Rolling-element bearing assembly

Abstract

A rolling-element bearing assembly includes a rolling-element bearing and an oil conditioning system for conditioning oil used to lubricate the bearing. The bearing has an inner ring and an outer ring and a plurality of rolling elements rotatably disposed between the inner ring and the outer ring. The bearing includes openings for discharging oil from the bearing and for introducing oil into the bearing, and the openings are connected to the oil conditioning system. A raceway of the inner ring and/or a raceway of the outer ring is coated with a first coating, and the rolling elements are at least partially coated with a second coating that is different from the first coating.

Claims

1. A rolling-element bearing assembly comprising: a rolling-element bearing having an inner ring and an outer ring and a plurality of rolling elements rotatably disposed between the inner ring and the outer ring, the rolling elements being configured to be lubricated with an oil, and an oil conditioning system, wherein the rolling-element bearing includes at least one opening for discharging oil from the rolling-element bearing and at least one opening for introducing oil into the rolling-element bearing, wherein the at least one opening for introducing oil into the rolling-element bearing is configured as at least one inlet bore in the outer ring, wherein the at least one opening for discharging oil from the rolling-element bearing and the at least one opening for introducing oil into the rolling-element bearing are connected to the oil conditioning system, wherein a raceway of the inner ring and/or a raceway of the outer ring is coated with a first coating and the rolling elements are at least partially coated with a second coating, and wherein the first coating is a phosphate coating and the second coating is a bluing, the bluing has a greater hardness than the phosphate coating.

2. The rolling-element bearing assembly according to claim 1, wherein the at least one opening for introducing oil into the rolling-element bearing and the at least one opening for discharging oil from the rolling-element bearing are axially offset with respect to each other.

3. The rolling-element bearing assembly according to claim 1, wherein the first coating is a coating selected from the group consisting of: a manganese phosphate coating, a zinc phosphate coating, a zinc calcium phosphate coating, and a tricationic phosphate coating.

4. The rolling-element bearing assembly according to claim 1, wherein the rolling elements are completely coated with the second coating, and/or wherein the raceway of the inner ring and/or the raceway of the outer ring are completely coated with the first coating.

5. The rolling-element bearing assembly according to claim 1, wherein the rolling-element bearing includes a seal carrier disposed on the outer ring and including two radial seals and/or an axial seal.

6. The rolling-element bearing assembly according to claim 5, wherein the seal carrier includes a circumferential groove.

7. The rolling-element bearing assembly according to claim 6, wherein the seal carrier includes a bore that extends radially starting from the groove.

8. The rolling-element bearing assembly according to claim 1, wherein the rolling-element bearing is a four-row cylindrical tapered-roller bearing.

9. The rolling-element bearing assembly according to claim 1, wherein the first coating is a manganese phosphate coating, a zinc phosphate coating, a zinc calcium phosphate coating, or a tricationic phosphate coating, wherein the rolling elements are completely coated with the second coating and the raceway of the inner ring and the raceway of the outer ring are completely coated with the first coating, wherein the rolling-element bearing includes a seal carrier having a circumferential groove disposed on the outer ring and including two radial seals and an axial seal, and wherein the seal carrier includes a bore that extends radially starting from the groove.

10. A roll stand comprising: at least one work roll supported by a rolling-element bearing assembly according to claim 1.

11. A rolling-element bearing assembly comprising: a rolling-element bearing having an inner ring and an outer ring and a plurality of rolling elements rotatably disposed between the inner ring and the outer ring, the rolling elements being configured to be lubricated with an oil, and an oil conditioning system, wherein the rolling-element bearing includes openings for discharging oil from the rolling-element bearing and introducing oil into the rolling-element bearing, wherein the openings are connected to the oil conditioning system, wherein a raceway of the inner ring and/or a raceway of the outer ring is coated with a first coating and the rolling elements are at least partially coated with a second coating, and wherein the first coating is different from the second coating, wherein the first coating or the second coating is a phosphate coating, wherein the first coating is the phosphate coating, and wherein the second coating has a greater hardness than the first coating, and wherein the second coating is a black oxide coating.

12. A rolling-element bearing assembly comprising: a rolling-element bearing having an inner ring and an outer ring and a plurality of rolling elements rotatably disposed between the inner ring and the outer ring, the rolling elements being configured to be lubricated with an oil, and an oil conditioning system, wherein the rolling-element bearing includes at least one opening for discharging oil from the rolling-element bearing and at least one opening for introducing oil into the rolling-element bearing, wherein the at least one opening for discharging oil from the rolling-element bearing and the at least one opening for introducing oil into the rolling-element bearing are connected to the oil conditioning system, wherein a raceway of the inner ring and/or a raceway of the outer ring is coated with a first coating and the rolling elements are at least partially coated with a second coating, wherein the first coating is a phosphate coating selected from the group consisting of a manganese phosphate coating, a zinc phosphate coating, a zinc calcium phosphate coating, and a tricationic phosphate coating, and wherein the second coating is a black oxide coating or a bluing.

