EP0172369B1 - Method and apparatus for dust removal from fibre material - Google Patents

Description

The present invention relates to a method for separating dust from fiber material which is passed over a sieve-like surface, being exposed to a suction air flow to be passed through the sieve-like surface, and to an apparatus for carrying out this method.

From the licker-in of a card it is known to guide the fiber material during its transport over a sieve-like surface surrounding the licker-in roller (DE-OS 1,510,337). This fiber material is exposed to a radially outward flow of suction air while it is held in the area of action of the licker-in roller. In this way, dust which is loosely located on the outside of the fiber material in the set of the licker-in roller can be sucked off, but there is a risk that fiber residues, shell particles, etc. will stick to the screen-like surface and block it.

Even with the known dust removal in the blow room, the fiber material is guided over sieve-like surfaces (DE-PS 3,304,571). Since here too the suction air flow acts transversely to the direction of fiber transport, there is also the danger here that fiber residues, shell particles etc. lead to a blockage of the screen-like surface.

A proposal is also known to retain the fiber sliver fed to an opening roller of an open-end spinning device as a fiber beard while it is being guided over a sieve-like surface surrounding the opening roller (DE-AS 2,648,715). This has the advantage over cleaning in the area of the lickerin of a carding machine that a very intensive removal of the dust is achieved, since at this point a supplied sliver is dissolved in individual fibers. However, since the fiber beard is still retained here, the dust located between the fibers is stripped off by the clothing of the rotating opening roller. The dust detached from the fibers in this way is then removed by the suction air. In this known device, too, there is a risk that fiber residues, debris, etc., will stick to the sieve-like surface and thus impair the dust separation.

The object of the present invention is therefore to create a method and a device for separating dust from fiber material, in particular on open-end spinning machines, in which this risk of clogging of the screen-like surface does not exist or is at least considerably reduced.

This object is achieved in that the suction air flow, to which the fiber material is exposed in the area of the sieve-like surface, is guided away from the fiber material at an acute angle opposite to the fiber transport direction of the fiber material in motion and is passed through the sieve-like surface in the same direction. This orientation of the suction air flow, which has a movement component opposite to the direction of fiber transport, prevents flight, fiber remnants, shell particles, nits etc. from getting stuck in the sieve-like surface. Due to the inertia, the fibers and dirt particles retain their previous flight direction along the wall containing the screen-like surface. Only the micro-dust particles, which are practically inert due to their small mass and can therefore easily make this change of direction, follow this suction air flow through the sieve-like surface.

A particularly intensive cleaning is possible if the fiber material is held in the area of influence of a clothing roller by the sieve-like surface while it is exposed to the suction air flow.

A further intensification of the cleaning of the fiber material is achieved if it is parallelized before it is exposed to the suction air flow. In this case, a stronger relative movement between the clothing and the fiber material to be cleaned is possible, whereby not only the dust that is already on the surface of the fibers or detached from the fibers is sucked off, but also dust is scraped off the fibers carrying them, so that also this dust can be removed by the suction air flow.

In open-end spinning machines, the fiber material is fed to the clothing roller, which is designed as a opening roller, in the form of a fiber sliver consisting of parallelized fibers. According to a development of the method according to the invention, the fiber material is still retained in the clamping line of the delivery device in the form of a fiber beard while it is exposed to the suction air flow. This further intensifies the stripping effect, which leads to a thorough cleaning of the fiber material. This is extremely important in open-end spinning, since the fiber composite is interrupted during spinning, so that any dirt can lead to considerable impairments in the spinning process.

In order to avoid that light material such as flight etc. permanently settles on the sieve-like surface and thus can impair the functionality of the dust separation device, it is provided according to a further feature of the invention that a jet of air is briefly on the side facing away from the fiber transport path the screen-like surface is directed. This causes these components to be lifted off the sieve-like surface, so that the dust separating device can perform its task perfectly. The cleaning interval for the screen-like surface can thus be based on the working process of the textile machine or device on which the invention subject is applied, agreed that this work process is not affected.

To carry out the method according to the invention, the screen openings of the screen-like surface are inclined at an acute angle opposite to the fiber transport direction. This ensures that the suction air flow, which acts on the side of the sieve-like surface facing away from the fiber transport path, can suck off the dust detached from the fibers, but without larger particles such as dirt or fibers being able to become lodged in the sieve openings.

