Abstract: The method of forming an annular piston with a central hub, a radial pressure face and an outer cylindrical flange having an outwardly opening annular seal receiving groove which comprises the steps of forming an annular sheet metal stamping having an axial hub portion, an annular radial pressure face and an axial cylindrical flange with an annular free end portion; rotating the stamping while radially and axially supporting the hub; radially inwardly rolling and permanently deforming the flange into U-shape while simultaneously axially compressing and bending the free end portion radially inward throughout 360.degree..

Abstract: A planetary production workpiece processing machine having a rotatable annular drum with circumferentially extending planetary workpiece engaging tooling and opposed fixed reaction tooling providing a progressively variable relative radial tooling spacing for rolling and variably stressing the planetary workpiece beyond elastic limit as it progresses from an entrance to an exit portion of the machine. Processing operations may include straightening of linear workpieces with rapid and gradually reduced deflection or progressive reduction forming of the workpiece. Multiple diameters in a linear workpiece are accommodated through the use of free floating as well as power driven drum elements.