FI121350B - Method and arrangement for removing a zero bearing load - Google Patents

Description

The present invention relates to a method of removing a zero bearing of a rolling bearing, such as a roller, needle or ball bearing, comprising fixed rolling members.

The invention also relates to an arrangement for carrying out the method.

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In the manufacture of paper, board and other fibrous webs, various nip rolls are used during manufacture to, among other things, dewater, apply treatment agents, and smooth and polish the surface of the product. The greatest clamping forces are found in calenders and dewatering presses. The nip load between the rollers is controlled by compression by various actuators, and in some cases it is possible that the forces exerted on the roller are so balanced that the bearings 20 supporting it are not subjected to any load at all and so-called. zero load area. By this is meant a bearing load situation where the load on its rolling members is too low to cause rolling contact and the bearing begins to slide. A zero load is detrimental to the bearings because sliding contact consumes the rollers of the bearings quite quickly. Bearing manufacturers therefore recommend a 1-2% load on the bearing capacity to eliminate the zero load problem.

30 In most cases, the risk of being in the zero-load area occurs with calendars. The load on the bearings of the calender end rolls varies according to the calender running conditions. Adjusting the calender line load affects the load on the roller bearings. When the force 35 generating gravity in the vertical track and the nip lifting force from the bottom of the roll are in equilibrium, the bearings are not loaded. Likewise, if a roll is subjected to a line load on both sides, a situation may arise in which the misalignment of the nip forces and the pull of the roll mass are balanced. Roller bearings require 5 specific loads to prevent the rollers or balls in the bearing from rotating and not sliding. In the zero-load situation described above, this load criterion is not met.

10 In a multi-roll calender, zero load occurs in the so-called. partial nip, so that only two or three rollers work together. The problem also occurs with soft calendars. To eliminate the zero load problem, there is a restriction on the calender line load adjustment range. With the Vertical Soft and Multi-Roll Calender 15, the minimum load recommended by the bearing manufacturers significantly reduces the calender's available line loading range, especially for matte grades. Within a linear nip load range of a partial roller of a multi roll calender, typically 20 to 100 kN / m, up to 30% may be a limited operating range due to a zero load 20 mains problem. If the process were still to work best in this area, this would be a serious problem.

In order to eliminate or reduce the zero load 25 conventionally used e.g. the following means: - the rack may be slanted, whereby the horizontal force component of the load generates the required minimum load on the bearings, such a solution is disclosed in WO 2006/051169, 30 in the zero load range, 35 - Applying brake oil through the oil 3 through the bearing - US 4,322,117.

Installing a track on a skewed calender requires a redesign of the entire track and device placement.

Thus, this solution is at least not suitable for use in existing calendars. If you want to stay in a vertical calender for other reasons, skewing is not a good option as it will result in expensive roller feeders. The axial loading device has been tested in 10 soft calendars. For example, the device does not completely eliminate the problem with, for example, double row spherical roller bearings, as the device only loads one of the roller rings, which further reduces the load on the parallel ring. Bearing retreading is an option to reduce the problem of zero loading. 15 However, it does not completely remove it. In addition, the coating is expensive and its functionality is highly dependent on the lubrication conditions. Due to replaceable rolls, all rolls should be equipped with expensive plated bearings.

It is an object of the present invention to provide a method and arrangement for reducing or even eliminating the problem of zero load on fiber web machines.

The invention is based on the fact that the shaft leading from the roll of the fiber web machine to the bearing 25 is loaded radially and in a direction deviating from the loading direction.

According to a preferred embodiment of the invention, the loading direction is substantially horizontal so that it does not produce 30 loading directional components that should be taken into account in the line load calculation of the machine.

According to one preferred embodiment, the bearing shaft is directly loaded.

More specifically, the method according to the invention is characterized in what is stated in the characterizing part of claim 1.

The arrangement according to the invention, in turn, is characterized by what is disclosed in claim 6.

The invention provides considerable advantages.

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The invention can eliminate bearing damage due to a zero load problem. Equipment utilization improves and unpredictable production outages are reduced. The implementation of the device is easy and reasonably inexpensive and can be adapted to existing devices. At its most advantageous, the device does not affect the operation of the calender at all except by removing the harmful restriction of use. When there is no usage restriction, the machine operator can better optimize his production, for example to produce the best quality. The advantage of the device is its simplicity and thus its small space. It does not need a cooled and sealed separate bearing housing for the roll shaft. Roller movements do not complicate the device as the device is only attached to the roller while driving with the rollers in a straight line.

25 As the roller opens, the machine quickly releases from the roller shaft.

The invention will now be explained in more detail with reference to the accompanying drawings.

Figure 1 is a schematic top view of the invention.

Figure 2 is a side elevational diagram of the invention.

