METHOD AND APPARATUS FOR AUTOMATICALLY PRODUCING COIL SPRING

PURPOSE:To produce a coil spring of desired size without changing the diameter of a steel stock as a starting material by continuously subjecting a steel stock for long size coil spring to respective treatments of hot rolling, cutting, reheating, coiling forming, hardening, and tempering. CONSTITUTION:A steel stock 1 for long-size coil spring having cross-sectiona1 form and size slightly larger than the desired ones is continuously inserted into a heating furnace 3 to undergo heating and the end of this steel stock 1 is crushed by means of a cutter 4, and then this steel stock 1 is fed to a rolling mill 5 and hot-rolled to the prescribed diameter. After fed to a cutter 6 to undergo cutting to the desired length, the steel stock 1 formed into the desired cross section, size, and length is heated in a reheating furnace 8 up to the prescribed temp. and ted to a coiler 10 so as to be hot-formed into a prescribed coil spring stock 1'. Further, the resulting hot-formed coil spring stock 1' is fed, in succession, to a hardening machine 11 and a tempering machine 12 to undergo heat treatment, by which a desired coil spring 100 is formed. By this method, the coil spring 100 having the desired size within the prescribed range can be continuously and automatically produced without changing the diameter of the coil spring steel stock 1 as a starting material.