DE102014009702B3 - Plastic screen covering for a screening machine for classifying in particular fine-grained bulk material - Google Patents

Abstract

The invention relates to a plastic screen covering for a screening machine for classifying, in particular, fine-grained screenings, the screen meshes (1a; 1b; 1c; 1d) formed by longitudinal webs (4) and transverse webs (5) extending longitudinally or transversely to the direction of wire movement movement (A) and both in the longitudinal direction (L) and in the transverse direction (Q) have a mirror-symmetrical shape, the Siebmasche (1a; 1b; 1c; 1d) in the longitudinal direction (L) has a narrow central region () whose minimum width (Bm) is smaller than the maximum width (Be) of the adjacent end portions (7a, 7b) on both sides.

Description

The invention relates to a plastic screen covering for a screening machine for classifying in particular fine-grained bulk material, the screen meshes formed by longitudinal webs and transverse webs extending longitudinally or transversely to Siebarbeitsbewegungsrichtung and each have a mirror-symmetrical shape both in the longitudinal direction and in the transverse direction. In addition, the invention also relates to a sieve machine comprising this plastic sieve covering with an electrically operated mechanical oscillating drive.

The field of application of the invention extends to the screening of bulk material, which may be in the form of a dry solid or in a suspension. In particular, the solution according to the invention can also be used in the field of wet fine classification. Screen coverings of the type of interest here are usually not made of metal, but of plastic, in particular polyurethane, and have a plurality of openings, so-called sieve mesh through which the sieved bulk material falls through, whereas the relatively coarse-grained residue on the Sieboberseite remains. The Siebarbeitsbewegung in the form of a main back and shake the Siebbelags is performed by a known screening machine, in addition to the receiving box for the screenings usually an electrically operated mechanical vibration drive is mounted. The plastic sieve is interchangeable mounted in the area of the bottom of the sieve box.

From the US 4,857,176 A is a Kunststoffsiebbelag made of polyurethane material, which regularly have longitudinal and transverse webs separately arranged Siebmaschen an elongated rectangular shape. In the webs reinforcing threads are molded from a fiber material to increase the tensile strength of the material.

In sieve operation, a load is exerted on the rectangular sieve meshes so that they bulge out and assume an oval mesh shape. As a result, even larger particles than desired can fall through these deformed meshes. Especially with small web widths and high ratios between mesh length and mesh width, the proportion of defective grain increases. In addition, notch stresses, which can lead to cracking, which causes premature wear of the Siebbelags arise in the right angles tapered corners of the rectangular Siebmaschen.

From the AT 19 449 B For example, a metallic sorting plate is known in which the ends of the meshes are provided with round extensions. These extensions facilitate the passage of the bulk material at the ends of the Siebmaschen and prevent their clogging.

It is therefore the object of the present invention to provide a Kunststoffsiebbelag and a screening machine, which are characterized by a precise screening and a long service life.

The object is achieved on the basis of a screen covering according to the preamble of claim 1 in conjunction with its characterizing features and by a screening machine according to claim 13. The following dependent claims give advantageous developments of the invention.

The invention includes the technical teaching that the Siebmaschen the Kunststoffsiebbelags each viewed in the longitudinal direction have a narrow central region, the minimum width is smaller than the maximum width of both sides adjacent end regions. In this case, the sieve mesh takes on a substantially rectangular basic shape by elastic deformation under working load, in which approach the dimension of the width in the central region approaches the dimension of the width of the two end regions.

In other words, a specially shaped waisted screen mesh is proposed, which assumes an approximately rectangular mesh size only under load of Siebbelags. The Siebvorchen vorvorierten Siebmaschen are under load of the Kunststoffsiebbelags during sieving in the plane of the sieve at the minimum width having narrow central area widens the widest, since the webs between the Siebmaschen are weakest at this point. In existing on both sides of the central region end of the Siebmasche, which represents a club-shaped extension of Siebmaschen, there are crossing points, which deform less under load, since more material is present at the intersection.

According to a preferred embodiment of the sieve mesh according to the invention, the two end regions are formed approximately semicircular in order to form no points of attack for damaging notch stresses. In addition, it is also possible to form the end regions arcuate or as meeting edge portions with rounded corners in order to achieve the same advantage.

The minimum width in the center of the center region of the screen mesh can be specified via a waisting angle, which extends between the longitudinal direction of the screen mesh and a mesh edge section adjoining the end region, and 0.4 to 15 degrees. Depending on the material properties, screen lining thickness and mesh size, an optimum ratio between the maximum width in the end region of the screen mesh and the minimum width in the central center region of the screen mesh, which lies between 1.1 and 2.5, is achieved in this angular range.

In particular, for sieving in the fine grain range, according to a preferred embodiment of the plastic screen covering according to the invention, the minimum width of the screen mesh is 0.05 to 1 mm. The tuned length of the screen mesh should be in a range of 0.3 to 20 mm.

