Extrusion machine

Claim 1

APPARATUS FOR ADVANCING AND WORKING PLASTIC MATERIAL IN A HOLLOW CYLINDER OF UNIFORM INTERNAL DIAMETER COMPRISING: (A) A STOCK SCREW ROTATABLE IN SAID CYLINDER HAVING AT LEAST ONE HELICAL THREAD EXTENDING ALONG A FIRST PORTION OF THE LENGTH OF SAID STOCK SCREW COMPRISING A FEED SECTION FOR ADVANCING SAID PLASTIC MATERIAL TO A FIRST (B) COMPRESSION SECTION DISPOSED ADJACENT SAID FEED SECTION AND COMPRISED OF AT LEAST ONE HELICAL THREAD EXTENDING ALONG A SECOND PORTION OF THE LENGTH OF SAID STOCK SCREW HAVING A ROOT DIAMETER THAT GRADUALLY INCREASES IN THE DIRECTION OF MOVEMENT OF SAID PLASTIC MATERIAL ALONG SAID CYLINDER WHEREBY SAID PLASTIC MATERIAL IS COMPRESSED BETWEEN SAID STOCK SCREW AND THE INNER WALL OF SAID CYLINDER AND SAID COMPRESSED MATERIAL IS DISCHARGED FROM SAID COMPRESSION SECTION INTO (C) A DISTRIBUTING SECTION ADJACENT SAID COMPRESSION SECTION WHEREIN THERE ARE NO HELICAL THREADS AND THE COMPRESSION MATERIAL IS UNIFORMLY DISTRIBUTED AROUND SAID STOCK SCREW AND DELIVERED TO (D) A WORKING SECTION DISPOSED ADJACENT SAID DISTRIBUTING SECTION AND COMPRISED OF ONE OR MORE HELICAL THREADS EXTENDING ALONG A THIRD PORTION OF SAID STOCK SCREW, SAID THREADS HAVING A PITCH IN THE RANGE OF 3 TO 10 TIMES THE PITCH OF THE HELICAL THREAD IN SAID COMPRESSION SECTION AND A LEADING FACE THAT UNIFORMLY SLOPES DOWNWARDLY FORWARD TOWARD THE AXIS OF SAID STOCK SCREW AT AN ANGLE IN THE RANGE OF 2* TO 5*, SAID LEADING FACE MERGING WITH THE ARCUATE TRAILING FACE OF THE NEXT ADJACENT SCREW THREAD WHEREBY THE MATERIAL DELIVERED TO SAID WORKING SECTION FLOWS ALONG SAID STOCK SCREW AND PASSES OVER THE CREST OF SAID ELONGATE THREADS AND IS WORKED BETWEEN THE WALLS OF SAID CYLINDER AND THE FACE OF SAID SCREW THREAD, SAID MATERIAL BEING THEREAFTER DELIVERED TO (E) A SECOND COMPRESSION SECTION SUBSTANTIALLY THE SAME AS SAID FIRST COMPRESSION SECTION DISPOSED ADJACENT SAID WORKING SECTION AND EXTENDING ALONG A FOURTH PORTION OF SAID SCREW; AND (F) A METERING SECTION DISPOSED ADJACENT SAID SECOND COMPRESSION SECTION AND COMPRISED OF A SCREW THREAD EXTENDING ALONG A FIFTH PORTION OF SAID STOCK SCREW.