EP3650595B1 - Compensation device - Google Patents

Description

The present invention relates to a compensation device and a method for compensating for fluctuating conveying speeds of a material web, in particular a fibrous web or nonwoven web.

For the production of multi-layer nonwovens, corresponding material webs pass through a plurality of work stations arranged in series. A fiber flock web is fed to a carding machine, which is broken up down to individual fibers and output as an unconsolidated textile fiber web on the outlet side. In a non-woven layer, the fibrous web is laid on a discharge belt in a predetermined laying width in several layers. For example, a laying carriage is moved back and forth across the discharge direction of the discharge belt, while the discharge belt moves in the discharge direction. Due to the fluctuating movement of the laying carriage and the associated acceleration and braking processes, the outfeed belt must be moved synchronously in order to ensure the formation of a uniform fleece web. The nonwoven web is then consolidated in a needle machine, for example. The solidification of the nonwoven web usually takes place at a constant conveying speed of the nonwoven web.

It may therefore be necessary at several points during the web production process, in particular between the web layer and the consolidation device, to transfer the material web present at the respective point in time from a variable conveying speed to a constant conveying speed or vice versa. For this purpose, compensation devices can be provided along the conveying path of the respective material web, as they are, for example, from the EP 2 175 056 A1 , the WO 2014/037503 A1 and the EP 1 643 022 A1 are known.

The compensation devices disclosed therein have an endless, revolvingly driven storage belt with two deflection rollers. The nonwoven web is arranged on the upper run of the storage belt and is temporarily stored in a variable slack of the upper run if necessary. This makes it possible to compensate for differences in speed of the material web at the inlet of the compensating device and at the outlet of the compensating device, that is to say, for example, between a fleece layer and a needle loom. The size of the slack and the resulting fleece store is determined by the speed differences. Since the outlet of the compensating device is assigned to the inlet of the needle loom, the material web is moved there at a constant speed. The entry-side speed of the material web results from the exit speed of the same from the non-woven layer and varies according to the speed of the exit belt. If the input speed is now greater than the constant output speed, the length of the material web to be temporarily stored in the compensation device increases. If the input speed is lower than the output speed at another point in time, the length of the material web to be stored is reduced again. This can be achieved by increasing or decreasing the slack of the storage belt in accordance with the length of the material web to be stored, that is, as a function of the speed difference.

A disadvantage of such compensating devices is that at high conveying speeds the storage belt can vibrate in the area of the variable sag. These vibrations can be excited, for example, by the alternating acceleration and deceleration when changing the running-in speed. The oscillation amplitude of these oscillations can take on dimensions which lead to the material structure in the material web being unintentionally negatively influenced. The conveyed material web can also be caused to oscillate or vibrate, the material web can partially lift off the storage belt and its fibers or layers can be swirled.

It is therefore the object of the present invention to provide a device and a method which enable the compensation of fluctuating speed differences in the web production process and at the same time ensure a high quality of the web.

This object is achieved by the features of claims 1 and 12, respectively. Advantageous refinements are the subject of the dependent subclaims.

According to the invention, a compensation device for compensating for fluctuating conveying speeds of a material web, in particular a fibrous pile or nonwoven web, comprises an endlessly circulating storage belt for conveying the material web in one Conveying direction through the compensation device, wherein the storage belt has a variable slack and is guided over two deflection rollers which are arranged at a distance from one another in the conveying direction, the variable slack of the storage belt being arranged at least between the two deflection rollers. The compensation device is characterized in that it further comprises a damping device which is arranged in the region of the variable sag at a distance from the storage tape that is smaller than the oscillation amplitude of the expected vibrations of the storage tape in the region of the variable sag.

In this way it is achieved that occurring vibrations of the storage belt can be dampened or completely prevented, whereby negative effects on the quality of the conveyed material web are avoided. Vibrations that build up are dampened as soon as their vibration amplitude is greater than or equal to the distance between the damping device and the storage tape. The energy required for the oscillation is lost to the storage tape when it hits the damping device, which prevents the storage tape from oscillating. In the vibration-free state, e.g. at slow conveyor speeds of up to 10 m / min, the damping device is arranged at a distance from the storage belt and therefore does not cause any friction losses.

The expected vibrations of the storage tape in the area of the variable sag can be determined both mathematically and experimentally. The vibrations are largely determined by the excitation of the storage belt and the vibration properties of the storage belt, in particular its material, dimensions and the free length of the storage belt between the deflection rollers. The material web conveyed on the storage belt also affects the vibration properties of the storage belt.

