CN111486198A

CN111486198A - Eccentric oscillation type reduction gear and method for manufacturing external gear

Info

Publication number: CN111486198A
Application number: CN201911065497.4A
Authority: CN
Inventors: 阿部瞬; 为永淳
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2019-01-29
Filing date: 2019-11-04
Publication date: 2020-08-04
Also published as: JP7319784B2; JP2020122500A; DE102019131432A1; DE102019131432B4

Abstract

The invention provides an eccentric swing type speed reducing device which can restrain the reduction of durability even if the device is miniaturized. An eccentric oscillation type reduction gear (10) is provided with an external gear (14), an eccentric body that oscillates the external gear (14), and an internal gear that meshes with the external gear (14), wherein the external gear (14) has a 1 st through-hole (13) and a 2 nd through-hole (15) that is provided adjacent to the 1 st through-hole (13) in the circumferential direction or the radial direction. An inner peripheral surface (13b) of the 1 st through-hole (13) has a 1 st portion (13e) which includes a portion (13f) facing the 2 nd through-hole (15) and is subjected to plastic working.

Description

Eccentric oscillation type reduction gear and method for manufacturing external gear

The present application claims priority based on japanese patent application No. 2019-013541, applied on 29/1/2019. The entire contents of this Japanese application are incorporated by reference into this specification.

Technical Field

The present invention relates to an eccentric oscillating type reduction gear and a method of manufacturing an external gear.

Background

The present applicant discloses in patent document 1 a power transmission device including an internal gear and an external gear that meshes with the internal gear. The power transmission device described in patent document 1 includes an eccentric bearing that eccentrically rotates in accordance with rotation of an input shaft, and an inner pin that outputs a rotation component of an external gear. The external gear is provided with a hole for fitting the bearing for the eccentric body and a hole for fitting the inner pin.

Patent document 1: japanese laid-open patent publication No. 2006-263878

The present inventors have studied the miniaturization of an eccentric oscillating type reduction gear having an external gear, and have obtained the following recognition.

In order to miniaturize such an eccentric oscillating type reduction gear, it is conceivable to reduce the thickness of the external gear in the axial direction. When the external gear is made thin, the area of the portion in contact with the bearing for the eccentric body or the inner pin decreases. When the contact area is reduced, stress increases under the same load, and stress cracking is likely to occur in this portion, which causes a problem of reduced durability.

Such a problem occurs not only when the external gear is made thin, but also when the thickness of the external gear in the radial direction is made small for the purpose of reducing the diameter. Further, the same problem arises when the allowable torque is increased without changing the size of the reduction gear, in other words, when the size per unit allowable torque is reduced. That is, in the eccentric rocking type reduction gear, the miniaturization and the durability are in a relationship of the two-tone bar.

As described above, the present inventors have recognized that the power transmission device described in patent document 1 has room for improvement in terms of both downsizing and durability.

Disclosure of Invention

The present invention has been made in view of such a problem, and an object thereof is to provide an eccentric rocking type reduction gear device capable of suppressing a decrease in durability even when the reduction in size is made.

In order to solve the above-described problems, an embodiment of the present invention provides an eccentric oscillating type reduction gear including an external gear, an eccentric body that oscillates the external gear, and an internal gear that meshes with the external gear, wherein the external gear has a 1 st through-hole and a 2 nd through-hole that is provided adjacent to the 1 st through-hole in a circumferential direction or a radial direction. The inner peripheral surface of the 1 st through hole has a 1 st portion which includes a portion facing the 2 nd through hole and is subjected to plastic working.

Another embodiment of the present invention also provides an eccentric oscillating type reduction gear including an external gear, an eccentric body that oscillates the external gear, and an internal gear that meshes with the external gear, wherein the external gear has a 1 st through-hole and a 2 nd through-hole provided adjacent to the 1 st through-hole in a circumferential direction or a radial direction. The inner peripheral surface of the 1 st through hole has: a 1 st portion including a portion opposed to the 2 nd through hole and having a surface with a high compressive residual stress; and part 2 having a compressive residual stress at its surface which is equal to or greater than 1/5 of the compressive residual stress at its surface of part 1.

Another embodiment of the present invention provides a method of manufacturing an external gear. The external gear is oscillated by the eccentric body in the eccentric oscillating type reduction gear to be internally meshed with the internal gear, and the external gear has a 1 st penetration hole and a 2 nd penetration hole provided adjacent to the 1 st penetration hole in a circumferential direction or a radial direction. The method for manufacturing the external gear includes a plastic working step of performing plastic working on an inner peripheral surface of the 1 st through-hole.

In addition, any combination of the above-described constituent elements or a mode in which the constituent elements or expressions of the present invention are interchanged with each other between methods, systems, and the like is also effective as an embodiment of the present invention.

According to the present invention, it is possible to provide an eccentric rocking type reduction gear device capable of suppressing a decrease in durability even when the reduction in size is performed.

Drawings

Fig. 1 is a side sectional view showing an eccentric rocking type reduction gear according to embodiment 1.

