Wrist joint unit and work device equipped with the same

Abstract

To provide a wrist joint unit capable of achieving miniaturization and weight reduction and a work device equipped with the same.SOLUTION: A wrist joint unit HU comprises: an arm 5; a first rotation member 6 that is provided so as to be rotatable about a first rotation axis C1; a bevel gear 7 that is a second rotation member provided so as to be rotatable about a second rotation axis C2 orthogonal to the first rotation axis C1; a first motor 9 that is supported by the arm 5 and that drives the first rotation member 6 to rotate; and a second motor that is supported by the arm 5 and that drives the bevel gear 7 to rotate. The first rotation member 6 is supported in a cantilever manner by the arm 5, and the bevel gear 7 which is the second rotation member is supported in a cantilever manner by the first rotation member 6. An end effector 11 can be fitted to the bevel gear 7.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wrist joint unit and a working device equipped with the same, and relates to a technique that is applied to, for example, a SCARA robot, a Cartesian robot, a vertical articulated robot, etc. [Background technology]

[0002] A wrist joint unit is rotatably connected to the tip of the robot arm. This wrist joint unit has two mutually perpendicular rotation axes, and includes a first member that rotates around one axis, and a second member connected to the first member so as to rotate around the other axis. An end effector is installed on the second member so as to perform a predetermined task. Since the wrist joint unit is provided at the tip of the robot's arm, it is preferable that it is lightweight, and since the specified tasks are performed by the end effector attached to the wrist joint unit, it is preferable that it is small in size to avoid interference with the surroundings.

[0003] Patent Document 1 discloses a wrist unit. This wrist unit has two drive motors, and a multi-stage pulley and belt mechanism is installed between these drive motors and a wrist that is provided so as to be able to swing and rotate by these drive motors, and by ensuring the necessary reduction ratio without using a reducer such as a strain wave gear reducer, it is possible to avoid an increase in size and high costs.

[0004] Patent Document 2 discloses a vertical articulated robot. In this vertical articulated robot, a B arm is rotatably supported at one end by an A arm. A through hole is provided in the reduction gear that drives the A arm, and a transmission mechanism that drives the B arm is inserted through the through hole, thereby achieving a reduction in size and weight. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-226028 A [Patent Document 2] Patent No. 7009929 Summary of the Invention [Problem to be solved by the invention]

[0006] In the wrist unit described in Patent Document 1, the pivot axis is supported at both ends, which increases the width of the wrist and may cause interference with the surroundings when performing a specific task. In addition, the rotation range is limited due to the structure.

[0007] In the vertical articulated robot described in Patent Document 2, the arm at the tip is supported by a cantilever, which allows for a certain degree of miniaturization. However, since a reducer and other components are mounted on the rotating part, there is a limit to how much the robot can be made smaller and lighter.

[0008] An object of the present invention is to provide a wrist joint unit that can be made smaller and lighter, and a working device equipped with the same. [Means for solving the problem]

[0009] The wrist joint unit of the present invention comprises an arm and a first rotating member supported by the arm in a cantilever manner and rotatable about a first rotation axis; a bevel gear that is a second rotating member that is cantilevered on the first rotating member and rotatably provided around a second rotation axis that is perpendicular to the first rotation axis; a first motor supported by the arm and configured to rotate the first rotating member; a second motor supported by the arm and configured to rotate the bevel gear; An end effector is attachable to the bevel gear.

[0010] According to this configuration, the first rotating member is supported by the arm at one end, and the bevel gear, which is the second rotating member, is supported by the first rotating member at one end, so that the first and second rotating members can increase the degree of freedom of rotational movement without interfering with the first and second motors and the support member. In addition, since the first and second rotating members are supported by one end, the size and weight can be reduced compared to a structure in which the first and second rotating members are supported at both ends. Since the first and second motors are supported by the arm as the base, rather than by rotating members that perform rotational movement, the motor body does not move. This allows the first and second rotating members to be lightweight and compact. Furthermore, since an end effector can be attached to the bevel gear, which is the second rotating member, a wrist joint unit that has a small number of parts and is compact and lightweight can be realized.

