Robot arm

Abstract

To provide a robot arm configured so that tooth contact between a first gear and a second gear can be adjusted, without changing pressurization of a bearing.SOLUTION: A robot arm comprises: a first arm; a second arm having a placement surface, connected to the first arm to turn around a first rotary shaft; a bearing case placed on the placement surface; a bearing stored in the bearing case in a pressurized state; a first gear inserted into the second arm while penetrating through the bearing case and born by the bearing case through the bearing to rotate around the first rotary shaft; a second gear born by the second arm and engaged with the first gear in the second arm; and an adjustment member intervened between the placement surface and the bearing case, and adjusting tooth-contact between the first gear and the second gear by adjusting a separation distance between the placement surface and the bearing case.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a robot arm. [Background technology]

[0002] Patent Document 1 discloses a six-axis vertical articulated robot having a base and a robot arm connected to the base. The robot arm has a shoulder connected to the base to be rotatable around a first rotation axis, a lower arm connected to the shoulder to be rotatable around a second rotation axis, a first upper arm connected to the lower arm to be rotatable around a third rotation axis, a second upper arm connected to the first upper arm to be rotatable around a fourth rotation axis, a wrist connected to the second upper arm to be rotatable around a fifth rotation axis, and a flange connected to the wrist to be rotatable around a sixth rotation axis.

[0003] The wrist is provided with an input bevel gear that rotates about the fifth rotation shaft, and an output bevel gear that meshes with the input bevel gear and rotates about the sixth rotation shaft. The input bevel gear and the output bevel gear are each journaled in the wrist via a bearing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-070647 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a vertical articulated robot with such a configuration, when the input bevel gear is moved in a direction along the fifth rotation shaft to adjust the tooth contact with the output bevel gear, the magnitude of the preload on the bearing that supports the input bevel gear changes accordingly. In other words, it is not possible to adjust the tooth contact between the input bevel gear and the output bevel gear without changing the preload on the bearing. [Means for solving the problem]

[0006] The robot arm of the present invention includes a first arm, a second arm connected to the first arm so as to be rotatable about a first rotation axis and having a mounting surface; A bearing case placed on the mounting surface; a fixing member that fixes the bearing case to the second arm; a bearing housed in the bearing case in a preloaded state; a first gear that penetrates the bearing case and is inserted into the second arm and is journaled by the bearing case via the bearing so as to rotate about the first rotation axis; a second gear journaled on the second arm and meshing with the first gear within the second arm; and an adjustment member that is interposed between the mounting surface and the bearing case and adjusts the tooth contact between the first gear and the second gear by adjusting the separation distance between the mounting surface and the bearing case in a direction along the first rotation axis. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram showing an overall configuration of a robot system according to a preferred embodiment. [Diagram 2] FIG. 4 is a cross-sectional view showing the inside of the arm. [Diagram 3] FIG. 4 is a cross-sectional view showing the inside of the arm. [Figure 4] FIG. 11 is a cross-sectional view showing the input bevel gear unit removed from the arm. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, a preferred embodiment of a robot arm will be described with reference to the accompanying drawings.

[0009] Fig. 1 is a diagram showing an overall configuration of a robot system according to a preferred embodiment. Fig. 2 is a cross-sectional view showing the inside of an arm. Fig. 3 is a cross-sectional view showing the inside of an arm. Fig. 4 is a cross-sectional view showing a state in which an input bevel gear unit is removed from the arm.

[0010] The robot system 1 shown in FIG. 1 includes a robot 2 and a robot controller 10 that controls the driving of the robot 2.

[0011] The robot 2 is a vertical articulated robot having six drive axes. The robot 2 has a base 21 fixed to the floor and a robot arm 22 connected to the base 21.

[0012] The robot arm 22 has an arm 221 connected to the base 21 and rotatable around a rotation axis J1 relative to the base 21, an arm 222 connected to the arm 221 and rotatable around a rotation axis J2 relative to the arm 221, an arm 223 connected to the arm 222 and rotatable around a rotation axis J3 relative to the arm 222, an arm 224 connected to the arm 223 and rotatable around a rotation axis J4 relative to the arm 223, an arm 225 connected to the arm 224 and rotatable around a rotation axis J5 as a first rotation axis relative to the arm 224, and an arm 226 connected to the arm 225 and rotatable around a rotation axis J6 relative to the arm 225. The end effector 24 is connected to the tip of the arm 226.

