FIELD OF THE INVENTION
The present invention relates to development of multipurpose drilling device for
working on large size components of turbo generator.
BACKGROUND OF THE INVENTION
Large number of components of Turbo Generator (TG) including Rotor, Core Press Ring
and Diode Wheel under go various machining operations like grooving, slot cutting,
drilling and taping operations. Quality of these holes drilled and taped on Rotor shaft,
Core Press Ring and Diode Wheel with the help of universal drilling machine is not
found as per standard. The problem experienced that often the drill gets broken due to
shifting of machine there by spoiling the holes. When drilling the holes on many
components, clamped directly on bed, each time universal drilling machine has to be
shifted to set to the position of next hole. These frequent changes engaged more
handling staff and crane, hampering other handling work. Rotor Shaft and Core Press
Ring being heavy component take lot of time in setting on Horizontal Boring machine,

thereby increasing idle time of machine. CNC Horizontal Boring machine has a very high
per hour operating cost (Rs. 7500/-). Carrying out small size holes on critical and costly
Horizontal Boring machine increases production cost also waiting time for other
components to be loaded on this Horizontal Boring machine increases due to these
small operations. Due to over loading of Horizontal Boring machine some times
assembly work gets delayed. While drilling 90° holes between the slot to open deep drill
holes on faces (in TG Shaft THRI design), sometimes universal drilling machine shifts
from its position and dislocate drill from original drilling position. Due to this, drilled
holes open into dovetail groove cut across the length of the Rotor Shaft (as shown in
Fig.3). Position of opening holes in dovetail groove is such that there is only 1.75 mm
material margin (as shown in Fig.3A).
About the process
1. Large no. of components of Turbo Generator including Rotor, Core Press Ring
and Diode Wheel under go various machining operations like grooving, slot
cutting and taping operations.
2. A numbers of small size holes are drilled and taped at various locations on these
components. For drilling operations, Rotor is supported on rollers which can be
easily set in required position by rotating it.
3. For carrying out small drilling operation on core press ring and diode wheel,
component is set either on Rotary Table on Horizontal Boring machine or directly
clamped on machine bed.

4. After setting Rotor on rollers, Core Press Ring and Diode Wheel on rotary table,
small size hole are drilled with the help of universal drilling machine.
5. Position of hole in Rotor are set by rotating it on roller. Core Press Ring and
Diode Wheel are set by rotating Rotary Table. In case, when Core Press Ring
and Diode Wheel are clamped directly on the bed instead of rotary table, position
of the universal drilling machine is changed every time a new hole is drilled and
taped.
6. After installation of CNC H. Boring machine small holes on TG Rotor are being
drilled on this machine as shown in fig.1.
7. 18 holes dia 15 mm, depth 210 mm and 18 holes dia 12 mm, depth 310 mm are
drilled on each side of the Shaft for air vent.
8. These deep holes are opened in its slots by drilling two holes of dia 10.5 mm at
90° mark with the help of universal drilling M/c or CNC H. boring Machine.
9. These holes are very accurately drilled because a little shift of drill may open
holes in the dovetail groove (as shown in fig.2).
To avoid carrying out small drilling and taping operations on critical Horizontal Boring
machine, inventors designed and developed a portable drilling and tapping device as
shown in fig.4.

OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose development of a
multipurpose drilling device for working on large size components of turbo generators
which eliminates the disadvantages of existing state of art.
Another object of the present invention is to propose development of a multipurpose
drilling device for working on large size components of turbo generators which is handy
to operate.
A further object of the present invention is to propose development of a multipurpose
drilling device for working on large size components of turbo generators which
functions multi-directionally.
A still further object of the present invention is to propose development of a
multipurpose drilling device for working on large size components of turbo generators
which is eco-friendly.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1 - shows a photo view of large TG component (Rotor shaft) being drilled on CNC
machine
Fig.2 - shows a schematic view of drill hole size and position in TG Rotor Shaft
Fig.3 & 3A - shows a schematic detail of dovetail groove in TG Rotor Shaft:

Fig.4 - shows a photo view of drilling device in assembled condition
Fig.5 - shows a photo view of drill machine placed on a base plate
Fig.6 - shows a photo view of platform having T-grooves, plate with gear and
penion assembly and a base clamping plate
Fig.7 - shows a photo view of base clamping plate placed on a Taper Shoes
Fig.8 - shows a photo view of variable speed regulator
Fig.9 - shows am electrical circuit of variable speed and direction reversing circuit
diagram
Fig.10 - shows a photo view of height adjustable supports
Fig.11 - shows a photo view of circular T' slot for clamping cross slide at any angle
between 0-360° on horizontal plane
Fig.12 - shows a photo view of circular T' plate on a longitudinal motion fixture
engaged on a base plate
Fig.13 - shows a developed multipurpose drilling device as per invention
Fig.14 - shows a photo view of operation of puncturing of air vent holes in progress
on Rotor of THRI 250 MW Generator
Fig.15 - shows a photo view of drilling operation of 24 holes M-16 on the face of
Rotor of THRI 250 MG generator in progress
Fig.16 - shows a photo view of Rotor after drilling
Fig.17&18 - shows a photo view of reaming operation of dia 10 +.002 mm holes for
Slot Wedge Stopper on THRI Generator Rotor 250 MW in progress

