EP0908556A2 - Paper machine and process for making a paper web - Google Patents

Abstract

The papermaking machine, to produce a web (10) of paper or cardboard, has an extended press gap (36) along the direction (L) of web travel at the pick-off point (30). At this zone, the smooth surface of the transfer belt (24) towards the web (10) is deflected by the action of a concave trough (38) and the pressure against the pick-off roller (34), to increase the separation of the web (10) from the smooth transfer blanket surface.

Description

The invention relates to a paper machine for producing a material web such as in particular a paper or cardboard web, in which the to be manufactured Material web on the surface of a transfer medium to a Tapping point is transferred, in whose area a at least in essentially open surface, preferably air-permeable Tape is guided over a take-off roller or the like and the Material web decreases from the surface of the transfer medium. It affects also a method for producing a material web according to the preamble of claim 45.

Due to the increasing speeds of paper machines, the disruptive Influences of air movements on the paper web run. Here the web edges are increasingly stressed, which is a Edge fluttering results in folds in the paper and even tearing can lead. The runability and efficiency of the paper machine are severely impaired. As a result, it is necessary that the paper web as it runs through the respective paper machine and especially fully supported when passing through the wet part will and free moves will be avoided.

Various measures for this are already known. For example in a paper machine known from US-A-4,359,828 Endless transfer belt provided by a on a central roller Compact press section provided press nips runs. Here is the paper web on the outside of the transfer belt. She will be up to a transfer point fully supported and without free movement to one Result in dryer fabric. The transfer belt has a much smaller one Porosity as, for example, an intended press felt or the dryer fabric on.

Such a transfer belt with a compared to the porosity of the felts and sieves of lower porosity are also found in US-A-4,483 745 known paper machine used. The porosity of the Transfer ribbon should be so small that it is practically impermeable to water is. Tapes of this type have the advantage that, in contrast to you Press felting the rewetting of the web is reduced or even avoided becomes.

Such impermeable or substantially impermeable However, tapes pose additional problems. For one thing the removal of the paper web from a relatively closed surface having the belt to the open dryer and the other the Keeping the tape clean is problematic.

For example, from US-A-5 240 563 or US-A-5 534 116 known paper machine is said to support the web handover be that the transfer belt with the web in front of a suction roller to the the dryer fabric is guided, for example by deflection devices is distracted. Alternatively, a cylinder can be placed in the transfer belt loop be provided in the area downstream of a suction device is provided, which leads the web away from the transfer belt to the dryer fabric.

These well-known proposed solutions include the disadvantage with it that the contact between the web and the dryer fabric is through only immersing the cylinder in the transfer belt or by immersing it the suction roll in the paper-carrying transfer belt becomes. As a result, the contact can only be strengthened by one further immersion of the relevant elements can be achieved.

This in turn has the disadvantage that the tension of the Transfer ribbon is affected and also the element in question can bend unevenly across the machine width, resulting in different Presses between the web and the dryer fabric leads. Viewed across the width of the machine, the result is an uneven one Transmission, or the pressing cannot be on that for a safe Convey required dimension to be increased.

In addition, those used in the paper machines known to date Inadequate facilities for cleaning the transfer ribbon. This also bring a relatively high mechanical stress on the belt with itself, especially on the so-called conditioning nip occurring bending change is due. Eventually the stake leads touching cleaning elements such as a scraper and brush into one Wear of the surface of the belt, which is particularly disadvantageous is when the surface has a functional roughness like this for example in a paper machine known from EP-B1-0 576 115 the case is.

The invention is based, the paper machine and the task Develop methods of the type mentioned in such a way that in particular Always optimal conditions even at higher running speeds are guaranteed and reliable operation of the paper machine in question is ensured.

With regard to the paper machine, this object is achieved according to the invention solved that an extended in the web running direction at the take-off point Press nip is formed, in the area facing the material web Surface of the transfer agent, both forming a deflected at least substantially concave well as well a pressing force specifically generated in the area of this deflection against the Removal roller is pressed to thereby remove the web of material to support from the transfer agent surface.

Here, the transfer means can, for example, by at least one essential water-impermeable transfer ribbon be formed.

In certain cases it is advantageous if the transfer means at least one has essentially smooth surface.

In an expedient practical embodiment, the surface has functional roughness of the transfer agent.

It is often also advantageous if the surface of the transfer agent is at least essentially closed.

The invention is thus generally related to web acceptance through an air permeable Tissue from a transfer agent applicable, this Transfer agent, for example, by an at least substantially impermeable Band formed and the surface of the transfer agent for example, at least essentially smooth, with a functional Provide roughness and / or at least be essentially closed can.

The transfer means can in particular be an endless transfer belt be formed in the area provided at the delivery point Press nip forming the concave trough inside the Belt loop deflected and through provided in the area of the press nip, arranged inside the belt loop against the Removal roller is pressed.

