| 摘要 |
PROBLEM TO BE SOLVED: To improve the dimensional accuracy of products by setting the temperature of an inner mold lower than that of the outer mold within a specific temperature range at the time of injection, when a cylindrical sliding member is manufactured by injecting polyphenylene sulfide resin. with carbon fiber added into a cavity between the inner and outer mold. SOLUTION: A cylindrical sliding member 1 used as a spool valve body for a control valve of the hydraulic controlling device for the automatic transmission of vehicles is formed by injection molding in a cylindrical shape with a bottom being closed at one end thereof and is provided with an annular recessed section 2 on the periphery at the middle along the axial direction thereof. Though the cylindrical sliding member is manufactured by injecting polyphenylene resins added with carbon fiber into a cavity between an inner and outer mold, the temperature of the inner mold is set lower within a rang of 10-40 deg.C than that of the outer mold at the time of injection. Consequently, the heat radiating volume to both the outer and inner mold are equalized; which results in keeping both the difference in the shrinking speed and the strain between the inner and outer surface of the sleeve shape sliding member 1 and improving the dimensional accuracy of the injection molding products. |
