Patent ID: 7543384

Claim:
A method of making a variable thickness member for a vehicle, said method comprising the steps of: providing a planar blank; providing a die set having a first die half with a projection portion and a second die half with a cavity portion to receive the projection portion; stretching the planar blank to form a stretched blank, wherein stretching the planar blank includes stamping the planar blank with a punch stretching operation; and forming the stretched blank into a variable thickness member having a variable thickness along its length; and forming the variable thickness member into first and second channel shaped members, each of the channel shaped members having a pair of side walls extending longitudinally and a web extending between the side walls, the web having a thickness less than a thickness of the side walls; wherein each side wall of the first channel shaped member is attached to a respective one of the side walls of the second channel shaped member at predetermined points along the longitudinal expanse thereof to thereby form a closed section assembly.