It has proven to be expedient if the screen openings are designed as elongated holes which extend essentially transversely to the fiber transport direction.

According to an advantageous embodiment of the subject matter of the invention, the screen-like surface is arranged in the peripheral region of a clothing roller. In order to ensure that the suction air flow exerts a centering effect on the fiber / air flow, the sieve openings designed as elongated holes are advantageously arranged at an angle to the transport direction such that - seen in the fiber transport direction - their ends towards an imaginary central Circumferential line of the clothing roller are inclined. In this way it is also achieved that light flight, which is captured by the air flowing through the sieve-like surface, is oriented in the direction of these sieve openings designed as elongated holes and thus passes through these sieve openings. This also reduces the risk of the screen-like surface becoming blocked.

In sheet metal screens, screen openings are usually made by punching. In this way, however, it is not possible to orient the screen openings in the desired manner with respect to the direction of movement of the fiber / air stream. In order to be able to generate a suction air flow oriented in the desired manner in a simple manner, in an advantageous embodiment of the subject matter of the invention, lamellae are formed in the sheet metal by a combined deep-drawing / punching tool, which separate the elongated holes from one another and which are inclined in the fiber transport direction against the fiber transport path . In order to form the elongated holes, material does not even have to be punched out of the sheet; Rather, by making a cut parallel to the desired course of each elongated hole and then plastically deforming the sheet before this cut, the inclined lamella can be formed in relation to the direction of fiber transport.

In order to be able to remove flight components from time to time, which should settle on the screen-like surface despite the inventive inclination of the screen openings, it is advantageous if a blowing air nozzle is provided which is directed towards the side of the screen-like surface facing away from the fiber transport path and which is a short-term one Air jet generating device is assigned.

The subject of the invention can also be used to measure the dust content in a fiber material. For this purpose it is provided in a further embodiment of the device according to the invention that an expanding dust collecting chamber with a plurality of filters arranged one behind the other is arranged with increasing fineness between the sieve-like surface and the suction air source. Since the filters or sieves that the dusty air passes first are coarser than the following filters or sieves, the finer particles of flight and dust are passed through the first sieve or filter and only caught on the one or the next filter, causing a separation different waste components is achieved. So that not only a separation of different types of dust is made possible, but also that the exact ratio of the individual dust, dirt and good fiber fractions can be determined, according to the invention in the fiber transport direction in the wall surrounding the clothing roller, the dust separation opening, which is assigned an expanding dust collection chamber , a dirt separation opening, which is assigned a dirt collection chamber, and a fiber discharge opening, which is assigned a fiber collection chamber.

The invention makes it possible to remove dust from fiber material on a wide variety of textile machines and thereby avoids the risk of clogging of a screen surface which retains the fiber material against the action of a suction air stream. As a result, unchanged conditions with regard to dust separation are achieved for preparation machines and cards etc. even over longer periods of time. In open-end spinning machines, which are very sensitive to dust accumulation, by arranging a screen surface designed according to the invention in the peripheral wall surrounding the opening roller in the area of the fiber material still retained by the delivery device as a fiber beard, not only blockages of the screen-like surface are prevented, but dust deposits in over long operating periods the collecting groove or on the open edge of the spinning rotor avoided, which prevents thread breaks.

The above description shows that the clothing roller, in the range of which the screen-like surface is located, can be designed differently. Depending on the type of machine in which the invention is used, a sawtooth or needle roller (e.g. in the opening device of an open-end spinning device or a carding machine at the licker-in) or an impeller (e.g. in spinning preparation).

• Figur 1 eine Offenend-Spinnvorrichtung im Schnitt mit der erfindungsgemäß ausgebildeten Feinstaub-Abscheidevorrichtung sowie mit einer üblichen Schmutzabscheidevorrichtung ;
• Figur 2 eine erfindungsgemäße Abwandlung der siebartigen Fläche im Schnitt ;
• Figur 3 eine Draufsicht auf die erfindungsgemä- βe siebartige Fläche von der der Ganiturwalze zugewandten Seite ;
• Figur 4 im Schnitt eine erfindungsgemäß ausgebildete Reinigungsvorrichtung einer Vorspinnanlage ;
• Figur 5 in schematischer Seitenansicht eine gemäß der Erfindung ausgebildete Karde ; und
• Figur 6 im Schema eine erfindungsgemäß ausgebildete Staubmeßvorrichtung.

