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AssigneeGeneral Motors Corporation
InventorsSuresh D. Shah, David G. Hlavaty
Estimating the term…
Gas transmission plugs are placed in a supporting strip portion in plastics injection mold tooling so that an appropriate gas assist injection location can be readily selected, and mated, with a gas injection nozzle thereby eliminating the requirement for pre-drilling mold tooling with gas injection points and removing the tooling from the press so that a gas injection nozzle can be installed relative to the selected injection location. The plugs can be made from porous metal or ceramic with pores that are so small that plastics cannot enter the plug to cause pore clogging. Also, linear gas transmitting passages can be laser beam drilled through plugs of steel or other material with diameters that are sufficiently minute to prevent entry of plastics melt and resultant clogging.
A tool for a gas assisted plastics injection molding apparatus having plastics injector means associated therewith for injecting a short shot of plastics into said tool and having a gas injector associated therewith for injecting pressurized assist gas into said tool, said tool comprising a body having a cavity therein for receiving a short shot of plastics material from the plastics injector means, a support strip operatively mounted in said body having a plurality of discrete gas conducting plugs supported therein, each of said plugs being defined by a body member having an injection gas entrance and an injection gas exit at opposing end portions thereof, each of said plugs supported in said support strip extending completely through the support strip, said injection gas exit of each of said plugs being in communication with said cavity, each of said plugs having a plurality of gas passageways operatively connecting said injection gas entrance to said injection gas exit, said passageways being dimensioned so as to transmit the molecules of assist gas from the gas injector into said cavity and to inhibit the entrance of plastics material therein and the clogging thereof, said plugs being spaced from one another at distances along said strip for alignment of the gas injector with any selected one of said plugs to effect the supply of assist gas therein to force the short shot of plastics material against the wall of the cavity to thereby form a molded part.
Plastics injection mold tooling having a mold cavity therein for receiving a short shot of plastics melt therein, an elongated opening extending through said mold tooling communicating with said cavity, gas injection assist construction for transmitting assist gas into said mold cavity, said assist construction including a gas injector for injecting pressurized assist gas into a short shot of plastics melt in said cavity so that a plastics part will be molded to conform to the walls defining said cavity, said assist construction further including an elongated support strip secured to the mold tooling for closing said elongated opening therein, fastener means for securing said support strip to said mold tooling, a plurality of openings spaced from one another and extending completely through said support strip, a plurality of gas transmitting plugs spaced from one another and operatively mounted in said openings in said support strip, each of said plugs having a gas inlet end for receiving gas from said gas injector and having a gas discharge end for feeding pressure gas into said short shot of plastics melt to force the material of said melt as a wall against the profile of said cavity, and support means on said tooling for movably supporting said gas injector in a path corresponding to said support strip so that any one of said plugs can be selected and used for the transmittal of gas into said short shot.
Mold tooling for gas assisted plastics injection molding adapted to receive pressurized gas from a gas injector with a gas injection nozzle selectively movable with respect to said mold tooling to contact one of a plurality of gas injection stations, said mold tooling comprising body means with a molding cavity therein for receiving a short shot of plastics melt from a plastics injector associated with said tooling, a plurality of gas transmitting plug means for transmitting gas from said injector into said cavity defining the plurality of gas injection stations, each of said plug means having a gas entry head portion adapted to be selectively contacted by the gas injector nozzle and a gas exit end portion for directing pressurized gas into said short shot of plastics material, plug support means removably secured to said body means and supporting each said plug means in spaced relationship with respect to one another, fastener means for removably securing said support means to said body means so that said plug means transmits pressurized assist gas fed thereto from said gas injector into said short shot of plastics melt, said gas transmission plug means having minute gas passage means extending from said head portion to said exit end portion to transmit said assist gas directly into said short shot to force the plastics material of the melt against the wall defining said cavity to form a plastics part with a hollow interior, said gas passage means being sized so as to prevent the entry of said plastics melt therein and resulting clogging of gas passage means and said plug means.
Dependencies are inferred from the claim text.