Coated bearing and method for its manufacture

Abstract

Bearing (1) comprising a first bearing part (2) with a first base body (3) and a first running surface (4) and a second bearing part (5) with a second base body (6) and a second running surface (7), wherein the first running surface (4) and the second running surface (7) are at least partially facing each other, characterized in that the first running surface (4) has at least partially a lipophilic coating (8) and a lipophobic coating (9), wherein the lipophilic coating (8) is substantially arranged between the first base body (3) and the lipophobic coating (9).

Description

[0001] The invention relates to a coated bearing, in particular a rolling bearing, a linear guide, and a ball screw drive, comprising a first bearing part with a first base body and a first running surface, and a second bearing part with a second base body and a second running surface, wherein the first running surface and the second running surface at least partially face each other. The first running surface at least partially has a lipophilic coating and a lipophobic coating, wherein the lipophilic coating is arranged substantially between the first base body and the lipophobic coating. Furthermore, the invention relates to a method for its production.

[0002] Radial and axial rolling bearings are used to support two objects in a rotatable manner relative to one another. Rolling bearings have two bearing rings, each of which can be arranged on one of the objects to be supported and can rotate relative to each other about a common axis. To ensure that the bearing rings slide against each other with as little friction as possible, rolling elements are arranged between the bearing rings. These rolling elements roll or roll on the running surfaces of the bearing rings. Linear guides and ball screws essentially function according to the same principle, with linear guides using a carriage on a guide rail, and ball screws using a nut on a spindle.

[0003] To reduce the rolling resistance of rolling bearings, linear guides, or ball screws, to ensure the smoothest and most consistent running possible, to reduce operating temperatures, and to achieve minimal wear, the rolling elements and running surfaces have the smoothest and most consistent surfaces possible and are made of a hard, low-wear, preferably corrosion-resistant material. Furthermore, rolling bearings, linear guides, and ball screws are lubricated, e.g., with grease or oil, to further reduce rolling resistance.

[0004] During operation, different zones of rolling bearings, linear guides, or ball screws are exposed to different loads, which cause varying degrees of wear. For example, high localized compressive forces on rolling bearings, linear guides, or ball screws can initially lead to a local displacement of the lubricant. Centrifugal forces also contribute to the displacement of the lubricant towards the bearing seals. Failure to relubricate the bearing can lead to local dry running, meaning that in some areas of the bearing there is no longer sufficient lubricant to ensure adequate or continuous lubrication. To ensure the operational reliability of such a bearing, the bearing must be supplied with lubricant within a specific relubrication cycle.

[0005] A lack of lubricant leads to an increased operating temperature of the bearing and results in increased wear or surface fatigue.

[0006] Publication JP 2014-95437 A describes a thrust ball bearing with a pair of races arranged parallel to each other so that they are axially separated. A plurality of balls are arranged between the pair of races so that they roll between them. A retainer is arranged between the pair of races and holds the plurality of balls at substantially equal intervals. A lipophilic treatment is applied to the rolling surfaces of the pair of races.

[0007] Publication DE 11 2008 000 540 T5 describes a lubricating grease for a high-speed bearing. This lubricating grease comprises a urea-based grease containing a urea-based compound as its thickener, and a non-urea lubricating grease blended with the urea grease containing a non-urea-based thickener.

[0008] Publication DE 10 2010 031 439 A1 describes a rolling bearing. This comprises several components, including at least one bearing ring and rolling elements that roll on the at least one bearing ring. At least one of the components is provided on its surface with a coating with a thickness of 2 µm or less, wherein the coating contains a nickel-phosphorus alloy produced by a chemical deposition process in such a way that it exhibits microbrittle behavior.

[0009] Publication JP 2007-10 114 A describes a rolling bearing for a transmission. An oil coating is applied to at least one inner ring, one outer ring, and one rolling element. Oil-repellent films are formed on a sealing end portion, an outer peripheral surface of the inner ring, and an inner peripheral surface of the outer ring.

[0010] Publication US 2012 / 0 148 180 A1 discloses a lubricating oil supplied between a sliding surface of a shaft member and a sliding surface of a support member. The support member has a sliding surface portion corresponding to a load concentration portion between the shaft member and the support member. Sliding surface regions with higher oil repellency than the sliding surface portion are provided on the upstream and downstream sides of the sliding surface portion, respectively, in a flow direction of the lubricating oil.

[0011] The object of the present invention is therefore to provide a bearing and a method for manufacturing a bearing that ensures a sufficient supply of lubricant to the contact zone. In particular, the object of the present invention is to provide a bearing that, even under high mechanical loads, exhibits improved lubricant distribution, as well as lower wear, a longer service life, and a longer relubrication cycle than conventional bearings.

