Mechanical and Mathematical Evaluation of the Influence of Wire Mechanical Properties on Helical Cylindrical Compression Springs Wear Resistance

Abstract

A common defect of springs is a decrease in their wear resistance due to changes in the mechanical properties of the wire along its length, particularly the yield strength, including under friction during operation of the spring. According to the springs stress-strain state presented mathematical model, the wire yield strength changes effect on springs wear resistance during contact hardening is investigated. The residual springs deformation dependence graph on the yield strength of its material for different wire diameters is constructed. Dispersion of the spring wire yield strength in the coil according to state standards 9389, carbon steel spring wire can be up to 200–250 MPa. It is established that in this case, the manufactured springs deformation dispersion will amount to 11.76% and exceed the permissible values. For first precision group springs, the permissible deviations for deformation dispersion are ±5%, for second precision group springs, ±10%. The wire change in the yield strength effect graph along the length on the dispersion of spring deformation for a load of 140F3 (F3 is spring compression force when coils come into contact) is constructed. Using the presented technique and taking into account the dispersion of spring deformation depending on the change in the wire along the length yield strength, including due to friction during operation, it is possible to significantly reduce the percentage of defects in the manufacturing and increase helical cylindrical compression springs wear resistance.