Claims:We claim:
1) An apparatus (200) to facilitate in root machining operation on raw material blanks (22), said apparatus (200) comprising:
a) a mounting plate (24) having a ring shape defining a hole (H1) therein at the center, a plurality of grooves (G1) equidistantly spaced on its circumferential edge, a plurality of holes (H2) provided perpendicularly to equidistantly spaced radial lines, a plurality of holes (H3 and H4) provided parallel to the equidistantly spaced radial lines on their either side and a plurality of holes (H5) provided in between the equidistantly spaced radial lines therein in an alternate manner, said mounting plate exactly mounted at the center of a rotary bed of a vertical turning lathe (VTL) machine such that a plurality of grooves of the rotary bed of the VTL machine are in line to the plurality of grooves (G1) of the mounting plate (24) and locked in position ;
b) a plurality of abutting blocks (26) having at least one hole (H6) provided therein complementary to the hole (H3) of said mounting plate (24), placed adjoining to said raw material blanks (22) mounted along the equidistantly spaced radial lines of said mounting plate (24) and locked in position ;
c) a plurality of movement arresting blocks (28) having at least one hole (H7) provided therein complementary to the holes (H2 and H4) of said mounting plate and one hole (H8) provided there through across them, said plurality of movement arresting blocks (28) placed parallel and perpendicular to the equidistantly spaced radial lines of said mounting plate (24) and locked in position with the help of a plurality of bolts (38), said plurality of bolts (38) passes through the hole (H8) of the plurality of movement arresting blocks (28) and adapted to mount against said raw material blanks (22) thereby pressing the raw material blanks (22) against said plurality of abutting blocks (26) and arresting their movement ; and
d) a plurality of clamps (30 and 32) provided with a slot (S1) therein, mounted over said raw material blanks (22) such that the slot (S1) of said plurality of clamps (30 and 32) encompasses a plurality of dowel bolts (36) projecting out from the plurality of holes (H5) of said mounting plate (24) and locked in position.

2) An apparatus (200) to facilitate in root machining operation on raw material blanks (22) as claimed in claim 1, wherein angle between said equidistantly spaced radial lines is determined based on the number of said raw material blanks (22) to be placed on said mounting plate (24).

3) An apparatus (200) to facilitate in root machining operation on raw material blanks (22) as claimed in claim 1, wherein said plurality of bolts (38) passing through the hole (H8) of said plurality of movement arresting blocks (28) facilitates in accommodating the raw material blanks (22) of different heights and widths.

4) An apparatus (200) to facilitate in root machining operation on raw material blanks (22) as claimed in claim 1, wherein said raw material blanks (22) are arranged along the equidistantly spaced radial lines to form exactly circular shape.

5) An apparatus (200) to facilitate in root machining operation on raw material blanks (22) as claimed in claim 1, wherein tools of said vertical turning lathe (VTL) machine approaches from side face of said raw material blanks (22).

6) An apparatus (200) to facilitate in root machining operation on raw material blanks (22) as claimed in claim 1, wherein said plurality of bolts (38) are adapted to mount against said raw material blanks (22) by tightening said plurality of bolts (38) in said plurality of movement arresting blocks (28).

7) An apparatus (200) to facilitate in root machining operation on raw material blanks (22) as claimed in claim 1, wherein said plurality of clamps (30 and 32) are locked in position by means of a plurality of nuts (40).

8) A method of using an apparatus (200) to facilitate in root machining operation on raw material blanks (22), said method comprising the steps of :
a) placing a mounting plate (24) of said apparatus (200) on a rotary bed of a vertical turning lathe(VTL) machine and locked in position;
b) mounting a plurality of abutting blocks (26) around circumference of said mounting plate (24) at predetermined positions parallel to equidistantly spaced radial lines and locked in position;
c) mounting a plurality of movement arresting blocks (28) around circumference of said mounting plate (24) at predetermined positions parallel and perpendicular to the equidistantly spaced radial lines and locked in position;
d) placing said raw material blanks (22) along the equidistantly spaced radial lines adjacent to said plurality of abutting blocks (26);
e) passing a plurality of bolts (38) through a hole (H8) of said plurality of movement arresting blocks (28) and adapted to mount against said raw material blanks (22) thereby pressing the raw material blanks (22) against said plurality of abutting blocks (26) and arresting their movement; and
f) mounting a plurality of clamps (30 and 32) over said raw material blanks (22) in such a way that a slot (S1) provided therein encompasses a plurality of dowel bolts (36) projecting out from said mounting plate (24) in an alternate manner in between said raw material blanks (22) and locked in position.

