WO2008119597A2

WO2008119597A2 - Axial angular contact ball bearing arranged in four rows, comprising spherical rollers, particularly for mounting a rotary table on machine tools

Info

Publication number: WO2008119597A2
Application number: PCT/EP2008/052007
Authority: WO
Inventors: Frank Dürschmied; Andreas Geier; Jörg-Oliver Hestermann; Herbert Schimschal; Martin Schreiber
Original assignee: Schaeffler Kg
Priority date: 2007-03-30
Filing date: 2008-02-19
Publication date: 2008-10-09
Also published as: DE102007015421A1; WO2008119597A3

Abstract

The invention relates to an axial angular contact ball bearing (1) which is suitable for mounting a rotary table on machine tools and essentially comprises a monolithic or two-part inner bearing ring (2), an outer bearing ring (2), and a plurality of rolling members (8, 9) that are arranged in several rows (4, 5, 6, 7) next to each other between the bearing rings (2, 3). The bearing surfaces of the rolling members (8, 9) roll at defined pressure angles along several raceways (12, 13, 14, 15) that are disposed next to one another on the external face (10) of the inner bearing ring (2) and the internal face (11) of the outer bearing ring (4). According to the invention, all rolling members (8, 9) of the axial angular contact ball bearing (1) are designed as spherical rollers which have two faces that are symmetrically oblate at the axial end and run parallel to each other in order to be able to place more rolling members (8, 9) between the bearing rings (2, 3) of the axial angular contact ball bearing (1) than in previously known rotary table bearings while the mounting space is the same or nearly the same, and significantly increase the load-bearing capacity of the axial angular contact ball bearing (1).

Description

Name of the invention

Axial angular contact bearings, in particular for rotary table storage on machine tools

description

Field of the invention

The invention relates to a thrust roller bearing according to the preamble forming features of claim 1, and they particularly advantageous for rotary table bearings of machine tools applicable.

Background of the invention

Modern rotary table bearings for machine tools are nowadays manufactured as ready-to-install precision bearings for combined loads with high demands on the running accuracy and, depending on the speed and duty cycle, are designed either as axial-radial bearings or axial-angular-contact ball bearings. Both bearing types accommodate radial and bilateral axial loads as well as tilting moments and are preloaded radially and axially free of play. While axial-radial bearings are mainly used in standard applications with low speeds and low duty cycle and are usually characterized by a higher, with the speed increasing friction torque, axial angular contact ball bearings are very well suited for fast-turning applications with high duty cycle and are characterized by significantly low friction and low lubricant consumption.

Such rotary table bearings are known inter alia by the published by the applicant Catalog "Rolling" January 2006 and are described for example on pages 990 to 1019 in the embodiments mentioned as axial-radial bearings and axial angular contact ball bearings essentially from an axial and a radial part, wherein the axial part by an axial needle or cylindrical roller ring, an outer bearing ring, an angle ring and a wave washer is formed while the radial part of a full complement or cage-guided, biased cylinder roller set is used. By contrast, the illustrated axial angular contact ball bearings essentially consist of a one- or two-part inner bearing ring and of an outer bearing ring and a plurality of bearing balls arranged side by side between the bearing rings in two juxtaposed rows which at a defined contact angle with their running surfaces on several roll side by side on the outer side of the inner bearing ring and raceways arranged on the inside of the outer bearing ring. In addition, also designed as a double tapered roller bearing rotary table bearings are known in which instead of two rows of bearing balls two mutually employed rows of cylindrical rollers are used as rolling elements.

Current development trends in the machine tool industry, however, go to the fact that to increase the performance of machine tools whose rotary tables must be operable at ever higher speeds in order to perform in one clamping per machine in addition to the usual milling, drilling and grinding a turning of the workpieces can. So that this is possible even with smaller workpiece diameters taking into account the optimum machining speed, machine tools with rotary tables are required, which can be operated permanently even at very high speeds. Initial studies have shown, however, that the known rotary table bearings meet such limits in terms of their load capacity, rigidity and thermal resistance and by entering lubricant shortage, bearing overheating and Wälzkörperverklemmungen either have an extremely reduced service life or are not suitable. An obvious measure to avoid such premature bearing failures would be to increase the carrying capacity of the rotary table bearing by larger-sized rolling elements or by arranging additional rows of rolling elements, however, such measures are usually always at the expense of rigidity and accuracy of the Bearings and also require an associated only with complex design changes increased storage space.

