TWM635556U - Strain wave gearing device - Google Patents

Abstract

[Problem] It is necessary to provide a harmonic gear unit that does not cause deformation or loosening of the bolt fastened portion. [Solution] The harmonic gear device (1) has: a rigid internal gear (2), a flexible external gear (3), a harmonic generator (4), and a relatively rotatable support The cross roller bearing (5) of the internal gear (2) and the external gear (3). A bolt seating surface (25) is formed on an annular end surface (23) of the internally toothed gear (2), and one end of a bolt through hole (21a) is opened on the bolt seating surface (25). The bolt seating surface (25) is subjected to quenching treatment so that it becomes a quenched surface having a hardness higher than the material hardness of the surface portion adjacent to the bolt seating surface (25). By performing quenching treatment on the bolt seat surface (25), it is possible to prevent or restrain the bolt seat surface (25) from being dented or deformed when the bolt is tightened.

Description

Harmonic gearing

The present invention relates to a harmonic gear device, and more specifically relates to a harmonic gear device in which its component parts, that is, rigid gears and flexible gears, are fixed to other parts by fastening bolts.

The known harmonic gear device includes: a rigid internal gear, a flexible external gear, a harmonic generator, and a bearing that supports the internal gear and the external gear in a relatively rotatable state; The above-mentioned harmonic generator bends the external gear into an ellipse to partially mesh with the internal gear, and moves the meshing position of the two gears in the circumferential direction. For example, the inner wheel of the bearing is coaxially fastened to the internal gear with bolts, and the outer wheel is coaxially fastened to the external gear with bolts. A harmonic gear device including such a bearing is described in Patent Documents 1 and 2, for example. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 9-250608 [Patent Document 2] Japanese Patent Application Laid-Open No. 9-303496

[Problems to be solved by the new model]

When bolts are used to fasten the components of the harmonic gear unit to other parts, if the tightening force acting on the bolt seat surface causes the bolt seat surface to be dented or deformed, it will cause deterioration of the assembly accuracy of the parts. And there may be looseness and play in the fastening parts. It is not appropriate to increase the number of bolts to reduce the force applied to the bolt seating surface because it goes against the demands for miniaturization, weight reduction, and cost reduction of the harmonic gear unit.

In view of this, the purpose of the present invention is to provide a harmonic gear device without deformation or loosening of the bolt fastening part. [Means to solve the problem]

In order to solve the above-mentioned problems, the harmonic gear device of the present invention is equipped with: a rigid gear, a flexible gear that can mesh with the rigid gear, and a harmonic generator; the above-mentioned harmonic generator makes the flexible gear radially Deflection and partial meshing with the rigid gear, so that the meshing position of the flexible gear relative to the rigid gear moves in the circumferential direction; it is characterized by: a rigid gear or a flexible gear, with: formed for fastening with other parts A bolt through hole and a bolt seat surface surrounding one opening of the bolt through hole, wherein the bolt seat surface is a quenched surface having a hardness higher than that of a surface adjacent to the bolt seat surface.

For example, the rigid gear is an internal gear, and the flexible gear is an external gear arranged coaxially inside the internal gear. The bolt through holes extend through one of the internally toothed gear and the externally toothed gear in the axial direction, and are formed at constant angular intervals in the circumferential direction. The quenched surface, that is, the bolt seat surface, is formed to surround the opening of the bolt through hole located on one of the end surfaces of the gear in the axial direction.

For example, the harmonic gear device has: a bearing and a plurality of fastening bolts; the above-mentioned bearing supports the internal gear and the external gear in a relatively rotatable state; the above-mentioned multiple fastening bolts connect the inner wheel and the outer wheel of the bearing One of the track wheels and one of the internally toothed gear and the externally toothed gear are fastened coaxially. The gear and the track wheel are coaxially fastened by fastening bolts attached to the bolt through holes from one end surface side of the gear. [New Effect]

In the harmonic gear device of the present invention, the surface part of the rigid gear or the flexible gear is subjected to quenching treatment, and the part of the bolt seat surface is made into a quenched surface with a hardness higher than that of other surface parts. Thereby, it is possible to prevent or suppress depression and deformation of the bolt seat surface when the bolt is fastened.

