FI86209C - Process for producing a jacket for a roll or equivalent e, especially for a press roll in a paper machine - Google Patents

Description

86209

Method of manufacturing a roll or the like, in particular a press roll for a paper machine Förfarande för framställning av en mantel för en Vals eller motsvarande, speciellt för en pressvals 5 i en pappersmaskin

The invention relates to a method of manufacturing a jacket for a roll, a drying cylinder or the like, in particular a press roll for a paper machine, in which the surface jacket is formed from cylindrical bent and welded hollow-surface and / or smooth jacket plates.

Previously known methods for manufacturing a roll shell have been presented e.g.

FI patent publications 44076 and 44075. 44076 describes a coating method in which the roll body to be coated is surrounded by a thin tube or by plates bent around the roll body, which are welded together so as to form a tube. The tubular jacket is then surrounded by another tubular jacket, the surface layer 20 of which is brought into a molten state by welding or otherwise. Upon cooling, the uppermost sheath causes the inner sheath to compress around the roll body, after which the uppermost sheath can be removed, e.g., by sawing it through. 44075 discloses a coating method in which a shell is tightly fitted around a roll body by melting the outer surface layer of the shell, which, when cooled, causes the shell to shrink around the body. . after which the molten surface layer is removed either partially or * completely.

U.S. Patent No. 3,526,939 discloses a previously known coating method in which a shell is tightly fitted around a roll body by melting the outer surface layer of the shell, which upon cooling causes the shell to shrink around the body, after which the molten surface layer is removed by cutting. These above image. 35 methods require welding consumables as well as a lot of working time.

In addition, they undergo unfavorable changes in the microstructure of the material during over-welding.

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F1 Patent Publication No. 41489 discloses a method of making press rolls in which a thick-walled roll body is surrounded by a thin corrosion-resistant plate and an additive having the same composition as the plate is welded around the plate and which, when cooled, causes the plate to shrink around the roll body. A previously known method of manufacturing press rolls such as the one described above is also disclosed in SE patent publication 301416. Although the above-mentioned methods are useful per se, they nevertheless have certain limitations. The cover plate is e.g. be a highly weldable material. Since the welded filler generally has to be used in large quantities to achieve the desired shrinkage effect, the methods become relatively expensive considering that part of the surface layer must be removed by machining to provide a smooth surface. In addition, the methods are not suitable for obtaining thin coating layers, because over-welding 15 then presents difficulties.

In addition, a prior art method of making a grooved roll shell is disclosed in SU Patent Publication No. 324328. In this prior art method, a grooved roll shell is formed by connecting 20 radial groove-forming pieces together in the longitudinal direction of the roll. This method is cumbersome in construction.

Other prior art methods for making a grooved roll shell are disclosed in U.S. Patent Nos. 3,845,534 and 3,958,311. In these prior art methods, a grooved jacket is made from grooved rings which are heat-shrinked onto sheaths on a cylindrical roll shell. The above-mentioned construction according to the previously known methods is complicated and cumbersome to manufacture, whereby the structure becomes expensive.

• A previously known method of coating a roll is also disclosed in FI patent application 880725. In this previously known method, the length of the jacket plate is dimensioned to be smaller than the diameter of the roll body si -. **; 35 that when fitting the jacket plate to the roll body, the pi / plate of the jacket plate remains. too large a gap to be welded, and when the jacket plate is then heated, the heating member then causes thermal expansion, during which the jacket plate is tightened, whereby the gap is reduced so that the longitudinal seam of the jacket plate can be welded closed. In this previously known method, the heating takes place by means of a kind of resistance mat which completely surrounds the roll shell. The method has proved to be the most suitable for small rolls, because otherwise the resistance mat used for heating has to be made so large that it is difficult to handle. In addition, in an attempt to use this previously known method for large-diameter rollers 10, the electrical load required for heating becomes very high, whereby there are technical difficulties in connection.

The object of the invention is to provide a method which does not have the above-mentioned limitations or disadvantages and which is suitable for use in the production of metallic coatings.

It is also an object of the invention to provide a method suitable for use in coating rolls, drying cylinders or other similar machine parts which are exposed to corrosive and / or abrasive substances and which, in addition, require high rigidity and / or strength.

The object of the invention is to provide a coating method which is particularly suitable for the production of paper and cellulose machines, both grooved and perforated and smooth press rolls.

In order to achieve the above-mentioned and later-directed objects, the method according to the invention is mainly characterized in that the longitudinal seams 30 of the sheath plates bent into cylinders are at least partially welded before the sheath of the sheath plate cylinders. . from there on the roll body and that the jacket is shrunk by local heating by induction heating means.

Other advantageous features of the method according to the invention are set out in claims 2 and 3.

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When using the method according to the invention, e.g. the necessary holes and grooves in the casing can be made in advance before placing the casing on the surface of the roll or the like, whereby they are considerably easier to manufacture than when placed on the already finished body.

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The production of holes and grooves in the roll shell is made very advantageous when using the method according to the invention compared to the previously known methods in which the the holes and grooves were made by machining the finished roll surface, which is very expensive.

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The method of manufacturing a press roll casing according to the invention is also particularly advantageous in terms of energy costs, since induction heating is a very fast method and, in addition, less heat is transferred to the roll interior than in previously known heating solutions.

In the method according to the invention, it is possible to heat only those points where there is slack between the jacket and the body.

It is possible to apply the method according to the invention in connection with the maintenance of a previously manufactured roll, if it is then found that the casing is not tightly attached to the roll body.

"" Because the heating apparatus used in the method according to the invention is small in size and easy to move, possible repair work can be carried out under factory conditions without removing the roll from the paper machine.

