DE102011078010A1 - Method for monitoring homogeneous properties of cover for transportation of paper web through dry end of paper machine, involves determining degree of contamination by judging contrast between clean and contaminated surface portions - Google Patents

Abstract

The method involves illuminating a surface area of a cover with UV light and detecting the surface area by using a scanner (10) e.g. UV camera and UV sensor, where yarns of the cover are partially made of UV fluorescent material or material with mixtures of UV fluorescent particles. A degree of contamination (16) is determined by judging contrast between clean and contaminated surface portions by using an evaluation unit (13). The contaminated surface portions are cleaned by a cleaning apparatus (14), which is controlled and regulated by the evaluation unit. An independent claim is also included for a cover for transportation of fibrous material web through a dry end of a fibrous material web manufacturing machine.

Description

The invention relates to a method for monitoring properties of a circumferential covering, in particular a fabric covering for transporting a fibrous web through a dryer section of a machine for producing a fibrous web, wherein at least a surface region of the fabric is detected by means of a scanning device.

When operating a fabric in a fibrous web making machine, such as a paper machine, it is important that it has as homogeneous properties as possible. This means that as many polluted or damaged areas as possible should not be present. Therefore, the fabrics are monitored by means of scanning devices and cleaned by means of cleaning devices.

This is very difficult due to the environmental conditions, especially with dryer fabrics. In addition, these are usually operated over a period of about 1 year.

Checking the dryer fabrics for damage or contamination is usually done during machine downtime when the dryer section has cooled down so that it is easily accessible to personnel. The fabrics are subjected to a visual inspection to determine whether additional cleaning is necessary or damage makes a replacement of a covering necessary. This can lead to a delay in the shutdown schedule, leading to production stoppages.

For cleaning the dryer fabrics a variety of cleaning devices are known with which the fabric can be cleaned continuously or periodically.

In addition to condition monitoring, it is important to check the tape as there are often shifts or distortions that can cause tape running problems and / or wrinkles in the paper. By means of a transversely applied (CMD) color band which shifts with the tissue, a displacement or distortion can be easily identified. This can be done for example with a camera, but due to the poor visibility in the dryer section can not be used simultaneously to monitor wear, damage and / or contamination of the dryer fabrics.

Furthermore, the disclosure DE 10 2008 002 658 A1 a method for detecting the condition of a tape. Here it is proposed to determine the condition of a band having a substantially closed surface, in particular a steel band, by means of an optoelectronic detector and a light emitter which irradiates the band surface. By the light reflections of the band can be closed to its state. Especially with steel bands cracks can be very well recognized in this way. For monitoring tissue stresses, in particular the degree of contamination, this method is less suitable, since this is essentially dependent on good light reflections, as they are feasible in steel strips.

The invention has for its object to provide a method for monitoring a fabric and a covering, which / overcomes the disadvantages of the prior art.

According to the invention the object is achieved by a method according to claim 1 and with the covering according to claim 11.

In the method according to the invention for monitoring properties of a circumferential covering, at least one surface area of the covering is detected by means of a scanning device and the degree of contamination is determined by assessing the contrast between clean and soiled surface portions by means of an evaluation unit.

Surface areas which are contaminated are detected by the fact that the surface properties of a clean fabric, such as a dryer fabric, which can be detected by a sensor, appear different from those of a dirty fabric. In the evaluation unit, the values determined by the sensor can be assessed and from this the degree of contamination can be determined.

Furthermore, defects, such as holes in the sieve, can be detected.

In this case, a variety of sensors or cameras can be used, wherein the surface of the fabric is preferably illuminated to achieve a better contrast.

In a particularly preferred embodiment, the yarns of the fabric consist at least partially of a UV-fluorescent material or a mixture of materials with UV-fluorescent particles and the surface areas are illuminated with UV light and detected with a UV camera and / or UV sensor. Through the use of UV light, a very good contrast can be achieved even in low light conditions, as they prevail within a drying section, since the dirt particles cover the yarns and the yarns are therefore no longer glowing.

