ES2553460T3 - Flexible fine screening mesh and vibrant sieve with flexible fine screening mesh - Google Patents

Abstract

Vibrating screen comprising a first mobile system that has first crossbars (2), as well as a second mobile system that has second crossbars (4), the first and second mobile system being arranged with relative motion to each other and at least one screening mesh, made of plastic fabric and fixed on both a first assigned crossbar and a second assigned crossbar, to achieve an alternative contraction and expansion of the screening meshes, the screening mesh being configured as a fine screening mesh ( 5) and being connected to the first assigned crossbar (2) and / or to the second assigned crossbar (4) by at least one connecting element respectively, characterized in that the joining element has a greater elongation of breakage compared to the screening mesh fine (5), made of plastic fabric.

Description

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DESCRIPTION

Flexible fine screening mesh and vibrating screen with flexible fine screening mesh Field of the invention

The present invention relates to a vibrating screen according to the preamble of claim 1, as well as a screening mesh unit for a vibrating screen according to the preamble of claim 12.

Vibrating screens are known. These are used for both coarse and fine grains and are characterized by the contraction and expansion of screening meshes, which essentially reduces the grain jam compared to sieves of immobile screening meshes.

State of the art

Conventional screening meshes are mostly made of polyurethane, the screening holes being made by die cutting. These screening meshes, manufactured in a conventional manner, are characterized by their robustness and permanent load capacity which in both cases are decisive criteria for use in vibrating screens, since due to the alternative expansion and contraction of the screening meshes produce alternate efforts that negatively influence the durability of the materials used.

The punching of the screening holes is, however, a long and expensive process that conditions a high time for the production of a screening mesh. In addition, the diameter of the screening holes cannot be arbitrarily reduced during punching due to technological reasons or, in other words, there is a limit value for the dimensions of the screening holes, from which its punching is no longer possible. , both in terms of technology and profitability. In practice, this limit value in the case of a mesh opening is approximately 1 mm for square screening holes and 0.4 mm x 4 mm for slot-shaped screening holes.

The practice shows, however, that there is a sufficient demand for sieves for extremely fine grain screening materials, so far no adequate solution has been found to correspondingly cover this demand in the vibrating sieves sector due to difficulties mentioned technologies.

From US 4,430,211, which discloses a vibrating screen according to the preamble of claim 1 and a screening mesh unit according to the preamble of claim 12, it is known, for example, a vibrating screen of the generic type with two systems of mobile crossings, the first system and the second system with relative movement being arranged, plastic screening meshes being provided, fixed in each case in a first assigned crossbar and also in a second assigned crossbar, to achieve a contraction and expansion screening mesh alternatives. The screening meshes are fixed in the crossbars by means of conventional tightening slats.

In other screening sectors, but not in the vibrant sieve sector, it is known to provide screening meshes made of wire mesh. Such screening mesh is known, for example, from DE 3811641 A1. These screening meshes allow the realization of especially small screening holes, but cannot be used in a vibrating screen due to the material, since the alternative contraction and expansion of the screening meshes, which occur in a vibrant sieve, are not possible in the case of wire mesh screening meshes or cause breakage quickly.

In other screening sectors it is known to use fine screening meshes, made of plastic fabric, for example polyamide fabric, for particularly fine grain screening materials. Unlike the solution with die cut polyurethane, these fine screening meshes provide, due to their manufacturing as a fabric, the possibility of designing especially fine screening meshes. This will also be accompanied by an essentially larger open screening surface, which also provides, among others, a small constructive size of the screens equipped with such fine screening meshes.

In fine screening meshes, made of plastic fabric, it is problematic, however, their insufficient elongation of breakage for use in vibrating screens, so that such plastic fabrics have not been used so far in vibrating screens. As already mentioned, in the vibrating screens the screening meshes are contracted and expanded alternately in order to avoid the jamming of grains, expanding the screening meshes excessively in each expansion process after such a contraction process that the whip effect produced almost completely prevents the clogging of grains and releases the clogged screening holes.

