Method of manufacturing a rigid internal gear of a wave gear device

Abstract

A rigid internal gear 2 of the wave gear device is composed by integrating a tooth-forming ring 12 formed with internal teeth, and a main gear ring 11 into a single body. The tooth-forming ring 12 is manufactured from a ferrous or copper material that has superior strength and abrasion resistance, while the main gear ring 11 is manufactured from a lightweight material, such as an aluminum alloy. The outer circumferential surface of the tooth-forming ring 12 is aluminized to form a dispersed aluminum coating 15, before the tooth-forming ring 12 is cast within the main gear ring 11 so as to integrate the main gear ring 11 and the tooth-forming ring 12. Both parts are reliably integrated so that a large amount of torque can be transmitted, whereby realizing a rigid internal gear that is lighter than conventional models.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to a method of manufacturing a rigid internal gear of a wave gear device and to a rigid internal gear manufactured by this method of manufacturing. In more detail, the present invention pertains to a method of manufacturing a rigid internal gear that is made lighter with no loss in strength, abrasion resistance, etc., and to such a rigid internal gear.[0003] 2. Related Art[0004] A typical wave gear device includes a circular rigid internal gear, a cup-shaped flexible external gear disposed inside the rigid internal gear, and a wave generator fitted into the flexible external gear. The wave generator normally has an elliptical outline, and the flexible external gear is flexed elliptically so that the flexible external teeth on its outer circumferential surface are partially meshed with the internal teeth of the rigid internal gear. When the wave generator is rotated by a motor or the like, the engaging portions of b...

AI Technical Summary

Benefits of technology

[0019] With the method of manufacturing of the present invention, the pressure caused by the pressing in and the pressure caused by the difference in the linear expansion coefficients provide the pressing force at the bonding interface that is required for diffusion bonding. As a result, the two rings can be strongly integrated.

[0020] With the present invention, the pressing force that is generated at the bonding surface of the two rings when the tooth-forming ring is pressed in may be increased by making an inner circumferential surface of the main gear ring tapered, making an outer circumferential surface of the tooth-forming ring tapered so that the tooth-forming ring can be pressed into the tapered inner circumferential surface of the main gear ring, and pressing the tooth-forming ring into the inner circumferential surface of the main gear ring and diffusion-bonding the tooth-forming ring and the main gear ring together.

[0021] With the above method, the pressure that acts on the bonding surfaces of the rings during diffusion bonding can be increased, so that the two rings can be reliably bonded and integrated.

[0022] Note that it is preferable for the process that cuts the internal teeth in the tooth-forming ring to be performed after the tooth-forming ring has been integrated with the main gear ring, since this makes it possible to form the teeth accurately.

[0026] With the present invention, the tooth-forming ring cuts into the main gear ring as it is pressed into the main gear ring, so that the bonding strength of the rings can be increased.

[0027] Note that it is preferable for the process that cuts the internal teeth in the tooth-forming ring to be performed after the tooth-forming ring has been integrated with the main gear ring. By doing so, the internal teeth can be accurately formed.

Problems solved by technology

As a result, the rigid internal gear accounts for a large proportion of the weight of the components of the wave gear device.

In particular, in cases where an attachment flange for attaching a motor or an output-side member is integrally formed or a housing is integrally formed, the device becomes considerably heavy, so that the advantages of a wave gear device being lightweight are lost.

When the rings are joined in this way, it is necessary to manufacture the main gear ring and the tooth-forming ring as thick members, so that it is difficult to achieve weight reductions.

Since the rings are attached using bolts or the like, there is also a corresponding increase in weight due to such fixings.

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