DE10126103A1 - Bearing assembly has at least two roller bearings each axially pretensionable by at least one hydraulic tensioning device hydraulically interconnected for reciprocal compensation of axial forces acting on roller bearings - Google Patents

Abstract

The bearing assembly has at least two roller bearings (16,18) in tandem to support a shaft (12) in a housing (14), with each roller bearing axially pretensionable by at least one hydraulic tensioning device (38,40). The tensioning devices are hydraulically interconnected for reciprocal compensation of the axial forces acting on the roller bearings. A pressure switch is provided between the two tensioning devices to open the hydraulic connection to balance the axial forces at a predetermined switching pressure.

Description

The invention relates to a bearing arrangement, in particular for a machine tool, according to the generic term of the An saying 1.

A bearing arrangement of the type mentioned above occurs especially when used in addition to radial loads the bearing arrangement can also attack high axial loads and an axial displacement of the shaft relative to the housing should be avoided. So are such bearing arrangements especially in machine tools for storing the workpiece spindle or the tool spindle. Through the positioning of the roller bearings in the housing in the same direction which the pressure cone of the rolling bearing in the same axial direction show the Axi attacking the rolling bearings al forces distributed over the two bearings, so that the Bearing arrangement can absorb high axial forces.

In this known bearing arrangement there is now the pro blem that if the rolling bearings are at one on the shaft attacking axial force not exactly positioned to each other Support in the housing, load the roller bearings differently be steady. To avoid this, both the roller bearings as well as the bearing points in the housing and the bearings made on the shaft very precisely and the bearings be axially biased during assembly. Despite the high manufacturing, measuring and assembly costs the known bearing arrangements due to the manufacturing due to tolerances nonetheless to slight deviations in position conditions between the rolling bearings and thus too uneven axial loads.  

Despite the small deviations in position, which are usually in µ range, arise especially at high axial forces acting on the shaft, these can be at work machine tools are at 200 kN and more, correspondingly high Differences in the axial load on the La screened properly. These can cause uneven wear, related, different high lifespan and in case of peak loads, possibly even to a Versa against the disproportionately loaded roller bearing.

It is an object of the invention to provide a bearing arrangement training of the type mentioned at the beginning so that the Rolling the bearing arrangement axially as evenly as possible be charged.

The invention solves the problem by a bearing arrangement with the features of claim 1.

In the bearing arrangement according to the invention is for everyone Rolling bearing provided at least one clamping device with the axial bearing in question is preloaded can. The tensioning devices of the rolling bearings are in turn coupled with each other so that they are on the roller bearings attacking axial forces by changing the respective Compensate the preload with each other.

Grips one bearing compared to the other Ren roller bearing higher partial axial force, increases with the Coupling device of the heavily loaded roller bearing coupled Clamping device of the other rolling bearing its axial front clamping force, while the clamping device of the higher load roller bearing reduces the axial preload. That I  the two rolling bearings by positioning them in the same direction axially support each other, this now takes more axially preloaded roller bearings part of the other roller bearings attacking partial axial force additionally, whereby the axial load on the previously heavily loaded roller bearing decreases. Does the relationship between the to the Partial axial forces attacking the bearings again Partial axial forces in the same way again balanced.

Through the interplay between those that occur on the one hand axial loads on the rolling bearings of the bearing assembly and on the other hand varied from the tensioning devices Preloading forces can be applied to the roller bearings compensating partial axial forces mutually, so that the rolling bearings are exposed to the same axial loads are.

This makes it possible to prevent spikes in the axia len load to absorb and an even supply to reach the rolling bearing. Furthermore, the Bearing arrangement according to the invention deviations in installation location of the rolling bearings balanced without much effort, so that the measuring and manufacturing effort at the inventor inventive bearing arrangement turns out less than in the previously known bearing arrangements.

Further advantageous developments of the invention result from the following description, the drawing as well as the subclaims.

So in a preferred embodiment the Lageran order proposed for the axial preloading of the rolling bearings to use hydraulic tensioners that hydrau communicating with each other. The use of hy drastic tensioning devices has the advantage of being on  due to the incompressibility of the hydraulic fluid There are slight differences between those on the roller bearings attacking axial forces can be compensated directly.

In a further development of this embodiment proposed between the hydraulic tensioners to provide a pressure switch that the hydraulic Ver binding only at a given switching pressure to compensate Chen releases the axial forces. This can be a targeted at which axial loads the Axial forces attacking rolling bearings are compensated should.

