Reduction gear housing, reduction gear, and method for manufacturing a reduction gear housing

Abstract

The present invention relates to a reducer housing, a reducer, and a manufacturing method of a reducer housing. The reducer housing of the present invention has an inner tooth on an inner periphery. The reducer housing has an inner tooth portion including the inner tooth, and a housing main body portion that supports the inner tooth portion. The inner tooth portion is composed of a material that is superior in slidability to the slidability of the housing main body portion. The housing main body portion is composed of a material that is higher in hardness than the hardness of the inner tooth portion.

Description

Technical Field

[0001] This invention relates to a reducer housing, a reducer, and a method for manufacturing the reducer housing. Background Technology

[0002] For industrial robots, machine tools, etc., speed reducers are used to reduce the rotation of rotary drive sources such as motors (for example, see Patent Document 1).

[0003] The reducer described in Patent Document 1 has internal teeth, i.e., multiple pin grooves, arranged on the inner circumferential side of a cylindrical reducer housing. Columnar internal toothed pins are held in each pin groove in a slidable manner. The external teeth of the reduction mechanism portion housed inside the reducer housing mesh with the multiple internal toothed pins, appropriately reducing the input rotation and transmitting rotation to the output side. The pin grooves (internal teeth) arranged on the inner circumferential side of the reducer housing are integrally formed with the inner circumferential surface of the reducer housing.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-109264 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In the aforementioned reducer housing, the pin groove (internal tooth) is integrally formed with the inner circumferential surface of the reducer housing. Therefore, if aluminum alloy or the like is used to form the entire housing in order to improve the strength of the housing, the sliding properties of the pin groove (internal tooth) will deteriorate. On the other hand, if engineering plastic or the like is used to form the entire housing in order to ensure good sliding properties of the pin groove (internal tooth), it will be difficult to maintain a sufficiently high strength for the entire housing.

[0009] The present invention provides a reducer housing, a reducer, and a method for manufacturing the reducer housing, which can suppress the reduction of overall strength and improve the sliding properties of internal teeth.

[0010] Solution for solving the problem

[0011] One technical solution of the present invention provides a reducer housing with internal teeth on its inner circumference. The reducer housing has: an internal tooth portion containing the internal teeth; and a housing body portion supporting the internal tooth portion. The internal tooth portion is made of a material with better sliding properties than the housing body portion, and the housing body portion is made of a material with higher hardness than the internal tooth portion.

[0012] Alternatively, the main body of the shell may be made of a material with a higher melting point than the internal teeth.

[0013] Ideally, the housing body is formed as a cylindrical shape covering at least the radially outer region of the internal teeth.

[0014] Alternatively, the internal teeth of the internal tooth portion may be a pin groove that holds the cylindrical internal tooth pin in a sliding position.

[0015] The reducer of one embodiment of the present invention has any one of the reducer housings described above and a reduction mechanism portion disposed inside the reducer housing.

[0016] One technical solution of the present invention provides a method for manufacturing a reducer housing having internal teeth on its inner circumference. The reducer housing comprises: an internal tooth portion containing the internal teeth; and a housing body portion supporting the internal tooth portion. The internal tooth portion is made of a material with better sliding properties than the housing body portion. The housing body portion is made of a material with a higher hardness than the internal tooth portion. In the manufacturing method, the housing body portion is first formed, then placed in a molding die, and the internal tooth portion is formed by injection molding.

[0017] The effects of the invention

[0018] The reducer housing of one embodiment of the present invention can ensure overall strength by utilizing the main body of the housing, and can ensure the sliding properties of the internal teeth by utilizing the internal tooth portion. Therefore, when using the reducer housing of one embodiment of the present invention, the reduction in overall strength can be suppressed, and the sliding properties of the internal teeth can be improved. Attached Figure Description

[0019] Figure 1 This is a longitudinal sectional view of the speed reducer according to the implementation method.

[0020] Figure 2 This is a perspective view of the reducer housing according to the embodiment. Detailed Implementation

[0021] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

[0022] Figure 1 This is a longitudinal sectional view of the reducer 10 of this embodiment.

[0023] The reducer 10 of this embodiment is used together with a rotary drive source such as a motor in, for example, the movable joint of an industrial robot. A rotary drive source (not shown) is connected to the input side of the reducer 10.

[0024] The reducer 10 includes: a generally cylindrical reducer housing 11; an input shaft 12 rotatably disposed at the axial center of the reducer housing 11; a reduction mechanism 13 that reduces the rotation of the input shaft 12; and an output rotating body 14 that outputs the rotation reduced by the reduction mechanism 13.

