DE19527416A1 - Nonwoven produced by repeated cross-laying of carded webs - has web edges thinned by varying the laying width to improve final web uniformity - Google Patents

Abstract

A multi-layered nonwoven (11) is built up by laying a primary web (8) with thinned edges (12) which is fed to a final web producer (4). This produces a final web (9) with thinned longitudinal edges (12) which is supplied to the final web layer (5) to lay down the non-woven (11). Also claimed is the formation of a web with thinned edges by periodically reducing the laying width of the web layer (2) in different layers to form steps at the longitudinal edges (12).

Description

The invention relates to a method and a device to form a multi-layer fiber fleece with the Features in the preamble of the process and Device main claim.

From EP-A-0 520 869 it is known a multi-layer Manufacture fiber fleece with two fleece layers. Of a first fleece layer or a pre-fleece layer is a Vorvlies formed, which then a stretching device passes in which the nonwoven is stretched and one certain reorientation of the fiber and layer angle experiences. If necessary, the preliminary fleece is applied beforehand cut the folded side margins. Of the The pre-fleece reaches a second stretching device Fleece layer or end fleece layer, which the pre-fleece in several layers and at an angle one above the other with a layer closure to a final fleece. The end nonwoven layer has in generally a larger laying width than the previous fleece layer. The pile layers in the end fleece are as precise as possible End of position, the rear edge of the lower Pile just under the front edge of the top pile should come to rest. Compliance with the closing date can not always be in the desired accuracy guarantee. In addition, the fleece is created by the straight front and back edges of the pile layers one step, which are unfavorable in the further processing can impact.

From DE-C-12 87 980 is a similar arrangement known to two nonwoven layers, in which the preliminary nonwoven from the first Nonwoven layer directly and without stretching the second  Fleece layer is fed. Between the two layers of fleece an edge sharpening device is arranged, the The edges of the pre-fleece are slightly beveled, which results in the end fleece softer layer transitions occur at the end of the layer. In the It is also known practice to use the fibers on the edges of the Suck off the fleece in some areas in order to do the same sharpen the edges and more or less pointed or to run diagonally. Both techniques have that Disadvantage of mechanical action on the nonwoven and a fault in the fiber composite. This can be adversely affect the end product.

It is therefore an object of the present invention to better way of forming a qualitative to show high-quality end fleece.

The invention solves this problem with the features in Process and device main claim.

With the method according to the invention and the associated Device becomes a particularly homogeneous end product from outstanding quality. That from the nonwoven layer Formed pre-fleece is presented to a final pile producer, which produces a very even end pile from this. The quality of the final pile formation is due to that in the preliminary fleece existing pre-orientation and homogenization of the fibers better than with a normal card feed disoriented fibers.

A is used to form soft layer transitions in the end fleece Vorvlies formed with thinned longitudinal edges, this Marginal thinning remains in the final pile. The Marginal thinning of the pre-fleece is according to the invention already in the pre-fleece layer when depositing the pre-fleece educated. This technique offers more, better and more precise Possibilities of influence as a mechanical suction or Sharpen the edges. The edge thinning can be basically any length and bevel angle  to adjust. In particular, the invention does not work Fiber material lost. The fiber composite and the Fiber orientation remains in the deposited pile layers preserved and will not be destroyed. The final pile and that End fleece have a higher stability and Quality.

To optimize the final fleece quality, End fleece layer the thinned front and rear edges of the upper and lower end pile layer at the layer closing line with Overlap filed. This results in a special one soft layer transition while avoiding the previous one Step formation. Tolerance against position closure errors is much better due to the overlap. In the end the result is a fleece with a more uniform thickness and in consequently a higher quality end product.

The formation of the thinned longitudinal edges in the preliminary fleece layer can be done in different ways, for example by forming an edge on the edge, as is the case in the DE-A-37 38 190 or DE-A-40 10 174 is described. In the preferred embodiment of the invention Marginal thinning due to a periodic change in the Laying width of the fleece layer while the pile is being laid down generated. Here marginal steps are formed, which are in Pre-fleece as a bevel or thinning of the longitudinal edges impact. The change in the laying width can be seen in control in any way so that a large Variation in the shape of the generated Marginal thinning exists. This technique can also be used for use other purposes and is of secondary importance.

