FIELD OF INVENTION
The invention relates to a dual face flange device for coupling a steam turbine
rotor with the head stock of an indicating machine for machining. More particularly, the
invention pertains to a developed flange device that couples with rotor on one side
while the other side is coupled to the headstock so that the setting time and
unclamping time is much lesser compared to prior Art.
BACKGROUND OF THE INVENTION
A steam turbine is a device that extracts thermal energy from pressurized steam
and uses it to do mechanical work on a rotating output shaft. Depending upon the
steam inlet pressure, turbines are distinguished into three types viz, high pressure
turbine (HPT), low pressure turbine (LPT), and any turbine in between is an
intermediate pressure turbine (IPT). All turbines contains of three necessary and
essential components viz. a rotor which serves as the center of the rotation motion of
turbine, secondly, blades to guide the steam from inlet to the outlet of the turbine and
deliver the necessary rotation motion to the rotor thereby converting heat energy and
pressure of the incoming steam into mechanical energy (rotation) and lastly, a casing
which serves to cover all the assemblies and keep the steam intact in the system. In
power plant application, in general the size of a Low Pressure Turbine Rotor is

approximately 8 meters and 100 tonnes in weight. Rotor forging is received in rough
form and then different operations are done on the rotor to assemble it with turbine
blades (Fig. 1). On an indication machine, different operations are performed on the
rotor like turning diameters of fins & blades grooves, flow path machining, machining
of sealing fins. Thus a good amount of time is usually absorbed at indicating machine
and since it is the last operation (Refer fig. 2) CNC Indicating stand perform machining
on Bladed turbine rotor. At this stage Rotor is near completion and any problem at this
stage affect on production schedules. Also due to the criticality of the operations being
handled by the indicating machine, the time absorbed in performing these operations
directly increase the overall time in manufacturing a turbine.
While performing an operation, the rotor has to be coupled with the headstock of
the indicating machine so as to get the required rotary motion for machining. In the old
method this was done using two plates, one of which (Plate-1) is coupled to the
turbine side flange of the rotor and the other (Plate-2) is coupled with the already
coupled plate-1 as stated and the flange of the cardan shaft (refer fig. 2).
The specification for plate-1 is around 1680mm in diameter, 1120 Kg of weight
and use 16 bolts to fit in Rotor while for plate-2 it is 2300mm diameter, 2505 Kg of
Weight, use 16 bolts to fit Plate No. 1 and 8 bolts to cardan shaft.

After fitting both the plate on L.P. Rotor with the help of the crane, crane is
loaded with Cardan shaft; a mechanical component for transmitting torque and
rotation, usually used to connect other components of a drive train that cannot be
connected directly because of distance or the need to allow for relative movement
between them.
As torque carriers, drive shafts are subject to torsion and shear stress,
equivalent to the difference between the input torque and the load. They must
therefore be strong enough to bear the stress, whilst avoiding too much additional
weight as that would in turn increase their inertia.
To allow for variations in the alignment and distance between the driving and
driven components, drive shafts frequently incorporate one or more universal joints at
the ends or, jaw couplings, or rag joints, and sometimes a splined joint or prismatic
joint with lifting device and lift the Rotor for setting the Rotor on Indicating machine.
Since universal joint have hinge, both ends of the cardan shaft lie down at hinge
whenever the shaft is not in use. This required setting (adjusting the height and
rotation of the cardan shaft so as to match threaded hole of the cardan shaft with
headstock as well as the intermediate plate) of hinged end of the cardan shaft every

time rotor was placed on the steady and was coupled to the cardan shaft through
intermediate plates.
It should be noted here that cardan shaft is used to transmit the torque and the
rotation from the machine headstock to the plate.
For the same process, it was observed that it was taking Plate Setting time,
Crane engagement time, unclamping time and thus increase in overall machining time.
Thus there was a need of a new coupling arrangement which can serve the
overall time and more ergonomic in nature.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose a dual face flange device for
coupling a steam turbine rotor with the head stock of an indicating machine for
machining which is capable of reducing setting time, crane engagement time,
unclamping time and thus machining time for each unit.
Another object of the invention is to propose a dual face flange device for
coupling a steam turbine rotor with the head stock of an indicating machine for

