CA2290291C

CA2290291C - Heatable calender roll

Info

Publication number: CA2290291C
Application number: CA 2290291
Authority: CA
Inventors: Joachim Schonemann
Original assignee: Walzen Irle GmbH
Current assignee: Walzen Irle GmbH
Priority date: 1998-11-26
Filing date: 1999-11-24
Publication date: 2005-04-26
Anticipated expiration: 2019-11-24
Also published as: EP1006236B1; EP1006236A3; CA2290291A1; EP1006236A2; JP3443546B2; JP2000192392A

Abstract

A calender roll heatable with a heating medium and including a roll body having a central bore, flanged journals provided at opposite sides of the roll body for supporting the same, and a displacement body arranged in the central bore of the roll body and formed of a material having a specific weight smaller than a material of the roll body.

Description

BACKGROUND OF THE INVENTION
1. Field of the Invention.
The present invention relates to a calender roll heatable with a heating medium, in particular, to a calender roll for glazing, and including a hollow roll body provided with a displacement body and supported at its opposite ends by flanged journals.

2. Description of the Prior Art Calender rolls of the type discussed above are used for finishing or glazing of paper in a calender. An effective uniform heating of the roll body surface is achieved by providing in the roll body a plurality of peripheral bores through which a heating medium passes. Also, the inner surface of the roll body is heated, and by appropriate shaping of the displacement body, the clearance between the inner surface of the roll body and the displacement body has been so reduced that the obtained velocities of the heating medium permitted to insure a good heat transfer. The roll body, which is provided with the peripheral bores, is also provided with a central bore for purposes of reducing weight of the roll body. While the loss of the central, neutral phase reduces the weight, the load capacity is reduced only to a small degree. The hollow space of the roll body can be either filled or be prevented from being filled with the heating medium.
Usually, with this design of the calender roll, the displacement body in particular is formed of sheet steel within narrow tolerances, is inserted into the roll body, and is connected therewith. It means that with a rapid change of the speed of the calender roll and, in particular, at a sharp breaking of the calender roll, the elements connecting the displacement body with the roll body are subjected to high loads which can lead to their distraction and to a damage of the displacement body because of overload. Usually, when the metal sheet has a high specific weight, balancing of the calender roll is necessary. It is also critical to be able to sense the thermal deformation of the elements of the displacement body, which affect the roll body, in particular, at its end and in connection region.
Accordingly, an object of the present invention is to provide a displacement body insertable in the central bore of the roll body and devoid of drawbacks of conventional displacement bodies.
NYLIB I/635491/l SU1~ARY OF THE INVENTION
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a displacement body formed of a material having a specific weight smaller than the specific weight of a material the roll body is formed of. The formation of the displacement body of a plastic material or another light material, permits to connect the displacement body with the roll body by press fit or by other connection means, without a need the resilience of the plastic material, the displacement body is made of, matched the required fit accuracy which was necessary with the displacement bodies formed of sheet steel. Also, with the materials having a reduced specific weight, the balancing problems are reduced, and a damaging heat transfer, at the end and suspension regions, is eliminated due to a small thermal capacity of plastic materials. An easy workability of the plastic materials permits to provide a construction which insures good steam-condensate separation and an easy discharge of the heating medium. With supercalender and calender formed in accordance with the new concept, such as Janus*, Prosoft*
and Optiload*, with surface temperatures between 70 and about 135°, the displacement body can be formed of conventional plastic materials. Only with the rolls for soft calenders with surface temperatures up to 200°, the selection of particular heat-resistant plastic materials becomes necessary.
Thus, according to the present invention there is provided a calender roll heatable with a heating medium, comprising a roll body having a central bore; flanged * Trade-mark journals provided at opposite sides of the roll body for supporting same; and a displacement body arranged in the central bore of the roll body and formed of a material having a specific weight smaller than a material of the roll body.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
Fig. 1 shows a longitudinal cross-sectional view of a calender roll with bores formed in its periphery;
Fig. 2 shows a cross-sectional view along line 2-2 in Fig. 1;
Fig. 3 shows a longitudinal cross-sectional view of a calender roll the displacement body of which, formed of a plastic material, is formed as a plastic tube closed from both side with flanges and the wall of which is provided with grooves through which a heating medium can flow;
Fig. 4 shows a view of an involuate section of a jacket of a displacement body of a calender roll provided with grooves for a heating medium which, to simplify representation, are shown as extending parallel to the axis;
Fig. 5 shows a cross-sectional view of a calender roll formed as one-piece with a displacement body made of plastic material for a two-way connection head;
Fig. 6 shows a schematic view of a displacement body with a groove for the heating medium being formed as a double helix, with the two grooves passing into each other at their leftside ends and with their rightside ends being connected with a two-way connection head;

