WO2003031697A1

WO2003031697A1 - Device for detecting and eliminating foreign bodies on a nonwoven fabric, produced by means of a card

Info

Publication number: WO2003031697A1
Application number: PCT/EP2002/010924
Authority: WO
Inventors: Andreas Meyenhofer; Walter Kiechl; Christoph Schönbächler; Thomas Brose
Original assignee: Jossi Holding Ag; Maschinenfabrik Rieter Ag
Priority date: 2001-10-05
Filing date: 2002-09-28
Publication date: 2003-04-17
Also published as: EP1432854B1; EP1432854A1; DE50205759D1; EP1300493A1

Abstract

The invention relates to an elimination device (6), which is controlled by a detecting device (5) and arranged in the area of the doffer roller (3) or doffer device (4) of a card. Said elimination device comprises at least one guide wall (19) for the nonwoven fabric (2), in which at least a series of suction orifices (20) is arranged over the total width of said wall. Each suction orifice adjoins to a flow channel, provided with a Venturi nozzle for producing a suction effect.

Description

Device for recognizing and eliminating foreign substances on a nonwoven fabric formed by a card

The invention relates to a device for recognizing and eliminating foreign matter on a nonwoven fabric formed by a card according to the preamble of claim 1. The separation of foreign matter from the nonwoven fabric on the card is intended to prevent it from remaining in the card sliver, where it will later only be are difficult to remove and lead to loss of quality and production interruptions in the spinning mill. The foreign matter on the card's fiber fleece is easy to control from the direction of movement and is embedded in a relatively thin fiber layer.

EP-B 606 626 has already disclosed a device of comparable type in which disruptive particles such as e.g. Nits, shell parts, etc. on the pick-up device are torn out by an air flow directed transversely to the nonwoven fabric. For this purpose, a series of air nozzles is arranged over the entire width, which can be acted upon with compressed air via individual valves.

A similar device is also described in CH-A 689 600. As an alternative, it is also suggested here that the foreign matter is already sucked off on the surface of the take-off roller via a series of nozzles. The detection of foreign substances is also carried out on the take-off roller.

A disadvantage of the known devices is that the tearing out of the foreign matter from the nonwoven is associated with a considerable design effort and that the nonwoven is negatively influenced with regard to uniformity, evenness, etc. Also the anisotropic behavior of the nonwoven Because of the partial rectification of the fibers in the transport direction, problems arise because the fleece tears faster on a line parallel to the transport direction than transversely to the transport direction. It is therefore an object of the invention to provide a device of the type mentioned in the introduction, in which an efficient control of the air flow can be achieved with simpler means, the narrow spatial conditions at the card also being taken into account in particular.

According to a first embodiment of the invention, the object can be achieved with a device which contains the features in claim 1. An essential element here is the guide wall, in which at least one row of suction openings defining a plurality of separation cross sections is arranged over the entire width. Each suction opening is adjacent to a flow channel with a venturi nozzle for generating a suction effect. In this way, the suction effect can be generated with a blast of compressed air, this blast of compressed air simultaneously serving to further transport the foreign matter. The separation cross sections could be defined using the flow orifices described below. In certain cases, however, it would also be conceivable to omit the flow orifices completely, so that the openings on the guide wall are permanently exposed.

In order to prevent the foreign substances from being returned, at least one baffle can be arranged in the flow channel after the Venturi nozzle and after the suction opening. The guide wall can limit the nonwoven fabric at a suitable location on the pickup roller or on the pickup device. The guide wall is particularly advantageously formed by a fleece bridge on the customer device. The guide wall can, however, also be formed by a section above the take-up roll which is curved concentrically to the take-off roll. For reasons of space and in order to create a locally finely graduated separation option, several rows of suction openings can be arranged one behind the other, the suction openings of the individual rows being offset with respect to the width of the guide wall. The suction openings of the individual rows can overlap slightly in the feed direction.