[0011] a bevel gear that meshes with the bevel gear, and a gear shaft to which the bevel gear is fixed and which is rotatably supported by the arm and the first rotating member via bearings (2, 4), The first rotating member may be rotatably supported relative to the arm via a bearing (1), and this bearing (1) may be coaxially provided with a bearing (4) that rotatably supports the gear shaft relative to the arm. In this case, by rotating both the first and second motors in an appropriate relationship, it is possible to drive the bevel gear, which is the second rotating member, to rotate only around the first rotation axis. By rotating only the second motor without rotating the first motor, the bevel gear, which is the second rotating member, can be driven to rotate only around the second rotation axis.

[0012] The boss outer diameter D of the bevel gear, which is the second rotating member, may have a tolerance class of h7 or less or g6 or less in the dimensional tolerance used in commonly used fitting shafts, and the boss outer diameter D may have a concentricity of 0.03 mm or less with respect to the boss inner diameter d of the bevel gear into which the bearing (3) is fitted. In this case, the accuracy of operation of the end effector attached to the bevel gear can be improved compared to a structure in which the boss outer diameter D of the bevel gear exceeds h7, or a structure in which the concentricity of the boss outer diameter D of the bevel gear with respect to the boss inner diameter d of the bevel gear exceeds 0.03 mm.

[0013] The boss end face of the bevel gear which is the second rotating member may have a perpendicularity of 0.05 mm or less with respect to the boss inner diameter d of the bevel gear into which the bearing 3 is fitted. In this case, it becomes possible to accurately and appropriately attach the end effector to the bevel gear.

[0014] The bevel gear as the second rotating member may have a boss side surface and an end surface provided with a screw hole for mounting the end effector, in which case the end effector can be easily attached to and detached from the bevel gear.

[0015] The boss end face of the bevel gear, which is the second rotating member, may be provided with a mounting hole in which a pin can be installed to ensure reproducibility of the mounting of the end effector and prevent misalignment in the rotational direction. In this case, by installing a pin in the mounting hole in the boss end face of the bevel gear, it is possible to ensure reproducibility of the mounting of the end effector and prevent misalignment in the rotational direction, and the end effector can be easily attached to and detached from the bevel gear.

[0016] A shoulder may be provided on the boss outer diameter D of the bevel gear, which is the second rotating member, to regulate the mounting position of the end effector in the second rotational axis direction, and the radius R of the corner of the shoulder may be 0.2 mm or less, or the corner of the shoulder may be recessed. In this case, when the end effector is fitted onto the boss outer diameter D of the bevel gear, the end effector reliably abuts against the shoulder, ensuring the repeatability of the mounting position of the end effector in the second rotational axis direction.

[0017] The working device of the present invention is equipped with any one of the wrist joint units. This working device can be used in narrower spaces, near walls, or with multiple devices arranged closely together, compared to working devices using conventional wrist joint units. Effect of the Invention

[0018] The wrist joint unit of the present invention can be made smaller and lighter because the first and second rotating members are supported by a cantilever. The first and second motors are supported by an arm that serves as a base, so the motor body does not move, making it possible to realize lightweight and compact first and second rotating members. An end effector can be attached to the bevel gear, which is the second rotating member, making it possible to realize a compact and lightweight wrist joint unit with a small number of parts. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a longitudinal sectional view of a wrist joint unit according to a first embodiment of the present invention. [Diagram 2] FIG. 4 is a diagram showing an outline of the relationship between the two motors of the wrist joint unit and the spur gears. [Diagram 3] FIG. 2 is an enlarged partial cross-sectional view showing the vicinity of a second rotating member of the wrist joint unit. [Figure 4] FIG. 4 is a view taken along line IV-IV in FIG. [Figure 5A] FIG. 4 is a partial enlarged view of the VA portion in FIG. [Figure 5B] FIG. 5B is a partially enlarged view showing a modified example in which the shoulder corner of FIG. 5A is partially modified. [Figure 6A] FIG. 1 is a diagram showing a first example of a working device equipped with a wrist joint unit according to any one of the embodiments. [Figure 6B] FIG. 11 is a diagram showing a second example of a working device equipped with a wrist joint unit according to any one of the embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [First embodiment] A wrist joint unit according to an embodiment of the present invention will be described with reference to Figures 1 to 5A. A working device including the wrist joint unit, which will be described later, is used in, for example, medical equipment or industrial equipment. <Overall configuration of the wrist joint unit> 1, the wrist joint unit HU includes an arm 5, a first rotating member 6 supported on the arm 5 in a cantilever manner and rotatable about a first rotation axis C1, a reduction gear mechanism 8 including a second rotating member 7 supported on the first rotating member 6 in a cantilever manner and rotatable about a second rotation axis C2 perpendicular to the first rotation axis C1, and first and second motors 9 and 10 serving as drive sources. An end effector 11 is attached to the bevel gear 7 serving as the second rotating member. The working device performs work by positioning the end effector 11 attached to the bevel gear 7 with respect to a workpiece.

