FI122003B - Method for lubricating the paper / board or finishing machine's bending-compensated heated roller and bending-compensated heated roller - Google Patents

Description

The present invention relates to a method for lubricating a deflection-compensated heated roll of a paper / board or post-processing machine, which also has an inner shaft having a a shaft pin surrounded by a radial play on the center portion by an outer jacket having at its axial ends 10 radially inwardly extending end flanges disposed about a respective shaft pin wherein the heating medium is rotated from the outside of the roll to thence back to the inside of the inner shaft and back to the outside rotation of the roll 15 where the roll is inside the outer surface of the center of the shaft or the inner surface of the outer shell being bombarded, the inner surface of the outer shell of the roll being in contact with the outer surface of the inner shaft substantially throughout its axial length, using a hot lubricant. The invention further relates to a deflection compensated heated roll of a pa-20 per / carton or finishing machine.

^ In many parts of a paper / board or finishing machine, the rolls of the machine are loaded so that the load causes the rolls to bend. In the case of nip rolls § 25, the deflections affect the uniformity of the nip load and, in the case of the guide rolls, the uniformity of the tension of the controlled web. Guide rollers used e.g. for guiding the fiber web, fabrics and metal belt calender metal belt σ>.

cn tn σ> o ^ 30 In cases where the deflections become too large, the deflections must be compensated to reduce uneven loading. The known technique is to use a so-called. deflection compensated rolls, or simply use bombing on rolls, whereby the roll diameter profile corrects the load difference caused by the roll deflection line. However, bombardment cannot be used on a guide roll of a tissue or metal belt, because the surface speed differences produced by the difference in diameter within the roll cause rapid wear of the tissue or metal belt. The so-called "paper machine" fabrics have been developed for paper machine fabrics. a center-supported roller having a roller divided into an inner shaft and an outer jacket, and the outer jacket being supported centrally to an inner shaft. In this case, the outer sheath bends under load so that the difference in tension caused by the deflection of the other rolls is offset.

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However, the belt guide rollers of the metal belt calender cannot be made as centrally supported rolls because the belt load is too high and the rolls need to be heated. This is solved by making the roll so that it is divided between the inner shaft and the shell and the outer surface of the inner shaft or the inner surface of the shell is bombarded. In this case, the outer shell of the roll rolls freely on the surface of the inner shaft and, when loaded, due to the deflection of the inner shaft, the outer shell over its entire axial length contacts the inner shaft. In the volume between the shaft and the sheath, a medium for warming the roll, preferably a heat transfer oil, passes.

Figure 1 shows one such deflection compensated roll as disclosed in the applicant's previous Finnish patent application FI20065824. The roll 10 comprises a shaft 12 consisting of a cylindrical center portion 12c and a shaft end 12a, 12b at both ends of the center portion 12c, which are mounted on end bearings 13a, 13b. The central portion 12c of the shaft 12 i S 25 is bombarded and fitted with a cylindrical shell i $ 2 pa 11 supported at both ends by end pieces 20a, 20b | through the ends of the middle portion 12c of the shaft 12. Each end piece 20a, 20b σ> is secured by bolts 21b to the ends of the sheath 11. Each end piece 20a, 20b

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is further sealed with seals 31a, 31b to the end of the housing 11 and seals 30a, 30b to the shaft pin 12a, 12b. Each end piece 20a, 20b is disposed around the shaft pin 12a, 12b such that the fitting allows a small radial movement 3. The end pieces 20a, 20b move with the shell 11 slightly radially relative to the shaft pins 12a, 12b in a situation where the shell 11 is subjected to external loading.

A first passageway 40 is formed through a shaft end 12b of one end of roll 10 and extends axially spaced from opposite end end 20a of the opposite end of the roll, where it is branched into a plurality of radial passageways 41. These radial passageways 41 extend into the space 12c of center 12 . In addition, a second channel 50 is formed through the shaft pin 12b, which surrounds the first channel 40 and extends axially inside the end piece 20b at the shaft pin 12b, where it branches into radial channels 51. These radial channels 51 also open. 12 in the space between the central portion 12c and the sheath 11. Along the first passage 40, oil can be supplied to the space 42 between the center 12c of the shaft 12 and the shell 11 near the opposite end piece 20a, from where the oil is led back to the end piece 20b through the grooves on the outer surface of the center 12c . The first channel 40 may consist of a tube.

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The roll 10 becomes or pum compensated as a result of bombardment of the center 12c of the shaft 12. In the unloaded condition, the inner surface of the shell 11 is attached to the outer surface of the center 12c of the shaft 12 at the center of the central 12c, but the ends 12c have a small gap between the inner surface of the shell 11 and the outer surface of the central portion 12c. When the roll shell 11 is loaded externally, e.g. with another roll, the middle portion 12c of the shaft 12 begins to deflect from the middle and | at a given load, the deflection of the inner shaft is such that the inner surface of the sheath 11 engages the outer surface of the central portion 12c (g) of the inner shaft 12 throughout its travel, wherein the outer surface of the sheath 11 is straight at the point of loading. The bombardment of roll o 30 may be dimensioned such that the outer surface of the shell 11 becomes straight under the desired loading conditions.

