Stress and Deformation Studies for Sandwich Rolling Hard Metals

Abstract

The cold working of high-strength metals and alloys into sheet and strip form at the thinner gauges allows the metal manufacturer two alternatives: (1) high capital expenditure on a specialized mill of the Sendzimir or planetary type or (2) where demand does not justify the capital outlay, the application of new techniques utilizing existing equipment. In the latter class, the method of sandwich rolling is examined by theory and by experiment and it is shown that reductions in load up to 60 per cent can be achieved for rolling thin hard strip. The method allows greater reductions than for rolling the metal alone and decrease in finished thickness is obtained. A method of adapting current cold-rolling theory for the calculation of loads involved in planning production schedules is set out, based upon a criterion of simultaneous yielding in the hard and soft metal layers. Optimum conditions of metal thickness ratio and hardness ratio for the sandwich metals are discussed.