Nippon Piston Ring Co., Ltd.

Shinichi Yamamoto

Teruo Takahashi

Yoshikatsu Nakamura

Osamu Kawamura

A camshaft made of cast iron containing at least one element selected from the group consisting of Bi, Te, Se, As, Sb and Sn in a total amount of 0.0001 to 0.1 weight %, preferably, 0.001 to 0.1 weight %. The cast iron may further contain at least one elements selected from the group consisting of Ni, Cu and Co in an amount of 0.2 to 5.0 weight %. Furthermore, in the camshaft of the present invention, a carbide area ratio at the sliding surface of the cam lobe portion is not less than 40%, the chilled carbide has an average grain diameter of not more than 15 .mu.m, and the sliding surface of the cam lobe portion has a hardness of not less than HRC 53.

Method of manufacturing a camshaft

A camshaft made of cast iron containing at least one element selected from the group consisting of Bi, Te, Se, As, Sb and Sn in a total amount of 0.0001 to 0.1 weight %, preferably, 0.001 to 0.1 weight %. The cast iron may further contain at least one element selected from the group consisting of Ni, Cu and Co, in an amount of 0.2 to 5.0 weight %. Furthermore, in the camshaft of the present invention, a carbide area ratio at the sliding surface of the cam lobe portion is not less than 40%, the chilled carbide has an average grain diameter of not more than 15 .mu.m, and the sliding surface of the cam lobe portion has a hardness of not less than HRC 53.

Growing community of inventors

Tochigi-ken, Japan

Shinichi Yamamoto