Centering structures, machines and robots

Abstract

A centering mechanism being provided with a speed reducer, a bearing that is disposed radially outward from the center line of the speed reducer, and an adapter that is fixed to the speed reducer and maintains the speed reducer and the bearing to be coaxial.

Description

[Technical field]

[0001] The present invention relates to a machine centering technique, and more particularly to a centering structure, a machine, and a robot. [Background technology]

[0002] In large robots that transport heavy objects, the load on the joints of the robot is large, so a structure is known in which the bearings that support the load are not built into the reducer but are installed separately. In such a structure, since there is no bearing inside the reducer, it is necessary to make the reducer and the bearing concentric (also called centering, center alignment, axis alignment, centering, etc.). If the reducer and the bearing are assembled with the axial center misaligned, vibrations will occur, leading to early damage to the machine and deterioration of the positioning accuracy of the machine. The documents listed below are known as background art related to this application.

[0003] Patent Document 1 describes a rotary joint for a robot or the like, in which a cross-roller type bearing is arranged on a fixed base, a reducer case is rotatably supported on the inner ring of the bearing, and the reducer case is fixed to a rotating body.

[0004] Patent document 2 describes a structure for restricting the axial movement of the planetary member of a reduction gear device, in which the internal gear (case) of the reduction gear contacts only a portion of the axial direction of the inner ring of the bearing, a pressure ring is fitted into the part of the inner ring of the bearing where the internal gear is not present, and the pressure ring restricts the axial movement of the planetary gear. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-108485 [Patent Document 2] JP 2002-295605 A Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE PRESENT EMBODIMENT In view of the problems in the related art, an object of the present invention is to provide a technique for achieving concentricity between a reducer and a bearing. [Means for solving the problem]

[0007] One aspect of the present disclosure is a reducer, a bearing disposed radially outward from a center line of the reducer, and an adapter fixed to the reducer to maintain the concentricity of the reducer and the bearing; a first link that fixes the reducer and the bearing; and a second link that fits the adapter; The present invention provides a centering structure comprising: Another aspect of the present disclosure is a reducer; a bearing disposed radially outward from a center line of the reducer; an adapter fixed to the reducer; and a first link for fixing the reducer and the bearing, wherein the adapter maintains a concentric relationship between a shaft of the reducer and the bearing, and the first link maintains a concentric relationship between a case of the reducer and the bearing, or the adapter maintains a concentric relationship between a case of the reducer and the bearing, and the first link maintains a concentric relationship between the shaft of the reducer and the bearing, Provide a centering structure. Another aspect of the present disclosure provides a machine or robot equipped with such a centering structure. Effect of the Invention

[0008] According to one aspect of the present disclosure, the adapter that keeps the reducer and the bearing concentric can align the axial centers of the reducer and the bearing, thereby reducing vibration of the reducer and suppressing damage to the reducer. According to another aspect of the present disclosure, the axial centers of the reducer and the bearing can be aligned by a link that keeps the reducer and the bearing concentric, thereby reducing vibration of the reducer and suppressing damage to the reducer. According to another aspect of the present disclosure, by providing a machine or robot with such a centering structure, vibrations of the machine or robot are reduced, thereby suppressing damage to the machine or robot and improving the positioning accuracy of the machine or robot. [Brief description of the drawings]

[0009] [Figure 1] 1 is an overall view of a machine equipped with a centering structure of a first embodiment; [Diagram 2] FIG. 2 is a cross-sectional view of the centering structure of the first embodiment taken along line II-II. [Diagram 3] FIG. 2 is a cross-sectional view of the centering structure according to the second embodiment taken along line II-II. [Figure 4] FIG. 2 is a cross-sectional view of the centering structure according to the third embodiment taken along line II-II. [Diagram 5] FIG. 21 is a cross-sectional view taken along line II-II of the centering structure of the fourth embodiment. [Figure 6] FIG. 21 is a cross-sectional view taken along line II-II of the centering structure of the fifth embodiment. [Figure 7] FIG. 21 is a cross-sectional view taken along line II-II of the centering structure of the sixth embodiment. [Figure 8] FIG. 21 is a cross-sectional view taken along line II-II of the centering structure of the seventh embodiment. [Figure 9] FIG. 2 is a cross-sectional view taken along line II-II of the structure of the comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In each drawing, the same or similar components are given the same or similar reference numerals. In addition, the embodiments described below do not limit the technical scope and meaning of the terms of the invention described in the claims.

[0011] A machine equipped with the centering structure of the first embodiment will be described in detail. Fig. 1 is an overall view of a machine 1 equipped with the centering structure of the first embodiment. It should be noted that the machine 1 of this embodiment is an industrial robot, particularly an articulated robot, but in other embodiments, it may be other types of robots such as a single-articulated robot, a parallel link type robot, a humanoid robot, etc. In another embodiment, the machine 1 may be an industrial machine such as a machine tool, a construction machine, an agricultural machine, etc., or another machine such as a vehicle, an aircraft, etc.

[0012] The machine 1 includes a plurality of links 11-17 that are rotatably connected, but in other embodiments, the machine 1 may include a plurality of links that are translatably connected. The machine 1 includes rotary joints between the plurality of links 11-17, but in other embodiments, the machine 1 may include translatory joints between the plurality of links 11-17.

[0013] The first link 11 is a fixed base fixed in a predetermined position, and the second link 12 is a rotating body supported rotatably relative to the first link 11 about a first axis J1. The third link 13 is an upper arm supported rotatably relative to the second link 12 about a second axis J2 perpendicular to the first axis J1, and the fourth link 14 is a forearm supported rotatably relative to the third link 13 about a third axis J3 parallel to the second axis J2. The fifth link 15, the sixth link 16, and the seventh link 17 are a three-axis wrist unit 18 attached to the fourth link.