9) A method of using an apparatus (200) to facilitate in root machining operation on raw material blanks (22), wherein said predetermined positions for mounting said plurality of abutting blocks (26) and said plurality of movement arresting blocks (28) on said mounting plate (24) are determined based on the angle between said equidistantly spaced radial lines.

10) A method of using an apparatus (200) to facilitate in root machining operation on raw material blanks (22), wherein said raw material blanks (22) are mounted vertically on said apparatus (200).
, Description:FIELD OF THE INVENTION:
The present invention relates to the field of an apparatus and a method to facilitate in performing root machining operation on raw material blanks. Particularly, the present invention relates to an apparatus and a method to facilitate in performing straddle fir tree root machining operation on raw material blanks.

BACKGROUND OF THE INVENTION:
Traditionally in steam turbine industry, different types of root configurations like T-root, fir tree root, fork root, straddle root etc., are employed considering various factors like loading on blades, stress distribution, contact surface area, ease of manufacturing and cost implications. Generally, as root configurations are of complex shape, it is a common practice to use 5-axis CNC machine for root machining. Performing operation on 5-axis CNC machine requires good programming expertise and skilled labour.

Figure 1 illustrates a front view of straddle fir tree root blade.
The crux of this invention lies in fixture and method employed in machining the desired shape of the root of the blade marked as portion A of figure 1.

Figure 2(a) illustrates a perspective view of a conventional fixture employed in straddle fir tree root machining according to the prior art.

Figure 2(b) illustrates a perspective view of a conventional fixture employed in straddle fir tree root machining having a raw material blank mounted on it according to the prior art.
The conventional fixture 100 comprises a cylindrical block 12, a semi circular block 14,
a clamping plate 16 and a plurality of fasteners 18. The semi circular block 14 having a provision P on its top surface is coupled to the cylindrical block 12 which in turn is attached to the chuck of a CNC machine. A raw material blank 22 is placed in the provision P of the semi circular block 14 and held in position by placing the clamping plate 16 over the semi circular block 14 thereby clamping each other with the help of the plurality of fasteners 18.
Typically, the raw material blank 22 is mounted horizontally on the conventional fixture 100.

In this conventional method, the tool engages with the raw material blank from its front face and only one blade root can be machined at a time. The loading/unloading time for each raw material blank in the conventional fixture is 3 minutes and the cutting time for straddle fir tree root roughing and finishing operations on each raw material blank is 3 hours and 30 minutes. So, the total cycle time required to achieve straddle fir tree root on each raw material blank is 3 hours and 33 minutes.

Fixtures are the devices which hold the work piece during machining operation. Several techniques have been disclosed in the prior art to hold the work piece firmly during machining.

IN Patent Application no. 201641010347 filed on March 25, 2016 titled “A fixture to facilitate in slot milling operation on an unfinished locknut and a method thereof” discloses a fixture and a method which addresses the problems associated with conventional method of slot milling operation on an unfinished locknut like wastage of raw material, greater time involved in setup operation of each unfinished locknut, effort and skill of the operator involved in each setup operation, high scope for variation of locknuts finally produced, high chances of errors etc., The fixture and the method in accordance with the present invention provides a simple and fool proof fixture which can help to produce greater number of locknuts from a given raw material and which can reduce time and effort involved in setup of each unfinished locknut. This fixture is apt only for holding specific type of work pieces like cylindrical objects and can hold only one work piece at a time.

IN Patent Application no. 1041/CHE/2015 filed on March 4, 2015 titled “A compound adjustment fixture for pitch milling operation” discloses a fixture which addresses the problems associated with conventional compound angle adjustment fixture like difficulty in adjusting a work piece at any desired compound angle relative to the machining tool, non removal of uniform thickness of material on compound angle surface of the work piece, not developed particularly for blades as work pieces, not suitable for mounting on bed of CNC machines etc., The fixture in accordance with the present invention provides a simple, easy to use and easy to adjust compound angle adjustment fixture which can hold work pieces at any desired compound angle relative to the machining tool and which can accommodate different sizes of work pieces. This fixture also holds only one work piece at a time.

IN Patent Application no. 1089/CHE/2013 filed on March 14, 2013 titled “A fixture to facilitate in performing pitch milling on the root of the T-root blades” discloses a fixture which addresses the problems associated with the conventional fixture like difficulty in achieving a plane surface on the root of the blades and long set up time. The fixture in accordance with the present invention provides a simple fixture which can facilitate in easy removal of uniform material on root of the T-root blades.

