New digitalization approaches in forging technology

Forming technology has a high potential for digitalization in the course of Industry 4.0. In particular for bulk metal forming, new approaches to digital process monitoring, process control and workpiece tracking can make a major contribution to improving the quality of pressed parts. Therefore, the Institute of Metal Forming Technology (IFU, University of Stuttgart) has elaborated contributions to the digitalization of forming processes in various research projects. The first digitalization approach in this paper refers to hot forging, since these processes are barely designed with data gathering systems to get correlations of quality fluctuations on the pressed parts. To demonstrate the benefits a cyber-physical forging process chain with an integrated workpiece tracking system was developed. The real-time data analysis coupled with an Artificial Neural Network-based process control system was able to foresee, prevent, record and if necessary separate rejects after pre- and final forging. A further approach presented in this report applies to cold forging. Due to the so far missing process monitoring in cold forging, an additively manufactured cold forging tool with integrated functionalities was developed. As functional features a close contour fiber sensor for temperature measurement, a cooling system and a lubrication system were integrated into the die. This cold extrusion die was tested experimentally under serial production-like conditions. Thereby the integrated functional features for process digitalization were used and gathered data were recorded. The final digitalization approach presented comprise a thin-film sensors applied onto the surface of cold forging tools. Therefore, a new mechanical tool for a can backward extrusion process was designed by IFU Stuttgart to integrate a smart punch equipped with a multifunctional thin-film sensor system by the Fraunhofer IST as well as a related data logging system built up by Hahn-Schickard. The presented sensor layout should enable the temperature measurement at selected points on the punch surface to investigate the specific temperature increase due to the forging operation. All approaches presented in this paper enhance the possibilities of digitalization in forming technologies, especially the data gathering and monitoring in hot and cold forging processes.