FI115778B - Arrangement for cleaning a roller surface - Google Patents

Description

115778 Arrangement for cleaning surface of roller

The invention relates, for example, to an arrangement according to the preamble of claim 1 for cleaning the surface of a roll.

5 The surface of the rolls used in the on-line equipment of the paper machine line and the separate off-line equipment will wear out, become dirty and damaged as the rolls press against the fibrous web passing over their surface. Therefore, the surface of the rollers should be cleaned and sanded from time to time.

Roll contaminants such as paper shreds and coating stains are usually cleaned with so-called scrapers where the scraper blade is pressed against the roll surface by pneumatic or hydraulic loading and unloading devices. Despite continuous cleaning of the roll, contaminants that impair the performance of the equipment remain on the surface of the roll, necessitating occasional cleaning of the rolls by completely removing them from the equipment for maintenance.

When calendering a fiber web, particularly in a roll between a heated hard surface thermo roll and a polymer-coated roll, the polymer coating often overheats locally, causing overheating points in the polymer coating. The quality of the polymer coating may deteriorate rapidly due to these supercooling * »* · points and therefore need to be rapidly removed by cooling the polish.

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:, 20 polymer rolls, for example, by opening the roll nip or cooling the polymer roll by:, · coplanar cooling, or providing effective internal or external cooling of the thermal roll. Internal cooling of the thermo roll is most commonly provided by thermo; By internal coolant circulation and external cooling of the polymer roll by spraying water or a rack of fibrous web on the peripheral areas of the polymer roll susceptible to overheating. Current roll cooling methods are in many cases sufficient to cool the roll, but as calendering methods and equipment evolve, there is a need for new cooling methods to select the optimum cooling method for each calendering method. The need for roller cooling techniques has now increased dramatically due to efforts to increase the temperature of the thermal roller to above 200 ° C.

The surface of the rolls gradually wears as they press against the fibrous web, causing them to. ; ; the surface becomes uneven, which reduces the quality of the paper. As a result, the rollers need to be sanded from time to time to remove unevenness. Another factor contributing to the roughness of the rolls is the increase in calendering temperatures, which accelerates the increase in roll roughness by 2,115,778. The roughness is due to the uneven transfer of heat from the inside of the roll to the surface of the roll, resulting in an uneven thermal expansion of the roll steel / cast iron surface. An attempt has been made to solve the latter problem by increasingly switching to high temperature calendering with induction heating of rolls using an external energy source. In such a heating mode, there is no or only minimal heat transfer from the inside of the roll to its surface. However, in this type of heating, it is easily a problem to cool the hot thermal roller in the event of paper change or unplanned downtime (e.g., breaking the fiber web). Turning the roll cooling off completely by induction heating is too slow, and providing a full-scale oil or water circulation inside the roll for cooling the roll only is not cost effective.

It is an object of the invention to eliminate the disadvantages of the prior art. Thus, the main object of the invention is to provide a combined roll cleaning and cooling process. It is a further object of the invention to provide a process for cleaning and cooling rolls which enables high temperature calendering. In particular, it is an object of the invention to provide a method which makes it possible to cool a thermal roller with external induction heating means.

....: The arrangement according to the invention achieves the above objects.

:. The invention relates, for example, to an arrangement according to claim 1 for cleaning the surface of a roll.

In the arrangement according to the invention, the roll is cleaned by bringing in a cleaning means. ' a cleaning means for contacting the roll surface. The roller cleaning means having an elongated body is rotatable about its frame and a liquid or paste cleaning agent is applied to the roller surface or to the cleaning means. The roll surface can also be cooled by said cleaning means.

. In a preferred embodiment of the invention, the roll to be cooled is a heated steel roll, preferably provided with external induction heating means, and the cleaning means is a roll or brush.

In another preferred embodiment of the invention, the body of the cleaning means consists of two parallel-mounted body rolls arranged to rotate an elastic endless belt. The endless belt has a thickness of about 5 to 10 mm and is made of a soft material such as a rubber and / or polymer blend and / or abrasive ingredients.

3,115,778

The invention is based on the fact that a certain area of the roll is cleaned by means of an elongate cleaning means of the body, which is also possible to cool the roll by feeding a cooling agent, such as water, between cooling means rotating about its longitudinal axis and the surface of the roll. This provides the advantage that the arrangement of the invention makes it possible to both clean and cool the surface of the roll, if necessary. Such a roll surface cleaning / cooling method is particularly suitable for a roll equipped with an external induction heating means, since the roll does not need to be provided with internal cooling means and the induction heating does not have to be occasionally switched off when calendering has to be interrupted. If a cleaning means is used in the invention, the body of which consists of two parallel-mounted body rolls arranged to rotate an endless belt, this further provides the advantage that the arrangement according to the invention also has the option of grinding the roll. To clean the roll, a cleaning agent is used which contains components which abrade the roll surface. The latter cleaning means further provides the advantage that the cleaning of the roll surface is effected by a soft and / or rough endless belt, whereby this cleaning means can be used, for example, to clean polymer rolls.

