GB1589956A

GB1589956A - Sieve bottom

Info

Publication number: GB1589956A
Application number: GB579578A
Authority: GB
Original assignee: Hein Lehmann AG
Current assignee: Hein Lehmann AG
Priority date: 1977-02-15
Filing date: 1978-02-14
Publication date: 1981-05-20
Also published as: FR2380080A1; AT354957B; ATA92978A; FR2380080B3

Description

(54) SIEVE BOTTOM (71) We, HEIN, LEHMANN AKTIEN GESELLSCHAFT, of 75 Fichtenstrasse, D-4000 Duesseldorf, Federal Republic of Germany, a German body corporate, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: The present invention relates to a perforated sieve bottom having a plurality of sieve elements of predetermined width and made of rubber-elastic material, the sieve elements each having an upper surface located in the sieve plane, a lower surface and lateral edges with extensions and with stop surfaces serving for the clamping of adjacent sieve elements with one another, and having a support structure which is provided with supporting elements to which the sieve elements are detachably secured.

A sieve bottom of this kind generally serves the purpose of grading material to be screened, especially material to be screened having an abrasive effect, e.g. sand, gravel, coal or the like. Such a sieve bottom is known from German Auslegeschrift 12 51 635. This sieve bottom has a large number of sieve elements which are mounted in each region of a pair of opposite edges on supporting elements formed by tensioned, parallel extending wires. The wires as well as the sieve elements are provided first with a non-vulcanized rubber coating or layer. After this layer has been vulcanized, a close bond of the individual sieve elements on the wires is formed and acts as an endless surface for the whole sieve bottom.

If at a later date certain regions of the perforated bottom are worn, individual sieve elements can no longer be replaced or renewed without considerable expenditure or effort. This has an adverse effect on the adjustment of the new sieve bottom. Hence, if the first screening analyses do not show the required separation results, the whole sieve bottom has to be replaced. The sieve elements moreover, both in longitudinal and transverse direction have a definite size.

Therefore, values are obtained for the length and the width of the sieve bottom which are variable only in large steps in accordance with the standard sizes of sieve elements. This considerably limits the possibilities of deployment. Moreover, the sieve elements made of rubber-elastic material have a high degree of elasticity which on the one hand provides considerable advantages, but on the other hand requires reinforcements to prevent the sieve bottom from sagging. The more extensive the reinforcements, the greater is the loss of open screening surface and the costlier the production of a sieve element.

It is an object of the present invention to provide a sieve bottom which may be produced at favourable costs and have manifold uses having sieve elements and supporting elements, the sieve elements as such having a high degree of elasticity, adapted in simple manner to be individually replaceable, and mountable on the supporting elements and in the installed state having a relatively high rigidity and a secure hold.

According to the present invention there is provided a sieve bottom having a plurality of sieve elements made of rubber-elastic material and being of predetermined width, whereby the sieve elements are each provided with an upper surface located in the sieve plane, a lower surface and lateral edges with extensions and with stop surfaces serving for the clamping of adjacent sieve elements with one another, and with a supporting structure which has supporting elements to which the sieve elements are detachably secured, in which the widths of the sieve elements in their unstressed state are greater in the regions of the undersides of the sieve elements than the widths of the spaces into which the sieve elements are constrained by virtue of the spacing of the opposing supporting elements so that the sieve elements are subject to compression in the regions of their undersides.

By the relationship of the installation dimension to the width of the sieve element, a compressive tension is produced in the lower region of the sieve element which causes it to become arched. This leads to a substantial increase in the rigidity and to an improved retention of the sieve element. The compressive force, for example, may be produced by the arrangement of projections in the lower regions of the lateral edges of the sieve element, by parts of the supporting elements themselves, e.g. by a web and/or elevations formed thereon and/or by inserted spacing ledges. The compressive force which may be applied punctifortn or linearly, need not act on all sides of the sieve element. Frequently it suffices when pressure is applied to the sieve element along two opposite lateral edges in the installed state.

A particularly strong retention of the sieve elements on the supporting elements and adequate mutual bracing is obtained if the extensions of the lateral edges of the sieve elements each have an inverted groove open towards the underside, corresponding to the cross-section of the supporting elements.

It has been found to be favourable for the extensions to be larger than the relevant installation dimension. The sieve elements are hence joined together with force fit. This both further increases the retention and also the mutual bracing óf the sieve members and moreover prevents material being screened from entering between the sieve elements.