The expected oscillations of the storage tape can therefore be determined individually for each compensation device. It may be desirable to dampen vibrations with very small vibration amplitudes that are essentially noticeable as vibrations in the storage belt. It can also be desired to dampen only vibrations of larger vibration amplitudes for which negative influences on the material structure of the material web are known. Correspondingly, the distance between the damping device and the storage tape can be less than 1 mm, but also several centimeters be. The vibration states that are to be expected and / or must be avoided must be specified by the user and are also referred to below as critical vibrations.

In order to ensure the highest possible quality of the material webs, the distance between the damping device and the storage belt is preferably less than 5 cm, more preferably less than 2 cm, even more preferably less than 1 cm or less than 5 mm.

It goes without saying that, especially with distances between the damping device and the storage tape in the range of a few millimeters, contact between the damping device and the storage tape can occur in sections even if there are no major vibrations.

In a preferred embodiment of the compensation device, the storage belt comprises an upper run and a lower run, and the variable sag is formed at least in the upper run of the storage belt. The damping device is accordingly arranged at least in the region of the variable sag of the upper run of the storage belt. The material web is arranged on the upper run of the storage belt and is conveyed from the upper run through the compensation device. Accordingly, the variable sag of the upper run is decisive for the storage of the material web and the compensation of the occurring speed fluctuations of the material web. Vibrations in the upper run have a direct effect on the guidance and quality of the material web and can be specifically prevented in this way.

In order to make the damping device structurally simple, the damping device can preferably be arranged in a stationary manner. A stationary damping device can be formed, for example, by a flat or curved sheet metal that is supported in the area of the variable sag. Such a plate extends at least in sections along the storage tape in a certain state of the storage tape. If the sheet metal is curved, the curvature is adapted as far as possible to the sag of the storage belt in the respective state and is preferably arranged in the region of the apex of the sag. Instead of flat elements, such as a sheet metal, rods or bars with an essentially round or rectangular cross-section can also be provided, which extend linearly or in a curved manner along at least a section of the storage belt and a plurality of which are preferably arranged next to one another in the transverse direction of the storage tape. Alternatively, a stationary damping device can also be formed by an airbag made of textile fabric or plastic, which is connected to a compressed air source.

However, the damping device can also be designed in such a way that it can be carried along at least in sections with the variable sag of the storage tape, whereby the damping device can be adapted to different vibration states or different vibration amplitudes to be avoided with the greatest possible flexibility. Sheets or rod-shaped damping elements, as described above, can be designed to be flexible for this purpose and be supported and clamped in such a way that their deflection can be changed in accordance with the variation in the sag. It is also possible to provide stiff (sheet-metal or rod-shaped) elements that are moved linearly with the slack or that are pivotably mounted in order to follow the slack. Curved rigid elements can also be moved along with the slack, even if their contour is then no longer fully adapted to that of the slack, as long as at least areas of the elements are arranged so close to the storage belt that vibrations that occur are damped. An airbag can be designed, for example, by changing the volume of air it contains or by shifting the entire airbag in such a way that it can be carried along with the slack of the storage tape.

It can be the case that particularly critical vibrations only occur in certain states of the storage tape or the variable sag of the storage tape and only these vibrations need to be dampened in a targeted manner. A stationary damping device, which is arranged in the region of the variable sag in which the critical vibrations occur, would be sufficient in this case. For example, critical vibrations can occur when a maximum sag of the storage belt is reached and the free length of the storage belt between the two deflection rollers assumes the greatest possible length.

However, it can also be the case that, due to the vibration properties of the storage tape, a critical state is reached between the minimum and the maximum sag of the storage tape. The damping device can then be arranged in a stationary manner in the corresponding area or at least in sections it can be carried along with the storage tape become. The damping device can also be carried along with the storage tape over the entire path between the minimum and maximum sag of the storage tape, in order to enable vibrations which occur to be damped in all intermediate states. The distance between the damping device and the storage tape can in this case be constant or preferably vary as a function of the vibration amplitudes to be expected.

The compensation device can, however, also have one or more sensors which detect the occurrence of vibrations in the storage tape. The damping device can be controlled by means of a control device in such a way that it approaches the storage tape as soon as the sensors detect the occurrence of vibrations. A predetermined limit value can also be stored in the control device, e.g. a value of an oscillation amplitude, and the control device only causes the damping device to intervene as soon as the vibrations that occur exceed this limit value. Such a sensor can be a contactless sensor (e.g. a light barrier or laser sensor) or a pressure sensor. Further alternatives are apparent to the person skilled in the art.

