EP1644565A1

EP1644565A1 - Method and device for reinforcing a web of non-woven fabric by means of needling

Info

Publication number: EP1644565A1
Application number: EP04764967A
Authority: EP
Inventors: Johann Philipp Dilo
Original assignee: Oskar Dilo Maschinenfabrik KG
Current assignee: Oskar Dilo Maschinenfabrik KG
Priority date: 2003-10-02
Filing date: 2004-09-08
Publication date: 2006-04-12
Anticipated expiration: 2024-09-08
Also published as: WO2005033396A1; WO2005033396B1; CN100510224C; DE10346472A1; US7117571B2; DE502004001174D1; ATE335875T1; US20060174462A1; CN1863958A; EP1644565B1

Abstract

A system and method for reinforcing a textile web of a fiber web or a fiber fleece by needling in a plurality of directly successive steps are provided, in which the web is needed from both sides with a high needle density in an alternating manner and in the state of the needles stitched into the web is transported through a movement of the needles which extends in the longitudinal direction of the web, where each needle in a stitching-in movement grasps merely a single fiber, having a gauge of 1 to 2 dtex, from the web. By the aid of the invention very thin fleeces can be produced without damaging same during their processing.

Description

Method and device for consolidating a nonwoven web by needling

In order to achieve sufficient strength in very thin nonwovens, such as those used in the hygiene sector, a very close bond between the fibers forming the nonwoven is required. For the needling technique as one of the possibilities for the production of nonwovens from fiber pile and for the consolidation of nonwovens, this means that the pile or the nonwoven must be needled with a very high density of the punctures.

Thin fibrous webs and non-woven fabrics of the aforementioned type are very sensitive before they solidify. Even with little mechanical stress, they easily lose their cohesion and tear. Their processing in needle machines is therefore very delicate, which is why a reduction in the weight per unit area of the needled products has so far been relatively high limits that did not meet the wishes of the users.

The sensitivity of the processed material also meant that the working speeds were very low and the nonwoven web had to be processed in a very large number of steps in order to obtain the number of needle punctures per unit area of the product required for consolidation, which was in one correspondingly expressed low productivity.

The invention is therefore based on the object of specifying a method and a device with which gentle processing of fibrous webs and non-woven fabrics is possible, which allows very thin and light-weight needled products to be produced.

To achieve this object, the invention provides a method for solidifying a textile material web made of a fiber web or nonwoven fabric by needling in a plurality of immediately successive steps, in which the material web is needled alternately from both sides with a high needle density and in the state of being pierced into the material web the needles are moved exclusively by a movement of the needles running in the longitudinal direction of the material web. Furthermore, the invention provides a device for strengthening a textile material web made of a fiber web or nonwoven fabric by needling in a plurality of successive steps, comprising a plurality of double layers arranged one behind the other in a transport direction of the material web Needle machines, each having an upper and a lower, arranged on both sides of a needling zone, with a mutual phase shift of 180 ° driven needle bars, on each of which a needle board provided with a needle or a needle board group is attached, each needle bar with one of its puncturing movement causing stitch drive and a movement parallel to the longitudinal direction of the material transport transport drive is connected and the needles are designed in such a way that the material web is fed through the needle machines exclusively by the horizontal component of movement of the needles.

By using a high needle density, the invention achieves high productivity even in the individual needling steps. When using needle boards of, for example, 350 to 400 mm width, it enables an assembly density of up to 40,000 needles per meter of needle board length. The pitch of the needles is then, for example, about 3 mm or less, which necessitates the use of special needles of small diameter. The production speed can reach 200 m / min with working widths of up to 6 m, just to name a few. It can be used to produce lightweight products with a weight per unit area of up to 10 g / m ² , for example from a single cardboard pile. The fibers can be very fine, down to about 1 dtex. Fiber fibrils of less than 1 dtex can also be processed. The puncture densities are, for example, approximately 2,500 per cm ² , but may also be higher if necessary. With a needle loading density of the aforementioned type and an effective horizontal stroke of the needles of 1 cm, the nonwoven web of six needle boards must be needled on both sides in order to achieve the stitch density mentioned.