Fig. 7a shows a cross-sectional view of a first cut-out of a vertical section of the displacement body shown in Fig. 6;
Fig. 7b shows a cross-sectional view of a second cut-out of a vertical section of the displacement body shown in Fig. 6;
Fig. 8 shows a cross-sectional view of a calender roll somewhat similar to that of Fig. 5 and including a displacement body formed of a jacket and cover plates and through which a pipe extends;
Fig. 9-11 show a view similar to that of Fig. 4 with different flow pattern of the heating medium; and Fig. 12 shows a cross-sectional view of another embodiment of a calender roll according to the present invention with peripheral bores and with return conduit for the heating medium being formed by a clearance between the wall of the roll and the displacement body or by groove-forming channels.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A heatable calender roll according to the present invention, which is shown in Fig. 1, has a hollow cylindrical body 1 which is supported by flanged journals 2 provided on opposite sides of the cylindrical body 1. The hollow cylindrical body 1 of the inventive calender roll has a plurality of peripheral bores 3, through which a heating medium can flow, and a central bore 4 having a larger diameter. For feeding and return of the heating medium, at an end of one of the flanged journals 2, there is provided a two-part connection head 5.
Alternatively, a one-part connection head 5 can be provided at an end of each of the two flanged journals 2.
A displacement body 6 is provided in the central bore 4 of the calender roll body 1. The displacement body 6 is formed of a plastic material as a solid body. The displacement body 6 can be fixedly connected with the calender roll body 1 simply by being pressed into the central bore 4. Care should be taken not to form the displacement body 6 with the same outer diameter exceeding the g inner diameter along its entire length. Rather, only separate sections 7 of the displacement body 6 should be formed with an outer diameter exceeding the inner diameter of the calender roll body 1 which insures an adequate press fit.
The sections of the displacement body 6 located between the sections 7 have a reduced outer diameter. Alternatively, the displacement body 6 can, e.g., be formed of a plurality of separate sections which are pressed into the roll body 1 one after another.
The outer surface of the calender roll body 1 can be provided with a coating 8.
The return flow of the heating medium to the connection head 5 can be effected in a simple way through the central bore 9. Should it be necessary, the central bore 9 can be formed by expanding the pipe, if necessary, only partially.
It is also possible to provide one or several grooves 10, which can extend parallel to the calender roll axis, be formed as a helix and the like, for returning the heating flow to the connection head 5. The groove or grooves 10 can be drawn along the outer surface of the displacement body 6. With a corresponding layout of the grooves, they can be used for heating the inner NYLIB (/635497/1 surface of the calender roll body. By reducing their cross-section in the flow direction of the heating medium, the action of an increased cooling in the heating medium flow direction can be compensated. If necessary, in association with peripheral bores or only for the later, arbitrary flow patterns can be developed, e.g., two parallel conduit branches arranged in series with a further branch.
A further reduction in weight of a calender roll can be achieved when instead of a solid pressed-in block formed of a plastic material, a block, which is formed of a foamed plastic material, preferably with closed pores, is used as a displacement body.
The easy processability of the plastic material permits to economically form special features of a calender roll. Thus, in particular in steam-heated rolls, axial steam feeding bores or steam feeding bores extending parallel to the roll axis in the surface of the plastic displacement body, which is opposite to the calender roll body, can be so arranged in the same way as axial condensate discharging bores or condensate discharging bores extending parallel to the roll axis. For collecting the condensate, the displacement body 6 can be provided NYL.IBI/635497/1 1~

