An apparatus for producing injection mouldings, comprising:
- a mould having an interior surface which defines a mould space that includes an article of manufacture mould section, and said mould having a fluid plastic introduction opening that opens out at the interior surface into said mould space, and said mould also having a gas exhaust passageway which includes a nozzle reception opening that opens out at the interior surface into said mould space at a location spaced from said plastic introduction opening;
- a plastic material injection assembly which injects plastic material through said plastic introduction opening such that injected plastic material flows away from the plastic introduction opening along said interior surface;
- a gas supply nozzle positioned within said gas exhaust passageway, said gas supply nozzle having a first end dimensioned for sealing receipt by the nozzle reception opening of said gas exhaust passageway;
- a gas supply nozzle retraction assembly connected with said gas supply nozzle for shifting said gas supply nozzle between a plastic injection mode wherein the first end of said gas supply nozzle is received by said nozzle reception opening and extends into said mould space such that the injected plastic material passes around said first end while being prevented from entering said gas exhaust passageway and a gas escape mode wherein said first end is retracted into a gas exhaust position with respect to said nozzle reception opening, and said gas supply nozzle having an internal gas supply conduit which opens out at the first end of said gas supply nozzle;
- a valve member which is positioned in the gas supply conduit of said gas supply nozzle and has a head member that is dimensioned for sealing off an outlet end of said gas supply conduit when said valve member is placed in a valve closed state, and said valve member being dimensioned so as to extend further into the plastic material within said mould space when in an open state;
- a gas supply assembly which includes a gas line in communication with the internal gas supply conduit of said gas supply nozzle such that gas fed through said internal gas conduit and into contact with said valve member shifts said valve member from said valve closed state into the valve open state wherein the supplied gas penetrates the injected plastic and forms a gas cavity in the plastic material that facilitates the filling of the mould space as said nozzle reception opening is positioned at an intermediate location with respect to plastic travel along the interior surface in the mould space from the plastic introduction opening to a remote location of said article of manufacture mould section downstream, with respect to plastic travel, from both said plastic introduction opening and said nozzle reception opening, and said nozzle reception opening being positioned such that, upon a discontinuing of the gas supply, a return of said valve member to the valve closed state, and the retraction of the gas supply nozzle, the gas in the gas cavity escapes through said nozzle reception opening, past said first end of the gas supply nozzle and closed valve member and out said gas exhaust passageway,
- and wherein the first end of said gas supply nozzle is comprised of a frustoconical base section and a cylindrical tip, and said gas exhaust opening is defined by a corresponding frustoconical interior wall section and cylindrical wall section with the cylindrical wall section having an outlet end defining the nozzle reception opening and an axial length which is shorter than the axial length of said cylindrical tip such that said cylindrical tip extends away from the interior surface of said mould space and further into the mould space.