US20100319194A1

US20100319194A1 - Method for producing integrally bladed rotors

Info

Publication number: US20100319194A1
Application number: US12/863,422
Authority: US
Inventors: Erwin Bayer; Martin Bussmann; Albin Platz
Original assignee: MTU Aero Engines GmbH
Current assignee: MTU Aero Engines AG
Priority date: 2008-01-17
Filing date: 2008-12-20
Publication date: 2010-12-23
Also published as: WO2009089816A8; EP2229258B1; CA2708331A1; EP2229258A1; WO2009089816A1; DE102008004776A1

Abstract

A method for producing integrally bladed rotors comprises the following steps: a) defining and providing a blade profile of a blade to be manufactured with a pre-contour and a theoretical contour; b) producing at least two sectional planes of the blade profile, which sectional planes run vertically to a threading axis of the blade profile and of the blade to be manufactured; c) determining a point of rotation per sectional plane to produce an interval between the pre-contour and the theoretical contour that is approximately the same circumferentially, which points of rotation are located on a connecting line running parallel to the threading axis; and d) providing a base rotor body and electrochemically working the base rotor body in order to produce a raw blade with the blade pre-contour by movement of a hollow electrode into the base rotor body, the electrode movement including advancing motion along the connecting line superposed by rotation at the points of rotation, and which hollow electrode has an inner contour adapted to the pre-contour of the raw blade at least in an end area that is moved into the base rotor body.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase application submitted under 35 U.S.C. §371 of Patent Cooperation Treaty application serial no. PCT/DE2008/002143, filed 20 Dec. 2008, and entitled METHOD FOR PRODUCING INTEGRALLY BLADE-MOUNTED ROTORS, which application claims priority to German patent application serial no. 10 2008 004 776.7, filed 17 Jan. 2008, and entitled VERFAHREN ZUR HERSTELLUNG VON INTEGRAL BESCHAUFELTEN ROTOREN.
Patent Cooperation Treaty application serial no. PCT/DE2008/002143, published as WO 2009/089816, and German patent application serial no. 10 2008 004 776.7, are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a process for producing integrally bladed rotors, especially rotors of a gas turbine by an electrochemical process. The invention furthermore relates to an integrally bladed rotor produced with the named process.

BACKGROUND

Slender three-dimensional geometries of metallic structural components such as, for example, blisk blades are worked out of a solid material as a rule, at which time the so-called pre-allocation of the individual blades, i.e. the production of blade pre-profiles takes place by milling processes. In addition, the production of blade pre-profiles by water-jet cutting or eroding is known. In addition, it is possible to pre-allocate the intermediate blade space in the case of blisk blades by a straight or curved slot by electrochemical removal processes such as the so-called ECM (Electro Chemical Machining) or by grinding. In the cited ECM process the surface of the workpiece is worked as a rule with an electrode, during which a removal of material on the workpiece takes place by electrochemical reaction of the workpiece with the electrolyte located between the workpiece and the electrode. The electrode is connected as cathode to a direct current source. The electrode then moves at a given speed toward the structural component poled as anode. The width of the working slot between the electrode and the structural component is of considerable significance. In customary ECM processes the work is carried out with intervals from the element to the workpiece that can be in a range of 1 to 2 mm. In order to produce finer structures and forms the interval can be reduced to magnitudes in a range of 10 to 50 μm and above. However, the successful use of a poled ECM process (PECM) requires in many areas of use a uniform overmeasure of the blade and/or blade pre-profile to be worked. Thus, for example, an electrochemically produced pre-contour of a blade pan of a gas turbine, in particular of a blisk blade, previously had an overmeasure between ca. 1 and ca. 3 mm, conditioned by the process. In order to produce a necessary uniform overmeasure in these instances the non-uniform overmeasure was previously worked by milling. However, such processes can be used only in a very limited manner, in particular in the working of slender structural components such as, e.g., blade pans, since there is a danger of damage here such as, for example, a deformation of the structural parts. In addition, such a procedure for the production of blade pre-profiles is relatively time-consuming and therewith cost-intensive due to the plurality of process steps.

