DE102007023215A1 - Device for guiding a material web strip - Google Patents

Abstract

The invention relates to a device (1) for guiding a material web strip in a running direction (2), having a housing (3), in which a negative pressure generation system is arranged. It is intended to guide the material web strip safely. To this end, it is provided that a plurality of vacuum chambers (7-10 12) are arranged one after another in the running direction (2) in the housing (3), of which each comprises at least one suction device (20-25).

Description

The The invention relates to a device for guiding a material web strip in a running direction with a housing in which a negative pressure generating device is arranged.

The Invention is hereinafter in connection with a paper web as Example of a web strip described. she is however also with other material webs and cut from it Material web strip applicable.

A Paper web must be in the course of their production and processing by various processing facilities are managed, including a dryer section, a press section, a calender and possibly a coating or a sizing device. This is often done so before, that at the edge of the paper web a web strip with a width of the order of 200 cuts to 300 mm and this strip first by the processing device leads. As soon as this material web strip has come so far that you can train him can, the paper web is cut to width, allowing it in full width can pass through the appropriate processing facility.

For the lead of the material web strip are next to so-called Cable guide assemblies also used devices that work with negative pressure. Here is usually an air-permeable Band around a housing on which the material web lies. The band is supported on a plate with holes or slits. On the side facing away from the tape The plate is a negative pressure generated so that the web strip sucked on the other side of the tape.

An example of such a device is out EP 1 127 978 B1 known. Here, several turbines are arranged in the housing, which suck air through the tape to hold the web strip on the other side of the tape.

Another embodiment is made EP 1 342 844 A2 known. Here, several "doctor blades" are arranged in the housing, which ends shortly below the inside of the band and peel off the air layer located there, so to speak. This also creates a negative pressure on the Au ßenseite the band, with which the web or at least her web strip can be firmly sucked.

at But it is always faster machines in all cases difficult to ensure that the web strip so stable that it is easily connected to a subsequent transport device, for example, a cable guide arrangement or another Vacuum conveyor, can be handed over.

Of the Invention is based on the object, a web strip to lead safely.

These Task is characterized in a device of the type mentioned by solved that in the housing in the running direction one behind the other a plurality of vacuum chambers are arranged, each of which at least having a suction device.

With this design takes the time that is needed to apply the web strip with the full vacuum, shortened. The web strip is over the Housing led and thereby increasingly covers a Low pressure chamber off. As long as the vacuum chamber is not yet is completely covered, can through the remaining opening "Secondary air" are sucked in, so that the negative pressure in the vacuum chamber often still too weak to secure the material web strip hold. But as soon as the web strip the vacuum chamber has completely covered, acts of the suction device provided negative pressure in full on the Web strips. Because several vacuum chambers in the direction of travel are arranged one behind the other, is the length of each Vacuum chamber shorter than that of the overall device, so they finished earlier at the same speed becomes. When the web strip at the first vacuum chamber is held in the running direction, then he is already in a certain Circumference stabilized. However, the holding force that is made up Area times negative pressure composed, in many cases still too low to hold the web strip safe overall. This unstable situation holds only for short time, because the web strip continues to run and then the one in running direction next or next Covering chambers, so that there is also the negative pressure there the web strip acts. The holding force acting on the web strip, So it is built up in sections.

Preferably, a first vacuum chamber in the running direction of the material web strip has a larger number of suction devices than a vacuum chamber arranged behind it in the direction of travel of the material web strip. This makes it possible to generate a higher negative pressure in the first vacuum chamber, as long as the web of material web has not yet completely covered this vacuum chamber. Because of the plurality of suction devices namely more air is carried away, so that the web strip is already held with a high reliability on the screen or other air-permeable belt, if the first vacuum chamber still not completely closed. The highest negative pressure occurs when the first vacuum chamber is completely covered by the material web strip. After the web strip is stabilized in this way over the first vacuum chamber, a lower negative pressure is sufficient to transport the web strip to the end of the device. Since the vacuum chambers are gradually covered and then act with full negative pressure on the web strip, the holding force on the air-permeable belt at the end of the device is very large. Slippage of the material web strip is reduced or even prevented.

Preferably the suction devices are designed as suction nozzles. suction nozzles can be easily installed. They are supplied with compressed air, so that also necessary for sucking energy supply to simple Manner can be provided.

