JPS5827928A - Production of coil spring - Google Patents

Abstract

PURPOSE:To produce a coil spring of stable quality and dimensional accuracy inexpensively by cooling a heated spring blank material quickly while winding the material like coils and hardening the material. CONSTITUTION:While a bar- or wire-like spring blank material 1 is transferred with feed rollers 2, 2, 2, lead screws 3, etc., electricity is conducted to the material from an electric power source device 9 through electrodes 8, 8 in rolling contact with the material 1, whereby the material 1 is heated to a prescribed temp. A mandrel 4 fixes the terminal of the material 1 with a clamping mechanism 5, winds the material 1 and immerses the material into cooling liq. 7 while winding and forming the material like coils thereby cooling the material quickly. Upon completion of coiling and hardening, the coil spring product is removed from the mandrel 4. Since the material is hardened in a restrained state by the above-mentioned method, the deformation by the heat treatment is prevented, and the dimensional accuracy is improved. The products of stable high quality are obtained with the shorter time required from heating up to hardening, with less consumption of energy and under prevention of imperfect hardening and decarburization.

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing a coil spring.

When manufacturing coil springs used in automobile suspension systems, etc., conventionally, a bar-shaped material made of spring #1 is heated and hot-formed into a coil, and then quenched. That is, after the coil is formed, it is removed from the coiling machine and hardened, so it is necessary to heat the coil in anticipation of the temperature drop during coiling in order to maintain it at a predetermined temperature during hardening. However, if the temperature is too high, decarburization occurs and quality deteriorates, and if the temperature is too low due to variations in the handling time from completion of coiling to quenching, complete quenching may not occur. In either case, the quality tends to be uneven because of the low pressure.

Furthermore, since the quenching process is performed while the coil is formed, the cooling rate of each part tends to be uneven, which tends to cause deformation due to heat treatment. Therefore, it is necessary to restrain the steel again during hardening or to straighten it after heat treatment.

The present invention was made under the above circumstances, and its purpose is to be able to set the heating temperature before coil forming lower than conventional methods, and to avoid the need for special measures against heat treatment deformation. The object of the present invention is to provide a method for manufacturing a coil spring that can produce a stable, high-quality product.

The present invention is characterized in that the heated material is rapidly cooled to a predetermined temperature while being wound into a coil, thereby performing coil forming and quenching treatment at the same time.

That is, for example, a material formed into a rod or wire shape from a material such as spring steel is heated to a predetermined temperature indicated by a point & on the S[II] diagram shown in FIG. As shown in , it is rapidly cooled, passes through point 1-1 b (point M8) in a restrained state wound around a core metal, and is cooled to a temperature below point c (point Mt).

According to the above method, since the martensitic transformation, which is the main cause of heat treatment deformation, is restrained by the core metal, it is possible to substantially prevent the occurrence of so-called heat treatment deformation, and the product can be manufactured without straightening treatment. It is possible to improve the first ν degree of the shape. In addition, since the time required from heating to quenching in the trench is short, the heating temperature can be lowered to about 950℃ compared to conventional methods.
The temperature can be lowered by about 50 to 80°C compared to the above, which reduces energy consumption and can effectively prevent incomplete quenching, decarburization, etc., so quality can be stabilized at a high level.

FIG. 2 illustrates an example of a system ji', □t to which the present invention is fully applied.

In the figure, 1 is a raw material, 2 is a feed roller, 3 is a lead screw, 4 is a core metal, 5 is a crank f mechanism, 6 is a tank, 7 is a cooling liquid, 8 is an electrode, and 9 is a power supply device. The core bar 4 is supported by appropriate means (not shown) so as to be able to move in and out of the cooling fluid 7. The electrode '8 is in rolling contact with the material 1 so that the material 1 is energized and heated by the output current of the power supply device 9. In the initial state, the core metal 4 is located above the coolant 7. The material 1 is transferred by the feed roller 2 while being electrically heated via the electrode 8, and when the tip reaches an appropriate position, the material 1 is fixed to the core bar 4 via the flange mechanism 5.

Then, the core metal 4 is immersed in the cooling liquid 7 while winding the coil, and the coil is formed in the immersed state. When the coil forming and quenching processes are completed, the core metal 4 is lifted out of the cooling liquid 7 again, and the completed coil spring is removed from the core metal 4.

The present invention is characterized in that, as described above, the heated rod-shaped or wire-shaped material is rapidly cooled to a predetermined temperature while being wound into a coil. therefore,
Compared to the case where quenching treatment is performed after coil forming, the time required from heating to quenching is shorter, which contributes to energy saving, and also stabilizes quality by completely preventing incomplete quenching and decarburization. Can be done.

Further, since the hardening process can be performed in a restrained state, it is possible to prevent the occurrence of heat treatment deformation, and the straightening process can be omitted, and the shape accuracy can be improved.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the entire cooling process of the present invention, Figure 2 is a diagram showing the entire cooling process of the present invention.
The figure is a system diagram illustrating a device to which the present invention is applied. 1...Material, 2-...Feed roller, 3...Leeds freer, 4...Core metal, 7...Cooling liquid, 8...
·electrode. Applicant's agent Patent attorney Takehiko Suzue 5-

Claims (1)

[Claims] A method for manufacturing a coil spring, characterized in that a heated rod-shaped or wire-shaped material is rapidly cooled to a predetermined temperature while being wound into a coil.