Method for the operation of a roller

For a roller mounted on roller bearings in a roller stand, a hydrostatic support element is provided directly next to the roller bearing. The support element applies an additional force sufficient to assure proper rolling movement of the roller bearing bodies of the roller bearing when there is insufficient weight on the roller bearing to assure proper rolling movement. Alternatively, when great force is applied to the roller, the support element can alleviate the force applied to the roller bearing.

DETAILED DESCRIPTION OF THE DRAWINGS The calander 100 in FIG. 1 includes a vertical stack of rollers 10 , 11 , 12 . Top roller 10 is a weighting roller of conventional design, mounted in a fixed manner in a roller stand, not shown, which therefore includes a cylindrical roller body 1 with coaxial roller journals 2 attached at the ends. The bottom roller of calander 100 , not shown, is a deflection-controlled roller, which carries the entire roller stack and presses it up against weighting roller 10 . As shown in FIG. 3 , roller 10 is mounted in roller stand 3 , with its journals 2 , via a roller bearing 4 . Roller bearing 4 is arranged with its inner ring 4 ′ on a conical segment 2 ′ of roller journal 2 . The diameter of conical segment 2 ′ increases towards the interior of the roller. On the outside of roller bearing 4 , a support ring 5 , with a cylindrical outside circumference surface 6 , can be axially moved on roller journal 2 . Support ring 5 can be pressed against inside ring 4 ′ of roller bearing 4 by a ring nut 7 . Ring nut 7 is screwed onto a thread 2 ″ of roller journal 2 , so that inside ring 4 ′ is pushed up onto conical segment 2 ′. This causes roller bearing 4 to be fastened in the axial direction, and allows adjustment of the radial play. Support ring 5 is arranged axially directly next to roller bearing 4 , outside of the latter in the exemplary embodiment. However, a corresponding axial ring could be provided within roller bearing 4 , or support rings could be provided on both sides of it. In the exemplary embodiment of FIGS. 1 to 3 , four hydrostatic support elements 20 are provided. They lie diametrically opposite one another, in pairs, with reference to axis A, and are arranged symmetrical to the plane of effect W. The two support elements 20 provided above axis A and the two provided below axis A stand at an angle 8 of 60° relative to one another. Each support element acts against cylindrical outside circumference surface 6 of support ring 5 . The resulting total force K of the two top support elements 20 , 20 is directed downward, in accordance with FIG. 1 , in the direction of roll nip 9 between rollers 10 and 11 . The resulting force K′ of the two bottom support elements 20 , is directed upward, away from roll nip 9 . In FIG. 1 , the support elements are only indicated schematically. Their structure is evident in detail in FIGS. 2 and 3 . A ring housing 42 surrounding roller journal 2 engages into opening 41 of roller stand 3 , with a collar 13 , so that centering of ring housing 42 relative to roller stand 3 occurs. At the locations of support elements 20 , ring housing 42 has projections 14 that project radially inward. Each projection forms a support surface 15 perpendicular to a radial ray passing through axis A. The radially outward surface of each support element 20 rests against support surface 15 . Each support element 20 includes a cylinder part 16 which rests with its bottom against support surface 15 . Cylinder part 16 is attached to projection 14 by a hollow-drilled screw 18 . Hollow drilled screw 18 together with bore 17 forms a fluid feed line. Piston part 21 of a slide shoe 22 engages into cylinder chamber 19 of cylinder part 16 . Shoe 22 is shaped in accordance with cylinder surface 6 , on the outside facing the cylinder surface, and there forms a bearing pocket 23 . Bearing pocket 23 has an edge 24 which rests on cylinder surface 6 all around. Support surface 6 rotates under slide shoe 22 , which is fixed in place. Pressurized fluid within bearing pocket 23 provides sufficient force to avoid any metal-on-metal friction in the region of bearing pocket 23 . A film of fluid that constantly flows out between edge 24 and cylinder surface 6 avoids any metal on metal contact in the region of edge 24 . Bearing pocket 23 is connected with cylinder chamber 19 via a connecting bore provided with a spring-loaded kick-back valve. When pressurized fluid is supplied via screw 18 , bearing pocket 23 fills with pressurized fluid when the pressure produced by the spring force of the kick-back valve is exceeded. The pressurized fluid produces a corresponding force K 20 which is exerted on cylinder surface 6 . The force K 20 is then transferred to roller journal 2 . Force K 20 can perform two functions. The first function is to artificially produce a weight, so to speak, if there is insufficient weight on roller bearing 4 . For example, an operational state is possible in which the bottom roller of calander 100 , not shown in FIG. 1 , exerts a lifting force on the roller stack so that a line force prevails in roll nip 9 that precisely corresponds to the weight of top roller 10 . In this operational state, there is no weight on roller bearing 4 and its roller bearing bodies would tend to be dragged along the rolling contact surface. Since calanders in the paper industry operate at high speeds, up to a range of 2000 m/min, such dragging would result in significant friction wear, both on the rolling contact surfaces and on the roller bearing bodies. Thus, such an operational state should be avoided, if at all possible. This can be done by exerting a force by means of support elements 20 . The exerted force produces sufficient contact of the roller bearing bodies in roller bearing 4 to produce rolling movement, instead of a dragging movement. The present invention can also be used to produce another support function in the more or less opposite case of weighting, namely if roller bearing 4 is not free of weight, but rather has to bear a particularly great force. This state can occur if the line force in roll nip 9 has to be increased beyond the inherent weight of top roller 10 , by pressing the roller stack against it from below. A great radial stress in combination with the high speeds already mentioned represents the maximum stress for a roller bearing. If a resulting total force K is produced by support elements 20 , which acts in the direction of roll nip 9 , the arrangement of support elements 20 can relieve part of the stress on roller bearing 4 . Therefore, roller bearing 4 can be sized smaller with regard to its maximum stress, or will have a longer lifetime. While roller 10 according to FIGS. 1 to 3 represents a conventional roller mounted in roller stand 3 in fixed manner, FIG. 4 indicates a deflection-controlled roller 30 . In deflection-controlled toller 30 , a hollow roller 31 rotates around a non-rotating cross-beam 32 which passes through it over its length. Cross-beam 32 is supported from the inside by a hydraulic support device 33 , which is only schematically indicated, and acts against the inside circumference of hollow roller 31 . Support elements 40 are provided for roller 30 and are located axially outside of roller bearings 34 . Support elements 40 are attached in fixed manner on cross-beam 32 , and act against the inside circumference of hollow roller 31 with their slide shoes. With regard to the arrangement in the circumferential direction and the structure, in detail, support elements 40 are similar to support elements 20 . The two functions of maintaining a minimum weight on roller bearing 34 and support under very great stress can also be performed by support elements 40 .