| 摘要 |
PROBLEM TO BE SOLVED: To hold the sliding surfaces of a piston rod and sealing member in between in an always lubricated condition even in case a nitride film and oxide film are formed on the periphery of the piston rod. SOLUTION: A nitride film is formed on the outside surface of a metal member as a base for a piston rod 4, and thereon an oxide film 7 is formed. The surface of this oxide film 7 is over the whole length subjected to a buff polishing process in the circumferential direction, and thereby a number of transverse grooves 8 are formed in the film 7. This is subjected to an axial direction buff polishing process approx. over the whole length, and thereby a number of longitudinal grooves 9 are formed. |