Furthermore, the contaminated surface portions can be cleaned by means of a cleaning device which is controlled and regulated by the evaluation unit. Soiled areas can be cleaned in this way, at least in CMD.

It is also advantageous if a marking is arranged on at least one clothing side, which can be detected by means of a sensor, so that the clothing can be assessed and / or monitored and / or cleaned in a location-specific manner.

The marking may be a microsensor connected to the clothing and / or data logger and / or transponder, which communicates with a corresponding transceiver unit.

The tag is preferably an RFID tag, from which e.g. also the data in relation to the clothing can be read out.

However, the marking may also consist of at least one weft yarn, which does not have fluorescent properties, the weft yarn is then also used to assess the tissue shift.

In a further step, the intensity of the reflection of the yarns can be measured and concluded therefrom on the wear of the yarns. Thus, the reflection surface, the fluorescence and / or the reflection intensity of the worn yarns can be measured, which change with progressive wear.

The proposed fabric comprises a system of warp yarns interwoven with a system of weft yarns designed to support the fibrous web on top of the fabric, the yarns crossing each other and forming an open volume, at least a portion of the yarns consists of a UV-fluorescent material or a mixture of materials with UV-fluorescent particles, so that at least one surface area of the fabric can be detected by a scanning device and the degree of contamination by the contrast between clean and dirty surface portions by means of an evaluation unit can be assessed.

In order to obtain an accurate location allocation of the soiled areas and / or tissue displacement, the fabric can mark a mark.

Preferably, the label is an RFID tag and / or at least one weft yarn of non-fluorescent material or material mixture.

The invention will be explained in more detail with reference to drawings. In these show:

1 a section of a dryer section of a paper machine

2a , b Dryer screens with different fault patterns

3 a representation of the wear process.

In 1 is a section of a dryer section 1 a paper machine shown. The in the dryer section 1 incoming paper web 3 usually has a dry content of about 40-70% and is dewatered or dehumidified within the dryer section to a dry content of about 85-96%, so that the paper web at the exit of the dryer section still has a moisture content of about 4 to 12%.

In the dryer section, the paper web 3 from an endlessly circulating dryer 5 supported and alternately heated, in a row juxtaposed drying cylinders 4 and over guide rollers 6 guided. The dry band 5 pushes the fibrous web 3 against the hot surface of the drying cylinder 4 so that these through direct contact with the drying cylinders 4 dried or dehumidified.

In the 1 are two dryer fabrics 5 shown in their complete circulation path, each of the dryer fabrics 5 each a group of drying cylinders 4 circulates. In other words, every drying wire runs 5 in the field of drying cylinders 4 wavy up and down, with the drying wire 5 on the wave mountain of a drying cylinder 4 is deflected and in the trough of a suction roll of a respective vacuum device 6 is diverted. After leaving the last drying cylinder 4 the corresponding group becomes the dryer fabric 5 over several guide rollers 7 back to the first drying cylinder 4 returned to the group.

The dryer section can be single row, as shown, or double row and is always surrounded by a hood in which a regulated, humid climate prevails. Unlike in the wet part or in the press section of a paper machine has a drying wire 5 a high temperature resistance and ideally a cfm value between 70 and 1000.

The structure of such a dryer 5 can have very different weave patterns and structures. Here reference is made to the sands of the technology.

In the 2a + b the principal arrangement of the components for carrying out the method is shown. In the area of the return is above the dryer 5 a scanning device 10 positioned that captures the surface or surface areas. In this embodiment, the scanning device exists 10 from at least one IR lamp and one IR sensor or one IR camera. The yarns 18 of the dryer 5 consist at least partially of a UV-fluorescent material or a mixture of materials with UV-fluorescent particles. Are the yarns 18 Dirty dirt covers the yarns 18 and the areas appear as a dark area 16 ,

The scanning device 10 For example, in CMD it can be traversed across the screen surface. Alternatively, however, it is also possible to arrange a series of sensors next to one another, each of which detects a strip area.

