United Wire Limited

Dugald Stewart

Andrew Hughes

Gordon James Cook

Arthur Robert Bailey

George Charles Hartnup

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.

Method of constructing a filter screen

A method of constructing a frame ( ) for a filtering screen from a polymer material is described in which a wire frame reinforcement is wholly encapsulated during the frame moulding process so that two parallel spaced apart wires extend through each of the intersecting orthogonal ribs ( ) which define the open area of the frame ( ) across which the wirecloths ( ) are stretched. The surfaces of the frame ( ) in which the wirecloths ( ) are embedded are formed with ridges ( ) and the crests of the latter extend to different heights. The crests are softened by heating during the manufacturing process and the wirecloths ( ) stretched over the frame ( ) are forced into the softened crests after which the assembly is allowed to cool and cure. The frame ( ) is re-usable by stripping wirecloths ( ) from the top of the frame ( ) and fitting fresh wirecloths over the plastics material and heating the regions which are to encapsulate the fresh wirecloth.

Method of making a filtering screen and support frame therefor

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. Lengths of cut wire are located in a jig to form a third array, in which the lengths are also substantially equally spaced apart, and a fourth array of lengths of cut wire is arranged over the third array with the lengths of the fourth array substantially at right angles to the lengths of wire of the third array, and the wires of the third and fourth arrays are also resistance welded at points of mutual intersection to form a second substantially rectilinear matrix.

Reinforcement for a moulded filtering screen support frame

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. Alternatively the stripped frame may be inserted in a mould, and fresh polymer material is injected into the mould so as to reform ridges on the surfaces of the frame similar to those which existed when the frame was first manufactured, before the wirecloth is applied thereto.

Filtering screen and support frame therefor

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.

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Edinburgh, United Kingdom

Dugald Stewart