Joint structure and robot

Abstract

A joint structure (10) comprises: a first component (11), (62a) having a cylindrical first inner surface (11i), (62i) along a predetermined axis (J6); a second component (12), having a cylindrical outer surface (12o1), (12o2) arranged coaxially with the first inner surface; and a first seal (21), (22) which seals an annular space between the first inner surface (11i), (62i) and the outer surface (12o1) while allowing the first component and the second component to rotate relative to each other around the axis (J6). a gap; a third component (31), (32) having a second inner surface (31i), (32i) coaxially arranged with the first inner surface and removably mounted on the first component outside the sealing position sealed by the first seal; and a second seal (41), (42) pressed into the second inner surface (31i), (32i) and sealing the annular gap between the second inner surface (31i), (32i) and the outer surface (12o2) while allowing the first component and the second component to rotate relative to each other around the axis (J6).

Description

Technical Field

[0001] The present invention relates to a joint structure and a robot. Background Art

[0002] A robot having a joint portion is disclosed, wherein the joint portion includes: a first wall member that accommodates a power transmission mechanism and a lubricant inside; and a second wall member that is supported by the first wall member in a manner that allows rotation around a predetermined rotation axis (for example, see Patent Document 1).

[0003] A contact seal element is disposed between the first and second wall members to seal the gap therebetween. Furthermore, a second seal portion is disposed between the first and second wall members outside the contact seal element to seal the gap therebetween. The second seal portion is pressed into the outer peripheral surface of the first wall member by a press.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-107116 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] When replacing the second seal, it is necessary to remove the second seal from the first wall member and press the new second seal onto the outer surface of the first wall member using a press. However, a press may not always be available at the site where the robot is introduced, and in such cases, replacing the second seal becomes difficult.

[0009] Therefore, it is desired to be able to easily replace the sealing member even at a site where no press machine is installed.

[0010] Solutions for solving problems

[0011] One embodiment of the present invention is a joint structure, comprising: a first component having a cylindrical first inner surface along a predetermined axis; a second component having a cylindrical outer surface coaxially arranged with the first inner surface; a first seal that seals the annular gap between the first inner surface and the outer surface while allowing the first component and the second component to rotate relative to each other around the axis; a third component having a second inner surface coaxially arranged with the first inner surface and being removably mounted on the first component outside the sealing position sealed by the first seal; and a second seal that is pressed into the second inner surface and seals the annular gap between the second inner surface and the outer surface while allowing the first component and the second component to rotate relative to each other around the axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a diagram showing the overall structure of a robot according to one embodiment of the present invention.

[0013] Figure 2 Yes Figure 1 A longitudinal sectional view of an example of a joint structure of an embodiment of the present invention included in a robot.

[0014] Figure 3 It is an explanation Figure 2 An enlarged longitudinal sectional view of a portion of the oil seal of the joint structure.

[0015] Figure 4 Observed from the sixth axis Figure 2 Front view of the first assembly and disassembly component of the joint structure.

[0016] Figure 5 yes Figure 2 Exploded longitudinal cross-sectional view of the joint structure.

[0017] Figure 6 Yes Figure 2 A longitudinal sectional view of a modified example of a joint structure.

[0018] Figure 7 yes Figure 6 Exploded longitudinal cross-sectional view of the joint structure.

[0019] Figure 8 Yes Figure 2 A longitudinal sectional view of another modified example of the joint structure. DETAILED DESCRIPTION

[0020] Hereinafter, a joint structure 10 and a robot 1 according to an embodiment of the present invention will be described with reference to the drawings.

[0021] like Figure 1 As shown, the robot 1 equipped with the joint structure 10 of this embodiment is, for example, a vertical six-axis articulated robot.

[0022] The robot 1 includes a base 2 installed on a horizontal floor F, and a revolving body 3 supported on the base 2 so as to be rotatable about a vertical first axis J1. The robot 1 also includes a first arm 4 supported on the revolving body 3 so as to be rotatable about a horizontal second axis J2, and a second arm 5 rotatable relative to the first arm 4 about a horizontal third axis J3.