In conventional screening meshes, made of polyurethane and used in vibrating screens, this whip effect produced is not problematic because the polyurethane has an elongation of rupture of approximately 400%. The concept of elongation of rupture is a concept, used in elastomers, which is

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denominates fracture elongation in other materials and expresses the percentage, in which a material can expand before breaking. Due to its high elongation of breakage, polyurethane meshes are insensitive to the effect of whip that occurs when used in vibrating screens.

The plastic fabric, used as screening meshes in other screens, has, however, only an elongation of rupture of approximately 30% -40%, so that such screening meshes would be broken when these screening meshes are used in vibrating sieves and when the screening meshes expand excessively or when the whip effect occurs.

However, giving up the use of the whip effect would dramatically decrease screening performance due to the increase in jammed grains and would require downtime, in which the stuck grains would have to be removed by hand.

Presentation of the invention

Therefore, the aim of the present invention is to avoid this disadvantage and improve known vibrating screens so that they can also be used for extremely fine grain screening material.

Another objective of the invention is to adapt the vibrating screens so that it is possible to use fine plastic screening meshes, without destroying these screening meshes or reducing their durability to unacceptable values in practice.

According to the invention, this is achieved by the characteristics of claims 1 and 12.

According to claim 1, it is provided that the screening mesh is configured as a fine screening mesh in the case of known vibrating screens comprising a first mobile system having a first crossbar, as well as a second mobile system presenting a second crossbar, being arranged the first system and the second mobile system with relative movement between each other and at least one screening mesh being provided, made of plastic fabric and fixed both in a first assigned crossbar and in a second assigned crossbar, to achieve a contraction and a alternative expansion of the screening meshes, as well as it is envisaged that the screening mesh is linked to the first assigned crossbar and / or to the second assigned crossbar by means of at least one joint element respectively which has a greater elongation of breakage compared to the mesh Fine screening made of plastic fabric.

Due to the lower elongation of rupture, already mentioned, of the plastic fabric in comparison with the die-cut screening meshes of polyurethane, the whip effect is cushioned by the provision of one or more elastic joining elements between the fine screening mesh and the first or second mobile system or between the fine screening mesh and the first assigned crossbar or the second assigned crossbar, without impeding its cleaning effect on the screen holes. In this respect, the exact determination of the material of the joint element or the elongation of breakage of the material (for example, by means of the elastic modulus) of the joint element is important. The material should be selected so that the sharply produced load is not too dampened during the contraction and expansion of fine sieve meshes and thus prevents the appearance of the whip effect, which would prevent the cleaning of the clogged grains. On the other hand, the material should not be selected in such a way that there is too strong vibration of the fine sieve meshes.

According to a preferred embodiment variant of the invention, described in claim 2, it is provided that the at least one connecting element is a spring element, and a conventional helical spring which fixes the fine screening mesh can be used here, for example. in the first mobile system, for example, a screening box, or in the second mobile system, for example, a vibrating frame, by means of the respective crossbars.

According to another preferred embodiment of the invention, described in claim 3, it is envisaged that the joint element is a plastic fastening element that can be fixed in the first assigned crossbar and / or in the second assigned crossbar and in the that the fine screening mesh is cast. This embodiment variant is characterized by its particular robustness.

Another preferred embodiment of the invention according to claim 4 provides as a joint element a molten plastic bed in a housing of a fastening element that can be fixed in the first assigned crossbar and / or in the second assigned crossbar. In this plastic bed, the fine sieve mesh is melted. The clamping element may be made of a harder material in this case and may not have the elongation of breakage or elasticity required for the present case of application in a vibrating screen, since the element, which dampens the effect of whip, In this embodiment variant is the plastic bed that is configured in the fastener and in which the fine sieve mesh is cast. The fine screening mesh can be fixed in the plastic bed, for example, by melting the fine screening meshes in the plastic or, for example, by vulcanizing or gluing.

According to the characteristics of claim 5, the housings are configured in the form of a groove, a particularly simple fixation of the fine screening meshes being possible in the housing or in the plastic bed located inside.

