EARLY PROGRESSIVE JUNCTION EXTRUSION SYSTEM

摘要

The invention relates to a method and apparatus for forming a multi-material continuous elastomeric strip, such as a tire tread slab for pneumatic tires. The apparatus comprises a plurality of extrusion means for advancing separate elastomeric materials under pressure through separate flow chambers, a preform die through which the flow chambers converge together to a common junction within the preform die. From the common junction, the multi-material flowstream flows through a preform die exit chamber on to a final die. The configuration of the preform die exit chamber permits the plurality of materials to adhere to each other to establish a material boundary location within the elastomeric strip prior to final shaping in a final chamber formed between a roller and a final die confronting and converging against the rotating roller upon which the elastomeric strip is deposited in the form of a tire tread slab. The placement of the common junction upstream of the final die also aids in allowing the operator to control the location of the material boundary within the extruded strip by controlling pressure or extrusion rate of the different materials within their individual flowpaths.