plain bearing

Abstract

The invention relates to a plain bearing (1), in particular a large plain bearing for a wind turbine or a hydroelectric power plant, wherein the plain bearing (1) has at least one face which has a first surface region (20) which has been laser-hardened to a first hardening depth (T1).

Description

Technical Field

[0001] This invention relates to a sliding bearing according to the preamble of claim 1, particularly a large sliding bearing, for example, with a diameter greater than 380 mm. Large sliding bearings are particularly suitable for wind power or hydropower generation. Background Technology

[0002] Sliding bearings can be used in different technical fields, and depending on the application field, different requirements are placed on these sliding bearings.

[0003] Especially in the case of sliding bearings subjected to high loads, such as in wind or hydropower, the raceway / sliding surfaces must be hard and wear-resistant. In contrast, other surfaces can remain untreated (in the condition at delivery). The sliding surfaces of a sliding bearing can slide against each other or against different bushings, thrust washers, strips, slip shoes, or be separated by a lubricating film (such as an oil film).

[0004] To provide a hard and wear-free surface, the sliding surface can be hardened. A known method for this is to subject the sliding surface to heat treatment.

[0005] However, existing heat treatment techniques (such as martensitic hardening, bainitic hardening, surface hardening, nitriding, or induction hardening) have the following disadvantages:

[0006] - Batch processing (excluding induction hardening), no single-piece process.

[0007] - Large-sized equipment / furnaces required for large circles (not easy to obtain)

[0008] Significant warping leads to noticeably oversized soft components and costly rework.

[0009] - Great efforts were made in parts handling and logistics.

[0010] - Surface damage requires hard machining to remove the damaged surface (e.g., decarburization, oxidation, etc.).

[0011] - Tooling costs and associated costs specific to a component (e.g., inductors used for induction hardening).

[0012] - Long tool changeover time when changing production parts

[0013] - Cannot be selectively hardened (except for induction hardening).

[0014] - Floor space requirements for heat treatment plant

[0015] - High energy requirements (except for induction hardening).

[0016] Furthermore, for some of the aforementioned heat treatment methods, it is impossible to find a suitable furnace size, especially for large furnaces.

[0017] Therefore, the present invention solves the problem of providing a sliding bearing whose sliding surface can be manufactured and hardened in an energy-saving and cost-effective manner, and can save laborious rework. Summary of the Invention

[0018] This problem is solved by using a sliding bearing according to technical solution 1.

[0019] Below, a sliding bearing is proposed having at least one face having a first surface region that has been laser-hardened to a first hardness depth.

[0020] The hardening depth should be understood as the region where the phase transformation of the starting material from a ferrite matrix to a martensitic microstructure occurs due to the thermal input of the laser. In other words, during laser hardening of the first surface region, a transformed peripheral portion appears in this region extending over the first hardening depth, which is adjoined to the untransformed matrix.

[0021] What is particularly advantageous here is that the first hardening depth is less than 2 mm, especially about 1 mm deep.

[0022] The aforementioned drawbacks are overcome by using laser hardening. Furthermore, the advantages in energy efficiency and handling are evident in the case of large bearings with diameters greater than 100 cm, which will be explained in more detail below.

[0023] During laser hardening, the steel components undergo localized heat treatment, resulting in a predominantly martensitic microstructure through rapid laser heating followed by cooling via heat conduction. Additional quenching media (e.g., compressed air or water) may be used to increase the quenching rate if necessary for geometric reasons and / or due to the limited hardenability of the steel used.

[0024] Laser hardening is characterized by limited energy / heat input, resulting in low energy consumption and associated low CO2 emissions, low warpage, and limited or zero surface oxidation. This allows for skipping subsequent machining steps to remove surface damage (such as oxide layers / decarburized surfaces / scale that may occur during conventional hardening) and the possibility of integrating the hardening process into soft machining. Therefore, particularly for sliding bearings with large diameters, it can reduce lead time and workload in the manufacturing chain for handling and logistics.

[0025] Furthermore, laser hardening is characterized by high energy density and short processing time. It is also advantageous that only small volumes are affected, or only a small portion of the workpiece cross-section is processed, and no process gas is required. As mentioned above, in the case of laser hardening, quenching of the workpiece after heating can be eliminated, as quenching occurs through heat conduction within the constituent parts. This has the advantage of eliminating the need for quenching media for quenching or cooling the equipment and therefore eliminating the need for pumps. Another advantage of rapidly cooling small volumes of heated material is that cost-effective steels with small CO2 footprints can be used due to the relatively low required alloying element content or the lower desired potential hardness increase. Moreover, the same laser source and optics can be used for different workpiece geometries, thus eliminating or significantly reducing the need for part-specific tooling.

