FIELD OF INVENTION
The present invention relates to a spindle mounted laser device of a CNC
machine to record two dimensional (2D) coordinates of surfaces without prior
geometrical information and the method for the same. More particularly, the
invention relates to the development of a dead center that can much precisely
record the coordinates of surfaces of complexity or immobile surfaces of eye
level or even high over-head heights such as recording coordinates of turbine
outer casings.
BACKGROUND OF THE INVENTION
A steam turbine consists of three main components viz. outer casing,
inner casing and bladed rotor. For higher rating such as 600/600/800MW, the
size of outer casing of Low Pressure Turbine is in the order of height 6.5 meter,
Width 3.8 meter, Length 4.5 meter and Weight 14 Tons (approx). Rotor of the
turbine is first kept in inner casing and inner casing is then covered by the outer
casing of the turbine. The outer casing is divided into two parts i.e., upper and
lower outer casing. In order to save time, the machining work on both the halves
of the casing has to be performed simultaneously on different shops. Joint
(threaded) holes for fastening the upper and lower outer casing together are first
made on the joint plane of upper half of the outer casing and after that the those
threaded holes are transferred from upper half to the lower half of the outer
casing.
As per prior art, both the halves (lower and upper) were used to placed
together on their joint plane and marking through punches (to remember the
place where the hole is to be done) on lower outer casing was performed
manually through the upper outer casing. For making threaded hole at punched
place on lower outer casing through CNC machine, it was required to feed the
geometric location of the markings/punching in numerical control (NC) program.

For that, the dead center of a CNC machine was taken near the surface of
unknown geometrical information and the coordinate of that place was then
noted down by CNC dead center as its feedback regarding the position of the
spindle (spindle is a rod or pin serving as an axis that revolves or on which
something revolves). Again, since the height of the casing, as mentioned earlier,
is significant, the error in taking the dead center/spindle to the exact place of
marking increases with increase in height from the eye level. Human error also
plays a very significant role as by naked eye it is very difficult to place the dead
center as per requirement.
Since no proper arrangement was available to quickly make the dead
center reach the mark of the punch, the problem was leading to huge
manufacturing time and over usage of the machine on which the job was being
performed. Apart from manufacturing time, checking of the marking was taking a
lot of time that was resulting in high fatigue and work pressure on operators.
Additionally, Crane needed to be engaged and therefore high men power was
required. In order to eliminate all these problems, it was required to propose
some solution of marking the holes in casing.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose a spindle mounted
laser device of a CNC machine to record two dimensional (2D) coordinates of
surfaces without prior geometrical information which is capable of recording
precisely the 2-Dimension coordinates of surfaces of complexity which are in
eye-level or even higher than that.
Another object of the invention is to propose a spindle mounted laser
device of a CNC machine to record two dimensional (2D) coordinates of surfaces
without prior geometrical information which is able to reduce the cycle time in
recording the holes compared to manual recording of prior art.

A further object of the invention is to propose a spindle mounted laser
device of a CNC machine to record two dimensional (2D) coordinates of surfaces
without prior geometrical information which is capable of reducing man hours
compared to old method.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1: Shows assembled invented two dimensional (2D) coordinates
recording laser device clamped with CNC machine .
Fig. 2 : Shows assembled 2-D coordinates recording laser device according
to the invention.
Fig. 3 : Shows laser unit used in the device.
Fig. 4 : Shows outer shell of the device.
Fig. 5 : Shows laser marking system on lower half of LP outer casing.
Fig. 6 : Shows an actual photographic view of the invented device (outer
shell with laser device).
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
The invented spindle mounted laser device (L) replaces the conventional
CNC position defining dead centers with an advance laser system which can
more precisely define, identify and hence make one able to record the 2-d
coordinates of any point on a surface of unknown geometric information.
As shown in Fig.1 and Fig.2 the invented device in fully assembled
conditions consists of following items:
Item L: Laser device.
Item 1: Threaded M8 Bolt
Item 2: Outer shell of the device

Item 3: M20 Bolt
Item 8: On-Off Button on the laser machine
Item 9: 1mm x 1mm square Hole in item-2 for laser light to emit
Item 10: Laser Unit Main body inside the Outer Shell
Item 11: Tip of the laser unit
Item 12: Threads for Item-3
This device (L) in fully assembled condition is attached to the CNC
Machine in replacement of the dead center. The parts of the machine used are:
Item 4: Clamping Collar
Item 5: Spindle
Item 6: Hexagonal Nut to tighten Clamping collar on
Item 7: CNC Machine Head
As shown in Fig.2 and Fig.3, the Laser Device (L) are made of a Outer
Shell (2) and a Laser Unit (10) placed inside the shell (2). The outer shell is
made of brass.
The Laser Unit (10) (Fig.3), consisting of Tip of the laser (11) and spring
loaded On-Off Switch (8), is the standard device available over the counter. The
laser unit (10) is put in the Outer Shell (2) as shown in Fig.4 in such a way that
the tip (11) of the laser unit (10) is towards the 1mm x 1mm square hole (9)
given in the front side of the device (L). The laser emits a very narrow coherent
low-powered laser beam through the tip (11) of the laser unit in the form of a
pointer and passes through the outer shell through 1mm x 1mm square hole (9).
The laser is battery powered, so it is required that the laser unit should be
able to come out of the Outer Shell (2) whenever required to replace the battery.
For the same purpose, a special bolt (3) of 20mm diameter, 28mm length has
been made in such a way that it is assembled through threaded joint at the back

