HEATING ROLLER

Abstract: Heating rollers for use in calender mills and similar installations. The fluid heating the roller passes through a space (3) of annular cross-section defined between an inner jacket (4) and an outer jacket (5). In order to make the outer jacket easily replaceable, both jackets are held in position by a pressure ring (8). According to the invention the pressure ring has flanges (8a, 8b) extending axially inwards and co-operating with the jackets via frusto-conical contact surfaces in such a way, that increased temperature in space (3) results in an increase of the contact pressure between the frusto-conical surfaces.

Description: Heating roller The present invention relates to a roller for use in calender mills and similar installations. It does substantially consist of a tubular inner jacket and a tubular outer jacket. The two jackets are coaxial and define between themselves an annular cross-section space for- a -heat-delivering fluid. At each of the two ends of the roller there is a pressure ring which, upon tightening of a number of screws spaced in the circum¬ ferential direction of the roller and traversing holes in the rings, is displaced axially inwards whereby the jackets are retained in their positions. In rollers of the type above specified there is a problem to achieve sealing between the pressure ring and the jackets, especially the outer jacket. This is due to the fact that, when the hot fluid enters the space between the jackets, there occurs a thermal expan¬ sion tending to increase the distance between them so that leakage may occur. The prior art solution of the corresponding sealing problem is to interconnect the jackets and the pressure rings by welding. However, that solution has several disadvantages the two most signifi¬ cant of which being the following ones. First, it should be mentioned that the external surface of the outer jacket is highly exposed to the risk of being damaged by e.g. metal parts which are carried into the mill by the material to be calendered or otherwise treated there¬ in. When this happens and the finely polished surface of the roller gets scratched it often becomes necessary to remove the outer jacket for repair. If it is secured by welded joints, the repair operation gets complicated. Second, the presence of welded joints means that the relative positions of the jackets get permanently fixed during the welding operation, making it impossible after- wards to carry out any adjustment of the centricity or of the circular form of the outer jacket. . The object of the invention is to eliminate the above disadvantages by providing a heating roller com- bining the possibility of quick replacement and adjust¬ ment of the outer' jacket with eliminated sealing problems- According to the main characteristic of the invention this has been achieved in the way that the pressure rings have flanges extending axially inwards and co-operating wxth the jackets via frusto-conical surfaces so that, upon heat expansion of the jackets, the contact pressure between the jackets and the flanges is increased due to wedge action. Two embodiments of the invention will now be described with reference to the drawing. Figure 1 is a part-sectional, lateral view of a roller according to the first embodiment. Figure 2 does, on a larger scale, illustrate the parts of the roller of Figure 1 of direct interest in connection with the present invention. Figure 3 corresponds to- Figure 2 but relates to the second embodiment. The roller illustrated in Figures 1 and 2 does at each of its ends have a stub shaft 1 comprising a hub portion la carrying a number of radial spokes 2. The spokes are tubular and communicate with a central bore lb in shaft 1. Through that bore the heat-delive¬ ring fluid, for example vapour, is introduced into the space 3 of annular cross-section defined between the inner jacket 4 and the outer jacket 5 of the roller. The fluid flows through space 3 and exits in the same way at the opposite end of the roller. Between the two ends of the roller the fluid passes along a heli¬ cal path defined by a helical guide vane 6 surrounding a layer 7 of heat-insulating material on the external surface of the inner jacket 4. The edge portion 4a of the inner jacket 4 is be¬ velled so that its outer surface forms a frustrated cone, Correspondingly, the edge portion 5a of the outer jacket 5 is bevelled so that its outer surface forms a frust- rated cone. These two part-conical surfaces are in con¬ tact with matching surfaces of an inner flange 8a and an outer flange 8b, respectively, extending axially in¬ wards from a pressure ring 8. Ring 8 has a number of axial holes, spaced in the circumferential direction of the ring and traversed by bolts 9 engaging threaded ho¬ les in a nut ring 10. Interposed between rings 8 and 10 is a packing, or sealing ring, 11 consisting of an elastic material such as rubber. The inner jacket 4 does, adjacent to its free end, carry a stop ring 12 the inner radial surface of which contacts a shoulder surface of a flange 10a of nut ring 10. As is under¬ stood, when bolts 9 are tightened, ring 10 is in this way blocked against displacement axially outwards meaning that pressure ring 8 will be forced axially in- wards. During such movement its conical surfaces slide along the conical surfaces of the tapered end portions of jackets 4 and 5. At the same time sealing ring 11 is compressed and the overall result is that space 3 will be sealed off. When a heat-delivering fluid such as vapour is passed through space 3, outer jacket 5 is first heated whereas the temperature rise of the inner jacket 4 is restricted .by the heat-insulating layer 7. This leads to heat-expansion of outer jacket 5 yielding radially outwards directed force components increasing the con¬ tact pressure between the conical contact surface of jacket end portion 5a and pressure ring flange 8b. It is realized that the higher the temperature of the outer jacket the more will that contact pressure, i.e. the sealing effect, increase. As has been illustrated on the drawing, the outer diameter of pressure ring 8 is slightly less than that of the outer jacket 5. This means that the pressure ring 8 can never get into contact with the other roller in a pair of co-operating rollers in the mill. In the embodiment illustrated in Figure 3 de¬ tails having direct or functional counterparts in Figure 2 have been given the same reference numerals as in Figure 2. The only difference between the two embodiments is that, in Figure 3, the inner flange 8a of pressure ring 8 does not have a conical but a cylind¬ rical outer surface, and portion 4a of inner jacket 4 naturally exhibiting a matching configuration. The two embodiments illustrated and above de¬ scribed are intended only to illustrate the principle of the solution of the sealing problem in heating rol¬ lers covered by the present invention. Accordingly, the inventive concept resides in the realization that the pressure rings and the end portions of one or both of the jackets can be shaped in such a way that, thanks to wedge action, thermal expansion results in an increase of the contact pressure at the sealing surfaces whereby the leakage risk is eliminated. It follows therefrom, that it also is within the scope of the invention to use such a layout of the roller that the contact between the pressure ring and the jackets is not direct but occurs via some intermediate members. ' _ H

Claims: Claims . 1. A heating roller for use in calender mills and the like, comprising an inner jacket (4) and a coaxial outer jacket (5) , said jackets defining between them¬ selves a space (3) of annular cross-section for re- ceiving a heat-delivering fluid, the roller having at each of its ends a pressure ring (-8) which, upon ■ tightening of bolts (9) spaced in the circumferential direction of the ring and passing through holes there¬ in, is displaced axially inwards for the purpose of retaining the jackets, characterized in that the rings (8) have flanges (8a, 8b) extending axially inwards and retaining the jackets (4, 5) between them¬ selves, at least the flange (8b) adjacent to outer jacket (5) being arranged to contact the outer jacket via conical surfaces so that heating of the outer jacket (5) results in increased contact pressure be¬ tween said conical surfaces due to wedge action. 2. A roller as claimed in claim 1, characterized in that both flanges (8a, 8b) of each pressure ring (8) is in direct contact with jackets (4, 5) via frusto-conical contact surfaces. 3. A roller as claimed in claim 1 or 2, charac¬ terized in that bolts (9) do, in a manner know per se, engage threaded holes in a nut ring (10) located between jackets (4, 5) and secured against displace¬ ment axially outwards, a sealing- ring (11) being in¬ terposed between pressure ring (8) and nut ring (10) .

Inventors: JARREBY BERTIL
Applicants: JARREBY BERTIL, SKANDINAVISKA APPARATIND
Application year: 1982
Main classification: D21G1
IPC codes: D21F5, D21G1, F16C13