[0026] Another advantage of laser hardening is that only very small warping (if any) occurs in the bearing components during laser hardening, thus partially or completely eliminating costly rework, especially laborious hard machining. This also has the advantage of requiring less material allowance due to less deformation, meaning better material utilization and cost savings.

[0027] Furthermore, the laser hardening process can be integrated into soft machining processes (such as turning, milling, etc.) (i.e., into machining before actual hardening) and / or into hard machining processes (such as grinding, honing) (i.e., into machining after hardening), or even into existing machines.

[0028] Furthermore, flexible laser hardening devices can be integrated into soft machining, but also into hard machining units, which can reduce cycle time and significantly improve productivity. This is particularly important in the field of large bearings, where the effort spent on handling and logistics is relatively significant and costly.

[0029] Especially in sliding bearings, exemplary embodiments in which at least one of the surfaces is a sliding surface that slides in contact with the sliding mating member of the sliding bearing are particularly advantageous, since the sliding surface (i.e., the functional surface) is particularly loaded.

[0030] In contrast to rolling bearings, where relatively cost-effective hardening processes can only be used to a limited extent on raceways or functional surfaces, the hardness penetration depth achievable by laser hardening is usually insufficient to cover Hertzian stresses, whereas the hardness penetration depth achievable by laser hardening for sliding surfaces is perfectly adequate.

[0031] Preferably, the laser-hardened region extends across the entire contact surface of the tribological pairing. However, the hardening depth can gradually decrease in the outer regions of the area to be hardened, as long as the desired surface hardness is achieved in the sliding contact.

[0032] Preferably, the surface hardness of the inner and outer rings at the sliding contact point is at least equal to or higher than the surface hardness of the sliding mating parts.

[0033] However, in addition to laser hardening of the sliding surfaces, it is also advantageous to harden the non-functional surfaces (i.e., surfaces not used for tribological mating) to, for example, protect them from wear. Therefore, the following exemplary embodiment is also advantageous: at least one of the at least three surfaces is a non-functional surface, wherein the non-functional surface, in its assembled state, contacts either the element supported on the sliding bearing or the element receiving the sliding bearing.

[0034] In this case, the non-functional face can be the inner diameter face of the inner ring, the outer diameter face of the outer ring, the lateral face of the bearing ring, and / or the flange of the bearing ring.

[0035] Laser hardening of functional (sliding surface) or non-functional surfaces, such as during assembly, can prevent wear marks. Similarly, the laser-hardened surface can prevent damage to bearing components or other bearing components caused by wear particles in the event of creep between bearing components and surrounding components. Furthermore, the laser-hardened surface area generally reduces wear in motion or in sliding contact between bearing components and / or between bearing components and receiving elements, thus increasing the lifespan of the bearing components and the bearing as a whole.

[0036] Furthermore, a microstructural phase change occurs during laser hardening, leading to changes in specific volume and the density of the physical phase, for example, in the case of transformation to martensite and / or bainite. Consequently, the hardened and transformed surface region has a larger volume than in the initial stage, resulting in micrometer-range elevations on the laser-hardened surface. This can, in turn, increase press fit and / or friction, particularly at the contact surfaces with surrounding components (e.g., shafts or seats), thus reducing the exposure of the components to creep motion.

[0037] Furthermore, "craters" can be generated in the surface morphology due to localized melting of the material and evaporation of the melt (laser engraving). In addition, the increased specific volume of the outer martensite layer generates residual compressive stress in the peripheral region, which counteracts crack initiation and crack propagation.

[0038] However, an increased coefficient of friction can also reduce the press fit or force fit itself, as a high coefficient of friction ensures equally good form fit between components. A lower press fit or a smaller contribution of force fit results in lower tensile stress in bearing components (e.g., the inner ring that contracts to the shaft), which in turn leads to a longer component life.

[0039] Furthermore, the increased coefficient of friction between bearing components and the surrounding environment (e.g., housing / shaft) caused by surface texturing can help prevent motion (e.g., ring creep), thus increasing the lifespan of bearing components.

[0040] Laser hardening of functional and / or non-functional surfaces can be performed using one or more laser heads.