Accordingly, there is a compression of the Transfer belt on its side facing the material web, while this transfer belt on the opposite, from the material web expands on the opposite side. By combining one such deflection of the transfer belt in the area of the take-off point the simultaneous pressing of the web on the take-off roller with a sufficient minimum contact pressure becomes a highly reliable Transfer of the web from the transfer belt to the one at least essentially Open surface, preferably air-permeable Tape ensured. It is particularly important that the transfer belt is deflected into the interior of the belt loop, so that by the resulting concave deformation of the band of the material web facing surface is compressed, whereby the web loosens and the web in connection with the pressure with the required Minimum contact pressure can be released more easily and transferred without any problems can. This enables an extremely reliable transfer of the web basically through the relaxation that takes place on the one hand and the tension on the other side in connection with the contact pressure corresponding to a minimum contact pressure of the inward deflected transfer belt against the take-off roller can be achieved. In contrast, with a convex deformation or Bulging of the tape, such as when using a internal cylinder occurs (see, for example, US-A-5 534 116), stretched the web and stretched even more onto the transfer belt.

In a preferred embodiment of the invention in practice In the paper machine, the pressing means have one of the material webs facing contact surface, which at least after reaching a certain Pressure is concavely curved. Here, the concave curvature the contact surface is at least substantially complementary to the cylindrical Surface of the take-off roller.

In an expedient embodiment of the paper machine according to the invention the pressing means comprise one made of elastic material existing press roll, the surface of which is due to the pressure on the Pickup roller deformed concavely. The press roller can, for example be a full roll made of elastic material.

In an advantageous alternative embodiment, the pressing means comprise at least one press shoe with one facing the material web concave contact surface.

This press shoe is expedient by several across the machine width distributed pressure elements pressed against the take-off roller. Here the pressure elements can be at least partially independent of each other be acted upon.

The pressing surface of the press shoe is advantageously lubricated hydrodynamic and / or hydrostatic. For example at least essentially within the loop of the transfer belt Water spray pipe extending over the machine width is provided be. Alternatively or additionally, the transfer belt can be on the inside with a wear-resistant and / or friction-reducing layer be provided.

In a preferred embodiment of the invention in practice Paper machine, the transfer belt is formed by a press belt. This press belt can be in the web running direction before at the take-off point provided press nip together with the material web by at least a further press nip serving to treat the material web be guided in a press section.

In an expedient practical embodiment, the press belt formed by the press jacket of a shoe press, the area the tapping point provided, arranged within the press jacket Pressing means in this case at least one press shoe with one of the Include material web facing concave pressure surface.

The press shoe can again by several across the machine width distributed pressure elements to be pressed against the take-off roller, wherein these pressure elements are preferably at least partially independent again can be acted upon by each other.

In this case too, the contact surface of the press shoe can be hydrodynamic again and / or be hydrostatically lubricated.

In a practical embodiment of the paper machine according to the invention forms the shoe press roll assigned to a press section in Web direction in front of the press nip provided at the take-off point together with a respective counter surface at least one of the treatment the further press nip serving the material web. In this case is expediently associated with at least one of the press section felted further press nip and the relevant counter surface by a Counter roll formed against which the press jacket of the shoe press roll can be pressed by at least one press shoe.

The counter roll can be, for example, by a roll with a relative rigid roll shell or alternatively by a shoe press roll with at least one provided in the area of the relevant press nip, arranged within the flexible press shell press shoe.

In a preferred embodiment of the invention in practice Paper machine, the take-off roller is formed by a suction roller. As already mentioned, however, the extraction point is vented not absolutely necessary, since relaxation on the one hand and the tension on the other hand in conjunction with that accordingly a minimum contact pressure against the take-off roller reliable rail takeover already guaranteed. This However, takeover can be done by appropriate suction can be further optimized.

A particularly safe path is achieved when the suction zone the suction roll in the web running direction over that formed at the take-off point Press nip extends.

In the case of the one guided over the take-off roller, at least essentially tape with an open surface can be, for example a dryer fabric of a dryer section. The tapping point can thus, for example, between a press section and a dryer section the paper machine.

The take-off roller can be cambered, even in the event of a deflection to ensure an even surface pressure of the roller.

To achieve the best possible, gentle belt cleaning, are in a preferred embodiment in practice in the direction of web travel behind the delivery point means for a non-contact and / or not abrasive cleaning of the outside of the transfer belt is provided.

These cleaning agents can have at least one jet cleaning device include. At least one jet cleaning device is expedient provided for cleaning by rotating Water jet takes place, for example, through a rotating water nozzle is generated as used for cleaning dryer fabrics becomes. At least one such jet cleaning device can be used as a traversing device Cleaning device be formed.