Mutual bracing in the manner of a zip fastener of the sieve elements is attained in that at least one of the stop surfaces is located on each extension and moreover these stop surfaces are located in planes substantially at right angles to the sieve plane.

In particular when utilising soft rubberelastic material for the sieve elements, the retention and the bracing may be ensured if one of the stop surfaces is located on the end face óf the extensions and when these stop surfaces are located substantially in planes parallel to the sieve plane. The required effect occurs especially when at the same time the groove formed in the underside of the extensions is recessed.

Mounting the . sieve elements may be facilitated in that the extensions and lateral edges of the sieve elements are provided with corresponding wedge-shaped located or wedge-like acting surfaces.

The supporting elements are preferably formed with a T-shaped cross-section or as webs having apertures for the extensions.

In the webs the-apertures may be slots or elongate holes extending parallel to the upper faces of the webs, in which the recessed pfdjections e.g. of the groove, engage.

The present invention will be further illustrated, by way of-example; with refer ence to the accompanying drawings, in which: Figs. 1, 3 and 5 each show a fragmentary section of a sieve bottom in accordance with the invention; Figs. 2, 4 and 6 each show a plan view of each of the sieve bottoms; Fig. 7 is a fragmentary section of a further sieve bottom; and Fig. 8 is a perspective view of the sieve element shown in Fig. 7.

Fig. 1 shows a fragmentary section of an edge piece of a sieve bottom in accordance with the invention in which only a single sieve element 1 (of several) and associated supporting elements 2 is shown. A lateral edge 3 of sieve element 1, which acts at the same time as the lateral edge of the sieve bottom, has a continuous flange 4 of angular cross-section. In certain cases, it also suffices to arrange the flange only in sections spaced along the periphery of element 1. The flange 4 has a recessed groove which corresponds to the profile of supporting element 2. The recessed groove automatically grips clampingly around supporting element 2. Supporting element 2 is comprised of a hkad portion 5 and a web 6. It may be made integrally or be an assembled, e.g. welded, profile.The head portion 5 has wedgeshaped surfaces 7 which facilitate the mounting of sieve element 1. Below the surfaces 7 stop surfaces 8 are provided which prevent accidental detachment of the sieve element 1.

The spacing between two adjacent supporting elements 2 and the width of sieve element 1 are adapted to each other in such a manner that the elements 2 so engage the flanges 4 along opposite lateral edges of the sieve element 1, as to impress a tensile stress on the sieve element 1 in the region of the sieve plane 9. In the region of the underside 10 remote from the sieve plane 9, the sieve element is oversize relative to the associated spacing of two adjacent supporting elements 2. This causes a compressive force to be exerted on the sieve element.

Compressive force and tractive force produce a bracing of the sieve element 1.

Additionally a reliable retention is obtained.

A sieve bottom in accordance with the invention may be of any desired size. The sieve elements 1 may be made in strips of substantially any length. This may be effected by moulding, injection moulding or extrusion of suitable plastics materials, e.g.

polyurethane. The sieve elements may also be assembled from individually prefabricated components which contain the sieve openings. The sieve elements may be strengthened by means of reinforcements, webs or the like. The width of a sieve element is preferably dimensioned such that during its assembly a sieve bottom of marketable width (or length) is created, e.g. a sieve element width of 100 mm, 125 mm, 200 mm or the like. The length of the sieve element preferably conforms to the width (or length) of the sieve bottom, which may be built up of a plurality of abutting elements.

The high degree of rigidity of an installed sieve element is provided moreover in that the sieve element is compressed in its lower region and stretched in its upper region.

This leads to arching of the individual sieve element. It has been found that the rigidity of a sieve element under load then increases even more than proportionally, since the proportion of the increase of rigidity produced by the tractive force increases accordingly.

Fig. 2 shows a plan view of the same sieve bottom as Fig. 1 in accordance with the invention. The sieve openings 11 are so arranged that the material being screened sweeping over the sieve bottom does not pass any continuous sections without sieve openings. At the marginal face 12 of the sieve element 1, further parts of a supporting structure, sealing devices and/or other parts may be arranged.