[0012] This object is achieved by a bearing according to claim 1. Dependent claims 2 to 7 relate to particularly preferred embodiments of a generic bearing. Furthermore, the object is achieved by a method for producing a bearing according to claim 8.

[0013] Accordingly, the object of the present invention is achieved by a bearing comprising a first bearing part with a first base body and a first running surface and a second bearing part with a second base body and a second running surface, wherein the first running surface and the second running surface are at least partially facing each other.

[0014] The first running surface has at least partially a lipophilic and a lipophobic coating, wherein the lipophilic coating is arranged substantially between the first base body and the lipophobic coating.

[0015] The first bearing part and the second bearing part are movable relative to one another, e.g., rotatable about a common axis or movable along a longitudinal axis. Preferably, the first running surface and the second running surface are designed to reduce friction occurring during such a relative movement and therefore, for example, have a low roughness value and / or are particularly hard or erosion-resistant.

[0016] The first running surface has, at least in part, a lipophilic coating. A lipophilic coating has the special property of attracting greases or lubricants. Such a coating is particularly advantageous in areas of the bearing where particularly high mechanical forces act during operation, so that at least in these areas sufficient lubricant is still present even after extended periods of operation. Therefore, it is particularly advantageous if at least a central area of ​​the first running surface has a lipophilic coating. Alternatively, the entire first running surface has a lipophilic coating.

[0017] A lipophobic coating has the special property of repelling grease or lubricants. In this case, a lipophobic coating can be applied over the entire lipophilic coating. This has the advantage that in a non-worn bearing, the lubricant only comes into contact with the lipophobic coating and is repelled, causing further wear. Wear locally erodes the lipophobic coating, exposing the lipophilic coating at these points and attracting lubricant. This ensures that more lubricant is present in areas of the bearing that are subject to particularly high mechanical stress than in areas with less stress. This has the advantage that even when there is little lubricant present, sufficient lubrication can be guaranteed in these areas. In an alternative embodiment, the lipophobic coating is only applied in areas of the bearing, e.g.They are arranged in peripheral areas that are subject to relatively low mechanical loads or through which the lubricant could escape from the bearing. This has the advantage that the lubricant is concentrated particularly in areas exposed to increased loads and that escape of the lubricant from the bearing is at least partially prevented. Such bearings exhibit lower internal friction values, a longer service life, and an extended relubrication cycle, even after extended operation.

[0018] Preferably, the second running surface has a lipophilic coating and a lipophobic coating, with the lipophilic coating being arranged substantially between the second base body and the lipophobic coating. This has the advantage that a lipophilic coating is arranged on both the first running surface and the second running surface, which promotes optimal distribution of the lubricant in the bearing. Such a bearing exhibits lower internal friction values, an increased service life, and an extended relubrication cycle, even after extended operation.

[0019] More preferably, the bearing is designed as a rolling bearing, with the first bearing part being designed as an inner ring or outer ring, and the second bearing part being designed as an outer ring or inner ring, respectively. At least one rolling element is arranged between the first raceway and the second raceway. The rolling bearing preferably has a plurality of rolling elements to better distribute forces acting between the inner ring and outer ring on the raceways or the raceway coatings. Alternatively, the bearing is designed as a linear guide or ball screw drive.

[0020] In an advantageous embodiment, the rolling element is arranged in a rolling element cage. Such a rolling element cage has the advantage that adjacent rolling elements are always sufficiently spaced apart and do not roll against each other during operation. This reduces internal friction and thus wear on the bearing, extending its service life.

[0021] The bearing is preferably designed as a rolling bearing. Such bearings are subject to particularly high loads in certain areas, so that a coating of this type can advantageously improve the supply of lubricant in these areas.

[0022] It is preferred that the lipophobic coating has at least one inner recess in which a first part of the lipophilic coating is arranged, wherein the first part of the lipophilic coating is surrounded by the lipophobic coating on at least two sides. In a preferred embodiment, the lipophilic coating has a T-shaped cross-section. Likewise preferably, the lipophobic coating is designed such that in one region the lipophilic coating is not covered by the lipophobic coating. Thus, for example, a region of the lipophilic coating of the first bearing part can face directly towards the second bearing part without a lipophobic coating being arranged in this region between the lipophilic coating and the second bearing part.This has the advantage that even with a bearing that is not or only slightly worn, a better supply of lubricant is ensured in this area of ​​the lipophilic coating. Abrasion of the lipophobic coating is therefore unnecessary, as the lipophilic coating is already exposed.

