Patent attributes
The valve nozzle according to the invention is constructed so that, in the internal space of a valve nozzle main body, a gate opening and closing mechanism is disposed in which a piston having a head part and a shaft part, a torpedo that is disposed in the internal space of the nozzle head and slidably supports the piston and guides the piston, and is provided with, on its outer circumferential surface, concaved grooves that are twisted with respect to a resin injection direction and serve as a plurality of wound resin flow channels, a coil spring that presses the piston in the direction toward a gate, and a cover that closes the rear end of the torpedo and serves as a spring receiving part of the coil spring are integrally assembled, and when the resin pressure is at a predetermined value or less, the entire circumference of the circular section of the head part of the piston comes into contact with the inner wall of the gate of the nozzle head to close the resin flow channels, and when the resin pressure becomes a predetermined value or more, the head part withdraws from the gate to release the gate.
