WO2015176766A1

WO2015176766A1 - Part of a wind turbine

Info

Publication number: WO2015176766A1
Application number: PCT/EP2014/060635
Authority: WO
Inventors: Thomas Krause; Junbiao Lai; Otto Menig; Armin Olschewski; Arno Stubenrauch; Alexander De Vries
Original assignee: Aktiebolaget Skf
Priority date: 2014-05-23
Filing date: 2014-05-23
Publication date: 2015-11-26

Abstract

The invention relates to a part of a wind turbine (1), comprising at least one bearing arrangement (2) by which a rotor (3) is rotatably mounted relative to a housing (4), the bearing arrangement comprising at least one rolling bearing (5). The rolling bearing (5) has at least one first bearing ring (6) connected to the rotor (3) and at least one second bearing ring (7) connected to the housing (4), and rolling elements (8) are disposed between the bearing rings (6, 7). The first bearing ring (6) connected to the rotor (3) has a cylindrical seat surface (9) by which first bearing ring (6) is seated on a cylindrical portion of the rotor (3). In order to prevent the bearing ring from being prone to cracking, according to the invention the cylindrical seat surface (9) of the bearing ring (6) connected to the rotor (3) is produced by a hard turning process. An annular element (13), which is made of a material having a lower rigidity than the material of the first bearing ring (6) and of the rotor (3), is disposed between an end face (10) of the first bearing ring (6) und an end face (11), formed for axial abutment, of a shoulder (12) of the rotor (3).

Description

The invention relates to a part of a wind energy plant, comprising at least one bearing arrangement, with which a rotor is rotatably mounted relative to a housing, wherein the bearing arrangement comprises at least one roller bearing, wherein the roller bearing at least one first bearing ring connected to the rotor and at least one connected to the housing second bearing ring, wherein between the bearing rings rolling elements are arranged, wherein the first bearing ring connected to the rotor has a cylindrical seat, with which it sits on a cylindrical portion of the rotor, preferably with a press fit.

The storage of the rotor of a wind turbine is a demanding warehouse task. The bearing inner ring of the often designed as a tapered roller bearing bearing is often arranged with a press fit on a cylindrical portion of the rotor to permanently fix the bearing ring during its service life on the rotor.

With appropriate load during the use of a rolling bearing, there are sometimes problems with crack formation in the raceway area. In this connection, it is known that cracks are formed on the raceway at high loads and in conjunction with slip occurring on the raceway surface in the axial direction. Therefore, it often comes to fretting corrosion on the bearing bore and the mounted shaft. In addition, a circulation bend is relevant, which acts during the rotation of the bearing ring.

The effects mentioned limit the service life of the rolling bearing and sometimes lead to premature failure of storage. The invention has for its object to provide a generic wind turbine or a part thereof, in which the tendency to cracking on the bearing rings of the storage is at least greatly reduced. Also, the occurrence of fretting corrosion in the region of the cylindrical seat of the bearing is to be reduced by shaft deflection under load.

The solution to this problem by the invention is characterized in that the cylindrical seat surface of the bearing ring connected to the rotor is produced by a hard turning operation, wherein between an end face of the first bearing ring and an end face formed for axial abutment of a shoulder of the rotor Ring element is arranged, which consists of a material having a lower rigidity than the material of the first bearing ring and the rotor. The bearing rings and the rotor preferably consist of steel, while the ring element consists of plastic. The plastic is preferably fiber-reinforced; Polyamide is particularly preferred as the plastic, in particular polyamide 6.6.

The ring element preferably has a rectangular shape in radial section.

The cylindrical seat is optionally subjected to honing in the course of a final machining operation. This is followed by honing in on hard turning. Meanwhile, the cylindrical seat is preferably kept free of an abrasive machining operation; the seat is therefore not ground.

It has surprisingly been found that a particularly good result is achieved when said hard turning and optionally honing process - in subsequent installation of the bearing ring preferred, but not necessarily by means of press fit - is performed to such a degree until a defined maximum radial difference between maximum and minimum value over the circumference of the cylindrical seat. With particular advantage, therefore, the cylindrical seat is designed after hard turning and optionally the subsequent honing such that the radial difference between maximum and minimum value over the circumference of the cylindrical seat is at most equal to the following value:

D i ⁴²⁰⁰ (

5,000 with: the radial difference between the maximum and minimum values of the radius over the circumference of the cylindrical seat in mm;

Diameter of the cylindrical seat of the bearing ring in mm;

Modulus of elasticity of the bearing ring material in N / mm ² (MPa);

critical hoop stress in the bearing ring before application of an external load, possibly after the production of an interference fit, in N / mm ² (MPa);

nominal hoop stress in the bearing ring after its

Mounting, possibly caused by a press fit, m N / mm ² (MPa). The critical hoop stress (< _c ) in the bearing ring before the application of an external load is preferably based on a value between 180 MPa and 220 MPa, preferably of 200 MPa.

