Arm member and robot

Abstract

This arm member is composed of a first portion, a second portion, and a third portion between the first portion and the second portion. The third portion includes first and second motors, the first portion comprises a first deceleration mechanism having a first coupling gear coupled to the first motor, and the second portion comprises a second deceleration mechanism having a second coupling gear coupled to the second motor. The first and third portions respectively have a first fitting surface and a second fitting surface that are composed of cylindrical surfaces disposed coaxially with the first coupling gear or the first motor and are fitted to each other in the longitudinal direction. The second and third portions respectively have a third fitting surface and a fourth fitting surface that are composed of cylindrical surfaces disposed coaxially with the second coupling gear or the second motor and are fitted to each other in the longitudinal direction. The first and second fitting surfaces and the third and fourth fitting surfaces are disposed at positions shifted from each other in a direction perpendicular to the longitudinal direction.

Description

Arm member and robot

[0001] The present disclosure relates to an arm member and a robot.

[0002] A six-axis articulated robot has been known in the art (see, for example, Patent Document 1), which includes a first arm made up of three detachable sections. Both ends of the first arm are connected to a rotating body and a second arm, and the three sections, starting from the second arm, are a first arm section, a second arm section, and a third arm section. The second arm section houses a first motor and a second motor for driving the first arm and the second arm, respectively, and each of the first arm section and the third arm section houses a speed reduction mechanism for reducing the rotation speed of the motor.

[0003] Patent No. 7101134

[0004] When assembling the first arm, it is necessary to align the first arm portion, the second arm portion, and the third arm portion with respect to one another. To simplify the alignment process, it is desirable that this alignment can be performed without using alignment members such as pins.

[0005] One aspect of the present disclosure provides an arm member having a longitudinal direction and a first end and a second end that are opposite ends in the longitudinal direction, the first end being connected to a first member so as to be rotatable about a first rotation axis that intersects the longitudinal direction, and the second end being connected to a second member so as to be rotatable about a second rotation axis that intersects the longitudinal direction, the arm member comprising a first portion including the first end, a second portion including the second end, and a third portion sandwiched between the first portion and the second portion, the first portion, the second portion, and the third portion being mutually coupled in the longitudinal direction, the third portion having a first motor and a second motor that rotate respectively about axes parallel to the longitudinal direction, the first portion including a first reduction mechanism that converts rotation of the first motor into rotation about the first rotation axis and transmits the rotation to the first member, the first reduction mechanism including a first connecting gear that is coupled to the first motor and rotatable about the axis parallel to the longitudinal direction. the second part is equipped with a second reduction mechanism that converts rotation of the second motor into rotation about the second rotation axis and transmits the rotation to the second member, the second reduction mechanism having a second connecting gear that is connected to the second motor and rotatable about an axis parallel to the longitudinal direction, the first part and the third part respectively have first and second mating surfaces that mate with each other in the longitudinal direction, the first mating surface and the second mating surface being cylindrical surfaces that are arranged coaxially with the first connecting gear or the first motor, the second part and the third part respectively have third and fourth mating surfaces that mate with each other in the longitudinal direction, the third mating surface and the fourth mating surface being cylindrical surfaces that are arranged coaxially with the second connecting gear or the second motor, and the first and second mating surfaces and the third and fourth mating surfaces are arranged at positions that are offset from each other in a direction perpendicular to the longitudinal direction.

[0006] FIG. 1 is a configuration diagram of a robot according to an embodiment of the present disclosure; FIG. 2 is an internal configuration diagram of a lower section and a middle section of a first arm; FIG. 3 is an internal configuration diagram of an upper section and a middle section of a first arm; FIG. 4 is a front view of a first arm; FIG. 5 is a side view of a first arm; FIG. 6 is a diagram explaining a method of assembling the first arm; FIG. 7 is a diagram explaining a method of assembling the first arm; FIG. 8 is a side view of a robot equipped with a short first arm;

[0007] An arm member and a robot according to an embodiment of the present disclosure will be described below with reference to the drawings. As shown in FIG. 1 , the robot 1 according to this embodiment is a six-axis vertical articulated robot. The robot 1 includes a base 2 installed on a floor (a support surface), a rotating body 3 supported rotatably about a first axis J1 perpendicular to the base 2, a first arm 4 supported swingably about a second axis J2 horizontal to the rotating body 3, a second arm 5 supported swingably at the distal end of the first arm 4 about a third axis J3 horizontal to the first arm 4, and a three-axis wrist unit 6 supported at the distal end of the second arm 5. The second axis J2 and the third axis J3 are parallel to each other. FIG. 1 is a structural diagram of the robot 1 viewed horizontally from the opposite side of the wrist unit 6.

