DE102012212688B3 - Larger bearing ring e.g. inner ring, for e.g. roller bearing of wind-power plant, has surface area coated with primary layers of paint on polyurethane base and covering layer of another paint such that covering layer covers primary layers - Google Patents

Abstract

The ring has a surface area (2) coated with primary layers (3) of paint on polyurethane base and a covering layer (4) of another paint on polyurethane base such that the covering layer covers the primary layers. Zinc is added to the surface area, and iron mica is added to the covering layer. The surface area is not radiated. The paints are formed identical regarding the polyurethane base, where the paints are one-component paint and moisture-hardened. The primary layers and the covering layer are attached one above the other on the surface area. An independent claim is also included for a method for protecting a bearing ring of a rolling bearing or a slide bearing from corrosion.

Description

The invention relates to a corrosion-protected bearing ring of a rolling bearing or a sliding bearing, a bearing with the bearing ring and a method for protecting a bearing ring from corrosion.

Bearings are sometimes exposed to corrosive environmental conditions. This is true, for example, for bearings that are installed in wind turbines and due to design or cost reasons are not installed in a housing that protects, for example, from weather conditions. Particularly problematic is the situation with wind turbines that are built directly on the coast or even in the sea. In this case, the bearings may come into contact with highly corrosive salt water.

To protect against corrosion, the bearings can be provided with a coating. As anticorrosive coatings are usually paints based on epoxy resin used. To ensure reliable corrosion protection, it is necessary that the coating adheres firmly to the substrate. As a rule, a preparation of the underground is a prerequisite for this. A known measure for achieving a good adhesion of a coating is to roughen the surface to be coated. The roughening is done in many cases by a blast treatment of the surface to be coated. For this purpose, abrasive particles are thrown against the surface to be coated. However, a blast treatment of a bearing component involves the risk that remaining abrasive particles damage the bearing during operation or is associated with a very high cost for the most complete removal of the abrasive particles from the bearing component.

From the DE 28 55 120 A1 , of the EP 0 832 908 A1 and the DE 10 2005 026 523 A1 Each anticorrosion coatings are known in which at least one polyurethane-based layer can be formed.

The corrosion of exposed outer surfaces, for example on main rotor bearings of wind turbines is usually not a critical problem function, but is usually undesirable, so that countermeasures are taken. The functionally essential rolling and sliding surfaces in the bearing interior are sealed and protected with grease. The seal running surface forms a greasy film or even fat bead, which also protects the areas adjacent the seal running surface. Taking into account the corrosion values of unprotected steel, even in maritime environments, for example 10 mm in 100 years in one-sided saltwater-treated steel hydraulic structures, it becomes clear that a functional problem of the main rotor bearing due to external surface corrosion is hardly to be expected.

In conventional corrosion protection measures on such main rotor bearing outer surfaces these are blasted, z. B. corundum blasted, and then by thermal zinc spraying, so zinc flame spraying or zinc plasma spraying coated. Likewise, in all conventional painting the surfaces are always blasted, usually on Sa 2.5. Blasting uses hard particles similar to grinding wheel or sand grains. Zinc spraying also does not produce metal particles bound to the surface. It is extremely difficult, if not impossible, to get a part such as a main rotor bearing or a main rotor bearing ring completely free of particles after such a process. Even covering the functional surfaces leads to the removal of the covers to back contamination, as accumulate everywhere loose particles. The cleaning of large annular components due to their shape and the associated steady Schmutzrekontamination leads to cleaning results similar to a dilution series, where the value zero is difficult to achieve.

It is therefore of statistical probability to find in some such treated bearings even after careful cleaning as possible some Abrasivstoffpartikel. It is mathematically demonstrable that even small amounts of such particles can induce surface damage during operation of the bearing and can lead to a significant reduction in bearing life.

The primary objective of all technical measures for wind energy storage facilities is to achieve the highest possible service life. It is therefore inconclusive to take the considerable risk with measures for hardly increasing the useful life of the external corrosion protection, to significantly reduce the service life and performance due to internal contamination and to reduce the reliability of the installation.

The object of the invention was therefore to find an effective and economical corrosion protection for the outer surfaces of a bearing component, which has no pollution potential in pretreatment and order and thus represents no risk for the actual useful life and performance of the current camp.

This object is achieved by the feature combinations of the independent claims.

The bearing ring according to the invention for a roller bearing or a slide bearing has a surface area which is provided with a plurality of base layers of a first polyurethane-based paint, the zinc is added and a cover layer of a second polyurethane-based lacquer, the iron mica is added, is coated such that the cover layer covers the base layers.