The first bearing ring is preferably the bearing inner ring; just as the first bearing ring but also be the bearing outer ring, which is designed accordingly. The rolling bearing is preferably designed as a tapered roller bearing or as a cylindrical roller bearing.

It is therefore provided that the cylindrical seat surface of the bearing ring is produced by a hard turning process, wherein the hard turning process is the last machining step of the seat or wherein the hard turning process is followed by only one honing process. The raceway of the bearing ring is preferably hard-turned; it can also be hard-rolled.

The track and / or the cylindrical seat are preferably burnished. It has been found that the tendency to crack on the raceway of the bearing ring and the tendency to fretting corrosion can be significantly reduced when the proposed design of the bearing assembly is used.

In the drawing, an embodiment of the invention is shown. Show it:

1 shows a radial section of a part of a wind turbine with a bearing arrangement according to the invention,

Fig. 2 for the cylindrical seat of the bearing inner ring of the bearing assembly of FIG. 1, the course of the radius of the seat over the circumference and

3 shows the maximum permissible radial difference between the maximum and minimum values of the radius over the circumference of the cylindrical seating surface as a function of the diameter of the cylindrical seating surface for various nominal circumferential stresses in the bearing ring.

1, the radial section of a part of a wind energy plant 1 is sketched, wherein here a bearing arrangement 2 in the form of a tapered roller bearing can be seen, with which a rotor 3 - this may, but need not, be the main rotor of the wind energy plant - in a housing 4 is stored; Of course, a second, not shown (tapered rollers) bearing is necessary to support the rotor 3 in the housing 4; the bearing assembly 2 in this case therefore comprises two rolling bearings 5 in the form of tapered roller bearings.

The tapered roller bearing 5 has a first bearing ring 6, namely the bearing inner ring, and a second bearing ring 7, namely the bearing outer ring. Between the bearing rings 6, 7 rolling elements 8 are arranged in the usual way in the form of tapered rollers.

The bearing inner ring 6 is seated with a cylindrical seat surface 7 in the embodiment with a press fit on a congruent cylindrical section of the rotor 3. The claw ring 6 has an end face 10, which faces an end face 11 of a f anschförmigen paragraph 12. Between the two end faces 11 and 12, a plastic ring 13 is arranged, which consists of polyamide. The plastic ring 13 has in radial section - as can be seen - a rectangular shape.

In the assembled state, ie when the bearing ring 6 is arranged on the rotor 3, here is an interference fit between bearing ring 6 and rotor 3 before. The bearing ring 6 therefore has a nominal hoop stress < _nom (in this case given in MPa, 1 Pa = 1 N / m ² ), which is caused by the interference fit. In Fig. 2, this voltage is illustrated.

If there is no interference fit but a loss seat, the nominal hoop stress <5 _{nom is} usually zero. But it can also be greater than zero, if, for example, in the case of a tapered roller bearing outer ring due to an axial load and thereby caused thereby widening of the ring, a hoop stress in the ring is caused.

Furthermore, a critical hoop stress o _c (in MPa) can be defined, which may prevail in the bearing ring after the production, but before the application of an external load. This value is material-dependent and may be 200 MPa for steel, for example. In Fig. 2 it is shown how the cylindrical bore 9 with its nominal diameter D (in mm) changed in radius over the circumference of the bearing ring 6, wherein, of course, the course of the bore is shown greatly exaggerated. It turns out that due to the irregularity or waviness there is a radial difference between the maximum and the minimum value of the radius; this difference is denoted by h _c .

The cylindrical bore 9 is presently brought by hard turning in its final form; There is no further mechanical machining of the bore. Alternatively, at most, a honing process can follow. In any case, the cylindrical bore 9 is not processed by grinding.

The raceway of the bearing ring 6 can be made classic, ie that the final contour is made by grinding. However, hard twisting and / or hard rolling is also possible here, possibly followed by honing. A very advantageous result and a substantial improvement against cracks in the raceway are achieved if the radial difference hc does not exceed the following value:

As the course of hc looks, the nominal circumferential stress <5 _nom over the diameter D in FIG. 3 is shown for various values. Here, a critical circumferential stress o _c of 200 MPa is assumed. The value hc represents the critical value of the unevenness of the bore. The formula given above gives the value for h _c in mm, even if the diameter D in mm is used.

It can be seen that the closer the nominal voltage value approaches the critical voltage value, the smaller the degree of h _c, depending on the diameter D, in order to ensure a permanent avoidance of cracks on the track.

Accordingly, in the implementation of the idea according to the invention, the procedure is such that, based on the intended construction and the planned use of the rolling bearing in the wind energy plant, it is first determined with which _{hoop stress} σ _ηοπι, for example, the bearing _{inner ring} will sit on the rotor 3.

