Claims:We claim:
1) A means (100) to prevent chattering during machining on a plurality of rotor discs (12) of a turbo machine comprising a plurality of bolts (112) and a plurality of nuts (114) adapted to pass over said plurality of bolts (112), said means (100) adapted to configure in between said plurality of rotor discs (12)
in such a way that a head (H) of said plurality of bolts (112) mates against one face of said plurality of rotor discs (12) and said plurality of nuts (114) mates against other face of said plurality of rotor discs (12) next in line by giving load through turning of said plurality of nuts (114), said giving load on said plurality of rotor discs (12) next in line results in the creation of equal and opposite load on said plurality of rotor discs (12) preceding in line thereby arresting degrees of freedom of each of said plurality of rotor discs (12) during machining.

2) A means (100) to prevent chattering during machining on a plurality of rotor discs (12) of a turbo machine as claimed in claim 1, wherein uniform loading is given at either one or multiple locations across circumference of each of said plurality of rotor discs (12).

3) A means (100) to prevent chattering during machining on a plurality of rotor discs (12) of a turbo machine as claimed in claim 1, wherein size of said plurality of bolts (112) is decided depending on the distance between said plurality of rotor discs (12).

4) A means (100) to prevent chattering during machining on a plurality of rotor discs (12) of a turbo machine as claimed in claim 1, wherein deviation of each of said plurality of rotor discs (12) is measured with the help of dial gauge and accordingly adjustments are done to the loading of each of said plurality of rotor discs (12) through turning of said plurality of nuts (114).

5) A method of using a means (100) to prevent chattering during machining on a plurality of rotor discs (12) of a turbo machine, said method comprising the steps of :
a) passing a plurality of nuts (114) of said means (100) over a plurality of bolts (112) of said means (100);
b) arranging said means (100) in between said plurality of rotor discs (12) in such a way that a head (H) of said plurality of bolts (112) adapted to mate against one face of said plurality of rotor discs (12) and said plurality of nuts (114) adapted to mate against other face of said plurality of rotor discs (12) next in line by giving load through turning of said plurality of nuts (114); and
c) giving load on said plurality of rotor discs (12) next in line results in the creation of equal and opposite load on said plurality of rotor discs (12) preceding in line thereby arresting degrees of freedom of each of said plurality of rotor discs (12) during machining.
, Description:FIELD OF THE INVENTION:
The present invention relates to the field of means and methods to prevent chattering during machining. Particularly, the present invention relates to a means and a method of preventing chattering during grooving operation on a plurality of rotor discs of a turbo machine.

BACKGROUND OF THE INVENTION:
Figure 1(a) illustrates a perspective view of a plurality of rotor discs of a turbo machine after machining operation.

Figure 1(b) illustrates a cross sectional view of a plurality of rotor discs of a turbo machine of figure 1(a).

Figure 1(c) illustrates an enlarged view of portion A of figure 1(b).

A plurality of rotor discs 12 having an outer diameter of 962mm and width of 24mm are provided with a plurality of grooves G to accommodate a plurality of blades. As the root of the plurality of blades is of inverted T shape, a complementary plurality of grooves G
of inverted T shape as shown in the figure 1(c) are formed on the plurality of rotor discs 12. As the outer diameter of the plurality of rotor discs 12 is high and the width of the plurality of rotor discs 12 is low, it is very difficult to perform grooving operation on the
plurality of rotor discs 12.

Figure 2 illustrates an enlarged view of surface of a rotor disc of figure 1(a) produced because of chattering during machining operation.

Generally, the act of machining operation involves motion of the workpiece against motion of the tool. This engagement of the workpiece against the tool results in the production of chattering vibration. If chattering vibration is within permissible limits, the surface finish of the work piece is smooth and uniform; otherwise, the surface finish of the work piece is rough and non uniform and is generally indicated by reference letter RN as shown in the figure 2.

Further, excess chattering vibration also results in frequent breakage of tool. In order to prevent the breakage of the tool, generally low speed and feed is given to the tool which ultimately results in high cycle time

So, In order to keep the chattering vibration within permissible limits, it is common practice to bolster either workpiece or tool or both workpiece and tool.

Several techniques have been disclosed in the prior art to prevent chattering during machining.

