| 摘要 |
An injection apparatus for injecting hot plastics material into an injection mold has an actuator section forming an actuator chamber and a nozzle member connected to the actuator section and extending to a nozzle tip having an injection aperture. The nozzle member includes an injection passage system for conducting the hot plastics material to the injection aperture. An elongate valve pin extends through a guide passage in the nozzle member and is movable between open and closed positions. A piston is connected to this pin, is slidably mounted in the actuator chamber and moves the valve pin between the open and closed positions. The piston and actuator section are machined to close tolerances so as to form a micro-gap between the wall of the piston and the wall of the chamber thereby avoiding fluid seals. The actuator is able to operate at temperatures ranging between 200 and 400° C.
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