The processing of even such light-weight products, as explained above, is made possible by the measures according to the invention, according to which the material web in the inserted state of the needles is moved within the needle machine exclusively by a movement of the needles running in the longitudinal direction of the material web. Because the needles of the two needle units, which are combined in a double needle machine, alternately pierce the nonwoven web in the invention, i.e. the working cycles of these needle units are offset by 180 °, an almost continuous transport of the nonwoven web takes place through the needle machine solely by the effect of needles. Furthermore, this operating mode enables the needle boards to be densely populated, since the needles of two opposite needle boards come from the start cannot collide with each other.

So there is essentially no tension acting on the material web from external transport devices, which would be braked by the needles when the needles are inserted into the material web, rather the needle units ensure the advance of the material web itself.

Depending on the type of material web being processed, the length of the material web may change due to the individual needling processes when the needle machines are in operation. In order to avoid upsetting or warping of the material web between the individual needle machines, the feeds with which the individual needle machines transport the material web must be suitably adapted to one another. With the same horizontal and vertical strokes of the needle bars per plunge movement in the individual needle machines, the feeds can be adjusted by changing the stitch frequencies of the individual needle machines. This solution is particularly useful when the horizontal stroke and vertical stroke of the needle bars are firmly coupled. However, it is also possible to make the penetration depths of the needles different with the same horizontal and vertical strokes of the individual needle machines, because this influences the time period during which the needles are inserted into the material web and transport it through the horizontal movement of the needle bar. which has a certain effect on the transport stroke in the horizontal direction per needle insertion. If needle machines of the type described in EP 0 892 102 B1 are used, the horizontal feed per needle insertion can be influenced within wide limits by appropriate control of the needle machines.

The co-movement of the needles with the material web when the needles are inserted into it is known per se from DE 196 15 697 A1. It has the aim of avoiding a disturbance of the surface of the material web, which could be caused by a warping if the transport speed of the nonwoven fabric through the needle machine is high. The speed of the horizontal drive component of the needle bar is adapted to the conveying speed at which the material web of feed and take-off devices is moved through the needle machine. The present invention uses the oscillating movement component of the needles running in the longitudinal direction of the material web to actively transport the material web without the need for other transport devices. With the help of the invention can even Consolidate single-layer but also multi-layer fibrous webs supplied directly from a card into a nonwoven. However, it is also possible to consolidate cross-laid nonwovens using the measures according to the invention. Even aerodynamically laid, possibly very thin card webs can be consolidated by needling with the aid of the invention.

The invention is not only suitable for processing extremely light material, but can also be used to process materials with a basis weight of up to 200 g / m ² . The fibers can be cotton fibers, for example, stack lengths of 20 mm to 40 mm are possible, and continuous fibers of spunbonded nonwovens, smooth fibers and textured fibers can form the material webs which can be processed with the aid of the invention.

When processing very light-weight material webs, needles are preferably used, the notches of which are so fine that they can grip only a single fiber, for example of a thickness of 1-2 dtex. Such a needle has, for example, a shaft diameter of 1.85 mm and reduces its diameter over its length to 0.5 mm in two steps. The notch depth of the needles is 0.02 mm, and preferably only one notch is formed on one edge of the needle. Because preferably only a single fiber is pressed into the fleece by the needle and the needle has an extremely small diameter, no puncture holes remain visible. Therefore, and because of the high puncture density, a marking-free surface of the needled product with high abrasion resistance is obtained.

However, it is also possible to dimension the notches of the needles, taking into account the fiber thickness, in such a way that predominantly two or three fibers are taken up by one needle notch.

The distance of the notches from the needle tip should preferably be small in order to be able to work with a small needle stroke. A preferred distance between the notch and the needle tip is, for example, 2 mm. A small needle stroke allows higher working speeds. Fork needles, crown needles or wreath needles can also be used, for example with fork widths and depths of 2/100 mm. The needles can have a standard length of 2.5, 3 or 3.5 inches, but may also be shorter, which benefits their stability and weight reduction. A weight reduction advantageously also contributes if the needles consist of plastic. One as small as possible The diameter of the needle shaft improves the strength of the needle board because more board material then remains with the same density of needles.

Since the needle boards are very heavy due to the high density of needles, plastic needles are also suitable, the weight of which is about 1/8 that of steel needles. In order to prevent the needle boards from fluttering on the needle bars carrying them, the needle boards can be attached to the needle bar in a pretensioned manner with little elastic deformation, as described in DE 102 38 063 A1. This technology also enables the use of very wide needle boards.