Fig. 1 shows a roll 1 with an axis 2 at its end. An axle 2 is attached to a bearing housing 3, which in turn is secured to a load arm 4. The roll 1, the shaft 2 and the bearing housing 3 move on the load arm. An example of Fig. 1 may be a calender roll that moves relatively little in the driving situation, but for example in the event of a web break, the Nippe-5 moves quickly and at a moderate distance when the ice is opened. The loading device according to the invention consists of a loading fork 5 and a hydraulic cylinder 6 and a wear ring 7 driving it. The loading device is arranged in the axis 2 so that the movement and loading direction of the hydraulic cylinder 6 is horizontal when the calender is running. In this case, the cylinder 6 is secured by clamps 10, 11 to the load arm 4 parallel thereto. Thus, the direction of movement of the cylinder is parallel to the load arm. The structure of the load fork 5 is more clearly shown in Fig. 15. are pressed. The loading ring mi-20 is fed based on the surface pressure and the roll ring interval is sufficient for the wear ring to last because the tire remains stuck on the replaceable roll. The width of the load wheels and the wear ring may be about 100 mm.

25 The loading direction should be as horizontal as possible to avoid creating a vertical loading component affecting the nip load. In this case, the zero load protection load need not be taken into account when calculating the nip load. Of course, with the current computing capacity, adjusting a standard load li-30 to nip load computing does not pose a problem.

In Fig. 2, the nip loads are denoted Q1 and Q2 and the zero load manifold load F. In addition, the nip forces and bearing forces are, of course, influenced by the masses of the rollers. However, if the applied 6 load force F is horizontal, i.e. at an angle of 90 ° to the vertical load, the calculation of nip loads can be maintained and the calender operation need not be interfered in this regard. The risk of a zero load usually occurs only in vertical loads, but also in non-vertical loads, the forces exerted on the bearing can be added to create a zero load situation. The invention can also be applied in these cases. Further, although it is advantageous to add that the zero load compensation is perpendicular to the load force, the slight deviation from this direction does not change the nipple load much. For example, if a zero load load is set between 75 and 105 ° with a vertical load, the portion of the vertical component 15 is quite small and may even be neglected in the calculation of the nip load. The same applies to non-vertical load situations.

The minimum bearing load required by the bearing is supplied to the roller 1 by means of roller-bearing load-bearing wheels 9 which load the shaft 1 of the roller 1 adjacent the main bearing housing 3. The load is approximately horizontal, so it does not even need to be taken into account in the calender line load calculation. The device can also be made to be loaded in other directions, but the load must be taken into account in the line load calculation. The horizontal force does not cause significant deformation of the nip, so it does not affect the line load profile of the calender. Preferably, the device is switched on only in and near the calender's zero load range. The device is suitable for both thermal rollers 30 and polymer rolls because it does not move the roll from its position but only causes a light load. Only the wear ring 7 that rotates against the load wheels 9 is added to the rolls. The machine does not increase the roll change time because it remains trapped in the calender when the roll is changed. The load on the load wheels is created by, for example, a hydraulic or pneumatic cylinder or other actuator for direct movement. The device is equipped with a lever transmission for transmitting the force of the cylinder to the load wheel. In normal driving, when there is no zero load problem, the device 5 is driven by cylinders off the roll axis.

In addition to the above, the present invention has other embodiments. In other embodiments of the invention, the load may be provided by a sliding bearing element 10 located in the main bearing housing. It gets its lubrication from the main bearing lubrication circuit. A separate roller bearing housing on the roller shaft is one possible solution. In all of these, it is conceivable to use tensile loading instead of pushing. One solution to provide tensile load on a roller or its axle is a chain or belt loop that is tightened to the specified tension either permanently or only at zero load risk. The invention can also be applied to bearings of cylinders and other rotating machine members. The load can also be applied at the end of the roll in the free area of the jacket 20 provided that there is sufficient space.

Claims (10)

A method of reducing the zero load in connection with the storage of a rotating machine element (1) for a fiber web machine, wherein the machine element (1) is loaded (Q1, Q2) in the load direction, characterized in that a load (F) which deviates from the load direction is installed for the machine element (1) at least where it operates in the zero load risk area in such a way that the deviating load is arranged in a 75 - 105 ° , preferably at a 90 ° angle relative to the load forces of the rollers. Method according to claim 1, characterized in that the aberrant load force (F) is directed to the axis (2) of the roller. Method according to any of the preceding claims 1 or 2, characterized in that the deviating force (F) is directed against the sheath of the roller (1). Method according to any of the preceding claims, characterized in that the deviating loading force (F) is directed to a separate bearing arranged at the axis (2) of the roller. Method according to any of the preceding claims, characterized in that the machine element under load consists of a roller of a calender, preferably a multi-pin calender. Apparatus for reducing the zero load range of a bearing in the vertical direction under load, rotating machine element (1), which rotating machine element comprises at least one sheath, one support shaft (2) and a roller bearing type main bearing (3) arranged (5). characterized by at least one load means (5 - 7) to form a load deviating from the load direction against the machine element (1) in such a way that the load means (5 - 7) are arranged in a 75 - 105 °, preferably in a 90 ° angle relative to the vertical load force. Device according to claim 6, characterized in that the load means (5 - 7) comprise a load ring (7) arranged on the shaft (2) and an operating element (6), which provides a straight movement, and to the operating element (6). connected load wheels (5) which can be pressed against the load ring (7) by the operating element. Device according to any of claims 6-7, characterized by a separate bearing housing arranged at the shaft (2) for transferring the load force to the shaft (2). Device according to any of claims 6-7, characterized by a means for directing the aberrant load force (F) to the sheath of the rotating machine element (1). Device according to claim 9, characterized in that it comprises a link-shaped means for forming tensile load.