Fig. 2 is a front view showing an external gear of the eccentric oscillation type reduction gear of fig. 1.

Fig. 3 is a flowchart schematically showing an example of a method of manufacturing the external gear of fig. 1.

Fig. 4 is a schematic view illustrating a plastic working process of the external gear of fig. 1.

Fig. 5 is a side sectional view showing the eccentric rocking type reduction gear according to embodiment 2.

Fig. 6 is a sectional view taken along line a-a of fig. 5.

Fig. 7 is a front view showing an external gear of the eccentric oscillation type reduction gear of fig. 5.

In the figure: 10-eccentric oscillating type reduction gear, 12-input shaft, 12 a-eccentric body, 13-1 st through hole, 13 b-inner circumferential surface, 14-external gear, 15-2 nd through hole, 16-internal gear, 18, 20-wheel carrier, 22-shell, 24-main bearing, 30-roller bearing, 32-internal pin, 35-roller, 80-plastic processing device and 84-nozzle.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the embodiment, the comparative example, and the modification, the same or equivalent constituent elements and components are denoted by the same reference numerals, and overlapping description is appropriately omitted. In the drawings, the dimensions of the components are shown enlarged or reduced as appropriate for the convenience of understanding. In the drawings, parts that are not essential to the description of the embodiments are omitted.

Further, although the terms including the numbers 1, 2, and the like are used to describe various constituent elements, the terms are used only for the purpose of distinguishing one constituent element from other constituent elements, and the terms are not intended to limit the constituent elements.

[ embodiment 1 ]

Hereinafter, the structure of the eccentric rocking type reduction gear transmission 10 according to embodiment 1 will be described with reference to the drawings. Fig. 1 is a side sectional view showing an eccentric rocking type reduction gear transmission 10 according to embodiment 1. The eccentric oscillating type speed reduction device 10 of the present embodiment is an eccentric oscillating type speed reduction device that oscillates an external gear meshing with an internal gear, thereby rotating one of the internal gear and the external gear and outputting the motion component from an output member to a driven device.

The eccentrically oscillating type reduction gear 10 mainly includes an input shaft 12, an external gear 14, an internal gear 16, a carrier 18, a carrier 20, a housing 22, a main bearing 24, and a main bearing 26, hereinafter, a direction along a central axis L a of the internal gear 16 is referred to as an "axial direction", a circumferential direction and a radial direction of a circle centered on the central axis L a are referred to as a "circumferential direction" and a "radial direction", respectively, and hereinafter, for convenience of description, one side (right side in the drawing) in the axial direction is referred to as an input side, and the other side (left side in the drawing) is referred to as an opposite input side.

The input shaft 12 rotates about a rotation center line by rotational power input from a driving device (not shown), the eccentric rocking type reduction gear transmission 10 of the present embodiment is of a center crank type in which the rotation center line of the input shaft 12 is provided coaxially with the center axis line L a of the ring gear 16, and the driving device is, for example, a motor, a gear motor, an engine, or the like.

The input shaft 12 of the present embodiment is an eccentric body shaft having a plurality of eccentric bodies 12a for oscillating the external gear 14. The axis of the eccentric body 12a is eccentric with respect to the rotation center line of the input shaft 12. In the present embodiment, three eccentric bodies 12a are provided, and the eccentric phases of the adjacent eccentric bodies 12a are shifted by 120 ° from each other. A spline 12b for receiving power from an output member of the drive device is formed at an end portion of the input side of the input shaft 12.

Three external gears 14 are assembled to the outer periphery of the eccentric body 12a via roller bearings 30. Each external gear 14 meshes with the internal gear 16. The external gears 14 are assembled in three rows to increase the transmission capacity and reduce vibration and noise due to the shift of the eccentric phase. The structures of the external gears of the respective rows are the same except for the difference in eccentric phase.

Fig. 2 is a front view of the external gear 14 as viewed from the input side. The external gears 14 are provided individually corresponding to the plurality of eccentric bodies 12a, respectively. The external gear 14 is rotatably supported by the corresponding eccentric body 12a via a roller bearing 30. The external gear 14 is provided with a 1 st through hole 13 through which the inner pin 32 passes and a 2 nd through hole 15 which abuts against the roller bearing 30. As shown in fig. 2, the 1 st through-hole 13 and the 2 nd through-hole 15 are adjacent to each other in the radial direction.

The 1 st through hole 13 is provided in the outer gear 14 offset from the center thereof. The 1 st through hole 13 is provided in plural corresponding to an inner pin 32 described later. In this example, six 1 st through-holes 13 are provided at intervals of 60 ° in the circumferential direction. The 2 nd through hole 15 is provided at the center of the external gear 14, and is a hole into which the eccentric body 12a is inserted.

As shown in fig. 1, the housing 22 is cylindrical as a whole, and the internal gear 16 is provided on the inner peripheral portion thereof. The internal gear 16 meshes with the external gear 14. The internal gear 16 of the present embodiment is composed of an internal gear main body integrated with the case 22, and outer pins 16a (pin members) rotatably supported by the internal gear main body and constituting internal teeth of the internal gear 16. The number of internal teeth of the internal gear 16 (the number of the outer pins 16 a) is slightly larger than the number of external teeth of the external gear 14 (in this example, only 1 more).

