Nhk Spring Co., Ltd.

Takeshi Furuse

Shinichi Nishizawa

Senri Moriyama

Hideki Okada

Takuya Sato

Yuichiro Yamauchi

Takashi Yajima

Ryo Tanaka

Katsuyuki Nishioka

Fang Dai

Daiki Hagiwara

Yusuke Kumagawa

A coiling machine includes feed rollers for moving a wire, a wire guide, a first forming roller, a second forming roller, a pitch tool, a cutting mechanism, and a support mechanism for supporting the wire. The cutting mechanism includes a cutting rotor. The wire coming out of the wire guide is formed into a helical shape by the first forming roller, the second forming roller and the pitch tool. After one coil spring of a predetermined length is formed, the wire is cut by moving the cutting rotor in the radial direction of the wire. The cutting rotor cuts the wire supported by the support mechanism in the radial direction of the wire between the second forming roller and the pitch tool.

Coiling machine, method for manufacturing coil spring, and coil spring

According to one embodiment, a coil spring includes a wire rod with a first end and a second end. The wire rod includes a round section portion including a round first cross section perpendicular to a longitudinal direction of the wire rod, a quadrangle section portion including a quadrangle a second section perpendicular to the longitudinal direction, and a variable section portion formed between the round section portion and the quadrangle section portion of the wire rod. The cross section of the variable section portion varies from circular to quadrangle from the round section portion to the quadrangle section portion. The end turn part of the coil spring includes the quadrangle section portion. The width and thickness of the second cross-section are smaller than the diameter of the first cross-section. The area of the second cross section is smaller than the area of the square inscribed in the circle of diameter of the first cross section.

Coil spring

According to an embodiment, a coil spring includes a wire rod having an end and the other end. The wire rod of the coil spring includes, with regard to a section of the wire rod, a round section portion of an effective spring part, a square section portion in which the section is substantially square, and a taper portion. The square section portion includes an end turn part. A length of each side of the section of the square section portion is less than or equal to a square root of &#xbd; multiplied by a diameter of the wire rod of the round section portion. In the taper portion, from the round section portion to the square section portion, the section changes from a round shape to substantially a square shape, and a sectional area is decreased.

A coiling machine includes a material guide, first pin, second pin, pitch tool, cutting tool, heating device, temperature sensor, and controller. A material is bent between the first pin and the second pin to form an arc part between the first pin and the second pin. The controller select control data corresponding to the temperature of the material from a plurality of control data corresponding to a processing temperature. Then, the positions of the first pin and the second pin are controlled such that a radius of curvature of the arc part increases when the temperature of the material increases, and the position of the cutting tool is controlled such that a gap between the center of curvature of the arc part and the cutting tool increases.

Coiling machine and manufacturing method of coil spring

A method for heat treatment of a coiled spring includes cold forming a coiled spring, annealing the coiled spring after the cold forming, thereby removing of residual stress generated in the cold forming, in which the annealing is performed by electric resistance heating.

Method for heat treatment of coiled spring

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.

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Yokohama, Japan

Takeshi Furuse