The change in laying width is preferably symmetrical, so that similar on both longitudinal edges of the fleece Stages are formed. The step formation can be vary by the number of steps and / or their width and the period formation are changed. To this  The use of a programmable is recommended for this purpose Control of the fleece layer in connection with any controllable or adjustable drives. this concerns especially the drives for the main car as well if necessary also the non-woven layer's auxiliary wagons. A such control is also for the final nonwoven layer Generation of edge overlaps advantageous.

For the quality of the end product, it is advantageous if Pre and final pile essentially the same Have basis weight. The basis weight of the The final pile is submitted to the nonwoven preferably as large as a normal one Card feed. The fleece is used accordingly many, preferably at least twenty doubles Pile layers deposited. The in the formation of the marginal steps in Pre-fleece are possible closing errors tolerable and are eliminated in the end pile generator. By the large thickness of the nonwoven they fall anyway not weight. You can also in the Fleece layer through suitable control measures and the Coordination of laying car and take-off belt speed be met.

In the subclaims are further advantageous Embodiments of the invention specified.

The invention is in the drawings for example and shown schematically. In detail show:

Fig. 1 is a schematic arrangement with two non-woven stackers and a Endflorerzeuger,

Fig. 2 is an end view of a cross-lapper according to arrow II of FIG. 1,

Fig. 3 is an enlarged and fragmentary top plan view of the preliminary fleece,

Fig. 4 broken end views of the longitudinal edges of the nonwoven with step formation in two variants and

Fig. 5 shows a broken longitudinal section through the Endvlies in the region of the layer circuit.

Fig. 1 shows a schematic representation of an arrangement for forming a multi-layer fiber fleece. It consists of a first pile generator ( 1 ), which in a suitable manner forms a pre-web ( 6 ) from individual fibers, which is fed to a first nonwoven layer ( 2 ), which is referred to below as the pre-layer layer. The pile generator ( 1 ) is in any suitable manner, for. B. formed as a card or card.

The Vorvliesleger ( 2 ) can also be designed in any suitable manner, for. B. as a so-called carriage layer, nonwoven tape layer, fleece backing or the like. It has the task of folding the supplied sheet ( 6 ) transversely and placing it in several layers one above the other on a take-off belt ( 3 ). The pile layers ( 7 ) are placed at an angle to one another in a kind of scale formation. The deposited pile layers ( 7 , 7 ', 7 '') form the so-called preliminary fleece ( 8 ).

The preliminary fleece ( 8 ) is then fed to a final pile generator ( 4 ), which can be used in any suitable manner, e.g. B. can be constructed in the manner of a card. The end pile producer turns the pre-fleece ( 8 ) into an end pile ( 9 ) of particularly great homogeneity in structure and weight.

The end pile ( 9 ) is presented to a second non-woven layer, the so-called final non-layer layer ( 5 ), which deposits it into a final non-woven layer ( 11 ) on its take-off belt ( 3 ). The end fleece layer ( 5 ) can also be of any suitable type and constructive design.

The running direction of the pile or fleece is symbolized in Fig. 1 by arrows. The arrow in the end pile generator also shows the processing direction of the preliminary nonwoven ( 8 ), which is pulled apart, thinned and homogenized in the running direction and dissolution and standardization of the fiber orientation.

One or more suitable measuring devices ( 17 ) for the various material and processing parameters, with which e.g. B. the basis weight of the pile ( 6 , 9 ) or fleeces ( 8 , 11 ) or the like is measured. Fig. 1 shows schematically such a measuring device ( 17 ) on the final pile generator.

The pre-fleece layer ( 2 ) forms a pre-fleece ( 8 ) which has thinned longitudinal edges ( 12 ) on at least one side, preferably on both sides. The edge thinning can be formed in various ways, e.g. B. by warping the pile at the edge areas.

In the preferred exemplary embodiment, the edge thinning results from a change in the laying width of the preliminary fleece layer ( 2 ). A delay, e.g. B. with the technology described in DE-A-37 38 190 and DE-A-40 10 174 may optionally be added.

Fig. 2 illustrates in front view the basic design of a nonwoven layer. FIGS. 3 and 4 show the details of the preliminary fleece (8) and the edge dilution as described below.

The laying width of the pre-fleece layer ( 2 ) is determined in the embodiment shown by the travel distance of the lower main carriage ( 21 ), which is also referred to as the laying carriage. The laying carriage ( 21 ) travels back and forth over the take-off belt ( 3 ) and places the ruffled sheet ( 6 ) supplied by the card ( 1 ) in folds one above the other on the laying belt ( 3 ). Depending on the choice of speed or feed rate, two, four or 2 ⁿ individual pile layers are created one above the other between the laying carriage ( 21 ) and the take-off belt ( 3 ). Two layers of pile belonging together form a so-called double layer. This layer formation and the basic functions of such fleece layers are known per se. In the drawings and the description below, reference is made to double pile layers ( 7 , 7 ', 7 '').

