To provide a spiral spring manufacturing method in which inter-spring wire space can be freely set.
A conch-shaped difference in level 21 is formed on a nearly conical body 20 to make a conch-shaped mandrel 3. A spring wire 1 in a prescribed shape is wound on this conch-shaped mandrel 3, forming a conch-shaped intermediate product 4 and compressing it in the axial direction to produce a planar spiral spring. By adjusting a distance in the radial direction of the difference in level 21 formed on the mandrel 3, inter-spring wire 1 space 2 of the spiral spring can be set. In compressing the intermediate product 4, the pressurization is performed with two molds 5, 6. On the pressurizing faces 7, 8 of the molds 5, 6, there are formed grooves 9, 10 for storing the spring wire 1, controlling deformation at the time of the compression and prescribing the inter-spring wire 1 space 2. Spring-back of the intermediate product 4 may be suppressed by ruggedly combining the pressurizing faces 7, 8 of the molds 5, 6.
Yoshiaki Naito
Cui Shu Tetsu