[0008] The arm member according to this embodiment is a first arm 4. The first arm 4 has a longitudinal direction A parallel to the first axis J1 and a base end (first end) 4a and a tip end (second end) 4b, which are opposite ends in the longitudinal direction A. The base end 4a is connected to the rotating body (first member) 3 so as to be rotatable about a second axis (first rotation axis) J2, and the tip end 4b is connected to the second arm (second member) 5 so as to be rotatable about a third axis (second rotation axis) J3.

[0009] 1 to 3, the first arm 4 includes a cover 7, two motors 8 and 9, two speed reduction mechanisms 10 and 11, and two bearings 12 and 13, and the motors 8 and 9, the speed reduction mechanisms 10 and 11, and the bearings 12 and 13 are housed within the cover 7. The bearings 12 and 13 are not shown in FIG.

[0010] 4A and 4B , the cover 7 is divided into three portions 71, 72, and 73 along two dividing planes P1 and P2 in the longitudinal direction A. As a result, the first arm 4 is made up of a lower portion (first portion) 4A, an upper portion (second portion) 4B, and a middle portion (third portion) 4C, which are arranged in the longitudinal direction A. Hereinafter, the portions 71, 72, and 73 will also be referred to as covers 71, 72, and 73.

[0011] The lower stage 4A includes a base end 4a, the upper stage 4B includes a tip end 4b, and the middle stage 4C is sandwiched between the lower stage 4A and the upper stage 4B. The lower stage 4A and the middle stage 4C are separably connected to each other in the longitudinal direction A, and the upper stage 4B and the middle stage 4C are separably connected to each other in the longitudinal direction A.

[0012] At the first dividing plane P1, the upper end surface 71 a of the cover 71 and the lower end surface 73 a of the cover 73 come into contact with each other, and at the second dividing plane P2, the lower end surface 72 a of the cover 72 and the upper end surface 73 b of the cover 73 come into contact with each other. To achieve high assembly precision of the three parts 4A, 4B, and 4C, the two dividing planes P1 and P2 are preferably flat surfaces parallel to each other. In the reference drawings, the two dividing planes P1 and P2 are flat surfaces perpendicular to the longitudinal direction A.

[0013] The lower stage 4A includes a cover 71, and a first reduction gear mechanism 10 and a first bearing 12 housed in the cover 71. The upper stage 4B includes a cover 72, and a second reduction gear mechanism 11 and a second bearing 13 housed in the cover 72. The middle stage 4C includes a cover 73 and two motors 8 and 9 housed in the cover 73.

[0014] The first motor 8 rotates about an axis parallel to the longitudinal direction A and generates power for rotating the first arm 4 about the second axis J2 relative to the rotating body 3. The second motor 9 rotates about an axis parallel to the longitudinal direction A and generates power for rotating the second arm 5 about the third axis J3 relative to the first arm 4. Input gears 8a and 9a connected to reduction gear mechanisms 10 and 11 are provided on the output shafts of the motors 8 and 9, respectively. The two motors 8 and 9 are preferably arranged parallel to each other in a direction perpendicular to the longitudinal direction A.

[0015] 2 shows the internal structure of the lower stage 4A and the middle stage 4C as viewed in a direction parallel to the second axis J2 from the side opposite the rotating body 3. The first reduction gear mechanism 10 is connected to the first motor 8 and reduces the rotation of the first motor 8 before transmitting it to the rotating body 3. The first reduction gear mechanism 10 also converts the rotation of the first motor 8 into rotation about the second axis J2. Specifically, the first reduction gear mechanism 10 has a first hypoid gear set 14 and an intermediate gear unit (first connecting gear) 15 between the first motor 8 and the hypoid gear set 14.

[0016] The hypoid gear set 14 has a ring gear (first output hypoid gear) 141 and a pinion gear unit (first input hypoid gear) 142 that mesh with each other. The ring gear 141 is disposed coaxially with the second axis J2 and is fixed to the rotating body 3 with bolts. The pinion gear unit 142 is supported by bearings 20a and 20b so as to be rotatable about an axis parallel to the longitudinal direction A, and meshes with the ring gear 141 and the intermediate gear unit 15. For example, the pinion gear unit 142 has a bevel gear 142a that meshes with the ring gear 141 and a spur gear 142b that meshes with the intermediate gear unit 15.