[0023] Furthermore, the robot 1 includes a three-axis wrist unit 6 at the distal end of the second arm 5. The wrist unit 6 includes a first wrist element 61, which is supported on the second arm 5 so as to be rotatable about a fourth axis J4 extending along a plane perpendicular to the third axis J3. Furthermore, the wrist unit 6 includes a second wrist element 62, which is supported on the first wrist element 61 so as to be rotatable about a fifth axis J5 perpendicular to the fourth axis J4. Furthermore, the wrist unit 6 includes a third wrist element 63, which is supported on the second wrist element 62 so as to be rotatable about a sixth axis (axis) J6, which is perpendicular to the fifth axis J5 and passes through the intersection of the fourth axis J4 and the fifth axis J5.

[0024] The joint structure 10 of this embodiment is, for example, a structure in which the third wrist element 63 is driven to rotate relative to the second wrist element 62. Figure 2 As shown, the joint structure 10 includes: a housing (first component) 62a of the second wrist element 62 and an annular fixed component (first component) 11 fixed to the housing 62a; and a movable component (second component) 12, which is arranged inside the housing 62a and the fixed component 11.

[0025] The fixed member 11 forms an outer ring, the movable member 12 forms an inner ring, and rollers 13 are arranged between the fixed member 11 and the movable member 12 to form a bearing. The movable member 12 is supported by the fixed member 11 so as to be rotatable about the sixth axis J6.

[0026] The joint structure 10 also includes an oil seal (first seal) 21 disposed between the fixed member 11 and the movable member 12 , and an oil seal (first seal) 22 disposed between the housing 62 a and the movable member 12 .

[0027] The joint structure 10 also includes a first detachable member (third member) 31 removably secured to the end of the fixed member 11, and a second detachable member (third member) 32 removably secured to the end of the housing 62a. Furthermore, the joint structure 10 includes an oil seal (second seal) 41 disposed between the first detachable member 31 and the movable member 12, and an oil seal (second seal) 42 disposed between the second detachable member 32 and the movable member 12.

[0028] The fixing member 11 and the housing 62a respectively have cylindrical inner peripheral surfaces (first inner surfaces) 11i and 62i centered on the sixth axis J6. The fixing member 11 and the housing 62a are fixed with an O-ring 70 interposed therebetween, thereby being sealed.

[0029] The movable member 12 is cylindrical and has a through-hole 12h centered on the sixth axis J6. The movable member 12 has two outer peripheral surfaces (external surfaces) 12o1. These two outer peripheral surfaces (external surfaces) 12o1 are positioned radially inward of the inner peripheral surfaces 11i and 62i of the fixed member 11 and the housing 62a, respectively, with a gap therebetween. Furthermore, the movable member 12 has two outer peripheral surfaces (external surfaces) 12o2 coaxial with the outer peripheral surfaces 12o1. The outer peripheral surfaces 12o2 are positioned on either side of the outer peripheral surfaces 12o1 along the sixth axis J6.

[0030] The movable member 12 is provided with a flange surface 12 f on one end side in the sixth axis J6 direction for attaching a tool (not shown) such as a hand.

[0031] The movable member 12 is provided with a driven gear 12a that meshes with a driving gear (not shown). Rotation of the driving gear transmits rotational force to the movable member 12 via the driven gear 12a, causing the movable member 12 to rotate relative to the fixed member 11 and the housing 62a about the sixth axis J6.

[0032] like Figure 2 as well as Figure 3 As shown, the oil seal 21 has an annular lip portion 21a on the radially inner side and is press-fitted into the inner circumferential surface 11i of the stepped portion of the fixed member 11. Similarly, the oil seal 22 has an annular lip portion 22a on the radially inner side and is press-fitted into the inner circumferential surface 62i of the stepped portion of the housing 62a. The lips 21a and 22a each contact the outer circumferential surface 12o1 of the movable member 12 over their entire circumference.