SUMMARY

The present disclosure therefore addresses the problem of making available a generic process for the production of integrally bladed rotors, in particular rotors of a gas turbine, which facilitates a relatively rapid and precise production of raw blades with approximately the same overmeasure.
The present disclosure furthermore addresses_the problem of making available an integrally bladed rotor of the initially cited type that can be produced relatively rapidly and precisely.
These problems are addressed by a process in accordance with the features disclosed and claimed herein as well as by an integrally bladed rotor in accordance with the disclosure and claims.
Advantageous embodiments of the invention are described in the particular subclaims.
A process in accordance with one aspect of the invention for producing integrally bladed rotors, in particular rotors of a gas turbine, comprises the following steps:

a) The defining of and making available a blade profile of a blade to be manufactured with a pre-contour and theoretical contour;
b) The production of at least two sectional planes of the blade profile, which sectional planes run vertically to a threading axis of the blade profile and of the blade to be produced;
c) The determining of a point of rotation per sectional plane in such a manner that the interval between the pre-contour and the theoretical contour is approximately the same circumferentially, which points of rotation are located on a connecting line running parallel to the threading axis;
d) Making available a base rotor body and the electrochemical working of the base rotor body in order to produce a raw blade with a blade pre-contour by a lowering of a hollow electrode into the base rotor body, during which an advance movement of the hollow electrode, that is superposed by rotation, takes place along the connection line determined in process step c), and during which the hollow electrode has an inner contour adapted to the pre-contour of the raw blade at least in an end area that is lowered onto the base rotor body.

The process in accordance with the invention facilitates_the production of blade pre-profiles for integrally bladed rotors with a uniform circumferential overmeasure in all cross sections by a simple lowering movement with a hollow electrode which movement compensates the blade twist by a rotation, which hollow electrode encloses the overmeasure blade in the interior. In addition, it is possible that a pre-allocation of intermediate spaces between two adjacent raw blades takes place at the same time in process step d). The process in accordance with the invention ensures that the overmeasure contour results in each step in an almost uniform overmeasure on the convex side and concave side of the blade although the lateral has a three-dimensional swung form. Furthermore, the process in accordance with the invention ensures the use of a simple electrode contour for lowering the intermediate spaces of the blade in the case of integrally bladed rotors.
In an advantageous embodiment of the process in accordance with the invention a plurality of hollow electrodes is moved simultaneously or successively into the base rotor body. Prior to a lowering of the plurality of hollow electrodes a determination of the connecting line for the determining of the advance movement of each hollow electrode can take place. This ensures that each raw blade produced has an optimized overmeasure.
In a further advantageous embodiment of the process in accordance with the invention the points of rotation are arranged off-center relative to the blade profile. In addition, the points of rotation are located off-center relative to the contour of the hollow electrode. This process has proven to be especially advantageous for the rapid and precise production of raw blades.
In a further advantageous embodiment of the process of the invention the hollow electrode is constructed in an electrically insulating manner up to an end area that is lowered onto the base rotor body. This ensures that no undesired removal events occur on the raw blade by the inner contour of the electrode.
In further advantageous embodiments of the process of the invention, after the production of the raw blades according to the process steps a) to d) an electrochemical working of the raw blades takes place for making available fluidic surfaces in accordance with the theoretical contour of the blades to be produced. The electrochemical working can take place here by a precise electrochemical removal process (PECM). For the rest, it is also conceivable that the production of the raw blades takes place by a PECM process. Even in the precise electrochemical removal the inner- and/or outer contour of at least one electrode used to this end can be adapted to the theoretical contour of the blades. In addition, the precision of the removal procedure can be raised during the precise electrochemical removal by an oscillating of the electrode during lowering. The cited measures make it possible to efficiently produce integrally bladed rotors such as blisks and blings.
A gas turbine rotor integrally bladed in accordance with the invention is produced according to a process described above. The rotor integrally bladed in accordance with the invention can be rapidly and precisely produced.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the process in accordance with the invention is described in detail in the following with reference made to the figures.

