FIELD OF INVENTION :
The present invention relates to an arrangement of fixture position and
new hydraulic circuit in case of fixture for root and shroud milling of bar type
steam turbine blades on horizontal milling machine. More particularly the present
invention relates to establishment of optimum fixture position and hydraulic
arrangement of fixture in case of root and shroud machining of steam turbine
blades to reduce cycle time and manual effort.
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. For loading the blades, first the fixture has to be rotated by 180
degrees. Then the blade is placed in the fixture and is clamped. After clamping
the blade, the fixture has to be again rotated back in place before machining can
take place.
In this system, however, due to the need for manual rotation of the
fixture, unnecessary human effort is wasted. This system also results in longer
cycle times of manufacturing as rotating the fixture takes extra time. Also there
is a chance of error as the fixture may not be rotated in its proper place due to
human error.

OBJECTS OF THE INVENTION :
Therefore, it is an object of the invention to propose an arrangement of
fixture position and new hydraulic circuit in case of fixture for root and shroud
milling of bar type steam turbine blades on horizontal milling machine which is
capable of eliminating the need for rotating the fixture when loading/unloading
steam turbine blades.
Another object of the invention is to propose an arrangement of fixture
position and new hydraulic circuit in case of fixture for root and shroud milling of
bar type steam turbine blades on horizontal milling machine which is capable of
establishing a new hydraulic circuit for the fixture to work in its new position.
A further object of the invention is to propose an arrangement of fixture
position and new hydraulic circuit in case of fixture for root and shroud milling of
bar type steam turbine blades on horizontal milling machine which is capable of
reducing the amount of manual labour required for root and shroud milling of
steam turbine.
A still another object of the invention is to propose an' arrangement of
fixture position and new hydraulic circuit in case of fixture for root and shroud
milling of bar type steam turbine blades on horizontal milling machine which is
able to improve the productivity of root and shroud milling of steam turbine lock
blades by reducing cycle time.
A still further object of the invention is to propose an arrangement of
fixture position and new hydraulic circuit in case of fixture for root and shroud
milling of bar type steam turbine blades on horizontal milling machine which can
improve the safety of root and shroud milling process of steam turbine lock
blades by reducing the chance of human error in blade loading/unloading.

SUMMARY OF THE INVENTION :
Accordingly, there is provided a fixture for the Root and Shroud Milling on
CNC horizontal machining center. The fixture has two sides - RS milling side and
centering side.
Prior to the invention, the machine used to bring the centering side of the
fixture to the loading door, which necessitated the rotating of the fixture to load
a steam turbine blade for RS milling operation.
The proposed invention re-orients the fixture and reconfigures the
hydraulic circuit such that the machine now brings the RS milling side of the
fixture to the loading door for steam turbine blade loading and unloading.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS:
Fig. 1 : Shows a 3D model of the fixture in the machine. The machine doors are
open and the RS milling side of the fixture is facing the doors.
Fig.2 : Shows how prior to the invention the fixture would come to the loading
area with the centering side facing the door.
Fig.3-: Shows how prior to the invention the fixture would come to the machining
area with the centering side facing the machine.
Fig. 4 : Shows how after the invention the fixture now comes to the loading area
with the RS milling side facing the doors.
Fig.5 : Shows how after the invention the fixture now comes to the machining
area with the RS milling side facing the machine.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION:
The fixture used for root and shroud milling of steam turbine blades has
two sides. One is used for carrying out root and shroud milling of steam turbine
blades while the other is used for carrying out centering of blanks.
Prior to the invention the fixture would come to the loading area with the
centering side facing the door. This would necessitate manual rotation of the
fixture (180 Degrees) by the operator to bring the RS side forward. The operator
would then load the blade, clamp it and again manually rotate the fixture back,
turning the RS side inward.
The doors would then be locked and the machine would rotate the fixture
in to the machining area.
Even the fixture would come to the machining area with the centering
side facing the machine and the machine would rotate the fixture to bring the RS
side towards the machine before carrying out root and shroud milling operation.
The invention consists of rotating the fixture in its place and re-setting its
hydraulic circuit such that the fixture now comes to the loading area with the RS
milling side facing the doors.
This eliminates the need for manual rotation of the fixture by machine
operator.

Also the fixture now comes to the machining area with the RS milling side
facing the machine further saving time.
ADVANTAGES OVER THE PRIOR ARTS:
1. A new fixture orientation and hydraulic arrangement of fixture of root and
shroud milling on horizontal milling center which ensures that the root and
shroud side of the fixture is presented on the door for loading and unloading.
2. The new arrangement reduces the operator's manual labor during loading
and unloading of blades for root and shroud milling operation.
3. The new arrangement increases productivity of root and shroud milling
operation by reducing the cycle time.
4. The new arrangement ensures safety by eliminating the chances of
human error during loading/unloading of steam turbine blades for root and
shroud milling.

WE CLAIM :
1. An arrangement of fixture position and new hydraulic circuit in case of
fixture for root and shroud milling of bar type steam turbine blades on horizontal
milling machine, the said arrangement comprising;
arranging a new hydraulic circuit for the fixture (F) to work in its new
position;
orienting the fixture (F) to bring RS milling side of the fixture to the
loading door (D) for allowing steam turbine blade facing the door;
loading and clamping the blades; wherein,
the fixture (F) moves to the machining area with RS milling side facing the
machine for blade machining.

ABSTRACT

The invention relates to an arrangement of fixture position and new
hydraulic circuit in case of fixture for root and shroud milling of bar type steam
turbine blades on horizontal milling machine. A new hydraulic circuit is
implemented for the fixture (F) to work in its new position. The fixture (F) is
oriented to bring RS milling side of the fixture to the loading door (D) for
allowing steam turbine blade facing the door. The blades are loaded and
clamped, when the fixture moves to the machining area with RS milling side
facing the machine for blade machining.