Spinning preparation device for dedusting a fiber stream

Abstract

The invention relates to a spinning preparation device for dedusting a fiber stream (F), comprising: an inlet (13) via which the fiber stream can be introduced into the device, an outlet (33) via which the fiber stream can be discharged from the device, a first cleaning channel (14) which fluidically connects the outlet (33) to the inlet (13), extends along a first longitudinal axis (L_14) and is delimited by a tubular first wall (15), and a fiber transport device which is configured to convey the fiber stream in the first cleaning channel (14) in a helical manner about the first longitudinal axis (L_14) in a first transport direction, wherein a first portion of the first wall (15) is configured as a first dust filter portion (16), and a second portion of the first wall is configured as a second dust filter portion (17), and the first portion and the second portion are arranged in a diametrically opposing manner with respect to the first longitudinal axis (L_14).

Description

[0001] Internal file number P249943WO1 11 / 11 / 2025

[0002] Device in the spinning mill preparation area for dust removal from a fiber stream

[0003] Description

[0004] The invention relates to a device in the spinning mill preparation for dedusting a fiber stream.

[0005] In spinning preparation, fiber flakes are homogenized and cleaned before being fed into a spinning process to produce yarn. Cleaning the fiber flakes involves removing coarse impurities as well as dedusting. The dust content of the fiber material fed to the spinning machine can significantly impact yarn quality. For example, in OE rotor spinning, the rotor groove quickly becomes clogged with dust remaining in the fiber stream. This leads to a higher probability of yarn breaks and periodic defects, which manifest as a moiré effect in a textile fabric.

[0006] A cleaning device for fiber flakes is known from EP 1 807 562 A1. It comprises a roller fitted with impact elements, arranged in a cleaning chamber, with an inlet at one end and an outlet at the other. Between the inlet and outlet, guide plates inclined to the roller axis are provided to generate a fiber flow rotating around the roller axis. The top of the roller is covered by a wall at a distance from the roller circumference, a substantially vertical section of which is permeable to dust and connected to a vacuum chamber. Grate bars for removing coarse contaminants are provided in a circumferential section offset by approximately 90 degrees. These are not suitable for dedusting the flake flow, as dust has too low a settling velocity.Instead of falling into the collection area located under the grate bars, dust is drawn into the cleaning chamber by the fiber conveyor flow.

[0007] The object of the invention is to provide a device in the spinning preparation for dedusting a fiber stream, which increases the efficiency and quality of the dedusting.

[0008] To solve the problem, a device for dust removal from a fiber stream in the spinning mill preparation area is proposed, comprising: an inlet through which the fiber stream can be introduced into the device; and an outlet through which the fiber stream can be discharged from the device; and a first cleaning channel that fluidically connects the outlet to the inlet and extends along a first longitudinal axis and is bounded by a tubular first wall; and a fiber transport device configured to convey the fiber stream helically around the first longitudinal axis in a first transport direction in the first cleaning channel, wherein a first section of the first wall is the first dust filter section and a second section of the first wall is the second dust filter section. Internal file reference P249943WO1 11.11.is designed in 2025 and the first section and the second section are arranged diametrically opposite each other with respect to the first longitudinal axis.

[0009] The device according to the invention has the advantage that, due to the helical movement of the fiber stream together with the diametrical arrangement of the dust filter sections, the individual fibers or fiber flakes are guided past one of the dust filter sections in different orientations. The fibers or fiber flakes are thus more likely to be dusted from different sides, which significantly improves the efficiency of the dust removal device.

[0010] The fiber stream can be a stream of detached single fibers, a stream of fiber flakes, or a combination of detached fibers and fiber flakes. The first transport direction is from the inlet towards the outlet, or towards the transfer section described below, and can be straight or deviating from a straight path.

[0011] A dust filter section within the meaning of the invention is understood to be a section of the wall that has filter properties such that dust can pass through the section from the cleaning channel, while larger components, in particular the fibers, of the fiber stream are retained by the section in the cleaning channel. Dust comprises solid substances with a particle diameter of less than 500 pm.

[0012] The dust filter sections can be designed as coarse dust filters, medium dust filters, fine dust filters and / or particulate filters, depending on which dust particle size is to be filtered out by the dust filter sections.