FIG. 1 shows a schematic lateral view of several raw blades of an integrally bladed rotor which blades are produced with the process in accordance with the invention; and

FIG. 2 shows a schematic top view onto the integrally bladed rotor according to FIG. 1.

DETAILED DESCRIPTION

FIG. 1 shows a schematic lateral view of several raw blades 12 produced with the process for the production of integrally bladed rotors 10. In the exemplary embodiment shown the rotor is a so-called blisk. The raw blades 12 as well as the rotor disk 18 connected to them are worked out of a base disk body. Raw blades 12 have a blade pre-contour with a uniform overmeasure so that they can be readily further processed. The further processing takes place, for example, by a PECM process with which fluidic surfaces can be produced according to the theoretical contour of the final blades to be produced.
FIG. 2 shows a schematic top view onto integrally bladed rotor 10 according to FIG. 1. Here, two points of rotation 14, 16 are sketched in by way of example. Points of rotation 14, 16 each correspond to a sectional plane through the blade profile, namely, vertically to a threading axis of the blade profile. Points of rotation 14, 16 are determined in such a manner per sectional plane that the interval between a pre-contour and a theoretical contour of the blades to be produced is circumferentially approximately the same, and the points of rotation 14, 16 are located on a connecting line running parallel to the threading axis. The advance movement of a hollow electrode (not shown), that is additionally superposed by a rotation about the particular points of rotation 14, 16, takes place along the determined connecting line. The hollow electrode is constructed in such a manner here at least in an end area that is lowered onto the base rotor body that this hollow electrode has an inner contour that is adapted to the pre-contour of the raw blade. Furthermore, it can be recognized that points of rotation 14, 16 are arranged off-center relative to the blade profile of the raw blades. In addition, it is clear that a pre-allocation of the intermediate spaces 20 between adjacent raw blades 12 takes place by the lowering of the hollow electrode in the direction of the base rotor body. The integrally bladed rotor 10 produced can consist of alloys based on nickel, cobalt or titanium.

Claims

1-11. (canceled)

12. A method for producing integrally bladed rotors, the method comprising the following steps:

a) defining and providing a blade profile of a blade to be manufactured with a pre-contour and a theoretical contour;

b) producing at least two sectional planes of the blade profile, which sectional planes run vertically to a threading axis of the blade profile and of the blade to be manufactured;

c) determining a point of rotation per sectional plane to produce an interval between the pre-contour and the theoretical contour that is approximately the same circumferentially, which points of rotation are located on a connecting line running parallel to the threading axis; and

d) providing a base rotor body and electrochemically working the base rotor body in order to produce a raw blade with the blade pre-contour by movement of a hollow electrode into the base rotor body, the electrode movement including advancing motion along the connecting line superposed by rotation at the points of rotation, and which hollow electrode has an inner contour adapted to the pre-contour of the raw blade at least in an end area that is moved into the base rotor body.

13. A method in accordance with claim 12, wherein a plurality of hollow electrodes is moved simultaneously or successively into the base rotor body.

14. A method in accordance with claim 13, wherein prior to moving each of the plurality of hollow electrodes, a respective connecting line is determined along which the advancing motion of the respective hollow electrode takes place.

15. A method in accordance with claim 12, wherein the points of rotation are arranged off-center relative to the blade profile.

16. A method in accordance with claim 12, wherein during the step of providing a base rotor body and electrochemically working the base rotor body, a pre-allocation of intermediate spaces between two adjacent raw blades takes place.

17. A method in accordance with claim 12, wherein the hollow electrode is constructed in an electrically insulating manner except for an end area that is moved into the base rotor body.

