| 摘要 |
Provided is a method for manufacturing a piston with which the holes on the upper surface of a low thermal conductivity member (a porous member) provided on the crest surface of a piston can be sealed effectively. The flat tip-end surface 44a of a rotary tool 44 of a frictional hole sealing device is brought into contact with an upper surface 5a of a low thermal conductivity member 5 cast on a crest surface 2a of an aluminum alloy piston 1, and is pressed against the upper surface, thereby applying a load on the low thermal conductivity member side while rotating this rotary tool by means of an electric motor or a speed reduction mechanism. Thus, a plastic flow layer 5d is formed on the upper surface of the low thermal conductivity member by means of frictional heat between the upper surface and the tip-end surface of the rotary tool, thereby sealing the apertures of the holes 9a in the upper surface of the porous member 6. |