[0033] As the movable member 12 rotates about the sixth axis J6 relative to the fixed member 11 and the housing 62a, the outer peripheral surface 12o1 moves circumferentially while maintaining contact with the lips 21a and 22a of the oil seals 21 and 22, respectively. Thus, even as the movable member 12 rotates, the oil seals 21 and 22 can seal the gap between the fixed member 11 and the housing 62a, and the movable member 12.

[0034] like Figure 2 As shown, the first detachable member 31 has a cylindrical inner circumferential surface (second inner surface) 31i, which is coaxially arranged with the inner circumferential surface 11i of the fixed member 11 and is arranged radially outward with a gap relative to the outer circumferential surface 12o2 of the movable member 12. Figure 4 As shown, the first detachable member 31 includes a plurality of through holes 31 a and two pin holes 31 b that are parallel to the sixth axis J6 serving as the central axis.

[0035] The first detachable member 31 is detachably fixed to one end of the fixing member 11 by fastening bolts (not shown) inserted through the through holes 31a to threaded holes (not shown) provided in the fixing member 11. Furthermore, pins (not shown) inserted into the two pin holes 31b are inserted into pin holes (not shown) provided in the fixing member 11 to position the first detachable member 31 in the radial direction relative to the fixing member 11.

[0036] The second detachable member 32 has a cylindrical inner circumferential surface (second inner surface) 32i. This inner circumferential surface (second inner surface) 32i is coaxially arranged with the inner circumferential surface 62i of the housing 62a and radially outwardly spaced apart from the outer circumferential surface 12o2 of the movable member 12. Similar to the first detachable member 31, the second detachable member 32 has a plurality of through-holes (not shown). Bolts (not shown) passing through these through-holes are fastened to threaded holes (not shown) provided in the housing 62a, thereby detachably securing the second detachable member 32 to one end of the housing 62a. The second detachable member 32 is radially positioned relative to the housing 62a by fitting the second detachable member 32 to the fitting surface 62b of the housing 62a.

[0037] A seal member such as a gasket (not shown) is used to seal the first detachable member 31 from the fixed member 11. An O-ring 71 is interposed between the second detachable member 32 and the housing 62a.

[0038] like Figure 2As shown, the oil seals 41 and 42 have annular lips 41a and 42a on the radially inward sides, respectively, and are press-fitted into the inner circumferential surfaces 31i and 32i of the first and second detachable members 31 and 32, respectively. By securing the first and second detachable members 31 and 32 to the fixed member 11 or the end of the housing 62a, the lips 41a and 42a contact the outer circumferential surface 12o2 over the entire circumference, outward of the sealing position established by the oil seals 21 and 22.

[0039] As the movable member 12 rotates about the sixth axis J6 relative to the fixed member 11 and the housing 62a, the outer peripheral surface 12o2 moves circumferentially while maintaining contact with the lips 41a and 42a of the oil seals 41 and 42, respectively. Thus, even as the movable member 12 rotates, the oil seals 41 and 42 can seal the gap between the inner peripheral surfaces 31i and 32i of the first and second detachable members 31 and 32 and the outer peripheral surface 12o2 of the movable member 12.

[0040] Furthermore, in this embodiment, the maximum diameter of movable member 12 outside the sealing position sealed by oil seals 41 and 42 is set to be less than or equal to the outer diameter of outer peripheral surface 12o2 of movable member 12 at the sealing position sealed by oil seals 41 and 42. This allows oil seal 41 to be removed from flange surface 12f or inserted from flange surface 12f into outer peripheral surface 12o2 without interfering with other components. Similarly to oil seal 41, oil seal 42 can also be installed and removed without interfering with other components with lip 42a.

[0041] Hereinafter, the operation of the joint structure 10 of this embodiment configured as described above will be described.

[0042] According to the joint structure 10 of this embodiment, the space sandwiched between the oil seals 21 and 22, disposed in the gap between the fixed member 11 and the housing 62a, and the movable member 12, is maintained in a sealed state. This allows the movable member 12 to rotate about the sixth axis J6 relative to the fixed member 11 and the housing 62a while preventing grease or other lubricant filling the space from leaking out, thereby lubricating the roller 13, the drive gear, the driven gear 12a, and the like.

