Forming Parameters and Forming Defects in Incremental Forming Process: Part B

Abstract

Single point incremental forming (SPIF), at present, is suffering from defects. With an aim to enhance understanding on their development to control them methodically, FE analyses by varying four parameters are performed in the present study. It is found that, while deforming sheet, stresses develop in the bottom of part. The SPIF defects are in fact outgrowth of these stresses. More precisely, the ratio of vertical- to horizontal-stress is a principal factor that controls (or causes) defects. The development of wall defect depends on the stress ratio in the tool/blank contact (zone A), while that of pillow defect depends on the stress ratio both in the tool/blank contact (zone A) as well as in the center of part's bottom (zone B). Moreover, the magnitude and nature (tension or compression) of the stress ratio, subject to the type of parameter, varies as a parameter is varied. These variations in the stress state in turn affect the defects growth (or size). It is concluded that the stress ratio both in zone A and in zone B needs to be simultaneously controlled so as to overcome the SPIF defects.