Device and method for hydrodynamically strengthening a material web

Abstract

The invention relates to a device and a method for consolidating and transferring a nonwoven fabric from a first circulating belt (7a) to a second transport element arranged above it, with at least one water bar (8.1), wherein the first circulating belt (7a) is designed as a liquid-permeable transport belt, the second transport element is designed as a liquid-permeable drum (8) and has at least one suction opening (8c) for suctioning liquids, and the at least one water bar (8.1) is arranged below the circulating belt (7a) and is designed to consolidate the nonwoven fabric and detach it from the circulating belt (7a) by means of water jets at high pressure through the circulating belt (7a), characterized in that the water bar (8.1) with the direction of action of the water jets opposite to the material transport direction by an angle (α) of 1 - 6°, preferably rotated by 3° and shifted in the material transport direction.

Description

[0001] The invention relates to a device and a method for the hydrodynamic consolidation of a web of material.

[0002] From DE 10 2005 055 939 B3, a nozzle bar for processing textiles with water jets is known. The processing of the textile, for example in the form of consolidation, structuring, or perforation, is carried out with a multitude of water jets generated in a row, which extend, for example, across the entire width of a textile web moving beneath them and act upon it. For this purpose, the nozzle bar has a water connection through which water is fed into the pressure chamber via the opening. The water enters the pressure chamber through the opening at a pre-pressure of, for example, 250 bar. The nozzle bar is elongated and thus slender, and is essentially formed by an elongated upper section that houses the pressure chamber and an elongated lower section on or in which a nozzle strip is arranged.The lower part is arranged in a liquid-tight manner on the side of the upper part that faces the textile material, and the water jets are generated via the lower part and via the nozzle strip arranged in or on the lower part by the multitude of bores that are introduced in the nozzle strip.

[0003] Since a web of material is often compacted and structured from the top and bottom by several nozzle bars, it is transferred from a first circulating conveyor belt to a second conveyor belt or a water-absorbing drum, which are arranged either vertically or offset from each other. For this to occur, the web must be detached from the first conveyor belt. EP 2113041 B1, for example, suggests making the distance between the vertically stacked transport elements (belt / belt or belt / drum) greater than the thickness of the web, in order to lift the web from the lower conveyor belt.

[0004] A disadvantage is that the consolidation of the nonwoven fabric is insufficient with regard to its fiber properties. For example, the fiber orientation can only be influenced inadequately. The method described in EP 2113041 B1 is disadvantageous for fiber blends with a high proportion of short fibers, as the fiber web can be damaged by lifting at low basis weights, and fiber washout increases. Furthermore, the plant configuration is disadvantageous because it has an excessively large longitudinal extent due to the necessary pre-consolidation.

[0005] The object of the invention is to improve the existing device with the aim of creating improved consolidation and transfer of the nonwoven fabric from a first conveyor belt to a second conveyor element arranged above it.

[0006] This problem is solved by means of a device for consolidating and transferring a nonwoven fabric from a first circulating belt to a second transport element arranged above it, which includes at least one water beam. The first circulating belt is designed as a liquid-permeable conveyor belt, and the second transport element as a liquid-permeable drum. The second transport element has at least one suction opening for extracting liquids. The at least one water beam is arranged below the circulating belt and is designed to consolidate the nonwoven fabric and detach it from the circulating belt by means of high-pressure water jets.

[0007] The consolidation is achieved by arranging the water beam at an angle (α) of 1–6°, preferably 3°, opposite to the direction of material transport, with the direction of the water jets. This causes the nonwoven fabric to be compressed against the second transport element, thereby consolidating the nonwoven and aligning the fibers. This technical effect improves the MD / CD ratio of the fibers and alters the strength of the nonwoven fabric. Since the nonwoven fabric is in contact with both the circulating belt and the drum at the point where the water jets impact it, the web is not damaged and fiber washout is reduced.