[0014] The fifth link 15 is a first wrist element supported relative to the fourth link 14 for rotation about a fourth axis J4 perpendicular to the third axis J3, the sixth link 16 is a second wrist element supported relative to the fifth link 15 for rotation about a fifth axis J5 perpendicular to the fourth axis J4, and the seventh link 17 is a third wrist element supported relative to the sixth link 16 for rotation about a sixth axis J6 perpendicular to the fifth axis J5.

[0015] The machine 1 is provided with an actuator 10 including various machine elements such as an electric motor, a reducer, and bearings at the joints between the multiple links 11 to 17. The actuator 10 is structured so that the bearings are not built into the reducer but are placed separately in order to support a relatively large load. In this structure, since there are no bearings inside the reducer, it is necessary to make the reducer and the bearings concentric (also called centering, center alignment, axis alignment, centering, etc.). If the reducer and the bearing are assembled with their axial centers misaligned, vibrations will occur, leading to premature damage to the reducer. This will ultimately lead to premature damage to the machine and deterioration of the positioning accuracy of the machine. Therefore, the machine 1 or the actuator 10 is provided with a centering structure that can align the axial centers of the reducer and the bearings.

[0016] 2 is a cross-sectional view taken along line II-II of the centering structure of the first embodiment. The centering structure of this embodiment is a joint structure (joint structure of the first axis J1) between the first link 11 and the second link 12, but it should be noted that in other embodiments, the centering structure can also be applied to joint structures (joint structures of the other axes J2-J6) between the other links 12-17. The actuator 10 is composed of an electric motor 20, a reducer 40, a bearing 50, and an adapter 60, and the centering structure of this embodiment includes the reducer 40, the bearing 50, the adapter 60, the first link 11, and the second link 12.

[0017] The electric motor 20 includes a rotating shaft 21 and a motor-side gear 22 connected to the rotating shaft 21. The reducer 40 includes a central gear 41 meshing with the motor-side gear 22, a plurality of orbital gears 42 meshing with the central gear 41, a shaft 43 rotatably supporting the plurality of orbital gears 42, and a case 44 meshing with the shaft 43. The reducer 40 of this embodiment is configured as a planetary gear reducer, in which the central gear 41 corresponds to the sun gear, the orbital gears 42 correspond to the planetary gears, the shaft 43 corresponds to the planet carrier, and the case 44 corresponds to the internal gear. It should be noted that in other embodiments, the reducer 40 may be configured as another type of reducer, such as a strain wave gear reducer.

[0018] The bearing 50 includes an inner ring 51, an outer ring 52, and a rolling element 53 that rolls between the inner ring 51 and the outer ring 52. The bearing 50 is disposed radially outward from the center line of the reducer 40. The bearing 50 is disposed radially outward from the outermost diameter of the reducer 40, but in other embodiments, the inner ring 51 of the bearing 50 may be disposed radially inward from the outermost diameter of the reducer 40, and the outer ring 52 of the bearing 50 may be disposed radially outward from the outermost diameter of the reducer 40. In addition, since the bearing 50 is disposed between the top surface and the bottom surface of the reducer 40, the centering structure (i.e., the joint structure) can be made compact. The bearing 50 of this embodiment is configured as a cross roller bearing that can support loads in various directions, such as axial loads, radial loads, and moment loads. In other embodiments, the bearing 50 may be configured as other types of bearings, such as an angular ball bearing or a tapered roller bearing. The adapter 60 is a flanged cylindrical body and includes a cylindrical portion 62, an inner flange 61 extending inwardly from the cylindrical portion 62, a first outer flange 63 extending outwardly from the cylindrical portion 62, and a second outer flange 64 extending outwardly from the cylindrical portion 62.

[0019] The electric motor 20 is fixed to the second link 12, the reducer 40 is fixed to the first link 11 and the adapter 60, the bearing 50 is fixed to the first link 11 and the second link 12, and the adapter 60 is fixed to the reducer 40 and the second link 12. Specifically, the case 44 of the reducer 40 is fixed to the first link 11 with screws 30, and the shaft 43 of the reducer 40 is fixed to the inner flange 61 of the adapter 60 with screws 31. The outer ring 52 of the bearing 50 is fixed to the first link 11 with screws (not shown) or the like, and the inner ring 51 of the bearing 50 is fixed to the second link 12 with screws 32. The first outer flange 63 of the adapter 60 is fixed to the second link 12 with screws 33.

[0020] The electric motor 20 rotates the rotating shaft 21 and the motor side gear 22, and transmits torque from the motor side gear 22 to the central gear 41 of the reducer 40. The reducer 40 reduces the rotation speed of the central gear 41, the orbiting gear 42, and the shaft 43, in that order, and transmits a larger torque from the shaft 43 to the adapter 60. The adapter 60 rotates to transmit the torque to the second link 12, and the bearing 50 supports the second link 12 for rotation. The bearing 50 supports the links 12 to 17 of the machine 1 and the load applied to the tip of the machine 1.

[0021] Since the outer diameter of the case 44 of the reducer 40 is smaller than the inner diameter of the bearing 50, it is necessary to ensure that the case 44 of the reducer 40 and the bearing 50 are concentric. The first link 11 includes a fitting portion 70 that fits into the outer ring 52 of the bearing 50, and a fitting portion 71 that fits into the case 44 of the reducer 40, thereby enabling the case 44 of the reducer 40 and the bearing 50 to be concentric. The fitting portions 70 and 71 are, for example, stepped holes. The first link 11 keeps the case 44 of the reducer 40 and the bearing 50 concentric, so that the axial centers of the case 44 of the reducer 40 and the bearing 50 are aligned with the first axis J1.

