Method for dynamic analysis of a servo-spindle press: Presentation held at 6th Forming Technology Forum, 19th - 20th September 2013, Herrsching, Germany

Servo-press machines are leading the development of new technologies in the steel shap-ing industry. This new generation of press machines contributes to greater production flexibility and presents a higher dynamic power, i.e. less rotational inertia, allowing for significantly higher acceleration of the movement of the machine. This has resulted in innovative approaches to the dynamic behaviour of the ser-vo-press. One example is the reduction of noise emission during the cutting operation. Because of a signifi-cant reduction in the ram speed during cutting, the mechanical stress and consequently the effect of the cut-ting stroke are reduced. Another example is the extension of forming technologies for steel deep drawing by superimposed oscillations with rapid change of direction. Initial investigations, carried out by Fraunhofer IWU, show that the dynamic features of the servo-spindle press influence the quality of the workpieces. Here, in order to explore the potential for innovative technologies, we perform dynamic studies. We analyse mass and stiffness distribution and different boundary conditions such as machine setup or external loads using a linear elastic FE model. We evaluate the analyses of nonlinearities and damping properties by means of experimental tests under static and dynamic loading. Moreover, we use the results of experimental inves-tigations to validate the developed models and to evaluate their complexity. In the final discussion of current research, we focus on the modelling of metal forming processes with high process dynamics, which illus-trates the need for the analysis to consider elastic interactions between the process and the machine. In addi-tion, for users of servo-spindle presses, productivity, durability and process reliability are important criteria when making investment decisions. For this purpose, it is important to know the real load cases when de-signing the linear guidance. Forming technologies that have dynamic process kinematics require a press construction with a high stiffness and positioning accuracy. Therefore press machines need to be analysed and optimised with respect to different stiffnesses and mass distributions for quasi-static and dynamic form-ing technologies