Method and apparatus for forming a filter element

摘要

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 DEG 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 DEG 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. The partially rounded sheet, then is reformed to impart true circular arcs to the ridges and valleys by inserting reforming wedges into the valleys in one side of the sheet and sliding the wedges along those valleys along fixed predetermined circular arcs.