Further details of the invention are explained in more detail with reference to drawings. Show it :

• 1 shows an open-end spinning device in Section with the fine dust separator designed according to the invention and with a conventional dirt separator;
• Figure 2 shows a modification of the sieve-like surface according to the invention in section;
• FIG. 3 shows a top view of the sieve-like surface according to the invention from the side facing the gantry roller;
• FIG. 4 shows in section an inventive cleaning device for a roving unit;
• Figure 5 is a schematic side view of a card designed according to the invention; and
• 6 shows a dust measuring device designed according to the invention in the diagram.

FIG. 1 shows the parts of an open-end spinning device necessary for understanding the invention. In such a spinning device, the sliver 1 to be spun is fed to an opening roller 3 by means of a feed device 2. In the embodiment shown, the feed device 2, which can in principle be designed in different ways, has a delivery roller 20 and a feed trough 21 which cooperates with it. The front end of the fiber sliver 1, which forms a fiber beard 10, is broken up into individual fibers 11 by the opening roller 3 and is fed in this form through a fiber feed channel 30 to a spinning element 31. In the exemplary embodiment shown, this is designed as a spinning rotor, but an electrostatic, pneumatic, friction or other spinning element can also be used as the spinning element. The fiber material in the form of a thread is drawn off from the spinning element 31 in a known (not shown) manner.

The opening roller 3 is surrounded by a housing 32, which is provided with a wear-resistant lining 33, which has the technologically required openings 330 (for feeding the sliver 1 to the opening roller 3) and 331 (for removing the fibers 11 into the fiber feed channel 30). having.

A dust removal opening 4 is provided in the housing 32 between the delivery device 2 and the spinning element 31 and is covered by a screen-like surface 5. The screen-like cover 5 is an integral part of the housing lining 33, on the side facing away from the opening roller 3, the feed trough 21 is supported. For this purpose, the feed trough 21 is associated with two compression springs 210 and 211 in a known manner.

The sieve-like surface 5 has sieve openings 50 which are inclined at an acute angle a opposite to the fiber transport direction (see arrow 34). As FIG. 1 shows, the transport direction is given by the tangent which is applied at the apex of the angle a to the circle defined by the clothing tips 35 of the opening roller 3.

Provided on the feed trough 21 is a pipe socket 40 which is connected to the dust removal opening 4 and to which a hose-like channel 41 connects. A suction air source 43 is connected to the channel 41 via a filter 42.

The fibers 11 are detached from the front end of the sliver 1 by the rotating opening roller 3 and guided between the opening roller 3 and the inner wall of the housing 32 formed by the lining 33 to the fiber feed channel 30, whereby they pass through the lining 33 in the area of action of the clothing tips 35 Opening roller 3 are held. The fibers 11 reach the interior of the spinning element 31 for incorporation into the thread end from the fiber feed channel 30.

On their way from the feed device 2 to the fiber feed channel 30, the fibers 11 are guided over the sieve-like surface 5, which covers the dust removal opening 4. In the area of this sieve-like surface 5, the individual fibers 11 are exposed to the action of the air vortex rotating in the direction of arrow 34 and the action of the air flow sucked through the sieve openings 50 into the dust separation opening 4. This second air flow, which causes separation of dust and fiber material by inertial separation and to which the fiber material is exposed in the area of the screen-like surface 5, is also at this acute angle a opposite to the fiber transport direction (arrow 34) due to the inclination of the screen openings 50 at an acute angle α oriented to this fiber transport direction and is guided away from the fiber material in this direction. Due to the inertia and / or due to the meshing action of the clothing rollers 35, the individual fibers 11 are prevented from following this air stream oriented at an acute angle a opposite to the transport direction. Rather, they continue on their way to the fiber feed channel 30. The practically inert inert dust components, on the other hand, have a high air resistance due to their small size and therefore have a lower sink rate. They can therefore remain in the gas or airborne state for a long time and be transported with the air movement. The dust particles thus follow the change in direction imposed by the air flow and pass through the sieve openings 50 to the filter 42, where they are collected. In order to ensure the suction intensity in the long term, the filter 42 is replaced or cleaned from time to time with a new one.