The invention has the advantage that with very little effort and in a reliable manner, a very effective corrosion protection can be achieved.

The first paint has such a high adhesive strength even on a non-roughened surface that no complex and dangerous for the bearing ring surface preparation, in particular no blasting of the surface of the bearing ring is required. Thus, it is possible that the surface area is not blasted. In addition to the advantage of simplifying the process, this eliminates the risk that abrasive residues from the blasting process will damage the bearing ring during operation.

The layer thickness of the base layers may each be 30 .mu.m to 90 .mu.m, preferably 40 .mu.m to 80 .mu.m.

The layer thickness of the cover layer may be 40 μm to 100 μm, preferably 50 μm to 90 μm.

The first lacquer and the second lacquer may be identical in terms of their polyurethane base. This reduces the risk of problems due to incompatibilities between the first paint and the second paint.

The first paint and / or the second paint may be a one-component paint. This can be processed with very little effort and without the risk of mixing errors. But it is also possible to form the first paint and / or the second paint as a two-component paint.

The first lacquer and / or the second lacquer may be moisture-curing. This has the advantage that the progress of the hardening process can be estimated very easily with known air humidity.

The bearing component may be designed such that at least the predominant part of the coated surface area does not come to rest on a mating surface after ready-to-use assembly of the bearing ring.

The bearing ring may be formed in particular as an inner ring or an outer ring.

The invention further relates to a bearing ring of a rolling bearing or plain bearing having a non-blasted surface area coated with a plurality of base layers of a polyurethane-based paint to which zinc has been added.

In addition, the invention relates to a bearing with a bearing ring according to the invention.

The bearing can be designed as a large warehouse. In particular, the bearing may be formed as a component of a wind turbine.

Furthermore, the invention relates to a method for protecting a bearing ring of a rolling bearing or a sliding bearing from corrosion, wherein a plurality of base layers of a first polyurethane-based lacquer, the zinc is added successively to a surface region of the bearing ring and successively applied to the last Base layer, a cover layer of a second polyurethane-based lacquer is added to the iron mica is applied.

All information given below regarding percentages of substances is based on volume, ie. H. % is the vol%.

The invention will be explained below with reference to the embodiments illustrated in the drawings.

Show it

1 a schematic representation of an embodiment of a coated bearing component and

2 a further embodiment of the coated bearing component in a 1 corresponding representation.

1 shows a schematic representation of an embodiment of a coated bearing component 1 , The illustration is greatly simplified and not to scale and shows only a section of the bearing component 1 , At the bearing component 1 it is a bearing ring of a rolling or sliding bearing. In particular, the bearing component 1 formed as a component of a large warehouse of a wind turbine or other large machine. The bearing component 1 can be made of steel.

On a surface area 2 of the bearing component 1 are on top of each other three base layers 3 and a cover layer 4 applied. This will cause the bearing component 1 within the surface area 2 protected against corrosion. The surface area 2 can extend over the entire surface of the bearing component 1 excluding the running and sliding tracks or only over a portion of the surface of the bearing component 1 extend. How else is explained in detail, takes place before the coating of the bearing component 1 no blasting of the surface area 2 with abrasive particles, but the bottom layer 3 is directly on the usually ground and degreased surface area 2 of the bearing component 1 applied.

The base layers 3 each have a thickness of 60 microns and consist of a moisture-curing one-component polyurethane-based paint to which zinc particles are added. An epoxy resin lacquer does not have a sufficient adhesive strength under the conditions mentioned and requires a blasted substrate. In principle, the base layers are 3 Layer thicknesses of about 30 microns to about 90 microns possible. The preferred range is between 40 microns and 80 microns. If the layer thickness chosen too low, there is no sufficient corrosion protection. In principle, it is also possible for the base layers 3 to use a two-component polyurethane-based paint, in turn, zinc particles are added. The proportion of zinc particles in the dried base layers 3 is about 60% to 90%. As with all other information regarding percentages of substances, these values refer to the volume, ie the percentages are by vol%.

The cover layer 4 has a thickness of about 40 microns to about 100 microns, preferably 50 microns to 90 microns, on. Typically, the thickness of the cover layer is 4 about 60 microns and thus corresponds to the thickness of the base layers 3 , In the tendency becomes the thickness of the cover layer 4 but rather a bit thicker than the thicknesses of the base layers 3 , The cover layer 4 consists of a moisture-curing one-component polyurethane-based paint, in which instead of zinc iron mica particles in platelet form are added. Analogous to the base layers 3 can also for the topcoat 4 a two-component polyurethane-based paint can be used.

