DK2612712T3 - Aim - Google Patents

Description

Description [0001] The invention relates to a sieve with which ribbon-shaped and sheetlike elements, particularly but not exclusively, are separated from the material to be screened, for example during separation of household waste or shredder waste according to claim 1.

[0002] In screening inhomogeneous mixtures of materials, it often happens that particularly elongated, and consequently ribbon-shaped, or sheet-like or plate-like components impede the transport of the material along the screening direction and lead to the formation of material pileups, which upon reaching a critical size, roll over wide areas of the screen, without thereby being screened; these components of the material to be screened also tend to block a considerable proportion of the screen openings for long periods of time, thus further compromising screening quality. The following documents in this technical field deserve to be mentioned: DE 10 2009 007 823: This screener has as its content the special problem statement of making it easy and feasible to install, to adjust the separation and slope of and to change the separating diaphragms. For this purpose, curved plates are constituted as separating diaphragms, which run substantially diagonally to the screening direction and which in their upper portion, which comes first into contact with the material to be screened, are arranged at least approximately parallel to the plane of the screen, but with their segment lying definitely below the screen plane arranged more steeply. Consequently, the curvature is concave facing the material to be screened.

[0003] A screen is known from the applicant's EP 2 196 081, which admittedly is particularly designed to form relatively small mesh openings, but is not limited to that. In this screen, the webs running in vertical planes through the screening direction are provided with recesses surrounded on all sides by web material, into which sections are inserted corresponding to the separating diaphragms of the aforementioned document. These sections can exhibit a curved or bent cross-section; the curvature is thereby formed just as in the aforementioned document. The point of this measure is to arrive at mechanically stable configurations, even at small mesh openings wherein welding of the sections to the webs is no longer possible.

[0004] Another screen is known from the applicant’s AT 509 855 wherein the webs running in the screening direction exhibit slits on their underside into which sections are inserted having slits on their upper side. The sections in turn are bent or curved, as in the two aforementioned documents, but here a fillet is provided on the upper side of each web which, viewed diagonally to the screening direction, is thicker than the web, whereby preferably the sections have recesses on their upper edges so configured that the fillet lies at least partially below the upper surface of the portions of the sections running parallel or nearly parallel to the plane of the screen.

[0005] Moreover, it is known for improving the separation of plate-like elements from a stream of material, in screens wherein the screen facing, viewed in the screening direction, is tiered downward, to place finger-like struts in the area of each tier running above the following screen surface and to cover these to the extent of at least a third of the length of the respective tier. Sheet-like or ribbonshaped elements are to be thereby prevented from covering the screen openings to a considerable degree and thereby also reducing both the screening quality and the throughput.

[0006] The measures mentioned do indeed contribute to improving screening quality and thereby also to raising the achievable throughput, but these improvements have the disadvantages that they are only incremental and still unsatisfactory. It is the object of the present invention to substantially overcome or ameliorate one or more of the disadvantages of the prior art, or at least provide a useful alternative.

[0007] In accordance with the present invention, this is achieved by the distinguishing part of claim 1. In other words, it’s surprisingly sufficient when the webs of the sieve are at least 30% of the sieve width, preferably at least 50% of the sieve width and, especially preferred at least 100% of the sieve width higher than the sections in the screening direction; in one preferred embodiment, the upper edges of the webs are configured or equipped with upward rounded cross-sections. Moreover, the sections are curved according to the invention, with a radius of curvature of at least 30% of the mesh width, preferably at least 60% of the mesh width and especially preferably at least 100% of the mesh width, and exhibit upper end tangents lying in the plane of the screen. Linear rim segments can be connected to one or both ends without bending.

[0008] Preferred embodiments of the invention will be described hereinafter, by way of examples only, with reference to the accompanying drawings, wherein:

Fig. 1 shows a screen according to an embodiment of the invention in section view perpendicular to the screen surface and parallel to the screening direction to show the most important size relations,

Fig. 2 shows a schematic view of a plurality of screens positioned one behind the other,

Fig. 3 to 6 shows details.

[0009] Fig. 1 shows, purely schematically and without showing the framework, the drive or the bearings of the screen, a schematic section in the vertical direction parallel to the sieving direction S between two webs 2 running parallel to the screening direction, hence through the sections 3 and therewith a side view of the web 2 positioned behind the section. The screen is shown without the customary diagonal arrangement.

[0010] The mesh width M of the screen is given by the separation of adjoining thickened portions of the webs 2, or by fillets 4 (Fig. 6) and adjoining sections 3; these separations are generally of equal size; otherwise, the arithmetic mean of the two separation values is to be used as the mesh width M for the purpose of the invention. Now this mesh width defines various sizes, dimensions and relations of the screen according to an embodiment the invention, in order to be able to attain the initially stated goals: The sections 3 preferably exhibit, in their upper portion, a straight portion or segment 5, to which a curved portion or segment 6 is joined. According to an embodiment of the invention, the straight segment 5 and the curved segment 6 merge into one another without a bend; if no straight section 5 is provided for, the curved section 6 ends in its upper portion at the end point in a tangent wherein that of the straight segment would run if one were provided. In other words, the upper tangents of the sections 3 all lie in a plane, designated in the application as the screen plane 7 and which, otherwise considered, at least runs parallel to a separately defined screen plane.

