JP2010269400A - Robot joint structure and robot including the same - Google Patents

Abstract

A wrist structure that is compact and lightweight is provided.
A wrist structure includes a proximal casing, a movable casing, and a distal casing. A B-axis reduction mechanism 24 that swings the movable casing 16 about the B-axis is provided between the proximal-side casing 11 and the movable casing 16, and the distal-side casing 19 about the T-axis is provided between the movable casing 16 and the distal-side casing 19. A T-axis speed reduction mechanism 35 is installed, and a rotational driving force is applied to the input shaft 24a of the T-axis speed reduction mechanism 35 by a transmission shaft 31 provided on the B-axis between the base end side casing 11 and the movable casing 16. A transmission mechanism 30 for transmission is installed. The movable casing 16 includes a support portion 25 that pivotally supports one end of the input shaft 24 a and the transmission shaft 31 of the B-axis speed reduction mechanism 24.
[Selection] Figure 3

Description

  The present invention relates to a joint structure of a robot including a base end side casing, a movable casing and a front end side casing which are provided so as to be rotatable with respect to each other, and a robot including the same.

  The articulated robot includes a joint structure in which a movable casing (wrist) is pivotally supported on a support casing (arm portion) as described in Patent Document 1. The movable casing is provided with a speed reducer for wrist rotation, and the movable casing is rotated by rotating an input shaft provided therein. Further, the movable casing is provided with a second shaft provided coaxially with the input shaft, and a third shaft that bevel-engages with the second shaft. The third shaft is connected to a speed reducer for rotating the most advanced wrist, and the speed reducer is provided at the tip of the movable casing.

Japanese Patent Application Laid-Open No. 64-20993

  The articulated structure of the articulated robot of the prior art is such that a unitized wrist rotation speed reducer is attached to a movable casing. Therefore, the speed reducer for rotating the wrist includes a casing different from the movable casing, and the casing needs to be attached to the movable casing. Therefore, the size of the joint structure itself is increased and the weight is also increased. In addition, the state-of-the-art wrist rotation speed reducer is similarly unitized and equipped with a separate casing. By providing the state-of-the-art wrist rotation speed reducer, the dimensions of the joint structure itself can be reduced. Increases weight and weight.

  Accordingly, an object of the present invention is to provide a lightweight and compact joint structure.

  The joint structure of the robot according to the present invention is a joint structure of a robot including a base end side casing, a movable casing, and a tip end side casing that are provided so as to be rotatable with respect to each other, and is installed on the base end casing and the movable casing. A first speed reduction mechanism for rotating the movable casing around the first input shaft, and the distal end around the second input shaft that is installed on the movable casing and the distal end side casing and is orthogonal to the first input shaft. Rotational power is transmitted to the second input shaft by a second speed reduction mechanism for rotating the side casing, the base end side casing and the movable casing, and a transmission shaft coaxial with the first input shaft. The movable casing includes a first input shaft and a transmission shaft that support opposite ends of the transmission shaft, and a notch portion that is recessed in the axial direction of the second input shaft is formed. A support portion that is, one end portion of said second input shaft is disposed in the cutout portion, in which and to bevel mesh with the end of the transmission shaft.

  According to the present invention, the first speed reduction mechanism is built in the base end side casing and the movable casing, and the second speed reduction mechanism is built in the movable casing and the front end side casing. The casing of the second speed reduction mechanism can be omitted, and the joint structure of the robot can be made compact and lightweight.

  In the present invention, the first input shaft and the transmission shaft provided on the same axis are supported by one support so that the member supporting the first input shaft and the transmission shaft is supported by the first input shaft and the transmission shaft. Therefore, it is not necessary to arrange the joint structures in the extending direction, and the dimension of the joint structure in the direction can be shortened.

  Furthermore, the distance from the first input shaft to the tip of the second input shaft is shortened by arranging the base end portion of the second input shaft at the notch formed in the support body and engaging the bevel with the transmission shaft. Thus, the dimension in the direction in which the second input shaft extends can be made compact. As a result, the turning radius of the tip of the tip casing can be reduced, and the bending moment generated at the tip of the tip casing can be reduced.