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According to another preferred embodiment variant, described in claim 6, it is provided that the joining element and the fine screening mesh form an interchangeable screening mesh unit. This makes it possible to prefabricate such a screen mesh unit and fix it, for example, to hold it, in situ on the vibrating screen. Particularly in the case of an intended fastening element, its configuration may have a shape corresponding to the fixing possibilities, in particular of the crossbars, in the vibrating screen, so that quick fixation is possible and, nevertheless , safe from the screen mesh unit in the vibrating screen.

According to another variant of the preferred embodiment of the invention, provided in claim 7, the joining element is an elastic element, preferably separated, which is fixed in the first assigned crossbar or in the second assigned crossbar. In this case, the fine screening mesh, made of plastic fabric, can be fixed directly on the first assigned crossbar or on the second assigned crossbar.

In such a case, according to claim 8, fixing means are provided which join the elastic element, on the one hand, with the fine screening mesh and, on the other hand, with the first crossbar assigned or with the second crossbar assigned.

According to another preferred embodiment of the invention, described in claim 9, it is provided that at least one of the two groups of warp and weft threads of the plastic fabric, which forms the fine screening mesh, is arranged in position inclined with respect to the crossbars, that is, neither in parallel nor in a right angle with respect to them. In this way it is achieved that the plastic fabric presents in the direction of contraction or expansion of the vibrating screen an elongation of breakage or an elasticity greater than in the case of not being positioned in an inclined manner. Therefore, the joining element can be configured with a slightly greater stiffness, without the danger of breaking the fine screen mesh of plastic fabric.

In a particular embodiment according to claim 10, it is provided that the fine screen mesh of plastic fabric also functions as a joint element and that the elongation of breakage required to use the fine screen mesh in vibrating screens is achieved by the position corresponding slope of the warp and weft with respect to the crossbars. In this case, an additional connecting element is no longer necessary to fix the fine screening mesh in the crosspieces and the fine screening meshes of plastic fabric can be fixed conventionally in the crossbars.

According to the characteristics of claim 11, the mesh opening of the fine screening meshes of plastic fabric is less than 2 mm x 2 mm in the case of square sieve holes or 2 mm x X mm in the case of holes oblong (X = greater than 2 mm).

Claims 12 to 15 refer to a screening mesh unit for a vibrating screen with a screening mesh and a fastening element intended for fixing in a crossbar of a mobile system of the vibrating screen and disposed in the marginal zone, It is provided according to the invention in claim 12 that the screening mesh is configured as a fine screening mesh, made of plastic fabric, and that the fastener comprises a joint element that has a greater elongation of breakage compared to The fine screening mesh. The direct arrangement of the joint element, which serves as a damping element for the whip effect, in the plastic mesh screening mesh allows the use of fine screening meshes of plastic fabric with a correspondingly smaller mesh opening in vibrating screens , the joining element and the fine screening mesh forming an exchangeable unit that facilitates the replacement of the entire screening mesh unit in the vibrating screen.

According to a preferred embodiment variant of the invention, described in claim 13, the fastener element itself creates the joint between the fine screening mesh and the respective crossbars as a joint element with a greater elongation at break.

According to another preferred embodiment variant, described in claim 14, the fastener element has a housing, preferably in the form of a groove, with a plastic bed that functions as a joint element for the fine mesh screen of plastic fabric and with the one that is linked to the fine screening mesh, for example, by casting.

Brief description of the figures

The invention is described in detail below by means of an exemplary embodiment. They show: Figure 1, an axonometric view of a vibrating screen;

Figure 2, a schematic side view of a screening mesh unit, formed by a screening mesh and a connecting element, with spring element;

Figure 3, a schematic side view of a screening mesh unit, formed by a screening mesh and a

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union element, with clamping element and plastic bed;

Figure 4, a schematic side view of a screening mesh unit, formed by a screening mesh and a connecting element, with fastening element and without a plastic bed;

Figure 5, a schematic side view of a screening mesh unit in the state fixed in the crossbars;

Figure 6, a plan view of a screening mesh unit;

Figure 7, an alternative embodiment variant of a fastener element;

Figure 8, a schematic side view of a screening mesh unit in the state fixed in the crossbars;

Fig. 9, a schematic side view of a screen mesh unit in the state fixed in a crossbar with separate joint element;

Figure 10, a plan view of a screen mesh unit with weft or warp in an inclined position; and Figure 11, a plan view of a screen mesh unit with weft and warp in an inclined position.