With such a device, for example, the build-up of coverings from, for example, fine materials or used in papermaking Chemicals can be prevented, or such deposits be removed.

In addition, in the direction of web travel behind the jet cleaning device an essentially extending across the machine width, preferably provided a lower spray pressure spray tube be. It is in the web running direction after the additional spray tube preferably at least one cleaning roller with an associated scraper and / or at least one foil which effects a contactless cleaning intended. With the downstream second spray pipe smaller The belt can be jetted across the entire machine width be sprayed, which in interaction with a contactless Cleaning foil or a cleaning roller Scraper, especially lightly adhering dirt, is removed.

The use of is particularly advantageous Combinations of these devices, creating a gentle even Guaranteed cleaning of the tape and the tape always even is kept clean. Wear on the belt is prevented. By the use of only a few or even just one traversing nozzle high energy water jet is compared to energy consumption a variety of stationary high pressure nozzles.

In a preferred embodiment of the invention in practice Paper machine is behind the transfer belt in the direction of web travel the tapping point is guided over a deflecting roller, the jet cleaning device in front and the additional spray pipe with downstream Cleaning roller and scraper and / or downstream foil behind the Deflection roller are arranged.

The deflection roller can be assigned a scraper around the material web scrape off the belt with the gap open. During normal operation this scraper is not in engagement with the paper machine the deflection roller.

At least the jet cleaning device and / or the additional one A spraying device can be assigned to a heating device.

Another advantageous embodiment of the paper machine according to the invention is characterized by the fact that an endless transfer medium It is provided that the transfer belt is provided at the delivery point Press nip between the take-off roller and at least one counter element is formed and that the at least substantially concave Trough in the surface of the transfer belt facing the material web by pressing the take-off roller into the Transfer ribbon material resulting in one-sided deformation of a corresponding one Transfer ribbon having thickness and flexibility is produced.

In this case, too, the acceptance pressure is replaced by a corresponding one Pressing the take-off roller and / or a corresponding pressing of the pressing means or counter element. The concave trough will however no longer specified by this counter element, but now by pressing the take-off roller into the Transfer ribbon material resulting in one-sided deformation of the transfer ribbon generated, which has a corresponding thickness and flexibility.

The transfer belt can for example again by a press belt and in particular a press jacket.

In the case of using a press jacket, the counter element preferably has a support surface facing the press jacket, the radius of curvature at least substantially equal to the inside radius of the Press sleeve is. The radius of curvature of the support surface can thus in particular also larger than the radius of curvature of the concave trough be determined by the outer diameter of the take-off roller.

The transfer belt can, for example, be made of a material with a hardness exist in the range of about 90 Shore A.

In an expedient practical embodiment, the transfer belt has a thickness greater than or equal to about 3 mm, and preferably is in a range from about 4 mm to about 5 mm.

The method according to the invention is characterized in that in the range the removal point the surface of the material facing the Transfer means to form an at least substantially concave Trough is deflected and that in the area of this deflection Material web and the decreasing band are pressed against each other, thereby the removal of the material web from the transfer medium surface to support.

A transfer agent can, for example, be at least essentially again waterproof transfer tape can be used. The surface the transfer agent can, for example, at least essentially smooth, with a functional roughness and / or at least in be essentially closed.

Further advantageous embodiments of the specified method according to the invention.

The web acceptance according to the invention is, for example, in the area or following the last press nip of a press section of a relevant one Paper machine conceivable. You can in particular through a dryer fabric a dryer section.

Figur 1

eine vereinfachte schematische Teildarstellung einer Ausführungsform einer Papiermaschine, bei der ein die Materialbahn führendes endloses Transferband durch eine aus elastischem Material bestehende Preßwalze gegen eine Abnahmewalze gepreßt wird,

Figur 2

eine vereinfachte schematische Teildarstellung des im Bereich der Abnahmestelle umgelenkten Transferbandes,

Figur 3

eine vereinfachte schematische Teildarstellung einer weiteren Ausführungsform der Papiermaschine, bei der das Transferband durch einen Preßschuh gegen die Abnahmewalze gepreßt wird,

Figur 4

eine vereinfachte schematische Teildarstellung einer weiteren Ausführungsform der Papiermaschine, bei der das Transferband durch den Preßmantel einer Schuhpreßwalze gebildet ist, der durch einen Preßschuh gegen die Abnahmewalze gepreßt wird, und die Materialbahn auf der Oberfläche der Schuhpreßwalze ausgehend von einem Preßspalt zur Abnahmestelle geführt ist, der zwischen der Schuhpreßwalze und einer Gegenwalze mit starrem Walzenmantel gebildet ist,

Figur 5

eine vereinfachte schematische Teildarstellung einer weiteren, mit der der Figur 3 vergleichbaren Ausführungsform der Papiermaschine, bei der auch die Gegenwalze durch eine Schuhpreßeinheit gebildet ist, und

Figur 6

eine vereinfachte schematische Teildarstellung einer weiteren Ausführungsform einer Papiermaschine, bei der zwar das Transferband wieder durch einen Preßmantel und der an der Abnahmestelle vorgesehene Preßspalt wieder zwischen einer Abnahmewalze und einem Gegenelement gebildet ist, die konkave Mulde jedoch nicht mehr durch das Gegenelement vorgegeben, sondern durch eine sich mit einem Eindrücken der Abnahmewalze in das Transferbandmaterial ergebende einseitige Deformation des Transferbandes erzeugt ist.