[0017] The intermediate gear unit 15 is disposed between the first motor 8 and the pinion gear unit 142 and is supported by bearings 12 and 20c so as to be rotatable about an axis parallel to the longitudinal direction A. The intermediate gear unit 15 is coupled to the first motor 8 by meshing with the input gear 8a, thereby mechanically coupling the lower stage portion 4A to the middle stage portion 4C. The rotation of the first motor 8 is transmitted to the rotating body 3 via the input gear 8a, the intermediate gear unit 15, the pinion gear unit 142, and the ring gear 141, and is converted into rotation about the second axis J2 by ​​the gears 142 and 141. This causes the first arm 4 to rotate relative to the rotating body 3.

[0018] 3 shows the internal structure of the upper stage portion 4B and the middle stage portion 4C as viewed in a direction parallel to the third axis J3 from the side opposite the wrist unit 6. The second reduction mechanism 11 is connected to the second motor 9 and reduces the rotation of the second motor 9 before transmitting it to the second arm 5. The second reduction mechanism 11 also converts the rotation of the second motor 9 into rotation about the third axis J3. Specifically, the second reduction mechanism 11 has a second hypoid gear set 16 and an intermediate gear unit (second connecting gear) 17 between the second motor 9 and the hypoid gear set 16.

[0019] The hypoid gear set 16 has a ring gear (second output hypoid gear) 161 and a pinion gear unit (second input hypoid gear) 162 that mesh with each other. The ring gear 161 is disposed coaxially with the third axis J3 and is fixed to the second arm 5 with bolts. The pinion gear unit 162 is supported by bearings 20d and 20e to be rotatable about an axis parallel to the longitudinal direction A, and meshes with the ring gear 161 and the intermediate gear unit 17. For example, the pinion gear unit 162 has a bevel gear 162a that meshes with the ring gear 161 and a spur gear 162b that meshes with the intermediate gear unit 17.

[0020] The intermediate gear unit 17 is disposed between the second motor 9 and the pinion gear unit 162 and is supported by bearings 13 and 20f so as to be rotatable about an axis parallel to the longitudinal direction A. The intermediate gear unit 17 is coupled to the second motor 9 by meshing with the input gear 9a, thereby mechanically coupling the upper stage portion 4B to the middle stage portion 4C. The rotation of the second motor 9 is transmitted to the second arm 5 via the input gear 9a, the intermediate gear unit 17, the pinion gear unit 162, and the ring gear 161, and is converted into rotation about the third axis J3 by the gears 162 and 161. This causes the second arm 5 to rotate relative to the first arm 4.

[0021] 2 , the bearing (first annular member) 12 is disposed across the first dividing plane P1 in the longitudinal direction A, and a portion of the bearing 12 and a portion of the intermediate gear unit 15 protrude in the longitudinal direction A from an upper end surface 71 a at the first dividing plane P1. The middle stage 4C has a circular recess 18 that opens to a lower end surface 73 a and receives the portion of the bearing 12 and the portion of the intermediate gear unit 15. The outer surface 12 a of the portion of the bearing 12 and the inner surface 18 a of the recess 18 are cylindrical surfaces that are disposed coaxially with the intermediate gear unit 15 and constitute a first fitting surface and a second fitting surface that fit together in the longitudinal direction A.

[0022] 3 , the bearing (second annular member) 13 is disposed across the second dividing surface P2 in the longitudinal direction A, and a portion of the bearing 13 and a portion of the intermediate gear unit 17 protrude in the longitudinal direction A from a lower end surface 72 a at the second dividing surface P2. The middle stage 4C has a circular recess 19 that opens to an upper end surface 73 b and receives the portion of the bearing 13 and the portion of the intermediate gear unit 17. The outer surface 13 a of the portion of the bearing 13 and the inner surface 19 a of the recess 19 are cylindrical surfaces that are disposed coaxially with the intermediate gear unit 17 and constitute third and fourth fitting surfaces, respectively, that fit together in the longitudinal direction A.

[0023] Here, the central axes of the bearings 12 and 13 are not aligned on the same line, but are offset from each other in a direction perpendicular to the longitudinal direction A. As a result, the central axes of the first and second mating surfaces 12 a, 18 a and the central axes of the third and fourth mating surfaces 13 a, 19 a are also offset from each other in a direction perpendicular to the longitudinal direction A.

[0024] Figure 4A is a front view of the first arm 4 viewed horizontally from the rotating body 3 and second arm 5 side. Figure 4B is a side view of the first arm 4 viewed horizontally perpendicular to the second axis J2 and the third axis J3. As shown in Figures 4A and 4B, the lower stage 4A has a first reference surface 21 on its outer side, the upper stage 4B has a second reference surface 22 on its outer side, and the middle stage 4C has two third reference surfaces 23a and 23b on its outer side. The reference surfaces 21 and 23a are used to adjust the relative positions of the lower stage 4A and the middle stage 4C around the axis in the longitudinal direction A. The reference surfaces 22 and 23b are used to adjust the relative positions of the upper stage 4B and the middle stage 4C around the axis in the longitudinal direction A.

