Comparison of deforming forces, residual stresses and geometrical accuracy of deformation machining with conventional bending and forming

Abstract

Deformation machining is a combination of thin structure machining and single point incremental forming/bending. This process enables the creation of complex structures, which are difficult or sometimes impossible to manufacture employing conventional manufacturing techniques. Moreover, advantages of fabrication of thin monolithic structures employing this process over assembled sheet metal components is critical in many aerospace and marine applications. The quality, strength and acceptability of the products largely depend upon the stresses induced during the fabrication and residual stresses remaining in the components afterwards. In the present work, a comprehensive comparison of the deforming forces, residual stresses and geometrical discrepancies in Deformation Machining (bending and stretching mode) with conventional and incremental sheet metal bending/stretch forming has been performed. Effect of prior anisotropy in the deforming forces and spring back is also included in bending comparisons. A substantial reduction in deforming forces in deformation machining and incremental bending/forming over conventional bending/forming process was observed. Residual stress induced across the part section of deformation machined process was comparable to conventional bending and was less compared to conventional stretch forming process. This work could provide initial insights in endeavor to commercialize Deformation Machining and developing it as a potential replacement for conventional sheet metal operations and subsequent assembly of the components.