New developments in bend forming of welded sheet metals

Abstract

The forming of sheet metal into complex shapes is an essential operation. Mostly the sheet metal products in the final form comprise of two or more sheet metal blanks joined together. The traditional press tool based forming of sheet metal is not viable for products that are large and have irregular form such as those employed in defense, aerospace, shipbuilding and railroad transportation. The tooling, die-punch and molds and associated cost to manufacture them limit the sheet metal shaping for large/non-regular shapes by conventional press-tools. The weld-zone present in the sheet metal acts as a property partition and may be source of failure and defects. It is important to assess the formability of sheet metal for defect free deformation and gauge the effect of weld-zones in order to suitably compensate the effect. The non-contact forming of sheets such as shot peeing, laser peeing and by laser heating are attractive and cost effective route in forming sheet metals especial for large and non-regular forms because the need for tooling is obviated. The laser shock forming works on the localized plastic strain on the surface to produce local induced deformation. The laser thermal forming however works on the long range thermal strain, which may be exceed plastic yield strain, distributed over the surface and its magnitude is comparable to the prevailing temperature.