Abstract
Copper, brass, and mild steel strips were deformed under elastic-plastic bending in cylindrical dies by matched cylindrical punches, without the use of any lubrication, to study the history of the enforced deformation. Separation between the punch and the strip, the punch load-displacement relationship, and the elastic springback are described. The deformation model is found to be dominated by the parameter (Y/E) (l/h), where Y is the material yield stress, E its Young's modulus, h the strip thickness, and I the strip length. When the value of this parameter is small, the strip is described as ‘stiff‘, and when it is large, ‘slender‘. The complete deformation process may be divided into several stages, each associated with a number of loading points. The phenomena of multi-point loading and the effects of largest punch load have been successfully incorporated into an explanation of the non-uniformity in final curvature of the strip after springback.
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