EP2962773B1 - Plastic screen lining for a screening machine for classifying in particular fine-grained material to be screened - Google Patents

Description

The invention relates to a plastic screen covering for a screening machine for classifying in particular fine-grained bulk material, the screen mesh 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 is a Kunststoffsiebbelag made of polyurethane material, the regularly spaced over longitudinal and transverse webs Siebmaschen one elongated have 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 these bulges and an oval mesh shape take on one another. 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.

The NL 278883 discloses a plastic screen covering having mirror-symmetrical meshes having a narrow center region and the opposite wider end regions on both sides. The gap width of the sieve meshes is adjusted before use of the plastic sieve lining by pulling in the mesh longitudinal direction, so that the plastic sieve lining is biased.

The US 2013/0126397 A1 discloses a screen covering whose individual screen meshes are provided with a plurality of bulges arranged along the longitudinal extension. If the sieved material exerts a high work load when sieving on these sieve meshes, as a result of deformations, the center region of these sieve meshes may widen and sieve material having a coarser grain size may pass through the sieve lining.

The DE 38 42 041 A1 discloses a screened plastic mesh lining having, in one embodiment, a narrow center region and wider end regions. The intervening webs are elastically deformable under work load. However, this deformation does not aim at a precise adjustment of the screened grain size.

It is therefore an object of the present invention to provide a Kunststoffsiebbelag, which is 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. 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 other words, a specially shaped waisted screen mesh is proposed, which assumes an approximately rectangular mesh size only under load of Siebbelags. The sieve meshes pre-profiled according to the invention are most extensively widened under load of the plastic sieve covering during the sieving in the sieve plane at the narrow middle region having the minimum width, since the webs between the Siebmaschen are the 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 area of the screen mesh can be indicated via a waisting angle, which extends between the longitudinal direction of the screen mesh and a mesh edge section adjoining the end region and is between 0.4 and 15 degrees. Depending on the material properties, screen cover 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 middle 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 sieve lining according to the invention, the minimum width of the sieve mesh is between 0.05 to 1 mm. The tuned length of the screen mesh should be in a range between 0.3 to 20mm.

The Siebbelagdicke is in this preferred embodiment of the Kunststoffsiebbelags preferably in the range between 0.5 to 5mm, the sieve mesh in cross section preferably conically under a widening in the direction of diarrhea of the Siebguts Edge angle between 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 in this respect parallel to each other along the plastic screen covering extending rail-like Materialanformungen lead the screenings on the screen covering.

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.

Figur 1

eine schematische perspektivische Ansicht eines Kunststoffsiebbelags in einer ersten Ausführungsform,

Figur 2

eine schematische perspektivische Ansicht eines Kunststoffsiebbelags in einer zweiten Ausführungsform,

Figur 3

eine schematische Daraufsicht einer Auswahl von Siebmaschen im Ausgangszustand gemäß einer ersten Ausführungsform,

Figur 4

eine schematische Daraufsicht einer Auswahl von Siebmaschen im Belastungszustand gemäß der ersten Ausführungsform,

Figur 5

eine schematische Daraufsicht einer Auswahl von Siebmaschen im Ausgangszustand gemäß einer zweiten Ausführungsform und

Figur 6

eine Detaildarstellung im Schnitt A-A einer Siebmasche aus Figur 5.

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:

FIG. 1

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

FIG. 2

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

FIG. 3

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

FIG. 4

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

FIG. 5

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

FIG. 6

a detailed representation in section AA of a sieve mesh FIG. 5 ,

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

To reinforce the Kunststoffsiebbelags extending 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 covering. The reinforcing threads 2 run inside the web area next to the screen meshes 1.

According to the alternative embodiment according to FIG. 2 Reinforcement threads 2 'are provided only in the longitudinal direction L of the Kunststoffsiebbelags. Rail-like material projections 3 are arranged along the reinforcing threads 2 'on the wire butt side. The rail-like Materialanformungen 3 have seen in cross section a wedge-shaped shape.

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

The row of wire meshes 1a and 1b is divided by the row of wire meshes 1c and 1d by longitudinal webs 4. In each case adjacent Siebmaschen 1 a and 1 c and 1 b and 1 d are divided by transverse webs 5 from each other. As a result of the regular grid structure of the mesh arrangement created in this way, a four-sided node K1, which is indicated here by a dashed circular line, is formed in each case in the crossing region of the longitudinal webs 4 with the transverse webs 5.

