SCREW TYPE INJECTION MOLDING APPARATUS

摘要

PROBLEM TO BE SOLVED: To certainly prevent the backflow of a molten resin at the time of injection/dwelling while adding an auxiliary material such as a fiber or the like certainly and simply. SOLUTION: A torpedo 7 arranged in a cylinder head 4 is allowed to advance and retreat in its axial direction by a torpedo linear drive means 16. The torpedo 7 has a reservoir 6 having a pressure receiving part 7b due to difference in level piercing therethough axially and a screw head 3 having a diameter almost same to that of the bottom surface of the screw groove 2a thereof is fitted and inserted in the large diameter portion 6a of the reservior 6 so as to be freely slidable in the peripheral and axial directions thereof. The torpedo 7 receives the pressure of a molten resin in its pressure receiving part 7b in addition to the acting force of the torpedo linear drive means 16 at the time of injection/dwelling to generate pressing force for pressing the seal part 7c of the torpedo 7 to the conical inner wall surface 4a of the cylinder head 4. During the flowing of the molten resin through the outer wall groove 8a of the torpedo 7, an auxiliary material such as a fiber or the like is added through the through-hole 4c of the cylinder head 4 by a plunger 21.