A particularly intensive dust separation is achieved if the dust is sucked out of the fiber material in the area of the fiber transport path in which it is detached from the fibers 11 anyway. This is the case in the dissolving area, where the fiber material is still retained by the feed device 2 as a fiber beard 10. When the fiber sliver 1 is dissolved in individual fibers 11, the opening roller 3, the mechanical stress on the fibers 11 at the clothing tips 35, the friction of the fibers 11 against one another and on the guide surface and the friction of the fibers 11 the wall of the housing 32 dust on the surface of the fibers rubbed and released. According to FIG. 1, the dust removal opening 4 covered by the sieve-like surface 5 is therefore arranged in the region of this fiber beard 10.

The air stream that is sucked through the screen openings 50 also sucks in light flight, which usually passes through the screen openings 50 without difficulty. Nonetheless, it cannot be avoided that some short fibers and some fiber fly will also become attached to the screen openings 50 over time. In order to avoid impairment of the dust separation, a blow air nozzle 44 is provided in the feed trough 21 according to FIG. 2, which is directed in the opposite direction to the air flowing through the screen-like surface 5 against the side of this surface 5 facing away from the opening roller 3. The blown air nozzle 44 is assigned a control device which generates a short-term compressed air jet. This control device has, for example, a valve which briefly connects the blown air nozzle 44 to the compressed air side of the suction air source 43, which generates the negative pressure in the dust removal opening 4. For this purpose, the control device can be controlled in different ways. It is thus possible for the control device to emit periodic control pulses for controlling a valve upstream of the blown air nozzle 44. However, a vacuum measuring device can also be assigned to the dirt separating opening 4. If, by partially covering the screen openings 50, the negative pressure leaves a predetermined tolerance range, the compressed air is hereby released via the control device. Of course, manual control of a control valve for the blowing air nozzle 44 is also possible.

An air jet is directed briefly through the blown air nozzle 44 onto the side of the screen-like surface 5 facing away from the opening roller 3. This air flow, which is thus oriented in the opposite direction to the air that otherwise flows through the sieve-like surface 5, thus lifts all of the components that may be stuck in the sieve openings from the sieve-like surface 5. The duration during which the compressed air jet acts is so short that it remains practically without harmful effects on the fibers 11 fed to the spinning element 31. If there is nevertheless a risk of malfunctions in the spinning process for certain materials, this screen cleaning process can also take place when the spinning station is not working.

In order to also be able to separate heavy dirt constituents from the fiber / air stream, which generally have a greater mass and consequently also a greater inertia than the individual fibers 11, according to FIG. 1, the wall of the housing surrounding the opening roller 3 in the fiber transport direction (arrow 34) after the dust removal opening 4 a dirt removal opening 37 is provided.

FIG. 3 shows a feed trough 21 which not only receives the dust separation opening 4 but also carries the sieve-like surface 5 covering this dust separation opening. A hose-like channel 81 connects to the feed trough 21. In this exemplary embodiment, the sieve openings 50 are designed as elongated holes which extend essentially transversely to the fiber transport direction (arrow 34). The sieve openings 50, which are designed as elongated holes, are not - as is also possible - arranged at right angles to the fiber transport direction (arrow 34) in this exemplary embodiment, but rather are inclined in such a way that - seen in the fiber transport direction - their ends approach an imaginary center circumferential line 36. On the one hand, this achieves an effect centering on the fiber / air stream rotating with the clothing tips 35 of the opening roller 3. On the other hand, the arrangement and design of the elongated sieve openings 50 means that even flight components and short fibers, which due to their low weight follow the air flow sucked through the sieve-like surface 5, can pass through the sieve openings 50 to the filter 42.

The sieve openings 50 can be produced in various ways, for example by drilling or milling, etc. FIG. 2 shows a sieve-like surface 5, in which the sieve openings 50 designed as elongated holes have been produced by punching and plastic deformation. The edges delimiting the screen openings 50 counter to the fiber transport direction (arrow 34) are formed by lamellae 51 which are inclined in the fiber transport direction against the opening roller 3. As the arrow 52 shows, an air flow is created even with such a design of the screen-like surface 5, which is oriented essentially opposite to the fiber transport direction indicated by the arrow 34.