Embodiments of the harmonic gear device to which the present invention is applied will be described below with reference to the drawings. Embodiment shown below shows an example of this invention, and does not intend to limit this invention to embodiment.

The harmonic gear device 1 of the present embodiment, as shown in FIG. . The inner gear 2 and the inner ring 51 of the crossed roller bearing 5 are fastened coaxially by a plurality of bolts 6 . Similarly, the externally toothed gear 3 and the outer ring 52 of the crossed roller bearing 5 are fastened coaxially by a plurality of bolts 7 .

Referring to FIG. 2 for illustration, the internal gear 2 is made into a ring shape, and bolt through holes 21a, 21b are formed at equal angular intervals along the circumferential direction. One of the annular end surfaces 22 and the other annular end surface 23 in the direction of the axis 1a. The four bolt through holes 21a at angular positions at intervals of 90° are insertion holes for the bolts 6 for fastening the internal gear 2 and the inner ring 51, and the inner ring 51 side corresponds to the bolt through holes 21a. A threaded hole 51a is formed at the position. The remaining bolt through holes 21b are bolt through holes for fastening the inner ring 51 and the internal gear 2 to other members not shown (fixed-side device case or load-side member for output deceleration rotation).

Counterbore portions 24 are formed at angular intervals of 90° in the circumferential direction on the annular end surface 23 of the internally toothed gear 2 . A portion of the bottom surface of each counterbore portion 24 serves as a bolt seating surface 25 . One end of the bolt insertion hole 21 a is opened at the center portion of the bolt seat surface 25 . The bolt seating surface 25 is quenched to become a quenched surface. The bolt seat surface 25 has a higher hardness than the material hardness of the internal gear 2 other than the bolt seat surface 25 .

By partially quenching the portion of the internal gear 2 where the bolt seating surface 25 is formed, a required hardness is applied to the bolt seating surface 25 , thereby suppressing dents and deformation caused by bolt tightening. Thereby, the inner wheel 51 and the internal gear 2 can be assembled coaxially with high precision. As quenching, laser quenching or induction quenching can be used. The degree of hardness of the bolt seat surface 25 can be appropriately set according to the pressing force applied to the bolt seat surface 25 when the bolt is tightened to obtain a required bolt tightening force.

On the other hand, the externally toothed gear 3, as shown in FIG. The boss portion 33 is formed as an annular rigid body on the outer peripheral portion of the diaphragm 32 . External teeth 30 are formed on the outer peripheral surface portion of the front end side of the cylindrical body portion 31 . The external gear 3 is arranged coaxially inside the internal gear 2 , with the external teeth 30 facing the internal teeth 20 of the internal gear 2 .

The hub portion 33 , which is the rigid part of the externally toothed gear 3 , and the outer ring 52 of the crossed roller bearing 5 are fastened coaxially by bolts 7 . Bolt through holes 34 extending in the axial direction are formed at four positions of the hub portion 33 at angular intervals of 90° along the circumferential direction. Screw holes 52 a are formed at positions corresponding to the bolt through holes 34 of the outer ring 52 . The hub portion 33 and the outer ring 52 are formed with bolt through holes 35, 52b penetrating and extending in the direction of the axis 1a, and these bolt through holes 35, 52b are formed at constant angular intervals along the circumferential direction. These bolt through holes 35 and 52b are used to fasten the hub portion 33 and the outer ring 52 to other members not shown (fixed-side device case or load-side member for output deceleration rotation).

On one of the annular end surfaces 33 a of the boss portion 33 , the position of the head of the bolt 6 is an end surface portion serving as a bolt seating surface. The end surface portion may be partially subjected to quenching treatment to form a quenched surface, thereby forming a portion having a hardness higher than that of other materials.

