Method for hardening the surface of a component in a wind turbine

Abstract

A method for hardening a surface of a component in a wind turbine is disclosed. The component to be hardened includes a surface and the surface is applied with a blasting material by ultrasound waves. The component is a part of a drive or a drive housing, a bearing surface, a gear wheel or a pinion. The ultrasound waves are emitted with the aid of a piezo electric transducer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of German application No. 10 2010 006 094.1 filed Jan. 28, 2010, which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a method for hardening the surface of a component in a wind turbine, in particular the surface outer layer of a component in a wind turbine.

BACKGROUND OF THE INVENTION

Microscopic cracks in the respective part frequently appear, as a result of high Hertzian pressure, in heavily loaded regions of drives, for instance in heavily stressed regions of bearing surfaces of drives or tooth flanks of gear wheels. Microscopic cracks of this type may result in premature faults and corresponding failures of the respective part. The crack formation frequently occurs on the outer surfaces and/or in the region of the periphery of the heavily loaded contact surfaces. Micro defects of this type reduce the operating time and the service life of the respective part, for instance of the drive and the drive housing. In numerous plants, for instance in wind turbines, the thus necessary replacement of the respective component, for instance of the drive or parts thereof, is generally complicated and expensive.

The hardening processes and processing technologies used to date, such as rolling, hard turning or blasting material peening, do not achieve increased internal stress particularly of the heavily loaded contact regions and therefore reduce the high tensile load. Only internal stresses of a maximum of 400 MPa can currently be achieved.

DE 10 2007 009 470 A1 and WO 93/20247 A1 describe methods for the surface peening, in particular for the ultrasound ball peening of a part, in particular a gas turbine. Ultrasound blasting material peening is characterized in that a sub-region of the surface of a part is hardened by applying a blasting material. The blasting material preferably consists of small balls with a diameter of less than 4 mm.

SUMMARY OF THE INVENTION

The object of the present invention consists in providing an advantageous method for hardening the surface of a component in a wind turbine. This object is achieved by a method as claimed in the independent claim. The dependent claims contain further advantageous embodiments of the invention.

The inventive method for hardening the surface of a component in a wind turbine is characterized in that the component to be hardened has a surface and the surface is applied with a blasting material by means of ultrasound waves. The component to be hardened can be in particular parts of bearings or the drive of the wind turbine. In particular, the component can include a part of a drive or a drive housing, a bearing surface, in particular of a bearing, for instance a bearing surface of a roller bearing, or of a drive, a gear wheel or a pinion, in particular a drive pinion. The component to be hardened can be in particular a tooth flank of a gear wheel.

By means of ultrasound blasting material peening, in other words applying the surface to be hardened with a blasting material by means of ultrasound waves, the internal stress of the respective component is increased and the susceptibility to cracking is thus reduced. The service life and the operating time of the respective component are increased in this way by approximately 20%.

The ultrasound waves can preferably be emitted with the aid of a piezo electric transducer. For instance, ultrasound waves can be emitted with a frequency between 10 kHz and 30 kHz, preferably 20 kHz. It is particularly advantageous if the ultrasound waves are amplified. This can take place for instance with the aid of an acoustic amplifier.

The blasting material can preferably include a relatively heavy material, like for instance tungsten carbide, and/or consist of tungsten carbide. In addition, the blasting material can include balls. The blasting material can preferably include balls with a diameter of more than 1 mm, advantageously with a diameter of more than 5 mm, or can exclusively consist of blasting balls with a diameter of more than 1 mm, advantageously with a diameter of more than 5 mm. It has emerged that the use of tungsten carbide balls and the use of balls with a relatively large diameter, in particular of more than 5 mm, can achieve particularly high internal compressive stress results, since the balls are in this case embodied in a relatively large and heavy fashion.

With the aid of the inventive method, internal stresses, in particular of bearing surfaces of wind turbine bearings and wind turbine drives, for instance gear wheel drive systems, of more than 800 MPa can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features, characteristics and advantages of the present invention are described in more detail below with reference to an exemplary embodiment with respect to the appended figures. Here the described features are advantageous both individually and also in combination with one another.

FIG. 1 shows a schematic representation of a wind power plant.

FIG. 2 shows a schematic representation of a first cross-section through a part of an apparatus for implementing the inventive method on a gear wheel.

FIG. 3 shows a schematic representation of a second cross-section through a part of an apparatus for implementing the inventive method on a gear wheel.

FIG. 4 shows a schematic representation of a first cross-section through a part of an apparatus for implementing the inventive method on the interior surface of a roller bearing outer ring.

FIG. 5 shows a schematic representation of a second cross-section through a part of an apparatus for implementing the inventive method on the inner surface of a roller bearing outer ring.

FIG. 6 shows a schematic representation of a first cross-section through a part of an apparatus for implementing the inventive method on the outer surface of a roller bearing inner ring.

FIG. 7 shows a schematic representation of a second section through a part of an apparatus for implementing the inventive method on the outer surface of a roller bearing inner ring.

DETAILED DESCRIPTION OF THE INVENTION

An exemplary embodiment of the invention is described in more detail below with the aid of FIGS. 1 to 7. FIG. 1 shows a schematic representation of a wind power plant 1. The wind power plant 1 includes a tower 2, a pod 3 and a rotor hub 4. The pod 3 is arranged on the tower 2. The rotatably mounted rotor hub 4 is arranged on the pod 3. At least one rotor blade 5 is fastened to the rotor hub 4. The wind power plant 1 typically includes two or three rotor blades 5.

The wind power plant 1 also includes at least a rotational axis 6, a main bearing 30, a drive 7, a brake 8 and a generator 9. The rotational axis 6, the main bearing 30, the drive 7, the brake 8 and the generator 9 are arranged inside the pod 3. A center to center difference is essentially possible in the drive 7. Different components can therefore have different rotational axes. In addition, the wind power plant 1 can also be embodied without drives.