The Siebbelagdicke is in this preferred embodiment of the Kunststoffsiebbelags preferably in the range of 0.5 to 5 mm, the Siebmasche in cross-section preferably extends conically under a widening in Durchfallrichtung Siebguts edge angle of 5 ° to 20 °. This edge angle prevents jamming of the screened material falling through in the screen mesh.

According to a further measure improving the invention, it is proposed that reinforcement threads extend at least through part of the longitudinal webs and / or the transverse webs within the polyurethane material from a fibrous material which is preferably cast in here.

For directing the Siebguts during the screening process is also proposed that preferably a cross-sectional wedge-shaped, arcuate or polygonal raised polyurethane Materialanformung is arranged on the Sieboberfläche in the area along at least one reinforcing thread. These rail-like material projections, which extend parallel to one another in this respect over the plastic screen covering, guide the screenings over the screen lining.

According to a first embodiment of a screen mesh arrangement, it is proposed to arrange the screen meshes in series next to and above one another in order to form a regular grid structure. This lattice structure allows rectilinear longitudinal and transverse webs, which may be at least partially penetrated by reinforcing threads, in particular to maximize the strength of the Kunststoffsiebbelags.

According to an alternative embodiment, it is proposed that adjacent rows are arranged offset in the longitudinal direction one above the other arranged meshes. This embodiment leads to narrower nodes and thus to a better ratio between open screen area and web area, without impairing the functionality of the shape matching of the screen meshes under load.

With the solution according to the invention, a high precision of the separating cut can be achieved despite the fine structures of the screen lining. In particular, this advantage has an effect on fiber-reinforced polyurethane screens which, due to their flat design, have small web cross-sections.

Further measures improving the invention will be described in more detail below together with the description of preferred embodiments of the invention with reference to FIGS. Show it:

1 a schematic perspective view of a Kunststoffsiebbelags in a first embodiment,

2 a schematic perspective view of a Kunststoffsiebbelags in a second embodiment,

3 a schematic plan view of a selection of meshes in the initial state according to a first embodiment,

4 FIG. 2 is a schematic plan view of a selection of strained meshes in the loaded state according to the first embodiment; FIG.

5 a schematic top view of a selection of Siebmaschen in the initial state according to a second embodiment and

6 a detailed representation in section AA of a sieve mesh 5 ,

According to 1 comprises a plastic screen covering made of polyurethane in rows arranged side by side sieve mesh 1 which have a mirror-symmetrical shape both in the longitudinal direction L and in the transverse direction Q. The sieve meshes 1 extend longitudinally to Siebarbeitsbewegungsrichtung A, which is produced by a - not shown - screening machine.

To reinforce the Kunststoffsiebbelags extend in the longitudinal direction L as well as in the transverse direction Q a plurality of mutually parallel reinforcing threads 2 made of a fiber material through the plastic screen coating. The reinforcing threads 2 thereby run within the web area next to the Siebmaschen 1 ,

According to the alternative embodiment according to 2 are reinforcing threads 2 ' provided only in the longitudinal direction L of the Kunststoffsiebbelags. At the Sieboberseite are along the reinforcing threads 2 ' rail-like Materialanformungen 3 arranged. The rail-like Materialanformungen 3 have a wedge-shaped shape seen in cross-section.

After the in 3 shown first embodiment of a plastic mesh coating with regular grid structure are the exemplary Siebmaschen 1a and 1b such as 1c and 1d arranged one above the other in the longitudinal direction L. In the transverse direction Q are the Siebmaschen 1a and 1c such as 1b and 1d arranged exactly next to each other. Schematically, only a portion of the Siebmaschen a Kunststoffsiebbelags are shown here.

The row of meshes 1a and 1b gets from the row of sieve meshes 1c and 1d through longitudinal webs 4 divided. In each case adjacent Siebmaschen 1a and 1c such as 1b and 1d be through crossbars 5 shared by each other. As a result of the regular grid structure of the mesh arrangement created in this way, the longitudinal webs are created in the intersection area 4 with the crossbars 5 in each case a four-sided node K1, which is indicated here by a dashed circle.

Every sieve mesh 1c (by way of example) has a narrow middle region in the longitudinal direction L. 6 whose minimum width B _{m is} smaller than the maximum width B _{e of} the adjacent end regions on both sides 7a and 7b is. The two end areas 7a and 7b every sieve mesh 1c are semicircular in this embodiment. The waisting angle α between the longitudinal direction L of the mesh 1c and one at the end 7a adjacent mesh edge section 8th is about 10 °.

According to 4 subject to the sieve mesh 1c (exemplary) under workload of elastic deformation, so that this is a substantially rectangular basic shape - except for the rounded end portions 7a and 7b - accept. In the case of this rectangular basic shape under load, the dimension of the width B _m approaches in the middle region 6 to the extent of the width B _{e of} the two end regions 7a and 7b at; ideally these dimensions are the same.