Therefore, there is felt a need for development of an apparatus and a method to facilitate in root machining operation on raw material blanks to overcome the drawbacks of the prior art and thereby increase the productivity of straddle fir tree root machining.

OBJECTS OF THE INVENTION:
An object of the present invention is to provide a simple and fool proof apparatus for straddle fir tree root machining.

Another object of the present invention is to perform straddle fir tree root machining operation on a simple CNC machine.

One more object of the present invention is to perform straddle fir tree root machining operation in less cycle time.

Still another object of the present invention is to improve productivity of straddle fir tree root machining operation.

Further another object of the present invention is to perform straddle fir tree root machining operation even with semi skilled labour also.

Yet one more object of the present invention is to save power consumed by a CNC machine while performing straddle fir tree root machining operation.

Still one more object of the present invention is to perform straddle fir tree root machining operation at cheap cost.

SUMMARY OF THE INVENTION:
In accordance with the present invention an apparatus (200) to facilitate in root machining operation on raw material blanks (22) is provided, the apparatus (200) comprising :
i) a mounting plate (24) having a ring shape defining a hole (H1) therein at the center, a plurality of grooves (G1) equidistantly spaced on its circumferential edge, a plurality of holes (H2) provided perpendicularly to equidistantly spaced radial lines, a plurality of holes (H3 and H4) provided parallel to the equidistantly spaced radial lines on their either side and a plurality of holes (H5) provided in between the equidistantly spaced radial lines therein in an alternate manner, the mounting plate exactly mounted at the center of a rotary bed of a vertical turning lathe (VTL) machine such that a plurality of grooves of the rotary bed of the VTL machine are in line to the plurality of grooves (G1) of the mounting plate (24) and locked in position;

ii) a plurality of abutting blocks (26) having at least one hole (H6) provided therein
complementary to the hole (H3) of the mounting plate (24), placed adjoining to the
raw material blanks (22) mounted along the equidistantly spaced radial lines of the
mounting plate (24) and locked in position;

iii) a plurality of movement arresting blocks (28) having at least one hole (H7) provided therein complementary to the holes (H2 and H4) of the mounting plate and one hole (H8) provided there through across them, the plurality of movement arresting blocks (28) placed parallel and perpendicular to the equidistantly spaced radial lines of the mounting plate (24) and locked in position with the help of a plurality of bolts (38), the plurality of bolts (38) passes through the hole (H8) of the plurality of movement arresting blocks (28) and adapted to mount against the raw material blanks (22) thereby pressing the raw material blanks (22) against the plurality of abutting blocks (26) and arresting their movement; and

iv) a plurality of clamps (30 and 32) provided with a slot (S1) therein, mounted over the raw material blanks (22) such that the slot (S1) of the plurality of clamps (30 and 32) encompasses a plurality of dowel bolts (36) projecting out from the plurality of holes (H5) of the mounting plate (24) and locked in position.

Typically, the angle between the equidistantly spaced radial lines is determined based on the number of the raw material blanks (22) to be placed on the mounting plate (24).

Typically, the plurality of bolts (38) passing through the hole (H8) of the plurality of movement arresting blocks (28) facilitates in accommodating the raw material blanks (22) of different heights and widths.

In accordance with the present invention a method to facilitate in root machining operation on raw material blanks (22) is provided, the method comprising the steps of:
i) placing a mounting plate (24) of the apparatus (200) on a rotary bed of a vertical
turning lathe(VTL) machine and locked in position;
ii) mounting a plurality of abutting blocks (26) around circumference of the
mounting plate (24) at predetermined positions parallel to equidistantly spaced radial lines and locked in position;
iii) mounting a plurality of movement arresting blocks (28) around circumference of
the mounting plate (24) at predetermined positions parallel and perpendicular to the equidistantly spaced radial lines and locked in position;
iv) placing the raw material blanks (22) along the equidistantly spaced radial lines
adjacent to the plurality of abutting blocks (26);
v) passing a plurality of bolts (38) through a hole (H8) of the plurality of movement
arresting blocks (28) and adapted to mount against the raw material blanks (22) thereby pressing the raw material blanks (22) against the plurality of abutting blocks (26) and arresting their movement; and
vi) mounting a plurality of clamps (30 and 32) over the raw material blanks (22) in
such a way that a slot (S1) provided therein encompasses a plurality of dowel bolts (36) projecting out from the mounting plate (24) in an alternate manner in between
the raw material blanks (22) and locked in position.
Typically, the raw material blanks (22) are mounted vertically on the apparatus (200).