In the 1 shown layer sequence represents a very effective corrosion protection. It can thus reach the level C4 / 10 years to C5 / 10 years according to EN ISO 12944-2: 2000. By using several thin base layers 3 is compared to using a single thick base coat 3 the through-drying when applying the base layers 3 improved. In addition, the porosity is reduced and it reduces the internal stresses that can lead to delamination in extreme cases. This is particularly due to the fact that when drying the base layers 3 resulting carbon dioxide and solvent from a thin base layer 3 escape better than from a thick base layer 3 , When using a one-component polyurethane-based paint, water vapor can also diffuse more easily for cross-linking. That in the base layers 3 contained zinc protects the steel of the bearing component 1 before corrosion.

The cover protects the base layers 3 due to the comparatively high hardness of the iron mica contained therein against mechanical effects. The iron mica platelets form a kind of protective armor. In addition, a high diffusion-tightness is achieved by the platelet-like shape of the iron mica, so that hardly any water vapor up to the base layers 3 and in particular can penetrate to the zinc particles contained therein. In addition, in a combination of zinc particles and iron mica favorable conditions with regard to the electrochemical series, since the system then contains a total of a small number of metals.

If the base layers 3 and the topcoat 4 Based on the same polyurethane base, embrittlement, which can be caused by diffusion of paint components in the adjacent layer and stresses that can lead to a lifting and spalling of layers can be particularly reliably avoided.

Alternatively to the in 1 illustrated embodiment, the bearing component 1 also with only two base layers 3 and a cover layer 4 be coated. The other parameters may be for the system with two base layers 3 to be kept.

To train the in 1 The following and similar sequence of sequences can be carried out as follows:
The bearing component 1 , whose surface is usually ground, is cleaned and thereby in the surface area 2 in which the coating should take place activated. This can be done, for example, by treatment first with alcohol and then with acetone. In particular, an activation should take place above 72 mN / m. Neither before nor after activation, the bearing component 1 blasted with abrasive particles and thereby roughened. Unlike silicates, for example, polyurethane also adheres very well to increased binder content on non-blasted steel surfaces if the layer thickness is selected appropriately. In the case of an adhesion test according to DIN EN ISO 4624, the tearing value on a ground, non-blasted steel surface is typically 17-20 MPa, the break occurring when tearing off within the coating.

On the activated surface area 2 For example, by means of a roller, the first base layer 3 applied. For this purpose, the polyurethane-based paint previously zinc particles are added. The internal electrical contact in the paint and thus the corrosion protection can be improved when not only zinc powder is used, but also a proportion of zinc flakes. In a mixture of zinc powder and zinc flakes, the optimum packing density is achieved with more contact surfaces among each other.

For different target layer thicknesses of the base layer 3 the same basic recipe with different powder grains is used. The different layer thickness is adjusted by the grain size of the powder used and at the same time by the viscosity of the polyurethane binder. Higher solvent addition (VOC) lowers the viscosity and makes the layer thinner - and vice versa. The viscosity of the paint can also be influenced by the degree of precrosslinking of the polyurethane and by the rheology. A lower pre-crosslinking corresponds to a lower viscosity.

The ready mixed paint for the base coat 3 contains a solvent content (eg naphtha) of 20% to 40%, in particular 30%.

• – 20–40%, insbesondere 30%, einkomponentiges feuchtigkeitshärtendes Polyurethan (Basis aromatisches Polyisocyanat),
• – 50–80% Feststoffanteil,
• – bis zu 10% Additive (fest oder flüssig).

After deduction of the solvent content, the remaining dry content of the paint is composed as follows, using as a reference for the percentages the total dry content:

• - 20-40%, in particular 30%, one-component moisture-curing polyurethane (based on aromatic polyisocyanate),
• - 50-80% solids,
• - up to 10% additives (solid or liquid).

In such a composition, the paint is easy and evenly applied, fast drying, high adhesion and chemically and mechanically stable.

With a polyurethane content of less than 20%, problems arise with respect to the adhesion of the paint to the surface of the bearing component 1 on; above 40%, the corrosion protection effect of the paint is no longer guaranteed, since it can no longer be assumed that there is a continuous electrical connection over the entire volume of the paint layer.

The curing of the paint takes place via a crosslinking of functional ends (isocyanate) of the polyurethane system. The volume of the dried layer is about 70% of the volume of the wet layer.

