Coil of tapered wire

Abstract From the Canadian patent

A coil of taper wire for forming coil springs formed by winding substantially in concentric loops a quench-hardened and tempered taper wire having a successive arrangement of taper wire segments each consisting of a thick section, two thin sections and two taper sections connecting the thin sections to the opposite ends of the thick section, respectively. The taper wire is subjected to a preforming action immediately before being wound in loops on a winding drum to form, plastic bends in the thick section and plastic bends of a radius of curvature greater than that of the plastic bends in the thick sections so that the taper wire is wound substantially uniform, concentric circular loops on …