FI111176B - A method, apparatus, and use thereof for controlling a paper machine roll - Google Patents

Description

111176 METHOD, APPARATUS AND ITS USE TO CONTROL THE PAPER MACHINE ROLL.

The present invention relates to a method and apparatus for monitoring a roll of a papermaking machine according to the preamble of claim 1

Since the 1970s, paper machines have been using "soft" calender rollers for paper calendering. These provide better-10 quality paper than a conventional metal / metal calender roll. The softness of the calender roll is achieved by a polymer coating, for example a polyurethane, hard rubber, epoxy coating.

However, a soft calender roller is more vulnerable to damage than a traditional hard roller. 15 The calender rolls have very high compression pressure and the rolls are at high temperatures during operation. To prevent damage, the operation of the rolls is monitored, for example, by a non-contact infrared thermometer which detects overheating points on the calender roll surface. Heating may result in damage to the sensitive surface. Temperature measurement based on infrared radiation emitted by the roll surface reveals a process failure at a relatively late stage, and damage to the roll may not be prevented. Roll roll repair is expensive and the paper machine produces nothing during the repair process.

It is an object of the present invention to overcome the above disadvantages. The method and apparatus for monitoring the roll of a paper machine according to the invention are characterized in the claims. In the solution of the invention, the surface of the roll is monitored by a fast-acting electronic camera of substantially visible light. The wavelength range of the light used in the invention is typically from about 400 to about 900 nm. If necessary, the wavelength range can be specified to a specific spectral range if, for example, the absorption or reflection properties of the interferer are limited to a specific range. The principle of operation of the 111176 according to the invention is that the electronic camera controlled by the microcomputer stores in its memory the multicolored appearance of the calender roll at several points along the axis of the roll and in the event of a malfunction the system gives an alarm.

The invention will now be described in more detail by way of example with reference to the accompanying drawing, in which

Figure 1 illustrates a preferred method for carrying out the method of the invention, 10

Figure 2 shows an imaginary distribution of the darkness of the roll surface,

Figure 3 illustrates a preferred camera hanger and lamp position relative to the camera from the side, in the direction of the roll axis.

15

Figure 1 shows a preferred way of illuminating the surface of a roll (1) with lamps (3,4,5) such that a diffusely illuminated view of the surface (2) of the roll (1) is obtained for the cameras (6,7) in the viewing cone (8).

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Each camera (6,7) is provided with a lens (20) which focuses the distribution of the surface darkness of the roll on the electronic image sensor (21) inside the camera. As an image sensor, it is advantageous to use, for example, a CCD (Charge Coupled Device) line detector. Such a detector preferably has, for example, about 2000 to 25 pixels, but may be, for example, 128 to 15,000 depending on the situation. Such an image sensor can read the axial distribution of the darkness of the roll surface along the line to which the camera is aligned.

Figure 2 shows an imaginary distribution of the density of the roll surface. The vertical coordinate (19) is proportional to the darkness of the surface of the roll, and the 3111176 axial coordinate (18) represents the different locations of the roll. The density curve (17) has bright (22) and darker (23) spots. Our example image has 2048 consecutive points. For example, the distance between them on the surface of the roll in the object plane is, for example, 0.5 mm, if one camera is set to look at 5 portions of the surface of the roll for 1 meter. As the roll rotates about its axis, the apparent density variation of the roll surface is reduced and the contrast between the various points is minimized if the detector receives light at each resistor for at least the time it takes for one roll of the roll to rotate. By way of example, if the roll surface had a circumference of 1 meter and a web speed of 10 meters per second, one 10 exposure time would be at least 100 milliseconds so that each point on the roll surface would appear at least once in each image.

Figure 3 shows a preferred side view of the camera (6) with respect to the calender roll (1), the counter roll (32) and the paper web (33), in particular from the axial direction of the calender roll (1). It is preferable to mount the lamp (3) so that diffuse reflection (31) is obtained in the direction of the camera rather than glare reflection (30).

The camera records a clean, naturally blurry, "signature" image of the roll surface in its memory, for example, with the approval of the operating personnel. An acceptable density profile (17) is stored, for example, in RAM, EEPROM, or FLASH.

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The camera processor can update slow changes in the help profile to its memory. Such slow changes can be caused, for example, by the accumulation of dust on the surface of the optics, the contamination and / or aging of the lamp (3).

