FIELD OF INVENTION
This invention relates to a device for machining of slits on the joint
plane of IP inner casing of steam turbines. The tooling refers to
segmental circular saw with variable body thickness for machining
of slits on the joint plane of upper half and lower half of LP inner
casings.
BACKGROUND OF THE INVENTION
Currently, segmental circular saw cutter of Dia. 1430mm having
uniform body thickness of 10 mm is used for machining slits on
the joint planes of upper half and lower half of LP. Inner casings
on the conventional horizontal borer. Cutter of uniform thickness
is generally available in the market. Width of the segments
mounted on the periphery of the cutter is also 10mm (as shown in
fig. 1). Achieved slit size using this cutter is 14-15mm against
requirement of slit size of ≤ 10mm as per the figure.
Thickness of the segmental circular saw could not be reduced
because of higher level of vibrations due to large diameter of the
cutter which would have resulted in breakage of the cutter during
operation.
This is a recurring problem in machining of slits which is not
acceptable to customer.

OBJECTS OF THE INVENTION
The primary object of the present invention is to provide a device
for machining of slits on the joint plane of IP inner casing of steam
turbines which overcomes disadvantages associated with the
known art.
Another object of the present invention is to provide a device for
machining of slits on the joint plane of IP inner casing of steam
turbines which is simple in construction.
Still another object of the present invention is to provide a device
for machining of slits on the joint plane of IP inner casing of steam
turbines which is efficient.
STATEMENT OF INVENTION
According to this invention, there is provided a device for
machining of slits on the joint plane of IP inner casing of steam
turbines comprising of a circular saw body with bore provided with
a side plate with bore on both sides riveted to each other wherein a
plurality of holes are provided on the circular saw body for
mounting of the cutting segments.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Further objects and advantages of this invention will be more
apparent from the ensuing description when read in conjunction
with the accompanying drawings and wherein:
Fig. 1 shows: conventional saw cutter.
Fig. 2 shows: saw cutter of the present invention.
Fig. 3 shows: details of slits on the joint plane of LP. Inner casing.
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE
TO THE ACCOMPANYING DRAWINGS:
The present invention discloses a device for machining of slits on
the joint plane of IP inner casing of steam turbines. Referring to fig.
2 and 3, wherein the device comprising of a circular saw body with
bore of atleast 150mm and thickness of atleast 6mm. Said saw
body is provided with a side plate on both sides. Said side plate is
atleast 3 mm thick with 830 mm diameter and 150 mm bore.
Atleast six holes of diameter 10 mm on PCD of 400 mm and 650
mm are provided on the side plates for clamping with the main
cutter body. Thereafter, one side of these side plates are precisely
ground.
Said holes of diameter 10 mm on PCD of 400 mm and 650mm are
then transfer marked on the main cutter body to ensure perfect
alignment of the holes during fit up. The machined plates are
mounted on both sides of the main cutter body, which are riveted
together.

A plurality of holes are provided for mounting of the cutting
segments on PCD of 1348 mm and atleast four holes of maximum
diameter of 26 mm on PCD of 225 are provided for mounting of
cutter.
A plurality of segments of HSS M-2 material having atleast four
cutting teeth and thickness of 8 mm are fixed and riveted on the
periphery of circular saw cutter. Thus, the cutter body provides the
mechanical strength while HSS M-2 segments cut the material.
A plurality of segments are riveted on outer diameter of 1348mm to
achieve diameter of 1430mm. Said segments along with circular
saw cutter constitute cutter of the present invention.
Figure 2 shows complete details of segmental circular saw cutter of
the present invention.
Figure 3 shows LP. Inner Casing (Upper half & Lower half) in
which machining of slits is to be done. The slits are machined on a
conventional Horizontal boring machine.
Advantageous features
Use of the cutter has been successfully established for accurate
machining of slit of the joint plane of upper half and lower half of
LP. Inner Casings.
The instant invention is applicable for all large size cutters which
run the risk of breakages during cutting operations and are unsafe
and have risk hazards.

As the vibrations during cutting operations are minimized, the
risks of breakage of cutters is avoided & slits of desired quality as
per requirement are machined without any problem.
It is to be noted that the present invention is susceptible to
modifications, adaptations and changes by those skilled in the art.
Such variant embodiments employing the concepts and features of
this invention are intended to be within the scope of the present
invention, which is further set forth under the following claims:-

WE CLAIM:
1. A device for machining of slits on the joint plane of IP inner
casing of steam turbines comprising of a circular saw body
with bore provided with a side plate with bore on both sides
riveted to each other wherein a plurality of holes are
provided on the circular saw body for mounting of the
cutting segments.
2. A device as claimed in claim 1, wherein said circular saw
body and side plate are having bore, thickness and diameter
of atleast 150mm, 150mm; 6mm, 3mm and 1330mm,
830mm respectively.
3. A device as claimed in claim 1 or 2, wherein atleast six holes
of diameter 10 mm on PCD of atleast 400mm and 650 mm
are provided on the side plates for clamping with the main
cutter body.
4. A device as claimed in any of the preceding claims, wherein
said plurality of holes are provided for mounting of the
cutting segments on PCD of 1348 mm and atleast four holes
of maximum diameter of 26 mm on PCD of 225 are provided
for mounting of cutter.
5. A device as claimed in any of the preceding claims, wherein
said plurality of segments of HSS M-2 material having
atleast four cutting teeth and thickness of 8 mm are fixed
and riveted on the periphery of circular saw cutter.

6. A device for machining of slits on the joint plane of IP inner
casing of steam turbines substantially as herein described
with reference to the accompanying drawings.

This invention relates to a device for machining of slits on the joint
plane of IP inner casing of steam turbines comprising of a circular
saw body with bore provided with a side plate with bore on both
sides riveted to each other wherein a plurality of holes are provided
on the circular saw body for mounting of the cutting segments.