Preferably is in the first vacuum chamber, a boundary wall with suction filled. So you can see such a large number of suction devices that this wall, for example the bottom of the vacuum chamber, completely or at least almost completely covered with suction devices. The suction devices are here not just the openings through which the suction air from the Vacuum chamber is sucked out, but also the elements surrounding the suction holes. By having a correspondingly large one Number of suction devices provides that over the boundary wall are distributed, the negative pressure can be flat so to speak produce.

Preferably have the negative pressure chambers on a guide side, on which runs along the web strip, and one of Guide side opposite ground, taking the suction devices act through the floor. This embodiment has the advantage that the dirt is sucked towards the floor and then be removed by the suction devices. In the long run, virtually no dirt in the vacuum chamber accumulate. This is true regardless of whether the device is operated so that the web strip in the direction of gravity above or below her. Important is in this context, that the air flow so to speak straight from the dirt-causing side to the opposite Page can be sucked.

Preferably The guide side and the bottom run parallel to each other. The vacuum chambers thus have a constant height in the direction of travel. This simplifies the production.

in this connection it is preferred that the leading side and the bottom one Distance in the range of 5 to 35 mm, in particular in the range of 10 to 20 mm. This will be the volume of the vacuum chamber on the one hand kept so small that you relatively with an acceptable cost can quickly generate a sufficient negative pressure. on the other hand exists between the guide side and the floor sufficient Distance, so that the flow cross section for the air to be sucked off is big enough.

Preferably The suction devices are parallel with respect to a central axis to the running direction, arranged symmetrically. In order to Also, the negative pressure with respect to the central axis can be symmetrical produce, which also leads to a stabilization of the material web strip contributes to the air-permeable band. If only one suction device, for example a suction nozzle, in the vacuum chamber, then this suction nozzle is through divided the central axis. If you have two suction nozzles in the Vacuum chamber has, then these are symmetrical on both sides arranged the central axis.

Preferably At least two adjacent vacuum chambers are separated by a partition wall separated, at least in sections an angle to the direction includes, greater than 95 ° or is less than 85 °. In other words, it runs the partition at least partially at an angle ≠ 90 ° to Direction. This has the advantage that the web strip at least temporarily covers two vacuum chambers. This avoids one dead zone, which may cause instability could lead the material web strip. If the web strip with its beginning on the partition Run away, then he is at the same time of the oppressions acted upon in two vacuum chambers, wherein in the running direction first vacuum chamber stronger on the web strip acts.

in this connection is preferred that the partition wall has two legs, which in opposite directions are inclined to the direction. Preferably these two legs are inclined in the direction of travel. With that result in turn symmetrical conditions, which is favorable affects the stabilization of the material web strip.

Preferably the legs collide in a V-shape. The partition thus has two substantially straight sections, so they easy to manufacture. Once the web strip with his Beginning over the top of the "V", he is also from subjected to the following vacuum chamber with negative pressure.

Preferably, at least one runs Vacuum chamber, the partition in the direction of both sides of the suction device. The suction device is thus positioned relatively close behind the partition, so that the negative pressure can act relatively early on the web strip, so almost immediately if the web has been passed over the partition wall. This results in conditions after only a short time, through which the material web strip can be stably guided. If the partition is V-shaped, then the suction is, so to speak, in the gusset of the "V".

Preferably the housing has a vacuum chamber limiting Intermediate wall on. This makes it possible to increase the volume of Keep vacuum chambers small. The smaller the volume, the better faster, the air in it can be sucked off and the negative pressure being constructed. The amount of negative pressure will not significantly affected. So you do not have the entire housing vacuum empty to create the vacuum.

Preferably the partition wall is trough-shaped with sloping side walls educated. The inclined side walls contribute to one to a reduction in volume. On the other hand, they also help Dirt or water that enters the vacuum chamber, to divert to the suction devices out.

in this connection it is preferred that the side walls are in the direction of gravity are inclined towards the suction device. This also facilitates the Removal of dirt.