18. A method in accordance with claim 12, further comprising:

e) electrochemically working the raw blade having the blade pre-contour to produce a blade having fluidic surfaces corresponding to the theoretical contour.

19. A method in accordance with claim 18, wherein the electrochemical working of the raw blade having the blade pre-contour is performed using a precise electrochemical removal process (PECM).

20. A method in accordance with claim 19, wherein during the electrochemical working of the raw blade having the blade pre-contour, at least one of an inner contour and an outer contour of at least one electrode is adapted to the theoretical contour of the blade.

21. A method in accordance with claim 19, wherein during the electrochemical working of the raw blade having the blade pre-contour, the electrode executes oscillating movements.

22. A method for integrally forming a raw blade having a pre-contour on a base rotor body for which a blade profile including a threading axis, a raw blade pre-contour and a blade theoretical contour have been defined, the method comprising the steps:

providing a base rotor body for which a blade profile including a threading axis, a raw-blade pre-contour and a blade theoretical contour have been defined;

providing a hollow electrode having an inner contour configured to the raw blade pre-contour at least in an end area;

defining a plurality of sectional planes of the blade profile, the sectional planes being spaced apart along the threading axis;

determining a point of rotation for each sectional plane, each point of rotation constituting a point at which the hollow electrode is to be rotated to produce a substantially uniform overmeasure between the respective pre-contour and the respective theoretical contour of the sectional plane, the points of rotation defining a connecting line; and

electrochemically working the base rotor body while moving the end area of the hollow electrode into the base rotor body with an advancing motion along the connecting line superposed by rotation at the points of rotation;

whereby a raw blade with the blade pre-contour is produced, the pre-contour having a substantially uniform overmeasure with respect to the theoretical contour.

23. A method in accordance with claim 22, wherein the points of rotation are arranged off-center relative to the blade profile.

24. A method in accordance with claim 22, wherein the hollow electrode is constructed in an electrically insulating manner except for the end area.

25. A method for integrally forming a blade on a base rotor body for which a blade profile including a threading axis, a raw blade pre-contour and a blade theoretical contour have been defined, the method comprising the steps:

determining a point of rotation for each sectional plane, each point of rotation constituting a point at which the hollow electrode is to be rotated to produce a substantially uniform overmeasure between the respective pre-contour and the respective theoretical contour of the sectional plane, the points of rotation defining a connecting line;

electrochemically working the base rotor body while moving the end area of the hollow electrode into the base rotor body with an advancing motion along the connecting line between each point of rotation;

rotating the electrode at each point of rotation while continuing to electrochemically work the base rotor body and advancing along the connecting line until a raw blade with the blade pre-contour is produced, the pre-contour having a substantially uniform overmeasure with respect to the theoretical contour; and

electrochemically working the raw blade having the blade pre-contour using an electrode wherein at least one of an inner contour and an outer contour is configured to the theoretical contour of the blade;

whereby a blade having fluidic surfaces substantially corresponding to the theoretical contour is integrally produced on the base rotor body.

26. A method in accordance with claim 25, wherein the electrode used to produce the raw blade having the pre-contour and the electrode used to produce the blade have the theoretical contour are the same electrode.

27. A method in accordance with claim 25, wherein the electrode used to produce the raw blade having the pre-contour and the electrode used to produce the blade have the theoretical contour are different electrodes.

28. A method in accordance with claim 25, wherein during the electrochemical working of the raw blade having the blade pre-contour, the electrode executes oscillating movements.

29. A method in accordance with claim 25, wherein the points of rotation are arranged off-center relative to the blade profile.

30. A method in accordance with claim 25, wherein the hollow electrode is constructed in an electrically insulating manner except for the end area.

31. A method in accordance with claim 25, wherein the electrochemical working of the raw blade having the blade pre-contour is performed using a precise electrochemical removal process (PECM).