The invention is explained below using exemplary embodiments with reference to the drawing; in this show:

Figure 1

1 shows a simplified schematic partial illustration of an embodiment of a paper machine in which an endless transfer belt guiding the material web is pressed against a take-off roller by a press roller made of elastic material,

Figure 2

a simplified schematic partial representation of the transfer belt deflected in the area of the take-off point,

Figure 3

1 shows a simplified schematic partial illustration of a further embodiment of the paper machine, in which the transfer belt is pressed against the take-off roller by a press shoe,

Figure 4

a simplified schematic partial representation of a further embodiment of the paper machine, in which the transfer belt is formed by the press jacket of a shoe press roll, which is pressed against the take-off roll by a press shoe, and the material web on the surface of the shoe press roll is guided from a press nip to the take-off point, which is formed between the shoe press roll and a counter roll with a rigid roll shell,

Figure 5

a simplified schematic partial representation of another, comparable to that of Figure 3 embodiment of the paper machine, in which the counter-roller is formed by a shoe press unit, and

Figure 6

a simplified schematic partial representation of a further embodiment of a paper machine, in which the transfer belt is again formed by a press jacket and the press nip provided at the take-off point between a take-off roll and a counter element, but the concave trough is no longer predetermined by the counter element but by one one-sided deformation of the transfer belt resulting from the removal roller being pressed into the transfer belt material.

Figure 1 shows the press section in a simplified schematic representation and part of the dryer section of a paper machine for production a material web 10, which is a paper or cardboard web can act.

The web of material 10 is removed from a screen belt 14 by a felt 12 and through the felt 12 a first press nip S1 of the press section fed between a shoe press roll 16 lying below and a suction roll 18 arranged above it is formed. As with the FIG. 1 shows a further felt 20 around the shoe press roll 16 out, so that there is a double felted press nip S1. Subsequently the material web 10 is passed through a second press nip S2, formed between the suction roll 18 and a further press roll 22 is around which an endless press belt 24 is guided. About that around the press roll 22 guided press belt 24, the material web 10 comes to a third press nip S3, between the press roll 22 and one above arranged further shoe press roll 26 is formed. Around Shoe press roller 26 is in turn guided by a felt 28.

The endless press belt 24 guided around the press roll 22 serves at the same time as a transfer means through which the material web 10 to be produced is subsequently connected at the last press nip S3 of the press section to a take-off point 30 is transferred, in the area of which an at least essentially open-air permeable tape, in the present case Fall a dryer fabric 32 of the dryer section, over a take-off roller 34 is guided and the material web 10 from the surface of the press belt 24 decreases. In the present embodiment, the take-off roller 24 formed by a suction roll.

Basically are in connection with an inventive Web acceptance of transfer means of the most different kind conceivable. A such a transfer belt can in particular by at least essentially waterproof transfer belt be formed. The surface the transfer agent can e.g. at least essentially smooth, with a provided functional roughness and / or at least essentially be closed.

In the present embodiment, the press belt 24 can in particular be at least substantially impermeable to water. The surface this press belt 24 can in particular be smooth and / or closed.

At the take-off point 30 there is an extended press nip in the web running direction L. 36 is formed, in the area of which the material web 10 facing Surface of the press belt 24 both forming at least one deflected substantially concave trough 38 inward as well by a pressing force specifically generated in the area of this deflection the take-off roller 34 is pressed to thereby remove the web of material 10 to support the surface of the press belt 24.

As can be seen from FIG. 1, the material web 10 is subsequently connected to the take-off point 30 through the drying wire 32 the first Drying cylinder 41 supplied to the dryer section.

The press belt 24 serving as a transfer belt is thus in the area of the the tapping point 30 provided press nip 36 with the formation of deflected concave trough 38 into the interior of the belt loop, it additionally by provided in the area of the press nip 36 within the belt loop arranged special pressing against the take-off roller 34 is pressed. In the present case, the pressure means are through a soft press roll 44 made of elastic material is formed, the surface of which is pressed against the take-off roller 34 concavely deformed. This results in a material web 10 facing concave curved contact surface, which is complementary to the cylindrical Surface of the take-off roller 34 is.