It is also advantageous when working with a laminated hold-down device, which consists of a slotted plate on which a plurality of mutually parallel slats are formed, which extend transversely to the longitudinal extent of the plate. In this way, a hold-down plate can be realized, which on the one hand has a small thickness in the slot area and is accordingly less susceptible to blockages due to fiber fly, but on the other hand has great stability with low weight. This hold-down device can also be used with the slats directed against the nonwoven web to be needled, but also vice versa, if necessary also as a stitch pad. Such a hold-down device accommodates the fact that, due to the small needle shaft diameter, the needles tend to bend more easily than thick needles. A laminated hold-down device makes it easier to thread the needle into the slots of the plate carrying the lamellae or makes threading unnecessary if the needles do not leave the slots in the plate during their entire lifting movement.

Instead of using a large number of needle machines in series, through which a nonwoven web is passed one after the other, one can also provide for the nonwoven to be passed through the same needle machine several times forwards and backwards and to be processed in several stages with this needle machine, whereby the individual passes between the individual runs Needle boards can be changed if needling is required differently in the different processing stages, for example with different needles and different needle populations.

With the help of the invention, smooth nonwovens can be produced on both sides, the puncture depths of the needles then being able to decrease from the processing step, ie needle assembly, to the processing step, ie the next needle assembly. The fibers needled by the needles through the material web and on the protrude the opposite side from the material web, pushed through the needling from the other side back into the material web, and with the help of the gradual reduction in the puncture density, it can finally be achieved that no more fibers protrude from the material web. The double needle technique, in which the material web is needled either simultaneously or alternately from both sides in a needling zone, doubles the penetration density in a small space.

On the other hand, it is also possible to produce hairy nonwovens with fibers protruding on one side. Such nonwovens are used, for example, for lamination to a base, the hair then favoring the anchoring of the nonwoven on the base.

It is also possible with the aid of the invention to produce light nonwovens with a structured surface, for example wiping cloths which have a perforated pattern pierced into them. Such wipes are popular in the household because of their dirt-holding capacity. All that is required is to insert a corresponding work step into the process sequence with suitable smooth needles with an enlarged shaft diameter and a low population density of the needle board. Due to the elastic resilience of the fibers, which could lead to the holes being closed, this process may need to be carried out in several stages with needles increasing in diameter from stage to stage, paying attention to the alignment of the holes of the semi-finished product with the needles of the subsequent processing stage must become. With the help of modern synchronizing devices, this can be achieved without difficulty. The use of a brush tape as a stitch pad that is guided through all processing stages is also advantageous in this case because the fleece adheres well to the brush tape and thus maintains its position on the pad. After the holes have been formed, thermal fixing can optionally take place by passing the perforated material through a sieve drum oven or through a flat-belt dryer in order to achieve a thermofusion of the fibers at their crossover points, provided that they are made of a suitable material, e.g. a thermoplastic.

Other structures are also conceivable. The needling on a grate, or more precisely on a slotted plate or a laminated plate as a stitch underlay, in particular using needles with several notches per edge or several edges with notches and with a higher notch depth, enables the fleece to be structured, which occurs on both sides when needling is carried out from both sides of the fleece. Tufts of fibers are pulled out or pushed out of the pre-consolidated fleece and transported to the fleece surface. If a multiple arrangement of needle machines is used, this structuring is carried out in the last needle machines or the last needle machines in the chain of machines, or in a separate operation within a single machine which is operated outside the machine chain for the purpose of patterning and structuring.

Depending on the feed of the material web or per stroke and needle arrangement in the needle board, known patterns can be produced, such as longitudinal stripes, transverse stripes, diagonals or stitch patterns.

It is essential that at least the horizontal drives, which are assigned to the different needling zones, are independent of one another, so that an adaptation to different transport speeds, which are caused by shortening and lengthening the material web, is possible. Unless a synchronous vertical drive of all needle bars is considered, which is preferable for the nonwoven web to be transported through the device as smoothly as possible, the transport speeds caused by the individual needle machines can be considered by changing the stroke frequencies of the individual ones To influence needle machines.

The invention is explained in more detail below with reference to a device for strengthening a fibrous web shown in the drawing.

1 and 2 together show a system for producing a needled nonwoven web. 1 shows an aerodynamic fleece former with feed, intake and take-off, a transfer device and the inlet area of a multi-stage needling plant, while FIG. 2 shows further needling machines of a needling plant. Instead of an aerodynamic fleece former, a roller card, a card or other pile or fleece producer can also be provided.

