CA2291213C - Heatable roll - Google Patents
Heatable roll Download PDFInfo
- Publication number
- CA2291213C CA2291213C CA 2291213 CA2291213A CA2291213C CA 2291213 C CA2291213 C CA 2291213C CA 2291213 CA2291213 CA 2291213 CA 2291213 A CA2291213 A CA 2291213A CA 2291213 C CA2291213 C CA 2291213C
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- Prior art keywords
- roll
- ducts
- mantle
- heating medium
- fitted
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
- D21G1/00—Calenders; Smoothing apparatus
- D21G1/02—Rolls; Their bearings
- D21G1/0253—Heating or cooling the rolls; Regulating the temperature
- D21G1/0266—Heating or cooling the rolls; Regulating the temperature using a heat-transfer fluid
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- Rolls And Other Rotary Bodies (AREA)
- Paper (AREA)
Abstract
The invention concerns a heatable roll for a paper machine, paper finishing device, or equivalent, which roll comprises a roll mantle (31) which is heated by means of a heating medium, into which roll mantle (31) ducts (32) or equival-ent extending from end to end in the roll mantle have been formed substantially in the vicinity of the outer face (34) of the roll mantle (31), through which ducts the heating medium has been made to circulate in order to heat the outer face (34) of the roll mantle (31). In view of reducing the temperature gradient in the roll mantle (31), ducts (32,33) or equivalent have been arranged in at least two circumferential rows (R1, R2), and the ducts (32, 33) or equivalent placed in two rows (R1, R2) fitted in the direc-tion of the circumference have been fitted as interlocked with each other so that the ducts (32, 33) are placed on different radial lines.
Description
Heatable roll The invention concerns a heatable roll for a paper machine, paper finishing device in order to heat the outer face of the roll mantle.
In paper and board machines and in paper finishing devices, in particular in calenders and supercalenders, as a rule, heatable rolls are used. Heatable rolls are also used, for example, in the press section of a paper machine. The heating of the rolls is com-monly arranged by means of a heat transfer medium, such as hot water, oil, or steam.
There are mainly two types of heatable rolls. On one hand, from the prior art, heatable rolls are known in which the roll mantle or a massive roll is provided with substantially axial bores formed in the vicinity of the outer face of the roll, through which bores the heating medium has been passed from end to end in the roll. As a rule, there are several such bores, usually uniformly distributed in the circumferential direction of the roll. In said bores, the heating medium may have been made to circulate either once from end to end through the roll, or twice or several times, so that in adjacent bores the heating medium may flow in opposite directions.
On the other hand, as heatable rolls, what is called double-mantle rolls or rolls provided with a displacement piece are used commonly, in which rolls a displace-ment piece has been fitted inside the roll mantle so that an annular intermediate space remains between said displacement piece and the circumferential face of the roll mantle, in which intermediate space a heating medium has been fitted to circulate from end to end through the roll.
From the prior art, a heatable roll is also known in which the main types of heatable rolls described above have been combined, i.e. inside heating has also been arranged in connection with a roll provided with axial bores along the circumference.
Such a roll has been described in the US Patent 5,072,497.
In paper and board machines and in paper finishing devices, in particular in calenders and supercalenders, as a rule, heatable rolls are used. Heatable rolls are also used, for example, in the press section of a paper machine. The heating of the rolls is com-monly arranged by means of a heat transfer medium, such as hot water, oil, or steam.
There are mainly two types of heatable rolls. On one hand, from the prior art, heatable rolls are known in which the roll mantle or a massive roll is provided with substantially axial bores formed in the vicinity of the outer face of the roll, through which bores the heating medium has been passed from end to end in the roll. As a rule, there are several such bores, usually uniformly distributed in the circumferential direction of the roll. In said bores, the heating medium may have been made to circulate either once from end to end through the roll, or twice or several times, so that in adjacent bores the heating medium may flow in opposite directions.
On the other hand, as heatable rolls, what is called double-mantle rolls or rolls provided with a displacement piece are used commonly, in which rolls a displace-ment piece has been fitted inside the roll mantle so that an annular intermediate space remains between said displacement piece and the circumferential face of the roll mantle, in which intermediate space a heating medium has been fitted to circulate from end to end through the roll.