[0025] The reducer housing 11 has: a main housing 11A, which is mounted on the joint movable part of the robot, etc.; and an annular end block 11B, which is bolted to one end face of the main housing 11A in the axial direction.

[0026] The input shaft 12 has a rotary drive source (not shown) connected to one axial end, and its other axial end supported rotatably by a bearing 16 in the central bore 14a of the output rotating body 14. The input shaft 12 has a pair of eccentric portions 12A and 12B in its central region, radially eccentric relative to the central axis o1 of the input shaft 12. The pair of eccentric portions 12A and 12B are eccentrically offset from each other by 180° in phase about the central axis o1. Each eccentric portion 12A and 12B is formed in a circular cross-section, and an eccentric bearing 17 is mounted on its outer circumferential surface.

[0027] The reduction mechanism 13 includes: a first oscillating gear 18A and a second oscillating gear 18B, which have external teeth 20 on their outer circumferences and oscillate and rotate (revolve) with the rotation of the input shaft 12; a pin groove 30, which has internal teeth formed on the inner circumference of the main housing 11A; and a plurality of internal toothed pins 19 held in the pin groove 30. The pin groove 30 is configured, for example, as an involute tooth. Each internal toothed pin 19 is held in the pin groove 30 on the inner circumference of the main housing 11A in a manner that allows it to roll parallel to the central axis o1. The outer diameters of the first oscillating gear 18A and the second oscillating gear 18B are formed to be slightly smaller than the inner diameter of the reducer housing 11. The number of teeth of the external teeth 20 formed on the outer circumferential surfaces of the first oscillating gear 18A and the second oscillating gear 18B is set to be slightly less than the number of internal toothed pins 19 (for example, one less).

[0028] Each of the first oscillating gear 18A and the second oscillating gear 18B has a through hole 21 with a predetermined inner diameter formed in its center portion. An eccentric bearing 17, which is mounted on the eccentric portions 12A and 12B of the input shaft 12, is inserted into each through hole 21. The first oscillating gear 18A and the second oscillating gear 18B are rotatably supported on the eccentric portions 12A and 12B of the input shaft 12 by means of the eccentric bearing 17.

[0029] If the input shaft 12 is driven by a rotational drive source (not shown) and rotates, the eccentric portions 12A and 12B of the input shaft 12 will oscillate and rotate (revolve) in the same direction with a predetermined radius. Simultaneously, the first oscillating gear 18A and the second oscillating gear 18B will oscillate and rotate (revolve) in the same direction with the same radius. At this time, the external teeth 20 of each of the first oscillating gear 18A and the second oscillating gear 18B will engage with the plurality of internal toothed pins 19 on the inner circumference of the main housing 11A. In this embodiment, the number of teeth on the external teeth 20 of each of the first oscillating gear 18A and the second oscillating gear 18B of the reduction mechanism 13 is set to be slightly less than the number of internal toothed pins 19 on the main housing 11A side. Therefore, during one revolution of the first oscillating gear 18A and the second oscillating gear 18B, the first oscillating gear 18A and the second oscillating gear 18B receive a reaction force in the direction of rotation from the internal tooth pin 19 on the main housing 11A side, and rotate a predetermined distance in the opposite direction to the oscillating rotation direction (rotation direction). Thus, for the reduction mechanism 13 of this embodiment, the rotation of the input shaft 12 is reduced by a predetermined reduction ratio, causing the first oscillating gear 18A and the second oscillating gear 18B to rotate.

[0030] The output rotating body 14 is formed as a short-shaft cylinder with a central bore 14a. The output rotating body 14 is positioned within the housing 11 adjacent to the second oscillating gear 18B. The output rotating body 14 is rotatably supported on the reducer housing 11, for example, by means of bearings 22 such as crossed roller bearings.

[0031] Furthermore, a plurality of pin insertion holes 23 are formed at equal intervals in the circumferential direction on the outer periphery of the output rotating body 14. The plurality of pin insertion holes 23 are arranged on a concentric circle centered on the axis of the output rotating body 14 (the central axis o1 of the input shaft 12). Each pin insertion hole 23 passes through the output rotating body 14 parallel to the axis of the output rotating body 14 (the central axis o1 of the input shaft 12). A rotary transmission pin 24 for transmitting the rotation of the first oscillating gear 18A and the second oscillating gear 18B to the output rotating body 14 is inserted into each pin insertion hole 23. The rotary transmission pin 24 has: a rod portion 24a with a substantially fixed outer diameter; a flange portion 24b extending radially outward from one axial end of the rod portion 24a; and an external thread portion 24c protruding coaxially with the rod portion 24a from the other axial end. The external threaded portion 24c is formed with a diameter smaller than that of the rod portion 24a, and has an external thread on its outer circumferential surface.

