FIELD OF INVENTION
The present invention relates to a universal adjustable holding and cutting
device for extra material removal of root and shroud of turbine blades after 5 axis
machining but before milling on a horizontal milling center (HMC) by abrasive cutting.
More particularly, the invention relates to a device and method for end cutting of steam
turbine blades on an abrasive wheel that results in reduction of insert consumption and
cycle time reduction on a HMC machine.
BACKGROUND OF THE INVENTION
Presently after the machining of root and shroud of steam turbine blades
on 5 axis machine, the finished and complete root and shroud milling operation is
carried out by face milling operation on 4-axis CNC horizontal machining center.
It is observed that because of excessive machining allowance left on the
root and shroud (RS) of the blades after the 5-axis machining, the final milling
operation of root and shroud results high consumption of costly milling inserts on the
HMC machine. Also, the cycle time required for RS milling of the blades was found to be
very high.
Because of the above said disadvantages of the existing method of
machining, a new step has been introduced ahead of the HMC operation so that about
90% of the machining allowance is reduced. This necessiated a new holding device

and method of material removal. Hence, a universal adjustable holding device is
introduced along with a process of abrasive cutting by a cut off abrasive wheel in
process planning of root and shroud machining.
This resulted to a net saving on machining time as well as tooling cost and
productivity.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose a universal
adjustable holding and cutting device for extra material removal of root and shroud of
turbine blades after 5 axis machining but before milling on a horizontal milling center
(HMC) by abrasive cutting which is capable of reducing the machining allowance for
HMC milling.
Another object of the invention is to propose a universal adjustable
holding and cutting device for extra material removal of root and shroud of turbine
blades after 5 axis machining but before milling on a horizontal milling center (HMC) by
abrasive cutting which is able to reduce the consumption of milling inserts on HMC
machine.
A further object of the invention is to propose a universal adjustable
holding and cutting device for extra material removal of root and shroud of turbine
blades after 5 axis machining but before milling on a horizontal milling center (HMC) by
abrasive cutting which is capable of reducing the cycle time of RS milling of steam
turbine blades.
A still further object of the invention is to propose a universal adjustable
holding and cutting device for extra material removal of root and shroud of turbine

blades after 5 axis machining but before milling on a horizontal milling center (HMC) by
abrasive cutting which results in the improvement of productivity.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Fig. 1 - Shows the universal adjustable device along with abrasive cutting wheel.
Fig. 2A and Fig. 2B - Shows the fixed dovetail rail of the device according to the
invention.
Fig. 3A and Fig. 3B - Shows the sliding block of the device according to the
invention.
Fig. 4A and Fig. 4B - Shows the main supporting pad of the device according to
the invention.
Fig. 5A and Fig. 5B - Shows the pad for extra material removal from root
according to the invention.
Fig. 6A and Fig. 6B - Shows the pad for extra material removal from shroud
according to the invention.
Fig. 7A and Fig. 7B - Shows the fixed support block pad for extra material
removal from root.
Fig. 8 - Shows the bolt for adjustment.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
Fig. 1 shows the universal adjustable device (1) along with abrasive wheel
driving system (9) having a abrasive cutting wheel (10). In this process the blade of the
turbine is rested in the universal adjustable device (1) in such a manner with pre-
calculation that when the rotating abrasive wheel (10) is brought in contact with the
blade, it automatically cuts the extra material on the blade.
The device (1) consists of fixed dovetail rail (2) as shown in Fig. 2A and
Fig. 2B which guides the sliding block (3) shown in fig 3A and fig. 3B. The arrangement
supports the sliding of sliding block (3) to hold the main supporting pad (4). This is
done to accommodate a wide range of blade rhomboid sizes. The sliding block (3) is
guided by the fixed dovetail rail (2) by the rotation of bolt (8) which adjusts the space
between the sliding block (3) and the fixed block (11). The bolt (8) is threadedely fixed
to the fixed block (11) so that when the bolt (8) rotates against the block (11) the
sliding block (3) moves towards the fixed block (11) sliding along the dovetail block (2).
Main supporting pad (4) as shown in fig. 4A and fig. 4B rests upon the fixed dovetail
rail-sliding block assembly (2 and 3) as shown in fig. 1. The position of this pad is pre-
calculated depending upon the technical allowances taken during the blade machining
and for supporting the pad (5) for extra material removal from root or pad (6) for extra
material removal from shroud.
Pads 4, 5, 6 make the clamping device universal. Dimension of Pad (4)
remains fixed and is used only for support. Pads (5, 6) have been manufactured
keeping the dimensions of the blade being machined. By varying the dimensions of
pads (5) and (6) we can carry out root and shroud cutting operation for all blade sizes.

