WO2017202404A1

WO2017202404A1 - Rolling bearing for use with alternating high and low loads

Info

Publication number: WO2017202404A1
Application number: PCT/DE2017/100236
Authority: WO
Inventors: Christoph NEUFELD; Michael Plogmann; Wolfgang Braun; Vasilios Bakolas
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2016-05-25
Filing date: 2017-03-23
Publication date: 2017-11-30
Also published as: DE112017002626A5

Abstract

The invention relates to a rolling bearing (1) with an outer bearing ring (2) and an inner bearing ring (4) disposed coaxially therein, wherein the outer bearing ring (2) comprises an outer ring raceway (3) and the inner bearing ring (4) comprises an inner ring raceway (5), wherein rolling elements (6, 7), which roll along the outer ring raceway (3) and along the inner ring raceway (5), are disposed between the outer bearing ring (2) and the inner bearing ring (4), and in which at least one of the rolling elements (7) has a larger diameter and a lower modulus of elasticity than the other smaller-diameter rolling elements (6). In order to provide such a rolling bearing for use with alternating high and low loads, which has a higher load-carrying capacity than a known rolling bearing, according to a first embodiment comprising a smaller-diameter rolling element (6) consisting of a rolling bearing steel, at least one larger-diameter rolling element (7) consists of a ceramic material or a cemented carbide, or a material produced by powder metallurgy, with a modulus of elasticity between 80 GPa and 120 GPa.

Description

Rolling bearings for applications with varying high and low loads

description

The invention relates to a rolling bearing with a bearing outer ring and a coaxial arranged therein bearing inner ring, the bearing outer ring an outer ring raceway and the bearing inner ring having an inner ring raceway, wherein between the bearing outer ring and the bearing inner ring rolling elements are arranged, which roll on the outer ring raceway and the inner ring raceway, and in which at least one of the rolling elements has a larger diameter and a lower modulus of elasticity than the remaining, smaller-diameter rolling elements.

Such a rolling bearing in the form of a needle bearing is known from DE 2741 057 A1. It is a Nadeliager for moving in steering gears and manual transmissions of motor vehicles. This needle bearing is radially prestressed, in that, according to one embodiment, it is provided with at least one, preferably several, elastically deformable rolling elements distributed over the circumference of the rolling bearing whose diameter is greater than that of the other rolling elements, wherein the elastic deformable rolling elements may consist of plastic or thin-walled, hollow steel bodies. These rolling elements with a larger diameter than the other rolling elements are used to eliminate the bearing play inherent in such roller bearings at low radial load, without biasing the rolling bearing so much that its life is impaired at high radial load. Since plastic is known to have a very low modulus of elasticity in comparison with roller bearing steel, the plastic, elastically deformable rolling elements can be made solid. A disadvantage of this needle roller bearing is that plastic roll and Hohirolien compared to non-hollow rollers and rollers made of a metallic material have only a low load capacity. Therefore, such roles contribute little to the overall load capacity of the bearing. DE 695 18 488 T2 describes a rolling bearing whose rolling elements consist of a part of conventional bearing steel with a modulus of elasticity of 210 GPa and to a further part of a material having a modulus of elasticity greater than 280 GPa. The rolling elements with the higher modulus of elasticity can consist of a technical ceramic material such as silicon nitride, including sialons, silicon carbide and alumina or cermets, such as sintered hard metals. These Wälzköper should all have the same diameter and are not intended to give the roller bearing an internal bias, but to compress the protruding parts when rolling over depressions in the rolling bearing rings, thereby avoiding early fatigue and cracking of the bearing and stronger vibration and a loud run of the bearing should not arise.

Against this background, the invention has the object, a rolling bearing for applications with changing, very high loads and very low loads, for example, for rolling bearings in wind turbines or Biegeeinstellwalzen in paper machines, imagine that with a radial bias at very low - Run loads loads by the Wälzkörperschlupf is reduced in the rolling bearing. In addition, in the case of high bearing load, all rolling elements should largely share in the load bearing capacity of the rolling bearing to a large extent.

