EP2327822A1 - Method and device for creating a UD layer - Google Patents

Abstract

The method for producing uni-directional layer (2) with a predetermined layer width from a predetermined number of filament strands (5), comprises spreading the filament strands transverse to longitudinal direction of the uni-directional layer to tape and then arranging to each other. The tape spreads on a width, which is greater than a division width that arises itself from the layer width divided through the number of the filament strands. The tapes fold together after spreading transverse to the longitudinal direction on a tape width, which corresponds to the division width. The method for producing uni-directional layer (2) with a predetermined layer width from a predetermined number of filament strands (5), comprises spreading the filament strands transverse to longitudinal direction of the uni-directional layer to tape and then arranging to each other. The tape spreads on a width, which is greater than a division width that arises itself from the layer width divided through the number of the filament strands. The tapes fold together after spreading transverse to the longitudinal direction on a tape width, which corresponds to the division width. The tape width is smaller than the division width. The tape is arranged transverse to longitudinal direction. The tape spreads and pushes together on tape width, which is greater than the division width. The filament strand spreads in two different plains. An independent claim is included for a device for producing uni-directional layer.

Description

The invention relates to a method for producing a UD layer with a predetermined layer width from a predetermined number of filament strands, wherein the filament strands transverse to the longitudinal direction of the UD layer spreads to ribbon and juxtaposed.

Furthermore, the invention relates to a device for producing a UD layer having a predetermined layer width with a filament strand dispenser assembly from which a predetermined number of filament strands is simultaneously removable, a spreading device for each filament strand for spreading the filament strand transversely to its longitudinal direction into a ribbon and a winding device for the common winding of the spread and juxtaposed ribbon.

The invention is described below using the example of filament strands with carbon filaments. However, it is not limited to carbon filaments.

Carbon filaments are sold in filament strands containing 12,000, 24,000, 48,000 or more carbon filaments. The larger the number of carbon filaments, the cheaper the filament strands are usually. The filament strands have in cross section approximately the shape of an ellipse or a circle.

In the production of fiber-reinforced plastics, so-called UD layers are required in many cases. In a UD layer, the fibers or filaments are all in the same main direction. They do not have to be exactly parallel to each other. However, they all go in the same direction. A fiber reinforced plastic will then have an increased tensile strength in that direction.

In order to be able to produce such a UD layer from the filament strands, the filament strands must be arranged side by side and spread out to form ribbons. The then present in a plane next to each other tapes are then co-wound or otherwise processed together. Under certain circumstances, a cross-cohesion between adjacent ribbons is produced.

If in the later plastic product with reinforcing fibers increased tensile strengths in several directions are desired, then several UD layers with different fiber directions placed on each other and then embedded together in a plastic.

A method and a device of the type mentioned is, for example EP 0 972 102 B1 known.

DE 10 2005 008 705 B3 shows an apparatus for feeding slivers to a knitting machine in which slivers are withdrawn from bobbins at a uniform speed but further processed with predetermined down times. During downtime, the slivers are cached in a controlled memory.

Out DE 10 2005 052 660 B3 For example, an apparatus and method for spreading a carbon fiber strand are known. In order to spread the fiber strand better, it is heated by an electric current is passed.

DE 197 07 125 A1 describes a method for producing unidirectional ply, in which the spread fibers are joined together by cross-link yarns to form a web.

The spreading of the filament strands to the tapes is carried out simply by pulling the filament strands with a certain tension over a deflection device, for example a round bar. Due to the tensile stress, all filaments or fibers tend to approach the rod. In this case, filaments or fibers, which are arranged closer to the rod, through the farther away filaments or Fiber displaced laterally outwards. This automatically creates a broadening of the filament strand to the ribbon.

However, it can be observed that a UD ply made with such ribbons has some waviness or unevenness across its length, in other words a non-uniform thickness.

The invention has for its object to produce a UD layer with a uniform thickness as possible.

This object is achieved in a method of the type mentioned in that one spreads the ribbon to a ribbon width which is greater than a pitch width, resulting from the layer width divided by the number of filament strands results.

For the following explanation, the term "filaments" is used. However, the invention is equally applicable to fibers.

