Dana Corporation

Michael J Siegmund

David Joseph Yaniak

Danny L Gander

R James Bushelle

A method for manufacturing a rotor for use in an electromagnetic friction clutch includes the initial step of forming a flat circular blank of material into a generally cup-shaped outer rotor piece including a flat circular base portion and an annular flange portion. A piercing operation is performed to form a non-circular opening through the base portion of the outer rotor piece. Then, a plurality of concentric arrays of discontinuous recesses are formed sequentially in the outer rotor piece from the radially outermost area of the base portion to the radially innermost area of the base portion. This sequential forming virtually eliminates any manufacturing related stresses in the radially innermost region of bridge areas defined between adjacent recesses, while focusing such stresses toward the radially outermost regions of the bridge areas. A piercing operation is next performed on the outer rotor piece so as to form a circular opening therethrough. Next, a portion of the outer circumferential surface of the annular flange portion of the outer rotor piece is deformed so as to provide a circumferential rib thereabout. The next step in the method is to form a precise circumferential inner surface for the opening. This inner circumferential surface provides a seat to accurately position a hollow cylindrical inner rotor piece relative to the outer rotor piece. The inner rotor piece is also formed from a magnetically permeable material, such as a ferromagnetic material, and includes an axially extending protrusion which extends within the opening and is piloted on the axially extending surface. The inner rotor piece can then be secured to the outer rotor piece in a conventional manner, such as by laser welding, to form a rotor preform. Lastly, portions of the rotor preform are finish machined to form a rotor.

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Rockford, IL, United States of America

Michael J Siegmund