rolling bearings

Abstract

Rolling bearings with a first bearing ring (2) and a second bearing ring (3) rotatable relative to the first bearing ring (2) about an axis of rotation (A) of the rolling bearing (1), and with at least three rows of rolling elements (4, 5, 6) arranged to roll between the bearing rings (2, 3), wherein the first bearing ring (2) has a radially projecting, circumferential lug (7) and the second bearing ring (3) comprises a support ring (8) and a retaining ring (9) which engage the lug (7) of the first bearing ring (2) including the rows of rolling elements (4, 5, 6) between the two bearing rings (2, 3), wherein the lug (7) has an axial side surface (10) facing the support ring (8) as a first raceway for an axially acting first row of rolling elements (4) of the rows of rolling elements (4, 5, 6), wherein on one of the axial side surfaces (10) opposite side (11) of the nose (7) a circumferential, tooth-like projection (12) in the axial direction is formed,the bearing has two converging flanks (13, 14), each designed as a raceway for a second and third row of rolling elements (5, 6) of the rows of rolling elements (4, 5, 6), and the tooth-like projection (12) engages axially in a circumferential, groove-shaped recess (15) of the retaining ring (9), including the second and third rows of rolling elements (5, 6), and wherein the rolling bearing (1) has exactly three rows of rolling elements (4, 5, 6).

Description

State of the art

[0001] The invention relates to a rolling bearing according to claim 1.

[0002] Rolling bearings are used to transmit forces and / or moments in slewing rings. The choice of bearing type depends on the expected load cases. For example, there are rolling bearing types that can only absorb radial or axial forces, as well as rolling bearing types – such as the double tapered roller bearing – that can absorb both radial and axial forces, as well as tilting moments.

[0003] For particularly large loads and tilting moments, the three-row roller slewing ring type of rolling bearing has become established, as described, for example, in US Pat. No. 3,652,141 A. In three-row roller slewing rings, the main axial loads are absorbed by a row of axially acting support rollers. Another row of axially acting rollers, the retaining roller row, absorbs axial loads in the opposite direction. A third row of rolling elements consists of radial rollers, which transmit the radial forces acting between the two bearing rings. The three rows of rollers are enclosed between three sides of a radially projecting nose of the first bearing ring and the second bearing ring, which encloses the nose on three sides.

[0004] Deformations of the bearing rings, which occur due to high radial loads and can cause the bearing rings to move apart in the radial direction, are limited in the known three-row roller slewing ring solely by the inherent rigidity of the ring materials used and the supporting effect of the connecting structures to which the bearing rings are attached. However, it has been found that with large diameters of slewing bearings and / or in extreme load situations, radial deformations can still occur between the first and second bearing rings. This leads to such a large widening of the bearing gap between the bearing rings that the axial rollers can at least partially leave their respective assigned raceways on the bearing rings. In such a case, very high pressures occur at the raceway edges between the respective rolling element and the raceway, which can lead to damage to the raceway and / or the rolling element.

[0005] To limit the radial deformation of the bearing rings relative to each other, DE 20 2006 020 464 U1 discloses a roller bearing that has a total of four opposing pairs of rolling bearing rows, two of which surround the nose ring in the axial direction and two in the radial direction, guiding it during rotation. The additional radial roller bearing can absorb additional loads in the radial direction and prevents or reduces deformation of the nose ring. Disadvantages include the high production costs incurred for the creation of an additional raceway system, as well as the complex process of filling all four raceway systems with rolling elements during assembly.

[0006] Furthermore, DE 20 2006 020 465 U1 discloses a roller bearing with an inner ring and an outer ring and rolling elements arranged between them, rolling on raceways. In this bearing, the rolling elements guide a nose ring attached to the outer ring with support rollers in the axial direction and with radial rollers in the radial direction. An additional rolling bearing with diagonal retaining rollers is arranged between the inner ring and the nose ring of the outer ring. Due to the diagonal arrangement, the bearing can absorb additional radial loads and thus prevent or reduce deformation of the nose ring. Although the known roller bearing only has three rows of rollers, the diagonal retaining roller row is designed as a crossed roller bearing to prevent the diagonal retaining rollers from tilting under radial loads. Despite three rows of rollers, four pairs of raceways must therefore be formed on the bearing, which leads to high costs.Furthermore, the raceways of the crossed roller row, which are directly adjacent to one another within a V-shaped groove, can only be manufactured with considerable effort and special machinery without damaging the immediately adjacent raceway. Finally, a crossed roller bearing can only be adapted to the expected load situation to a limited extent, since the rollers are designed with a square cross-section.