This problem is solved by a rolling bearing having the features of claim 1. Accordingly, the rolling bearing has a bearing outer ring and a bearing inner ring arranged coaxially therein, wherein the bearing outer ring has an outer ring raceway and the bearing inner ring has an inner ring raceway. Rolling elements are arranged between the bearing outer ring and the bearing inner ring, which roll on the outer ring raceway and the inner ring raceway. At least one of the rolling elements has a larger diameter and a lower modulus of elasticity than the other, diameter-reduced rolling elements. The smaller-diameter rolling elements consist of a rolling bearing steel. In this rolling bearing is provided according to the invention that the at least one, larger diameter rolling elements of a ceramic material or a cemented carbide sintered or from a powder metallurgy produced material having a modulus of elasticity between 80 GPa and 120 GPa. The stated object is also achieved by a rolling bearing with the features of claim 2, wherein the at least one, larger diameter rolling elements consists of a rolling bearing steel. Accordingly, the object is also achieved by a rolling bearing with a bearing outer ring and with a coaxially arranged therein La * gerinnenring, the bearing outer ring an outer ring raceway and the bearing inner ring have an inner ring raceway, wherein between the bearing outer ring and the bearing inner ring rolling elements are arranged, soft on the Rolling outer ring raceway and the inner ring raceway, and in which at least one of the rolling elements has a larger diameter and a lower modulus of elasticity than the other, smaller-diameter rolling elements. In this rolling bearing, it is provided that the at least one larger diameter Wäizkörper consists of a Wälzlager- steel, and that the remaining, diameter-serially rolling elements consist of a ceramic material or a cemented carbide sintered with a modulus of more than 230 GPa.

In the case of the two rolling bearings mentioned, it is preferably provided that the diameter and the modulus of elasticity of the at least one rolling element of larger diameter are selected so that a bearing preload is applied during operation with low loads, which reduces or reduces the slip of the relatively small rolling elements in the rolling bearing completely eliminated by the at least one, larger-diameter rolling elements driving the Wälzkörper- set formed by all rolling elements in the rolling bearing and keeps at kinematic speed, and that the diameter, the modulus of elasticity and the profiling of at least one, larger diameter rolling elements are coordinated so that no overloading and premature fatigue of the at least one diameter larger rolling element occurs even at high loads occurring.

Accordingly, the invention proposes to reduce the slip in the rolling bearing by a bearing preload, for the production of which a combination of different rolling element diameter and rolling element materials with high strength is used. This technical solution means that a maximum high bearing capacity of the rolling bearing is achieved when the rolling bearing is exposed to very high loads. at At low loads, the larger diameter rolling elements drive the smaller diameter rolling elements.

A particular advantage of the invention is the fact that it can be applied to all bearing types, in particular cylindrical roller bearings, spherical roller bearings and ball bearings. In addition, in principle, all types of rolling elements can be manufactured from solid materials, so that similar finishing processes can be used as with conventional rolling bearings. In a further development of the invention, it is preferably provided that all rolling elements of the rolling bearing are accommodated in a common cage. Oer cage transmits at low bearing load, ie at non-load-bearing smaller diameter Wälz- bodies, the Umiaufbewegung the larger diameter rolling elements in the rolling bearing on the smaller diameter rolling elements and keeps them on the resulting speed.

In this case, it is preferably provided that the diameter and the modulus of elasticity of the at least one, larger-diameter rolling elements are selected so that in operation with low loads a bearing preload is given, which reduces the slip of the smaller-diameter rolling elements in the rolling bearing or completely eliminated by the at least a larger diameter rolling elements drives the rolling element formed by all rolling elements in the rolling bearing and keeps it at kinematic speed. In addition, it is provided that the diameter, the modulus of elasticity and the profiling of the at least one diameter-larger rolling element are coordinated so that no overloading and premature fatigue of the at least one diameter-larger rolling element occurs even at high loads occurring. The high strength of the rolling element material used contributes significantly to this. With regard to the materials used, it is preferably provided that the rolling bearing steel has a modulus of elasticity of 200 GPa to 230 GPa. The rolling elements of a bearing steel are preferably made of a steel from the group of Steels 100Cr6, St4, 100CrMnSi6-4, M50, 32CrMoV13, Cronidur®, Cronitec® and case hardening steels.