[0013] At least one of the dust filter sections can be designed as a perforated sheet. The hole size of the perforated sheet can range from 1 to 8 mm. Alternatively, or in combination, the hole spacing of the perforated sheet can range from 1 to 18 mm. The resulting open area of ​​the perforated sheet, determined by the hole size and spacing, can range from 10 to 60%.

[0014] At least one of the dust filter sections can be designed as a screen or wire mesh. The wire diameter of the screen / wire mesh can range from 0.1 to 1.5 mm. Alternatively, or in combination, the mesh size of the screen / wire mesh can range from 0.1 to 10 mm. The resulting open area of ​​the dust filter section, determined by the wire diameter and mesh size, can range from 10 to 60%.

[0015] In one possible embodiment, the device can include a second cleaning channel that fluidically connects the first cleaning channel to the outlet. The second cleaning channel can extend along a second longitudinal axis and be bounded by a tubular second wall. The first longitudinal axis and the second Internal File Number P249943WO1 11.11.2025

[0016] The longitudinal axes can be arranged parallel to each other. The fiber transport device can be configured to convey the fiber stream in the second cleaning channel helically around the second longitudinal axis in a second transport direction. The second transport direction is directed from the first cleaning channel towards the outlet and can be straight or deviating from a straight path. The second transport direction can be opposite to the first transport direction.

[0017] A first section of the second wall can be configured as a third dust filter section. A second section of the second wall can be configured as a fourth dust filter section. The first and second sections of the second wall can be arranged diametrically opposite each other with respect to the second longitudinal axis.

[0018] The first section of the first wall and / or the second section of the first wall can be permanently and / or interchangeably connected to other sections of the first wall. The first section of the first wall and the second section of the first wall can be offset or spaced apart from each other with respect to the first longitudinal axis.

[0019] The first section of the second wall and / or the second section of the second wall can be permanently and / or interchangeably connected to other sections of the second wall. The first section of the second wall and the second section of the second wall can be offset or spaced apart from each other with respect to the second longitudinal axis.

[0020] In one possible embodiment, at least one of the dust filter sections located downstream of the first dust filter section can have a finer filter fineness than the first dust filter section. The fineness of the dust filter sections can increase with increasing distance from each other in the transport direction from the inlet.

[0021] In another possible embodiment, the fiber transport device can comprise at least one first guide element that extends at least section by section parallel to a helical curve. The at least one first guide element can extend from an inner surface of the first wall in the direction of the first longitudinal axis. The at least one first guide element can be connected to the inner surface of the first wall.

[0022] The fiber transport device can comprise at least one second guide element that extends at least partially parallel to a helical curve. This second guide element can extend from an inner surface of the second wall towards the second longitudinal axis. The second guide element can be connected to the inner surface of the second wall.

[0023] The fiber transport device can include a first transport roller rotatably mounted in the first cleaning channel. The axis of rotation of the first transport roller can be arranged parallel to, and in particular identical to, the first longitudinal axis. When the first transport roller rotates in a first direction about the first longitudinal axis (Internal File No. P249943WO1, 11 / 11 / 2025), the fiber flow can be conveyed in the corresponding first transport direction along the first longitudinal axis.

[0024] The fiber transport device can include a second transport roller rotatably mounted in the second cleaning channel. The axis of rotation of the second transport roller can be parallel to, and in particular identical with, the second longitudinal axis. When the second transport roller rotates in a second direction about the second longitudinal axis, the fiber flow can be conveyed in the corresponding second transport direction along the second longitudinal axis.

[0025] In another possible embodiment, the first and second dust filter sections can be accessed by an extraction device. Alternatively, or in combination, the third and fourth dust filter sections can also be accessed by the extraction device. The extraction device can include a negative pressure arrangement that is fluidically connected to an outer surface of each dust filter section via an extraction chamber. The outer surface of the dust filter sections is the side facing away from the cleaning channel. The negative pressure arrangement can provide a negative pressure in the extraction chamber that is necessary for the dust removal function of the dust filter sections. For example, the negative pressure arrangement can generate a negative pressure of at least 250 Pascals, and in particular at least 650 Pascals, in the extraction chamber.Specifically, the negative pressure system in the extraction chamber can generate a negative pressure of at least 450, 850, 1050, or 1250 Pascals. The negative pressure system can handle an exhaust air volume of 2500 to 4500 m³ / h. 3 / h pump from the extraction chamber.