[0032] A circular rotation transmission hole 25, with an inner diameter larger than the inner diameter of the pin insertion hole 23, is formed at a position on the first oscillating gear 18A and the second oscillating gear 18B corresponding to the pin insertion holes 23 of the output rotating body 14. The rod portion 24a of the corresponding rotation transmission pin 24 passes through the rotation transmission hole 25 of each of the first oscillating gear 18A and the second oscillating gear 18B. The base side of the rod portion 24a of the rotation transmission pin 24 is fitted into the pin insertion hole 23 of the output rotating body 14, and the top end side passes through the rotation transmission hole 25 of each of the first oscillating gear 18A and the second oscillating gear 18B. A pair of sliding rings 26 with low frictional resistance are fitted onto the outer peripheral surface of the top end side of the rod portion 24a. Each sliding ring 26 slides in contact with the inner surface of the corresponding rotation transmission hole 25 when the first oscillating gear 18A and the second oscillating gear 18B oscillate and rotate simultaneously as described above. Thus, the rotational force of the first oscillating gear 18A and the second oscillating gear 18B is transmitted to the rotary transmission pin 24. The rotational force transmitted to the rotary transmission pin 24 is then transmitted to the output rotating body 14, which is held at one end of the rotary transmission pin 24 in the axial direction.

[0033] Furthermore, an annular end plate 27 is disposed at the axial end of the reducer 10 on the side opposite to the output rotating body 14. Multiple through holes 28 are formed in the end plate 27. An external threaded portion 24c of the rotation transmission pin 24, protruding from the rotation transmission hole 25 of the first oscillating gear 18A, passes through each through hole 28. A fastening nut 29 is screwed into the top end of the external threaded portion 24c protruding from the through hole 28. Thus, the end plate 27 is integrally fastened to the ends of the multiple rotation transmission pins 24. Therefore, the end plate 27 and the output rotating body 14 always rotate integrally.

[0034] Figure 2 This is a perspective view of the main housing 11A of the reducer housing 11.

[0035] The main housing 11A has: a generally cylindrical internal toothed portion 35 having a plurality of pin grooves 30 on its inner circumferential side; and a housing body portion 36 supporting the internal toothed portion 35 from the outside. The housing body portion 36 is formed in a cylindrical shape to cover the radially outer region and the two axially oriented sides of the internal toothed portion 35. The housing body portion 36 is made of a lightweight metal with high specific strength, such as aluminum alloy. In contrast, the internal toothed portion 35 is made of a hard resin such as an engineering plastic with excellent surface lubricity.

[0036] The internal teeth 35 are made of a material with better sliding properties than the main body 36 of the housing, and the main body 36 is made of a material with a higher hardness than the internal teeth 35. Furthermore, the main body 36 is made of a material with a higher melting point than the material constituting the internal teeth 35.

[0037] Also Figure 1As shown, an annular groove 40 with a predetermined axial width is formed on the inner circumferential side of the housing body 36. The internal toothed portion 35 is disposed in the annular groove 40 of the housing body 36 in such a way that a plurality of pin grooves 30 are exposed on the inner circumferential side.

[0038] The main housing 11A can be manufactured, for example, as follows.

[0039] First, the main body of the shell 36, made of a lightweight metal with high specific strength, is pre-formed using casting or other methods.

[0040] Next, the main body 36 of the housing is placed in a molding die, and hard resin for shaping the internal teeth 35 is injected into the die. At this time, the pin groove 30 of the internal teeth 35 is shaped using the inner surface of the molding die, and the injected hard resin fills the annular groove 40 of the main body 36 without gaps. After this, the hard resin is allowed to harden before the product is removed from the molding die. The internal teeth 35 of the removed product are integrated with the main body 36 of the housing, and the pin groove 30 of the internal teeth 35 becomes a smooth injection-molded surface.

[0041] In addition, the resin constituting the internal tooth portion 35 can also be a fiber-reinforced resin.

[0042] Furthermore, the end block 11B of the reducer housing 11 does not have a pin groove 30, so it is cast using a lightweight metal with high specific strength, such as aluminum alloy. In addition, the housing body 36 of the main housing 11A and the end block 11B are machined into suitable shapes by cutting or the like.