From the prior art, a heatable roll is also known in which the main types of heatable rolls described above have been combined, i.e. inside heating has also been arranged in connection with a roll provided with axial bores along the circumference.
Such a roll has been described in the US Patent 5,072,497.
A prior-art heatable roll has been described in the FI Patent 89,087, in which roll the supply of heating medium has been arranged in every second duct through the first end of the roll, the discharge being through the second end of the roll, and similarly the supply of medium has been arranged into every second duct through the second end of the roll, the discharge being through the first end, so that the heating medium flows in opposite directions in adjacent ducts.
In the FI Patent 91,297, a heatable roll is described, which is provided with means by which the heat transfer coefficient from the flowing heating medium that acts upon the material of the roll mantle or of the roll to the roll material increases in the direction of flow of the heating medium. In said publication, a roll is also described which comprises a hollow roll mantle, into whose interior a displacement piece has been fitted so that an annular intermediate space remains between the roll mantle and the displacement piece, in which space the heating medium has been fitted to circulate from end to end in the roll. The inner face of the roll mantle is provided with a coating of an insulating material or equivalent, whose thickness is reduced in the direction of flow, or the inner face of the roll mantle has been made rough so that said roughness increases in the flow direction of the heating medium.
In the published DE Patent Application 40 02 530, a heatable roll is described in which axial bores have been arranged in two rows in the direction of the circumfer-ence so that in the bores placed closer to the outer face of the roll the heating medium is passed from end to end in the roll even three times back and forth, and the return flow takes place in the bores placed on the same, inner radial line.
In the published DE Patent Application 44 07 239, a heatable roll is described in which steam is used as the heating medium, which steam is passed along axial bores so that the heated steam is passed through the roll along outer bores, whereas the condensate water is returned along inner bores.
In the published DE Patent Application 43 17 875, an embodiment of circulation of a heating medium in a heatable roll is described. In this prior-art arrangement, flows passing in opposite directions along the circumference as well as flows arranged in the centre of the roll have been employed.
In the published DE Patent Application 195 38 236, a roll heatable by means of steam is described, in which steam which operates as the heating medium is fed through the roll along axial bores fitted along the circumference of the roll and through the roll centre, and the returned condensate arrives along a circumferential bore and through the centre back to the feed end.
In the published EP Patent Application 0,597,814, a heatable roll is described, in which a coating has been employed on the outer face of the roll mantle, in which the heating medium is circulated in the roll mantle, which coating consists of a ceramic compound or of a metal-ceramic mix whose thermal conductivity and elasticity are lower than said properties of the roll mantle.
In the FI Laid-Open Publication 98,940, a method and a device for calendering of paper are described, in which device there is a calender roll heated from inside for finishing of the paper by means of formation of heat in the body material, which roll is provided with a roll mantle of a thickness of at least 101,6 mm, which mantle is provided with a set of ducts so as to conduct heat in view of heating the material to be calendered. The roll mantle is provided with a thin coating consisting of a material that contains cermet or a ceramic.
In the prior-art thermo-roll solutions in which the ducts for the heating medium in the roll mantle are placed in one row close to the roll face, a little difference in tempera-ture is achieved between the outer face of the roll and the heating fluid as the effective heat transfer distance is relatively short. The gradient that is formed is, however, relatively large. The distribution of temperature that arises in the roll mantle is cyclic in compliance with the distribution of the ducts, and even on the roll face, minor cyclic variations in temperature occur. The variations in temperature cause a non-homogeneous thermal expansion and result in small cyclic variations in the diameter of the roll (gingerbread effect). This disturbance may cause, among other things, cyclic oscillation in a revolving nip. The present invention is directed towards solving problems related to uneven distribution of heat.
Besides the problem described above, in many applications known froin the prior art, heating and cooling of the roll are remarkably slow, for energy can be transferred to a narrow area of the set of tube rows only. When the heating capacity is applied to a narrow area in the roll, high differences in temperature and so also differences in strains arise. In such a case, spot-like temperature gradients may arise, and the metal can start yielding plastically. This is why the upper limit of the heating speed becomes a limiting factor. This situation is particularly problematic in on-line applications, in which the efficiency of the production line depends directly, for example, on the efficiency of a heatable roll used in the calendar. The present invention is directed towards a solution for this problem.
