GB2037618A

GB2037618A - Sieve construction

Info

Publication number: GB2037618A
Application number: GB7937374A
Authority: GB
Original assignee: Hein Lehmann AG
Current assignee: Hein Lehmann AG
Priority date: 1978-11-17
Filing date: 1979-10-29
Publication date: 1980-07-16
Also published as: BR7907439A; NL7907822A; FR2441436B1; ZA796180B; IT1162434B; FR2441436A1; BE880067A; DE2849838B1; IT7950760A0; GB2037618B

Abstract

A sieve bottom comprises perforated or apertured sieve elements (7) made of rubber-elastic or like material and a supporting frame (9) on to which the sieve elements are replaceably located and automatically clamped. The underside of each sieve element is provided at least at two lateral edges with frame-connecting elements which include an inside rib (15) extending parallel to the associated lateral edge (14) of the sieve element and having an outer extension (16) associated therewith. A groove (17) is formed between the rib (15) and the inward surface of the extension (16) and the outside surface of the extension (16) is flush with the lateral edge (14). <IMAGE>

Description

SPECIFICATION Sieve bottom The present invention relates to a screen or sieve bottom having sieve elements made of rubberelastic material or like material and having a supporting structure on which the sieve elements are interchangeably located and self-clamping, whereby the sieve elements are provided with a surface located in the sieve plane and an underside extending parallel thereto on at least two opposing lateral edges.

A sieve bottom of this kind is generally used to grade or screen material to be riddled e.g. sand, gravel, coal or the like. Such a sieve bottom is known from the German Offenlegungsschrift 24 37 809, wherein the sieve bottom has a large number of sieve elements made of rubber-elastic material which have downwardly projecting extensions along their lateral edges and which extensions are attached automatically clamping in bores of bearing elements of a supporting structure. The spacings between the extensions and those of the bores are so adapted to each other that the sieve element is retained tensionally stressed in the incorporated state. The sieve elements are square and fitted together on all sides to form the sieve bottom.

In such a sieve bottom all sieve elements are of a definitive size longitudinally and in transverse direction. Therefore, sizes are obtained for the length and the width of the sieve bottom which are variable only in substantial amounts in accordance with the screen dimension of a sieve element. This limits the possibilities of deployment. Furthermore, such sieve elements can be subsequently replaced only to a limited extent. It has also been found that the extensions may be ripped or even completely torn off during replacement. The necessary supporting elements have to be relatively wide because of the bores. The wider the supporting elements, however, the wider have to be the imperforate ribs of the sieve elements. This causes the effective sieve surface to be reduced.More especialiy the bores in the supporting elements have to be fashioned with considerable accuracy of manufacture to enable the sieve elements to be retained at the required tension and this increases the manufacturing costs. The securing of the sieve elements is effected in collaboration with extensions of adjacent sieve elements. It is therefore necessary to fit additional filler bars having corresponding extensions at the sieve elements located at the edge of a sieve bottom.

Moreover, German Auslegesschrift 1301 952 discloses a sieve bottom having sieve elements made of load bearing plastics material and which have extensions in the manner of grooves and tongues on all four lateral edges which extension, beginning from below, do not quite extend to the surface of the sieve elements. In the upper region of the sieve elements, a stop surface for the grooves and tongues is provided which prevents the tongues from slipping through and at the same time produces a smooth upper lateral edge of the sieve element. The sieve elements are joined together without further assistance into a panel of sieve elements. Edge rails enclose such a sieve panel on all four sides. These edge rails have grooves and tongues in accordance with those of the lateral edges of the sieve elements. Such sieve bottom may be comprised of several sieve panels.

In such a sieve bottom, problems in connection with dimensions are also encountered due to its screen-like structure. Furthermore, the necessary edge rails for the grooves and tongues are very costly to produce. If such edge rails were inserted between all sieve elements, such would not only be very costly but it would also contradict the theory of techinical progress imparted by this patent, namely to provide a sieve bottom formed of directly interconnected sieve elements.

An object of the present invention is to provide a particularly variable sieve bottom producable at favourable costs and having interchangeable sieve elements and a universally usable supporting structure.

According to the present invention, there is provided a screen or sieve bottom having perforated or apertured sieve elements made of rubber-elastic or like material and having a supporting structure on to which the sieve elements are replaceably located or locatable and automatically clamping, whereby the sieve elements are provided with an upper side located in the sieve plane and an underside extending parallel thereto and having connecting means or elements at least at two lateral edges, characterised by the feature that the connecting elements include an inside rib extending parallel to the associated lateral edge and having an outer extension associated therewith, whereby a groove is formed between the rib and inward surface of the extension and the outside surface of the extension is flush with the lateral edge.

The sieve elements in accordance with the invention may be attached so as to individually clamp or engage the supporting structure. Filler bars at the edge of the sieve bottom are therefore dispensed with. The force required for detaching the sieve elements may also be individually established for each sieve element, hence also independent of adjacent sieve elements individually. The sieve elements adapted as strips are simple and replaceable independently of each other.

For storage and stackability of the sieve elements it is favourable for the inside ribs and the extensions to be flush with the underside of the sieve elements.

A particularly reliable hold of the sieve elements may be attained with the extensions being formed as continuous ribs.

It is possible in accordance with the invention for the extensions to have a semi-circular cross-section.

A particularly variable sieve bottom is characterised by the feature that the supporting structure comprises a frame having parallel rungs which has rails replaceably mounted thereon and extending transversely thereto, whereby the clamping or connecting elements are mountable on the rails. The frame may thus be fixedly installed in a sieve machine. By replacement of the rails, most varied types of sieve elements may be mounted.