Object of the invention

Based on the stated disadvantages of the solutions of the known prior art, the invention is therefore the object of an axial skew, especially for rotary table storage on machine tools to design, which at the same or approximately the same space requirements as known rotary table bearings and without losses Rigidity and accuracy has a higher load capacity and thus is suitable for very high speeds in continuous operation.

Description of the invention

According to the invention, this object is achieved in an axial helical roller bearing according to the preamble of claim 1 such that all rolling elements of the axial helical roller bearing are formed as ball rollers, each having two axial side symmetrically flattened from its basic spherical shape, parallel to each other arranged end faces.

The invention is thus based on the finding that it is already possible by exchanging the previously trained as bearing balls or cylindrical rollers against trained as ball rolling elements and by adapted thereto track training in the bearing rings, the number of rolling elements and thus the carrying capacity of an axial Inclined roller bearing without loss of rigidity and accuracy to increase so that it is also suitable for very high speeds, with no axial space flattened and therefore narrow design of the rolling elements no additional space for such axial thrust roller bearing is necessary.

Preferred embodiments and advantageous developments of the invention formed according to the axial angular contact roller bearing are in the subclaims described.

Thereafter, it is provided according to claims 2 and 3 in the inventively designed axial oblique roller bearing, that it preferably has four rows formed as ball rollers rolling elements, of which the two inner rows are formed with an identical pitch circle diameter, which is smaller than the also identical pitch circle diameter is two outer rows. In addition, while the diameter of the ball basic shape of the rolling elements of the two outer rows compared to the diameter of the rolling elements of the two inner rows is larger, so that in each case an outer row and the adjacently arranged inner row of rolling elements a first and a second row pair, each with different Wälzkörper- and form pitch diameters. Alternatively, it would also be possible to form the ball rollers of all rows with the same diameter of the ball basic shape at different pitch diameters between the inner and the outer rows of rolling elements. Likewise, it would be conceivable to equip the axial angular rolling bearings with the same or different ball basic diameters depending on the respectively required bearing yield numbers with less or more than four rows of ball rolling elements designed as ball rollers. Regardless, however, it is advantageous to additionally form the ball rollers on the edge parts of their treads or the edge parts of their careers in the inner and outer bearing ring with an expiring logarithmic profile to counteract occurring edge stresses between the ball rollers and their raceways.

Based on the above-described embodiment, the invention formed according to Axial Schrägwälzlager according to claims 4 and 5 further characterized by the fact that the adjacent rolling elements of both pairs of rows are each arranged on a common axis of rotation and parallel to each other inclined pressure angle axes and both pairs of rows Rolling elements are employed in O arrangement against each other. The rolling elements of each pair of rows are preferably guided in such a way in each case in a common, designed as a plastic cage cage bearing cage, in that the rolling bodies arranged in each case on a common axis of rotation are arranged adjacent to one another in a common cage window with their mutually facing side faces and thus lead one another mutually in an advantageous manner. In addition, it has proven to be kinematically particularly advantageous if the diameters and the widths of the adjacent rolling elements of both rows are dimensioned such that all enveloping cones touching the rolling elements at their outer contours with their conical tips exactly at the intersection of the common axis of rotation of these rolling elements are arranged with the axis of rotation of the axial angular contact bearings. This Hüllkegel bearing kinematics known per se from tapered roller bearings represents an optimum for angular contact bearings of all kinds with respect to bearing load capacity, wear reduction and service life and moreover, in the specific case, causes the adjacent ball rollers of two adjacent rows to roll synchronously with one another or at least different relative speeds between these ball rollers, the friction occurring is reduced.