The method according to the invention is also particularly advantageous for use in the manufacturing step, because it is fast and low in cost.

The invention will now be described in more detail with reference to the figures of the accompanying drawing, in which Fig. 1 schematically shows a method of manufacturing a jacket around a roll, Fig. 2 schematically shows a longitudinal section of a roll in the case of a grooved surface jacket, and Fig. 3 schematically shows a longitudinal roll. , in the case of a roller with blind holes.

The body 12 of the roll 10 shown in Fig. 1 is made of e.g. cast iron or the surface of the roll 10 is inductively or electrochemically (e.g. by brush coating) or thermally (by spraying) chemically resistant coating having a thickness of about 50-100 μπι.

The sheath 13 of the roll 10 is made by making a stainless or acid-resistant sheath on top of the unprotected roll body 12. In the embodiment shown in the figure, the sheath is smooth. The sheath 13 is made of separate sheath plates 11. Each sheath plate 11 is bent into a cylinder and its longitudinal seam 14a is crosslinked by welding. The jacket plate cylinders 11 thus obtained are pushed onto the body 12 of the roll 10 and tightened by means of tightening means, e.g. When all of the sheath plates 11 are in place, the longitudinal 14a and transverse 14b seams are welded. The jacket 13 is then shrunk by heating the jacket with induction * '* thio heating. In induction heating, shrinkage is achieved through a shrinkage phenomenon based on crystal structure changes known per se. When the material is heated above a certain temperature, the material undergoes crystal structure changes that cause it to shrink.

The heating elements 15 used in induction heating are placed, for example, radially at long distances "* * apart from each other in the longitudinal direction of the roll 12. The means used in induction heating can also be used to heat the jacket 13 locally so that it is first determined, e.g. there is slack between the body 12 and the jacket 13. The loose parts of the jacket are then heated by means of an induction heating strip of suitable shape and size, whereby the jacket shrinks tightly against the body.

In connection with the method according to the invention, any type of induction heating element is available which provides sufficient heating. For example, a smaller loop-shaped heating element can be used, which is moved, for example, radially in the longitudinal direction of the roll 12 in suitable heating zones.

When using the method according to the invention, the extra machining (turning) of the casing is eliminated and a thinner material is available as the casing plates 11. There is also no need for separate shrink welding, which saves manufacturing time, as no welding time is required and, in addition, no welding consumables or welding car-15 working time are required, which further achieves cost savings.

In the application example shown in Figure 2, an intermediate jacket 16 is made of a thin plate on the roll body 12. The intermediate jacket 16 is e.g. stainless or acid-resistant material and the thickness of the jacket plate varies from 0.5 to 20 mm, preferably from 1 to 1.5 mra. The intermediate jacket 16 is shrunk on the roll body 12 by the jacket seams, i.e. by the seams 14a, 14b according to Fig. 1 in connection with welding. In the embodiment shown in the figure, the surface jacket 17 is pre-provided with grooves 18. The surface jacket can also be of another type with a hollow surface, e.g. provided with holes (Fig. 3). Finished 25 The groove plate, i.e. the surface jacket 17, is pre-bent and the longitudinal seams of the jacket cylinder are pre-welded. If necessary, the intermediate jacket 16 is ground or · turned to provide sufficient roundness. The surface jacket 17 is then threaded onto the intermediate jacket 16, after which the transverse seams are welded and the entire jacket is shrunk using induction heating. : 30 en. The members used in induction heating may be longitudinal heating members placed radially around the roll, or other types of heating members for performing heating locally. It is also possible to use locally heated, portable induction heating elements.

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The center line of the roll is indicated by reference numeral C in Figures 2 and 3.

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According to Figure 3, the roll body 12 is coated with a coating 16 having a thickness of about 50-100. Coating can be done by chemical, thermal or inductive method. Instead of the coating 16, it is also possible to use the intermediate jacket 16 according to Fig. 2.

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The surface jacket 17 provided with blind holes 19 is manufactured by bending the perforated plate and pre-welding its longitudinal seams, after which the surface jacket 17 is threaded onto a roll body 12 provided or coated with an intermediate jacket 16. If necessary, the intermediate jacket 16 has previously been ground or turned to provide the required roundness. The transverse seams of the surface sheath 17 are then welded and the entire sheath is shrunk using induction heating. As the heating means, local, portable heating elements or longitudinal heating elements which are mounted radially around the roll shell or other similar heating elements used in induction heating can be used.

The invention has been described above only with reference to some of its preferred embodiments. The method according to the invention is applicable, for example, to the coating of shaft pins and other similar machine members, e.g. when the durability or other properties of the coating obtained by metal spraying are not sufficient. The method according to the invention is also applicable when carrying out a large-diameter icing rolling bearing sleeve during installation.

It is not to be construed as limited to the examples and figures set forth above, but, as will be apparent to those skilled in the art, many modifications are possible within the scope of the inventive idea defined by the following claims.

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Claims (3)

A method of making mannequins for a roller, drying cylinder or equivalent, in particular a press roll in a paper machine, wherein the surface jacket (17) is formed into cylinders from curved and welded casing sheets (11) with a grooved and / or smooth surface, in that the length joints (14a) of the casing discs (11) bent into cylinders are at least partially welded before the casing disc cylinders (11) are threaded onto the roller body (12) and causing the manpower (17) to shrink through local heating with induction heating means (15). 2. A method according to claim 1, characterized in that the induction heating means (15) are placed radially in the longitudinal direction 15 of the roller (10) at a suitable distance from each other. 3. A method according to claim 1, characterized in that the induction heating means (15) are placed locally in areas where there is looseness between the roller body (12) and the manifold (13; 16,17). 20