The

carriers

18, 20 are disposed on the axial side portions of the external gear 14. The

carriers

18, 20 include a 1 st carrier 18 disposed on the side of the input side of the external gear 14 and a 2 nd carrier 20 disposed on the side of the opposite side of the input side of the external gear 14. The

carriers

18 and 20 have a disk shape, and rotatably support the input shaft 12 via an input shaft bearing 34.

The 1 st carrier 18 and the 2 nd carrier 20 are coupled together via inner pins 32, the inner pins 32 axially penetrate the plurality of external gears 14 at positions radially offset from the axial centers of the external gears 14, the inner pins 32 of the present embodiment are formed integrally with the 2 nd carrier 20, the inner pins 32 may be formed separately from the

carriers

18, 20, the inner pins 32 are provided in plurality at predetermined intervals around the central axis L a of the internal gear 16, and in the present embodiment, six inner pins 32 are provided at intervals of 60 ° in the circumferential direction.

The inner pin 32 has a tip end portion fitted into a bottomed recess 18c formed in the 1 st carrier 18, and couples the 1 st carrier 18 and the 2 nd carrier 20 together with a bolt 36 inserted from the input side of the 1 st carrier 18.

The inner pin 32 penetrates the 1 st penetration hole 13 formed in the outer gear 14. A roller 35 is rotatably covered on the outer peripheral surface 32s of the inner pin 32 as a sliding promoting member. The axial movement of the roller 35 is restricted by the input side of the 1 st carrier 18 and the opposite side of the 2 nd carrier 20. A play (i.e., a gap) for absorbing the oscillation component of the external gear 14 is provided between the drum 35 and the 1 st through-hole 13. The roller 35 is partially in contact with the inner wall surface of the 1 st penetration hole 13. Further, the drum 35 may be omitted.

A member that outputs rotational power to a driven device (not shown) is an output member, and a member that is fixed to an external member that supports the eccentric rocking type reduction gear transmission 10 is a fixed member. The output member of the present embodiment is the 2 nd carrier 20, and the fixed member is the casing 22. The output member is rotatably supported by the fixed member via

main bearings

24 and 26.

The

main bearings

24 and 26 include a 1 st main bearing 24 disposed between the 1 st carrier 18 and the casing 22, and a 2 nd main bearing 26 disposed between the 2 nd carrier 20 and the casing 22. In the present embodiment, the

main bearings

24 and 26 are arranged in a so-called back-to-back combination state. The outer peripheries of the 1 st carrier 18 and the 2 nd carrier 20 form the inner rings of the 1 st main bearing 24 and the 2 nd main bearing 26, respectively. In the present embodiment, angular ball bearings having spherical rolling elements 42 are exemplified as the

main bearings

24 and 26. In addition, rolling bearings such as tapered roller bearings and angular contact roller bearings described later may be used as the

main bearings

24 and 26.

The operation of the eccentric rocking type reduction gear transmission 10 configured as described above will be described. When the rotational power is transmitted from the driving device to the input shaft 12, the eccentric body 12a of the input shaft 12 rotates about the rotation center line passing through the input shaft 12. Since the eccentric body 12a performing eccentric motion is in contact with the 2 nd through-hole 15 via the roller bearing 30, the external gear 14 oscillates. At this time, the external gear 14 oscillates so that its axis rotates around the rotation center line of the input shaft 12. When the external gear 14 oscillates, the meshing positions of the external gear 14 and the internal gear 16 sequentially deviate. As a result, one of the external gear 14 and the internal gear 16 rotates by the difference in the number of teeth between the external gear 14 and the internal gear 16 for each rotation of the input shaft 12. In the present embodiment, the external gear 14 rotates and the decelerated rotation is output from the 2 nd carrier 20 via the inner pin 32.

Next, the external gear 14 will be further explained with reference to fig. 2. The 2 nd through-hole 15 of the external gear 14 functions as an outer ring raceway surface of the roller bearing 30, and therefore receives a rolling element load of the roller bearing 30. In order to achieve miniaturization, it is conceivable to reduce the thickness between the 1 st through hole 13 and the 2 nd through hole 15. However, if the thickness between the 1 st through hole 13 and the 2 nd through hole 15 is small, stress increases under the same rolling element load, and stress cracking easily occurs in this portion. Even if the thickness between the 1 st through hole 13 and the 2 nd through hole 15 is not changed, the rolling element load increases and the stress increases during high torque operation, and stress cracking is likely to occur similarly.

When the rolling element load is received, the stress distribution of the external gear 14 is compressive stress on the 2 nd through-hole 15 side receiving the load, and tensile stress on the 1 st through-hole 13 side. Therefore, for example, a stress crack may be generated as indicated by reference sign D in fig. 2 starting from the 1 st through hole 13 side receiving the tensile stress. Therefore, in the external gear 14 of the present embodiment, plastic working is performed on a predetermined portion, and the influence of the tensile stress of the load is reduced by the compressive residual stress based on the plastic working.