[0041] According to another advantageous exemplary embodiment, the face has at least one second surface region, wherein the second surface region has been laser-hardened to a second hardening depth, wherein the second hardening depth is less than the first hardening depth.

[0042] Alternatively or additionally, the surface may also have at least one third surface region, wherein the third surface region is not laser-hardened.

[0043] As mentioned above, a microstructural phase transformation occurs during laser hardening, leading to changes in specific volume and the density of the physical phase, for example, during the transformation to martensite and / or bainite. The hardened and transformed regions have a larger volume than in the initial stage, resulting in micron-sized bulges on the laser-hardened surface.

[0044] During the process, the more "deeply" hardened surface areas bulge higher than the smaller "deeply" hardened surface areas or the completely unhardened surface areas. In other words, the first surface area bulges higher than the second and / or third surface areas. However, similarly, the second surface area also bulges higher than the third surface area.

[0045] Therefore, specific surface textures and topologies can be applied. Alternatively, material can also be removed / evaporated due to sufficient heating and the creation of localized molten pools, thereby producing textures (laser engraving).

[0046] Of course, additional surface areas with different hardening depths can also be provided to, for example, further refine the surface texture.

[0047] Therefore, as disclosed in a further preferred exemplary embodiment, the first surface region, the second surface region, and / or the third surface region can be configured such that the second surface region and / or the third surface region form a lubricant reservoir and / or lubricant channel defined by the first surface region. This advantageously helps to reduce wear at the sliding contact. Furthermore, it can thus be ensured that lubricant can be retained at specific points on the sliding bearing components, particularly at specific points on the sliding surface, and / or that lubricant can be guided to specific points within the sliding bearing components, particularly at specific points on the sliding surface.

[0048] Therefore, it is possible to create, for example, a "golf-ball topography" to generate lubricant channels and thus improve lubrication conditions. As mentioned above, this can be achieved through selective hardening of localized areas, by varying hardening depths, or by localized melting. The resulting recesses serve as lubricant reservoirs.

[0049] This behavior or characteristic can also be used to create textures that increase friction on non-functional contact surfaces, for example, to prevent relative movement between the ring and the mating contact (seat / shaft). Because the very high coefficient of friction in a form fit or friction fit impedes relative movement between the bearing and the mating part during use, lower pressure fits / less contributing force fits can be achieved. This, in turn, results in lower tensile stresses in bearing components (e.g., the inner ring, which is shrink-fitted onto the shaft) and longer component life.

[0050] Therefore, the following exemplary embodiment is also advantageous: at least one surface is a non-functional surface, and a first surface region that is laser-hardened to a first hardening depth has a first coefficient of friction, and a second surface region that is hardened to a shallower second hardening depth and / or a third surface region that is not laser-hardened has a second coefficient of friction and a third coefficient of friction, respectively, wherein the first coefficient of friction is higher than the second coefficient of friction and / or the third coefficient of friction.

[0051] Due to the specific increase in the coefficient of friction of bearing components at certain points, relative movement between bearing components and mating parts (e.g., shaft / seat) can become more difficult during use. The increased coefficient of friction, along with the specific construction of surface textures, can allow for lower pressure fits or smaller force fits, which in turn leads to lower tensile stresses in the bearing components and longer component life.

[0052] According to another advantageous exemplary embodiment, the first surface region is continuous.

[0053] Therefore, a sliding bearing can be characterized by the absence of soft spots on its entire circumferential surface, thereby ensuring, for example, a uniform increase in the coefficient of friction, and thus ensuring uniform force transmission. This can be achieved using one or more laser heads.

[0054] Alternatively, it is certainly advantageous for the first surface region to be in the form of separate surface region portions.

[0055] Therefore, for example, a soft, un-laser-hardened region can be provided across the entire circumferential surface between the start and end positions of the scanning operation, or even multiple soft regions can be allowed to form a specific pattern. Thus, for example, hardening can take the form of multiple rectangular / square points, multiple circular / elliptical points, multiple triangles, or zigzags, optionally with different angles.

[0056] In this context, patterns can include additional functions, such as the aforementioned lubricant reservoir or channel. However, they can also be configured as specific designs, such as designs that visually assign the bearing to the applicant as the manufacturer.

[0057] According to another preferred exemplary embodiment, the laser-hardened surface region has at least one soft spot or flexible joint, wherein the soft spot / flexible joint is configured in a non-load-bearing region of the laser-hardened surface region, and / or wherein the soft spot / flexible joint is configured at an angle to the load-bearing direction.

