| 摘要 |
<P>PROBLEM TO BE SOLVED: To manufacture a piston for a swash type compressor having a hollow head part at low cost. <P>SOLUTION: A piston stock 160 for manufacturing a piston 14 is manufactured by a pore-free die casting method in a die cast step S12. A core manufactured in a core casting step S10 is positioned in a cavity of a die by a positioning support member. The core forms an internal space of the head part of the piston stock 160. The molten metal in the finely atomized condition is ejected into the cavity by forming an opening part on the cavity side of a runner to be a gate of the diameter smaller than that of other parts. The gate is opened at a plurality of parts which are not interfered by the surface of the core in the cavity. A circumferential wall of the head part of the piston stock 160 can be thin-walled while satisfying the required strength. A through hole is formed in the circumferential wall of the head part after the positioning support member is detached from the piston stock 160. Then, a heat treatment step S14 and a low melting point material flowing-out step are performed at the same time, the characteristic of the material of the piston stock 160 is improved, and the core material in the head part is melted and allowed to flow out of the through hole. <P>COPYRIGHT: (C)2003,JPO |