Further, it is preferably provided that the at least one, larger-diameter rolling elements made of a nickel-titanium alloy, if the smaller-diameter rolling elements consist of a bearing steel. Here, the nickel-titanium alloy NiTi60 is of particular advantage. Such a nickel-titanium alloy has a modulus of elasticity of 80 GPa to 120 GPa. Finally, it is preferably provided that the at least one, larger-diameter rolling elements have a profiling to prevent Kantentra- gene with greater deformation.

By using the at least one, larger-diameter rolling element, which has a lower modulus of elasticity than the other, smaller-diameter rolling elements, the bias of the bearing can be adjusted so that no external load on the rolling bearing whose rolling element has no or only a small Wälzkörpersatzschlupf. There is also the possibility to arrange not only a larger diameter rolling elements with a larger diameter in the rolling bearing, but also rolling bearings can be made with several larger diameter rolling elements evenly spaced by, for example, two, three, four, five or six larger diameter rolling elements are arranged between the rolling elements of normal diameter in the rolling bearing.

Since all rolling elements in the rolling bearing according to the invention consist of Voilmaterial, the processing costs of the components are lower compared to pierced rolling elements.

The invention will be explained in more detail below with reference to an exemplary embodiment shown in the attached drawing. The single drawing figure shows a schematic side view of a rolling bearing according to the invention. The roller bearing 1 shown by way of example is a ball bearing which has a bearing outer ring 2 with an outer ring raceway 3 and a bearing inner ring 4 with an inner ring raceway 5. Radially between the two mentioned bearing rings 2, 4 twelve rolling elements 6, 7 are arranged in the illustrated embodiment, which roll on the raceways 3, 5 of the bearing rings 2, 4. The twelve rolling bodies 6, 7 are accommodated in a common cage 8. Of the twelve rolling elements, eight rolling elements 6 have a conventional ball bearing diameter and a common bearing clearance. Four further rolling elements 7 obviously have a slightly larger diameter. They are arranged uniformly distributed between the smaller diameter rolling elements 6, such that in each case two smaller-diameter rolling elements 6 are arranged between each two larger-diameter rolling elements 7. Since the larger-diameter rolling elements 7 have a slightly larger diameter than the other rolling elements 6, they generate a radial prestress in the rolling bearing 1. This bias causes the Wälzkörpersatz formed from all rolling elements 6, 7 without external load on the rolling bearing 1 has no or only a small Wälzkörpersatzschlupf. If a ceramic material or cemented carbide is selected for the material of the eight rolling elements 6 with the usual diameter and the usual bearing play, the larger diameter rolling elements 7 can consist of a bearing steel, for example of the bearing steel 100Cr6. Since this bearing steel has a modulus of elasticity of about 210 GPa and the ceramic material or sintered cemented carbide material has a modulus of elasticity of at least 230 GPa, the larger diameter rolling elements 7 deform at a load bearing so that then also the smaller diameter rolling elements 6 come into play , in contrast to the known from DE 27 41 057 A1 needle roller bearings then bear all rolling elements 6, 7 with largely the same proportion acting on the bearing 1 load. In the unloaded state of the rolling bearing 1, no slip of the rolling element set can occur.

If the smaller diameter rolling elements 6, ie those with the usual diameter and the usual bearing clearance, from a bearing steel, for example bearing steel 100Cr6, can be used for the larger diameter rolling elements? a metal alloy or a powder metallurgically produced material having a lower modulus of elasticity than that of bearing steel can be used. The pulp metallurgically produced material for the larger-diameter rolling bodies 7 may be the nickel-titanium alloy ΝΊΤΊ60, which may have a modulus of elasticity of 80 GPa to 120 GPa.

In both cases, the diameter of the larger diameter rolling elements 7 can be chosen so that in operation with low loads a bearing preload is given, which reduces the slip of the smaller diameter rolling elements 6 in the rolling bearing 1 or completely eliminated by the larger diameter rolling elements 7 by all rolling elements , 7 Rolling body set formed in the rolling bearing 1 on the cage 8 antreib- and keep it at kinematic speed. Even with the highest occurring loads, the proposed structure will not cause any overloading and premature fatigue of the larger diameter rolling elements 7, because these consist of a high-strength material and at the same time enable a high bearing capacity of the entire rolling bearing. Since the larger-diameter rolling bodies 7 neither consist of a plastic nor are formed as hollow bodies, they too, like the smaller-diameter rolling bodies 6, carry the load acting on the roller bearing 1 with at least substantially equal proportion.

