Csongor; D. G. ; Lasch; E. J.; Kapila; V. U.S. Pat. 5,670,112 (1997)

The present invention comprises a method for delivering a medium such as a gas, vapor or liquid into a melted plastic in a mold via an elongated screw shaft rotatably supported in a housing, the method including the steps of providing the screw shaft with a bore longitudinally therethrough from a proximal end to a distal tip end thereof, rotating the screw shaft in the housing to move plastic therethrough, and into the mold, introducing a gas, vapor or liquid into the bore, to permit the gas, vapor or liquid to be delivered through the bore, and into the molten plastic in the mold through the distal tip end of the screw shaft.

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