| 摘要 |
PURPOSE:To improve size stability in oil by a method wherein insert molding in which specified wt% polyphenylene sulfide resin, fluororesin, a spherical filler, and a fibrous filler are an essential composition is applied on the outer peripheral part of a piston. CONSTITUTION:Polyphenylene sulfide resin is crystalline wear resisting thermoplastic resin prepared by alternately coupling a benzene ring and sulfur and is 60-80 wt%. 10-30 wt%, based on a total amount of a resin composition, fluorine resin is added. 2-10 wt%, based on a total amount of a resin composition, a spherical filler, e.g. silicon, is added. 2-10 wt%, based on a total amount of a resin composition, a fibrous filler, e.g. glass fibers, is added. A peripheral groove is preformed in, for example, the outer peripheral part of a body 2 in a manner that a section forms a protrusion part 21. Additives are mixed in a resin composition to mold an insert, and in a piston ring, two lines of peripheral recessed parts 31 and 32 are formed by molding shrinkage. |