In Fig. 3 a fragmentary section of a further sieve bottom in accordance with the invention is shown in the region of two adjacent sieve elements 13 and 14. The lower parts 15 of the lateral edges of the sieve elements press against the supporting element 16, while the upper parts of the edges comprise interlocking extensions 17, which engage to clamp the enlarged head of supporting element 16 between them. The supporting element has a T-shaped, e.g. a club-shaped profile. It is, however, also possible to have a double club-shaped profile.

The plan view shown in Fig. 4 shows that the extensions 17 have dove-tailed stop surfaces 25 and 26 which in this elevation are shown as lines and which are located substantially in planes at right angles to the sieve plane. The extensions 17 by means of the stop surface 25 and 26 interengage in the manner of a zip fastener. This makes it possible to introduce not only tractive forces from the supporting elements into the sieve elements, but also to transmit tractive forces from one sieve element to the next. The sieve elements, for example, have rectangular sieve openings 18 arranged in a row.

Figs. 5 and 6 show a further alternative for forming the extensions 20 and supporting elements 19. Herein, the extensions 20 are so formed that the supporting element is only slightly clasped. This also permits the strip without sieve openings to be further reduced in width. The supporting element 19 may thus be formed as a single rod, wire or steel cable. The sieve elements 21 and 22 in the region of their undersides mutually abut directly against their lateral edges 23, 24 and so reach the required pressure in the region of the underside. Moreover, a variety of cross-sectional shapes e.g. oval, T-shaped, double T-shaped, rectangular trapezoidal, club-shaped or double club-shaped may be chosen for the supporting elements.

Fig. 7 shows a fragmentary section of a further sieve bottom in the region of two adjacent sieve elements 27 and 28. The sieve elements have extensions 29 each of which has a recessed groove to receive the supporting element 30. The supporting element 30 is a web having openings 31, e.g.

elongate holes provided therein. The extensions have projections 32 which engage in openings 31 and ensure a particularly secure retention of the sieve elements 27, 28 on the supporting element 30. At the end faces of the extensions 29, stop surfaces or ledges 33 are located which substantially extend in a plane parallel to the sieve plane. The extensions 29 of the sieve elements 27 or 28 are somewhat larger than the corresponding installation space located between the extensions 29 of the adjacent sieve elements 28 or 27. In the completed mounted state the sieve elements are hence assembled with force fit.

The mutual bracing of the sieve elements 27 and 28 no longer occurs in the sieve plane but at right angles thereto. In collaboration with the projections 32 and/or with the grooves of the extensions 29, a secure retention is attained. The force fit of the extensions increases the retention forces and at the same time prevents particles of material being screened from penetrating between the sieve elements. Opposing lateral edges of sieve elements with the exception of edge sieve elements are provided with identical extensions.

Fig. 8 shows a perspective view of the sieve element 28 shown in Fig. 7 whereby especially the projections 32 and the stop surfaces 33 are clearly evident.

WHAT WE CLAIM IS:- 1. A sieve bottom having a plurality of sieve elements made of rubber-elastic material and being of predetermined width, whereby the sieve elements are each provided with an upper surface located in the sieve plane, a lower surface and lateral edges with extensions and with stop surfaces serving for the clamping of adjacent sieve elements with one another, and with a supporting structure which has supporting elements to which the sieve elements are detachably secured, in which the widths of the sieve elements in their unstressed state are greater in the regions of the undersides of the sieve elements than the widths of the spaces into which the sieve elements are

