WO2014064503A1

WO2014064503A1 - Device for cutting fibrous material and agricultural machine comprising said device

Info

Publication number: WO2014064503A1
Application number: PCT/IB2013/002344
Authority: WO
Inventors: Remi VALLAEY; Filip SANDERS
Original assignee: Huis Vallaey Bvba
Priority date: 2012-10-25
Filing date: 2013-10-21
Publication date: 2014-05-01
Also published as: EP2911501A1; BE1021567B1

Abstract

Device (1) for cutting fibrous material comprising a cutting element which is rotatable about a rotation axis and is provided at both ends with disc-shaped flanges extending transversely to the rotation axis wherein a connecting body (4) is provided between said flanges (2), wherein the connecting body (4) is provided with a passage (5) for a drive shaft (6) of the cutting element and said cutting element comprises at least two of said cutting blades (3) which are provided on said connecting body (4). By means of this device (1), it is possible to cut fibrous material into fibres having a relatively long length and small standard deviation of the fibre length.

Description

DEVICE FOR CUTTING FIBROUS MATERIAL AND AGRICULTURAL MACHINE COMPRISING SAID DEVICE

The present invention relates, on the one hand, to a device for cutting fibrous material comprising a cutting element which is rotatable about a rotation axis and is provided at both ends with disc-shaped flanges extending transversely to the rotation axis and which is provided with one or more cutting blades extending along the longitudinal direction of the device. On the other hand, the present invention relates to an agricultural machine for harvesting and cutting fibrous agricultural crops. r

In harvesting and cutting fibrous agricultural crops, use is made of agricultural machines which are provided with feed rollers and a cutting element. After the agricultural crop has been harvested, the harvested fibrous material is taken to the cutting element via the feed rollers. The cutting element cuts the fibrous material, long fibres, into fibrous material of the desired length, shorter fibres. The same agricultural machine returns the cut fibres to the field. This may be effected in an active manner with the aid of ejecting means or the fibres may just fall from the cutting element onto the field.

Often, use is made of blade drums if the fibrous material is to be cut into pieces of a relatively short length. The expression 'relatively short length' is intended to mean fibres smaller than 20 mm. This is the case, for example, with feed maize. Blade drums are rotating drums on which several blades are arranged. Due to the large number of blades and the speed at which these blade drums rotate, these blade drums are very suitable for obtaining fibres having a relatively short length.

When harvesting and cutting fibrous material, such as hemp, kenaf, sugar cane, etc., fibres having a relatively long length are desirable. Thus, the processing industry requires the length of the fibres to be between 30 cm and 60 cm. It is also important for the processing industry that the different fibres are all of approximately the same length. The standard deviation of the fibre length has to be as low as possible. EP1180322 discloses an agricultural machine with a blade drum which is driven at a reduced speed of 200 to 300 revolutions per minute. Since the blade drum of this agricultural machine rotates more slowly than the blade drum of agricultural machines which are used, for example, to chop/cut feed maize, the fibrous material, the long fibres, can be cut into fibres having a relatively long length, somewhere between 10 cm and 90 cm. However, the problem with this device is that there is a relatively large standard deviation of the fibre length. Many of the fibres are either too small in length (<30 cm) or too large in length (>60 cm). The reason why there are many fibres which are too small in length is that the fibrous material may remain in the drum for a certain period of time, as a result of which the fibres which have already been cut can end up on the feed rollers again. In this way, fibres may be cut more than once by the cutting blades.

NL 1001602 discloses a device for cutting hemp in which the rotating cutting element comprises one cutting blade and a counter-blade. Due to the fact that only one cutting blade is used, fibres having a relatively long length may be obtained, since there is only one cutting action during each rotation of the cutting element. Here, the cutting blade is connected to the drive shaft via a plurality of discs which are arranged on the drive shaft. The problem with this device is that the fibrous material may become stuck around the drive shaft, resulting in the device stalling.