[0021] <Arm> The base arm 5 has a base arm 5b and a tip arm 5a connected to the base arm 5b. The tip arm 5a is formed in a cylindrical shape with a bottom, and the base arm 5b is connected to the peripheral edge of the opening of the cylindrical part of the tip arm 5a. A part of the reduction mechanism 8 described later is provided in a space S1 surrounded by the base arm 5b and the tip arm 5a.

[0022] <First rotating member> The first rotating member 6 is supported by the distal arm 5a in a cantilever manner and is provided rotatably around the first rotating axis C1 by the bearing 1. The first rotating member 6 has a hollow cylindrical base rotating table 6a and a tip rotating table 6b fixed to the base rotating table 6a. In this example, the base rotating table 6a and the tip rotating table 6b are provided as separate members and connected to each other, but the base rotating table 6a and the tip rotating table 6b may be provided integrally. The term "provided integrally" means that the base rotating table 6a and the tip rotating table 6b are not formed by combining a plurality of elements but are formed as a part or the whole of a single object from a single material by, for example, machining. The first and second rotating axes C1 and C2 mean rotation axes that do not have a substance.

[0023] The outer peripheral surface of the outer ring of the bearing 1 is fitted and fixed to the bottom of the tip arm 5a, which is a bottomed cylinder, and the outer peripheral surface of the base side rotating table 6a is fitted and fixed to the inner peripheral surface of the inner ring of the bearing 1. A tip side rotating table 6b, for example, in the shape of a square cylinder, is connected to one side of the base side rotating table 6a, and this tip side rotating table 6b is provided so as to protrude in one direction of the first rotation axis, that is, the upper side in FIG. 1. A space S2 is formed in the tip side rotating table 6b to prevent interference with the bevel gears 7 and 12, and a hole 6ba is formed to fit and fix the gear shaft 13 that supports the bevel gear 7. A cover 14 is provided on one side of the tip side rotating table 6b to prevent foreign matter from entering the space S2 and to prevent grease from leaking.

[0024] <Drive source> As shown in Figs. 1 and 2, the first and second motors 9 and 10 are supported by the base-side arm 5b of the arm 5. The first motor 9 is a drive source that rotates the first rotating member 5, and the second motor 10 is a drive source that rotates the bevel gear 7, which is the second rotating member. As shown in Fig. 1, a hole 5ba that supports the motor body of the first motor 9 is formed in the base-side arm 5b, and the motor shaft is housed in the space S1 in the arm 5. The rotation axis of the motor shaft is arranged parallel to the first rotation axis C1. A hole that supports the motor body of the second motor 10 (Fig. 2) is also formed in the base-side arm 5b, and the motor shaft of the second motor 10 (Fig. 2) is also housed in the space S1 in the arm 5. The rotation axis of the motor shaft is also arranged parallel to the first rotation axis C1.

