Method and apparatus for forming an apex filler and/or applying an apex filler to a bead ring sub-assembly

A method of forming an apex filler and also applying the apex filler onto a ring sub-assembly, said method comprising:

• mounting a ring sub-assembly on a roller chuck, the ring sub-assembly having a substantially annular inner periphery adapted to be contacted by roller members on the chuck, a substantially annular outer periphery and a pair of laterally spaced sidewalls joining the inner and outer surfaces;
• extruding a substantially linear elastomeric strip having an apex, a base and a pair of sidewalls converging between the base and the apex such that the elastomeric strip is narrower at the apex than at the base;
• engaging the sidewalls of the ring sub-assembly and the sidewalls of the elastomeric strip with a pair of opposed, driven frusto-conical rollers, the base of the elastomeric strip being forced into contact with the outer periphery of the ring sub-assembly to effect at least temporary tacking therebetween;
• pressing the elastomeric strip between the frusto-conical rollers while causing rotation of the ring sub-assembly and the base of the elastomeric strip at a first linear speed, the apex at a second, and greater, linear speed and the sidewall of the elastomeric strip at a linear speed substantially proportional to the distance from the base to the apex,
• thereby elongating the elastomeric strip in a radially differential manner as determined by the frusto-conical rollers to form an annulus circumferentially about the ring sub-assembly with the base of the elastomeric strip having a linear dimension equal to the circumference of the outer, substantially annular periphery of the ring sub-assembly and the apex of the elastomeric strip having a linear dimension sufficient to form a substantially stress-free annulus;
• and,
• splicing the ends of the elastomeric strip to close the annulus.