Filtering screen

摘要

A method of constructing a filter screen is described. This involves forming a polymer support frame including therein a plurality of substantially similarly sized rectilinear apertures, defined by an integral rectilinear matrix of wire reinforced struts of polymer material. An upper edge of each strut is ridged and an upper surface of each boundary of the support frame provided with a plurality of ridges. One or more woven wirecloths are fitted over the ridges and tensioned. The wirecloths are secured in place by heating at least the ridges so as to soften the polymer material sufficiently to allow the wirecloths to penetrate crests of the ridges and upon cooling to remain embedded therein. This maintains tension in the wirecloths after cooling. The wires in one of the wirecloths are preferably tensioned differently from those in the other, so that different tensions exist in the wires of the two cloths after bonding to the frame.