The guide Ring is positioned on a top plate (9) of the frame (1) such that it is uniformly clamped at three positions equally distributed at an angle of 120 degrees by three external clamps (5) and three internal Clamps (6) on outer diameter and internal diameter of the Guide Ring respectively.
The external clamps (5) and the internal Clamps (6) are fixed with threaded Spindles (4) passing through the external Supports (2) and the internal Supports (3) and locked by the locking Nut (8).
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1(a) shows a clamping device for machining of guide ring of High Pressure Control Valve of Steam Turbine governing system according to the present invention.
Figure 1(b) shows View-Y of figure 1 (a).
Figure 2 shows Frame of the clamping device shown in figure 1 (a) and figure 1 (b).
Figure 3 (a) and Figure 3(b) - shows the External Support and Internal Support of the clamping device.
Figure 4 (a) shows a threaded Spindle having hexagonal head with threaded portion and socket according to present invention.
Figure 4(b) & Fig.4(c) - shows External Clamp and Internal Clamp with holes having radial surfaces respectively according to present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION :
Frame (1), three External Supports (2), three Internal Supports (3), Six Threaded Spindles (4), three External Clamps (5), three Internal Clamps (6), a plurality of Clamping Screws (7), and a plurality of Locking Nuts (8).
The frame (1) is a fabricated structure comprising a Top plate (9), a Bottom Plate (12) with slots H4 and H5, a plurality of "I" beams (10), and a pipe (11). The Top plate (9) has a plurality of threaded holes H1, H2 and H3.
The supports (2,3) comprises threaded holes H9, H14 and clamping holes H6, H7 and H8 according to an embodiment of the present invention.
In details figure 1(a) and figure 1 (b) shows the clamping device which comprises a Frame (1). At least three External Supports (2) are fastened with a Top plate (9) of the Frame (1) horizontally with holes H1 & H6 and vertically with holes H2 & H7 by a plurality of Clamping Screws (7). Three Internal Supports (3) are fastened with the Top plate (9) of the Frame (1) with holes H3 and H8 by a plurality of Clamping Screws (7).
Three threaded Spindles (4) are guided inside the External Supports (2) with threaded hole H14 configured in the External Supports (2), and a threaded portion H10 of the Six threaded Spindles (4) respectively. Three External Clamps (5) are fitted on Threaded Spindles (4) with holes H12 and socket H11. The External Clamps (5) having radial surface R1, which clamps the Outer diameter of the Guide Ring (13) at three positions equispaced at an angle of 120 degrees. After clamping, the Threaded Spindles (4) are locked with Locking Nuts (8).

Similarly three Threaded Spindles (4) are guided inside three Internal Supports (3) with threaded hole H9 configured in the Internal Supports (2) and a threaded portion H10 of the Threaded Spindles (4) respectively. Three Internal Clamps (6) are fitted on the Threaded Spindles (4) with holes H13 and socket H11.
The Internal Clamps (6) having radial surface R2 which clamps the Internal diameter of the Guide Ring (13) at three positions equispaced at an angle of 120 degrees. After clamping, the Threaded Spindles (4) are locked with the Locking Nuts (8). The Threaded Spindles (4) are rotated with the help of L type hexagonal socket wheel spanner so that proper tightening of the External Clamps (5) and the Internal Clamps (6) is achieved.
Figure 2 shows the Frame (1) of the clamping device which is a fabricated structure comprising a Top Plate (9) four 1 beams (10), a Pipe (11), and a Bottom Plate (12). The Bottom plate (12) has slots H4 and H5 to clamp the Frame (1) with the base plate of CNC vertical milling centre. The top plate (9) has a plurality of threaded holes H1, H2 and H3 at different locations to clamp the External Supports (2) and the Internal Supports (3).
Figure 3(a) and Figure 3(b) - shows the External Support (2) and the Internal Support (3) of the clamping device with threaded holes H9, H14 and clamping holes H6, H7 and H8 according to an embodiment of the present invention.
Figure 4 (a) shows the Threaded Spindle (4) having hexagonal head with a threaded portion H10 and a socket Hll according to the present invention. The threaded portion H10 has an allowance to accommodate the variation in diameters of the Guide Ring (13).

FIELD OF THE INVENTION
The present invention generally relates to rigid and uniform clamping of guide ring of high pressure control valve of steam turbines while machining on CNC vertical milling centre. More particularly, the present invention relates to a clamping device for machining of guide ring at higher feeds and cutting speeds with less vibrations on CNC vertical miller.
BACKGROUND OF THE INVENTION
Guide Ring is a fragile and precise component of High Pressure Control Valve of Steam turbine governing system. At present, machining of the guide ring is done at very low cutting speeds and feeds due to high cutting forces and heavy vibrations generated. Also there is no proper arrangement for rigid clamping of guide ring on CNC vertical milling centre. Hence the job setting time and cycle time of machining becomes very high which results in "delay of assembly" and leading to higher cost.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose a clamping device for machining of guide ring of HIGH Pressure Control Valve of Steam Turbine governing system, which eliminates the disadvantages of the prior art.
Another object of the present invention is to propose a clamping device for machining of guide ring of HIGH Pressure Control Valve of Steam Turbine governing system, which reduces the vibrations.

