Patent ID: 6373021
Filing Date: 2002-04-16
Classification: B23K

Abstract:
A method of electrical resistance welding a hydroformed metal tube and a metal sheet for an automotive vehicle structure, comprising the steps of:(a) providing a hydroformed metal tube having a wall thickness in the range of about 0.6 millimeter to about 3 millimeters, said tube having a planar wall portion; (b) providing a metal sheet for welding to said metal tube and having a thickness of about 0.6 millimeter to about 3 millimeters at a location for a weld; (c) forming a protrusion pattern having an outside diameter including a plurality of generally circular and generally concentric protrusions at said weld location, said protrusions being generally triangular in cross section, each triangular cross section having a base and an apex, each base having a length of about 0.4 to about 0.6 millimeter, each protrusion having a height of about 0.15 to about 0.25 millimeters from said base to said apex; (d) contacting at least a portion of said protrusion pattern of said sheet with said planar surface of said metal tube; (e) applying force to said sheet and said tube with resistance welding electrodes for flexing said planar wall portion of said tube and for promoting contact between an outermost one of said protrusions and said tube; (f) passing an electrical current between said welding electrodes through said protrusions and said tube for melting metal to form a weld nugget between said sheet and said tube; and (g) solidifying said molten metal to form a weld nugget having an outside diameter approximating said outside diameter of said protrusion pattern.