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. (or length) is created, e.g. a sieve element width of 100 mm, 125 mm, 200 mm or the like. The length of the sieve element preferably conforms to the width (or length) of the sieve bottom, which may be built up of a plurality of abutting elements. The high degree of rigidity of an installed sieve element is provided moreover in that the sieve element is compressed in its lower region and stretched in its upper region. This leads to arching of the individual sieve element. It has been found that the rigidity of a sieve element under load then increases even more than proportionally, since the proportion of the increase of rigidity produced by the tractive force increases accordingly. Fig. 2 shows a plan view of the same sieve bottom as Fig. 1 in accordance with the invention. The sieve openings 11 are so arranged that the material being screened sweeping over the sieve bottom does not pass any continuous sections without sieve openings. At the marginal face 12 of the sieve element 1, further parts of a supporting structure, sealing devices and/or other parts may be arranged. In Fig. 3 a fragmentary section of a further sieve bottom in accordance with the invention is shown in the region of two adjacent sieve elements 13 and 14. The lower parts 15 of the lateral edges of the sieve elements press against the supporting element 16, while the upper parts of the edges comprise interlocking extensions 17, which engage to clamp the enlarged head of supporting element 16 between them. The supporting element has a T-shaped, e.g. a club-shaped profile. It is, however, also possible to have a double club-shaped profile. The plan view shown in Fig. 4 shows that the extensions 17 have dove-tailed stop surfaces 25 and 26 which in this elevation are shown as lines and which are located substantially in planes at right angles to the sieve plane. The extensions 17 by means of the stop surface 25 and 26 interengage in the manner of a zip fastener. This makes it possible to introduce not only tractive forces from the supporting elements into the sieve elements, but also to transmit tractive forces from one sieve element to the next. The sieve elements, for example, have rectangular sieve openings 18 arranged in a row. Figs. 5 and 6 show a further alternative for forming the extensions 20 and supporting elements 19. Herein, the extensions 20 are so formed that the supporting element is only slightly clasped. This also permits the strip without sieve openings to be further reduced in width. The supporting element 19 may thus be formed as a single rod, wire or steel cable. The sieve elements 21 and 22 in the region of their undersides mutually abut directly against their lateral edges 23, 24 and so reach the required pressure in the region of the underside. Moreover, a variety of cross-sectional shapes e.g. oval, T-shaped, double T-shaped, rectangular trapezoidal, club-shaped or double club-shaped may be chosen for the supporting elements. Fig. 7 shows a fragmentary section of a further sieve bottom in the region of two adjacent sieve elements 27 and 28. The sieve elements have extensions 29 each of which has a recessed groove to receive the supporting element 30. The supporting element 30 is a web having openings 31, e.g. elongate holes provided therein. The extensions have projections 32 which engage in openings 31 and ensure a particularly secure retention of the sieve elements 27, 28 on the supporting element 30. At the end faces of the extensions 29, stop surfaces or ledges 33 are located which substantially extend in a plane parallel to the sieve plane. The extensions 29 of the sieve elements 27 or 28 are somewhat larger than the corresponding installation space located between the extensions 29 of the adjacent sieve elements 28 or 27. In the completed mounted state the sieve elements are hence assembled with force fit. The mutual bracing of the sieve elements 27 and 28 no longer occurs in the sieve plane but at right angles thereto. In collaboration with the projections 32 and/or with the grooves of the extensions 29, a secure retention is attained. The force fit of the extensions increases the retention forces and at the same time prevents particles of material being screened from penetrating between the sieve elements. Opposing lateral edges of sieve elements with the exception of edge sieve elements are provided with identical extensions. Fig. 8 shows a perspective view of the sieve element 28 shown in Fig. 7 whereby especially the projections 32 and the stop surfaces 33 are clearly evident. WHAT WE CLAIM IS:-

1. A sieve bottom having a plurality of sieve elements made of rubber-elastic material and being of predetermined width, whereby the sieve elements are each provided with an upper surface located in the sieve plane, a lower surface and lateral edges with extensions and with stop surfaces serving for the clamping of adjacent sieve elements with one another, and with a supporting structure which has supporting elements to which the sieve elements are detachably secured, in which the widths of the sieve elements in their unstressed state are greater in the regions of the undersides of the sieve elements than the widths of the spaces into which the sieve elements are

constrained by virtue of the spacing of the opposing supporting elements so that the sieve elements are subject to compression in the regions of their undersides.

2. A sieve bottom as claimed in claim 1, in which the extensions each have an inverted groove corresponding to the crosssection of the supporting elements.

3. A sieve bottom as claimed in claim 1 or 2, in which the extensions of a sieve element are larger than the corresponding installation space located between the extensions of the adjacent sieve element.

4. A sieve bottom as claimed in any preceding claim, in which at least one of the stop surfaces is located on each extension and in which these stop surfaces are located in planes substantially at right angles to the sieve plane.

5. A sieve bottom as claimed in any one of claims 1 to 3, in which one of the stop surfaces is located on the end faces of the extensions and in which these stop surfaces are located substantially parallel with the sieve plane.

6. A sieve bottom as claimed in any preceding claim, in which the extensions have wedge-shaped or wedge-like acting surfaces located thereon to facilitate the mounting of the sieve elements on the supporting elements.

7. A sieve bottom as claimed in any preceding claim, in which the supporting elements are T-shaped in cross-section or formed as webs with openings for the extensions.

8. A sieve bottom, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.