NOZZLE FOR GAS-ASSISTED INJECTION MOLDING

摘要

IMPROVED NOZZLE FOR GAS-ASSISTED INJECTION MOLDING An improved nozzle for gas-assisted injection molding and a method of gas-assisted injection molding using the improved nozzle are provided. This improved nozzle employs a very simple design to vent the gas from the mold cavity once the plastic article has cooled sufficiently to be self supporting. In one especially preferred embodiment of this invention, the improved nozzle contains a separate plastic shut-off valve, a separate gas inlet passage with check valve, and a separate gas venting passage containing a movable pin. Venting of the pressurized gas occurs by movement of the movable pin so that the pressurized gas can burst through the thin layer of plastic material covering the gas venting passage. The improved nozzle design and method allow fir almost continuous operation with minimal operator attention to the nozzle.