FIELD OF INVENTION

The present invention relates to an arrangement for root and shroud milling of turbogenerator moving blades.
BACKGROUND OF THE INVENTION
Unlike turbine blades which generally have a root part at the bottom, a shroud part and the top and a aerofoil or profile at the middle, a turbo generator moving blades have root and profile portion only. In a general practice, a turbogenerator finished blades is machined from rectangular cross sectional blanks in multi-axis CNC machines. The blanks are clamped in special clamping adapters while carrying out the milling operation. Therefore, technological allowances, or also known as clamping allowances, are kept in the blanks while blanking operation is carried out.
After completion of machining of the complete blade in multi-axis machines, these blades are loaded on milling machines, where the clamping allowances are milled off and blade dimensions are maintained.
However, since turbogenerator blades do not contain shroud, they cannot be treated similar to a turbine blade and dedicated arrangement is required to mount these blades rigidly on a milling machine where the technological allowances are being milled off.

Also, since the shape and size of turbogenerator moving blades would vary with turbogenerator rating, it is of particular requirement that such arrangements use plurality of support pads of varied dimension so that these can be installed in conjunction with the turbogenerator blade dimension in order to ensure that axis of the blades in both horizontal and vertical direction are aligned while clamping as well during machining.
Within the objects of this invention, it is sought to cure the defects existing in the art as mentioned in part above, and to provide an arrangement for root and shroud milling of turbogenerator moving blades having low initial cost and upkeep, great and continuing accuracy inherent in its design and operation, ruggedness and simplicity in its construction and operation, all to the ultimate end of faithfully and consistently reproducing quality in blades.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose an arrangement for root and shroud milling of turbogenerator moving blades, which is capable of improving the machining quality of the turbogenerator blades and thus improving the service life of the generator.

Another object of the invention is to propose an arrangement for root and shroud milling of turbogenerator moving blades, which is simple, economical, foolproof and inherently free from tendency to err or fall of adjustment.
A still another object of the invention is to propose an arrangement for root and shroud milling of turbogenerator moving blades, which completely eliminates the need of an operator to interchange clamping fixtures to accommodate variation in blade dimension.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The foregoing and other features of the invention, comprising the improved arrangement of root and shroud milling of turbogenerator blades together with the construction and relative arrangement of the several parts, will be apparent from the following more particular description of the invention, as illustrated in the accompanying drawings, in which like reference characters refer to the same parts throughout the different figures and subsequently incorporated in the subjoined claims. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention and in which:
Figure 1 shows a line representation of turbogenerator moving blade and
Dimension-A depicting tang height in accordance with the present invention;

Figure 2 shows a line representation of complete arrangement as proposed in
present application along with clamped blade in accordance with the present invention;
Figure 3 shows a line representation of profile resting block in accordance with the
present invention;
Figure 4 shows a line representation of showing the assembly of the profile resting
block along with the blade in accordance with the present invention;
Figure 5A, 5B, 5C shows a line representation of plate spring and bolt in accordance with the present invention;
Figure 6A, 6B shows a line representation of the top thrust pad and stepped block in accordance with the present invention;
Figure 7A, 7B shows a line representation of the threaded means used in the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Before describing in detail, arrangement for root and shroud milling of turbogenerator moving blades, it should be observed that the present invention resides primarily in a novel and non-obvious combination of hardware elements and method steps. Accordingly, these elements and steps have been represented by conventional elements and steps in the drawings, showing only those specific details that are pertinent to the present invention so as not to obscure the disclosure with details that

will be readily apparent to those skilled in the art having the benefit of the description herein.
The present invention is directed to solve the above-described problems of the prior art and to provide an arrangement for root and shroud milling of turbogenerator moving blades in accordance with the present invention and to enable to rigidly clamp and thereby manufacture the blades easily and in short time.
The invention provides a novel arrangement for root and shroud milling operation of turbogenerator moving blades suitable of being operable on milling machines which will improve the machining quality of the turbogenerator blades and the reliability and service life of the generator thereof. More especially this invention is concerned with obtaining great accuracy in root and shroud milling of a turbogenerator blade through an arrangement that is simple, economical, foolproof and inherently free from tendency to err or fall out of adjustment.
The invention provides an arrangement for root and shroud milling of a turbogenerator blade which does not require a plurality of clamping fixture to accommodate variation in blade dimensions but alternatively providing a solution through support pads which completely eliminates the need of an operator to interchange clamping fixtures, thus avoiding the work and loss of time involved in transferring the job and the running time required before the blade is realigned for useful operation.

