Method of manufacturing hollow member

Abstract

A washer is provided between two inner rings arranged in a row, and annular washers are disposed outside the inner rings in the axial direction of the inner ring, respectively. A bolt is inserted into the two inner rings so that a head part of the bolt comes in contact with the washer disposed outside one inner ring in the axial direction of the inner ring. A nut is fastened on an end of the bolt opposite to the head part, from the outside of the washer. The inside of the through holes of the inner rings is substantially completely isolated from the outside thereof. The inner rings of which the inside of the through holes is substantially completely isolated from the outside are exposed to a carburizing atmosphere at high temperature, so as to perform carburizing and quenching only on the outer surfaces of the inner rings.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a method of manufacturing a hollow member, such as an inner ring of a bearing, an outer ring of a bearing, or a rocker arm, and more particularly, to a method of manufacturing a hollow member that performs a heat treatment such as a surface hardening treatment (for example, carburizing, nitriding, or carbonitriding), etching, or film formation only on the outer surface of a hollow member. [0002] A method of manufacturing a hollow member in the related art is disclosed in JP-A-8-60335. According to the method of manufacturing a hollow member in the related art, an anti-carburizing material formed of a water glass or the like is applied on a portion of a hollow member where carburizing and quenching is not intended to be performed, for example, on the inner periphery of a hollow member, and then dried. Subsequently, the hollow member on which the anti-carburizing material is partially applied is exposed to a carburizi...

AI Technical Summary

Benefits of technology

[0006] Accordingly, it is an object of the invention to provide a method of manufacturing a hollow member that can perform a specific treatment only on the outer surface of a hollow member at relatively low cost and obtain a hollow member that has more various shapes and is made of more various materials.

[0014] According to the embodiment of the invention, a specific treatment is performed on the outer surfaces of the at least one hollow member by exposing one or more hollow members, of which the inside of the holes is isolated from the outside, to a treatment atmosphere. Therefore, it is possible to more simply and inexpensively perform the specific treatment on the outer surfaces of the at least one hollow member, as compared to a method of applying a treatment-prevention material (a material for preventing the occurrence of a specific treatment) on an inner periphery.

[0017] According to the embodiment of the invention, it is possible to improve the airtightness of the inner spaces of the at least one hollow members after the isolation step. Accordingly, in the outer surface treatment step, it is possible to reliably prevent the inner peripheries of one or more hollow member from being exposed to a specific atmosphere.

[0019] According to the embodiment of the invention, a coefficient of linear expansion of the washer is larger than that of any one of the hollow members, the insertion member, and the fastening member. Accordingly, when the outer surface treatment step is performed at high temperature after the isolation step, the washer is expanded more than the other members during the outer surface treatment step. For this reason, a pressing force of the washer against the end faces of the hollow members having a hole is significantly increased. As a result, it is possible to further improve the airtightness of the inner spaces of the hollow members.

[0021] According to the embodiment of the invention, at least one of a groove, a step, and a thread is formed on the inner periphery of at least one hollow member. For this reason, it is possible to more simply and inexpensively perform the specific treatment on the outer surfaces of the hollow members, as compared to a method of applying a treatment-prevention material on an inner periphery. Further, in the outer surface treatment step, it is possible to reliably prevent the toughness of at least one of the groove, the step, and the thread from deteriorating.

[0022] According to a method of manufacturing a hollow member of the invention, a specific treatment is performed on the outer surface of the at least one hollow member by exposing the at least one hollow member, of which the inside of the holes is isolated from the outside, to a treatment atmosphere. Accordingly, it is possible to simply and inexpensively perform the specific treatment on the outer surfaces of the at least one hollow member.

Problems solved by technology

However, according to the method of manufacturing a hollow member, it is difficult to distinguish a hollow member where an anti-carburizing material is applied from a hollow member where an anti-carburizing material is not applied.

Further, since the applied anti-carburizing material should be removed after the carburizing and quenching, there is a problem that a lot of man-hours (efforts) and time are required to manufacture a hollow member.

Further, according to the method of manufacturing a hollow member, when a groove or thread is formed on the inner periphery of the hollow member, it is difficult to apply the anti-carburizing material on the recesses of the groove or thread.

If the anti-carburizing material is not sufficiently applied on the recesses of the groove or thread, the toughness of the groove or thread deteriorates after the carburizing and quenching.

As a result, there is a problem that the groove or thread is easily damaged.

In addition, there is another problem that it is difficult to remove the anti-carburizing material applied on the groove or thread after the carburizing and quenching.

However, according to this method, a predetermined hardness is not obtained by high frequency heating in some materials, and cracks occur in the hollow member having a small thickness.

That is, there is another problem that the application of this method is limited to specific material or thickness of the hollow member.

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