The damping device is preferably arranged essentially parallel to the storage tape. This means that the contour of the damping device essentially follows the contour of the variable sag of the storage tape. The distance between the damping device and the storage tape can also vary slightly and deviate from an exactly parallel course, which is due in particular to the mounting of the damping device.

In a preferred embodiment, the damping device is arranged in the interior of a loop formed by the circulating storage belt. This enables a space-saving construction of the compensation device. In addition, damping devices can thereby be used which dampen both the upper run and the lower run of the storage belt and do not hinder the variable slack of the storage belt.

The damping device is preferably a passive damping device, as a result of which a mechanically and control-technically simple structure is achieved. In contrast to one active damping device, the passive damping device does not actively counteract vibrations that occur, for example by generating counter-vibrations. Rather, vibrations that occur are prevented by taking away the energy they need to vibrate.

The variable sag is particularly preferably formed in an upper run and a lower run of the storage belt and the damping device is arranged both in the region of the variable sag of the upper run and in the region of the variable sag of the lower run. The variable sag of the lower run varies in the opposite direction to the variable sag of the upper run in order to enable the corresponding increase or decrease of the variable sag of the upper run with a constant length of the endless storage belt. Since the lower run does not convey the material web, vibrations of the lower run do not have a direct effect on the material web and are therefore to be regarded as less critical. Nevertheless, it may be desirable to also suppress vibrations in the lower run of the storage belt, for example to avoid air turbulence which acts on the transported material web through the gaps between the slats of the upper run of the storage belt. Correspondingly, the damping device is then also arranged in the region of the variable sag of the lower run at a distance from the storage belt which is smaller than the oscillation amplitude of the oscillations of the lower run to be expected.

In a preferred embodiment, the damping device comprises at least one damping element which is flexible and extends between the two deflection rollers. Due to the flexibility of the at least one damping element, its shape can be easily adapted, at least in sections, to the variable sag of the storage tape. The at least one damping element can be assigned to the upper run or the lower run of the storage belt. Viewed over the working width of the storage belt, that is to say transversely to the conveying direction, a damping element can preferably be arranged in the middle. Several damping elements can also be provided distributed over the working width. The at least one damping element can be flat or rod-shaped. The at least one damping element is preferably designed as a spring bar or leaf spring

The at least one damping element is preferably mounted on the two deflecting rollers so as to be rotatable relative to the deflecting rollers. This results in a particularly space-saving mounting and arrangement of the damping device in the compensation device. The damping element is not influenced by the rotary movement of the pulleys.

The damping device further preferably comprises two damping elements, a first damping element being assigned to an upper run of the storage belt and being bendable at least in the direction of a lower run of the storage belt and a second damping element being assigned to the lower run and being bendable at least in the same direction as the first damping element. As a result, a damping device can be provided in a particularly advantageous manner, which damps both the upper run and the lower run of the storage belt and can be integrated into the compensation device in a space-saving manner.

The first and the second damping element are preferably coupled to one another in such a way that they can be adjusted together. On the one hand, the damping device is then designed in such a way that it can follow the variable slack in the upper run and in the lower run in order to enable damping in different states of the variable slack. On the other hand, the damping device can thereby be easily driven and controlled. In particular, a drive for adjusting the damping elements is sufficient.

A method according to the invention for compensating for fluctuating conveying speeds of a material web, in particular a fibrous pile or nonwoven web, comprises:
Conveying the material web by means of a storage belt in a conveying direction from an inlet to an outlet;

Changing a variable sag of the storage belt as a function of the speed difference between the conveying speed of the material web at the inlet and the conveying speed of the material web at the outlet; and is characterized by arranging a damping device in the area of the variable sag at a distance from the storage belt that is smaller than the oscillation amplitude of the expected vibrations of the storage belt in the area of the variable sag, and thereby damping vibrations that occur.

In this way it is achieved that occurring vibrations of the storage tape can be dampened or completely prevented, which has negative effects on the Quality of the conveyed material web can be avoided. Vibrations that build up are dampened as soon as their vibration amplitude is greater than or equal to the distance between the damping device and the storage tape. The energy required for the oscillation is lost to the storage tape when it hits the damping device, which prevents the storage tape from oscillating.

The arrangement of the damping device preferably comprises carrying along the damping device with the variable slack of the storage tape, whereby it is possible to dampen vibrations in several states of the variable slack of the storage tape.

Carrying along the damping device with the variable slack of the storage tape particularly preferably includes changing the bend of at least one damping element of the damping device. As a result, a damping device can be used which is particularly simple to implement and, above all, can be easily adapted to the variable sag present at any given time.