[0008] Shifting the water beam in the material transport direction improves the separation of the nonwoven fabric from the circulating belt. This is because, by moving the point of impact of the water jets laterally to the drum's central axis, the distance between the circulating belt and the second transport element located above it is increased. The water jets detach the nonwoven fabric from the circulating belt and transfer it to the drum. Even at this point, the nonwoven fabric is still in contact with both the circulating belt and the drum. The elastic properties of the nonwoven fabric are utilized to detach it from the circulating belt. The impact of the water jets briefly lifts the fabric from the belt, and the suction from the discharge opening then transfers it to the drum.

[0009] In order to efficiently extract the water jets and prevent them from rebounding from the drum, the position of at least one extraction opening of the transport element located above is also changed so that it corresponds to the direction and position of the water jets.

[0010] Preferably, the second transport element is designed as a drum with a rotating, liquid-permeable outer shell and a suction area with at least one suction opening. The suction area can be positioned inside the drum and fixed in place so that the at least one suction opening corresponds to the direction of action of the water jets from the nozzle bar.

[0011] A further technical advantage is achieved by making the distance (B) between the drum and the circulating belt adjustable, and by setting it to compact the nonwoven fabric. The distance between the drum and the circulating belt should not exceed the thickness of the nonwoven fabric. By reducing the distance between the drum and the circulating belt, the degree of compaction can be adjusted. This compaction increases the strength of the nonwoven fabric, resulting in less fiber being washed out during the subsequent waterjet bonding process. It also facilitates the release of the nonwoven fabric from the circulating belt and its transfer to the drum above, as it has already been compacted. The combination of compaction and bonding allows for a shorter and more cost-effective system, as pre-bonding is no longer necessary.

[0012] To transfer the nonwoven fabric, the water jet from the water bar strikes the fabric at a point where it is in contact with both the circulating belt and the drum. This prevents damage to the nonwoven and reduces fiber loss.

[0013] The inventive method for consolidating and detaching a nonwoven fabric from a first circulating conveyor belt onto a second conveyor element arranged above it by means of water jets provides that water jets act through the conveyor belt onto the underside of the nonwoven fabric. A suction opening on the second conveyor element is associated with the water jets, through which the water is extracted.

[0014] The water jets strike the nonwoven fabric at an angle (α) of 1–6°, preferably 3°, opposite to the material flow direction, thus consolidating it. Due to the opposing direction of the water jets, the nonwoven fabric is compressed on the opposite drum, and the fibers are aligned, thereby adjusting and improving the MD / CD ratio and thus the direction of higher or more uniform strength.

[0015] To detach the nonwoven fabric from the circulating belt, its elastic properties are utilized. The impacting water jets briefly detach the fabric from the belt, and it is then drawn onto the drum by the suction of the extraction opening. By shifting the point of impact of the water jets on the nonwoven fabric in the material transport direction, the water jet strikes a point on the fabric where it has relaxed again after compaction. Here, the elastic properties of the nonwoven fabric can be used to detach it from the lower transport element.

[0016] Preferably, the suction of the water jets of the transport element arranged above is adjusted so that, with the rotation of the water jets against the material transport direction and the displacement of the water jets in the material transport direction, the suction opening corresponds to the direction and position of the water jets.

[0017] Separate pre-compaction can be omitted by compacting the nonwoven fabric between the circulating belt and the second transport element. For this purpose, the distance B between the conveyor belt and the second transport element is set to a value that is smaller than the thickness of the nonwoven fabric.

[0018] Further measures improving the invention are described in more detail below together with a description of a preferred embodiment of the invention with reference to the figures.

[0019] They show: Fig. 1: A first layout of a plant for the production of a nonwoven fabric; Fig. 2: An enlarged view of the first drum with the transport table; Fig. 3: A further embodiment of the solution according to the invention.

[0020] Figure 1Figure 100 shows a system for the production of, for example, a single- or two-layer nonwoven fabric, which introduces a loose fiber material 2 into the system by means of an inclined screen former 1 and a carded nonwoven fabric 5a by means of a carding machine 5.

