| 摘要 |
A filtering screen is described comprising: a first filter mesh, a second filter mesh having a different mesh size from the first and overlying the first mesh, and an apertured support to which both of the meshes are bonded so as to maintain the two meshes in tension, the tension in one of the meshes being greater than that in the other. At least one other filter mesh may be bonded over the first two meshes. The support may comprise a plate of fiber reinforced material having apertures formed therein which are much greater in area than the openings in the filter mesh, or a sheet of metal in which apertures are formed and in which edge regions of each aperture are turned through approximately 90 DEG to extend normal to the plane of the sheet from the underside thereof to increase the rigidity of the sheet. The frame may alternatively be a honeycomb structure or an apertured metallic plate, the filter meshes being joined to the surface of the frame.
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