DE102008033789A1 - Axialfraktionierer - Google Patents

Abstract

An axial fractionator and associated process for the fractionated separation of shives and short fibers from fiber flakes is described. The Axialfraktionierer consists of at least one elongated housing, wherein at a first lateral end of the housing, a filling opening and at a second lateral end of the housing is arranged an outlet, at least one discharge at the bottom of the housing and at least one arranged in the housing screw conveyor, the causes a transport of the fiber flakes on the discharge.

Description

The The present invention relates to an axial fractionator and a Process for the fractionated separation of shives and short fibers from fiber flakes as well as its use.

For cultivation and the harvest of natural fibers already exist efficient working Technologies. The processing of the straw as well as the processing of the resulting products However, it still improves to sufficient quantities and the same lasting qualities for the processing industry (vehicle, construction, etc.) and thus a successful plant operation and a economic production of natural fibers and shives.

For the classification and fractionation of short fiber shives mixtures in fiber production plants one uses the typical from the classifying technique known machines in a variety of combinations, including machines Usage found normally in the cotton industry be used.

Known Machines used in the natural fiber industry for the preparation of short-fiber shives mixture are used mainly serve the classification of the shives. For one additional Cleaning or recovery however, the short fibers that are in the mixture still exist not a satisfactory solution.

To the typical classifying machines for shives in dry fiber production belong on the one hand, the sieve drum, with the shives in different fractions can be classified and various vibrating screens.

however it is impossible, Short fibers with a residual shives content recovering below 6% by mass with the help of these machines. Another widespread machine is the so-called Duvex by van Dommele. This machine comes from the cotton industry, is however for those produced in natural fiber production from native plants Products very costly and especially for the task of separation of shives, Fibers and dust as well as classifying the shives in a machine not suitable. This depends together with the fact that with the Duvex, depending on the design of the machine, either only clean fibers or fractionate shives only. Both Tasks are not feasible with a single machine. This would only be in a machine group consisting of two connected in series Machines possible. The Duvex works roughly like a classic screen drum. additionally has the Duvex but still rotating fingers that are active in the Intervene to be cleaned material while destroying the shives (grind). The fine particles can then pass unhindered through the sieve tray. By grinding the shives is no fractionation possible, there all the shives have the same particle size.

task The present invention is the fractionated separation of fibers and shives made of fiber flakes and a dedusting and fractionating the shives.

The object of the invention is constituted by an axial fractionator
at least one elongated housing, wherein a filling opening is arranged at a first lateral end of the housing and an outlet at a second lateral end of the housing,
at least one discharge at the bottom of the case and
at least one auger arranged in the housing, which causes a transport of the fiber flakes on the discharges.

The casing the Axialfraktionierers invention consists of two parts, a lower part, which is at least a discharge, and an upper part, for cleaning purposes is removable.

Of the upper part of the housing Can be made of a transparent material, such as glass or plastic be produced or have flaps or (visual) window, the one observation of the processes inside the Axialfraktionierers enable.

In addition, can the Axialfraktionierer contain an exhaust gas, with which one Dedusting can make.

The auger in the context of the invention consists of a shaft on the devices, as in For example, paddles are arranged to transport fiber flocks over the discharges.

With the Axialfraktionierer invention is a fiber cleaning possible, in the case of both shunting as well as short fibers can be obtained. Short fibers (short fibers) For the purposes of the invention are fibers having a length of about 5 to 70 mm.

The recovering of short fibers from the mixture with a residual shale content in the fiber of ≤ 6% and residual fiber content in the shives of ≤ 1% can with the Axialfraktionierer invention be achieved.

The Fractionation of fibers and shives only possible with the special choice of paddling tools (mold) and tool speed.

In order to the fibers back from the mixture can be won it is necessary the shives that not bound to the fiber flakes, classified and into different To fractionate grain sizes.

For this are about the discharges preferably perforated screens arranged with different hole sizes.

In order to the shives and short fibers can be classified, d. H. separated according to their size and can be ordered, The perforated screens each have a different hole size. The perforated screens are arranged such that with the shives and Short fibers loaded fiber flakes first on perforated screens with less Hole size to be guided and then over Perforated sieves whose hole size is always gets bigger.

The Perforated sieves form the floor or at least part of the floor of the housing and at the same time cover the events.

The Auger is powered by a motor, the speed of the Rotation of the screw conveyor is controllable.

