Sliding component and production method thereof

Details Sliding component and production method thereof Sliding component and production method thereof

1996-09-19

1998-07-21

Yee, Deborah

Stock material or miscellaneous articles

All metal or with adjacent metals

Composite; i.e., plural, adjacent, spatially distinct metal...

148516, B32B 1800, B32B 1500, C21D 100

Patent

active

057833141

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to sliding components having a plurality of sliding faces, for which wear resistance is requisite, such as a tappet, a rocker arm and other engine components, bearings, and so forth, and a production method of such sliding components.


BACKGROUND ART

In order to prevent uneven contact due to poor alignment, one of a pair of sliding faces of a mechanical sliding component generally is not a flat face but has a convexed crowning shape such that its center portion is slightly higher than its outer edge portion (by several to dozens of microns).
This crowning shape is formed by various methods such as machining (polishing), a method described in Japanese Patent Laid-Open No. 63-289306 which fits metal over ceramic so as to cause elastic deformation of the ceramic by its fastening force, a method described in Japanese Patent Laid-Open No. 63-225728 which heats and joins ceramic that form a sliding face to a metal as a main body and utilizes the difference of their thermal expansion coefficients, and a method which shapes in advance a calcined body into a crowning shape, then sinters this calcined body and Technology", Vol. 39, No. 10, (1985) p1184!, and so forth.
However, since the crowning shape is a three-dimensional shape, formation of this shape by machining requires an enormous cost of production.
According to the method which fits metal over ceramic or the method which utilizes the difference of thermal expansion coefficients between ceramic and metal, the crowning quantity is limited once the structure, the heating temperature, etc, are decided.
On the other hand, the method which shapes in advance the calcined body into the crowning shape, then sinters it and utilizes the as-sintered face as the sliding face is not free from the problem that the face shaped into the crowning shape undergoes deformation due to shrinkage at the time of sintering, and dimensional accuracy drops.
In view of the problems of the prior art described above, the present invention aims at providing a sliding component having improved utility and a method of producing such a sliding component.


DISCLOSURE OF THE INVENTION

The sliding components provided by the present invention for accomplishing the object described above are as follows: a crowning shape by applying partially surface quenching treatment to a portion made of a steel; or machining of a steel portion conducted after the surface quenching; and of crowning by surface quenching described above is formed by joining or fitting.
The methods of producing the sliding components described above are as follows: portion, constituted by a steel, of a sliding component main body in order to shape a sliding face into a crowning shape; so as to change the crowning quantity after the surface quenching; and sliding component main body.
It is more preferred to use ceramics for the member for forming the sliding face which is formed by joining or fitting.


MODE OF OPERATION

In the sliding component according to the present invention, the crowning shape is formed on the sliding face of at least one portion by partially applying surface quenching to a steel which constitutes the sliding component and is hardenable.
In other words, deformation is partially generated by utilizing volume expansion due to martensitic transformation or so-called quenching distortion at the time of surface quenching, and the crowning shape is imparted to at least one arbitrary sliding face in the sliding component.
The portion to which surface quenching is applied is appropriately selected in accordance with the position of the sliding face to which crowning is imparted, or with the crowning quantity. Crowning by surface quenching is imparted by utilizing the phenomenon described above. Accordingly, it is more efficient to apply surface quenching to the portion or portions near the joined portion or portions in a broader range. Incidentally, the total surface area of surface quenched is preferably at least 30% of the surface area as the difference obtained by subtr

REFERENCES:
PCT/ISA/210 Jul. 1992.

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