The influence of strong pressure on springs

The permanent deformation of a spring is when the external force exceeds the elastic limit of the spring, and the rebound height is lower than the original height or exceeds 0.6 mm. After permanent deformation of the spring, the elastic force and stiffness will also change. Therefore, in order to obtain a suitable spring, sometimes the spring is made higher in the design drawings and subjected to strong compression treatment after production to permanently deform and change the spring. Spring specifications that meet the requirements
However, it is conditional to improve the bearing capacity of the spring through strong compression (tension, torsion) treatment. Due to the strong compression process, only when the surface material of the spring generates beneficial residual stress and strong working pressure will it affect compression, and only during strong compression (tension, torsion), the residual stress generated by the spring material and the material with large plastic deformation will increase the elastic limit of the spring. However, there is a certain limit to the elastic limit of each material. Once this limit is exceeded, the material will not only undergo plastic deformation, but also undergo "complete yielding" deformation. Many hot springs strongly compress 0.5 σ b (tensile) materials under complete compression. "Output" deformation
The yield limit of different materials also varies. The yield limit value can only be determined after strength calculation and testing. In addition, the effect of strong pressure (tension, torsion) treatment is closely related to the shape and structure of the spring, as well as the process method of strong pressure treatment. In terms of the shape of the spring, it is impossible to improve its load-bearing capacity through strong compression with a large helix ratio or a small helix lift angle. To achieve the desired spiral ratio and spiral lift angle, it is necessary to design strong pressure. The experiment can be determined. Therefore, it is not just about simply pressing the spring, pulling it, pulling it or twisting it, it can increase the load capacity at once
Except for high stress springs, general compression, tension, and torsion springs do not have the necessary conditions for strong compression (tension, torsion), but the conditions can be achieved through the "pre high" process of springs. Taking compression springs and torsion springs as examples, by maintaining strong pressure on the "pre height" and "pre angle" of the spring, two goals can be achieved: first, to make the spring achieve "compression", "compression", and torsion; The second is that the height or angle of the spring after strong pressure treatment just meets the design requirements
Our opinion on spring pressure treatment is:
When considering the strong pressure treatment of springs, the strong pressure design of the spring should be carried out first to determine whether the spring is suitable for strong pressure treatment
After high-pressure treatment and high stress conditions, the mechanical properties of compression springs and torsion springs will be significantly improved
3. For tension springs with initial tension requirements, the initial tension will decrease or even disappear during the strong tensioning process. This type of spring cannot withstand strong tension treatment. It is not easy to improve the load-bearing capacity of tension springs without initial tension through strong tension treatment
4. Springs operate under high temperature (+60 ° C or above) and corrosive conditions, and are subjected to strong pressure treatment. They can only play a stabilizing role in size and cannot improve load-bearing capacity