Pre-plasticizing injection apparatus having a plurality of heating and

Abstract

A pre-plasticizing injection apparatus operated with a mold clamped by a mold clamping device comprises: a screw device movable toward and away from the mold clamping device and including a heat-plasticizing cylinder having a bore and a screw which rotatably extends through the bore, so that a resin material introduced into the heat-plasticizing cylinder is fed by rotation of the screw to one axial end of the heat-plasticizing cylinder, while being plasticized, and is ejected from the axial end; and a plunger device movable toward and away from the mold clamping device and including a plurality of heating and injecting cylinders and an injection nozzle which is connectable to the mold, each heating and injecting cylinders being operated to store therein the resin material plasticized by the screw device, while being operated to inject the resin material through the injection nozzle into the mold; and a switching valve device which permits the screw device to be connected to at least one of the plurality of the heating and injecting cylinders to supply the resin material from the screw device to the cylinder, while at the same time permitting the injection nozzle to be connected to at least one of the rest of the plurality of heating and injecting cylinders to inject the resin material store in the cylinder through the injection nozzle into the mold. An injection molding method using the injection apparatus is also disclosed.