EP0860546B1 - Suction apparatus and press part of a paper machine as well as process to dry a section of a fabric in a paper machine - Google Patents

Abstract

Suction device for use in a machine for producing a sheet and a method to vacuum a web section of a paper machine. The suction device includes a contact surface to place on the web section and a suction box. The suction box is designed to have a vacuum pressure applied to drain the web section. The suction device further includes a control device and a release mechanism or an adjustment mechanism for releasing the suction box from the web section while the vacuum pressure is applied or thereafter so that the web section is guided along the contact surface with less friction and without the web section detaching from the contact device. A method to suction a web section in a paper machine including arranging a contact surface a suction device on the web section and applying a vacuum pressure to the suction device to vacuum the web section. The method further includes operating the paper machine to guide the web section along the contact surface and pressing the web section onto the contact surface by the vacuum pressure. Finally, the method includes releasing the suction device from the web section at the time of or after applying the vacuum pressure thereby guiding the web section along the contact surface with less friction and without the web section detaching from the contact surface.

Description

The present invention relates to a suction device for a paper machine, with a plant section, to plant a web section of the paper machine and with a suction box, to which a vacuum can be applied in order to close the web section drain.

The invention further relates to a press section of a paper machine, with at least one fabric sheet into the moisture is pressed from a paper web to be produced, one Suction device arranged on a web section of the fabric web is to subsequently drain the fabric web.

• Anordnen eines Anlageabschnittes einer Saugvorrichtung an dem Bahnabschnitt,
• Anlegen eines Unterdruckes an die Saugvorrichtung, um den Bahnabschnitt zu besaugen und
• Anfahren der Papiermaschine, so daß der Bahnabschnitt an dem Anlageabschnitt entlang geführt wird, wobei die Bahn durch Unterdruck an den Anlageabschnitt angedrückt wird.

The invention also relates to a method for vacuuming a web section of a paper machine, comprising the steps:

• Arranging a contact section of a suction device on the web section,
• Applying a vacuum to the suction device to vacuum the web section and
• Starting the paper machine so that the web section is guided along the contact section, the web being pressed against the contact section by negative pressure.

Such a suction device and press section and such a method for suctioning a web section is known, for example, from US Pat. No. 3,420,736.

Suction devices are mainly used in paper machines used, webs of the paper machine with or without overlying paper web to suck up the fabric web and / or to dehumidify the paper web. But they are also used to take over the paper web from another fabric web.

In the present context, a fabric web is said to be typically a felt sheet can be understood. The term but should also include forming and drying fabrics.

Due to the negative pressure applied to the suction device between a contact section of the suction device and the Fabric web generates a normal force that compares to a strong friction between the fabric web and the contact section leads. This friction naturally leads to high wear the fabric web and the contact section with itself.

To reduce friction, it is known the suction device on felts in press sections opposite the straight roller connection slightly reset. In this known However, suction device is sucked in air when starting, so that the felt be applied by hand to the suction device got to. Due to the deflection of the web section opposite the straight roller connection becomes one against the one described above Normal force creates force, so that the friction is reduced.

However, creating the track section by hand is tedious and expensive due to the use of specialist personnel.

It is therefore the object of the present invention, a Suction device for a paper machine, a press section a paper machine and a method for vacuuming a Specify web section of a paper machine, the friction between a contact section on the suction device and the Track section is reduced without using specialist personnel to have to.

This task is in the suction device mentioned above solved in that the suction device is a control device and one so controlled by the control device Relief mechanism has that the suction device in Operation with negative pressure applied to the web section is relieved, so that the friction between the web section and the plant section is reduced. In the above Press section is the task through the use of the invention Suction device released.

In the above-mentioned method for vacuuming a web section a paper machine, the task is through the step solved the suction device with or after putting on the Relieve negative pressure against the web section, so that the track section with reduced friction on the Plant section is guided along without the Path section detaches from the contact section.

The task is thus solved completely.

