METHOD FOR INJECTION MOLDING EXTRA-THIN CONTAINER

摘要

PROBLEM TO BE SOLVED: To thin a body bottom of an extra-thin container by extrapolating an unfilled part generated from a difference of a flowing speed of a resin flow by a core with an excess resin generated by a compression. SOLUTION: A mold 1 having a shallow bottom cavity 2 for molding the extra-thin container body 10 and the core 3 for molding a body inner surface in the cavity is used. A method for injection molding the extra-thin container comprises the step of movably projecting the core 3 in the cavity except a compression margin of 2 to 5 times as large as a thickness of a body bottom. A side gate 5 is provided at the cavity 2. The method further comprises the steps of injection filling the resin 6 in the cavity 2 from the side gate 5, and primarily molding a body edge 11 and a thick body bottom by the core 3. The method also comprises the step of stopping injection filling of the resin 6 when centers of the body bottom of an opposite side to the gate 5 and the body edge are disposed at flowing spaces 7, 8 in an incomplete state. The method also comprises the steps of compression molding the thick body bottom to an extra-thin thickness by the core 3, and simultaneously extruding the excess resin in the spaces 7, 8 the extrapolate the resin of an uncompleted part.