FIELD OF THE INVENTION
Present invention generally relates to edge preparation of pipes used in high
pressure boilers. More particularly the invention relates to an improved tool
holder device adapting a sequence shaped insert for edge preparation of relief
tubes of outlet headers connected to the boiler drum in high pressure boilers.
BACKGROUND OF THE INVENTION
In the high pressure boilers, according to an exemplary embodiment of prior art,
the feed water entering the economizer and the economizer outlet is connected
to a boiler drum through a plurality of relief tube headers of sizes varying from
about 88.9 mm to about 219.1 mm of outside diameter with varying thickness
between 5.49 mm to 30 mm. These pipes are to be edge prepared on both the
ends for butt welding. A special purpose machine known as EPM 220 is used for
making edge preparation.
The cutting tool used in this conventional process is having cutting edges only at
the top and having two useful cutting edges in the opposite direction with
Rhombus shape. Because of this configuration, the other cutting edges are not
utilized in prior art tool holder. This cutting insert doesn't have side rake angle
hence tool life is also less and vibration is more. Because of only two cutting

edges, the cycle time is more and also tool life is less. More over quality is not
frequently obtained leading to rework which causes delay in edge preparation of
tubes. In large plants, normally 4000 tubes are to be edge prepared per month,
which multiplies the magnitude of said problems of prior art.
Hence there is a need to invent a new cutting tool holder with suitable cutting
insert to overcome the above drawbacks.
IN 731/KOL/2011 titled "A single tool holder deployed for edge preparation of
tubes of various sizes" describes a tool holder in which three tool blocks
accommodated with a provision for adjustment of the blocks and these cutting
tools (blocks are) used to perform facing operation, boring operation, chamfering
operation and edge preparation respectively.
The present invention does not have any blocks as described above and hence it
is not relevant to the above invention.
OBJECT OF THE INVENTION
It is therefore an object of the invention to propose an improved tool holder
device adapting a sequence shaped insert for edge preparation of relief tubes of
outlet headers connected to the boiler drum in high pressure boilers.

A further object of the invention is to propose an improved tool holder device
adapting a sequence shaped insert for edge preparation of relief tubes of outlet
headers connected to the boiler drum in high pressure boilers, which is enabled
to adapt during edge preparation process a square shaped insert having both top
and bottom cutting edges.
SUMMARY OF THE INVENTION
According to the invention, there is provided an improved tool holder device
adapting a sequence shaped insert for edge preparation of relief tubes of outlet
headers connected to the boiler drum in high pressure boilers the tool device is
constructed with an included angle of 90°. The modified cutting tool profile
allows a square insert having four cutting edges with reversible provision so that
at least eight cutting edges can be used for the edge preparation of the relief
pipes of the outlet headers connected to the boiler drum of high pressure boilers.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 is a tool holder with rhombus shaped insert having only two useful
cutting edges at the top with include angle 80° (X 1) according to the prior art.
Figure 2 shows an improved cutting tool holder with included angle 90° (X 2)
accommodating a square shaped insert having top and bottom cutting edges
according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION
Referring to figure 2, an improved cutting device holder exhibits an include
angle of 90° (X 2) to enable a reversible square insert to position in all four
sides make edge preparation of the relief pipes in outlet headers of High
Pressure boilers. The device avoiding rework which achieves substantial savings
by using only 5 inserts per month in large plants instead of 75 inserts in the prior
art. Thus, substantial reduction in tool changing time is saved which increases
productivity. Angle selection of X 2 is derived based on the series of experiments
as tabulated below.


From the above table it has been found that, the include angle 90° (X 2) is the
best one and selection of square insert is the best one for the cutting tool device
of the invention

WE CLAIM:
1. An improved cutting tool holder device having a cutting tool holder
angle of 900, characterized in that the device is enabled to adapt a
square insert having eight useful cutting edges, wherein the device
allows edge preparation of boiler piping ranging from 88.9mm to
219.1mm outside diameter with thickness ranging from 5.49mm to
30mm.
2. The device as claimed in claim 1, wherein the square shaped insert is
having reversible and both top and bottom cutting edges.
3. The device as claimed in claim 1, wherein the tubes to be edge
prepared is formed of mild steel to alloy steel.

ABSTRACT

The present invention relates to an improved cutting tool holder device having a
cutting tool holder angle of 900, characterized in that the device is enabled to
adapt a square insert having eight useful cutting edges, wherein the device
allows edge preparation of boiler piping ranging from 88.9mm to 219.1mm
outside diameter with thickness ranging from 5.49mm to 30mm.