[0043] Furthermore, the oil seal 41 that seals the gap between the first detachable member 31 and the movable member 12 outside the sealing position of the oil seal 21 can reduce the chance of external dust and the like reaching the oil seal 21 and protect the oil seal 21 .

[0044] If the oil seal 41 exposed to the outside is damaged by external dust or the like, the sealing performance can be restored by replacing it.

[0045] When replacing the oil seal 41, remove the bolts that fix the fixing component 11 and the first assembly and disassembly component 31. Figure 5 As shown, the first detachable component 31 and the oil seal 41 are removed from the fixed component 11 along the sixth axis J6 toward the flange surface 12f. The removed first detachable component 31 and oil seal 41 are then replaced with new ones, and the components are returned to their original mounting positions from the flange surface 12f, completing the replacement of the oil seal 41.

[0046] In this case, since the maximum diameter of the movable member 12 outside the sealing position of the oil seal 41 is smaller than the outer diameter of the outer peripheral surface 12o2, the oil seal 41 can be easily attached to and detached from the outer peripheral surface 12o2 without damaging the lip portion 41a.

[0047] Furthermore, since the first detachable member 31 and the oil seal 41 are removed without removing the oil seal 21, the space enclosed with the lubricant can be maintained in a sealed state. This allows the oil seal 41 to be replaced easily and quickly without discharging the lubricant from the space.

[0048] Thus, according to the joint structure 10 of this embodiment, the oil seal 41 can be easily removed from the wrist element 6 simply by removing the first detachable member 31 from the fixing member 11 , and can be easily installed on site without using a press or the like.

[0049] Thus, the oil seal 41 can be easily replaced without removing the wrist unit 6 from the robot 1 , moving the robot 1 itself to a location where a press is located, or bringing a press to the site.

[0050] In addition, regarding the oil seal 42, the same as the oil seal 41, as shown in FIG. Figure 5 As shown in FIG. 6 , the second detachable member 32 can be removed from the housing 62 a toward the side opposite to the flange surface 12 f , thereby being easily replaced.

[0051] If the first detachable member 31 or the second detachable member 32 removed from the wrist element 6 is undamaged and can be reused, the oil seals 41 and 42 are removed from the first detachable member 31 and the second detachable member 32 using a tool. Then, a new oil seal 41 and 42 is pressed into the first detachable member 31 and the second detachable member 32 from which the oil seals 41 and 42 have been removed, respectively, using a press.

[0052] Since the first detachable member 31 or the second detachable member 32 detached from the wrist unit 6 can be carried relatively easily, it can be brought to a place where a press machine is installed.

[0053] Furthermore, in this embodiment, the movable member 12 is composed of a single member, but instead, as Figure 6 As shown, a movable member (second member) 112 composed of two or more members may be used.

[0054] exist Figure 6 In the joint structure 110 shown, the movable member 112 includes: a cylindrical hollow member 81 provided with a through hole 81h extending along the sixth axis J6; and a through member 82 detachably mounted on the hollow member 81 while being inserted into the through hole 81h.

[0055] like Figure 6 As shown, the hollow member 81 may be a member integrally formed by fastening a main body 81 a constituting the inner ring of the bearing and a gear member 81 b provided with the driven gear 12 a by bolts 9 .

[0056] The hollow member 81 includes two outer peripheral surfaces (outer surfaces) 112o1 that are in full contact with the lips 21a, 22a of the oil seals 21, 22. A plurality of screw holes 81c are provided at one end of the hollow member 81 at intervals in the circumferential direction.

[0057] The through-hole member 82 is formed into a cylindrical shape having a through-hole 82h with the sixth axis J6 as the central axis. The through-hole member 82 has two outer peripheral surfaces (outer surfaces) 112o2 that are in contact with the lips 41a and 42a of the oil seals 41 and 42 over the entire circumference. Figure 6 As shown, a flange surface 112f is provided at one end of the through member 82 so as to protrude radially outward from the outer peripheral surface 112o2 in a flange-like manner. A plurality of through holes 82a are provided at intervals in the circumferential direction on the flange surface 112f.

