EP1715093B1 - Method for controlling the lay down of a web during the formation of a fleece and apparatus for making the same. - Google Patents

Abstract

Method for controlling the nap deposition during the production of a fibrous fleece comprises measuring the thickness of the nap deposit in relation to a moving plaiting site (8) of a plaiting device (1) before deposition of a further nap deposit and controlling the deposition of the next nap deposit depending on the measuring result. An independent claim is also included for a device for producing a fleece.

Description

Field of the invention

The present invention relates to the production of a nonwoven fabric by crossing a card web.

Background of the invention

It is known to make a fibrous web from a carded or carded batt by means of a batt layerer, also known as a crosslapper, which is then fed to a needling machine to be felted. In the nonwoven layer, the card web is laid in a zigzag shape in partially overlapping layers on a delivery conveyor belt in order to obtain a nonwoven web which has a multiple of the thickness of the card web from which it has been produced. The quality of the nonwoven web, especially its uniformity, depends not only on the laying process, but also on the quality of the card web, which is fed to the fleece layer.

Description of the Prior Art

In this context, it is off DE 1 287 980 C It is known to measure the thickness of the nonwoven web leaving the nonwoven web or its grammage along its longitudinal extent. The measurement result reaches a processor which, in the event of a deviation of the measurement result from a predetermined desired value, influences the speed of the feed belt delivering the web to the web laying machine, for example if an incorrect overlay of the individual web layers leads to transverse thickenings or thin spots in the nonwoven web. In the event of a deviation of the thickness of the mat from a predetermined reference value, the speed of the pick-up on the carding machine which supplies the pile to the mat-laying machine is changed.

Out EP 0 315 930 A For example, a nonwoven layering machine is known, with the aid of which the desired nonwoven web can be given a desired transverse profile, in particular in order to compensate for edge thickening in a product needled from the nonwoven web. For this purpose will be stretched within the nonwoven layer of the pile before depositing on the delivery conveyor belt in the end region of the reciprocating laying movements of the laying member of the nonwoven layer.

However, the literature reports that it is difficult to give the nonwoven web leaving the nonwoven layer such a non-uniform profile that the defects produced in the subsequent needling process are fully compensated in advance. In practice, perfect precompensation is very difficult to achieve because it requires many laborious adjustments. Moreover, it is not guaranteed that a good initial setting will give equally good results for a long time, since the properties of the pile are in many respects related to the raw material fed to the card, i. its condition, compaction, humidity, etc., depend.

From the US 6,434,795 A method and apparatus embodying the starting point of the present invention has become known in which a physical size of the web is measured at a measurement station and the profile of the web corrected on the basis of the measurement result by an operating parameter from at least one fiber processing unit located upstream of the measurement station is arranged is set. For this purpose, the physical size is measured at a plurality of points distributed transversely to the longitudinal extent of the nonwoven at the measuring station in order to record a cross-sectional profile of the nonwoven. In the case of a discrepancy between the measured profile and a reference profile, the said operating parameter is corrected during the processing of the fibers. This fiber processing unit is one which, for example, belongs to a carding machine or a cross-stacker and has an influence on the arrangement or distribution of the fibers in the nonwoven.

A disadvantage of this procedure is that the cross-sectional profile of the finished nonwoven fabric is measured, in the method described in said document even behind the needle machine and thus indirectly on the felt produced from the web, with the result that between the location of detection a deviation and the location of the correction of the deviation is a considerable fleece or even felt track length is present in which the work result is not optimal. The known procedure is then only suitable for the correction of "long-wave" deviations of the cross-sectional profile of the desired profile and determined.

In practice, however, it happens that a fibrous web leaving the carding machine has irregularities which can occur at irregular intervals. Such irregularities can result from irregularities in the feeding of the fibers into the card, which can not fully compensate for the carding. For example, filling fluctuations in the filling shaft of the carding machine have an influence on the basis weight of the web. Such "short-wave" fluctuations in the basis weight of the card web leaving the carding can not be compensated for by the aforementioned known method.

Overview of the invention

The invention is based on the object of specifying a method and a device with which a predetermined cross-sectional profile of a non-woven fabric laid from a card web can be achieved with high accuracy.

