FIELD OF THE INVENTION:
The present invention relates to the field of fixture for holding T-root blades during machining operation. Particularly  the present invention relates to a fixture to reduce the cycle time of machining excess material from T-root of the blades.

BACKGROUND OF THE INVENTION:
Figure 1 illustrates a T-root blank at the onset of blade profile machining.
The T-root Blank at the onset of blade profile machining comprises an extra material E on both the sides to provide a proper butting surface between the T-root Blank and the fixture during profile machining operation.

Figure 2 illustrates a T-root blade mounted on a section of rotor disc. The section of rotor disc is generally indicated by a letter D.

Figure 3 illustrates an enlarged view of figure 2.

It is evident from figure 2 and figure 3 that the slot in the rotor disc D cannot accommodate the extra material E of the T-root blank. So  the extra material from the T-root blank needs to be removed after the blade profile machining operation. The operation of removal of extra material from T-root blades requires a fixture for holding of the T-root blades during machining.

Figure 4 illustrates a pictorial view of conventional fixture.

Figure 5 illustrates an enlarged view of components of figure 4 with T-root blade fitted on the fixture from one angle.

Figure 6 illustrates an enlarged view of components of figure 4 with T-root blade fitted on the fixture from another angle.

Figure 7 illustrates an enlarged view of components of figure 4 without T-root blade.
Referring to figure 4  figure 5  figure 6 and figure 7  there is provided a conventional fixture comprising a base plate 12  a side clamp 14  a side clamp holding device 16  a top clamp 18  a top clamp mounting block 20  a flexible resting pad 22  a locking pin 24  a hexagonal driving nut 26  a bolt 28  a washer 30  two hexagonal nuts 32  cap screws 34 and a handle 36.

A side clamp holding device 16 is of fork shape with two prongs 16(a) and 16(b) having a space defined in between therein. Two threaded holes in line to each other are drilled on the prongs 16(a) and 16(b) of the side clamp holding device 16. The side clamp holding device 16 is mounted on the base plate 12 and bolted by means of cap screws 34. A side clamp 14 is of hexagonal bolt shape provided with an integral semicircular provision 15 at the head of the bolt for mounting a flexible resting pad 22. The flexible resting pad 22 is locked on to the semicircular provision 15 by means of the locking pin 24. A hexagonal driving nut 26 is inserted in to the space between the two prongs of the side clamp holding device 16 and made in tandem to the threaded holes on the prongs 16(a) and 16(b). The side clamp 14 is made to pass in to the threaded holes of the prongs through the hexagonal driving nut 26. Now  the hexagonal driving nut 26 is in a position to move the side clamp 14 forward and backward.

A top clamp mounting block 20 is mounted on the base plate 12 and bolted by means of cap screws 34. A bolt 28 is made to pass through the base plate 12 and top clamp mounting block 20. A top clamp 18 with a projection at the bottom and a handle 36 attached at the top by means of a bolt-nut mechanism is inserted in to the bolt 28 with the help of a hole provided at the center of the top clamp 18 and bolted tightly by means of hexagonal nuts 32 and washer 30. The handle 36 facilitates the operator in the movement of the top clamp 18. An integral stopper 19 is provided on the top clamp mounting block 20 to restrict the movement of the top clamp 18 between 0 to 90 degrees.

The method of removal of excess material from T-root of the blades by using conventional fixture is as follows:
The side clamp 14 is moved backward by rotating the hexagonal driving nut 26 in counter clockwise direction to accommodate the T-root blade. The T-root blade is placed in the space between top clamp mounting block 20 and the side clamp 14 as shown in the figure 4 and figure 5 and now  the side clamp 14 is moved forward by rotating the hexagonal driving nut 26 in clockwise direction such that the T-root blade is pressed tightly against the top clamp mounting block 20 by means of the flexible resting pad 22 of the side clamp 14. The flexible resting pad 22 adapts to the shape of the root surface of the T-root blade (Generally  the T-root blade will have a plain surface on one side and tapered surface on other side at root portion). The extra material on either side of the T-root blade is removed by passing the tool horizontally over the top surface at the root portion in one pass and by passing the tool horizontally over the bottom surface at the root portion in other pass.