By the measure, the suction device opposite the web section to relieve only when there is a vacuum on this Device is applied, the friction is reduced without that it is necessary to touch the track section by hand against the Press section of the suction device. Under a Relief mechanism in this context should be of every kind be understood by mechanism that allows the through the normal force caused by the negative pressure between the system section and to reduce track section, so that also reduces the friction. The relief mechanism is included in other words a mechanism that is one of these normal forces opposite force is generated. It is understood that the Control device for controlling the relief mechanism Can be part of the higher-level paper machine control. Under a control device in the present context Any kind of facility can be understood that is the controller allows the normal force between the system section and Only reduce the web section if there is already a vacuum is applied to the suction device, if not more there is the possibility that the track section again from the plant section resolves. This can safely avoid that the suction device sucks in air and its intended Can no longer function. Due to the lower friction is less power to drive the paper machine required.

The relief mechanism preferably acts on the suction device force controlled to this opposite the web section to relieve.

This ensures that the relief mechanism generated force acting against the normal force set directly can be. The web section detaches from the contact section when falling below a certain difference between the Normal force and that generated by the relief mechanism Force. Because in this embodiment this difference is direct is adjustable, the difference between the normal force and the force generated by the relief mechanism be maximized. On the one hand, this makes it very low Friction reached. On the other hand, it can be safely ruled out that the web section detaches from the contact section.

According to a further preferred embodiment, the Relief mechanism as an adjustment mechanism for the suction device formed, the control device the adjustment mechanism activated in operation with negative pressure applied, that the suction device relative to the web section by one such amount is withdrawn that the frictional force between the Plant section and the web section is reduced without the web section separates from the contact section.

In this embodiment, the generation takes place against the Normal force directed force in that the suction device through the adjustment mechanism opposite the web section straight roller connection is lifted off.

The adjustment mechanism is preferably by a mechanism formed by means of which the suction device for maintenance purposes can be lifted off the track section.

Such maintenance mechanisms are known and are used to to lift the suction device in relation to the web section in order to to be able to maintain or clean the suction device. Through the Can use this mechanism for the adjustment mechanism the paper machine can be built much more compact, since no additional mechanism must be installed. It is alone necessary, the control device with the existing one To couple the maintenance mechanism so that the maintenance mechanism in operation with negative pressure applied by a certain amount is lifted off to the friction between the web section and to reduce the plant section.

It is still preferable if the adjustment mechanism is in the lifted position can be locked or self-holding.

This measure is avoided throughout Operation to supply power to the adjustment mechanism. The This can reduce the energy consumption of the paper machine become. The use of a is particularly preferred Spindle mechanism for the adjustment mechanism as a Spindle mechanism is particularly easy to control, for example by an electric motor, and there a spindle mechanism on the other hand is self-retaining. Alternatively it is also possible for the adjustment mechanism a hydraulic or pneumatic piston / cylinder arrangement. In this The catch could fall through in the off position flipping a valve.

According to a further preferred embodiment, the Adjustment mechanism on both sides of the web section the suction device, wherein the contact section with a concave crowning is provided.

The convex deflection becomes due to the concave crowning balanced, which is generated by the adjustment mechanism on both sides of the web section on the suction device attacks the normal force generated by the negative pressure however acts in the area of the track section.

The control device preferably controls the relief mechanism depending on the operating parameters of the paper machine on.

These operating parameters can be the web tension, the differential pressure at the suction device, the type of fabric, the web runtime, the suction device length, by just a few To name examples.

The relief mechanism preferably has a pressure-driven one Bellows arrangement on.

With this measure it is not necessary for the relief mechanism to provide its own drive source, because for the A suction device is provided anyway.

It is preferred if the bellows arrangement on the Facing section facing away from the suction device and when the bellows assembly is driven by the vacuum is applied to the suction device.

This measure has the advantage that the bellows arrangement Suction device with an even greater force from the web section takes off, the greater the negative pressure applied.

It is also preferable if the bellows arrangement is a row of individual bellows distributed across the web running direction are arranged.

As a result, the bellows arrangement on the suction device applied force evenly over the length of the suction device distributed. It is therefore avoided that the suction device deflects transversely to the web running direction, so that one across the width uniform suction power of the web section is achieved.

According to a further preferred embodiment, the System section on two squeegees, between which one Suction opening is formed, the squeegees around Are inclined to each other.