[0025] The first reference surface 21 is a flat surface parallel to the output surface 10a of the first reduction gear mechanism 10 and is provided on the outer surface of the cover 71. The output surface 10a is a flat mounting surface attached to the rotating body 3 and, in this embodiment, is the end surface of the ring gear 141 on the rotating body 3 side. The second reference surface 22 is a flat surface parallel to the output surface 11a of the second reduction gear mechanism 11 and is provided on the outer surface of the cover 72. The output surface 11a is a flat mounting surface attached to the second arm 5 and, in this embodiment, is the end surface of the ring gear 161 on the second arm 5 side. The two output surfaces 10a, 11a are located on the same side of the first arm 4 and are parallel to each other. In this embodiment, the cover 7 has a flat side surface 7c on the side of the rotating body 3 and the second arm 5, and the output surfaces 10a, 11a protrude from the side surface 7c.

[0026] The two third reference surfaces 23a, 23b are provided on the outer surface of the cover 73 and are arranged in the longitudinal direction A. As will be described later, when a user assembles the first arm 4, the positional relationship between the reference surface 23a on the base end 4a side and the first reference surface 21 is measured, and the positional relationship between the reference surface 23b on the tip end 4b side and the second reference surface 22 is measured. To facilitate the measurements, the third reference surface 23a is preferably arranged in a line with the first reference surface 21 in the longitudinal direction A, and the third reference surface 23b is preferably arranged in a line with the second reference surface 22 in the longitudinal direction A. In this embodiment, the four reference surfaces 21, 22, 23a, and 23b are arranged in a straight line in the longitudinal direction A on the flat side surface 7c.

[0027] The two third reference surfaces 23a, 23b are flat surfaces parallel to the axes of the motors 8, 9, and form a predetermined angle with the first reference surface 21 and the second reference surface 22, which are parallel to each other, when viewed in the longitudinal direction A. In this embodiment, the predetermined angle is 0°, and the third reference surfaces 23a, 23b are parallel to the first reference surface 21 and the second reference surface 22.

[0028] As shown in Figures 2 and 4A, when the reference surfaces 21, 23a are viewed from the front, the reference surfaces 21, 23a are preferably disposed at positions spaced apart from the central axes of the mating surfaces 12a, 18a in a direction perpendicular to the longitudinal direction A. As shown in Figures 3 and 4A, when the reference surfaces 22, 23b are viewed from the front, the reference surfaces 22, 23b are preferably disposed at positions spaced apart from the central axes of the mating surfaces 13a, 19a in a direction perpendicular to the longitudinal direction A.

[0029] Next, a method for assembling the first arm 4 will be described. As shown in FIGS. 5A and 5B , during manufacturing at a factory or the like, the first arm 4 is assembled using a positioning jig 30. As shown in FIG. 5A , the positioning jig 30 is made of a horizontally disposed plate-like member and has an upper surface 31 and two flat positioning surfaces 32a and 32b that receive the output surfaces 10a and 11a of the speed reduction mechanisms 10 and 11, respectively. In this embodiment, the upper surface 31, which faces the flat side surface 7c, is a flat surface. The two positioning surfaces 32a and 32b are positioned in recessed positions relative to the upper surface 31. The two positioning surfaces 32a and 32b are parallel to each other and, specifically, have a high degree of parallelism that is less than the specified tolerance of the parallelism required for the output surfaces 10a and 11a.

[0030] 5B , the lower stage portion 4A, the upper stage portion 4B, and the middle stage portion 4C are coupled to one another with the output surfaces 10a and 11a aligned with the positioning surfaces 32a and 32b, respectively. Specifically, the bearing 12 is inserted into the recess 18 until the end faces 71a and 73a come into contact with each other, and the mating surface 12a is fitted into the mating surface 18a. The input gear 8a of the first motor 8 is then engaged with the intermediate gear unit 15, thereby coupling the lower stage portion 4A and the middle stage portion 4C to one another. Similarly, the bearing 13 is inserted into the recess 19 until the end faces 72a and 73b come into contact with each other, and the mating surface 13a is fitted into the mating surface 19a. The input gear 9a of the second motor 9 is then engaged with the intermediate gear unit 17, thereby coupling the upper stage portion 4B and the middle stage portion 4C to one another.

