Analytical prediction of wall thickness reduction and forming forces during the radial indentation process in Incremental Profile Forming


Incremental Profile Forming (IPF) is a recently introduced flexible tube forming technology, which allows the manufacture of tubular structures with varying cross-sectional geometries along the longitudinal axis of the part. The process is characterized mainly by the operation of several tools, laterally moving, indenting and deforming the initial tubular workpiece. In kinematic IPF the use of universal tools with hemispheric tool shapes allow the flexible manufacture of highly complex parts since its geometry is mainly defined by the tool motions. Thinning of the tube material in the tool contact region is typical for kinematic IPF forming processes. In order to predict the forming behavior, an analytical model is developed taking the tube dimensions, the tool geometry as well as the tube material into account. Based on the predicted forming behavior, the process force during the indentation process is also determined analytically. The validation of the analytical model is performed by experimental and numerical investigations. After the geometrical analysis of the tool contact region and the tube deformations, the plastic strain distribution in the forming zone is described, in order to predict the reduction of the wall thickness. Furthermore, the analytical model allows the prediction of the forming force course over the indenting depth for various process parameters.
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