The press roller 44 can, for example, be an elastic material Be a full roller.

Thus, in the area of the press nip supporting the web removal 36 the surface of the press belt 24 facing the material web 10 compressed during this press belt 24 on the opposite side undergoes an elongation (see FIG. 2). Because of this under training of the concave trough 38 in connection with the contact pressure corresponding to a minimum contact pressure the take-off roller 34 is the take-off of the material web 10 from the Surface of the press belt 24 and the takeover by the dryer fabric 32 optimally supported.

The suction zone 40 of the take-off roller 34 designed as a suction roller extends in the web running direction L over that formed at the take-off point 30 Press nip 36 addition.

In the web running direction L behind the take-off point 30 there are means for one non-contact and / or non-abrasive cleaning of the outside of the Press belt 24 is provided.

These cleaning agents comprise a jet cleaning device 42 which between the take-off point 30 and a deflection roller 45 outside the Loop of the press belt 24 is arranged In the following case, the Jet cleaning device 42 a rotating nozzle for generating a rotating on the outside of the endless press belt 24 Water jet. This jet cleaning device 42 can also be used as a traversing device Cleaning device be formed.

In the web running direction L behind the deflecting roller 45 there is an additional at least essentially extending across the machine width, preferably lower jet pressure than device 42 Spray tube 46 is provided, on which a cleaning roller 48 with an associated Scraper 50 follows. Basically, the spray tube 46 can also Foil downstream. As can be seen from FIG. 1, a scraper 52 assigned to the deflection roller 45. At least the jet cleaning device 42 and / or the additional spray tube 46 can also be assigned a heating device. In the area of the cleaning roller 48 and the spray tube 46, a collecting container 53 is also provided.

Figure 3 shows a simplified schematic partial representation of another Embodiment of the paper machine in which the serving as a transfer means endless press belt 24 by a press shoe 54 against the take-off roller 34 is pressed. As can be seen from FIG. 3, this press shoe 54 has a concave contact surface facing the material web 10, which are at least essentially complementary to that cylindrical surface of the take-off roller 34. Following the Press shoe 54 or the take-off point 30, the press belt 24 is a Deflection roller 56 out.

The press shoe 54 can be distributed over the machine width by several Pressure elements be pressed against the take-off roller 34, this Pressure elements can be acted upon at least partially independently of one another could be.

The contact surface of the press shoe 54 can be hydrodynamic and / or hydrostatic be lubricated. According to Figure 3 is in the web running direction L before the press shoe 54, a spray tube arranged inside the belt loop 58 provided to the inside of the press cover 24 with the corresponding To apply liquid.

On its inside, the press belt 24 can be wear-resistant and / or a friction-reducing layer.

Otherwise, this embodiment has the same structure as that of Figure 1. So in this case, the material web 10 is following the take-off point 30 through the drying wire 32 to the first drying cylinder 41 fed to the dryer section.

Figure 4 shows a further embodiment of the paper machine. In this The case is the press belt through the press jacket 60 of a shoe press roll 62 educated. The provided in the area of the take-off point 30, within of the press jacket 60 arranged pressing means again include one Press shoe 64. This press shoe 64 also has one of the material web 10 facing concave contact surface, which is at least essentially complementary to the cylindrical surface of the take-off roller 34.

The press shoe 64 can again by several across the machine width distributed pressure elements can be pressed against the take-off roller 34, these contact elements at least partially independent again can be acted upon by each other. The contact surface of the press shoe 64 is again lubricated hydrodynamically and / or hydrostatically.

In the present case, the last press nip S3 of the press section is through the shoe press roller 62 and an overhead, wrapped in felt 28 Press roll 66 formed with a rigid roll shell. The press jacket 60 of the shoe press roller 62 is against the by a press shoe 68 press roller 66 pressed above.

In addition, the shoe press roll 62 forms the second with the suction roll 18 Press gap S2 of the press section. In the area of this second press nip S2 the press jacket 60 of the shoe press roll 62 by a press shoe 70 pressed with a convex contact surface against the suction roller 18 or opposite this supported.

As can be seen from FIG. 4, are behind in the web running direction the take-off point 30 or the press nip supporting the take-off 36 again a jet cleaning device 42 and a spray tube 46 are provided. In this case, the spray tube 46 is followed by a foil 72. In addition, a collecting container 53 is again provided in the area of the foil 72.

Otherwise, this embodiment has the same structure as that of Figure 1, corresponding parts with the same reference numerals are provided.

