Predictions of Optimum Forming Conditions in Press Forming using TAGUCHI Method and FEM Simulation

Abstract

Developments with short-term and lower cost are strongly required for shorten products life cycle. In press forming, many trials are needed to design of mold and to decide optimum forming condition. For these problems, FEM simulation is used to predict the result of processing instead of real test. The other side, TAGUCHI method (robust design) in also used to decide optimum processing conditions with narrow dispersion. Generally, production conditions have some factors such as tolerance, order entry, date of delivery, material price and machining cost. In the actual production stage, there're many kinds of suitable production conditions, e.g. accuracy priority, total cost priority and so on. Therefore, the optimum forming condition is changed by the order of priority. In this study, spring back of warm press forming of magnesium alloy plate is intended. First, material property of magnesium plate and friction coefficient of lubricants (Teflon sheet and two types of oil) are investigated to use for FEM calculation data. Next, spring back simulations performed under various processing conditions are decided by TAGUCHI method. Average spring back and its dispersion are estimated by TAGUCHI Method with the results. Then, productivity such as accuracy, total cost, total working time and non-defective unit rate are estimated at all forming condition combination. Finally, optimum processing conditions are decided each priority. And actual spring back test results are performed to confirm the predictions. It is concluded from the result that (1) The proposed method predicted optimum processing conditions effectively in each priority and (2) The predicted results conformed to the results of the actual spring back test.