Coil spring is not only a process in spring manufacturing, but also an important process. Winding accuracy plays an extremely important role in the entire manufacturing process. It basically determines the geometric dimensions and characteristics of the spring as well as the utilization of materials.
Spring rolling equipment is generally divided into mandrel spring rolling machines and mandrelless spring rolling machines.
There are two methods: single continuous rolling and multi-continuous rolling. Single rolling is generally used for springs made of strips and oil-sealed springs. Multiple continuous rolls are rolled into a string of coil springs at a time and then cut into individual springs according to size.
In order to obtain the required dimensional accuracy after cold forming, it is necessary to accurately grasp the rebound conditions of springs made of various materials during the forming process when designing springs, designing spring process equipment, and compiling process procedures. There are many factors that affect springback, including the mechanical properties of the material, the winding ratio of the spring, and process equipment.
Rebound is directly proportional to the tensile strength fb of the material and inversely proportional to the elastic modulus e. The larger σ/e, the greater the rebound. When the mechanical properties of the material are unstable, the rebound is also unstable. stainless steel spring
The greater the helix ratio and pitch of the spring, the smaller the plastic deformation, the more unstable the internal stress, and the more difficult it is to control the accuracy of the spring diameter and pitch. Therefore, when rolling springs with large winding ratios and pitches, special attention should be paid to the operation of each process. For example, the reversing speed should be slow, the rolled spring blank should be handled with care, and the movement should be as little as possible before stress relief annealing. For spring blanks with a large winding ratio, they are generally fixed after winding and then removed from the mandrel at the same time after stress relief annealing.