Patent ID: 6739169
Filing Date: 2004-05-25
Classification: B21D,Y10T

Abstract:
A method for hemming two aluminum sheet metal panels together comprising the steps of:forming a flange along an outer edge of one of said panels so that said flange extends from a bend line to the outer edge of said one of said panels and such that said flange lies in a plane substantially perpendicular to a plane of said one of said panels, said bend line having an outer radius R in the range of (1.0 mm+t)>R>(0.2 mm+t) where t=the thickness of said one of said panels in millimeters, positioning an outer edge of the other panel adjacent said bend line, bending said flange so that said flange overlies the outer edge of said other panel, and thereafter compressing said flange against an outer peripheral portion of said other panel so that said outer peripheral portion of said other panel is sandwiched in between said flange and said one panel, wherein said bending step further comprises the step of impacting a curvilinear prehemming tool against an outer edge of said flange, said prehemming tool having a radius such that, upon initial contact between said prehemming tool and the outer edge of said flange, the angle between the plane of said flange and a tangent of said prehemming tool is in the range of fifty-five to seventy degrees.