Multi-gate molding heater assembly

An injection molding heater assembly for heating melt injected into an injection molding mold block mold bore, wherein the mold bore has multiple mold cavities and multiple mold gates leading to the mold cavities, said heater assembly comprising an elongated heated member having a melt inlet end and a melt outlet end and being adapted to centrally extend into said mold bore in heating communication with said mold bore, said elongated heated member being a torpedo, said melt inlet end of said heated member having a longitudinal melt transfer passage extending through said melt inlet end and providing a flow passageway for heated melt through said melt inlet end along said torpedo, said torpedo having an enlarged portion thereon at said melt outlet end, said enlarged portion including a lower gate tip portion having a plurality of gate tips corresponding in number to the mold gates of said mold bore, each of said gate tips extending downwardly from said torpedo enlarged portion and outwardly from said torpedo body to a position adjacent a mold cavity gate, each of said gate tips having an outer wall which is complementary in configuration to said mold bore and an arcuate inner wall, said gate tips being spaced apart and peripherally disposed on said torpedo enlarged portion so as to define a recess beneath said torpedo enlarged portion and between said torpedo enlarged portion said mold bore and said gate tips, each of said gate tips having a lower face which includes a channel extending radially across at least a portion of the lower face, the channel being aligned with said mold gates when said torpedo is inserted into said mold bore, said recess providing an area in said mold bore for injected melt to accumulate in and to solidify in so as to form a melt layer between said gate tips and said mold bore which insulates subsequently injected melt from said mold bore and minimizes heat loss from the injected melt to said mold bore.

In an injection molding heater assembly for heating injection melt supplied from an injection molding machine to a mold block having multiple mold cavities, the mold block including a mold bore extending therein which provides a passage for flow of the heated melt from said molding machine to the multiple mold cavities, said mold block including a plurality of gates corresponding to the number of said mold cavities which define mold passages for communicating the flow of melt from said mold bore to said mold cavities, the improvement comprising, an elongated heated bushing member having a bushing melt inlet end and a bushing melt outlet end, the bushing member further having a melt transfer passage generally centrally disposed therein and extending axially through said bushing, the bushing melt outlet end terminating in a bushing enlarged end portion having a substantially flat nozzle face disposed thereon and gate direction means including a plurality of gate tips corresponding in number to the number of mold cavity gates in said mold bore, said gate tips being peripherally disposed on said bushing nozzle face, said gate tips extending downwardly and outwardly from a bushing body portion to points adjacent said mold gates, said gate tips having outer surfaces which are generally complementary in configuration to said mold bore and further having arcuate inner surfaces, said gate tips further including a radial channel extending across a gate tip lower surface, said gate tips defining a recess between themselves and said mold bore when said bushing is inserted into said mold bore, said recess being positioned from said mold bore to provide an accumulation area for injected melt to accumulate and solidify in so as to form a melt layer between said gate tips and said mold bore which insulates subsequently injected melt from said mold bore and minimizes heat loss from the injected melt to said mold bore, said bushing member further including means for positioning said bushing within said mold bore, the bushing positioning means including a skirt extending radially outwardly from and disposed on said bushing between said melt inlet end and said melt outlet ends.