Patent ID: 6109909
Filing Date: 2000-08-29
Classification: B29C

Abstract:
A pre-plasticizing injection apparatus operated with a mold clamped by a mold clamping device comprising:a screw device movable toward and away from said mold clamping device and including a heat-plasticizing cylinder having a center bore to which a resin material is supplied, and a screw which extends through said center bore of said heat-plasticizing cylinder such that said screw is rotated to feed said resin material to one of opposite axial ends of said heat-plasticizing cylinder such that said resin material is heated and thus plasticized within said center bore of said heat-plasticizing cylinder, and the plasticized resin material is ejected from said one axial end of said heat-plasticizing cylinder;a plunger device movable toward and away from said mold clamping device and including a plurality of heating and injecting cylinders each having a center bore and a plunger axially slidably received in said center bore, and an injection nozzle which is connectable at one of opposite end portions thereof to said mold, each of said plurality of heating and injecting cylinders being operated to store therein said resin material plasticized by said screw device by a retracting movement of the corresponding plunger, and to eject said resin material stored therein, through said injection nozzle, by an advancing movement of the corresponding plungers toward one of opposite axial ends of the corresponding heating and injecting cylinder; anda switching valve device which permits said screw device to be connected to at least one of said plurality of said heating and injecting cylinders so that said resin material ejected from said screw device is supplied into and stored in said at least one of said heating and injecting cylinders, while at the same time permitting said injection nozzle to be connected to at least one of the rest of said plurality of heating and injecting cylinders which is not connected to said screw device so that said resin material stored in said at least one of said rest of said plurality of heating and injecting cylinders is injected through said injection nozzle, wherein said plunger device further has a communication passage which permits temporary communication between said at least one of said plurality of heating and injecting cylinders which has been operated to eject said resin material stored therein and said at least one of said rest of said plurality of heating and injecting cylinders which is to be operated to eject said resin material, so that said resin material is transferable between said plurality of heating and injecting cylinders communicated with each other by said communication passage.