The greater the degree of dissolution of the fiber material, the better the dust separation. Before the fiber material is fed to the Offenend = spinning device described above, it is therefore parallelized with the aid of draw frames etc. and presented to the opening roller 3 as fiber sliver 1 with parallelized fibers. The fibers 11 detached from this sliver 1 thus also have a parallel position before being exposed to the air flow sucked through the sieve-like surface 5.

Although the dust excretion from a fiber material broken down to individual fibers 11 is particularly intensive, dust can also be separated from non-parallelized fiber material which is guided in flake or fleece form over a sieve-like surface.

A first embodiment of this type is described with reference to FIG. 4, which shows a device for homogenizing, separating and cleaning fiber mixtures (DE-OS 2,217,394). A container 6, to which the fiber material is fed at the top, has two distribution shafts 60 and 600 next to one another, each with an impeller 61 or 610, which has a sealing flue gel 62 or 620 is made of soft material and which rotates in a housing 63 or 630. Each housing 63 or 630 has in its fiber guide area a wall consisting of a screen-like surface 64 or 640. The sieve-like surface 64 or 640 has sieve openings 641 which are inclined at an acute angle a opposite to the fiber transport direction indicated by the arrow 34.

Below the impellers 61 and 610 are two shafts 65 and 650, at the lower end of which cylinders 66 and 660 or 661 and 662 are arranged, which feed the fiber material to a drum 67 or 670. These in turn lead the fiber material for separating heavy dirt components via grate bars 671 to a channel 68, in which the fiber material is pneumatically removed and fed to other machines.

The impellers 61 and 610 rotating in the direction of the arrows 34 remove the fiber material pneumatically fed to them from the distribution shafts 60 and 61. The transport air is extracted together with the dust through the screen openings 641, in which an air flow is achieved with the aid of suction air lines 69 and 690. Since the screen openings 641 are also inclined at an acute angle a opposite to the fiber transport direction (arrow 34), there is no risk of blockage of these screen-like surfaces 64 and 640.

FIG. 5 shows that such a design of a dust separation device is also possible with cards 7. According to the exemplary embodiment shown, the wall surrounding the licker-in roller 70 is interrupted in the fiber transport area. The dirt separation openings 71 and 72 thus formed are each delimited in the transport direction (arrow 34) by a knife 73, with the aid of which coarse dirt is scraped off the fiber material. In order to separate the fine dust, which cannot be removed with the aid of such knives 73, the last dirt separating opening 72 is followed by a sieve-like surface 74 which has sieve openings 740 which, in the manner described, at an acute angle a opposite to the fiber transport direction (arrow 34 ) are inclined. Here, too, a reliable separation of the dust is achieved without the danger of this sieve-like surface 74 becoming blocked. In order to increase the functional reliability even over longer operating times, a compressed air nozzle (not shown) can be provided here (as in the device shown in FIG. 4), which on the side facing away from the licker-in roller 75 (the impellers 61 and 610) onto the screen-like surface 74 (or 64 and 640) is directed so that the airborne components attached to the screen-like surface can be blown off by a brief compressed air blast.

In order to treat the fiber material gently, the fibers that have not yet been parallelized in preparation machines, cards etc. are not subjected to such a strong relative movement as in the opening device of an open-end spinning device. Nevertheless, the dust and dirt content of a fiber material can also be measured with a modification of the device described with reference to FIGS. 1 to 3. Such a modified device designed as a dust and dirt measuring device is shown in FIG. In this device, a loading device 8 with a conveyor belt 80 is provided, which extends into a filling shaft 81 for the fiber material 12. A drive roller 82 is provided for driving the conveyor belt 80 at the lower end of the filling shaft 81. The conveyor belt 80 is deflected at the upper end of the filling shaft 81 by a deflecting roller 83 and a tensioning roller 84 so that the conveyor belt extends from the deflecting roller 82 to a further deflecting roller 85 essentially in the horizontal direction. A compressor roller 86 works together with the deflection roller 83.

