| 摘要 |
<p>PURPOSE:To provide a producing method for spiral spring by which the production of defective products is suppressed and the automation of production is facilitated. CONSTITUTION:When the thickness of a long plate like hardened wire 30 having an almost uniform cross-sectional shape is thick, by using a long heating coil 31 having length L1, the quenching length of the end part of the wire 30 is made long, the wire is wound around a core metal 32, and the boundary between inner quenched part and non-quenched part in the vicinity of the core metal 32 is positioned on a position whose radius of curvature is comparatively large to produce the spiral spring. Accordingly, since a crack is hardly occurred on the boundary between quenched and non-quenched parts in the vicinity of the core metal, the production of defective products is suppressed, the material is efficiency utilized and, moreover, the automation of production of spiral springs is facilitated.</p> |