Finally, it is preferred that the storage belt is guided over two deflection rollers which are arranged at a distance from one another in the conveying direction, the variable slack of the storage belt being arranged at least between the two deflection rollers, and the damping device following the free variable slack of the storage belt, which is caused by the The length of the storage tape between the pulleys and the distance between the two pulleys is defined.

As a result, the storage tape is not influenced in an undesired or uncontrolled manner by the damping device. In particular, the damping device does not serve as a deflection point or deflection element of the storage tape. The variable sag of the storage belt changes only as a function of the fluctuating speed differences at the inlet and outlet of the compensation devices. The damping device is only carried along or follows the free variable sag in such a way that it dampens vibrations that occur.

Fig. 1

zeigt in einer Querschnittsansicht eine Ausführungsform einer erfindungsgemäßen Kompensationseinrichtung in einem Ausgangszustand;

Fig. 2

zeigt in einer Querschnittsansicht die erfindungsgemäße Kompensationseinrichtung nach Fig. 1 mit verändertem Durchhang;

Fig. 3

zeigt eine Perspektivansicht eines Ausschnitts aus der erfindungsgemäßen Kompensationseinrichtung aus Fig. 1 und 2; und

Fig. 4

zeigt in einer Querschnittsansicht schematisch einen vergrößerten Ausschnitt der erfindungsgemäßen Kompensationseinrichtung nach Fig. 1 und 2.

Further features and advantages of the present invention emerge from the following description with reference to the drawings.

Fig. 1

shows in a cross-sectional view an embodiment of a compensation device according to the invention in an initial state;

Fig. 2

shows the compensation device according to the invention in a cross-sectional view Fig. 1 with changed sag;

Fig. 3

FIG. 14 shows a perspective view of a section from the compensation device according to the invention from FIG Figs. 1 and 2 ; and

Fig. 4

shows in a cross-sectional view schematically an enlarged section of the compensation device according to the invention Figs. 1 and 2 .

The Figures 1 and 2 show an embodiment of a compensation device 1 according to the invention for compensating for fluctuating conveying speeds of a material web 18 (see FIG Fig. 4 ). The compensation device 1 comprises an endlessly circulating storage belt 2 for conveying the material web in a conveying direction F through the compensation device 1. The storage belt 2 can be formed, for example, by lined toothed belts. The storage belt 2 has a variable sag 4 in order to enable the transition of the material web from a conveyance at fluctuating conveying speeds to a conveying at a constant speed. The storage tape 2 is via two pulleys 6 (see Fig. 3 ), which are arranged in the conveying direction F at a distance from one another. The material web to be conveyed is arranged on the upper run 10 of the storage belt 2 and is conveyed by the latter through the compensation device 1.

The first pulley 6 (in Fig. 1 arranged concealed on the left side) is arranged on the input side of the compensation device 1 and the second deflection roller 6 (in Fig. 1 arranged concealed on the right-hand side) is arranged on the output side of the compensation device 1. On the input side, the compensation device 1 receives a material web, preferably from a non-woven layer. For the transfer of the material web, the discharge belt of the fleece layer can directly adjoin the storage belt 2 guided around the first deflecting roller 6, or one or more feed belts can be interposed be. The first deflection roller 6 is preferably driven synchronously with the discharge belt of the web layer at a fluctuating speed.

The second deflection roller 6 arranged on the output side is adjoined in the conveying direction F by a feed belt of the subsequent consolidation device, for example a needle loom. In the area of the second deflection roller 6, the material web is transferred from the storage belt 2 to the feed belt of the consolidation device. The second deflection roller 6 is therefore preferably constantly driven synchronously with the feed belt of the solidifying device.

In addition to the deflecting rollers 6, further deflecting elements or deflecting rollers can be provided in order to stretch the storage tape 2. For example, the upper run 10 of the storage belt 2 can be guided over a further deflection roller arranged upstream of the first deflecting roller 6 in the conveying direction F and / or a deflecting roller arranged downstream of the second deflecting roller 6. Likewise, one or more deflection rollers can be provided for tensioning the lower run 12 of the storage belt 2.

The variable sag 4 of the storage tape 2 is arranged at least between the two deflection rollers 6. In the embodiment shown, the variable sag 4 is formed both in the upper run 10 and in the lower run 12 of the storage belt 2. To compensate for fluctuating conveying speeds of the material web, however, it is sufficient if at least the upper run 10 has a variable sag 4. The lower run 12 can be guided via alternative compensating mechanisms in order to enable a variable sag 4 in the upper run 10 with a constant length of the endless storage belt 2.