  In the above invention, it is preferable that one end side of the second input shaft is pivotally supported by the movable casing, and the other end side is pivotally supported by the distal end side casing.

  If the said structure is followed, the one end part and other end part of a 2nd input shaft will be pivotally supported by a different casing. Thereby, the distance between the two points on which the second input shaft is pivotally supported can be increased, and rattling can be reduced.

  In the above invention, it is preferable that one end side of the transmission shaft is pivotally supported by the base end side casing, and the other end side is pivotally supported by the movable casing.

  If the said structure is followed, the one end part and other end part of a transmission shaft will be pivotally supported by a different casing. Thereby, the distance between the two points on which the transmission shaft is pivotally supported can be increased, and rattling can be reduced.

  The robot of the present invention has the joint structure of any one of the above robots.

  If the said structure is followed, the robot which has the above joint structures is realizable.

  According to the present invention, a lightweight and compact joint structure can be realized.

It is a perspective view which shows the industrial robot 2 provided with the wrist structure 1 of embodiment of this invention. It is the front view which looked at the wrist structure 1 from the front. It is sectional drawing which looked at the wrist structure 1 cut | disconnected by cutting line AA shown in FIG. It is an expanded sectional view which expands and shows a part of wrist structure 1 of FIG. It is the expanded sectional view which cut | disconnected the wrist structure 1 by the cutting line BB shown in FIG.

  FIG. 1 is a perspective view showing an industrial robot 2 including a wrist structure 1 according to an embodiment of the present invention. The industrial robot 2 is a so-called multi-joint type 6-axis robot, and an attachment (not shown) is attached to the tip of the robot so that a workpiece can be grasped or processed. The industrial robot 2 includes a base 3 that is fixed to a floor or the like. The base 3 is provided with a first arm 4 so as to be rotatable around the S axis which is a vertical axis. A second arm 5 is provided on the upper portion of the first arm 4 so as to be rotatable around an L axis that is a horizontal axis. The lower end of the second arm 5 is provided on the first arm 4, and the base end of the third arm 6 is provided at the upper end of the second arm 5 so as to be rotatable around the U axis that is a horizontal axis. . The third arm 6 extends in an axial direction orthogonal to the U axis, and the wrist structure 1 is pivotable around the R axis that is the axis of the third arm 6 at the tip of the third arm 6. Is provided.

  The wrist structure 1 includes a first wrist movable part 7, a second wrist movable part 8, and a third wrist movable part 9. The first wrist movable unit 7 is provided at the tip of the third arm 6 so as to be rotatable around the R axis. The first wrist movable part 7 is provided with a second wrist movable part 8 so as to be rotatable around a B axis orthogonal to the R axis. Further, the second wrist movable unit 8 is provided with a third wrist movable unit 9 that can be rotated about a T axis orthogonal to the B axis, and the tip of the third wrist movable unit 9 is a tool, or Attachments (not shown) such as jigs can be removed. Below, the wrist structure 1 is demonstrated in detail.

[About the casing of the wrist structure 1]
FIG. 2 is a front view of the wrist structure 1 as viewed from the front. FIG. 3 is a cross-sectional view of the wrist structure 1 taken along the cutting line AA shown in FIG. FIG. 4 is an enlarged sectional view showing a part of the wrist structure 1 of FIG. 3 in an enlarged manner. FIG. 5 is an enlarged cross-sectional view of the wrist structure 1 taken along the cutting line BB shown in FIG. The first wrist movable part 7 of the wrist structure 1 has a proximal end side casing 11 provided at the distal end of the third arm 6 so as to be rotatable around the R axis. The proximal-side casing 11 is directly or indirectly connected to an R-axis motor (not shown) provided in the third arm 6 so as to rotate around the R-axis by driving the R-axis motor. It has become.

  The proximal end casing 11 extends in the direction in which the R axis extends. The tip side portion is bifurcated. As a result, a pair of support plates 12 and 13 that oppose each other at an interval in a direction parallel to the B-axis (hereinafter also simply referred to as “B-axis direction”) are provided on the distal end side portion of the proximal-side casing 11. It is formed. The pair of support plates 12 and 13 are provided with a pair of shaft portions 14 and 15 that protrude toward the opposite support plates 12 and 13, respectively. The pair of shaft portions 14 and 15 are formed in a cylindrical shape, and a second wrist movable portion 8 is provided on them so as to be rotatable around the B axis.