[0026] The following describes an embodiment of a device according to the invention for dust removal from a fiber stream in spinning mill preparation, with reference to the figures. This shows:

[0027] Figure 1 shows a perspective view of a textile machine in the form of a dust removal device according to an embodiment of the invention.

[0028] Figure 2 shows a cross-section of the device from Figure 1;

[0029] Figure 3 is a perspective view of the cross-section from Figure 2; and

[0030] Figure 4 shows a schematic partial view of the device from Figure 1 with arrows pointing towards

[0031] Representation of the fiber stream.

[0032] Figures 1 to 4, which are described together below, show a dust removal device 1 for spinning preparation in an embodiment according to the invention. The device 1 comprises a housing 10 containing the essential operating elements of the device 1. The housing 10 includes a frame (not shown here, Internal File No. P249943WO1, 11.11.2025) which supports the other elements of the device 1, as well as a cover for the frame. The housing 10 has adjustable feet 11 by means of which the device 1 can be supported on a surface. A display 12 is arranged on the front of the housing 10. The display 12 serves the purpose of making operating states, operating processes, or production values ​​visible to the outside.

[0033] Above the housing 10 is a fiber feed device 2, through which a stream of fibers can be supplied to the device 1 for dust removal. The fibers can be supplied to the device 1 as fiber flakes or in a more dispersed state. The fiber feed device 2 comprises a first tube 3 and a second tube 7, which are fluidically connected to each other via a fan 5. The fan 5 is driven by a motor 6 and conveys the fibers into the device 1 in a flow direction. The second tube 7 terminates in an optional airflow divider 8, which is designed to discharge excess air from the second tube 7 into an air outlet 9.

[0034] The housing 10 incorporates a tubular or channel-shaped inlet 13. The inlet 13 is fluidically connected to the fiber feed device 2 and the second tube 7, respectively. The housing 10 also contains a first cleaning channel 14, which extends along a first longitudinal axis L_14. The first cleaning channel 14 is bounded by a first wall 15. The inlet 13 opens into the first cleaning channel 14 through an opening in the first wall 15. The inlet 13 and the first cleaning channel 14 are thus fluidically connected.

[0035] In this case, the first wall 15 is designed as a dust filter in sections. A first dust filter section 16 is arranged vertically below the first longitudinal axis L_14. This first dust filter section 16 extends along a circular arc around the first longitudinal axis L_14 at an angle of approximately 120 degrees, as indicated by the dotted lines in Figure 2. A second dust filter section 17 is arranged vertically above the first longitudinal axis L_14. This second dust filter section 17 extends around the first longitudinal axis L_14 at an angle of slightly less than 90 degrees, as indicated by the dotted lines in Figure 2. The first dust filter section 16 and the second dust filter section 17 are arranged diametrically opposite each other with respect to the longitudinal axis. In other words, there exists a longitudinal plane in which the first longitudinal axis L_14 lies completely and which intersects the first dust filter section 16 and the second dust filter section 17.

[0036] In the present case, the first dust filter section 16 and the second dust filter section 17 each extend along the first longitudinal axis L_14 from one end face of the first cleaning channel 14 to an opposite second end face. The first dust filter section 16 and the second dust filter section 17 are thus arranged in complete axial overlap with each other. However, it is also conceivable that the first dust filter section 16 and the second dust filter section 17 each extend only partially along the first longitudinal axis L_14. In this case, the first dust filter section 16 and the second dust filter section 17 can be arranged in complete axial overlap, axially overlapping, or without axial overlap with each other.

[0037] The first dust filter section 16 and the second dust filter section 17 are each designed as a perforated sheet or sieve element. The first dust filter section 16 and the second dust filter section 17 are each inserted into a recess in the first wall 15 and are firmly but interchangeably connected to other sections of the first wall 15. The first dust filter section 16 and the second dust filter section 17 are thus fixed relative to the rest of the first wall 15.

