Roll or roller – With antideflection means – Rotatable relative to supporting shaft
Reexamination Certificate
2000-09-28
2002-06-25
Cuda-Rosenbaum, I (Department: 3726)
Roll or roller
With antideflection means
Rotatable relative to supporting shaft
C492S016000, C492S020000
Reexamination Certificate
active
06409644
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a sag (deflection) compensation roll with a rotatable roll jacket, a non-rotating carrier arranged inside the roll jacket, and a hydraulic support element arrangement between the carrier and the roll jacket. A bearing ring is located at each end of the roll jacket, which can be moved relative to the carrier in a press plane, and a beating arrangement is located between the bearing ring and the roll jacket.
The invention also relates to a process for operating a sag compensation roll with a roll jacket that rotates around a carrier and is supported in the area of each of its axial ends by a bearing arrangement that has a bearing ring and at least three hydrostatic support elements with bearing pockets distributed over the bearing ring in the circumferential direction.
2. Discussion of Background Information
Such a sag compensation roll is known from, e.g., EP 0 332 594 B1. In operation, the roll jacket rotates around the carrier. Sags that might result from a loading of the roll jacket are accepted by the hydraulic support element arrangement that supports the roll jacket from inside against the carrier. While this does lead to a sagging of the career under certain circumstances, the elastic line of the roll jacket can correspondingly be better influenced.
The support element arrangement, however, can only accept forces that act in the press plane, for example, that are produced by an opposing roll or an adjacent roll stack. It is also necessary for the roll jacket to be held on the carrier with a bearing that allows the roll jacket to rotate against the carrier and simultaneously allows a certain positioning.
This bearing or, more generally, this bearing arrangement, is loaded differently in different situations. In operation, the roll jacket is supported against the carrier by the hydrostatic support elements. Thus, the bearing arrangement can be held virtually free of support forces, at least with a vertically oriented roll stack, in which the support elements also produce a vertically oriented force component between the carrier and the roll jacket. The weight of the roll jacket itself and the forces acting in the press direction, which are applied by other rolls, are absorbed by the support elements between the roll jacket and the carrier. In this case, the bearing arrangement serves virtually exclusively to position the roll jacket against the carrier. When the nips of the roll stack are opened, the weight of the roll jacket rests on the bearing arrangement. In this case, the bearing arrangement must be capable of accepting this weight, even when the roll jacket rotates. In all cases, it must be ensured that the bearing arrangement runs with the smallest possible amount of play, which must not exceed a predetermined amount.
In the known case, this bearing is formed by a roll body, as is customary in the state of the art. It has been found, however, that such roll bearings no longer work with the necessary reliability when the rolls run ever faster.
SUMMARY OF THE INVENTION
The present invention provides a sag (deflection) compensation roll which is operable at a higher operating speed.
The sag compensation roll of the instant invention includes a bearing arrangement formed by at least three hydrostatic support elements which are distributed in the circumferential direction. At least one of the at least three hydrostatic support elements can move with respect to the bearing ring.
It is thus possible to operate a sag compensation roll with a jacket lift even at higher speeds, i.e., circumferential speeds on the order of magnitude of about 2000 m/min and above. The presence of at least three support elements distributed in the circumferential direction allows a defined supporting in all radial directions. Since at least one, but preferably several or even all, of the support elements can move against the bearing ring, they are capable of self-adjusting even when there are diameter changes of the roll jacket and/or the bearing ring or the carrier, which do not always need to run alike. Thus, they are able to guarantee that the roll jacket is always supported to the desired extent. Plays, as are known from roll bearings and that could lead under certain circumstances to an unfavorable oscillation behavior of the roll during operation, are kept very low with this type of bearing. In addition, the hydrostatic support of the roll jacket in the area of the rotation bearings enables relatively low-wear operation, even at higher speeds.
The fact that, in a preferred embodiment, the effective surface of the bearing pocket arrangement, i.e., the area in which the pressure can act between the roll jacket and the support element, is greater than the effective surface between the support element and the bearing ring, ensures that the support element can indeed be pressed into the bearing ring with a certain force when corresponding forces act on the roll jacket. Since hydraulic pressures build up above and below the support element, however, the force with which the support element lies against the bearing ring remains limited. Its magnitude can be influenced by the difference in area. This results in a stable support, even when the diameters of the roll jacket change. It is virtually always ensured that the roll jacket can slip on a film of fluid.
It is also preferred for the support element to be able to be driven into the bearing ring under load up to its fixed position. No relative movement that could lead to friction occurs between the foot surface of the support element and the bearing ring, so that it can certainly be accepted here that the support element can be driven into the bearing ring “up to the stop.” During operation, the roll jacket is supported in the known manner, e.g., by the support elements between the carrier and the roll jacket or else by further rolls arranged below the roll jacket, which rolls form a nip with the sag compensation roll in question. In this case, the bearing arrangement is virtually free of external support forces. It serves primarily to position the roll jacket against the carrier. Owing to the at least one movable support element between the bearing ring and the roll jacket, it is possible to design the bearing arrangement with a decidedly small amount of play. The support elements can be held always in the immediate vicinity of the inside of the roll jacket, with the formation of a fluid film of the hydraulic fluid.
It is also advantageous if the bearing pocket arrangement is connected with a supply device that delivers a constant volume flow of hydraulic fluid. Owing to the supplying of the bearing pockets with a constant volume flow of the hydraulic fluid, changes in loading can also be received without difficulty, Even when the weight of the roll jacket must be carried by the bearing arrangement, a reliable support is possible without difficulty. The support element lying against the direction of the force of gravity is thus driven into the bearing ring up to the stop, i.e., into its fixed position. The supplying of the bearing pockets with a constant volume flow of the hydraulic fluid, however, still ensures that the fluid film is maintained between the support element and the roll jacket, largely independently of the loading. A constant pressure difference prevails between the cylinder chamber below the support element and the hydrostatic pocket between the support element and the roll jacket, owing to the constant volume flow of hydraulic fluid. By applying load to the roll, the support element facing the nip is supported on the floor of its cylinder bore. Since its capillary continues to be supplied with hydraulic fluid, however, and at a constant volume flow, the pressure will rise in the pockets. At every load, the pressures in the pockets adjust automatically. By the constant volume flow, it is possible to ensure that the support function is maintained for each support element, independently of the load.
The bearing pocket arrangement is preferably connect
Cuda-Rosenbaum I
Greenblum & Bernstein P.L.C.
Voith Sulzer Papiertechnik Patent GmbH
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