[0013] The robot 2 also has a drive mechanism 231 that rotates the arm 221 around a rotation axis J1 relative to the base 21, a drive mechanism 232 that rotates the arm 222 around a rotation axis J2 relative to the arm 221, a drive mechanism 233 that rotates the arm 223 around a rotation axis J3 relative to the arm 222, a drive mechanism 234 that rotates the arm 224 around a rotation axis J4 relative to the arm 223, a drive mechanism 235 that rotates the arm 225 around a rotation axis J5 relative to the arm 224, and a drive mechanism 236 that rotates the arm 226 around a rotation axis J6 relative to the arm 225.

[0014] The robot controller 10 controls the driving mechanisms 231-236 independently and causes the robot 2 to perform a predetermined task. The robot controller 10 is, for example, configured as a computer, and has a processor for processing information, a memory communicatively connected to the processor, and an external interface. In addition, various programs executable by the processor are stored in the memory, and the processor can read and execute the various programs stored in the memory.

[0015] The above is a brief description of the robot system 1. However, the configuration of the robot system 1 is not particularly limited. For example, the robot 2 may be a horizontal articulated robot (SCARA robot), a dual-arm robot having two arms, or the like, in addition to a six-axis robot. Furthermore, the robot 2 does not need to be fixed to the floor, and may be fixed to an automated guided vehicle such as an AMR (Autonomous Mobile Robot) or an AGV (Automatic Guided Vehicle).

[0016] Next, a detailed description will be given of drive mechanism 235 that rotates arm 225 about rotation axis J5 relative to arm 224, and drive mechanism 236 that rotates arm 226 about rotation axis J6 relative to arm 225, with reference to Figures 2 to 4. Note that, for ease of explanation, the upper side of Figures 2 to 4 will be referred to as "upper" and the lower side will be referred to as "lower" below.

[0017] 2, arm 224 has a bifurcated tip portion, and supports arm 225 at both sides of rotation axis J5 between the bifurcated tip portion. Driving mechanism 236 is disposed at upper tip portion 224a, and driving mechanism 235 is disposed at lower tip portion 224b. By supporting arm 225 at both ends in this manner, the rotation accuracy of arm 225 is improved, and separate spaces for disposing driving mechanisms 235 and 236 can be secured.

[0018] The arm 224 has a housing 31 and a cover 32 attached to the housing 31. The base end of the housing 31 is rotatably connected to the arm 223, and the tip end of the housing 31 is rotatably connected to the arm 225. A through hole 311 is formed in the upper tip 224a of the housing 31, the through hole 311 being concentric with the rotation axis J5. The through hole 311 is formed at a position overlapping with an input bevel gear unit 5 (described later) attached to the arm 225 in a plan view from the direction along the rotation axis J5, and is larger than the input bevel gear unit 5. Therefore, the input bevel gear unit 5 can be removed from the arm 225 through the through hole 311.

[0019] The arm 225 is formed with a cylindrical first insertion hole 251 along the rotation axis J5 and a cylindrical second insertion hole 252 along the rotation axis J6. The first insertion hole 251 opens to the tip 224a side, and the central axis coincides with the rotation axis J5. The second insertion hole 252 opens to the arm 226 side, and the central axis coincides with the rotation axis J6. The first insertion hole 251 and the second insertion hole 252 are connected at their tips perpendicular to each other within the arm 225. The input bevel gear unit 5 is inserted into the first insertion hole 251, and the output bevel gear 66 is inserted into the second insertion hole 252. However, the first and second insertion holes 251 and 252 are not limited to being cylindrical, and may be polygonal such as a square or hexagon, elliptical, or irregular in plan view.

[0020] The first insertion hole 251 has an inner diameter that decreases in three steps toward the bottom, and has a base end 251a, a central portion 251b located below the base end 251a and having a smaller diameter than the base end 251a, and a tip end 251c located below the central portion 251b and having a smaller diameter than the central portion 251b. At the boundary between the base end 251a and the central portion 251b, a mounting surface 251d is formed that is a step surface perpendicular to the rotation axis J5 and faces upward. At the boundary between the central portion 251b and the tip end 251c, a tapered guide portion 251e is formed whose inner diameter gradually decreases toward the bottom. The "diameter" can be rephrased as "width" when the planar shape of the first and second insertion holes 251 and 252 is other than circular.