It has hitherto been assumed that a UD layer having a predetermined layer width is produced by spreading all the filament strands to the pitch width and then placing them next to one another. The pitch width is the ply width divided by the number of filament strands used. With such spread filament strands to obtain a UD layer with transversely to the longitudinal direction contiguous or colliding ribbon. It has now been found that the propagation of the filament strands to the ribbons Although it is possible in a simple manner, if they are pulled over a deflection device. However, where the filament strand was originally thicker, that is usually in the middle, the thickness of the ribbon is greater than in areas where the filament strand was originally thinner. In simple terms, a thickness distribution over the width of the ribbon, which corresponds approximately to a flat bell curve. Now, if you arrange such ribbon side by side, then this results in a certain ripple in the UD layer transverse to its longitudinal direction. If you extend the ribbon wider than it corresponds to the pitch width, then in principle initially nothing changes in the thickness of each individual ribbon. However, one has a large number of possibilities how to influence either the thickness of each strip alone or the thickness of the UD layer in the transverse direction.

A first possibility is that the strips are pushed together after spreading transversely to the longitudinal direction. The pushing together, for example, by passing the ribbon through a guide that is narrower than the original ribbon width. This guide acts primarily on the outer fibers of the ribbon and shifts them inwards. The ribbon center (seen in the transverse direction) is virtually unaffected by the pushing together. Accordingly, there is an increase in thickness at the longitudinal edges of the ribbon, without a corresponding increase in thickness in the middle of the ribbon. It is preferred that one pushes the ribbon to a ribbon width corresponding to the pitch width. In this case, it is possible to arrange the juxtaposed strips transversely side by side, so to speak, in order to produce a UD layer with a closed surface.

In an alternative embodiment, it is provided that one pushes the ribbon to a ribbon width, which is smaller than the pitch width. In this case, resulting in the finished UD layer between the individual bands smaller distances. This may be desired to allow the passage of plastic when the UD layer is embedded in a plastic matrix. The distances can be chosen to be relatively small, for example 0.1 to 1 mm.

In a further embodiment, it may be provided that the ribbons are arranged overlapping transversely to the longitudinal direction. The overlapping placement may occur after the ribbons have been pushed together transversely. However, the overlapping arrangement can also take place without the strips being pushed together in the transverse direction. In this case, each edge areas are deposited on each other, which have a, compared to the center of the ribbon, smaller thickness. In sum, then results in an approximately uniform thickness across the width of the ribbon. By pushing together the ribbon before overlapping you can adjust the thickness more precisely.

It is preferred that the bands are spread to a ribbon width greater than the pitch width is. This results in overlapping areas, which in sum have the desired thickness.

Preferably, when pushed together, ribbons of varying width are produced. As stated above in connection with the device, in this way, when the strips are brought together into a sheet, it is possible to create gaps between adjacent strips, through which a plastic can later pass to form a fiber-reinforced plastic part. The width change can be done periodically, for example. Adjacent tapes can then be arranged next to one another in such a way that they hit one another with their larger widths, so that a gap remains in the flat material in the areas of smaller width.

Preferably, the filament strands are prepared in at least two different planes. This then leads to the fact that the filament strands do not interfere with each other during spreading. So you can easily spread the filament strands to a width that is greater than the pitch width. Even if the filament strands are spread out to a smaller width or pushed laterally together after spreading to a larger width, it is advantageous if you have enough handling space available for each filament strand or the resulting ribbon.

The object is achieved in a device of the type mentioned above in that the spreading devices are divided into at least two groups, wherein the groups are arranged at different positions and adjacent filament strands are guided by different groups.

With this embodiment, it is possible to widen the individual filament strands in the transverse direction beyond the pitch width, which results from the layer width divided by the number of filament strands used. The fact that adjacent filament strands are spread in different positions, the filament strands do not interfere with the spreading, but they can widen beyond the pitch width addition. After passing through the spreading devices of the different groups, it is then necessary to merely merge the individual strips into one plane or otherwise guide them in such a way that they can be wound up together later.