[0058] There can be one soft spot / flexible connector or multiple soft spots / flexible connectors.

[0059] Such soft spots / soft joints can also occur, for example, when a previously hardened area is reheated. This can happen, for instance, when a laser scanning the surface to be hardened passes over an area of ​​the surface that has already been reheated and cooled. Particularly in sliding bearings, such soft spots are not absolutely critical because the entire surface is used as a sliding surface, and small, localized soft spots are not essential once the sliding surface has also hardened.

[0060] As a result, the hardening process can be significantly simplified because complex facility technologies or process controls (especially for preheating, etc.) can be eliminated, which is necessary for slip-free hardening (i.e., hardening without soft spots or joints).

[0061] In principle, the surface area to be hardened can be hardened by laser hardening, whether or not a flexible joint is present.

[0062] If possible, prioritize technically simpler processes, namely hardening processes with flexible joints for raceway / sliding surface hardening. Flexible joints are acceptable, especially when permanent contact between sliding elements can be avoided (e.g., in hydrodynamic or hydrostatic sliding bearings).

[0063] All non-functional surfaces can be hardened with flexible joints.

[0064] The soft spot or flexible joint is preferably oriented in the axial direction or perpendicular to the overrolling / load direction.

[0065] To achieve better load and stress distribution, as disclosed in a further preferred exemplary embodiment, the flexible joint can be embodied at different angles other than the axial direction parallel to the ring.

[0066] If the sliding bearing performs an oscillating motion of less than 360° (typically + / -5°-40°), the flexible joint can also be positioned in the non-load-bearing zone.

[0067] According to another preferred exemplary embodiment, the sliding bearing has a split bearing ring at at least one mating surface, wherein at least one soft spot is preferably located near the mating surface. A laser beam hardening device can also be used to create localized grooves at the mating surface for crack initiation, for subsequent intentional separation (laser grooving).

[0068] Laser hardening is particularly advantageous if one of the sliding bearing races separates due to assembly reasons, because the volume of internal stress introduced by laser hardening is much smaller than in the case of conventional hardening, resulting in less deformation when the bearing race separates. The deformation during separation is due to the release of internal stress introduced into the bearing race during heating / hardening. Especially in the case of induction hardening, the internal stress can be so high that laborious rework is required after separation, or in the worst case, the entire bearing race becomes unusable.

[0069] Furthermore, it is advantageous that the bearing rings to be separated have a flexible joint in addition to the mating surfaces. This flexible joint can be configured near the separation point, outside the load-bearing area. Therefore, the deformation generated during the stress release caused by separation can be particularly well offset, since no internal stress or only minimal internal stress is introduced in the area of ​​the flexible joint.

[0070] Furthermore, the following exemplary embodiment is advantageous: the sliding bearing includes a first sliding partner having a first sliding surface and a second sliding partner having a second sliding surface, the first sliding partner and the second sliding partner slidingly contacting each other at their respective sliding surfaces, wherein the first sliding surface and the second sliding surface each have a first surface region that has been laser-hardened, wherein the hardness of the first surface region of the first sliding surface and the hardness of the first surface region of the second sliding surface have substantially the same laser-hardened hardness.

[0071] When two sliding mating parts have the same hardness, it can be ensured that one of the mating parts will not become excessively worn, while the other mating part will not experience wear or will only experience very little wear.

[0072] Furthermore, it is advantageous that the components of the sliding bearing, including the surface with a laser-hardened surface area, are made of quenched and tempered steel.

[0073] Typical steel grades are all hardenable steel grades, with the following chemical composition ranges:

[0074] Carbon (0.30% to 1.10% by weight), and / or

[0075] Silicon (0.10 wt% to 1.0 wt%), and / or

[0076] Manganese (0.10% to 1.50% by weight), and / or

[0077] Chromium (0.10% to 2.00% by weight) and / or

[0078] Molybdenum (0.01 wt% to 0.75 wt%).

[0079] Particularly preferred are steels with quenched and tempered grades having a carbon content between 0.3% and 1.1% by weight. These particularly include steels with a specification of 42CrMo4.

[0080] Alternatively, it is also advantageous to use steel with a specification of 50CrMo4.

[0081] This type of quenched and tempered steel can be hardened particularly easily.

