Finite-elements modeling and simulation of electrically-assisted rotary-draw bending process for 6063 aluminum alloy micro-tube

Bent micro-tubes have been frequently applied in electronics, medical devices and aerospace for heat transfer due to the increasing heat flux in high-density electric packages. Rotary-draw bending (RDB) is a commonly used process in forming tubes due to its versatility. However, the control of forming defects is the key problem in micro-tube bending in terms of wall thinning, cross-sectional deformation and wrinkling. In this paper, a three-dimensional (3D) finite-elements (FE) modeling of electrically-assisted (EA) RDB of 6063 aluminum alloy micro-tubes is developed with the implicit method in ABAQUS. The multi-field coupled behavior was simulated and analyzed during the EA RDB of micro-tubes. Several process parameters such as micro-tube diameter, bending radius, current density and electrical load path were selected to study their effects on the bending defects of the Al6063 micro-tubes. The simulated results showed that the cross-sectional distortion could be improved when electrical current mainly pass through the vicinity of the tangent point in the micro-tube RDB, and the cross-sectional distortion tended to decrease with the increases of current density and tube diameter, and the decreases of bending speed and radius. A trade-off should be made between the benefit and side effect due to electrical current since the risk of wall thinning and wrinkling may increase.