[0038] The dust extraction device 1 comprises an extraction device 27, which is designed to transport away dust deposited on the dust filter sections 16, 17. The first

[0039] Dust filter section 16 and the second dust filter section 17 each define, with a side facing away from the first cleaning channel 14, an extraction chamber 28 and a first chamber branch 29 of the extraction chamber 28, respectively. The extraction chamber 28 is further defined by an extraction chamber wall 31. The extraction chamber 28 opens into an extraction pipe 32. The transition between the extraction chamber 28 and the extraction pipe 32 is arranged vertically below the first dust filter section 16. The extraction pipe 32 is pressurized by a negative pressure source (not shown), so that air from the first cleaning channel 14 is drawn through the first dust filter section 16 and the second dust filter section 17, through the extraction chamber 28, and into the extraction pipe 32. In other words, the extraction chamber 28 is pressurized by the negative pressure source.In this process, dust that has settled from the fibers of the fiber stream F at the dust filter sections 16, 17 is extracted and transported away by the corresponding airflow, while the fibers are transported further in the first cleaning channel 14.

[0040] In the first cleaning channel 14, a first transport roller 19 is rotatably mounted about a first longitudinal axis L_14. The first transport roller 19 has a cylindrical base body from which a plurality of drive sections extend radially outwards. In the present example, the drive sections are rod-shaped, but this is not the only possible configuration.

[0041] Several first guide elements 18 are arranged on the first wall 15. The first guide elements 18 are designed to guide the fiber stream F away from the inlet 13. The first guide elements 18 are oriented relative to a transverse plane that is orthogonal to the first longitudinal axis L_14 and, in particular, describe a helical path around the first longitudinal axis L_14. The first guide elements 18 extend over a portion of the circumference around the first longitudinal axis L_14. In this case, the first guide elements 18 are connected to the wall 15 in the region of the second dust filter section 17. Internal file number P249943WO1 11 / 11 / 2025

[0042] However, it is also conceivable that these are connected to wall 15 outside of a dust filter section.

[0043] By rotating the first transport roller 19 around the first longitudinal axis L_14, the fiber stream F is conveyed from the inlet 13 along the first longitudinal axis L_14 into the first cleaning channel 14. The fiber stream F moves helically around the first transport roller 19, or rather around the first longitudinal axis L_14, as can be seen particularly in Figure 4.

[0044] The helical movement of the fiber stream F guides the individual fibers or fiber flakes past one of the dust filter sections 16, 17 in two directions. This increases the likelihood that the fibers or fiber flakes are dusted from different sides, significantly improving the efficiency of the dust removal device 1.

[0045] The housing 10 also contains a second cleaning channel 21, which extends along a second longitudinal axis L_21. The second cleaning channel 21 is bounded by a second wall 22. The first cleaning channel 14 and the second cleaning channel 21 are fluidically connected to each other via a channel-shaped transfer section 20. The transfer section 20 opens into the first cleaning channel 14 via an opening in the first wall 15 and into the second cleaning channel 21 via an opening in the second wall 22. The second cleaning channel 21 fluidically connects the transfer section 20 to a tubular outlet 33. The outlet 33 opens into the second cleaning channel 21 via an opening in the second wall 22. The outlet 33 is connected to an outlet pipe 34, which is subjected to a vacuum via a fiber conveying device (not shown).The inlet 33 is thus fluidically connected to the outlet 33 or the outlet pipe 34 via the first cleaning channel 14, the transfer section 20 and the second cleaning channel 21.

[0046] In this case, the second wall 22 is designed as a dust filter in sections. A third dust filter section 23 is arranged vertically below the second longitudinal axis L_21. The third dust filter section 23 extends along a circular arc around the second longitudinal axis L_21 at an angle of approximately 120 degrees, as indicated by the dotted lines in Figure 2. A fourth dust filter section 24 is arranged vertically above the second longitudinal axis L_21. The fourth dust filter section 24 extends around the second longitudinal axis L_21 at an angle of approximately 45 degrees, as indicated by the dotted lines in Figure 2. The third dust filter section 23 and the fourth dust filter section 24 are diametrically opposed with respect to the second longitudinal axis L_21. In other words, there exists a longitudinal plane in which the second longitudinal axis L_21 lies completely and which intersects the third dust filter section 23 and the fourth dust filter section 24.Internal file number P249943WO1 11.11.2025.

[0047] In the present case, the third dust filter section 23 and the fourth dust filter section 24 each extend along the second longitudinal axis L_21 from one end face of the second cleaning channel 21 to an opposite second end face. The third dust filter section 23 and the fourth dust filter section 24 are thus arranged in complete axial overlap with each other. However, it is also conceivable that the third dust filter section 23 and the fourth dust filter section 24 each extend only partially along the second longitudinal axis L_21. In this case, the third dust filter section 23 and the fourth dust filter section 24 can be arranged in complete axial overlap, axially overlapping, or without axial overlap with each other.