[0021] Furthermore, the drive mechanism 235 has a motor 41 with a built-in encoder fixed to the housing 31, a speed reducer 42 that reduces the rotation of the motor 41, a pulley 43 attached to the output shaft of the motor 41, a pulley 44 attached to the speed reducer 42, and a power transmission belt 45 that is wound around the pulleys 43, 44. The speed reducer 42 is a wave gear device, and a circular spline 422 is fixed to the housing 31, and a flex spline 423 is fixed to the arm 225. Furthermore, the pulley 44 is fixed to the wave generator 421.

[0022] According to this configuration, the rotation of the motor 41 is transmitted to the wave generator 421 of the reducer 42 via the pulley 43, the power transmission belt 45, and the pulley 44, causing the wave generator 421 to rotate. Furthermore, the flexspline 423 rotates at a predetermined reduction ratio relative to the rotation of the wave generator 421, causing the arm 225 to rotate about the rotation axis J5 relative to the arm 224.

[0023] Although the driving mechanism 235 has been described above, the configuration of the driving mechanism 235 is not particularly limited.

[0024] The drive mechanism 236 has an input bevel gear unit 5 inserted into the first insertion hole 251 and placed on the mounting surface 251d. As shown in Fig. 3, the input bevel gear unit 5 has a bearing case 51 placed on the mounting surface 251d, a bearing 52 accommodated in the bearing case 51 in a preloaded state, and an input bevel gear 53 which is a first gear that passes through the bearing case 51 and is journaled in the bearing case 51 via the bearing 52.

[0025] The bearing case 51 has a cylindrical shape that matches the shape of the first insertion hole 251. The bearing case 51 has a base 511 and a cover 512 that is located above the base 511 and fixed to the base 511. An accommodation space for accommodating the bearing 52 and the input bevel gear 53 is formed inside the bearing case 51. However, the shape of the bearing case 51 is not limited to a cylindrical shape and can be determined according to the shape of the first insertion hole 251.

[0026] The outer diameter of the base 511 is tapered in three steps toward the bottom, and includes a base end 511a, a central portion 511b located below the base end 511a and having a smaller diameter than the base end 511a, and a tip end 511c located below the central portion 511b and having a smaller diameter than the central portion 511b. At the boundary between the base end 511a and the central portion 511b, a placement surface 511d is formed that is a step surface perpendicular to the rotation axis J5 and faces downward. At the tip end 511c, a flange 511e is formed that protrudes into the storage space. On the other hand, the lid 512 is located above the base 511 and is fastened and fixed to the base end 511a by a screw (not shown). The base 511 and the lid 512 are made of a metal material such as aluminum or stainless steel.

[0027] The bearing case 51 as described above is inserted into the first insertion hole 251 from the base body 511 side, and the mounting surface 511d is mounted on the mounting surface 251d. This facilitates attachment of the bearing case 51 to the arm 225. In addition, at this time, the tip portion 511c of the bearing case 51 is guided to the tip portion 251c by the guide portion 251e of the first insertion hole 251 before the mounting surface 511d is mounted on the mounting surface 251d, so that the bearing case 51 is easily inserted into the first insertion hole 251. The bearing case 51 is fastened and fixed to the arm 225 by a plurality of screws N as fixing members in a state where it is mounted on the mounting surface 251d. In a state where the bearing case 51 is fixed to the arm 225, the input bevel gear 53 rotates around the rotation axis J5. Note that the fixing member for fixing the bearing case 51 to the arm 225 is not particularly limited.

[0028] The bearing 52 is disposed in the housing space of the bearing case 51. The bearing 52 includes a first bearing 521 and a second bearing 522. The first and second bearings 521, 522 are disposed at a distance from each other along the rotation axis J5. By disposing the first and second bearings 521, 522 at a distance from each other, the input bevel gear 53 is supported at two points spaced apart from each other, and thus the rotation of the input bevel gear 53 is stabilized.

[0029] The first bearing 521 is an angular ball bearing, and has a first outer ring 521a supported on the inner circumferential surface of the base body 511, a first inner ring 521b into which the input bevel gear 53 is inserted, and a ball 521c as a first rotating body arranged between the first outer ring 521a and the first inner ring 521b. Similarly, the second bearing 522 is an angular ball bearing, and has a second outer ring 522a supported on the inner circumferential surface of the base body 511, a second inner ring 522b into which the input bevel gear 53 is inserted, and a ball 522c as a second rotating body arranged between the second outer ring 522a and the second inner ring 522b.

