Impact of the process velocities on the quality of free-form bent parts

Abstract

The geometrical accuracy of the bent components as well as their surface quality are crucial parameters to evaluate the feasibility of a bent geometry in free-form bending. In the process the deformation of the part is obtained by displacing and rotating a movable bending head with respect to the fixed holder with a given relative velocity with respect to the feed velocity. High process velocities have a beneficial effect on the realisation of bending radii and angles, but induce high local solicitations on the semi-finished part, which can result in surface defects like indentations and buckles. In this work the impact of the bending head velocity as well as of the feed velocity on the bend’s stability and the arising of indentations is investigated. Experimental tests with different head and feed velocity are conducted on mild, moderate and severe bends keeping the same kinematics. The resulting bending radii, angles and surface defects are evaluated. The results allow to identify the parameters having the highest influence on the quality of bent profiles and to propose a compromise between geometrical stability and surface quality.