[0048] The third dust filter section 23 and the fourth dust filter section 24 are each designed as a perforated sheet or sieve element. The third dust filter section 23 and the fourth dust filter section 24 are each inserted into a recess in the second wall 22 and are firmly but interchangeably connected to other sections of the second wall 22. The third dust filter section 23 and the fourth dust filter section 24 are thus fixed relative to the rest of the second wall 22.

[0049] The extraction device 27 is also designed to transport away the dust deposited on the dust filter sections 23 and 24. The third dust filter section 23 and the fourth dust filter section 24 each delimit the extraction chamber 28 and a second chamber branch 30 of the extraction chamber 28, respectively, on a side facing away from the second cleaning channel 21. The extraction chamber 28 opens into the extraction pipe 32 at an end arranged vertically below the third dust filter section 23. The extraction pipe 32 is pressurized by a vacuum source (not shown) so that air from the second cleaning channel 21 is drawn through the third dust filter section 23 and the fourth dust filter section 17, through the extraction chamber 28, and into the extraction pipe 32.In this process, dust that has settled from the fibers of the fiber stream F at the dust filter sections 23, 24 is extracted and transported away by the corresponding airflow, while the fibers are transported further in the second cleaning channel 21.

[0050] In the second cleaning channel 21, a second transport roller 26 is rotatably mounted about a second longitudinal axis L_21. The second transport roller 26 has a cylindrical base body from which a plurality of drive sections extend radially outwards. In the present example, the drive sections are rod-shaped, but this is not the only possible configuration.

[0051] Several second guide elements 25 are arranged on the second wall 22. The second guide elements 25 are designed to guide the fiber stream F away from the transfer section 20. The second guide elements 25 are inclined relative to a transverse plane that is orthogonal to the second longitudinal axis L_21 and, in particular, describe a helical course around the second longitudinal axis L_21. Internal file reference P249943WO1 11.11.2025. The second guide elements 25 extend over a portion of the circumference around the second longitudinal axis L_21.

[0052] By rotating the second transport roller 26 about the second longitudinal axis L_21, the fiber stream F is thus conveyed from the transfer section 20 along the second longitudinal axis L_21 into the second cleaning channel 21. The fiber stream F moves helically around the second transport roller 26, or rather around the second longitudinal axis L_21, as can be seen particularly in Figure 4.

[0053] The helical movement of the fiber stream F guides the individual fibers or fiber flakes past one of the dust filter sections 23, 24 in two directions. This increases the likelihood that the fibers or fiber flakes are dusted from different sides, significantly improving the efficiency of the dust removal device 1.

[0054] The first transport roller 19 together with the first guide elements 18, and the second transport roller 26 together with the second guide elements 25, are thus part of a fiber transport device designed to convey the fiber flow F in the first cleaning channel 14 helically around the first longitudinal axis in a first transport direction, and in the second cleaning channel 21 helically around the second longitudinal axis in a second transport direction. In other words, the fiber transport device conveys the fiber flow F from the inlet 13 towards the outlet 33.

