WO2021032352A1

WO2021032352A1 - Web holding device

Info

Publication number: WO2021032352A1
Application number: PCT/EP2020/068808
Authority: WO
Inventors: Heinrich Hütz
Original assignee: Voith Patent Gmbh
Priority date: 2019-08-20
Filing date: 2020-07-03
Publication date: 2021-02-25
Also published as: EP4017821A1; EP4017821C0; CN114222710A; EP4017821B1; DE102019122312A1; DE102019122312B4

Abstract

The invention relates to a device for holding a fibrous web (1) or a start and/or end of a fibrous web (1), more particularly a paper, cardboard or tissue web, having at least two holding elements (3, 4) opposing one another with respect to the fibrous web (1) and running transverse to the web running direction (2), of which at least one can be moved perpendicular to the fibrous web (1) by means of an actuator (5). The aim of the invention is to make possible a compact and light design in that at least one of the opposing holding elements (3, 4) has at least one controllable thrust body (6) braced on the holding element (3, 4) and directed to the fibrous web (1) and the opposing holding elements (3, 4) have magnetic force elements (7, 8) which attract these holding element (3, 4) together.

Description

Railway stopping device

The invention relates to a device for holding a fibrous web or a beginning and / or end of a fibrous web, in particular a paper, cardboard or tissue web with at least two holding elements opposite the fibrous web and running transversely to the web running direction, at least one of which by means of an actuator is mounted movable perpendicular to the fibrous web.

The invention also relates to the use of this device and a method for holding a fibrous web or a beginning and / or end of a fibrous web, in particular a paper, cardboard or tissue web with this device.

In the case of unwinding devices for winding rolls made of fibrous webs, in particular paper, cardboard or tissue webs, splicing devices are known which connect the end of the expiring fibrous web to the beginning of a new winding roll. When unwinding heavy paper rolls that are wound on continuous metal axles (reels) and can have a weight of more than 50 t with a web width of 10 m and more, the unwinding device and the downstream processing machine are usually shut down for splicing.

A device is known from EP 0 462 157-B1 which has a device for severing and holding the running web. The holding device for the running web is pivotably mounted in order to press it against an exchanged full winding roll, at the beginning of which an adhesive strip is attached. This creates a connection in which the end of the running out web overlaps with the beginning of the web of the new winding roll at the splice point.

A device of the generic type is known from DE 43 25 944 AI. This device has a holding device for holding the end of the outgoing web, which is arranged stationary on one side of the running web and has two holding elements which are arranged at a distance from one another in the direction of web travel are. A web transport device is used to pick up the beginning of the web of a full winding roll on its circumference and to transport the beginning of the web to behind the area of the holding device. To cut through the web, a cutting knife is arranged in a groove of the holding device between the two holding elements. On the other side of the web there is a strip dispenser that can be moved up and down and with which an adhesive connecting strip can be moved against the webs.

When a pressure piece moves against the holding element, the running web and the beginning of the new web are severed together. As a result, the new end of the web and the new start of the web are directly next to each other and can thus be seamlessly connected to one another.

Such a connection, referred to as a butt splice, without overlapping of the two webs has the advantage that the connection point does not have twice the web thickness and there is also no stepped shoulder (joint) at the splice point. A shock at the splice point can lead to malfunctions in downstream processing machines.

The disadvantage is that the considerable clamping forces are absorbed by cross members, which guide the flow of forces through the machine in a very disadvantageous manner.

In addition, these holding devices usually take up a lot of space and are relatively heavy.

The object of the invention is therefore to create a compact and lightweight web holding device.

According to the invention, the object was achieved in that at least one of the opposing holding elements has at least one controllable pressure body supported on the holding element and directed towards the fibrous web, and the opposing holding elements have magnetic force elements which pull these holding elements together.

The clamping and holding of the fibrous web is based predominantly, preferably exclusively, on the magnetic attraction of the opposing force elements. The effect on the fibrous web lying between these holding elements is relatively great because of the small thickness of the fibrous web and thus the small distance between the holding elements with their magnetic force elements.

To clamp the fibrous web, the actuator brings the corresponding holding element up to the fibrous web. The opposing holding elements are then pressed against one another in order to clamp the fibrous web in place by their magnetic force elements, the pressure body producing no pressure between the fibrous web and the respective holding element and preferably being depressurized.

With this clamping, the force flow runs directly through the fibrous web so that no external reaction forces arise on the surrounding components.

To release the fibrous web, the magnetic force elements of the opposing holding elements are first pushed away from one another via the pressure body until the magnetic force of attraction between these force elements is sufficiently small. Here, too, there is a favorable flow of forces.

Subsequently, these holding elements can then be moved away from one another by means of an actuator with little force.

In the interest of a light and simple construction, the opposing magnetic force elements are each formed by a pair of permanent magnets or a permanent magnet and a magnetizable counter element.

If two permanent magnets are opposite each other, they must be arranged in order to generate a magnetic force of attraction that poles of different names are opposite each other.

The magnetizable counter-elements are ferromagnetic substances such as iron or ferrimagnetic substances such as ferrites. Permanent magnets exert an attraction on these substances.