[0007] DE 25 52 526 A1 describes a centerless large-diameter bearing with two support rings, the partial cross-section of which is symmetrical, at least in the area of ​​the raceways of the rolling element sets, with the axis of symmetry running approximately parallel to the bearing axis. Raceways for four rows of rollers are mounted on inclined surfaces, transmitting axial, radial, and moment loads.

[0008] From DE 10 2014 104 862 A1 a rolling bearing arrangement for a wind turbine is known, comprising an outer ring and an inner ring, between which a first and a second tapered roller bearing are formed, wherein the first and the second tapered roller bearing are formed asymmetrically.

[0009] DE 10 2014 106 558 A1 shows a bearing arrangement with two bearing halves, which has four rows of tapered rollers. Two rows of tapered rollers are provided between an inner ring section of the first bearing half and the second bearing half, as well as between the second bearing half and the outer ring section of the first bearing half. The four rows are positioned mirror-symmetrically, so that in a radial section through the tapered roller bearing, the rows are arranged in a diamond shape.

[0010] The object of the invention is therefore to provide a rolling bearing in which the radial deformations of the bearing rings relative to each other are limited and which can be structurally adapted more easily to the intended use while being cost-effective to manufacture.

[0011] This object is achieved by a rolling bearing having the features of claim 1.

[0012] This creates a rolling bearing with a first bearing ring and a second bearing ring rotatable relative to the first bearing ring about a rotational axis of the rolling bearing, and with at least three rows of rolling elements arranged to roll between the bearing rings. The first bearing ring has a radially projecting, circumferential nose. The second bearing ring comprises a support ring and a retaining ring, which engage around the nose of the first bearing ring, enclosing the rows of rolling elements between the two bearing rings. The nose has an axial side surface facing the support ring as a first raceway for an axially acting, first row of rolling elements.According to the invention, a circumferential, tooth-like cross-sectional projection is formed in the axial direction on a side of the nose opposite the axial side surface. The projection has two converging flanks, each of which is designed as raceway for a second and third row of rolling elements. The tooth-like projection engages in a circumferential, groove-shaped recess of the retaining ring in the axial direction, including the second and third row of rolling elements.

[0013] In the rolling bearing according to the invention, the first and second bearing rings are interlocked in the radial direction by the engagement of the tooth-like projection of the first bearing ring with the groove-shaped recess of the second bearing ring, mediated by the second and third rows of rolling elements. The interlocking creates a positive connection between the two bearing rings in the radial direction. Because the support ring and retaining ring engage around the nose of the first bearing ring, there is also a positive connection in the axial direction between the two bearing rings. The positions of the two bearing rings relative to one another are thus already defined according to the invention by three rows of rolling elements with three pairs of raceways. Due to the reduced number of preferably hardened raceways, the rolling bearing can be manufactured significantly more cost-effectively than previously known rolling bearings with a higher number of raceways.

[0014] Thanks to the positive locking in the radial and axial directions, the bearing rings support each other when subjected to loads, regardless of the direction of the load. The stiffness of the individual bearing rings thus advantageously combines to absorb the applied loads. This reduces the radial deformation between the first and second bearing rings of the rolling bearing to such an extent that the rolling elements can no longer leave the raceways, thus preventing damage from rolling elements on the raceway edge.

[0015] In the rolling bearing according to the invention, the rolling elements of the second and third row of rolling elements roll on the flanks of the tooth-like projection and the inner surfaces of the groove-shaped recess. This arrangement ensures that the raceways to be machined during production are easily accessible and spaced apart from one another. In particular, unlike a crossed roller bearing, no raceways directly adjoin one another in a V-shaped annular groove.

[0016] Further advantages of the arrangement of the second and third row of rolling elements according to the invention, particularly compared to a crossed roller bearing, are that the rolling elements can be dimensioned in both diameter and width depending on the load, and that space can be provided in the raceway systems for the use of a cage guiding the rolling elements.

[0017] In preferred embodiments of the invention, the angle enclosed by the converging flanks is in the range between 60° and 120°, particularly preferably between 75° and 105°. By selecting the angle enclosed by the flanks, the bearing can be adapted to the load cases expected in the respective application area. The larger the angle selected, the higher the loads that can be absorbed in the axial direction. Conversely, a smaller angle between the flanks allows for larger radial loads to be absorbed.