A roll in accordance with one aspect of the present invention is provided which comprises a roll mantle which is heated by means of a heating medium, into which roll mantle ducts extending from end to end in the roll mantle have been foilned substantially in the vicinity of the outer face of the roll mantle, through which ducts the heating medium has been made to circulate in order to heat the outer face of the roll mantle, wherein, in view of reducing the temperature gradient in the roll mantle, ducts have been arranged in at least two circumferential rows and wherein the ducts placed in the two rows fitted in the direction of the circumference have been fitted as interlocked with each other so that the ducts are placed on different radial lines.
In accordance with another aspect of the present invention, there is provided a heatable roll for a paper machine, paper finishing device, which roll comprises a roll mantle which is heated by means of a heating medium, into which roll mantle ducts extending from end to end in the roll mantle have been formed substantially in the vicinity of the outer face of the roll mantle, through which ducts the heating medium has been made to circulate in order to heat the outer face of the roll mantle, and in wllich roll heating medium has been fitted to be circulated through the centre of the roll, wherein, in view of reducing the temperature gradient in the roll mantle, the temperatures of the heating medium passed in the ducts in the roll mantle and in the centre of the roll are separately adjustable.
4a In accordance with the present invention, problems arising from uneven, even spot-like temperature gradients are eliminated so that the bores at the circumference are divided from one circumferential row of bores to at least two circumferential rows of bores placed with different radii, i.e. at different distances from the centre point of the roll, and the bores are fitted on different radial lines, i.e. interlocked with each other.
In this way an even distribution of the temperature is achieved, because the flux of heat is transferred evenly in the roll mantle. In accordance with the invention, instead of being heated by means of ducts of heating medium placed in the roll mantle, in a way in itself known the roll can also be heated from the centre of the roll, in which case the temperature in the roll mantle can be made more tmiform, and liigll temperature gradients can be eliminated. In this connection, the tenlperature of the heating medium flowing in the peripheral bores or in the central bore, respectively, is regulated in order to achieve uniform transfer of the flux of heat. In cormection with heating from the centre, if necessary, it is possible to employ a displacement piece, by whose means attempts are made to control the heating to the vicinity of the edge of the duct and to reduce the required amount of heating medium.
Further, in connection with the arrangement in accordance with the invention, it is 5 possible to use displacement pieces, by whose means equalization of the temperature in the longitudinal direction of the roll is achieved. Further, in order to equalize the temperature in the longitudinal direction of the roll, it is possible to use flows of heating medium passing in different directions in the ducts, in which connection it is possible to use several different combinations, which are primarily known in them-selves. For example so that, when the channels are placed in two rows with different radii, the heating medium is passed from one end of the roll to the other end of the roll along two, preferably smaller ducts placed in the upper row and returned along one duct placed in the lower row. Moreover, for example, it is possible to vary the directions in adjacent ducts and to use other arrangements that may occur to a person skilled in the art. The flow in each duct is controlled preferably by means of a valve of its own. In each duct, the flow speed and the temperature of the heating medium are controlled. A central bore can be used as a duct for heating medium, both as a return duct and as a supply duct, either with a displacement piece or without.
By means of the present invention, the distribution of temperature in a heatable roll can be made more uniform, and, moreover, by means of the present invention, transient heating/cooling stages can be made quicker. In the roll mantle, heating medium ducts are constructed in two or more circumferential rows, and the ducts are placed as interlocked with each other while the different rows are on different radial lines, and the temperatures of the heating medium flowing in the ducts are arranged appropriately, and in this way the distribution of the temperature in the surface layers of the roll mantle can be made uniform. When the number of ducts is higher, the diameter of the ducts can be made smaller accordingly.
In a stage of heating/cooling of a roll, when thermal energy is transferred through a number of different areas, the available capacity can be distributed over a larger area of effect. It is possible to heat the roll by means of a greater number of rows of heating ducts and possibly also additionally by means of induction from the surface.
In this way the capacity is distributed over a larger area, and no limiting large temperature gradients can arise. In accordance with the invention, a uniform distribu-tion of temperature is achieved over the face of the roll, and, moreover, distribution of the set of heating ducts (heating capacity) over a larger area permits quicker heating of the roll without limitations imposed by thermal strains. In this way the idle time of calenders in connection with maintenance etc. standstills is reduced.
