Deformation resistance welding of sheet metal, tubes, and similar shapes

Abstract

Welded structures having a first and a second member formed from sheet metal, tubes, and similar shapes, are economically fabricated through use of a method for joining a second member to a first member having a folded rim extending therefrom. The folded rim defines an air gap within the folded rim. The first and second members are joined together by forcing the folded rim against the second member under sufficient pressure to flatten the folded rim to a point that there remains substantially no air gap inside the folded rim, and resistance welding together the first and second members. The second member and the rim respectively define faying surfaces thereof. The air gap inside the folded rim extends generally parallel to the faying surfaces. The faying surfaces of the rim and second member are forced against one another by applying pressure through the folded rim in a direction generally perpendicular to the faying surfaces. While applying pressure, a first level of electrical current may be passed through the first and second members for softening the rim by electrical resistance heating and causing the softened rim to deform against the second member. Pressure is maintained, and a second level of electrical current, higher than the first level of current, is applied for a time sufficient to at least partially melt the folded rim and form a deformation resistance weld between the first and second member.