[0021] The one in Figure 1 The introduced carded nonwoven fabric 5a can be formed as an unconsolidated nonwoven fabric from a carding machine 5, or as a consolidated nonwoven fabric from a carding machine 5 with subsequent consolidation not shown or from an unwinding station into the system 100.

[0022] For example, this carded nonwoven fabric 5a can be combined with a layer of unbonded fibers, which are introduced into the system, for example, from an inclined wire former 1. Instead of the inclined wire former, any other device for producing and depositing loose fibers can also be used, such as an airlay carding machine, a secondary stock headbox, or a meltblown machine. The sequence of the fiber layers (carded nonwoven fabric and loose fibers) is not relevant to the invention.

[0023] In the transport direction of the web of fibrous material 2, a carding unit 5 is arranged in the system 100. The carding unit 5 can be positioned spatially above the belt 3, so that the web of fibrous material 2 can be guided independently of the carding unit 5 to a water jet compaction process with at least one water beam. In other words, the belt 3 can be guided below the stationary carding unit 5 and is designed to guide the web of fibrous material 2 directly from the device for depositing the loose fibers – here the inclined screen former 1 – to the water jet compaction process. In this process, the web of fibrous material 2 is compacted. Alternatively, the carding unit can also be positioned upstream of the inclined screen former 1 in the material transport direction.

[0024] The fiber / nonwoven composition 6 is described below, whereby it is clear that the system is variable and can also consolidate and process only a single-layer nonwoven, for example, the fiber material 2 or only the unconsolidated carded nonwoven 5a. The fiber / nonwoven composition 6 is transferred from the circulating belt 3 to a transport table 7 with a circulating belt 7a, which has a horizontal section in the material flow direction. The circulating belt 7a is designed as a liquid-permeable screen belt and can consist of a plastic or metal mesh. Alternatively, it can also consist of a perforated plastic. The degree of openness of the circulating belt 7a is determined, among other things, by the amount of liquid in the first water bar 8.1.

[0025] A first drum 8 is assigned to the transport table 7 with the circulating belt 7a. This drum receives the fiber / nonwoven composition 6 with the top side facing up, i.e., with the unbonded carded nonwoven 5a. A first water bar 8.1 is arranged within the transport table 7. This water bar bonds the fiber / nonwoven composition 6 from below and simultaneously transfers it from the circulating belt 7a onto the drum 8. The distance B between the belt 7a and the drum 8 is adjustable and, if compaction of the incoming nonwoven or fiber / nonwoven composition 6 is desired, can correspond to a maximum of the thickness of the fiber / nonwoven composition 6. This allows the water pressure from the water bar 8.1 to simultaneously compact the fiber / nonwoven composition 6. After the transfer of the fiber / nonwoven composition 6 onto the first drum 8, further consolidation takes place by two further water bars 8.2, 8.3 also on the underside of the fiber / nonwoven composition 6.The fiber / nonwoven composition 6 is then transferred, underside down, onto a second rotating drum 10, where the top side of the fiber / nonwoven composition 6 is consolidated with further water bars 10.1, 10.2. This creates a consolidated nonwoven 12, which is transferred via a deflection roller 11 to a suction device 13 for further processing.

[0026] Figure 2Figure 1 shows an enlarged view of the first drum 8 with the transport table 7. The first drum 8 has a rotatable outer shell 8a and a fixed inner suction area 8b, to which a plurality of suction openings 8c are assigned, only one of which is shown. The outer shell 8a has liquid-permeable perforations. Additionally, the outer shell 8a can also be designed to structure the nonwoven fabric. For this purpose, the surface of the outer shell 8a can have corresponding structural patterns. Independently of the rotatable outer shell 8a, the suction area 8b with its suction openings 8c can be freely positioned around its circumference and then fixed in place. The suction openings 8c extend over the entire working width and correspond in length and position to the associated water bars 8.1, 8.2, 8.3.The extraction area 8b is subjected to negative pressure by, for example, a fan (not shown), so that the extracted water is directed to a separator. According to the prior art, the water bars 8.1, 8.2, 8.3 are always aligned with the axis of the drum. The invention provides to first rotate the water bar 8.1, which is arranged in the transport table 7 and acts on the fiber / nonwoven composition 6 via the belt 7a, by an angle α of 1° to 6°, preferably 3°, to the vertical opposite to the material flow direction (dashed line drawing of 8.1). This also causes the nozzle openings of the water bar 8.1 to rotate with the direction of action of the water jets against the material flow direction of the nonwoven.