The present invention is based on a method for controlling the pile support in the production of a nonwoven fabric with a nonwoven fabric, which is fed to a card web, which is stored in a zigzag shape by the laying member in partially overlapping layers on a delivery conveyor belt moved transversely to its feed direction. wherein the thickness of the product of the pile tray is measured at a plurality of locations distributed transversely to the direction of movement of the delivery conveyor belt and derived from the measurement results by comparison with a target value, a manipulated variable with which the local pile storage in order to achieve a predetermined, seen transversely to the direction of movement of the Abliefertransportbandes profile of laid fleece is influenced. The above object is achieved according to the invention in that the thickness of the product of the pile tray is measured locally in close proximity to a moving laying point of the laying member before the storage of another pile layer and depending on the measurement result the immediately following storage of the next pile layer by action is controlled on the laying body.

With a device for producing a nonwoven, comprising a nonwoven layerer with a movable laying member transversely to a movement direction of a delivery conveyor belt, which defines a laying point for depositing a card web fed to the nonwoven fabric on the delivery conveyor belt, a measuring device for determining the thickness profile of one with the help of the nonwoven layer product and one with the The device underlying the invention is achieved in that the laying member at least two measuring devices are assigned, which are adapted to the thickness of the product of the pile tray locally immediately before each of the measuring device connected to the effect on the pile storage Tray to measure another pile layer, and that the means for acting on the pile tray is adapted to act on the laying member in the sense of stretching or compression of the supplied card web.

In contrast to that US Pat. No. 6,434,759 B1 In the present invention, known processes do not measure the finished nonwoven fabric or even the felt produced therefrom, but rather measure an only partially finished product before the last pile layer is deposited, so that it is possible to measure deviations from a desired value immediately after to compensate for the detection of these deviations by acting on the subsequent pile storage directly on the laying body by stretching the laying member in the area of the laying site the pile as needed or can be compressed. This achieves better work results, in which all errors are completely compensated in the ideal case, without length sections caused by the length of the controlled system being present, in which the compensation is not yet effective.

Since in practice a laid nonwoven fabric consists of a plurality, for example ten, pile layers, which are superimposed on one another, control action already takes place during the construction of the individual layers as a result of the invention, which enables early compensation of defects.

According to a particularly advantageous embodiment of the invention, the thickness of the laid product is measured immediately behind the laying point. If, due to a disturbance in the fed pile, which can not detect the upstream of the jig arranged measuring device, from the downstream of the jig measuring device a deviation from the set value is determined, can immediately intervene in the laying process by, depending on the sign of the deviation, by means of the laying member according to more or less Flor is supplied. The invention thus provides a total of a very short control path, with which one is able to compensate not only the aforementioned "long-wave" deviations of the cross-sectional profile of nominal values, but also "short-wave" deviations.

By "cross-sectional profile" is not necessarily meant here that the cross-sectional profile at the edges of the laid web should be thinner than in the middle, as in the already mentioned EP 0 315 930 A , Even cross-sectional profiles fall under this definition.

It is advantageous if the distance between the measuring points and the location is changed as a function of the speed of movement of the laying member, because in this way the time constants to which the processing of the measurement results is subject can be taken into account in a very simple manner.

For detection of the thickness of the laid product come by radiation method with X-rays, RF, ultrasound or β-rays into consideration, which in addition to the product placed optionally also masking tapes are irradiated, which only makes it necessary to provide a constant base value of thickness in the Evaluation to take into account. The receiver or receivers may be arranged below the delivery conveyor belt and be moved with the laying member, or it works with a reflection method in which there is a reflector under the delivery conveyor belt and each radiation transmitter is assigned a radiation receiver on the side of the transmitter. Alternatively, one can also work with capacitive sensors, since different thicknesses of the product placed have different dielectric properties, which can be detected metrologically.

An essential feature of the invention is that the influence of the measurement result on the card web to be deposited takes place directly at the nip, i. that there the card web is stretched or compressed, as needed, and not before the entry into the nonwoven or within the nonwoven layer at a location that is located at a greater distance in front of the laying site.

