Abstract: Apparatus and method for forming an axial flow filter element from a fan or sectorial shaped sheet having parallel curved ends, straight sides converging at an angle less than 180.degree. and a plurality of curved ridges and valleys extending between the sides parallel to the curved ends. Holding wedges are inserted into the valleys in the upper side of the sheet while the latter is supported on a table. The pitch between the holding wedges is then reduced uniformly to reduce the radial length of the sheet. The sheet is then partially rounded into a semi-circular shape to increase the central angle of the sectorial shape sheet to as much as 180.degree. by forcing the wider convex end of the reduced sheet toward a circular post centrally engaging the midpoint of the smaller concave end of the sheet.

Abstract: Cutting of a corrugated fin into predetermined lengths for a radiator in a vehicle. The phase mating is, when the cutter is moved in the direction opposite to the corrugated member, effected at the correcting point where the torque in the cutter is the same as the torque at a cutting point where the corrugated member is moved synchronizingly with the cutter. Thus, automatic phase mating is effected, thereby causing the fin to be cut precisely at a trough of the fin.