As shown in fig. 2, in the present embodiment, a 1 st portion 13e, which includes an opposing portion 13f opposing the 2 nd through-hole 15 and is subjected to plastic working, is provided on an inner peripheral surface 13b of the 1 st through-hole 13. In this case, the occurrence of stress cracking due to the rolling element load can be suppressed by the compressive residual stress of the plastic working. The 1 st portion 13e may extend toward both sides of the opposing portion 13f of the inner peripheral surface 13 b. The 1 st portion 13e may be provided continuously or intermittently. The 1 st portion 13e of the present embodiment is provided in an arc shape in a range of 20% to 70% of the inner peripheral surface 13b in a front view.

If the plastic working is performed in a wide range, the working time may be prolonged, which may increase the working cost. Therefore, in the present embodiment, the 2 nd portion 13h, which is not subjected to plastic working, is provided on the inner peripheral surface 13b of the 1 st through-hole 13. In this case, the processing cost can be reduced and the processing time can be shortened. The 2 nd portion 13h may include a portion 13j of the inner peripheral surface 13b on the opposite side to the opposing portion 13f, or may extend toward both sides of the portion 13 j. The 2 nd part 13h of the present embodiment is provided in a range other than the 1 st part 13 e. In addition, the "portion not subjected to plastic working" includes a portion which is not intentionally subjected to plastic working but has a slight residual stress for some reason.

In the present embodiment, the 2 nd through hole 15 is not subjected to plastic working. The reason for this is that the stress of the rolling element load applied to the 2 nd through hole 15 is substantially compressive stress, and therefore the necessity of performing plastic working is lower than that of the 1 st through hole 13. Further, since the roller bearing 30 is in contact with the inner peripheral surface of the 2 nd through hole 15, it is not preferable to perform plastic working, and the surface roughness is increased.

As the plastic working, various methods can be employed as long as a working method is applied with a stress equal to or greater than the elastic limit to a predetermined portion and plastic deformation having a compressive residual stress is generated. In the present embodiment, as the plastic working, a working by shot peening using a blasting medium (hereinafter, simply referred to as "shot peening") is used. That is, the shot peening is performed as plastic working for the 1 st portion 13 e. In this case, since shot peening is used, plastic working can be performed easily and inexpensively.

Next, the residual stress by plastic working will be described. In the following, when the residual stress is expressed in numerical form, the compressive stress is expressed by a negative value denoted by "-", and the tensile stress is expressed by a positive value not denoted by a symbol. Further, "a value equal to or larger than a certain value" indicates a value on the positive direction side from the certain value, and "a value equal to or smaller than the certain value" indicates a value on the negative direction side from the certain value.

The compressive residual stress "higher than a certain value" indicates that the residual stress is a value on the negative direction side of the value, and the compressive residual stress "lower than a certain value" indicates that the residual stress is a value on the positive direction side of the value.

First, the residual stress on the surface of the raw material will be described. Tensile stress of rolling element load is applied to the contact surface (i.e., surface). Therefore, the plastic working is preferably plastic working in which the surface of the raw material has compressive residual stress. According to the study of the present inventors, it was confirmed that the generation of stress cracks due to the rolling element load can be suppressed as long as the residual stress on the surface of the 1 st portion 13e is-800 MPa or less. From the viewpoint of more effectively suppressing stress cracking, the residual stress of the surface of the 1 st portion 13e is preferably-1100 MPa or less. In addition, these residual stresses may be measured at the opposing portion 13 f.

Next, the residual stress inside the material will be described. The tensile stress of the rolling element load affects not only the surface but also the inside of the raw material. Therefore, the plastic working preferably causes the raw material to have compressive residual stress also inside. According to the study of the present inventors, it was confirmed that the generation of stress cracks due to the rolling element load can be suppressed as long as the compressive residual stress at 60 μm from the surface of the 1 st part 13e is higher than the compressive residual stress of the surface. From the viewpoint of more effectively suppressing stress cracking, the residual stress at 60 μm from the surface of the 1 st portion 13e is preferably-1000 MPa or less, and more preferably-1300 MPa or less. In addition, these residual stresses may be measured at the opposing portion 13 f.

From the viewpoint of shortening the processing time, the compressive residual stress of the surface of the 2 nd portion 13h may be 1/5 or more of the compressive residual stress of the surface of the 1 st portion 13 e. In addition, the residual stress of the surface of the 2 nd portion 13h may be expressed as a compressive residual stress having an absolute value of 1/5 or less or a tensile residual stress having an absolute value of the compressive residual stress of the surface of the 1 st portion 13 e. For example, when the residual stress of the surface of the 1 st portion 13e is-800 MPa, the residual stress of the surface of the 2 nd portion 13h may be-160 MPa or more, or may be a tensile stress. In this case, plastic working can be concentrated on the 1 st portion 13e, and therefore the entire working time can be shortened.