25 In the event of a malfunction, the surface of the roll may suddenly become dirty, causing the compression pressure to increase at that point. This dirt can be, for example, a paste due to a malfunction of the coating device, etc. Such a malfunction is most likely to occur.

min in the area where the edge of the paper passes, but may also occur in the center of the roll. The dirt is immediately visible as changes in the camera's intensity profile (17). Figure -30a2 shows the intensity peak (24) caused by the light damp spot and the intensity name (25) of the dark dirt area. The camera's programmed processor immediately recognizes this type of interference in the signal and can provide an alarm (16), for example, at closing relay tips or other suitable means.

According to Figure 1, the entire roll area is most preferably monitored by a plurality of cameras (6,7) connected by wires (9,10) to a separate hub device (11) which, if necessary, provides a centralized alarm (15). The hub (11) can also be connected (12) to the control panel computer (13) and its alarm system (14). Communications may be based on galvanic wires (RS485, RS232, etc.), optical fiber, infra-10 red link or the like. Based on their experience, operating staff can set limits on the amount of reported malfunction (26,27). The magnitude of the interference is calculated as the positive or negative difference from the accepted base image (17). The alarm can also be based on the number of pixels in which the disturbance occurs (28,29). Thus, when tuned to its highest sensitivity, the device 15 will detect a 0.5 mm wide interference trace within a 1 meter viewing area. The above figures are exemplary only, it is natural that the device can also be set to monitor a narrower or wider zone. For setup and tuning, each camera's darkness profile can be requested from the control room computer.

The invention further relates to the surface * of a roll (1), in particular a soft calender roll.

(2) using an electronic camera (6,7) for monitoring one or more substantially visible light areas to monitor the paper machine roll (1).

As stated above, it is essential to the invention that the electronic camera 25 stores in its memory and automatically learns to know its area from the Variable surface of the calender roll. The camera quickly informs operating personnel in less than a second that, for example, coating paste or other solids have suddenly appeared on the press nip. Based on the alarm, the press nip between the calender rollers can be opened immediately and the roll surfaces cleaned before the rolls 30 are damaged.

5, 111176

The wavelength range utilized in the invention can, if necessary, be specified and defined according to different needs, for example in a specific spectral range. In addition, the device of the invention adapts to the lamp or optic contamination at the desired time constant (e.g., 4 hours), but responds immediately to sudden changes. 5 Updating the setpoint or setpoint is interrupted whenever an alarm occurs. The alarm disappears when the fault is resolved. The device can compensate for contamination, etc. by changing its own shutter speed, but still gives the user a warning. The basis for the alarm can be determined by the magnitude or width of the darkening deviation.

10

In the device according to the invention, readily available fluorescent lamps or the like can be used as a light source. Staff can check the operation of the device if desired by placing the camera in the field of vision in front of the roll, for example, a piece of wire hanging. This should cause an alarm depending on how the alarm limits are set.

The camera's processor is equipped with so-called. with watchdog feature: The processor program starts automatically from scratch if, for example, an external power failure has set the program in a mess. A warning will be given to the user. Stopping the roll rotation 20 always gives an alarm because the staggered roll variance exceeds the # # variability around the rotation.

It will be apparent to one skilled in the art that various embodiments of the invention are not limited to the foregoing, but may vary within the scope of the appended claims.

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Claims (10)