At least the larger diameter rolling elements 7 may have suitable profiling to prevent edge bearing thereof at high deformation, thereby avoiding overloading of the larger diameter rolling elements 7 even at the highest occurring loads with associated premature fatigue.

All the features mentioned in the preceding description of the figures, in the claims and in the introduction to the description can be used both individually and in any combination with one another. The invention is thus not limited to the described and claimed combinations of features, but all Merkmaiskombinationen be regarded as disclosed. LIST OF REFERENCE NUMBERS

1 rolling bearing

2 bearing outer ring

3 outer ring raceway

4 bearing inner ring

5 inner ring raceway

6 rolling elements with a common diameter and bearing clearance

7 rolling elements with a larger diameter and under radial prestressing

8 cage

Claims

claims

1. rolling bearing (1), with a bearing outer ring (2) and with a coaxially arranged therein bearing inner ring (4), wherein the bearing outer ring (2) an outer raceway (3) and the bearing inner ring (4) an inner ring eggufbahn (5) Autweisen, between the bearing outer ring (2) and the bearing inner ring (4) Wharf body (6, 7) are arranged, soft on the outer ring raceway (3) and the Innenringiaufbahn (5) roll, at least one of the rolling elements (7) has a larger diameter - These and a lower modulus of elasticity than the other, smaller-diameter rolling elements (6), and in which the smaller diameter rolling elements (6) consist of a bearing steel, characterized in that the at least one, larger diameter rolling elements (7) made of a ceramic Material or a sintered Hartmetali or from a puivermetaiiurgisch produced material having a modulus of elasticity between 80 GPa and 120 GPa.

2. rolling bearing (1), with a bearing outer ring (2) and with a coaxially arranged therein bearing inner ring (4), wherein the bearing outer ring (2) an outer raceway (3) and the bearing inner ring (4) an inner ring raceway (5) have, between the bearing outer ring (2) and the bearing inner ring (4) rolling elements (6, 7) are arranged, which roll on the outer ring raceway (3) and the Innenringiaufbahn (5), and at least one of the Wäizkörper (7) a larger diameter and a lower modulus of elasticity than the other, smaller-diameter rolling elements (6), characterized in that the at least one, larger diameter rolling elements (7) consists of a Wäizlagerstahi, and that the remaining, smaller-diameter rolling elements (6) of a ceramic - Consist of material or a cemented carbide with a modulus of elasticity of more than 230 GPA.

3. Rolling bearing according to claim 1 or 2, characterized in that all Wälzkör- by (6, 7) in a cage (8) of the rolling bearing (1) are accommodated.

4. rolling bearing according to claim 1 to 3, characterized in that the diameter and the modulus of elasticity of the at least one, larger diameter Wälzlager body (7) are selected such that, during operation with low loads, a bearing preload is provided which reduces or completely eliminates the slippage of the relatively small Wäfzkör- (6) in the rolling bearing (1) by at least one, larger-diameter rolling elements ( 7) drives the Wälzkörpersatz formed by all rolling elements (6, 7) in the rolling bearing (1) and keeps at kinematic speed, and that the diameter, the modulus of elasticity and the profiling of the at least one larger diameter rolling element (7) are coordinated with each other so that no overloading and premature fatigue of the at least one diameter-larger rolling body (7) occurs even at high loads occurring.

5. Rolling bearing according to one of claims 1 to 4, characterized in that the used bearing steel has a modulus of elasticity of 200 GPa to 230 GPa.

6. Rolling bearing according to one of claims 1 to 5, with smaller diameter Wälzkör- pern (6) from a Wäizlagerstahl, characterized in that the at least one, larger-diameter rolling elements (7) consists of a nickel-titanium alloy.

7. Rolling bearing according to claim 6, characterized in that the at least one, larger diameter rolling elements (7) consists of the nickel-titanium alloy NiTi60.

8. Rolling bearing according to one of claims 1 to 7, characterized in that the bearing steel is a steel from the group of steels 100Cr6, StA 100CrMnSi6-4, M50, 32CrMoV13, Cronidur®, Cronitec® and the case-hardened steels.

9. Rolling bearing according to one of claims 4 to 8, characterized in that the at least one, larger-diameter rolling elements (7) has a profiling to prevent the edge wear at greater deformation.