Parison extrusion head

Claim 2

An extrusion head for extruding a tube of plastic material comprising a die mandrel, a die body enclosing said die mandrel to define therewith an annular outlet orifice, an annular inlet orifice and an annular accumulation chamber in communication with and located between said inlet and outlet orifices, a diverter supported on said die mandrel and having an inlet port for receiving plastic material from an extruder and defining with said die mandrel an annular outlet port in communication with said annular inlet orifice for passage of the plastic material from said extruder to said accumulation chamber, said die body being axially expansible and contractible for expanding and contracting the volume of said accumulation chamber so that plastic material can be received through said inlet orifice and accumulated in said chamber when said die body is expanded and can be discharged through said outlet orifice when said die body is contracted.

Claim 3

The extrusion head that is defined in claim 1, wherein said die body includes two sections telescoped together and axially movable relative to one another for axially expanding and contracting the volume of said accumulation chamber.

Claim 4

An extrusion head for extruding a tube of plastic material comprising a die mandrel, a die body supported in spaced relation around said die mandrel so as to define therewith an annular outlet orifice, an annular inlet orifice and an annular accumulation chamber in communication with and located between said inlet and outlet orifices, said die body including a stationary portion at said outlet orifice and a movable portion at said inlet orifice telescoped over said stationary portion and movable axially with respect thereto for varying the volume of said accumulation chamber, and a stationary diverter mounted on said die mandrel and having an inlet port for receiving plastic material from an extruder, said diverter defining said die mandrel an annular outlet passage in communication with said inlet orifice for flow of plastic material to said accumulation chamber.

Claim 5

An extrusion head for extruding a tube of plastic material comprising a die mandrel, a die body supported in spaced relation around said die mandrel so as to define therewith an annular outlet orifice, an annular inlet orifice and an annular accumulation chamber in communication with and located between said inlet and outlet orifices, said die body including a stationary portion at said outlet orifice and a movable portion at said inlet orifice telescoped over said stationary portion and movable axially with respect thereto for varying the volume of said accumulation chamber, and a stationary diverter mounted on said die mandrel and having an inlet port for receiving plastic material from an extruder, said diverter defining said die mandrel an annular outlet passage in communication with said inlet orifice for flow of plastic material to said accumulation chamber.

Claim 6

The extrusion head that is defined in claim 3, wherein said movable portion is telescoped over said diverter and is movable axially relative thereto when said movable portion is moved to vary the volume of said accumulation chamber.

Claim 7

The extrusion head that is defined in claim 4, including a cylinder mounting plate on which said diverter is supported, a die body plate on which said stationary portion is mounted, said mounting and die body plates being interconnected by a plurality of guide rods, a movable plate supported on said guide rods for travel thereon and connected to said movable portion, and fluid cylinder means mounted on said cylinder mounting plate and having cylinder rods connected to said movable plate for moving the latter and thereby said movable portion.

Claim 8

The extrusion head that is defined in claim 5, wherein said movable portion has a radially outwardly directed wall adjacent to said annular inlet against which plastic material can flow when received in the accumulation chamber from said diverter and responsive to pressure of the plastic material in the accumulation chamber for moving said movable portion away from said stationary portion.

Claim 9

An extrusion head for extruding a tube of plastic material comprising a die mandrel, a die body supported in spaced relation around said die mandrel so as to define therewith in series an annular inlet orifice, an accumulation chamber and an annular outlet orifice, said die body including a stationary portion at said outlet orifice and a movable portion at said inlet orifice telescoped over said stationary portion and movable axially with respect thereto for varying the volume of said accumulation chamber, a diverter mounted on said die mandrel and having an inlet port for receiving plastic material, said diverter defining With said die mandrel an annular outlet passage in communication with said inlet orifice for flow of plastic material to said accumulation chamber, said movable portion and said diverter being in a sealed relation so that plastic material can continue to flow from said diverter to said accumulation chamber during movement of said movable portion, said accumulation chamber having a radially outwardly directed wall adjacent to said annular inlet orifice against which plastic material can flow when received in said accumulation chamber, and means to advance said movable portion toward said outlet orifice so that said wall will exert pressure on the plastic material in the accumulation chamber to extrude a tube of plastic material from said annular outlet orifice.

Claim 10

An extrusion head for extruding a tube of plastic material comprising a die mandrel, a die body supported in spaced relation around said die mandrel so as to define therewith in series an annular inlet orifice, an accumulation chamber and an annular outlet orifice, said die body including a stationary portion at said outlet orifice and a movable portion at said inlet orifice telescoped over said stationary portion and movable axially with respect thereto for varying the volume of said accumulation chamber, a diverter mounted on said die mandrel and having an inlet port for receiving plastic material, said diverter defining With said die mandrel an annular outlet passage in communication with said inlet orifice for flow of plastic material to said accumulation chamber, said movable portion and said diverter being in a sealed relation so that plastic material can continue to flow from said diverter to said accumulation chamber during movement of said movable portion, said accumulation chamber having a radially outwardly directed wall adjacent to said annular inlet orifice against which plastic material can flow when received in said accumulation chamber, and means to advance said movable portion toward said outlet orifice so that said wall will exert pressure on the plastic material in the accumulation chamber to extrude a tube of plastic material from said annular outlet orifice.

Claim 11

The extrusion head that is defined in claim 7, wherein said movable portion includes heating means for maintaining the movable portion at selected tempertures.

Claim 12

The extrusion head that is defined in claim 7, including a stationary mounting plate connected with said diverter, a stationary die body plate connected with said stationary portion, said mounting plate and said die body plate being interconnected by a plurality of guide rods, a movable plate supported on said guide rods for travel thereon and connected to said movable portion, said means being supported by one of said stationary plates and connected to said movable plate for moving the latter.