[0030] The input bevel gear 53 has a shaft 531 that passes through the bearing case 51 and is journalled in the bearing case 51 via first and second bearings 521, 522, and a gear portion 532 that is disposed at the tip of the shaft 531 and located below the bearing case 51. In addition, the gear portion 532 is located at the tip of the first insertion hole 251 and faces the second insertion hole 252.

[0031] The input bevel gear unit 5 further includes a preload mechanism 59 for preloading the first and second bearings 521 and 522. The preload mechanism 59 includes a preload member 54 disposed between the first bearing 521 and the cover 512, and a preload transmission member 55 disposed between the first bearing 521 and the second bearing 522. The preload member 54 is an annular (ring-shaped) spacer shim, and is sandwiched between the cover 512 and the first outer ring 521a of the first bearing 521. On the other hand, the preload transmission member 55 is a cylindrical spacer through which the input bevel gear 53 is inserted, and is disposed between the first inner ring 521b of the first bearing 521 and the second inner ring 522b of the second bearing 522. The second outer ring 522a of the second bearing 522 abuts against the flange 511e, and further displacement is restricted.

[0032] The preload member 54 is pressed against the first outer ring 521a by the cover 512, and presses the first outer ring 521a downward. The force received by the first outer ring 521a from the preload member 54 is transmitted from the first inner ring 521b to the second inner ring 522b via the preload transmission member 55, and presses the second inner ring 522b downward. As a result, the first and second bearings 521 and 522 are preloaded evenly. The thicker the preload member 54 is, the stronger the force pressing the first outer ring 521a becomes, and the greater the preload of the first and second bearings 521 and 522 becomes. Therefore, by adjusting the thickness of the preload member 54, the first and second bearings 521 and 522 can be preloaded with a desired force. As a result, the rotational accuracy and rigidity of the first and second bearings 521 and 522 are improved.

[0033] The method for adjusting the thickness of the preload member 54 is not particularly limited. For example, a plurality of preload members 54 having different thicknesses may be prepared, and one of them may be selected and used to adjust the thickness of the preload member 54. Alternatively, a plurality of preload members 54 having the same thickness may be prepared, and the number of preload members 54 to be used may be selected to adjust the thickness of the preload member 54. According to these methods, the thickness of the preload member 54 can be easily adjusted. The preload member 54 is not limited to a spacer shim, and may be, for example, a wave washer. In this case, the thickness of the preload member 54 can be adjusted by elastically deforming the wave washer by tightening the screw so as to crush it.

[0034] The input bevel gear unit 5 has been described above. In this manner, in this embodiment, the bearing case 51, the bearing 52, the input bevel gear 53, and the preload mechanism 59 are unitized as the input bevel gear unit 5. Therefore, these can be attached to the arm 225 or removed from the arm 225 all at once, facilitating assembly and adjustment of the robot 2. In addition, the preload of the first and second bearings 521, 522 can be adjusted before attachment to the arm 225, facilitating this operation.

[0035] The configuration of the input bevel gear unit 5 is not particularly limited. For example, the bearing case 51 is composed of a base body 511 and a cover body 512, but is not limited to this, and may be configured with three or more members connected. The base body 511 and the cover body 512 are screwed together, but the method of fixing them is not particularly limited. The number of bearings is not limited to two, and may be one, or three or more. The first bearing 521 and the second bearing 522 do not have to be angular ball bearings, and may be, for example, angular roller bearings. In the figure, the first bearing 521 is larger than the second bearing 522, but is not limited to this, and the first bearing 521 may be smaller than the second bearing 522 or may be the same.

[0036] 2, the drive mechanism 236 further includes a motor 61 with a built-in encoder, a pulley 63 attached to the output shaft of the motor 61, a pulley 64 attached to the input bevel gear 53, and a power transmission belt 65 wound around the pulley 63 and the pulley 64. The drive mechanism 236 further includes an output bevel gear 66, which is a second gear connected to the arm 226. The output bevel gear 66 includes a shaft 661 inserted into the second insertion hole 252 and journaled on the arm 225 via a bearing, and a gear portion 662 disposed at the tip of the shaft 661 and meshing with the gear portion 532 in the arm 225. The rotation axis of the output bevel gear 66 coincides with the rotation axis J6.

