DE202022002614U1 - Device for stretching film webs in the machine direction with a cleaning device - Google Patents

Abstract

Device for stretching film webs in the machine direction with a plurality of rollers, two of which are stretching rollers (5) which form a stretching gap in which the film web can be stretched, characterized by a cleaning unit (12) which is arranged on a linear guide (13) and parallel to the longitudinal axis a roller to be cleaned can be moved.

Description

The invention relates to a device for stretching film webs in the machine direction with a cleaning device.

Stretching systems are used in the production of foils in order to reduce the thickness of foils after they have been produced. Film stretching is used for both tubular films and cast films.

A stretching line typically consists of heated rolls to prepare the film for stretching, followed by stretching rolls between which the film is stretched. So-called annealing or tempering rollers can follow the stretching, here the film is subjected to a temperature treatment in order to affect the film properties. Finally, the film is cooled using chill rolls. By stretching the foil webs, the foils are not only changed in their geometric dimensions, their properties such as transparency or strength can also be specifically influenced.

Stretching systems are operated offline or inline in blown film systems. Tubular films can also be stretched inline in blown film lines directly after the pair of take-off rollers or after the turner bar system following the pair of take-off rollers.

The treatment of the foils in the stretching system, also known as MDO (Machine Direction Orientation), causes the rollers over which the foils are guided to become soiled. These rollers must be cleaned at specified intervals. The contamination can be monomers that outgas from the films, but also dust and deposits from the environment and the production process. Dirty rollers impair the quality of the film, since markings such as streaks appear on the film. In addition, dirty rollers lead to a deterioration in the stretching process, e.g. due to clogged or dirty vacuum rollers.

It is generally known to remove and clean rollers during production breaks or to clean them on site in the stretching system.

When using vacuum rollers in the stretching system as in the DE 10 2020 000 334 A1 is described, cleaning is important since the monomers can clog the openings of the vacuum roll. Cleaning these rollers is very laborious and the vacuum rollers have to be removed at regular intervals for this purpose. Production has to be stopped for this.

The DE 10 2020 134 815 A1 discloses a stretching device for stretching plastic film with at least one roller through which air can flow from the outside inwards and which can be continuously cleaned.

For this purpose, the roller has a first area through which flow can take place from the outside to the inside and a second area through which flow can take place from the inside to the outside; the latter is used for cleaning. This makes it possible to keep the through-openings of the roller free of dirt with increased pressure by means of a blow-out process. This prevents the openings of the roller from becoming clogged and the production plant from being stopped.

It is therefore the object of the present invention to provide a device which enables rollers in stretching systems to be cleaned without dismantling them.

In a device of the type described above, the object is achieved according to the invention by a device according to the characterizing part of claim 1.

A cleaning device is provided for cleaning rollers in stretching systems, especially vacuum rollers of a stretching system. This is arranged parallel to the roll to be cleaned in the stretching system so that it can be moved in the axial direction of the roll and clean the roll in the process.

The cleaning unit comprises a belt which is used in contact with and moved over the roller.

The cleaning unit includes two rollers for winding and unwinding the belt. In addition, it has another roller over which the belt is guided and pressed against the roller to be cleaned, referred to below as the pressure roller. The three rollers are arranged in a housing. The tape and the winding and unwinding roll is designed to be interchangeable and can be replaced if necessary.

The pressure roller of the cleaning unit is connected to a vibration motor and performs an oscillating movement. This movement helps to clean the roller.

The cleaning unit is arranged in such a way that it can be moved parallel to the longitudinal axis of the roller to be cleaned by means of a linear guide and spindle.

Abrasive belts of different grits are preferably used as belts, so that dirt of different strengths can be removed from the roller surface. In this way, even stubborn deposits can be removed.

Depending on the degree of soiling of the roller, the traversing speed of the cleaning unit, the relative speed of roller and belt of the cleaning unit can be adjusted. Other adjustable parameters are the contact pressure and vibration speed of the pressure roller.

In addition, depending on the degree of soiling, sanding belts with different grits can be selected.

Cleaning can be done with or without coolant.

The cleaning unit has an exchangeable tape magazine.

Alternatively, the cleaning unit can be equipped with a polishing belt, so it can also be used for polishing the rollers of the stretching system.

The cleaning unit is preferably used to clean stretching rollers that are designed as vacuum rollers, but it can also be used to clean any other roller in a stretching system, such as rubber rollers, chrome rollers or embossing rollers.

If vacuum rollers are cleaned, they are additionally pressurized with compressed air from the inside to the outside. In this way, the openings of the vacuum roller can be freed from contamination, specifically by monomers.

If necessary, the surface of the roll is additionally flushed with compressed air.

The grain size of the sanding belts is selected depending on the type of openings in the vacuum roller and the degree of contamination.

To clean the rolls, the stretching system, also known as MDO (Machine Direction Orientation), is switched to a cleaning mode. For the cleaning of stretching rollers, they are moved in such a way that a large stretching gap is created. The cleaning unit then moves on a linear guide from its parking position to a cleaning position on the roller until the pressure roller has reached its position. The pressure roller is moved to the roller and the vibration motor is switched on. The roller to be cleaned is set in rotation. The cleaning unit moves along the roller along its longitudinal axis and cleans the roller. The belt, preferably an abrasive belt, is constantly renewed in that it is unwound from one roll and continuously wound onto the other roll. When cleaning vacuum rollers, compressed air is applied to them from the inside out in order to force the dirt out of the openings in the roller. At the same time, the surface of the rollers can be flushed with compressed air.

