Abstract: A method of plugging an area of damaged mesh in a sifting screen. The method is applicable to screens in which woven wire mesh is stretched, tensioned and secured over a supporting frame containing a plurality of windows and in which local damage to the mesh is in an area of the mesh which overlies one of the windows. The method has the steps of inserting into the window a device which is a close fit therein, and securing the device in the window so as to completely cover the area of damaged mesh. The device may be a former having stretched thereacross and secured thereto mesh similar to that stretched across the window in question, or simply a plate or block. The device may be secured in place by a force or interference fit, mechanical means, or adhesive, or the device may be resiliently deformable to allow it to be pushed past a projection in the window, so as to snap fit the device in place.

Abstract: A filtering screen comprises a fine woven wirecloth filtering mesh (4) disposed above a coarse woven wirecloth support mesh (2). An intermediate woven wirecloth mesh (3) is disposed between the fine woven mesh (4) and the coarse woven mesh (2), the intermediate mesh (3) extending over a proportion of the area of the screen at or towards the rear thereof, said proportion being in the range of 20% to 40% of the area of the screen, and preferably substantially one third of the area of the screen.

Abstract: A method is described for making a reinforcing wire frame for embedding in a moulded polymer support frame over which woven wire cloth is to be stretched and secured to form a sifting screen. The method involves locating lengths of cut wire substantially equally spaced apart in a jig to form a first array. A second array of lengths of cut wire is located over the first array with the lengths of wire in the second array being substantially at right angles to those of the first array. The lengths of wire in the first and second arrays are resistance welded at points of mutual intersection so as to form a first substantially rectilinear matrix.

Abstract: A screen is described wherein one end of the screen frame is provided with an upwardly open channel profile and the other end with a similar but downwardly open channel profile, such that the outboard edge of an upwardly open profile will fit within the channel of a downwardly open profile provided along the edge of an adjoining screen frame, to enable two such screens to be connected together and to enable linear movement in a direction generally perpendicular to the line of engagement and generally in the plane of at least one of the two screens, to be transmitted from one screen frame to the other. The engagement of one profile by another also serves to close the gap between the two screen frames and prevent at least particulate material from passing therebetween. Preferably the engagement prevents liquid from passing therebetween.

Abstract: A method of repairing or refurbishing a filter screen is described. The type of screen is defined in the specification. The repair or refurbishment is effected by stripping worn or damaged wirecloth from the surface of the frame and placing fresh cloth over the frame and tensioning it as appropriate. Heat is then applied so as to soften surfaces of the frame over which wirecloth is stretched, so that the latter can penetrate softened plastics material in the surfaces and become embedded therein. The frame and its associated fresh cloth is allowed to cool, after which the applied tensioning is removed. Exposed edges of the wirecloth can be trimmed back to the surrounding flange. Plastics material may be applied to the surface of the frame which is to receive the new wirecloth, before the latter is fitted, to provide additional plastics material for bonding the wirecloth to the frame.

Abstract: A filter screen having support frame including an outer peripheral flange surrounding a central region. Faces of the outer peripheral flange of the support frame to which the wirecloth is bonded by heating are formed with a plurality of closely spaced apart parallel ridges including outer ridges and inner ridges, each having a crest, so that when heated, the crests of the ridges soften, and the woven wirecloth laid thereover and tensioned can, under an appropriate downward loading, penetrate and become embedded in the softened ridge crests. The outer ridges extend to a greater height above the frame than said inner ridges, whereby there is a greater volume of polymer to be melted and spread by the application of heat and pressure to the wire cloth near outer regions of the outer peripheral flange than near inner regions of the outer peripheral flange.

Abstract: A sifting screen is described comprising a rigid frame, a first woven cloth of hard wearing metal wire, stretched thereacross and secured thereto, and a second woven cloth having a coarser mesh than the first cloth and being woven from an elongate material of greater cross-section than the first, also stretched across the frame, and secured thereto, below the first cloth, to support the latter against sagging. In accordance with the invention, at least the wearing surface of the material from which the lower cloth is woven is selected to be significantly less hard wearing than that from which the upper cloth is woven, so that wear due to rubbing and vibration during use, occurs to a greater extent in the lower cloth than in the upper cloth. In one example the upper cloth is woven from stainless steel wire and the lower from phosphor bronze wire. In another example the lower cloth is of wire having a coating of an epoxy based material, or Teflon (TM), or Molybdenum Disulphide.

Abstract: In a method of continuously coating a conductive substrate such as brass wire to produce a desired cross-sectional size of coated material, the wire is drawn through a first die to produce an oversize wire, electroplate in a bath, and then drawn through a final die to reduce its area to the desired size and produce a controlled surface finish. The wire may be cleaned in an acid bath and rinsed in a rinsing bath prior to the electroplating bath. A further rinsing bath and dryer may be interposed upstream of the final die.

Abstract: A sifting screen having a rigid frame, a first woven cloth of hard wearing metal wire, stretched thereacross and secured thereto, and a second woven cloth having a coarser mesh than the first cloth and being woven from an elongate material of greater cross-section than the first, also stretched across the frame, and secured thereto, below the first cloth, to support the latter against sagging. In accordance with the invention, at least the wearing surface of the material from which the lower cloth is woven is selected to be significantly less hard wearing than that from which the upper cloth is woven, so that wear due to rubbing and vibration during use, occurs to a greater extent in the lower cloth than in the upper cloth. In one example the upper cloth is woven from stainless steel wire and the lower from phosphor bronze wire. In another example the lower cloth is of wire having a coating of an epoxy based material, or TEFLON.TM., or Molybdenum Disulphide.

Abstract: An assembly comprises a rectangular principal frame (12) of moulded plastics material and subdivided by crosspieces (14, 16) to form sub-areas (18). Each sub-area receives as a releasable snap-fit a plastics moulded insert (20) in the form of a sub-frame carrying one or more tensioned screen meshes (FIG. 1). A peripheral sealing gasket may seal the joint between each sub-area (18) and the insert (20).