US Patent no. 8360697 filed on June 15, 2010 titled “Method for reducing vibrations, which occur during a machining process, of a machine element and/or of a workpiece” discloses a method of reducing chattering vibrations during machining through attaching a plurality of masses of different mass automatically to workpiece holder or spindle of a tool depending on the cutting parameters like speed and feed. The plurality of masses is arranged on an exchange device which can rotate around itself along horizontal axis. The plurality of masses are attached the workpiece holder and the spindle of a tool by their respective movement along horizontal axis and vertical axis respectively towards the exchange device. This method is apt only to specific type of workpieces and specific type of lathes, CNC machines and robots. The workpiece in question is a rotor having spaced rotor discs and CNC machine is specifically designed for machining of the rotor.

US Patent no. 4266454 filed on September 21, 1978 titled “Method and Apparatus for dampening vibrations during turning of a rotor” discloses a method of inhibiting vibrations while machining both faces of a brake disc to produce a thin brake disc as per design specifications. The chattering vibrations are arrested by inclined positioning of dampener rods on provisions provided on both sides of the brake disc and the dampener rods are adapted to mate on both faces of the rotor disc by force of gravity. The tips of the dampener rods which mates with the faces of the brake disc are eroded during machining.
This method is specifically designed for dampening vibrations in machining of brake discs and does not find its application in grooving operation on rotor discs.
US Patent Application Publication no. 20160067784 published on March 10, 2016 titled
“Anti Vibration Plug for mechanizing tubes & method for placing said plug inside a tube” discloses an anti vibration plug comprising a plurality of arms which can extend outwards and adapt to the inner circumference of the tubes depending on the inner diameter of the tubes thereby providing structural rigidity to the tubes while machining and also acts as a stopper to prevent the entry of coolant, chips, debris etc in to the tubes. This method finds its application specially in machining of tubes.

Therefore, there is felt a need for development of a means and a method to prevent chattering during machining on a plurality of rotor discs of a turbo machine to overcome the drawbacks of the prior art and thereby achieving a good quality surface finish on the plurality of rotor discs.

OBJECTS OF THE INVENTION:
An object of the present invention is to provide a simple and fool proof mechanism to prevent chattering during machining on a plurality of rotor discs of a turbo machine.

Another object of the present invention is to prevent breakage of tool and thereby increase the life of the tool.

One more object of the present invention is to perform machining on a plurality of rotor discs of a turbo machine in less cycle time.

Still another object of the present invention is to achieve a good quality surface finish on a plurality of rotor discs of a turbo machine after machining.

Further another object of the present invention is to increase cutting parameters of the tool like speed and feed.

Yet one more object of the present invention is to bolster a plurality of rotor discs while machining.

SUMMARY OF THE INVENTION:
In accordance with the present invention a means to prevent chattering during machining on a plurality of rotor discs of a turbo machine is provided, the means comprising a plurality of bolts (112) and a plurality of nuts (114) adapted to pass over the plurality of bolts (112), the means (100) adapted to configure in between the plurality of rotor discs (12) in such a way that a head (H) of the plurality of bolts (112) mates against one face of the plurality of rotor discs (12) and the plurality of nuts (114) mates against other face of the plurality of rotor discs (12) next in line by giving load through turning of the plurality of nuts (114), the giving load on the plurality of rotor discs (12) next in line results in the creation of equal and opposite load on the plurality of rotor discs (12) preceding in line thereby arresting degrees of freedom of each of the plurality of rotor discs (12) during machining.

Typically, the size of the plurality of bolts (112) is decided depending on the distance in between the plurality of rotor discs (12).

Typically, the thickness of the plurality of rotor discs (12) at extreme ends is significantly more when compared to the rest of the plurality of rotor discs (12).

Typically, the means (100) is held between the plurality of rotor discs (12) at four equidistant locations to give uniform loading across their circumference.

