FIELD OF THE INVENTION
The present invention relates to a device for Edge preparation (EP) of water wall
panel tubes attached to drilling machines. More particularly, the invention relates
to an improved drilling device for Edge preparation of water wall panel tubes of
boiler system.
BACKGROUND OF THE INVENTION
All water wall panels are to be edge prepared before welding. According to the
prior art, the edge preparation of panel tubes is done using a pneumatically
operated edge preparation machine tailor made for this application. Normally,
the raw panel is placed on the supports, a pneumatic edge preparation machine
is hung in a chain hook at a pre-determined height, the edge preparation
machine is locked in the panel tubes and the machine is operated to prepare the
edge of the tubes. The machine is selected to have at least a stroke of 100 mm
and a speed of 90 to 100 rpm.
In once through super crucial boiler technology, there is no drum and ring
header in the boiler design. Hence the shop of the ring header is converted to a
panel shop. For the conversion of the panel shops, only EP machines, cutting
machines and welding machines are applicable.
In the prior art edge preparation process, specific types of EP machines are used.
The machines are hung using a crane and maintained in holding position
throughout the process. The crane is also locked throughout the process.
US Patent Publication US20070110531 Al describes a method of tube edge
preparation in panels. In provides a special tool for in-situ edge preparation of

the tubes in power plant sites during repair works.
US Patent 7143673 B2 describes a specialized milling head used to perform the
micro-diameter tube film removal process.
US Patent Publication US 3518901 A discusses about a drill offset attachment to
the radial drilling machine which is capable of drilling or boring holes in offset
manner in heavy machine parts.
According to prior art, a traveling column drilling machine is used for drilling in
vertical axis only. The Panel is placed in the horizontal plane over supporting
stands. For carrying-out the edge preparation of the boiler tubes, the feed and
spindle rotations is given in the horizontal direction.
OBJECTS OF THE INVENTION
It is therefore, an object of the invention to propose an improved edge
preparation of water wall panel tubes of boiler system.
Another object of the invention is to propose an additional facility for panel tube
edged preparation process.
SUMMARY OF THE INVENTION
Accordingly, there is provided an improved edge preparation of water wall panel
tubes of boiler system. In accordance with the principle of the invention, a
vertical feed in the drilling machine is converted into horizontal feed and rotation.
For converting the vertical axis to horizontal axis, a concept of Bevel gear system
is adopted.

Thus, the inventive drilling machine undertakes the drive transmission by a Spiral
bevel gear system. A simple gearbox is fabricated with the bearing for converting
the vertical axis to horizontal axis. For the fabricated gearbox, the input drive is
taken from the drilling machine spindle. A drill taper shank is attached to the
spiral bevel gear input shaft so that the taper shank can be mounted on the
drilling machine in the same way as a drill bit.
The output end of the fabricated gearbox is constructed in the same way as a
pneumatic EP machine available in the prior art. The pneumatic EP machine
spindle is mated in perfect concentricity to the output spiral gear shaft. Because
of this spindle, the same EP tool used in the pneumatic machine can be used in
the improved drilling machine.
The pneumatic drilling machine has a feed stroke of at least 100mm. To enable
the existing drilling machine to operate in that fashion, a screw rod boxnut
system with a small worm reducer is attached to the known drilling machine.
For locking the panel tubes with the machine, a front portion of the machine is
provided with a V block and a mechanical clamping means.
Thus the invented apparatus saves substantial time (approximately 30% time
reduction) in edge preparation of the boiler tubes ranging from 38mm to 76mm
outside diameter which are to be machined in huge quantities for a boiler system.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1 - shows a schematic view of the device of the invention with all the
internal parts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 shows a schematic view of the improved drilling machine with all the
internal parts. The implement is characterized in that the input drive is taken
from the drilling machine spindle (01). A drill bit taper shank (02) is welded to
the input shaft of a spiral bevel gear with perfect concentricity. The input drive is
given to the spiral bevel gearbox (03). A gearbox with spiral bevel gears is thus
fabricated with all the support bearings required to take the necessary load. The
gearbox converts the vertical drive to horizontal drive.
The prior art EP machine has a feature of cutting feed for about 100mm depth.
To incorporate that feature in the improved drilling machine, a screw rod box nut
arrangement (04) with a small worm reducer gearbox (05) is connected with the
output shaft (06). This arrangement forms a feed mechanism for traverse motion.
The output shaft (06) of the spiral bevel gearbox (03) is connected to the EP
machine spindle (07). The spindle (07) is welded to the spiral bevel shaft in
perfect concentricity by an internal guide pin arrangement (not shown). Since an
existing EP machine spindle with in-built tooling is adapted for the disclosed
invention, the pneumatic cylinder for clamping the tubes is used during
machining. A mechanical clamping system (08) for tube clamping arrangement
with V block (09) and screw (10) to hold the job during machining, is provided to
the improved drilling machine.

WE CLAIM
1. An improved edge preparation of water wall panel tubes of boiler system,
the improvement is characterized by comprising:
- machined spiral bevel gearbox (03); wherein an
input for the gearbox is obtained through a drill bit shank (02) welded
on to the spiral gear shaft, an output of the gearbox is given to the
existing EP tool spindle, and wherein the feed is obtained through a
screw rod (04) with a small worm reducer (05).

ABSTRACT

The invention relates to an improved edge preparation of water wall panel tubes
of boiler system, the improvement is characterized by comprising machined spiral
bevel gearbox (03); wherein an input for the gearbox is obtained through a drill
bit shank (02) welded on to the spiral gear shaft, an output of the gearbox is
given to the existing EP tool spindle, and wherein the feed is obtained through a
screw rod (04) with a small worm reducer (05).