  The second wrist movable unit 8 has a movable casing 16. The movable casing 16 has recesses 16a and 16b formed on one side and the other side in the B-axis direction. A pair of shaft portions 14 and 15 are inserted into the recesses 16a and 16b in a state where a seal is achieved, respectively, and the pair of shaft portions 14 and 15 are inserted into the recesses 16a and 16b via bearings 17 and 18, respectively. It is supported. The movable casing 16 is generally formed in a bottomed cylindrical shape, and extends in a direction perpendicular to the B axis, that is, the T axis. A third wrist movable part 9 is provided at the opening end of the movable casing 16 so as to be rotatable around the T axis.

  The third wrist movable part 9 has a bottomed cylindrical tip side casing 19. The opening end portion of the front end side casing 19 is fitted into the opening end portion of the movable casing 16 via a bearing 20. An attachment can be attached to and detached from the bottom of the front end side casing 19.

  The second wrist movable unit 8 and the third wrist movable unit 9 configured as described above can be rotated by driving the B-axis motor 21 and the T-axis motor 22. The B-axis motor 21 and the T-axis motor 22 are mounted side by side in the R-axis direction on the proximal end side casing 11, and the B-axis motor 21 is disposed on the distal side of the T-axis motor 22. The output shaft 21a of the B-axis motor 21 is disposed in parallel to the B-axis. The output shaft 21 a is mechanically connected to the input shaft 24 a of the B-axis reduction mechanism 24 via the gear train 23, and the rotational drive force of the B-axis motor 21 is transmitted to the output shaft 21 a of the B-axis reduction mechanism 24 by the gear train 23. Transmission to the input shaft 24a is possible. The gear train 23 is disposed along the inner wall surface on one side in the B-axis direction of the base end side casing 11.

  The B-axis reduction mechanism 24 is disposed along the B-axis in one shaft portion 14, and is installed on the shaft portion 14 and the movable casing 16 of the base end side casing 11. The B-axis reduction mechanism 24 is a so-called wave gear mechanism (harmonic drive: registered trademark), and includes an input shaft 24a, a wave generator 24b, a flex spline 24c, and a circular spline 24d. The input shaft 24 a is disposed along the B axis, and one end thereof is pivotally supported by one shaft portion 14. One end portion of the input shaft 24a protrudes from the one shaft portion 14 into the one support plate 12, and a gear train 23 is connected to the one end portion. Further, the other end portion of the input shaft 24 a protrudes from the one shaft portion 14 into the movable casing 16. One recess 16a of the movable casing 16 is formed with a support portion 25 extending from the bottom thereof toward the inside of the movable casing 16, and the other end portion of the input shaft 24a is pivotally supported on the support portion 25. Has been.

  The wave generator 24b is integrally provided on the input shaft 24a supported in this manner. The wave generator 24b is fitted to a bottomed cylindrical flexspline 24c via a bearing 26. The flex spline 24 c is accommodated in one shaft portion 14 and meshes with a circular spline 24 d provided integrally on the inner wall of the shaft portion 14. The bottom of the flex spline 24c is fixed to the movable casing 16. Thereby, when the B-axis motor 21 is driven and the input shaft 24 a rotates, the movable casing 16 rotates with respect to the base end side casing 11. That is, by driving the B-axis motor 21, the second wrist movable portion 8 rotates with respect to the first wrist movable portion 7.

  The T-axis motor 22 is disposed closer to the base end side than the B-axis motor 21. The output shaft 22 a of the T-axis motor 22 is arranged in parallel with the B-axis and extends in the direction opposite to the output shaft 21 a of the B-axis motor 21. A transmission mechanism 30 is mechanically connected to the output shaft 22a. The transmission mechanism 30 is disposed in the base end side casing 11 and is installed on the base end side casing 11 and the movable casing 16. The transmission mechanism 30 includes a transmission shaft 31, two pulleys 32 and 33, and a belt 34.

