PURPOSE: To form recessions and projections each having a suitable contour on the inner peripheral surface of each of iron valves, and thereafter pouring a molten nonferrous metal therein thereby to obtain a slide surface of casting faults and excellent in mechanical and physical properties.
CONSTITUTION: A recessed and projected part 1a having a suitable contour in the peripheral direction, such as a triangle or a semi-circle in cross section, is provided on the inner peripheral surface of an iron valve 1. Then, a molten nonferrous metal 2 is poured in the valve 1, and deposited. After hardening said valve, the inner part thereof is subjected to a cutting operation to make the valve have a predetermined thickness to form a slide surface 2a, whereby casting cracks are prevented and defects such as shrinkage cavities are eliminated.
KUWANO SHIYUNICHI
IWASAKI KENJI
HITACHI CONSTRUCTION MACHINERY