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The surface velocity of the roll is constant, since the casing can be manufactured as a tube of uniform diameter. This prevents slipping between the outer surface and the metal belt contact. Instead, the contact between the inner surface of the sheath 11 and the outer surface of the inner part 12 of the inner shaft 12 is slip due to bombardment and this contact requires lubrication. As the process requirements require that the roll be heated to temperatures above 200 ° C, the lubricity (viscosity) of the heat transfer oil is not good enough. For this reason, a solid lubricant may be added to the heat transfer oil, as disclosed, for example, in the applicant's prior patent FI 120216.

The heating medium used for the heat transfer, preferably the oil, is further admixed with a solid lubricant which is mixed with the oil in powder form. The concentration of the additive is 1 to 5% by volume. As an additive, e.g.

15 tungsten disulfide (WS2), molybdenum disulfide (MoS2) or graphite powders. In the export-front situation, the lubricant in the oil is rolled onto the rolling surface, filling the surface roughness volume, thus preventing the occurrence of a limit lubrication. In addition, a thin film of lubricant with low shear strength is formed on the surface. In the sliding condition, the lubricant film 20 on the surface is sheared, thereby not exceeding the shear strength of the inner shaft and the sheath material. The additive detached from the surface drifts back into the oil cycle and the substance in the oil cycle re-adheres to the surface upon rolling contact.

^ Em. lubricants are chemically inert to very high temperatures up to § 25 where they do not affect the properties of the base oil. Neither do they "dissolve in oil, but they remain small particles among the oil. About this autumn | it is preferred that the particles have a small particle size, preferably less than about 1.5 microns σ> meters. However, in the case of an oil heating system, the insolubility and particulate matter of the particles do not pose a problem since the system preferably does not contain a tank of 30 particles in which the particles are separated from the oil and the oil circulates continuously in the system. However, pipeline design should take into account that the pipeline will not be constructed with downward facing branches at low flow rates, e.g., less than about 0.2 m / s. In these situations, solid particles can settle to the bottom of the tube and can cause the tube to become clogged and, in addition, the lubricant content of the oil decreases.

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At about 250 ° C, the properties of the solid lubricant and heat transfer oil are no longer sufficient to lubricate the contact between the shaft and the inner surface of the sheath.

The object of the present invention is to provide an improved solution 10 whereby the contact between the inner surface of such a deflection compensated roll shell and the outer surface of the inner axis can be reliably lubricated at elevated temperatures of about 250 ° C and above. To achieve this object, the method according to the invention is characterized in that the method utilizes a roll having an inner surface and / or a surface of the shaft coated or surface-treated to increase its hardness and / or reduce the coefficient of friction.

By way of example, the surface treatment of the inner surface of the jacket and / or the surface of the shaft with carbon dioxide may be mentioned. This results in the formation of 20 hard and wear-resistant compound layers (about 5 to 20 µm) with a low coefficient of friction and a diffusion layer of about 0.1 to about 0.4 mm thick on the surface of the subject to be nitrified. Such a surface treatment together with a solid lubricant used in heat transfer oil causes the lubrication to operate at a temperature of about 250 degrees.

Other alternative methods for performing surface treatment include e.g.

§ 25 different surface hardening methods, such as induction hardening, laser surface hardening, carbon hardening, nitrification and boronation processes, and various surface | coating methods such as electrolytic coatings, gas phase coating and diamond coatings.

The deflection-compensated heated roll of a paper / board or finishing machine according to the invention is characterized in that the inner surface of the 6 roll shell and / or the surface of the shaft is coated or surface treated to increase its hardness and / or friction. to reduce.

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Claims (3)

A method for lubricating a deflection compensated heated roll of a paper / board or finishing machine comprising an inner shaft 5 (12) having a cylindrical center portion (12c) having at each axial end a shaft pin (12a, 12b) surrounded by a central portion radial play with an outer jacket (11) having at its axial ends radially inwardly extending end flanges (20a, 20b) disposed about a respective shaft pin (12a, 12b) in which the roll heating medium 10 is circulated from the outside of the roll through the inner heating medium 40 , 41) into the heating medium space (42) between the outer surface of the inner shaft center and the inner surface of the outer shell, and back to the inner shaft (51) and back (50) to the outer roll, wherein the outer surface of the inner shaft center (12c) or with the outer casing of the roll included the surface being in contact with the outer surface of the inner shaft when loaded, substantially along its entire axial length, wherein the method utilizes a heating medium supplemented with a solid lubricant, characterized in that the method uses a roll coated or surface treated to increase its size. and / or to reduce the coefficient of friction. Process according to Claim 1, characterized in that the surface treatment is carried out by means of charcoal hydrogenation. δ (M 0 25 3. Deflection compensated heating roll of a paper / board or finishing machine, comprising a roller shaft (12) having a cylindrical center | a portion (12c) having at each axial end a shaft pin (12a, σ> 12b) surrounded by a radial play with an outer jacket (11) having σ> g at its axial ends having radially inwardly extending end flanges (20a, 20b); ) disposed about a respective shaft pin (12a, 12b) in which the heating medium is circulated from the outside of the roll through the inner axis of the inner shaft (40, 41) to and from the inner inner surface of the inner shaft and the inner surface of the outer shell (51) and back (50) to an external rotation of the roll in which the outer surface of the inner shaft center portion (12c) or the inner surface of the outer sheath (11) is bombarded, wherein the inner surface of the outer outer sheath that the inner surface of the roll shell and / or i The surface of the shaft is plated or surface treated to increase its hardness and / or to reduce the coefficient of friction. δ {M sj- o 00 X en CL σ> σ> m σ> o o {M