FIELD OF INVENTION:
The invention generally relates to development of a portable pneumatic grinder
to carry the local material removal through grinding.
Particularly, the present invention relates to a sonar machine having a
innovative grinding technique for material removal through grinding over any
metallic surface or a surface where other conventional grinding method can
beapplied. Local material removal from the joint plane surface of outer casing
of the turbine is taken here as reference.
BACKGROUND OF INVENTION:
The modern day coal fired steam turbine essentially consists of outer casing
serving as the pressure containment element, inner casing with guide
bladeswhich along with bladed rotor provides the steam flow path in the
turbine.
Design requires the casing-of the turbine to be manufacturedinto two halves
mating at joint planes during trial assembly, hydraulic testing.
To serve the intended purpose, the flatness at the parting plane assumes
utmost significance which at times deviates owing to machining inaccuracies.
Turbine casings are usually assembled in two halves, to facilitate assembly.
These two halves are joined with the help of studs/ bolts, after ensuring color
matching to obviate steam leakage. Studs/ bolts provide necessary force to
keep these halves together against pressure which is trying to force open the
parting plane to ret steam out and separate both the halves of the casing. The
temperatures and pressures, in the modern steam turbines, are very large

leading to large size of the plane studs/ bolts. These studs/ bolts are to be
borne by the flanges provided on both the halves of the turbine casing. Large
sized studs/ bolts mean large flanges. These joints at flangesare usually
referred as "PARTING PLANE".
The present day method to achieve the desired result involves the use
ofmanualbuffing wheel, sandpaper which is not reliable and when this
methodis practiced, process the becomes iterative resulting in increase of
assemblycycle time. Apart from these this process covers lesser surface area
and hencethe process is tedious when applied over larger size casings.
OBJECTS OF THE INVENTION;
An object of the invention is to develop a portable pneumatic grinder which can
reduce in assembly cycle time.
Another object of the invention is to develop a portable pneumatic grinder
which can provide quality assurance.
SUMMARY OF THE INVENTION;
A hose pipe containing pneumatic pressure is connected to hoseconnection.
The main body of the holding attachment contains animpeller which rotates
when pressurized air coming through hose connection strikes the blade of the
impeller. The impeller is connected to the impellershaft. The impeller shaft
rotates with the impeller. The tip of the impeller shaft is in atapered square
form.The holding attachment and the grinding unit assemble to each other
through a thread joint between on impeller shaft and grinding unit shaft. The
length of the shaft is kept in such a way that the tapered square tip fits into
tapered square slot provided at the end of the grinding unit shaftin the main
body of grinding unit.At the other end of grinding unit shaft is installed a

major belt wheel.Belt wheel minor of grinding unit is also installed on the main
body ofthe grinding unit through screw connection. The shaft of the
minorwheel is supported on bearing inside the main body.When the pneumatic
pressure through air is provided impeller shaft rotates which finally rotates the
major wheel. The minor wheel and the major wheel supportsthe grinding belt
as selected for the finishing operation.
BREIF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 shows the pneumatic grinder according to the invention.
DETAILED DESCRIPTION OF A PREFFERED EMBODIMENT OF THE
INVENTION:
The assembly process of high pressure and intermediate pressure cylinder of
steam turbine includes a series of process, majorly, the color matching of outer
casing, hydraulic pressure test of casing, checking the alignment of stationary
part with rotating part etc. Each of these process involves joining the two
halves of casing/shells.
The functionality is served depending upon the flatness of surface at joint
planes but the process local grinding is carried out to remove the high points
on parting plane surface that appears during machining. The joint plane
matching to ensure the leak proof joint is an iterative process which requires
uniform material removal at parting plane surface area to remove high points,
depressions if any which may have appeared during preceding processes.
Figure 1 shows the pneumatic grinder according to the invention.
A hose pipe containing pneumatic pressure is connected to hose connection (4).
The main body of the holding attachment (A) contains an impeller which

rotates when pressurized air coming through hose connection (4) strikes the
blade of the impeller. The impeller is connected to the impeller shaft (5). The
impeller shaft (5) rotates with the impeller. The tip of the impeller shaft is in a
tapered square form.
The holding attachment (A) and the grinding unit (B) assemble to each other
through a thread joint between (2) and (10).
The length of the shaft (5) is kept in such a way that the tapered square tip
(ll)fits into tapered square slot provided at the end of the grinding unit shaft
(12)in the main body (6) of grinding unit (B).
At the other end of grinding unit shaft (12) is installed a major belt wheel (7).
Belt wheel minor (8) of grinding unit (B) is also installed on the main body (6) of
the grinding unit through screw connection (9). The shaft (13) of the minor
wheel (8) is supported on bearing inside the main body (6).
When the pneumatic pressure through air is supplied impeller shaft (5) rotates
which rotates the major wheel (7). The minor wheel (8) and the major wheel (7)
supports the grinding belt as selected for the finishing operation.
The grinder uses abrasive belt of varying width and grit sizes as working
medium which are wrapped over head and rotates at constant speed. The
grinder being portable and light weight provides the ease of use and ensures
uniform material removal resulting in desired quality requirements.

WE CLAIM;
1. A portable pneumatic grinder comprising:
- a housing attachment (A) which includes a hose (4) at one end to
receive pneumatic pressure, wherein the hose (4) is coupled to a main body (3)
that comprises a holding grip (1); impeller connected to a impeller shaft (5)
tapered at its end in a square shape wherein a portion of the impeller shaft (5)
in encapsulated in a thread joint (2);
- a grinding unit (B) that comprises a threaded joint (10) at one end
which engages to the thread joint (2) of the holding attachment (A), a main
body (6) that allows passage of a grinding unit shaft (12) supported by bearing
means wherein the length of shaft (5) is extended to engage to a tapered square
slot at an end of the grinding unit shaft (12); that connects to a major wheel
(7), a belt wheel minor (8) installed on the main body (3) fastened by means of
screw (9) wherein the belt wheel minor (8) that comprises a shaft (13)
supported by bearing means.
2. A portable pneumatic grinder as claimed in claim 1, wherein the belt wheel
minor (8) and the major wheel (7) supports a grinding belt.