[0082] Further advantages and advantageous embodiments are specified in the specification, drawings, and claims. In particular, the combinations of features specified in the specification and drawings are merely by way of example, and therefore the features may exist alone or in combination. Attached Figure Description

[0083] The invention will now be described in more detail with reference to exemplary embodiments shown in the accompanying drawings. In this context, the exemplary embodiments and combinations thereof shown are merely examples and are not intended to define the scope of the invention. The scope of the invention is defined only by the appended claims.

[0084] In the attached diagram:

[0085] Figure 1 A schematic cross-sectional view of a first exemplary embodiment through a sliding bearing is shown;

[0086] Figure 2 A schematic cross-sectional view of a second exemplary embodiment through a sliding bearing is shown;

[0087] Figure 3 A schematic cross-sectional view of a third exemplary embodiment passing through a sliding bearing is shown;

[0088] Figure 4 A schematic perspective view of a fourth exemplary embodiment of a sliding bearing ring is shown;

[0089] Figure 5 A schematic perspective view of a fifth exemplary embodiment of a sliding bearing ring is shown;

[0090] Figure 6 A schematic perspective view of a sixth exemplary embodiment of a sliding bearing ring is shown;

[0091] Figure 7 A schematic perspective view of a seventh exemplary embodiment of a sliding bearing ring is shown;

[0092] Figure 8 A schematic perspective view of an eighth exemplary embodiment of a sliding bearing ring is shown;

[0093] Figure 9 A schematic perspective view of a ninth exemplary embodiment of a sliding bearing ring is shown;

[0094] Figure 10 A schematic perspective view of a tenth exemplary embodiment of a sliding bearing ring is shown;

[0095] Figure 11 A schematic perspective view of an eleventh exemplary embodiment of a sliding bearing ring is shown;

[0096] Figure 12 This diagram illustrates the surface texture.

[0097] Figure 13 A schematic perspective view of a twelfth exemplary embodiment of a sliding bearing ring is shown; and

[0098] Figure 14 A schematic perspective view of a thirteenth exemplary embodiment of a sliding bearing ring is shown.

[0099] List of reference numerals

[0100] 1. Sliding bearing

[0101] 2, 4 Bearing Rings (Outer Ring, Inner Ring)

[0102] 5. Sliding bearing ring

[0103] 6, 8, 7 Sliding surfaces

[0104] 12 seats

[0105] 14-axis

[0106] 16 and 18 contact surfaces

[0107] Surface areas 20, 22, and 24

[0108] 21 Matrix

[0109] 25 End area / Connector area

[0110] 26 gaps

[0111] 25 connector

[0112] 28 Lubricant dents

[0113] 30 Seals

[0114] 32 Thrust surface

[0115] 34, 36, 38 Sliding Boots

[0116] 40 mating surfaces

[0117] T1, T2 hardening depth Detailed Implementation

[0118] In the following text, the same elements or elements having the same functional effect are identified by the same reference numerals.

[0119] Figure 1 A schematic cross-sectional view through a sliding bearing 1 is shown, the sliding bearing 1 having an outer ring 2 and an inner ring 4, the outer ring 2 and the inner ring 4 slidingly contacting each other at sliding surfaces 6 and 8, respectively. Furthermore, Figure 1 The diagram shows the outer ring 2 housed within a housing 12, while the inner ring 4 is supported by a shaft 14. Therefore, the outer ring 2 is in frictional contact with the housing 12 via its outer surface 16, and the inner ring 4 is in frictional contact with the shaft 14 via its inner surface 18. According to the definition of the invention, the sliding surfaces 6 and 8 should therefore be considered functional surfaces, while the contact surfaces 16 and 18 should be considered non-functional surfaces.

[0120] also, Figure 1 and Figure 2 (In more detail) It is shown that the sliding surfaces 6 and 8 have first surface regions 20-6 and 20-8, wherein the sliding surfaces 6 and 8 have been laser-hardened to first hardening depths T1-6 and T1-8.

[0121] During laser hardening, the steel components undergo localized heat treatment, resulting in a martensitic microstructure through rapid laser heating and subsequent cooling via heat conduction. This martensitic microstructure extends in the first surface region 20 to a first hardening depth T1. Below the surface region 20 lies the matrix 21 (i.e., the initial microstructure of the steel), which, if affected, is only slightly influenced by the heat treatment performed using the laser.

[0122] The martensitic microstructure generated by the laser ensures that the bearing ring is much more wear-resistant and can withstand significant loads in the first surface region 20 at sliding surfaces 6 and 8.