[0018] Preferably, the two flanks of the tooth-like projection form equal angles with the rotational axis of the rolling bearing. By selecting the support angles of the second and third rows of rolling elements symmetrically to the rotational axis of the rolling bearing, a particularly even distribution of forces in the retaining ring is achieved. With such a symmetrical design, the two rows of diagonal rollers are subjected to essentially the same load under a radial load and also in combination with an axial load. An angle of both flanks of approximately 45° to the bearing rotational axis means that equal forces can be transmitted in the axial and radial directions. However, designs with an asymmetrical selection of the angles of the two flanks to the rotational axis are also possible and, under certain load situations, even advantageous.

[0019] Preferably, at least one sliding surface is formed on the nose adjacent to the tooth-like projection and / or in a groove base of the groove-shaped recess as a guide surface for a cage spacing a rolling element of the second or third row of rolling elements. Sufficient space can be provided in the interlocking of the tooth-like projection and groove-shaped recess to guide the rolling elements of the second and / or third row of rolling elements by means of a cage. The cage is preferably guided on sliding surfaces that are adjacent to and arranged at an angle in the range of 90° to 180° to the raceways. The sliding surfaces are preferably induction hardened.

[0020] According to the invention, the rolling bearing has exactly three rows of rolling elements. Three rows of rolling elements are the minimum required to achieve the double positive locking between the first and second bearing rings in the radial and axial directions. With exactly three rows of rolling elements, the teaching of the invention is implemented particularly cost-effectively, since only exactly three raceway systems need to be formed. If cylindrical rollers are used as rolling elements, some or all of the exactly three rows of rolling elements can also be split. A split design of the rollers in the form of double rollers is advantageous for rolling bearings with particularly high load capacities.

[0021] As a rule, the second and third rows of rolling elements contain rolling elements of the same size. In the case of rollers as rolling elements in the second and third rows of rolling elements, the rollers then have the same diameters and the same widths. However, the second and third rows of rolling elements can also contain rollers as rolling elements that differ in their length and / or width. Preferably, the two flanks of the tooth-like projection then also have different widths. It is particularly preferred to provide the roller row furthest from the center of gravity of the retaining ring cross-section with the smaller roller (see Fig. 3).

[0022] In some embodiments, the first bearing ring is divided at the level of a root region of the tooth-like projection into a nose ring surrounding the nose and a support ring connected to it in the axial direction. Dividing the first bearing ring facilitates access to the flank of the tooth-like projection facing the support ring for forming the raceway.

[0023] Further advantageous embodiments can be found in the following description and the subclaims.

[0024] The invention is explained in more detail below with reference to the embodiments shown in the attached figures. Brief description of the drawings Fig. 1 shows schematically in a partially sectioned view a first embodiment of a rolling bearing according to the invention, Fig. 2 shows schematically in a sectional view a second embodiment of a rolling bearing according to the invention with a divided first bearing ring, and Fig. 3 shows schematically in a sectional view a third embodiment of a rolling bearing according to the invention with different width flanks of the tooth-like projection. Embodiments of the invention

[0025] In the various figures, identical parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

[0026] Fig. Figure 1 shows a partially sectioned view of a rolling bearing 1 with a first bearing ring 2 and a second bearing ring 3 rotatable relative to the first bearing ring 2 about a rotational axis A of the rolling bearing 1. The rolling bearing 1 has three rows of rolling elements 4, 5, 6 arranged so as to roll between the bearing rings 2, 3. The rolling elements of the rows of rolling elements 4, 5, 6 are preferably designed as cylindrical rollers.

[0027] The first bearing ring 2 has a radially projecting, circumferential nose 7. The second bearing ring 3 comprises a support ring 8 and a retaining ring 9, which surround the nose 7 of the first bearing ring 2, enclosing the rolling element rows 4, 5, 6 between the two bearing rings 2, 3.