[0058] like Figure 6 As shown, the hollow component 81 and the through-component 82 are coaxially arranged by fitting the through-component 82 into the through-hole 81h of the hollow component 81, and the hollow component 81 and the through-component 82 are fixed integrally by fastening a bolt (not shown) passing through the through-hole 82a to the threaded hole 81c.

[0059] When assembling the joint structure 110, with the first and second detachable components 31 and 32, into which the oil seals 41 and 42 are press-fitted, secured to the fixed component 11 and the housing 62a, respectively, the through-hole component 82 is inserted into the through-hole 81h and secured to the hollow component 81. When the through-hole component 82 is inserted into the through-hole 81h, the two outer peripheral surfaces 112o2 of the through-hole component 82 engage with the inner sides of the lips 41a and 42a of the oil seals 41 and 42, respectively. Furthermore, the flange surface 112f of the through-hole component 82 is positioned to cover the oil seal 41.

[0060] According to the joint structure 110 thus configured, the oil seal 41, which is susceptible to being splashed with dust and the like from the tool side, is protected by being covered by the flange surface 112f, thereby advantageously improving the durability of the oil seal 41. Furthermore, when replacing the oil seal 41, it is first necessary to remove the through member 82 from the hollow member 81 and then remove the first detachable member 31 from the fixed member 11.

[0061] Even in this case, if Figure 7 As shown, this can be done without removing the hollow member 81, so the oil seal 41 can be easily replaced without draining the lubricant. The oil seal 42 can be easily replaced by removing the second detachable member 32 from the housing 62a without removing the through member 82.

[0062] Furthermore, if the oil seals 41 and 42 are damaged by dust or the like, the two outer peripheral surfaces 112o2 in contact with the lips 41a and 42a may also be damaged by the dust being bitten into them. In such a case, the joint structure 110 has the advantage of being able to easily replace the through member 82 having two outer peripheral surfaces 112o2 without discharging the lubricant.

[0063] Furthermore, according to the joint structure 110, a movable member 112 is employed that includes a hollow member 81 having a through-hole 81h and a through-member 82 that can be easily attached to and detached from the hollow member 81. The through-member 82 is fixed to the hollow member 81 while being inserted through the through-hole 81h. This allows the two outer peripheral surfaces 112o2, located on either side of the oil seals 21 and 22 along the sixth axis J6, to be provided on a single through-member 82, eliminating the need for separate components and thus offering the advantage of reducing the number of components.

[0064] In addition, in this embodiment, Figure 6As shown, a through hole (observation window) 31h extending radially through the side wall of the first detachable member 31 between the oil seal 21 and the oil seal 41 may be provided. The through hole 31h may be sealed with a window member (not shown) made of a transparent material or with a detachable plug (not shown).

[0065] Thus, an operator can observe the state of the space between oil seals 21 and 41 from the outside through through-hole 31h. If dust or the like is detected in the space, the operator can determine that the sealing performance of oil seal 41 has deteriorated. In other words, by regularly or as needed checking the state of the space sealed by oil seals 21 and 41, oil seal 41 can be replaced before oil seal 21 is damaged.

[0066] In the case where the side surface of the fixing member 11 extends to a position between the oil seal 21 and the oil seal 41, the through hole 31h may be provided in the fixing member 11. Furthermore, instead of forming the observation window by the through hole 31h, the observation window may be formed by a notch provided in at least one of the fixing member 11 or the first detachable member 31 at the joint surface between the fixing member 11 and the first detachable member 31.

[0067] In addition, in this embodiment, the movable member 12 is arranged inside the housing 62a and the fixed member 11 so as to be rotatable around the sixth axis J6. Figure 8 As shown in FIG. 1 , the movable member (first member) 212 may be arranged outside the housing (second member) 162a. Figure 8 In the illustrated example, fixing members (second members) 111 are detachably mounted on both ends of the housing 162 a in the direction of the sixth axis J6 .