The invention will be explained in more detail below with reference to the drawings on a schematically illustrated embodiment of a nonwoven layer.

Brief description of the drawings

• Fig. 1 eine schematische stirnseitige Ansicht des Legeorgans eines Steilarm-Vlieslegers im Bereich der Legestelle über einem Abliefertransportband, und
• Fig. 2 eine schematische Draufsicht auf die Legestelle und die den Vliesleger verlassende Vliesbahn.

In the accompanying drawings:

• Fig. 1 is a schematic frontal view of the laying member of a steep-arm-fleece layer in Area of laying over a despatch conveyor, and
• Fig. 2 is a schematic plan view of the laying point and the nonwoven web leaving the nonwoven layer.

Detailed Description of the Preferred Embodiment

Fig. 1 shows a schematic representation of an end view of a nonwoven layer in the same laying position. The nonwoven is executed in the example shown as Steilarmleger and shows him only the laying area at the lower end of the laying arm 1, which forms the laying member. The lower end of the laying arm 1 is movable back and forth across an endless circulating delivery conveyor belt 2 transversely to its direction of movement. The delivery conveyor belt 2 runs over a plurality of deflection and support rollers, which are not shown in FIG. 1 for reasons of clarity.

At the lower end of the laying arm 1, two rollers 3 forming a first pair of rollers are rotatably mounted, which are each surrounded by a feed belt 4, which are closely adjacent to one another in their sections running towards the lower end of the laying arm 1 and clamp a card web 5 between them in Fig. 1 as a thick line, partially dashed, is shown. In close proximity to the rollers 3 of the first pair of rollers are the rollers 6 of a second pair of rollers. The rollers 6 are each wrapped by a cover strip 7, the lower strands extend over the delivery conveyor belt 2 and serve to cover the filed by the laying arm 1 on the delivery conveyor belt 2 pile layers. The rollers 3 and 6 of each pair each have such a small distance to each other that the card web 5 is clamped between them. The gap between the rollers 6 of the second pair of rollers determines a denomination designated 8, at which the pile 5 is discharged to be deposited on the delivery conveyor belt 2. In practice, the two roller pairs 3 and 6 are mounted on a common laying carriage 9, which is movable on rails (not shown here) transversely to the longitudinal extent of the delivery conveyor belt 2 back and forth.

The laying point 8 adjacent to both sides of the same radiation transmitting devices 10, which are respectively attached to the first slide carriage 11. The first displacement slide 11 are mounted in the laying carriage 9 and therefore moved together with the laying point 8 back and forth on the delivery conveyor belt 2. Every first sliding carriage 11 has a drive 12, with the aid of the distance of the relevant radiation transmitting device 10 is adjustable to the laying point 8.

Below the upper run of the delivery conveyor belt 2, on which the card web 5 is deposited, there are radiation receiving devices 13, which are reciprocable in synchronism with the movement of the beam transmitting devices 10. This is illustrated in the drawing by a toothed belt 14, which runs around a drive gear 15 which is drivable by a motor 16 (see FIG. 2) in alternating directions of rotation. The radiation receiving devices 13 are attached to the toothed belt 14 respectively by means of a second sliding carriage 17 with associated drive means 18, so that their position along the toothed belt 14 in accordance with a displacement of the beam transmitting devices 10 can be adjusted.

The laying carriage 9 is connected to a drive device which generates its movement over the delivery conveyor belt 2. The drive it sledge 9 can be done by means of two acting on a cover strip 7 drive rollers, which are driven at different peripheral speeds, as shown symbolically in the drawing by the black / white rauted guide rollers 19. The difference in the peripheral speeds of the driven deflection rollers 19 determines the speed of movement of the squeegee 9, while the absolute speed level of the driven guide rollers determines the speed at which the lower run of a cover strip 7 moves over the deposited pile layers. The masking tapes 7 have in each case at the deflecting them on the laying carriage 9 rollers 6 a rotational speed to produce at the gap between the rollers 6 of the second pair of rollers, a peripheral speed, which conveys the card web 5 from the gap between the rollers 6 and on the Abliefertransportband 2 or the already stored thereon piles deposits.

