Experimental and numerical investigations on structural thinning, thinning evolution and compensation stratagem in deformation machining stretching mode

Deformation machining (DM) is a combination of thin structure machining and single point incremental forming/bending. This process enables creation of monolithic structures with complex geometries employing conventional tooling and equipment. In the present work, a comprehensive experimental and numerical (finite element) investigations on structural thinning, evolution of thinning across the forming depth in DM stretching mode has been performed. Structural thickness was found to be highly non uniform along the forming depth across all the investigated fixed and variable forming angles profiles. Structural thickness of the formed structure influences the strength and stiffness of the formed component. A theory behind non-uniform and reducing thickness profile has been proposed from the analysis of thinning evolution of the same formed profile at varied forming depths. Finally, a compensation strategy in thin structure machining has been proposed to obtain uniform structural thickness encompassing variable profiles in incremental forming. In this strategy, a relationship to machine an initial non-uniform section thickness radially taking the uncompensated formed thickness profile into consideration is obtained in order to achieve a uniform formed thickness profile.