METHOD FOR INJECTION-MOLDING RESIN RING

摘要

PROBLEM TO BE SOLVED: To provide a method for injection-molding a resin ring capable of suppressing the lowering of the strength of a weld part and capable of inexpensively manufacturing the resin ring of high precision. SOLUTION: In the method for manufacturing the resin ring, a molten resin is injected in an annular cavity 19 formed in a mold 21 from the resin injection gate 10 provided to the peripheral edge of the annular cavity 19 to injection- mold a plastic seal 20 for a bearing. A resin sump 23 in which a part of the molten resin can flow is provided to the peripheral edge shifted from a weld part P2 of the ring-shaped cavity 19. The communication part 27 for allowing the resin sump 23 to communicate with the annular cavity 19 restricts the inflow amount of the molten resin flowing in the resin sump 23 from the annular cavity 19 to fill the resin sump 23 with the molten resin after the resin is charged in the annular cavity 19.