This paper describes a very simple device that can establish the ram deflection during a presswork or forging cycle. Two types of error can be detected, both the linear displacement and the rotation of the ram. The device operates by measuring the co-ordinates of four points, before and after the deformation of a specimen, depending on the expected forces experienced during an actual forming or blanking process. The measured co-ordinates are then used to describe a plane and a vector normal to it: knowing these is sufficient to specify the displacement and rotation of the ram. The device described also provides the opportunity to add an additional horizontal force, modelling the horizontal forces that appear during the forging operation of a complicated component. The device consists of two plates: an upper plate fixed to the ram of the press and a lower plate fixed to the press bed. During the stroke, four 'markers' (i.e. punches), which are ground flat in one plane and attached to the upper plate, make small tracks over four corresponding bodies fixed to the bottom plate. Measuring the co-ordinates of these tracks twice, first during the idle stroke and second after the deformation of a specimen, leads to a description of six components (three displacement and three rotation) of the ram. The device can either incorporate a mechanical or electrical method of measurement and is very convenient for small factories. For medium and large forging presses the instructions of the German Standard DIN55189 should be applied to determine the elastic deflection, rotation and tilting of the slide of the presses tested. (C) 1998 Elsevier Science S.A. All rights reserved.
