Fixed center tooling for an extruder that provides for concentric layers of coating material

Claim 1

A fixed center extruder die assembly for applying concentric layers of coating material over an advancing core wire embodies an outer die block means with a first passage therethrough having a first longitudinal axis and including a first internal engaging portion; said die block means also including a generally annular guiding shoulder formed with an inwardly directed first abutment surface, an intermediate passage portion being concentric to the first axis and terminating in a first plane transverse to the first axis, and a generally smooth decreasingly tapered surface extending from the abutment surface to the intermediate passage; guiding die means having a second passage therethrough having its axis substantially coincident with the first axis, first flange means securely cooperating with the first internal engaging portion and having an aligning portion cooperating with the first abutment, a multiplicity of spaced ports formed in the flange for permitting flow of a first coating material therethrough, and a cylindrical tubing tip concentrically disposed within the intermediate passage for forming a first annular and concentric material passageway and terminating in the first plane, the guiding die means also including a generally thin walled conical section interconnecting the tip and the first flange, a second internal engaging section formed internally of the first flange, and a second generally annular guiding shoulder formed with an inwardly directed second abutment surface; and inner guiding means defining a third passageway extending therethrough with its axis substantially coincident to the first axis and including a third flange having an external surface securely engaging the second internal engaging section, a mulitiplicity of spaced ports, a second aligning portion cooperating with the second abutment shoulder, a second cylindrical tubing tip concentrically disposed within the first tip and terminating in the first plane for forming a second annular and concentric material passageway.