MOLDING METHOD FOR BOSS SECTION OF RESIN MOLDED PRODUCT

PURPOSE:To mold simply a product of high quality appearance without surface sink without manufacturing a mold of a design in which the shape and wall thickness of a boss section are taken into consideration and without using an exclusive molding machine for injection compression molding or the like, either, by pressurizing the bottom section of a boss opening of the boss section with pressurizing fluid from the back side. CONSTITUTION:An opening 6 to be opened in a cavity section 3 between both forces 1 and 2 is bored in the bottom force 2 for the purpose of forming a boss section 5 integrally in a product, and a cylindrical mold 7 with projected section for the boss is fitted upward in the lower section of the opening 6. A passage 12 leading to around an end 11 of a boss pin section 9 is bored in the mold 7 for the boss in which a boss opening 8 of closed-end shape by the boss pin section 9, a small diameter section of said mold 7 for the boss. A recessed section 15 is formed at the bottom of the boss opening 8 by passing compressed air through a line 13 and jetting out of micro-pores 14 through after filling resin material 4 into the cavity section 3 and a surplus wall of a base of the boss section 5 is undercut to reduce the variation of wall thickness between the base of the boss section 5 and other flat sections.