111176 A method for monitoring a roll (1) of a papermaking machine, characterized in that the surface (2) of the roll (1), in particular the soft calender roll, is monitored by one or more 5 substantially visible light areas, preferably by an automatically operating electronic camera (6,7). Method according to Claim 1, characterized in that the microcomputer-controlled electronic row detector type camera (6,7) stores in its memory 10 the appearance of the surface (2) of the calender roll (1) at several points in the axis direction and in a disturbance or similar change, e.g. or a sudden change thereto, the programmed processor of the camera (6,7) generates an alarm (16). 3. Förfarande enligt patent krav 1 eller 2, tiltecknat av att valsens (1) polymer-eller förderning (2) in the inner flasher lamp (3,4, 5), att för camera (6,7) 8) omrade fäs en företrädesvis 20 varäsentligen diffust (31) belyst vy av valsens (1) (2). Method according to Claim 1 or 2, characterized in that the polymer or corresponding surface (2) of the roll (1) is illuminated by one or more lamps (3,4,5) such that a viewing cone (8) is obtained for the camera (6,7). ), preferably a substantially diffusely illuminated view of the surface (2) of the roll (1). 4. Förfarande enligt face av patent kraven 1-3, tiltecknat av att man med cameraans (6,7) Objective (20) focusser valsens (1) mörkhetsfördelning pa cameraans (6,7) electronic image sensor (21). 25 Method according to one of the preceding claims 1 to 3, characterized in that the lens (20) of the camera (6,7) focuses the density distribution of the roll (1) on the electronic image sensor (21) of the camera (6,7). 5. Förfarande enligt face av patentkraven 1 - 4, tiltecknat av att camera in synnerhet in fall att under uppfõlningsperioden inte har getts alarm (6, 7) uppdaterar slør styrprofilsänderringar here, account exempel i et RAM, EEPROM eller -where. 30 Method according to any one of claims 1 to 4, characterized in that:. 25 that the camera (6.7) updates slow changes in the instruction profile to its memory, such as RAM, EEPROM or FLASH, especially if there were no alarms during the tracking period. 30, 111176 6. Anordning för åvervakning av en Vals (1) i en pappersmaskin, kännetecknad av att man för ævervakning ytan (2) av en Vals (1), särskilt en mjuk kalervervals, har anordnat en eller flera väsentligen inom det synliga ljusets omräde automatiskt electronic camera (6, 7) i riktning av 35 valsens (1) Axel. 9111176 Apparatus for monitoring the roll (1) of a papermaking machine, characterized in that one or more electronic cameras (6,7) of substantially visible light are arranged along the axis of the roll (1), in particular the soft calender roll surface (2). ). 5 7. Anordning en patent patent application 6, a rotating device for bel valing an valsens (1) polymer-elleric lantern (2) and a valentine axel har anordnat en eller flera lampor (3, 4, 5) som monterade sa, att för camera (6, 7) inom blickconens (8) omrade fas en väsentligen diffust (31) belyst vy av 5 valsens (1) yta (2). * Apparatus according to Claim 6, characterized in that one or more lamps (3,4,5) are arranged so as to illuminate the polymeric or corresponding surface (2) of the roll (1) and mounted so that the camera (6,7) ) provides a substantially diffusely illuminated view of the surface 10 (2) of the roll (1) in the viewing cone (8). 8. Anordning enligt patent application 6 eller 7, a telescopic camera (6, 7), and an electronic image sensor (21), and a radar detector system (16), an av 10 lamp. (3, 4, 5), av en concentrator (11) som vid behov and copplad till en control drum (13) and d larmsystem (14), also av centralizing larmsystem (15). Device according to Claim 6 or 7, characterized in that the device consists of a microcomputer controlled line-detector-type camera (6,7) with an electronic image sensor (21), an alarm system (16) thereof, a lamp (3,4,5), 15 hub devices (11) connected, if necessary, to the control panel computer (13) and its alarm system (14) and the centralized alarm system (15). 9. Användning av en eller flera, väsentligen inom det synga ljusets omrade 15 fungerande kamoror (6, 7) som værk ytan (2) av en Vals (1), särskilt en mjuk fishing verns, för ververvning av en Vals (1) i en pappersmaskin. Use of an electronic camera (6,7) of a roll (1), in particular of one or more substantially visible light areas, monitoring the surface (2) of a soft calender roll to monitor a roll (1) of a paper machine. «« Use of a camera (6,7) according to claim 9 for monitoring and alerting the size and / or width of a darkness deviation caused by a sudden change in the roll (1), in particular the surface (2). 9 8 111176 $ 1. Förfarande för övervakning av en Vals (1) i en pappersmaskin, kännetecknat av att manövervakar ytan (2) av en Vals (1), särskilt en mjuk kalervervals, med en eller flera väsentligen inom det synliga ljusets omräde, företrädesvis automatiskt fungerande electronic camera (6,7). 10 2. Förfarande enligt patentkrav 1, telecommand av att en persondatorstyrd, electronic camera (6, 7) av raddetektortyp i flera puncture i croting av valensens Axel lagrar utseendet hos ytan (2) av calendervalen (1) i here min och att camera ( 6, 7) programmerade processor vid störning eller motantvarändring, account exempel vid en plötslig änderring som sker pa ytan (2) eller som 15 corrupt mot den, ger alarm (16). 10. Användning enligt patentkrav 9 av camera (6, 7) för att øvervaka storleken och / eller bredden av en mörkhetsavvikelse som förekommer hos en Vals (1), 20 roaches (2), eller mot denää Grund av en plötslig ändring samt för att ge alarm för den. 25 • * (»· *