Coextrusion apparatus and method with rotating cord guidance

Coextrusion apparatus having a central axis for producing a generally tubular elastomeric ply made up of at least first, second and third coaxial streams of elastomeric material which merge together at an annular extrusion orifice;

• said apparatus including:
• a) stationary first channel forming means for forming an inner flow channel for delivering the first stream of elastomeric material to the extrusion orifice;
• b) stationary second channel forming means for forming an intermediate flow channel for delivering the second stream of elastomeric material to the extrusion orifice, said second channel forming means being located concentrically about said first channel forming means;
• c) stationary third channel forming means for forming an outer flow channel for delivering the third stream of elastomeric material to the extrusion orifice, said third channel forming means being located concentrically about said first and second channel forming means;
• d) an inner guide element rotatably mounted between the stationary first and second channel forming means for delivering a plurality of individual reinforcing elements in a first helical pattern to the annular extrusion orifice for introducing into the interface of the merging first and second streams of elastomeric material;
• e) an outer guide element rotatably mounted between the stationary second and third channel forming means for delivering a plurality of individual reinforcing elements in a second helical pattern opposed to the first helical pattern, to the annular extrusion orifice for introducing into the interface of the merging second and third streams of elastomeric material, with the second stream of elastomeric material separating the first and second helical patterns of reinforcing elements;
• f) means for rotating said inner and outer guide elements in opposite directions with respect to each other;
• and
• g) means for positioning discharge ends of the first, second and third channel forming means and discharge ends of the inner and outer guide elements, at an imaginary circle which lies in a plane which extends generally transverse to the axis of the coextrusion apparatus, whereby said first, second and third streams of elastomeric material and the first and second pluralities of reinforcing elements substantially simultaneously merge together at the extrusion orifice.