[0028] The nose 7 has an axial side surface 10 facing the support ring 8 as a first raceway for an axially acting, first rolling element row 4 of the rolling element rows 4, 5, 6. On a side 11 of the nose 7 opposite the axial side surface 10, a circumferential, tooth-like cross-sectional projection 12 is formed in the axial direction, which projection has two converging flanks 13, 14. The two flanks 13, 14 are each formed as a raceway for a second and third rolling element row 5, 6 of the rolling element rows 4, 5, 6. The tooth-like projection 12 engages in a circumferential, groove-shaped recess 15 of the retaining ring 9 in the axial direction, including the second and third rolling element row 5, 6. The rolling bearing 1 according to Fig. 1 has exactly three rows of rolling elements 4, 5, 6.

[0029] The angle W1 enclosed by the converging flanks 13, 14 is preferably in the range between 60° and 120°, particularly preferably between 75° and 105°. In the embodiment according to Fig. 1 the angle W1 is chosen to be approximately 90°.

[0030] Furthermore, the two flanks 13, 14 of the tooth-like projection 12 in the embodiment according to Fig. 1 with the rotation axis A of the rolling bearing 1 equal angles W2, W3, for example approximately 45°.

[0031] The rolling elements 50, 60 of the second and third rolling element rows 5, 6 are each guided at a distance from one another by a cage 18, 19. Sliding surfaces 26, 27 are formed on the nose 7 adjacent to the tooth-like projection 12 and in a groove base 16 of the groove-shaped recess 15 as guide surfaces for the cages 18, 19. The cages 18, 19 comprise sliding pieces 20, preferably made of bronze, for example aluminum bronze, brass, or plastic, which are in sliding contact with the sliding surfaces 26, 27. The sliding pieces can also have a coating to improve the sliding properties, for example a PA coating. The first rolling element row 4 also preferably has a cage 17 for guiding the rolling elements.

[0032] In the embodiment according to Fig. 1, the second and third rolling element rows 5, 6 contain rolling elements 50, 60 of equal length and diameter. In particular, the rolling elements 50, 60 have the same width Bw1, Bw2. The widths Bf1, Bf2 of the flanks 13, 14 serving as raceways on the tooth-like projection 12 are also equal and matched to the widths Bw1, Bw2 of the rolling elements 50, 60. The rolling bearing 1 is thus designed symmetrically with respect to inwardly and outwardly acting radial forces.

[0033] The first and second bearing rings 2, 3 can have fastening holes 24 for mounting on an associated connecting structure (not shown). Preferably, the fastening holes 24 of the second bearing ring 3, when installed, also serve to fix the support ring 8 to the retaining ring 7. For lifting or transporting the rolling bearing, additional retaining screws and / or pins can be used to fix the support ring 8 and the retaining ring 7 to one another. The support ring 7 and the retaining ring 8 can have centering means 25 that ensure centering of the rings 7, 8 during fixation.

[0034] Fig. Figure 2 shows a second embodiment of the rolling bearing according to the invention in a sectional view. In contrast to the embodiment in Fig. 1, the first bearing ring 2 is divided at the level of a root region 21 of the tooth-like projection 12 into a nose ring 22 surrounding the nose 7 and a support ring 23 connected to it in the axial direction. The subdivision of the first bearing ring 2 into nose ring 22 and support ring 23 primarily has the advantage that the flank 14 is more easily accessible during the manufacture and machining of the nose ring 22 and can be machined using standard tools. Furthermore, the subdivision makes it possible to manufacture larger and / or heavier first bearing rings 2 and thus overcome weight-related limits for individual components. Furthermore, particularly in combination with an axial division of the first bearing ring 2, it is possible to design the rolling bearing 1 with bearing rings 2, 3 segmented in the circumferential direction.

[0035] The rolling bearing preferably has a diameter of at least 3 m. For bearing diameters of less than 3 m, the rings, either alone or in combination with the connecting structures used, typically have a rigidity at which the radial deformations of the rings only reach a small fraction of the raceway widths, and the rollers therefore do not leave the raceway system. Preferred applications for the bearings according to the invention are oil transfer stations (FPSOs), as well as large cranes and excavators.

[0036] Analogous to the support ring 8 and retaining ring 7, the nose ring 22 and support ring 23 can have centering means (not shown) which ensure mutual centering of the two rings to each other.

[0037] Furthermore, the explanations for the first embodiment apply to the Fig. 2 shown embodiment accordingly.

