Method of manufacturing a coil spring having an oblique and straight axial line
AssigneeNHK Spring Co., Ltd.
InventorTakeshi Furuse
Life of this patent
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Abstract
In a cold coil forming process, a pitch control tool is moved in synchronism with the displacement of the outer diameter control roller so as to form a coil spring having a straight and oblique axial line, and, at the same time, maintain a pitch of the coil wire substantially constant substantially over an entire length thereof. Thus, the method of the present invention can be implemented by using a conventional coiling machine only if the outer diameter control roller and the pitch control tool can be adjusted as required by the present invention. In particular, the pitch of the coil spring can be kept constant over each turn of the coil wire without regard to the variation in the radius of curvature of the coil spring.
Claims5
A method of manufacturing a coil spring having a straight and oblique axial line, comprising the steps of:
- feeding a rod member along an axial line thereof;
- applying an outer diameter control roller to said rod member from a first direction which is substantially perpendicular to said axial line;
- applying a pitch control tool from a second direction substantially perpendicular to both said axial line of said rod member and said first direction;
- displacing said outer diameter control roller cyclically so as to form a first section having a relatively large effective radius of curvature and a second section having a relatively small effective radius of curvature in each turn of said coil spring;
- and
- displacing said pitch control tool in said second direction in synchronism with the displacement of said outer diameter control roller so as to maintain a pitch of said coil wire substantially constant substantially over an entire length thereof.
Dependencies are inferred from the claim text.