You saw for the realization of the invention

Figure 1 shows as a preferred construction type a vibrating screen 1 with a screening box 3 as the first mobile system that has screening sides 3a, 3b and that rests on springs 15 with respect to a fixed bottom, and with a drive 16 that makes vibrate the screening box 3 and which may be designed, for example, as a single or double unbalanced drive. The screening sides 3a, 3b are connected to each other by means of several screening box crossings 2 that form first crossings arranged parallel to each other.

In the screening box 3 a second mobile system is configured, in this case as a vibrating frame, comprising push bars 17 supported on the screening sides 3a, 3b or in slats 18 arranged here. The support of the push bars 17 is executed by elastic elements, for example, rubber blocks or spring elements (not shown in both cases), so that the fundamental vibration of the screening box 3 excites the vibrating frame for another vibration with amplitude excitation.

The push bars 17 are joined together by vibrating frame cross members 4 forming second cross members arranged parallel to each other and parallel to the screen box crossings 2.

The screening surfaces are constructed by individual screening meshes that are alternately fixed in a vibrating frame crossbar 4 and in a screening box crossbar 2.

The vibrating screen works as follows: The vibrating frame is also vibrated with amplitude excitation by means of the screening box 3 which vibrates by the drive 16 designed as an unbalanced drive. As a result of the elastic support of the push bars 17 of the vibrating frame in the screening box 3 there is a vibration of the vibrating frame, offset with respect to the fundamental vibration of the screening box 3. Due to the alternative fixation of the meshes of screening in the screening box 3 or in the vibrating frame or more exactly in the screening box crossings 2 and in the vibrating frame crossings 4, the screening meshes contract and expand or expand in excess alternately, which allows not only screening the screening material, but also preventing the clogging of grains. This in turn provides an optimal screening effect.

The present embodiment shows a screening device with a screening plane. It is understood by itself that it is also possible to superimpose several planes and that this is also usual in vibrating screens. In this case, several push bars 17 are elastically supported on the screening box 3 or several vibrating frame cross members 4, which run in different planes, are elastically supported on a push bar 17.

The present vibration system can also be carried out with a banana type configuration with a sieve cover inclination that is reduced continuously.

In order to use the vibrating screens also in the fine grain sector, it is provided according to the invention that the screening mesh is configured as a fine screening mesh (5) of plastic fabric, joined with a vibrating frame traverse assigned 4 and / or an assigned screening box traverse 2 by at least one joining element, said joining element presenting a greater breakage elongation compared to the fine screening mesh 5 made of plastic fabric.

In this case it is necessary to differentiate in general between two different principles of realization, specifically, by a

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part, that principle, according to which the fine screening mesh forms an interchangeable screening mesh unit with the joint element. In this principle of realization, the joining element and the fine screening mesh are interconnected, preferably inseparably.

The second principle of realization provides that the joint element, which dampens the effect of whip, is an element arranged in the screening box crossbar 2 or in the corresponding vibrating frame crossbar 4, whose elongation of breakage is greater according to the invention than that of fine screening mesh.

Figures 2, 3 and 4 respectively show examples of realization that work according to the first principle of realization.

Figure 2 shows the schematic representation of a fine screening mesh 5 that is joined by a joint element, designed as a spring element 6, with a fastener element 12, already known, which only must meet the condition of being able to be fixed in a traverse 2, 4 of one of the two mobile systems.

Figure 3 shows a screening mesh unit with a fine screening mesh 5 and a fastening element 10 having a groove-shaped housing 11. In the groove-shaped housing 11 there is a joint element designed as a bed of plastic 7 and inserted in the housing or fixed here in another way. The ends of the plastic screening fabric are cast in the plastic bed 7.