This results in particular from the intended fit between the cylindrical seat of the bearing ring 6 and the shaft portion of the rotor 3. For this purpose, appropriate computer programs can be used with which the nominal hoop stress can be determined in the bearing ring, which results from the proposed interference fit.

Then the critical hoop stress o _{c is determined} in the bearing ring, as it is present after the production of the press fit and before the application of an external load in the bearing ring. This value is material-dependent; an example of said voltage has been given above. It can then be determined from the above-mentioned mathematical relationship how large the radial difference hc may be.

The hard turning or honing is then finally performed so that the determined maximum radial difference amount is maintained, which is optionally checked by interactive measurement.

LIST OF REFERENCE NUMBERS

1 wind turbine or part thereof

2 bearing arrangement

3 rotor

4 housing

5 rolling bearings

6 first bearing ring (inner ring)

7 second bearing ring (outer ring)

8 rolling elements (tapered roller)

9 cylindrical seat

10 end face of the first bearing ring

11 face of the paragraph

12 paragraph

13 ring element (plastic ring) h _c radial difference between maximum and minimum

Value of the radius over the circumference of the cylindrical seat D Diameter of the cylindrical seat

E modulus of elasticity of the material of the bearing ring

o _c critical hoop stress in the bearing ring before the application of an external load and possibly after the production of a

press fit

<5 _nom nominal hoop stress in the bearing ring, possibly caused by a press fit

Claims

P a n t a n s p r e c h e

Part of a wind turbine 1. Part of a wind turbine (1), comprising at least one bearing assembly (2) with which a rotor (3) is rotatably mounted relative to a housing (4), wherein the bearing assembly comprises at least one rolling bearing (5), wherein the rolling bearing (5) has at least one first bearing ring (6) connected to the rotor (3) and at least one second bearing ring (7) connected to the housing (4), rolling elements (8) being arranged between the bearing rings (6, 7) are, with the

Rotor (3) connected first bearing ring (6) has a cylindrical seat surface (9), with which it sits on a cylindrical portion of the rotor (3), preferably with a press fit, characterized in that the cylindrical seat surface (9) of the with Rotor (3) connected to the bearing ring (6) is produced by a hard turning process, wherein between an end face (10) of the first bearing ring (6) and formed for axial abutment face (11) of a paragraph (12) of the rotor (3) a ring element (13) is arranged, which consists of a

Material is that has a lower rigidity than the material of the first bearing ring (6) and the rotor (3).

Second part of a wind turbine according to claim 1, characterized in that the bearing rings (6, 7) and the rotor (3) consist of steel and that the ring element (13) consists of plastic, wherein the plastic is preferably fiber-reinforced.

3. Part of a wind turbine according to claim 2, characterized in that the ring element (13) made of polyamide, in particular of polyamide 6.6, consists.

4. Part of a wind turbine according to one of claims 1 to 3, characterized in that the ring element (13) has a rectangular shape in radial section.

5. part of a wind turbine according to one of claims 1 to 4, characterized in that the cylindrical seat surface (9) is subjected to a honing machining as a final machining operation.

6. part of a wind turbine according to one of claims 1 to 5, characterized in that the cylindrical seat surface (9) is free of a Schleifbearbeitungsvor- gang.

7. Part of a wind turbine according to one of claims 1 to 6, characterized in that the cylindrical seat surface (9) after the hard turning and optionally the subsequent honing is formed such that the radial difference amount (h _c ) between maximum and minimum value via the circumference of the cylindrical seat (9) is at most equal to the following value:

With: h _c : radial difference between maximum and minimum

Value of the radius over the circumference of the cylindrical seat (9) in mm;

D: diameter of the cylindrical seat of the bearing ring (6)

m mm;

E: modulus of elasticity of bearing ring material in N / mm ² (MPa);

critical hoop stress in the bearing ring (6) before application of an external load, if necessary after the production of an interference fit, in N / mm ² (MPa);

σ _ηοπι : nominal _{hoop stress} in the bearing ring (6) after its

Mounting, possibly caused by a press fit, m N / mm ² (MPa).

8. part of a wind turbine according to claim 7, characterized in that as a critical hoop stress (o _c ) in the bearing ring (6) prior to the application of an external load a value between 180 MPa and 220 MPa is based, preferably of 200 MPa.

9. part of a wind turbine according to one of claims 1 to 8, characterized in that the first bearing ring (6) is a bearing inner ring.

10. part of a method according to one of claims 1 to 8, characterized in that the first bearing ring (7) is a bearing outer ring.

1 1. Part of a wind turbine according to one of claims 1 to 10, characterized in that the rolling bearing (5) is a tapered roller bearing or cylindrical roller bearing.