When cutting the fibrous material, it is desirable to prevent frayed fibres and to prevent fibres from not being cut through completely. In order to prevent this, the cutting edge of the blade is bevelled and the counter-blade is straight. This results in a kind of 'scissor effect' when the cutting blade comes into contact with the counter- blade and causes the fibrous material to be cut readily into shorter fibres. However, as the device is being used, the cutting blade becomes increasingly blunt, i.e. less bevelled. In order to prevent the cutting blade from becoming too blunt, the cutting blade has to be sharpened after a certain period of time. The sharpening is carried out by means of a sharpening system, in the workshop or on the field. As a result of sharpening, the cutting blade loses weight. Since only one cutting blade is present in the cutting element, the weight loss therefore occurs on one side of the cutting element, resulting in a cutting element which is no longer balanced after sharpening. In order to rebalance the cutting element after the sharpening, the cutting element may be balanced by means of (fixed) counterweights. If the cutting element is out of balance, i.e. imbalanced, this may have disastrous consequences for, for example, the drive mechanism of the element, since an imbalanced rotating element shakes and vibrates. Rebalancing the cutting element is time-consuming and labour-intensive and also cannot be carried out in the field.

The standard deviation of the lengths of the fibres produced by the device disclosed in NL1001602 is also relatively large. Certain fibres are cut by the cutting blade more than once. Fibres may be cut more than once as a result of the fact that after the fibrous material has been cut, the cut material does not always immediately fall back onto the field from the cutting element. In this way, fibrous material may remain in the cutting element for a certain period of time, as a result of which it may end up back on the feed rollers after it has already been cut. It is a first object of the present invention to provide a device for cutting fibrous material comprising a cutting element whereby fibres can be produced which have a relatively long length and whose standard deviation of the fibre length is small, and which does not pose a risk, or poses only a very small risk, of fibres winding themselves around the drive shaft which drives the cutting element.

This object is achieved by providing a device for cutting fibrous material comprising a cutting element which is rotatable about a rotation axis and is provided at both ends with disc-shaped flanges extending transversely to the rotation axis and which is provided with one or more cutting blades extending along the longitudinal direction of the device, wherein a connecting body is provided between said flanges which extends along the longitudinal direction of the device, wherein the connecting body is provided with a passage for a drive shaft of the cutting element, wherein said cutting element comprises at least two of said cutting blades which are provided on said connecting body and wherein the cross section, at right angles to the longitudinal direction of the device, of the connecting body is wider at the location of said passage for the drive shaft than at the location of said cutting blades.

The cutting element is in particular suitable for cutting fibrous material into fibres of a relatively long length. Thus, fibres having a length of between 30 cm and 60 cm can be obtained. The longitudinal direction of the device substantially corresponds to the direction of the rotation axis of the device.

The drive shaft is arranged in a passage of the connecting body of the cutting element. The connecting body protects the drive shaft from the fibrous material, so that the fibrous material cannot wind itself around the drive shaft. The cut fibres are pushed down by means of the connecting body, as a result of which they readily leave the cutting element. The specific shape of the connecting body, i.e. the fact that the cross section of the connecting body, at right angles to the longitudinal direction of the device, is wider at the location of said passage for the drive shaft than at the location of said cutting blades, provides good access for the fibrous material in the cutting element and makes it easier for the fibrous material and therefore also the cut fibres to be pushed down. As a result thereof, the cut fibres are able to readily leave the cutting element. In addition, the connecting body divides the cutting element into as many chambers, cutting chambers, as there are cutting blades. That is to say that once a cut fibre is situated in one cutting chamber, it will not readily be able to move to another cutting chamber, or will only be able to do so with difficulty. After cutting, a cut fibre will immediately be guided to the field via the connecting body and can thus not be cut more than once. As a result thereof, the standard deviation of the fibre length is small.

