Closed loop control of the 3D bending process

Abstract

Mechanical properties of the incoming material have a major effect on the shape stability of 3D wire bent products. The study of the wire straightening process prior to final bending showed that it could efficiently be used to control the mechanical properties as well as straightness of the wire. The core of the stabilization algorithm is a slightly modified Prager's flow rule [1,2] considering material hardening or softening as a result of accumulated small reverse plastic strains. Flow stress calculation of the incoming material is based on the measured transverse roller forces. The obtained data define the needed repositioning of the straightening rollers. The new settings stabilize the wire material properties, which reflect in the shape of the 3D bent product.