| 摘要 |
PURPOSE:To keep a surface layer from being deformed in the projecting direc tion during use under heating by forming the surface layer by chilled cast iron or the like and forming an inner layer by material having a coefficient of ther mal expansion lower than that of the cast iron or the like. CONSTITUTION:Chilled cast iron fused at a high temperature is poured into a cylindrical case rotating at high speed to form a surface layer 1, and subse quently material having a coefficient of thermal expansion lower than that of the fused chilled cast iron is similarly poured into the case to form an inner layer 2 on the inner surface of the surface layer 1. Accordingly, during use under heating, a very small recessed deformation as shown by a dotted line 3 is caused at a portion which is not uniform in thickness to avoid projecting deformation due to thermal expansion of the inner layer.
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