In a preferred embodiment The invention is the screw conveyor a paddle worm with paddles mounted on a shaft. The shaft is driven by a motor.

The Paddle screw preferably has crescent-shaped paddles. Through this Paddle snails are loaded with shives and short fibers Fiber flakes guided axially along the housing wall.

In a preferred embodiment According to the invention, a plurality of axial fractionators can be coupled to one another. For this purpose, a housing a first Axialfraktionierers with the housing of a second Axialfraktionierers to one of two housings existing Axialfraktionierer coupled together.

at the coupling is preferably in each case the outlet of the first Axialfraktionierers with the filling opening of the coupled to the second Axialfraktionierers.

A Coupling not only has the advantage of making the entire machine lighter transportable, since it consists of several parts. It is by such a construction also possible, the separation and classification the shives and short fibers in two stages. Here, the Paddle screws in the two Axialfraktionierern with different Speeds are operated and / or different paddle shapes be used.

The Auger in the first Axialfraktionierer preferably has sickle paddles or Double sickle paddle and in the second Axialfraktionierer full paddle on.

In order for the fibers to be recovered from the mixture, it is necessary to classify the shives which are not bound to the fiber flakes and to fractionate them into two particle sizes. This makes up about 60% by mass of the starting mixture. This is done in the first stage in the first Axialfaktionsierer. The material is guided axially by a kind of paddle screw, wherein the bottom of the vessel (trough bottom) is provided with two different perforated sieves. By the paddle or also the shape of the paddles, which are similar to a sickle, for example, the material is guided up to a certain point on the paddle along the curved screen wall up to a _critical angle φ crit. At this point it comes to flow of the bulk material on the paddle. This means that the bulk material, which does not yet flow over the paddles, moves laterally in the axial direction and then rolls down on the sieve bottom. Material which can not roll over the paddles in the short time is moved over the paddle screw, tangentially falls back onto the curved sieve bottom and rolls over it again. The grains can align and have time to move through the sieve opening. The material that is still on the sieve bottom is caught by the next paddle and the procedure is repeated, so that each time the shaft rotates, four paddles loosen up the material and clear the sieve surface.

Further The material is moved axially with the shaft rotation. This is adjustable by the pitch of the paddles, with the individual Paddle not overlapping work. They have a negative degree of coverage.

The shaft angular velocity ω is preferably 3 to 10.5 s ^-1 in the first axial fractionator (first stage) and 10 to 26.2 s ^-1 in the second axial fractionator (second stage).

The shaft angular velocity ω can be calculated according to the following formula (formula I): ω = 2 · π · f (formula I) with f = drive frequency

The Orbit velocity v in the first axial fractionator (first stage) is preferably at most 2.7 m / s and in the second Axialfraktionierer (second Stage) a maximum of 6.5 m / s.

The orbit velocity v can be calculated according to the following formula (formula II): ν = 2 · π · r · f (formula II) with f = drive frequency
r = paddle outer radius

at the speeds in the first axial fractionator (first stage) the flakes with the bound shives are not dissolved. This happens afterwards in the second axial fractionator (second stage).

The Fiber flakes are accelerated by the paddle screw and it comes to a throwing motion. Upon reentry into the waveform the flakes are accelerated. Due to the inertia of the flakes as well as their air resistance, the flakes are partially apart cracked. By additional friction on the sieve bottom, the flakes are then finally pulled apart and the shives are thus separated from the fibers.

In addition comes it through the paddles on the shaft of the paddle snail in the first Step to an axial movement depending on the slope of the paddle.

Of the Slope angle α is preferably in a range of 60 ° to 85 °. The pitch angle α results from the chosen one pitch G and the rotor diameter r according to the formula III.

Farther is an embodiment the Axialfraktionierers conceivable, in which in a housing two screw conveyors mounted one behind the other at different shaft speeds can be operated and equipped with different paddles.

Of Furthermore, the object of the present invention by a method solved using at least one Axialfraktionierers invention, at the shives and / or short fibers separates from the fiber flakes and the shives and / or classified short fibers.

Shocks and short fibers are lightweight and firm due to their surface hooked together.

Preferably, the shives and / or short fibers are separated from the fiber flakes with a pad with snail paddles or double-needle paddles so that the shives and / or short fibers can pass through the perforated sieves. Through the paddles of the paddle screw, the fiber flakes are pulled apart, so that the shives fall out of the fiber flakes.

The severed shives and short fibers are preferably classified by the above Austragungen located perforated screens with different hole sizes.