[0055] Internal file number P249943WO1 11 / 11 / 2025

[0056] Reference sign

[0057] 1 dust extraction device

[0058] 2 Fiber feed device

[0059] 3 pipe

[0060] 4

[0061] 5 fans

[0062] 6 engine

[0063] 7 pipe

[0064] 8 air flow distributors

[0065] 9 Air discharge

[0066] 10 cases

[0067] 11 Adjustable foot

[0068] 12 ads

[0069] 13 Admission

[0070] 14 Cleaning channel

[0071] 15 wall

[0072] 16 Dust filter section

[0073] 17 Dust filter section

[0074] 18 guiding elements

[0075] 19 Transport roller

[0076] 20 Transfer section

[0077] 21 Cleaning channel

[0078] 22 Wall

[0079] 23 Dust filter section

[0080] 24 Dust filter section

[0081] 25 guiding elements

[0082] 26 Transport roller

[0083] 27 Extraction system

[0084] 28 Extraction chamber

[0085] 29th Chamber Branch

[0086] 30 Chamber branch

[0087] 31 Suction chamber wall

[0088] 32 Suction pipe

[0089] 33 Outlet

[0090] 34 Outlet pipe

[0091] L Longitudinal axis

[0092] F Fiber current

Claims

Internal file number P249943WO1 11 / 11 / 2025 Patent claims 1. Device in the spinning preparation for dedusting a fiber stream (F), comprising: an inlet (13) through which the fiber stream (F) can be introduced into the device (1); and an outlet (33) through which the fiber stream (F) can be discharged from the device (1);and a first cleaning channel (14) which fluidically connects the outlet (33) to the inlet (13) and which extends along a first longitudinal axis (L_14) and which is bounded by a tubular first wall (15), and a fiber transport device which is configured to convey the fiber stream (F) in the first cleaning channel (14) helically around the first longitudinal axis (L_14) in a first transport direction, wherein a first section of the first wall (15) is configured as a first dust filter section (16), characterized in that a second section of the first wall (15) is configured as a second dust filter section (17), wherein the first section and the second section are arranged diametrically opposite each other with respect to the first longitudinal axis (L_14).

2. Device according to claim 1, characterized in that the device (1) comprises a second cleaning channel (21) which fluidically connects the first cleaning channel (14) to the outlet (33) and extends along a second longitudinal axis (21) and is bounded by a tubular second wall (22), and Internal file number P249943WO1 11.11.2025 that the fiber transport device is designed to convey the fiber stream (F) in the second cleaning channel (21) helically around the second longitudinal axis (21) in a second transport direction, and that a first section of the second wall (22) is designed as a third dust filter section (23), and that a second section of the second wall (22) is designed as a fourth dust filter section (24), wherein the first section of the second wall (22) and the second section of the second wall (22) are arranged diametrically opposite each other with respect to the second longitudinal axis (21).

3. Device according to claim 2, characterized in that the first section of the first wall (15) and / or the second section of the first wall (15) is firmly connected to other sections of the first wall (15) and / or that the first section of the second wall (22) and / or the second section of the second wall (22) is firmly connected to other sections of the second wall (22).

4. Device according to one of claims 2 or 3, characterized in that the first section of the first wall (15) and the second section of the first wall (15) are arranged offset or spaced apart from each other with respect to the first longitudinal axis (L_14), and / or that the first section of the second wall (22) and the second section of the second wall (22) are arranged offset or spaced apart from each other with respect to the second longitudinal axis (21). Internal file number P249943WO1 11 / 11 / 2025 5. Device according to one of claims 2 to 4, characterized in that at least one of the dust filter sections (16, 17, 23, 24) which are located downstream of the first dust filter section (16) has a finer filter fineness than the first dust filter section (16).

6. Device according to one of claims 2 to 5, characterized in that at least one of the dust filter sections (16, 17, 23, 24) is designed as a perforated sheet or screen fabric.

7. Device according to one of claims 2 to 6, characterized in that the fiber transport device comprises at least a first guide element (18) which extends at least sectionally parallel to a helical curve and which is connected to an inner side of the first wall (15) and which extends from the inner side of the first wall (15) in the direction of the first longitudinal axis (L_14) and / or that the fiber transport device comprises at least a second guide element (25) which extends at least sectionally parallel to a helical curve and which is connected to an inner side of the second wall (22) and which extends from the inner side of the second wall (22) in the direction of the second longitudinal axis (21).

8. Device according to one of claims 2 to 7, characterized in that the fiber transport device comprises a first transport roller (19) which is rotatably arranged in the first cleaning channel (14) about the first longitudinal axis (L_14) such that when the first transport roller (19) rotates in a first direction of rotation about the first longitudinal axis (L_14), the fiber flow (F) is conveyed in the corresponding first transport direction along the first longitudinal axis (L_14), and / or Internal file number P249943WO1 11.11.2025 that the fiber transport device comprises a second transport roller (26) which is rotatably arranged in the second cleaning channel (21) about the second longitudinal axis (21) such that when the second transport roller (26) rotates in a second direction of rotation about the second longitudinal axis (21), the fiber flow (F) is conveyed in the corresponding second transport direction along the second longitudinal axis (21).

9. Device according to one of claims 2 to 8, characterized in that the first dust filter section (16) and the second dust filter section (17) can be extracted by an extraction device (27), and that the third dust filter section (23) and the fourth dust filter section (24) can be extracted by the extraction device (27), and that the extraction device (27) comprises a negative pressure arrangement which is fluidically connected to an outside of each of the dust filter sections (16, 17, 23, 24) via an extraction chamber (28).

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