It is also proposed to place a pressure sensor in the flow Connection between the two hydraulic clamping to arrange facilities. With the help of the pressure sensor the hydrostatic pressure in the hydraulic fluid con determined continuously or intermittently to a pressure waste, for example due to a leak in the system is to be able to record.

Furthermore, when using the hydraulic Clamping devices proposed for the hydraulic To provide clamping devices with a common filling valve, which ensures even filling of the hydraulic Clamping devices is ensured.

The oil is preferably used as the hydraulic fluid with which the rolling bearings are also lubricated. On the This way it is achieved that possibly from the hydrau Clamping devices exiting Hy draulic liquid with the oil with which the La lubricated, can mix easily.  

In a preferred embodiment of the bearing arrangement With hydraulic clamping devices, every hydrauli cal clamping device an axially adjustable pressure ring on in a ring filled with hydraulic fluid is only recorded. The ring grooves of the hydraulic clamping facilities are in flow communication with each other, so that if the pressure ring is moved, the clamping device tion of a rolling bearing caused by an increase in the this partial axial force acting on the roller bearing is the hydraulic fluid from the annular groove in the Ring groove of the other hydraulic clamping device on whose rolling bearing is pressed, whereby the other Wälzla ger to compensate for the part attacking the rolling bearings axial forces are biased more axially.

As roller bearings are in the bearing arrangement according to the invention Preferably, spherical roller thrust bearings are used because due to their structure even at high speeds are able to simultaneously high axial and radial bela recordings. For axial pretensioning of the axial pen The roller bearing is the corresponding axial spherical roller bearing ger associated clamping device on its outer ring bar, so that when the outer ring of one Spherical roller thrust bearing the preload of this ordered clamping device is increased. This directs the Zu continued to the other tensioning device, which of their to compensate for the on the spherical roller thrust bearings partial axial forces engaging the outer ring of the other Axial spherical roller bearing preloaded.

In addition, it is possible to use the spherical roller thrust bearing with the help of the clamping devices before commissioning the bearing arrangement with a minimum taxi load without play  preload, which makes a kinematically perfect Abrol len of the spherical roller thrust bearings even at low on the Spherical roller thrust bearings attacking during operation Axial forces is ensured.

Alternatively, other types of roller bearings, for example Shoulder ball bearings, single row angular contact ball bearings, tapered roller oil bearings and similar types of rolling bearings, who are able to absorb combined loads.

It is also proposed to insert a first one into the housing set and a second axially supported on this Use insert, which is one of the rolling bearings on first use and the other roller bearing on the second use supports and one of each of the two inserts Clamping devices is provided. The use of the A sets has several advantages. On the one hand, one and the same housing when using different inserts use for differently dimensioned bearing arrangements be det. On the other hand, the clamping devices can be mounted outside the housing in the inserts where by mounting the tensioning devices compared to egg nem direct installation in the housing is facilitated.

Furthermore, it is advantageous if the two are the same sensibly arranged roller bearings by another Rolling bearings are adjusted axially to a defined axial Ensure installation position of the shaft. It is particularly particularly advantageous if the two are arranged in the same direction neten rolling bearing and the further rolling bearing in an O arrangement are axially aligned with each other, so that the bearing arrangement a large support base. This can also be the case with short Bearing distances absorb a high tipping moment, so too radial forces acting at a distance from the bearing arrangement can be supported by the bearing arrangement.  

The bearing arrangement according to the invention is particularly preferred for storing a spindle in the spindle housing of a plant used machine because the bearing arrangement for receiving is designed for high radial and axial loads rend at the same time an axial displacement of the spindle effectively prevented relative to the spindle housing.

Because of the high forming that occurs during spinning rolling forces directly on the workpiece spindle when Press rollers act, the bearing according to the invention arrangement in particular for storing the spindle in the spindle rim housing of a pressure rolling machine.

In the following the invention will be explained with reference to an embodiment game explained with reference to the drawing. In it, the only figure shows a sectional view of a La geranordnung a spindle in a press rolling machine.

In the single figure, a bearing arrangement 10 for rotatably supporting a spindle 12 in a spindle housing 14 of a press-rolling machine is shown in a sectional view. On the end face of the spindle 12 shown on the left in the figure, a workpiece holder, for example a chuck, is fastened in a known manner during operation.

For storing the spindle in the spindle housing 14 , two axial spherical roller bearings 16 and 18 are pushed onto the spindle 12 . The axial spherical roller bearings 16 and 18 are equally useful in tandem in the spindle housing 14 , ie the two axial spherical roller bearings 16 and 18 are arranged so that the pressure cone D of the axial spherical roller bearings 16 and 18 point in the same axial direction , Between the two inner rings 20 and 22 of the two spherical roller thrust bearings 16 and 18 , an intermediate ring 24 is pushed onto the spindle 12 , which holds the inner rings 20 and 22 of the spherical roller thrust bearings 16 and 18 at a defined distance from one another.