By lifting the suction device from the web section is the part of the web section leading to the suction device at an obtuse angle to the part leading away from the suction device inclined. By the measure, the squeegees by one corresponding angles to each other, the corresponding lie Parts of the track section each on a large area the squeegees so that the vacuum generated normal force spread over a larger area what leads to less friction overall.

It is still preferable if the plant section two Has suction strips between which a suction opening is formed and if the squeegees on their outer edges are rounded.

Especially with suction bars inclined at an angle to each other this is an advantage since the squeegees are not in the lifted state with its outer edges on the web section attack. Rounding the outer edges eliminates the danger Avoid damage to the track section.

According to a further preferred embodiment, the System section on two squeegees, between which one Suction opening is formed, the squeegees in relation are concavely curved on the track section.

This makes it possible to directly the suction device Assign web section of a roller of the paper machine wraps. The concave curvature is preferably at the Adjusted radius of the roller.

It is understood that the above and those below Features to be explained not only in each case specified combination, but also in other combinations or can be used alone without the scope of the to leave the present invention.

Fig. 1

eine schematische Seitenansicht eines Ausschnittes aus einer Pressenpartie einer Papiermaschine mit einer erfindungsgemäßen Saugvorrichtung;

Fig. 2

eine Ausführungsform der Saugvorrichtung von Fig. 1 in einer nicht gegenüber dem Bahnabschnitt abgehobenen Stellung;

Fig. 3

die Saugvorrichtung von Fig. 2 in einer gegenüber dem Bahnabschnitt abgehobenen Stellung;

Fig. 4

eine weitere Ausführungsform einer erfindungsgemäßen Saugvorrichtung;

Fig. 5

eine weitere Ausführungsform einer erfindungsgemäßen Saugvorrichtung zur Verwendung an einem Bahnabschnitt an einer Walze;

Fig. 6

eine Draufsicht auf eine weitere Ausführungsform einer erfindungsgemäßen Saugvorrichtung;

Fig. 7

eine weitere alternative Ausführungsform einer erfindungsgemäßen Saugvorrichtung; und

Fig. 8

eine weitere alternative Ausführungsform einer erfindungsgemäßen Saugvorrichtung.

Embodiments of the invention are shown in the drawing and are explained in more detail in the following description. Show it:

Fig. 1

a schematic side view of a section of a press section of a paper machine with a suction device according to the invention;

Fig. 2

an embodiment of the suction device of Figure 1 in a position not raised against the web section.

Fig. 3

the suction device of Figure 2 in a raised position relative to the web section.

Fig. 4

a further embodiment of a suction device according to the invention;

Fig. 5

a further embodiment of a suction device according to the invention for use on a web section on a roller;

Fig. 6

a plan view of a further embodiment of a suction device according to the invention;

Fig. 7

a further alternative embodiment of a suction device according to the invention; and

Fig. 8

a further alternative embodiment of a suction device according to the invention.

In Fig. 1 is a section of a press section Paper machine generally designated by the reference number 10.

In this section of the press section, a paper web 12 between a bottom felt 14 and a top felt 16 into one Press nip 18 out, which is formed by two press rolls 20, 22 becomes.

The paper web 12 runs on the bottom felt 14 in the press nip 18 a. The top felt 16 is around a series of felt guide rolls 24 out. In the press nip 18 is by means of the press rolls 20, 22 moisture present in the paper web in the felts 14, 16 pressed. To drain the upper felt 16 is the Upper felt 16 around two felt guide rollers arranged downstream of the press nip 18 24 out, between which a suction device is arranged, which is generally indicated by reference number 30.

The suction device 30 has a contact section 34 for contact on the web section formed between the two felt guide rollers 24 32 of the upper felt 16 and a suction box 36, to which a vacuum can be applied.

The suction device 30 can what the contact section 34 and the suction box 36, of a conventional type, so that there is no detailed description here becomes.

Unlike conventional suction devices, there is a relief mechanism 38 provided by a control device 40 is controlled.

