FIELD OF THE INVENTION:
The present invention relates to the field of suitable tooling for achieving high accuracy in locating the axial holes in field lead core bar of turbo generator (TG) rotor and exciter rotor of turbo generator. More particularly, the present invention relates to a tooling arrangement for making axial holes in two separate components which are high speed moving components needing perfect alignment co-axially.
BACKGROUND OF THE INVENTION:
A turbo generator (TG) used in thermal power necessarily constitutes two major components known as turbo generator rotor and exciter. The exciter and the turbo generator rotor are required to rotate at 3000 rpm in normal operations. These two components viz. rotor and exciter are coupled together through their shafts by using bushes on the outer periphery of their flanges. There are plurality of holes numbering 14 of particular diameter on the flange of the TG rotor towards exciter end (6) (refer fig-3). Similar holes are provided on exciter rotor flange also towards generator end.
On the center of the rotor is field lead core bar or core bar which is split centrally into two halves.
To give excitation from exciter to generator, 4 (four) conducting pins are used that go from inside of core bar in exciter rotor to inside of core bar in TG rotor. 4 axial holes are required to be made on matching faces on both core bars in TG rotor and exciter rotor to carry these conductor pins (8). The holes for these conductor pins are arranged in a square array.
During power plant in operation, there can be a transfer of load on the pin (8) due to either of the following:
1) The holes for bushes are not aligned properly.
2) The squarely arrayed holes of the conducting pins are not aligned.

As per design requirement the square arrayed holes of conducting pins are located automatically when the coupling of rotor and exciter is done through their flanges.
Since the flange holes are on the outside and there is some tolerance given in these holes as per design, the misalignment in these holes can be corrected during assembly, but the misalignment in the connecting pin holes cannot be corrected as reworking in these holes will loosen up the conducting pins.
Therefore the coupling of rotor and exciter (9) is done in such a manner that the coupling load is taken up by bushes and the conducting pins are off loaded. The pin (8) is a very critical component of a TG as all the excitation from exciter is transferred to the rotor. The pin is surrounded and held tight in contact with sliver coating (since conductivity of silver is high) so that the excitation can be transferred without any losses. Any loss in excitation directly results in loss of output from the turbo generator.
OBJECT OF THE INVENTION:
It is the object of the invention to develop a Pokayoke tooling for achieving high accuracy in locating axial hole on field lead core bar in both TG rotor and exciter rotor of large size turbo generator so that the conducting pins (8) are offloaded during high speed rotation and thereby avoiding any excitation loss.
SUMMARY OF THE INVENTION:
A Pokayoke tooling arrangement for achieving high accuracy in locating axial hole in the field lead core bar (3) in TG rotor and exciter rotor of large size turbo generator. The setup consist of plurality of bushes (1) of cylindrical shape and in stepped form to be used in conjunction with an intermediate plate (10) having plurality of holes with diameter same as minor diameter (0D1) of the bush (1) arranged on a particular pitch on the periphery of a certain diameter. The major diameter (002) of the bush (1) fits on the hole (0D2) of rotor flange (7) whereas the minor diameter (0D1) of the bush (1) fits on the corresponding hole (0D1) of the intermediate plate (10).

The process is repeated for all the holes of rotor flange (7) / intermediate plate (10) where at least a minimum of 3 holes of rotor flange / exciter flange and intermediate plate are matched. Once both the rotor shaft and exciter shaft are aligned separately with intermediate plate, then the 4 axial holes are automatically located for tracing, drilling and boring from the intermediate plate to fteld lead core bar of rotor / exciter shaft.
BRIEF DESCRIPTION OF THE ACCOMPANIED DRAWINGS:
Figure 1. Developed bush
Figure 2. Generator rotor
Figure 3. Generator rotor flange (at exciter end)
Figure 4. Exciter rotor and TG rotor assembly
Figure 5. Manufacturing of axial hole through developed tooling
Figure 6. Intermediate plate (10) with developed bush (1)
Figure 7. TG Rotor with flange (7)
Figure 8. Fitment of bush (1) in intermediate plate (10) and exciter/TG
rotor flange (7)
Figure 9. Photographic view of rotor flange and location of 4 axial holes in core bar.
DETAILED DESCRIPTION OF THE INVENTION: Reference numbers of different parts of the invention:
1. Bush
2. Plurality of coupling holes on flange
3. Field lead coare bar
4. TG Rotor
5. Turbine end of TG rotor
6. Exciter end of TG rotor
7. TG/Exciter flange
8. Plurality of Conducting pins
9. Exciter
10. Intermediate plate

