Injection molding nozzle probe and stack molding apparatus

Claim 1

Stack injection molding apparatus for conducting melt from a fixed platen to a movable platen, where said platens are actuated according to an operating cycle between open and closed positions, comprising: (a) a first heated elongated nozzle probe seated in the fixed platen, said first nozzle probe having a pointed tip in alignment with a first gate extending through the fixed platen, the first nozzle probe having at least one melt passage extending to convey pressurized melt from an inlet in said first nozzle probe to the first gate; and (b) a second heated elongated nozzle probe seated in the movable platen, said second nozzle probe having a pointed tip in alignment with a second gate extending through the movable platen, the first gate through the fixed platen connecting with the second gate through the movable platen in the closed position, the second nozzle probe having at least one melt passage extending to convey pressurized melt from the second gate to a melt duct in the movable platen; the first and second nozzle probes each having first and second electrical heating elements extending longitudinally along the melt passage, the first heating element having a portion extending into the pointed tip of the respective nozzle probe and the second heating element terminating short of the pointed tip, including an electrical power source which is connected to energize only the second heating element in the first nozzle probe and at least the first heating element in the second nozzle probe, whereby the pointed tip of the second nozzle probe is heated to a higher temperature than the pointed tip of the first nozzle probe to reduce stringing of the melt when the movable platen is actuated to the open position.