With conventional fleece layers, the laying width is kept constant. In the embodiment of the pre-fleece layer ( 2 ) according to the invention, however, the laying width is deliberately changed. This happens periodically. Fig. 4 shows different possibilities.

The laying width is preferably changed in a symmetrical manner, the change taking place at both longitudinal edges ( 12 ). The period preferably relates to the width of the rafters ( 6 ) and the relevant end of layer.

As shown in FIG. 4 in the left image using a simplified example of a four-layer pre-fleece ( 8 ) for reasons of clarity, z. B. the first and lower pile layer ( 7 ') with a shortened laying width on the take-off belt ( 3 ). In the next run of the laying carriage ( 21 ) in the same laying direction, the following pile layer ( 7 ) is deposited with a larger laying width, whereby the pile edge protrudes a bit above that of the lower pile layer ( 7 '). In the next rectified laying stroke, the subsequent pile layer ( 7 ') is shortened again and then the fourth pile layer ( 7 ) is deposited again with a larger laying width.

Fig. 4 shows another variant in the right half. Here the first pile layer ( 7 ) with the normal laying width is placed on the take-off belt ( 3 ). The next pile layer ( 7 ′ ′) jumps back particularly far. The upward pile layer ( 7 ′) jumps back a little less, while the top pile layer ( 7 ) again has the full laying width.

The following pile layers (not shown) are in then both versions again in the manner described filed.

In addition to the two embodiments shown, there are further variants not shown. For example, starting from the right representation in Fig. 4, the middle pile layers ( 7 ') and ( 7 '') both protrude the same distance and the upper and lower pile layers ( 7 ) on the other hand spring back. In addition, there are any other design forms.

Both embodiments of FIG. 4 clarify the layer formation over the width of the slab ( 6 ). As already mentioned, these are double layers which are laid with a return trip during a double stroke of the laying carriage ( 1 ). The top pile layer or double layer is the one that still lies above the rear end area of the bottom pile layer. The next following pile layer, which is no longer shown, is no longer on the lowest pile layer shown in FIG. 4, but rather connects with its front edge to its rear edge in the so-called layer closure. The period then starts again.

Fig. 3 illustrates in plan view the paneling or shed storage of the pile layers ( 7 , 7 ') and corresponds essentially to the embodiment shown in the left half of Fig. 4 with alternating projecting and recessed pile layer edges.

As is clear from FIGS. 3 and 4, changes in the laying width result in edge steps ( 16 ) on the longitudinal edges ( 12 ) of the preliminary fleece ( 8 ). The soft and deformable pile layers ( 7 , 7 ', 7 '') do not remain in the manner shown schematically in Fig. 4, but sit down. The wider pile layers fold over the narrower ones, this deformation resulting in the aforementioned thinning of the longitudinal edges ( 12 ). The edge thinners have an essentially conical or beveled shape. They are idealized in FIG. 5 described below as so-called edge thinning ( 18 ).

The angle of inclination and the width of the edge thinning can be varied in a targeted manner. On the one hand, they depend on how wide the steps ( 16 ) formed by the change in laying width between the pile layers ( 7 , 7 ', 7 '') are. They also depend on the type of step formation and the number of protruding and recessed pile layers.

The pre-fleece layer ( 2 ) has a suitable machine control ( 24 ) for changing the laying width, which is preferably computerized and freely programmable. At least the two main carriages ( 20 , 21 ), which are also referred to as superstructures ( 20 ) and laying carriages ( 21 ), have controllable drives ( 23 ) with servomotors or the like. If auxiliary wagons are available for decoupling the main wagons and forming a storage unit and are provided with drives, these can also be controlled. Furthermore, the drives ( 23 ) of the laying belts ( 22 ) and the take-off belt ( 3 ) can be controllable and can be influenced and changed by the machine control ( 24 ).

The pre-fleece ( 8 ) presented to the end pile producer ( 4 ) has a weight per unit area which corresponds to that of a normal card feed. For this, the preliminary fleece ( 8 ) is deposited with a corresponding number of double layers. This usually means at least twenty double layers. In preferred embodiments, it is e.g. B. twenty to sixty double layers. The possible variations in the formation of the marginal steps are correspondingly diverse ( 16 ).

