Fuji Oozx Inc.

Masahito Hirose

Hiroaki Asanuma

Yuji Takano

Ryousuke Hada

Kazufumi Nakamura

A rod material made of Ti alloy has a larger diameter portion at the end, which is joined with the end of material made of Ti&mdash;Al intermetallic compound, by friction welding, to form a poppet valve for an internal combustion engine. Instead of providing such larger diameter portion, the end of the material made of Ti&mdash;Al intermetallic compound may be heated to facilitate joining.

Method of joining different metal materials by friction welding

A Ti alloy poppet valve consists of a valve stem and a valve head, and is employed as intake or exhaust valve in an internal combustion engine of an automobile. O is put into the valve in a furnace at very slight amount and heated to introduce oxygen atoms into titanium of the valve to form a Ti&mdash;O interstitial solid solution without making titanium oxides. The valve is strengthened to increase hardness and wear resistance.

Ti alloy poppet valve and a method of manufacturing the same

Ti alloy is embedded in a powder such as graphite and heated with the powder in an oxygen atmosphere. Oxygen atoms are diffused into the Ti alloy to form an oxygen diffusion layer of Ti&mdash;O solid solution, thereby increasing wear resistance of the valve. A poppet valve in an internal combustion engine may be made of such Ti alloy.

Ti alloy surface treatment

A poppet valve in an internal combustion engine of a vehicle consists of a valve body which comprises a valve stem and a valve head at one end of the valve stem. An oxidized layer is formed on portions of the valve body which contacts another valve-operating member. On the oxidized layer, a carburized layer is formed to cover the whole surface to increase wear resistance and fatigue strength of the valve.

Ti alloy poppet valve and surface treatment thereof

To manufacture a tappet in an internal combustion engine, a tappet rough body which comprises a cylindrical portion with an upper wall and an annular side wall is moulded by press processing of metal powder, such that the upper wall, the cylindrical portion and the annular side wall become larger than the tappet to be manufactured in the axial size. After sintering the tappet rough body, it is re-compressed to form the final tappet.

Method of forming a tappet in an internal combustion engine

A tappet in a direct acting type valve operating mechanism of an internal combustion engine comprises a top wall and a cylindrical portion. The upper and lower surfaces of the top wall contacts a rotary cam and the end of a stem of an engine valve respectively. A hard metal layer is formed at the upper and lower surfaces of the top wall to increase strength thereof, thereby increasing wear resistance and durability of the tappet.

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Hayama-machi, Japan

Masahito Hirose