PLASTIC INJECTION MOLDING APPARATUS

摘要

PURPOSE:To provide the titled apparatus for mechanically preventing the sink mark of a thick part such as a boss or rib part, constituted by providing a space adjusting body which is moved in a cavity to increase or decrease the sapace thereof and an elastomer for energizing elastic force corresponding to the injection or contraction of resin to said space adjusting body. CONSTITUTION:The cavity 3 formed by a fixed side mold plate 1 and a movable side mold plate 2 shows an example for molding a molded product to which a plate part 41, a rib 42 extending from the plate part at right angles and a boss 43 provided at a spaced apart position are integrally formed. A frame body 5 is provided so as to be embedded in the movable side mold plate 2 in close vicinity to the rib 42 and the boss 43 and an operation block 6 is provided in said frame body 5. The operation block 6 is moved upwardly and downwardly in the inlay orifice 5a thereof to adjust the volume of the cavity 3. A spring 7 for pressing the operation block 6 is provided to the rear surface side of the operation block 6 and energizes pressing force to the direction moving the operation block 6 to the side of the cavity but the other end side thereof is limited by a snap ring 8.