Plastic material extrusion head

Claim 1

APPARATUS FOR EXTRUDING PLASTIC MATERIAL IN CONTINUOUS TUBULAR FORM, SAID APPARATUS HAVING MEANS FOR DELIVERING PLASTIC MATERIAL UNDER PRESSURE, A HEAD DISPOSED ON THE MECHANISM AND HAVING A BORE FOR RECEIVING PLASTIC MATERIAL FROM THE DELIVERING MEANS, A DELIVERY PASSAGE INTERPOSED BETWEEN THE DELIVERING MEANS AND THE BORE, A DIE AT THE FORWARD END OF THE BORE FOR SHAPING THE PLASTIC MATERIAL AS IT PASSES OUT OF THE HEAD, A CENTRAL MEMBER IN THE BORE OF THE HEAD EXTENDING ACROSS THE OPEN END OF THE DELIVERY PASSAGE TOWARD THE DIE, MEANS CLOSING THE REAR END OF THE BORE AND HAVING AN ANNULAR SURFACE SURROUNDING THE CENTRAL MEMBER, SAID SURFACE FACING THE DIE AND DIVERTING THE PLASTIC MATERIAL TOWARD THE DIE AS IT PASSES THROUGH THE BORE FROM THE DELIVERING MEANS, THE PORTION OF SUCH ANNULAR SURFACE NEARER THE DIE LYING ACROSS AT LEAST A PORTION OF THE DELIVERY PASSAGE AND SLANTING AT AN ANGLE ON THE ORDER OF 45* WITH RESPECT TO THE AXIS OF THE BORE IN A DIRECTION OUTWARDLY OF THE DELIVERY PASSAGE AND FORWARDLY OF THE BORE, A SEPARATE AND REMOVABLE SLEEVE-LIKE MEMBER SURROUNDING AND RADIALLY SPACED FROM THE CENTRAL MEMBER AT THE FORWARD END OF THE BORE AND HAVING A REAR END AXIALLY SPACED FROM AND GENERALLY PARALLEL TO THE ANNULAR SURFACE TO FORM AN INCLINED PLASTIC MATERIAL RECEIVING CHAMBER THEREBETWEEN, THE REAR END OF THE SLEEVE-LIKE MEMBER AT THE ZONE THEREOF NEAREST THE DELIVERY PASSAGE EXTENDING SUBSTANTIALLY TO THE JUNCTURE BETWEEN THE DELIVERY PASSAGE AND THE BORE IN THE HEAD, THE FORWARD END OF THE SLEEVELIKE MEMBER EXTENDING SUBSTANTIALLY TO THE FORWARD END OF THE BORE IN THE HEAD, SAID CHAMBER EXTENDING COMPLETELY AROUND SAID CENTRAL MEMBER, THE ANNULAR SPACE BETWEEN THE INNER SURFACE OF THE SLEEVE-LIKE MEMBER AND THE CENTRAL MEMBER CONDUCTING PLASTIC MATERIAL FROM THE CHAMBER TOWARD THE DIE, THE RADIALLY INNER EDGE AT THE REAR END OF THE SLEEVE-LIKE MEMBER BEING BEVELLED AT VARYING RADIAL DEPTHS THROUGHOUT AT LEAST A PREDOMINANT PART OF ITS CIRCUMFERENCE, SAID BEVEL HAVING ITS MAXIMUM DEPTH AT THE AXIALLY FORWARDMOST ZONE OF THE REAR END OF THE SLEEVE-LIKE MEMBER AND ITS MINIMUM DEPTH ADJACENT THE AXIALLY REARMOST ZONE OF THE REAR END OF THE SLEEVE-LIKE MEMBER.