BRIEF DESCRIPTION OF THE DRAWINGS:
The invention will now be described with reference to the accompanying drawings in which:
Figure 1 illustrates a front view of straddle fir tree root blade;

Figure 2(a) illustrates a perspective view of a conventional fixture employed in straddle fir tree root machining according to the prior art;

Figure 2(b) illustrates a perspective view of a conventional fixture employed in straddle fir tree root machining having a raw material blank mounted on it according to the prior art;

Figure 3 illustrates a perspective view of an apparatus employed to facilitate in straddle fir tree root machining operation on raw material blanks in accordance with the present invention;

Figure 4 illustrates a perspective view of a mounting plate of figure 3;

Figure 5 illustrates a perspective view of an abutting block of figure 3;

Figure 6 illustrates a perspective view of a movement arresting block of figure 3;

Figure 7(a) and 7(b) illustrates a perspective view of a clamp of first type and a clamp of second type respectively of figure 3;

Figure 8 illustrates an isometric view of a dowel bolt of figure 3; and

Figure 9 illustrates a perspective view of raw material blanks after straddle fir tree root machining operation in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
A preferred embodiment will now be described in detail with reference to accompanying drawings. The preferred embodiment does not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.

Figure 3 illustrates a perspective view of an apparatus employed to facilitate in straddle fir tree root machining operation on raw material blanks.
In accordance with the present invention, there is provided an apparatus 200 to facilitate in straddle fir tree root machining operation on a plurality of raw material blanks 22 comprising a mounting plate 24, a plurality of abutting blocks 26, a plurality of movement arresting blocks 28, a plurality of clamps of first type 30, a plurality of clamps of second type 32, a plurality of dowel pins 34, a plurality of dowel bolts 36, a plurality of bolts 38 and a plurality of nuts 40.

The number of the plurality of raw material blanks 22 to be equidistantly spaced around the circumference of the mounting plate 24 is first determined depending on the circumference of the mounting plate 24 and the width of the raw material blanks 22.

The angle at which each of the raw material blanks 22 are supposed to be placed from each other around the circumference of the mounting plate 24 = Angle of a circle (360 deg)/No. of raw material blanks (22).

So, each of the raw material blanks 22 are placed at an equidistant angle of 16.36 degrees around the circumference of the mounting plate 24.

Figure 4 illustrates a perspective view of a mounting plate of figure 3.
The mounting plate 24 is typically a circular plate of predetermined radius depending on the radius of the rotary bed of Vertical Turning Lathe (VTL) machine. The mounting plate 24 is provided with a plurality of grooves G1 on its circumferential edge complementary to the grooves of the rotary bed of Vertical Turning Lathe (VTL) machine. A hole H1 is provided at the center of the mounting plate 24 to facilitate in placing the mounting plate 24 exactly at the center of the rotary bed of Vertical Turning Lathe (VTL) machine. To facilitate in marking of holes around the circumference of the mounting plate 24, a plurality of radial lines equidistantly spaced at an angle of 16.36 degrees are marked. Accordingly, a plurality of set of two holes H2 equidistantly spaced at an angle of 16.36 degrees around the circumference of the mounting plate 24 perpendicular to the plurality of radial lines are provided for locking of the plurality of movement arresting blocks 28, a plurality of set of four holes H3 equidistantly spaced around the circumference of the mounting plate 24 parallel to the plurality of radial lines are provided for locking of the plurality of abutting blocks 26, a plurality of set of two holes H4 equidistantly spaced around the circumference of the mounting plate 24 parallel to the plurality of radial lines are provided for locking of the plurality of movement arresting blocks 28 and a plurality of holes H5 equidistantly spaced at an angle of 40 degrees in concentric circles around the circumference of the mounting plate 24 in between alternate plurality of radial lines are provided for locking of the plurality of dowel bolts 36.

Typically, all the plurality of holes (H2, extreme holes of H3, H4 and H5) are threaded.

Typically, the two holes in between the extreme holes of H3 are plain.

Figure 5 illustrates a perspective view of an abutting block of figure 3.
Four holes H6 complementary to the set of four holes H3 of the mounting plate 24 are drilled on top face of the abutting block 26. The extreme holes of H6 of the abutting block 26 are counter bore and threaded. The two holes in between the extreme holes of H6 of the abutting block 26 are plain.

Figure 6 illustrates a perspective view of a movement arresting block of figure 3.
Two holes H7 complementary to the set of two holes (H2 and H4) of the mounting plate 24 are drilled on top face of the movement arresting block 28. A hole H8 is drilled at the center across the movement arresting block 28. The two holes H7 of the movement arresting block 28 are counter bore and threaded. The hole H8 of the movement arresting block 28 is threaded.

