FIELD OF INVENTION
The present invention relates to a device and method for flaring rivet head in bladed discs of a steam turbine rotor. More particularly, the invention relates to the maintenance of accuracy, while making head in the rivets of Bladed disc when disc is finally overturned.
BACKGROUND OF THE INVENTION
in a power general plant there are two main components one is turbine and other one is generator. Turbines are of different type depending upon the medium being used in them like steam turbine, gas turbine, hydro turbine etc
in our case device has been designed for steam turbine. The steam turbine consist of three modules i.e. high pressure (HP) turbine module, intermediate pressure (IP) turbine module and low pressure (LP) turbine module. Each turbine module consists of
three parts:
1. Outer casing
2. Inner casing
3. Rotor
In rotors of IP turbine and LP turbine, bladed discs are shrink fitted. The blades are
fitted in rotor discs which are kept intact firmly by rivets.

Roots of Wades are fitted in the flnger shaped grooves in the periphery of discs. Holes are drilled/reamed in these finger shaped grooves with fitted blades. Tightening and rigidity of fitted biades are ensured by inserting rivets in the holes of disc and biades. Ends of holes are countersinked in which flared head of rivets rests.
Rivets head is formed in two steps. Step 1- when thrust side is on top position, and Step 2 is when side opposite to thrust side is on top after disc overturning.
In step-1, there is no problem to make the rivet head. After overturning rivets head made already in step 1 comes downwards thus while hammering from top this rivet may come out from hole in the down side. To avoid this incident this device is made and used.
Rivet rest on the device and then during hammering proper head is formed without any problem. This gives excellent quality of flared head made and proper fitting of head in the countersink portion.
OBJECTS OF THE INVENTION
Therefore, it is an object of the Invention to propose a device and method for flaring rivet head in bladed discs of a steam turbine rotor which is capable of eliminating the chance of rivet failing from the hole after overturning, from the bottom side while hammering from the top.

Another object of the invention is to propose a device and method for flaring rivet head in bladed discs of a steam turbine rotor which is able to reduce cycle time of assembly and to produce accurate head of rivets.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
fig. 1: Shows the device according to the invention.
Fig. 2 ; Shows the different items of the device according to the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Tne device (D), as shown in fig.1 comprising of a bottom support (1) with jacking facility which not only provides Am support to the device (D) but also incorporates Jacking facility giving extra edge to adjust the height of device and hence the device can be utilized for different heighs. A screw housing cylinder (2) is disposed for providing housing for screw Jack in which a screw (3) can smoothly move up and down for giving firm support to rivet heads at the bottom side after overturning during hammering on the top side of rivet. Tne rivet which is being hammered on the top has a countersink. A rivet support (5) with spherical head fixed at the top of the device (D) provides firm support from bottom side of rivet after overturning and its round head fits inside the countersink portion of rivet preventing slipping of device from its position and also prevents damage of

rivert head. screw type jack (3) has good quality of thread which can withstand heavy
blow of hammer given on the tor side of the rivert during jacking of rivert A threaded nut
(4) with handle (6) welded to it is disposed to facilirtate jacking thr thread nut down to provide firm support to the rivet through a nut (7) fixed to the housing (2). The nut (7) has similar thread as that of screw/thread (3)to facilitate the movement of rivet support (5), the hammer blow given on the top of the rivert flares the head while because of the support at the bottom during hammering the rivet is prevented to fall down by
the support of the device (D).
The method for flaring rivet head in bladed discs of a rotor in steam turbine are as
follows:
Bladed rotor discs having reamed holes for riverts is placed on a cast iron support-
are inserted into reamed hoies. The rivet head is then flared. This flared rivet head
is then overturned when this already made flared rivet heads are at bottom side. A fresh
rivet is now on the top for hammering to mate it flared up.in this situation the device (D)
is used.
i) The assembled device (D) is placed at the bottom of assembled disc under fte
reamed holes.
ii) The height of screw type jack (3) is adjusted by moving through nut (7) by fte handle (6) when height is not being able to get adjusted with bottom support lack (1).

iii) The rivet supPort (5)of the device (D) is then alligned with countersink of rivet and is made to suport the rivet firmly by jacking it up with screw type jack (3). iv) Precaution is taken to confirm that the disc is not lifted while jacking.
v) After ensuring firm support at the bottom of the rivet, the top head of rivet is flared
by hammering.
vi) Process above is repeated for all rivets.

WE CLAIM
1) A device (D) for faring rivet head in bladed discs of a steam turbine rotor
comprising;
a bottom support (1) disposed for jacking facility;
a screw housing cylinder (2) having a hollow inside diameter;
a screw type jack (3);
a nut (7) fixed to the screw housing cylinder (1) having thread matching to the said
screw type jack (3);
a threaded nut (4) along with a handle welded to the said screw type jack (3);
a rivet support (5) with spherical head;
characterized in that,
the screw type jack (3) is disposed to move up and down in the housing cylinder (2), aided by the nut (7) fixed to the said housing for adjusting the height of the device for imparting firm support to the rivet with spherical headed rivet support (5) of the device being aligned and fitted with countersink of rivet preventing slippage of device wherein the hammer blow on the rivet head on the upper side of the disc results excellent fitting of rivets in the reamed hole with proper flared head.
2. A method for flaring rivet head in bladed discs of a steam turbine rotor comprising; inserting rivets in reamed holes of the blade assembled disc;

hammering the rivet head to flare up;
overturning the flared up rivet at the bottom side exposing new rivet at the top for
hammering;
placing the assembled device (D) at the bottom of assembled disc under the
reamed holes;
adjusting the height of screw type Jack (3) by moving the jack (3) through nut (7)
by handle (6);
aligning and fixing the rivet support (5) of the device (D) with countersink of rivet;
support the rivet firmly by jacking the rivet support (5) with screw type jack in the bottom side of the rivet; wherein the rivet head on the top on the upper side of disc is hammered to have the rivets fitted in the reamed hole with heads being flared.