Furthermore, a tapered roller bearing 26 is slid onto the spindle 12 , which is axially adjusted with respect to the axial spherical roller bearings 16 and 18 positioned in a tandem arrangement. By the axial adjustment of the gel roller bearing 26 to the spherical roller thrust bearings 16 and 18 it is achieved that the bearing arrangement 10 has a large support base which can absorb a high tilting moment, which acts on the spindle 12 by radial loads acting at a distance from the bearing arrangement 10 during the operation is caused.

The outer ring 28 of the spherical roller thrust bearing 16 is inserted into egg NEN first insert 30 inserted in the spindle housing 14 is set and supported in this. The outer ring 32 of the second spherical roller thrust bearing 18 is received in a second insert 34 , which is also inserted into the spindle housing 14 , is axially supported in this on a shoulder 36 , while the second insert 34 in turn the first insert 30 in the spindle housing 14 axially supports. Between the two inserts 30 and 34 there is provided a cylindrical pin 37 which serves to prevent rotation and prevents the two inserts 30 and 34 from rotating relative to one another about the spindle 12 . The Ke gel roller bearing 26 is also inserted into the second insert 34 , whereby the previously mentioned axial adjustment is possible.

At each insert 30 and 34 , a hydraulic Spannein direction 38 and 40 is provided, with the help of which the two spherical roller bearings 16 and 18 can be hydraulically preloaded hy in the axial direction.

Thus, the hydraulic tensioning device 38 provided on the first insert 30 has a pressure ring 42 which can be placed on the end face of the outer ring 28 of the axial spherical roller bearing 16 and is slidably received in an annular groove 44 which runs concentrically to the axis of rotation R R of the spindle 12 . The annular groove 44 is in flow connection with a connec tion channel 46 which is formed on the spindle housing 14 .

In the same way, the hydraulic tensioning device 40 has a pressure ring 48 which bears against the end face of the outer ring 32 of the other axial spherical roller bearing 18 and is displaceably received in an annular groove 50 which is identical to the annular groove 44 . The annular groove 50 is also connected to a connecting channel 52 of the spindle housing 14 . To the two connecting channels 46 and 52 , a line system 54 is connected, which connects the two connec tion channels 46 and 48 and thus the two ring grooves 44 and 50 hydraulically. The line system 54 can be filled with a hydraulic fluid through a filling valve 56, a predetermined pressure being set in the hy draulic system formed by the line system 54 and the two hydraulic tensioning devices 38 and 40 during the first filling. The hydraulic clamping devices 38 and 40 are hydraulically preloaded by this pregiven filling pressure, so that their pressure rings 42 and 48 each bear with a defined preload force Fv1 and Fv2 on the outer rings 28 and 32 of the two axial pen roller bearings 16 and 18 and preload them axially NEN. In the line system 54 , a pressure sensor, not shown, is also arranged, with which the hydrostatic pressure in the line system is determined. With the help of the pressure sensor, a pressure drop in the line system 54 can be detected, which occurs, for example, in the event of a leak. In such a case, appropriate countermeasures can then be taken, such as. B. by refilling hydraulic fluid speed, the pressure drop in the line system 54 can be compensated.

Furthermore, a pressure switch (not shown) is provided in the line system 54, which prevents an exchange of hydraulic fluid between the two hydraulic tensioning devices 38 and 40 until the hydraulic internal pressure acting in one of the two hydraulic tensioning devices 38 and 40 exceeds a predetermined value, as will be explained later.

In order to also be able to absorb the radial loads acting on the spindle 12 during operation, a cylindrical roller bearing 58 is in the first vicinity in the immediate vicinity of the connection end of the spindle 12 shown on the left in the figure, on which the workpiece holder is provided Insert 30 used. With this, the spindle 12 is supported in the spindle housing 14 in the radial direction.

On the open end face of the first insert 30 , a housing cover 60 is screwed, with which the Zylinderrollenla ger 58 secured and the housing interior of the spindle housing 14 is sealed fluid-tight to the outside with the aid of seals 62 . The inner ring of the cylindrical roller bearing 58 abuts a support ring 64 which is pushed on to the spindle 12 and in turn to that of the inner ring 20 of the spherical roller thrust bearing 16 supports the Zylinderrol roller bearing 58 facing end side. The other end of the spindle housing 14 is closed by a cover 66 , which seals the interior of the housing in a fluid-tight manner by means of a shaft sealing ring 68 .