[0022] In addition, since the outer diameter of the shaft 43 of the reducer 40 is smaller than the inner diameter of the bearing 50 and the inner diameter of the second link 12, the adapter 60 complements the size difference between the shaft 43 of the reducer 40, the bearing 50, and the second link 12, and maintains the concentricity of the shaft 43 of the reducer 40, the bearing 50, and the second link 12. The inner flange 61 of the adapter 60 has a fitting portion 72 that fits into the shaft 43 of the reducer 40, the outer peripheral surface of the second outer flange 64 of the adapter 60 is inscribed in the inner ring 51 of the bearing 50 (contacts the inner peripheral surface), and the second link 12 has a fitting portion 73 that fits into the first outer flange 63 of the adapter 60, so that the shaft 43 of the reducer 40, the bearing 50, and the second link 12 can be concentric. The fitting portions 72 and 73 are, for example, stepped holes. The adapter 60, which keeps the shaft 43 of the reducer 40, the bearing 50, and the second link 12 concentric, aligns the axial centers of the shaft 43 of the reducer 40, the bearing 50, and the second link 12 with the first axis J1.

[0023] The shaft 43 and case 44 of the reducer 40 may be assembled with their respective axial centers misaligned due to a gap between the shaft 43 and case 44 (e.g., a gap between gears). However, the adapter 60 keeps the shaft 43 and bearing 50 of the reducer 40 concentric, and the first link 11 keeps the case 44 of the reducer 40 concentric with the bearing 50, so that the axial centers of the shaft 43 and case 44 of the reducer 40 are also aligned with the first axis J1.

[0024] According to the centering structure of the first embodiment described above, the adapter 60 that keeps the reducer 40 and the bearing 50 concentric, aligns the axial centers of the reducer 40 and the bearing 50, thereby reducing vibration of the reducer 40 and suppressing damage to the reducer 40. In particular, the adapter 60 that keeps the shaft 43 of the reducer 40 and the bearing 50 concentric, and the first link 11 that keeps the case 44 of the reducer 40 and the bearing 50 concentric, align the axial centers of the shaft 43 and the case 44 of the reducer 40, thereby reducing vibration when the shaft 43 and the case 44 of the reducer 40 are assembled with their axial centers misaligned, and suppressing damage to the reducer 40. Furthermore, by providing the machine 1 with such a centering structure, vibration of the machine 1 is reduced, suppressing damage to the machine 1 and improving the positioning accuracy of the machine 1.

[0025] The centering structure of the second embodiment will be described below. Fig. 3 is a cross-sectional view of the centering structure of the second embodiment taken along the line II-II. The centering structure of the second embodiment differs from the centering structure of the first embodiment in that the shaft 43 of the reducer 40 is fixed to the first link 11 with a screw 31, and the case 44 of the reducer 40 is fixed to the inner flange 61 of the adapter 60 with a screw 30.

[0026] The electric motor 20 rotates the rotating shaft 21 and the motor side gear 22, and transmits torque from the motor side gear 22 to the central gear 41 of the reducer 40. The reducer 40 rotates at a reduced speed through the central gear 41, the orbiting gear 42, and the case 44, in that order, and transmits a larger torque from the case 44 to the adapter 60. The adapter 60 rotates and transmits the torque to the second link 12, and the bearing 50 supports the second link 12 for rotation. The bearing 50 supports the links 12 to 17 of the machine 1 and the load applied to the tip of the machine 1.

[0027] In the second embodiment, since the case 44 of the reducer 40 rotates, the first link 11 does not have a fitting portion 71 that fits into the case 44 of the reducer 40 as in the first embodiment. The first link 11 has a fitting portion 70 that fits into the outer ring 52 of the bearing 50 and a screw hole into which the shaft 43 of the reducer 40 is fastened with a screw 31, so that the shaft 43 of the reducer 40 and the bearing 50 can be made concentric. In other words, the screw hole of the first link 11 that fastens the shaft 43 of the reducer 40 is precisely machined to position the shaft 43 of the reducer 40. The first link 11 that maintains the concentricity of the shaft 43 of the reducer 40 and the bearing 50 aligns the axial centers of the shaft 43 of the reducer 40 and the bearing 50 with the first axis J1.

[0028] In addition, since the outer diameter of the case 44 of the reducer 40 is smaller than the inner diameter of the bearing 50 and the inner diameter of the second link 12, the adapter 60 complements the size difference between the case 44 of the reducer 40, the bearing 50, and the second link 12, and maintains the concentricity of the case 44 of the reducer 40, the bearing 50, and the second link 12. The inner flange 61 of the adapter 60 has a fitting portion 72 that fits into the case 44 of the reducer 40, the outer peripheral surface of the second outer flange 64 of the adapter 60 is inscribed in the inner ring 51 of the bearing 50 (contacts the inner peripheral surface), and the second link 12 has a fitting portion 73 that fits into the first outer flange 63 of the adapter 60, so that the case 44 of the reducer 40, the bearing 50, and the second link 12 can be concentrically aligned. The adapter 60, which keeps the case 44, bearing 50, and second link 12 of the reducer 40 concentric, aligns the axial centers of the case 44, bearing 50, and second link 12 of the reducer 40 with the first axis J1.

[0029] The shaft 43 and case 44 of the reducer 40 may be assembled with their respective axial centers misaligned due to a gap between the shaft 43 and case 44 (e.g., a gap between gears). However, the adapter 60 keeps the case 44 of the reducer 40 and the bearing 50 concentric, and the first link 11 keeps the shaft 43 of the reducer 40 and the bearing 50 concentric, so that the axial centers of the shaft 43 and case 44 of the reducer 40 are also aligned with the first axis J1.

