Warm Press Forming of Magnesium Alloy with Assist of Direct Cooling and Induction Heating

Abstract

Warm press forming is very effective to improve draw ability of magnesium alloy. Generally, increasing the temperature of metal makes it soften. In warm press forming, heating the blank on the die decrease its deforming resistance. On the other hand, cooling the blank on the punch increases its tensile strength of sidewall of the product. Draw ability is increased by these methods. But there is a forming limit in this process. Because, excessive high heating of the die increase the temperature of the sidewall, then its strength is decrease. Similarly, high punch speed increase the temperature of the sidewall, then draw ability is decrease. In this study, warm press forming of magnesium with assist of direct cooling and induction heating is investigated. Sidewall of the product is directly cooled by water. Temperature of the blank on the die is increased very quickly and locally without increasing the temperature of the side wall by induction heating. The optimum condition and its performance of this forming system are fisrt investigated by FEM simulation. And real press test is performed for confirmation. It is concluded from the results that (1) Warm press forming with assist of direct cooling and induction heating can increase draw ability from D. R. 3.0 to 4.0 and D. R. 2.4 to 3.2 each punch speed 2.5 and 10 mm/s respectively, (2) Scheduled induction heating power that decided using FEM simulation improves the thickness distribution of sidewall of drawing cup.