TAPERED ROLLER BEARING

Abstract

A tapered roller bearing (1) is provided including an inner ring (2) having an inner ring raceway (3), an outer ring (4) having an outer ring raceway (5), and tapered rollers (6) rolling on the raceways (3, 5). This tapered roller bearing (1) is characterized in that the nominal contact angle (a) thereof is between 20°-30°, and the tapered rollers (6) have a ratio of rolling element length (L) to rolling element diameter (Dw) of 1.0-1.2.

Claims

1. A tapered roller bearing, comprising: an inner ring with an inner ring raceway; an outer ring with an outer ring raceway; and tapered rollers rolling on the raceways; wherein a nominal contact angle is between 20°-30° and the tapered rollers have a ratio of rolling element length to rolling element diameter of 1.0-1.2.

2. The tapered roller bearing according to claim 1, wherein the nominal contact angle is between 22° and 28°.

3. The tapered roller bearing according to claim 2, wherein the nominal contact angle is 25°.

4. The tapered roller bearing according to claim 1, wherein the ratio of the rolling element length to the rolling element diameter is 1.02-1.1.

5. The tapered roller bearing according to claim 4, wherein the ratio of the rolling element length to the rolling element diameter is 1.04.

6. The tapered roller bearing according to claim 1, wherein at least one of the inner and outer ring raceways or the tapered rollers are provided with a wear protection coating.

7. The tapered roller bearing according to claim 6, wherein the wear protection coating is carbon and hydrogen based.

8. The tapered roller bearing according to claim 1, further comprising one or more bores on at least one of the inner or the outer ring configured to allow lubricant entry into a rolling area.

9. A tool spindle arrangement comprising: a tool spindle; a housing; and several of the tapered roller bearings according to claim 1 supporting the tool spindle in the housing.

10. The tool spindle arrangement according to claim 9, wherein the tool spindle is only supported in the housing via two axially spaced-apart ones of the tapered roller bearings.

11. The tapered roller bearing according to claim 7, wherein the wear protection coating includes integrated nanoparticles formed of a nitride, boride, carbide, or silicide.

12. The tapered roller bearing according to claim 8, wherein the bores are located on a rim of the inner or outer ring.

13. A tapered roller bearing, comprising: an inner ring with an inner ring raceway; an outer ring with an outer ring raceway; tapered rollers rolling on the raceways; and a cage that retains the tapered rollers wherein a nominal contact angle is between 20°-30° and the tapered rollers have a ratio of rolling element length to rolling element diameter of 1.0-1.2.

14. The tapered roller bearing according to claim 13, further comprising one or more bores on at least one of the inner or the outer ring configured to allow lubricant entry into a rolling area.

15. The tapered roller bearing according to claim 14, wherein the bores are located on a rim of the inner or outer ring.

16. A tool spindle arrangement comprising: a tool spindle; a housing; and several of the tapered roller bearings according to claim 13 supporting the tool spindle in the housing.

17. The tool spindle arrangement according to claim 16, wherein the tool spindle is only supported in the housing via two axially spaced-apart ones of the tapered roller bearings.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The disclosure is explained below on the basis of exemplary embodiments with reference to the drawings. The drawings are schematic representations, wherein:

[0022] FIG. 1 is a schematic diagram, in section, of a tapered roller bearing according to the disclosure,

[0023] FIG. 2 is a basic illustration of a tool spindle arrangement according to the disclosure, and

[0024] FIG. 3 is a tool spindle arrangement according to the prior art.

DETAILED DESCRIPTION

[0025] FIG. 1 shows a tapered roller bearing 1 according to the disclosure in a sectional view. The tapered roller bearing 1 comprises an inner ring 2 with an inner ring raceway 3 and an outer ring 4 with an outer ring raceway 5. Tapered rollers 6, which are guided in a cage 7, roll on the raceways 3, 5. The tapered rollers 6 are guided over two rims 8, 9 formed on the inner ring 2.