In all cases the magnetic attraction increases disproportionately as the distance between the magnetic force elements decreases.

In order to enable a very simple structure for a holding element, in particular in the form of a strip made of steel running transversely to the direction of travel of the web, this should opposite holding element have a pressure body and a permanent magnet as a magnetic force element.

The task of the pressure body is, if necessary, to increase the distance between the fibrous web and the respective holding element by means of a pressure build-up. In principle, electrical, pneumatic or hydraulic actuators can be used.

However, with regard to pressure distribution across the width of the web, it has proven to be advantageous if the pressure body is designed as a deformable pressure hose extending transversely to the direction of travel, the cavity of which can be subjected to a pressure fluid such as compressed air or water.

For bringing the respective holding element towards and away from the fibrous web, it is structurally advantageous if the corresponding holding element, in particular the holding element equipped with a pressure body, is attached to at least one lever that can be pivoted relative to the fibrous web.

The actuator should then also act on this lever.

To generate favorable force relationships over a longer lever arm of the pressure body, the magnetic force element should be arranged between the pressure body and the pivot axis of the lever.

In general, to minimize the effort, it is advantageous if only one holding element is mounted so as to be movable perpendicular to the fibrous web by means of an actuator and this preferably also has the pressure body and the permanent magnet. In this way, the opposite holding element can be designed as a fixed bar or the like.

However, there can also be applications in which it is necessary for the two opposing holding elements to be mounted so as to be movable perpendicular to the fibrous web by means of an actuator each.

A simple construction results when at least one, preferably both, holding elements extend over the entire width of the fibrous web. This then also applies with advantage to their pressure bodies and magnetic force elements. However, the production and assembly of the holding elements are simplified if several holding elements are arranged next to one another transversely to the web running direction at least on one, advantageously on both sides of the fibrous web.

In order to still be able to run the pressure body, in particular the pressure hose, over the entire width of the web, the adjacent holding elements should be mechanically coupled to one another with little play. This prevents shear forces on the pressure body between the adjacent holding elements.

In addition, the play between the coupled holding elements also allows manufacturing tolerances and thermal changes in length.

It is particularly advantageous to use the holding device for connecting the end of an outgoing fibrous web to the beginning of a new winding roll when unwinding fibrous webs, in particular paper, cardboard or tissue webs.

In so-called butt splice devices in particular, two initially uncut fiber webs are often placed on top of one another and held by a device in front of and after the splice point.

This means that on both sides of the fibrous web or the two fibrous webs there are two holding elements which are spaced apart from one another in the direction of web travel.

With regard to the flow of force, it has proven to be advantageous here if the fibrous web runs vertically between the opposing and / or the holding elements spaced apart from one another in the direction of web travel.

The invention will be explained in more detail below using an exemplary embodiment. In the attached drawing show:

FIGS. 1 to 3: a schematic cross section through a holding device in various operating states;

Figure 4: a partial view of a holding element and

FIG. 5: an enlargement of a partial section from FIG. 4. The invention is particularly suitable for unwinding devices for paper rolls which are wound onto continuous metal axles called reels and which can have a weight of over 50 t with a web width of 10 m and more.

The winding roll is rotatably mounted with its spool at the two ends of the axis. The fibrous web 1 is withdrawn from the winding roll and fed to a subsequently arranged roll cutting and winding machine, where it is longitudinally divided into individual webs and wound up into smaller winding rolls.

A splice device through which the fibrous web 1 is guided is arranged at a distance behind the unwinding device and outside the diameter range of a full winding roll.

When changing the winding roll, the splice device connects the end of the outgoing web with the beginning of the web of a new winding roll in a so-called butt splice, without any overlap between the two webs.

As an essential component, the splicing device comprises one or two stationary web holding devices, spaced apart from one another in the web running direction 2, each with at least two opposing holding elements 3, 4, between which the fibrous web 1 according to FIG. 1 is passed vertically from top to bottom.

As a further element, the splicing device often also contains a web transport device, by means of which a web beginning or a web end can be picked up and transported into the region of the holding device.

In the area of the web holding device, a known web separating and adhesive tape application device is usually arranged which cuts the web ends and connects them to one another without overlapping.

When the winding roll is unwound except for a residual roll, the unwinding process is first slowed down. The stationary fibrous web 1 can thus be clamped by the holding device via the holding elements 3, 4 according to FIG. The holding device comprises on one side a holding element 3 in the form of a steel strip extending over the entire width of the fibrous web 1.

On the opposite side with respect to the fibrous web 1 there are, as indicated in FIG. 4, a plurality of holding elements 4 which are arranged next to one another transversely to the web running direction 2. These short holding elements 4 are also formed by strips running transversely to the web running direction 2.

While the simply designed holding element 3 extending over the entire width of the web is stationary, the holding elements 4 arranged next to one another on the other side of the fibrous web 1 can be moved essentially perpendicular to and away from the fibrous web 1 via pivotable levers 9.

In order to be able to control this movement, these levers 9 are each coupled to a controllable actuator 5, for example in the form of a pneumatic cylinder or a spindle lifting element.