[0030] According to the centering structure of the second embodiment described above, the adapter 60 that keeps the reducer 40 and the bearing 50 concentrically aligned aligns the axial centers of the reducer 40 and the bearing 50, thereby reducing vibration of the reducer 40 and suppressing damage to the reducer 40. In particular, the adapter 60 that keeps the case 44 of the reducer 40 and the bearing 50 concentrically aligned and the first link 11 that keeps the shaft 43 of the reducer 40 and the bearing 50 concentrically aligned align the axial centers of the shaft 43 and the case 44 of the reducer 40, thereby reducing vibration when the shaft 43 and the case 44 of the reducer 40 are assembled with their axial centers misaligned, thereby suppressing damage to the reducer 40. Furthermore, by providing the machine 1 with such a centering structure, vibration of the machine 1 is reduced, thereby suppressing damage to the machine 1 and improving the positioning accuracy of the machine 1.

[0031] The centering structure of the third embodiment will be described below. Fig. 4 is a cross-sectional view of the centering structure of the third embodiment taken along line II-II. The centering structure of the third embodiment differs from the centering structure of the first embodiment in that the adapter 60 is not fixed to the second link 12 but is fixed to the bearing 50. Specifically, the cylindrical portion 62 of the adapter 60 is fixed to the inner peripheral surface of the inner ring 51 of the bearing 50 by the screw 34. The adapter 60 also differs from the centering structure of the first embodiment in that it does not include a first outer flange 63 and a second outer flange 64, but only includes an inner flange 61 and a cylindrical portion 62. In other words, the adapter 60 is configured in a simpler shape.

[0032] The electric motor 20 rotates the rotating shaft 21 and the motor side gear 22, and transmits torque from the motor side gear 22 to the central gear 41 of the reducer 40. The reducer 40 reduces the rotation speed of the central gear 41, the orbiting gear 42, and the shaft 43 in that order, and transmits a larger torque from the shaft 43 to the adapter 60. The adapter 60 rotates and transmits the torque to the inner ring 51 of the bearing 50, and the inner ring 51 of the bearing 50 rotates and transmits the torque to the second link 12. The bearing 50 supports the load applied to the links 12 to 17 of the machine 1 and the tip of the machine 1.

[0033] Since the outer diameter of the case 44 of the reducer 40 is smaller than the inner diameter of the bearing 50, it is necessary to ensure that the case 44 of the reducer 40 and the bearing 50 are concentric. The first link 11 includes a fitting portion 70 that fits into the outer ring 52 of the bearing 50, and a fitting portion 71 that fits into the case 44 of the reducer 40, thereby enabling the case 44 of the reducer 40 and the bearing 50 to be concentric. The first link 11 maintains the concentricity of the case 44 of the reducer 40 and the bearing 50, so that the axial centers of the case 44 of the reducer 40 and the bearing 50 are aligned with the first axis J1.

[0034] In addition, since the outer diameter of the shaft 43 of the reducer 40 is smaller than the inner diameter of the bearing 50 and the inner diameter of the second link 12, the adapter 60 complements the size difference between the shaft 43 of the reducer 40, the bearing 50, and the second link 12, and maintains the concentricity of the shaft 43 of the reducer 40, the bearing 50, and the second link 12. The inner flange 61 of the adapter 60 has a fitting portion 72 that fits into the shaft 43 of the reducer 40, the outer peripheral surface of the cylindrical portion 62 of the adapter 60 is inscribed in the inner ring 51 of the bearing 50 (contacts the inner peripheral surface), and the second link 12 has a fitting portion 73 that fits into the cylindrical portion 62 of the adapter 60, so that the shaft 43 of the reducer 40, the bearing 50, and the second link 12 can be concentrically aligned. The adapter 60, which keeps the shaft 43 of the reducer 40, the bearing 50, and the second link 12 concentric, aligns the axial centers of the shaft 43 of the reducer 40, the bearing 50, and the second link 12 with the first axis J1.

[0035] The shaft 43 and case 44 of the reducer 40 may be assembled with their respective axial centers misaligned due to a gap between the shaft 43 and case 44 (e.g., a gap between gears). However, the adapter 60 keeps the shaft 43 and bearing 50 of the reducer 40 concentric, and the first link 11 keeps the case 44 of the reducer 40 concentric with the bearing 50, so that the axial centers of the shaft 43 and case 44 of the reducer 40 are also aligned with the first axis J1.

[0036] According to the centering structure of the third embodiment described above, the adapter 60 that keeps the reducer 40 and the bearing 50 concentrically aligned aligns the axial centers of the reducer 40 and the bearing 50, thereby reducing vibration of the reducer 40 and suppressing damage to the reducer 40. In particular, the adapter 60 that keeps the shaft 43 of the reducer 40 and the bearing 50 concentrically aligned and the first link 11 that keeps the case 44 of the reducer 40 and the bearing 50 concentrically aligned align the axial centers of the shaft 43 and the case 44 of the reducer 40, thereby reducing vibration when the shaft 43 and the case 44 of the reducer 40 are assembled with the axial centers misaligned, and suppressing damage to the reducer 40. Furthermore, by providing the machine 1 with such a centering structure, vibration of the machine 1 is reduced, thereby suppressing damage to the machine 1 and improving the positioning accuracy of the machine 1. Furthermore, since the adapter 60 is configured in a simple shape, the centering accuracy of the adapter 60 can be improved.