(Other implementations) In the above example, the present invention can also be applied to a flat-top type harmonic gear device. The present invention is also applicable to a cup-shaped harmonic gear device with a cup-shaped external tooth gear, and a flat harmonic gear device with two inner-toothed gears and a cylindrical external-toothed gear. Moreover, the present invention is also applicable to a harmonic gear device, and has: a rigid external gear, a flexible internal gear coaxially surrounding the external gear, and a flexible internal gear that deflects the internal gear from the outer peripheral side toward the radial direction. and a harmonic generator that meshes with externally toothed gears.

1: Harmonic gear device 1a: axis 2: Internal gear 3: External gear 4: Harmonic generator 5: Cross roller bearing 6: Bolt 7: Bolt 20: Internal teeth 21a, 21b: Bolt through holes 22,23: Circular end face 24: counterbore part 25: bolt seating surface 30: External teeth 31: Cylindrical body 32: Diaphragm 33: Hub 33a: circular end face 34,35: bolt through hole 51: inner wheel 51a: threaded hole 52: outer wheel 52a: threaded hole 52b: Bolt through hole

[FIG. 1(a)] is an explanatory diagram showing a cross-sectional structure of a harmonic gear device to which the present invention is applied, [FIG. 1(b)] is an explanatory diagram showing an end face viewed from one of the axial directions, and [FIG. 1( c)] is an explanatory diagram showing an end face viewed from the other side in the axial direction. [Fig. 2(a)] is a vertical cross-sectional view of the internal gear, [Fig. 2(b)] is an end view of the internal gear, and the portion of the bolt seating surface is shown by a dot pattern.

1: Harmonic gear device

1a: axis

2: Internal gear

3: External gear

4: Harmonic generator

5: Cross roller bearing

6: Bolt

7: Bolt

20: Internal teeth

21a, 21b: Bolt through holes

22,23: Circular end face

24: counterbore part

25: bolt seating surface

30: External teeth

31: Cylindrical body

32: Diaphragm

33: Hub

33a: circular end face

34,35: bolt through hole

51: inner wheel

51a: threaded hole

52: outer wheel

52a: threaded hole

52b: Bolt through hole

Claims (3)

A harmonic gear device, comprising: a rigid gear, a flexible gear capable of meshing with the rigid gear, and a harmonic generator; The above-mentioned harmonic wave generator makes the above-mentioned flexible gear flex in the radial direction and partially meshes with the above-mentioned rigid gear, so that the meshing position of the above-mentioned flexible gear with respect to the above-mentioned rigid gear moves in the circumferential direction; its characteristics are: The above-mentioned rigid gear or the above-mentioned flexible gear has: a bolt through hole for fastening with other parts is formed, and a bolt seat surface surrounding one of the openings of the bolt through hole, The bolt seat surface is a quenched surface and has a hardness higher than that of a surface portion adjacent to the bolt seat surface. The harmonic gear device according to claim 1, wherein the above-mentioned rigid gear is a ring-shaped internal tooth gear, The flexible gear is an externally toothed gear arranged coaxially inside the internally toothed gear; The bolt through holes extend through one of the internal gear and the external gear in the axial direction, and are formed at regular angular intervals in the circumferential direction; The quenched surface, that is, the bolt seat surface, is formed to surround an opening of the bolt through hole that is opened on one end surface of the gear in the axial direction. Such as the harmonic gear device of claim 2, wherein, it is equipped with: bearings and multiple fastening bolts; The bearing supports the internal gear and the external gear in a relatively rotatable state; The above-mentioned plurality of fastening bolts fasten the track wheel of one of the inner wheel and the outer wheel of the above-mentioned bearing, and the above-mentioned gear; The gear and the track wheel are coaxially fastened by the fastening bolt attached to the bolt through hole from the end surface side.

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