Queuing for axially of the tapered roller bearing 26, a shaft nut 70 is screwed onto the spindle 12, which abuts the tapered roller bearing 26 at the In nenring 72nd As soon as the shaft nut 70 is preloaded, some of the forces are transmitted to the support ring 64 via the tapered roller bearing 26 , the second insert 34 , the first insert 30 and the two axial spherical roller bearings 16 and 18 .

The support ring 64 is in turn supported on a spindle shoulder 74 , so that the pretensioning force transmitted from the spindle nut 70 to the spindle 12 is transmitted to the support ring 64 via the spindle shoulder 74 . In this way, the entire arrangement of axial spherical roller bearings 16 and 18 , the two inserts 30 and 34 , the spindle 12 and the tapered roller bearing 26 is axially preloaded and secured in the spindle housing 14 . The bearing assembly 10 is preloaded with a minimum tax clamping force that corresponds to the expected load. In this way it is achieved that the bearing arrangement is axially preloaded without play and the spindle 12 is not relative to the housing 14 even under normal loads.

Furthermore, a plurality of lubrication channels 76 are provided on the second insert 34 , through which the various bearings 16 , 18 , 26 and 58 can be supplied with lubricants.

As lubricants for the bearings 16 , 18 , 26 and 58 there is the same oil used for the hydraulic clamping devices 38 and 40 , so that a mixing of the lubricating oil with the hydraulic fluid is possible without problems.

The functioning of the bearing arrangement 10 according to the invention is explained in more detail below.

As soon as the press-rolling machine is put into operation, a force Fres resulting from a radial force Fr and an axial force Fa acts on the spindle 12 . The radial force Fr acting on the bearing arrangement 10 , in accordance with the given geometric ratio, leads to load moments which are taken up by the individual bearings 16 , 18 , 26 and 58 .

The axial force Fa acting on the bearing arrangement 10 , however, is only absorbed by the two axial spherical roller bearings 16 and 18 and the tapered roller bearing 26 . Act through the same arrangement of the axial spherical roller bearings 16 and 18 partial axial forces Fa1 and Fa2 on the two axial spherical roller bearings 16 and 18 , which are caused by the axial force Fa acting against the pressure cones D of the axial spherical roller bearings 16 and 18 on the spindle 12 are.

The partial axial force Fa1 or Fa2 which engages on the respective spherical roller bearing 16 or 18 counteracts the respective preload force Fv1 or Fv2 of the hydraulic tensioning device 38 or 40 in question, which supports the respective spherical roller bearing 16 or 18 .

Ideally, the two spherical roller thrust bearings 16 and 18 should be equally loaded by the partial axial forces Fa1 and Fa2, ie the two partial axial forces Fa1 and Fa2 are identical. However, this is only guaranteed if the axial force Fa from the inner ring 20 of the axial spherical roller bearing 16 partially to the inner ring 22 of the intermediate ring 24 transmitted to their axial spherical roller bearing 18 is dimensioned exactly such that the axial spherical roller bearing 16 is also included support its outer ring 28 on the first insert 30 and the axial spherical roller bearing 18 with its outer ring 32 on the second insert 34 , each with the same force.

In the bearing arrangement 10 according to the invention, the outer rings 38 and 32 of the two axial spherical roller bearings 16 and 18 are now supported by the hydraulic tensioning devices 38 and 40 against the partial axial force Fa1 and Fa2, respectively.

If one of the two partial axial forces Fa1 or Fa2 increases compared to the other partial axial force Fa2 or Fa1, in the relevant hydraulic tensioning device 38 or 40 of the relevant outer ring 28 or 32 of the axial spherical roller bearing 16 or relative to the other hydraulic tensioning device 40 or 38 causes a pressure increase in the hydraulic fluid contained in the annular groove 44 or 50 .

If the pressure difference between the two annular grooves 44 and 50 of the two hydraulic tensioning devices 38 and 40 exceeds the signal pressure specified by the pressure switch, not shown, the pressure switch opens, so that hydraulic fluid from one hydraulic tensioning device 38 or 40 into the other hydraulic tensioning device 40 or 40 38 can flow in.

This results in a pressure equalization between the two hydraulic tensioning devices 38 and 40 , so that the preload force Fv1 or Fv2 of the one hydraulic tensioning device 38 or 40 , on the axial spherical roller bearings 16 and 18, the higher partial axial force Fa1 and Fa2 engages, is reduced, while at the same time the preload force Fv2 or Fv1 acting on the other spherical roller bearing 18 or 16 is increased by the relevant hydraulic clamping device 40 or 38 to the same extent. This results in an equal load pressure in the two hydraulic tensioning devices 38 and 40 , whereby a uniform load on the two axial spherical roller bearings 16 and 18 is effected.

