| 摘要 |
PURPOSE:To strengthen the head of a piston and improve the heat resistant strength by constituting the head of a piston and a part around a top ring groove with a specific perlite family organization and the rest with a vermicular graphite. CONSTITUTION:When casting a piston, a core 2 having a specific shape is installed in a mold 1. A cooling member 3 which is desinged to accelerate a cooling speed after casting, is installed to a place applied to the head A of a piston. Under this consition, melted metal is flown into the mold as usual and then cast. The presence of the cooling member 3 produces a tight perlife family organization having rapidly cooled-fine spherelike graphite in the piston head A and around the top ring groove. The rest is turned to be a vermicular graphite organization accompanied with ferrite. Care must be exercised not to crystalline free-state cement. As a cooling member, zirconic sand, sand with steel shot and cooling metal are used. |
