Development of Forming Temperature Curves for Warm Deep Drawing Process Under Non-isothermal Conditions

Abstract

Temperature is the main effective process parameter in the warm deep drawing (WDD) process to improve the formability of light-weight engineering materials, and this feature requires the accurate measurement and assessment of temperature for process stability. In this study, an evaluation of the WDD process was conducted according to the forming temperature curves (FTCs) characterized from work piece temperatures instead of tool temperatures, as usual. To achieve this goal, a special index material was developed to accurately obtain FTCs from the work piece material under closed and heated tool conditions. The differences of temperature on work piece material are required to define temperatures by curves. The characteristic behavior of these curves was investigated under non-isothermal WDD of AA 5754-O. In the experimentation stage, the process parameters, namely FTC, blank holder force and punch velocity, which assure successful deep drawability, were determined according to the failure-free cups by analyzing wrinkling and tearing conditions and minimum cup height parameters as output parameters. As the next step, optimum conditions were investigated by evaluating the cup volume and spring-back parameters. As a general conclusion, approximately 330°C in the flange–die radius region and 100°C in the cup wall-punch bottom region are the ideal optimum temperatures for the warm deep drawing process.