In accordance with an embodiment of the invention, it is also possible to use a bore in a central duct and peripheral bores in the mantle together in a rational way in different situations of operation. In a normal running situation, into the central bore, slightly hotter oil is passed, as compared with a peripheral bore, in which connection the distribution of temperature arising in the roll mantle is more uniform than when exclusively peripheral ducts are employed. In this connection, the cyclic variation arising on the surface is also reduced. Also in a stage of heating and cooling the roll, capacity is transferred both through the central duct and through the peripheral ducts.
When the overall capacity is scattered, the temperature gradients that arise in the transient stage are lower with the same overall capacity. In other words, this permits the use of a higher overall capacity without an increase of the temperature gradients to a higher level. This means shorter transient stages in heating and cooling.
The invention is particularly well suited for use in connection with rolls heated by means of oil.
In the following, the invention will be described in more detail with reference to the figures in the accompanying drawing, the invention being, however, not supposed to be strictly confined to the details in said drawing.
Figure 1 is a schematic illustration of the curves of equal temperature in a roll mantle with a prior-art solution.
In the FI Patent 91,297, a heatable roll is described, which is provided with means by which the heat transfer coefficient from the flowing heating medium that acts upon the material of the roll mantle or of the roll to the roll material increases in the direction of flow of the heating medium. In said publication, a roll is also described which comprises a hollow roll mantle, into whose interior a displacement piece has been fitted so that an annular intermediate space remains between the roll mantle and the displacement piece, in which space the heating medium has been fitted to circulate from end to end in the roll. The inner face of the roll mantle is provided with a coating of an insulating material or equivalent, whose thickness is reduced in the direction of flow, or the inner face of the roll mantle has been made rough so that said roughness increases in the flow direction of the heating medium.
In the published DE Patent Application 40 02 530, a heatable roll is described in which axial bores have been arranged in two rows in the direction of the circumfer-ence so that in the bores placed closer to the outer face of the roll the heating medium is passed from end to end in the roll even three times back and forth, and the return flow takes place in the bores placed on the same, inner radial line.
In the published DE Patent Application 44 07 239, a heatable roll is described in which steam is used as the heating medium, which steam is passed along axial bores so that the heated steam is passed through the roll along outer bores, whereas the condensate water is returned along inner bores.
In the published DE Patent Application 43 17 875, an embodiment of circulation of a heating medium in a heatable roll is described. In this prior-art arrangement, flows passing in opposite directions along the circumference as well as flows arranged in the centre of the roll have been employed.
In the published DE Patent Application 195 38 236, a roll heatable by means of steam is described, in which steam which operates as the heating medium is fed through the roll along axial bores fitted along the circumference of the roll and through the roll centre, and the returned condensate arrives along a circumferential bore and through the centre back to the feed end.
In the published EP Patent Application 0,597,814, a heatable roll is described, in which a coating has been employed on the outer face of the roll mantle, in which the heating medium is circulated in the roll mantle, which coating consists of a ceramic compound or of a metal-ceramic mix whose thermal conductivity and elasticity are lower than said properties of the roll mantle.
In the FI Laid-Open Publication 98,940, a method and a device for calendering of paper are described, in which device there is a calender roll heated from inside for finishing of the paper by means of formation of heat in the body material, which roll is provided with a roll mantle of a thickness of at least 101,6 mm, which mantle is provided with a set of ducts so as to conduct heat in view of heating the material to be calendered. The roll mantle is provided with a thin coating consisting of a material that contains cermet or a ceramic.
In the prior-art thermo-roll solutions in which the ducts for the heating medium in the roll mantle are placed in one row close to the roll face, a little difference in tempera-ture is achieved between the outer face of the roll and the heating fluid as the effective heat transfer distance is relatively short. The gradient that is formed is, however, relatively large. The distribution of temperature that arises in the roll mantle is cyclic in compliance with the distribution of the ducts, and even on the roll face, minor cyclic variations in temperature occur. The variations in temperature cause a non-homogeneous thermal expansion and result in small cyclic variations in the diameter of the roll (gingerbread effect). This disturbance may cause, among other things, cyclic oscillation in a revolving nip. The present invention is directed towards solving problems related to uneven distribution of heat.