machining which is able to withstand the torque of the headstock of an indicating
machine while imparting the rotary motion to the rotor without any hazards.
A further object of the invention is to propose a dual face flange device for
coupling a steam turbine rotor with the head stock of an indicating machine for
machining which can couple the flange device with cardan shaft and thus to the Head
stock and is allowed to remain in the cantilever position to facilitate coupling of rotor
only with the flange device (F).
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 : Shows a turbine rotor.
Fig. 2 : Shows existing plates 1 and 2 for coupling turbine rotor with cardan shaft
and Head stock according to prior Art.
Fig. 3 : Shows a developed dual face flange device in accordance with the
invention.
Fig. 4 : Shows the dual face flange device coupled with cardan shaft and Head
stock in one end and fixed to the rotor on the other end according to
invention.
Fig. 5 : Shows the cantilever position of the dual flange face when assembled with
head stock with the help of long studs.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
The developed dual face flange for coupling rotor during machining comprises of
the following key components (Refer fig. 3 and 4):
Item 1: Cardan shaft side coupling flange.
Item 2: Turbine side (TS) coupling flange.
Item 3: Coupling arm.
Item 4: Plurality of threaded hole for coupling Item 1 to cardan shaft.
Item 5: Plurality of threaded hole for coupling Item 2 to rotor to be machined.
Item 6: Cardan shaft.
Item 7: Headstock.
Item 8: Steady Bearings.
Item 9: Turbine end flange of the rotor.
Item 10: Rotor.
Item 11: Long Studs.
The dual face flange device comprising of a turbine side (TS) coupling flange (2)
welded to a coupling arm (3), the other end of which is welded to a cardan shaft side
coupling flange (1) so that two flanges and the coupling arm form a single unit. Flange
(1) is provided with plurality of threaded holes (4) for being coupled to the

cardan shaft (6) which is fixed to the Headstock (7). Plurality of threaded holes (5) are
disposed in flange (2) for coupling the turbine end flange (9) of the rotor. The hole unit
(F) is fixed to a cardan shaft (6) and then to a Head stock (7) of an indicating machine.
While the rotor is placed on the bearings (steady) (8), the developed coupling’s
turbine side flange (2) is first lifted up using the overhead crane and is taken near to
the turbine side (TS) flange of the rotor (10) where it is first coupled to the flange (9)
directly using the threaded holes (5) in the developed coupling and threaded holes in
the TS flange (9) of the rotor. The other end of the developed coupling flange (1) is
then coupled to the cardan shaft (6) using threaded holes (4). The coupling arm (3)
helps in successful transmission of the initial high torque to overcome the resisting
forces due to the static friction in the bearings as well as due to the weight of the rotor.
Earlier, this TS flange of the rotor was used to couple with plate-1 which in turn was
coupled with another plate type flange (shown as plate-2) and this plate-2 is connected
to one end of the cardan shaft and other end of the cardan shaft is connected to the
headstock of the machine. Long studs (11) are designed in such a manner that they
have one end dia as just less than the hole given in the headstock of the machine
(alternately such holes can be drilled in the machine headstock if these are not readily
available). The other end of the studs (11) are threaded and make threaded connection
with TS flange (2) of the developed coupling.

This arrangement shortens the time by installing the rotor significantly in such a
way that the cardan shaft hinge sections are already in threaded connection with the
developed coupling and headstock and the load of the cantilever is taken up by the
studs (11) where the TS end (2) is not coupled with the rotor (10) (as the rotor is not
placed on the steady).
As shown in fig. 5 the dual face flange device remains fixed with the cardan shaft
(6) which is coupled to the Headstock (7). Four long studs (11) take the load of the
entire cantilever, composing of cardan shaft (6) and invented flange device (F). Two
preselected steady bearings (8) and placed in position to hold the rotor (10).
The rotor (10) is then placed over the steady bearings (8) with the help of a
crane. Since different rotors are machined, steady bearings are preselected for each
rotor so that when the rotor is placed on the bearings marked for it, the height of the
steady bearings (8) are such that it brings perfect alignment with the turbine side
flange (2) when long studs (11) having one end in the holes of headstock and other
end threaded into the threaded holes (5) of turbine side flange (2), takes the load of
the cantilever. The rotor is now in a condition for machining.

WE CLAIM
1. A dual face flange device (F) for coupling a steam turbine rotor with the Head
stock of an indicating machine for machining comprising;
a turbine side (TS) coupling flange (2) welded to a coupling arm (3);
a cardan shaft side coupling flange (1) welded to other side of coupling arm (3)
so that the device form a single unit (F); wherein a plurality of threaded holes (4) are
disposed in flange (1) for fixing the said flange to a cardan shaft (6) which is coupled to
a Head stock (7) when a plurality of threaded holes (5) are disposed in turbine side
coupling flange (2) for fixing the said flange to the turbine end flange (9) when the
rotor rests on steady bearings (8) making a perfect alignment with the centre line of
the head stock wherein four long studs (11) are disposed for fixing the flange device (F)
to the head stock (7) in a cantilever position.
2. A method for coupling the flange device (F) with head stock and with a rotor of a
steam turbine comprising;
coupling a cardan shaft with the headstock;
coupling the said cardan shaft with cardan shaft side coupling flange (1) of the
said flange device (F);

holding the flange device (F) with long studs (11) having one end in the head
stock and threaded ends of the other side threaded (5) into threaded holes of the
turbine side coupling flange (2) disposing the said device (F) in a cantilever condition;
placing the preselected steady bearings (8) in position to hold the rotor (10);
when,
the rotor is placed on the preselected steady bearings (8) and the rotor being
brought towards the headstock, when flange device (F) and the head stock (7) will be
in perfect alignment for machining automatically.