Hereinafter, the residual stress in the examples will be described. The residual stress of the 1 st portion 13e is compressive residual stress at least in the range from the surface to the depth of 140 μm. The compressive residual stress of the portion 1 e is-1300 MPa at the surface, is-1300 to-1400 MPa in the range from the surface to the depth of 40 μm, and is-1550 MPa (maximum value) at the depth of 60 μm. The compressive residual stress gradually decreased in the range from 60 μm in depth to 140 μm in depth, and was-700 MPa at 140 μm in depth. That is, in the embodiment, the compressive residual stress imparting effect based on plastic working is at least waved to the region. The compressive residual stress is higher than-1000 MPa in the range from the surface to the depth of 100 μm.

Next, an example of the method S80 for manufacturing the external gear 14 will be described with reference to fig. 3 and 4. Fig. 3 is a flowchart schematically showing an example of the method S80 for manufacturing the external gear 14. Fig. 4 is a schematic diagram illustrating a plastic working step S88 of the external gear 14. The method S80 of manufacturing the external gear 14 includes a step S82 of forming a circular disk, a step S84 of forming external teeth, a step S86 of forming the 1 st through-hole 13 and the 2 nd through-hole 15, and a plastic working step S88 of performing plastic working on the inner circumferential surface of the 1 st through-hole 13. Hereinafter, the external gear 14 in the middle of manufacturing is referred to as a "workpiece".

In step S82, a disk-shaped workpiece is formed from the material by cold forging. In step S84, external teeth are formed on the disc-shaped workpiece by further cold forging. In step S86, the 1 st through-hole 13 and the 2 nd through-hole 15 are formed in the workpiece having the external teeth formed thereon by punching. In step S88, the inner peripheral surface of the 1 st through hole 13 of the workpiece is subjected to plastic working. The outer gear 14 may be subjected to heat treatment for surface hardening, finish polishing for correcting thermal strain, chemical conversion treatment for reducing friction, and the like as necessary. This manufacturing method S80 is merely an example, and the order of the steps may be changed, or a part of the steps may be deleted, added, or changed.

Next, the plastic working step S88 will be described. The workpiece (the external gear 14) is subjected to plastic working by the plastic working apparatus 80. The plastic working step S88 in this example is based on shot peening in which a medium such as a steel ball (sometimes referred to as shot peening) is accelerated by air pressure, centrifugal force, or the like and is ejected from a nozzle and blown against a work object.

In the plastic working step S88, the plastic working may be performed on the entire workpiece, or may be performed on a selected portion of the workpiece. In the present embodiment, the plastic working step S88 performs plastic working on the 1 st portion including the portion of the 1 st through-hole facing the 2 nd through-hole, and does not perform plastic working on the remaining 2 nd portion. In this case, the processing time can be shortened.

In the plastic working step S88, the medium may be ejected to the workpiece in a stationary state or may be ejected to the workpiece in a rotating state. In the present embodiment, the workpiece (external gear 14) is rotated and the medium is ejected from the fixed nozzle. In this case, the level of residual stress and the variation in deformation in the circumferential direction of the workpiece can be reduced.

In the plastic working step S88, shot peening may be performed only once or a plurality of times. In the present embodiment, the plastic working step S88 includes the 1 st step S88a of spraying the 1 st medium M1 (steel balls) to the workpiece (external gear 14) and the 2 nd step S88b of spraying the 2 nd medium M2 (steel balls) to the workpiece (external gear 14) that has received the spray of the 1 st medium M1. In this case, since a plurality of media having different processing characteristics can be used, a desired residual stress distribution can be easily obtained. The plastic working apparatus 80 can be used in the 1 st step S88a and the 2 nd step S88 b.

The sizes of the 1 st medium M1 and the 2 nd medium M2 may be the same or different. In the present embodiment, the size of the 1 st medium M1 and the size of the 2 nd medium M2 are different from each other. In this case, by using media having different sizes, a desired residual stress distribution can be easily obtained. In particular, the 1 st medium M1 is larger than the 2 nd medium M2.

The hardness of the 1 st medium M1 and that of the 2 nd medium M2 may be the same or different. In the present embodiment, the hardness of the 1 st medium M1 and the hardness of the 2 nd medium M2 are different from each other. In particular, the 2 nd medium M2 is harder than the 1 st medium M1.

In the plastic working step S88, plastic working may be performed on one workpiece alone, or plastic working may be performed by ejecting a medium in a state where a plurality of workpieces are stacked. If the machining is performed in an overlapping manner, the total machining time can be shortened.

In the plastic working step S88, the number of workpieces to be overlapped is not limited, but in the present embodiment, the 1 st medium M1 or the 2 nd medium M2 is ejected in a state where a plurality of (three in this example) workpieces (external gears 14) assembled to the same eccentric oscillating type reduction gear transmission 10 are overlapped. When plastic working is performed on a plurality of workpieces at different times or using different processing machines, the level or distribution of residual stress becomes inconsistent due to the difference in the processing machines or the times, and when the plastic working is performed on a plurality of workpieces stacked, the level or distribution of residual stress is easily made consistent. By making the residual stress distribution uniform, it is difficult for a problem such as cracking easily to occur in only a part of the plurality of workpieces, and it is also difficult for unevenness (unbalances) due to machining variations to occur.