  The transmission shaft 31 is disposed along the B axis in a state where sealing is achieved in the other shaft portion 15, and one end side is pivotally supported by the other shaft portion 15 and the other end portion is pivotally supported by the support portion 25 of the movable casing 16. ing. One end portion of the transmission shaft 31 protrudes from the other shaft portion 15 into the other support plate 13, and one pulley 32 is fixed thereto. The other pulley is fixed to the output shaft 22a. These two pulleys 32 and 33 are disposed along the inner wall surface on the other side in the B axis direction of the base end side casing 11, that is, disposed on the opposite side with respect to the gear train 23 and the R axis. An endless belt 34 is stretched between the two pulleys 32 and 33, and the belt 34 transmits the rotational driving force of the T-axis motor 22 to the transmission shaft 31, and the transmission shaft 31 rotates. It is like that. The transmission shaft 31 is integrally formed with a bevel gear 31a on the other end side. The bevel gear 31a is meshed with the input shaft 35a of the T-axis reduction mechanism 35.

  The T-axis deceleration mechanism 35 is disposed along the T-axis and is installed on the movable casing 16 and the front end side casing 19. The T-axis speed reduction mechanism 35 is a so-called wave gear mechanism, and includes an input shaft 35a, a wave generator 35b, a flex spline 35c, and a circular spline 35d. The input shaft 35a is disposed along the T-axis, and a bevel gear 35e is provided at one end thereof. The bevel gear 35e is meshed with the transmission shaft 31.

  The bevel gear 35e is disposed so as to face the outer peripheral surface of the support portion 25 on the front end side casing 19 side (hereinafter also simply referred to as “front end side outer peripheral surface”). The support portion 25 is recessed in the direction parallel to the T-axis so that the front-end-side outer peripheral surface approaches the B-axis, and this recess forms a notch portion 25a. The bevel gear 35e is disposed in the cutout portion 25a, so that the bevel gear 35e is disposed so as to sink between the one and the other concave portions 16a and 16b. In addition, the cutout portion 25a has a semicircular shape whose outer peripheral surface protrudes substantially toward the tip side when viewed in the B-axis direction, and when the movable casing 16 rotates around the B-axis. The bevel gear 35e does not interfere.

  The input shaft 35 a is provided with a bearing 36 on one end side thereof, and is supported on the inner peripheral portion of the movable casing 16 via the bearing 36. The input shaft 35a is formed with a recess 35f on one end side, and the bearing 36 is fitted into the recess 35f, whereby the input shaft 35a is positioned with respect to the movable casing 16. Further, the other end portion of the input shaft 35 a projects from the opening of the movable casing 16 into the distal end side casing 19 and is pivotally supported by the distal end side casing 19.

  A wave generator 35b is integrally provided on the input shaft 35a supported in this manner. The wave generator 35 b is fitted to a cylindrical flex spline 35 c via a bearing 37. The flex spline 35 c is accommodated in the front end side casing 19 and meshes with a circular spline 35 d provided integrally on the inner wall of the front end side casing 19. The flex spline 35 c has an outward flange portion 35 g extending radially outward at one end in the axial direction, and the outward flange portion 35 g is fixed to the opening of the movable casing 16.

  With regard to the transmission mechanism 30 and the T-axis deceleration mechanism 35 configured as described above, when the transmission shaft 31 is rotated by driving the T-axis motor 21, the rotational driving force is transmitted to the input shaft 35 a via the transmission shaft 31. Then, the front end side casing 19 rotates with respect to the movable casing 16. That is, by driving the T-axis motor 22, the third wrist movable unit 9 rotates with respect to the second wrist movable unit 8.

  In the wrist structure 1 configured as described above, the B-axis speed reduction mechanism 24 is installed in the base end side casing 11 and the movable casing 16, and the T axis speed reduction mechanism 35 is provided in the base end side casing and the movable casing. Since the casings for the B-axis and T-axis deceleration mechanisms 24 and 35 can be omitted, the wrist structure 1 can be made compact and lightweight.

