Process and apparatus for forming plastic articles

摘要

A valve gating apparatus and method for injection molding includes at least one shutter disposed between the gate and the cavity melt channel into a mold cavity. The shutter is moved laterally, between a closed position wherein flow of melt from the nozzle into the cavity is inhibited, and an open position wherein flow of melt into the cavity is unimpeded by the shutter. Intermediate these two positions, the shutter can be employed to reduce the cross sectional area of the gate to throttle the gate. Embodiments are disclosed wherein one shutter or pairs of shutters are employed to gate the gate. Further, when pairs of shutters are employed, the shutters can abut each other in the close position or can overlie each other. This novel design prevents generation of waste material and eliminates the need to have devices for removing cold plugs.