| 摘要 |
PROBLEM TO BE SOLVED: To provide a piston and a buffer capable of being manufactured at low cost.SOLUTION: In this invention, the cross sectional shape of a port 16 of a piston 2 is a square round rectangular shape so that arcs of both ends are arranged on the same circumference. Consequently, a mold 34 molding the port 16 used in sintering the piston 2 can be easily manufactured at low cost. As the result, since the mold 34 is inexpensive, the piston 2 and a buffer D can be manufactured at low cost.SELECTED DRAWING: Figure 3 |
