Importance

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Abstract

The invention relates to a valve nozzle used for a molding machine of synthetic resin and is characterized in that a gate opening and closing mechanism consisting of a spool having a head portion at which a circular cross-sectioned part and a notched part are formed, a shaft portion and an arrow feather shaped projection, and a coil spring which presses the abovementioned spool in the direction opposite to the gate, is disposed in the interior space of a nozzle head attached to the tip end of a nozzle holder via a screw mechanism, when resin pressure is less than a certain fixed level, the abovementioned spool is pressed by the abovementioned coil spring in the direction opposite to the gate and the entire periphery of the circular cross-sectioned portion of the head portion of the spool is brought into contact with the interior wall of the gate of the nozzle head to cause the resin flow path to be closed, and when the resin pressure becomes higher than a certain fixed level, the head portion of the abovementioned spool overcomes a pressing force of the coil spring and is caused to protrude outward of the gate of the nozzle head, wherein a resin flow path is formed between the notched part of the head portion of the spool and the interior wall of the gate and the resin flow path is caused to open. With such construction, resin flow in the vicinity of the gate can be remarkably improved, and in particular it is possible to obtain molding components which are rarely cracked in comparison with molded components in which a conventional type nozzle is used.

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First Claim