The invention relates to a method for the surface blasting of hollow spaces or cavities, especially cavities of gas turbines.
Gas turbines, especially aircraft engines, have at least one rotor equipped with rotating runner or rotor blades especially in the area of a compressor as well as a turbine, whereby the rotor blades are increasingly embodied as an integral component of the rotor. Integral bladed rotors are also designated as “blisk” (bladed disk) or “bling” (bladed ring). Generally, through-going bored holes, extending in the radial direction, for fluids, for example oil, are generally integrated in such rotors. Such through-going bored holes are also designated as “bleed holes” and represent hollow spaces or cavities with small cross-sectional areas. Other bored holes extend in the axial direction and often serve for the screwing connection, whereby these bored holes similarly represent highly loaded zones or areas of compressor and turbine. Further cavities with small-cross sectional areas are, for example, located between neighboring rotor disks of a gas turbine rotor. During the operation of a gas turbine, especially the rotors thereof are subject to high demands. In order to reduce the wear rate, the rotors are densified or hardened by special surface treating or processing methods. In that regard, it is of significance to densify or harden also the surfaces of the above described cavities with small cross-sectional areas and the associated transition radii.
For the hardening of surfaces, the shot peening or shot blasting is usually used according to the state of the art, whereby the shot balls are accelerated with the aid of an airstream or a centrifuge. If, for example, the surfaces of through-going bored holes are to be hardened with the aid of shot balls accelerated by an airstream or a centrifuge, the problem arises, that especially corners or transition areas of the through-going bored holes between a surface of the rotor and an inner surface of the through-going bored holes are subjected to a strong plastic material deformation, whereby the ductility of the material in the area of the through-going bored holes can be reduced and thus disadvantageously influenced. The methods for the surface blasting known from the state of the art are thus suitable only with great limitations for the treatment of cavities with especially tight cross-sectional areas.
Beginning from this, the problem underlying the present invention is to provide a novel method for the surface blasting of cavities, especially cavities of gas turbines.
This problem is solved by a method according to the invention, wherein shot balls are accelerated with the aid of at least one vibrator, whereby the accelerated shot balls are directed onto surfaces of a cavity that is to be blasted and the corresponding transition radii. In that regard, the vibrator is preferably positioned at a small spacing distance, preferably a spacing distance on the order of magnitude of the diameter of the shot balls used for the blasting, away from the cavity that is to be blasted.
Through the inventive acceleration of the shot balls used for the blasting with the aid of a vibrator, a random motion direction of the shot balls arises due to multiple reflections, whereby material deformations in the area of the cavities are minimized. Furthermore, a temporally smaller impulse or momentum density arises due to the smaller number of the utilized shot balls, whereby similarly the danger of material damages is reduced. In order to provide a momentum sufficient for the surface hardening despite the reduced temporal momentum density, shot balls with an adapted diameter, a higher density and therewith ultimately a greater mass are used.
According to a preferred further development of the invention, the or each ultrasonic vibrator is operated or driven with a frequency between 10 kHz and 50 kHz, especially with a frequency between 20 kHz and 40 kHz, whereby preferably shot balls with high density and hardness of a ceramic material, especially of tungsten carbide, are used for the blasting.
Preferably, the method is utilized in the blasting of through-going bored holes extending in the radial direction of a gas turbine rotor or of connecting bored holes extending in the axial direction with a relatively small cross-sectional area of especially 5 mm2 to 100 mm2, whereby such a through-going bored hole is first blasted in a transition area between a component surface and an inner surface of the through-going bored hole, and is then blasted in the area of the inner surface, whereby shot balls with a diameter between 0.2 mm and 5 mm, especially between 0.4 mm and 1 mm, are used for the blasting, and whereby the vibrator is operated or driven with a frequency between 10 kHz and 50 kHz, especially at 20 kHz, for the blasting of a radially outward lying transition area between the component surface and the inner surface of the through-going bored hole as well as for the blasting of the inner surface, whereas however the ultrasonic vibrator is operated or driven with a frequency between 10 kHz and 50 kHz, especially at 40 kHz, for the blasting of a radially inward lying transition area between the component surface and the inner surface.
Preferred further developments of the invention arise from the dependent claims and the following description. Example embodiments of the invention will be explained more closely in connection with the drawing, without being limited hereto. Thereby:
In the following, the present invention will be described in greater detail with reference to
With the present invention, a method is now proposed, to densify or harden especially hollow spaces or cavities with such small dimensions, on their surfaces, by shot blasting. For this purpose, in the sense of the present invention, the shot balls are accelerated with the aid of at least one ultrasonic vibrator, especially with the aid of a so-called ultrasonic sonotrode whereby the thusly accelerated shot balls are then directed onto the surfaces of the cavity to be blasted.
In the sense of the present invention, in that regard, the or each ultrasonic vibrator is operated or driven with a frequency between 10 kHz and 50 kHz, especially with a frequency between 20 kHz and 40 kHz. Preferably shot balls of a ceramic material, preferably of tungsten carbide, are utilized for the blasting. Shot balls of a steel alloy, preferably of a 100Cr6 material, can also be utilized. The shot balls used for the blasting preferably have a polished surface and a diameter that is matched or adapted to the dimensions of the cavity to be blasted.