In this case, the clamping element 10 can be made of a material with a lower elongation of breakage, since as a cushioning elastic element with a corresponding elongation of breakage, the plastic bed 7 is present which contributes to the effect of the whip produced Do not destroy the plastic fabric of the fine screening mesh.

Figure 4 shows another embodiment variant of the first embodiment principle. Here, a joining element, designed as a holding element 8, is fused directly with the fine screening mesh 5 and forms the joining element. In this variant embodiment, it is necessary, therefore, that the fastening element has the required elongation of rupture according to the invention must be greater than the elongation of rupture of the plastic fabric that forms the fine sieve mesh 5.

In FIGS. 2 to 4, the fasteners 8, 10, 12 respectively have a special design that allows a quick and safe fastening thereof to the screen box crossings 2 or the vibrating frame cross members 4, as shown in Fig. 5. For this purpose, the fasteners 8, 10, 12 have a corresponding notch 19 which allows them to fit into the screen box crossbars 2 or the vibrating frame crossbars 4. For the expansion of the support elements 8, 10, 12 in the screening box crossbars 2 or the vibrating frame crossbars 4, are provided, for example, one or more bolts 25 or a lath 25, so that the fasteners 8, 10, 12 remain firmly fixed on the screen box crossbars 2 or the vibrating frame crossbars 4.

In the case of the fasteners, shown in Figures 2 to 4, this is a possible embodiment variant. Of course, other embodiments are also possible which provide a secure fixation of the screening mesh units in the screening box crossings 2 or the vibrating frame crossings 4.

Figure 7, for example, shows such an alternative embodiment variant of a fastener. The screening mesh unit is formed by the fine screening mesh 5 and the clamping element 20, the clamping element 20 presenting a different form to the shape represented in figures 3 and 4, but its construction being identical, that is to say its construction , it has a housing with a plastic bed 7, in which the union element is cast, or constitutes by itself the union element and is manufactured in a correspondingly elastic manner. However, the clamping element 20 is flatly configured unlike the clamping elements 8, 10 of Figures 2, 3. For fixing on the screening box crossings 2 or the vibrating frame crossings 4, it is used in this case a fixing means 14, for example, a screw, as can be seen in figure 8.

Figure 6 shows in a plan view a fine screening mesh 5 of plastic fabric, according to the invention, as shown in Figures 2 to 5 and 7 and 8. The fastening element 8, 10, with which performs the fixation on the screening box crossings 2 or the vibrating frame crossings 4, extends in the longitudinal direction of the fine screening mesh along its marginal zone.

Figure 9 shows a variant of embodiment according to the second principle of realization. In this case, the connecting element 13, as a preferably separated element, is fixed in a screening box cross member 2 or a vibrating frame cross member 4 by means of a fixing means 14, for example, a screw. The fixing means 14 also serves at the same time for the direct fixation of the fine screening mesh 5, which in this case does not have to have a fastening element, in the screening box traverse 2 or the vibrating frame traverse 4 , by tightening between a clamping element 21 and the connecting element 13. In this way, a very elastic union of the fine screening surface of plastic fabric with the screen box crossings 2 or the frame cross members is also achieved. vibrant 4.

Figures 10 and 11 show a plan view of a fine screen mesh 5 of plastic fabric according to another preferred embodiment of the invention. By way of orientation, the screening box crossings 2 or the vibrating frame crossings 4 are shown schematically. The group of threads of the fabric, which forms the warp 23, is arranged here in an inclined position, instead of in parallel, with respect to to the screening address 24, as can be seen in Figure 10.

In another variant embodiment according to Figure 11, the group of threads, which forms the weft 22, is additionally arranged in an inclined position with respect to the screening box crossings 2 or the vibrating frame crossings 10. The inclined arrangement allows to achieve a greater elasticity of the plastic fabric in the direction of screening 24 and, consequently, an increase in the elongation of breakage. The fasteners 8, 10, shown in Figures 10 and 11, are no longer necessary if the groups of threads are in a sufficiently inclined position, so that in this special case, the plastic fabric itself constitutes the joining element . In such a case, an additional elastic bonding element is no longer necessary to join the fine screening mesh of plastic fabric to the cross-section 15 of the screening box 2 or to the cross-section of the vibrating frame 4.