Fig.19&20 - shows a photo view of drilling operation of coupling bolt locking holes in
coupling of Generator Rotor 500 MW in progress
Fig.21 - shows a photo view of drilling operation of 72 holes M 10 on Diode Wheel
500 MW exciter in progress. Machine is directly clamped on floor bed
Fig.22&23- shows M 10 72 holes drilled and tapped on periphery of Diode Wheel for
500 MW and THRI Exciter
Fig.24 - shows a photo view of drilling operation of 48 holes M 8 on Core Press Ring
for 500 MW Generator placed on fixture cum rotary device in progress. Drilling device is
clamped on the body of the fixture.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in Fig.5, a standard portable electrical hand drill machine (1) was selected
wherein a new set of coil winding was made to withstand more torque during drilling
operation and increased 1500 RPM. The hand drill machine (1) was fixed in a
rectangular steel base plate (2) by means of a clamp (3) at front end and fixing a bolt
at rear end (4) with the base plate. The base plate (2) is also welded with a slightly
bigger rectangular plate (5) having a plurality of holes at each corner (6) and middle
(7) for fixing with subsequent attachment- Step I.

As shown in fig.6, a platform was made by machining and cutting a rectangular steel
plate (8). A plurality of slots (9) were made by machining along the length of the
rectangular plate. An arrangement was also made with a gear and pinion assembly (10)
fitted in a plate (11) mounted at the opposite side of slotted face of the platform in
order to make cross slide (14) and longitudinal slide (15) of the platform. The platform
including gear and pinion assembly and longitudinal slide rest on base clamping plate
(12). The platform provided with two locking holes at two ends for housing a locking
pin (13) for carrying out tapping operation, locking pin is removed to release cross slide
from feed mechanism. The hand drill machine with base plate in step-I rest on a
platform (8) affixing with sliding bolts housed inside slots of platform and nut on the
base plate (5).
Up to this stage, the drill machine will be capable to move crosswise and longitudinal
wise by operating a round handle (10) connected with a gear-pinion assembly-Step-II.
As shown in fig.7, for fine adjustment of height of the machine a taper shoe jack (16) is
provided between base clamping plate (12) and lower slide and there is a locking
arrangement (13) for jack so that there is no movement of slide during drilling
operation. Drilling machine is mounted on taper shoe slide between to parallel clamping
plate (12) in such a way that after setting the device drill axis will be exactly 90° to the
face of the job- Step III.

As shown in fig.8, drilling machine is provided with a variable speed regulator to obtain
a speed for 10 to 1500 RPM depending upon the size of the drill and operation of
drilling, tapping and counter sinking, one switch for reversing the direction of rotation
of drilling machine is also provided for tapping operation -Step IV.
As shown in fig.9, an electrical diagram showing how the variable speed regulator (17)
for operating at variable speeds and reversing the direction of rotation.
As shown in fig.10, the whole arrangement of the device (step-I to step-IV) is mounted
on height adjustable base supports (18,19) for changing height of the device as per
requirement -step V.
As shown in fig.11, a circular T slot (20) made on a round plate. A male and a female
part of the arrangement allows the clamping of cross slide at any angle in horizontal
plane. Longitudinal slide can be related 360° on its vertical axis for drilling holes at any
angle in horizontal plane. Motion of this slide is also used for drilling device for setting
as per surface of the component (as shown in Fig. ll)-Step VI.
As shown in fig.12, the circular motion arrangement is placed on a longitudinal
movement fixture (21) of a main base stand (22)-Step VII.

As shown in fig.13, development of multipurpose drilling device comprises an assembly
starting from top step I to downward step VII and the developed portable drilling
machine is being used successfully for carrying out small drilling and tapping operations
on heavy components of turbo generators replacing the use of costly CMC Horizontal
Boring machine as shown in Fig-14,15,16,17,18,19,20,21,22,23 and 24.

WE CLAIM
1. Development of multipurpose drilling device for working on large size
components of turbo generators comprises the steps of:
(a) taking a standard portable electrical hand drill machine (1) with new coil
winding;
(b) fixing the hand drill machine (1) on a rectangular steel base plate (2) by means
of a clamp (3) at front end and fixing bolt at rear end (4);
(c) welding the base plate (2) with a slight bigger rectangular plate (5) having a
plurality of holes at each corner (6) and middle (7) for fixing with subsequent
attachment;
(d) placing and fixing the drilling machine with base plate-after step (c) on a
rectangular steel plate platform (8) having a plurality of slots (9) parallel to
longitudinal length of the platform and a gear and pinion assembly (10)
engaged in a plate (11) disposed at the opposite side of slotted face of platform
(8) in order to make cross slide (14) and longitudinal slide (15) of the platform
which rest on base clamping plate (12);
(e) placing and fixing the base clamping plate (12)after step (d) on a taper shoe
jack (16) for fine adjustment of height of the machine (1);
(f) placing and fixing the taper shoe jack (16) after step (e) on a circular 'T' slot
(20) made on a round plate wherein a male and a female part of the

arrangement allowed circular T' for clamping cross slide at any angle between
0-360° on horizontal plane;
(g) placing and fixing the circular motion arrangement after step (f) on a
longitudinal movement fixture (21) of a main base stand (22);
2. The multipurpose drilling device a claimed in claim 1, wherein the drilling
machine is operated through a variable speed regulator which provided with one
switch for reverse motion also.
3. The multipurpose drilling device a claimed in claim 1, wherein the height of
device can be increased by placing height adjustable base supports (18,19) in
between step (e) and step (f).

The present invention relates to development of multipurpose drilling device for
working on large size components of turbo generator.