Process Control of Forming Processes to Compensate Temperature Induced Friction Changes

• Main Authors: Heingärtner, Jörg, Veldhuis, Mark, Kott, Matthäus, Hora, Pavel
• Format: Conference Proceeding
• Language: English
• Subjects: deep drawing; draw-in measurement; process control
• ISSN: 2351-9789; 2351-9789
• DOI: 10.1016/j.promfg.2020.04.164

Forming processes undergo large temperature changes after production start e.g. after a tool exchange or production stops; usually tool temperatures increase due to friction and forming energy. These temperature changes lead to changed friction behavior during production runs. There are two basic approaches to account for these changes. Either a very robust process, which will only require slight adjustments of the process parameters through the operator, or a process control system that will automatically adapt the process to the instantaneous friction conditions. The first approach will not make full use of the raw material due to large safety margins of the process, which is a key requirement to minimize part cost. Therefore, process control systems to account for temperature induced friction changes were implemented in two different forming processes during the ASPECT project. One of the demonstrator parts is a specifically designed part from Philips, the other one is an automotive part from Opel. The approach followed to implement the control systems is based on metamodels generated using the results from numerical simulations and a re-calibration in production. These metamodels are evaluated through an optimization algorithm to calculate the required process parameters. As state variables, the draw-in and several temperatures are measured in-line. In both processes, the binder force is the parameter that is adapted by the control system.