| 摘要 |
An extruder that can control the temperature on the whole screw including the flight and avoid an extruded material form adhering on a surface of the screw, has a center hole with its front end closed formed in the center of the screw core, and an inner tube inserted in the center hole from the base end side of the center hole. The front end of the inner tube opens at a position corresponding to the base end of the flight. A ring seal member occludes a space between a front outer surface of the inner tuber and the corresponding inner surface of the center hole. Thus, a main channel of a dual tube is formed which has an outward channel inside the inner tube and an inward channel outside the inner tube. On the other hand, on the back side of the flight, a jacket-form spiral channel is formed along the whole backside. The front end and the rear end of the spiral channel each communicate with the outward channel and inward channel of the main channel, respectively, through radial communicating holes.
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