| 摘要 |
There is provided an injection apparatus comprised of a heating cylinder which is closed by a front end member having a nozzle. The apparatus is further comprised of a plasticating screw in the heating cylinder in a freely rotating and reciprocating manner, and a plunger connected to the front end of the screw. The plunger has a conical front end in which flow channels are formed. The front end member has a measuring chamber formed therein at an internal central location thereof. The measuring chamber has a predetermined length and an internal diameter which is reduced by 8 to 15% with respect to an internal diameter of the heating cylinder. The diameter of the injection plunger is set almost equal to the diameter of the measuring chamber, whereby the injection plunger is inserted into the measuring chamber in a freely reciprocating manner. A gap is formed on the external peripheral surface of the plunger due to the difference between the heating cylinder internal diameter and the plunger diameter, and the gap functions as a plastication-accelerating block. The block is formed so as to have a distance longer than an injection stroke, whereby uniform plastication is achieved and uneven temperature in the material is eliminated. Further, the plunger advance blocks the gap, which leads to uniform density and precise measurement of the material.
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