FI89087B - Heatable roll - Google Patents

Description

89087

Heated roller Upphettbar Vals 5

The invention relates to a heated roll for wet pressing paper or paperboard which is in direct contact with a paper or paperboard web during driving and which roll comprises a hollow tubular roll jacket heated by a heating medium in which the roll 10 is formed substantially in proximity to the outer surface of the roll jacket. ducts or the like extending from the first end to the second end through which the heating medium is circulated to heat the outer surface of the roll shell.

15 The paper and board machine uses rollers that can be heated in several locations. Such items include, for example, the press section of a paper machine and a calendar. In particular, it is very advantageous for the press section to use a heated roll to heat the web, since such an arrangement provides considerable savings in the consumption of steam 20 in the drying section of the web. The present invention relates specifically to a roll used in the wet pressing of paper.

The prior art is familiar with several different arrangements for heating a roll. One previously known solution is to heat the roll with steam, in which solution a hollow roll is used, and the hot steam is introduced inside the roll to heat the inner surface of the roll shell. The formed condensate water is generally removed, e.g. by means of zions or the like, and led out through a hole formed in the central axis of the roll. The disadvantage of such a solution is that since the roll shell is very large in thickness, usually of the order of 100 mm, heating causes a harmful thermal gradient. Also, the roll heated in this way cannot be realized in a deflection-adjustable manner, because deflection control devices cannot be arranged inside the roll. Another previously known solution is one in which the roll consists of a rotating roll shell and a non-rotating displacement body 33 arranged inside it. In such an arrangement, hot water or oil is circulated between the roll shell and the displacement body. Also in this solution the great disadvantage of the creation of harmful thermal gradient. Furthermore, 2,39087 solutions are known in which either one or more axially through holes are drilled in a solid roll and hot water is circulated through these holes. Such rolls also involve the generation of a detrimental thermal gradient, and a common disadvantage 5 for all the above-mentioned rolls according to the prior art is that they cannot be implemented as deflection-compensated. In deflection-cored rolls, the heating is generally carried out by heating with an oil which is introduced into the roll and sprayed on the inner surface of the roll shell by suitable equipment. Such a solution-10 mouth is also associated with the formation of a detrimental thermal gradient.

It is an object of the present invention to provide a novel heated roll which avoids the disadvantages associated with the previously known solutions and which is particularly suitable for use in the wet pressing of paper or board. The roll can be used, for example, as the center roll of the press section of a paper machine.

In order to achieve the object of the invention, the invention is mainly characterized in that the supply of heating medium is arranged in every other channel from the first end of the roll and outlet from the second end of the roll, and correspondingly fed to every other channel from the second end of the roll and out of the first end of the roll. .

Among the advantages achieved by the invention, it can be pointed out in this connection e.g. the fact that the roll according to the invention is not associated with a harmful thermal gradient and, on the other hand, the fact that the roll according to the invention can also be realized with deflection compensation. Other advantages and features of the invention will become apparent from the following detailed description of the invention.

Figure 1 is a schematic longitudinal cross-section of an embodiment of a roll according to the invention.

Figure 2 is an enlarged view of point A of the roll of Figure 1.

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Figure 3 is a partial sectional view taken along line B-B of Figure 2.

Figure 4 shows a partial cross-section of an alternative embodiment of a roll according to the invention.

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In Figure 1, the roll is generally indicated by reference numeral 10. The roll 10 is intended in particular for use in the wet pressing of paper or board, which is in direct contact with the paper or board web during driving. The roll 10 according to Figure 1 comprises a hollow roll shell 10 consisting of a shell body 11 and a substantially thinner shell surface layer 12 mounted on the body 11. The outer surface of the roll shell is indicated by reference numeral 13 in Figure 1. In the embodiment of Figure 1. grooves 14, which according to Fig. 3 are arranged in a plurality of circumferences 15 of the sheath body 11. Said grooves 14 together with the surface layer 12 of the casing are bounded by channels extending from end to end of the roll. In order to heat the roll 10, the heating medium is arranged to circulate in said channels 14.

