FIELD OF THE INVENTION
The present invention relates to a holding and adjustment device for alignment
of inner-inner and inner-outer casings of low-pressure steam turbines.
BACKGROUND OF THE INVENTION
Large steam turbines are made up of High pressure (HP), intermediate pressure
(IP) and low pressure (LP) stages. The LP stage consists of an inner-inner casing
and an inner-outer casing. During assembly of the LP stage, an adjustment of
the inner-inner casing in respect of the inner-outer casing and the turbing rotor
is necessary. This is a fine adjustment and very critical because of its close (0.8-
1.1 mm) radial clearances in the blading area. To maintain the above clearances
it is necessary to hold the inner-inner casing rigidly with respect to the inner-
outer casing. To achieve this, a centerring bolt and eccentric bush, is provided
which holds the inner-inner casing rigidly with the inner-outercasing.
The prior art process of assembling the Inner-inner casing with the inner-outer
casing involves the steps of :
i) lowering the bottom half of inner-outer casing on an assembly bed,
ii) centering the inner-outer casing bottom half with respect to the bearings,
iii) lowering the bottom half of the inner-inner casing with keys into the bottom
half of the inner-outer casing,
iv) centering the inner-inner casing with respect to the inner-outer casing bottom
half,

v) placing an eccentric bush and a centering bolt in the inner-outer casing hole
and inserting the top head of the centering bolt into the key hole of the
inner-inner casing,
vi) aligning the inner-innercasing with the inner-outercasing, the eccentric bush
being rotated till the desired tolerances are achieved, the eccentric bush
having slot at the bottom coller.
vii) rotating the eccentric bush by placing a rod into the slot and hammering the
bush to rotate till required tolerances on alignment of the innercasing is
achieved.
Drawbacks of the prior art.
1) The process of hammering the rod placed inside an eccentric coller of the
bush is an unsafe practice.
2) This process requires, more manpower for holding and hammering the
rod.
3) The eccentric bush may fall down while rotating during the assembly.
4) There are possibilities of the eccentric bush being damaged.
5) It is a time taking and tedious process.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a holding and adjustment
device for alignment of inner-inner and inner-outer casings of low-pressure
steam turbines, which eliminates the disadvantages of prior art.

Another object of the invention is to propose a holding and adjustment device for
alignment of inner-inner and inner-outer casings of low-pressure steam turbines,
which eliminates the possibility of damaging the eccentric bush of the turbine.
A further object of the invention is to propose a holding and adjustment device
for alignment of inner-inner and inner-outer casings of low-pressure steam
turbines, which is safe, fast, and cost-effective.
SUMMARY OF THE INVENTION
Accordingly, there is provided a holding and adjustment device for alignment of
inner-inner and inner-outer casings of low-pressure steam turbines, comprising :
a main body having a hollow hexagonal head at bottom face . The main body
attached with eccentric bush with least clearance; a rotating handle providing for
rotating the holding ring so that eccentric bush and main body can be attached
to each other and the holding ring is locked with the outer casing by threading. A
a hammer and a forged spanner used for smoothly rotating the main body.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 shows the prior art method of aligning the inner-inner and inner-outer
casings.
Figure 2 shows a holding and adjustment device for alignment of inner-inner and
inner-outer casings of Low-pressure steam turbine according to the invention.

Figure 3 shows a process for aligning the inner-inner and inner-outer casings
with the device of figure 2.
DETAILED DESCRIPTION OF THE INVENTION
The invented holding and adjusting device allows rotating of the eccentric bush
of the turbine. The device comprises a main body having a hollow hexagonal
head at bottom fact and two teeth on top face and a threaded cap (holding ring)
with a center hole for holding the device against the eccentric bush of the
turbine casing.
Working of the device
The eccentric bush needs to rotate from outside bottom of the inner-outer casing
to move the inner-inner casing in the required direction (Left or Right). The
device allows rotating the eccentric bush smoothly with high torque.
The eccentric bush is having a slot at the bottom of its collar. The teeth of the
main body is fitted into the slot with a minimum clearance and the holding ring
provides support to the main body from falling down.

The holding ring has matching threading, which enables the device to be
attached to the inner-outer casing of the turbine. The holding ring is rotated with
the help of a rotating handle (pos.4 in fig.2) by placing it inside the threaded
bush (pos.3 in fig-2) which is welded to the holding ring.
Now with the help of a forged spanner and a hammer the main body can be
easily rotated by a single man.

WE CLAIM :
1. A holding and adjustment device for alignment of inner-inner and inner-outer
casings of low-pressure steam turbines, comprising :
- a main body having a hollow hexagonal head at bottom face;
- at least two teeth configured on the top face of the main body;
- a holding ring with threads and a centre hole, the holding ring
enabling the device to be attached to the inner-outer casing of the
turbine;
- an eccentric bush having a slot for locating the hexagonal head with
least clearance;
- a rotating handle for rotating the holding ring by locating the handle
inside the eccentric bush; and
- a hammer and a forged spanner for smoothly rotating the main body.

ABSTRACT

The invention relates to a holding and adjustment device for alignment of inner-
inner and inner-outer casings of low-pressure steam turbines, comprising : a
main body having a hollow hexagonal head at bottom face; at least two teeth
configured on the top face of the main body; a holding ring with threads and a
centre hole, the holding ring enabling the device to be attached to the inner-
outer casing of the turbine; an eccentric bush having a slot, the main body
attached with eccentric bush with least clearance; a rotating handle providing for
rotating the holding ring so that eccentric bush and main body can be attached
to each other and the holding ring is locked with the outer casing by threading. A
hammer and a forged spanner is used for smoothly rotating the main body.