In a preferred embodiment, the cutting element contains two mutually opposite cutting blades. A cutting element having only two cutting blades is more suitable for cutting fibrous material into fibres of a relatively long length than cutting elements having three or more cutting blades. There are two options to cut fibrous material into fibres of a relatively long length. It is possible to limit the rotary speed of the cutting element in such a manner that it takes longer for the fibrous material which enters the cutting element to be cut again and/or to limit the number of cutting blades in order to limit the number of cutting actions per rotation of the cutting element. Slow rotation of a cutting element is possible if the cutting element is driven via, for example, a hydromoter (hydraulic motor). By means of a hydromotor, it is possible to achieve a low rotary speed of the cutting element. However, the minimum rotary speed which can be attained using such a hydromotor or other drive means is limited. It is therefore simpler to use a smaller number of cutting blades. The advantage of two cutting blades is that the rotary speed can be higher than with 3 or a plurality of cutting blades in order to produce fibres of the same length. A higher rotary speed is better for a hydromotor and other drive means. An additional advantage of the use of two mutually opposite cutting blades is that there is no risk of imbalance after the cutting blades have been sharpened. When sharpening the cutting blades by means of, for example, a sharpening system, both blades are sharpened in an equal manner and thus both cutting blades lose an equal amount of weight. Since the blades are situated opposite one another, there is therefore an equal amount of weight loss at opposite parts of the cutting element and the cutting element remains balanced after each sharpening action. No additional measures therefore have to be taken after each sharpening action to prevent imbalance. Of course, it is also possible to prevent imbalance where there are three of more cutting blades present. This is done by ensuring that the distances between the successive cutting blades of the cutting element are identical and the cutting blades extend at the same distance from the rotation axis.

Another advantage is the fact that the size of the cutting element can be reduced if only two cutting blades are used. In order to produce fibres of a relatively long length, the distance between the cutting blades has to be sufficiently large. This distance determines the dimensions of the cutting chamber. Before the fibrous material can be cut, part of the fibrous material has to first of all be in the cutting element, i.e. in the cutting chamber. When cutting this fibrous material, it is important that the fibrous material which ends up in the cutting chamber is not longer or not much longer than the length which the dimensions of the cutting chamber allow. Therefore, in order to be able to cut long fibres, the dimensions of the cutting chamber cannot be too small. It is true for cutting elements of identical dimensions that the fewer cutting chambers there are, the larger the cutting chambers are. If there are only two cutting blades and therefore two cutting chambers, the dimensions of the cutting element can be made smaller than if there were three or more cutting blades and this produces a cutting chamber of the desired dimensions. A smaller cutting element not only means a reduction in weight and volume, but also a saving in material and hence a cost saving. The cross section, at right angles to the longitudinal direction of the device, of the connecting body, is furthermore preferably elongate. Said cross section is longer than it is wide. This shape is important because with an elongate shape, the dimensions of the cutting chamber are sufficiently large to accommodate fibrous material having a relatively long length.

Preferably, the separating body is a closed body. In this way, fibres are not able to travel from one cutting chamber to another cutting chamber. In a preferred embodiment, said connecting body is a substantially solid body. A solid body means more weight, therefore the entire cutting element will also weigh more. A greater weight contributes to maintaining a constant rotary speed. The higher the weight, the more energy is required to change the rotary speed. The more fibrous material has to be cut, the greater the resistance when cutting said material and the greater the risk of reducing the rotary speed. However, if the cutting element has sufficient weight, this risk is reduced. A constant rotary speed is important to obtain fibres of identical length, i.e. fibres with a relatively small standard deviation of the fibre length. The cutting blades are preferably provided on said flanges. Since the cutting blades are then not only arranged on the connecting body, but also on the flanges, the cutting blades are more securely anchored in the cutting element, which makes the cutting element stronger. More preferably, the cutting blades are arranged on the outer side of the flanges. The cutting blades are then situated on the outer side of the cutting element and the cutting blades then determine the dimensions of the cutting element. The dimensions of the cutting element are preferably as small as possible and therefore not larger than is necessary for the cutting blades.