Pad (5) used for extra material removal from root is shown in fig. 5A and
fig. 5B and pad (6) used for extra material removal from shroud is shown in fig. 6A and
fig. 6B. There is also a fixed support block pad (7) for extra material removal from root
disposed in the device (1). The bolt (8) is shown in fig. 8 pad (5) for extra material
removal from root is designed such that it can axially orient the blade in such a manner
that the extra material from the root can be removed by abrasive cutting wheel (10)
and the dimensions of the aforesaid pad remains fixed as technical allowance of blade
at root is fixed. Pad (6) for extra material removal from shroud is designed such that it
can axially orient the blade in such a way that the extra material from the shroud can
be removed by the abrasive cutting wheel (10) and the dimensions of the aforesaid pad
(6) remains fixed as technical allowance of blade at shroud is fixed.
The fixed support block pad (7) for extra material removal from root. This
is to support the root while cutting extra material from shroud and vice-versa.
The abrasive wheel driving system of the holding and cutting device (1)
consists of a cutting wheel (10) fixed to a handle (12). The handle is hinged with a
block (13). The block is fixed to a heavy base (14). The handle (12) is pulled
downwards at the time of cutting the extra material of root and shroud. The wheel (10)
gets its rotational power from a three phase induction motor not shown in the drawing.

WE CLAIM
1. An universal adjustable holding and cutting device for extra material removal of
root and shroud of turbine blades before milling operation on HMC machine
comprising;
a fixed dovetail rail (2) for guiding a sliding block (3);
a sliding block (3) for guiding over the dovetail rail (2);
a fixed block (11) disposed on the base of dovetail rail (2);
a bolt (8) passing through a hole in the sliding block (3) and threaded into the
fixed block (11) for moving the sliding block (3) over dovetail rail (2);
characterized in that;
a main supporting pad (4) rested upon the fixed dovetail rail-sliding block
assembly is disposed in a position based on pre calculation according to the
technical allowances taken during blade machining when pads (5 and 6) are used
for extra removal of root and shroud respectively wherein a fixed support block
pad (7) supports the root while cutting extra material from the shroud and
supports the shroud while cutting extra material from root wherein the extra
material of root and shroud of the blade is cut by the cutting wheel (10) disposed
in the device (1).
2. The device as claimed in claim 1, wherein the pads (4, 5, 6) are rested in the
dovetail rail-sliding block assembly.

ABSTRACT

The invention relates to an universal adjustable holding and cutting device for
extra material removal of root and shroud of turbine blades before milling operation on
HMC machine. The device comprising a fixed dovetail rail (2) for guiding a sliding block
(3) over it. A fixed block is disposed on the base of the dovetail rail (2). A bolt (8)
passing through a hole in the sliding block (3) is threaded into the fixed block (11) for
moving the sliding block (3) over dovetail rail (2). A main supporting pad (4) rested
upon the fixed dovetail rail-sliding block assembly is disposed in a position based on pre
calculation according to the technical allowances taken during blade machining when
pads (5 and 6) are used for extra removal of root and shroud respectively wherein a
fixed support block pad (7) supports the root while cutting extra material from the
shroud and supports the shroud while cutting extra material from root wherein the
extra material of root and shroud of the blade is cut by the cutting wheel (10) disposed
in the device (1).