to be rotatable in any direction, and a second ball joint 287c that connects the −Z side end of each joint arm 287a to the drill support 33 so as to be rotatable in any direction. With this configuration, the connection angle between the first hanging member 287 and the balance member 286 and the connection angle between the first hanging member 287 and the drill support 33 can be varied, while preventing torsion, which is rotation of the drill unit 3 around the drill axis AX1, from occurring.

[0062] That is, because both ends of a pair of joint arms 287a arranged in the Y direction with the drill axis AX1 in between are connected to the balance member 286 and the drill support 33 via ball joints 287b and 287c, the displacement modes of the drill unit 3 can be limited to the following first to fourth modes. Specifically, the first mode is a mode in which the drill unit 3 is displaced in the Z direction, as shown in the upper left diagram of FIG. 13 . This first mode can be generated by the balance member 286 tilting in the X direction around the support axis P1. The second mode is a mode in which the drill unit 3 is displaced in the Y direction, as shown in the upper right diagram of FIG. 13 . This second mode can be generated by the joint arms 287a tilting in the Y direction. The third mode is a mode in which the drill unit 3 tilts in the X direction relative to the balance member 286 when viewed in the Y direction, as shown in the lower left diagram of FIG. 13 . The fourth mode is a mode in which the drill unit 3 tilts in the X direction relative to the balance member 286 when viewed in the Z direction. These first to fourth modes may occur individually, or two or more modes may occur simultaneously.

[0063] When the displacement modes of the drill unit 3 are limited to the above four modes, the drill unit 3 cannot rotate around the drill axis AX1, and torsion of the drill unit 3 is sufficiently suppressed. In this way, in the present embodiment, torsion of the drill unit 3 can be suppressed, and therefore, a decrease in the machining accuracy of the drill 31 due to the torsion can be suppressed, and machining accuracy can be improved.

[0064] In addition, in this embodiment, the power motor 41, which is part of the power unit 4 that moves the drill 31 back and forth and rotates it, is also used as a counterweight to balance the drill unit 3, making it possible to simplify and lighten the device compared to when a dedicated counterweight is provided.

[0065] In this embodiment, the second elastic connecting member 25 is composed of a plurality of second laminated rubbers 251, each including a rubber plate 255 and a rigid plate 256, laminated in a direction non-parallel to the drill axis AX1. Specifically, the plurality of second laminated rubbers 251 are arranged with their center lines, i.e., laminated rubber center lines AX2, inclined toward the drill axis AX1 toward their tips. This configuration enables the drill support 33 to tilt relative to the second base member 22 in response to shear deformation of each second laminated rubber 251, as viewed in a direction perpendicular to the drill axis AX1, as shown in FIG. 8. In other words, when the laminated rubber center lines AX2 are inclined with respect to the drill axis AX1, the deformation mode of the second laminated rubber 251 when it undergoes shear deformation becomes a two-dimensional deformation mode in a coordinate system in which the axis parallel to the drill axis AX1 is the first axis. That is, when the second laminated rubber 251 undergoes shear deformation, the deformation mode is a two-dimensional mode having a displacement component in the X direction parallel to the drill axis AX1 and a displacement component in the Z direction or Y direction perpendicular to the drill axis AX1. Therefore, shear deformation of the second laminated rubber 251 at multiple locations on either side of the drill axis AX1 allows the drill support 33 to rotate slightly around the intersection J where the center lines AX2 of the laminated rubbers intersect, causing the drill support 33 to tilt with respect to the second base member 22. Such tilting of the drill support 33 makes it easy to bring the tip of the pressure foot 34 into uniform contact with the workpiece W.

[0066] FIG. 14 is a schematic diagram showing how tilting the drill support 33 achieves uniform contact of the pressure foot 34. The upper diagram in FIG. 14 shows a state of partial contact, in which only one tip of the pressure foot 34 abuts against the workpiece W. Even if such partial contact of the pressure foot 34 occurs, according to the configuration of this embodiment in which each second laminated rubber 251 is tilted with respect to the drill axis AX1, as shown in the lower diagram in FIG. 14, the drill support 33 autonomously tilts due to shear deformation of each second laminated rubber 251. As a result, the entire tip of the pressure foot 34 abuts against the workpiece W, achieving uniform contact of the pressure foot 34. In other words, the end effector 1 of this embodiment has a self-alignment function that adjusts the attitude of the drill support 33 so that uniform contact of the pressure foot 34 is achieved.

[0067] More specifically, in this embodiment, the center lines of the second laminated rubbers 251, i.e., the laminated rubber center lines AX2, intersect at a single intersection point J on the drill axis AX1. With this configuration, the drill support 33 can be appropriately rotated slightly around the intersection point J on the drill axis AX1, thereby enhancing the self-alignment function described above.