From the synopsis of the Figures 1 to 3 the mode of operation of the compensation device 1 can be seen. At the second deflection roller 6, the storage belt 2 and the material _web arranged thereon are moved in the conveying direction F at a constant speed V const. On the input side, the storage belt 2 and the material web arranged thereon are moved on the first deflection roller 6 and at a variable speed V _var . The variable speed V _var. Is synchronous with the speed of the outfeed belt of the fleece layer and fluctuates between values which are partly greater and partly less than the constant speed V _const . In particular, the storage tape 2 at the First pulley 6 braked to a standstill and accelerated _{to speeds greater than the constant speed V const.} If the variable speed V _{var. Is greater than the constant speed V const} . At certain times or over a certain period of time, more storage tape 2 is moved between the two deflection rollers 6 than is moved out of this area by the second deflection roller 6. The variable sag 4 of the upper run 10 of the storage belt 2 increases accordingly, as in FIG Fig. 2 you can see. The material web additionally fed in due to the excess speed is temporarily stored in the variable slack 4. Since the storage belt 2 has an essentially constant length, the variable sag 4 of the lower run 12 of the storage belt 2 decreases as soon as the sag of the upper run 10 increases.

If the variable speed V _var. Decreases to the point that it is less than the constant speed V _const. , More storage tape 2 and material web is moved out of the area between the two deflecting rollers 6 than is moved into this area by the first deflecting roller 6 becomes. The variable sag 4 of the upper run 10 of the storage belt 2 is correspondingly reduced, while the variable sag 4 of the lower run 12 of the storage belt 2 increases again.

The compensation device 1 further comprises a damping device 14, which is in the Figures 1 to 3 is shown in a preferred embodiment. A detail of the cross-sectional view of the upper run 10 of the storage belt 2 according to FIG Figs. 1 and 2 is in Fig. 4 shown in a detailed view.

The damping device 14 is arranged in the region of the variable sag 4 at a distance from the storage tape 2 which is smaller than the oscillation amplitude of the expected vibrations of the storage tape 2 in the region of the variable sag 4. In the preferred embodiment, FIG Figs. 1 and 2 the damping device 14 is arranged both in the region of the variable sag 4 of the upper run 10 and in the region of the variable sag 4 of the lower run 12. It can also be seen that the damping device 14 is preferably arranged in the interior of a loop formed by the circumferential storage belt 2 in order to enable a space-saving configuration of the compensation device 1. It goes without saying that the damping device 14 also only can be arranged in the area of the upper run 10 or the lower run 12 of the storage belt 2, as well as outside the loop formed by the storage belt 2.

In some embodiments, the distance between the damping device 14 and the storage tape 2 can be so small that it can hardly be seen. In Fig. 4 a detailed view of the cross section of the upper run 10 in the area of the variable sag 4 is therefore shown in order to illustrate the principle according to the invention. It goes without saying that the statements made in this regard can also be transferred to the lower run 12, this not conveying any material web.

The storage tape can, for example, be caused to oscillate due to the fluctuations in speed at the input of the compensation device 1. In particular, between the two deflection rollers 6, between which the variable sag 4 is formed, so-called cable oscillations of the storage belt 2 can therefore occur. A sinusoidal oscillation 18 of the storage tape 2 in FIG Fig. 4 indicated by a dashed line. The waveform and amplitude depend specifically on the storage tape 2 used, its storage and its excitation. For each storage tape 2 used, the vibrations and vibration amplitudes to be expected can be determined mathematically or experimentally.

The damping device 14 is arranged in the area of the variable sag 4 at a distance D from the storage belt 2 which is smaller than the oscillation amplitude A of the expected oscillation 18 of the storage belt 2 in the area of the variable sag 4. If the storage belt 2 is excited to oscillate, this oscillation is damped as soon as its amplitude is so great that the storage tape 2 touches the damping device 14. At this moment, the damping device 14 takes from the storage tape 2 the energy required for the further build-up of the vibrations. The occurrence of an oscillation 18, the amplitude A of which is greater than the distance D between the damping device 14 and the storage tape 2, is thereby prevented. By selecting the distance D between the damping device 14 and the storage tape 2, undesired vibrations can be damped in a targeted manner.

In principle, the distance to be selected between the damping device 14 and the storage tape 2 depends on the specific application. To avoid vibrations that arise the distance between the damping device and the storage tape is preferably less than 5 cm, more preferably less than 2 cm, even more preferably less than 1 cm or less than 5 mm.

Further features and properties of the damping device 14 are described below using the in Figs. 1 to 3 illustrated preferred embodiment, but can also be easily transferred to other embodiments.