[0023] It is particularly preferred that in a first region, in which the greatest forces occur during operation of the bearing, a layer thickness of the lipophilic coating is thicker than in other regions and / or a layer thickness of the lipophobic coating is thinner than in other regions. This has the advantage that the presence of a lipophilic coating in the first region and thus the positive properties of the lipophilic coating in the first region are ensured. A thinner lipophobic coating in the first region has the advantage that only minimal wear of the lipophobic coating is required until the positive properties of the lipophilic coating in the first region become apparent.

[0024] Particularly advantageously, a lubricant containing at least one AW and / or EP additive is arranged between the first bearing part and the second bearing part. AW (anti-wear) additives are lubricant additives that reduce abrasive wear. EP (extreme pressure) additives are lubricant additives that prevent welding of metal bearing parts rubbing against each other under pressure.

[0025] Furthermore, the problem is solved by a method for producing a bearing comprising the steps: - Providing a first bearing part with a first base body and a first running surface; - Applying a lipophilic coating to the first tread; - Applying a lipophobic coating on the lipophilic coating; - Providing a second bearing part with a second base body and a second running surface; and - Arranging at least one rolling element between the lipophobic coating and the second running surface.

[0026] A bearing according to the invention can be produced using this method.

[0027] The invention will be explained in more detail below with reference to a drawing. The drawings schematically show: Fig. 1 a flow diagram of the method according to the invention for producing a bearing; Fig. 2 a plan view of a bearing ring of a first embodiment of a bearing; Fig. 3 a sectional top view of the bearing ring from Fig. 2 Fig. 4 a side view of the first embodiment of the bearing with the bearing ring from Fig. 2, and Fig. 5 a sectional plan view of a bearing ring of a second embodiment of a bearing.

[0028] In Fig. 1 shows a flow diagram of a method for producing a rolling element cage. In the first method step 100, a first bearing part 2 having a first base body and a first running surface 4 is provided. In the second method step 200, the first running surface 4 is coated with a lipophilic coating 8. The lipophilic coating 8 is preferably arranged at least in regions of the first running surface 4 that are exposed to particularly high mechanical loads during operation of the bearing 1. In the third method step 300, a lipophobic coating 9 is applied to the lipophilic coating 8. The lipophobic coating 9 preferably covers at least regions of the lipophilic coating 8 that are exposed to less high mechanical loads during operation of the bearing 1.In the fourth method step, a second bearing part 5 is provided with a second base body 6 and a second raceway 7, which may also have a lipophilic coating 8, preferably covered with a lipophobic coating 9. In the fifth method step 500, at least one rolling element 12 is arranged between the lipophobic coating 9 and the second raceway 7. The thickness of the lipophilic coating 8 and the lipophobic coating 9 is preferably significantly thinner in relation to the inner ring 10 than shown in the drawing.

[0029] Fig. 2 shows a plan view of a bearing ring of a first embodiment of a bearing 1. The bearing ring is a first bearing part 2 and is designed as an inner ring 10 with a bearing axis L. The inner ring 10 has a running surface 4, which has a lipophobic coating 9 on each of its two outer sides and a lipophilic coating 8 between the lipophobic coatings 9. The thickness of the lipophilic coating 8 and the lipophobic coating 9 is preferably substantially thinner in relation to the inner ring 10 than shown in the drawing.

[0030] In Fig. 3 is the bearing ring or the first bearing part 2 from Fig. 2 in a sectional plan view. The inner ring 10 has a hatched first base body 3, which is hollow cylindrical in shape and extends along the bearing axis L. The cylindrical base body 3 has an inner surface 15, on which, for example, a shaft can be arranged. A lipophilic coating 8 is arranged on the base body and completely covers the outside of the base body 3. The lipophilic coating 8 has a T-shaped cross-section. A lipophobic coating 9 is arranged on the lipophilic coating 8 on both sides of a first part 14 of the lipophilic coating 8. The lipophobic coating 9 thus has an inner recess 13 in which the first part 14 of the lipophilic coating 8 is arranged. The thickness of the lipophilic coating 8 and the lipophobic coating 9 is preferably considerably thinner in relation to the inner ring 10 than shown in the drawing.

[0031] Fig. 4 shows the first embodiment of the bearing 1 in a side view with the inner ring 10 of Fig. 2. A second bearing part 5 is arranged concentrically around the first bearing part 2. The second bearing part 5 is designed as an outer ring 11 and has a second base body 6 with a second running surface 7 facing the first bearing part 2 and an outer surface 16 facing away from the first bearing part 2. A lipophilic coating 8 and a lipophobic coating 9 are arranged on the second running surface 7 such that the lipophilic coating 8 is arranged between the second base body 6 and the lipophobic coating 9. A rolling element space 17 is formed between the inner ring 10 and the outer ring 11, in which a plurality of rolling elements 12 are formed, of which only one rolling element 12 is shown and further rolling elements 12 are indicated. The thicknesses of the lipophilic coatings 8 and the lipophobic coatings 9 are preferably substantially thinner in relation to the outer ring 11 and inner ring 10 than shown in the drawing.

