Influences of mandrel types on forming quality of TA18 high strength tube in numerical control bending

Abstract

Abstract In order to improve the forming quality and limit of tube numerical control (NC) bending, it is necessary to select reasonable mandrel types. A finite element (FE) model of the whole process of TA18 high strength tube in NC bending was established based on the platform of ABAQUS, and its reliability was validated. Then, using the model, the effects of no mandrel, cylindrical mandrel, hemispherical mandrel and ball-and-socket mandrel on the distribution of tangential stress/strain, wall thinning and cross section distortion were studied. The results show that the shape, size and location of the tangential stress/strain distribution have no obvious difference for the NC bending without mandrel and with three mandrel types. For the bending without mandrel, the wall thinning is the smallest, and the cross section distortion is the largest, which exceeds the requirement of aviation standard. Three types of mandrel have no significant effect on the wall thinning, while the hemispherical mandrel is the most conducive to control the cross section distortion.