The relief mechanism 38 acts in the most general case that he on the arrangement of the suction box 36 and the system section 34 exerts a force. That through the relief mechanism 38 generated force acts against a normal force caused by the vacuum applied to the suction box 36 is generated and which presses the web section 32 against the contact section 34. By the counterforce generated by the relief mechanism 38 there is a lower resulting force between Track section 32 and contact section 34 acts so that the friction is reduced between these two parts. Through this Relief of the suction device 30 with respect to the web section 32 will therefore wear both on the felt 16 as well reduced on the contact section 34.

The key, as I said, is that through the relief mechanism 38 one of the normal force generated by the negative pressure counteracting force is generated. As a rule, it is for this necessary, the suction device 30 opposite the web section 32 to raise. The lifting can be perpendicular to the web running direction or at an angle to this. However, it can also be possible, the suction device 30 opposite the web section 32 by relieving a piston force, for example, the suction device 30 is not significantly opposite the web section 32 is raised.

In Fig. 1 there is also a sensor 42 for the web tension indicated, which is connected to the control device 40. With this configuration it is possible to discharge the Suction device 30 in relation to the web section 32 in dependence to regulate from the web tension. In addition, it is possible, the function of the relief mechanism 38 depending set or regulate other operating parameters. These operating parameters can be, for example: the type of felt used, the felt runtime, the suction device length, the differential pressure at the suction device.

The control device 40 can be a separate, decentralized one Control device or as part of a central, not Paper machine control system shown may be provided.

FIGS. 2 and 3 show an embodiment of the invention shown, in which the relief mechanism 38 as an adjustment mechanism 44 is formed. The adjustment mechanism 44 has a lever 46, which at a pivot point 48 on the fixed Chair of the paper machine is pivotally mounted. On middle part of the lever 46 is connected via a fulcrum 52 connected to the suction box 36. The free end of the lever 46 is coupled to a drive 54, by means of which the lever the pivot point 48 can be pivoted around. The drive 54 is with the control device (not shown in FIGS. 2 and 3) 40 connected.

Before applying a vacuum to the suction box 36 the Suction device 30 is the lever 46 in one Position that the contact section 34 on the one straight roller connection forming web section 32 abuts. With or after the application of the vacuum, the lever 46 is an angle 56 pivots, taking the suction device 30 with it. By the vacuum does not release the web section 32 from that Contact section 34, so that the web section 32 as a result is deflected by an amount 58. The by the deflection of the web section 32 produces a tensile stress Force 60, against the normal force generated by the vacuum acts with which the web section 32 against the contact section 34 is pressed. This results in between the track section 32 and the contact section 34 a lower friction, what overall, less wear and less Power consumption of the paper machine leads.

The part of the adjustment mechanism formed by the lever 46 44 can be part of a conventional, in many paper machines already existing maintenance mechanism, by means of which the suction device for maintenance or cleaning purposes The paper machine 10 comes to a standstill from the web section 32 can be lifted off. In this case, the realization of the Adjustment mechanism 44 only one drive 54 with one suitably programmed control device 40 can be provided.

4 shows a further embodiment of a suction device 64 shown. The relief mechanism 38 is only in FIG. 4 indicated schematically.

The suction device 64 has two offset in the web running direction arranged suction strips 66, 68, between which one Suction opening 69 is formed. The suction strips 66, 68 are inclined at an angle 70 to each other. The outer edges 72 of the suction strips 66, 68 are each rounded.

The angular arrangement of the two suction strips 66, 68 reaches that part running to the suction device 64 of the web section 32 and that of the suction device 64 running part of the web section 32 when the suction device is lifted off 64 aligned parallel to the suction strips 66, 68 are. This will reduce the friction between the squeegees 66, 68 and the track section 32 due to the flat system further decreased.

When not lifted off, the web section 32 becomes exclusive from the outer edges 72 of the suction strips 66, 68 touched. Rounding them off will damage the Track section 32 avoided.

Another embodiment of a suction device is shown in FIG. 5 generally indicated with the reference number 76. The relief mechanism 38 is again only shown schematically. The contact section of the suction device 76 consists of two Suction strips 80, 82, between which a suction opening 83 is trained. The bottom of the squeegees 80, 82 is concave with a radius that corresponds to the radius of a corresponds to ventilated roller 78 around which the web section 32 is looped around in this embodiment. Thus suitable the suction device 76 in particular for the suction of Track sections that wrap around rollers.