Preferably shot balls with a diameter between 0.2 mm and 5 mm, especially between 0.4 mm and 1 mm, are used for the blasting of the through-going bored holes 11, 12 with small cross-sectional areas as described with reference to
One preferably proceeds in a two-staged manner for the blasting of the through-going bored holes 11, 12 of the component 10 according to
For the blasting of the corner areas or the transition areas 15 between the surface 13 of the component 10 and the inner surface 14 of the through-going bored holes 11 or 12, one proceeds as shown in
For the blasting of the inner surfaces 14 of the through-going bored holes 11 and 12, one proceeds as shown in
The number of the shot balls used for the blasting and the time duration of the ultrasonic shot blasting are determined dependent on the desired internal residual stress profile to be achieved and the size of the cavity to be blasted.
The inventive method for the surface blasting of cavities is suitable not only for the blasting of cavities embodied as through-going bored holes or connecting bored holes, but rather also for the blasting of cavities between neighboring rotor disks of a gas turbine rotor. Thus
In the sense of the present invention, an ultrasonic shot blasting process is proposed for the surface densification or hardening of cavities, whereby the shot balls are accelerated with the aid of an ultrasonic vibrator, namely with the aid of an ultrasonic sonotrode. The diameter of the shot balls is matched or adapted to the cavity to be treated, whereby preferably shot balls of tungsten carbide are utilized. The shot balls have a polished surface.
Because smaller velocities of the shot balls occur and moreover a randomly distributed motion direction of the shot balls arises with the ultrasonic shot blasting, therefore the risk of plastic deformations in the area of the blasted cavities, especially on the edges, is minimized. Hereby it is avoided that the ductility of the material, of which the component to be hardened is formed, becomes unacceptably reduced.
Number | Date | Country | Kind |
---|---|---|---|
10 2004 059 592 | Dec 2004 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/DE2005/002205 | 12/7/2005 | WO | 00 | 7/6/2007 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2006/061004 | 6/15/2006 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
3668912 | Baughman et al. | Jun 1972 | A |
3668913 | Morris | Jun 1972 | A |
3695091 | Smith | Oct 1972 | A |
4108689 | Peter et al. | Aug 1978 | A |
4115076 | Hitzrot, Jr. | Sep 1978 | A |
4350035 | Kopp et al. | Sep 1982 | A |
4694672 | Baughman | Sep 1987 | A |
4888863 | Cox et al. | Dec 1989 | A |
4974434 | Reccius et al. | Dec 1990 | A |
5085747 | Nikano | Feb 1992 | A |
5443201 | Cartry | Aug 1995 | A |
5509286 | Coulon | Apr 1996 | A |
5596912 | Laurence et al. | Jan 1997 | A |
5771729 | Bailey et al. | Jun 1998 | A |
5820011 | Ito et al. | Oct 1998 | A |
5829116 | Vilon | Nov 1998 | A |
5950470 | Prewo et al. | Sep 1999 | A |
6170308 | Veronesi et al. | Jan 2001 | B1 |
6289705 | Duquenne et al. | Sep 2001 | B1 |
6336844 | Duquenne et al. | Jan 2002 | B1 |
6343495 | Cheppe et al. | Feb 2002 | B1 |
6383317 | Bellus et al. | May 2002 | B1 |
6467321 | Prokopenko et al. | Oct 2002 | B2 |
6490899 | Berthelet et al. | Dec 2002 | B2 |
6505489 | Berthelet et al. | Jan 2003 | B2 |
6508093 | Berthelet et al. | Jan 2003 | B2 |
6536109 | Berthelet et al. | Mar 2003 | B2 |
6584820 | Benedict et al. | Jul 2003 | B1 |
6938448 | Kennerknecht et al. | Sep 2005 | B2 |
7028378 | Cheppe et al. | Apr 2006 | B2 |
7140216 | Garza | Nov 2006 | B2 |
7181944 | Wuestefeld et al. | Feb 2007 | B2 |
7389663 | Cheppe et al. | Jun 2008 | B2 |
7481088 | Bayer et al. | Jan 2009 | B2 |
20020124402 | Berthelet et al. | Sep 2002 | A1 |
20030005736 | Inoue et al. | Jan 2003 | A1 |
20030115922 | Berthelet et al. | Jun 2003 | A1 |
20060021410 | Cheppe et al. | Feb 2006 | A1 |
20060174483 | Bayer et al. | Aug 2006 | A1 |
20070214640 | Bayer et al. | Sep 2007 | A1 |
Number | Date | Country |
---|---|---|
2 815 280 | Apr 2002 | FR |
2 250 931 | Jun 1992 | GB |
07-308859 | Nov 1995 | JP |
WO 2005123338 | Dec 2005 | WO |
Number | Date | Country | |
---|---|---|---|
20090095042 A1 | Apr 2009 | US |