[0031] After alignment and joining, the lower and upper portions 4A, 4B may be fixed to the positioning jig 30 by the presser members 33. Then, the lower, upper, and middle portions 4A, 4B, 4C are fixed to each other by any means such as bolts.

[0032] In order to ensure high positional accuracy in the operation of the robot 1, the lower and upper portions 4A and 4B need to be aligned with high accuracy in the circumferential direction about the axis of the longitudinal direction A so that the parallelism between the two output surfaces 10a and 11a is within a specified tolerance. According to this embodiment, by using the positioning jig 30 having the positioning surfaces 32a and 32b, it is possible to easily align the lower and upper portions 4A and 4B so that the parallelism between the two output surfaces 10a and 11a is within a specified tolerance, and the required assembly accuracy of the first arm 4 can be ensured.

[0033] Furthermore, according to this embodiment, the lower stage 4A and the middle stage 4C have mating surfaces 12a, 18a, respectively, that are provided coaxially with the intermediate gear unit 15 and that mate with each other in the longitudinal direction A. Therefore, by mating the mating surfaces 12a, 18a, the lower stage 4A and the middle stage 4C can be aligned to the position where the intermediate gear unit 15 and the input gear 8a mesh with each other. This eliminates the need for a member such as a pin to align the lower stage 4A and the middle stage 4C.

[0034] Similarly, the upper stage portion 4B and the middle stage portion 4C have mating surfaces 13a, 19a, respectively, that are provided coaxially with the intermediate gear unit 17 and that fit together in the longitudinal direction A. Therefore, by mating the mating surfaces 13a, 19a, the upper stage portion 4B and the middle stage portion 4C can be aligned to the position where the intermediate gear unit 17 and the input gear 9a mesh together. This eliminates the need for a member such as a pin to align the upper stage portion 4B and the middle stage portion 4C.

[0035] Furthermore, according to this embodiment, the bearings 12, 13 are arranged at positions offset from each other in a direction intersecting the longitudinal direction A. As a result, when the lower step portion 4A and the upper step portion 4B are aligned with the positioning surfaces 32a, 32b, the circumferential position of the middle step portion 4C relative to the lower step portion 4A and the upper step portion 4B is uniquely determined. Therefore, there is no need for a member such as a pin for circumferentially aligning the middle step portion 4C relative to the lower step portion 4A and the upper step portion 4B.

[0036] Furthermore, according to this embodiment, the fitting surfaces 12a, 13a are formed by the outer surfaces of the bearings 12, 13 that support the intermediate gear units 15, 17. Therefore, it is not necessary to add a new annular member to the first arm 4 to provide the fitting surfaces 12a, 13a. Furthermore, according to this embodiment, the two motors 8, 9 are arranged in parallel. Therefore, as shown in FIG. 6 , a short first arm 4 can be manufactured by a simple design change that simply changes the positions of the two motors 8, 9 in the longitudinal direction A.

[0037] Furthermore, according to this embodiment, the first arm 4 is divided into portions 4A and 4B including the speed reduction mechanisms 10 and 11, respectively, and a portion 4C including the motors 8 and 9. Therefore, when assembling the speed reduction mechanisms 10 and 11, such as by adjusting backlash, the portions 4A and 4B can be assembled into small units. This facilitates automation of assembly. Furthermore, in manufacturing the first arm 4, the portions 4A, 4B, and 4C can be machined using small machine tools, thereby reducing processing costs.

[0038] Furthermore, according to this embodiment, each of the portions 4A, 4B, and 4C has the reference surfaces 21, 22, 23a, and 23b. When replacing the portions 4A and 4B that house the speed reduction mechanisms 10 and 11, the reference surfaces 21, 22, 23a, and 23b are used, allowing the first arm 4 to be assembled with the same high assembly precision as before disassembly.

[0039] For example, after the first arm 4 is shipped, the user may replace the lower stage 4A in order to replace the first reduction gear mechanism 10. At this time, the lower stage 4A is detached from the middle stage 4C, and then the new lower stage 4A is coupled to the middle stage 4C. Similarly, in order to replace the second reduction gear mechanism 11, the upper stage 4B is detached from the middle stage 4C, and then the new upper stage 4B is coupled to the middle stage 4C. In such a case, as shown in FIG. 4B , the user can accurately align the lower stage 4A and the upper stage 4B using the reference surfaces 21, 22, 23a, and 23b.