[0026] The two raceways 3, 5 are each provided with a wear protection coating 10, 11, which at the same time has friction-reducing properties. For this purpose, for example, a wear protection coating, as described in DE 10 2006 029 415 A1 or used by the applicant under the brand name “TriondurC+” or “TriondurCX+”, can be used.

[0027] The tapered rollers 6 have a specific geometry in terms of the ratio of rolling element length Lw to rolling element diameter at the thick roller end Dw. FIG. 1, on the one hand, shows the rolling element length Lw, which is defined by the thin and thick roller end face. The rolling element diameter Dw is determined at the position of the thick end of the roller. The ratio of Lw/Dw is 1.0-1.1, preferably 1.02-1.1 and in particular 1.04. This means that the rolling element length Lw is approximately equal to the rolling element diameter Dw; a ratio as close as possible to 1.0 is preferred.

[0028] In addition, a specific nominal contact angle α is provided, which is between 20°-30°. The nominal contact angle is preferably between 22°-28°, in particular between 24°-26° and in particular 25°.

[0029] An extremely high axial and radial rigidity is formed via the nominal contact angle α, if necessary in conjunction with a corresponding bias of the tapered roller bearing 1. By choosing the ratio Lw/Dw provided according to the disclosure, the rolling friction or the overall friction of the tapered roller bearing 1 is greatly reduced, with the wear protection coatings 10, 11 being additionally conducive to this reduction in friction. Overall, the result is a high load-bearing, axially and radially very rigid, tapered roller bearing with a very low surface pressure resulting from the ratio Lw/Dw, which is insensitive to load and speed and has very low friction compared with previously known tapered roller bearings. Therefore, the tapered roller bearing according to the disclosure is suitable for use in high-speed bearing applications.

[0030] As is also shown by the dashed lines in FIG. 1, one or more bores 19 which allow lubricant to enter the rolling area can be provided, which bores are preferably formed on a rim 8, 9. Via these bores 19, lubricant can directly enter the rolling area and in particular the rim area where the end faces of the tapered rollers 6 run against the respective rim 8, 9.

[0031] Such a high-speed bearing arrangement according to the disclosure in the form of a tool spindle arrangement 12 according to the disclosure is shown in FIG. 2. A tool spindle 13 is shown, which is supported in a housing 14, which is only suggested here, by two tapered roller bearings 1 according to the disclosure, which are positioned here in an O-arrangement. Due to the properties described above, in particular with regard to the high load rating, the high radial and axial rigidity and the relatively low friction, it is possible to mount such a tool spindle 13 with only two tapered roller bearings 1 instead of providing several angular contact ball bearings as was previously the case.

[0032] An example of such a tool spindle arrangement according to the prior art is shown in FIG. 3. The tool spindle arrangement 15 shown there also has a tool spindle 16 which is mounted in a housing 17, wherein four angular contact ball bearings 18 are used, which are installed in a tandem-O-tandem arrangement. Two angular contact ball bearings 18 each form a pair, that is, a tandem, the angular contact ball bearings 18 being arranged identically within the pair by the arrangement of the contact angle, but the two pairs are positioned in an O arrangement. Since with such a spindle bearing, which requires four angular contact ball bearings 18, due to the large number of angular contact ball bearings 18, there is a considerable reduction in the speed limit, the use of only two tapered roller bearings according to the disclosure instead of four (or more) angular contact ball bearings is of particular advantage, since with fewer components, namely only two tapered roller bearings, comparable or even better bearing properties can be achieved.

LIST OF REFERENCE SYMBOLS

[0033] 1 Tapered roller bearing [0034] 2 Inner ring [0035] 3 Inner carrier [0036] 4 Outer ring [0037] 5 Outer ring raceway [0038] 6 Tapered rollers [0039] 7 Cage [0040] 8 Rim [0041] 9 Rim [0042] 10 Wear protection coating [0043] 11 Wear protection coating [0044] 12 Tool spindle arrangement [0045] 13 Tool spindle [0046] 14 Housing [0047] 15 Tool spindle arrangement [0048] 16 Tool spindle [0049] 17 Housing [0050] 18 Angular contact ball bearings [0051] 19 Bore