The recorded data are forwarded to the evaluation unit and in this, the degree of contamination is determined in a known manner, for example by comparing the contrasts. The cleaning device 14 can then according to the determined pollution, the Sieboberfläche 5 clean specifically.

Cleaning can be carried out in a more targeted manner if a marking such as an RFID tag is inserted in the clothing, which is connected to a sensor 12 is detectable and / or can be read. Thus, a contamination or a defect in the fabric can be detected with respect to this location location.

In 2 B the mark is shown as a stripe pattern, so that a tissue shift can be determined. For this purpose, for example, some weft threads are inserted from a non-fluorescent material.

3 shows simplified the wear pattern of a yarn. Depending on how the yarn is abraded or worn, the appearance changes with respect to the scanning device 10 , This change can be used to define the wear. Thus, the degree of reflection or the reflection surface can be selected as an auxiliary size. The corresponding comparison values can, for example, be stored on the RFID tag and compared with the measured values in the evaluation unit.

LIST OF REFERENCE NUMBERS

1

 drying section

2

 Dryer section group

3

 Fibrous web

4

 drying cylinders

5

 dryer

6

 Vacuum device

7

 leadership

8th

 idler

9

 cutting device

10

 scanning device

11

 mark

12

 sensor

13

 evaluation

14

 cleaning device

16

contamination

17

 marking line

18

 yarn

MD

 machine direction

CMD

 Transverse to the machine direction

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102008002658 A1 [0007]

Claims (13)

Method for monitoring properties of a circumferential covering ( 1 ), in particular a covering for transporting a fibrous web through a dryer section of a machine for producing a fibrous web, in which at least one surface region of the fabric ( 5 ) by means of a scanning device ( 10 ) is detected and the degree of contamination is determined by the fact that the contrast between clean and contaminated surface portions by means of an evaluation unit ( 13 ). A method according to claim 1, characterized in that the surface is illuminated. A method according to claim 1, characterized in that the yarns 18 the covering consist at least partially of a UV-fluorescent material or a mixture of materials with UV-fluorescent particles and the surface areas are illuminated with UV light and detected with a UV camera and / or UV sensor. A method according to claim 3, characterized in that the soiled surface portions are cleaned by means of a cleaning device which is controlled and regulated by the evaluation unit. Method according to one of claims 1 to 4, characterized in that a marking is arranged on at least one string side, which is detected by means of a sensor and the string is judged location-related and / or monitored. Method according to claim 5, characterized in that the marking is a microsensor connected to the clothing and / or data logger and / or transponder, which communicates with a corresponding transceiver unit. A method according to claim 6, characterized in that the mark is an RFID tag, from which the data are read out. A method according to claim 5, characterized in that the marking consists of at least one weft yarn having non-fluorescent properties, wherein the weft yarn is used to assess the tissue displacement. A method according to claim 1, characterized in that the intensity of the reflection of the yarns 18 is measured and from this on the wear of the yarns 18 is closed. A method according to claim 9, characterized in that the reflection surface, the fluorescence and / or the reflection intensity of the worn yarns 18 is measured. Covering, in particular covering for transporting a fibrous web through a dryer section of a machine for producing a fibrous web, comprising a system of warp yarns interwoven with a system of weft yarns adapted to support the fibrous web on top of the fabric; Yarns ( 18 ) intersect each other and form an open volume, characterized in that at least part of the yarns ( 18 ) consists of a UV-fluorescent material or a mixture of materials with UV-fluorescent particles, so that at least one surface area of the fabric can be detected by a scanning device, so that the degree of contamination by the contrast between clean and dirty surface portions by means of an evaluation unit can be assessed. Fabric according to claim 11, characterized in that the fabric has a marking. Covering according to claim 12, characterized in that the marking is an RFID tag and / or at least one weft yarn of non-fluorescent material or material mixture.

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