In this case, it is preferred that at least some spreading devices are each followed by a calibration device which pushes the ribbon transversely to its longitudinal direction to a predetermined width. As explained above in connection with the method, it is possible in this way to equalize the thickness of a ribbon. When spreading the filament strand to the ribbon results in a bell-shaped course of the thickness distribution, ie the ribbon is thicker in the middle than at its edge regions. The calibration device now pushes the filaments in the region of the longitudinal edge in the direction of the center of the ribbon, so that the edge regions are thicker again, but the thickness in the middle of the ribbon remains virtually unchanged. Preferably, the predetermined width is equal to a pitch width corresponding to the ply width divided by the number of filament strands. In this case results in a UD layer in which the fibers are arranged side by side without gaps.

In an alternative embodiment, it is provided that the predetermined width is greater than the pitch width. In this case, the adjacently arranged bands overlap, so that the sum of their border areas is added together. Even with thinner edge areas then results in total thickness, which corresponds much better to the thickness in the middle of the ribbon.

In a third alternative, it may be provided that the predetermined width is smaller than the pitch width. In this case, resulting in the later UD position in the transverse direction gaps between the individual bands that allow a passage of plastic.

The calibration device preferably has a bandwidth variation device. When pushing the ribbon transverse to its direction of rotation, one can thereby produce portions of the bands which have a greater width and portions which have a smaller width. If the individual ribbons are then arranged next to one another, gaps are created in the sheet formed thereby, through which plastic can later pass. This makes it easier to realize a penetration of the gel with plastic. The bandwidth variation device may be formed in different ways. If the calibration device has a rotating shaft with grooves that ultimately define the width of the ribbons, then one can easily change the width of the ribbons by using grooves having a varying width in the circumferential direction. In this case, the width of the ribbons thus produced varies periodically. Another possibility is to form the calibration device by flanges located on a shaft, between which the tapes are passed. By changing the axial position of the flanged wheels can cause a change in the width of the ribbon. One can tune the width variation of adjacent bands to one another such that the bands with their larger widths abut each other when they are arranged next to each other, so that larger gaps are formed at the areas with smaller width.

Fig. 1

eine schematische Darstellung einer Vorrichtung zum Erzeugen einer UD-Lage und

Fig. 2

verschiedene Möglichkeiten zur Einstellung von benachbarten Bändchen.

The invention will be explained below with reference to preferred embodiments in conjunction with the drawing. Herein show:

Fig. 1

a schematic representation of a device for generating a UD layer and

Fig. 2

various options for setting adjacent bands.

Fig. 1 shows a device 1 for producing a UD layer 2, which is wound on a winding 3. In not shown, adjacent turns can be separated by a release paper or other release agent on the winding 3 from each other. Instead of a winding, it is also possible to immediately further process the UD layer 2, for example to produce a multiaxial fabric or a fiber-reinforced plastic.

The device 1 has a filament strand dispenser assembly 4. The filament strand dispenser assembly 4 may be formed, for example, as a gate in which a plurality of coils is arranged, wherein a filament strand is wound on each spool. The filament strand dispenser assembly may also include a plurality of drums or cartons, with a filament tow arranged in each bin or carton.

Filament strands 5 are withdrawn from the filament strand dispenser assembly and passed through a first delivery mechanism 6. Conveniently, the filament strands 5 are arranged parallel to each other here.

In the direction of the filament strands 5 behind the delivery mechanism 6, a first group 7 of spreading devices is arranged and a second group 8 of spreading devices. The spreading device 7 has three rods 9-11, over which the filament strands 5 are drawn with a predetermined tension. The tensile stress is generated by a second delivery mechanism 12, which is arranged shortly before the winding 3.

The second group 8 of spreaders has three rods 13-15 over which other filament strands 5 are pulled with the same tension. The same voltage results from the fact that all filament strands 5 are exposed to the voltage which results in dependence on the tensile stress of the second delivery mechanism 12.

The filament strands 5 are now guided so that adjacent filament strands 5 are alternately fed to the first group 7 and the second group 8 of the spreading devices. The spreading or spreading of adjacent filament strands 5 thus takes place in different planes. This makes it possible to spread the individual filament strands 5 quasi independent of each other. In other words, the filament strands 5 can be spread to ribbons whose width is greater than a pitch width. The pitch width corresponds to the ply width of the finished UD ply 2 divided by the number of filament strands 5.

