Force Variations with Defects and a Force-based Strategy to Control Defects in SPIF

Abstract

The control of defects and forces is, respectively, necessary to produce robust components and to preserve machine tool and energy. In the present work, the variations in forces with the evolution of various SPIF (single point incremental forming) defects are studied by employing the pyramid geometry. It is found that the forming force increases as the size of pillow and wall defects increases, and contrarily decreases as the size of corner-fold increases. Further, to carry out defect-free forming, the corner requires more force than the straight-wall of pyramid (i.e., F-cr>F-sw). This fact appears in the form of spikes corresponding to corner location in the force curve. Therefore, online monitoring of the force curve is proposed as a strategy to control defects in SPIF. Finally, following the condition F-cr>F-sw, force models describing the defect-force-parameter relationship are developed. These models will help the users to simultaneously predict and optimize the force as well as defects.