[0037] The centering structure of the fourth embodiment will be described below. Fig. 5 is a cross-sectional view of the centering structure of the fourth embodiment taken along line II-II. The centering structure of the fourth embodiment differs from the centering structure of the first embodiment in that the inner ring 51 of the bearing 50 is fixed to the first link 11 with a screw (not shown) or the like, and the outer ring 52 of the bearing 50 is fixed to the second link 12 via an adapter 60 with a screw 32. The centering structure of the fourth embodiment is also different from the centering structure of the first embodiment in that the adapter 60 does not include a first outer flange 63, and the fitting portion 75 of the second outer flange 64 of the adapter 60 circumscribes the outer ring 52 of the bearing 50 (contacts the outer peripheral surface).

[0038] The electric motor 20 rotates the rotating shaft 21 and the motor side gear 22, and transmits torque from the motor side gear 22 to the central gear 41 of the reducer 40. The reducer 40 reduces the rotation speed of the central gear 41, the orbiting gear 42, and the shaft 43, in that order, and transmits a larger torque from the shaft 43 to the adapter 60. The adapter 60 rotates to transmit the torque to the second link 12, and the bearing 50 supports the second link 12 for rotation. The bearing 50 supports the links 12 to 17 of the machine 1 and the load applied to the tip of the machine 1.

[0039] Since the outer diameter of the case 44 of the reducer 40 is smaller than the inner diameter of the bearing 50, it is necessary to make the case 44 of the reducer 40 and the bearing 50 concentric. The first link 11 includes a fitting portion 70 that fits into the inner ring 51 of the bearing 50 and a fitting portion 71 that fits into the case 44 of the reducer 40, thereby making it possible to make the case 44 of the reducer 40 and the bearing 50 concentric. The fitting portion 70 is, for example, a stepped flange, and the fitting portion 71 is, for example, a stepped hole. The first link 11 keeps the case 44 of the reducer 40 and the bearing 50 concentric, so that the axial centers of the case 44 of the reducer 40 and the bearing 50 are aligned with the first axis J1.

[0040] In addition, since the outer diameter of the shaft 43 of the reducer 40 is smaller than the inner diameter of the bearing 50 and the inner diameter of the second link 12, the adapter 60 complements the size difference between the shaft 43 of the reducer 40, the bearing 50, and the second link 12, and maintains the concentricity of the shaft 43 of the reducer 40, the bearing 50, and the second link 12. The inner flange 61 of the adapter 60 has a fitting portion 72 that fits into the shaft 43 of the reducer 40, the second outer flange 64 of the adapter 60 has a fitting portion 75 that circumscribes the outer ring 52 of the bearing 50, and the second link 12 has a fitting portion 73 that fits into the cylindrical portion 62 of the adapter 60, thereby making it possible to maintain the concentricity of the shaft 43 of the reducer 40, the bearing 50, and the second link 12. The fitting portions 72, 75, and 73 are, for example, stepped holes. The adapter 60, which keeps the shaft 43 of the reducer 40, the bearing 50, and the second link 12 concentric, aligns the axial centers of the shaft 43 of the reducer 40, the bearing 50, and the second link 12 with the first axis J1.

[0041] The shaft 43 and case 44 of the reducer 40 may be assembled with their respective axial centers misaligned due to a gap between the shaft 43 and case 44 (e.g., a gap between gears). However, the adapter 60 keeps the shaft 43 and bearing 50 of the reducer 40 concentric, and the first link 11 keeps the case 44 of the reducer 40 concentric with the bearing 50, so that the axial centers of the shaft 43 and case 44 of the reducer 40 are also aligned with the first axis J1.

[0042] According to the centering structure of the fourth embodiment described above, the adapter 60 that keeps the reducer 40 and the bearing 50 concentric, aligns the axial centers of the reducer 40 and the bearing 50, thereby reducing vibration of the reducer 40 and suppressing damage to the reducer 40. In particular, the adapter 60 that keeps the shaft 43 of the reducer 40 and the bearing 50 concentric, and the first link 11 that keeps the case 44 of the reducer 40 and the bearing 50 concentric, align the axial centers of the shaft 43 and the case 44 of the reducer 40, thereby reducing vibration when the shaft 43 and the case 44 of the reducer 40 are assembled with the axial centers misaligned, and suppressing damage to the reducer 40. Furthermore, by providing the machine 1 with such a centering structure, vibration of the machine 1 is reduced, suppressing damage to the machine 1 and improving the positioning accuracy of the machine 1.

[0043] The centering structure of the fifth embodiment will be described below. Fig. 6 is a cross-sectional view of the centering structure of the fifth embodiment taken along line II-II. The centering structure of the fifth embodiment differs from the centering structure of the first embodiment in that the inner ring 51 of the bearing 50 is fixed to the first link 11 with a screw (not shown) or the like, and the outer ring 52 of the bearing 50 is fixed to the second link 12 via an adapter 60 with a screw 32. Furthermore, the centering structure of the fifth embodiment differs from the centering structure of the first embodiment in that the shaft 43 of the reducer 40 is fixed to the first link 11 with a screw 31, and the case 44 of the reducer 40 is fixed to the inner flange 61 of the adapter 60 with a screw 30.

[0044] The electric motor 20 rotates the rotating shaft 21 and the motor side gear 22, and transmits torque from the motor side gear 22 to the central gear 41 of the reducer 40. The reducer 40 rotates at a reduced speed through the central gear 41, the orbiting gear 42, and the case 44, in that order, and transmits a larger torque to the adapter 60 via the case 44. The adapter 60 rotates to transmit the torque to the second link 12, and the bearing 50 supports the second link 12 for rotation. The bearing 50 supports the links 12 to 17 of the machine 1 and the load applied to the tip of the machine 1.