[0025] <Deceleration mechanism> The reduction mechanism 8 includes a first reduction mechanism 8A that reduces the speed of rotation of the first motor 9, and a second reduction mechanism 8B that reduces the speed of rotation of the second motor 10 (FIG. 2). The first reduction mechanism 8A has a spur gear 15 fixed to the motor shaft of the first motor 9, a spur gear 16 fixed to the other side of the base end side rotating table 6a and meshing with the spur gear 15, and a bearing 1 that supports the first rotating member 6 relative to the arm 5. The spur gear 16 is rotatable around the first rotating axis C1, and the spur gears 15 and 16 are housed in the space S1 in the arm 5. A deep groove ball bearing capable of receiving radial and axial loads is applied as the bearing 1. By driving the first motor 9 to rotate, the first rotating member 6 is driven to rotate around the first rotating axis C1 at a predetermined reduction ratio by the first reduction mechanism 8A.

[0026] The second reduction mechanism 8B has spur gears 17, 18 (Fig. 2), bearings 2, 4, a base-side gear shaft 19, bevel gears 12, 7, a bearing 3, and a tip-side gear shaft 13. The spur gear 17 (Fig. 2) is fixed to the motor shaft of the second motor 10 (Fig. 2). The base-side gear shaft 19 is rotatably supported by the base-side arm 5b and the base-side rotating table 6a via bearings 4, 2. The bearings 2, 4 are provided coaxially with the bearing 1. A spur gear 18 is fixed to the base end of the base-side gear shaft 19, and a bevel gear 12 is fixed to the tip of the gear shaft 19. The spur gear 18 is accommodated in the space S1 in the arm 5, and the bevel gear 12 is accommodated in the space S2 of the tip-side rotating table 6b, and meshes with the bevel gear 7, which is the second rotating member.

[0027] As shown in Fig. 3, the gear shaft 13 on the tip side extends in the direction of the second rotation axis C2. The gear shaft 13 on the tip side has a small diameter portion 13a located at the tip in the longitudinal direction and a large diameter portion 13b coaxially connected to the small diameter portion 13a. Most of the large diameter portion 13b is fitted and fixed into a hole 6ba in the tip side rotating table 6b, and the small diameter portion 13a is provided so as to protrude from the hole 6ba. The bevel gear 7 is fixed to the small diameter portion 13a of the gear shaft 13 via multiple bearings 3,3 (two in this example).

[0028] The inner ring of each bearing 3 is fitted and fixed to the small diameter portion 13a of the gear shaft 13, and the boss inner diameter d of the bevel gear 7 is fitted and fixed to the outer ring of each bearing 3. Similarly to the bearing 1, deep groove ball bearings capable of receiving radial and axial loads are also used for the bearings 2, 3, and 4 in Fig. 1. By driving the second motor 10 in Fig. 2 to rotate, the bevel gear 7 shown in Fig. 1 is driven to rotate around the second rotation axis C2 at a predetermined reduction ratio by the second reduction mechanism 8B.

[0029] However, the base end rotating table 6a is rotatably supported by the tip end arm 5a via bearing 1, and the base end gear shaft 19 is fixed to this base end rotating table 6a via bearing 2, and the bearings 1 and 2 are arranged coaxially, so that when the first motor 9 is driven to rotate, the base end gear shaft 19 rotates with it. As a result, the bevel gear 7 rotates around the second rotation axis C2. At this time, in order for the bevel gear 7 to rotate only around the first rotation axis C1 without rotating around the second rotation axis C2, it is necessary to perform an appropriate rotational drive on the gear shaft 19 on the base end side in response to the rotational drive of the first rotating member 5.

[0030] By rotating the first motor 9 and the second motor 10 (FIG. 2) in an appropriate relationship, it is possible to rotate the bevel gear 7 only about the first rotation axis C1. By appropriately rotating the second motor 10 (FIG. 2) without rotating the first motor 9, it is possible to rotate the bevel gear 7 only about the second rotation axis C2. In addition, by rotating the first motor 9 and the second motor 10 (Figure 2) in an appropriate relationship, it is possible to simultaneously rotate the bevel gear 7 around the first and second rotation axes C1, C2 at desired speeds, respectively.