Depending on the type and degree of contamination, the temperature of the rollers can be adjusted so that a distinction is made between cold and warm grinding.

By providing a cleaning unit in the stretching system, the rollers to be cleaned, especially the vacuum rollers, no longer have to be removed for cleaning.

The function of the rollers can be completely restored by cleaning, by removing the dirt from the roller surface.

Stretching systems are to be understood here as all devices that cause a change in length of a film web in the machine direction, which also includes the stretching or stretching of film webs.

Further details, features and advantages of the subject matter of the invention result from the dependent claims and from the following description of the associated drawings, in which a preferred exemplary embodiment of the invention is illustrated by way of example.

• 1 eine Ansicht einer Reckanlage mit Reinigungseinheit,
• 2 einen Ausschnitt aus 1 mit der erfindungsgemäßen Reinigungseinheit.

In the drawing shows:

• 1 a view of a stretching system with a cleaning unit,
• 2 a snippet 1 with the cleaning unit according to the invention.

The 1 shows a stretching system, also called MDO, for changing the length of a film web in the machine direction.

The film web (1) is introduced into the stretching system from above via guide rollers (10). First, it is guided over a heating section (2) with heating rollers (3). The film web (1) is then fed to the stretching section (4) with the stretching rollers (5) and a stretching gap in between, and stretched. The stretching rollers (5) can have a smaller diameter than the heating rollers (3). The film web (1) is then subjected to an annealing section (6) with annealing rollers (7) for tempering ren supplied, followed by a cooling section (8) with cooling rollers (9). Finally, the film (1) leaves the MDO system and can, for example, be wound up in a downstream winder (not shown here). The film web is held on the different rollers by means of lay-on rollers (11).

The cleaning unit (12) is arranged on one of the stretching rollers (5). It is movably arranged on a linear guide so that it can move back and forth parallel to the roller (5) to be cleaned.

The 2 shows the cleaning unit (12) on one of the stretching rollers (5) in detail. The cleaning unit (12) consists of two rollers (17) and (18), the belt (14) being unrolled from one roller (17) and rolled up from the other roller (18) with drive (20). The belt (14), here a grinding belt, is guided between the rollers via a pressure roller (15). This pressure roller (15) is provided with a vibration motor (16) which causes the pressure roller (15) to oscillate. The cleaning unit (12) is arranged on a linear guide (13) which is fastened parallel to the roller (5) to be cleaned in the housing of the stretching system. A spindle (not shown here) can be used to move the cleaning unit (12) on the linear guide (13) parallel to the longitudinal axis of the roller (5) at a predetermined traversing speed, with the roller (5) rotating at a predetermined speed. In its parking position, the cleaning unit (12) is positioned in the side wall of the stretching unit outside the production width of the film. To clean a stretching roller (5), the stretching rollers (5) are moved apart, with the roller to be cleaned being moved in the direction of the linear guide of the cleaning unit (12). The cleaning unit (12) is first moved from its parking position to the edge area of the production width of the foil, then the pressure roller (15) is moved to the roller (5). Now the sanding belt (14) is set in motion and the roller (5) is set in rotation. The cleaning unit (12) moves along the roller (5) on the linear guide (13) at a predetermined speed, cleaning it.

Reference List

1

film web

2

heating section

3

heated rollers

4

stretch stretch

5

stretching rollers

6

annealing stretch

7

annealing rollers

8th

cooling line

9

chill rolls

10

guide rollers

11

lay-on rollers

12

cleaning unit

13

linear guide

14

tape

15

pinch roller

16

vibration motor

17

roll

18

roll

20

drive

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102020000334 A1 [0007]
• DE 102020134815 A1 [0008]

Claims (9)

Device for stretching film webs in the machine direction with a plurality of rollers, two of which are stretching rollers (5) which form a stretching gap in which the film web can be stretched, characterized by a cleaning unit (12) which is arranged on a linear guide (13) and parallel to the longitudinal axis a roller to be cleaned can be moved. device after claim 1 characterized in that the cleaning unit (12) in a housing - a belt (14), - two rollers (17,18) for unwinding and winding up the belt (14), - a pressure roller (15) with a vibration motor (16), which presses the belt (14) against the roller to be cleaned. device after claim 1 and 2 , characterized in that the traversing speed of the cleaning unit (12), the relative speed of the belt (14) and the roller to be cleaned and the contact pressure and the vibration speed of the pressure roller (15) of the cleaning unit (12) are adjustable. Device according to one of the preceding claims, characterized in that the grain size of the belt (14) of the cleaning unit (12) can be selected. Device according to one of the preceding claims, characterized in that the belt (14) is a grinding belt, by means of which impurities can be removed from the roller. Device according to one of the preceding claims, characterized in that the roller surface can be flushed with compressed air Device according to one of the preceding claims, characterized in that the roller to be cleaned is a stretching roller, rubber roller, chrome roller or embossing roller. Device according to one of the preceding claims, characterized in that the stretching roller (5) is a vacuum roller. Device according to one of the preceding claims, characterized in that the vacuum roller can be charged with compressed air from the inside to the outside for cleaning.

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