[0068] [Variations] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and the following modifications are possible, for example.

[0069] In the above embodiment, a plurality of first laminated rubbers 241 including rubber plates 245 and rigid plates 246 laminated in the X direction are used as the first elastic connecting member 24. However, the first elastic connecting member 24 may be any elastic body that can elastically connect the first base member 21 and the second base member 22, and various elastic bodies can be used as the first elastic connecting member 24. For example, an elastic body made of a single material such as rubber or elastomer may be used as the first elastic connecting member 24. The same applies to the second elastic connecting member 25.

[0070] In the above embodiment, in addition to the first elastic connecting member 24 whose center line extends in the X direction, the second elastic connecting member 25 whose center line is inclined with respect to the X direction is used, but the second elastic connecting member 25 may be omitted. In this case, it is sufficient to connect the first base member 21 and the drill support 33 via the first elastic connecting member 24, and the second base member 22 becomes unnecessary.

[0071] In the above embodiment, the rotary motor 41A that rotates the drill 31 is disposed on the opposite side of the first base member 21 from the drill unit 3, but the motor that rotates the drill 31 may also be built into the drill housing 32.

[0072] In the above embodiment, the drill 31 is rotated and advanced / retracted by the power unit 4 including the rotary motor 41A and the feed motor 41B, but the power unit 4 may be any power unit that rotates and / or advances / retracts the drill 31.

[0073] [summary] The above-described embodiment and its modifications include the following disclosures.

[0074] An end effector according to a first aspect of the present disclosure is an end effector attached to a robot arm for machining a workpiece, and includes: a drill unit including a drill, a drill support supporting the drill, and a pressure foot protruding from the drill support toward the workpiece and coming into contact with the workpiece when the drill is machining; a base member fixed to the robot arm and spaced from the drill support in an X direction parallel to a central axis of the drill; a power unit for moving the drill back and forth relative to and / or rotating the drill support; an elastic connecting member including an elastic body for connecting the base member and the drill support to each other; a counterweight; and a load transmission mechanism for converting the weight of the counterweight into a load in a direction lifting the drill unit and transmitting the load to the drill unit, when the direction of the weight of the drill unit has a component in a Z direction perpendicular to the X direction.

[0075] According to this first aspect, the base member and the drill support are connected via the elastic connecting member, so that even if a reaction force acts on the robot arm when the pressure foot comes into contact with and applies pressure to the workpiece during drilling, and this reaction force causes the robot arm to bend, the effect of the reaction force can be absorbed by the shear deformation of the elastic connecting member, thereby improving the accuracy of drilling.

[0076] However, in this embodiment, in which an elastic connecting member is interposed between the base member and the drill support, when the vertical direction, which is the direction of the drill unit's weight, has a Z-axis component, the weight of the drill unit may cause shear deformation of the elastic connecting member, which may result in the drill unit being displaced downward relative to the robot arm, i.e., causing the drill unit to sag. In contrast, in this embodiment, the counterweight and the drill support are connected to each other via a load transmission mechanism, so the weight of the counterweight can be converted into a load in a direction lifting the drill unit and transmitted to the drill unit. The transmitted load acts in a direction that counteracts the weight of the drill unit, preventing the drill unit from sagging. Furthermore, misalignment of the drill 31, which may occur due to the sagging, is prevented, thereby improving the drill machining accuracy.

[0077] In the end effector of the second aspect, in the first aspect, the counterweight is positioned on the opposite side of the drill unit across the base member in the X direction, and the load transmission mechanism includes a slide support portion that supports the counterweight slidably in the Z direction relative to the base member, and a connecting mechanism that connects the counterweight and the drill support so that they can move relative to each other in the Z direction.

[0078] In this second aspect, the weight of the counterweight, which is slidable in the Z direction, is transmitted to the drill support via a connecting mechanism, thereby allowing a load to be appropriately applied to the drill unit in the direction of lifting it.

[0079] In the end effector of a third aspect, in the second aspect, the connecting mechanism includes a balance member extending in the X direction and supported by the base member so as to be tiltable around a support axis extending in a Y direction perpendicular to the X direction and the Z direction, a first hanging member connecting one end of the balance member in the X direction to the drill support, and a second hanging member connecting the other end of the balance member in the X direction to the counterweight.

[0080] In this third aspect, a rational structure using a balance member and two hanging members can convert the weight of the counterweight into a load in the direction of lifting the drill unit and transmit it to the drill unit.

[0081] The end effector of the fourth aspect is the third aspect, wherein the first hanging member includes a pair of joint arms extending in the Z direction arranged side by side in the Y direction across the central axis of the drill, a first ball joint that connects one end of each of the joint arms in the Z direction to the balance member so as to be rotatable in any direction, and a second ball joint that connects the other end of each of the joint arms in the Z direction to the drill support so as to be rotatable in any direction.