The final pile ( 9 ) preferably has the same basis weight as the preliminary pile ( 6 ). The number of double layers in the nonwoven ( 8 ) then essentially corresponds to the degree of dilution of the final pile generator ( 4 ).

Of the Vorvliesleger (2) downstream Endflorerzeuger (4) entrains the preliminary fleece (8) longitudinally apart, and orients the fibers to form a loose Endflors (9) new. The layer structure and any layer closing errors are resolved without eliminating the thinning on the longitudinal edges ( 12 ). These remain in the final pile ( 9 ).

The supply of a preliminary fleece ( 8 ) has the advantage over a normal card feed that a more uniform preliminary product is supplied. The preliminary fleece already has a relatively uniform fiber structure, which is oriented essentially transversely or obliquely to the direction of travel, so that the fangs of the carding devices each capture largely the same amount of fibers. With a normal card feed, there are completely disordered, tangled fiber distributions, which can lead to inconsistent fiber quantities and to inhomogeneities in the fiber distribution and in the weight per unit area of the initial pile. In contrast, the pre-fleece ( 8 ) produces an end pile ( 9 ) with a very uniform density, structure, distribution and orientation of the fibers.

The end fleece layer ( 5 ) deposits the end pile ( 9 ) fed by the end pile producer ( 4 ) into an end fleece ( 11 ) with an overlap ( 19 ) on the layer closing line ( 15 ). The overlap ( 19 ) consists in each case between the rear edge ( 14 ) of the lower pile layer ( 10 ') and the front edge ( 13 ) of the upper pile layer ( 10 ). The number of layers in the end fleece ( 11 ) depends on the desired end product. In Fig. 5 only a few layers are shown for clarity.

A real visible location closure line (15) does not exist by the overlap (19) in the inventive Endvlies (11). Rather, it is a theoretical line, as it would appear with a conventional position closure.

Conventional nonwovens lay the pile with the end of the layer, ie the rear edge of the lower pile layer and the front edge of the upper pile layer lie exactly one above the other at the layer closure line ( 15 ) in the end fleece. With conventional fleece layers, these pile edges are essentially straight and steeply sloping. The conventional laying method is illustrated in Fig. 5 by dashed lines on the pile edges ( 13 , 14 ).

The invention, on the other hand, envisages widening the area closing area and placing the pile edges ( 13 , 14 ) with overlap ( 19 ) on the theoretical layer closing line ( 15 ). This overlap is preferably center-symmetrical with respect to the position closure line ( 15 ). The edge overlap ( 19 ) has a width of approximately 20 to 100 mm, for example.

The pile edges ( 13 , 14 ) are formed by the longitudinal edges of the pre-fleece ( 8 ) or end pile ( 9 ). The edge thinning described above then has an effect in the end fleece ( 11 ) as edge thinning ( 18 ). It is idealized in FIG. 5 as a conical, protruding edge tip. In practice, the edge thinnings ( 18 ) rest on the adjacent pile layers. The overlap ( 19 ) of the oppositely directed edge thinners ( 18 ) results in a softer thickness transition of the pile layers in the end fleece ( 11 ) in the end-of-layer area. The intervening pile layers also do not have to deform as much as was necessary in the former step formation at the layer closing line ( 15 ). The overlap ( 19 ) compensates or tolerates laying errors. The pile edges ( 13 , 14 ) can slip somewhat against each other in the area of the edge overlap ( 19 ) without this noticeably influencing the quality of the nonwoven.

The arrangement shown is suitable for nonwovens ( 8 , 11 ) made of any fibers. These can be textile fibers. A preferred area of application is the production of paper felts.

Variations of the embodiment shown are in FIG possible in different ways. For one, more than two fleece layers are used, each with another End pile producers can be interposed, but not have to. This can be done in any or just a few of the non-woven fabrics edge thinning is formed. Also Stretching devices can alternatively or additionally in the system can be integrated.

In a modification of the special fleece laying technique shown with the formation of the marginal thinning through Laying width variation can also be any other Techniques for forming marginal thinning in one Fleece layers are used. The technology shown Laying width changes can also be for others Purposes are used, e.g. B. to avoid otherwise usual edge thickening of a fleece layer. They arise with conventional fleece layers through the constant continuous pile, which at the edge areas of the Laying width due to the braking and Accelerating processes of the laying vehicle are increasingly discarded becomes.