The drive of the cover strips 7 is independent of the drive of the feed belts 4 controllable. It is therefore possible to impart to the rollers 6 of the second pair of rollers a deviating from the rollers 3 of the first pair of rollers peripheral speed to stretch the card web 5 in the region between the two pairs of rollers 3 and 6 or to compress.

The distance between the radiation transmitting devices 10 and the laying point 8 is preferably adjustable, for which purpose the first displacement slides 11 are provided. It is open This way it is possible to give the transmitting device 10 located in front in the direction of movement of the laying point 8 a greater distance to the laying point 8 than the transmitting device 10 located behind the laying point. In this way the time constants of the electrical switching devices receiving the signals from the receiving devices can be determined 13 received, take into account. Moves the landing spot 8 faster, the distance is to increase, it moves slower, it is to reduce. In practice, the movement of the laying point 8 is never uniform because it must be slowed down to zero when approaching the laying point 8 to the reversal points of the laying movement and then has to be accelerated again. It is understood that the radiation receiving means 13 must be moved accordingly, so that the radiation emitted by the radiation transmitting devices 10 beams can be recorded. Therefore, they are also along the toothed belt 14 relative to this adjustable.

Fig. 2 is only the rounding of the sitter. It shows the result of the laying operation in the form of zigzag-shaped superimposed layers of the card web 5 after leaving the laying area on the supporting delivery conveyor belt 2. Furthermore, it can be seen that the radiation receiving devices 13 are in the area of the laying site, i. where the nonwoven web is produced, not outside of it, as in the prior art.

In alternative embodiments, it is possible to dispense with the receiving device which can be moved below the laid product if a reflector arrangement is provided there instead and assigns corresponding radiation receiving devices to the beam transmitters 10 on the same side of the laid product. The laid product must then pass through the beams twice, which increases the sensitivity and at the same time reduces the effort, because there must be no moving parts under the delivery conveyor.

The transmitting devices may be β-ray transmitters, X-ray transmitters, ultrasonic transmitters or RF transmitters, and the receiving devices are adapted to the physics of the transmitting devices, respectively. Alternatively, one can work with capacitive devices.

It is understood that all belonging to the measuring devices elements and all drives are connected to a control device that not only the movement of the Laying organ controls 1, but also controls the drives 11, 16, 17 and 19, which are required to correct deviations from the thickness setpoint of the product from the measurement results. This control device and the necessary connecting lines are not shown in the drawing for reasons of clarity.

Claims (22)