[0040] 4B illustrates the replacement of the upper stage 4B. Before removing the upper stage 4B from the middle stage 4C, the user uses a measuring device 40, such as a dial gauge, to measure the positional relationship between the reference surfaces 23b and 22 (e.g., the parallelism between the reference surfaces 23b and 22). The user then connects a new upper stage 4B to the middle stage 4C and uses the measuring device 40 to measure the positional relationship between the reference surfaces 23b and 22 again. The user then rotates the upper stage 4B relative to the middle stage 4C around the central axis of the mating surfaces 13a and 19a, positioning the upper stage 4B relative to the middle stage 4C so that the positional relationship between the reference surfaces 23b and 22 is the same as the positional relationship before removal, and then fixes the upper stage 4B to the middle stage 4C. This makes it possible to achieve a high degree of parallelism between the output surfaces 10a and 11a equivalent to that before replacement, without using a dedicated jig such as the positioning jig 30.

[0041] At this time, the upper stage portion 4B and the middle stage portion 4C can be aligned with high positional accuracy because the reference surfaces 22, 23b are located at positions spaced apart from the central axes of the mating surfaces 13a, 19a in a direction perpendicular to the longitudinal direction A. Similarly, when replacing the lower stage portion 4A, the reference surfaces 21, 23a are located at positions spaced apart from the central axes of the mating surfaces 12a, 18a in a direction perpendicular to the longitudinal direction A, so that the lower stage portion 4A and the middle stage portion 4C can be aligned with high positional accuracy.

[0042] Although the embodiments and modifications of the present disclosure have been described above, the arm member and robot of the present disclosure are not limited to the above-described embodiments and modifications, and various modifications are possible without departing from the spirit and scope of the present disclosure. For example, the robot 1 is not limited to a vertical articulated robot, but may be any robot including an arm member and two members rotatably connected to both ends of the arm member. The two motors 8, 9 may be arranged in series in the longitudinal direction A.

[0043] The first arm 4 may be assembled without using the positioning jig 30. For example, the lower and upper stages 4A, 4B may be aligned using any other means so that the output surfaces 10a, 11a are parallel to each other. In this case, the middle stage 4C is automatically aligned by aligning the lower and upper stages 4A, 4B, so no alignment members such as pins are required.

[0044] The third reference surfaces 23a, 23b may be inclined with respect to the first and second reference surfaces 21, 22. That is, in a state in which the first reference surface 21 and the second reference surface 22 are arranged parallel to each other, the third reference surfaces 23a, 23b may be arranged at a predetermined angle greater than 0° with respect to the reference surfaces 21, 22 when viewed in the longitudinal direction A. In this case as well, the lower step portion 4A can be positioned with respect to the middle step portion 4C based on the positional relationship between the reference surfaces 21, 23a, and the upper step portion 4B can be positioned with respect to the middle step portion 4C based on the positional relationship between the reference surfaces 22, 23b.

[0045] Only one of the third reference surfaces 23 a, 23 b may be provided on the middle stage 4 C. The third reference surfaces 23 a, 23 b do not necessarily have to be provided. In this case, for example, when replacing the upper stage 4 C, the positional relationship between the first reference surface 21 and the second reference surface 22 is measured, and the upper stage 4 B is positioned so that the first reference surface 21 and the second reference surface 22 are parallel to each other.

[0046] The specific configuration of the reduction gear mechanisms 10 and 11 may be other configurations as long as they can transmit the rotation of the motors 8 and 9 to the two members 3 and 5. For example, the gears for converting the rotation of the motors 8 and 9 into rotation about the axes J2 and J3 may be gears of a type different from the hypoid gears 141 and 142; 161 and 162. The members constituting the mating surfaces and their arrangement may be changed depending on the specific configuration of the reduction gear mechanisms 10 and 11.

[0047] The first and second annular members are not limited to bearings 12, 13, but may be any annular or cylindrical members provided in lower stage 4A and upper stage 4B. The first and second annular members may be provided in middle stage 4C and arranged coaxially with the axes of motors 8, 9. In this case, a cylindrical fitting surface that fits with the cylindrical outer surface of the annular member is provided on each of lower stage 4A and upper stage 4B.

