Cutting method to be applied to producing helical springs by cold-forming thick high-strength wire

Abstract

A cutting method to be applied to producing helical springs by cold-forming a thick high-strength wire having a tensile strength in the range of 1765 to 2157 N/mm.sup.2 and a diameter in the range of 8 to 16 mm on a coiling machine, and then the wire is cut at the end coil of the coiled portion to provide a helical spring. A predetermined range about a position on the wire at a distance coresponding to the length of wire in the helical spring from the free end of the wire fed to the coiling machine is heated to a temperature within a predetermined temperature range. Therefore, the end coil of the helical spring is formed by the heated portion of the wire, and hence the helical spring is cut off the wire at a position in the heated portion. Accordingly, the helical spring can be cut with the cutting mandrel and the cutting blade or the coiling machine by a small shearing force and, since the cut end is only a portion of the end coil of the helical spring, the mechanical properties of the helical spring are not affected by cutting in the least.

Dependencies are inferred from the claim text.