1. A method of controlling the deposition of the non-woven when manufacturing a fibre fleece by means of a cross lapper to which a non-woven web is supplied which is deposited by a layering member in zigzag in layers partially overlapping one another onto an output conveyor belt which is moved transversely to the feed direction of said web, wherein the thickness of the product of the deposition of the non-woven is measured at a plurality of locations distributed transversely to the movement direction of the output conveyor belt and a correcting variable is derived from a comparison of each of the measurement results with a respective target value, the local deposition of the non-woven being influenced by said correcting variable to attain a predetermined profile of said layered fleece when seen transversely to the movement direction of said output conveyor belt, characterized in that the thickness of the product of said non-woven deposition is measured locally in close neighbourhood to a moved layering position of the layering member prior to depositing another non-woven layer, and dependent on the measuring result the immediately following deposition of the next non-woven layer is controlled by influence onto the layering member.
2. The method of claim 1, characterized in that continuously immediately after depositing a non-woven layer the thickness of the product is measured downstream of the layering position and the results of these measurements are taken into consideration as well when depositing the subsequent non-woven layers.
3. The method of claim 1 or 2, characterized in that the measuring location(s) is/are moved along with the layering member depositing the non-woven.
4. The method of claim 3, characterized in that in operation the distance between the measuring location and the layering position is changed dependent on the velocity of the movement of the layering position.
5. The method of claim 4, characterized in that in operation the distance between the measuring location and the layering position is changed dependent on the direction of the movement of the layering position.
6. The method of one of claims 1 to 3, characterized in that the thickness of the product of the non-woven deposition is measured at a plurality of locations distributed transversely to the non-woven web to be layered and already layered, respectively.
7. The method of one of the preceding claims, characterized in that the thickness of the product is measured utilizing rays directed through the product.
8. The method of claim 7, characterized in that the measurement is made employing the reflection method in which the rays having traversed the layered product twice are received on the same side on which they have been transmitted.
9. The method of one of claims 1 to 6, characterized in that the thickness of the product is determined by capacitance measuring means.
10. The method of one of the preceding claims, characterized in that for influencing the thickness of the non-woven to be layered the non-woven is stretched or upset upon the discharge from the layering member in the region of the layering position.
11. An apparatus for manufacturing a fleece, comprising a cross lapper having a layering member (1) which is movable above an output conveyor belt (2) transversely to the movement direction of the latter, said layering member (1) defining a layering position (8) on the output conveyor belt (2) for layering a non-woven web (5) supplied to the cross lapper, a measuring device (10, 13) for determining the thickness profile of a product manufactured by means of the cross lapper, and an installation connected to the measuring device (10, 13) for influencing the deposition of the non-woven in a manner to influence the thickness profile, characterized in that at least two measuring devices (10, 13) are assigned to the layering member (1), which are adapted to detect the thickness of the product of the non-woven deposition locally in the region of the layering position (8) immediately before the deposition of another non-woven layer, and that the installation for influencing the non-woven deposition are adapted to influence the layering member (1) in a manner to stretch or upset the supplied non-woven web (5).
12. The apparatus of claim 11, characterized in that the layering member (1) comprises two closely spaced roller pairs (3, 6) in the region of the layering position (8), said roller pairs defining a first and a second roller nip through which the non-woven web (5) to be layered is passed and to each of which a driving means is assigned adapted to vary the circumferential speeds of the roller pairs (3, 6) with respect to one another dependent on the measuring results of the thickness measuring device (10, 13).
13. The apparatus of claim 12, characterized in that the rollers of the first roller pair (3) are wrapped by two feed belts (4) for supplying the non-woven web (5) to the layering position (8).
14. The apparatus of claim 12 or 13, characterized in that the rollers of the second roller pair (6) are wrapped by two covering belts (7), sections thereof disposed adjacent to the output conveyor belt (2) extending transversely to the output conveyor belt (2) in close distance thereto.
15. The apparatus of one of claims 11 to 14, characterized in that two radiation transmitter means (10) are attached to the layering member (1) at both sides thereof, and below the output conveyor belt (2) a radiation receiver means (13) is disposed opposite to each radiation transmitter means (10), said radiation receiver means (13) being attached at a support (17) which is movable together with the layering member (1) transversely to the movement direction of the output conveyor belt (2).
16. The apparatus of claim 15, characterized in that the positions of radiation transmitter and radiation receiver are exchanged with respect to one another.
17. The apparatus of one of claims 11 to 14, characterized in that at least two radiation transmitter means and at least two radiation receiver means are attached at the layering member (1) on either side of the layering position, and a reflector means is disposed below the output conveyor belt for reflecting the radiation impinging on said reflector means onto the radiation receiver means.
18. The apparatus of one of claims 14 to 17, characterized in that the radiation transmitter means (9) are one of the following types: β radiation transmitter, X-ray transmitter, radio transmitter, ultrasonic transmitter.
19. The apparatus of one of claims 11 to 14, characterized in that the measuring means comprise capacitively responsive sensors.
20. The apparatus of one of claims 16 to 19, characterized in that the radiation transmitter means (10) and the radiation receiver means (13) and the sensors, respectively, are displaceably mounted to the layering member (1) and are each connected to an adjustment drive (12, 18) which is adapted to vary the distance between the radiation transmitter means (10) and the radiation receiver means (13) and between the sensor and the layering position (8), respectively.
21. The apparatus of one of claims 16 to 19, characterized in that the radiation receiver means (13) are mounted to a carrier (14) which is movable in synchronism with the layering member (1), said radiation receiver means (13) being displaceable in the movement direction of said carrier (14) with respect to same by means of driving means (18).
22. The apparatus of one of claims 11 to 20, characterized in that a plurality of radiation transmitters (10) and sensors, respectively, are disposed in mutual spacing on respective lines extending in parallel to the layering position (8) on either sides thereof.

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