[0123] Preferably, the hardening depths T1-6 and T1-8 are substantially the same.

[0124] Optionally, such as Figure 1 The simplified drawing shows that non-functional surfaces (i.e., contact surfaces 16, 18, through which the outer ring 2 is accommodated in the seat 12 and the inner ring 4 contacts the shaft 14) can also be laser-hardened in surface areas 20-16, 20-18 up to a hardening depth T1 (see [reference]). Figure 1 ).

[0125] Due to the microstructural phase transformation that occurs during laser hardening, resulting in changes in specific volume and physical phase density—for example, during the transformation to martensite and / or bainite—the hardened and transformed surface region has a larger volume than in the initial stage, leading to micron-level bulges on the laser-hardened surface. This, in turn, increases press fit and / or friction, particularly at the contact surfaces 16, 18 with surrounding components (e.g., shaft 14 or seat 12), reducing creep movement of the components. Alternatively, localized melting can alter the surface morphology, increasing the coefficient of friction through the resulting molten pits and bulges.

[0126] Furthermore, the friction-field-increasing characteristic of laser hardening allows for a smaller overlap between the bearing rings (e.g., outer ring 2, inner ring 4) and the components receiving the bearing rings (e.g., shaft 14, seat 12), and also enables a comparable (if not better) rotationally fixed connection between the bearing components and surrounding components. This, in turn, reduces tensile stress in the bearing itself and results in a longer lifespan. The residual compressive stress generated in the hardened outer layer also contributes to a longer lifespan.

[0127] Figure 2 Another example is shown in a detailed view, in which the sliding bearing 1 additionally has a seal 30, which is fastened to the outer ring 2 and rubs against the inner ring 4 in areas where it does not slide against the outer ring 2, and the inner ring serves as a thrust surface 32 for the seal 30. The thrust surface 32 can be assigned as a functional surface (i.e., the sliding surface 8) or as a non-functional surface (since there is no sliding contact with the outer ring 2 here). Regardless of the assignment, the thrust surface 32 of the seal 30 is likely to be subject to increased wear. Therefore, it is advantageous to also laser harden the thrust surface 32.

[0128] The thrust surface 32 can be hardened to the same hardening depth T1 as the sliding surface 8.

[0129] Optionally, the thrust surface 32 can be hardened to a second hardening depth T2.

[0130] Optionally, the sliding surface 8 then includes a first surface region 20 having a first hardening depth T1 and a second surface region 22 having a second hardening depth T2.

[0131] Figure 3Another example of a sliding bearing 1 with a sliding bearing ring 5 is schematically shown. The sliding bearing ring 5 is housed in a seat 12 and slides on three sides along sliding shoes 34, 36, and 38 carried by the seat 12. For this purpose, the sliding ring 5 has three sliding surfaces 7-1, 7-2, and 7-3, which are also hardened to a first hardening depth T1-7 in the first surface region 20 of the sliding contact.

[0132] As mentioned above, laser hardening causes a phase transformation, which leads to a volume change in the hardened material, causing the hardened points to protrude slightly from the surface. This fact can also be used to provide surfaces with specific textures, ensuring, for example, that lubricants are held at specific points or guided to specific locations.

[0133] In this case, particularly at sliding surfaces 6 and 8, it is especially preferable to apply a lubricant reservoir structure or lubricant channel structure, which ensures that the lubricant is retained at sliding surfaces 6 and 8 and is not transported away. Therefore, improved emergency operating characteristics or lubrication conditions can be achieved even at low speeds.

[0134] Figures 4 to 11 The sliding surfaces 8 with different laser hardening processes are schematically shown, such as the sliding surface on the inner ring 4.

[0135] Therefore, for example, Figure 4 The first surface region 20, which is laser-hardened, extends over the entire sliding surface 8.

[0136] Surface 20 can be laser-hardened in a slip-free manner (i.e., there is no discernible difference in the hardening of surface 20 around the entire circumference) or in a slip-based manner (i.e., there is at least one joint 25).

[0137] Similarly, it is conceivable to form hardnesstracks in a spiral pattern around the circumference, while retaining soft areas between the tracks.

[0138] Alternatively, hardness tracks can be formed in a directly adjacent manner, resulting in a hardened surface.