For clamping the fibrous web 1 between the opposing holding elements 3, 4 these have magnetic force elements 7, 8 which pull these holding elements 3, 4 together.

While in the stationary holding element 3 the magnetic force element 7 is formed by the steel bar as a magnetizable counter-element itself, the opposite, pivotable holding element 4 carries several magnetic force elements 8 in the form of permanent magnets distributed over the width of the track.

Furthermore, a controllable pressure body 6 running transversely to the web running direction 2 and extending over the entire width of the fibrous web 1 is attached to the pivotable holding elements 4, which is supported on the holding elements 4 and can generate a pressure in the direction of the fibrous web 1.

For this purpose, the pressure body 6 is designed as a deformable pressure hose, the cavity of which can be acted upon with a pressure fluid such as compressed air or water.

So that no shear forces are generated on the pressure hose between the adjacent holding elements 4, the adjacent holding elements 3, 4 are mechanically coupled to one another with little play via drivers 11 in accordance with FIGS. 4 and 5. To clamp the fibrous web 1 in place, the opposing holding elements 3, 4 according to FIG. 2 are brought together by means of actuators 5 when the pressure body 6 is depressurized. The actual compression of the holding elements 3, 4 is taken over by the opposing, magnetically attracting force elements 7, 8.

To release the fibrous web 1, the magnetic force element 8 is first pushed away from the fibrous web 1 and thus also from the opposite holding element 3, as can be seen in FIG. 3, by applying a pressure fluid to the pressure body 6. As a result, only a relatively small magnetic force of attraction remains between the opposing holding elements 3, 4. The pivotable holding element 4 can then be moved further away from the fibrous web 1 by means of the actuator 5 with little force.

In order to optimize the effectiveness of the pressure body 6, the magnetic force element 8 is located between the pressure body 6 and the pivot axis 10 of the lever 9.

Claims

1. Device for holding a fibrous web (1) or a beginning and / or end of a fibrous web (1), in particular a paper, cardboard or tissue web with at least two opposite to the fibrous web (1) and running transversely to the web running direction (2) Holding elements (3, 4), of which at least one can be moved perpendicular to the fibrous web (1) by means of an actuator (5), characterized in that at least one of the opposite holding elements (3, 4) is at least one on the holding element (3, 4 ) has supporting and on the fibrous web (1) directed, controllable pressure body (6) and the opposite

Holding elements (3, 4) have magnetic force elements (7, 8) which pull these holding elements (3, 4) together.

2. Device according to claim 1, characterized in that the opposing magnetic force elements (7, 8) are each formed by a pair of permanent magnets or a permanent magnet and a magnetizable counter element.

3. Device according to claim 1 or 2, characterized in that the holding element (3, 4) with the pressure body (6) has a permanent magnet as a magnetic force element (7, 8).

4. Device according to one of the preceding claims, characterized in that the pressure body (6) is designed as a deformable pressure hose extending transversely to the web running direction (2), the cavity of which can be acted upon with a pressure fluid.

5. Device according to one of the preceding claims, characterized in that that the holding element (3, 4) is attached to the pressure body (6) on at least one lever (9) which can be pivoted relative to the fibrous web (1).

6. The device according to claim 5, characterized in that the lever (9) is coupled to the actuator (5).

7. Apparatus according to claim 5 or 6, characterized in that the magnetic force element (7,8) is arranged between the pressure body (6) and the pivot axis (10) of the lever (9).

8. Device according to one of the preceding claims, characterized in that the two opposing holding elements (3, 4) are movably mounted by means of an actuator (5) each perpendicular to the fibrous web (1).

9. Device according to one of claims 1 to 7, characterized in that only one holding element (3, 4) is movably supported by means of an actuator (5) perpendicular to the fibrous web (1).

10. Device according to one of the preceding claims, characterized in that at least one holding element (3, 4) extends over the entire width of the fibrous web (1).

11. Device according to one of the preceding claims, characterized in that at least on one side of the fibrous web (1) several holding elements (3, 4) are arranged next to one another transversely to the web running direction (2).

12. The device according to claim 11, characterized in that that the adjacent holding elements (3, 4) are mechanically coupled to one another with play.

13. A method for holding a fibrous web (1) or a beginning and / or end of a fibrous web (1), in particular a paper, cardboard or tissue web with a device according to one of the preceding claims, characterized in that the opposing holding elements (3 , 4) to clamp the fibrous web (1) in a pressureless pressure body (6) are brought together by means of an actuator (5) and to release the fibrous web (1) first the pressure body (6) the magnetic force elements (7, 8) of the opposing holding elements (3 , 4) pushes away from each other and then these holding elements (3, 4) are moved away from each other by means of an actuator (5).

14. Application of the device according to one of claims 1 to 12 for connecting the end of an expiring fibrous web (1) with the beginning of a new winding roll when unwinding fibrous webs (1), in particular paper, cardboard or tissue webs.

15. Application according to claim 14, characterized in that on both sides of the fibrous web (1) there are two holding elements (3, 4) spaced from one another in the web running direction (2).