[0032] In Fig. 5 shows a first bearing part 2 of a second embodiment of a bearing according to the invention in a sectional plan view. The first bearing part 2 is designed as an inner ring 10 with a first base body 3, wherein the first base body 3 has an inwardly facing inner surface 15. An outwardly facing first running surface 4 is arranged on the first base body 3. The first running surface 4 has a lipophilic coating 8 and a lipophobic coating 9, wherein the lipophilic coating 8 is arranged between the base body 3 and the lipophobic coating 9. In this second embodiment, the lipophobic coating 9 completely covers the lipophilic coating 8 in the radial direction from the bearing axis L outwards. An outer ring 11 (not shown) is constructed accordingly in this second embodiment.

[0033] The second embodiment of the bearing 1 has the advantage during operation that the lipophilic coating 8 is only exposed in areas of greatest mechanical stress when the lipophobic coating 9 wears, subsequently ensuring that sufficient lubricant is present in these areas. The second embodiment therefore has the advantage that lubricant is provided to a greater extent in particularly heavily worn areas by the lipophilic coating 8. The lubricant is thus distributed particularly efficiently in the bearing. This is particularly important when only a relatively small amount of lubricant is present. The thickness of the lipophilic coating 8 and the lipophobic coating 9 is preferably considerably thinner in relation to the inner ring 10 than shown in the drawing. List of reference symbols 1 warehouse 2 First bearing part 3 First basic body 4 First running surface 5 Second bearing part 6 Second basic body 7 Second running surface 8 Lipophilic coating 9 Lipophobic coating 10 inner ring 11 Outer ring 12 rolling elements 13 Inner recess 14 Part One 15 inner surface 16 Exterior area 17 Rolling element chamber L bearing axis 100 first procedural step 200 second process step 300 third process step 400 fourth process step 500 fifth process step

Claims

[1] Bearing (1), comprising a first bearing part (2) with a first base body (3) and a first running surface (4) and a second bearing part (5) with a second base body (6) and a second running surface (7), wherein the first running surface (4) and the second running surface (7) are at least partially facing each other, characterized by that the first running surface (4) at least partially has a lipophilic coating (8) and a lipophobic coating (9), wherein the lipophilic coating (8) is arranged substantially between the first base body (3) and the lipophobic coating (9). [2] Bearing (1) according to claim 1, characterized by that the second running surface (7) has a lipophilic coating (8) and a lipophobic coating (9), wherein the lipophilic coating (8) is arranged substantially between the second base body (6) and the lipophobic coating (9). [3] Bearing (1) according to one of the preceding claims, characterized bythat the bearing (1) is designed as a rolling bearing, wherein the first bearing part (2) is designed as an inner ring (10) or outer ring (11) and the second bearing part (5) is designed accordingly as an outer ring (11) or inner ring (10), wherein at least one rolling body (12) is arranged between the first running surface (4) and the second running surface (7). [4] Bearing (1) according to claim 3, characterized by that the rolling element (12) is arranged in a rolling element cage. [5] Bearing (1) according to one of the preceding claims, characterized by that the lipophobic coating (9) has at least one inner recess (13) in which a first part (14) of the lipophilic coating (8) is arranged, wherein the first part (14) of the lipophilic coating (8) is surrounded by the lipophobic coating (9) on at least two sides. [6] Bearing (1) according to one of the preceding claims, characterized bythat in a first region in which the greatest forces occur during operation of the bearing (1), a layer thickness of the lipophilic coating (8) is thicker than in other regions and / or a layer thickness of the lipophobic coating (9) is thinner than in other regions. [7] Bearing (1) according to one of the preceding claims, characterized by that a lubricant comprising at least one AW and / or EP additive is arranged between the first bearing part (2) and the second bearing part (5). [8] Method for producing a bearing (1), characterized by the steps: - Providing a first bearing part (2) with a first base body (3) and a first running surface (4); - applying a lipophilic coating (8) to the first running surface (4); - applying a lipophobic coating (9) on the lipophilic coating (8); - Providing a second bearing part (5) with a second base body (6) and a second running surface (7); and - Arranging at least one rolling element (12) between the lipophobic coating (9) and the second running surface (7).

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