[0139] If hardening is not achieved in a non-slip manner, a soft joint may exist in the area of ​​optional joint 25. For example, such a soft spot / soft joint can occur when a hardened area is reheated. This can happen, for example, when the laser scanning the surface to be hardened passes again over an area of ​​the surface that has been reheated and cooled, or, for example, when the distance between the laser and the hardened surface is very small, heat is introduced into the reheated and cooled area of ​​the surface to be hardened via thermal conduction. Such a soft spot is not absolutely critical, especially in sliding bearings, because the entire surface is used as a sliding surface, and small, localized soft spots are not critical when the sliding surface has also been hardened.

[0140] In contrast, as already referenced Figure 2 As described, Figure 5 It is shown that not the entire sliding surface 8 has been uniformly laser-hardened. In the illustrated exemplary embodiment, a first surface region 20 that has been laser-hardened to a first hardening depth T1, a second surface region 22 that has been laser-hardened to a second hardening depth T2, and a third surface region 24 that has not been laser-hardened at all are provided. Furthermore, Figure 5 The laser-hardened surface regions 20 and 22 are shown to extend continuously around the entire bearing ring 2.

[0141] In contrast, Figure 6 In the exemplary embodiment, the laser-hardened surface region 20 does not extend around the entire circumference, thus leaving a gap 26 in the end region / joint region 25. This gap 26 can occur, for example, when a bearing race is scanned using a laser head. However, since the laser-hardened surface 20 is a sliding surface 8, the small unhardened area 26 is not critical, even for the wear characteristics of the bearing race.

[0142] Figure 7 Two laser-hardened surface regions 20-1 and 20-2 are shown, which, laterally and centrally, have corresponding surface regions 22-1, 22-2, and 22-3 with a shallower hardening depth T2 and / or unhardened regions 24-1, 24-2, and 24-3. These regions 22 and 24 can, for example, serve as lubricant channels to specifically retain or guide lubricant to the sliding surface.

[0143] Figure 12The image shows these lubricant channels or indentations 28 in a magnified manner. As mentioned above, these lubricant channels or indentations are created due to specific local adjustments in laser hardening, wherein in the lubricant indentation areas (surface areas 22; 24), laser hardening is not performed (surface area 24), or only at a lower intensity (surface area 22).

[0144] As a result, the golf ball shape can also be applied to bearing rings to ensure particularly good lubricant reception.

[0145] Of course, it is also possible, for example, that the surface region 22-2 hardened to the second hardening depth T2 is centrally located between the surface regions 20 hardened to the first hardening depth, but the unhardened surface regions 24-1, 24-3 remain in the peripheral region of the bearing ring 2.

[0146] Apart from Figures 4 to 7 In addition to the exemplary implementation that extends continuously, the points separated can also be laser-hardened only, such as... Figures 8 to 11 The exemplary implementation is shown in the figure. Of course, other patterns are conceivable, and therefore, specific patterns, such as those used to assign bearing rings to a particular manufacturer, are also possible.

[0147] As mentioned above, bearing rings 2 and 4 can be hardened with or without slippage.

[0148] In addition, one or more laser heads can be used.

[0149] Figure 13 and Figure 14 Another exemplary embodiment is shown, in which bearing rings 2 and 4 are split at the mating surface 40 for assembly reasons. Especially in the case of large sliding bearings, one of the bearing rings must be split in order to assemble the two bearing rings in a sliding contact manner with each other.

[0150] In bearing rings 2 and 4 that must be separated due to assembly requirements, laser hardening is particularly advantageous because the volume of internal stress introduced by hardening is much smaller in the case of laser hardening than in the case of conventional hardening. This results in less deformation when the bearing rings separate. The deformation during separation is due to the release of internal stress introduced into the bearing rings during heating / hardening.

[0151] Figure 13Bearing rings 2 and 4 are shown, in which all surfaces to be hardened around the circumference have been laser-hardened, and joint faces 40 can be configured circumferentially on bearing rings 2 and 4 as needed. When installing the bearing, the joint face 40 can, for example, be configured such that it is positioned at a point on the sliding bearing where it is not loaded or carries little load.

[0152] Figure 14 A bearing ring is shown, wherein at least one unhardened region 26 or a region that has been hardened and then tempered again (i.e., the so-called soft joint 25) is disposed near the mating surface 40. Therefore, deformation generated during the release of internal stress caused by separation can be particularly well offset because no internal stress or only negligible internal stress is introduced in the region of the soft joint. Furthermore, due to the provision of one or more soft regions near the hardened “predetermined fracture point,” more targeted crack initiation can be established in the hardened, more brittle microstructure (laser-hardened).