Each screen mesh 1c (by way of example) has a narrow center region 6 in the longitudinal direction L, the minimum width B _{m of which is} smaller than the maximum width B _{e of} the mutually adjacent end regions 7a and 7b. The two end regions 7a and 7b of each sieve mesh 1c are semicircular in this embodiment. The waisting angle α between the longitudinal direction L of the screen mesh 1c and a mesh edge section 8 adjoining the end region 7a is approximately 10 °.

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

At the in FIG. 5 shown embodiment, adjacent rows of Siebmaschen 1 a 'and 1 b' and 1 c 'and 1 d' offset from one another. This forms a three-sided node K2 and the longitudinal webs 4 'and transverse webs 5' can be made narrower compared to the embodiment described above, so that the ratio of sieve mesh surface increased to web surface and thus a higher sieve throughput can be achieved.

The sectional view AA according to FIG. 6 illustrates that the screen mesh 1c 'extends (exemplary) from the screen top to the bottom of the sieve conically widening at an edge angle β, to avoid jamming of sieved particles within the sieve mesh 1c'.

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. That's the way it is, for example possible to integrate reinforcing threads 2 only in the longitudinal direction L or in the transverse direction Q and spaced apart by a plurality of Siebmaschen. The rail-shaped material projections 3 can form reinforcements in the region of guided reinforcing threads 2.

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)

1. Plastic screen lining for screening machines for classifying in particular fine-grained screen material, the screen meshes (1) of which, formed by longitudinal webs (4) and transverse webs (5), extend longitudinally or transversely to the direction of screen movement (A) and each have a mirror-symmetrical shape both in the longitudinal direction (L) and in the transverse direction (Q), the screen mesh (1a; 1b; 1c; 1d) in the longitudinal direction (L) has a narrow central region (6) whose minimum width (B_m) is smaller than the maximum width (B_e) of the end regions (7a, 7b) adjacent on both sides,
   characterized in that the screen mesh (1a; 1b; 1c; 1d) is a waisted screen mesh which only assumes a rectangular basic shape by elastic deformation under a working load, in which the dimension of the width (Bm) in the central region (6) approaches the dimension of the width (Be) of the two end regions (7a, 7b).
2. Plastic screen lining according to claim 1,
   characterized in that the two end regions (7a, 7b) of the screen mesh are formed in a semi-circular manner, in an arcuate manner or with rounded corners of edge portions meeting one another.
3. Plastic screen lining according to claim 1,
   characterized in that the waist angle (α) between the longitudinal direction (L) of the screen mesh (1a; 1b; 1c; 1d) and a mesh edge portion (8) adjacent the end portion (7a; 7b) is between 0.4 to 15° to produce the minimum width (B_m) at the center of the center portion (6) of the screen mesh (1a; 1b; 1c; 1d).
4. Plastic screen lining according to claim 1,
   characterized in that the ratio between maximum width (B_e) and minimum width (B_m) of the screen meshes (1a; 1b; 1c; 1d) is in the range between 1.1 to 2.5.
5. Plastic screen lining according to claim 1,
   characterized in that the minimum width (B_m) of the screen mesh (1a; 1b; 1c; 1d) is between 0.05 to 1 mm, and that the length of the screen mesh (1a; 1b; 1c; 1d) is in the range between 0.3 to 20 mm.
6. Plastic screen lining according to claim 1,
   characterized in that the screen lining thickness is in the range between 0.5 to 5 mm.
7. Plastic screen lining according to claim 1,
   characterized in that the screen mesh (1a; 1b; 1c; 1d) in cross-section extends conically under an edge angle (β) between 5° to 20° widening in the direction of sifting of the screenings.
8. Plastic screen lining according to claim 1,
   characterized in that the screen structure formed by the longitudinal webs (4) and transverse webs (5) is made of a polyurethane material.
9. Plastic screen lining according to claim 1,
   characterized in that reinforcing threads (2) of a fibrous material extend at least through a part of the longitudinal webs (4) and/or transverse webs (5) within the polyurethane material.
10. Plastic screen lining according to claim 9,
    characterized in that an material molding (3) which is wedge-shaped, arcuate or polygonal in cross-section is arranged on the upper side of the screen in the region along at least one reinforcing thread (2).
11. Plastic screen lining according to claim 1,
    characterized in that the screen meshes (1a; 1b; 1c; 1d) are arranged in series side by side and one above the other to form a regular lattice structure.
12. Plastic screen lining according to claim 1,
    characterized in that adjacent rows of screen meshes (1a; 1b; 1c; 1d) arranged one above the other in the longitudinal direction (L) are arranged offset from one another.
13. Screening machine for classifying in particular fine-grained screenings with an electrically operated mechanical vibration drive, comprising an exchangeable plastic screen lining according to one of the preceding claims.

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