Next, the plastic working apparatus 80 will be explained. The plastic working apparatus 80 includes a rotary table 82 and a nozzle 84 which are rotationally driven. Three workpieces (external gears 14) are mounted on the rotary table 82, and are rotationally driven in the direction of arrow R integrally with the rotary table 82. A cover member may be provided to cover a portion of the workpiece (external gear 14) where plastic working is not performed. In this example, a pin-shaped member 82p protruding from the rotary table 82 is inserted into the 2 nd through-hole 15 and functions as a cover member. The nozzle 84 is disposed toward the portion 13f of the 1 st portion 13 e. Therefore, the vicinity of the portion 13f is intensively plastic-worked, and the portion 13j of the 2 nd portion 13h is hardly plastic-worked. Further, a cover member covering the 2 nd portion 13h may be provided.

The nozzle 84 and the rotary table 82 may be configured to be relatively movable in the thickness direction of the workpiece, or may be configured to reciprocate relatively in the thickness direction of the workpiece while ejecting the medium. In this case, variations in the level or distribution of the residual stress in the thickness direction can be suppressed. The rotary table 82 may be continuously rotated or intermittently rotated while being repeatedly stopped and rotated according to the position of the 1 st through-hole 13.

The above is a description of embodiment 1. According to the eccentric rocking type reduction gear 10 of embodiment 1, it is possible to provide an eccentric rocking type reduction gear in which a decrease in durability can be suppressed even when the reduction in size is performed.

[ 2 nd embodiment ]

Next, the structure of the eccentric rocking type reduction gear unit 10 according to embodiment 2 will be described with reference to fig. 5 to 7. In the drawings and the description of embodiment 2, the same or equivalent constituent elements and components as those of embodiment 1 are denoted by the same reference numerals. Description of the structure different from embodiment 1 will be omitted as appropriate, and the description will be repeated. Fig. 5 is a side sectional view showing the eccentric rocking type reduction gear transmission 10 according to embodiment 2, which corresponds to fig. 1. Fig. 6 is a sectional view taken along line a-a of fig. 5.

The embodiment 1 has been described taking an eccentric rocking type reduction gear of a center crank type as an example. The eccentric oscillating type reduction gear of the present embodiment is a so-called distributed type eccentric oscillating type reduction gear. The eccentric oscillating type reduction gear 10 mainly includes an input gear 70, an input shaft 12, an external gear 14, an internal gear 16, a carrier 18, a carrier 20, a housing 22, a main bearing 24, and a main bearing 26. The present embodiment differs from embodiment 1 mainly in that a plurality of input gears 70 and input shafts 12 are provided and the number of external gears 14 and the through-holes of the external gears 14 are different.

The plurality of input gears 70 are disposed around a center axis L a of the internal gear 16, only one input gear 70 is shown in fig. 5, the input gear 70 is supported by the input shaft 12 inserted into a central portion thereof and is rotatable integrally with the input shaft 12, the input gear 70 is engaged with an external tooth portion of a rotating shaft (not shown) provided on the center axis L a, and rotational power is transmitted from a not-shown driving device to the rotating shaft, and the input gear 70 is rotated integrally with the input shaft 12 by rotation of the rotating shaft.

The input shaft 12 of the present embodiment is provided with a plurality of (for example, three) input shafts 12 spaced apart from each other in the circumferential direction at a position offset from the center axis L a of the ring gear 16. fig. 5 shows only one input shaft 12. two eccentric bodies 12a having eccentric phases shifted by 180 ° are axially arranged on each input shaft 12.

Two external gears 14 are assembled to the outer periphery of the eccentric body 12a via roller bearings 30. Each external gear 14 internally meshes with the internal gear 16. The structures of the external gears 14 are the same except for the eccentric phases.

Fig. 7 is a front view showing the external gear 14 of the present embodiment, which corresponds to fig. 2. The external gear 14 is provided with a 1 st through-hole 13 through which the inner pin 32 passes, a 2 nd through-hole 15 in contact with the roller bearing 30, and a 3 rd through-hole 17 provided in the center of the external gear 14. As shown in fig. 7, the 1 st through-hole 13 and the 2 nd through-hole 15 are provided at positions offset from the center of the external gear 14 and adjacent to each other in the circumferential direction.

The 1 st through hole 13 is provided in plural corresponding to the inner pin 32. In this example, three 1 st through-holes 13 are provided at intervals of 120 ° in the circumferential direction. The 1 st through hole 13 has a substantially triangular shape with rounded corners. As shown in fig. 6, the 1 st through hole 13 of the present embodiment is not in contact with the inner pin 32. That is, the inner pin 32 of embodiment 1 has a function of transmitting the rotation of the external gear 14 and a function of coupling the 1 st carrier 18 and the 2 nd carrier 20, while the inner pin 32 of embodiment 2 has a function of coupling the 1 st carrier 18 and the 2 nd carrier 20 but does not have a function of transmitting the rotation of the external gear 14. Therefore, the inner pin 32 of embodiment 2 is sometimes also referred to as a wheel carrier pin. The 2 nd through hole 15 is a circular hole into which the eccentric body 12a is inserted, and is provided in plural corresponding to the input shaft 12. In this example, three 2 nd through-holes 15 are provided at intervals of 120 ° in the circumferential direction.