[0045] In the fifth embodiment, since the case 44 of the reducer 40 rotates, the first link 11 does not have a fitting portion 71 that fits into the case 44 of the reducer 40 as in the first embodiment. The first link 11 has a fitting portion 70 that fits into the inner ring 51 of the bearing 50 and a screw hole into which the shaft 43 of the reducer 40 is fastened with a screw 31, so that the shaft 43 of the reducer 40 and the bearing 50 can be made concentric. In other words, the screw hole of the first link 11 that fastens the shaft 43 of the reducer 40 is precisely machined to position the shaft 43 of the reducer 40. The first link 11 that maintains the concentricity of the shaft 43 of the reducer 40 and the bearing 50 aligns the axial centers of the shaft 43 of the reducer 40 and the bearing 50 with the first axis J1.

[0046] In addition, since the outer diameter of the case 44 of the reducer 40 is smaller than the inner diameter of the bearing 50 and the inner diameter of the second link 12, the adapter 60 complements the size difference between the case 44 of the reducer 40, the bearing 50, and the second link 12, and maintains the concentricity of the case 44 of the reducer 40, the bearing 50, and the second link 12. The inner flange 61 of the adapter 60 has a fitting portion 72 that fits into the case 44 of the reducer 40, the second outer flange 64 of the adapter 60 has a fitting portion 75 that circumscribes the outer ring 52 of the bearing 50, and the second link 12 has a fitting portion 73 that fits into the cylindrical portion 62 of the adapter 60, thereby making it possible to maintain the concentricity of the case 44 of the reducer 40, the bearing 50, and the second link 12. The fitting portions 72, 75, and 73 are, for example, stepped holes. The adapter 60, which keeps the case 44, bearing 50, and second link 12 of the reducer 40 concentric, aligns the axial centers of the case 44, bearing 50, and second link 12 of the reducer 40 with the first axis J1.

[0047] The shaft 43 and case 44 of the reducer 40 may be assembled with their respective axial centers misaligned due to a gap between the shaft 43 and case 44 (e.g., a gap between gears). However, the adapter 60 keeps the case 44 of the reducer 40 and the bearing 50 concentric, and the first link 11 keeps the shaft 43 of the reducer 40 and the bearing 50 concentric, so that the axial centers of the shaft 43 and case 44 of the reducer 40 are also aligned with the first axis J1.

[0048] According to the centering structure of the fifth embodiment described above, the adapter 60 that keeps the reducer 40 and the bearing 50 concentric, aligns the axial centers of the reducer 40 and the bearing 50, thereby reducing vibration of the reducer 40 and suppressing damage to the reducer 40. In particular, the adapter 60 that keeps the case 44 of the reducer 40 and the bearing 50 concentric, and the first link 11 that keeps the shaft 43 of the reducer 40 and the bearing 50 concentric, align the axial centers of the shaft 43 and the case 44 of the reducer 40, thereby reducing vibration when the shaft 43 and the case 44 of the reducer 40 are assembled with their axial centers misaligned, and suppressing damage to the reducer 40. Furthermore, by providing the machine 1 with such a centering structure, vibration of the machine 1 is reduced, suppressing damage to the machine 1 and improving the positioning accuracy of the machine 1.

[0049] The centering structure of the sixth embodiment will be described below. Fig. 7 is a cross-sectional view of the centering structure of the sixth embodiment taken along line II-II. The centering structure of the sixth embodiment differs from the centering structure of the first embodiment in that the inner ring 51 of the bearing 50 is fixed to the first link 11 by a screw (not shown) or the like, and the outer ring 52 of the bearing 50 is fixed to the second link 12 by a screw 32 via an adapter 60. Furthermore, the centering structure of the sixth embodiment differs from the centering structure of the first embodiment in that the adapter 60 does not include a first outer flange 63 and a second outer flange 64, but only includes an inner flange 61 and a cylindrical portion 62. In other words, the adapter 60 is configured in a simpler shape.

[0050] The electric motor 20 rotates the rotating shaft 21 and the motor side gear 22, and transmits torque from the motor side gear 22 to a central gear 41 of the reducer 40. The reducer 40 rotates at a reduced speed through the central gear 41, the orbiting gear 42, and the case 44, in that order, and transmits a larger torque from the case 44 to the adapter 60. The adapter 60 rotates and transmits the torque to the second link 12. The bearing 50 supports the load applied to the links 12 to 17 of the machine 1 and the tip of the machine 1.

[0051] In the sixth embodiment, since the case 44 of the reducer 40 rotates, the first link 11 does not have a fitting portion 71 that fits into the case 44 of the reducer 40 as in the fourth embodiment. The first link 11 has a fitting portion 70 that fits into the inner ring 51 of the bearing 50 and a screw hole into which the shaft 43 of the reducer 40 is fastened with a screw 31, so that the shaft 43 of the reducer 40 and the bearing 50 can be made concentric. In other words, the screw hole of the first link 11 that fastens the shaft 43 of the reducer 40 is precisely machined to position the shaft 43 of the reducer 40. The first link 11 that maintains the concentricity of the shaft 43 of the reducer 40 and the bearing 50 aligns the axial centers of the shaft 43 of the reducer 40 and the bearing 50 with the first axis J1.