The Bottom of Axialfraktionierers is preferably in cross section essentially V-shaped; only the sieve bottom is preferably substantially U-shaped, so that the paddle screw leads the fiber flakes directly over the bottom. On The underside of the Axialfraktionierers are the discharges, the covered with perforated screens. The hole size of the perforated sieves is chosen so that the shives fall into the first heats and the short fibers in the last Trials for this Own perforated screens with larger holes. The shives and short fibers obtained in this way can be used for a variety of purposes Applications are recycled.

mixtures made of short fibers and shives are suitable for example as litter in horse husbandry and for the Production of furniture panels. The fibers obtained in the last discharge are suitable, for example for the Production of fiber composites.

In order to the desired Classification results can be obtained, the number of discharges and the perforated screens used are varied accordingly.

The Procedure leads one prefers in several stages, wherein the fiber flakes several Axial fractionators happen. By using multiple axial fractionators, which are coupled together, the separation process in several Stages performed become. In the individual stages / Axialfraktionierern can different screw conveyors and / or different paddles are used. Also the speed with the screw conveyor in the axial fractionator can vary.

there one operates the screw conveyors preferably in the respective Axialfraktionierern with different Speed. The different speeds in the respective Axialfraktionierern lead to different results when dissolving the fiber flakes.

The shaft angular velocity ω is preferably set to 3 to 10.5 s ^-1 in the first axial fractionator and 10 to 26.2 s ^-1 in the second axial fractionator.

The Orbit velocity v is preferably set in the first axial fractionator to a maximum of 2.7 m / s and in the second Axialfraktionierer to a maximum 6.5 m / s.

The Slope angle α represents preferably at 60 ° to 85 °.

Of the Axial fractionator becomes 10-40% filled with good (shives-fiber mixture). In a preferred embodiment filled the invention one the Axialfraktionierer to 10-25% with good. Is the Axialfraktionierer too full, the solved scrapings again taken up by the fiber flakes and do not fall on the perforated sieves over the Discharges on the bottom of the case.

Farther The object of the present invention is achieved by the use of at least one Axialfraktionierer invention Extraction of shives and short fibers dissolved. By using the Axialfraktionierers invention it possible also to utilize the by-products of fiber pulping plants. One of these byproducts is a shives-fiber mixture, which is in Fiber cleaning systems accumulates.

The with the axial fractionator according to the invention recovered shives and short fibers can as Litter in animal husbandry, for the production of furniture panels and be used as composites.

in the The invention will be described in more detail below with reference to examples and figures. In detail shows

1 a three-dimensional view of two coupled Axialfraktionierer,

2 a cross-sectional view of two coupled Axialfraktionierer,

3 a sketch of the first stage with sickle paddling and occupancy,

4 a sketch of the good movement over a paddle in the first stage,

5 a sketch of the throwing motion and distribution of the sieving over the sieve,

6 a three-dimensional representation of the wave with sickle paddles,

7 a representation of different paddle shapes,

8th a diagram of the separation sequence of the first stage and

9 a diagram comparing two classification technologies.

The 1 shows two coupled Axialfraktionierer 1 , The axial fractionators 1 consist of a housing 2 with a filling opening 3 and an outlet 4 ,

Through the filling opening 3-1 of the first axial fractionator 1-1 becomes the good 5 (Shives-fiber mixture) in the Axialfraktionierer 1 brought in. In the first axial fractionator 1-1 (first stage) becomes the estate 5 through a paddle screw 6 about the events 7 that attach to the bottom of the axial fractionator 1 located, guided. From there, the estate can 5 through the outlet 4-1 of the first axial fractionator 1-1 led out or through the filling opening 3-2 into another axial fractionator 1-2 be transferred. In the second axial fractionator 1-2 becomes the good 5 also by a paddle screw 6 about the events 7 promoted. Finally, the cleaned fibers pass through the outlet 4-2 from the axial fractionator 1 promoted.

For process monitoring are located on top of the Axialfraktionierers 1 fold 8th or window 13 , by which the good movement in the Axialfraktionierer 1 can be observed.

The in the 1 shown Axialfraktionierer 1-1 and 1-2 have a suction nozzle 14 on the upper housing part, which serves for dedusting.

The 2 shows the material flow of the shives-fiber mixture by two coupled Axialfraktionierer 1 , Each of the illustrated axial fractionators 1-1 and 1-2 owns two discharges 7 for the separate removal of various shives and short fiber fractions (A-D). However, embodiments are also conceivable in which an axial fractionator 1 only one or more than two exits 7 having.

