Analysis of Camber Deformation Occurring at the Edge of Sheet-metal Bending

摘要

In sheet-metal bending, a saddle shaped camber deformation appears at the edge along the ridge line direction of a bent sheet, because of extreme changes in the stress state from plane strain to plane stress. The camber deformation under uniform bending is analyzed by deformation theory. The numerical results enable quantitative clarification of the characteristic of the edge camber deformation. The camber at the inner surface of the sheet increases with decreasing bending radius while it decreases at the outer surface. The camber height of the outer surface is approximately between 10 percent and 20 percent of sheet thickness. When the sheet width is larger than the certain value determined by the bending radius, the camber height becomes constant and the plane strain condition is satisfied in the middle portion along the ridge direction. The camber height increases proportionally to Lankford's anisotropy parameter r value. On the other hand, the work hardening exponent n value is insensitive to the camber deformation. Finally, from the practical viewpoint, an approximated equation of the camber is proposed.