Robustness for Intelligent Tooling While Forming Shallow Aluminum Pans

Abstract

This study examines the robustness of stamp forming tooling. An oval pan was formed using tooling that included a flexible blank holder, active draw beads, and closed-loop control of both wrinkling and local punch forces. The results were compared to open-loop tests using the same tooling and earlier work that utilized tooling that produced similar pans but included a rigid blank holder. For the current study, robustness was defined as the ability to delay wrinkling or tearing. A description of the tooling design process is provided as well as a synopsis of the development of the control system for the tooling. Open-loop and closed-control tests using AL 6111-T4 blanks were performed in order to evaluate the ability to reject process disturbances and demonstrate improved robustness of the tooling. During open-loop tests, the current tooling was shown to be more robust than the earlier tooling with the rigid blank holder. Control of wrinkling eliminated one form of part failure while closed-loop control of local punch forces significantly improved the robustness of the tooling by delaying tearing.