Preferably is a compressed air supply line for the suction nozzles arranged between the housing and the intermediate wall. These In any case, compressed air supply line is within the device not visible and does not bother. Also, the danger that it is damaged, reduced.

preferably, a vacuum chamber has a volume of a maximum of 2 l, in particular maximum 1 l, up. Such a small volume can be relative quickly suck empty so that even high-speed material web strips, for example, a speed of the order of magnitude of 1,800 m / min, can be kept stable very quickly.

preferably, is at least one vacuum chamber parallel to the direction in divided into at least two compartments. These are preferably around the first vacuum chamber in the running direction. If the web strip is cut from the web, then it can happen that he does not come to rest exactly in the middle of the vacuum chamber. In this case, there is a risk that he is the vacuum chamber not completely covering, so that laterally still secondary air can be sucked, whereby the holding force is reduced. If Now the vacuum chamber parallel to the direction in at least divided into two compartments, then the chance is great at least one of these compartments is completely covered by the material web strip becomes. At least in this compartment of the web strip is then held with full force.

in this connection is preferred that each compartment in the direction of a V-shaped Partition is limited. This results in the advantages that are discussed above In connection with a vacuum chamber generally described have been. The V-shaped partition creates no Deadband when the web strip passes over the partition. Much more he is then wall when crossing the separation then from the negative pressure acted upon in two adjacent compartments in the direction.

The Invention will be described below with reference to a preferred embodiment described in conjunction with the drawing. Herein show:

1 a perspective view of an apparatus for guiding a web of material in the open state,

2 a plan view of the device according to 1 .

3 a section III-III after 2 and

4 a sectional view through a suction nozzle.

A device 1 for guiding a material web strip, not shown, in a running direction 2 has a housing 3 on, at its front end with a pulley 4 and at its rear end with a pulley 5 is provided. For the pulley 5 at the rear end is a drive pin 6 provided, to which a non-illustrated drive motor can be connected. About the two pulleys 4 . 5 an air-permeable belt is guided, which is not shown for reasons of clarity in the drawing. This band may be formed, for example, as a sieve.

The housing 3 has a cover plate also not shown, which is provided with openings, for example in the form of slots. The cover plate has been omitted to give details from inside the device 1 to be able to represent. In operation, the air-permeable tape lies on the cover plate. On the tape is then the web strip, through the cover plate and the air-permeable belt is subjected to negative pressure and thus sucked on the outside of the air-permeable belt.

In the case 3 are six vacuum chambers 7 - 12 intended. The vacuum chambers are by partition walls 13 - 17 separated from each other. Every partition 13 - 17 has in plan view a V-shape, so two legs 18 . 19 at an angle of about 45 ° to the direction of travel 2 run.

Every vacuum chamber 7 - 12 is with at least one suction device in the form of a suction nozzle 20a - 20e . 21 - 25 Mistake. The in the direction of travel 2 first suction chamber 7 has a larger number of suction nozzles 20a - 20e on as the running direction 2 further back arranged vacuum chambers 8th - 12 , In the present embodiment, the first vacuum chamber 7 five suction nozzles 20a - 20e on. But it is also possible, the first vacuum chamber 7 only with three or four suction nozzles to provide.

The suction nozzles 20 - 25 are in a ground 26 the vacuum chamber 7 - 12 arranged. The floor 26 is a boundary wall that is a leading edge 27 opposite, is guided along the web strip. On the leading side 27 is the air-permeable belt on which the web strip is applied (not shown). The floor 26 and the leadership side 27 are parallel to each other with a distance in the range of 5 to 35 mm, preferably with a distance in the range of 10 to 20 mm.

How out 1 and 2 shows, are the suction nozzles 20a - 20e in the running direction 2 first vacuum chamber 7 arranged so that they cover the ground 26 to fill. So there would be no room for another suction nozzle 20a - 20e available. This makes it possible in the first vacuum chamber 7 not only relatively quickly build a negative pressure when the web strip over the vacuum chamber 7 is passed away, but already let the negative pressure act on the web strip to a sufficient extent, if the web strip the vacuum chamber 7 not finished yet.

In the other vacuum chambers 8th - 12 is, however, the respective suction nozzle 21 - 25 arranged so that they are relatively close to the dividing wall 13 - 17 is, so they are in the running direction 2 on both sides of the respective partition 13 - 17 is towered over. The suction nozzle 21 - 25 is, so to speak, in the "gusset" of the "V".