13. The rolling-element bearing assembly according to claim 12, wherein the second coating is the bluing.

14. The rolling-element bearing assembly according to claim 12, wherein the rolling elements are completely coated with the second coating, and/or wherein the raceway of the inner ring and/or the raceway of the outer ring are completely coated with the first coating.

15. The rolling-element bearing assembly according to claim 12, wherein the rolling-element bearing includes a seal carrier disposed on the outer ring and including two radial seals and/or an axial seal.

16. The rolling-element bearing assembly according to claim 15, wherein the seal carrier includes a circumferential groove.

17. A roll stand comprising: at least one work roll supported by a rolling-element bearing assembly according to claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a sectional view of a rolling-element bearing including an inner ring and an outer ring according to an embodiment of the invention.

(2) FIG. 2 is a sectional view of a four-row cylindrical roller bearing including an oil conditioning system.

(3) FIG. 3 is a sectional view of a cylindrical roller bearing including an inner ring and an outer ring and seals.

DETAILED DESCRIPTION

(4) In the following, identical or functionally equivalent elements are designated by the same reference numbers.

(5) In FIG. 1 a rolling-element bearing 2 is depicted in a greatly simplified outline. The rolling-element bearing 2 includes an inner ring 3 and an outer ring 4. Rolling elements 6 are rotatably disposed between the two rings 3, 4. Here the rolling elements 6 run against an outer surface 8 of the inner ring 3 as well as an inner surface 10 of the outer ring 4. In order to protect the raceways 8, 10 as well as the rolling elements 6 against wear, these are each provided with a coating. Here the coating of the rolling elements 6 can have a greater hardness than a coating of the raceways 8, 10. The coating of the rolling elements 6 can be, for example, a bluing.

(6) The ring raceways 8, 10, and preferably the entire rings 3, 4 are provided with a phosphate coating in order to provide a sliding layer for the rolling elements 6. In particular, a smearing of the rolling elements 6 can be prevented by the coating of the rolling elements 6.

(7) Here both the phosphate coating and the coating of the rolling elements 6 can be configured so thin that even with wear of the coatings the bearing clearance in the rolling-element bearing is increased only in an acceptable range. Since the coating of the rolling elements 6 is harder than the phosphate coating, the coating of the rolling elements 6 is preferably not worn and thus remains even with a reduced thickness of the phosphate coating as a separating layer between the rolling elements 6 and the raceways 8, 10.

(8) Furthermore, a bluing is preferably provided for the rolling elements 6, since this can be applied very thinly. In comparison thereto the phosphate coating is thicker. If the phosphate coating were to be applied onto the rolling elements 6, with a reduction of the thickness of the phosphate coating (which occurs very quickly due to the softness of the phosphate coating in operation) the layer thickness of the rolling elements 6 would be reduced and a clearance would be present between the rolling elements 6. In order to prevent the phosphate coating from rapidly losing layer thickness in operation, which would unacceptably increase the bearing clearance, the phosphate coating may not be applied to all components. Phosphate on rings and rollers would generate too large a clearance change. The phosphate coating is therefore preferably applied only onto the rings since the essential effects of phosphate, inter alia corrosion protection and prevention of fretting corrosion, are predominantly required on the rings. The rollers are therefore provided with a thin and dimensionally stable layer, preferably a bluing. In this way the coatings of the rollers do not additionally contribute to the phosphate-typical clearance enlargement.

(9) The rolling-element bearing 2 can be used in a rolling-element bearing assembly 1 as is described in FIG. 2. The rolling-element bearing assembly 1 includes a four-row cylindrical roller bearing 2, which includes the coatings described in connection with FIG. 1. Here the cylindrical roller bearing 2 is comprised of two one-part inner rings 3 and two one-part outer rings 4, between which an intermediate ring 40 is disposed. The cylindrical roller bearing 2 can be pushed onto a shaft journal 12 that rotates about an axis of rotation 14.

(10) In order to minimize the damage to the surfaces of the cylindrical roller bearing 2, according to FIG. 2 an oil conditioning system 36 is provided. In this oil conditioning system oil, which is discharged from the cylindrical roller bearing 2, can be conditioned by removing air and water from the oil. The conditioned oil can then be fed back to the cylindrical roller bearing 2 via a pump 38.