FIG. 5 shows the section labeled “A” in FIG. 4 of another Embodiment of the paper machine. In this embodiment, the press roll 66 located above, as well as press roll 62 as a shoe press roll formed with a flexible, water-tight press jacket. In the area of the press nip S3, the press sleeves become these Shoe press rolls 62, 66 through opposing press shoes 68, 74 pressed against each other. In this Figure 5 is also the top Press roll 62 to detect wrapping felt 28. Otherwise has this Embodiment the same structure as Figure 4, with each other corresponding parts are again provided with the same reference numerals. The Material web 10 is thus in the present case from the last Press nip S3 of the press section through the press jacket 60 of the shoe press roll 62 transferred to the take-off point, at which through the press nip 36 (compare Figures 1 and 4) supported takeover by a dryer fabric the dryer section takes place.

5 shows another in a simplified schematic partial representation Embodiment of a paper machine. In this case too the transfer belt again through a press jacket 60 and at the take-off point 30 provided press nip 36 again between a take-off roller 36, namely a suction roll, and a counter element 76. The concave trough 38 is, however, different from, for example, that of 4 no longer by the counter element 64 or 76, but by pressing in the take-off roller 34 one-sided deformation of the resulting in the transfer ribbon material Generated transfer belt 60, which has a corresponding thickness d and Owns flexibility.

In the present case, the support surface facing the press jacket 60 has 80 of the counter element 76 has a radius of curvature r, which at least is substantially equal to the inner radius R of the press cover 60. Of the Radius of curvature r of this support surface 80 is thus greater than the radius of curvature the concave trough 38, which is due solely to the outside diameter the take-off roller 34 is determined.

The press jacket 60 can, for example, be made of a material with a Hardness in the range of about 90 Shore A.

In the present embodiment, the press belt 60 has a thickness d, which is greater than or equal to 3 mm and preferably in a range from about 4 mm to about 5 mm.

The removal pressure can be achieved by pressing the removal roller accordingly 34 and / or by pressing the counter element accordingly 76 be generated.

As in the embodiment according to FIG. 4, the press jacket 60 in the area behind the press nip 36 a scraper 82 assigned to the Scrape off the material web 10 from the press belt 60 with the gap open. While this scraper 82 is against the normal operation of the paper machine not in engagement with the press jacket 60.

Otherwise, this embodiment can be the same again, for example Have the same structure as the previously described embodiments, parts which correspond to one another are provided with the same reference symbols are. In the present case, for example, there is again a dryer fabric 32 a dryer section over the take-off roller 34, so that the Material web 10 through this dryer fabric 32 from the surface 78 of the Press cover 60 is removed.

Reference list

10th

Material web

12th

felt

14

Screen belt

16

Shoe press roll

18th

Suction roll

20th

felt

22

Press roll

24th

Press belt

26

Shoe press roll

28

felt

30th

Tapping point

32

Dryer fabric

34

Take-off roller

36

Press nip

38

concave trough

40

Suction zone

41

Drying cylinder

42

Jet cleaning device

44

elastic press roll

45

Deflection roller

46

Spray tube

48

Cleaning roller

50

scraper

52

scraper

53

Collecting container

54

Press shoe

56

Deflection roller

58

Spray tube

60

Press jacket

62

Shoe press roll

64

Press shoe

66

Press roll

68

Press shoe

70

Press shoe

72

Foil

74

Press shoe

76

Counter element

78

surface

80

Support surface

82

scraper

d

thickness

r

Radius of curvature

R

Inner radius

L

Belt running direction

S1

Press nip

S2

Press nip

S3

Press nip

Claims (57)