More preferably, between the connecting body and said cutting blades, supporting plates are provided which extend along the longitudinal direction of the device. The cutting blades, which also extend along the entire longitudinal direction of the device, are thus supported along their entire length, which improves the sturdiness and strength of the cutting element. Furthermore, these supporting plates are preferably also attached to said flanges in order to produce a cutting element which is even sturdier and stronger.

In a specific preferred embodiment, underneath the cutting face of each cutting blade, there is an unwinding plate, so that the fibrous material can readily come off said cutting blade after it has been cut by one of the cutting blades. When cutting fibrous material using a cutting blade, there is a risk that the fibrous material will get caught underneath the cutting blade at the location of the portion which has been cut. If the cut fibres remain caught there, there is a risk that they will not leave the cutting element immediately after cutting and that they will remain in the cutting element for a certain period of time. As a result thereof, fibres could be cut more than once, producing fibres which are too small and resulting in a large standard deviation of the fibre length. More preferably, each unwinding plate is attached to said cutting blade and is attached to said flanges. The unwinding plate is thus securely anchored in the cutting element.

Preferably, a curved plate is attached to the connecting body for each of said cutting blades in order to guide the cut fibrous material downwards, thus making it easy for the cut fibrous material to be removed from the cutting element. This curved plate moves the cut fibre away from the cutting element, as it were, and helps to remove the cut fibres from the cutting element. The disc-shaped flanges are preferably cylindrical and provided with recesses for the bearings of the cutting element. These recesses are situated on the outer side of the cutting element. Since the bearings are provided in said recesses of the flanges, they are separated from the fibrous material. Fibrous material can then not hamper the operation of the bearings.

The second object of the present invention is to provide an agricultural machine for harvesting and cutting fibrous agricultural crops, wherein fibres of relatively long length can be obtained which have a small standard deviation of the fibre length and wherein there is no risk, or only a very small risk, of fibres winding themselves around the drive shaft of the cutting element.

This object is achieved by providing an agricultural machine for harvesting and cutting fibrous agricultural crops comprising a device as described above.

The agricultural machine is in particular suitable for harvesting fibrous material and cutting fibrous material into fibres having a length between 30 cm and 60 cm. Preferably, the agricultural machine comprises a counter-blade which is arranged in a fixed position in the agricultural machine and the distance between the rotation axis and the counter-blade is substantially identical to the distance between the rotation axis and the cutting face of said cutting blades. Fibrous material can be cut more easily if, in addition to the cutting blade, a counter-blade is also present. During cutting of the fibrous material by the cutting blade, the fibrous material is partly held back by the counter-blade, as a result of which the cutting action can be carried out in a simple manner. The counter-blade is situated at approximately the same distance from the rotation axis as the cutting face of the cutting blade, so that each cutting action can be carried out smoothly.

Preferably, the agricultural machine comprises fixed side walls which extend on either side of said device. These fixed side walls prevent fibrous material from ending up in parts of the agricultural machine where it does not belong and where it can cause damage. In addition, these fixed side walls protect the bearings against fibrous material.

The present invention will now be explained in more detail by means of the following detailed description of a preferred embodiment of a device for cutting fibrous material according to the present invention and an agricultural machine comprising said device according to the present invention. The sole aim of this description is to give illustrative examples and to indicate further advantages and features of this device and this agricultural machine comprising this device and can therefore by no means be interpreted as a limitation of the area of application of the invention or of the patent rights defined in the claims. Reference numerals are used in this detailed description to refer to the attached drawings, in which:

Figure 1 shows a cross section of a cutting element, drive shaft, flat side walls and bearings along the longitudinal direction of the device;

Figure 2 shows a cross section of the cutting element, drive shaft, counter-blade, at right angles to the longitudinal direction of the device;

Figure 3 shows a perspective view of the cutting element and the bearings.

