DE102005013627A1 - shooting method - Google Patents

Abstract

The invention relates to a method for closing an extended nip of a smoothing arrangement for smoothing a paper, cardboard, tissue or another fibrous web (1) in a machine for producing and / or finishing the same, which between a smoothing roll (2) and a arranged underneath counter roll (3), wherein the smoothing roll (2) has a flexible roll shell (4) which is pressed by a pressing element (5) to the counter roll (3). DOLLAR A The risk of a web break when closing the calendering nip is to be reduced by that Mantelspann- and / or -saugmittel are provided which ensure that the roll shell (4) during closing of the calendering preferably over its entire length on the pressing surface of the pressing element (5) is present.

Description

The The invention relates to a method for closing a lengthened one calendering nip a smoothing arrangement for smoothing a paper, board, tissue or other fibrous web in a machine for the production and / or refinement thereof, which between a smoothing roll and an underlying counter roll is formed, wherein the smoothing roller has a flexible roll shell, of a pressing element pressed to the counter roll becomes.

Because of the width of the smoothing roll, which can reach values of 10 m, the flexible one Roll shell when open polishing nip due to its own weight on a slack. The slack is while in the middle of the roll largest.

hereby collects in the center of the roll on the inside of the roll shell more lubricating oil as at the edges, which reinforces this effect.

To the transfer of the Fibrous web becomes the smoothing nip with rotating smoothing and counter rollers closed.

On Due to the sag, the center of the roll mantle comes first the counter roll in contact, resulting in an increased load on the middle of Roll mantle and can lead to a demolition of the fibrous web.

This results in particular from the fact that the roll shell in the area of the smoothness gap Reason of its larger radial Distance to the axis in the middle range also a higher rotational speed as at the edges having the roll shell.

The The object of the invention is therefore, in particular the risk of Tear off the fibrous web with the simplest possible means reduce.

According to the invention was solved the task by that jacket tensioning and / or suction means are provided which ensure that the roll shell when closing the calendering preferably on his whole length at the pressing surface of the Pressing element abuts.

There the pressing surface is largely straight in the axial direction, is in adjacent roll shell prevents it from sagging. Consequently will when closing of the smoothness gap guaranteed that the roll shell over his entire length essentially comes into contact with the counter roll at the same time.

In addition, will thus also ensuring that the speed of the roll shell in the area of the calendering nip in the middle region coincides with that at the edges of the roll shell.

there should be the speed of the roll mantle with the peripheral speed match the counter roll.

in the The result is the roll jacket against uneven loading and the fibrous web from excessive stress due to a also only partially occurring differential speed between Retains roll shell and counter roll.

For this it is possible in an advantageous way that the pressing element as a jacket clamping means before or during the closing of the smoothness gap as far as pressed in the direction of the backing roll that the roll shell preferably over his entire length at the pressing surface the pressing element rests, the roll shell only then with the counter roll is brought into contact.

in the general leads this causes the pressing element beyond its operating position pressed in the direction of the counter roll is and thus tensioned the roll shell. After contact of the roll mantle with the counter-roller then the pressing element can be relieved again.

In complement or separately, but it may also be advantageous if the roll shell on jacket clamping means before or during the closing of the calendering nip, preferably in the form of axially extending in the roll shell guide rails, which the roll shell outside Press the pressing element radially outward, is stretched so that the roll shell preferably over his entire length at the pressing surface of the pressing element is applied, wherein the roll shell only then with the Counter roller is brought into contact.

in this connection Is it possible, that the jacket clamping means radially against the pressing direction of the pressing element acts and so raises the roll shell, until this completely the pressing surface of the pressing element is applied.

In complement for this or independently can However, the jacket clamping means also oblique with a direction of action, preferably Both sides of the and symmetrical to the press plane.

This causes the roll shell with a component is pressed transversely to the pressing direction from the circular shape and thereby tensioned. As a result of this tensioning, the roll shell is attracted to the pressing element.

The guide rails run over axially the entire length the roller and worry while of the operation for a cylindrical shape of the flexible roll shell.

At least in addition this action is It is also advantageous if the roll shell during the closing of the Glättspaltes about that Jacket suction, preferably in the form of suction openings provided pressing element sucked to the pressing surface of the pressing element becomes.

For this have to the suction openings only be connected to a vacuum source.

there The lubricant is sucked out of the roll shell, which the weight decreases.

If the suction forces are sufficiently large or the roll mantle is correspondingly light, the suction of the Roll mantle as the sole means of solving the inventive task be used.

Around it is counteracting the sag of the roll mantle also advantageous if the air pressure in the roll shell during the closing of the calendering nip elevated becomes, whereby the air pressure higher as while the operation of the smoothing roller is.

to Formation of a prolonged Pressing gap can the smoothing and the counter roll have a flexible roll shell, which the Formation of a flat extended calendering nip allowed.

Mostly is however present the counter roll is cylindrical, which is why the pressing element to form an elongated Glättspaltes one concave pressing surface has.

Especially at the concave pressing surface it is sufficient at all solutions, when the roll shell during of closing of the smoothness gap only in contact with the radially protruding areas of the pressing surface is brought.

following the invention is based on an embodiment be explained in more detail. In the accompanying Drawing shows:

1 a schematic cross section through a smoothing arrangement and

2 : another smoothing arrangement with sliding guide rails 7 ,

In both cases, the smoothing nip of the smoothing arrangement of a paper machine is obtained from a smoothing roll 2 and an underlying cylindrical counter-roller 3 educated.