[0027] To ensure that the water jet from the nozzle bar 8.1 strikes the suction opening 8c of the drum 8 perpendicularly, the water bar is shifted by the dimension X in the material flow direction. Simultaneously, the suction area 8b is rotated by the angle β in the material flow direction so that the water jet is aligned with the geometric center of the drum 8. Since the angle β can differ in magnitude from the angle α, the suction area 8b can alternatively be rotated until a dimension A is set. This allows the water jet from the water bar 8.1 to be efficiently discharged without rebound. For this purpose, the suction area 8b of the drum 8 is aligned and positioned so that the water jets of each water bar 8.1 correspond to the respective suction openings 8c. The alignment and positioning of the drum 8 and the suction opening 8b are determined by the following factors:The adjustment of the suction area 8b is carried out by rotating the suction area 8b so that the suction openings 8c are centered opposite the incident water jets. Due to the different axes of rotation of the drum 8 and the water bar 8.1 during alignment, the angle of rotation β of the suction area 8.2 does not automatically correspond to the angle of rotation α of the water bar 8.1. Therefore, the adjustment of the suction area 8.2 with the suction opening 8.3 must correspond to dimension A, which extends from the central axis of the drum 8 to the geometric center of the outer suction opening 8.3. This dimension A corresponds to the displacement of the water bar 8.1 by dimension X plus the horizontal displacement due to the rotation of the water bar 8.1 by the angle α. Both settings A and X depend, among other things, on the thickness of the nonwoven fabric or, in this case, the fiber / nonwoven composition 6, and the distance of the water bar 8.1 from the belt 7a.

[0028] The water bar 8.1 can be operated at a pressure of 20 bar to 200 bar, preferably at 20 bar to 40 bar, in order to achieve initial consolidation and separation of the nonwoven fabric or the fiber / nonwoven composition 6 from the web 7a without damaging the fiber web. The subsequent water bars 8.2, 8.3 can be operated at a higher pressure of 40 bar to 250 bar.

[0029] The advantage of the invention, achieved by rotating the water beam 8.1 by an angle α of 1° to 6°, preferably 3°, to the vertical opposite to the material flow direction, lies in a higher and more aligned consolidation of the nonwoven fabric or fiber / nonwoven composition 6, since the MD / CD ratio improves in the material flow direction. This results in compression of the nonwoven fabric or fiber / nonwoven composition 6 against the drum 8, thereby improving the fiber alignment. Simultaneously, the release of the nonwoven fabric or fiber / nonwoven composition 6 from the circulating belt 7a is facilitated, as the elastic behavior of the nonwoven fabric or fiber / nonwoven composition 6 is utilized, which is locally compressed by the water jets and then at least partially relaxes again.This property is sufficient for the removal of the nonwoven fabric without the need to adjust the distances between the transport elements to a value greater than the thickness of the nonwoven fabric.

[0030] Additionally, reducing the distance B between the circulating belt 7a and the first drum 8 compacts the nonwoven fabric or fiber / nonwoven composition 6, thereby increasing the efficiency of the bonding effect provided by the water jets of the first water bar 8.1. This simultaneously improves the transfer of the nonwoven fabric or fiber / nonwoven composition 6 from the first transport element to the second transport element. The distance B between the transport table 7 and the circulating belt 7a of the first drum can be variably adjusted. Preferably, the distance B corresponds to the thickness of the nonwoven fabric at most. For nonwoven fabrics or fiber / nonwoven compositions 6 with short fibers, this additional compaction is advantageous, as the nonwoven fabric gains higher strength before being bonded by the water jet of the first water bar 8.1 and transferred to the first drum 8.Compaction at least partially freezes the structure of the nonwoven fabric and reduces the leaching of short fibers. For nonwovens or fiber / nonwoven compositions 6 with longer fibers of 40 mm or more, compaction can be omitted. The distance between drum 8 and the circulating belt 7a then corresponds to the thickness of the nonwoven fabric.