After passing through the first group 7 or the second group 8 of the spreading devices, the filament strands 5 are in the form of bands 16, 17. These tapes 16, 17 are now performed together by a nip 18, which is formed between two rollers 19, 20 and can also be referred to as a "nip". In the nip 18, the UD layer 2 is then formed, which can be deflected by a further deflection roller 22 and then passed through the second delivery mechanism 12. Other tours are possible.

Since the ribbons 16, 17 have a greater width than the division width, the ribbons 16 overlap, 17. The overlapping areas are pressed together in the nip 18 with a high voltage. You can also omit the nip 18, if you can achieve a tension in the ribbon 16, 17 in other ways on the roller 19, which causes the edge regions of the ribbon 16, 17 are pressed into each other.

• Nach dem Durchlaufen der ersten Gruppe 7 oder der zweiten Gruppe 8 der Ausbreiteinrichtungen haben die Bändchen 16, 17 in ihrer Mitte (dies ist die Mitte quer zu ihrer Laufrichtung) eine Dicke, die etwas größer ist als die Dicke der Bändchen 16, 17 in ihren Randbereichen. Dies ergibt sich wahrscheinlich daraus, dass die Filamentstränge 5 in ihrer Mitte zuvor ebenfalls dicker waren und ein vollständiger Dickenausgleich in den Ausbreiteinrichtungen mit vertretbarem Aufwand nicht realisierbar ist. Dies führt dazu, dass die Bändchen 16, 17 in Querrichtung eine etwas dickere Mitte und dünnere Randbereiche haben. Der Dickenverlauf folgt einer Art "Glockenkurve". Dies würde bei der fertigen UD-Lage 2 zu einer entsprechend variierenden Dicke führen, was in manchen Fällen ungünstig ist. Durch die Überlappung der dünneren Randbereiche ergeben sich in der Summe aber Dicken, die der Dicke in der Mitte der Bändchen 16, 17 entspricht, so dass man die Dicke der UD-Lage in einem hohen Maße gleichförmig halten kann. Eine absolute Konstanz der Dicke ist in vielen Fällen nicht erforderlich.

This procedure has the following advantage:

• After passing through the first group 7 or the second group 8 of the spreading devices, the bands 16, 17 at their center (this is the center transverse to their direction of travel) have a thickness which is slightly greater than the thickness of the bands 16, 17 in theirs edge areas. This is probably due to the fact that the filament strands 5 in their midst were also thicker before and a complete thickness compensation in the spreaders with reasonable effort is not feasible. As a result, the bands 16, 17 have a somewhat thicker center and thinner edge areas in the transverse direction. The course of thickness follows a kind of "bell curve". This would result in the finished UD layer 2 to a correspondingly varying thickness, which is unfavorable in some cases. Due to the overlapping of the thinner edge regions, however, the overall thickness is equal to the thickness in the middle of the ribbons 16, 17, so that the thickness of the UD layer can be kept uniform to a high degree. An absolute consistency of the thickness is not required in many cases.

The bands 16, 17 can still be passed through calibration devices 22, 23 after passing through their respective spreading devices. The calibration devices 22, 23 are in Fig. 2 shown schematically. In the simplest case, these are rods 24, 25 which have alternating circumferential grooves 26, 27 and projections 28, 29.

When the ribbon 16 is passed through the calibration device 22, then, after exiting the calibration device 22, it has a width corresponding to the distance between two protrusions 28a, 28b. Similarly, a ribbon 17 passing through the calibration device 23 has a width corresponding to a distance between two protrusions 29a, 29b.

The two calibration devices 22, 23 are each offset by a ribbon width transversely to the running direction or longitudinal direction of the UD layer 2, so that a projection 28a, 28b is arranged approximately in a gap to a groove 27a, 27b.

By means of a relative adjustment of the width of the groove 27a to the width of the opposite projection 28a, it is possible to produce different configurations of the finished UD layer.

In Fig. 2a For example, a situation is illustrated in which the groove 27c has a width that is less than the opposite projection 28c. Accordingly, a distance 30 transversely to the longitudinal direction results between adjacent bands 16, 17 after passing through the calibration devices 22, 23. This distance can For example, adjust to a size in the range of 0.2 to 1 mm. In the UD layer 2, it is then possible for the plastic to pass through the UD layer.

In Fig. 2b For example, a situation is illustrated in which the width of the groove 27a of one calibration device 23 corresponds exactly to the width of the projection 28a in the other calibration device 22. Accordingly, one can produce here a UD layer in which the individual bands 16, 17 lie side by side without gaps and without overlap.