of the laser unit (10) (opposite to the tip side) through its 25mm threaded length
(12) and keep the laser unit (10) intact and motionless.
The laser unit (10) needs to be switched off when not in use and for the
same a spring loaded On-Off switch (8) was already there on the standard laser
device. But since the device would be inside the Outer Shell (2), it would not be
feasible to open the special Bolt (3) time and again to switch off and on the unit.
For the same, a provision is made using an M8 bolt, which will be inserted in the
Outer Shell (2). The length of the bolt (1) is kept longer in such way that when
the bolt would be tightened, it would press the spring loaded on/off button (8) of
the standard unit (10). The bolt (1) would be loosened when the laser unit is not
in use.
First, the punching marks are made by slight hammering/punching on the
lower half of the turbine outer casing through upper half. For a fix position of the
"Dead Center" of the CNC Machine, there would be a fix position of the machine
spindle (5) also and CNC machine records the 2-D coordinates of the spindle with
reference to a originally set origin (Fig.5). Here, this laser device (L) replaces the
dead center. The Laser Unit is clamped tightly to the spindle (5) of the CNC
Machine Head (7) through Collars (4)(Fig.l).It is the CNC machine head (7) in
which the spindle (as in turn laser device) moves to reach the punch mark.
This device (in ON condition) is then taken to the punching mark whose
coordinates are to be recorded. When the laser beam/point becomes concentric
with that of punching mark, the coordinate is shown on the panel of the CNC
machine which is being recorded by machine or manually. The process is
repeated for all the punching done on the lower half of the casing. Since the
machine of these holes is done on CNC machine, the noted co-ordinates would
be feed in the NC program while machining of holes in lower half.

We Claim:
1. Spindle mounted laser device (L) of a CNC machine to record two
dimensional coordinates of surfaces without prior geometrical information and
the method for the same, the said laser device comprising;
an outer shell (2) of the device for housing a laser unit (10);
a laser unit (10) disposed inside the outer shell (2) to form together a
laser device (L) for recording the coordinates;
the said laser unit (10) having its tip (11) placed towards the square hole
(9) in front side of the unit (10) for emitting a very narrow laser beam.
a spring loaded on-off switch (8) disposed on the laser unit (10);
an M 8 bolt inserted into a threaded hole disposed on the outer shell for
operating the on and off switch (8) of the laser unit (10);
a special bolt (3) assembled at the threaded joint at the back of the laser
unit (10) and disassembled at the time of changing the battery of the laser unit
(10); characterized in that,
the laser unit is clamped tightly to the spindle (5) of the CNC machine
head (7) through collars (4) such that when the machine head (7) moves, the
laser device in turn moves to reach the punch mark punched on the lower half of
the turbine outer casing when the laser beam passing through the square hole
(9) of the laser unit becomes concentric with that of punching mark showing the
co-ordinates on the panel of the CNC machine.
2. A laser device (L) as claimed in claim 1 wherein the outer shell (2) is
made of brass.

3. A laser device (L) as claimed in claim 1, wherein the laser unit (10) has a
square hole (9) of 1 mm x 1 mm for allowing the tip (11) of the laser unit (10) to
emit a very narrow coherent low-powered laser beam.
4. A method to record two dimensional (2D) coordinates of surfaces without
prior geometrical information by the laser device claimed in claim 1, the said
method comprising;
making punching marks on the lower half of the turbine outer casing through
upper half;
providing a laser unit (10) inside an outer shell (2) to form a laser device (L);
providing a spring loaded on and off switch (8) on the laser unit;
disposing a bolt (1) in a threaded hole of the outer shell (2) to operate the
spring-loaded switch (8);
assembling a special bolt (3) to the threaded joint at the back of the laser unit
(10) to facilitate replacement of battery of the laser unit (10) and to keep the
said unit intact and motionless; wherein
the laser unit (10) is put in the outer shell (2) in such a manner that the tip (11)
of the laser unit (10) is towards the square hole (9) to emit a very narrow
coherent low-powered laser beam through the tip (11) of the laser unit (10) in
the form of a pointer passing through the square hole (9) of the device (L) when
the laser device (L) is clamped to the spindle of the CNC machine head (7)
through collars (4) when the spindle and in turn laser device moves and the
device (L) is taken to the punching mark in ON condition wherein the laser beam
becoming concentric with that of said punching marks resulting the coordinates
being shown on the panel of the CNC machine.

5. The method as claimed in claim 4, wherein the special bolt (3) is of 20mm
diameter and 28mm length and is assembled to a threaded length of 25mm (12)
at the back of the laser unit (10).
6. The method as claimed in claim 4, wherein the length of the bolt (1) is
kept longer in such a way that when the bolt is tightened , it presses the spring
loaded on/off button (8) of the lesser unit (10) to make it ON and is loosened
when the said unit (10) is not functioning.

ABSTRACT

The invention relates to a spindle mounted laser device (L) of a CNC
machine to record two dimensional coordinates of surfaces without prior
geometrical information. Punching marks are made by slight hammering on the
lower half of the turbine outer casing through upper half. A laser unit (10) is put
inside an outer shell (2) to form a laser device (L). The laser unit is disposed in
the said shell (2) to emit a very narrow coherent low-powered laser beam
through the tip (11). A bolt (1) is disposed in a threaded hole of the outer shell
(2) to operate ON and OFF switch of the laser unit (10). A special bolt (3) is
assembled at the back of the laser unit (10) to facilitate replacement of battery
of the laser unit (10) when the laser device (L) is clamped to the spindle of the
CNC machine head (7) through collars (4) when the spindle and in turn laser
device (L) moves and the device is taken to the punching marks wherein the
laser beam emitting in the form of a pointer becomes concentric with said
punching marks resulting the coordinates being shown on the panel of the CNC
machine.