The bending of plate using a three-roll pyramid type plate bending machine

Abstract

An experimental three-roll pyramid type plate bending machine was constructed and measurements were made of the upper roll vertical force, the driving torque and the relaxed radius of curvature for a given disposition of the top and bottom rolls. Two methods of analysing the plate bending process in the machine are given: (1) a geometrical analysis based on the assumption that the deflected form of the plate is in the arc of a circle and (2) a load analysis using the uniaxial stress-strain relationship for the material. The experimental results for an aluminium alloy (N.P.8) were best accounted for by the geometrical analysis whilst the load analysis gave disappointing predictions.In Part 2 experiments are reported on the bending of mild steel. In most of the experiments the two lower rolls were driven, but to determine the effect of plate roll friction, some were carried out in which the lower exit roll only was driven. A discussion of the various theoretical analyses which have been proposed is given and they are compared with the results of the authors' experiments.