[0031] <About parameters etc.> As shown in Fig. 3, the boss outer diameter D of the bevel gear 7, which is the second rotating member, is set to a tolerance class of h7 or g6 or less in the dimensional tolerance used for commonly used fitting shafts so that the end effector 11 (Fig. 1) can be properly attached. Specifically, the dimensional tolerance of the boss outer diameter D is set to a tolerance class of interference fit such as h7, h6, h5, g6, etc. Furthermore, the coaxiality of the boss outer diameter D with the boss inner diameter d of the bevel gear 7, which fits the bearing 3, is set to 0.03 mm or less.

[0032] In this case, the operating accuracy of the end effector attached to the bevel gear 7 can be improved for a structure in which the boss outer diameter D of the bevel gear 7 exceeds h7, or a structure in which the concentricity of the boss outer diameter D relative to the boss inner diameter d of the bevel gear 7 exceeds 0.03 mm. The boss end face 7a of the bevel gear 7 has a perpendicularity of 0.05 mm or less with respect to the boss inner diameter d of the bevel gear 7 into which the bearing 3 is fitted. This makes it possible to appropriately attach the end effector to the bevel gear 7 with high precision.

[0033] 3 and 4, the boss side surface 7b and end surface 7a of the bevel gear 7 are provided with screw holes 20 for attaching an end effector. A plurality of screw holes 20 are provided at equal intervals in the boss end surface 7a, and each screw hole 20 is formed to extend parallel to the second rotation axis direction. The screw holes 20 provided in the boss side surface 7b are formed to extend in a radial direction perpendicular to the second rotation axis direction. In this case, the end effector can be easily attached to and detached from the bevel gear 7.

[0034] A boss end face 7a of the bevel gear 7, which is the second rotating member, is provided with a mounting hole 22 in which a pin 21 can be installed to ensure reproducibility of the mounting of the end effector and prevent misalignment in the rotational direction. The mounting hole 22 extends parallel to the second rotation axis direction. For example, a knock pin or the like is used as the pin 21. In this case, by installing the pin 21 in the mounting hole 22 in the boss end face 7a of the bevel gear 7, it is possible to ensure reproducibility of the mounting of the end effector and prevent misalignment in the rotational direction, and the end effector can be easily attached to and detached from the bevel gear 7.

[0035] As shown in Fig. 5A, in order to ensure the repeatability of the attachment of the end effector, a shoulder 23 that regulates the attachment position of the end effector in the second rotation axis direction is provided on the boss outer diameter D of the bevel gear 7, which is the second rotating member. Furthermore, the radius R of a corner 23a of the shoulder 23 is 0.2 mm or less, or as shown in Fig. 5B, a recess 24 is provided at the corner of the shoulder 23. In this case, when the end effector is fitted onto the boss outer diameter D of the bevel gear 7, the end effector reliably abuts against the shoulder 23, and the repeatability of the attachment position of the end effector in the second rotation axis direction can be ensured.

[0036] <Action and effect> According to the wrist joint unit HU of FIG. 1 described above, the first rotating member 6 is supported by the arm 5 at one end, and the bevel gear 7, which is the second rotating member, is supported by the first rotating member 6 at one end, so that the first and second rotating members 6, 7 can increase the degree of freedom of rotational movement without interfering with the first and second motors 9, 10 (FIG. 2) and supporting members. In addition, because the first and second rotating members 6, 7 are supported by one end, the size and weight can be reduced compared to a structure in which the first and second rotating members 6, 7 are supported by both ends. The first and second motors 9, 10 (FIG. 2) are not rotating members that perform rotational movement, but are supported by the arm 5, which serves as the base, so that the motor body does not move. This allows the first and second rotating members 6, 7 to be lightweight and compact. Furthermore, because the end effector 11 is attached to the bevel gear 7, which is the second rotating member, the number of parts is reduced, and a compact and lightweight wrist joint unit HU can be realized.