The in the 1 and 2 illustrated cascade of two Axialfraktionierern 1 works in two stages. In the first stage, the loose shives are separated and separated into two fractions. At the same time, the fiber flakes are indeed loosened, but not destroyed. In the loosening first shives, which are included in the flake, moved out and can be classified. In the second stage, the fit of the fibers by working tools, such as full paddles 10-2 , which are also responsible for the material movement in the axial direction, dissolved.

The separation and classification of the shives is done by perforated sieves 9 that are at the bottom of the case 2 the axial fractionator 1 are located. The perforated sieves 9 each have different hole sizes, so that for example in the position A shives with a grain size of 0-3 mm in diameter, in the position B shives with a grain size of 3 to 8 mm in diameter and at the positions C and D shives and short fibers from the Fiber cleaning can be obtained. The cleaned fibers are then passed through the outlet 4 (Position E) from the axial fractionator 1 transported out and sent for further recovery.

The paddle slugs 6 in the axial fractionators 1 be by a motor 12 driven.

In the 3 is the movement of the shives over a perforated screen 9 shown. The amplitude of the shifter movement changes as a function of the shaft angular velocity ω and the pitch angle α (see 6 ) the paddle 10 , The sinusoidal function of the shifter movement S over the perforated screen 9 is represented by a trend line and its direction by an arrow.

The 4 shows a sketch of the material movement over the sickle paddles 10-1 the first stage in a first axial fractionator 1 , Through the sieve paddles 10-1 the sieve bottom is cleared, but a part of the goods 5 over the paddles 10 flows and falls back to the sieve bottom. Here, the shives pass the perforated screen 9 ,

• 1. Bewegung: Die Paddel 10 räumen das Material vom Siebboden. Dabei wandert ein Anteil des Schüttgutes über die Paddel 10 und kann sich somit auf dem frei geräumten Siebboden wieder ausrichten und die Lochsiebe 9 passieren.
• 2. Bewegung: Die Paddel nehmen das Schüttgut bis zu einem Grenzwinkel ϕ mit. Dabei bewegt sich das Material über den Siebboden und passiert dabei teilweise die Lochsiebe 9. Ab dem Grenzwinkel ϕ fängt das Material seitlich entlang des Paddels 10 an zu fließen. Es führt eine axiale Bewegung aus. Anschließend fließt das Material auf dem Siebboden nach unten. Dabei haben die Partikel wieder genügend Zeit sich auszurichten und somit die Lochsiebe 9 zu passieren.
• 3. Bewegung: Die Paddel 10 nehmen das übrige Material, das weder über die Paddel (Bewegung 1) noch seitlich (Bewegung 2) entlang der Paddel 10 bewegt wurde, weiter mit und es kommt zu einem schrägen Wurf. Das Material fliegt über die Welle 11, fällt tangential gegen das Lochsieb 9 und rollt dann wieder auf dem Siebboden entlang. Dabei hat es Zeit, sich auszurichten und kann durch die Lochsiebe 9 fallen.

In summary one can say that in the first stage three movements take place:

• 1st movement: the paddles 10 clear the material from the sieve bottom. A portion of the bulk material migrates over the paddles 10 and can thus align itself again on the cleared sieve bottom and the perforated sieves 9 happen.
• 2. Movement: The paddles take the bulk material up to a limit angle φ. The material moves over the sieve bottom and sometimes passes through the perforated sieves 9 , From the critical angle φ, the material catches laterally along the paddle 10 to flow to. It performs an axial movement. Then the material flows down on the sieve bottom. The particles have enough time again to align themselves and thus the perforated sieves 9 to happen.
• 3rd movement: the paddles 10 take the remaining material that is not above the paddles (movement 1 ) still laterally (movement 2 ) along the paddles 10 was moved, continue with and it comes to a weird throw. The material flies over the shaft 11 , falls tangentially against the perforated screen 9 and then roll back along the sieve bottom. It has time to align and can through the perforated sieves 9 fall.