The damping device 14 is arranged essentially parallel to the storage tape 2. If the damping device 14 is arranged both in the region of the upper run 10 and in the region of the lower run 12 of the storage belt 2, it preferably has a first damping element 20 and a second damping element 22. The first damping element 20 is assigned to the upper run 10 of the storage belt 2 and is bendable at least in the direction of the lower run 12. The second damping element 22 is assigned to the lower run 12 and can be bent at least in the same direction as the first damping element 20. The first damping element 20 runs essentially parallel to the upper run 10 and the second damping element 22 runs essentially parallel to the lower run 12 of the storage belt 2. The damping device 14, here the first and second damping elements 20, 22, can be mounted on the deflection rollers 6. The distance between the damping device 14 and the storage belt 2 in the area of the deflecting rollers 6 is consequently smaller than in the area of the apex of the variable sag 4. Accordingly, deviations from an exactly parallel course of the damping device 14 and the storage belt 2 can occur.

The damping device 14 can be arranged in a stationary manner in order to be arranged only in a predetermined state of the variable sag 4 of the storage tape 2 in the region of the oscillation amplitude of the expected vibrations of the storage tape. For example, it may be sufficient if the damping device 14 is only arranged at a distance from the storage belt 2 at a maximum or minimum sag of the upper run 10 that is smaller than the oscillation amplitude of the expected vibrations of the storage belt 2 in the area of the variable sag 4 the damping device 14 can only be arranged at a distance from the lower run 12 at a distance from the lower run 12 that is smaller than the oscillation amplitude of the oscillations of the lower run 12 to be expected only when the lower run 12 sags. This has the advantage that the damping device 14 can be designed very simply and a mechanism for adjusting or carrying along the damping device 14 with the variable sag 4 of the storage tape 2 can be dispensed with.

However, it is preferred that the damping device 14 is designed in such a way that it can be carried along with the variable sag 4 of the storage tape 2 at least in sections. It is thereby achieved that the damping device 14 damps critical or disruptive vibrations of the storage tape 2 in several states of the variable sag 4.

Carrying the damping device 14 with the variable sag 4 can, for example, by the in the Figs. 1 and 2 illustrated embodiment can be easily implemented. For this purpose, the damping device 14 comprises at least the first damping element 20, preferably also the second damping element 22. The damping elements 20, 22 are flexible and extend at least partially, but preferably completely, between the two deflection rollers 6. The flexibility of the damping elements 20, 22 is achieved that these can be bent in accordance with the variable sag 4 in order to be carried along with the free variable sag. The damping elements 20, 22 are designed, for example, as spring bars or leaf springs. A damping element 20, 22 can be arranged in a transverse direction of the storage belt 2, which extends transversely to the conveying direction F and in the plane of the surface of the storage belt 2 receiving the material web 16. In order to reliably prevent vibrations over the entire width of the storage tape 2, however, it is preferred that a plurality of first damping elements 20 and a plurality of second damping elements 22 are arranged in the transverse direction next to one another, distributed over the width of the storage tape.

In Fig. 3 the transverse slats of the storage tape 2 are not shown for better clarity. How out Fig. 3 As can be seen, the at least one damping element, here the first and the second damping element 20, 22, is rotatably mounted relative to the deflection rollers 6.

At least one toothed belt pulley is rotatably mounted in each case on the deflection rollers 6 or is formed integrally with the deflection roller 6 in order to engage with the storage tape 2 and to drive it.

Offset to the toothed belt pulleys, at least one adjusting disk 24, 26 can be rotatably mounted on the shaft of the deflecting rollers 6 or on the rollers themselves. In the embodiment shown, a first adjusting washer 24 is rotatably mounted on the shaft of the first deflection roller 6 and a second adjusting washer 26 is rotatably mounted on the shaft of the second deflecting roller 6.

Each damping element 20, 22 is articulated to both adjusting disks 24, 26. The positions of the bearing points of the articulated connections between the damping elements 20, 22 and the adjusting disks 24, 26 are shown in FIG Fig. 1 indicated by the points 28. In Fig. 1 an initial state of the storage belt 2 is shown, in which the variable sag of the upper run 10 is minimal and the variable sag of the lower run 12 is maximal. In this initial state, the first damping element 20 is pretensioned in the direction of the lower strand 12. This means that the first damping element 20, starting from its bearing points 28, is bent downward in the direction of the lower run 12. If the second damping element 22 is also provided, it is pretensioned in the same direction as the first damping element 20, that is to say has a deflection in the same direction. In the initial state, the sag of the upper run 10 is less than the sag of the lower run 12, which is why the second damping element 22 is more bent in the initial state than the first damping element 20.

