WO2013068442A1

WO2013068442A1 - Device and method for conditioning a roll

Info

Publication number: WO2013068442A1
Application number: PCT/EP2012/072102
Authority: WO
Inventors: Juergen Abraham; Oliver Kaufmann; Marc Erkelenz; Alexander Etschmaier
Original assignee: Voith Patent Gmbh
Priority date: 2011-11-11
Filing date: 2012-11-08
Publication date: 2013-05-16
Also published as: DE102011086139A1

Abstract

A device for conditioning, in particular for scraping, a roll, in particular in a web-producing, -processing and/or -finishing machine such as a paper, cardboard, tissue or film machine, comprises at least one sensor unit arranged in the region of the roll to be scraped, and at least one evaluation unit. At least one portion of a surface of the roll is disposed in such a manner that the surface can be detected by means of the at least one sensor unit and the degree of soiling can be evaluated by contrasting the clean and soiled sections of the surface and/or by pattern recognition and/or by image recognition using the evaluation unit.

Description

Apparatus and method for conditioning a roll

The invention relates to a device for conditioning a roller, in particular in a web-making, -processing and / or -veredelnden machine such as a paper, board, tissue or foil machine according to the preamble of claim 1 and a method for Beschaberung according to the preamble of claim 6th

In web-making, -processing and / or -veredelnden machines a variety of rollers for stabilizing, guiding and further transporting the web and for guiding the web supporting elements such as clothing are provided. In the production and also in the refinement of a fibrous or film web, it always comes back to unwanted accumulation of particles on the rollers. These include, for example, agglomerations of fibers and additives from stock preparation, adhesive impurities from waste paper processing or coating residue when applying lines on the fibrous web. Depending on their origin, the agglomerations are referred to as pitch, stickies and white pitch. The following is a simplified discussion of impurity accumulation, as far as specific problems of the individual subgroups are not addressed.

The accumulation of contaminants lead in the course of operation to the fact that the surfaces of the rollers are more and more contaminated, which has quality-reducing effects on the respective end product by various mechanisms or even can lead to malfunctions or failure of the web-processing machine. On the one hand, surface functional structures of various rolls such as suction and blind bores and creases are laid, which thus can no longer fulfill their dewatering function and can lead to increased residual moisture and mottling of the fabric. Spottiness can also occur in the drying group, since heavy soiling of the drying cylinder results in uneven drying of the web. On the other hand, the accumulation of impurities accumulation on smooth roll surfaces can lead to mechanical marking of the fabric, which is also visible in the final product. The replacement of the accumulated impurities from the roll surface and the embedding in the fabric can lead to problems by both the quality of the fabric is deteriorated as well as by carryover into subsequent units such as coating units or calenders their function can be impaired.

Furthermore, it is no longer possible to drive a stable process with heavy pollution, especially if the pollution is distributed unevenly. It can even come to a web breaks of the fabric due to a change in tensile stresses due to altered friction behavior, resulting in expensive machine downtime and laborious work. Due to the well-known and diverse problems, a number of measures for avoiding deposits and for removing the contaminants from prior art roll surfaces are known.

A disadvantage of the devices and measures known from the cited prior art is, for example, that the Beschaberung usually takes place permanently and thus draws a high energy demand by friction by itself.

For example, WO 02/20901 A1 discloses a method and a device for cleaning and servicing rolls in a calender. The method is to monitor the web surface and to detect and locate contamination of the surface of rolls by a soil sensor. A cleaning device then removes the contaminants. It is provided that a cleaning liquid is sprayed on.

A disadvantage of this known prior art is that a rewetting of the fibrous web is to be expected by the cleaning liquid. To one To ensure complete removal of liquid and removed contaminants, extensive equipment is required, which makes cleaning expensive and equipment side expensive. It is accordingly an object of the invention to provide an apparatus and a method for needs-based conditioning, in particular Beschaberung of rollers, the Beschaberung is automatically triggered and reset depending on the state of contamination in a simple and cost-effective manner, without requiring control by personnel.

The object is achieved in terms of the device by the characterizing features of claim 1 and in terms of the method by the characterizing features of claim 6 in each case in conjunction with the generic features.

According to the invention, it is provided that at least a part of a surface of the roller is designed so that the surface can be detected by means of the at least one sensor unit and that the degree of contamination by a contrast between clean and dirty surface portions and / or pattern recognition and / or image recognition means the evaluation unit is recognizable and assessable.