The system of FIGS. 1 and 2 comprises a fiber feeder 1, which is connected to an aerodynamic fleece former 3 via a feed 2. A transfer device 4, which has an endlessly circulating conveyor belt 5, leads from the fleece former 3 to the Running area of a needling machine 6 comprising a plurality of needle machines. The conveyor belt 5 is opposed in the inlet area of the needling machine 6 by an endlessly rotating pressure belt 7, which serves to compress a nonwoven web 8 released by the roller card 3 and which is located on the endlessly rotating conveyor belt 5.

A multiplicity of double-needle machines 9 are arranged within the needling system 6, of which the needle bars 10, which needle the nonwoven web 8 alternately from above and below, are each shown schematically by hatched triangles. The needle bars 10 each carry a needle board densely populated with needles or a needle board group densely populated with needles (not shown). Of the needling machines 9, only the drive motors 91 for the vertical stitch drive and horizontal drive units 11 are schematically shown, which are coupled to the needle bar 10 via connecting rods 12, so that the latter runs horizontally, parallel to the direction of extent of the nonwoven web 8 and to give moving components. The coupling between the connecting rods 12 and the needle bar 10 is not shown here for reasons of clarity. For details, reference can be made, for example, to the already mentioned DE 196 15 697 A1 and also to EP 0 892 102 B1, the latter also disclosing elegantly adjustable devices for continuously changing the stroke size of the horizontal movement of the needle bar. It should be noted in this connection that it is advantageous if the penetration depth of the needles can also be adjusted, because this determines the dwell time during which the needles are in the state of being pierced into the nonwoven fabric. For further explanations in this connection, reference is made to DE 196 15 697 A1.

The arrangement of the needle bars 10 and their drives 11 and 91 is the same for all needle machines 9. The vertical drives of the individual needle machines 9 can be controlled independently of one another and also independently of one another in order to be able to influence the stroke frequencies individually, with which the transport speeds of the nonwoven web on the individual needle machines can be changed. However, they can also be driven synchronously with one another, in particular by a common drive device, which helps to avoid stretching and compressing the nonwoven fabric web within the needling plant. At least then, however, the horizontal drives should be individually adjustable in their stroke size in order to be able to make local transport speed adjustments. On the outlet side of the needle machine system 6, a pair of take-off rollers 13 is arranged, which delivers the finished machined nonwoven web, now designated as the end product with 81, from the system.

In the needle machine system 6, two double needle machines 9 can be combined in a common machine frame to form a twin unit, which has common upper and lower stitch pads (not shown) for the material web to be processed. Possibly. all the upper needle bars, i.e. the upper needle bar group of the twin arrangement can be driven together, and the same applies to all lower needle bars.

Since the horizontal drives 11 take up a certain space for the needle bars 10, the gaps Z between adjacent twin units, where the horizontal drives are accommodated, are each bridged by endlessly circulating conveyor belts 14, which support the processed nonwoven web 8 from below, so that they are not under their own weight sags and may stretch in an undesirable manner. As an alternative, smooth support plates with low surface friction can also be considered, over which the nonwoven web can slide easily.

Since in the invention the material web 8 is needled from both sides and the invention therefore uses double-needle machines in which there are two needle aggregates needling against each other in a needling zone, the needles of which alternately pierce the nonwoven web, the stitch pads are on both sides of the nonwoven web 8 against which the latter 8 is pressed by the needle movement, in each case lamella grids with longitudinal slots or slotted plates, the slots of which enable the horizontal movement of the needles for the transport of the nonwoven web 8 in the state in which it is pierced. Details are not shown here, reference can be made to the publications already mentioned. The use of lamella grids is already known per se from the needling technique, in particular when forming pile loops on needle felts, which are to be used, for example, as a floor covering.

The needles can each be arranged in packages on the needle boards, packages viewed in the longitudinal direction being offset transversely to one another by less than one needle pitch in order to increase the puncture density on the nonwoven web. The slots in one Slit plate as a stitch pad must then also be mutually offset accordingly in the transverse direction. It is also possible to adjust the lateral guidance on the individual needle machines in coordination with one another so that the punctures produced by the needles of a subsequent needle machine in the nonwoven web are offset transversely with respect to the punctures produced by the needles of a preceding needle machine in the same nonwoven web become.

