Concept of a control system based on 3d geometry measurement for open die forging of large-scale components

Hot forming processes, especially open die forging, are often used for production of high-performance, large-scale objects. The main benefits compared to, e.g. shape cutting methods, include lower material use and higher stress resistance. Inline process control by 3d geometry measurement is an important part of a cost-effective component production. However, there are no automated control systems commercially available for open die forging, which results in a limited precision of the final component geometry. The main challenges for a control system in said conditions are imposed by the temperature influence of the hot object on the measurement systems as well as limited actuator accuracy for the precise handling of hot, heavy objects. Additionally, the tools used in open die forging are kept simple for financial reasons. Comparable tools for, e.g., drop forging, need to be exclusively made for each new object form and therefore cannot be used for a cost-efficient production of low-quantity components. In this paper, we present a production concept in order to control a hot forming method for large scale, low quantity components. The approach combines an adaptable high-resolution 3d geometry measurement system and an incremental open die forging press for cost- and time-efficient production. Forming simulations will need to be conducted prior to the process to gain access to a large database of possible forming steps to reach the desired final geometry. The control system itself compares the measured geometry and temperature to the simulated ones. Occurring deviations are analysed and a sequence of forming steps is calculated from the database. The necessary forging forces and strokes of the actuating system are extracted from the chosen forming sequence and linked back into the system to achieve maximum precision.