| 摘要 |
PURPOSE: To provide a manufacturing method for forming a piston-body member into a shape by which its weight can be reduced. CONSTITUTION: With the body member 162 of a single-head piston manufacturing raw material, the bottom face 176 of a head body forming part 170 is formed three dimensionally and nonaxisymmetrically with respect to a center line of the head body forming part 170. Concretely, a recessed part 178 detented to the arm part 188 side from other of the bottom face 176, is formed in a position located on the base part side of an engaging part forming part 166 of the bottom face 176. A metal mold device for casting the body member 162 is provided with a pair of metal molds which can be opened and closed, and a slide core 220 which can be advanced and retracted in the direction parallel to the center line of the head body forming part 170, in the metal mold cavity. The slide core 220 has a shape which corresponds to the internal space of the head body forming part 170, and has a projected part 252 projected from other part in the tip face 246. Further, a squeeze member 260 is concentrically provided in the slide core 220. Semi-fluidized molten metal supplied is forced in a cavity 224 formed between the metal mold and the slide core 220 to eliminate blow holes on the engaging part forming part 166 side. |