The horizontal strokes that the individual horizontal drives 11 have to perform must be adjustable depending on the material properties of the nonwoven web. As already mentioned, devices are disclosed in EP 0 892 102 B1 with which the horizontal stroke can be continuously adjusted, even when the machine is in operation. As already mentioned, an alternative is to change the stroke frequency. The stretching or shrinkage of the nonwoven web 8 that may occur as a result of the processing can be determined, for example, without contact using electronic cameras and auto-correlation of the images recorded by them, and the horizontal drives can be adjusted with the aid of these. The facilities required for this are not shown in the drawing for reasons of clarity. It is understood that such devices are provided on each needle machine where the nonwoven web can undergo changes, and a central control unit can be provided for the entire system.

Claims

Expectations

1.Process for solidifying a textile material web made of a fiber web or nonwoven fabric by needling in a plurality of immediately successive steps, in which the material web is alternately needled from both sides with a high needle density and in the state of the needles being pierced into the material web exclusively by one in the Longitudinal direction of the web of movement of the needles is advanced.

2. The method of claim 1, wherein the puncture depth of the needles decreases from step to step.

3. The method of claim 1, wherein at least in late steps of the method, the penetration depth of the needles on one side of the material web is smaller than the penetration depth of the needles on the other side of the material web.

4. The method according to any one of the preceding claims, wherein the material web consists of a single or multi-layer carded pile.

5. The method according to any one of the preceding claims, wherein the vertical puncturing movements of the needle bars are synchronized with each other.

6. The method according to any one of the preceding claims, characterized in that the horizontal speed components of the needles are of different sizes in the individual steps.

7. The method according to any one of claims 1 to 4, characterized in that the needle bars of the individual needle machines are driven with different stitch frequencies.

8. The method according to any one of the preceding claims, in which the material web between at least some of the needling steps by smooth contact surfaces or by moving with the material web, in contact with the material web. brought support surfaces is supported.

9. The method according to any one of the preceding claims, characterized in that only one fiber is gripped by a needle during the puncturing movement and is pressed into the material web.

10. The method according to any one of the preceding claims, characterized in that permanent holes are produced in the needled material web with the aid of needles and the material web is then subjected to a fixing process.

11. Device for solidifying a textile material web (8) made of a fiber web or nonwoven fabric by needling in a plurality of successive steps, comprising a plurality (6) one after the other in a transport direction of the material web (8) arranged double needle machines (9), each an upper and one have the lower needle bars (10), which are arranged on both sides of a needling zone and are driven with a mutual phase shift of 180 °, to each of which a needle board or a needle board group provided with needles is attached, each needle bar (10) having a needle drive which causes its puncturing movement (91) and a transport drive (11) causing a movement parallel to the longitudinal direction of the material web (8), the needling machines (9) being configured in such a way that the feed of the material web through the needle machines (9) is exclusively through the horizontal Bewegungsko component of the needles.

12. The apparatus of claim 11, wherein the drives (91, 11) of the different double-needle machines (9) are independent of each other and are independently adjustable and controllable.

13. The apparatus of claim 11 or 12, wherein the double needle machines (9) are driven with different stroke frequencies of their needle bars from machine to machine.

14. The apparatus of claim 11, wherein the drive means for generating the Grooving movement of the needle bar of all needle machines are connected to a common drive motor.

15. The device according to one of claims 11 to 14, in which at least between some of the needling machines (9) on the material web (8) adjacent, moving transport device (14) is arranged.

16. The device according to one of claims 11 to 15, in which a roller card (3) is arranged on the inlet side to the first double needle machine (9) of the plurality (6) and is connected to the needle machine (9) by a pile feed device (4).

17. The apparatus of claim 16, wherein the pile feed device (4) has an endlessly rotating pressure belt (7).

18. Device according to one of claims 11 to 17, characterized in that a distance detection device is arranged on each needle machine, which is connected to a control device for influencing the horizontal stroke length of the needle bar (10) of the relevant needle machine (9).

19. Device according to one of claims 11 to 18, wherein the needles consist of plastic.

20. Device according to one of claims 11 to 19, wherein the needles have a notch depth of 0.02 mm.

21. Device according to one of claims 11 to 20, in which the needles attached to a needle board are arranged in groups which, viewed in the transport direction of the nonwoven web, are offset transversely to one another by less than one needle pitch.