Apparatus for extruding a homogeneous tubular length of soft thermoplastic material

Claim 1

An apparatus for extruding a tube of relatively soft thermoplastic material comprising; a generally cylindrical housing having an interior wall and a longitudinal axis; a generally cylindrical core member extending through at least a portion of said cylindrical housing and being co-axially aligned therewith; said core member having a longitudinal bore extending therethrough; said core member having a lower end provided with a downwardly opening cavity communicating with said longitudinal bore; a mandrel having an upper portion slidably disposed in said cavity in said lower end of said core member; said mandrel having an outwardly flaring lower portion extending downwardly through the lower end of said housing and terminating in an enlarged, generally circular bottom end; a generally annular die member having an upper end disposed within said lower end of said housing and a lower end extending downwardly through said lower end of said housing and surrounding said lower end of said mandrel; said lower ends of said die member and said mandrel defining an annular space therebetween; a control rod extending downwardly through said longitudinal bore in said core member and having a lower end connected to the upper end of said mandrel for moving said mandrel upwardly and downwardly; means defining an opening in the wall of said housing for receiving thermoplastic material; a double walled piston mounted in said housing for longitudinal sliding movement relative to said core member and said cylindrical housing; said double walled piston including: a generally annular, longitudinal extending outer wall; a generally annular, longitudinally extending inner wall; and means defining a generally semi-cylindrical, longitudinally extending channel in the outer surface of said outer wall; said inner and outer annular walls of said piston defining an annular piston chamber therebetween; said longitudinal channel having an open upper end in communication with said annular piston chamber; and said longitudinal channel communicating with said opening in said wall of said cylindrical housing.

Claim 2

An apparatus for extruding a tube of relatively soft thermoplastic material comprising; a generally cylindrical housing having an interior wall and a longitudinal axis; a generally cylindrical core member extending through at least a portion of said cylindrical housing and being co-axially aligned therewith; said core member having a longitudinal bore extending therethrough; said core member having a lower end provided with a downwardly opening cavity communicating with said longitudinal bore; a mandrel having an upper portion slidably disposed in said cavity in said lower end of said core member; said mandrel having an outwardly flaring lower portion extending downwardly through the lower end of said housing and terminating in an enlarged, generally circular bottom end; a generally annular die member having an upper end disposed within said lower end of said housing and a lower end extending downwardly through said lower end of said housing and surrounding said lower end of said mandrel; said lower ends of said die member and said mandrel defining an annular space therebetween; a control rod extending downwardly through said longitudinal bore in said core member and having a lower end connected to the upper end of said mandrel for moving said mandrel upwardly and downwardly; means defining an opening in the wall of said housing for receiving thermoplastic material; a double walled piston mounted in said housing for longitudinal sliding movement relative to said core member and said cylindrical housing; said double walled piston including: a generally annular, longitudinal extending outer wall; a generally annular, longitudinally extending inner wall; and means defining a generally semi-cylindrical, longitudinally extending channel in the outer surface of said outer wall; said inner and outer annular walls of said piston defining an annular piston chamber therebetween; said longitudinal channel having an open upper end in communication with said annular piston chamber; and said longitudinal channel communicating with said opening in said wall of said cylindrical housing.

Claim 3

An apparatus for extruding a tube of relatively soft thermoplastic material comprising: a generally cylindrical housing having an interior wall and a longitudinal axis; a generally cylindrical core member extending through at least a portion of said cylindrical housing and being co-axially aligned therewith; means defining an opening in the wall of said housing for receiving thermoplastic material; a double walled piston mounted in said housing for longitudinal sliding movement relative to said core member and said cylindrical housing; said double walled piston including: a generally annular, longitudinally extending outer wall; a generally annular, longitudinally extending inner wall; and means defining a generally semi-cylindrical, longitudinally extending channel in the outer surface of said outer wall; said inner and outer annular walls of said piston defining an annular piston chamber therebetween; said longitudinal channel having an open upper end in communication with said annular piston chamber; and said longitudinal channel communicating with said opening in said wall of said cylindrical housing.

Claim 4

An apparatus for extruding a tube of relatively soft thermoplastic material comprising: a generally cylindrical housing having an interior wall and a longitudinal axis; a generally cylindrical core member extending through at least a portion of said cylindrical housing and being co-axially aligned therewith; means defining an opening in the wall of said housing for receiving thermoplastic material; a double walled piston mounted in said housing for longitudinal sliding movement relative to said core member and said cylindrical housing; said double walled piston including: a generally annular, longitudinally extending outer wall; a generally annular, longitudinally extending inner wall; and means defining a generally semi-cylindrical, longitudinally extending channel in the outer surface of said outer wall; said inner and outer annular walls of said piston defining an annular piston chamber therebetween; said longitudinal channel having an open upper end in communication with said annular piston chamber; and said longitudinal channel communicating with said opening in said wall of said cylindrical housing.