An alternative embodiment of the invention formed according to Axial- Schrägwälzlagers it is according to claims 5 and 6, finally, that the adjacent rolling elements of both series pairs are arranged on different, preferably to the longitudinal center axis of the axial angular contact bearing converging pressure angle axes and both pairs of rows of rolling elements in O arrangement are employed against each other. In this embodiment, the rolling elements of both pairs of rows are preferably also performed in a common, designed as a plastic cage cage bearing cage, but each rolling element of the individual rows is each arranged in a separate cage window. By such a design is to be achieved that the tilting stiffness of the axial angular contact bearing is particularly increased and the decisive properties of the bearing, such as accuracy and possible carrying capacity of axial and radial forces, can be tuned even better to higher speeds.

In summary, the axial skew roll Bearing for a rotary table storage thus compared to the known from the prior art rotary table bearings the advantage that it can be equipped by using ball rollers as rolling elements with the same or approximately the same space requirements and without loss of rigidity and accuracy with a much higher number of rolling elements and is thus suitable for very high speeds in continuous operation due to the increased carrying capacity.

Brief description of the drawings

Preferred embodiments of the invention formed according to the invention Axial- Schrägwälzlagers be explained in more detail with reference to the accompanying drawings. Showing:

FIG. 1 shows a cross section through a first embodiment of an axial skew roller bearing designed according to the invention;

FIG. 2 shows a cross section through a second embodiment of an axial skew roller bearing designed according to the invention.

Detailed description of the drawings

From FIGS. 1 and 2, an axial angular contact bearing 1 suitable for rotary table mounting on machine tools, which consists essentially of a two-part inner bearing ring 2 and a one-piece outer bearing ring 3 and of a plurality between the bearing rings 2, 3 in several rows 4, 5, 6, 7 juxtaposed rolling elements 8, 9 is arranged under defined pressure angles with their running surfaces on several side by side on the outer side 10 of the inner bearing ring 2 and on the inner side 11 of the outer race 4 arranged raceways 12, 13, 14, Roll off 15. The unspecified holes in the inner and outer bearing ring serve to screw the Axial- Schrägwälzlagers 1 to the adjacent construction of the machine tool. Furthermore, it can be seen in Figures 1 and 2, that all rolling elements 8, 9 of the axial angular rolling bearing 1 according to the invention as ball rollers with two axially symmetrical flattened from their basic spherical shape, parallel to each other arranged faces are formed to the same or approximately the same space requirements Known rotary table bearing and without loss of rigidity and accuracy to be able to arrange a higher number of rolling elements 8, 9 between the bearing rings 2, 3 of the axial angular rolling bearing 1. Clearly visible, the axial angular contact bearing 1 therefore on the space previously required for two rows of conventional bearing balls four rows 4, 5, 6, 7 designed as ball rolling elements 8, 9, through which its load capacity is significantly increased and by which it also for very high speeds in continuous operation is designed to be suitable. The two inner rows 5, 6 are formed with an identical pitch circle diameter, which is smaller than the likewise identical pitch circle diameter of the two outer rows 4, 7 and at the same time the diameter of the ball basic shape of the rolling elements 8 of the two outer rows 4, 7 is greater as the diameter of the rolling elements 9 of the two inner rows 5, 6.

A peculiarity of the first embodiment shown in Figure 1 of the present invention formed axial angular rolling bearing is that each form an outer row 4, 7 and the adjacently arranged inner row 5, 6, a first and a second row pair 16, 17 and the adjacent rolling elements , 9 of these two pairs of rows 16, 17 are each arranged on a common axis of rotation 18, 19 and on mutually parallel oblique pressure angle axes 20, 21, 22, 23. Both pairs of rows 16, 17 of the rolling elements 8, 9 are set in O arrangement against each other and are each guided in a common, designed as a plastic cage cage bearing cage 24, 25 such that each arranged on a common axis of rotation 18, 19 rolling elements , 9 are arranged in a common cage window and lead one another mutually.