[0068] exist Figure 8 In the joint structure 210 shown, each fixed member 111 is provided with an outer peripheral surface 12o2 that contacts the lips 41a, 42a of the oil seals 41, 42. The first and second detachable members 31, 32 are detachably mounted on both ends of the movable member 212.

[0069] When replacing the oil seal 41, after removing the fixed member 111 from the housing 162a, the first detachable member 31 can be removed from the movable member 212, thereby enabling easy replacement in the same manner as described above. Furthermore, when replacing the oil seal 42, simply removing the second detachable member 32 from the movable member 212 allows easy replacement in the same manner as described above.

[0070] In this embodiment, the oil seals 41 and 42 are arranged on both sides of the sealing position sealed by the pair of oil seals 21 and 22. However, this embodiment can also be applied to a case where the housing 62a has a bag-like structure that is open in only one direction. In this case, for example, the oil seal 41 can be arranged on the outside of the sealing position sealed by the single oil seal 21 and mounted so that it can be removed using the first detachable member 31.

[0071] In addition, in this embodiment, the joint structure 10 between the second wrist element 62 and the third wrist element 63 is described as an example, but the present invention is not limited thereto and can be applied to joint structures at any other positions.

[0072] Description of reference numerals:

[0073] 1: Robot

[0074] 10: Joint structure

[0075] 11: Fixed component (first component)

[0076] 11i: Inner circumferential surface (first inner surface)

[0077] 12: Movable part (second part)

[0078] 12o1: outer surface (outer surface)

[0079] 12o2: outer surface

[0080] 21: Oil seal (first seal)

[0081] 22: Oil seal (first seal)

[0082] 31: First assembly and disassembly component (third component)

[0083] 31i: Inner circumferential surface (second inner surface)

[0084] 31h: Through hole (observation window)

[0085] 32: Second assembly and disassembly component (third component)

[0086] 32i: Inner circumference (second inner surface)

[0087] 41: Oil seal (second seal)

[0088] 42: Oil seal (second seal)

[0089] 62a: Housing (first component)

[0090] 62i: Inner circumferential surface (first inner surface)

[0091] 81: Hollow parts

[0092] 81h: Through hole

[0093] 82: Through parts

[0094] 110: Joint structure

[0095] 111: Fixed component (second component)

[0096] 112: Movable component (second component)

[0097] 112o1: outer surface (outer surface)

[0098] 112o2: outer surface

[0099] 162a: Housing (second component)

[0100] 210: Joint structure

[0101] 212: Movable component (first component)

[0102] J6: Sixth axis (axis)

Claims

1. A joint structure, characterized in that: have: a first member having a cylindrical first inner surface along a predetermined axis; a second member having a cylindrical outer surface disposed coaxially with the first inner surface; a first sealing member that seals an annular gap between the first inner surface and the outer surface while allowing the first component and the second component to rotate relative to each other about the axis; a third member having a second inner surface arranged coaxially with the first inner surface and detachably attached to the first member outside a sealing position sealed by the first seal; as well as a second sealing member pressed into the second inner surface and sealing an annular gap between the second inner surface and the outer surface while allowing the first component and the second component to rotate relative to each other about the axis; The first seal is disposed at both ends of the first component in the axial direction at positions for sealing the annular gap between the first inner surface and the outer surface. The second sealing member and the third member are respectively arranged outside the sealing position sealed by each of the first sealing members. The second member includes: a hollow member having a through hole extending in a direction along the axis; and a through member detachably fixed to the hollow member while being inserted through the through hole. The outer surface on which each of the first seals slides is provided on the hollow member, The outer surface on which each of the second seals slides is provided on the penetrating member.

2. The joint structure according to claim 1, characterized in that The joint structure includes an observation window that enables observation from the outside of a state in a gap between the first member and the second member between the first seal and the second seal disposed outside a sealing position of the first seal.

3. The joint structure according to claim 1 or 2, characterized in that: The maximum diameter of the second member outside a sealing position sealed by the second seal is equal to or smaller than the diameter of the outer surface on which the second seal slides.

4. A robot, characterized in that: The robot includes the joint structure according to any one of claims 1 to 3.

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