The invention will now be illustrated in more detail with reference to the accompanying drawings.

Figure 1 schematically illustrates one embodiment of an arrangement according to the invention applied to a multi-nip calender. The multi-nip calender is shown directly at the end of the calender.

Figure 2 also schematically shows another embodiment of the arrangement according to the invention applied to the cleaning of a single roll. The roll is viewed at 25 straight ends.

Figures 1 and 2 show two different embodiments of the arrangement according to the invention.

Figure 1 shows only that part of the multi-nip calender roller 5 which uses the arrangement 1 of the invention for cleaning and cooling roller 4. Figure 30 shows only the parts of a multi-nip calender essential to understanding the invention. For a more detailed construction of a multi-nip calender, reference is made to, for example, patent publication FI-96334. Multi-nip calender, "" shown in the figure. the portion of the track 5 comprises four rolls 4, which may be, for example, intermediate rolls of the track 5 provided with load compensation means. Second and fourth roll 4; 4 ", 4" "4 115778 are steel surface thermo rolls, the first of which is heated by external induction heating means (not shown). With regard to the more specific construction of the induction heating means, reference is made to the prior art known, for example, in the aforementioned publication. The first and third rolls 4 'and 4 "' 5, in turn, are polymer-coated rolls. The fibrous web W passes through the roll nipples N between the polymer rolls 4 ', 4'" and the thermal rollers 4 ", 4" "; N1, N2, N3 profiled on the same surface. Before moving from the roll nip to the next roll nip, the fibrous web W passes through the take-out rolls 6 outside the line L of the roll 5. Outside the track L, there is a thermal roller 4; 4 "adjoined roll cleaning and cooling means 2; 21 according to the invention, hereinafter referred to simply as cleaning means. Cleaning means 2; 21 has an elongated body protruding by small bristles not shown in the figure. Cleaning means 21 is not in contact with the thermal roll 4 during calendering. ; 4 ". Instead, in the event of a web break or paper change, when the thermal roller 4; 4 "is desired to be cooled, fed to a cleaning fluid 2 or a liquid mixture A, such as water, rotatable about its pi-15 axis and contacted with the surface of the roll. The liquid is fed either directly to the roll to be cleaned or, ; 21 for bristles. Preferably, the cleaning fluid is supplied as a fine mist from a metered portion, thereby providing a cooling surface of as large as possible. The cleaning means 2; 21 cleans and cools the surface of the roll 4, 4 "and does not need to be turned off. Cleaning means 2; 21 is secured to the body of a multi-nip calender or to a separate external lifting platform (not shown). To enhance the cooling power of Arrangement 1, cooling agents may be added to the cleaning fluid, such as water.

Figure 2 shows another embodiment of arrangement 1 according to the invention. The cleaning means 2 according to the figure; 22 is in contact with surface 4a of the chuck roll 4. The chill roll 4 is heated or unheated. Cleaning means 2; The body 2a 22 is a two-part body of body parts 2a formed by identical body members 2a 'and 2a "which are separated by a gap. 'and 2a; 2a ". The frame housings 2 can advantageously be moved relative to one another to tighten and loosen the belt 2b. As the housing rolls 2 are moved relative to one another, the longitudinal axes of said rolls remain approximately the same to maintain constant tension of the endless belt 2b • ·: 35 throughout the cleaning means 2; 22 lengths. With frame housings 2; 2a '' is moved farther apart, the endless belt 2b passing between them is tightened, and as they are moved towards each other, said endless belt is loosened. The belt material is a soft polymer / rubber blend, so that the belt 2b follows the surface of the roll 4; 4a curvature when in contact with said roll surface. With the roll surface 4; 4a to be cleaned, providing a cleaning means 2; 22 contacts with surface 4a of roll 4 and endless belt 2; 2b is tightened to a suitable tension by moving the frame housings 2a relative to one another. For endless belt 2 rotating on body rolls; 2b, a relatively small amount of suitable cleaning agent A (0.01-0.001 mm thick on the belt surface) is applied. At the same time, the housing rolls 2a and the endless belt 2b rotating around them are rotated at high speed. Partly by cleaning agent A, partly by roll surface 4; 4a and end-10 free belt 2; Due to the friction between the 2b, the surface 4a of the roll 4 is effectively cleaned. If the surface 4a of the roll 4 is also to be sanded, abrasive components are added to the cleaning agent A. The cleaning agent A is preferably a paste abrasive. Roll surface 4; It is also possible to cool 4a with the above cleaning means 2; 22; in this case, the cleaning agent A preferably contains cooling components and the housing 2a of said cleaning means 15 is rotated about its longitudinal axis at a lower speed.