At the in 5 shown embodiment are adjacent rows of Siebmaschen 1a ' and 1b ' such as 1c ' and 1d ' staggered to each other. This forms a three-sided node K2 and the longitudinal webs 4 ' and crossbars 5 ' can be made narrower compared to the embodiment described above, so that the ratio of Siebmaschenfläche increased to web surface and thus a higher throughput of sieve can be achieved.

The sectional view AA according to 6 clarifies that the mesh 1d ' (by way of example) extends from the screen top side to the bottom side of the sieve in a widening manner at an edge angle β, in order to jam sieved particles within the sieve mesh 1d ' to avoid.

The invention is not limited to the two embodiments described above. On the contrary, modifications are conceivable which are included in the scope of protection of the following claims. So it is also possible, for example, reinforcing threads 2 only in the longitudinal direction L or in the transverse direction Q and by several Siebmaschen spaced apart from each other to integrate. The rail-shaped Materialanformungen 3 can thereby material reinforcements in the area guided by reinforcing threads 2 form.

LIST OF REFERENCE NUMBERS

1

screen mesh

2

reinforcing thread

3

material accumulation

4

longitudinal web

5

crosspiece

6

the central region

7

end

8th

Mesh edge portion

L

longitudinal direction

Q

transversely

A

Siebarbeitsbewegungsrichtung

B _m

minimum width

B _e

maximum width

α

Taillierungswinkel

β

edge angle

K1

Node, four sided

K2

Node, three-sided

Claims (13)

Plastic screen covering for a screening machine for classifying, in particular, fine-grained bulk material, whose longitudinal webs ( 4 ) and transverse webs ( 5 ) formed Siebmaschen ( 1 ) extend longitudinally or transversely to the Siebarbeitsbewegungsrichtung (A) and each in both the longitudinal direction (L) and in the transverse direction (Q) have a mirror-symmetrical shape, characterized in that the Siebmasche ( 1a ; 1b ; 1c ; 1d ) in the longitudinal direction (L) a narrow central region ( 6 ) whose minimum width (B _m ) is smaller than the maximum width (B _e ) of the adjacent end regions ( 7a . 7b ), whereby the sieve mesh ( 1a ; 1b ; 1c ; 1d ) assumes by elastic deformation under work load a substantially rectangular basic shape, in which the dimension of the width (B _m ) in the central region ( 6 ) to the extent of the width (B _e ) of the two end regions ( 7a . 7b ) approximates. Plastic sieve covering according to claim 1, characterized in that the two end regions ( 7a . 7b ) of the sieve mesh semicircular, arcuate or are formed with rounded corners meeting edge portions. Plastic sieve covering according to claim 1, characterized in that the waisting angle (α) between the longitudinal direction (L) of the sieve mesh ( 1a ; 1b ; 1c ; 1d ) and one at the end ( 7a ; 7b ) adjacent mesh edge portion ( 8th ) of 0.4 to 15 ° to the minimum width (B _m ) in the center of the central region ( 6 ) of the mesh ( 1a ; 1b ; 1c ; 1d ) to create. Plastic sieve covering according to claim 1, characterized in that the ratio between the maximum width (B _e ) and the minimum width (B _m ) of the sieve meshes (B _m ) 1a ; 1b ; 1c ; 1d ) is in the range of 1.1 to 2.5. Plastic sieve covering according to claim 1, characterized in that the minimum width (B _m ) of the sieve mesh ( 1a ; 1b ; 1c ; 1d ) 0.05 to 1 mm, and that the length of the mesh ( 1a ; 1b ; 1c ; 1d ) is in the range of 0.3 to 20 mm. Plastic screen covering according to claim 1, characterized in that the Siebbelagdicke is in the range of 0.5 to 5 mm. Plastic sieve covering according to claim 1, characterized in that the sieve mesh ( 1a ; 1b ; 1c ; 1d ) in the cross-section conically under a extending in the direction of diarrhea of Siebguts edge angle (β) of 5 ° to 20 °. Plastic sieve covering according to claim 1, characterized in that by the longitudinal webs ( 4 ) and transverse webs ( 5 ) formed sieve structure is made of a polyurethane material. Plastic sieve according to claim 1, characterized in that at least by a part of the longitudinal webs ( 4 ) and / or transverse webs ( 5 ) within the polyurethane material reinforcing threads ( 2 ) extend from a fiber material. Plastic sieve covering according to claim 1, characterized in that on the sieve top side in the region along at least one reinforcing thread ( 2 ) a wedge-shaped in cross section, arcuate or polygonal Materialanformung ( 3 ) is arranged. Plastic sieve covering according to claim 1, characterized in that the sieve meshes ( 1a ; 1b ; 1c ; 1d ) are juxtaposed and stacked in series to form a regular lattice structure. Plastic sieve covering according to claim 1, characterized in that adjacent rows in the longitudinal direction (L) of sieve meshes arranged one above the other ( 1a ; 1b ; 1c ; 1d ) are offset from one another. Screening machine for classifying in particular fine-grained screenings with an electrically operated mechanical oscillating drive, comprising an exchangeable plastic screen covering according to one of the preceding claims.

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