Next Generation of Deep Drawing

Using Smart Observers, Closed-Loop Control, and a 3D-Servo-Press

During this project, a close-loop controlled deep drawing process shall be realized. In contrast to previous approaches, no external actuators will be required. Instead, the additional degrees of freedom provided by a novel forming machine, the 3D servo press, are utilized to influence the process. Furthermore, the use of acoustic emission sensors will be investigated with the objective to eventually replace currently used methods for controlling variables like the flange draw-in.

Motivation

Deep drawing is one of the most commonly used sheet metal forming processes in the industry. Current trends in the automotive sector, as for example the use of higher strength materials, reduce the process window. Combined with variations of incoming material properties, tribological parameters as well as possible wear of the tools, this poses a serious challenge to the robustness of the forming process. In order to guarantee a constant product quality, research projects aim to implement a closed-loop control of the forming process. Up to now, these systems rely on external actuators that are embedded in the tool, causing a dramatic increase in development costs due to the additional time and effort required.

Fertiges Werkzeug eingebaut in Presse — [1] Manufactured tool installed in the press

Methodical approach

The 3D servo press has the ability to perform a vertical ram movement, like conventional presses, but additionally can perform a tilting motion around two axes. A first tool concept has been designed and manufactured; it is depicted in picture number [1], while the further working principle is explained in graphic [2]: Tilting the ram triggers a linear movement of the cylindrical pins, which in turn leads to a compression of the underlying springs. This allows adjusting the blank holder force locally.

Funktionsprinzip eines Werkzeugs — [2] Tool concept to apply local blank holder forces using the orbital ram movement: Tilting of the ram causes a linear movement of the cylindrical pins, which causes a compression of the springs. This allows for locally different blank holder forces.

Acknowledgement

This project is a cooperation project with the University of New Hampshire. In Germany the project is funded by the German Research Foundation (DFG) under the project „Next Generation Deep Drawing Using Smart Observers, Close-Loop Control, and 3D-Servo-Press“ (Project number: 386415239), while the National Science Foundation (NSF) provides funding for the project partner in the United States (NSF – Award Number: 1727490)