Patent ID: 7125242

Claim:
An injection molding apparatus comprising: a sprue bushing having a melt channel for receiving a melt stream of moldable material from a source, said melt channel having a first upstream portion, a second downstream portion and a decompression cavity provided between said first upstream portion and said second downstream portion; a manifold having a manifold channel for receiving said melt stream from said melt channel of said sprue bushing and delivering said melt stream through a plurality of thermal gated nozzles; and a rod having an enlarged head with an outer diameter that is larger than an inner diameter of each of said first upstream portion and said second downstream portion of said sprue bushing melt channel, said enlarged head being movable within said decompression cavity between an extended position and a retracted position by an actuator, said enlarged head of said rod being sized to restrict melt flow from said first upstream portion of said melt channel to said decompression cavity when said enlarged head is in the retracted position, wherein movement of said enlarged head from the extended position to the retracted position causes a portion of the melt occupying said manifold channel to be drawn into said decompression cavity.