According to a second embodiment of the invention, the object is also achieved with a device which has the features in claim 6. The at least two flow orifices which can be displaced relative to one another and each have an opening make it possible to expose a cross-section of the separation directly on the nonwoven fabric. Depending on the number and arrangement of the openings and depending on the direction of the movement, alternating cross-sections can be exposed over the entire width of the nonwoven fabric. For this purpose, the two openings form a first cross-section in at least a first relative position, wherein a second cross-section can be exposed in at least one second position, which cross-section is arranged offset to the feed direction to the first cross-section. The guide wall, which contains one of the two flow orifices, supports and guides the nonwoven fabric, making it much easier to pull out the foreign matter.

The openings can be intersecting slots, the relative displacement of which leads to a displacement of the cutting cross-section transversely to the feed direction. The separation cross-section is formed by the intersection area. Alternatively, it can also be individual openings that are covered or exposed depending on the relative position. The flow orifices can be arranged above the take-off roll and, if necessary, can be adapted to the roll curvature. However, it is also conceivable to arrange the flow orifices on the customer device, in particular on a fleece bridge. At least one of the flow orifices can be displaced in the feed direction and / or transversely to the feed direction. However, it is also conceivable to mount both flow orifices movably and, if necessary, to move them simultaneously.

A considerable design simplification can be achieved if each separation cross-section is connected to a common flow channel over the entire width of the nonwoven fabric. However, it is also conceivable to combine several separation cross sections into a group, each group being connected to a common flow channel. Several flow channels have to be routed, but they serve several separation cross sections within a group.

The sensor device can act directly on the surface of the nonwoven fabric. These can be sensors that react to different physical parameters. However, these will preferably be light-sensitive sensors which react to certain wavelengths of light. In order to open up difficult-to-access locations for the detection, it is particularly advantageous if the signal transmission from a detection field extending across the width of the fiber fleece to the actual sensor takes place via several optical waveguides. This enables the use of a non-imaging sensor system that does not require complex lens systems. The ends of the optical fibers can be brought very close to the nonwoven fabric and they are relatively insensitive to contamination. The fleece can be illuminated in incident light or in transmitted light. It is conceivable that the fleece or the detection field is also illuminated via optical fibers.

The detection field could easily be arranged in the area of the take-off roller.

Further individual features and advantages of the invention result from the following description of exemplary embodiments and from the drawings. Show it:

FIG. 1: a schematic side view of a card,

FIG. 2: the take-off roller of a card with sensor device and separating device with flow orifices,

FIG. 3: a top view of a first exemplary embodiment of flow orifices,

FIG. 4: a top view of a second exemplary embodiment of flow orifices,

FIG. 5 shows a perspective illustration of a third exemplary embodiment of flow orifices,

FIG. 6: a schematic side view of a doffer with a fleece bridge,

FIG. 7: a top view of the fleece bridge according to FIG. 6, FIG. 8: a perspective representation of a sensor device with optical waveguides on a freely stretched nonwoven fabric,

Figure 9 is a perspective view of a sensor device with optical fibers on a doffer, and

Figure 10: the take-off roller of a card with sensor device and separation device with Venturi nozzles and

Figure 11: a plan view of a guide wall with staggered suction openings.

FIG. 1 shows part of a card 1 in which cotton fibers are fed to a feed device 12 in the feed direction a) in a manner known per se. From there, the fibers reach the drum 13, where they are straightened on fixed carding elements and on the traveling lids 14. The fiber fleece 2 is removed from the doffing roller 3, which runs slower than the drum, and detached from the doffing roller at the doffing device 4. For this purpose, a doctor roll 15 is provided in the exemplary embodiment, which guides the nonwoven fabric onto a nonwoven bridge 17. A pair of pull rollers 16 is provided for removal.

The sensor device 5 and the separating device 6 can optionally be arranged in the peripheral area of the take-off roller 3 or in the area of the take-off device 4. A multiple arrangement of sensor device and separation device on different sections of the feed path would also be conceivable. According to FIG. 2, the separating device 6 consists of two flow orifices 8 and 9 which can be displaced relative to one another. The orifices are curved concentrically to the take-off roller 3 and they each have an opening which exposes a separating cross section 7 in a relative position. The first diaphragm 8 is fixedly arranged, while the second diaphragm 9 lying on it can be displaced in the circumferential direction b). The first screen 8 also forms a guide wall for the nonwoven fabric, or is a component of such.