Paper machine for producing a material web (10), such as in particular a paper or cardboard web, in which the material web (10) to be produced is transferred on the surface of a transfer means (24, 60) to a take-off point (30), in the area of which an at least one substantially open-air, preferably air-permeable tape (32) is guided over a take-off roller (34) or the like and the material web (10) removes from the surface of the transfer means (24, 60),
characterized by
that at the take-off point (30) an elongated press nip (36) is formed, in the area of which the material web (10) facing surface of the transfer means (24, 60) both with formation of an at least substantially concave trough (38 ) is deflected and also pressed by a pressing force specifically generated in the area of this deflection against the take-off roller (34) in order to thereby support the removal of the material web (10) from the transfer medium surface. Paper machine according to claim 1,
characterized by
that the transfer means is formed by an at least substantially water-impermeable transfer belt (24, 60). Paper machine according to claim 1 or 2,
characterized by
that the surface of the transfer means (24, 60) is at least substantially smooth. Paper machine according to one of the preceding claims,
characterized by
that the surface of the transfer agent (24, 60) has a functional roughness. Paper machine according to one of the preceding claims,
characterized by
that the surface of the transfer means (24, 60) is at least substantially closed. Paper machine according to one of the preceding claims,
characterized by
that the transfer means is formed by an endless transfer belt (24, 60) which is deflected into the interior of the belt loop in the region of the press nip (36) provided at the take-off point (30) to form the concave trough (38) and through in the region of the press nip (36) provided, arranged within the belt loop pressure means (44, 54, 64) against the removal roller (34) is pressed. Paper machine according to claim 6,
characterized by
that the pressing means (44, 54, 64) have a pressing surface which faces the material web (10) and which is concavely curved at least after a certain pressing pressure has been reached. Paper machine according to claim 7,
characterized by
that the concave curvature of the contact surface is at least substantially complementary to the cylindrical surface of the removal roller (34). Paper machine according to one of claims 6 to 8,
characterized by
that the pressing means comprise a pressing roller (44) made of elastic material, the surface of which is deformed concavely by the pressure on the removal roller (34). Paper machine according to claim 9,
characterized by
that the press roll (44) is a solid roll made of elastic material. Paper machine according to one of claims 6 to 8,
characterized by
that the pressing means comprise at least one pressing shoe (54, 64) with a concave pressing surface facing the material web (10). Paper machine according to claim 11,
characterized by
that the pressure shoe (54, 64) is pressed against the removal roller (34) by a plurality of pressure elements distributed over the machine width. Paper machine according to claim 12,
characterized by
that the pressure elements can be acted upon at least partially independently of one another. Paper machine according to one of claims 11 to 12,
characterized by
that the contact surface of the press shoe (54, 64) is lubricated hydrodynamically and / or hydrostatically. Paper machine according to claim 14,
characterized by
that a spray tube (58) extending at least substantially across the machine width is provided within the loop of the transfer belt (24, 60). Paper machine according to one of the preceding claims,
characterized by
that the transfer belt (24, 60) is provided on its inside with a wear-resistant and / or friction-reducing layer. Paper machine according to one of the preceding claims,
characterized by
that the transfer belt is formed by a press belt (24, 60). Paper machine according to claim 17,
characterized by
that the press belt (24, 60) in the web running direction (L) in front of the press nip (36) provided at the take-off point (30) together with the material web (10) by at least one further press nip (S2, S3) serving to treat the material web (10) ) a press section is guided. Paper machine according to claim 17 or 18,
characterized by
that the press belt is formed by the press jacket (60) of a shoe press roll (62), the pressure means provided in the region of the take-off point (30) and arranged within the press jacket (60) facing at least one press shoe (64) with one of the material web (10) include concave contact surface. Paper machine according to claim 19,
characterized by
that the pressure shoe (64) is pressed against the removal roller (34) by a plurality of pressure elements distributed over the machine width. Paper machine according to claim 20,
characterized by
that the pressure elements can be acted upon at least partially independently of one another. Paper machine according to one of claims 19 to 21,
characterized by
that the contact surface of the press shoe (64) is lubricated hydrodynamically and / or hydrostatically. Paper machine according to one of claims 19 to 22,
characterized by
that the shoe press roller (62) assigned to a press section forms in the web running direction (L) in front of the press nip (36) provided at the take-off point (30) together with a respective counter surface at least one further press nip (S2, S3) serving to treat the material web (10) . Paper machine according to claim 23,
characterized by
that at least one further press nip (S2, S3) assigned to the press section is felted and the relevant counter surface is formed by a counter roll (18, 66) against which the press jacket (60) of the shoe press roll (62) is formed by at least one press shoe (70, 68) is pressable or supported. Paper machine according to claim 24,
characterized by
that at least one counter roll (66) is formed by a shoe press roll with at least one press shoe (74) provided in the area of the press nip (S3) in question and arranged within the press cover. Paper machine according to one of the preceding claims,
characterized by
that the take-off roller (34) is formed by a suction roller. Paper machine according to claim 26,
characterized by
that the suction zone (40) of the take-off roller (34) extends in the web running direction (L) beyond the press nip (36) formed at the take-off point (30). Paper machine according to one of the preceding claims,
characterized by
that the belt, which is guided over the removal roller (34) and has an at least substantially open surface, is formed by a dryer fabric (32) of a dryer section. Paper machine according to one of the preceding claims,
characterized by
that the take-off roller (34) is cambered. Paper machine according to one of the preceding claims,
characterized by