The arrangement (B) consists of a profile resting block (16) or a base block having plurality of counter holes (9) for holding it with machine fixture and a matching blade airfoil or profile counterpart portion (8) at its center on which the delicate profile part (40) of the blade rests so that root (20) and shroud part (20) of the blade (5) are free during machining operation. This profile counterpart portion (8) of the Profile resting block (16) is such that it matches the pressure side/internal profile surface curvature (40) of the blade (5) to be machined. The shape of the profile (8) on the Profile resting block (16) is done by impression of cerroband casting material.
Profile resting block (16) utilizes plurality of hole (9) for getting clamped to the standard machine fixture (not shown) base with help of threaded means such as a T-bolt arrangement depending on the machining arrangement.
The root (20) of the blade is fixed in the slot of the plate (4) which is fixed to the profile resting block (16) with the help of plurality of threaded means (6, 12, 10) and spring means (7). The referencing of the root is done by butting the root on the surface of the profile resting block (16).
The movement of the blade in vertical direction during machining is restrictedly eliminated by the top thrust pad (3) and the stepped block (1) wherein the top thrust pad (3) is fixed with stepped block (1) with the help of threaded means (2, 11, 13, 15).

The top thrust pad (3) is connected to hydraulic cylinder (not shown) via the hole (14) of stepped block and rests on the suction side of the blade and thus supports the blade during machining.
For strengthening purposes, stepped block (1), profile resting block (16) and top thrust pad (3) are made of hardened and ground material such as but not limited to EN-24.
Further, it will be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its scope.
Furthermore, all examples recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

WE CLAIM
1. An arrangement (B) for root and shroud milling of turbogenerator moving blades
consisting of;
a profile resting block (16) clamped to a standard machine fixture and having a blade profile counterpart portion (8) at its center;
a plate (4) fixed to the profile resting block (16) by a plurality of threaded means (6, 12, 10) and spring means (7);
a top thrust pad (3) connected to a hydraulic cylinder and fixed to a stepped block (1) by threaded means (2, 11, 13, 15) disposed for restricting the movement of the blade in vertical direction during machining;
wherein,
the profile counterpart portion (8) of the profile resting block (16) matches with the pressure side internal profile surface curvature (40) of the blade (5) to be machined accommodating the delicate profile part (40) of the blade (5) on it so that root (20) and shroud part of the blade (5) are free during machining operation, when the root (20) is butted on the surface of the profile resting block (16) for referencing the root, wherein root and shroud machining is performed once the blade (5) is rigidly held in the arrangement.

2. The arrangement as claimed in claim 1, wherein the shape of the profile (8) on the profile resting block (16) is made by impression of cerroband casting material.
3. The arrangement as claimed in claim 1, wherein the stepped block (1), profile resting block (16) and top-thrust pad (3) are made of hardened and ground material not limited to EN 24 only for adding rigidly and strength to the arrangement.
4. A method for root and shroud milling of turbogenerator moving blades by an arrangement claimed in claim 1, comprising;
fixing profile resting block (16) on blade machining fixture through a plurality of counter holes by a threaded means;
fixing the plate (4) to the profile resting block (16) by a plurality of threaded means (6, 12, 10) and spring means (7);
connecting top thrust pad to a hydraulic cylinder through a hole (14) of stepped block (1) to support the blade (5) during machining;
wherein,
the blade (5) is rested over profile counterpart portion (8) of the profile resting block (16) such that the said profile counterpart portion matches the pressure side internal profile surface curvature (40) of the blade (5) when root (20) and shroud part

of the blade (5) are free during machining operation when the root (20) is referenced by butting the root (20) on the surface of the profile resting block (16) wherein the root and shroud machining of the turbogenerator blades are machined when the blade (5) is rigidly held in the arrangement.