with corresponding, preferably deepened grooves, radial circularly extending grooves at the ends of the displacement body 6. Further, turned grooves in the end portions of the central bore 4 proved themselves. Also, the supply of the peripheral bores 3 with the heating medium can be effected, with the given pattern, by additional shaping of the displacement body or at least its end portion. Advantageously, the easy processability, just as the small specific weight of the plastic material, facilitate or makes unnecessary the balancing work. The displacement body and the built-in elements can be formed of a plurality of parts and be connected by press fitting, by being screwed with each other, by being glued and welded to each other, and so forth.
Fig. 3 shows a calender roll the hollow cylindrical body 11 of which is formed without peripheral bores. The calender roll body 11 is provided with a displacement body 12 which is formed as a hollow body in a form of plastic tube 13 which is closed at its opposite ends with plastic flanges 14. The inner surface of the roll body 11 and/or the vsrall of the displacement body 12 is (are) provided with grooves 15. The grooves 15 insure a direct contact of the heating medium with the inner surface of the roll body l, providing for the transmission of heat to the roll body 1. In principal, several grooves can be arranged parallel 30735-3 vv .:~ . .,~ w w y .. . . .
to each other as shown in the developed view shown in Fig. 4. However, generally, there is provided a plurality of helix-shaped grooves entwined with each other in a manner of a multiple thread. Already here, there exists a possibility, during flow of the heating medium, to accelerate the velocity of the heating medium, which is cooled as a result of a heat exchange with the roll body, by tapering the grooves, reducing their diameter. The increased velocity of the cooled heating medium compensates the reduced temperature of the heating medium, by changing the heat transfer coefficient in a way which maintains the heat transfer substantially unchanged. .
Fig. 5 shows another embodiment of a heatable calender roll 16. The calender roll 16 is provided with a solid plastic displacement body 17 vrhich is preferably formed of a foamed plastic material with closed pores. Here, likewise, the grooves 15, which forms the channels for the heating medium, are preferably formed as a helices. The heating medium that flows through the grooves 15 accumulates in the chamber 18 and is discharged through a central bore 9 of the displacement body 27 . Ai the end of the central bore 9, there is provided a pipe socket 19 which, on the other hand, can extend along an entire length of the bore 9.

