DE102015201174B4 - Coated bearing and method for its manufacture - Google Patents

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) at least partially face each other, characterized in 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).

Description

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 are at least partially facing each other. The first running surface has at least partially a lipophilic coating and a lipophobic coating, wherein the lipophilic coating is arranged essentially between the first base body and the lipophobic coating. Furthermore, the invention relates to a method for its production.

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 one another around a common axis. In order to enable the bearing rings to slide against one another as smoothly as possible, rolling elements are arranged between the bearing rings, which roll or roll on the running surfaces of the bearing rings. Linear guides or ball screws essentially work according to the same principle, with a carriage sliding on a guide rail in linear guides and a nut sliding on a spindle in ball screws.

To reduce the rolling resistance of rolling bearings, linear guides or ball screws, to ensure that they run as smoothly and evenly as possible, to reduce operating temperatures and to achieve low wear, the rolling elements and running surfaces have a surface that is as smooth and even as possible and are made of a hard, low-wear, preferably corrosion-resistant material. In addition, rolling bearings, linear guides and ball screws are lubricated, e.g. with grease or oil, to further reduce rolling resistance.

During operation, different zones of the rolling bearings, linear guides or ball screws are exposed to different loads, which cause different levels of wear. For example, high point pressure forces on rolling bearings, linear guides or ball screws can initially lead to a local displacement of the lubricant. Centrifugal forces also help to displace the lubricant towards the bearing seals. If relubrication is not carried out, this can lead to local dry running of the bearing, so that in some places on the bearing there is no longer enough lubricant to ensure adequate or continuous lubrication of the bearing. In order to ensure the operational reliability of such a bearing, the bearing must be supplied with lubricant within a certain relubrication cycle.

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

The publication JP 2014- 95 437 A describes a thrust ball bearing having a pair of races arranged parallel to each other so that they are separated from each other in the axial direction. A plurality of balls are arranged between the race pair so that they roll therebetween. A retainer is arranged between the race pair and holds the plurality of balls at substantially equal intervals. A lipophilic treatment is carried out on the rolling surfaces of the race pair.

The publication DE 11 2008 000 540 T5 describes a grease for a high speed bearing. This grease includes a urea grease containing a urea-based compound as a thickener thereof and a non-urea grease containing a non-urea-based thickener mixed with the urea grease.

The publication DE 10 2010 031 439 A1 describes a rolling bearing. This has 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 that was produced by a chemical deposition process in such a way that it exhibits micro-brittle behavior.

The publication JP 2007- 10 114 A describes a rolling bearing for a transmission. There, an oil coating is applied to at least an inner ring, an outer ring and a 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.

The publication US 2012 / 0 148 180 A1 shows 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 which is load concentration portion between the shaft member and the support member. Sliding surface portions having higher oil repellency than the sliding surface portion are respectively provided on upstream and downstream sides of the sliding surface portion in a flow direction of the lubricating oil.

The object of the present invention is therefore to provide a bearing and a method for producing 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 has an improved distribution of lubricant even under high mechanical loads and also less wear, a longer service life and a longer relubrication cycle than conventional bearings.

This object is achieved by a bearing according to claim 1. The 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.

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.

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

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 have, e.g. a low roughness value and/or are designed to be particularly hard or erosion-resistant.

The first running surface has at least a partial lipophilic coating. A lipophilic coating has the special property of attracting grease or lubricants. Such a layer is particularly advantageous in areas of the bearing in which particularly high mechanical forces act during operation of the bearing, so that at least in these areas there is still sufficient lubricant even after the bearing has been in operation for a long time. It is therefore 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.

A lipophobic coating has the special property of repelling grease or lubricants. A lipophobic coating can be applied to 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 removes the lipophobic coating, exposing the lipophilic coating at these points and attracting lubricant. This ensures that more lubricant is applied in areas of the bearing that are subject to particularly high mechanical stress than in areas that are less stressed. This has the advantage that even if there is little lubricant, 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. in edge areas, that are exposed to relatively low mechanical stress or through which the lubricant could escape from the bearing. This has the advantage that the lubricant is concentrated in particular on areas that are subject to increased stress and that the lubricant is at least partially prevented from escaping from the bearing. Such bearings have lower internal friction values, an increased service life and an extended relubrication cycle even after long periods of operation.

The second running surface preferably has a lipophilic coating and a lipophobic coating, the lipophilic coating being arranged essentially 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 has lower internal friction values, an increased service life and an extended relubrication cycle even after prolonged operation.

The bearing is further preferably designed as a rolling bearing, wherein the first bearing part is designed as an inner ring or outer ring and the second bearing part is designed as an outer ring or inner ring. At least one rolling element is arranged between the first running surface and the second running surface. net. The rolling bearing preferably has a plurality of rolling elements in order to better distribute forces acting between the inner ring and the outer ring on the running surfaces or the coatings of the running surfaces. Alternatively, the bearing is designed as a linear guide or ball screw drive.