[0082] In this fourth aspect, the connection angle between the first suspension member and the balance member and the connection angle between the first suspension member and the drill support can be varied, while preventing torsion, which is rotation around the central axis of the drill unit, from occurring. As a result, it is possible to prevent a decrease in drill machining accuracy due to torsion of the drill unit, and to improve machining accuracy.

[0083] In the end effector of a fifth aspect, in the first to fourth aspects, the elastic connecting member includes a plurality of element elastic bodies having a structure in which a plurality of rubber plates and a plurality of rigid plates having higher rigidity than the rubber plates are stacked, and the plurality of element elastic bodies are arranged at an angle so that the stacking direction of the rubber plates and the rigid plates is non-parallel to the X direction when viewed in a Y direction that is orthogonal to the X direction and the Z direction, respectively.

[0084] In this fifth aspect, the lamination direction of the rubber plates and rigid plates in the elastic element is non-parallel to the drill axial direction, so that the deformation mode when the elastic element undergoes shear deformation is a two-dimensional deformation mode in a coordinate system with a directional axis parallel to the central axis of the drill as one axis. Therefore, the shear deformation of the multiple elastic element bodies allows for slight rotation of the drill support, which causes the drill support to tilt relative to the base member. This tilting of the drill support occurs autonomously when the pressure foot contacts the workpiece, making it easier for the tip of the pressure foot to contact the workpiece evenly. In other words, this aspect achieves a self-alignment function that adjusts the attitude of the drill support to achieve even contact of the pressure foot.

[0085] An end effector according to a sixth aspect is any of the first to fifth aspects, wherein the counterweight is configured by at least a part of the power unit.

[0086] In this way, when at least a part of the power unit is used as a counterweight, the unit can be simplified and made lighter than when a dedicated counterweight is provided. [Explanation of symbols]

[0087] 1 End Effector 2 Support mechanism 21 First base member (base member) 24 First elastic connecting member (elastic connecting member) 25 Second elastic connecting member (elastic connecting member) 251 Second laminated rubber (element elastic body) 255 Rubber Plate 256 Rigid plate 28 Load transmission mechanism 281 Slide support 285 Connection mechanism 286 Balance Components 287 First Hanging Member 287a Jointed Arm 287b First ball joint 287c Second ball joint 288 Second Hanging Member 3 Drill Unit 31 Drill 33 Drill Support 34 Pressure Foot 4 Power plant 41 Power motor (counterweight)

Claims

1. An end effector attached to a robot arm for machining a workpiece, a drill unit including a drill, a drill support that supports the drill, and a pressure foot that protrudes from the drill support toward the workpiece and comes into contact with the workpiece during machining by the drill; a base member fixed to the robot arm and spaced apart from the drill support in an X direction parallel to a central axis of the drill; a power unit for moving the drill forward and backward and / or rotating the drill relative to the drill support; an elastic connecting member including an elastic body and connecting the base member and the drill support to each other; A counterweight and a load transmission mechanism that converts the weight of the counterweight into a load in a direction lifting the drill unit and transmits the load to the drill unit, when the direction of the weight of the drill unit has a Z-direction component perpendicular to the X-direction.

2. The end effector of claim 1 , the counterweight is disposed on the opposite side of the drill unit with the base member interposed therebetween in the X direction; The load transmission mechanism includes a slide support portion that supports the counterweight slidably in the Z direction relative to the base member, and a connecting mechanism that connects the counterweight and the drill support so that they can move relatively in the Z direction.

3. The end effector according to claim 2, The connecting mechanism includes: a balance member extending in the X direction and supported by the base member so as to be tiltable about a support shaft extending in a Y direction perpendicular to the X direction and the Z direction; a first hanging member connecting one end of the balance member in the X direction and the drill support; a second hanging member connecting the other end of the balance member in the X direction to the counterweight.

4. The end effector according to claim 3, The first hanging member includes: a pair of joint arms extending in the Z direction and arranged side by side in the Y direction with a central axis of the drill therebetween; a first ball joint that connects one end of each of the joint arms in the Z direction to the balance member so as to be rotatable in any direction; a second ball joint that connects the other end of each joint arm in the Z direction to the drill support so as to be rotatable in any direction.

5. The end effector according to any one of claims 1 to 4, the elastic connecting member includes a plurality of elastic elements having a structure in which a plurality of rubber plates and a plurality of rigid plates having higher rigidity than the rubber plates are stacked together, the plurality of 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 X direction when viewed in a Y direction perpendicular to the X direction and the Z direction.

6. The end effector according to any one of claims 1 to 4, The end effector, wherein the counterweight comprises at least a portion of the power unit.

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