After sufficient flash-off during which a large part of the carbon dioxide formed in the drying reaction from the first base layer 3 escapes, and for which depending on the temperature and humidity about three to eight hours are to be estimated, is on the first base layer 3 a second base layer 3 applied. The same procedure is used as for the first base layer 3 and a lacquer is used which, in terms of its polyurethane base and with regard to the added zinc, is identical to the lacquer of the first base coat 3 is formed so that there is an identical with respect to the adhesion and corrosion protection properties paint composition. To allow a better control of the paint application, the paint for the second base coat 3 other color pigments may be added than the lacquer for the first base coat 3 , For the education of the second base class 3 eliminates the activation of the surface area 2 of the bearing component 1 as a preparatory action, as this by the first base layer 3 is covered.

After bleeding the second base layer 3 becomes analogously a third base layer 3 applied, for the paint composition that for the first and second base layer 3 The same applies analogously. In particular, there is the possibility that the paint for the third base layer 3 completely identical to the paint for the first base coat 3 is trained. Through the second base layer 3 they are in the first base layer 3 remaining through pores largely closed. A further reduction of the continuous pores takes place through the third base layer 3

Next is the topcoat 4 to the topmost base layer 3 applied. Again, first wait until the third base layer 3 sufficiently ventilated. The one for the formation of the top layer 4 envisaged paint is mixed in place of zinc iron mica. It can for the cover layer 4 the starting material is the identical lacquer - but without zinc - as in the production of the base coats 3 can be used, ie the paints can be identical in terms of their polyurethane base. This guarantees good compatibility of the topcoat 4 with the base layers 3 and avoids undesirable reactions leading to damage to the topcoat 4 or the base layers 3 could lead. The cover layer 4 can be applied for example with a paint roller. In a similar way as for the base layers 3 is described in the formation of the cover layer 4 the desired layer thickness is formed in the dried state by adjusting the viscosity or other parameters or by selecting the platelet size of the added iron mica.

After curing the topcoat 4 and the base layers 3 they protect the bearing component 1 very effective and against corrosion for a long time.

If the bearing component 1 should be used in a less corrosive environment, for example, in a wind turbine that is installed inland, a different type of coating can be used. This is based on 2 explained in more detail.

2 shows a further embodiment of the coated bearing component 1 in a 1 corresponding representation. This in 2 illustrated bearing component 1 differs from the embodiment of 1 in terms of coating. According to 2 are just two base layers 3 on the surface area 2 of the bearing component 1 applied. The base layers 3 are each formed in an identical manner and in an identical manner to the surface area 2 of the bearing component 1 applied, as based on 1 again, with no previous blast treatment of the surface area 2 of the bearing component 1 he follows. Accordingly, the base layers 3 in 2 each have a thickness of 60 microns and consist of a moisture-curing one-component polyurethane-based paint to which zinc particles are added. The missing cover layer 4 has the consequence that in the embodiment of 2 no high corrosion resistance as in the embodiment of 1 is reached. A slight improvement can be made by a third base layer 3 achieve. The corrosion resistance of in 1 but illustrated embodiment is not achieved.

Analogous to the embodiment of 1 are also at the 2 Modifications possible, such as the use of a two-component paint instead of a one-component paint.

LIST OF REFERENCE NUMBERS

1

bearing component

2

surface area

3

base layer

4

topcoat

Claims (10)

Bearing ring of a rolling bearing or plain bearing with a surface area ( 2 ), which has several base layers ( 3 ) of a first polyurethane-based lacquer to which zinc has been added and a topcoat ( 4 ) of a second polyurethane-based lacquer to which iron mica has been added in such a way that the top layer ( 4 ) the base layers ( 3 ) covers. Bearing ring according to claim 1, wherein the surface area ( 2 ) is not blasted. Bearing ring according to one of the preceding claims, wherein the first paint and the second paint are identical in terms of their polyurethane base. Bearing ring according to one of the preceding claims, wherein the first lacquer and / or the second lacquer is a one-component lacquer. Bearing ring according to one of the preceding claims, wherein the first lacquer and / or the second lacquer is moisture-cured. Bearing ring of a rolling bearing or plain bearing with a non-blasted surface area ( 2 ), which has several base layers ( 3 ) of a polyurethane-based varnish to which zinc has been added. Bearing with a bearing ring ( 1 ) according to any one of the preceding claims. Bearing according to claim 7, wherein the bearing is designed as a large warehouse. Bearing according to one of claims 7 or 8, wherein the bearing is formed as a component of a wind turbine. Method for protecting a bearing ring of a rolling bearing or plain bearing ( 1 ) against corrosion, with a surface area ( 2 ) of the bearing ring ( 1 ) successively several base layers ( 3 ) of a first polyurethane-based lacquer to which zinc has been added and applied to the last base coat ( 3 ) a cover layer ( 4 ) of a second polyurethane-based varnish to which iron mica is added.

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