The 5 shows a sketch of the throwing motion and the distribution of the sieving of the goods 5 over the hole sieves 9 in the second stage, or in one, to the first coupled second Axialfraktionierer 1-2 ,

First, only the not hooked to fibers or incorporated in fiber flakes formed by short fibers shovels are sieved and fractionated. For this are sickle paddles 10-1 or double sickle paddle 10-3 necessary. Only with this paddle shape and at correspondingly low circular path velocities (up to 2.7 m / s) is it possible to screen the shives without dissolving the fiber flakes and also screening off the fibers. The shives are going through these paddles 10 deliberately gently broken up. By sliding along the shives on the sickle edge and the overflow of the sickle flank from a certain critical angle φ only the shives are loosened and can thereby pass through the sieve openings ( 4 ).

The fiber flakes remain when using sickle paddles 10-1 and the selected low orbit speeds. In addition, the formation of fiber flakes under these process conditions is even deliberately and intentionally promoted to prevent premature deposition of the fibers.

Will be a single-stage axial fractionator 1 can only be divided into three fractions: 1. fine shives, 2. rough shives and 3. shives and short fibers.

Will be a two-stage axial fractionator 1 used, so come in the second stage full paddle 10-2 as a separating and transport tool at higher circular path speeds (10 to 26.2 m / s) are used. Through these paddles 10 (Tools) and under these process conditions no more slip of the material flow on the screen surfaces, but the material is thrown targeted, circulated and the flake structure through the full paddle 10-2 destroyed (destroyed) 5 ). According to the chosen screen perforation in this second stage can now with two discharges 7 two different mixtures of shives with short fibers and over the outlet 4 cleaned short fibers are obtained.

6 shows a three-dimensional view of the paddle screw 6 of the axial fractionator 1 with sickle paddling 10-1 , The arrangement of sickle paddles 10-1 is characterized by the distance F between two successive paddles 10 , the pitch angle α, around which the paddles 10 are inclined, and the pitch G, the distance to the repeatedly occurring in a row paddle 10 , Usually the paddles 10 arranged offset by 90 °. Thus, a paddling of four consecutive paddles 10 educated. However, it can also be versions with only two or up to eight paddles 10 be chosen per gear.

7 shows three suitable paddles 10 , These are a sickle paddle 10-1 , a full paddle 10-2 and a double sickle paddle 10-3 , sickle paddle 10-1 and double sickle paddle 10-3 come with a two-stage axial fractionator 1 used in the first stage, full paddle 10-2 in the second stage.

8th shows a diagram of the separation sequence of a (experimental) Axialfraktionierers 1 (or first level). In the diagram, the separation function T _i between the fine and coarse shives (grain size d _i ) is shown taking into account the mass flow ṁ.

in the Specifically, T (d) (V2) shows the separation function for roasted raw materials at a mass flow of 1200 kg / h; T (d) (V1a) the separation function for unroasted raw materials at a mass flow of 1200 kg / h and T (d) (V1b) the separation function for unroasted raw materials at a mass flow of 700 kg / h.

With this (experimental) axial fractionator 1 an optimum mass flow of 700 kg / h shives-fiber mixture was achieved. This corresponds to a total mass flow of about 1500 kg / h starting material.

When cleaning the fibers in a coupled second axial fractionator 1 (second stage) it is necessary with a higher angular velocity ω of the shaft 11 to work. At an angular velocity ω of 26 s ^-1 is an optimal destruction of the flakes with the smallest fiber losses on the perforated screens 9 been determined. The required degree of purity of the short fibers of at least 6% by weight residual shives content is ensured up to a straw mass flow of approximately 2500 kg / h in unroasted or roasted hemp.

In the in 9 shown diagram is shown as the yield of pure material (Y: proportion of the input material in percent) and thus recyclable material through the use of an axial fractionator 1 can be increased. The values resulting from the diagram are summarized in Table 1. Thus, the yield of pure material is increased by about 15% compared to the use of a sieve drum. Table 1 - yield of pure material: P1 in% P2 in% P3 in% S1 0 15.8 9.3 S2 0 17.8 13.3 S + F 40.4 4.4 17.8 F 0 2.4 0 MP 40.4 4.4 17.8 RP 0 36 22.6

• P1 products without the use of a sieving or fractionating device
• P2 products with axial fractionator
• P3 products with screening drum

Products made of fiber-sheath mixture (X1):

• S1 shives fine
• S2 shives rough
• S + F shives with fiber content
• F short fibers

Distribution of products (X2):