[0037] In the drive mechanism 236 configured as above, the rotation of the motor 61 is transmitted to the input bevel gear 53 via the pulley 63, the power transmission belt 65, and the pulley 64, causing the input bevel gear 53 to rotate. Furthermore, the rotation of the input bevel gear 53 is transmitted to the output bevel gear 66, causing the arm 226 connected to the output bevel gear 66 to rotate about the rotation axis J6.

[0038] As shown in FIG. 3, the drive mechanism 236 further includes an adjustment member 7 for adjusting the tooth contact and backlash between the input bevel gear 53 and the output bevel gear 66. The adjustment member 7 is an annular (ring-shaped) spacer shim, and is sandwiched between the mounting surface 251d and the mounted surface 511d. The adjustment member 7 is a member for adjusting the separation distance between the mounting surface 251d and the mounted surface 511d along the rotation axis J5. The thicker the adjustment member 7 is, the more the input bevel gear unit 5 is displaced upward relative to the arm 225, and the meshing between the input bevel gear 53 and the output bevel gear 66 becomes shallower accordingly. Therefore, by adjusting the thickness of the adjustment member 7, the position of the input bevel gear 53 can be determined, and the tooth contact and backlash between the input bevel gear 53 and the output bevel gear 66 can be adjusted. This can improve the transmission accuracy of the rotational motion, reduce noise, and extend the life, etc.

[0039] The method for adjusting the thickness of the adjustment member 7 is not particularly limited. For example, a plurality of adjustment members 7 having different thicknesses may be prepared, and one of them may be selected and used to adjust the thickness of the adjustment member 7. Alternatively, a plurality of adjustment members 7 having the same thickness may be prepared, and the number of adjustment members 7 to be used may be selected to adjust the thickness of the adjustment member 7. According to these methods, the thickness of the adjustment member 7 can be easily adjusted. The adjustment member 7 is not limited to a spacer shim, and may be, for example, a wave washer. In this case, the thickness of the adjustment member 7 can be adjusted by tightening the screw N to elastically deform the wave washer so as to crush it.

[0040] In particular, in this embodiment, the bearing case 51, the bearing 52, the input bevel gear 53, and the preload mechanism 59 are unitized as the input bevel gear unit 5. Therefore, when adjusting the tooth contact and backlash between the input bevel gear 53 and the output bevel gear 66, the adjustment member 7 can be replaced simply by removing the input bevel gear unit 5 from the arm 225 as shown in Fig. 4. Furthermore, even if the input bevel gear unit 5 is removed from the arm 225, the preloads of the first and second bearings 521 and 522 are kept constant without being affected by this. Therefore, the tooth contact and backlash between the input bevel gear 53 and the output bevel gear 66 can be adjusted without causing fluctuations in the preload.

[0041] As described above, the input bevel gear unit 5 can be removed from the arm 225 through the through hole 311 formed in the housing 31. Therefore, the adjustment member 7 can be replaced while the arm 224 and the arm 225 are connected. Therefore, the tooth contact and backlash between the input bevel gear 53 and the output bevel gear 66 can be easily adjusted.

[0042] In addition, both the first and second bearings 521, 522 are disposed in the bearing case 51. Therefore, the first and second bearings 521, 522 are protected by the bearing case 51. Therefore, when adjusting the tooth contact and backlash between the input bevel gear 53 and the output bevel gear 66, even if the input bevel gear unit 5 is repeatedly attached and detached to and from the arm 225 in order to replace the adjustment member 7, the first and second bearings 521, 522 do not directly hit the arm 224, the arm 225, etc., and damage and destruction of the first and second bearings 521, 522 can be effectively suppressed.

[0043] According to the drive mechanism 236 as described above, by changing the thickness of the preload member 54, it is possible to adjust only the preload of the first and second bearings 521, 522 without causing fluctuations in the tooth contact and backlash between the input bevel gear 53 and the output bevel gear 66. Also, by adjusting the thickness of the adjustment member 7, it is possible to adjust only the tooth contact and backlash between the input bevel gear 53 and the output bevel gear 66 without causing fluctuations in the preload of the first and second bearings 521, 522. In other words, it is possible to adjust the preload of the first and second bearings 521, 522 and the tooth contact and backlash between the input bevel gear 53 and the output bevel gear 66 independently of each other.