Figure 7(a) and 7(b) illustrates a perspective view of a clamp of first type and a clamp of second type respectively of figure 3.
The clamp of first type 30 and the clamp of second type 32 are blocks provided with a slot S1 therein.

Figure 8 illustrates an isometric view of a dowel bolt of figure 3.
The dowel bolt 34 is threaded on its both ends.

Figure 9 illustrates a perspective view of raw material blanks after straddle fir tree root machining operation.

The configuration and method of working of the apparatus 200 to facilitate in straddle fir tree root machining operation on a plurality of raw material blanks 22 in accordance with the present invention is as follows:
The mounting plate 24 is exactly mounted at the center of the rotary bed of the vertical turning lathe (VTL) machine and locked in position with the help of fasteners passing through the grooves of the rotary bed of the VTL machine and the plurality of grooves G1 of the mounting plate 24. The plurality of raw material blanks 22 are placed along the equidistantly spaced plurality of radial lines around the circumference of the mounting plate 24 to form a circular shape. The plurality of abutting blocks 26 are placed adjoining
the plurality of raw material blanks 22 around the circumference of the mounting plate 24
such that the four holes H6 of the abutting blocks 26 are in line to the set of four holes H3 of the mounting plate 24. Proper butting surface between the plurality of raw material blanks 22 and the plurality of abutting blocks 26 is crucial to maintain circular shape of the plurality of raw material blanks 22 and is achieved by inserting the plurality of dowel pins 34 in to the holes H6 of the abutting blocks 26 and the holes H3 of the mounting plate 24. The plurality of abutting blocks 26 are locked to the mounting plate 24 by means of the plurality of bolts 38 passing through the holes H6 of the abutting blocks 26 and the holes H3 of the mounting plate 24. The plurality of movement arresting blocks 28
are placed parallel and perpendicular to the plurality of raw material blanks 22 in such a way that the two holes H7 of the movement arresting blocks 28 are in line to the set of two holes (H2 and H4) of the mounting plate 24 and locked in position by means of the plurality of bolts 38. The plurality of bolts 38 passes through the hole H8 of the plurality of movement arresting blocks 28 and adapted to mount against the plurality of raw material blanks 22 thereby pressing the plurality of raw material blanks 22 against the plurality of abutting blocks 26 and restricting the movement of the plurality of raw material blanks 22 towards backside and sideways. The plurality of dowel bolts 36 are adapted to pass through the plurality of holes H5 of the mounting plate 24 and locked in position. The plurality of clamps of first type 30 and the plurality of clamps of second type 32 are placed in inverted manner to each other over the plurality of raw material blanks 22 in such a way that the slot S1 of the plurality of clamps of first type 30 and the plurality of clamps of second type 32 encompasses the plurality of dowel bolts 36 and locked in position by means of the plurality of nuts 40.

The provision of the hole H8 in the plurality of movement arresting blocks 28 facilitates in accommodating the raw material blanks 22 of different heights and widths.

The plurality of raw material blanks 22 are mounted vertically on the apparatus 200.

The tool of the vertical turning lathe (VTL) machine approaches from side face of the plurality of raw material blanks 22.

RESULTS:
For a batch of 22 raw material blanks, straddle fir tree root machining operations are run on the vertical turning lathe (VTL) machine. The total cycle time took for machining 22 raw material blanks is 24 hours which includes 22 hours of cutting time and 2 hours of loading/unloading time. So, for machining each raw material blank, the cycle time is 1 hour 6 minutes approximately.

In comparison to conventional method, the straddle fir tree root machining operation in accordance with the present invention saved the cycle time of 2 hour 27 minutes for each raw material blank.

TECHNICAL ADVANCEMENTS:
An apparatus to facilitate in root machining operation on a bar stock has several technical advantages including but not limited to the realization of :
• a simple and fool proof apparatus for straddle fir tree root machining ;
• an apparatus which can facilitate to perform straddle fir tree root machining operation on a simple CNC machine ;
• an apparatus which can facilitate to perform straddle fir tree root machining operation in less cycle time ;
• an apparatus which can improve productivity of straddle fir tree root machining operation ;
• an apparatus which can perform straddle fir tree root machining operation even with semi skilled labour also ;
• an apparatus which can help to save power consumed by a CNC machine while performing straddle fir tree root machining operation ; and
• an apparatus which can facilitate to perform straddle fir tree root machining operation at cheap cost.

Although the invention has been described herein above with reference to the embodiments of the invention, the invention is not limited to the embodiments described herein above. It is to be understood that modifications and variations of the embodiments can be made without departing from the spirit and scope of the invention.