This makes it possible to automatically determine the Beschabbedarfbedarf and initiate appropriate measures to clean the roller, without the staff is required. In addition, the energy requirement for the conditioning measures is optimized, since the conditioning measures can be promptly set again when a limit value for cleaning is reached. Further advantageous embodiments of the invention are specified in the subclaims. Advantageously, at least one scraper unit is provided for conditioning, which is arranged in the region of the roller such that upon detection of the exceeding of a threshold value of contamination the at least one scraper unit can be controlled by the evaluation unit and brought into tribological contact with the surface of the roller. Scrapers are the most reliable and easiest way to clean rotating surfaces and are superior to liquid cleaning because of easier handling and lower costs. According to a preferred embodiment, the surface of the roller may at least partially consist of a UV-fluorescent material or a mixture of materials with UV-fluorescent particles or be provided with a coating comprising UV-fluorescent material or a mixture of materials with UV-fluorescent particles. By means of a UV light source through which the surface can be illuminated with UV light and thus forming the at least one sensor unit as an image camera, line scan camera, UV camera and / or UV sensor, contaminations can be reliably detected without impairing the functionality of the roll , Alternatively, the surface of the roller can be configured to be heat-loadable and the degree of contamination can be measured by the at least one sensor unit based on the detection of warmer and colder areas. This can be implemented, for example, in the area of the drying group of a paper machine in a simple manner, since the drying cylinders must anyway be heated in order to be able to fulfill their function.

When the first threshold value of the contamination is exceeded, the at least one scraper unit is preferably brought into contact with the surface of the roller and swiveled down again when it falls below a second threshold value. Particularly preferably, the second threshold value can be smaller than the first threshold value. In the optimal case, this achieves a complete cleaning of the roll surface with a contamination value of approximately 0%. The invention will be described in more detail with reference to the drawing. Show it:

Fig. 1 is a highly schematic representation of an exemplary inventively designed device for Beschaberung a

Roller; and

Fig. 2 is a highly schematic representation of another embodiment of an inventively designed device.

In Fig. 1, a device 1 for Beschaberung a roller 2 is shown in a highly schematic representation in perspective view.

The device 1 essentially comprises at least one sensor unit 3, which is arranged at a suitable location in the region of the roller 2 to be doctored. The at least one sensor unit 3 is preferably approximately as long as the axial length of the roller 2, but may also be shorter if the sensor unit 3 has a corresponding geometry. However, it should at least be designed so that the working width of a fabric not shown in Fig. 1 is completely detectable.

The at least one sensor unit 3 may be integrally formed or composed of individual sensor elements. The latter embodiment is particularly advantageous since the sensor unit 3 can be flexibly adapted to deviating roll lengths by fitting or removing sensor elements.

The at least one sensor unit 3 is connected in the illustrated embodiment via cable 4 to an evaluation unit 5, which is designed to record the data collected by the at least one sensor unit 3 and to drive at least one likewise connected via cable 7 scraper unit 6. Also wireless transmission paths such as wireless or wireless connection to the evaluation unit 5 are conceivable and executable. Such detection and AnSteuereinheiten and their connections with sensors are well known in the prior art, which is why a detailed description can be omitted here. On the surface of the roll 2 to be shredded, by way of example, some impurity accumulations 8 are shown which adhere to the surface. The impurities accumulations 8 are usually not so isolated, as shown for reasons of clarity in Fig. 1, but can cover the surface of the roller 2 up to 100%.

In order to enable the sensor unit 3 to record measured values, the roller 2 is provided with a coating which, according to one exemplary embodiment, can be activated by incident light of suitable wavelength. The coating may, for example, contain particles which fluoresce when exposed to UV light. The at least one sensor unit 3 and the evaluation unit 5 are then to be interpreted according to the visual data acquisition of the fluorescence and its further processing.

If an uncontaminated roller 2 is irradiated with UV light, it will shine back evenly over its entire coated surface. However, if impurities in the form of impurities accumulations 8 are present, these areas of the surface of the roller 2 are hidden and thus appear dark. The at least one sensor unit 3 can record the resulting contrast differences over one or more revolutions of the roller 2, and subsequently both a degree of contamination can be determined and a contamination map of the surface of the roller 2 can be created. If a specific threshold value, which can be, for example, a percentage of covered roll surface or even as a percentage of an image detail of the sensor unit 3 and is freely selectable, the evaluation unit 5 directs the application of the at least one scraper unit 6 in tribological contact to the roller 2 and the Conditioning the surface. As a further threshold criterion, a certain size of the contamination accumulations would also be possible, eg a diameter of more than 5 mm. During the conditioning, the at least one sensor unit 3 further measures the contrast differences, so that the undershooting of a further threshold value, preferably different from the first, can also be detected by the cleaning and the at least one scraper unit 6 can be swiveled away from the roller 2 again. As a result, an efficient energy-saving operation of the at least one scraper unit 6 is ensured. This is applied only when necessary, conditioned as long as necessary, the surface of the roller 2 and is immediately swung back when the roller 2 is sufficiently cleaned. Unnecessarily long conditioning times are thus avoided.

If the second threshold, which indicates the degree of cleanliness of the roll 2, e.g. At 0% contamination, the roller is most thoroughly conditioned to achieve the cleanest surface possible. If it is not necessary to completely clean the surface, any other threshold value can also be selected, for example, to drive only very short conditioning times with the lowest possible energy requirement.