[0044] The above has described the robot system 1. As described above, the robot arm 22 of the robot system 1 includes the arm 224 which is a first arm, the arm 225 which is a second arm connected to the arm 224 so as to rotate about the rotation axis J5 which is a first rotation axis and has a mounting surface 251d, the bearing case 51 which is mounted on the mounting surface 251d, the screw N which is a fixing member which fixes the bearing case 51 to the arm 225, the bearing 52 which is accommodated in the bearing case 51 in a preloaded state, and the screw N which penetrates the bearing case 51 and connects the arm 225 to the bearing case 51. The arm 225 includes an input bevel gear 53, which is a first gear, inserted into the arm 225 and journaled in the bearing case 51 via a bearing 52 so as to rotate about a rotation axis J5, an output bevel gear 66, which is a second gear journaled in the arm 225 and meshed with the input bevel gear 53 within the arm 225, and an adjustment member 7, which is interposed between the mounting surface 251d and the bearing case 51 and adjusts the distance between the mounting surface 251d and the bearing case 51 in the direction along the rotation axis J5, thereby adjusting the tooth contact between the input bevel gear 53 and the output bevel gear 66. With this configuration, by adjusting the thickness of the adjustment member 7, it is possible to adjust the tooth contact between the input bevel gear 53 and the output bevel gear 66 without causing a fluctuation in the preload of the first and second bearings 521 and 522. This makes the operation easier.

[0045] As described above, the bearing case 51, the bearing 52, and the input bevel gear 53 are unitized as the input bevel gear unit 5. This makes it easy to attach the bearing case 51, the bearing 52, and the input bevel gear 53 to the arm 225 and remove them from the arm 225. Also, the preload of the bearing 52 can be adjusted before attaching it to the arm 225, making this operation easy.

[0046] As described above, the arm 225 has a through hole 311 larger than the bearing case 51 at a position overlapping with the bearing case 51 in a plan view from the direction along the rotation axis J5. With this configuration, the input bevel gear unit 5 can be removed from the arm 225 via this through hole 311. Therefore, the adjustment member 7 can be replaced while the arm 224 and the arm 225 are connected to adjust the tooth contact and backlash between the input bevel gear 53 and the output bevel gear 66. This makes it easy to perform the adjustment work.

[0047] As described above, the bearing case 51 has the base 511 that supports the bearing 52, and the lid 512 that is fixed to the base 511. The robot arm 22 has a preload member 54 that is located between the bearing 52 and the lid 512 and preloads the bearing 52 in the direction along the rotation axis J5. This makes it possible to preload the bearing 52 with a simple configuration. Also, by changing the thickness of the preload member 54, the magnitude of the preload can be easily adjusted.

[0048] As described above, the bearing 52 has the first bearing 521 and the second bearing 522 that are spaced apart in the direction along the rotation axis J5. This allows the input bevel gear 53 to be supported at two spaced apart points, stabilizing the rotation of the input bevel gear 53.

[0049] As described above, the first bearing 521 comes into contact with the preload member 54. The robot arm 22 also has a preload transmission member 55 that is disposed between the first bearing 521 and the second bearing 522 and transmits the force that the first bearing 521 receives from the preload member 54 to the second bearing 522. This allows the preload member 54 and the preload transmission member 55 to preload the first and second bearings 521, 522 evenly.

[0050] As described above, the first bearing 521 has a first outer ring 521a supported by the bearing case 51, a first inner ring 521b through which the input bevel gear 53 is inserted, and a ball 521c that is a first rotating body disposed between the first outer ring 521a and the first inner ring 521b. Similarly, the second bearing 522 has a second outer ring 522a supported by the bearing case 51, a second inner ring 522b through which the input bevel gear 53 is inserted, and a ball 522c that is a second rotating body disposed between the second outer ring 522a and the second inner ring 522b. The first outer ring 521a and the second outer ring 522a are supported by the bearing case 51, the first outer ring 521a abuts against the preload member 54, and a preload transmission member 55 is disposed between the first inner ring 521b and the second inner ring 522b. According to this configuration, the force received by the first outer ring 521a from the preload member 54 is transmitted to the second bearing 522 via the preload transmission member 55, so that the first and second bearings 521, 522 are preloaded evenly.