[0052] In addition, since the outer diameter of the case 44 of the reducer 40 is smaller than the inner diameter of the bearing 50 and the inner diameter of the second link 12, the adapter 60 complements the size difference between the case 44 of the reducer 40, the bearing 50, and the second link 12, and maintains the concentricity of the case 44 of the reducer 40, the bearing 50, and the second link 12. The inner flange 61 of the adapter 60 has a fitting portion 72 that fits into the case 44 of the reducer 40, the cylindrical portion 62 of the adapter 60 has a fitting portion 75 that circumscribes the outer ring 52 of the bearing 50, and the second link 12 has a fitting portion 73 that fits into the cylindrical portion 62 of the adapter 60, so that the case 44 of the reducer 40, the bearing 50, and the second link 12 can be concentrically aligned. The adapter 60, which keeps the case 44, bearing 50, and second link 12 of the reducer 40 concentric, aligns the axial centers of the case 44, bearing 50, and second link 12 of the reducer 40 with the first axis J1.

[0053] The shaft 43 and case 44 of the reducer 40 may be assembled with their respective axial centers misaligned due to a gap between the shaft 43 and case 44 (e.g., a gap between gears). However, the adapter 60 keeps the case 44 of the reducer 40 and the bearing 50 concentric, and the first link 11 keeps the shaft 43 of the reducer 40 and the bearing 50 concentric, so that the axial centers of the shaft 43 and case 44 of the reducer 40 are also aligned with the first axis J1.

[0054] According to the centering structure of the sixth embodiment described above, the adapter 60 that keeps the reducer 40 and the bearing 50 concentric, aligns the axial centers of the reducer 40 and the bearing 50, thereby reducing vibration of the reducer 40 and suppressing damage to the reducer 40. In particular, the adapter 60 that keeps the case 44 of the reducer 40 and the bearing 50 concentric, and the first link 11 that keeps the shaft 43 of the reducer 40 and the bearing 50 concentric, align the axial centers of the shaft 43 and the case 44 of the reducer 40, thereby reducing vibration when the shaft 43 and the case 44 of the reducer 40 are assembled with the axial centers misaligned, and suppressing damage to the reducer 40. Furthermore, by providing the machine 1 with such a centering structure, vibration of the machine 1 is reduced, so that damage to the machine 1 can be suppressed and the positioning accuracy of the machine 1 can be improved. Furthermore, since the adapter 60 is configured in a simple shape, the centering accuracy by the adapter 60 can be improved.

[0055] The centering structure of the seventh embodiment will be described below. FIG. 8 is a cross-sectional view of the centering structure of the seventh embodiment taken along line II-II. The centering structure of the seventh embodiment is different from the centering structure of the first embodiment in that it includes a second link 12 with an adapter 60 integrated therein. Specifically, the second link 12 includes an inner flange 61 and a cylindrical portion 62, and the inner flange 61 of the second link 12 is fixed to the shaft 43 of the reduction gear 40 with a screw 31, and the cylindrical portion 62 of the second link 12 is fixed to the inner ring 51 of the bearing 50 with a screw 32. It should be noted that since the second link 12 is integrated with the adapter 60, the inner diameter D2 of the inner flange 61 of the second link 12 or the inner diameter D2 of a part of the inner flange 61 is formed larger than the outer diameter D1 of the central gear 41 of the reduction gear 40 so that the central gear 41 of the reduction gear 40 can be disposed inside the second link 12 with respect to the inner flange 61 of the second link 12.

[0056] The electric motor 20 rotates the rotating shaft 21 and the motor side gear 22, and transmits torque from the motor side gear 22 to a central gear 41 of the reducer 40. The reducer 40 reduces the rotation speed of the central gear 41, the orbiting gear 42, and the shaft 43, in that order, and transmits a larger torque directly from the shaft 43 to the second link 12. The bearing 50 supports the second link 12 for rotation. The bearing 50 supports the links 12 to 17 of the machine 1 and the load applied to the tip of the machine 1.

[0057] Since the outer diameter of the case 44 of the reducer 40 is smaller than the inner diameter of the bearing 50, it is necessary to ensure that the case 44 of the reducer 40 and the bearing 50 are concentric. The first link 11 includes a fitting portion 70 that fits into the outer ring 52 of the bearing 50, and a fitting portion 71 that fits into the case 44 of the reducer 40, thereby enabling the case 44 of the reducer 40 and the bearing 50 to be concentric. The fitting portions 70 and 71 are, for example, stepped holes. The first link 11 maintains the concentricity of the case 44 of the reducer 40 and the bearing 50, so that the axial centers of the case 44 of the reducer 40 and the bearing 50 are aligned with the first axis J1.

[0058] In addition, since the outer diameter of the shaft 43 of the reducer 40 is smaller than the inner diameter of the bearing 50, the second link 12 compensates for the size difference between the shaft 43 of the reducer 40 and the bearing 50, and maintains the concentricity between the shaft 43 of the reducer 40 and the bearing 50. The inner flange 61 of the second link 12 has a fitting portion 72 that fits into the shaft 43 of the reducer 40, and the cylindrical portion 62 of the second link 12 has a fitting portion 74 that is inscribed in the inner ring 51 of the bearing 50 (contacts the inner peripheral surface), so that the shaft 43 of the reducer 40 and the bearing 50 can be maintained concentric. The fitting portion 72 is, for example, a stepped hole, and the fitting portion 74 is, for example, a stepped flange. The second link 12 that maintains the concentricity between the shaft 43 of the reducer 40 and the bearing 50 aligns the axial centers of the shaft 43 of the reducer 40 and the bearing 50 with the first axis J1.

[0059] The shaft 43 and case 44 of the reducer 40 may be assembled with their respective axial centers misaligned due to a gap between the shaft 43 and case 44 (e.g., a gap between gears). However, the second link 12 keeps the shaft 43 of the reducer 40 and the bearing 50 concentric, and the first link 11 keeps the case 44 of the reducer 40 and the bearing 50 concentric, so that the axial centers of the shaft 43 and case 44 of the reducer 40 are also aligned with the first axis J1.