In order to enable the sag 4 of the compensation device 1 to be varied and not to be blocked by the damping elements 20, 22, the at least one damping element 20, 22 with the variable sag is to be carried along. For this purpose, the first and the second adjusting washer 24, 26 are rotated in opposite directions, as indicated by the arrows within the deflection rollers 6 in FIG Fig. 2 is indicated. More precisely, the first adjusting disk 24 is rotated clockwise and the second adjusting disk 26 is rotated counterclockwise around the shaft of the respective deflection roller 6. The bearing points 28 of the first damping element 20 according to Fig. 1 move accordingly to the positions 28 ' Fig. 2 . In the case of the first damping element 20, the distance between the bearing points 28 ′ is after Fig. 2 in the conveying direction F less than the distance between the bearing points 28, whereby the deflection of the first Damping element 20 is increased. The apex of the deflection moves downwards accordingly in order to allow a greater slack in the upper run 10 of the storage belt 2. Out Fig. 2 it can be seen that the bearing points 28 of the second damping element 22 follow Fig. 1 move accordingly with the bearing points 28 of the first damping element 20, whereby the deflection of the second damping element 22 is reduced. The distance between the bearing points 28 'is more precise Fig. 2 greater than the distance between the bearing points 28, as a result of which the apex of the deflection of the second damping element 22 migrates upwards in order to follow the reduced slack of the lower run 12 of the storage belt 2.

The damping device 14 or the damping elements 20, 22 do not cause or influence the variable slack 4 of the storage tape 2. By appropriate adjustment, the damping device enables the free slack to be increased or follows the free slack when it is reduced.

A wide variety of possibilities are apparent to those skilled in the art for adjusting the damping device 14 or carrying along the damping device 14 with the variable sag 4. For example, adjustment means can be provided within the loop formed by the storage belt 2, which bring about the respective adjustment. For example, an adjustment means can exert a compressive force on the first damping element 20 in order to move it in the direction of maximum deflection. The same or a different adjustment means can be provided in order to exert a compressive force on the second damping element 22 in order to move it in the direction of maximum deflection. In principle, a separate adjustment means can be provided for each damping element 20, 22 or a common adjustment means can be provided for the first and second damping elements 20, 22. The damping device 14 or the damping elements 20, 22 can be adjusted by linear tensile and / or compressive forces or by moments.

A particularly preferred embodiment is in Figures 1 to 3 shown. The first and the second adjusting washer 24, 26 each have a toothed ring section 30 which extends over part of the circumference of the respective adjusting washer 24, 26 and is preferably directed into the interior of the loop formed by the storage belt 2. A first pinion 32 is arranged on the toothed ring section 30 of the first adjusting disk 24, which is in engagement with the ring gear portion 30. A second pinion 34 is provided on the ring gear section 30 of the second adjusting disk 26, which is in engagement with the ring gear section 30 of the second adjusting disk 26. If several first damping elements 20 and several second damping elements 22 and thus several first adjusting disks 24 and several second adjusting disks 26 are arranged next to one another across the width of the storage belt 2 in the transverse direction, a corresponding plurality of first and second pinions 32, 34 can each be on a common shaft be arranged or replaced by a rack.

At least one drive 36 is provided which moves one of the first and second pinions 32, 34 cyclically in a clockwise or counterclockwise direction. The drive 36 can drive the first or the second pinion 32, 34 directly or via a transmission. A separate drive 36 can be provided for each setting disk 24, 26. Alternatively, as shown, the drive movement is transmitted via a chain 38 and a further pinion 40 to the other of the first and second pinions 32, 34. The drive can be a crank drive or a servo motor. Various other drives are familiar to the person skilled in the art and can be used as desired. The drive 36 can itself be arranged within the loop formed by the storage belt 2. The drive movement can also be transmitted to the pinions 32, 34 via a drive shaft, the drive shaft running laterally at a distance from the storage belt 2 and transferring the drive movement to a first shaft of the first pinion 32 or a second shaft of the second pinion 34.

The manipulated variable of the controls for the bending of the at least first damping element 20 results from the speed difference between the variable speed V _var. And the constant speed V _const. , Which are defined by the exit speed of the outfeed belt of the nonwoven layer and the infeed speed of the feed belt of the needle machine.

A control device is therefore preferably provided which controls both the drives of the deflection rollers 6 and the drive 36 of the damping device 14 as a function of the exit speed of the web layer and the entry speed of the feed belt of the needle machine.

The damping device can have a rubber pad or a rubber buffer for increased damping.

