Patent ID: 7323653

Claim:
A method for joining a second member to a first member having a folded rim extending therefrom, with the folded rim defining an air gap therein, the method comprising: engaging the folded rim of the first member with a first electrode contacting only the first member; engaging the second member with a second electrode contacting only the second member; 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 by partially, but not completely, melting the folded rim, wherein the second member and folded rim respectively define faying surfaces thereof, the air gap inside the folded rim extends generally parallel to the faying surfaces, and the method further comprises: forcing the faying surfaces of the folded rim and second member against one another by applying pressure through the folded rim in a direction generally perpendicular to the faying surfaces, wherein the first and second members define a juncture thereof intersecting and extending from the faying surfaces, and the method further comprises: engaging the folded rim of the first member with a first electrode having a portion thereof extending beyond the folded rim; applying pressure against the folded rim with the first electrode in a first direction generally perpendicular to the faying surfaces; engaging the second member with a second electrode; applying pressure against the second member with the second electrode in a direction opposite the first direction; applying an electrical current between the electrodes for resistance heating of the first and second members; moving the first electrode toward the second electrode, while resistance welding together the first and second members, to a point where the portion of the first electrode extending beyond the folded rim contacts the second member; and continuing to apply pressure and electrical current after the portion of the first electrode extending beyond the folded rim contacts the second member, to thereby continue resistance heating of the juncture and force a portion of the material from the melted folded rim to flow into the juncture between the first and second members for welding them together.