In Figures 6, 7 and 8 are three different embodiments of relief mechanisms 38 or adjustment mechanisms 44 shown.

In Fig. 6, arrows 86 indicate how the negative pressure is applied to the suction box 36 of the suction device 30.

The relief mechanism 38 is through two piston / cylinder assemblies 90 formed on both sides of the suction box 36 of the track section 32 attack.

In Fig. 7, an adjustment mechanism 44 is shown by two spindle assemblies 92 is formed on both sides of the Attack web section 32 (not shown in Fig. 7). A motor 94 is assigned to each of the spindle mechanisms 32.

FIG. 7 also shows that the contact section 34 with a crown extending transversely to the web section 32 96 is provided. Due to the lateral attack of the spindle mechanisms 92, the suction device 30 is applied Vacuum 86 bent. This deflection is raised in the Condition compensated by the crowning 96, so that a flat contact of the plant section on the web section 32 is guaranteed. The crowning 96 is in FIG. 7 For illustration purposes, exaggerated.

In the embodiment of Fig. 8, the relief mechanism is 38 formed by a bellows arrangement 98. The bellows arrangement 98 is between the suction box of the suction device 30 and the Chair of the paper machine 10 on the plant section 34 arranged opposite side.

The bellows assembly 98 is driven by vacuum to the suction device compared to the (not shown in Fig. 8) Lift off section 32. For this purpose the bellows arrangement 98 via a channel 100 with the source for the Vacuum 86 connected to the suction device 30 for Suction of the web section 32 is created. This has the Advantage that the bellows assembly 98 on the suction device 30 applied force directly from the size of the negative pressure 86 depends, which is applied to the suction device 30. at this embodiment is not a separate control device 40 necessary. The bellows arrangement 98 is controlled automatically by the bellows arrangement via channel 100 is connected to the vacuum 86. There is no negative pressure 86 on, the bellows arrangement 98 is relaxed and the contact section 34 lies on the web section forming a straight roller connection 34. As soon as a vacuum 86 is applied, the Suction device 30 with increasing vacuum 86 more and more the straight roller connection is lifted off, creating a force is generated by the vacuum 86 between the system section 34 and path section 32 counteracts normal force generated. This force is directly proportional to the normal force. If direct proportionality is not desired, it can also in this embodiment, a control device 40 is provided be via a pneumatic acting on the channel 100 Actuator sets a desired characteristic.

For uniform distribution of the bellows arrangement 98 Exerted force may make sense to spread a number of Individual bellows arranged over the length of the suction device 30 To provide 102, which is only indicated schematically in Fig. 8 are.

Correspondingly, instead of that in FIGS. 6 and 7 shown, on both sides of the web section 32-on the suction device A mechanism is provided for 30 attacking mechanisms be uniform over the length of the suction device 30 attacks this to prevent deflection. In this It would also not be necessary to cover the plant section with a case To provide crowning 96, as shown in Fig. 7.

Claims (15)