The conventional fixture disclosed herein is complex  occupies a lot of space  requires a flexible articulated arm to maneuver the tool at the bottom surface of T-root blade while removing extra material (i.e.  difficulty in machining) and has less productivity.

Therefore  there is a felt need for development of a fixture that can remove excess material from T-root of the blades in minimum cycle time.

OBJECTS OF THE INVENTION:
An object of the present invention is to provide a simple fixture for holding T-root blades to facilitate in excess material removal operation.

Another object of the present invention is to provide a compact fixture.

One more object of the present invention is to provide a fixture wherein the operation of excess material removal can be performed on more number of blades and thereby increasing the productivity of the operation.

Still another object of the present invention is to provide a fixture that can facilitate the tool for easy machining of the excess material on either side of the T-root blade.

Further another object of the present invention is to provide a fixture which helps in machining the excess material on either side of the T-root blade in minimum cycle time.

BRIEF DESCRIPTION OF THE DRAWINGS:
The invention will now be described with reference to the accompanying drawings in which:

Figure 1 illustrates a T-root blank at the onset of blade profile machining;

Figure 2 illustrates a T-root blade mounted on a section of rotor disc;

Figure 3 illustrates an enlarged view of figure 2;

Figure 4 illustrates a pictorial view of conventional fixture;

Figure 5 illustrates an enlarged view of components of figure 4 with T-root blade fitted on the fixture from one angle;

Figure 6 illustrates an enlarged view of components of figure 4 with T-root blade fitted on the fixture from another angle;

Figure 7 illustrates an enlarged view of components of figure 4 without T-root blade;

Figure 8 illustrates a pictorial view of fixture in accordance with the present invention;

Figure 9 illustrates an enlarged view of the fixture of figure 8;

Figure 10(a) illustrates a front view of blade mounting block of fixture of figure 8;

Figure 10(b) illustrates a top view of blade mounting block of figure 10(a);

Figure 10(c) illustrates a side view of blade mounting block of figure 10(a);

Figure 11 illustrates a pictorial view of clamp of fixture of figure 8;

Figure 12(a) illustrates a front view of clamp of fixture of figure 11;

Figure 12(b) illustrates a top view of clamp of fixture of figure 12(a); and

Figure 12(c) illustrates a side view of clamp of fixture of figure 12(a).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
Figure 8 illustrates a pictorial view of fixture in accordance with the present invention.

Figure 9 illustrates an enlarged view of the fixture of figure 8.

Referring to figures 8 and 9  there is provided a fixture to facilitate in removal of excess material from T-root of the blades in minimum cycle time comprising a blade mounting block 12  a plurality of clamps 14  a plurality of dowel bolts 16  a plurality of nuts 18 and plurality of washers 20.

Figure 10(a) illustrates a front view of blade mounting block of fixture of figure 8.

Figure 10(b) illustrates a top view of blade mounting block of figure 10(a).

Figure 10(c) illustrates a side view of blade mounting block of figure 10(a).

Figure 11 illustrates a pictorial view of clamp of fixture of figure 8.

Figure 12(a) illustrates a front view of clamp of fixture of figure 11.

Figure 12(b) illustrates a top view of clamp of fixture of figure 12(a).

Figure 12(c) illustrates a side view of clamp of fixture of figure 12(a).

A blade mounting block 12 is of 280mm length  80mm width and 104 mm height and is indicated by reference numerals X1  Y1 and Z1 respectively. Rectangular slots S1 of 14mm width separated by a solid S2 of 10mm in between them are drilled on either side of the blade mounting block 12 by providing a solid S3 of 18mm between a pair of rectangular slots and are indicated by reference numerals X2  X3 and X4 respectively. Two half way threaded holes H1 of 10mm diameter and 20mm depth with a distance of 40mm between them are drilled on either side of the blade mounting block 12 at each of the solid S2 and is indicated by reference numerals D1  D2 and Y2. Two through threaded holes H2 are drilled from top to bottom of the blade mounting block 12 to facilitate in locking of the fixture to the base plate of CNC machine.

