The stress of the spring changes with time. This phenomenon is called stress relaxation. How to improve the relaxation resistance of the spring requires improving its elasticity and bearing capacity. In addition to proper heat treatment of the raw materials, strong pressure treatment is also required to improve the relaxation resistance. The specific operation method is as follows:
Increase the load on the spring so that the stress of the outer layer exceeds the elastic limit of the raw material, and plastic deformation occurs, which reduces the spring stress. The spring treated with high load will not appear to resist stress relaxation and can make the spring work for 10 years. The load loss rate is less than 5%.
Methods for handling springs with high loads include:
① Cold and strong pressure treatment: under high temperature, strong pressure for several hours to dozens of hours;
②Heat pressure: Put the spring into a constant temperature furnace, after a period of time, take it out and quickly cool to room temperature;
③Magnetic field pressure treatment: that is, the spring is placed in a bath furnace with a magnetic field around it for treatment;
④Electric pressure treatment: Put the spring between the two plates and heat it for a short time, then take out the quick cooling.
The spring steel wire produced by the above process has better anti-relaxation performance, and the product can be used for shock absorbers, engine valves, etc.