The cleaning arrangement 1 shown in Figure 2 can be used alone or in combination with a scraper to clean the surface of the roll; The scrubbing performance is usually not sufficient to completely clean the surface of the roller, but other scrubbing methods are required in addition to the scrubber. The embodiment of the invention shown in Fig. 2 above can be used both when the roll 4 is stationary, for example during fiber changeover, and also when the roll is rotating. The roll cleaning means 2 of Figure 2; 22: '·. the frame rollers 2a 'and 2a "forming the body 2a are preferably shorter in length than the cleanable roll 4 and can be moved in the longitudinal direction of the roll to be cleaned, said roll 4 being capable of being cleaned along its entire length. The cleaning device according to Fig. 2 is simple in design and thus inexpensive.

Only certain embodiments of the arrangement according to the invention have been described above, and it will be apparent to one skilled in the art that the invention may be practiced in many other ways within the scope of the inventive idea set forth in the claims.

:. Thus, it is possible to apply the cleaning arrangement 1 according to the invention to cooling / cleaning / grinding a plurality of Y types of calendering rolls. Possible applications include, in addition to the heated chill rolls described above, 35 non-heated steel or cast iron rolls as well as polymer rolls and rolls with a soft roll coating in general. 6 115778 trembling unheated rolls of steel / cast iron are used, inter alia, in machine calendars, in which a calender nip is formed between two hard surface blades of cast iron or cast iron. In particular, the cleaning means of Figure 2 can also be used to clean the surface of rolls with a soft roll coating, since the cleaning line does not damage the roll coating due to the elastic endless belt used in the cleaning medium. Rolls with a soft roll coating are used for calendering e.g. multi nip calendars and long nip calendars such as ken calendars. In shoe calendars, the calendering nip is formed between an endless belt with a soft coating, rotating about a shoe roll, and a hard, heated steel surface roll. Rolls with a soft roll coating are also used in so-called soft calenders in which at least one of the rolls forming the roll nip is a roll with a soft roll coating.

The cleaning device according to the invention can also be used in press equipment for removing water from the fibrous web. In these press devices, water is dewatered in the press nip, which is usually formed between a hard roll and a soft-faced roll opposite. The soft-surface roller is often provided with pressurizing means and a press shoe with an endless belt wrapped around it.

It is also possible for the invention to be used for cleaning rolls used to transfer the bulking agent onto the fibrous web, since cleaning the rolls with conventional scrubbers is often not sufficient. In particular, the embodiment of the cleaning means shown in Fig. 2 is sufficiently effective also for this purpose.

Claims (7)

115778 An arrangement (1) for cleaning the surface (4a) of a roll (4), wherein the roll is cleaned by a cleaning means (2) by contacting the cleaning means (2) with the surface of the roll (4a) and / or the cleaning means (2). ) dispensing liquid or paste cleaning agent (A), characterized in that in the arrangement (1) - the roller cleaning means (2) having an elongated body is rotatable about its body (2a) and the body (2; 2a) of the cleaning device consists of two a roller (2; 2b) disposed parallel to said roll and arranged to rotate the ends) so that said belt follows the curvature of the roll surface (4; 4a) when in contact with said roll surface, - the roll surface (4; 4a) is also coolable by said cleaning means. (2). Arrangement (1) according to Claim 1, characterized in that the roll (4) to be cleaned is a heated steel roll. Arrangement according to claim 2, characterized in that the steel roll is provided with heating means external and / or internal to the roll. Arrangement (1) according to one of the preceding claims, characterized in that the surface of the roll (4; 4a) is arranged to be cooled by a liquid cleaning agent (A) containing components which cool the surface of the roll. »« Arrangement (1) according to one of the preceding claims, characterized in that the endless belt (2; 2b) has a thickness of about 5 to 10 mm and is made of a soft material such as rubber or a polymer blend. »* Arrangement according to one of the preceding claims, characterized in that the cleaning agent (A) is a pasty substance which, when rotated infinitely: 25 belts (2; 2b) about its longitudinal axis, in contact with the surface of the roll (4; 4a). .: abrades the surface (4a) of the roll (4). · ;;; An arrangement (1) according to any one of the preceding claims, characterized by * *; in that the cleaning means (2) is arranged to be movable in the longitudinal direction of the roll (4). 115778