[0037] The wrist joint unit HU further includes a bevel gear 12 that meshes with the bevel gear 7, and a gear shaft 19 to which the bevel gear 12 is fixed and which is rotatably supported by the arm 5 and the first rotating member 6 via bearings 4 and 2. The first rotating member 6 is rotatably supported by the arm 5 via a bearing 1, and the bearing 1 and the bearing 4 that rotatably supports the gear shaft 19 by the arm 5 are provided coaxially. Therefore, by rotating both the first and second motors 9 and 10 (FIG. 2) in an appropriate relationship, the bevel gear 7, which is the second rotating member, can be rotated only around the first rotating axis C1. By rotating only the second motor 10 (FIG. 2) without rotating the first motor 9, the bevel gear 7, which is the second rotating member, can be rotated only around the second rotating axis C2.

[0038] <Other embodiments> At least one of the bearings 1, 2, 3, and 4 may be replaced with a rolling bearing other than a deep groove ball bearing. However, a rolling bearing capable of receiving radial and axial loads is applied. For example, an angular ball bearing, a four-point contact ball bearing, a tapered roller bearing, a cross roller bearing, etc. can be used as such a rolling bearing. It is also possible to use a sliding bearing instead of the rolling bearing. An end effector may be attached to the bevel gear, which is the second rotating member, via an intermediate member such as a tool changer.

[0039] <Work equipment> <Cartesian robot: Fig. 6A> As shown in Fig. 6A, a Cartesian robot (working device) 25 equipped with a wrist joint unit HU may be used. An XZ stage that moves in two orthogonal axial directions of the X-axis and the Z-axis is applied to the Cartesian robot 25 in this example. The Cartesian robot 25 includes an X-axis electric actuator 26 and a Z-axis electric actuator 27 that respectively correspond to the X-axis and the Z-axis that are orthogonal to each other. The Z-axis electric actuator 27 has a pillar part 29 that extends in the Z-axis direction, which is the up-down direction in Fig. 6A, on a support base 28, a guide part 30 fixed to one side of the pillar part 29, a Z-axis stage 31 that slides along the guide part 30, a Z-axis motor 32 that is a drive source of the Z-axis stage 31, and a conversion mechanism such as a ball screw (not shown) that converts the rotation of the Z-axis motor 32 into a linear reciprocating motion along the Z-axis.

[0040] The X-axis electric actuator 26 has a guide section 33 supported by the Z-axis stage 31 and extending along the X-axis direction, which is the left-right direction in Fig. 6A, an X-axis stage 34 that slides along the guide section 33, an X-axis motor 35 that is the drive source of the X-axis stage 34, and a conversion mechanism such as a ball screw (not shown) that converts the rotation of the X-axis motor 35 into a linear reciprocating motion along the X-axis. A wrist joint unit HU is connected to the X-axis stage 34 via a bracket 36 or the like. A first rotation axis C1 of this wrist joint unit HU is arranged, for example, parallel to the Z-axis.

[0041] A Y-axis electric actuator 37 in the Y-axis direction perpendicular to the X-axis and Z-axis is provided on the support base 28. The Y-axis electric actuator 37 has a guide portion 38 extending along the Y-axis direction on the support base 28, a Y-axis stage 39 sliding along the guide portion 38, a Y-axis motor 40 which is a drive source for the Y-axis stage 39, and a conversion mechanism such as a ball screw (not shown) which converts the rotation of the Y-axis motor 40 into a linear reciprocating motion along the Y-axis. A workpiece W is placed on the Y-axis stage 40.

[0042] The Cartesian robot 25, the Y-axis electric actuator 37 and each motor of the wrist joint unit HU are controlled in cooperation with each other by a control device (not shown). As a result, the Cartesian robot 25 positions the end effector 11 attached to the tip of the wrist joint unit HU with respect to the workpiece W to perform a desired task. This working device makes it possible to work in narrower spaces, close to walls, or by arranging multiple devices with close spacing between them, compared to working devices using conventional wrist joint units.