A still another object of the present invention is to propose a clamping device for machining of guide ring of HIGH Pressure Control Valve of Steam Turbine governing system, which allows machining of the guide ring at higher cutting speeds and feed.
Yet another object of the present invention is to propose a clamping device for machining of guide ring of HIGH Pressure Control Valve of Steam Turbine governing system, which reduces the job setting time and cycle time of machining of guide ring, hence improve the productivity.
A further object of the present invention is to propose a clamping device for machining of guide ring of HIGH Pressure Control Valve of Steam Turbine governing system, which improves the quality of machining, including better accuracy.
SUMMARY OF THE INVENTION
Accordingly, there is provided a clamping device for machining of guide ring of High Pressure Control Valve of Steam Turbine governing system comprising :
a) a frame (1);
b) an external Support (2);
c) an internal Support (3);
d) a threaded Spindle (4);
e) an external Clamp (5);
f) a internal Clamp (6);
g) a clamping Screw (7); and
h) a locking Nut (8).

Figure 4(b) & Fig.4(c) - shows the External Clamp (5) and the Internal Clamp (6) with holes H12 and H13, having radial surfaces R1 and R2 respectively according to present invention. The radial surfaces R1 and R2 grip the outer diameter and internal diameters of the Guide Ring (13) respectively.

WE CLAIM :
1. A clamping device for machining of guide ring of High Pressure Control Valve of Steam Turbine governing system, comprising :
- a frame having a top plate with a plurality of holes; at least four beams rigidly joined to each other; a hollow pipe attached substantially centrally to the frame; a bottom plate having at least two holes for fixing the frame with the base of the CNC vertical milling machine;
- a plurality of external supports releasably attached vertically and horizontally to the top plate via holes and clamp screws, the external supports each has a plurality of holes;
- a plurality of internal supports having a plurality of holes are screwably fastener to the top cover;
- a plurality of external clamps each having a first radial surface for clamping the outer diameter of the guide rings, the external clamps comprising holes;
- a plurality of internal clamps each having a second radial surface for clamping the internal diameter of the guide rings at three positions equispaced at an angle of 120°, the internal clamps comprising a plurality of holes;

- a plurality of spindles having each a threaded portion and a plurality of holes, the external clamps and the internal clamps are connected to the spindles via holes and sockets; and
- the threaded portion of the spindle provided with an allowance to accommodate different sizes of guide rings and enabled to be rigidly screwed upon clamping the guide rings.

2. The device as claimed in claim 1, wherein the Guide ring is clamped rigidly and uniformly at three positions on both outer diameter and internal diameter with External Clamps and Internal Clamps respectively is having radial surfaces R1 and R2.
3. The device as claimed in any of the preceding claims wherein the External Clamps and Internal Clamps are made of hardened alloy steels.
4. The device as claimed in any of the preceding claims, wherein the Frame is so configured that the Guide Ring is placed at a height according to the position of the CNC Vertical Milling centre.
5. The device as claimed in any of the preceding claims, wherein the Bottom Plate of the Frame is clamped with the base plate of CNC Vertical Milling centre through holes.

6. A clamping device for machining of guide ring of High Pressure Control Valve of Steam Turbine governing system as substantially described and illustrated herein with reference to the accompanying drawings.

The invention relates to a clamping device for machining of guide ring of High Pressure Control Valve of Steam Turbine governing system, comprising : a frame having a top plate with a plurality of holes; at least four beams rigidly joined to each other; a hollow pipe attached substantially centrally to the frame; a bottom plate having at least two holes for fixing the frame with the base of the CNC vertical milling machine; a plurality of external supports releasably attached vertically and horizontally to the top plate via holes and clamp screws, the external supports each has a plurality of holes; a plurality of internal supports having a plurality of holes are screwably fastener to the top cover; a plurality of external clamps each having a first radial surface for clamping the outer diameter of the guide rings, the external clamps comprising holes; a plurality of internal clamps each having a second radial surface for clamping the internal diameter of the guide rings at three positions equispaced at an angle of 120°, the internal clamps comprising a plurality of holes; a plurality of spindles having each a threaded portion and a plurality of holes, the external clamps and the internal clamps are connected to the spindles via holes and sockets; and the threaded portion of the spindle provided with an allowance to accommodate different sizes of guide rings and enabled to be rigidly screwed upon clamping the guide rings.