1. Suction apparatus (30; 64; 76) for a papermaking machine (10), having a contact section (34; 66, 68; 80, 82) to make contact with a web section (32), and having a suction box (36) to which a vacuum (86) can be applied in order to dewater the web section (32), the web being pressed against the contact section (34; 66, 68; 80, 82) by the vacuum (86), characterized in that the suction apparatus (30; 64; 76) has a control device (40) and a relief mechanism (38), which reduces a normal force, caused by the vacuum, between the contact section (34; 66, 68; 80, 82) and the web section (32) by producing an opposing force and is driven by the control device (40) in such a way that the suction apparatus (30; 64; 76) is relieved of load with respect to the web section (32) during operation with a vacuum (86) applied, so that the friction between the web section (32) and the contact section (34; 66, 68; 80, 82) is reduced without the web section (32) being separated from the contact section (34; 66, 68; 80, 82).
2. Suction apparatus according to Claim 1, characterized in that the relief mechanism (38) acts on the suction apparatus (30; 64; 76) under force control, in order to relieve the latter of load with respect to the web section (32).
3. Suction apparatus according to Claim 1, characterized in that the relief mechanism (38) is constructed as an adjusting mechanism (44) for the suction apparatus (30; 64; 76), the control device (40) driving the adjusting mechanism (44) during operation with vacuum (86) applied in such a way that the suction apparatus (30; 64; 76) is raised with respect to the web section (32) by an amount (58), so that the frictional force between the contact section (34; 66, 68; 80, 82) and the web section (32) is reduced without the web section (32) being separated from the contact section (34; 66, 68; 80, 82).
4. Suction apparatus according to Claim 3, characterized in that the adjusting mechanism (44) is formed by a mechanism by means of which the suction apparatus (30; 64; 76) can be raised off the web section (32) for maintenance purposes.
5. Suction apparatus according to Claim 3 or Claim 4, characterized in that the adjusting mechanism (44) can be latched or is self-retaining in the raised position.
6. Suction apparatus according to one of Claims 3 - 5, characterized in that the adjusting mechanism (44) acts on the suction apparatus (30; 64; 76) on both sides of the web section, and in that the contact section (34) is provided with concave cambering.
7. Suction apparatus according to one of Claims 1 - 6, characterized in that the control device (40) drives the relief mechanism (38) as a function of operating parameters of the papermaking machine (10).
8. Suction apparatus according to one of Claims 1 - 7, characterized in that the relief mechanism (38) has a pressure-driven bellows arrangement (98).
9. Suction apparatus according to Claim 8, characterized in that the bellows arrangement (98) acts on the suction apparatus (30; 64; 76) on the side which faces away from the contact section (34; 66, 68; 80, 82) and is driven by the vacuum (86) which is applied to the suction apparatus (30; 64; 76).
10. Suction apparatus according to Claim 8 or Claim 9, characterized in that the bellows arrangement (98) has a row of individual bellows (102) which are arranged distributed transversely with respect to the web running direction.
11. Suction apparatus according to one of Claims 1 - 10, characterized in that the contact section (66, 68) has two suction strips (66, 68), between which a suction opening (69) is formed, and in that the suction strips (66, 68) are inclined at an angle (70) to each other.
12. Suction apparatus according to one of Claims 1 - 11, characterized in that the contact section (66, 68) has two suction strips (66, 68), between which a suction opening (69) is formed, and in that the suction strips (66, 68) are rounded off at their outer edges (72).
13. Suction apparatus according to one of Claims 1 - 10, characterized in that the contact section (80, 82) has two suction strips (80, 82), between which a suction opening (83) is formed, and in that the suction strips (80, 82) are curved concavely in relation to the web section (32, 78).
14. Press section (10) of a papermaking machine, having at least one fabric web (14, 16) into which moisture from a paper web (12) to be produced is pressed, a suction apparatus (30; 64; 76) being arranged on a web section (32) of the fabric web (14, 16) in order subsequently to dewater the fabric web (14, 16), characterized in that the suction apparatus is a suction apparatus (30; 64; 76) according to one of Claims 1 - 13.
15. Method of applying suction to a web section (32) of a papermaking machine (10), having the following steps:

    arranging a contact section (34; 66, 68; 80, 82) of a suction apparatus (30; 64; 76) on the web section (32),

    applying a vacuum (86) to the suction apparatus (30; 64; 76) in order to apply suction to the web section (32), and

    starting up the papermaking machine (10) so that the web section (32) is guided along on the contact section (34; 66, 68; 80, 82), the web (32) being pressed against the contact section (34; 66, 68; 80, 82) by the vacuum (86),

    characterized by the step of relieving the load on the suction apparatus (30; 64; 76) with respect to the web section (32), with or following the application of the vacuum (86), by a relief mechanism (38) which is driven by a control device (40) and which reduces the normal force caused by the vacuum between the contact section (34; 66, 68; 80, 82) and web section (32) by producing an opposing force, so that the web section (82) slides along on the contact section (34; 66, 68; 80, 82) with reduced friction without the web section (32) being separated from the contact section (34; 66, 68; 80, 82).

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