(11) In order to discharge the oil from the cylindrical roller bearing 2, outlet openings 42, 46 are provided in the cylindrical roller bearing 2. The outlet openings 42 are provided in the intermediate ring 40 as radial bores. Alternatively the outlet openings 42 can also be provided directly in the outer ring 4. Through these outlet openings 42 as well as the outlet openings 46, which are provided on the axial ends of the cylindrical roller bearing 2, the oil is discharged in a substantially pressure-free manner by gravity and transmitted to the oil conditioning system 36.

(12) After conditioning the oil is supplied again to the cylindrical roller bearing 2 via the pump 38 through inlet openings 44 that are provided in the outer ring 4. The inlet openings 44 and the outlet openings 42 can be axially offset with respect to one another.

(13) The outlet openings 42 and the inlet openings 44 are distributed circumferentially about the intermediate ring 40 or the outer ring 4, so that the orientation of the cylindrical roller bearing 2 can be ignored when installing into a housing.

(14) As shown in FIG. 2, the oil in the cylindrical roller bearing 2 covers at east half a cylindrical roller 6 (minimum fill level 50) during stoppage. With the maximum fill level 48 a complete cylindrical roller 6 is covered during stoppage.

(15) In order to further reduce possible damage to the cylindrical roller bearing 2, in addition to the above-described coating as well as the oil conditioning, seals are provided in the rolling-element bearing assembly or cylindrical roller bearing assembly 2 that are described in the following in more detail with reference to FIG. 3.

(16) The cylindrical roller bearing 2 can be clamped onto a shaft journal 12 using a sleeve 16 that is disposed on the inner ring 3. A seal carrier 18 is disposed on the outer ring 4. This can be comprised of a plurality of elements that are attached to one another.

(17) Two radial seals 20, 22 are disposed between the sleeve 16 and the seal carrier 18. Due to these radial seals 20, 22 the cylindrical roller bearing 2 can be sealed both from the outside inward and from the inside outward.

(18) In addition, an axial seal 24 is provided that can be configured as a labyrinth seal. Due to the axial seal 24, the cylindrical roller bearing 24 can additionally be protected against the entry of water.

(19) If water nonetheless enters into the cylindrical roller bearing 2 through the seals 20, 22, 24, circumferential grooves 26, 28, 30 are provided on the seal carrier 18. Through these grooves 26, 28, 30 water can be collected independently of the position of the seal carrier 18. In order to be able to drain the collected water, the grooves 26, 28, 30 are provided with radial bores 32, 34. Through the radial bores 32, 34 the water can be drained outward.

(20) Due to the disclosed rolling-element bearing assembly it is possible to provide a rolling-element bearing that can reduce wear of the rolling-element bearing by the combination of different protective mechanisms under the most different conditions of use, for example even in an acidic or alkaline environment. On the one hand the rolling elements and raceways include a coating that offers protection even in an acidic or alkaline environment since at least one of the layers used remains and thus a protective layer remains between the surfaces of the bearing rings and of the rolling elements, which surfaces are moving against each other. Furthermore, due to the two different coatings the running properties of the rolling-element bearing can be improved since the advantages of both coatings can be utilized. In addition, the negative influencing of the surfaces of the rolling-element bearing is reduced since an oil conditioning system is connected to the rolling-element bearing in order to reduce the water proportion in the oil. In further designs a seal system can additionally reduce the penetrating of water into the rolling-element bearing.

(21) Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved rolling-element bearing assemblies.

(22) Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

(23) All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

REFERENCE NUMBER LIST

(24) 1 Rolling-element bearing assembly

(25) 2 Rolling-element bearing

(26) 3 Inner ring

(27) 4 Outer ring

(28) 6 Rolling element

(29) 8 Raceway

(30) 10 Raceway

(31) 12 Shaft journal

(32) 14 Axis of rotation

(33) 16 Sleeve

(34) 18 Seal carrier

(35) 20 Radial seal

(36) 22 Radial seal

(37) 24 Axial seal

(38) 26 Groove

(39) 28 Groove

(40) 30 Groove

(41) 32 Radial bore

(42) 34 Radial bore

(43) 36 Oil conditioning system

(44) 38 Pump

(45) 40 Intermediate ring

(46) 42 Outlet opening

(47) 44 Inlet opening

(48) 46 Outlet opening

(49) 48 Maximum oil fill level

(50) 50 Minimum oil fill level