Abstract
KEYWORDS –Tailored blanks, Gate loop, NURBS curve, Variable blank holder force, Servoflexible stamping.
ABSTRACT - The hot forming technique based on servo-flexible stamping that the variable blank holder force combined controlling the servo press slide motion characteristic curves, was studied by the finite element method. The numerical simulations indicated that the deep drawability of tailored blanks of strength steel B pillar can be improved obviously, at the same high temperature, using servo-flexible stamping. Furthermore, a structure of gate loop of tailored blanks of strength steel was designed according to the synchronous engineering of utilizing the servo-flexible stamping, and the parameters of hot forming were discussed by using the NURBS curve to optimize the stamping process characteristic curves. Based on the theorem of power-law in hot deformation with the Zener-Hollomon parameter and plastic work converted to heat, a new analytical model of variable blank holder force was proposed. The simulation suggested that the optimized VBHF by the new analytical model can improve the drawability of gate loop of tailored blanks obviously.