The operation of the eccentric rocking type reduction gear transmission 10 of the present embodiment will be described. When the rotational power is transmitted from the driving device to the rotating shaft, the rotational power is distributed from the rotating shaft to the plurality of input gears 70, and the input gears 70 rotate in the same phase. When each input gear 70 rotates, the eccentric body 12a of the input shaft 12 rotates about the rotation center line passing through the input shaft 12, and the external gear 14 is oscillated by the eccentric body 12 a. When the external gear 14 oscillates, the meshing positions of the external gear 14 and the internal gear 16 are sequentially shifted, and one of the external gear 14 and the internal gear 16 rotates, as in embodiment 1. The rotation component of the external gear 14 is transmitted to the

carriers

18, 20 via the input shaft 12. The rotation of the input shaft 12 is decelerated at a reduction gear ratio corresponding to the difference in the number of teeth of the external gear 14 and the internal gear 16, and is output from the output member to the driven device.

In the present embodiment, when receiving a rolling element load from the eccentric body 12a, the stress distribution of the external gear 14 is compressive stress on the 2 nd through-hole 15 side receiving the load and tensile stress on the 1 st through-hole 13 side. Therefore, for example, a stress crack may be generated as indicated by reference sign D in fig. 7 starting from the 1 st through hole 13 side receiving the tensile stress. Therefore, in the external gear 14 of the present embodiment, plastic working is applied to a predetermined portion, and the influence of the tensile stress of the rolling element load is reduced by the compressive residual stress based on the working.

As shown in fig. 7, in the present embodiment, a 1 st portion 13e including an opposing portion 13f opposing the 2 nd through-hole 15 and subjected to plastic working is provided on an inner peripheral surface 13b of the 1 st through-hole 13. In this case, the occurrence of stress cracking due to the rolling element load can be suppressed by the compressive residual stress of the plastic working. In this example, the 1 st through-hole 13 is opposed to the 2 nd through-hole 15 on both sides in the circumferential direction, and therefore there are two opposed portions 13f separated in the circumferential direction. Therefore, the 1 st portion 13e is provided at two places corresponding to the two opposed portions 13 f. Each of the 1 st portions 13e may extend along the inner peripheral surface 13b toward both sides of the opposing portion 13 f. The two 1 st portions 13e may or may not be partially connected. The 1 st portions 13e may be provided continuously or intermittently.

As shown in fig. 7, in the present embodiment, the 2 nd portion 13h, which is not subjected to plastic working, is provided on the inner peripheral surface 13b of the 1 st through-hole 13. In this example, the 2 nd portion 13h includes a portion 13m opposed to the outer periphery of the external gear 14 and is provided on both sides thereof. The 2 nd portion 13h may be provided with a portion not subjected to plastic working in the vicinity of a portion 13n opposed to the 3 rd through hole 17 provided at the center of the external gear 14.

In the present embodiment, no plastic working is performed on the 2 nd through-hole 15 and the 3 rd through-hole 17.

The situation of the residual stress from the surface to the inside of the 1 st portion 13e in embodiment 2 is also the same as that in embodiment 1. The method S80 for manufacturing the external gear 14 described in embodiment 1 can also be applied to the external gear 14 of the present embodiment.

The above is a description of embodiment 2. According to the eccentric rocking type reduction gear 10 of embodiment 2, the same operational effects as those of embodiment 1 can be obtained, and an eccentric rocking type reduction gear in which a decrease in durability can be suppressed even when the reduction in size is performed can be provided.

The above description explains an example of the embodiment of the present invention in detail. The above embodiments are merely specific examples for carrying out the present invention. The contents of the embodiments do not limit the technical scope of the present invention, and various design changes such as changes, additions, deletions, and the like of the constituent elements can be made without departing from the scope of the inventive concept defined in the claims. In the above-described embodiments, the description has been given with reference to the contents in which such a design change is possible, such as "in the embodiment" and "in the embodiment", but the contents without such a mark do not mean that the design change is not permitted.

Hereinafter, a modified example will be described. In the drawings and the description of the modified examples, the same or equivalent constituent elements and components as those of the embodiment are denoted by the same reference numerals. The description overlapping with the embodiment is appropriately omitted, and the description is repeated for the structure different from that of embodiment 1.

In the description of embodiment 1, the plastic working performed on the outer gear 14 is shot peening, but the present invention is not limited to this. The plastic working performed on the external gear 14 may be, for example, knurling or plastic working by a method of pressing a hard tool. Further, the plastic working may be performed by combining a plurality of different plastic working methods.

In the description of embodiment 1, an example in which shot peening is performed twice is shown, but shot peening may be performed once or three or more times.

In the description of embodiment 1, an example in which the shot-peening medium is steel balls is shown, but shot-peening may be performed using known media of various types and shapes.