Furthermore, it is conceivable to operate the active surface coating of the roller 2 in other wavelength ranges or with other mechanisms of action, for example with a roller heating in conjunction with a heat sensor that absorbs temperature differences between soiled and non-contaminated areas on the surface of the roller 2.

The device 1 according to the invention is also distinguished by a series of further advantages which can contribute to the effectiveness of the production. It is thus possible to use the data recorded by the evaluation unit 5 for the online monitoring of the contamination of one or more rollers 2 of a section of a web-processing machine and from this statistical evaluation options on the temporal and local course of the construction of impurities on rollers 2 in certain To open positions or sections of a web-processing machine. This allows, for example, the preparation of predictions about the structure of impurities, possible effects on the railway manufacturing process and possible hazards in certain positions or under specified operating conditions. As a result, it is possible to selectively counteract and thus ensure a high quality of the final product with reduced risk of malfunction and shutdown of the machine.

FIG. 2 shows in a similar representation as in FIG. 1 a modified embodiment of a device designed according to the invention. In contrast to the very simplified embodiment illustrated in FIG. 1, illumination with an LED light strip 9 and a plurality of line scan cameras 3 'are provided in FIG. 2 in order to reliably and conveniently record a complete image of the roll surface. For example, a single sensor unit 3 may not be sufficient if the length of the roller 2 exceeds a certain value. In addition, individual line scan cameras 3 ', each of which covers only one area, are more cost-effective than a long sensor unit 3. Roller lengths of 10 m and more are no longer a rarity in the paper industry. Furthermore, it is conceivable and possible to not only detect contamination with the device according to the invention and to control the Beschaberung accordingly, but also to detect the degree of wear of roll covers or coatings. For this application, an additional possibility of the display would then be provided, which informs the process control system when a roller 2 has run in or is worn out too much.

The invention is not limited to the illustrated embodiments. Thus, for example, more than one sensor unit 3 can be connected to the evaluation unit 5, wherein the sensor units 3 can then be arranged on different rollers 2 or on the same roller 2, for example in positions opposite one another. It is possible to couple a plurality of sensor units 3 with a plurality of evaluation units 5 and the latter to one another to achieve more spacious surveillance. The connection or integration of the evaluation units 5 in the machine control is also possible.

Claims

claims

Device (1) for conditioning, in particular for doctoring, a roller (2), in particular in a web-making, processing and / or finishing machine, such as a paper, board, tissue or film machine, comprising at least one sensor unit (3). , which is arranged in the region of the roll (2) to be conditioned, and at least one evaluation unit (5), characterized in that at least a part of a surface of the roll (2) is designed so that the surface by means of the at least one sensor unit (3 ) is detectable and that the degree of contamination by a contrast between clean and dirty surface portions and / or pattern recognition and / or image recognition by means of the evaluation unit (5) can be assessed.

Apparatus according to claim 1, characterized in that at least one scraper unit (6) is provided, which is arranged in the region of the roller (2), that upon detection of exceeding a threshold value of contamination, the at least one scraper unit (6) by the evaluation unit ( 5) and in tribological contact with the surface of the roller (2) can be brought.

Apparatus according to claim 1 or 2, characterized in that the

Surface of the roller (2) consists at least partially of a UV-fluorescent material or a mixture of materials with UV-fluorescent particles or is provided with a coating which has UV-fluorescent material or a material mixture with UV-fluorescent particles.

Apparatus according to claim 3, characterized in that a UV light source is present, through which the surface can be illuminated with UV light and that the at least one sensor unit (3) as an image camera, line scan camera, UV camera and / or UV sensor is.

5. Apparatus according to claim 1 or 2, characterized in that the

Surface of the roller (2) is designed heat-carrying capacity and that by the at least one sensor unit (3), the degree of contamination on the basis of the detection of warmer and colder areas is measurable. 6. A method for monitoring properties of a roller (2), in particular in a machine for producing and / or finishing a fibrous web, in which at least one surface region of the roller (2) by means of at least one sensor unit (3) is detected and determines the degree of contamination is that the contrast between clean and dirty surface portions and / or a pattern and / or a picture by means of an evaluation unit (5) is detected and assessed.

7. The method according to claim 6, characterized in that the soiled surface portions are cleaned by means of at least one scraper unit (6), which is controlled and regulated by the evaluation unit (5) in dependence on the determined degree of contamination.

8. The method according to claim 6 or 7, characterized in that the at least one scraper unit (6) is brought into contact with the surface of the roller (2) when a first threshold value of contamination is exceeded. 9. The method according to any one of claims 6 to 8, characterized in that falls below a second threshold, the at least one scraper unit (6) from the surface of the roller (2) is pivoted.

10.A method according to claim 8 or 9, characterized in that the second threshold value is smaller than the first threshold value.