With strip-like sieve elements their displacement in longitudinal extension may be prevented in that the length of the rails is at least as great as the groove formed between rib and inside surface of the extension and that the sieve elements are longer than the rails. At both its end faces the groove is preferably closed with a stop surface, so that in the installed state a certain clamping (or gripping) effect by the sieve elements also occurs in the longitudinal extension.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which Figure 1 is a perspective view of a screen or sieve bottom; and Figure 2 is a section through a further sieve bottom in accordance with the invention.

Figure 1 is a perspective view of a screen or sieve bottom in accordance with the invention. The sieve bottom has a supporting structure 1 comprising a frame 2 and with rails 3, 4. The frame 2 is assembled from beams and rungs arranged transversely thereto and welded together from, for example, U-shaped sections or square tubes. The rails 3,4 are replaceably mounted on the rungs, for example, by means of screw or dowel connections. For this purpose, the frame 2 has suitable recesses or bores 5. Strip-like screening or sieve elements 6 are mounted with their holding or connecting elements arranged in pairs along each lateral edge on the rails 3,4 mutually offset. The end faces of the sieve elements 6 are free of connecting elements.The rails 4 located on the edge of the sieve bottom are only singly provided since they only have to receive a single lateral edge, whilst the inside rails 3 are generally symmetrical and double. The shaping ofthe rails is variable within limits and is substantially adapted to the connecting elements of the sieve elements 6.

The frame 1 may be connected directly to a sieve apparatus - it being merely necessary to form bores for the rails 5 therein to permit such. In dependence upon the sieve elements selected and the nature of their connecting elements, the rails may then be selected and secured to the frame 2. Each sieve element is individually retained independently of the adjacent sieve element.

Figure 2 shows a section of an alternative sieve bottom in accordance with the invention, which substantially corresponds in structure to that shown in Figure 1. The sieve elements 7 of this sieve bottom are also attached to rails 8 which are replaceably secured to rungs of frame 9 of a supporting structure. The rails 8 are formed by combining the function of two individual rails and have a C-shaped cross-section. The rails 8 have two upright shanks 10 which merge into an inwardly bent head portion 11.

The rails 8 are provided with straps or plates 12 and by these plates 12 are connected to the frame 9 by means of securing elements 13. It suffices to provide a transverse plate at each end of the rail. The sieve elements 7 with their connecting elements are pressed onto the head portion 11 of opposing rails.

For this the connecting elements are fitted with an inner rib 15 extending parallel to the associated rail edge 14 and this rib has an outer extension 16 associated therewith. A groove 17 adapted to the shape of the head portion 11 is formed between the inside rib 15 and the outer extension 16. The retention capacity or the perfect fit of the sieve elements is increased by a recess 18 in the groove 15, into which the associated head portion 11 of a rail engages. The extension 14 is a continuous rib whose outer surface is flush with the lateral edge 14 of the sieve element 7. The undersides of the inside ribs 15 and the undersides of the extensions 16 also extend flush with the underside 19 of the sieve elements.

In the case of thinner sieve elements and for saving material it is also possible for the inside ribs 15 and the extensions 14 to be allowed to project from the underside 17. Furthermore, the ribs 15 and the extensions 16 of an individual sieve element may be arranged only in sections and opposed to each other or mutually offset. Moreover, extensions with semicircular cross-sections may be used. Ribs and extensions are integrally connected to the sieve elements, which are preferably made of castable or extrudable plastics material. The sieve elements in addition may be reinforced, especially in transverse direction.

To prevent the sieve elements from displacement in the direction of their longitudinal extension, the groove formed between the rib and the inside surface of the extension is sealed off at the end faces of the sieve elements buy a stop surface flush therewith. The length of the groove is thus slightly shorter than the length of the associated rail, so that in the installed state a certain clamping effect of the sieve elements also occurs in longitudinal direction.

This is particularly favourable if the sieve elements are aligned in the direction of conveying of the sieve bottom.

Claims

1. A screen or sieve bottom having perforated or apertured sieve elements made of rubber-elastic or like material and having a supporting structure on to which the sieve elements are replaceably located or locatable and automatically clamping, whereby the sieve elements are provided with an upper side located in the sieve plane and an underside extending parallel thereto and having connecting means or elements at least at two lateral edges, characterised by the feature that the connecting elements include an inside rib extending parallel to the associated lateral edge and having an outer extension associated therewith whereby a groove is formed between the rib and inward surface of the extension and the outside surface of the extension is flush with the lateral edge.

2. A sieve bottom as claimed in claim 1, in which the inside ribs and the extensions extend flush with the underside of the sieve element.

3. A sieve bottom as claimed in claim 1 or2, in which the extensions are formed as continuous ribs.

4. A sieve bottom as claimed in claim 1 or 2, in which the extensions are semicircular in crosssection.

5. A sieve bottom as claimed in any of claims 1 to 4, in which the supporting structure is provided with a frame having parallel rungs on which rails extending at right angles thereto are interchangeably located, whereby the clamping elements are adapted to be attached.

6. A sieve bottom as claimed in claim 5, in which the length of the rails is at least as great as the groove formed between the rib and inward surface of the extension, and in which the sieve elements are longer than the rails.

7. A screen or sieve bottom substantially as herein described with reference to and as illustrated in Figure 1 or as modified in Figure 2 of the accompanying drawings.