FILTER DEVICE AND METHOD OF PRODUCING THE SAME

摘要

FILTER DEVICE AND METHOD OF PRODUCING THE SAME A rectangular filter medium bent into folds has a frame-shaped wall integrally molded around its perimeter by extrusion molding so that its peripheral edge is embedded into the wall. That portion of the wall disposed on the lateral side of the filter medium parallel to its folds is provided on the inner surface with a plurality of spaced ridges and on the outer surface with a plurality of spaced depressions between the ridges and outside the outermost ridges. The lateral side of the filter medium is partly exposed to the depressions.