Claims (15)

1. Compensation device (1) for compensating variable conveying speeds of a material web (16), in particular a fibrous pile web or a fibrous non-woven web, comprising
   a continuously revolving accumulator belt (2) for conveying the material web (16) in a conveying direction (F) through the compensation device (1), wherein the accumulator belt (2) has variable slack (4) and is guided by way of two deflection rollers (6) which in the conveying direction (F) are disposed so as to be mutually spaced apart, wherein the variable slack (4) of the accumulator belt (2) is disposed at least between the two deflection rollers (6),
   characterized in that
   the compensation device (1) furthermore has a damping device (14) which in the region of the variable slack (4) is disposed at a spacing (D) from the accumulator belt (2) that is smaller than the oscillation amplitude (A) of oscillations (18) of the accumulator belt (2) that are to be expected in the region of the variable slack (4).
2. Compensation device (1) according to Claim 1, characterized in that the accumulator belt (2) comprises an upper lead (10) and a lower lead (12), and the variable slack (4) is configured at least in the upper lead (10) of the accumulator belt (2).
3. Compensation device (1) according to Claim 1 or 2, characterized in that the damping device (14) is disposed so as to be stationary and is configured in such a manner that said damping device (14) at least in portions is able to be guided conjointly with the variable slack (4) of the accumulator belt (2) .
4. Compensation device (1) according to one of the preceding claims, characterized in that the damping device (14) is disposed so as to be substantially parallel to the accumulator belt (2).
5. Compensation device (1) according to one of the preceding claims, characterized in that the damping device (14) is disposed inside a loop formed by the revolving accumulator belt (2).
6. Compensation device (1) according to one of the preceding claims, characterized in that the damping device (14) is a passive damping device (14).
7. Compensation device (1) according to one of the preceding claims, characterized in that the variable slack (4) is configured in an upper lead (10) and in a lower lead (12) of the accumulator belt (2), and the damping device (14) is disposed both in the region of the variable slack (4) of the upper lead (10) and in the region of the variable slack (4) of the lower lead (12).
8. Compensation device (1) according to one of the preceding claims, characterized in that the damping device (14) comprises at least one damping element (20, 22) which is flexible and extends between the two deflection rollers (6).
9. Compensation device (1) according to Claim 8, characterized in that the at least one damping element (20, 22) on the two deflection rollers (6) is mounted so as to be rotatable relative to the deflection rollers (6).
10. Compensation device (1) according to either of Claims 8 and 9, characterized in that the damping device (14) comprises at least two damping elements (20, 22), wherein a first damping element (20) is assigned to an upper lead (10) of the accumulator belt (2) and is able to bend at least in the direction of a lower lead (12) of the accumulator belt (2), and a second damping element (22) is assigned to the lower lead (12) and is able to bend at least in the same direction as the first damping element (20).
11. Compensation device (1) according to Claim 10, characterized in that the first and the second damping element (20, 22) are coupled to one another in such a manner that said damping elements (20, 22) are able to be conjointly adjusted.
12. Method for compensating variable conveying speeds of a material web (16), in particular a fibrous pile web or a fibrous non-woven web, comprising
    conveying the material web (16) in a conveying direction (F), from an infeed to an outfeed, by means of an accumulator belt (2);
    varying a variable slack (4) of the accumulator belt (2) as a function of the speed differential between the conveying speed of the material web (16) at the infeed and the conveying speed of the material web (16) at the outfeed;
    characterized by
    disposing a damping device (14) in the region of the variable slack (4) at a spacing (D) from the accumulator belt (2) that is smaller than the oscillation amplitude (A) of oscillations (18) of the accumulator belt (2) that are to be expected in the region of the variable slack (4) and, on account thereof, damping oscillations (18) that arise.
13. Method according to Claim 12, characterized in that the disposing of the damping device (14) comprises the guiding of the damping device (14) conjointly with the variable slack (4) of the accumulator belt (2) .
14. Method according to Claim 13, characterized in that the guiding of the damping device (14) conjointly with the variable slack (4) of the accumulator belt (2) comprises the varying of the bend of at least one damping element (20, 22) of the damping device (14) .
15. Method according to either of Claims 13 and 14, characterized in that the accumulator belt (2) is guided by way of two deflection rollers (6) which in the conveying direction (F) are disposed so as to be mutually spaced apart, wherein the variable slack (4) of the accumulator belt (2) is disposed at least between the two deflection rollers (6), and
    the damping device (14) follows the free variable slack (4) of the accumulator belt (2) that is defined by the length of the accumulator belt (2) between the two deflection rollers (6) and by the spacing of the two deflection rollers (6).

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