Besides the problem described above, in many applications known froin the prior art, heating and cooling of the roll are remarkably slow, for energy can be transferred to a narrow area of the set of tube rows only. When the heating capacity is applied to a narrow area in the roll, high differences in temperature and so also differences in strains arise. In such a case, spot-like temperature gradients may arise, and the metal can start yielding plastically. This is why the upper limit of the heating speed becomes a limiting factor. This situation is particularly problematic in on-line applications, in which the efficiency of the production line depends directly, for example, on the efficiency of a heatable roll used in the calendar. The present invention is directed towards a solution for this problem.
A roll in accordance with one aspect of the present invention is provided which comprises a roll mantle which is heated by means of a heating medium, into which roll mantle ducts extending from end to end in the roll mantle have been foilned substantially in the vicinity of the outer face of the roll mantle, through which ducts the heating medium has been made to circulate in order to heat the outer face of the roll mantle, wherein, in view of reducing the temperature gradient in the roll mantle, ducts have been arranged in at least two circumferential rows and wherein the ducts placed in the two rows fitted in the direction of the circumference have been fitted as interlocked with each other so that the ducts are placed on different radial lines.
In accordance with another aspect of the present invention, there is provided a heatable roll for a paper machine, paper finishing device, which roll comprises a roll mantle which is heated by means of a heating medium, into which roll mantle ducts extending from end to end in the roll mantle have been formed substantially in the vicinity of the outer face of the roll mantle, through which ducts the heating medium has been made to circulate in order to heat the outer face of the roll mantle, and in wllich roll heating medium has been fitted to be circulated through the centre of the roll, wherein, in view of reducing the temperature gradient in the roll mantle, the temperatures of the heating medium passed in the ducts in the roll mantle and in the centre of the roll are separately adjustable.
4a In accordance with the present invention, problems arising from uneven, even spot-like temperature gradients are eliminated so that the bores at the circumference are divided from one circumferential row of bores to at least two circumferential rows of bores placed with different radii, i.e. at different distances from the centre point of the roll, and the bores are fitted on different radial lines, i.e. interlocked with each other.
In this way an even distribution of the temperature is achieved, because the flux of heat is transferred evenly in the roll mantle. In accordance with the invention, instead of being heated by means of ducts of heating medium placed in the roll mantle, in a way in itself known the roll can also be heated from the centre of the roll, in which case the temperature in the roll mantle can be made more tmiform, and liigll temperature gradients can be eliminated. In this connection, the tenlperature of the heating medium flowing in the peripheral bores or in the central bore, respectively, is regulated in order to achieve uniform transfer of the flux of heat. In cormection with heating from the centre, if necessary, it is possible to employ a displacement piece, by whose means attempts are made to control the heating to the vicinity of the edge of the duct and to reduce the required amount of heating medium.
Further, in connection with the arrangement in accordance with the invention, it is 5 possible to use displacement pieces, by whose means equalization of the temperature in the longitudinal direction of the roll is achieved. Further, in order to equalize the temperature in the longitudinal direction of the roll, it is possible to use flows of heating medium passing in different directions in the ducts, in which connection it is possible to use several different combinations, which are primarily known in them-selves. For example so that, when the channels are placed in two rows with different radii, the heating medium is passed from one end of the roll to the other end of the roll along two, preferably smaller ducts placed in the upper row and returned along one duct placed in the lower row. Moreover, for example, it is possible to vary the directions in adjacent ducts and to use other arrangements that may occur to a person skilled in the art. The flow in each duct is controlled preferably by means of a valve of its own. In each duct, the flow speed and the temperature of the heating medium are controlled. A central bore can be used as a duct for heating medium, both as a return duct and as a supply duct, either with a displacement piece or without.
By means of the present invention, the distribution of temperature in a heatable roll can be made more uniform, and, moreover, by means of the present invention, transient heating/cooling stages can be made quicker. In the roll mantle, heating medium ducts are constructed in two or more circumferential rows, and the ducts are placed as interlocked with each other while the different rows are on different radial lines, and the temperatures of the heating medium flowing in the ducts are arranged appropriately, and in this way the distribution of the temperature in the surface layers of the roll mantle can be made uniform. When the number of ducts is higher, the diameter of the ducts can be made smaller accordingly.
In a stage of heating/cooling of a roll, when thermal energy is transferred through a number of different areas, the available capacity can be distributed over a larger area of effect. It is possible to heat the roll by means of a greater number of rows of heating ducts and possibly also additionally by means of induction from the surface.