In this way, it is possible to compensate for fluctuations occurring in the axial loading of the two axial pendulum roller bearings 16 and 18 with one another. If a permanent compensation between the attacking partial axial forces Fa1 and Fa2 is to be made, the pressure switch in the line system 54 is dispensed with, so that the hydraulic fluid can flow freely between the tensioning devices 38 and 40 to and fro.

Claims (11)

1. bearing arrangement, in particular for a machine tool,
with at least two roller bearings ( 16 , 18 ) for supporting a shaft ( 12 ) in a housing ( 14 ),
wherein the rolling bearings ( 16 , 18 ) are designed to accommodate axial forces (Fa) and are positioned in the same direction in tandem in the housing ( 14 ), characterized in that each rolling bearing ( 16 , 18 ) by at least one clamping device ( 38 , 40 ) can be axially preloaded and that the tensioning devices ( 38 , 40 ) of the roller bearings ( 16 , 18 ) are mutually coupled for mutual compensation of the axial forces (Fa) acting on the roller bearings ( 16 , 18 ). 2. Bearing arrangement according to claim 1, characterized in that the tensioning devices are hydraulic tensioning devices ( 38 , 40 ) which are connected to one another for the mutual compensation of the axial bearings ( 16 , 18 ) engaging the axial forces (Fa). 3. Bearing arrangement according to claim 2, characterized in that between the two hydraulic Spanneinrich lines ( 38 , 40 ) a pressure switch is provided which releases the hydraulic connection from a predetermined switching pressure to compensate for the axial forces (Fa). 4. Bearing arrangement according to claim 2 or 3, characterized in that between the two hydraulic Spanneinrich lines ( 38 , 40 ) a pressure sensor for detecting the pressure acting in the hydraulic connection hen is vorgese. 5. Bearing arrangement according to claim 2, 3 or 4, characterized in that a common filling valve for filling the hy draulic clamping devices ( 38 , 40 ) with hydraulic fluid is provided. 6. Bearing arrangement according to one of claims 2 to 5, characterized in that the hydraulic fluid is an oil which can be used simultaneously for lubricating the bearings ( 16 , 18 , 26 , 58 ). 7. Bearing arrangement according to one of claims 2 to 6, characterized in that each hydraulic tensioning device ( 38 , 40 ) has an axially adjustable pressure ring ( 42 , 48 ) which is received in an annular groove ( 44 , 50 ) which with a hydraulic fluid is filled, and that the annular groove ( 44 ) of a hydraulic tensioning device ( 38 ) with the annular groove ( 50 ) of the other hydraulic tensioning device ( 40 ) is in flow connection. 8. Bearing arrangement according to one of the preceding claims, characterized in that two, in particular identical, axial spherical roller bearings ( 16 , 18 ) serve as roller bearings, the inner ring ( 20 ) of an axial spherical roller bearing ( 16 ) being formed by an intermediate ring ( 24 ) on the inner ring ( 22 ) of the other spherical roller thrust bearing ( 18 ), and that on the outer ring ( 28 , 32 ) of the respective spherical roller thrust bearing ( 16 , 18 ) for axial preloading the respective spherical roller thrust bearing ( 16 , 18 ) to be arranged clamping device ( 38 , 40 ). 9. Bearing arrangement according to one of the preceding claims, characterized in that a first insert ( 30 ) and an axially supporting second insert ( 30 ) are inserted into the housing ( 14 ) such that one of the roller bearings ( 16 ) on the first One set ( 30 ) and the other roller bearing ( 18 ) supports the second insert ( 34 ) and that one of the clamping devices ( 38 , 40 ) is provided on each of the two inserts ( 30 , 34 ). 10. Bearing arrangement according to one of the preceding claims, characterized in that a further roller bearing ( 26 ), in particular a tapered roller bearing, is provided for axially positioning the two roller bearings ( 16 , 18 ) and that the two roller bearings ( 16 , 18 ) arranged in the same direction are provided. and the further roller bearings ( 26 ), in particular in an O arrangement to one another, are set axially. 11. Bearing arrangement according to one of the preceding Ansprü surface, characterized in that the bearing arrangement ( 10 ) for storing a spindle ( 12 ) in the spindle housing ( 14 ) of a machine tool, in particular in the spindle housing ( 14 ) of a pressure rolling machine, is used.