However, such fine screening meshes with warp 22 and / or weft 23 in an inclined position can also be combined with fasteners 8, 10, as shown in Figures 3 and 4, or with spring elements 6, as shown in Figure 2.

Claims (15)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 55 60 1. Vibrating screen comprising a first mobile system that has first crossbars (2), as well as a second mobile system that features second crossbars (4), the first and second mobile system being arranged with relative movement between each other and being provided to the less a screening mesh, made of plastic fabric and fixed both in a first assigned crossbar and in a second assigned crossbar, to achieve an alternative contraction and expansion of the screening meshes, the screening mesh being configured as a screening mesh fine (5) and being attached to the first assigned crossbar (2) and / or to the second assigned crossbar (4) by at least one joint element respectively, characterized in that the joint element has a greater elongation of breakage compared to the mesh fine screening (5), made of plastic fabric. 2. Vibrating screen according to claim 1, characterized in that the joint element is a spring element (6). 3. Vibrating screen (1) according to claim 1, characterized in that the joining element is a plastic holding element (8) that can be fixed in the second assigned crossbar (4) and / or the first assigned crossbar (2) and in which the fine sieve mesh is fused (5). 4. Vibrating screen (1) according to claim 1, characterized in that the joint element is a plastic bed (7) that is cast in a housing (11) of a fastening element (10), which can be fixed in the first assigned crossbar (2) and / or the second assigned crossbar (4), and in which the fine screen mesh (5) is cast. 5. Vibrating screen (1) according to claim 4, characterized in that the housing (11) is configured as a groove. 6. Vibrating screen according to one of claims 1 to 5, characterized in that the joining element and the fine screening mesh (5) form an interchangeable screening mesh unit. 7. Vibrating screen (1) according to claim 1, characterized in that the joint element is an elastic element (13), preferably separated and arranged in the second assigned crossbar (4) or the first assigned crossbar (2). 8. Vibrating screen (1) according to claim 7, characterized in that fixing means (14) are provided that join the elastic element (13), on the one hand, with the fine screening mesh (5) and, on the other hand , with the first assigned traverse (2) or the second assigned traverse (4). 9. Vibrating screen according to one of claims 1 to 8, characterized in that at least one of the two groups of yarn, made of warp (23) and weft (22), of the plastic fabric, which forms the fine screening mesh ( 5), it is arranged in an inclined position with respect to the crossings or to the transport direction (24). 10. Vibrating screen according to claim 1, characterized in that the joint element is the screening mesh itself and at least one of the two groups of yarn, warp compounds (23) and weft (22), of the plastic fabric, which It forms the fine screening mesh (5), is arranged in an inclined position with respect to the crossbars (2, 4). 11. Vibrating screen according to one of claims 1 to 10, characterized in that the mesh opening of the fine screening meshes (5) is smaller than 2 mm. 12. Screen mesh unit for a vibrating screen (1) according to claim 1 with a screen mesh, made of plastic fabric, and with a fastening element (8, 10), intended for fixing on a crossbar ( 2) of a mobile system of the vibrating screen (1) and arranged in the marginal area of the screening mesh, the screening mesh being configured as a fine screening mesh (5), made of plastic fabric, and comprising the fastener element (8, 10) a joint element, characterized in that the joint element has a greater elongation of rupture compared to the fine screen mesh (5). 13. Screen mesh unit according to claim 12, characterized in that the fastener element (8) is designed as a joint element (8). 14. Screen mesh unit according to claim 12, characterized in that the clamping element (10) has a housing (11), preferably in the form of a groove, with a plastic bed (7) as a joint element, with which The fine sieve mesh (5) is attached, preferably molten. 15. Screen mesh unit according to one of claims 12 to 14, characterized in that the mesh opening of the fine screen meshes (5) is smaller than 2 mm.