Claim 5

An apparatus for extruding a tube of relatively soft thermoplastic material comprising: a generally cylindrical housing having an interior wall and a longitudinal axis; a generally cylindrical core member extending through at least a portion of said cylindrical housing and being co-axially aligned therewith; means defining an opening in the wall of said housing for receiving thermoplastic material; a double walled piston mounted in said housing for longitudinal sliding movement relative to said core member and said cylindrical housing; said double walled piston including: a generally annular, longitudinally extending inner wall and a generally annular, longitudinally extending outer wall, said annular walls being interconnected for unitary longitudinal sliding movement; said inner and outer annular walls of said piston being mutually spaced to define an annular piston chamber therebetween; said annular piston chamber communication with said opening in said wall of said cylindrical housing.

Claim 6

An apparatus for extruding a tube of relatively soft thermoplastic material comprising: a generally cylindrical housing having an interior wall and a longitudinal axis; a generally cylindrical core member extending through at least a portion of said cylindrical housing and being co-axially aligned therewith; means defining an opening in the wall of said housing for receiving thermoplastic material; a double walled piston mounted in said housing for longitudinal sliding movement relative to said core member and said cylindrical housing; said double walled piston including: a generally annular, longitudinally extending inner wall and a generally annular, longitudinally extending outer wall, said annular walls being interconnected for unitary longitudinal sliding movement; said inner and outer annular walls of said piston being mutually spaced to define an annular piston chamber therebetween; said annular piston chamber communication with said opening in said wall of said cylindrical housing.

Claim 8

An apparatus for extruding a tube of relatively soft thermoplastic material comprising: a generally cylindrical housing having an interior wall and a longitudinal axis; a generally cylindrical core member extending through at least a portion of said cylindrical housing and being co-axially aligned therewith; said core member having a longitudinal bore extending therethrough; said core member having a lower end provided with a downwardly opening cavity communicating with said longitudinal bore; a mandrel having an upper portion slidably disposed in said cavity in said lower end of said core member; sand mandrel having an outwardly flaring lower portion extending downwardly through the lower end of said housing and terminating in an enlarged, generally circular bottom end; a generally annular die member having an upper end disposed within said lower end of said housing and a lower end extending downwardly through said lower end of said housing and surrounding said lower end of said mandrel; said lower ends of said die member and said mandrel defining an annular space therebetween; a control rod extending downwardly through said longitudinal bore in said core member and having a lower end connected to the upper end of said mandrel for moving said mandrel upwardly and downwardly; means defining a pair of diametrically opposed openings in the wall of said housing for receiving thermoplastic material; a double walled piston mounted in said housing for longitudinal sliding movement relative to said core member and said cylindrical housing; said double walled piston including: a generally annular, longitudinal extending outer wall; a generally annular, longitudinally extending inner wall; and means defining a pair of diametrically opposed, generally semi-cylindrical, longitudinally extending channels in the outer surface of said outer wall; said inner and outer annular walls of said piston defining an annular piston chamber therebetween; each of said longitudinal channels having an open upper end in communication with said annular piston chamber; and each of said longitudinal channels communicating with one of said openings in said wall of said cylindrical housing.

Claim 9

An apparatus for extruding a tube of relatively soft thermoplastic material comprising: a generally cylindrical housing having an interior wall and a longitudinal axis; a generally cylindrical core member extending through at least a portion of said cylindrical housing and being co-axially aligned therewith; said core member having a longitudinal bore extending therethrough; said core member having a lower end provided with a downwardly opening cavity communicating with said longitudinal bore; a mandrel having an upper portion slidably disposed in said cavity in said lower end of said core member; sand mandrel having an outwardly flaring lower portion extending downwardly through the lower end of said housing and terminating in an enlarged, generally circular bottom end; a generally annular die member having an upper end disposed within said lower end of said housing and a lower end extending downwardly through said lower end of said housing and surrounding said lower end of said mandrel; said lower ends of said die member and said mandrel defining an annular space therebetween; a control rod extending downwardly through said longitudinal bore in said core member and having a lower end connected to the upper end of said mandrel for moving said mandrel upwardly and downwardly; means defining a pair of diametrically opposed openings in the wall of said housing for receiving thermoplastic material; a double walled piston mounted in said housing for longitudinal sliding movement relative to said core member and said cylindrical housing; said double walled piston including: a generally annular, longitudinal extending outer wall; a generally annular, longitudinally extending inner wall; and means defining a pair of diametrically opposed, generally semi-cylindrical, longitudinally extending channels in the outer surface of said outer wall; said inner and outer annular walls of said piston defining an annular piston chamber therebetween; each of said longitudinal channels having an open upper end in communication with said annular piston chamber; and each of said longitudinal channels communicating with one of said openings in said wall of said cylindrical housing.