The present invention discloses a Pokayoke tooling arrangement for achieving
high accuracy in locating axial hole on field lead core bar in rotor shaft of large
size turbo generator (4) by plurality of bushes (1) having a major diameter
and minor diameter (refer fig. 1) being used in conjunction with
intermediate plate (10) and TG rotor flange (7) / exciter flange.
A TG rotor (4) longitudinally has two ends known as turbine end (5) and exciter
end (6).
There are 14 holes of diameter on the outer periphery of rotor flange (7)
towards exciter end (6).
Axial holes are to be done on the field lead core bar (FLCB) (3) which is co-axial to
the turbo generator rotor as well as the exciter.
The radius of both field lead core bar (FLCB) (3) corresponding to TG rotor and
exciter is same.
Axial holes are to be done in the field lead core bar (FLCB) (3) of TG rotor (4)
towards the rotors exciter end (6).
Similarly axial holes are to be done in the field lead core bar (FLCB) of the exciter
(9) towards the TG rotor end.
TG rotor and exciter couple to each other through their flanges at the end.
There are 14 holes of diameter on the outer periphery of the TG rotor
flange (reference Fig.3) and similar holes are present on exciter flange towards
rotor end. The holes on the rotor flange / exciter flange are highly accurate since
they are made using CNC drilling / boring machine as demanded by job
requirement.
The developed bush (1) also has a major diameter and minor diameter
(0D1).
The intermediate plate (10) having identical shape as that of rotor / exciter flange
and is used for tracing of four axial holes on the field lead core bar (FLCB) of TG
rotor as well as exciter.

The intermediate plate (10) consists of 14 holes of diameter on the same
periphery as that of rotor and exciter flange.
Towards the center of intermediate plate (10) are four squarely arranged holes
which are to be transferred on the FLCB (3) of TG rotor and exciter rotor for
making the said axial holes in which the current carrying conducting pins (8) are
to be accommodated.
The pitch and location of all 14 holes on rotor / exciter flange as well as the
intermediate plate is same.
The intermediate plate (10) is brought near the TG/Exdter rotor flange (7) such that the 14 holes of diameter of rotor flange (7) coincide with the
corresponding holes of the intermediate plate (10). After the face of
intermediate plate (10) and the rotor flange (7) are coplanar and in butt condition with each other, the bush (1) is inserted from the rotor flange side such that minor diameter enters through the rotor flange coupling hole(2)
which is bigger in diameter than of the bust (1) and sits in corresponding
coupling hole of diameter of the intermediate plate (10) and after that
major diameter of the bush (1) sits in coupling hole (2) of rotor
flange (7) (refer flg.8).
The intermediate plate (10) is so designed that when all 14 coupling holes of both rotor flange (7) and intermediate plate (10) are coupled to each other using bush (1), the center of 4 axial holes (as shown in fig.3) itself rest at the place as per
design requirement.
Tracing of these 4 axial holes is done on the face of the rotor flange by drilling operation and then these holes are accurately made by using boring machine.
Similar operation is repeated for tracing of holes in the (FLCB) of exciter shaft by butting the intermediate plate (10) with the flange on the exciter side in the same
way.

We Claim

1. A tooling arrangement for achieving high accuracy in locating axial holes on field lead core bar in TG rotor (4) and exciter rotor (9) of large size turbo generator comprising:
a plurality of stepped bushes (1) having major diameter and minor
diameter
the said bushes (1) being used with an intermediate plate (10) having plurality of holes same as minor diameter of the bush (1);
the holes ' of intermediate plate (10) are so arranged on a particular diameter in a manner such that it can be aligned with the holes (0D2) on the TG rotor (7) or and exciter rotor flanges and after the minor diameter of the bush (1) having inserted from the flange side through the coupling holes (2) of flanges, it locate the holes of the
intermediate plate (10) first, the minor diameter of the bush (1)
positioned on the holes of intermediate plate (10) and then the
major diameter of the bush (1) positioned and inserted in the
diameter holes of rotor flanges and the activity being followed for at least 03 bushes (1) to ensure that the intermediate plate (10) being perfect aligned and co-planer with the rotor flanges (7) followed by transfer of 4 central holes from intermediate plate (10) to field lead core bar (3) of rotor shaft followed by the same sequence of operation for transfer of holes from intermediate plate (10) to field lead core bar of exciter rotor.
2. A method for locating axial holes on field lead core bar (8) in TG/exciter rotor of large turbo generator comprising:
bringing the intermediate plate (10) near the rotor flange (7) such that the hole positions of intermediate plate (10) and rotor flange (7) are aligned;

inserting the minor diameter of the bush (1) from the rotor flange
side through the diameter holes of rotor flanges (7) for locating the
holes diameter on intermediate plate (10);
Positioning and inserting the major diameter of the bushes (1) into
the holes diameter of flanges;
repeating the activity for at least 03 bushes which are at 120° apart;
tracing the four identical holes of intermediate plate (10) into the field lead
core bar (3) of rotor shaft;
repeating the process with exciter rotor flange for tracing the four holes
from intermediate plate (10) to the field lead core bar (3) of exciter so that
the conducting pin (8) holes of TG rotor and exciter rotors are perfectly
aligned.