The agricultural machine according to the present invention comprises feed rollers, a device (1) for cutting fibrous material, bearings (11) and drive means for the feed rollers and said device (1), wherein the device (1) for cutting fibrous material comprises a cutting element. This agricultural machine is suitable for harvesting and cutting fibrous material, such as hemp, kenaf, sugar cane etc. to the desired fibre length. The harvested material is taken to the cutting element via the feed rollers, following which the fibrous material is cut and the cut fibres fall back onto the field. These fibres then rot on the field and are subsequently collected. The fibres may, inter alia, be used for the processing industry.

In the case of hemp fibres, for example, the processing industry requires fibres having lengths between 30 cm and 60 cm. Preferably, the standard deviation of the fibre length is also as small as possible. Obviously, it is possible to harvest and cut other fibrous agricultural crops which yield fibres having a relatively long length using this agricultural machine according to the invention.

The substantially cylindrical cutting element which is illustrated in the figures is particularly suitable for producing fibres of a relatively long length, such as fibres between 30 cm and 60 cm. Obviously, the range of the cut fibres may also differ from the abovementioned range. In addition, the standard deviation of the fibre length is relatively small. At both its ends, the cutting element is provided with cylindrical flanges (2) extending transversely to the rotation axis and is provided with two mutually opposite cutting blades (3) which extend along the longitudinal direction of the device (1) and at an equal distance from the rotation axis. Between said flanges (2), a solid closed connecting body (4) is provided which extends along the longitudinal direction of the device (1) and which is provided with a passage (5) for a drive shaft (6). In this embodiment, the drive shaft (6) does not form part of the cutting element. However, the cutting element may also be configured in such a manner that the drive shaft (6) forms a part of the cutting element. The cutting blades (3) are arranged on the connecting body (4) and on the outer side of said flanges (2). The cutting blades (3) thus define the sleeve surface of the substantially cylindrical cutting element. In the case of the cutting element as illustrated in the figures, the cutting blades (3) are not directly connected to said flanges (2) and the connecting body (4), but instead are attached to supporting plates (14). These supporting plates (14) are attached to the outer side of said flanges (2) and the connecting body (4) and extend along the longitudinal direction of the device (1). By not directly attaching the cutting blades (3) to the flanges (2) and the connecting body (4), but instead to said supporting plates (14), the cutting blades (3) are better supported. The cutting blades (3) are connected to the supporting plates (14) by means of bolts (15). Obviously, other types of connection are also possible.

The cross section, at right angles to the longitudinal direction of the device (1), of the connecting body (4) is elongate and at the location of said passage (5) for the drive shaft (6) it is wider than at the location of said cutting blades (3). The cross section is in the shape of two substantially identical isosceles trapeziums, wherein the large bases (the parallel sides having the greatest length) of the two trapeziums bear against each other at the location of said passage (5). As a result thereof, said cross section is therefore wider at the location of said passage (5) of the drive shaft (6) than at the location of said cutting blades (3).

Underneath the cutting face (7) of each cutting blade (3), there is an unwinding plate (8). This unwinding plate (8) is attached to said cutting blade (3) and to said flanges (2). The unwinding plate (8) is at an acute angle to the cutting blade (3) to which it is attached. Furthermore, for each cutting blade (3), the cutting element comprises a curved plate

(9) which is attached to the connecting body (4). The curved plate (9) extends from the unwinding plate (8) to just beyond the passage (5) of the drive shaft (6).

The agricultural machine comprises bearings (11) and the drive means of the agricultural machine for the cutting element comprises a drive shaft (6). Said bearings (11) are situated in the recesses (12) of the cylindrical flanges (2). The flanges (2) have these recesses (12) because they are hollow cylinders with a first open base which is situated on the outer side of said cutting element, a substantially closed sleeve surface and a substantially closed second base.