[0043] <Scalar robot: Figure 6B> As shown in FIG. 6B, a SCARA robot (working device) 41 equipped with a wrist joint unit HU may be used. In this SCARA robot 41, a first arm 44 on the base end side is provided rotatably around the Z-axis direction via a rotation mechanism 43 on a rotation drive source provided on a base unit 42. A second arm 46 is provided on the tip of the first arm 44 rotatably around the Z-axis direction via a rotation mechanism 45. A wrist joint unit HU is connected to the tip of the second arm 45 via a linear guide mechanism 47 that can be moved and driven in the Z-axis direction. The first rotation axis C1 of this wrist joint unit HU is also arranged parallel to the Z-axis. The workpiece W is placed and supported on a support table 28.

[0044] The motors of the SCARA robot 41 and the wrist joint unit HU are controlled in cooperation with each other by a control device (not shown). This allows the SCARA robot 41 to position the end effector 11 attached to the tip of the wrist joint unit HU with respect to the workpiece W to perform the desired work. This working device can also work in narrower spaces, near walls, or with multiple units lined up at close intervals, compared to working devices using conventional wrist joint units.

[0045] Although not shown, for example, a wrist joint unit may be provided at the tip of a four-axis or less vertical articulated robot. Of course, a wrist joint unit can also be provided at the tip of a five-axis or six-axis vertical articulated robot. In this case as well, the same effects as those described above can be achieved.

[0046] Although the embodiment of the present invention has been described above, the disclosed embodiment is illustrative in all respects and is not restrictive. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0047] Reference Signs List: 1 to 4... bearings, 5... arm, 6... first rotating member, 7... bevel gear (second rotating member), 9... first motor, 10... second motor, 11... end effector, 12... bevel gear, 19... gear shaft, 20... screw hole, 21... pin, 22... mounting hole, 23... shoulder, 24... steal, 25... Cartesian robot (working device), 26... SCARA robot (working device)

Claims

1. An arm, a first rotating member supported by the arm in a cantilever manner and rotatable about a first rotation axis; a bevel gear that is a second rotating member that is cantilevered on the first rotating member and rotatably provided around a second rotation axis that is perpendicular to the first rotation axis; a first motor supported by the arm and configured to rotate the first rotating member; a second motor supported by the arm and configured to rotate the bevel gear; The bevel gear is a wrist joint unit to which an end effector can be attached.

2. The wrist joint unit according to claim 1, further comprising: a bevel gear that meshes with the bevel gear; and a gear shaft to which the bevel gear is fixed and which is rotatably supported by the arm and the first rotating member via bearings (2, 4), The first rotating member is rotatably supported relative to the arm via a bearing (1), and this bearing (1) and a bearing (4) that rotatably supports the gear shaft relative to the arm are provided coaxially.

3. 3. The wrist joint unit according to claim 1 or 2, wherein the boss outer diameter D of the bevel gear which is the second rotating member has a tolerance range class of h7 or less or g6 or less in dimensional tolerances used in commonly used fitting shafts, and the boss outer diameter D has a concentricity of 0.03 mm or less with respect to the boss inner diameter d of the bevel gear which fits a bearing (3).

4. 3. The wrist joint unit according to claim 1, wherein the boss end face of the bevel gear which is the second rotating member has a perpendicularity of 0.05 mm or less with respect to the boss inner diameter d of the bevel gear which fits a bearing (3).

5. 3. A wrist joint unit according to claim 1, wherein a screw hole for mounting the end effector is provided on a boss side surface and an end surface of the bevel gear which is the second rotating member.

6. 3. The wrist joint unit according to claim 1 or 2, wherein a mounting hole is provided on an end surface of a boss of the bevel gear which is the second rotating member, and into which a pin can be installed to ensure repeatability of mounting the end effector and to prevent deviation in the rotational direction.

7. 3. The wrist joint unit according to claim 1 or 2, wherein a shoulder is provided on an outer diameter D of a boss of the bevel gear which is the second rotating member, for regulating an attachment position in the second axis direction of the end effector, and a corner of the shoulder has a radius R of 0.2 mm or less, or a corner of the shoulder is recessed.

8. A working device comprising the wrist joint unit according to claim 1 or 2.

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