Title of Invention

"LOCK FOR MOVING BLADES OF A TURBINE ROTOR"

Abstract Lock for closing an entry point of a circumferential slot undercut on both sides and Intended for accommodating blade roots (12) of moving blades of a turbine rotor (1), a filling piece (5) with a contour adapted to the blade roots being supported against a supporting flank (3) In the turbine rotor via a fitting piece (6), characterized by a step (4) for the axial support of the filling piece (5), the step (4) being provided in the base region of the lock (2).
Full Text -1A
Lock for moving blades of a turbine rotor


Description

The invention relates to a lock for moving blades of a turb ine rotor.
DE 30 28 701 Al discloses a lock for turbine blading in which the moving blades are inserted in a positive-locking manner in the circumferential slot of the turbine rotor, the circumferential slot being undercut in any shape on both sides. Provided on the circumference of the turbine rotor is at least one entry point, in which a filling piece, positive-locking with the blade root, is inserted. The wall of the entry point in the turbine rotor and that flank of the filling piece which faces this wall are designed so as to be inclined at an angle to the blade axis. The closure between the wall of the entry point and the flank of the filling piece is effected with a fitting piece which sits tightly in position.
The known lock is suitable in particular for root forms of the moving blades in which the blade roots are fully supported in the axial direction of the turbine rotor at the circumferential slot, for example for hammer-head roots. If the blade root is not fully supported in the axial direction in the circumferential slot - for

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example in the case of fir-tree roots - the blade root in the lock region may yield to an excessive degree when the filling piece is installed, so that the requisite prestress cannot be produced in the lock. Without prestressing of the lock assembly, the centrifugal-force effect on the inclined flank of the lock during operation may not adequately clamp the fitting piece, so that the fitting piece becomes detached from the lock and the lock fails.
The object of the invention is to specify a lock for moving blades of a turbine rotor of the type mentioned at the beginning which is also suitable for moving blades in which the blade roots are not fully supported in the axial direction of the turbine rotor at the circumferential slot.


Advantageous developments of the invention are specified in the subclaims.
The advantages which can be achieved by the invention consist in particular in the fact that the lock can also be used when fir-tree roots are used as the blade roots, in which case the assembly can be carried out in a simple manner. Even in the case of large lock sizes, the press-in forces required during assembly can be applied manually and are well below the limit values for the admissible mechanical loading of the turbine rotor. The configuration of the lock with a slit fitting piece ensures that the fitting piece is also positioned inside the lock in a predetermined manner in the expanded installation position and on no account projects above the filling piece, for example.

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Unlike the generally known locks for fir-tree roots, it is possible with the proposal according to the invention to reblade the associated blade ring repeatedly without damaging the turbine rotor in the process or " without having to rework the turbine rotor.
The invention is explained below with reference to the exemplary embodiments shown in the/drawing, in which:
Fig. 1 shows a section through a lock of a turbine rotor.
Fig. 2 shows a view of a lock of a turbine rotor.
A section through a lock of a turbine rotor is shown in Fig. 1. The section line A-B is sketched in Fig. 2. In principle, a blade root 12 - a fir-tree root is shown in the example - is supported with the use of a filling piece 5 and a fitting piece 6. The axial support is effected directly by the filling piece 5 in the turbine rotor 1 by virtue of the fact that the lock 2 is made in the turbine rotor 1 in such a way that it is deeper than the circumferential slot for the blade root 12, and the filling piece 5 is likewise extended in this region. The filling piece 5 is pressed at a flank 9 by the fitting piece 6- against the step 4, thereby formed, on the turbine rotor 1 and against the blade shoulder, i.e. the blade root 12. During operation, the moving blades, in the region of the lock as well as in the rest of the circumferential slot, can bear against the slightly inclined supporting flanks 13 on the turbine rotor 1 and be centred..
In order to permit expanding of the fitting piece 6, in particular in the case of large lock sizes, the fitting piece, in one design, is provided with a wedge-shaped

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slit 7. The slit 7 narrows in the direction of the base region of the lock 2, i.e. in the direction of the axis of the turbine rotor 1. Apertures, preferably tapped holes 8, are made on the top side, opposite the base region, of the fitting piece 6 (see Fig. 2) , and these tapped holes 8 lead into the slit 7 and enable tools to be passed through and screws to be screwed into place.
The supporting flank 3 in the turbine rotor 1 is inclined at a slightly larger angle to the radial than the filling piece 5, so that the expanded fitting piece 6 is fastened in a positive-locking manner. During assembly, a wedge 10 first of all rests loosely in the slit 7. After the fitting piece 6 is inserted into the lock 2, the wedge 10 is pressed in the direction of the base region of the wedge lock 2 wi th the us e of a suitable tool reaching through the holes 8. As a result, the slit 7 and thus the fitting piece 6 are opened out. The pressed-in wedge 10 is fixed in its position by screwing locking screws 11 (caulked grub screws) into the tapped holes 8.
The slit 7 is preferably made in the fitting piece 6 in one operation together with the wedge 10 by electrical-discharge wire cutting.
A view of a lock 2 of a turbine rotor 1 is shown in Fig. 2. The position of the blade roots 12 of the moving blades, arranged next to one another, relative to the lock 2 is indicated. The filling piece 5, the flank 9, the fitting piece 6 with tapped holes 8 and the supporting flank 3 can be seen. The position of the wedge 10 relative to the tapped holes 8 is sketched.

WE CLAIM
1. Lock for closing an entry point of a circumferential slot undercut on both
sides and intended for accommodating blade roots (12) of moving blades
of a turbine rotor (1), a filing piece (5) with a contour adapted to the blade
roots being supported against a supporting flank (3) in the turbine rotor via
a fitting piece (6), characterized by a step (4) for the axial support of the
filling piece (5), the step (4) being provided in the base region of the lock
(2).
2. Lock as claimed In claim 1, wherein the fitting piece (6) is provided with a
sIH (7), into which a wedge (10) for expanding the fitting piece can be
pressed.
3. Lock as claimed in claim 2, wherein at least one aperture (8) is provided In
the fitting piece (6), and this aperture (8) serves for the engagement of a
tool suitable for pressing in the wedge (10).
4. Lock as claimed In claim 3, wherein a design of the at least one aperture
as a tapped hole (8), into which a locking screw (11) can be screwed.
Lock for closing an entry point of a circumferential slot undercut on both sides and Intended for accommodating blade roots (12) of moving blades of a turbine rotor (1), a filling piece (5) with a contour adapted to the blade roots being supported against a supporting flank (3) In the turbine rotor via a fitting piece (6), characterized by a step (4) for the axial support of the filling piece (5), the step (4) being provided in the base region of the lock (2).

Documents:


Patent Number 202646
Indian Patent Application Number 382/CAL/1999
PG Journal Number 09/2007
Publication Date 02-Mar-2007
Grant Date 02-Mar-2007
Date of Filing 23-Apr-1999
Name of Patentee ABB PATENT GMBH
Applicant Address KALLSTADTER STR.1,D-68309 MANNHEIM
Inventors:
# Inventor's Name Inventor's Address
1 BERND SOKOL PEUNTING 9, D-90559 BURGTHANN
2 HORST MULLER ZUR WIESETHQUELLE 13, D-91589 WEINBERG ,
3 GEORG FEEDER OSILDENSTR.1, D-90461 NURNBERG
4 GERD RUPPRECHT LINDENSTR .15. D-91227 LEINBURG
PCT International Classification Number F 01 D 5/32
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 19826897.1 1998-06-17 Germany