FIELD OF INVENTION
The present invention relates to an improved dead center for centering heavy
rotors on lathe. More particularly, the present invention related to a dead center which
is lighter in weight such that it can be used for centering purpose, on lathe machines or
any other machine of its kind, easily without any hazards and accurately.
BACKGROUND OF THE INVENTION
A turbine is a turbo machine with at least one moving part called a rotor
assembly, which is a shaft or drum with blades attached. Moving fluid acts on the
blades so that they move and impart rotational energy to the rotor which in turn rotates
the generator to produce electricity. A steam turbine/Turbo generator consists of one
essential component called rotor. The weight of a Rotor in Power Production Industry
can go upto 200 tonnes. The unfinished rotor is brought as a forging part and then it
goes into numerous machining and inspection operations like turning before getting
converted into a finished rotor (refer fig.1).
A rotor may be mounted on a mandrel, or circular work clamped in a three- or
four-jaw chuck. Number of Jaw depends on the weight of the rotor to be supported.
These holding devices mount directly to the Lathe headstock spindle. In precision work
like rotor machining, cylindrical rotors are usually held in a chuck into the spindle.
Chucks are tightened on the flange of the rotor through vice and jaws so as to impact

the rotary motion to the rotor on its axis to perform various machining operations with
tools to create an object has symmetry about an axis of rotation.
A dead center is a technological item that has been ground to a point to
accurately position a rotor on an axis.
Since the forgoing of the rotor is very heavy and is to be placed in the chuck, the
dead center is placed in the center of the headstock and placement of jaw of the chuck
is done from the tip of the dead center to the inner dia of the jaws of the chuck. This
inner chuck dia is equal to the diameter of the rotor flange (refer fig,l).
Rotor placement on lathe is performed on the chucks by first placing the heavy
unfinished rotor on the Jaws of the chuck below the axis of rotation of the rotor flange
so as to first support the weight of the rotor and then the jaws above the axis of
rotation are tightened so as to prepare the rotor for machining.
This operation of placing dead center in lathe machine become cumbersome
since the weight of the dead center is too large and EOT crane is enagaged till the time
centering is done. Hence, it is not easy to pick the dead center and place it in the
center slot between the Jaws in the headstock.
The overall process is lengthy and hazardous and as such there is no other
technology item present to make the process easy.

Therefore it is required to have a new improved dead center that can establish a
standard method of centering heavy rotors.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose an improved dead center
for centering heavy rotors on lathe, which is of less weight and can be installed in the
chucks of the lathe machine without the help of a crane.
Another object of the invention is to propose an improved dead center for
centering heavy rotors on lathe which makes the process of installing the dead center
easy and thus capable of eliminating a length and hazardous process.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1: Shows the Rotor to be machined.
Fig. 2: Shows the arrangement of the dead center in the chucks.
Fig. 3: Shows the improved dead center according to the invention.
Fig. 4: Shows the invented dead center in the spindle bore of machine head.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
The improved dead center as shown in Fig.3. having the following Items.
Item-1: Center shaft of the dead center
Item-2: Plurality of collars for support

Item-3: Plurality of threads
Item-4: Tip of the center shaft with 60 degree tip nose
Item-5: Major tapered support
Item-6: Minor tapered support
Item-7: Plurality of locking nuts
Item-8: Front plate
Item-9: Jaws
Item-10: Vices
The assembly of the dead center consists of the following;
A center shaft (1) of the dead center (C) that provides center support of the
whole assembly. The center shaft (1) is having two-collars (2) integral with the said
shaft (1) for providing support. The top and bottom part of shaft (1) are threaded (3).
The shaft goes through the center of the hole of taper wedges (5,6) and through a
front plate (8). The shaft is assembled with plate (8), wedges (5 and 6). The shaft (1) is
of plain diameter for a length from the major taper (5) to minor taper support (6) inside
the spindle bore. The nuts (7) at the top of plate (8) and wedges (5,6) are disposed for
tightening the assembly. The taper of the wedges (5,6) are same as the Morse taper of
the spindle bore. The wedges are major tapered support (5) and minor tapered support
(6) for the dead center (C). These tapered supports (5,6) are made of Bakelite or wood
in order to reduce the weight of the dead center (C). These supports (5,6) rest against
the collars (2) and is tightened by a nut (7) on a threaded part (3) of shaft. A front
plate (8) is disposed between the support (5) and the nut (7) when it is tightened by

the nut (7) over the thread (3) in such a way that there is no movement of the front
plate (8).
The tip (4) made integral with center shaft (1) has a tip nose of 60 degree and is
placed in front of the dead center.
The assembled invented dead center is placed in the tapered spindle bore of the
chuck of the lathe machine which is provided for holding the dead center with the help
of vice and jaws.
The dead center is used as reference for measuring the distance of the tip of the
dead center from a projected part of jaw. This distance is the inner radius of the jaw
which are made equal for all jaws so that all points of the inner diameter of the jaws
from the tip of the center (4) are of same distance. The chuck holds the vices and the
vices (10) hold the jaws (9).
Major and minor tapered supports are assembled in the spindle bore in such a
way that the taper of the supports perfectly matches with the taper of the spindle bore
and fits in a shrink fit connection with the machine head so that there is no axial
movement in the dead center during measurements. The major tapered support (5) is
disposed on the center shaft (1) at such a length that the machine head become a

natural collar support for plate (8). The overall length of the dead center (C) is kept in
such a way that the tip (4) of the center shaft (1) is in the same plane as that of an
extended part of jaws (9) such that the corner of the adjacent jaws (9) of the chunk
are taken as reference during measurements.
Since the tip of the radius (4) is the obvious center of the whole system,
placement of jaw (9) of the chuck is done from the tip of the dead center to the inner
dia of the jaw of the chucks. This dia is equal to the dia of the rotor flange (refer fig. 1).
This is performed on the chucks below center axis of rotation so as to first support the
heavy unfinished rotor. After then the chuck above the axis of rotation of the rotor
flange are tightened so as to prepare the rotor for machining operations.

WE CLAIM
1. An improved dead center for centering heavy rotors on lathe comprising;
a center shaft (1) of the dead center (C) having integral collars (2) on it for
providing support to the system;
one major taper support (5) and minor taper support (6);
a front plate (8);
characterized in that;
the center shaft (1) along with the collar (2) passing through the holes disposed
in front plate (8) and taper supports (5,6) wherein the taper supports (5,6) disposed in
the front and rear end of the dead center (C) and resting on collars (2) matches
perfectly with the taper of a spindle bore when the plain diameter center shaft is
exposed in the spindle bore for a length between the two taper supports (5,6) wherein
a plurality of nuts (7) are disposed for tightening the assembly over a thread length (3)
of the shaft against the front plate (8) restricting the movement of the said plate when
the length of the tapered supports (5,6) are made to a predetermined length such that
machine head becomes a natural collar support for plate (8) wherein the overall length
of the dead center (C) is kept in such a way that the tip (4) of the center shaft (1) is in
the same plane as that of an extended part of 3aws (9) such that corner of adjacent
jaws of the chuck are taken as reference during measurements.
2. An improved dead center as claimed in claim 1, wherein the major (5) and minor
(6) tapered support are made of Bakelite or wood for reducing the weight of the dead
center.