[0038] In Fig. Figure 3 shows a third embodiment of the invention in a sectional view. The rolling bearing 1 differs from the first embodiment in that the second and third rolling element rows 5, 6 contain rollers as rolling elements 50, 60 that differ in their widths Bw1, Bw2. The two flanks 13, 14 of the tooth-like projection 12 also have different widths Bf1, Bf2. The widths Bf1, Bf2 of the flanks 13, 14 are adapted to the widths Bw1, Bw2 of the rolling elements 50, 60.

[0039] By selecting rolling elements 50, 60 with different widths Bw1, Bw2, the rolling bearing 1 according to the invention can be adapted particularly precisely to the expected loads. In particular, the bearing can be designed for radial forces of varying magnitude depending on their direction of action. In combination with a corresponding adjustment of the flank widths Bf1, Bf2, the required installation space is optimized.

[0040] Furthermore, the statements regarding the first and second embodiments apply to the Fig. 3 shown embodiment accordingly. List of reference symbols 1 rolling bearing 2 first bearing ring 3 second bearing ring 4, 5, 6 rolling element row 7 Nose 8 support ring 9 Retaining ring 10 axial side surface 11 opposite side of the nose 12 tooth-like projection 13, 14 flanks 15 groove-shaped recess 16 Groove base 17, 18, 19 cage 20 sliding piece 21 Foot area 22 Nose ring 23 Support ring 24 mounting holes 25 centering devices 26, 27 sliding surfaces 50, 60 rolling elements A axis of rotation W1 Angle between flanks W2, W3 Angle between flank and axis of rotation Bw1, Bw2 Width of the rolling elements Bf1, Bf2 width of the flanks

Claims

[1] Rolling bearing with a first bearing ring (2) and a second bearing ring (3) which is rotatable relative to the first bearing ring (2) about a rotational axis (A) of the rolling bearing (1), and with at least three rows of rolling elements (4, 5, 6) which are arranged so as to roll between the bearing rings (2, 3), wherein the first bearing ring (2) has a radially projecting, circumferential nose (7) and the second bearing ring (3) comprises a support ring (8) and a retaining ring (9) which engage around the nose (7) of the first bearing ring (2), enclosing the rows of rolling elements (4, 5, 6) between the two bearing rings (2, 3), wherein the nose (7) has an axial side surface (10) facing the support ring (8) as a first raceway for an axially acting, first row of rolling elements (4) of the rows of rolling elements (4, 5, 6), wherein on one of the On the side (11) of the nose (7) opposite the axial side surface (10), a circumferential, tooth-like projection (12) is formed in the axial direction,which has two flanks (13, 14) converging towards one another, each of which is designed as a raceway for a second and third row of rolling elements (5, 6) of the rows of rolling elements (4, 5, 6), and the tooth-like projection (12) engages in a circumferential, groove-shaped recess (15) of the retaining ring (9) in the axial direction, including the second and third row of rolling elements (5, 6), and wherein the rolling bearing (1) has exactly three rows of rolling elements (4, 5, 6). [2] Rolling bearing according to claim 1, characterized by that the angle (W1) enclosed by the converging flanks (13, 14) lies in the range between 60° and 120°, preferably between 75° and 105°. [3] Rolling bearing according to claim 1 or 2, characterized by that the two flanks (13, 14) of the tooth-like projection (12) enclose equal angles (W2, W3) with the axis of rotation (A) of the rolling bearing (1). [4] Rolling bearing according to one of claims 1 to 3, characterized bythat on the nose (7) adjacent to the tooth-like projection (12) and / or in a groove base (16) of the groove-shaped recess (15) at least one sliding surface (26, 27) is formed as a guide surface for a cage (18, 19) spacing the rolling elements (50, 60) of the second or third row of rolling elements (5, 6). [5] Rolling bearing according to one of claims 1 to 4, characterized by that the second and third rows of rolling elements (5, 6) contain rolling elements (50, 60) of the same size. [6] Rolling bearing according to one of claims 1 to 5, characterized by that the second and third rows of rolling elements (5, 6) contain rollers as rolling elements (50, 60) which differ in their width (Bw1, Bw2) and / or diameter. [7] Rolling bearing according to one of claims 1 to 6, characterized by that the two flanks (13, 14) of the tooth-like projection (12) have different widths (Bf1, Bf2). [8] Rolling bearing according to one of claims 1 to 7, characterized bythat the first bearing ring (2) is divided at the level of a foot region (21) of the tooth-like projection (12) into a nose ring (22) surrounding the nose (7) and a support ring (23) connected thereto in the axial direction.

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