However, a special bore, which serves for return of the heating medium, can be dispensed with when the displacement body 17 has a shape shown in Fig. 6 and has grooves 20, 21 which are formed in a manner of a double thread and end, at the left end of the displacement body 17, either in a cage ring or are connected with each other in any other manner. Thereby, e.g., the groove 20 forms a first channel through which the heating medium flows along a helical line to the opposite end of the displacement body and heats the calender roll body, and returns from this end through the channel formed by the groove 21.
Because the delivery and discharge channels extend adjacent to each other, a certain equalizing of the delivery and discharge temperature takes place. This equalization further increases when, as shown in Figs. 7a and 7b, the groove cross-sections in the flow direction are so reduced that the resulting different velocities produce the necessary changes in the heat transfer coefficient.
Fig. 8 shows yet another embodiment of a calender roll according to the present invention the system of channels for heat medium corresponds to that of Fig. 5 but the displacement body of which is similar to that shown in Fig. 3.
The displacement body is made hollow in order to reduce weight. In this embodiment, when it is desired that the return of the heating medium be effected through the chamber 18, it is necessary form the pipe socket as a pipe 22 which should extend through the entire displacement body, including the flanges. Further patterns of heat medium channels are shown in Figs. 9-11. In Fig. 9, the channel-forming grooves extend parallel to each other as channel in the tube 13 as it was discussed with reference to Fig. 4. In the embodiment shown in Fig. 9, the displacement body, which is similar to the displacement body 17 of Fig. 5, has two parallel grooves 23, 24 for delivery of the heating medium, with the discharge or return channel being formed by a single groove 25. The three grooves 23, 24, 25 form a set which is repeated along the circumference of the displacement body. Helical grooves can likewise be used.
In this embodiment, it can be conveniently provided for the flow of the heating medium through the delivery grooves 24 and 25 with a velocity reduced in comparison with the velocity of the heating mechanism through the return groove 25. Further changes in the flow pattern will now be discussed with reference to Fig. 10.
In the embodiment of Fig. 10, the delivery and return grooves are formed with different cross-sections. During manufacturing, the different cross-sections of the grooves can be achieved with different milling depths or by using mill cutters having different widths.
In Fig. 10, the return groove 35 has a larger width than the delivery grooves 33,34. In the pattern of Fig. 1 l, there are provided three grooves 26, 27 through which the heating medium consecutively flows and which provide a double helix channel in which the different flow velocity are again obtained by forming the grooves with different widths and/or depths.
Finally, a yet another embodiment of a heatable calender roll will be discussed with reference to Fig. 12. The calender roll body 1 corresponds to that shown in Figs. 1-2 and, as in the embodiment of Figs. 1-2, it is provided with peripheral bores 3. However, in the embodiment of Fig. 12, additional heating is contemplated. The heating medium is supplied to the peripheral bores through ascending bores 28 and is discharged from the peripheral bores 3 through discharge bores 29 and into a chamber 30. Then, the return heating medium flows through channel-forming grooves 31 formed in the displacement body 6. The channels, which are formed by grooves 31, are closed from outside by the inner surface of the calender roll body 1. The heating of the calender roll 1 is effected in accordance with the patterns discussed with reference to Figs. 4, 6 or 9 through 11.
Though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A calender roll heatable with a heating medium, comprising a roll body having a central bore; flanged journals provided at opposite sides of the roll body for supporting same; and a displacement body arranged in the central bore of the roll body and formed of a material having a specific weight smaller than a material of the roll body.

2. A calender roll as set forth in claim 1, wherein the displacement body is formed of a material having a specific weight smaller than a specific weight of the heating medium.

3. A calender roll as set forth in claim 1, wherein the displacement body is formed of a plastic material.

4. A calender roll as set forth in claim 3, wherein the calender roll is formed of a solid plastic material.

5. A calender roll as set forth in claim 1, wherein the displacement body is formed of a foamed plastic material.

6. A calender roll as set forth in claim 1, wherein the displacement body is formed of a foamed plastic material with closed pores.

7. A calender roll as set forth in claim 1, wherein the displacement body has at least one central bore.

8. A calender roll as set forth in claim 1, wherein the displacement body has at least one groove extending along a circumference of the displacement body.

9. A calender roll as set forth in claim 8, wherein the at least one groove is formed as a helically extending groove.

10. A calender roll as set forth in claim 8, wherein the at least one groove extend, along a surface line of the displacement body.

11. A calender roll as set forth in claim 8, wherein the at least one groove extends at an angle to a surface line of the displacement body.

12. A calender roll as set forth in claim 1, wherein the displacement body is secured in the central bore of the roll body with a press fit.

13. A calender roll as set forth in claim 12, wherein the displacement body has a plurality of longitudinal sections having an outer diameter, which is so adapted to a diameter of the central bore that the press fit is insured, and which are separated from each other by longitudinal sections having a smaller diameter.

14. A calender roll as set forth in claim 1, wherein the displacement body is divided in a longitudinal direction into separate sections.

15. A calender roll as set forth in claim 14, wherein the separate sections are formed as hollow bodies.

16. A calender roll as set forth in claim 1, wherein the displacement body is formed as a hollow body.

17. A calender roll as set forth in claim 1, wherein the displacement body is formed of a plurality of separate parts having recesses for performing different functions.