At present, the manufacturing of spiral drawing and torsion springs is except that a few manufacturers have imported CNC spring forming machines from abroad to automatically form and process various types of stretching and torsion springs. The vast majority of manufacturers still use the traditional processing method to manufacture. Here is a brief introduction.
1. Spiral extension spring. The process is basically the same as that of the spiral compression spring, but the difference is the end hook ring processing. The forming method of the tension spring is as follows:
1) In the same way as the spiral compression spring, the stress relief annealing is carried out after winding and forming, and then the hook ring is processed. Except for the special shape of the hook ring or the spiral tension spring with high initial tension, most of the springs are rolled by automatic spring coiling machine, except for the special shape of the hook ring or the spiral tension spring requiring high initial tension.
2) It is rolled with straight tail spring winding machine. It is a vertical spring winding machine with vertical mandrel. After rolling, the stress relief annealing is carried out, and then the hook ring is processed. There are many kinds of end structure and processing methods of spiral tension spring. The commonly used ones are: the small spring is processed manually with special tools or special process device; the ordinary spiral tension spring is processed by manual or automatic operation method with hook or mold; For the tension spring of long arm hook ring, the material length required for the drawing hook shall be reserved during winding, or the number of turns required for processing shall be reserved after winding, and the two ends shall be straightened with straightening tool, and then the hook ring shall be bent with special tools. The process specification of stress relief annealing is as mentioned above. After the spring is rolled, the stress relief annealing is carried out first, and then the hook ring is cut off and processed. After the hook ring is processed, generally, the stress relief annealing is conducted for 1-2 times. In order to prevent the change of the relative angle of the two shackles, the temperature of the processed shackles should be 20-30 ° C lower than that of the rolled ones during stress relief annealing. Generally speaking, the spiral tension spring is not shot blasting and tension treatment.
2. Helical torsion spring. The process is basically the same as that of spiral compression and tension spring, but the difference is also the end processing. In the case of small batch production and complicated torsion arm, most of them are formed by manual or semi-automatic mandrel coiling spring method, and then the torsion arm is processed according to the drawing requirements with the fixture. In mass production, it can be rolled on the straight tail spring coiling machine and the special machine for torsion spring. If the torsion arm can not be completed according to the drawing, it can be processed with tooling and fixture according to the division of labor. According to the characteristics of spiral torsion spring, the following two points should be paid attention to in design and manufacture
1) The end torsion arm of spiral torsion spring should be bent once in manufacturing to avoid machining defects and correction and shaping. The second stress relief annealing should be carried out after the torsion arm is processed;
2) At present, most of the spiral torsion springs are dense rings, so there is a similar pressing force between the spring coils which is equivalent to the initial tension of the tension spring. When the load and the rotation direction are the same or the number of turns increases, this tendency increases. In addition, it also brings difficulties to the surface treatment process. Therefore, in the design and forming, a little gap should be left between the coils. In mass production, under the condition of conditions, the manufacturer can use hydraulic and pneumatic methods to process the spiral drawing, torsion spring expansion, bending, hook and other processes.