| 摘要 |
PURPOSE:To subject coil spring to heat treatment with excellent work efficiency, and to improve the material quality by moving a continuous body of plural coil springs formed by one wire rod, through the inside of a carrying path, stopping it temporarily, and subjecting a pair of coil springs to an electric conductive heating. CONSTITUTION:One wire rod is formed to may coil springs (a) connected to each other by a connecting part (b), by a spring forming part 4, and moved in the right direction through the inside of a guide body 6 from an opening part 9. Stoppers 11 12 provided on the lower part in the guide body 6 are projected into the guide body 6 by air cylinders 13, 14 and pressed against the coil springs (a), and its movement is stopped, and it is stopped temporarily. At the same time, heating parts 16, 17 and 18 contact to the connecting part of the coil springs (a), and coil springs (d), (e) provided between the heating bodies 17, 18 to which a positive voltage has been applied, and the heating body 16 to which a negative voltage has been applied are subjected to electric conduction for a short time and heated to about 300 deg.C. This operation is executed for each pair of the coil springs (a) and the coil springs (a) are heated, the work hardening by a spring working of the wire rod is eliminated, and the strength of the spring is raised.
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