The counter-blade (10) is situated at substantially the same distance from the rotation axis as the cutting faces (7) of the two cutting blades (3). The counter-blade (10) has a straight cutting face and each cutting blade (3) has an oblique cutting face (7) in which the narrowest portion of the cutting face (7) first encounters the counter-blade

(10) . This design ensures a good cutting action. This cutting action can be described as a scissor effect. When harvesting and cutting fibrous material, such as hemp, use is made of an agricultural machine according to the invention. The hemp is harvested and the long fibres of the hemp are taken to the cutting element via the feed rollers. The long fibres enter the cutting element and are cut by the cutting blades (3). The length of the fibres which are cut from the long hemp fibre is inter alia determined by the rotary speed of the cutting element. This is the speed of rotation of the cutting element. In order to obtain fibres of 30 cm to 60 cm, the cutting element rotates at between 100 revolutions/minute and 300 revolutions/minute. The cutting element is driven by a hydraulic motor. A hydraulic motor makes it possible to operate at a low rotary speed.

The speed of rotation of the feed rollers is adapted to the speed of rotation of the cutting element. Adjusting the speeds of rotation of the feed rollers and the cutting element in a continuously variable way is carried out by means of a control cabinet. This control cabinet may additionally be provided with a fuse, so that when the cutting element is overloaded due to an excess of fibrous material in the cutting element, the feed rollers are immediately switched off in such a manner that further accumulation of fibrous material in the cutting element is prevented. The shape of the cutting chambers (16) of the cutting element illustrated in the figure is determined, inter alia, by the connecting body (4) and the curved plates (9). This shape is important in connection with the entry of the fibrous material into the cutting element and the removal of the cut fibres from the cutting element. As a result of the specific shape of the connecting body (4) described here, there is sufficient space when the long fibres enter the cutting element because uncut long fibres enter on the side of the cutting element where the connecting body (4) is not covered by the curved plate (9) after each cutting action. The fibres can thus enter unhampered. Uncut fibres enter from the side of the cutting blade (3) which is situated opposite the cutting face (7) of the cutting blade (3). Since each curved plate (9) extends from the unwinding plate (8) to just beyond the passage (5) of the drive shaft (6), there is therefore no curved plate (9) present on the opposite side of the cutting face (7) of each cutting blade (3). When the long fibres enter the cutting element, the cutting element obviously continues to rotate. The portion of the long fibres which enters later is pushed downwards by the curved plate (9). The fibrous material which has entered the cutting element is cut by the cutting blade (3). This cutting action is executed smoothly as a result of the cooperation between the cutting blade (3) and the counter- blade (10).

In order to enable this cutting action to always run smoothly, the cutting blades (3) have to be sharpened regularly by means of a sharpening system. The two cutting blades (3) are sharpened to an equal degree by means of a sharpening system, so that the weight loss of the two cutting blades (3) after each sharpening action is identical. As the cutting blades (3) are situated directly opposite each other and are at equal distances from the rotation axis, the cutting element remains balanced after each cutting action. For the cutting element illustrated in the figures, there is therefore no risk of imbalance after the sharpening actions have taken place. The unwinding plate (8) and the above-described exact position of the unwinding plate (8) ensure that the cut fibres do not get caught at the location where they have been cut, in the wedge formed by the cutting blade (3) and the supporting plate (14). As a result thereof and by means of the curved plate (9) which forces the cut fibres in the direction of the field, the cut fibres can easily leave the cutting element and the cut fibres fall back onto the field. The connecting body (4), the unwinding plates (8) and the curved plates ensure that fibres are easily removed from the cutting element after cutting and cannot be cut more than once. The fibres are, as it were, guided to the field, resulting in a relatively small standard deviation of the fibre length, as cut fibres are not cut again.

Due to the fact that the connecting body (4) is solid, the cutting element has sufficient weight and a lot of energy is required to change the rotary speed of the cutting element. The rotary speed of the cutting element therefore readily remains constant, as a result of which all the cut fibres obviously also have approximately the same length.