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 from one another and do not roll against one another during operation. This reduces internal friction and thus wear on the bearing and extends its service life.

Preferably, the bearing is designed as a rolling bearing. Such bearings have a particularly high load in some areas, so that a supply of lubricant in these areas can be advantageously improved by means of such a coating.

It is preferred that the lipophobic coating has at least one inner recess in which a first part of the lipophilic coating is arranged, the first part of the lipophilic coating being surrounded by the lipophobic coating on at least two sides. In a preferred embodiment, the lipophilic coating has a T-shaped cross-section. The lipophobic coating is also preferably designed such that in one area the lipophilic coating is not covered by the lipophobic coating. Thus, for example, an area 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 area between the lipophilic coating and the second bearing part. This has the advantage that even with a bearing that is not worn 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 not necessary because the lipophilic coating is already exposed.

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 a small amount of wear of the lipophobic coating is required until the positive properties of the lipophilic coating in the first region come into effect.

It is particularly advantageous to arrange a lubricant between the first bearing part and the second bearing part, which has at least one AW and/or EP additive. AW additives (anti wear) are additives for a lubricant that reduce abrasive wear. EP additives (extreme pressure) are additives for a lubricant that prevent welding of metal bearing parts that rub against each other under pressure.

• - Bereitstellen eines ersten Lagerteils mit einem ersten Grundkörper und einer ersten Lauffläche;
• - Auftragen einer lipophilen Beschichtung auf die erste Lauffläche;
• - Auftragen einer lipophoben Beschichtung auf der lipophilen Beschichtung;
• - Bereitstellen eines zweiten Lagerteils mit einem zweiten Grundkörper und einer zweiten Lauffläche; und
• - Anordnen mindestens eines Wälzkörpers zwischen der lipophoben Beschichtung und der zweiten Lauffläche.

Furthermore, the object is achieved by a method for producing a bearing with 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.

With this method, a bearing according to the invention can be produced.

• 1 ein Ablaufdiagramm des erfindungsgemäßen Verfahrens zur Herstellung eines Lagers;
• 2 eine Draufsicht auf einen Lagerring einer ersten Ausführungsform eines Lagers;
• 3 eine geschnittene Draufsicht des Lagerrings aus 2
• 4 eine Seitenansicht der ersten Ausführungsform des Lagers mit dem Lagerring aus 2, und
• 5 eine geschnittene Draufsicht eines Lagerrings einer zweiten Ausführungsform eines Lagers.

The invention will be explained in more detail below with reference to a drawing. The drawings show schematically:

• 1 a flow chart of the method according to the invention for producing a bearing;
• 2 a plan view of a bearing ring of a first embodiment of a bearing;
• 3 a sectional top view of the bearing ring from 2
• 4 a side view of the first embodiment of the bearing with the bearing ring from 2 , and
• 5 a sectional plan view of a bearing ring of a second embodiment of a bearing.

In 1 A process for producing a rolling element cage is shown in a flow chart. In the first process step 100, a first bearing part 2 with a first base body and a first running surface 4 is provided. In the second In 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 areas 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 areas 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 running surface 7, which can also have a lipophilic coating 8, which is 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 running surface 7. 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.

2 shows a top 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 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 designed to be significantly thinner in relation to the inner ring 10 than shown in the drawing.

In 3 the bearing ring or the first bearing part 2 is made of 2 shown 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, which completely covers the base body 3 from the outside. 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 significantly thinner in relation to the inner ring 10 than shown in the drawing.

4 shows the first embodiment of the bearing 1 in a side view with the inner ring 10 of 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. Between the inner ring 10 and the outer ring 11, a rolling element space 17 is formed 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.

In 5 a first bearing part 2 of a second embodiment of a bearing according to the invention is shown 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.

The second embodiment of the bearing 1 has the advantage during operation that the lipophilic coating 8 is only exposed in areas of highest mechanical stress when the lipophobic coating 9 wears out, and then ensures that sufficient lubricant is available in these areas. The second embodiment therefore has the advantage that lubricant is provided in a greater amount 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 there is only a relatively small amount of lubricant. The thickness of the lipophilic coating 8 and the lipophobic coating 9 is preferably made significantly thinner in relation to the inner ring 10 than shown in the drawing.

list of reference symbols

1

camp

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

First Part

15

inner surface

16

outer surface

17

rolling element space

L

bearing axis

100

first procedural step

200

second procedural step

300

third procedural step

400

fourth procedural step

500

fifth procedural step

Claims (8)

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) at least partially face each other, characterized in 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). camp (1) after claim 1 , characterized in 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). Bearing (1) according to one of the preceding claims, characterized in that 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). camp (1) after claim 3 , characterized in that the rolling element (12) is arranged in a rolling element cage. Bearing (1) according to one of the preceding claims, characterized in 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. Bearing (1) according to one of the preceding claims, characterized in that 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. Bearing (1) according to one of the preceding claims, characterized in 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). 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) to 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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