Triple-action forming technology to increase the limiting drawing ratio in the deep drawing process

This study proposes a novel technique for increasing the limiting drawing ratio (LDR) in the deep drawing process. This work uses “triple-action forming (TAF)” as a new technique to enhance LDR, achieving an LDR of 2.40 for stainless steel JIS and SUS304. The TAF consists of three sequential steps with a constant blank holder force of 3 kN. The first step involves deep drawing with a punch diameter of 30 mm. In the second step, we used a smaller punch diameter of 25 mm. The third step is going deep down with a punch diameter of 30 mm until the end of the die cavity. TAF reduces the intensity of material flow during deep drawing, which results in a delay in cup wall stretching and fracturing as a result of the reduced friction. The TAF approach offers a notable edge over alternative deep drawing techniques, such as multi-step deep drawing and temperature-based forming, due to its ability to effectively enhance the LDR. These process parameters are determined before experimentation through precise finite element simulation. Validation is shown through deep drawing experiments on JIS and SUS304, conducted using FE simulations with the Y-U model and Yoshida 6th yield function.