Stock material or miscellaneous articles – All metal or with adjacent metals – Composite; i.e. – plural – adjacent – spatially distinct metal...
Patent
1996-04-15
1998-06-23
Zimmerman, John J.
Stock material or miscellaneous articles
All metal or with adjacent metals
Composite; i.e., plural, adjacent, spatially distinct metal...
428469, 2281221, B32B 1504, C04B 3702, F01L 114, F01L 118
Patent
active
057703221
DESCRIPTION:
BRIEF SUMMARY
This application was filed under 35 U.S.C. 371 from International Application No. PCT/JP95/02311, filed Nov. 13, 1995.
TECHNICAL FIELD
The present invention relates to sliding components which are required to have wear resistance such as valve train parts, a cam follower, a rocker arm and a bearing of an automobile engine, especially those of a structure composed of a base metal and a ceramic sliding member joined together.
BACKGROUND ART
In recent years it has become of urgent necessity to strengthen the regulation on exhaust gas from automobiles from the viewpoint of global environmental issues. In particular, the reduction of the discharge of NO.sub.x (nitrogen oxides) and P/M (particulate matter) is being studied with respect to diesel engines. The reduction of NO.sub.x by attaching an exhaust gas recirculation (EGR) system to the engine exhaust system is being studied as a countermeasure. This has caused a problem such that the recirculation of exhaust gas components leads to chemical deterioration of the engine oil and introduction of P/M contaminating the oil, so that the engine sliding components would suffer from much wear.
Sliding component materials have been selected from the viewpoint of good wear resistance on the sliding face and low sliding resistance. A single material having excellent properties has been employed or a sliding member joined together has been prepared for practical utilization as a sliding component.
Attention has been drawn to ceramics having excellent sliding properties in recent years. Especially, examples of actual use are found in which a ceramic is joined to a metal material in a manner such that the ceramic is positioned in sliding parts where sliding conditions are severe.
For example, Japanese Patent Laid-Open No. 2-55809 disclosed a ceramic with excellent sliding properties being joined to a cam sliding part of an engine tappet as a countermeasure to the deterioration of lubrication conditions attributed to an increased engine horsepower and compliance with exhaust gas regulations.
Generally, mechanical sliding components each have a pair of sliding faces, one of which is not planar and has a protrudent crowning profile such that the center is slightly higher than the periphery (by about several microns to several tens of microns) in order to prevent eccentric tap.
This crowning profile is formed by, for example, machining (grinding), the process of Japanese Patent Laid-Open No. 63-289306 comprising clothing a ceramic with a metal and elastically deforming the ceramic with the clamping force of the metal, or the process of Jidosha Gijutsu (Automobile Technology), Vol. 39, No. 10, p1184 (1985) comprising previously working a tentatively sintered body into a crowning profile and conducting sintering to thereby directly use the sintered surface as a sliding face.
However, the crowning profile is three dimensional, so that the machining is costly.
In the clothing process, the extent of crowning is restricted depending on the structure, heating temperature, etc.
The process comprising previously working a tentatively sintered body into a crowning profile and conducting sintering to thereby directly use the sintered surface as a sliding face has encountered the problem that the sintering is accompanied by shrinkage which deforms the face worked into the crowning profile to thereby lower the dimensional accuracy thereof.
For example, Japanese Patent Laid-Open No. 63-225728 disclosed a process directed toward reduction of machining (grinding) cost in which a wear-resistant member having a coefficient of thermal expansion lower than that of the base metal to be joined is joined to the sliding face by heating and the sliding face is provided with the crowning profile by a difference in the coefficient of thermal expansion to thereby form the crowning without resort to machining such as grinding, so that a sliding component capable of preventing eccentric tap when subjected to sliding can be provided at a lowered cost. The above patent application specification further
REFERENCES:
patent: 5173458 (1992-12-01), Nishioka et al.
patent: 5394015 (1995-02-01), Tsuzuki et al.
patent: 5599493 (1997-02-01), Ito et al.
Complete translation of Japanese publication 6-92749, Futoshi Kuroda, Apr. 1994.
Complete translation of Japanese publication 63-225728, Shigeaki Akao et al., Sep. 1988.
Nishioka Takao
Satoh Takeshi
Takeuchi Hisao
Yamagiwa Masamichi
Yamakawa Akira
Sumitomo Electric Industries Ltd.
Zimmerman John J.
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