Injection molding system having spring biased nozzles

In a multi-cavity injection molding apparatus having a plurality of nozzles, each nozzle having an integral heating element and being received in a cavity plate between a manifold and a respective cavity, each nozzle having a rear end and a tapered forward end in alignment with a gate leading to the respective cavity, wherein pressurized melt from a molding machine flows through a melt passage extending through the manifold and a bore extending through each nozzle to the gate leading to each cavity, the improvement wherein:

• each nozzle is received in an opening in the cavity plate to reciprocate between a retracted open position and a forward closed position wherein the tapered forward end of the nozzle is seated in a respective gate, a spring and sealing housing is mounted between each nozzle and the manifold, each spring and sealing housing having a central bore, a rear face and a forward face, the rear face of the spring and sealing housing being secured against the manifold with the central bore of the housing in alignment with an outlet from the melt passage extending through the manifold, the forward face of the spring and sealing housing having a spring channel therein which extends around and is separate from the central bore of the housing, spring means mounted in the spring channel to apply a bias to the rear end of the nozzle to drive the nozzle to the forward closed position, the bore of the nozzle extending through a central sleeve portion which extends rearwardly into the central bore of the spring and sealing housing, the central sleeve portion of the nozzle having an outer surface which seals against an inner surface of the bore of the spring and sealing housing to prevent melt leakage therebetween as the nozzle reciprocates between the open and closed positions.