Sheet-metal forming

Abstract

Sheet-metal forming is gradually changing from a craft-based to an engineering-based process. The review acknowledges the metallurgical improvements that have been made in sheet metals and in tool steels, and concentrates on research aimed at understanding and describing the mechanical properties of sheet metals in a more quantitative manner. The need to forgo reliance on simple parameters, and to obtain more comprehensive data on plastic yielding and work hardening, is clearly recognized. The pronounced effect of the shape of the yield locus on the strain distribution in stretch forming and in deep drawing is discussed. Innovations and improvements in the engineering design of tooling now enable the production of long shells by deep drawing and redrawing, or by deep drawing and ironing, in a single stroke of the ram and without interstage annealing. Drawing into a pressurized fluid ensures greater control over deformation, and permits the forming of tapered shells in one operation, using thinner gauges than previously. General pressings are discussed with particular reference to galling problems, and to the different tooling requirements of various sheet metals.