Abstract:Sheet metal forming is prone to fracture, wrinkling and poor dimensional and shape accuracy.Based on the servo press, a closed-loop control system of independent loading with flexible and variable blank holder force was studied.The cylindrical workpiece was selected as the simulation object, and the simulation results of the cylindrical workpiece under different fixed values and variable blank force were analyzed by using the finite element software.The optimal blank holder force curve and the curve of the stamping load changing with time of the forming cylindrical workpiece were compared and loaded into the control system of the device, so that the blank holder unit and the sheet metal were always in the fitting state.The closed loop system controlled the forming process of stamping through the flexible beading device with different motion modes, such as variable load and variable stroke, and flexibly controlled the beading force and the load of punching die, so as to adapt to the characteristics of different deformation stages of parts.Experimental results show that the system can maximize the sheet metal forming performance, not only prevent the sheet thin in the tail of the fold and the workpiece tension, but also can improve the sheet deep limit.