Motion profile calculation for freeform bending with moveable die based on tool parameters

Abstract

In freeform bending the desired geometry is created by defined movements of the die while a continuous feed takes place. To compensate the differences and variations in properties of the semi-finished product, the motion profile has to be adjusted. Currently, this calibration is done once before the manufacturing process of a certain profile. Therefore, numerous iterations consisting of bending and measuring certain radii based on a default motion profile are performed. The measured data is subjected to a curve fit, which is not sufficiently suitable for all profiles and materials setups due to the fixed predefined function that is used. Furthermore, the tool setup is not taken in account. This results in wrong kinematics and production rejects. In this work, an enhanced geometrical model is introduced which incorporates tool parameters - such as distances, clearances and positioning aspects - as a starting point for further calculations. Furthermore, different calibration methods are tested and compared to each other using FEM simulations to fit the calculated curve to the actually used specimen. This work establishes the basis for further compensation and calibration strategies in order to improve the handling of varying properties of semi-finished products within the freeform bending process.