US Patent 7028596 Rotary cutting unit

A circular-cutter unit for equipment cutting flat lengths of material and sheet metal in a horizontal plane has upper and a lower circular blades both in planes perpendicular to the horizontal plane and in a longitudinal direction, carried by an upper and lower blade shaft, respectively, which are parallel with the horizontal plane and perpendicular to the longitudinal direction. The two blade shafts are rigidly and rotatably mounted in a common frame. The frame is U-shaped with the upper and lower legs connected by a flat yoke intersecting the horizontal plane at an acute angle. Several cutter units are mounted in a single apparatus and driven by a common drive from which the units can be individually detached for servicing.