As in particular from 3 shows, the housing has 3 an intermediate wall 28 on, which are the vacuum chambers 7 - 12 limited. The partition 28 has two sloping sidewalls 29 . 30 on that, in the direction of the suction nozzles 20 - 25 are inclined. When the device 1 arranged as is in 3 is shown, the web strip so in the direction of gravity above the housing 3 is led, then dirt particles or water droplets, which are in the vacuum chambers 7 - 12 enter, through the side walls 29 . 30 towards the suction nozzle 20 - 25 guided so that they can be easily removed. However, the same applies to operation "overhead", because even then creates a flow of air, the dirt particles on the side walls 29 . 30 and the floor 26 abfördert.

4 schematically shows a suction nozzle 23 on average. The suction nozzle 23 has a compressed air inlet 31 on, can be injected through the compressed air. The suction nozzle 23 also has a suction inlet 32 on. The through the compressed air inlet 31 incoming compressed air enters through a gap between the differently hatched parts of the suction nozzle 23 and then flows through an exit 33 out. It tears suction air through the suction inlet 32 occurred with. The suction nozzle 23 works on the Venturi principle. Through the partition 28 becomes the volume of the vacuum chambers 7 - 12 kept small. You can see the curtain wall 28 designed so that every vacuum chamber 7 - 12 has a volume of about 2 liters or less, for example 1 liter.

A compressed air supply line 34 is in the case 3 arranged between the partition 28 and the actual housing wall, so that the compressed air supply line 34 does not appear disturbing to the outside. The compressed air supply line 34 is each via a branch line 35 with the respective suction nozzles 20 - 25 connected.

A vacuum chamber 7 - 12 has a length in the direction of travel 2 of about 300 mm. At a web speed of 1,800 m / min, it takes about 1/100 of a second to a vacuum chamber 7 - 12 is covered by the web strip. Depending on the setting, a suction nozzle has a suction power of, for example, 4,500 l / min, so that in 1/100 second, about 0.75 l of air from each vacuum chamber 7 - 12 can be sucked off. When the vacuum chamber 7 - 12 has a volume of 1 to 2 l, then the web strip is reliably held, as soon as he has a vacuum chamber 7 - 12 has run over. In order to build up the necessary negative pressure, it is not necessary, all the air from the vacuum chamber 7 - 12 to remove.

Because the partitions 13 - 17 have the illustrated V-shape (other shapes are also possible, as long as they are not perpendicular to the direction of travel 2 ver run), the web strip at a promotion in the direction of travel 2 simultaneously from the negative pressure in two adjacent vacuum chambers 7 - 12 As soon as it starts, it applies a partition 13 - 17 To exceed. This avoids dead zones. It is also helpful that the suction nozzles 21 - 25 relatively close behind the partitions 13 - 17 are arranged so that the negative pressure generated thereby can also act relatively quickly on the web strip.

How out 3 shows, the suction nozzles open 20 - 25 practically at the height of the ground 26 , In any case, they are arranged so that air is sucked through the floor. This has a significant advantage for the self-cleaning effect of the device. If there are fibers, dust or water in the vacuum chambers 7 - 12 accumulate, these impurities through the suction nozzles 20 - 25 sucked in and on the bottom of the device 1 blown out.

It is now possible to influence the force with which the material web strip is held and guided by the length of the device. A zone, ie a vacuum chamber 7 - 12 has a length of the order of 250 to 400 mm. Depending on how long you want to lead the web strip, then you have more or less vacuum chambers 7 - 12 to switch one after the other. In the running direction 2 first vacuum chamber 7 For example, you can create a vacuum of 28 mbar. In the following vacuum chambers 8th - 12 then a negative pressure of 5 to 20 mbar is sufficient.

The suction nozzles 20 - 25 are in relation to a central axis 36 arranged symmetrically. So if a vacuum chamber 8th - 12 only one suction nozzle 21 - 25 has, then this suction nozzle 21 - 25 through the central axis 36 divided. If, as in the first vacuum chamber 7 , several suction nozzles 20a - 20e are provided, then these are symmetrical to the central axis 36 arranged. This allows pressure conditions in the vacuum chambers 7 - 12 realize that equally symmetrical to the central axis 36 are. A displacement of the material web strip by different pressures is virtually ruled out.