Otherwise, the characteristics of the different Described or indicated embodiments arbitrarily interchanged and combined to form the Modify embodiments.

Reference list

1 pile generator, card
2 fleece layers, pre-fleece layers
3 trigger tape
4 end pile producers, clutter
5 fleece layers, end fleece layers
6 low pile
7 pile position
7 ′ pile position
7 ′ ′ pile position
8 fleece
9 final pile
10 final pile
10 ′ end pile
11 end fleece
12 longitudinal edge
13 pile edge, front edge
14 pile edge, trailing edge
15 layer closing line
16 edge step
17 measuring device
18 edge thinning
19 edge overlap
20 main cars, superstructure
21 main carriage, laying carriage
22 bands
23 drive
24 machine control

Claims (14)

1. A method for forming a multi-layer fiber nonwoven with two or more nonwoven layers, wherein a nonwoven layer ( 8 ) with thinned longitudinal edges ( 12 ) is formed in a pre-nonwoven layer ( 2 ), which is fed to a downstream end pile generator ( 4 ), which from the Pre-fleece ( 8 ) produces an end web ( 9 ) with thinned longitudinal edges ( 12 ), which is then fed to an end batt layer ( 5 ), which deposits the end web ( 9 ) into an end web ( 11 ). 2. A method for forming a multi-layer fiber fleece with thinned longitudinal edges in a fleece layer, in particular according to claim 1, characterized in that the laying width of the fleece layer ( 2 ) is changed periodically while the pile ( 6 ) is being deposited, the pile layers ( 7 , 7 ', 7 '') are deposited on the longitudinal edges ( 12 ) to form steps ( 16 ). 3. The method according to claim 1 or 2, characterized in that the end pile ( 9 ) in the end fleece layer ( 5 ) with overlap ( 19 ) of the front and rear edge ( 13 , 14 ) of the upper and lower end pile layer ( 10 , 10 ') the layer closing line ( 15 ) is filed. 4. The method according to claim 3, characterized in that the edge overlap ( 19 ) has a width of about 20 to 100 mm. 5. The method according to any one of claims 1 to 4, characterized in that the nonwoven layer ( 2 ) forms a nonwoven ( 8 ) with a basis weight that corresponds to the basis weight of a card feed. 6. The method according to any one of claims 1 to 4, characterized in that the Vorvliesleger ( 2 ) a Vorvlies ( 8 ) with twenty or more double pile layers ( 7 , 7 ', 7 '') is formed. 7. The method according to any one of claims 1 to 6, characterized in that the end pile ( 9 ) corresponds in terms of basis weight substantially to the preliminary pile ( 6 ). 8. The method according to any one of claims 1 to 7, characterized in that the step formation ( 16 ) is carried out on both longitudinal edges ( 12 ). 9. The method according to any one of claims 1 to 8, characterized in that the step formation ( 16 ) on both longitudinal edges ( 12 ) is the same size and the same direction. 10. The method according to any one of claims 1 to 9, characterized in that periodically two or more stages ( 16 ) are formed. 11. Apparatus for forming a multi-layer fiber fleece with at least one pre-nonwoven layer ( 2 ), which is followed by an end pile generator ( 4 ) and an end non-woven layer ( 5 ), the pre-fleece layer ( 2 ) being designed and controlled in such a way that it forms a pre-fleece ( 8 ) with thinned longitudinal edges ( 12 ), from which the end pile generator ( 4 ) produces an end pile ( 9 ) with thinned longitudinal edges ( 12 ), which is deposited by the end fleece layer ( 5 ) into an end fleece ( 11 ). 12. fleece layer to form a multi-layer fiber fleece with thinned longitudinal edges, with a driven, controllable device for pile laying and a machine control, in particular according to claim 11, characterized in that the fleece layer ( 2 ) has a machine control ( 24 ) for periodically changing the laying width has during storage of the pre-pile ( 6 ), the pile layers ( 7 , 7 ', 7 '') being deposited on the longitudinal edges ( 12 ) with the formation of steps ( 16 ). 13. The apparatus of claim 11 or 12, characterized in that the end fleece layer ( 5 ) the end pile ( 9 ) with overlap ( 19 ) of the front and rear edge ( 13 , 14 ) of the upper and lower end pile layer ( 10 , 10 ') the layer closing line ( 15 ). 14. fleece layer according to claim 11, 12 or 13, characterized in that the machine control ( 24 ) of the fleece layer ( 2 , 5 ) is programmable.