[0060] According to the centering structure of the seventh embodiment described above, the second link 12 that keeps the reducer 40 and the bearing 50 concentric, aligns the axial centers of the reducer 40 and the bearing 50, thereby reducing vibration of the reducer 40 and suppressing damage to the reducer 40. In particular, the second link 12 that keeps the shaft 43 of the reducer 40 and the bearing 50 concentric, and the first link 11 that keeps the case 44 of the reducer 40 and the bearing 50 concentric, align the axial centers of the shaft 43 and the case 44 of the reducer 40, thereby reducing vibration when the shaft 43 and the case 44 of the reducer 40 are assembled with the axial centers misaligned, and suppressing damage to the reducer 40. Furthermore, by providing the machine 1 with such a centering structure, vibration of the machine 1 is reduced, suppressing damage to the machine 1 and improving the positioning accuracy of the machine 1.

[0061] The centering structure of the comparative example will be described below. Fig. 9 is a cross-sectional view of the centering structure of the comparative example taken along line II-II. In the centering structure of the comparative example, the adapter 80 is a ring-shaped plate body and has only an inner periphery and an outer periphery, which is different from the centering structure of the first embodiment. The inner periphery of the adapter 80 has a fitting portion 72 that fits onto the shaft 43 of the reducer 40, and the second link 12 has a fitting portion 73 that fits onto the outer periphery of the adapter 80, so that the shaft 43 of the reducer 40 and the second link 12 can be coaxially aligned. The fitting portions 72 and 73 are, for example, stepped holes.

[0062] However, since the adapter 80 cannot ensure concentricity between the shaft 43 of the reducer 40 and the bearing 50, in cases where the dimensions of the screw hole for fixing the second link 12 to the inner ring 51 of the bearing 50 with the screw 32 are larger than the screw 32, the second link 12 may be assembled with a deviation in the direction of the arrow S relative to the bearing 50. When the second link 12 is fixed with a deviation in the direction of the arrow S, the adapter 80 fitted to the fitting portion 73 of the second link 12 also deviates in the direction of the arrow S, so that the axis Jo of the shaft 43 of the reducer 40 and the axis Jc of the case 44 are misaligned due to a gap between the shaft 43 of the reducer 40 and the case 44 (for example, a gap between gears). When the shaft 43 of the reducer 40 and the case 44 are assembled with their respective axial centers misaligned, vibration occurs in the reducer 40, which may cause the reducer 40 to break. Furthermore, when vibration occurs in the machine 1, this leads to early damage to the machine 1 and deterioration of the positioning accuracy of the machine 1.

[0063] However, according to the centering structures of the various embodiments described above, the adapter 60 that maintains the concentricity of the reducer 40 and the bearing 50 allows the axial centers of the reducer 40 and the bearing 50 to be aligned. As a result, vibration of the reducer 40 is reduced, and damage to the reducer 40 can be suppressed. Furthermore, by providing the machine 1 with such a centering structure, vibration of the machine 1 is reduced, thereby suppressing damage to the machine 1 and improving the positioning accuracy of the machine 1.

[0064] Although various embodiments have been described herein, it should be recognized that the present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the following claims. [Explanation of symbols]

[0065] 1 machine 10 Actuator 11~17 Link 18 Wrist Unit 20 Electric motor 21 Rotation axis 22 Motor side gear 30~34 Screw 40 Reducer 41 Central Gear 42 Orbiting Gear 43 Shaft 44 cases 50 Bearings 51 Inner Circle 52 Outer ring 53 Rolling elements 60 Adapter 61 Inner flange 62 Cylindrical part 63 First outer flange 64 Second outer flange 70~75 Fitting part J1~J6 axis D1 Outside diameter of central gear D2 Inner flange inner diameter

Claims

1. A reducer; a bearing disposed radially outward from a center line of the reducer; an adapter fixed to the reducer to maintain the concentricity of the reducer and the bearing; a first link that fixes the reducer and the bearing; A second link for fitting the adapter; The centering structure is provided with:

2. The centering structure according to claim 1 , wherein the adapter is inscribed on an inner ring of the bearing or is circumscribed on an outer ring of the bearing.

3. The centering structure according to claim 1 or 2, wherein the adapter is fixed to a shaft or a case of the reducer.

4. The centering structure according to claim 1 , wherein the adapter is fitted to the reducer.

5. A centering structure described in any one of claims 1 to 4, wherein the first link maintains the concentricity of the reducer and the bearing.

6. The centering structure according to claim 1 , wherein the bearing is disposed between a top surface and a bottom surface of the reducer.

7. A reducer; a bearing disposed radially outward from a center line of the reducer; An adapter fixed to the reducer; a first link that fixes the reducer and the bearing; Equipped with The adapter maintains the concentricity of the shaft of the reducer and the bearing, and the first link maintains the concentricity of the case of the reducer and the bearing, or A centering structure in which the adapter maintains the concentricity of the reducer case and the bearing, and the first link maintains the concentricity of the reducer shaft and the bearing.

8. A reducer; a bearing disposed radially outward from a center line of the reducer; a first link that fixes the reducer and the bearing; A second link fixed to the reducer; Equipped with The second link maintains the shaft of the reducer and the bearing concentrically, and the first link maintains the case of the reducer and the bearing concentrically, or A centering structure in which the second link maintains the concentricity of the reducer case and the bearing, and the first link maintains the concentricity of the reducer shaft and the bearing.

9. A machine comprising a centering structure according to any one of claims 1 to 8.

10. A robot comprising the centering structure according to any one of claims 1 to 8.

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