In this way the capacity is distributed over a larger area, and no limiting large temperature gradients can arise. In accordance with the invention, a uniform distribu-tion of temperature is achieved over the face of the roll, and, moreover, distribution of the set of heating ducts (heating capacity) over a larger area permits quicker heating of the roll without limitations imposed by thermal strains. In this way the idle time of calenders in connection with maintenance etc. standstills is reduced.
In accordance with an embodiment of the invention, it is also possible to use a bore in a central duct and peripheral bores in the mantle together in a rational way in different situations of operation. In a normal running situation, into the central bore, slightly hotter oil is passed, as compared with a peripheral bore, in which connection the distribution of temperature arising in the roll mantle is more uniform than when exclusively peripheral ducts are employed. In this connection, the cyclic variation arising on the surface is also reduced. Also in a stage of heating and cooling the roll, capacity is transferred both through the central duct and through the peripheral ducts.
When the overall capacity is scattered, the temperature gradients that arise in the transient stage are lower with the same overall capacity. In other words, this permits the use of a higher overall capacity without an increase of the temperature gradients to a higher level. This means shorter transient stages in heating and cooling.
The invention is particularly well suited for use in connection with rolls heated by means of oil.
In the following, the invention will be described in more detail with reference to the figures in the accompanying drawing, the invention being, however, not supposed to be strictly confined to the details in said drawing.
Figure 1 is a schematic illustration of the curves of equal temperature in a roll mantle with a prior-art solution.
Figure 2 is a schematic illustration of the curves of equal temperature in a roll mantle with an arrangement in accordance with the invention in which the peripheral bores have been fitted in two separate circumferential rows interlocking each other.
Figure 3 is a schematic illustration of curves of equal temperature when peripheral bores and heating from the roll centre are employed.
Fig. 1 is a schematic illustration of a part of the mantle 11 of a heatable roll, in which, in compliance with the prior art, there is one row of heating medium ducts 12, which ducts are placed in a circumferential row near the face 14 of the mantle 11. In the figure, the flux of heat effective in the roll mantle has been illustrated when a heating medium is passed in the ducts. In the prior-art solution shown herein, an intensive temperature gradient is formed between the ducts 12 and the roll face 14 in an area 23, which situation results in cyclic variation 22 of temperature on the roll face 14. This can result in little deformations on the roll face and cause oscillation and/or deformations in the roll face.
Fig. 2 is a schematic illustration of a part of the mantle 31 of a heatable roll bearing an outer face 34, in which bores 32 and 33 have been fitted along the circumference.
The bores along the circumference are placed in two circumferential rows Rl and R2 and are fitted as interlocked with each other, i.e. radially on separate lines, as comes out from the figure. The figure is a schematic illustration of the flux of heat when a heating medium is passed in the bores along the circumference. Fig. 2 illustrates the uniform distribution of temperature 24 achieved in accordance with the present invention by means of the bores 32, 33 fitted along the circumference in two rows Rl, R2 placed at two different distances. The bores 32, 33 are placed on different radial lines as interlocked with each other, whereby a uniform distribution of temperature 24 is achieved.
Fig. 3 is a schematic illustration of a part of a roll mantle 41, in which there are bores 42 along the circumference and in which heating also takes place through the centre 45, and the arrows indicate the directions of transfer of heat. As is shown in the figure, when the centre 45 and the bores 42 along the circumference are heated, the distribution of heat and temperature is uniform and the temperature gradients are low. If necessary, in connection with heating from the centre, it is possible to employ a prior-art displacement piece (not shown in the figure).
In accordance with the invention, in the exemplifying embodiments shown in Figs.
2 and 3, in the different ducts (bores), the temperature of the heating medium can be varied, and in this way the distribution of heat can be equalized and the temperature gradients be reduced further. In different ducts, the flows can be carried into effect in the desired way in different directions and, when bores fitted in several rows along the circumference are employed, the bores can be fitted as interlocked with each other in many different ways, and ducts of different magnitudes can be used in order to accomplish the distribution of heat as uniformly as possible.
Above, the invention has been described with reference to some preferred exemplify-ing embodiments of same only, the invention being, however, not supposed to be strictly confined to the details of said embodiments. Many variations and modifica-tions are possible within the scope of the inventive idea defined in the following patent claims.