[0153] In summary, laser hardening can provide sliding bearings with greater wear resistance. Furthermore, laser hardening allows for the application of surface textures, which help retain lubricant on the sliding surface, thereby improving the lubrication characteristics of the sliding bearing.

[0154] Furthermore, during laser hardening of even non-functional surfaces, the relative movement between bearing components and the components that receive the bearing components can be reduced.

[0155] Laser hardening can be achieved using one or more laser heads and can preferably be integrated into existing machining processes, eliminating the need for additional, expensive machining steps.

Claims

1. A sliding bearing (1), particularly a large sliding bearing for wind turbines or hydroelectric power plants, characterized in that, The sliding bearing (1) has at least one surface having a first surface region (20) that has been laser-hardened to a first hardening depth (T1).

2. The sliding bearing (1) according to claim 1, characterized in that, At least one of the at least one surfaces is a sliding surface (6, 8, 7) that is in sliding contact with the sliding mating member of the sliding bearing (1).

3. The sliding bearing (1) according to claim 1 or 2, characterized in that, At least one of the at least one surfaces (16; 18) is a non-functional surface, wherein the non-functional surface (16; 18) is in contact with an element (12; 14) supported on the sliding bearing (1) or with an element receiving the sliding bearing (1) in the assembled state.

4. The sliding bearing (1) according to any one of the preceding claims, characterized in that, The surface has at least one second surface region (22), wherein the second surface region (22) has been laser-hardened to a second hardening depth (T2), wherein the second hardening depth (T2) is less than the first hardening depth (T1).

5. The sliding bearing (1) according to any one of the preceding claims, characterized in that, The surface has at least one third surface region (24), wherein the third surface region (24) is not laser-hardened.

6. The sliding bearing (1) according to claim 4 or 5, characterized in that, The first surface region and the second surface region and / or the third surface region (22, 24) are configured such that the second surface region and / or the third surface region (22, 24) form a lubricant reservoir and / or lubricant channel (26) defined by the first surface region (20).

7. The sliding bearing (1) according to claim 3 and any one of claims 4 and 5, characterized in that, The at least one surface is a non-functional surface, and the first surface region (20) that is laser-hardened to a first hardening depth (T1) has a first coefficient of friction, the second surface region (22) that is laser-hardened to a second hardening depth (T2) has a second coefficient of friction, and / or the third surface region (24) that is not laser-hardened has a third coefficient of friction, wherein the first coefficient of friction is higher than the second coefficient of friction and / or the third coefficient of friction.

8. The sliding bearing (1) according to any one of the preceding claims, characterized in that, The first surface region (20) is continuous.

9. The sliding bearing (1) according to any one of claims 1 to 7, characterized in that, The first surface region (20) is in the form of separate surface region portions.

10. The sliding bearing (1) according to any one of the preceding claims, characterized in that, The laser-hardened surface regions (20, 22) have at least one soft point (25), wherein the soft point is disposed in the non-load-bearing region of the laser-hardened surface region, and / or the soft point is configured at an angle to the load-bearing direction.

11. The sliding bearing (1) according to any one of the preceding claims, characterized in that, The sliding bearing (1) has a bearing ring that is split at at least one mating surface (40), wherein at least one soft spot (25) is preferably located near the mating surface (40).

12. The sliding bearing (1) according to any one of the preceding claims, characterized in that, The sliding bearing (1) includes a first sliding mating member having a first sliding surface and a second sliding mating member having a second sliding surface. The first sliding mating member and the second sliding mating member slide in contact with each other at their respective sliding surfaces. The first sliding surface and the second sliding surface each have a first surface area (20) that has been laser-hardened. The hardness of the first surface area of ​​the first sliding surface and the hardness of the first surface area of ​​the second sliding surface are substantially the same as the laser-hardened hardness.

13. The sliding bearing (1) according to any one of the preceding claims, characterized in that, The first hardening depth (T1) of the laser-hardened first surface region (20) has a depth of less than 2 mm, and in particular, the first hardening depth (T1) of the laser-hardened first surface region (20) has a depth of approximately 1 mm.

14. The sliding bearing (1) according to any one of the preceding claims, characterized in that, The components of the sliding bearing (1), including the surface region having the laser-hardened surface area, are made of quenched and tempered steel with a carbon content between 0.4% and 1.1% by weight, and in particular, the components are made of 42CrMo4 steel or 50CrMo4 steel.

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