Coextrusion apparatus

A coextrusion head for producing a generally tubular elastomeric ply made up of first and second coaxial tubular streams of elastomeric materials having interposed adjacent to their interface a closely and uniformly spaced large array of parallel and independent reinforcing elements, said coextrusion head comprising in combination:

• (a) a reinforcing element guide subassembly including a generally annular guide element having an outer wall surface and an inner wall surface as well as axially-directed guide means for individually and independently directing and accurately positioning a circular array of closely and uniformly spaced individual reinforcing elements;
• (b) a generally annular inner die assembly, having inner and outer wall surfaces, coaxial with and located substantially radially inwardly of said annular guide element, at least one of said annular guide element and said inner die assembly having a 360.degree. annular contoured channel in the wall surface, opposed to the wall surface of the other, said channel together with said opposed wall surface forming a first distribution channel;
• (c) a generally annular outer die assembly, having inner and outer wall surfaces, coaxial with and located substantially radially outwardly of said annular guide element;
• (d) at least one of said annular guide and said outer die assembly having a 360.degree. annular channel in the wall surface opposed to the wall surface of the other, said channel together with said opposed wall surface forming a second distribution channel;
• (e) the axial outer portions of the inner and outer wall surfaces of said annular guide element having converging portions merging into an end portion having a narrow annular outer end surface with said guide means having axial outlet end faces co-planar with said guide element narrow annular end surface;
• (f) a portion of the outer wall surface of said inner die assembly and a portion of the inner wall surface of said annular guide element, both axially outward of said first distribution channel, cooperating to form a first generally tubular extrudate path;
• (g) a portion of the outer wall surface of said annular guide element and a portion of the inner wall surface of said outer die assembly,, both axially outward of said second distribution channel, cooperating to form a second generally tubular extrudate path;
• (h) the axially outermost portions of the inner wall surface of said outer die and the outer wall surface of said inner die cooperating to form a third generally tubular extrudate path, said first and second extrudate paths merging together into said third generally tubular extrudate path at the narrow annular end surface of said guide element;
• (i) first and second inlet streams of elastomeric materials enter said first and second distribution channels and consequently said first and second annular tubular extrudate paths, respectively, and produce said first and second tubular streams which merge together into a combined third tubular stream of elastomeric material in said third extrudate path;
• (j) said individual reinforcing elements being introduced into the interface between said first and second streams of tubular elastomeric material as they merge together simultaneously with said individually and independently guided reinforcing elements into said third tubular stream of elastomeric material thus producing said tubular elastomeric ply that is internally provided with said closely and uniformly spaced array of parallel reinforcing elements.