• MP mixed product of fibers and shives
• RP pure product

1

Axialfraktionierer

1-1

first Axialfraktionierer

1-2

second Axialfraktionierer

2

casing

3

fill opening

3-1

Filling opening of the first axial fractionator

3-2

Filling opening of the second axial fractionator

4

outlet

4-1

outlet of the first axial fractionator

4-2

outlet of the second axial fractionator

5

Well

6

paddle screw

7

host

8th

flap

9

strainer

10

paddle

10-1

sickle paddle

10-2

full paddle

10-3

Double sickle paddle

11

wave

12

engine

13

window

14

suction

Claims (19)

Axial fractionator ( 1 ) for the fractionated separation of shives and short fibers of fiber flakes consisting of at least one elongated housing ( 2 ), wherein at a first lateral end of the housing ( 2 ) a filling opening ( 3 ) and at a second lateral end of the housing ( 2 ) an outlet ( 4 ), at least one event ( 7 ) at the bottom of the housing ( 2 ) and at least one in the housing ( 2 ) arranged conveying screw, the transport of the fiber flakes on the discharge ( 7 ) causes. Axial fractionator ( 1 ) according to claim 1, characterized in that the underside of the housing ( 2 ) in the field of organizing ( 7 ) Perforated sieves ( 9 ), wherein the hole sizes of the respective perforated sieves ( 9 ) may be different. Axial fractionator ( 1 ) according to claim 1 or 2, characterized in that the screw conveyor a paddle screw ( 6 ). Axial fractionator ( 1 ) according to claim 3, characterized in that the paddle screw ( 6 ) crescent-shaped paddles ( 10 ) having. Axial fractionator ( 1 ) according to one of claims 1 to 4, characterized in that a plurality of axial fractionators ( 1 ) can be coupled together. Axial fractionator ( 1 ) according to claim 5, characterized in that in each case the outlet ( 4-1 ) of the first axial fractionator ( 1-1 ) with the filling opening ( 3 ) of the following axial fractionator ( 1 ) can be coupled. Axial fractionator ( 1 ) according to claim 5 or 6, characterized in that the screw conveyor in the first Axialfraktionierer ( 1-1 ) Sickle Paddle ( 10-1 ) or double-needle paddle ( 10-3 ) and in the second axial fractionator ( 1-2 ) Full paddle ( 10-2 ) having. Axial fractionator ( 1 ) according to one of claims 5 to 7, characterized in that the shaft angular velocity ω in the first axial fractionator ( 1-1 ) 3 to 10.5 s ^-1 and in the second axial fractionator ( 1-2 ) Is 10 to 26.2 s ^-1 . Axial fractionator ( 1 ) according to any one of claims 5 to 8, characterized in that the orbit velocity in the first Axialfraktionierer ( 1-1 ) maximum 2.7 m / s and in the second Axialfraktionierer ( 1-2 ) is maximum 6.5 m / s. Axial fractionator ( 1 ) according to one of claims 5 to 9, characterized in that the pitch angle α is in a range of 60 ° to 85 °. Process for the fractionated separation of shives and short fibers from fiber flakes with at least one axial fractionator ( 1 ) according to one of the preceding claims, characterized in that shives and / or short fibers are separated from the fiber flakes and the shives and / or short fibers classified. A method according to claim 11, characterized in that the shives and / or short fibers of the fiber flakes with a paddle screw ( 6 ) with sickle paddles ( 10-1 ) or double-helical paddling ( 10-3 ) unmixed. A method according to claim 11 or 12, characterized in that the separated shives and short fibers through at the bottom of the housing ( 2 ) arranged perforated screens ( 9 ) classified in each case with different hole sizes. Process according to one of Claims 11 to 13, characterized in that the process is carried out in several stages, the fiber flakes comprising a plurality of axial fractionators ( 1 ) happen. A method according to claim 13, characterized in that the screw conveyors into the respective Axialfraktionierer ( 1 ) operates at different shaft speed. Method according to claim 15, characterized in that the shaft angular velocity ω in the first axial fractionator ( 1-1 ) to 3 to 10.5 s ^-1 and in the second Axialfraktionierer ( 1-2 ) to 10 to 26.2 s ^-1 . Method according to claim 15 or 16, characterized in that the orbit velocity v in the first axial fractionator ( 1-1 ) to a maximum of 2.7 m / s and in the second Axialfraktionierer ( 1-2 ) to a maximum of 6.5 m / s. Method according to one of claims 15 to 17, characterized that one has the pitch angle α 60 ° to 85 °. Use of at least one axial fractionator ( 1 ) according to one of claims 1 to 10, for the production of shives and short fibers.