[0031] In Figure 3A web of material, either a single-layer carded nonwoven 5a or a fiber / nonwoven composition 6, runs over the circulating belt 7a into the gap between the drum 8 and the circulating belt 7a. The thickness of the incoming nonwoven is 2 mm before the drum 8. The distance B between the drum 8 and the circulating belt 7a is set to 1.5 mm, so that the carded nonwoven 5a or the fiber / nonwoven composition 6 is compacted in the area of ​​the central axis M of the drum 8. The outer diameter of the drum 8 is approximately 500 mm. Behind the central axis M of the drum 8, the carded nonwoven 5a or the fiber / nonwoven composition 6 expands again to a thickness of 1.7 mm due to its elastic properties. With the water bar 8 aligned...1. At a 3° angle to the material transport direction and a displacement of the water beam by a dimension X of 30 mm from the central axis M of the drum 8 in the material transport direction, the water jet strikes the carding nonwoven 5a or the fiber / nonwoven composition 6 at a point where it is still in contact with both the circulating belt 7a and the drum 8. The water jet detaches the carding nonwoven 5a or the fiber / nonwoven composition 6 from the circulating belt 7a and transfers it to the drum 8, whose suction at the suction opening 8c assists the transfer.

[0032] Example 1: The fiber material 2 of the inclined screen former consists of short synthetic polyester fibers with a fiber length of 8 to 12 mm. This was mixed with pulp with a fiber length of 3 to 8 mm. Fiber material 2 has a layer thickness of 1.5 mm.

[0033] The carding fleece 5a consists of a blend of polyester and viscose and has a fiber length of 40 to 60 mm. The carding fleece has a thickness of 1 mm.

[0034] The fiber / nonwoven composition 6, with a total thickness of 2.5 mm, is transferred to the conveyor belt 7a. The distance B between the conveyor belt 7a and the drum 8 is 2 mm, resulting in initial compaction between the drum 8 and the conveyor belt 7a. The outer diameter of the drum 8 is 515 mm. The first water bar 8.1 was pivoted by an angle α = 3° against the material flow direction. The suction area 8b of the drum 8 was rotated in the material flow direction, shifting the geometric center of the outer suction opening 8.3 by 32 mm in the material flow direction. The water bar 8.1 is 22 mm from the suction opening and was shifted by a distance X = 33.2 mm in the material flow direction.

[0035] The water bar 8.1 exerts a pressure of 40 bar through the circulating belt 7a onto the fiber / nonwoven composition 6. This compacts the composition, which is then transferred from the conveyor belt 7a to the drum. The nonwoven fabric, or fiber / nonwoven composition 6, then has a thickness of 2.2 mm, and the MD / CD ratio has been improved to 5:1.

[0036] Example 2: The nonwoven fabric to be processed consists solely of a carded nonwoven 5a with a polyester-viscose blend and has a fiber length of 40 to 60 mm. The carded nonwoven fabric has a thickness of 3 mm.

[0037] The nonwoven fabric, with a total thickness of 3 mm, is transferred onto conveyor belt 7a. The distance B between conveyor belt 7a and drum 8 is 2 mm, resulting in compaction between the drum 8 and conveyor belt 7a. The outer diameter of drum 8 is 515 mm. The first water beam 8.1 was pivoted by an angle α = 5° against the material flow direction. The suction area 8b of drum 8 was rotated in the material flow direction, shifting the geometric center of the outer suction opening 8.3 by 40 mm in the material flow direction. The water beam 8.1 is 22 mm away from the suction opening and was shifted by X = 41.9 mm in the material flow direction.