The drive shaft (6) is situated in a passage (5) of the connecting body (4) and is completely protected by the connecting body (4) via the closed connecting body (4). The fibrous material can thus not wind itself around the drive shaft (6) and there is consequently no risk of the cutting element stopping to rotate due to the drive shaft (6)'no longer working as a result of an accumulation of fibrous material. In addition, the agricultural machine comprises fixed side walls (13) which extend on either side of the cutting element. These ensure that fibrous material cannot reach parts of the agricultural machine where it is not meant to be and protect the bearings (11), together with the flanges (2), against fibrous material.

Claims

C L A I M S

1. Device (1) for cutting fibrous material comprising a cutting element which is rotatable about a rotation axis and is provided at both ends with disc-shaped flanges (2) extending transversely to the rotation axis and which is provided with one or more cutting blades (3) extending along the longitudinal direction of the device (1), characterized in that a connecting body (4) is provided between said flanges (2) which extends along the longitudinal direction of the device (1), wherein the connecting body (4) is provided with a passage (5) for a drive shaft (6) of the cutting element, wherein said cutting element comprises at least two of said cutting blades (3) which are provided on said connecting body (4), and in that the cross section, at right angles to the longitudinal direction of the device (1), of the connecting body (4) is wider at the location of said passage (5) for the drive shaft (6) than at the location of said cutting blades (3).

2. Device (1) according to Claim 1, characterized in that the cutting element contains two mutually opposite cutting blades (3).

3. Device (1) according to Claim 1 or 2, characterized in that the cross section, at right angles to the longitudinal direction of the device (1), of the connecting body (4), is elongate.

4. Device (1) according to one of the preceding claims, characterized in that the connecting body (4) is a closed body.

5. Device (1) according to one of the preceding claims, characterized in that said connecting body (4) is a substantially solid body.

Device (1) according to one of the preceding claims, characterized in that the cutting blades (3) are provided on said flanges (2).

7. Device (1) according to one of the preceding claims, characterized in that, between the connecting body (4) and said cutting blades (3), supporting plates (14) are provided which extend along the longitudinal direction of the device (1).

8. Device (1) according to one of the preceding claims, characterized in that, underneath the cutting face (7) of each cutting blade (3), there is an unwinding plate (8), so that the fibrous material can readily come off said cutting blade (3) after it has been cut by one of the cutting blades (3).

9. Device (1) according to Claim 8, characterized in that each unwinding plate (8) is attached to said cutting blade (3) and is attached to said flanges (2).

10. Device (1) according to one of the preceding claims, characterized in that a curved plate (9) is attached to the connecting body (4) for each of said cutting blades (3) in order to guide the cut fibrous material downwards, thus making it easy for the cut fibrous material to be removed from the cutting element.

11. Device (1) according to one of the preceding claims, characterized in that the disc-shaped flanges (2) are cylindrical and provided with recesses (12) for the bearings (11) of the cutting element, wherein said recesses (12) are situated on the outer side of the cutting element.

12. Device (1) according to one of the preceding claims, characterized in that the device (1) is suitable for cutting fibrous material into fibres having a length between 30 cm and 60 cm.

13. Agricultural machine for harvesting and cutting fibrous agricultural crops, characterized in that said agricultural machine comprises a device (1) according to one of the preceding claims.

14. Agricultural machine according to Claim 13, characterized in that the agricultural machine comprises a counter-blade (10) which is arranged in a fixed position in the agricultural machine and in that the distance between the rotation axis and the counter-blade (10) is substantially identical to the distance between the rotation axis and the cutting face (7) of said cutting blades (3).

15. Agricultural machine according to Claim 13 or 14, characterized in that the agricultural machine comprises fixed side walls (13) which extend on either side of said device (1).

16. Agricultural machine according to one or more of Claims 13 to 15, characterized in that the agricultural machine is suitable for harvesting fibrous material and cutting fibrous material into fibres having a length between 30 cm and 60 cm.