Although the description of embodiment 1 has shown an example in which one nozzle 84 is used, shot peening may be performed using a plurality of nozzles 84. For example, a plurality of nozzles 84 provided separately on both sides of the workpiece (external gear 14) in the axial direction may be used, or a plurality of nozzles 84 provided separately in the radial direction may be used.

Although the example in which three external gears 14 are provided in embodiment 1 and the example in which two external gears 14 are provided in embodiment 2 are described, one external gear 14 may be used or four or more external gears 14 may be used depending on desired characteristics.

In the description of embodiments 1 and 2, the hole through which the inner pin 32 passes is subjected to plastic working, but the inner peripheral surface of another through-hole adjacent to the through-hole receiving the rolling element load may be subjected to plastic working. For example, the inner peripheral surface of the 3 rd through-hole 17 of embodiment 2 may be subjected to plastic working.

In embodiment 1, an example in which the 1 st main bearing 24 and the 2 nd main bearing 26 do not have an inner ring is described, but the present invention is not limited to this. At least one of the 1 st main bearing 24 and the 2 nd main bearing 26 may be a bearing having an inner race.

In the above, an example in which the output member of the embodiment is the

carrier

18, 20 and the case 22 is fixed to the external member has been described. In addition, the output member may be the casing 22, and the

carrier

18, 20 may be fixed to an external member.

The above modifications also exhibit the same operational advantages as those of embodiment 1.

Any combination of the above-described embodiments and modifications is also effective as an embodiment of the present invention. The new embodiment which is produced by the combination has the effects of the combined embodiments and the modifications.

Claims

1. An eccentric oscillating type reduction gear device comprising an external gear, an eccentric body oscillating the external gear, and an internal gear internally meshing with the external gear, characterized in that,

the external gear has a 1 st through-hole and a 2 nd through-hole provided adjacent to the 1 st through-hole in a circumferential direction or a radial direction,

the inner peripheral surface of the 1 st through-hole has a 1 st portion which includes a portion facing the 2 nd through-hole and is subjected to plastic working.

2. The eccentric oscillating type reduction gear according to claim 1,

the inner peripheral surface of the 1 st through-hole has a 2 nd portion which is not subjected to plastic working.

3. The eccentric oscillating type reduction gear according to claim 1 or 2,

the 2 nd through-hole is a hole into which the eccentric body is inserted, and the 1 st through-hole is provided at a position offset from the center of the external gear and adjacent to the 2 nd through-hole in the radial direction.

4. The eccentric oscillating type reduction gear according to claim 1 or 2,

the 2 nd through-hole is a hole into which the eccentric body is inserted, the 1 st through-hole being provided at a position offset from the center of the external gear and adjacent to the 2 nd through-hole in the circumferential direction.

5. An eccentric oscillating type reduction gear device comprising an external gear, an eccentric body oscillating the external gear, and an internal gear internally meshing with the external gear, characterized in that,

the 1 st through-hole has, on an inner peripheral surface thereof: a 1 st portion including a portion opposed to the 2 nd through-hole and having a surface with a high compressive residual stress; and

and (2) a surface of which has a compressive residual stress that is greater than or equal to 1/5 times the compressive residual stress of the surface of the part 1.

6. The eccentric oscillating type reduction gear according to claim 3,

the compressive residual stress at 60 μm from the surface of the 1 st portion is higher than that of the surface.

7. A method of manufacturing an external gear that is oscillated by an eccentric body in an eccentric oscillating type reduction gear so as to be internally meshed with an internal gear, characterized in that,

the method for manufacturing the external gear includes a plastic working step of performing plastic working on an inner peripheral surface of the 1 st through hole.

8. The method of manufacturing an external gear according to claim 7,

in the plastic working step, the 1 st portion including a portion of the 1 st through-hole facing the 2 nd through-hole is subjected to plastic working, and the remaining 2 nd portion is not subjected to plastic working.

9. The method of manufacturing an external gear according to claim 7 or 8,

the plastic working is a working based on shot peening of a blasting medium,

in the plastic working process, the external gear is rotated and the medium is ejected from the fixed nozzle.

10. The method of manufacturing an external gear according to claim 7,

the plastic working process comprises the following steps:

a 1 st step of ejecting a 1 st medium to the external gear; and

a 2 nd step of ejecting a 2 nd medium to the external gear after the ejection of the 1 st medium is received,

the size of the 1 st medium and the size of the 2 nd medium are different from each other.

11. The method of manufacturing an external gear according to claim 10,

the 1 st medium is larger than the 2 nd medium.

12. The method of manufacturing an external gear according to claim 10 or 11,

the 2 nd media is harder than the 1 st media.

13. The method of manufacturing an external gear according to any one of claims 9 to 12,

in the plastic working step, the medium is injected in a state where the plurality of external gears are overlapped.

14. The method of manufacturing an external gear according to claim 13,

in the plastic working step, the medium is injected in a state where a plurality of external gears assembled to the same eccentric oscillating type speed reduction device are overlapped.