In accordance with the present invention a method to prevent chattering during machining on a plurality of rotor discs (12) of a turbo machine is provided, the method comprising the steps of:
i) passing a plurality of nuts (114) of the means (100) over a plurality of bolts (112) of the means (100);
ii) arranging the means (100) in between the plurality of rotor discs (12) in such a way that a head (H) of the plurality of bolts (112) adapted to mate against one face of the plurality of rotor discs (12) and the plurality of nuts (114) adapted to mate against other face of the plurality of rotor discs (12) next in line by giving load through turning of the plurality of nuts (114); and
iii) giving load on the plurality of rotor discs (12) next in line results in the creation of equal and opposite load on the plurality of rotor discs (12) preceding in line thereby arresting degrees of freedom of each of the plurality of rotor discs (12) during machining.

BRIEF DESCRIPTION OF THE DRAWINGS:
The invention will now be described with reference to the accompanying drawings in which:
Figure 1(a) illustrates a perspective view of a plurality of rotor discs of a turbo machine after machining operation;

Figure 1(b) illustrates a cross sectional view of a plurality of rotor discs of a turbo machine of figure 1(a);

Figure 1(c) illustrates an enlarged view of portion A of figure 1(b);

Figure 2 illustrates an enlarged view of surface of a rotor disc of figure 1(a) produced because of chattering during machining operation according to the prior art; and

Figure 3 illustrates a front view of a means arranged in between a plurality of rotor discs of a turbo machine 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 front view of a means arranged in between a plurality of rotor discs of a turbo machine.

In accordance with the present invention, there is provided a means 100 to prevent chattering during machining on a plurality of rotor discs 12 of a turbo machine comprising a plurality of bolts 112 and a plurality of nuts 114. The plurality of rotor discs 12 have opposite side faces facing each other in between the spaces defined therein. A head H of the plurality of bolts 112 adapted to mate against one face of the plurality of rotor discs 12 and the plurality of nuts 114 passing over the plurality of bolts 112 adapted
to mate against other face of the plurality of rotor discs 12 next in line.

Typically, the size of the plurality of bolts 112 is decided depending on the distance in between the plurality of rotor discs 12.

Typically, the thickness of the plurality of rotor discs 12 at extreme ends is significantly more when compared to the rest of the plurality of rotor discs 12.

Typically, the means 100 is held between the plurality of rotor discs 12 at four equidistant locations to give uniform loading across their circumference.

The method of arrangement of the means 100 in between the plurality of rotor discs 12 to prevent chattering during machining in accordance with the present invention is as follows:
The means 100 comprising a plurality of bolts 112 and a plurality of nuts 114 wherein the plurality of nuts 114 adapted to pass over the plurality of bolts 112 by means of complementary threads. The means 100 is configured in between the plurality of rotor discs 12 in such a way that the head H of the plurality of bolts 112 adapted to mate against one face of the plurality of rotor discs 12 and the plurality of nuts 114 adapted to mate against other face of the plurality of rotor discs 12 next in line by giving loading through turning of the plurality of nuts 114. The application of loading on the other face of the plurality of rotor discs 12 next in line results in the creation of equal and opposite loading on the face of the preceding plurality of rotor discs 12.

The loading on one face of each of the plurality of rotor discs 12 is balanced by equal and opposite loading on other face of each of the plurality of rotor discs 12 thereby maintaining each of the plurality of rotor discs 12 within tolerance limits from centerline during machining. The deviation of each of the plurality of rotor discs 12 from centerline across the circumference is measured frequently with help of dial gauge and accordingly adjustments are done to the loading of each of the plurality of rotor discs 12 through turning of the plurality of nuts 114.

As degrees of freedom for the plurality of rotor discs 12 is restricted by strengthening on their both faces, we will not experience any chatter during machining on the plurality of rotor discs 12 and thereby achieve a uniform and good quality surface finish.

TECHNICAL ADVANCEMENTS:
A means to prevent chattering during machining on a plurality of rotor discs of a turbo machine has several technical advantages including but not limited to the realization of :
• a simple and fool proof mechanism to prevent chattering during machining on a plurality of rotor discs of a turbo machine ;
• a means which can facilitate to prevent breakage of tool and thereby increase the life of the tool ;
• a means which can facilitate to perform machining on a plurality of rotor discs of a turbo machine in less cycle time ;
• a means which can help to achieve a good quality surface finish on a plurality of rotor discs of a turbo machine after machining ;
• a means that can help to increase cutting parameters of the tool like speed and feed ; and
• a means which can bolster a plurality of rotor discs while machining.

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.