Numerical simulation of heat transfer during leaf spring industrial quenching process

Abstract

This study is carried out in partnership with the company CAVEO, manufacturer of leaf springs for vehicles. It concerns the development of a numerical model intended to follow the space-time temperature evolution of a leaf during two processing operations: hot cambering and quenching. This leaf is of a parabolic profile, made of EN-51CrV4 steel (AISI-6150). After austenitization, it passes through a cambering operation to confer it the desired deflection and then a quenching operation. This quenching is carried out in an oil bath to achieve better mechanical properties. The prediction of the temperature during quenching involves determining the heat transfer coefficient between the leaf and the oil bath. This coefficient is determined by quenching, under the same conditions as the leaf, using a standard probe of the same steel. The numerical model is based on the resolution of the transient heat equation by considering the heat loss flows towards the heterogeneous environment (ambient air, press contact and quenching oil). The results obtained by this model give the space-time temperature evolution of the leaf from the exit of the heating furnace to the exit of the oil bath. The numerical results are compared to the experimental profiles obtained through thermographic images throughout cambering and quenching operations. These results are consistent with experimental results.