The roll according to Figure 1 is not deflection compensated, but the ends 15,25 with shaft pins 16,26 are attached to each end of the roll shell 11,12. The ends 15,25 are fixed to the roll shell by fixing screws 18,28 or similar fixing members. As shown in Figs. . Correspondingly, through the grooves 14 at said annular spaces 33,35 are formed radially through-through bores 30 in the jacket body 11, thus connecting said grooves 14 to annular spaces 33,35 and further through radial tubes 32,34 to the heating medium supply tube 30. According to Figure 3, said radially the bores are formed in the shell body 11 so that in the adjacent channels 14a, 14b said radial bores 20 are arranged in the region of the opposite ends 15,25 of the roll 10. This causes the heating medium to flow in opposite directions in the adjacent channels 14a, 14b. With this arrangement, the temperature distribution of the roll shell is made uniform in the axial direction of the roll.

To direct the heating medium away from the roll 10, a heating medium outlet pipe 31 is arranged in the roll, which is coaxial with the supply pipe 30. Radial bores 17, 27 are formed at each end 15,25 of the roll, connecting the channels 14 to said outlet tube 31. Seals 38 are provided at the ends of the roll shell in the channels 14a, 14b to which the radially through-bore 20 is connected at said end 10 so that the heating medium does not cannot flow out of the same roll end from which it is fed to said channels. This arrangement forces the heating medium to flow from one end of the roll into the channel and out of the opposite end. Since in the embodiment of Figures 1-3 15 the channels consist of grooves formed in the shell body 11 and a surface layer 12 arranged on the shell body, in this embodiment the channels do not have to extend over the roll shell in the axial direction, but can be e.g. helical.

Fig. 4 schematically shows an embodiment of a roll according to the invention, in which the roll indicated by reference numeral 40 is a deflection-compensated roll. The roll 40 thus comprises a stationary roll shaft 42, on which the roll shell 41 is arranged to rotate. Arranged in the space between the roll shell 41 and the roll shaft 42 are deflection control devices 43 acting on the inner surface 44 of the roll shell, by means of which the profile of the roll shell can be adjusted in a controlled manner. The embodiment of Figure 4 further differs from the above in that the channels in the roll shell 41 preferably comprise bores 46 formed axially in the roll shell 41. According to Figure 4, the bores 46 are formed in the roll shell 41 substantially near the outer surface 45 of the shell to minimize thermal gradient formation.

The invention has been described above by way of example with reference to the figures of the accompanying drawing 35. However, the invention is not limited only to the examples shown in the figures, but many modifications 5,89087 are possible within the scope of the inventive idea defined in the appended claims.

Claims (6)

6 89087 A heated roll for wet pressing paper or board which is in direct contact with a paper or board web during travel and which roll (10; 40) comprises a hollow tubular roll shell (11,12; 41) heated by means of a heating medium, in which the roll shell (11, 12; 41) is formed with channels or the like (14, 14a, 14b; 46) extending substantially in the vicinity of the outer surface (13; 45) of the roll shell from the first end to the other end of the roll shell (11, 12; 41); The heating medium 10 is rotated to heat the outer surface (13; 45) of the roll shell, characterized in that a supply of heating medium is arranged in every other channel (14, 14a; 46) from the first end of the roll and outlet at the second end of the roll, respectively. 46) from the second end 15 of the roll and the removal from the first end of the roll so that in the adjacent channels (14, 14a, 14b) the heating medium only passes in all directions. Roll according to claim 1, characterized in that the roll shell comprises a shell body (11) with grooves (14, 14a, 14b) on its outer surface and a surface layer (12) attached to said body (11) so that said body ( 11) the grooves (14, 14a, 14b) and the surface layer (12) of the jacket delimit channels for the heating means. Roll according to Claim 1 or 2, characterized in that radial bores (20) for the supply of heating medium extending from the interior of the roll shell to the channels (14, 14a, 14b; 46) are formed in the roll shell (41) or the shell body (11) in the region of the roll ends. , that in adjacent channels (14, 14a, 14b; 46) said radial bores (20) are arranged in the region of the opposite ends of the roll. Roll according to Claim 3, characterized in that the heating medium supply pipe (30) is arranged centrally on the roll (10, 40) 35 and is connected to the radial bores (20) of the roll shell 7 89087 (11, 12; 41) at each end of the roll by one or more with a radiah flag tube (32,34). Roll according to any one of claims 1, 3 or 4, characterized in that said channels comprise bores (46) formed in the roll shell (41). Roll according to one of the preceding claims, characterized in that the roll (40) is a deflection-compensated roll 10 known per se, which is provided with a fixed central shaft (42) and deflection control devices (43) acting on the inner surface (44) of the roll shell. e 89087