On the side opposite the conveyor belt 80, the filling shaft 81 is delimited by sieves 87, 88. Compressed air is fed through the upper sieve 88 to the filling shaft 81, while the lower sieve 87 serves to discharge the exhaust air.

A limit switch 22 is assigned to the feed trough 21 of the feed device 2, which stops the drive motor for the drive roller 82 when the feed trough 21 is over-cycled and thus prevents the further supply of fiber material 12 to the opening roller 3. This prevents the dust content of insufficiently dissolved fiber material 12, which is fed to the feed device 2 in the form of excessively large flakes, from being measured.

The opening roller 3, the dirt separating opening 37 and the dust separating opening 4 with the sieve-like surface 5 are formed in the manner described using the example of FIGS. 1 to 3. Instead of a simple filter 42 - as shown in FIG. 1 - a filter unit 9 is provided in this embodiment, which has a sieve 90 for short fibers and flight and a dust filter 91 one after the other in the suction direction. A valve 93 is connected to the connecting line 92 between the filter unit 9 and the suction air source 43 and, by opening, establishes the connection with the atmosphere and thereby lowers the negative pressure acting in the dust separation opening 4.

A collecting container 38 connects to the dirt separating opening 37.

The fiber feed channel 30 ends in a fiber collecting container 94 which is connected to the suction air source 43 via a line 97 with the interposition of a sieve 95 and a throttle 96. A valve 98 is provided between the fiber collecting container 94 and the throttle 96, with which the connection to the atmosphere can be established in order to be able to control the negative pressure effective in the fiber feed channel 30.

By appropriate coordination of the negative pressures in the dust removal opening 4 and in The fiber feed channel 30 with the aid of the valves 93 and 98 and the throttle 96 determines what proportion of short fibers may pass through the sieve-like surface 5 into the filter unit 9, the arrangement of the sieve openings 50 at an acute angle α opposite to the fiber transport direction (arrow 34) that larger individual fibers 11 do not settle on the screen-like surface 5 and block the screen openings 50.

The fiber material 12 to be checked is kneaded together to form a uniform flake belt, the dimensions of which correspond to a fiber belt usual for open spinning machines. The fiber material 12 is fed between the compression roller 86 and the deflection roller 84, supported by the air flow supplied through the screen 87, and with the aid of the feed device 2 of the opening roller 3. The pneumatic compression of the flake column in the filling shaft 81 ensures an even supply of material to the opening roller 3. If, in exceptional cases, larger flakes are fed to the feed device 2, the limit switch 22 actuated by pivoting the feed trough 21 brings the drive roller 82 and thus the fiber feed to the opening roller to a stop 3rd

Light flight and dust are suctioned off on the screen-like surface 5, while the heavier dirt components are separated by centrifugal force at the dirt separation opening 37.

A suitable choice and sequential arrangement of sieves and filters with increasing fineness (e.g. sieve 90 and dust filter 91) achieve a perfect separation of short fibers and flight on the one hand and dust on the other. By expanding the cross-section through which the air flows in the filter unit 9 relative to the channel 41 and the connecting line 92 in order to form an expanded dust collection chamber, it is achieved that even after the deposit of flight and dust in this filter unit 9, the negative pressure in the dust removal opening is not is significantly affected.

After the test has been carried out, the amounts of dust (on the dust filter 91), short fibers (on the sieve 90), dirt particles (in the collecting container 38) and good fibers (in the fiber collecting container 94) can then be determined by measurement. This measurement can be done in different ways, e.g. B. also done electronically. For example, sensors for counting the fibers 11 or the coarse dirt components are provided in the area of the fiber feed channel 30 and the dirt separating opening 37. Instead of a dust filter, a piezo quartz disc is provided in the filter unit 9, on which the dust settles and thereby changes the frequency of the dust-containing quartz. The degree of dust mass allocation can be determined by comparison with a reference quartz.

This device can also be modified, for. B. by changing the sieve-like surface according to Figure 2 or 3, by choosing a different fiber feed (different feed chute or feed in the form of a sliver of parallelized fibers). In order to optimize the measurement result, especially when presenting disordered fibers, it is also possible to run the fibers collected in the fiber collecting container 94 twice or more through the dust measuring device shown in FIG.

