Hydraulic Die Cushions in Deep Drawing Presses: Analysis and Optimization Using Coupled Simulation

The scientific paper proposes a method to analyze and optimize the drawing press and the deep drawing process with a virtual model. It focuses on hydraulic multi-point die cushions since they offer a wide range of possible adjustments and a high potential to increase production quality and efficiency. The operator can apply individual die cushion cylinder forces to the blankholder which enables the control of the forming process and manual die spotting can theoretically be reduced to a minimum. Utilizing the virtual model can improve the drawing press’ behavior and significantly reduce the set-up time for drawing presses during try-out of new tools or when tool sets are transferred to a different machine. The paper presents a system simulation model of a deep drawing press including its mechanics, hydraulics, and control. It serves as a basis for developing an advanced control system which improves system performance with potentially higher slide speeds, and therefore, a more efficient production. Another aspect in the paper is the development of a coupled simulation consisting of the machine model and a process model. This includes the elasto-static as well as the dynamic behavior of the drawing press and allows for simulations with the highest possible level of detail. The model was used to determine individual set forces for the die cushion cylinders which allowed for the production of sound quality parts without manual die spotting.