[0048] The following additional notes are provided regarding the above-described embodiment and modifications. (Supplementary Note 1) An arm member having a longitudinal direction and a first end and a second end which are both ends in the longitudinal direction, the first end being connected to a first member so as to be rotatable about a first rotation axis which intersects with the longitudinal direction, and the second end being connected to a second member so as to be rotatable about a second rotation axis which intersects with the longitudinal direction, the arm member comprising a first part including the first end, a second part including the second end, and a third part sandwiched between the first part and the second part, the first part, the second part, and the third part being mutually coupled in the longitudinal direction, the third part having a first motor and a second motor which respectively rotate about an axis parallel to the longitudinal direction, the first part comprising a first reduction mechanism which converts rotation of the first motor into rotation about the first rotation axis and transmits the rotation to the first member, the first reduction mechanism having a first connecting gear which is connected to the first motor and is rotatable about an axis parallel to the longitudinal direction, an arm member, wherein the second portion is provided with a second reduction mechanism that converts rotation of the second motor into rotation about the second rotation axis and transmits the rotation to the second member, the second reduction mechanism having a second connecting gear that is connected to the second motor and rotatable about an axis parallel to the longitudinal direction; the first portion and the third portion respectively have first and second mating surfaces that mate with each other in the longitudinal direction, the first and second mating surfaces being cylindrical surfaces that are arranged coaxially with the first connecting gear or the first motor; the second portion and the third portion respectively have third and fourth mating surfaces that mate with each other in the longitudinal direction, the third and fourth mating surfaces being cylindrical surfaces that are arranged coaxially with the second connecting gear or the second motor; and the first and second mating surfaces and the third and fourth mating surfaces are arranged at positions offset from each other in a direction perpendicular to the longitudinal direction.

[0049] (Supplementary Note 2) An arm member described in Supplementary Note 1, wherein the first reduction mechanism has a first output hypoid gear arranged coaxially with the first rotation axis and fixed to the first member, and a first input hypoid gear supported rotatably about an axis parallel to the longitudinal direction and meshing with the first output hypoid gear, and the second reduction mechanism has a second output hypoid gear arranged coaxially with the second rotation axis and fixed to the second member, and a second input hypoid gear supported rotatably about an axis parallel to the longitudinal direction and meshing with the second output hypoid gear.

[0050] (Supplementary Note 3) The arm member according to Supplementary Note 1 or Supplementary Note 2, wherein the first fitting surface or the second fitting surface is an outer surface of a first annular member provided in the first portion or the third portion, and the third fitting surface or the fourth fitting surface is an outer surface of a second annular member provided in the second portion or the third portion. (Supplementary Note 4) The arm member according to Supplementary Note 3, wherein the first annular member is a first bearing provided in the first portion and supporting the first connecting gear.

[0051] (Supplementary Note 5) The arm member according to Supplementary Note 3 or Supplementary Note 4, wherein the second annular member is a second bearing provided in the second portion and supporting the second connecting gear. (Supplementary Note 6) The arm member according to any one of Supplementary Notes 1 to 5, wherein the first motor and the second motor are arranged parallel to each other in a direction perpendicular to the longitudinal direction.

[0052] (Supplementary Note 7) An arm member described in any one of Supplementary Notes 1 to 6, wherein the first part, the second part, and the third part are detachably connected to one another, the first part has a first reference surface provided on the outside of the first part, the second part has a second reference surface provided on the outside of the second part, the first reference surface is a flat surface parallel to the output surface of the first reduction mechanism, and the second reference surface is a flat surface parallel to the output surface of the second reduction mechanism.

[0053] (Appendix 8) An arm member according to Appendix 7, wherein the third portion has a third reference surface provided on the outside of the third portion, and the third reference surface is a flat surface that is positioned at a predetermined angle relative to the first reference surface and the second reference surface when the first reference surface and the second reference surface are positioned parallel to each other.

[0054] (Supplementary Note 9) The arm member according to Supplementary Note 7 or Supplementary Note 8, wherein the first reference surface is disposed at a position away from central axes of the first mating surface and the second mating surface when the first reference surface is viewed from the front, and the second reference surface is disposed at a position away from central axes of the third mating surface and the fourth mating surface when the second reference surface is viewed from the front. (Supplementary Note 10) A robot comprising the arm member according to any one of Supplementary Notes 1 to 9, a first member, and a second member.

[0055] (Supplementary Note 11) A robot as described in Supplementary Note 10, comprising: a rotating body supported rotatably about a first axis relative to a base; a first arm supported rotatably about a second axis perpendicular to the first axis relative to the rotating body; and a second arm supported rotatably about a third axis parallel to the second axis relative to the first arm, wherein the rotating body is the first member, the first arm is the arm member, and the second arm is the second member.