A clamp 14 is in the form of a T-shape with an integral projection P extending at its top having a space defined in between therein. Two holes H3 of 10mm diameter in line to the two half way threaded holes H1 are drilled on the clamp 14 and is indicated by reference numeral D3. The length at the top  length at the bottom  width and height of the clamp 14 is of 46mm  26mm  24mm and 95mm respectively and is indicated by reference numerals X5  X6  Y3 and Z2 respectively. The thickness of the clamp 14 is of 16mm and is indicated by reference numeral T1. The thickness of the integral projection is of 7.5mm and extends to a length of 8mm and is indicated by reference numerals T2 and Y4.

The method of working of the fixture in accordance with the present invention is as follows: Firstly  a plurality of dowel bolts 16 are made to pass through the half way threaded holes H1 of the blade mounting block 12. Secondly  one side of the T-root blades is made to sit in the slots S1 of the blade mounting block 12. Finally  plurality of the clamps 14 are inserted in to the plurality of dowel bolts 16 such that the other side of the T-root blades mounts on the integral projection P of the clamps 14 and locked in position by means of plurality of nuts 18 and washers 20. Extra material on one side of the T-root blades is removed in one pass and extra material on other side of the T-root blades is removed in other pass.

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.

We claim:
1) A fixture to facilitate in removal of excess material from T-root of the blades in minimum cycle time  said fixture comprising:
a) a blade mounting block having a plurality of rectangular slots on either side with a first solid provided between each of the two rectangular slots and a second solid provided between a pair of rectangular slots  said first solids of said blade mounting block provided with two half way threaded holes  said T-root blades placed in an invert manner in said rectangular slots of the blade mounting block such that half of the T-root of said blades rests above said blade mounting block;
b) a plurality of dowel bolts inserted in to said threaded holes of the blade mounting block;
c) a plurality of clamps of T-shape with an integral projection at top end having threaded holes complementary to two half way threaded holes of said blade mounting block  said plurality of clamps inserted in to said plurality of dowel bolts such that the other remaining half of the T-root of said blades rests above said projection of said clamps; and
d) a plurality of nuts and a plurality of washers provided to facilitate in holding said plurality of clamps in position and thereby arresting the movement of said T-root blades during machining operation.

2) A fixture to facilitate in removal of excess material from T-root of the blades in minimum cycle time as claimed in claim 1  wherein two through holes are provided from top to bottom of said blade mounting block to facilitate in locking of said fixture to base plate of CNC machine.

3) A fixture to facilitate in removal of excess material from T-root of the blades in minimum cycle time as claimed in claim 1  wherein said mounting block is of 280mm length  80mm width and 104mm height.

4) A fixture to facilitate in removal of excess material from T-root of the blades in minimum cycle time as claimed in claim 1  wherein said rectangular slots are of 14mm width.

5) A fixture to facilitate in removal of excess material from T-root of the blades in minimum cycle time as claimed in claim 1  wherein width of said first solid is of 10mm.

6) A fixture to facilitate in removal of excess material from T-root of the blades in minimum cycle time as claimed in claim 1  wherein the width of said second solid is of 18mm.

7) A fixture to facilitate in removal of excess material from T-root of the blades in minimum cycle time as claimed in claim 1  wherein the diameter of said half way threaded holes is of 10mm.

8) A fixture to facilitate in removal of excess material from T-root of the blades in minimum cycle time as claimed in claim 1  wherein the depth of said half way threaded holes is of 20mm.

9) A fixture to facilitate in removal of excess material from T-root of the blades in minimum cycle time as disclosed herein the description and accompanying drawings.