[0038] The water bar 8.1 exerts a pressure of 40 bar on the nonwoven fabric 6 via the circulating belt 7a. This compacts the fabric, which is then transferred from the conveyor belt 7a to the drum. The nonwoven fabric then has a thickness of 2.7 mm, and the MD / CD ratio has been improved to 5:1. Reference sign

[0039] 100 plant 1 Inclined screen former 2 Fiber material 3 Belt 5 Carding 5a Carding fleece 6 Fiber / fleece composition 7 Transport table 7a Belt 8 First drum 8a Outer shell 8b Suction area 8c Suction opening 8.1 - 8.3 Water bar 9 Guide roller 10 Second drum 10.1 - 10.2 Water bar 11 Deflection roller 12 Consolidated fleece 13 Suction device A Distance B Distance M Center axis first drum X Displacement in material transport direction α Angle of rotation water beam β Angle of rotation suction opening

Claims

1. Device for consolidating and transferring a nonwoven fabric from a first circulating belt (7a) to a second transport element arranged above it, with at least one water bar (8.1), wherein the first circulating belt (7a) is designed as a liquid-permeable transport belt, the second transport element is a liquid-permeable drum (8) and has at least one suction opening (8c) for suctioning liquids, and the at least one water bar (8.1) is arranged below the circulating belt (7a) and is designed to consolidate the nonwoven fabric and detach it from the circulating belt (7a) by means of water jets at high pressure through the circulating belt (7a). characterized by the fact that the water bar (8.1) is rotated with the direction of action of the water jets opposite to the material transport direction by an angle (α) of 1 - 6°, preferably by 3°, and is arranged displaced in the material transport direction.

2. Device according to claim 1, characterized by the fact thatThe displacement of the water beam (8.1) in the material transport direction corresponds to the position of the at least one suction opening (8c) of the transport element arranged above.

3. Device according to claim 1, characterized by the fact that the second transport element is designed as a drum (8) with a rotating liquid-permeable outer shell (8a), and with a suction area (8b) with at least one suction opening (8c).

4. Device according to one of claims 1 to 3, characterized by the fact that the extraction area (8b) with the at least one extraction opening (8c) inside the drum (8) is positioned such that the at least one extraction opening (8c) corresponds to the direction of action of the water jets of the nozzle bar (8.1).

5. Device according to claim 1, characterized by the fact that the distance (B) between the drum (8) and the circulating belt (7a) is adjustable and corresponds at most to the thickness of the fleece.

6. Device according to claim 1, characterized by the fact thatthe water jet of the water bar 8.1 hits the fleece at a point where it is in contact with both the surrounding belt (7a) and the drum (8).

7. Method for consolidating and detaching a nonwoven fabric from a first circumferential belt (7a) onto a second transport element arranged above it by means of water jets which act through the first circumferential belt (7a) on the underside of the nonwoven fabric and are extracted through a suction opening (8c) which is associated with the second transport element, characterized by the fact that the water jets strike and solidify the nonwoven fabric at an angle (α) of 1 - 6°, preferably 3°, against the material flow direction of the nonwoven fabric, and that a transfer of the nonwoven fabric from the first circulating belt (7a) to the second transport element is effected by a displacement of the point of impact of the water jets on the nonwoven fabric in the material transport direction.

8. Method according to claim 7, characterized by the fact thatThe extraction of the water jets from the transport element located above corresponds to the rotation of the water jets against the material transport direction and the displacement of the water jets in the material transport direction.

9. Method according to claim 7, characterized by the fact that the fleece is compacted between the circumferential belt (7a) and the second transport element.

10. Method according to claims 7 to 9, characterized by the fact that the nonwoven is designed as a single- or multi-layered nonwoven, which may comprise a carded nonwoven (5a), a fiber material (2) and / or a fiber / nonwoven composition.

11. Method according to claims 7 to 9, characterized by the fact that the fleece is detached from the circulating belt (7a) at a point where it touches the circulating belt (7a) and the drum (8).

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