As will be explained in more detail below, different displacement cross sections, of which at least individual groups open into a common flow channel 18, can be exposed by displacing the two diaphragms relative to one another over the width of the nonwoven fabric. The foreign matter is torn out of the nonwoven fabric and transported away via this flow channel.

According to FIG. 3, two rows of three first openings 10a, 10b, 10c and 10d, 10e, 10f are arranged offset from one another in the first flow orifice 8 at an angle of approximately 45 ° to the feed direction. In the second flow orifice 9, two parallel rows of second openings 11a, 11b, 11c and lld, lle, llf are likewise arranged at an angle of approximately 90 ° to the feed direction. In the position shown relative to each other, all openings 10a to 10f are covered, so that no cut-out cross section is exposed.

If the second flow orifice 9 is displaced in the direction of arrow c by the distance e, the opening 11a corresponds to the opening 10a below it, the corresponding separating cross section being exposed. However, all other openings in the first flow orifice 8 remain covered. At a Movement in the direction of arrow c by the distance f corresponds to the opening 11b with the opening 10b underneath, while likewise all other openings remain covered. With a displacement in the opposite direction d by the corresponding distances, the openings 10d, 10e or 10f can be exposed in the same way.

The flow orifices are shifted relative to one another for the selective exposure of the desired cross-section of the separation via a drive device, not shown here, e.g. via an electric motor. This drive device is controlled via a control device as a function of the position and the feed rate of the foreign substance determined by the sensor device.

The shift does not necessarily have to be in the feed direction. Movements transverse to the feed direction are also conceivable.

In the exemplary embodiment according to FIG. 4, only a single opening 10 or 11 is arranged in the first flow orifice 8 and in the second flow orifice 9. However, the openings have the shape of intersecting slits, a diamond-like separation cross section 7 being exposed in the intersection area. If the second flow orifice 9 is displaced in the direction of arrow c up to the new position 11 ^Λ shown in dash-dotted lines, the separating cross section 7 ^{obviously also} shifts along the axis of the first opening 10 by the lateral distance g. In this way, a practically stepless displacement of the separating cross section 7 is possible.

The exemplary embodiment according to FIG. 5 differs from that according to FIG. 4 in that the slot-shaped opening 10 in the first flow orifice 8 is parallel to the central axis the take-off roller 3 extends. The slot-shaped opening 11 in the second flow orifice 9, on the other hand, runs at a certain angle to the central axis or to the opening 10. In this arrangement, a displacement of the two flow orifices relative to one another also causes a displacement of the separating cross section 7 parallel to the central axis of the take-off roller 3.

In the exemplary embodiment according to FIG. 6, the nonwoven fabric 2 is removed by a doctor roller 15 from the take-off roller 3 and transferred to a nonwoven bridge which is formed by a guide wall 19. As can be seen from FIG. 7, a plurality of suction openings 20 are arranged in the guide wall, each of which opens into an underlying flow channel 18. A blast of compressed air can be conducted through this flow channel in the direction of flow h. In relation to the direction of flow, a Venturi tube or a Venturi nozzle 21 is arranged directly in front of each opening 20. Obviously, this causes an increase in the flow velocity and a pressure drop at the narrowest cross section, which can be determined using the Bernoulli equation. By means of this suction effect, the detected point of the carding fleece is sucked into the flow channel 18 and fed to a collecting container 27. Baffles 22 prevent the foreign substances from being returned. The compressed air blasts are controlled by a sensor device, not shown here, which can be arranged in the area of the take-off roller or in the area of the fleece bridge.

FIGS. 8 and 9 show possibilities for optical detection on the nonwoven fabric 2 in the stretched state or also on the take-off roller 3 with the aid of optical waveguides 25. The individual conductors are brought very close to the surface of the nonwoven fabric to be detected. This makes it possible to move the sensor 23 or the individual sensors relatively far away from the detection 24 to arrange. As shown in FIG. 9, the lighting can also take place via the individual optical fibers or via optical fibers guided in parallel. Illumination of the detection field is also possible in transmitted light, as shown in FIG. 8. The use of optical fibers in devices of comparable generic type has already become known through Uhlmann Jürg, "Detection of Foreign Substances in Raw Cotton", Diss. ETH Zurich, 1996.

