Reducing Uncertainty in Shunt Damping by Model-Predictive Product Stiffness Control in a Single Point Incremental Forming Process

Abstract

The stiffness of metal formed products strongly affects the dynamic behavior of structures in which they are integrated. Forming processes underlie short and long-term variations which cause the stiffness to be uncertain.In the application of resonant shunted piezoelectric transducers for vibration attenuation, uncertain stiffness may cause significant reduction in the vibration attenuation performance due to imprecise tuning. In the past, large efforts were made to control one or more geometrical feature of products while weightier features that cause uncertainty have not been addressed.In this paper, a single point incremental forming process of a membrane-like spring element on a servo press with a 3 degrees of freedom drive system is investigated. This spring element is used in a beam support for lateral vibration attenuation with resonant shunted transducers as well as axial buckling stabilization.To reduce uncertainty caused by process variations, an offline closed-loop control of product stiffness is presented. Different product and forming criteria are integrated into a control approach based on an optimization routine. By making use of a model-based prediction of the product properties, the approach shows how to realize a multi-objective control.

Targeted residual stress generation in single and two point incremental sheet forming (ISF)

“…These observations open new windows for ISF to be applied as an alternative surface treatment and integrated forming approach. These observations in combination with control of the ISF process can be used to achieve localized properties on a global scale, for example, localized hardening in the selected areas or control over radial or tangential residual stress components to achieve stiffness in the desired direction, for examples, as required by the disk springs used in the vibration actuators [24].…”

Methods and Technologies for Mastering Uncertainty

“…3.6.3. By having the complexity of the actuators in the machine, new processes can easily be developed [58,160], and passive standard processes, such as deep drawing, can be enhanced [51].…”

“…Uncertainty, which becomes visible in deviation of the predicted and measured product property, is taken into account after each step. This results in a closed control loop [160].…”