that in the web running direction (L) behind the take-off parts (30) means (42 - 50) are provided for a contact-free and / or non-abrasive cleaning of the outside of the transfer belt (24, 60). Paper machine according to claim 30,
characterized by
that the cleaning means (42-50) comprise at least one jet cleaning device (42). Paper machine according to claim 31,
characterized by
that at least one jet cleaning device (42) is provided, in which the cleaning is carried out by a rotating water jet. Paper machine according to claim 31 or 32,
characterized by
that at least one jet cleaning device (42) is designed as a traversing cleaning device. Paper machine according to one of claims 30 to 33,
characterized by
that in the web running direction (L) behind the jet cleaning device (42) there is additionally an spray tube (46) which extends at least substantially across the machine width and preferably delivers a lower jet pressure. Paper machine according to one of claims 34,
characterized by
that in the web running direction (L) after the additional spray tube (46) at least one cleaning roller (48) with an associated scraper (50) and / or at least one non-contact cleaning foil (72) is provided. Paper machine according to one of claims 30 to 36,
characterized by
that the transfer belt (24) in the web running direction (L) behind the take-off point (30) is guided over a deflection roller (45, 56) and that the jet cleaning device (42) before and the additional spray tube spray tube (46) with downstream cleaning roller (48) and Scraper (50) and / or downstream foil (72) is arranged behind the deflection roller (45, 56). Paper machine according to claim 36,
characterized by
that the deflection roller (45) is assigned a scraper (52). Paper machine according to one of claims 30 to 37,
characterized by
that at least the jet cleaning device (42) and / or the additional spray tube (46) is assigned a heating device. Paper machine according to one of the preceding claims,
characterized by
that an endless transfer belt (60) is provided as transfer means, that the press nip (36) provided at the take-off point (30) is formed between the take-off roller (34) and at least one counter element (76) and that the at least essentially concave trough (38 ) in the surface (78) of the transfer belt (60) facing the material web (10) by a one-sided deformation of the transfer belt (60) having a corresponding thickness (d) and flexibility resulting from the pressing of the removal roller (34) into the transfer belt material is. Paper machine according to claim 39,
characterized by
that the transfer belt is formed by a press belt (60). Paper machine according to claim 40,
characterized by
that the transfer belt is formed by a press jacket (60). Paper machine according to claim 41,
characterized by
that the counter element (76) has a support surface (80) facing the press jacket (60), the radius of curvature (r) of which is at least substantially equal to the inner radius (R) of the press jacket (60). Paper machine according to one of claims 39 to 42,
characterized by
that the transfer belt (60) consists of a material with a hardness in the range of approximately 90 Shore A. Paper machine according to one of claims 39 to 43,
characterized by
that the transfer belt (60) has a thickness (d) which is greater than or equal to approximately 3 mm and is preferably in a range from approximately 4 mm to approximately 5 mm. Method for producing a material web (10) such as, in particular, a paper or cardboard web, in which the material web (10) to be produced is transferred on the surface of a transfer means (24, 60) to a removal point (30) and in the area of this removal point (30) a preferably air-permeable band (32) having an at least substantially open surface is removed from the surface of the transfer means (24, 60),
characterized by
that in the region of the take-off point (30) the surface of the transfer means (24, 60) facing the material web (10) is deflected to form an at least substantially concave trough (38) and that in the region of this deflection the material web (10) and the decreasing one Band (32) are pressed against each other, to thereby support the removal of the material web (10) from the transfer agent surface. A method according to claim 45,
characterized by
that an at least substantially water-impermeable transfer belt is used as the transfer means. A method according to claim 45 or 46,
characterized by
that a transfer means (24, 60) with an at least substantially smooth surface is used. Method according to one of the preceding claims,
characterized by
that a transfer agent (24, 60) is used, the surface of which has a functional roughness. Method according to one of the preceding claims,
characterized by
that a transfer means (24, 60) with an at least substantially closed surface is used. Method according to one of the preceding claims,
characterized by
that the decreasing belt (32) in the area of the take-off point (30) is guided over a take-off roller (34) or the like. Method according to one of the preceding claims,
characterized by
that an endless transfer belt (24, 60) is used as the transfer means and that the transfer belt (24, 60) is deflected in the region of the take-off point (30) to form the concave trough (38) into the interior of the belt loop. Method according to one of the preceding claims,
characterized by
that the transfer belt (24, 60) is pressed by a press roller (44) made of elastic material so that the removal roller (34) that the surface of the press roller (44) is concavely deformed. Method according to one of claims 45 to 51,
characterized by
that the transfer belt (24, 60) is pressed against the removal roller (34) by at least one press shoe (54, 64) with a concave contact surface facing the material web (10). The method of claim 53
characterized by
that the press jacket (60) of a shoe press roll (62) is used as the transfer belt and the pressure on the take-off roll (34) is carried out by a press shoe (64) of the shoe press roll (62). Method according to one of the preceding claims,
characterized by
that an endless transfer belt (60) is used as the transfer means, that the material web (10) and the belt (32) are pressed against one another between the take-off roller (34) and at least one counter element (76) and that the at least essentially concave trough (38 ) in the surface (78) of the transfer belt (60) facing the material web (10) by a one-sided deformation of the transfer belt (60) having a corresponding thickness (d) and flexibility resulting from the removal roller (34) being pressed into the transfer belt material becomes. Method according to one of the preceding claims,
characterized by
that a corresponding web acceptance takes place in the area or following the last press nip (S3) of a press section. Method according to one of the preceding claims,
characterized by
that a corresponding web acceptance takes place through a dryer fabric (32) of a dryer section.

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