[0043] As described above, in this embodiment, the internal tooth portion 35 of the reducer housing 11 is made of a material with better sliding properties than the housing body portion 36, and the housing body portion 36 is made of a material with higher hardness than the internal tooth portion 35. Therefore, the overall strength can be ensured by utilizing the housing body portion 36, and the sliding properties of the pin groove 30 (internal tooth) can be improved by utilizing the internal tooth portion 35. Thus, when the reducer housing 11 of this embodiment is adopted, the reduction in strength of the reducer housing 11 can be suppressed, and the sliding properties of the pin groove 30 can be improved.

[0044] Furthermore, in this embodiment, the main body 36 of the reducer housing 11 is made of a material with a higher melting point than the internal gear portion 35. Therefore, it is possible to prevent deformation of the main body 36 due to the heat of the molten resin when the pre-shaped main body 36 is placed in a molding die and resin for shaping the internal gear portion is injected into the die in that state, as described above. Consequently, the shape of the main body 36 is stabilized, and the strength of the reducer housing 11 is ensured.

[0045] Furthermore, in this embodiment, the reducer housing 11 is formed as a cylindrical shape, with the housing body 36 covering the radially outer region of the internal gear 35. Therefore, even if a large torque is applied to the inner circumference of the internal gear 35 from the first oscillating gear 18A and the second oscillating gear 18B, the deformation of the internal gear 35 in the expansion direction (radially outer direction) can be limited by the high-strength cylindrical housing body 36. Thus, when the reducer housing 11 of this embodiment is adopted, the reduction accuracy of the reducer 10 can be maintained at a high level.

[0046] Furthermore, the reducer housing 11 in this embodiment is configured such that the columnar internal toothed pin 19 can be slidably held in the pin groove 30 of the internal tooth portion 35. Therefore, the sliding properties of the pin groove 30 and the internal toothed pin can be well maintained, and the reduction accuracy of the reducer 10 can be further improved.

[0047] Furthermore, in the aforementioned method for manufacturing the reducer housing, the housing body 36 is pre-formed, the housing body 36 is placed in a molding die, and the internal gear portion 35 is formed by injection molding. Therefore, by employing this manufacturing method, the internal gear portion 35 can be integrated with the housing body 36 in a close-fitting state, and on this basis, the surface of the pin groove 30 (internal gear) of the internal gear portion 35 can be made into a smooth injection-molded surface that contacts the molding die.

[0048] Furthermore, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from its spirit.

[0049] For example, in the above embodiment, the reducer housing 11 is composed of two parts: the main housing 11A and the end block 11B. However, the reducer housing may also be composed of one part or three or more parts. In addition, the materials constituting the internal gear portion 35 and the housing body portion 36 are not limited to the illustrated materials. For example, the housing body portion 36 may also be formed of ferrous metals or resin.

Claims

1. A reducer housing, wherein the reducer housing has internal teeth on its inner circumference, wherein, The reducer housing has: Internal tooth portion, which includes the internal teeth; and The main body of the housing supports the internal teeth. The internal teeth are made of a material with better sliding properties than the main body of the housing. The main body of the shell is made of a material with a higher hardness than the internal teeth. The main body of the housing is formed as a cylinder covering at least the radially outer region of the internal teeth. An annular groove is formed on the inner circumferential side of the main body of the housing. The annular groove is filled with the material forming the internal teeth, such that the internal teeth are exposed on the inner circumferential side. The internal teeth of the internal tooth portion are pin grooves that hold the cylindrical internal tooth pin in a sliding position.

2. The reducer housing according to claim 1, wherein, The main body of the shell is made of a material with a higher melting point than the internal teeth.

3. A speed reducer, wherein, This reducer has the following features: The reducer housing as described in claim 1 or 2; and The speed reduction mechanism is located inside the reducer housing.

4. A method for manufacturing a reducer housing, wherein the reducer housing has internal teeth on its inner circumference, wherein, The reducer housing has: an internal gear portion containing internal teeth; and a housing body portion supporting the internal gear portion, wherein the internal gear portion is made of a material with better sliding properties than the housing body portion, and the housing body portion is made of a material with higher hardness than the internal gear portion. In the manufacturing method of the reducer housing, First, the main body of the shell is formed. The main body of the housing is placed in a molding die, and the internal teeth are formed by injection molding. The internal teeth of the internal tooth portion are pin grooves that hold the cylindrical internal tooth pin in a sliding position.

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