It is also possible to provide the sieve 87 in the filling shaft 81 with sieve openings which are oriented at an acute angle opposite to the fiber transport direction. In this case, the exhaust air is sucked through the filter unit 9 or a second filter unit of this type, so that the amount of waste occurring there can also be measured. In this case, the sieve-like surface is not in a wall surrounding a roller, but dust separation is also possible here without the individual fibers that may be detached from their fiber composite as a flake, cotton web, fleece or fiber band being sucked through this sieve-like surface, since here too the suction air flow is discharged from the fiber material at an acute angle α opposite to the fiber transport direction against the fiber transport path. The described modifications of the sieve-like surface as well as the intermittently operating compressed air flow directed towards the side facing away from the fiber transport path are also. possible here.

A sieve formed in accordance with the sieve 87 can also be used in filling shafts of other textile machines, e.g. B. with cards, find application.

Further modifications of the device by exchanging features with one another and by replacing them with equivalents and their combinations are within the scope of the present invention.

Claims (13)

1. Method for removing dust from fibre material which is conveyed over a sieve-like surface, whereby it is exposed to a stream of suction air passing through the sieve-like surface, characterised in that the stream of suction air is guided away from the fibre material at an acute angle in opposition to the direction of transport of the moving fibre material and is guided through the sieve-like surface in the same direction.

2. Method according to Claim 1, characterised in that the fibre material is kept in the area of influence of a shaped roller by the sieve-like surface, while the fibre material is exposed to the stream of suction air.

3. Method according to Claim 2, characterised in that the fibre material is made parallel before it is exposed to the stream of suction air.

4. Method according to Claim 3, characterised in that the fibre material is held back as a tuft while it is exposed to the stream of suction air.

5. Method according to one or more of Claims 1 to 4, characterised in that a jet of air is briefly directed at the side of the sieve-like surface remote from the path of fibre transport.

6. Apparatus for carrying out the method according to one or more of Claims 1 to 5, having a dust removal opening which limits the path of fibre transport and which is connected to a source of suction air and covered by a sieve-like surface, and having means (3 ; 8) which transport the fibre material over the sieve-like surface (15 ; 64, 640 ; 74 ; 87) while the stream of suction air is effective, characterised in that the sieve-like surface has sieve openings (50 ; 641 ; 740), the limiting surfaces of which are inclined at an acute angle (a) in opposition to the direction of fibre transport.

7. Apparatus according to Claim 6, characterised in that the sieve openings (50 ; 641 ; 740) are constructed as elongate holes which extend substantially transversely to the direction of fibre transport.

8. Apparatus according to Claim 6 or 7, characterised in that the sieve-like surface (5 ; 64, 640 ; 74) is arranged in the peripheral area of a shaped roller (3).

9. Apparatus according to Claims 6 and 7, characterised in that the sieve openings (50 ; 641 ; 740) constructed as elongate holes are arranged at an angle to the direction of transport such that - seen in the direction of fibre transport - their ends are inclined in the direction of an imaginary centre-periphery line (36) of the shaped roller (3 ; 61, 610 ; 70).

10. Apparatus according to one of Claims 7 to 9, characterised by lamellae (51) separating the elongate holes (50 ; 641 ; 740) from one another, which lamellae are inclined at an acute angle (a) in opposition to the direction of fibre transport.

11. Apparatus according to one or more of Claims 6 to 10, characterised by a blowing air nozzle (44) directed towards the side of the sieve-like surface (5 ; 64, 640 ; 74) remote from the path of fibre transport, with which blowing air nozzle (44) there is associated an apparatus generating a brief jet of compressed air.

12. Apparatus according to one or more of Claims 6 to 11, characterised in that a widening dust collection chamber (9) having a plurality of filters (90, 91) of increasing fineness, arranged one after the other, is arranged between the sieve-like surface (5 ; 64, 640 ; 74) and the source (43) of suction air.

13. Apparatus according to one or more of Claims 7 to 12, characterised in that there are arranged, in the direction of fibre transport in the wall surrounding the shaped roller (3), one after the other, the dust removal opening (4), with which a widening dust collection chamber (9) is associated, a dirt removal opening (37), with which a dirt collection chamber (38) is associated, and a fibre take-off opening (30), with which a fibre collection chamber (94) is associated.

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