Figure 3 is a schematic illustration of curves of equal temperature when peripheral bores and heating from the roll centre are employed.
Fig. 1 is a schematic illustration of a part of the mantle 11 of a heatable roll, in which, in compliance with the prior art, there is one row of heating medium ducts 12, which ducts are placed in a circumferential row near the face 14 of the mantle 11. In the figure, the flux of heat effective in the roll mantle has been illustrated when a heating medium is passed in the ducts. In the prior-art solution shown herein, an intensive temperature gradient is formed between the ducts 12 and the roll face 14 in an area 23, which situation results in cyclic variation 22 of temperature on the roll face 14. This can result in little deformations on the roll face and cause oscillation and/or deformations in the roll face.
Fig. 2 is a schematic illustration of a part of the mantle 31 of a heatable roll bearing an outer face 34, in which bores 32 and 33 have been fitted along the circumference.
The bores along the circumference are placed in two circumferential rows Rl and R2 and are fitted as interlocked with each other, i.e. radially on separate lines, as comes out from the figure. The figure is a schematic illustration of the flux of heat when a heating medium is passed in the bores along the circumference. Fig. 2 illustrates the uniform distribution of temperature 24 achieved in accordance with the present invention by means of the bores 32, 33 fitted along the circumference in two rows Rl, R2 placed at two different distances. The bores 32, 33 are placed on different radial lines as interlocked with each other, whereby a uniform distribution of temperature 24 is achieved.
Fig. 3 is a schematic illustration of a part of a roll mantle 41, in which there are bores 42 along the circumference and in which heating also takes place through the centre 45, and the arrows indicate the directions of transfer of heat. As is shown in the figure, when the centre 45 and the bores 42 along the circumference are heated, the distribution of heat and temperature is uniform and the temperature gradients are low. If necessary, in connection with heating from the centre, it is possible to employ a prior-art displacement piece (not shown in the figure).
In accordance with the invention, in the exemplifying embodiments shown in Figs.
2 and 3, in the different ducts (bores), the temperature of the heating medium can be varied, and in this way the distribution of heat can be equalized and the temperature gradients be reduced further. In different ducts, the flows can be carried into effect in the desired way in different directions and, when bores fitted in several rows along the circumference are employed, the bores can be fitted as interlocked with each other in many different ways, and ducts of different magnitudes can be used in order to accomplish the distribution of heat as uniformly as possible.
Above, the invention has been described with reference to some preferred exemplify-ing embodiments of same only, the invention being, however, not supposed to be strictly confined to the details of said embodiments. Many variations and modifica-tions are possible within the scope of the inventive idea defined in the following patent claims.
Claims (11)
1. A heatable roll for a paper machine, paper finishing device, which roll comprises a roll mantle which is heated by means of a heating medium, into which roll mantle ducts extending from end to end in the roll mantle have been formed substantially in the vicinity of the outer face of the roll mantle, through which ducts the heating medium has been made to circulate in order to heat the outer face of the roll mantle, wherein, in view of reducing the temperature gradient in the roll mantle, ducts have been arranged in at least two circumferential rows and wherein the ducts placed in the two rows fitted in the direction of the circumference have been fitted as interlocked with each other so that the ducts are placed on different radial lines.
2. A heatable roll as claimed in claim 1, wherein the duct has been formed into the centre of the roll for circulation of a heating medium.
3. A heatable roll as claimed in claim 1 or 2, wherein, in view of reducing the temperature gradient in the roll mantle, the temperatures of the heating medium passed in the ducts in the roll mantle and in the roll centre are separately adjustable.
4. A heatable roll for a paper machine, paper finishing device, which roll comprises a roll mantle which is heated by means of a heating medium, into which roll mantle ducts extending from end to end in the roll mantle have been formed substantially in the vicinity of the outer face of the roll mantle, through which ducts the heating medium has been made to circulate in order to heat the outer face of the roll mantle, and in which roll heating medium has been fitted to be circulated through the centre of the roll, wherein, in view of reducing the temperature gradient in the roll mantle, the temperatures of the heating medium passed in the ducts in the roll mantle and in the centre of the roll are separately adjustable.
5. A heatable roll as claimed in claim 4, wherein, in view of reducing the temperature gradient in the roll mantle, ducts have been arranged in at least two circumferential rows, and wherein the ducts fitted circumferentially in at least two rows have been fitted as interlocked with each other so that the ducts are placed on separate radial lines.