The illustrated in Figure 2 second embodiment of the present invention formed axial bevel bearing 1, however, differs in that the adjacent rolling elements 8, 9 of both rows 16, 17 clearly visible on different, to the longitudinal central axis 26 of the axial Schrägwälzlagers 1 converging pressure angle axes 20, 21, 22, 23 are arranged and both pairs of rows 16, 17 of the rolling elements 8, 9 are also employed in O-arrangement against each other. Also in this embodiment, the rolling elements 8, 9 of both pairs of rows 16, 17 are guided in a common, designed as a plastic cage cage bearing cage 24, 25, but each rolling elements 8, 9 of the individual rows 4, 5, 6, 7 each in its own Cage window is arranged. This embodiment of the axial angular roller bearing 1 is characterized by a greatly increased tilting rigidity and makes it possible to tune the decisive bearing properties even better to higher speeds.

LIST OF REFERENCE NUMBERS

1 axial angular contact bearing

2 inner bearing ring

3 outer bearing ring

4 row

5 series

6 row

7 row

8 rolling elements

9 rolling elements

10 outside of 2

11 inside of 3

12 career

13 career

14 career

15 career

16 pairs of rows

17 pairs of rows

18 rotation axis of 16

19 rotation axis of 17

20 pressure angle axis of 4

21 print angle axis of 5

22 pressure angle axis of 6

23 print angle axis of 7

24 storage cage of 16

25 storage cage of 17

Claims

claims

1. axial oblique rolling bearing (1), in particular for rotary table storage on machine tools, consisting essentially of a one- or zweeili- gen inner bearing ring (2) and an outer bearing ring (3) and a plurality between the bearing rings (2, 3 ) in a plurality of rows (4, 5, 6, 7) arranged side by side rolling elements (8, 9) under defined pressure angles with their running surfaces on several side by side on the outside (10) of the inner bearing ring (2) and on the inside (11 Rolling raceways (12, 13, 14, 15) arranged on the outer bearing ring (4), characterized in that all the rolling elements (8, 9) of the axial angular rolling bearing (1) are designed as ball rollers, each having two axial symmetrical sides having flattened from their basic spherical shape, arranged parallel to each other end faces.

2. axial angular rolling bearing (1) according to claim 1, characterized in that it preferably four rows (4, 5, 6, 7) designed as ball rollers rolling elements (8, 9), of which the two inner rows (5, 6 ) are formed with an identical pitch diameter, which is smaller than the also identical pitch circle diameter of the two outer rows (4, 7).

3. Axial oblique rolling bearing (1) according to claim 2, characterized in that the diameter of the ball basic shape of the rolling bodies (8) of the two outer rows (4, 7) relative to the rolling bodies (9) of the two inner rows (5, 6) is formed larger and each form an outer row (4, 7) and the adjacent inner row (5, 6) form a first and a second row pair (16, 17).

4. Axial oblique rolling bearing (1) according to claim 3, characterized in that the adjacent rolling elements (8, 9) of both pairs of rows (16, 17) each on a common axis of rotation (18, 19) and on mutually parallel oblique Druckwinkelachsen (20 , 21, 22, 23) are arranged and both pairs of rows (16, 17) of the rolling elements (8, 9) are set in O arrangement against each other.

5. Axial oblique rolling bearing (1) according to claim 4, characterized in that the rolling elements (8, 9) of each pair of rows (16, 17) preferably in a common, formed as a plastic cage cage bearing cage (24, 25) are guided and thereby each arranged on a common axis of rotation (18, 19) rolling elements (8, 9) are arranged on one side mutually leader in a common cage window.

6. Axial oblique rolling bearing (1) according to claim 3, characterized in that the adjacent rolling bodies (8, 9) of both series pairs (16, 17) converge on different, preferably to the longitudinal central axis (26) of the axial Schrägwälz- campers (1) extending Druckwinkelachsen (20, 21, 22, 23) are arranged and both pairs of rows (16, 17) of the rolling elements (8, 9) in

O arrangement against each other are employed.

7. Axial oblique rolling bearing (1) according to claim 6, characterized in that the rolling bodies (8, 9) of both pairs of rows (16, 17) preferably in a common, formed as a plastic cage cage bearing cage (24, 25) are guided and thereby the rolling elements (8, 9) of each row (4, 5, 6, 7) are each arranged in a separate cage window.