Study on the influence of mandrel type on copper tube rotary draw bending

The process of rotary draw bending is a versatile, cost-effective and precise method for thin-walled copper Air Conditioning and Refrigeration (ACR) tube. Requested in industrial application for ACR tube, the wall thinning and the fattening of the cross-section are two major formability assessment factors. Mandrel type influences both of the formability assessment factors directly. In this paper, a 3D elastic-plastic Finite Element Method (FEM) model of the rotary draw bending is established using the dynamic explicit FEM code LS-DYNA. An experiment has been carried out to verify the FEM model. The influences of three basic type of mandrel on stress distribution and sectional deformation during the bending process have been investigated, and role of geometry parameter of complex-surfaced and ball-and-socket mandrel in wall thinning and sectional degradation has been revealed. The results indicate that wall thinning and sectional degradation can be precisely under control by choosing mandrel type and setting key geometry parameters.