FIELD OF THE INVENTION
The present invention relates to an universal device for mounting of steam
turbine blade resting pads for Root and shroud milling operation on machine.
BACKGROUND OF THE INVENTION
Steam turbine blade is a very precise and critical component of Steam turbine
system. Each stage of steam turbine blades which are fitted into the turbine rotor
has to be very precise dimension wise.
Root and shroud milling of steam turbine blades is carried out by using two
adjacent planes in the blade root and shroud as well as the root slot to
completely define the position of the blade in the fixture on a horizontal milling
machine.
The fixture which is used to carry out root and shroud milling is a specially
designed one. At present root and shroud milling is carried out by using fixed
pads at root and shroud to clamp the blade horizontal in such a way that blade
central axis remains parallel to the machine fixture. For carrying out the operation,
the position of the blade in the machine fixture is completely defined by root
locator with the help of root slot.
Now, these pads are mounted on the fixture body through M8 bolts. And as the
geometries of the blades change very frequency among different designs, these
pads need to be changed on daily basis. This frequent tightening and loosening
of the pads on the fixture body slowly lead to wear and tear of the threads
present in it. Fixture being a costly capital item, it cannot be replaced from time to
time whenever a thread fails in the body. So, need was there to devise a device
for safe mounting of the pads, which can prevent the failure of the fixture due to
thread damage.

OBJECTS OF THE INVENTION
It is therefore an object of the present invention to propose an universal device
for mounting of steam turbine blade resting Root and shroud milling pads on
machine, which eliminates fixture failure due to repeated fitment and removal of
the pads on the machine fixture body.
Another object of this invention is to propose an universal device for mounting of
steam turbine blade resting Root and shroud milling pads on machine, which
reduces the machine down time otherwise would have incurred to rectify a
damaged thread.
A still another object of this invention is to propose an universal device for
mounting of steam turbine blade resting Root and shroud milling pads on
machine, which improve the productivity of Root and shroud milling of steam
turbine blades.
A further object of this invention is to propose an universal device for mounting of
steam turbine blade resting Root and shroud milling pads on machine, which
enhances quality of steam turbine blades by eliminating rework and rejection on
account of frequent mounting and dismounting of pads on the machine fixture.
SUMMARY OF THE INVENTION
Accordingly, there is provided an universal device for mounting of steam turbine
blade resting Root and shroud milling pads on machine. The device comprising:
- an intermediate plate (1);
- a slotted fixture pad (2); and
- at least six numbers of screws (3).

The intermediate plate (1) is used to mount the slotted fixture pads (2) with the
help of the screws (3). The intermediate plate (1) then mounted on the machine
fixture body.
The slotted fixture pads (2) are used for placement of the steam turbine blade in
the required orientation. This is mounted on the intermediate plate (1) with the
help of the screws (3).
The screws (3) are used for fitment of the slotted fixture pads (2) on the
intermediate plate (1) and again for the fitment of the intermediate plate (1) on
the machine fixture body.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 shows a 3d model of the machine fixture explaining the entire Root and
shroud milling machine.
Figure 2 shows the top, bottom and side view of the intermediate plate of the
invented device.
Figure 3 shows a 3d model of the intermediate plate.
Figure 4 shows the top, bottom and side view of the slotted fixture pads of the
device of the invention.
Figure 5 shows a 3d model of the slotted fixture pads.
Figure 6 shows a 3d model of standard M6 screws used for the device.

Figure 7 shows the invented device for mounting of the pads on the machine
fixture through the intermediate plate.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE
PRESENT INVENTION
As shown in the figures, the device comprises mainly three parts. A slotted fixture
pad (2) shall remain in contact with the blade. This fixture pad is mounted on an
intermediate plate (1) with the help of screws (3). This intermediate plate (1) is in
turn mounted on the machine fixture body through two Screws at the center of
the plate.
This arrangement facilitates frequent mounting and dismounting of the slotted
fixture pads (2) while the intermediate plate (1) is kept fixed on the machine
fixture. Now, due to frequent tightening/ loosening of the mounting screws (3),
the wear and tear now takes places in the threads of the intermediate plate (1)
instead of the machine fixture. Any failure of threads will now result only in the
failure of the intermediate plate (1) which can very economically be changed as
compared to replacement of the entire machine fixture.
This will not only eliminate the down time of the machine incurred on account of
fixture unavailability, but also improve the quality of blades by eliminating the
rework/ rejection generated due to loose fitment of fixture pads.

ADVANTAGES OF THE INVENTION
(1) The inventive device including positioning of the pads on the machine fixture
for the root and shroud milling operation on horizontal milling center, results in
prevention of thread damage on the machine fixture.
(2) Standardization of the mounting arrangement of fixture pads in the root and
shroud milling operation of steam turbine blades on horizontal machine
centers is achieved.
(3) The invention increases productivity of the root and shroud milling operation
on horizontal machining centers by reducing the down time.
(4) The invention reduces rework and rejection caused in manufacturing of
blades due to loose fitment of the pads.

WE CLAIM
1. An universal device for mounting of steam turbine blade resting Root and
shroud milling pads on machine, the device comprising:-
- A slotted fixture pad (2) remaining in contact with the steam turbine blade
when loaded on the machine;
- an intermediate plate (1) removably accommodating the fixture pad (2) via
at least four standard M16 screws (3),
wherein the intermediate plate (1) including the fixture pad (2) is mounted on
the machine fixture, wherein the intermediate plate (1) remains mounted on
the machine fixture, and wherein the slotted fixture pad (2) is only mounted
and dismounted depending on the different geometry of the steam turbine
blades undergoing root and shroud milling on the machine, thereby
preventing damage of the machine fixture due to frequent mounting and
dismounting of the blade which damage is now sustained by the slotted
fixture pads (2).
2. The device as claimed in claim 1, wherein all the components of the device
are hardened.