6. A heatable roll as claimed in any one of claims 1 to 5, wherein the ducts placed in different rows in the roll mantle have diameters of different sizes.
7. A roll as claimed in any one of claims 1 to 6, wherein at least two heating media of different temperatures have been fitted to be circulated in the ducts in the roll mantle.
8. A roll as claimed in any one of claims 1 to 7, wherein, in connection with the roll, there is a valve system for control of the circulation and the temperature of the heating medium.
9. A roll as claimed in any one of claims 1 to 8, wherein a displacement piece has been fitted in at least one of a duct in the roll mantle and a roll centre in order to regulate the flow of the heating medium.
10. A roll as claimed in any one of claims 1 to 9, wherein, in adjacent ducts in a first row of the two rolls in the roll mantle, the heating medium has been fitted to be passed in the same direction, and the heating medium has been fitted to be returned along an interlocked duct placed in a second row of the two rolls.
11. A roll as claimed in any one of claims 1 to 10, wherein, the heating medium has been fitted to flow in different directions in adjacent ducts.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI982602 | 1998-12-02 | ||
| FI982602A FI105115B (en) | 1998-12-02 | 1998-12-02 | Heated roller |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2291213A1 CA2291213A1 (en) | 2000-06-02 |
| CA2291213C true CA2291213C (en) | 2007-11-27 |
Family
ID=8553021
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2291213 Expired - Fee Related CA2291213C (en) | 1998-12-02 | 1999-11-29 | Heatable roll |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA2291213C (en) |
| DE (1) | DE19957795B4 (en) |
| FI (1) | FI105115B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI118697B (en) * | 2006-12-13 | 2008-02-15 | Metso Paper Inc | Thermo roll for paper machine, has annular groove arranged on end surfaces of end pieces and shell for receiving composite-structured elastic metal seal to prevent leaking of heat-transfer medium from flow channels |
| DE102010044943A1 (en) * | 2010-09-10 | 2012-03-15 | Leonhard Breitenbach Gmbh | Calender roller has flow passage between inlet and outlet plenum that is comprised with additional axial parallel bore formed between peripheral bores and central bore of roller portion |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE9000980U1 (en) * | 1990-01-29 | 1990-05-10 | Schwäbische Hüttenwerke GmbH, 73433 Aalen | Roller for a smoothing unit or a calender |
| DE4002530A1 (en) * | 1990-01-29 | 1991-08-01 | Schwaebische Huettenwerke Gmbh | ROLLER FOR A SMOOTHING OR CALENDAR |
| FI89087C (en) * | 1990-08-08 | 1993-08-10 | Valmet Paper Machinery Inc | UPPHETTBAR VALS |
| US5171404A (en) * | 1990-11-30 | 1992-12-15 | S. D. Warren Company | Method and apparatus for calendering paper with internally heated roll |
| FI91297C (en) * | 1992-02-24 | 1994-06-10 | Valmet Paper Machinery Inc | Heatable roller |
| CA2108624A1 (en) * | 1992-10-20 | 1994-04-21 | Juhani Niskanen | Method for heating a roll and a heatable roll, in particular a press roll for a paper machine |
| DE4317875A1 (en) * | 1993-05-28 | 1993-10-14 | Voith Gmbh J M | Hollow roller used in paper-making machines - has axial drillings as a channel system for heat carrier medium feed and exhaust |
| DE4407239A1 (en) * | 1994-03-04 | 1995-09-07 | Schwaebische Huettenwerke Gmbh | Steam heated roller |
| DE19538236A1 (en) * | 1995-10-13 | 1997-04-17 | Schwaebische Huettenwerke Gmbh | Heating roller |
-
1998
- 1998-12-02 FI FI982602A patent/FI105115B/en not_active IP Right Cessation
-
1999
- 1999-11-29 CA CA 2291213 patent/CA2291213C/en not_active Expired - Fee Related
- 1999-12-01 DE DE1999157795 patent/DE19957795B4/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2291213A1 (en) | 2000-06-02 |
| DE19957795A1 (en) | 2000-06-08 |
| FI982602A0 (en) | 1998-12-02 |
| FI105115B (en) | 2000-06-15 |
| DE19957795B4 (en) | 2007-08-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |