Mechanical arm

Abstract

The invention provides a robot arm capable of performing tooth contact adjustment between a first gear and a second gear without changing the preload of a bearing. The robot arm includes: a first arm; a second arm connected to the first arm so as to rotate about a first rotation axis and having a placement surface; a bearing box mounted on the mounting surface; a bearing housed in the bearing housing in a pre-pressed state; a first gear which is inserted into the second arm through the bearing housing and is axially supported by the bearing housing via a bearing so as to rotate around a first rotation axis; a second gear supported by a shaft on the second arm and engaged with the first gear in the second arm; and an adjusting member that is interposed between the placement surface and the bearing housing and adjusts the tooth contact between the first gear and the second gear by adjusting the separation distance between the placement surface and the bearing housing.

Description

Technical Field

[0001] The invention relates to a robotic arm. Background Art

[0002] Patent document 1 discloses a vertical multi-joint robot having a six-axis structure including a base and a robot arm connected to the base. The robot arm includes: a shoulder connected to the base in a manner that allows rotation around a first rotation axis; a lower arm connected to the shoulder in a manner that allows rotation around a second rotation axis; a first upper arm connected to the lower arm in a manner that allows rotation around a third rotation axis; a second upper arm connected to the first upper arm in a manner that allows rotation around a fourth rotation axis; a wrist connected to the second upper arm in a manner that allows rotation around a fifth rotation axis; and a flange connected to the wrist in a manner that allows rotation around a sixth rotation axis.

[0003] In addition, an input bevel gear that rotates around a fifth rotation axis and an output bevel gear that meshes with the input bevel gear and rotates around a sixth rotation axis are arranged on the wrist portion. In addition, the input bevel gear and the output bevel gear are axially supported on the wrist portion via bearings.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2022-070647

[0005] However, in a vertical multi-joint robot of such a structure, when the input bevel gear is moved in the direction along the fifth rotation axis in order to adjust the tooth contact with the output bevel gear, the preload of the bearing supporting the input bevel gear also changes accordingly. In other words, it is impossible to adjust the tooth contact between the input bevel gear and the output bevel gear without changing the preload of the bearing. Summary of the invention

[0006] The robot arm of the present invention comprises: a first arm; a second arm connected to the first arm in a manner of rotating around a first rotation axis and having a loading surface; a bearing box loaded on the loading surface; a fixing component fixing the bearing box to the second arm; a bearing received in the bearing box in a pre-stressed state; a first gear passing through the bearing box and inserted into the second arm, and being axially supported on the bearing box via the bearing in a manner of rotating around the first rotation axis; a second gear being axially supported on the second arm and meshing with the first gear in the second arm; and an adjustment component interposed between the loading surface and the bearing box, for adjusting the tooth contact between the first gear and the second gear by adjusting the separation distance between the loading surface and the bearing box in the direction along the first rotation axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a diagram showing the overall configuration of a robot system according to a preferred embodiment.

[0008] Figure 2 It is a cross-sectional view showing the inside of the arm.

[0009] Figure 3 It is a cross-sectional view showing the inside of the arm.

[0010] Figure 4 It is a cross-sectional view showing a state where the input bevel gear unit is removed from the arm.

[0011] Description of Reference Numerals

[0012] 1…Robot system; 10…Robot controller; 2…Robot; 21…Base; 22…Robot arm; 221…Arm; 222…Arm; 223…Arm; 224…Arm; 224a…Front end; 224b…Front end; 225…Arm; 226…Arm; 231…Drive mechanism; 232…Drive mechanism; 233…Drive mechanism; 234…Drive mechanism; 235…Drive mechanism; 236…Drive mechanism; 24…End effector 251…first insertion hole; 251a…base end; 251b…central part; 251c…front end; 251d…loading surface; 251e…guide; 252…second insertion hole; 31…housing; 311…through hole; 32…cover; 41…motor; 42…speed reducer; 421…wave generator; 422…rigid gear; 423…flexible gear; 43…pulley; 44…pulley; 45…power transmission belt; 5…input cone gear unit; 51…bearing box; 511…base; 511a…base end; 511b…center; 511c…front end; 511d…mounting surface; 511e…flange; 512…cover; 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; 5 3…input bevel gear; 531…shaft; 532…gear unit; 54…preload component; 55…preload transmission component; 59…preload mechanism; 61…motor; 63…pulley; 64…pulley; 65…power transmission belt; 66…output bevel gear; 661…shaft; 662…gear unit; 7…adjustment component; J1…rotation shaft; J2…rotation shaft; J3…rotation shaft; J4…rotation shaft; J5…rotation shaft; J6…rotation shaft; N…screw. DETAILED DESCRIPTION

[0013] Hereinafter, preferred embodiments of the robot arm will be described based on the drawings.

[0014] Figure 1 It is a diagram showing the overall configuration of a robot system according to a preferred embodiment. Figure 2 It is a cross-sectional view showing the inside of the arm. Figure 3 It is a cross-sectional view showing the inside of the arm. Figure 4 It is a cross-sectional view showing a state where the input bevel gear unit is removed from the arm.

[0015] Figure 1 The robot system 1 shown has a robot 2 and a robot controller 10 which controls a drive of the robot 2 .

[0016] The robot 2 is a vertical multi-joint robot having six drive axes and includes a base 21 fixed to the ground and a robot arm 22 connected to the base 21 .

[0017] In addition, the robot arm 22 includes an arm 221 connected to the base 21 and rotating about a rotation axis J1 relative to the base 21; an arm 222 connected to the arm 221 and rotating about a rotation axis J2 relative to the arm 221; an arm 223 connected to the arm 222 and rotating about a rotation axis J3 relative to the arm 222; an arm 224 as a first arm connected to the arm 223 and rotating about a rotation axis J4 relative to the arm 223; an arm 225 as a second arm connected to the arm 224 and rotating about a rotation axis J5 as a first rotation axis relative to the arm 224; and an arm 226 connected to the arm 225 and rotating about a rotation axis J6 relative to the arm 225. In addition, the end effector 24 is connected to the front end of the arm 226.

[0018] In addition, the robot 2 has: a driving mechanism 231, which causes the arm 221 to rotate around the rotation axis J1 relative to the base 21; a driving mechanism 232, which causes the arm 222 to rotate around the rotation axis J2 relative to the arm 221; a driving mechanism 233, which causes the arm 223 to rotate around the rotation axis J3 relative to the arm 222; a driving mechanism 234, which causes the arm 224 to rotate around the rotation axis J4 relative to the arm 223; a driving mechanism 235, which causes the arm 225 to rotate around the rotation axis J5 relative to the arm 224; and a driving mechanism 236, which causes the arm 226 to rotate around the rotation axis J6 relative to the arm 225.

[0019] The robot controller 10 independently controls the drive mechanisms 231 to 236 to make the robot 2 perform a predetermined operation. The robot controller 10 is composed of, for example, a computer, and has a processor for processing information, a memory connected to the processor in a communicable manner, and an external interface. In addition, the memory stores various programs that can be executed by the processor, and the processor can read and execute various programs stored in the memory.

[0020] The above briefly describes the robot system 1. However, the structure of the robot system 1 is not particularly limited. For example, the robot 2 may be a horizontal multi-joint robot (SCARA robot), a dual-arm robot with two arms, or the like, in addition to a six-axis robot. In addition, the robot 2 may not be fixed to the ground, for example, it may be fixed to an unmanned transport vehicle such as an AMR (Autonomous Mobile Robot) or an AGV (Automatic Guided Vehicle).

[0021] Next, based on Figures 2 to 4 , the drive mechanism 235 for rotating the arm 225 relative to the arm 224 about the rotation axis J5, and the drive mechanism 236 for rotating the arm 226 relative to the arm 225 about the rotation axis J6 are described in detail. Figures 2 to 4 The upper side is referred to as “upper” and the lower side is referred to as “lower”.

[0022] like Figure 2 As shown, the front end of the arm 224 is divided into two forks, and the arm 225 is supported at both ends from both sides of the rotation axis J5. In addition, the driving mechanism 236 is arranged at the upper front end 224a, and the driving mechanism 235 is arranged at the lower front end 224b. In this way, by supporting the arm 225 at both ends, the rotation accuracy of the arm 225 is improved, and the arrangement space of the driving mechanism 235 and the driving mechanism 236 can be ensured respectively.

[0023] In addition, the arm 224 has a housing 31 and a cover 32 mounted on the housing 31. The base end of the housing 31 is rotatably connected to the arm 223, and the front end of the housing 31 is rotatably connected to the arm 225. In addition, at the front end 224a on the upper side, a through hole 311 is formed in the housing 31 that is concentric with the rotation axis J5. When viewed from above in the direction along the rotation axis J5, the through hole 311 is formed at a position overlapping with the input bevel gear unit 5 to be described later mounted on the arm 225, and is larger than the input bevel gear unit 5. Therefore, the input bevel gear unit 5 can be removed from the arm 225 via the through hole 311.

[0024] In addition, a cylindrical first insertion hole 251 along the rotation axis J5 and a cylindrical second insertion hole 252 along the rotation axis J6 are formed in the arm 225. In addition, the first insertion hole 251 is open to the front end 224a side, and the central axis is consistent with the rotation axis J5. In addition, the second insertion hole 252 is open to the arm 226 side, and the central axis is consistent with the rotation axis J6. In addition, the front ends of the first insertion hole 251 and the second insertion hole 252 are connected to each other orthogonally in the arm 225. In addition, 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 insertion hole 251 and the second insertion hole 252 are not limited to cylindrical shapes, for example, they can also be polygonal shapes such as quadrilaterals and hexagons, elliptical shapes, special shapes, etc. when viewed from above.

[0025] In addition, the inner diameter of the first insertion hole 251 is reduced in three stages toward the lower side, 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 front end 251c located below the central portion 251b and having a smaller diameter than the central portion 251b. In addition, at the boundary between the base end 251a and the central portion 251b, a loading surface 251d is formed that is formed by a stepped surface orthogonal to the rotation axis J5 and faces the upper side. In addition, at the boundary between the central portion 251b and the front end 251c, a conical guide portion 251e whose inner diameter gradually decreases toward the lower side is formed. It should be noted that in the case where the top view shape of the first insertion hole 251 and the second insertion hole 252 is other than a circle, the "diameter" can be replaced by "width".

[0026] The drive mechanism 235 includes an encoder built-in motor 41 fixed to the housing 31, a speed reducer 42 for reducing the rotation of the motor 41, a pulley 43 mounted on the output shaft of the motor 41, a pulley 44 mounted on the speed reducer 42, and a power transmission belt 45 wound around the pulleys 43 and 44. The speed reducer 42 is a wave gear device, a rigid gear 422 is fixed to the housing 31, and a flexible gear 423 is fixed to the arm 225. The pulley 44 is fixed to the wave generator 421.

[0027] According to such a structure, the rotation of the motor 41 is transmitted to the wave generator 421 of the speed reducer 42 via the pulley 43, the power transmission belt 45 and the pulley 44, so that the wave generator 421 rotates. In addition, relative to the rotation of the wave generator 421, the flexible gear 423 rotates at a predetermined reduction ratio, and as a result, the arm 225 rotates relative to the arm 224 around the rotation axis J5.

[0028] The driving mechanism 235 has been described above, but the structure of the driving mechanism 235 is not particularly limited.

[0029] The driving mechanism 236 includes an input bevel gear unit 5 inserted into the first insertion hole 251 and placed on the placement surface 251d. Figure 3 As shown, the input bevel gear unit 5 includes: a bearing box 51 mounted on the mounting surface 251d; a bearing 52 housed in the bearing box 51 in a pre-stressed state; and an input bevel gear 53 as a first gear, which passes through the bearing box 51 and is axially supported by the bearing box 51 via the bearing 52.

[0030] The bearing box 51 is cylindrical and matches the shape of the first insertion hole 251. In addition, the bearing box 51 has a base 511 and a cover 512 located on the upper side of the base 511 and fixed to the base 511. In addition, a storage space for storing the bearing 52 and the input bevel gear 53 is formed inside the bearing box 51. However, the shape of the bearing box 51 is not limited to a cylindrical shape, and can be determined according to the shape of the first insertion hole 251.

[0031] In addition, the outer diameter of the base 511 is reduced in three stages toward the lower side, and has a base end 511a, a central part 511b located at the lower side of the base end 511a and having a smaller diameter than the base end 511a, and a front end 511c located at the lower side of the central part 511b and having a smaller diameter than the central part 511b. In addition, at the boundary between the base end 511a and the central part 511b, a loading surface 511d is formed toward the lower side, which is composed of a stepped surface orthogonal to the rotation axis J5. In addition, a flange 511e protruding into the storage space is formed at the front end 511c. On the other hand, the cover 512 is located on the upper side of the base 511 and is fastened and fixed to the base end 511a by screws not shown. These bases 511 and cover 512 are made of metal materials such as aluminum and stainless steel, for example.

[0032] The bearing box 51 as described above is inserted into the first insertion hole 251 from the base 511 side, and the loaded surface 511d is loaded on the loading surface 251d. As a result, the installation of the bearing box 51 to the arm 225 becomes easy. In addition, at this time, since the front end 511c of the bearing box 51 is guided to the front end 251c by the guide portion 251e of the first insertion hole 251 earlier than the loaded surface 511d is loaded on the loading surface 251d, the insertion of the bearing box 51 into the first insertion hole 251 becomes easy. The bearing box 51 is fastened and fixed to the arm 225 by a plurality of screws N as a fixing member in a state where the bearing box 51 is loaded on the loading surface 251d. In a state where the bearing box 51 is fixed to the arm 225, the input bevel gear 53 rotates around the rotation axis J5. It should be noted that there is no particular limitation as a fixing member for fixing the bearing box 51 to the arm 225.

[0033] The bearing 52 is arranged in the storage space of the bearing box 51. In addition, the bearing 52 has a first bearing 521 and a second bearing 522. In addition, these first bearing 521 and second bearing 522 are separately arranged along the rotation axis J5. By separately arranging the first bearing 521 and the second bearing 522, since the input bevel gear 53 is supported by two separate points, the rotation of the input bevel gear 53 is stable.

[0034] In addition, the first bearing 521 is an angular contact ball bearing, and has a first outer ring 521a supported on the inner circumference of the base 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 contact ball bearing, and has a second outer ring 522a supported on the inner circumference of the base 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.

[0035] The input bevel gear 53 includes: a shaft 531 that passes through the bearing box 51 and is axially supported by the bearing box 51 via a first bearing 521 and a second bearing 522; and a gear portion 532 that is disposed at the front end of the shaft 531 and is located at the lower side of the bearing box 51. In addition, the gear portion 532 is located at the front end of the first insertion hole 251 and faces the second insertion hole 252.

[0036] The input bevel gear unit 5 also has a preload mechanism 59 for preloading the first bearing 521 and the second bearing 522. The preload mechanism 59 has a preload component 54 disposed between the first bearing 521 and the cover 512, and a preload transmission component 55 disposed between the first bearing 521 and the second bearing 522. The preload component 54 is an annular (ring-shaped) spacer that is sandwiched between the cover 512 and the first outer ring 521a of the first bearing 521. On the other hand, the preload transmission component 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. In addition, the second outer ring 522a of the second bearing 522 abuts against the flange 511e to restrict further displacement.

[0037] The preload component 54 is pressed against the first outer ring 521a by the cover body 512, and the first outer ring 521a is pressed downward. In addition, the force received by the first outer ring 521a from the preload component 54 is transmitted from the first inner ring 521b to the second inner ring 522b via the preload transmission component 55, and the second inner ring 522b is pressed downward. As a result, the first bearing 521 and the second bearing 522 are equally preloaded. The thicker the preload component 54 is, the greater the force pressing the first outer ring 521a is, and the preload of the first bearing 521 and the second bearing 522 is increased accordingly. Therefore, by adjusting the thickness of the preload component 54, the first bearing 521 and the second bearing 522 can be preloaded with a desired force. As a result, the rotation accuracy and rigidity of the first bearing 521 and the second bearing 522 are improved.

[0038] It should be noted that the method for adjusting the thickness of the pre-pressing member 54 is not particularly limited, but for example, the thickness of the pre-pressing member 54 can be adjusted by preparing a plurality of pre-pressing members 54 of different thicknesses and selecting one of them for use. In addition, the thickness of the pre-pressing member 54 can be adjusted by preparing a plurality of pre-pressing members 54 of the same thickness and selecting the number of sheets to be used. According to these methods, the thickness of the pre-pressing member 54 can be easily adjusted. It should be noted that the pre-pressing member 54 is not limited to a spacer, and may be, for example, a corrugated washer. In this case, the corrugated washer is elastically deformed in a compressed manner by tightening the screw, thereby adjusting the thickness of the pre-pressing member 54.

[0039] The input bevel gear unit 5 has been described above. Thus, in the present embodiment, the bearing box 51, the bearing 52, the input bevel gear 53, and the preload mechanism 59 are unitized as the input bevel gear unit 5. Therefore, they can be installed on the arm 225 or removed from the arm 225 at once, and the assembly and adjustment of the robot 2 become easy. In addition, the preload of the first bearing 521 and the second bearing 522 can be adjusted before being installed on the arm 225, making the operation easy.

[0040] It should be noted that the structure of the input bevel gear unit 5 is not particularly limited. For example, the bearing box 51 is composed of a base 511 and a cover 512, but it is not limited to this, and it can also be a structure formed by connecting more than three parts. In addition, the base 511 and the cover 512 are fixed by threads, but the method for fixing them is not particularly limited. In addition, the number of bearings is not limited to two, and it can be one or more than three. In addition, the first bearing 521 and the second bearing 522 may not be angular contact ball bearings, for example, they may be angular contact roller bearings. In addition, in the figure, the first bearing 521 is larger than the second bearing 522, but it is not limited to this, and the first bearing 521 can be smaller than the second bearing 522, or they can be the same.

[0041] like Figure 2 As shown, the drive mechanism 236 also includes an encoder built-in motor 61, a pulley 63 mounted on the output shaft of the motor 61, a pulley 64 mounted on the input bevel gear 53, and a power transmission belt 65 hung around the pulley 63 and the pulley 64. In addition, the drive mechanism 236 also includes an output bevel gear 66 as 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 axially supported by the arm 225 via a bearing; and a gear portion 662, which is arranged at the front end of the shaft 661 and meshes with the gear portion 532 in the arm 225. The rotation axis of such an output bevel gear 66 is consistent with the rotation axis J6.

[0042] In the driving mechanism 236 of such a structure, 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, so that the input bevel gear 53 rotates. In addition, the rotation of the input bevel gear 53 is transmitted to the output bevel gear 66, so that the arm 226 connected to the output bevel gear 66 rotates around the rotation axis J6.

[0043] like Figure 3 As shown, the drive mechanism 236 also has an adjustment component 7 for adjusting the tooth contact and tooth gap between the input bevel gear 53 and the output bevel gear 66. The adjustment component 7 is an annular (ring-shaped) isolation gasket, which is sandwiched between the loading surface 251d and the loaded surface 511d. The adjustment component 7 is a component for adjusting the separation distance between the loading surface 251d and the loaded surface 511d along the rotation axis J5. The thicker the thickness of the adjustment component 7, the more the input bevel gear unit 5 is displaced upward relative to the arm 225, and the meshing of the input bevel gear 53 and the output bevel gear 66 becomes shallower accordingly. Therefore, by adjusting the thickness of the adjustment component 7, the position of the input bevel gear 53 can be determined, and the tooth contact and tooth gap between the input bevel gear 53 and the output bevel gear 66 can be adjusted. As a result, it is possible to achieve improved transmission accuracy of rotational motion, reduced noise, and extended life.

[0044] It should be noted that the method for adjusting the thickness of the adjustment member 7 is not particularly limited, but for example, the thickness of the adjustment member 7 can be adjusted by preparing a plurality of adjustment members 7 of different thicknesses and selecting one of them for use. In addition, the thickness of the adjustment member 7 can be adjusted by preparing a plurality of adjustment members 7 of the same thickness and selecting the number of pieces to be used. According to these methods, the thickness of the adjustment member 7 can be easily adjusted. It should be noted that the adjustment member 7 is not limited to an isolation gasket, and can also be a corrugated washer, for example. In this case, the thickness of the adjustment member 7 can be adjusted by elastically deforming the corrugated washer in a compressed manner by tightening the screw N.

[0045] In particular, in this embodiment, the bearing box 51, the bearing 52, the input bevel gear 53 and the preload mechanism 59 are integrated as the input bevel gear unit 5. Therefore, when adjusting the tooth contact and tooth clearance between the input bevel gear 53 and the output bevel gear 66, Figure 4 As shown in the figure, the adjustment member 7 can be replaced only by removing the input bevel gear unit 5 from the arm 225. In addition, even if the input bevel gear unit 5 is removed from the arm 225, the preload of the first bearing 521 and the second bearing 522 is kept constant and is not affected. Therefore, the tooth contact and tooth clearance between the input bevel gear 53 and the output bevel gear 66 can be adjusted without causing a change in the preload.

[0046] In addition, as described above, the input bevel gear unit 5 can be removed from the arm 225 via 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.

[0047] In addition, the first bearing 521 and the second bearing 522 are both arranged in the bearing box 51. Therefore, the first bearing 521 and the second bearing 522 are protected by the bearing box 51. Therefore, when adjusting the tooth contact and tooth clearance between the input bevel gear 53 and the output bevel gear 66, even if the input bevel gear unit 5 is repeatedly mounted and dismounted relative to the arm 225 in order to replace the adjustment component 7, the first bearing 521 and the second bearing 522 will not directly collide with the arm 224, the arm 225, etc., and the damage and destruction of the first bearing 521 and the second bearing 522 can be effectively suppressed.

[0048] According to the driving mechanism 236 as described above, by changing the thickness of the preload component 54, it is possible to adjust only the preload of the first bearing 521 and the second bearing 522 without causing a change in the tooth contact and tooth gap between the input bevel gear 53 and the output bevel gear 66. In addition, by adjusting the thickness of the adjustment component 7, it is possible to adjust only the tooth contact and tooth gap between the input bevel gear 53 and the output bevel gear 66 without causing a change in the preload of the first bearing 521 and the second bearing 522. That is, the adjustment of the preload of the first bearing 521 and the second bearing 522 and the adjustment of the tooth contact and tooth gap between the input bevel gear 53 and the output bevel gear 66 can be performed independently.

[0049] The robot system 1 has been described above. As described above, the robot arm 22 of the robot system 1 includes: an arm 224 as a first arm; an arm 225 as a second arm, connected to the arm 224 in a manner of rotating around a rotation axis J5 as a first rotation axis, and having a mounting surface 251d; a bearing box 51, mounted on the mounting surface 251d; a screw N as a fixing member, fixing the bearing box 51 to the arm 225; a bearing 52, housed in the bearing box 51 in a pre-stressed state; an input bevel gear 53 as a first gear, penetrating the shaft The first bearing 521 and the second bearing 522 are connected to the bearing box 51 and inserted into the arm 225, and are supported by the bearing box 51 via the bearing 52 in a manner that rotates around the rotation axis J5; the output bevel gear 66, which is the second gear, is supported by the arm 225 and meshes with the input bevel gear 53 in the arm 225; and the adjustment component 7 is interposed between the mounting surface 251d and the bearing box 51, and the tooth contact between the input bevel gear 53 and the output bevel gear 66 is adjusted by adjusting the separation distance between the mounting surface 251d and the bearing box 51 in the direction along the rotation axis J5. According to such a structure, by adjusting the thickness of the adjustment component 7, the tooth contact between the input bevel gear 53 and the output bevel gear 66 can be adjusted without causing changes in the preload of the first bearing 521 and the second bearing 522. Therefore, this operation becomes easy.

[0050] In addition, as described above, the bearing box 51, the bearing 52, and the input bevel gear 53 are unitized as the input bevel gear unit 5. As a result, the bearing box 51, the bearing 52, and the input bevel gear 53 can be easily mounted on the arm 225 and removed from the arm 225. In addition, the preload of the bearing 52 can be adjusted before mounting on the arm 225, which makes the operation easier.

[0051] In addition, as described above, when viewed from above in the direction along the rotation axis J5, the arm 225 has a through hole 311 that is larger than the bearing box 51 at a position overlapping with the bearing box 51. According to such a structure, the input bevel gear unit 5 can be removed from the arm 225 via the through hole 311. Therefore, the tooth contact and tooth clearance between the input bevel gear 53 and the output bevel gear 66 can be adjusted by replacing the adjustment component 7 in a state where the arm 224 and the arm 225 are connected. Therefore, the adjustment operation can be easily performed.

[0052] In addition, as described above, the bearing box 51 has a base 511 that supports the bearing 52 and a cover 512 that is fixed to the base 511. In addition, the robot arm 22 has a pre-stressing member 54, which is located between the bearing 52 and the cover 512 and pre-stresses the bearing 52 in the direction along the rotation axis J5. Thus, the bearing 52 can be pre-stressed with a simple structure. In addition, by changing the thickness of the pre-stressing member 54, the size of the pre-stress can be easily adjusted.

[0053] As described above, the bearing 52 includes the first bearing 521 and the second bearing 522 which are arranged separately in the direction along the rotation axis J5. Thus, since the input bevel gear 53 is supported by two separate points, the rotation of the input bevel gear 53 is stable.

[0054] In addition, as described above, the first bearing 521 is in contact with the preload member 54. In addition, the robot arm 22 has a preload transmission member 55, which is disposed between the first bearing 521 and the second bearing 522 and transmits the force received by the first bearing 521 from the preload member 54 to the second bearing 522. Thus, the first bearing 521 and the second bearing 522 can be preloaded equally by the preload member 54 and the preload transmission member 55.

[0055] As described above, the first bearing 521 includes the first outer ring 521a supported by the bearing box 51, the first inner ring 521b through which the input bevel gear 53 is inserted, and the balls 521c as the first rotating body arranged between the first outer ring 521a and the first inner ring 521b. Similarly, the second bearing 522 includes the second outer ring 522a supported by the bearing box 51, the second inner ring 522b through which the input bevel gear 53 is inserted, and the balls 522c as the second rotating body arranged between the second outer ring 522a and the second inner ring 522b. Furthermore, the first outer ring 521a and the second outer ring 522a are supported by the bearing box 51, the first outer ring 521a is in contact with the preload member 54, and the preload transmission member 55 is arranged between the first inner ring 521b and the second inner ring 522b. According to such a structure, the force received by the first outer ring 521 a from the preload member 54 is transmitted to the second bearing 522 via the preload transmission member 55 , so that the first bearing 521 and the second bearing 522 are equally preloaded.

[0056] The robot arm of the present invention has been described above based on the illustrated embodiment, but the present invention is not limited thereto, and the structure of each part can be replaced with any structure having the same function. In addition, any other structure can be added to the present invention.

[0057] In addition, in the aforementioned embodiment, the first gear is the input bevel gear 53 and the second gear is the output bevel gear 66, but the present invention is not limited thereto, and the first gear may be the output bevel gear 66 and the second gear may be the input bevel gear 53. That is, the output bevel gear 66 may be unitized as an output bevel gear unit together with the bearing box, the bearing and the preload mechanism.

Claims

1. A robotic arm, characterized in that: have: First arm; A second arm is connected to the first arm in a manner of rotating around a first rotation axis and has a loading surface; A bearing box, mounted on the mounting surface; a fixing member, fixing the bearing box to the second arm; A bearing is housed in the bearing box in a pre-stressed state; a first gear penetrating the bearing box and inserted into the second arm, and being axially supported by the bearing box via the bearing so as to rotate around the first rotation axis; a second gear supported by a shaft on the second arm and meshing with the first gear in the second arm; as well as An adjustment component is interposed between the mounting surface and the bearing box, 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 box in the direction along the first rotation axis.

2. The robotic arm according to claim 1, characterized in that: The bearing housing, the bearing, and the first gear are unitized.

3. The robotic arm according to claim 2, characterized in that: The first arm has a through hole larger than the bearing box at a position overlapping the bearing box when viewed in plan from a direction along the first rotation axis.

4. The robotic arm according to claim 1, characterized in that: The bearing box includes a base body supporting the bearing and a cover body fixed to the base body. The robot arm has a pre-pressing component, which is located between the bearing and the cover body and pre-presses the bearing in a direction along the first rotation axis.

5. The robotic arm according to claim 4, characterized in that: The bearing includes a first bearing and a second bearing that are disposed separately in a direction along the first rotation axis.

6. The robotic arm according to claim 5, characterized in that: The first bearing is in contact with the preload component. The robot arm includes a preload transmission component, which is disposed between the first bearing and the second bearing and transmits the preload received by the first bearing to the second bearing.

7. The robot arm according to claim 6, characterized in that: The first bearing includes a first outer ring supported by the bearing box, a first inner ring through which the first gear is inserted, and a first rotating body arranged between the first outer ring and the first inner ring. The second bearing includes a second outer ring supported by the bearing box, a second inner ring through which the first gear is inserted, and a second rotating body arranged between the second outer ring and the second inner ring. The first outer ring and the second outer ring are supported by the bearing box, The first outer ring abuts against the pre-compression component, The preload transmission member is arranged between the first inner ring and the second inner ring.

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