[0051] While the robot arm of the present invention has been described above based on the illustrated embodiment, the present invention is not limited thereto, and the configuration of each part can be replaced with any configuration having a similar function. In addition, any other configuration may be added to the present invention.

[0052] In addition, in the above-described embodiment, the first gear is the input bevel gear 53 and the second gear is the output bevel gear 66, but this is not limiting, and the first gear may be the output bevel gear 66 and the second gear may be the input bevel gear 53. In other words, the output bevel gear 66 may be unitized as an output bevel gear unit together with a bearing case, a bearing, and a preload mechanism. [Explanation of symbols]

[0053] 1...robot system, 10...robot controller, 2...robot, 21...base, 22...robot arm, 221...arm, 222...arm, 223...arm, 224...arm, 224a...tip portion, 224b...tip portion, 225...arm, 226...arm, 231...driving mechanism, 232...driving mechanism, 233...driving mechanism, 234...driving mechanism, 235...driving mechanism, 236...driving mechanism, 24...energy end effector, 251...first insertion hole, 251a...base end, 251b...center, 251c...tip end, 251d...mounting surface, 251e...guide portion, 252...second insertion hole, 31...housing, 311...through hole, 32...cover, 41...motor, 42...reduction gear, 421...wave generator, 422...circular spline, 423...flex spline, 43...pulley, 44...pulley, 45...moving Force transmission belt, 5...input bevel gear unit, 51...bearing case, 511...base body, 511a...base end portion, 511b...center portion, 511c...tip portion, 511d...receiving surface, 511e...flange, 512...lid body, 52...bearing, 521...first bearing, 521a...first outer ring, 521b...first inner ring, 521c...ball, 522...second bearing, 522a...second outer ring, 522b...second inner ring, 522c...ball, 53...input bevel gear, 531...shaft, 532...gear portion, 54...preload member, 55...preload transmission member, 59...preload mechanism, 61...motor, 63...pulley, 64...pulley, 65...power transmission belt, 66...output bevel gear, 661...shaft, 662...gear portion, 7...adjustment member, J1...rotating shaft, J2...rotating shaft, J3...rotating shaft, J4...rotating shaft, J5...rotating shaft, J6...rotating shaft, N...screw

Claims

1. A first arm; a second arm connected to the first arm so as to be rotatable about a first rotation axis and having a mounting surface; A bearing case placed on the mounting surface; a fixing member that fixes the bearing case to the second arm; a bearing housed in the bearing case in a preloaded state; a first gear that penetrates the bearing case and is inserted into the second arm, and is journaled by the bearing case via the bearing so as to rotate about the first rotation axis; a second gear journaled on the second arm and meshing with the first gear within the second arm; and an adjustment member interposed between the mounting surface and the bearing case, the adjustment member adjusting the tooth contact between the first gear and the second gear by adjusting the separation distance between the mounting surface and the bearing case in a direction along the first rotation axis.

2. The robot arm according to claim 1 , wherein the bearing case, the bearing, and the first gear are unitized.

3. The robot arm according to claim 2 , wherein the first arm has a through hole larger than the bearing case at a position overlapping with the bearing case in a plan view from a direction along the first rotation axis.

4. the bearing case has a base body that supports the bearing and a cover body that is fixed to the base body, 2. The robot arm according to claim 1, further comprising a preload member positioned between the bearing and the cover, preloading the bearing in a direction along the first rotation axis.

5. The robot arm according to claim 1 , wherein the bearing comprises a first bearing and a second bearing spaced apart from each other in a direction along the first rotation axis.

6. the first bearing abuts against the preload member, 6. The robot arm according to claim 5, further comprising a preload transmission member disposed between the first bearing and the second bearing, for transmitting the preload received by the first bearing to the second bearing.

7. the first bearing includes a first outer ring supported by the bearing case, a first inner ring through which the first gear is inserted, and a first rotating body disposed between the first outer ring and the first inner ring, the second bearing includes a second outer ring supported by the bearing case, a second inner ring through which the first gear is inserted, and a second rotating body disposed between the second outer ring and the second inner ring, the first outer ring and the second outer ring are supported by the bearing case, the first outer ring abuts against the preload member, 6. The robot arm according to claim 5, wherein the preload transmission member is disposed between the first inner ring and the second inner ring.

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