Title of the Invention
HP Turbine Disc Assembly Fixture
2 Field of the Invention
The present invention relates to manufacturing, repair, overhaul of Gas
Turbines. Fixture is assembly of turbine rotor.
3 Background of the Invention
Gas Turbine assembly requires critical control of clearances between rotating
and stationary parts. One of such component! Assembly Gas Turbine where
maintaining correct concentricity is of prime importance is High Pressure
Turbine Rotor Assembly. In order to optimize the performance and minimize
the vibration during operation the concentricity of turbine playS‘an important
role. Here, maintaining correct concentricity of rotor during assembly
improves the vibration levels.
3.1 Prior Art
Earlier HP turbine disc were assembled on forward shaft one by one and at
each stage there was need of checking multiple times till we reach to aft shaft
dia. During this process there were no of iterations where indexing of disc
was needed and to do so we have to disassemble the entire assembly. There
Was a need of tool which facilitates multiple disc assembly at a time on thé
shaft to reduce no of iteration and cycle time of the process.
4 Brief Summary of the Invention
Present fixture is designed to hold two HP turbine disc together during
assembly to avoid any concentricity problems with respect to forward shaft of
the turbine assembly. This offers following benefit over earlier method of assembly.
1_. 'Able to assemble two disc and thermal shield on fon/vard shaft at a time
2. Reduction in no iteration for achieving concentricity
3. Ease of handling multiple discs at same time

6 Detail Description of the Invention
Construction:
This fixture is designed to hold two discs together during assembly.
The Lock plate (1) which hold the stage one disc in the locked position
due to its uniquely shaped locking pin (7) which enters into the blade
mounting slot on the disc. This lock plate also acts as amounting base
for the threaded rod (5) which is welded to lock plate perpendicularly
and facilitates movement of locating plate (2) in vertical axis through a
hole of adequate size along the threaded rod. When stage one Disc is
fixéd with lock plate the threaded rod acts as a vertical guide for the
locating plate (2). The position of locating plate on the rod is
dependent on the hub thickness of the disc and inter stage thermal
shield between the two discs‘ The locating pin (6) of the locating platé
.gets engaged into stage two turbine disc. Locating plate is held in
‘
position with help of a washer (3) and a nut (4)‘ This fixture in a set of
four is used at four equi spaced location on the disc holding the two
discs together.

Function :
This fixture‘is used for assembling two HP turbine Disc & a inter stage
thermal shield. Stage one turbine disc is first placed on the rotary table
.on c_entre hub location then run out and face out is recbrded for stage
one disc. Further, thermal shieid is chilled with help of dry ice and it
will be placed on stage one disc such that bolt hole location on the
disc; matches with the nut location on the thermal shield. The bolt hole
on the disc is having play hence some time during tightening there is
' chance of eccentricity of disc and thermal shield. Subsequently stage
two turbine disc will be placed over upper part of the thermal shield in
such a way that bolt hole in the disc stage two matches with nut
position on upper flange of the thermal shield. The bolt holes in turbine
disc are also a free hole for the bolt hence there is chance of disc
shifting during tightening of the bolt. Now this fixture tool will be used to arrest movement of turbine discs with respect to each other during
tightening of the bolt on stage one and stage two discs to make this as
disc combo without any concentgicity error. Lock pin (7) mounted on
the lock plate (1) of this tool is engaged with blade slot on the stage
one disc (8) and remains in position. Locating pin (6) on the Locating
plate (2) engages with stage two disc (10) through adjusting the height
of locating plate (2) on threaded rod (5) which will be held in position
with help of washer (3) and a nut (4). After proper installation of such
four fixtfires set at four equi-spaced locations on stage one disc and
tightening of Nut (4) the set up will be ready for making disc combo
with ifiter stage thermal shield (9)‘ To complete the combo assémbly
bolts on two turbine discé will be tighten and torqued to appropriate
torque value so that stage one disc (8) gets attached to bottom flange
of thermal shield (9) and stage two disc (10) is attached with upper
flange of the thermal shield. (9). During the tightening process this
fixture (11) hold stage two disc (10) in concentric position with stage
one disc (8) and hence avoid eccentricity error and eliminates the
needs of multi iteratidn to achieve concentric assembly of disé combo.
Figure - 2 illustrates the application of the assembly fixture (11). Four
such fixtures at equi spaced location the disc facilitate the concentric
assembly of discs by arresting their relative movement during
assembly and tightening. This also facilitates handling/ lifting of two
turbine discs together along with thermal shield while assembling
discs with shaft without any eccentricity thus ensuring error free
assembly.

Title: HP Turbine Disc Assembly Fixture
We Claim,
1. A fixture designed and manufactured for assembly of HP turbine
disc comprising:
a lock plate (1);
a locating plate (2);
a washer (3);
a nut (4);
a threaded rod (5);
a locating pih(6); and
a lock pin (7), characterized in that, lock pin (7) is fixed to the lock
plate (1) which is fixed to threaded rod (5) and in turn holds the
locating plates (2) and locating pin (6) at four equi spaced
locations on the disc with help of a washer (3) and a nut (4) to
facilitate concentric assembly of two turbine disc.