Heating schemes and process parameters of induction heating of aluminium sheets for hot stamping

Abstract

Induction heating is one of the most popular metal heating technologies due to its high heating rate and high energy efficiency. This method is suitable for heating workpieces/blanks in different shapes, sizes and materials. Although induction heating of metal sheets has already been investigated by various research organizations and industrial companies, information concerning the induction heating of aluminium blanks is limited. Considering that hot stamping of aluminium sheets for automotive and aerospace applications is currently attracting a lot of attentions, it is timely important to gain more understanding on this technology by conducting in-depth investigations. Especially, investigations are required to address issues relating to the uneven temperature distributions developed in the metal sheets when they are heated, so that optimum designs could be obtained to improve the technology and its applications. This paper presents an in-depth analysis conducted recently for the investigation into heating schemes and process parameters in induction heating of aluminium sheets, mainly using 3D FE simulations, based on a general experimental validation. Different material, coil geometric and power-setting factors were considered during the modelling and analysis to examine their effects on the heating efficiency and developed temperature profiles. It was revealed from the simulations that design features of the induction coils affect the uniformity of the developed temperatures in the metal sheets. It is shown that an optimised combination of the coil design and the power setting could help to achieve higher heating rates, at the same time, also to achieve higher temperature-distribution uniformity. At the end of this paper, a discussion of practical factors that affect applications of induction heating of aluminium sheets for hot stamping applications is presented.