FIG. 2 shows a schematic representation of a cross-section through part of an apparatus for implementing the inventive ultrasound shot peening method. The apparatus includes a peening chamber 10, within which the shot peening is implemented. Part of a component to be hardened, in the present exemplary embodiment part of a drive pinion 11, is arranged within the peening chamber 10. The drive pinion 11 includes a rotational axis 13. FIG. 2 shows a cross-section through the drive pinion 11 along the rotational axis 13, in other words an axial cross-section. The drive pinion 11 includes a number of teeth 24, of which at least one part is arranged within the peening chamber 10. The surface to be hardened of the teeth 24 of the gear pinion 11 is identified with reference character 26.

At least one part of a sonotrode 17 is also arranged within the peening chamber 10. The sonotrode 17 is preferably arranged opposite the surface 26 to be hardened. The sonotrode 17 is connected to an amplifier 16, preferably an acoustic amplifier. The amplifier 16 is also connected to a transducer, preferably in the form of a piezo electric emitter.

A cavity 27 is disposed between the sonotrode 17 and the drive pinion 11 within the peening chamber 10. A number of balls 18 are arranged in this cavity 27. The balls 18 preferably consist of tungsten carbide. The balls 18 advantageously have a diameter of more than 1 mm, preferably of more than 5 mm. A homogenous hardening of the surface 26 is herewith achieved.

In order to implement the inventive method, ultrasound waves with a frequency between 30 kHz and 10 kHz, advantageously with a frequency of 20 kHz, are generated with the aid of the transducer 14. The ultrasound waves are then amplified with the aid of the acoustic amplifier 16. The amplified ultrasound waves are transmitted by means of the sonotrode into the peening chamber 10, and/or into the cavity 27 disposed therein. The ultrasound waves cause the balls 18 inside the peening chamber 10 to vibrate and move inside the peening chamber 10. The balls 18 are in this way reflected by the surface of the sonotrode 17, by the surface 26 to be hardened and by the walls of the peening chamber 10. In addition, the balls 18 collide with one another. As a result of the random scattering of the balls 18, a homogenous treatment of the surface 26 to be hardened is achieved.

FIG. 3 shows a schematic representation of a cross-section according to FIG. 2 through an apparatus for implementing the inventive method. Contrary to FIG. 2, the drive pinion 12 is shown in FIG. 3 in a radial cross-section, in other words in a cross-section at right angles to the rotational axis 13. The view of the remaining parts in FIG. 3 can essentially correspond to the cross-section shown in FIG. 2, with only the part 11 and/or 12 to be hardened being arranged differently. Alternatively the cross-section shown in FIG. 3, in respect of all parts, may be a cross-section at right angles to the cross-section shown in FIG. 2. The longitudinal axis of the apparatus is identified in both FIGS. 2 and 3 with reference character 15.

The teeth 24 of the drive pinion 12 shown in FIG. 3 include tooth flanks 25. With the aid of the inventive method, the tooth flanks 25 can in particular be effectively hardened, since as a result of the random scattering of the balls, the whole surface to be hardened can be evenly treated.

FIGS. 4 and 5 show a cross-section through part of an apparatus for implementing the inventive method. FIGS. 4 and 5 show the hardening of the inner bearing surface 21 of a roller bearing outer ring 19 and/or 20. Here the roller bearing outer ring 19 in FIG. 4 is shown in an axial cross-section in respect of a rotational axis 23. FIG. 5 shows the roller bearing outer ring 20 in a radial cross-section in respect of the rotational axis 23. Similarly to the embodiments rendered in conjunction with FIGS. 2 and 3, FIGS. 4 and 5 may be two cross-sections arranged at right angles to one another and the same arrangement or however the same cross-section, with the roller bearing outer ring 19 and/or 20 being arranged differently.

The same applies to FIGS. 6 and 7, in which a cross-section is shown through an apparatus for hardening the outer bearing surface 22 of a roller bearing ring 28 and/or 29. FIG. 6 shows part of the roller bearing inner ring 28 in an axial cross-section in respect of the rotational axis 23, while FIG. 7 shows part of the roller bearing inner ring 29 in a radial cross-section in respect of the rotational axis 23.

The inventive method described in conjunction with FIG. 2 can be implemented in a similar fashion with the aid of the embodiments shown in FIGS. 3 to 7.

As a result, an internal stress of the surface of the drive pinion 11, 12, in particular of the surface of the tooth flanks 25, of the outer bearing surface 22 and of the inner bearing surface 21 of the roller bearing ring 19, 20, 28, 29 of more than 800 MPa can be achieved with the aid of the inventive method.

Claims

1.-9. (canceled)

10. A method for hardening a surface of a component in a wind turbine, comprising:

applying a blasting material by ultrasound waves with the surface of the component.

11. The method as claimed in claim 10, wherein the component is a part of a drive or a drive housing, a bearing surface, a gear wheel or a pinion.

12. The method as claimed in claim 10, wherein the ultrasound waves are emitted by a piezo electric transducer.

13. The method as claimed in claim 10, wherein the ultrasound waves are emitted in a frequency between 10 kHz and 30 kHz.

14. The method as claimed in claim 10, wherein the ultrasound waves are amplified.

15. The method as claimed in claim 10, wherein the blasting material comprises a tungsten carbide.

16. The method as claimed in claim 10, wherein the blasting material comprises a ball.

17. The method as claimed in claim 10, wherein the ball has a diameter of more than 1 mm.

18. The method as claimed in claim 17, wherein the ball has a diameter of more than 5 mm.