| 摘要 |
A pre-plasticization type injection molding machine is equipped with a plasticizing part for plasticizing synthetic resin material by turning a screw in a heating cylinder and an injection part for injecting the plasticized material through a nozzle by advancing and retreating an injection plunger into and from an injection cylinder. A conduit connects the tip of a plasticizing chamber, consisting of the heating cylinder, with the tip of an injection chamber consisting of the injection cylinder. The screw advances at the time of injection, closes the conduit with its tip. The opening of the conduit in the injection chamber is arranged on the periphery of a nozzle side-wall. An injection passage extends from the injection chamber toward the nozzle, the passage being open to the center of the nozzle side-wall. An injection by-pass extends from the injection chamber toward the injection passage, the injection by-pass being open on the nozzle side-wall to a region opposite to the conduit opening with the injection passage therebetween. As the injection plunger advances, dissolved material in the injection chamber is introduced in to the nozzle through the injection passage while material is retained after the previous injection is introduced in to the nozzle by way of the injection by-pass.
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