Deep Drawing with Superimposed Low-frequency Vibrations on Servo-screw Presses

Abstract

The power train of a modern servo-screw press with low rotational moment of inertia provides higher dynamics and a new kind of flexibility in forming and stamping processes compared to conventional servo presses. In this paper a new technology for deep drawing on servo-screw presses called cushion-ram pulsation is described. It uses superimposed low-frequency vibrations between 10 Hz and 50 Hz at the cushion and the press ram. For deep drawing operations, the high tensile stresses in the frame of cylindrical cup usually lead to a reduction of material thickness. Thus, and due to the lack of work hardening, fractures frequently occur in the punch radius. The process developed here shifts critical loads to higher drawing ratios by decoupling the drawing operation and the prevention of wrinkles. A high frequency of the cushion-ram pulsation is necessary to allow high productivity. Technological results will be increasingly determined by the machine.

Influence of Press Ram Pulsation on Deep Drawability of Dual Phase Steel Sheet

“…* corresponding author; e-mail: olguner@gantep.edu.tr Kriechenbauer et al [3] described a new technology for deep drawing on servo-screw presses, called "cushion-ram pulsation". In their study, the effects of superimposed low frequency vibrations on deep drawability of DC04 steel sheets, with 10-50 Hz at cushion and press ram, were investigated.…”

Deep Drawing with Local Hardening on Digital Multi-axis Servo Press

“…The material behavior at the moment when the stroke is interrupted [3,4] or the deformation caused by alternating tension-compression is also examined [5]. Numerous publications reported on the use of state-of-the-art servo presses that use different design types and have modified kinematic structure [5][6][7][8][9][10][11].…”

“…There are applications for the superposition of pulsation in deep drawing processes [3,9,14]. In this case, primarily the ram is moved by special kinematics, and the cushion performs a synchronized movement.…”

“…The limits of deep drawing may be extended by a multi-axis servo press. In cushion-ram pulsation (CRP), the drawing force is reduced by decoupling the forming operation (by the ram) and reduction of wrinkles (by the cushion) [9]. These tasks are performed sequentially with varying amplitudes and frequencies.…”

“…The technology can be categorized as a kind of incremental forming. The drawing force required is reduced through targeted removal of stress at the flange zones for better continued flowing of the material [9]. The method is more suitable for materials with shallow flow curves, such as mild steel or aluminum.…”