It owns the smoothing roller 2 a flexible roll shell 4 made of fiber-reinforced plastic, which is used to form a prolonged nip of a pressing element 5 with concave pressing surface to the counter roll 3 is pressed.

The extended smoothing gap causes because of the extended residence time of the fibrous web 1 in Glättspalt a significant improvement in the smoothing result while preserving the same.

For shaping, the flexible roll shell 4 from the inside over several axially extending guide rails 6 . 7 supported. While a guide bar 6 on the opposite side of the pressing element 5 is arranged, there is a guide strip 7 symmetrical to the press plane 9 in the two lower quadrants of the smoothing roller 2 ,

In addition, the shape is still supported and counteracted a slack that the air pressure in the roll shell 4 is increased during the closing of the calendering nip, wherein the air pressure is higher than during operation of the calender roll 2 is.

This is the fibrous web 1 only completely through the open Glättspalt before it is closed. To do this as gently as possible and without differential speed between the roll shell 4 and the counter roll 3 To ensure, not only the roll shell 4 at the same speed as the counter roll 3 accelerates, but also the roll shell 4 during the closing of the calendering nip with the protruding parts of the concave pressing surface of the pressing member 5 brought into contact.

Since the pressing surface extends in the axial direction largely straight, thus has the roll shell 4 in the region of the smoothing gap over its entire length substantially the same radial distance to the roll axis.

This is the basis for making the roll shell 4 over its entire length at least about the same time and at the same speed with the counter roll 3 can be brought into contact.

This minimizes the load on the rollers mantels 4 and prevents a break in the fibrous web 1 when closing the Glättspaltes ago.

According to 1 the tensioning of the roll mantle takes place 4 in that the pressing element 5 as jacket tensioning means before or during the closing of the smoothing gap as far as in the direction of the counter roll 3 is pressed that the roll shell 4 over its entire length partly at the pressing surface of the pressing element 5 is applied. In this case, the roll shell 4 from the guide rails 6 . 7 held.

Only then is the roll shell 4 with the counter roll 3 brought into contact.

In order to keep the contact of the roll mantle 4 on the pressing surface of the pressing element 5 yet to support, has these suction holes 8th which are connected to a vacuum source and so the roll shell 4 to the pressing element 5 suck.

In contrast, shows 2 an embodiment in which the roll shell 4 before or during the closing of the smoothing gap via jacket clamping means in the form of axially in the roll shell 4 extending guide rails 7 , which the roll shell 4 outside the pressing element 5 Press radially outward, is stretched so that the roll shell 4 over its entire axial length partly on the pressing surface of the pressing element 5 is applied.

Again, the roll shell 4 only then with the counter roll 3 brought into contact.

The guide rails 7 in the two lower quadrants of the smoothing roller 2 act here obliquely, but symmetrically to the press level 9 and press the roll shell 4 so across the press 9 from its circular shape.

In both versions, the roll shell 4 on the pressing element 5 opposite side of a guide rail 6 stabilized.

Claims (7)

Method of closing an extended nip of a straightener for smoothing a paper, board, tissue or other fibrous web ( 1 ) in a machine for the production and / or refinement thereof, which between a smoothing roll ( 2 ) and an underlying counter-roller ( 3 ), wherein the smoothing roll ( 2 ) a flexible roll shell ( 4 ) possessed by a pressing element ( 5 ) to the counter roll ( 3 ) is pressed, characterized in that Mantelspann- and / or -saugmittel are provided which ensure that the roll shell ( 4 ) when closing the smoothing gap preferably over its entire length at the pressing surface of the pressing element ( 5 ) is present. Method according to claim 1, characterized in that the pressing element ( 5 ) as jacket tensioning means before or during the closing of the smoothing gap as far as in the direction of the counter-roller ( 3 ) is pressed, that the roll shell ( 4 ) preferably over its entire length on the pressing surface of the pressing element ( 5 ) is applied, wherein the roll shell ( 4 ) only afterwards with the counter-roller ( 3 ) is brought into contact. Method according to claim 1 or 2, characterized in that the roll shell ( 4 ) via jacket clamping means before or during the closing of the calendering nip, preferably in the form of axially in the roll shell ( 4 ) extending guide rails ( 6 . 7 ), which the roll shell ( 4 ) outside the pressing element ( 5 ) is pressed radially outward, is tensioned such that the roll shell ( 4 ) preferably over its entire length on the pressing surface of the pressing element ( 5 ) is applied, wherein the roll shell ( 4 ) only afterwards with the counter-roller ( 3 ) is brought into contact. A method according to claim 3, characterized in that the jacket clamping means radially against the pressing direction of the pressing element ( 5 ) and / or with a direction of action obliquely to the press plane ( 9 ), preferably on both sides of and symmetrical to the press plane ( 9 ) Act. Method according to one of the preceding claims, characterized in that the roll shell ( 4 ) during the closing of the calendering nip via the jacket suction means, preferably in the form of one with suction openings ( 8th ) provided pressing element ( 5 ) to the pressing surface of the pressing element ( 5 ) is sucked. Method according to one of the preceding claims, characterized in that the air pressure in the roll shell ( 4 ) is increased during the closing of the calendering nip, wherein the air pressure is higher than during the operation of the calender roll ( 2 ). Method according to one of the preceding claims, characterized in that the speed of the roll mantle ( 4 ) in the smoothing gap area when closing the calendering nip with the peripheral speed of the counter-roller ( 3 ) is at least brought into approximate agreement.