Stress and Strain Analysis of Spring Manufactured by Coiling Pin System

Abstract

One needs to consider the optimization for the decrease in the number of effective coils and the increase in the pitch of a spring not only in the design but also the manufacturing because of causing higher design stress due to weight reduction with all automobile parts. In this study, the simulation of coiling process with coiling pin system was carried out by the dynamic explicit method with finite element analysis, LS-DYNA, and revealed the stress and strain distribution caused by the coiling process in the cross section of the spring wire. As a result, the neutral axis of the spring wire moved toward the outside of the coiling because this movement was caused by the axial compression during the process. However, there was some residual tensile stress after the coiling. This suggested that the spring endured in severe plastic deformation during the coiling process, while the residual tensile stress effected the fatigue less compared to the spring manufactured by lathe system coiling, which caused more residual compressive stress due to the axial tension during the process. It should indicate that some post process to any spring made by coiling pin system might be needed for less the stress.