[0011] The curved portion 6 of the section 3 exhibits at every point a radius of curvature R which, as stated above, amounts to at least 30% (or at least 60%, or at least 100%) of the mesh width M. If the curvature is not constant this applies to each segment, and the individual segments having different curvatures merge into one another without bends.

[0012] In the example embodiment shown, the curved segment 6 is joined "downwardly" by a linear segment or portion 9, by means of which screening can be further improved. If such a linear portion 9 is provided, it is important that it join the curved portion 6 without a bend.

[0013] The webs 2, where the sections 3 either are inserted into slits or onto which they are suitably attached, preferably welded, protrude distinctly above the screen plane 7, as defined above; This superelevation H amounts to at least 30% of the mesh width M, preferably 50% of the mesh width and it is especially preferable if it is more than 100% of the mesh width M. Moreover, the webs 2 exhibit along their upper edges a thickening, which is accomplished either by plastic distortion of the web material or, as preferred on the grounds of cost, by the application, preferably by welding, of a fillet 4, whereby the fillet, as shown in Fig. 6 exhibits, in the direction perpendicular to the plane of the web 2 and thus in the viewing direction of Fig. 1, a thickness D, which amounts to at least twice, preferably three times, and especially preferably four times the web thickness d. Moreover, as shown in Figs. 3-5, it is preferred that the cross-section of the fillet 4, which is applied to the web 2, along its upper contour, that is from its thickest point on along the perimeter, is made smooth, that is with no bends, hence is made rounded, preferably circular or elliptical. With an elliptical configuration, the transversely elliptical configuration as shown in Fig. 3 is preferred.

[0014] Figure 2 shows the arrangement of two (of several) screens 1 according to an embodiment of the invention, one after the other, whereby the screen planes 7 running diagonally with the screens are not arranged in alignment with one another, but rather each subsequent screen in the screen direction S lie deeper (mutually parallel in the example embodiment shown) than in the foregoing screen. Flere the previously mentioned fingers 8, which are distinctly arranged above the fillets 4, are clearly visible. The fingers can exhibit mutual separations, which correspond to the mesh width; however, it is possible to provide these fingers with a greater separation from one another. The angle of the fingers with respect to the screen plane 7 lies between the horizontal and the parallel to the screen plane. The angle as drawn, about (+10%) half as strongly inclined with respect to the vertical as the screen plane, is preferred.

[0015] In Fig. 2, two angles are also given, adhering to which (absolute value, hence as a scalar) allows screens according to an embodiment of the invention to be even more effective. This relates to the angle Y joining the screen plane 7 to the horizontal, and the angle X, which joins the tangents of the lower end of the curved segment 6 -and consequently an optionally provided lower linear portion 9 of the sections -to the horizontal. It is preferred that the angle X amount to at least 1.5 times, preferably two times and especially preferably three times the angle Y.

[0016] The invention is not limited to the embodiments illustrated and described, but rather can be modified in various ways. It is, as indicated in Fig. 2, possible to combine several screen elements according to the invention, not only in series as shown but also so as to form several screen levels. The mesh width M can vary within wide limits; when used for separating domestic waste, favorable values are 200 mm ±20%.

Claims (5)

A screen consisting of a vertical step (2) extending in a direction (S) with thickening (4) at their upper edges and transversely curved profile bodies (3) arranged between the steps (2) whose tangents at their upper end points define a screen plane (7) parallel to the direction of the screen (S) and where the free distance between the adjacent steps (2) and profile bodies (3), respectively, determines a mesh width (M), characterized in that: a) (H) between the screen plane (7) and the top edge of a thickening (4) is at least 30% of the mesh width (M), preferably at least 50% of the mesh width (M), and especially preferably at least 100% of the mesh width (M), b) that the radius of curvature (R) of the curved profile bodies (3) is at least 30% of the mesh (M), preferably at least 60% of the mesh (M), and particularly preferably at least 100% of the mesh (M), and c) optionally some rectilinear extending end regions (5, 9) of the profile bodies (3) without cracks flow into curved sections (6). Sieve according to claim 1, characterized in that the thickness (D) of a thickening or strip (4) of the step (2) is at least twice, preferably at least three times, and especially preferably at least four times the step thickness (d). Sieve according to claim 2, characterized in that the thickening or strip (4) along its upper contour is round, preferably circular or elliptical. 4th Sieve according to one of claims 1 to 3, characterized in that an angle (X) between the tangent in the lower point of the curved section (6) of the profile body (3) and the horizontal plane corresponds at least to 1.5 times, preferably at least 2 times, particularly preferably at least 3 times an angle (Y) between the screen plane (S) and the horizontal plane.