FIG. 10 shows an embodiment of an invention with a function similar to that according to FIG. 6. The guide wall 19 is designed here as a section which is curved concentrically to the center of the take-off roller 3. Of course, the guide wall could also extend over a larger sector of the take-off roller and the suction openings 20 could also be arranged elsewhere, e.g. near the fleece bridge 17. Here, too, the venturi nozzles 21 are arranged in the flow channel 18 directly in front of the suction openings 20, the baffles 22 preventing the foreign substances from being returned.

As shown in FIG. 11, a plurality of rows of suction openings 20a, 20b and 20c could be arranged one after the other, the suction openings of the individual rows being offset relative to the width of the guide wall 19. Depending on the given pressure conditions, it would be entirely possible for a group of suction openings to be arranged in the area of influence of a common Venturi nozzle, that is to say that a single flow channel 18 serves a group of suction openings.

Claims

claims

1. Device for recognizing and separating foreign matter on a non-woven fabric (2) formed by a card (1) with a pickup roller (3) and with a pickup device (4), a sensor device (5) for recognizing the foreign matter and one in the feed direction of the Fiber fleece arranged after the sensor device separating device (6), which means for selectively pulling the foreign matter out of the fiber fleece through a, on a separating cross-section

(7) has limited air stream, characterized in that the separating device comprises at least a baffle (19) for the fiber fleece (2) in which all over the width of at least one row of a plurality of separation cross sections defining ^'suction openings (20) is arranged and that each Suction opening to a flow channel with a venturi nozzle

(21) adjacent to produce a suction effect.

2. Device according to claim 1, characterized in that in the flow channel after the venturi nozzle and after the suction opening at least one chicane (22) is arranged to prevent the foreign substances from being returned.

3. Device according to claim 1 or 2, characterized in that the guide wall is formed by a fleece bridge on the customer device.

4. The device according to claim 1 or 2, characterized in that the guide wall is formed by a section concentrically curved to the take-off roller above the take-off roller.

5. Device according to one of claims 1 to 4, characterized in that several rows of suction openings behind are arranged to each other and that the suction openings of the individual rows are arranged offset to one another with respect to the width of the guide wall.

6. Device for recognizing and separating foreign matter on a nonwoven fabric (2) formed by a card (1) with a pickup roller (3) and with a pickup device (4), a sensor device (5) for recognizing the foreign matter and one in the feed direction of the Fiber fleece arranged after the sensor device separating device (6), which has means for selectively pulling the foreign matter out of the fleece by an air flow limited to a separating cross-section (7), characterized in that the separating device (6) has at least two flow orifices (8) which can be displaced relative to one another , 9), each of which contains at least one opening (10, 11), the two openings forming the separating cross section (7) in at least one relative position and the one flow orifice being arranged in a guide wall for the nonwoven fabric.

7. The device according to claim 6, characterized in that the two openings (10, 11) form a first cross-section in at least a first relative position, and that in a second relative position a second cross-section can be exposed, which is offset transversely to the feed direction to the first cross-section is arranged.

8. The device according to claim 6 or 7, characterized in that the flow orifices (8, 9) above the take-off roller (3) are arranged.

9. The device according to claim 6 or 7, characterized in that the flow orifices on the customer device (4), in particular on a fleece bridge (17) are arranged.

10. Device according to one of claims 6 to 9, characterized in that at least one flow orifice is displaceable in the feed direction and / or transversely to the feed direction.

11. The device according to one of claims 6 to 10, characterized in that each separation cross-section is connected to a common flow channel over the entire width of the nonwoven fabric.

12. Device according to one of claims 6 to 10, characterized in that a plurality of separation cross-sections are combined into groups over the entire width of the nonwoven fabric and that each group is connected to a common flow channel.

13. Device according to one of claims 1 to 12, characterized in that the sensor device contains at least one - light-sensitive sensor for detecting the foreign matter in the nonwoven fabric and that the signal transmission from a detection field (24) extending over the width of the nonwoven fabric to the sensor (23rd ) over several optical fibers (25).

14. The apparatus according to claim 13, characterized in that the detection field (24) is illuminated via optical fibers.

5. Device according to one of claims 13 or 14, characterized in that the detection field (24) is arranged on the take-off roller (3).