However, it may happen that the material web strip is already displaced laterally during cutting. In this case, it may be convenient, the individual vacuum chambers 7 - 12 parallel to the direction of travel 2 into two or three compartments to divide. In a subdivision into two compartments, an intermediate wall would be arranged where the central axis 36 located. In this case, each compartment will have its own suction nozzle 20 - 25 provided, wherein in the direction of the first compartment of each row in turn more suction nozzles than the downstream in the direction of the compartments.

When looking at the subdivision of the vacuum chambers 7 - 12 into individual compartments, then it will be convenient, the partitions 13 - 17 also to design between the individual compartments in the direction of V-shaped to achieve the advantages mentioned above.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1127978 B1 [0005]
• - EP 1342844 A2 [0006]

Claims (19)

Device for guiding a material web strip in a running direction with a housing in which a vacuum generating device is arranged, characterized in that in the housing ( 3 ) in the running direction ( 2 ) successively several vacuum chambers ( 7 - 12 ) are arranged, each of which at least one suction device ( 20 - 25 ) having. Device according to claim 1, characterized in that one in the running direction ( 2 ) of the material web strip first vacuum chamber ( 7 ) a larger number of suction devices ( 20a - 20e ) as one in running direction ( 2 ) of the material web strip behind arranged vacuum chamber ( 8th - 12 ) having. Device according to one of claims 1 to 2, characterized in that the suction devices as suction nozzles ( 20 - 25 ) are formed. Apparatus according to claim 2 or 3, characterized in that in the first vacuum chamber ( 7 ) a boundary wall with suction devices ( 20a - 20e ) is filled. Device according to one of claims 1 to 4, characterized in that the vacuum chambers ( 7 - 12 ) a leadership page ( 27 ), along which the web strip runs, and one of the guide side ( 27 ) opposite ground ( 26 ), wherein the suction devices ( 20 - 25 ) through the ground ( 26 ) through. Device according to claim 5, characterized in that the guide side ( 27 ) and the ground ( 26 ) parallel to each other. Apparatus according to claim 5 or 6, characterized in that the guide side ( 27 ) and the ground ( 26 ) have a distance in the range of 5 to 35 mm, in particular in the range of 10 to 20 mm. Device according to one of claims 1 to 7, characterized in that the suction devices ( 20 - 25 ) with respect to a central axis ( 36 ) parallel to the running direction ( 2 ), are arranged symmetrically. Device according to one of claims 1 to 8, characterized in that at least two adjacent vacuum chambers ( 7 - 12 ) by a partition wall ( 13 - 17 ) are separated from each other, at least in sections an angle to the direction ( 2 ) greater than 95 ° or less than 85 °. Apparatus according to claim 9, characterized in that the partition ( 13 - 17 ) two legs ( 18 . 19 ), which in opposite directions to the direction ( 2 ) are inclined. Apparatus according to claim 10, characterized in that the legs ( 18 . 19 ) Collide in a V-shape. Device according to one of claims 9 to 11, characterized in that at least in a vacuum chamber ( 8th - 12 ) the partition ( 13 - 17 ) in the running direction ( 2 ) on both sides of the suction device ( 21 - 25 ) runs. Device according to one of claims 1 to 12, characterized in that the housing ( 3 ) one the vacuum chamber ( 7 - 12 ) bounding partition ( 28 ) having. Apparatus according to claim 13, characterized in that the intermediate wall ( 28 ) trough-shaped with inclined side walls ( 29 . 30 ) is trained. Device according to claim 14, characterized in that the side walls ( 29 . 30 ) in the direction of gravity to the suction device ( 20 - 25 ) are inclined. Device according to one of claims 13 to 15, characterized in that a compressed air supply line ( 34 . 35 ) for the suction nozzles ( 20 - 25 ) between the housing ( 3 ) and the intermediate wall ( 28 ) is arranged. Device according to one of claims 1 to 16, characterized in that a vacuum chamber ( 7 - 12 ) has a volume of not more than 2 l, in particular not more than 1 l. Device according to one of claims 1 to 17, characterized in that at least one vacuum chamber ( 7 - 12 ) parallel to the running direction ( 2 ) is divided into at least two compartments. Apparatus according to claim 18, characterized in that each compartment in the running direction ( 2 ) is bounded by a V-shaped partition.