The thickness of the UD layer is nevertheless kept uniform in these two cases. Namely, it can be observed that the calibration means 22, 23 mainly act on the filaments disposed at the edge portions of the ribbons 16, 17 and push these filaments toward the center of the ribbons 16, 17. This results in a thickening of the ribbons 16, 17 in the edge regions. However, the center of the ribbons 16, 17 remains practically uninfluenced by this displacement of the filaments in the edge regions.

In Fig. 2c a situation is shown in which the groove 26 has a greater width than the opposite projection 29c. Accordingly, there is an overlap 31 between adjacent bands 16, 17. Since the slightly wider bands 16, 17 have also been pushed together transversely to the longitudinal direction, the thickness of the edge regions can be adjusted relatively well so that the sum of the thicknesses of the edge regions can be adjusted later of the Thickness of the ribbon 16, 17 corresponds to its center. A slightly larger thickness is harmless.

If one provides the grooves 26 of the calibration means 23 in the circumferential direction with a varying width, then also arise ribbons 16, 17 with a width that varies continuously and periodically in the running direction. If you later the ribbon 16, 17 merges into a sheet, then arise in the areas of the bands 16, 17, which have a smaller width, gaps or recesses between adjacent ribbon 16, 17, through which a plastic can later, if a fiber reinforced plastic element is produced. Alternatively, it is also possible to use calibration devices 23, in which the bands 16, 17 are passed between flange discs whose axial position can be changed. When the flanges are pushed closer together, resulting band areas with a smaller width. As the flanges are moved farther apart, band areas with a greater thickness result. In all cases, the width variation is relatively small. It is sufficient if the bandwidth is changed by a few percent, for example 3.5% or 10%.

Claims (14)

A method for producing a UD layer (2) having a predetermined ply width from a predetermined number of filament strands (5), wherein the filament strands (5) transverse to the longitudinal direction of the UD layer (2) to ribbons (16, 17) propagates and juxtaposed, characterized in that the strips (16, 17) are spread to a width which is greater than a pitch width, which results from the ply width divided by the number of filament strands (5). Method according to Claim 1, characterized in that the strips (16, 17) are pushed together after spreading transversely to the longitudinal direction. A method according to claim 2, characterized in that the strips (16, 17) are pushed together to a ribbon width corresponding to the pitch width. Method according to Claim 2, characterized in that the strips (16, 17) are pushed together to a ribbon width which is smaller than the division width. A method according to claim 1 or 2, characterized in that arranging the ribbon (16, 17) transversely to the longitudinal direction overlapping. A method according to claim 5, characterized in that the strips (16, 17) spreads to a ribbon width and possibly zusammenschiebt again, which is greater than the pitch width. Method according to one of claims 2 to 6, characterized in that one produces when pushing together strips (16, 17) with varying width. Method according to one of claims 1 to 7, characterized in that the filament strands (5) propagate in at least two different planes. Apparatus for producing a UD layer (2) having a predetermined ply width with a filament strand dispenser assembly (4) from which a predetermined number of filament strands (5) are simultaneously peelable, spreading means (9-11; 13-15) for each Filament strand (5) for spreading the filament strand (5) transversely to its longitudinal direction to a ribbon (16, 17) and a winding device (3) for jointly winding up the expanded and juxtaposed ribbon (16, 17), characterized in that the spreading device (9-11, 13-15) on at least two groups (7 , 8), wherein the groups (7, 8) are arranged in different positions and adjacent filament strands (5) are guided by different groups (7, 8). Apparatus according to claim 9, characterized in that at least some spreading devices (9-11, 13-15) are each followed by a calibration device (22, 23) which pushes the ribbon (16, 17) transversely to its longitudinal direction to a predetermined width , Apparatus according to claim 10, characterized in that the predetermined width is equal to a pitch width corresponding to the ply width divided by the number of filament strands (5). Apparatus according to claim 10, characterized in that the predetermined width is greater than the pitch width. Apparatus according to claim 10, characterized in that the predetermined width is smaller than the pitch width. Device according to one of claims 10 to 13, characterized in that the calibration device (22, 23) has a bandwidth changing device.

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