  In addition, by supporting the input shaft 24a and the transmission shaft 31 provided on the B-axis with one support portion 25, it is not necessary to arrange the members that support the input shaft 24a and the transmission shaft 31 in the B-axis direction. The dimension of the wrist structure 1 in the B-axis direction can be shortened and made compact.

  Further, the bevel gear 35e of the T-axis speed reducer 35 is disposed in the notch portion 25a formed in the support portion 25 and engaged with the transmission shaft 31 so that the distance from the B-axis to the tip of the second input shaft. Becomes shorter, the dimension in the T-axis direction is shorter, and the size can be reduced. As a result, the turning radius of the tip of the tip casing 19 can be reduced, and the bending moment generated at the tip of the tip casing 19 can be reduced.

  One end portion and the other end portion of the input shaft 35a of the T-axis speed reducer 35 are pivotally supported by different casings 16 and 19, and a bevel gear 35e of the T-axis speed reducer 35 is formed in a notch 25a formed in the support portion 25. Since the bevel is engaged with each other, the distance between the two points on which the input shaft 35a is pivotally supported can be increased, and rattling can be reduced. Similarly, one end and the other end of the transmission shaft 31 are pivotally supported by different casings 11 and 16. Thereby, the distance between the two points on which the transmission shaft 31 is pivotally supported can be increased, and rattling can be reduced.

  In the present embodiment, the output shaft 21a of the B-axis motor 21 and the input shaft 24a of the B-axis reduction mechanism 24 are connected by the gear train 23, but the present invention is not limited to such a configuration. For example, a pulley may be provided on each of the shafts 21a and 24a, and a belt may be stretched around these pulleys so that the rotational driving force can be transmitted. Moreover, the structure which transmits a rotational driving force with a drive shaft may be sufficient. The same applies to the connection between the output shaft 22a of the T-axis motor 22 and the transmission shaft 31, and is not limited to the transmission of the rotational driving force by the pulleys 32, 33 and the belt 34, but by the gear train or the drive shaft. You may comprise so that a rotational drive force may be transmitted.

  In this embodiment, the case where the wrist structure 1 is applied to an articulated 6-axis robot has been described. However, the present invention is not limited to the 6-axis robot. For example, a 3-axis robot having only the wrist structure 1, a 4-axis or 5-axis robot, or a robot with 7 or more axes may be used. The robot to be applied is not limited to a stationary robot, and may be applied to a transfer robot or the like, and any kind of industrial robot can be applied.

  In the present embodiment, the case where the joint structure of the present invention is applied to the wrist as a wrist structure has been described. However, the same effects can be obtained even when applied to other joints.

  The present invention is not limited to the embodiments, and can be added, deleted, and changed without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 1 Wrist structure 2 Industrial robot 11 Base end side casing 16 Movable casing 19 Front end side casing 24a Input shaft 25 Support part 25a Notch part 30 Transmission mechanism 31 Transmission shaft 31a Bevel gear 35 T-axis reduction mechanism 35a Input shaft 35e Bevel gear

Claims (4)

A joint structure of a robot provided with a base end side casing, a movable casing, and a front end side casing provided so as to be rotatable with respect to each other,
A first speed reduction mechanism that is installed in the base end side casing and the movable casing and rotates the movable casing around a first input shaft;
A second speed reduction mechanism that spans the movable casing and the distal casing, and rotates the distal casing about a second input shaft that is orthogonal to the first input shaft;
A transmission mechanism that is installed on the base end side casing and the movable casing, and that transmits torque to the second input shaft by a transmission shaft that is coaxial with the first input shaft;
The movable casing has a support portion that supports end portions of the first input shaft and the transmission shaft that face each other, and is formed with a notched portion that is recessed in the axial direction of the second input shaft.
One end portion of the second input shaft is disposed in the notch portion, and beveled with the end portion of the transmission shaft. The joint structure of the robot according to claim 1, wherein one end side of the second input shaft is pivotally supported by the movable casing, and the other end side is pivotally supported by the distal end side casing. The joint structure of the robot according to claim 1, wherein one end side of the transmission shaft is pivotally supported by the base end side casing and the other end side is pivotally supported by the movable casing. A robot having the joint structure of the robot according to any one of claims 1 to 3.

Images