Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With accumulator – trap chamber – or serially arranged valves...
Patent
1998-07-30
2000-09-05
Heitbrink, Tim
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With accumulator, trap chamber, or serially arranged valves...
425563, A23P 100
Patent
active
061133809
ABSTRACT:
A back-flow prevention apparatus is composed of a screw and a platelike closing member. The screw includes at least a metering portion having a groove formed thereon for advancing a resin. The closing member is brought into an open position state by resin pressure which is developed behind the closing member in association with metering, thereby establishing communication between the groove and a space located ahead of the screw. The closing member is brought into a closed position by a restoring force of an elastic material, thereby shutting off communication between the groove and the space located ahead of the screw. Upon completion of a metering step, the restoring force brings the closed position into the closing state to thereby shut off communication between the groove and the space located ahead of the screw. Accordingly, sealing can be completed before the start of an injection step. Further, since timing for shutting off communication between the groove and the space located ahead of the screw does not vary, not only can the amount of resin charged into a mold cavity be stabilized, but also variation in injection peak pressure can be suppressed. As a result, molded products can be prevented from suffering burrs, short shot, or like defects. Also, variation in weight among molded products can be suppressed.
REFERENCES:
patent: 5441400 (1995-08-01), Zeiger
Heitbrink Tim
Sumitomo Heavy Industrie's, Ltd.
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