[0056] DESCRIPTION OF SYMBOLS 1 Robot 3 Rotating body (first member) 4 First arm (arm member) 4A Lower stage (first portion) 4B Upper stage (second portion) 4C Middle stage (third portion) 4a Base end (first end) 4b Tip end (second end) 5 Second arm (second member) 8, 9 Motor 10, 11 Reduction mechanism 12, 13 Bearing (annular member) 12a, 13a, 18a, 19a Fitting surface 141, 161 Ring gear (output hypoid gear) 142, 162 Pinion gear unit (input hypoid gear) 15, 17 Intermediate gear unit (connecting gear) 21, 22, 23a, 23b Reference surface A Longitudinal direction J2 Second axis (first rotation axis) J3 Third axis (second rotation axis)

Claims

1. An arm member having a longitudinal direction and a first end and a second end which are both ends in the longitudinal direction, the first end being connected to a first member so as to be rotatable about a first axis of rotation that intersects with the longitudinal direction, and the second end being connected to a second member so as to be rotatable about a second axis of rotation that intersects with the longitudinal direction, the arm member comprising a first part including the first end, a second part including the second end, and a third part sandwiched between the first part and the second part, the first part, the second part, and the third part being mutually connected in the longitudinal direction, the third part having a first motor and a second motor which respectively rotate about an axis parallel to the longitudinal direction, the first part comprising a first reduction mechanism which converts the rotation of the first motor into rotation about the first axis of rotation and transmits the rotation to the first member, the first reduction mechanism having a first connecting gear which is connected to the first motor and is rotatable about an axis parallel to the longitudinal direction, an arm member, wherein the second part is provided with a second reduction mechanism that converts rotation of the second motor into rotation about the second rotation axis and transmits the rotation to the second member, the second reduction mechanism having a second connecting gear that is connected to the second motor and rotatable about an axis parallel to the longitudinal direction; the first part and the third part each have a first fitting surface and a second fitting surface that fit with each other in the longitudinal direction, the first fitting surface and the second fitting surface being cylindrical surfaces that are arranged coaxially with the first connecting gear or the first motor; the second part and the third part each have a third fitting surface and a fourth fitting surface that fit with each other in the longitudinal direction, the third fitting surface and the fourth fitting surface being cylindrical surfaces that are arranged coaxially with the second connecting gear or the second motor; and the first and second fitting surfaces and the third and fourth fitting surfaces are arranged at positions offset from each other in a direction perpendicular to the longitudinal direction.

2. An arm member as described in claim 1, wherein the first reduction mechanism has a first output hypoid gear arranged coaxially with the first rotation axis and fixed to the first member, and a first input hypoid gear supported rotatably about an axis parallel to the longitudinal direction and meshing with the first output hypoid gear, and the second reduction mechanism has a second output hypoid gear arranged coaxially with the second rotation axis and fixed to the second member, and a second input hypoid gear supported rotatably about an axis parallel to the longitudinal direction and meshing with the second output hypoid gear.

3. An arm member as described in claim 1 or claim 2, wherein the first mating surface or the second mating surface is the outer surface of a first annular member provided on the first part or the third part, and the third mating surface or the fourth mating surface is the outer surface of a second annular member provided on the second part or the third part.

4. An arm member according to claim 3, wherein said first annular member is a first bearing provided in said first portion and supporting said first connecting gear.

5. An arm member according to claim 3 or 4, wherein the second annular member is a second bearing provided in the second portion and supporting the second connecting gear.

6. An arm member according to any one of claims 1 to 5, wherein the first motor and the second motor are arranged in parallel with each other in a direction perpendicular to the longitudinal direction.

7. An arm member according to any one of claims 1 to 6, wherein the first part, the second part and the third part are connected to each other in a detachable manner, the first part has a first reference surface provided on the outside of the first part, the second part has a second reference surface provided on the outside of the second part, the first reference surface is a flat surface parallel to the output surface of the first reduction mechanism, and the second reference surface is a flat surface parallel to the output surface of the second reduction mechanism.

8. An arm member as described in claim 7, wherein the third portion has a third reference surface provided on the outside of the third portion, and the third reference surface is a flat surface that is disposed at a predetermined angle with respect to the first reference surface and the second reference surface when the first reference surface and the second reference surface are disposed parallel to each other.

9. An arm member as described in claim 7 or claim 8, wherein the first reference surface is positioned at a position away from the central axes of the first mating surface and the second mating surface when the first reference surface is viewed from the front, and the second reference surface is positioned at a position away from the central axes of the third mating surface and the fourth mating surface when the second reference surface is viewed from the front.

10. A robot comprising an arm member according to any one of claims 1 to 9, a first member, and a second member.

11. The robot described in claim 10, comprising: a rotating body supported rotatably about a first axis relative to a base; a first arm supported rotatably about a second axis perpendicular to the first axis relative to the rotating body; and a second arm supported rotatably about a third axis parallel to the second axis relative to the first arm, wherein the rotating body is the first member, the first arm is the arm member, and the second arm is the second member.

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