Injection molding apparatus comprises gating system including valve pin and actuator, in which valve pin is movable between open and closed positions to permit melt flow into mold cavity, and block melt flow passage, respectively

摘要

An injection molding apparatus comprises mold block; nozzle; gating system; and slug heater. The gating system includes valve pin and actuator, where valve pin is movable between open position where melt flow is permitted into mold cavity, and closed position where valve pin blocks melt flow passage to prevent melt flow into mold cavity. The actuator is operatively connected to valve pin. An injection molding apparatus comprises a mold block; nozzle (14); gating system (18); and slug heater. The mold block defines a mold cavity (32) having a mold cavity inlet (32a). The nozzle has a nozzle inlet fluidically connectable downstream from a melt source and upstream from the mold cavity inlet, and a melt flow passage extends from the nozzle inlet to the mold cavity inlet. The gating system includes a valve pin (44) and actuator (46), where the valve pin is movable between an open position where melt flow is permitted into the mold cavity, and a closed position where the valve pin blocks the melt flow passage to prevent melt flow into the mold cavity. The actuator is operatively connected to the valve pin to move the valve pin between the open and closed positions. The mold block and/or valve pin includes a cooling system for selectively solidifying melt to form a slug immediately upstream from the valve pin when the valve pin is in closed position, where, in use, the slug blocks the melt flow passage to prevent melt leakage past the slug when the valve pin is away from the slug. The slug heater is thermally connectable to the slug and is configured for selectively melting the slug to permit melt flow in the melt flow passage. An Independent claim is also included for a method for controlling melt flow in an injection molding apparatus, comprising providing at gate passage (33) of mold cavity, a valve pin that is movable between an open position where the valve pin is at least partially removed from the gate passage to permit melt flow through the gate passage, to a closed position where the valve pin cooperates with the gate passage to inhibit melt flow, where the valve pin is outside the nozzle melt channel in both the open and closed positions and is away from the mold cavity in both the open and closed positions; and moving the valve pin between the open and closed position to control the flow of melt into the mold cavity.