GB1336594A - Sieve screens - Google Patents

Abstract

1336594 Sieves DUNLOP HOLDINGS Ltd 31 Aug 1971 [28 Aug 1970] 41458/70 Headings B1D and B2H A sieve comprises two interconnected sets of parallel elements forming the warp and weft of a mesh, each element comprising a core of plastics material covered at least in part by a layer of elastomeric material. In Fig. 1, the sieve is constructed by weaving elements 1, 2. The elements are produced by extruding polypropylene material through a circular die to form rods 3 which are passed through a second die in which a layer 4 of an elastomer, e.g. natural or synthetic rubber, is extruded over the rods 3 and thereafter cured. Each composite rod is then crimped to assist weaving and to obtain a mechanical interlock between the members. Alternatively, crimping and weaving take place before curing which bonds the elastomeric cover at the points of contact 5. A number of different sections for the core are illustrated. In a modification, Fig. 10 (not shown), composite rod elements of rectangular section are overlapped and bonded together at the cross-over points. In Fig. 12, composite rod warp elements 10 of rectangular section are provided with apertures 11 to accommodate removable weft elements 12 which may be rectangular or circular in section. This construction allows the aperture size of the sieve to be varied. In Fig. 14 the warp elements are of triangular section. The apertures may be formed by machining or drilling through the cured composite element or through the extruded polypropylene rod which is subsequently covered with the elastomer, the apertures being formed by cutting away the uncured elastomer and the covering being finally cured. In Fig. 15, rectangular warp elements 14 covered on the top and sides by elastomer are provided with suitably shaped slots in the upper surface to receive weft elements 16 which may be of different cross-sections and which have an elastomer covering on appropriate surfaces.