Stiffness of multipoint servo presses: Mechanics vs. control

The accuracy of metal-formed products is strongly affected by the stiffness of the machine used. Therefore, huge efforts to increase moments of inertia and reduce backlash were made in conventional press design. Multipoint servo presses allow for an alternative approach: increasing the position accuracy with respect to the press stroke direction and the ram tilting by controlling deflections. Necessary models and parameters as well as the effectiveness of such a control are discussed in this paper. The proposed method is validated by experiments using a 3D servo press.