Determination of six stiffnesses for a press

In this paper a new press test is introduced, where the press is described by six load/deflection curves and by two Assumed Rotation Point (ARP). The experimental measurements have been performed on a 400 kN open C-press. To load and measure the deflection special equipment has been designed. The equipment can load the press in both vertical and horizontal direction during the stroke and can be placed in either the symmetry plans or eccentric. In this way both vertical and horizontal forces and resulting moment can be applied to the press. The maximum deflection is measured by upsetting of 8 lead specimens. The stiffnesses and assumed rotation points (ARP) has successfully been determined. For the analysed press, the rotational stiffness related to the X- and Y-axis is almost identical but a clearance at 2 mm/m has been identified for the rotation around the Y-axis. The approach has been validated by forging of a non-symmetric specimen causing torques and lateral forces. The load-displacement curves can be simplified into 6 stiffness- and 6 clearance values. (C) 2000 Elsevier Science B.V. All rights reserved.