DESCRIPTION
WELD BEAD CUTTING DEVICE AND METHOD OF REMOVING RADIAL PIN OF
STEAM TURBINE
TECHNICAL FIELD
[0001]
The present invention relates to a weld bead cutting
device for cutting a weld bead formed on a periphery of one end
portion of a pin having the one end portion protruded from a
surface of a structure and the other end portion inserted into
a hole formed in the structure, and a method of removing a radial
pin of a steam turbine using the weld bead cutting device.
BACKGROUND ART
[0002]
Conventionally, a pin has been used for various uses such
as coupling and fixing mechanical portions to each other and
the like and, among them, there is a case where the pin is welded
to the mechanical portion in order to prevent the removal of
the pin. In this case, one end portion of the pin is inserted
into a hole formed in a structure as the mechanical portion,
the other end portion of the pin is protruded from the surface
of the structure, and a weld bead is provided on the periphery
of the other end portion. With this, the weld bead prevents
the removal of the pin.
1
[0003]
An example of the pin fixed to the structure using the
weld bead in this manner includes a radial pin used for
positioning a blade ring, a dummy ring, or an internal casing
with respect to a turbine casing in a steam turbine in a nuclear
power plant or a thermal power plant.
[0004]
For example. Patent Document 1 describes a radial pin for
setting the position of a blade ring or a dummy ring with respect
to a rotor of a turbine. Note that, though not clearly described
in Patent Document 1, in general, the radial pin has a portion
protruded from an outer surface of a turbine casing, and the
radial pin is fixed to the turbine casing by forming a weld bead
on the periphery of the portion.
[0005]
When the periodic inspection or modification of the steam
turbine is carried out, there is a case where the radial pin
is removed and the steam turbine is disassembled. In this case,
it is necessary to remove the weld bead provided on the periphery
of the radial pin, and the removal of the weld bead has been
conventionally performed by the following method.
[0006]
FIG. 7 is a view showing the removal of the weld bead
provided on the periphery of the radial pin in which FIG. 7(a)
shows an entire turbine casing, while FIG. 7(b) shows an
2
enlarged portion in the vicinity of the radial pin (an area
indicated by A of FIG. 7(a)).
As shown in FIG. 7(a), after a dedicated machine 50 is
installed on a floor F via a machine installation stand 52, a
turbine casing 1 is hoisted using a crane, moved to a
predetermined position, and placed over the dedicated machine
50. Note that, at this stage, a large-diameter drill 54A for
perforation is attached to the dedicated machine 50. On the
other hand, a radial pin 2 is inserted into a through hole 3
provided in the turbine casing 1, a portion thereof is protruded
from an outer surface of the turbine casing 1, and a weld bead
4 (see FIG. 7(b)) is formed on the protruded portion.
In a state where the turbine casing 1 is placed over the
dedicated machine 50, as shown in FIG. 7(b), after a large
diameter hole 5 is formed in the radial pin 2 from the inside
of the turbine casing 1 by using the large-diameter drill 54A
of the dedicated machine 50, the large-diameter drill 54A is
replaced with a small-diameter drill 54B, and a through hole
6 is formed by using the small-diameter drill 54B. Herein, the
reason why the two-stage perforation operation using the
large-diameter and small-diameter drills 54A and 54B is
performed is to prevent the displacement of the center position
of the through hole 6 by using the large diameter hole 5 as a
guide such that the turbine casing 1 is not damaged.
Thereafter, a cutter main body 56 is attached to the
3
dedicated machine 50, the cutter main body 56 is inserted into
the through hole 6 from the inside of the turbine casing 1, a
cutting blade 57 is attached to a peripheral surface of the
cutter main body 56, and the cutter main body 56 is rotated by
the dedicated machine 50, whereby the cutting of the weld bead
4 is performed.
[0007]
Although FIG. 7(a) shows the upper half portion of the
casing having a structure divided into halves as the turbine
casing 1, when the turbine casing 1 corresponds to the lower
half portion of the casing, a base plate is placed on a horizontal
dividing plane of the casing in spanning relation, the dedicated
machine 50 is installed on the base plate via the machine
installation stand 52, and the cutting of the weld bead 4 is
performed according to the same procedures as those in the case
of the upper half portion of the casing.
[0008]
[Patent Document 1] Japanese Unexamined Utility Model
Application Publication No. S61-17104
[0009]
However, in the conventional method described above, in
order to remove the weld bead 4, the large diameter hole 5 and
the through hole 6 need to be formed in the radial pin 2 in advance
so that working efficiency has been low, and there has been a
possibility that the through hole 3 of the turbine casing 1 is
4
damaged.
In addition, a large torque is required in order to form
the large diameter hole 5 and the through hole 6 in the radial
pin 2 so that the large dedicated machine 50 having an electric
motor mounted thereon had to be used. As a result, in displacing
the position of the dedicated machine 50, it has been necessary
to hoist and move the dedicated machine 50 itself using the
crane.
DISCLOSURE OF THE INVENTION
[0010]
The present invention has been achieved in view of the
above-described circumstances, and an object thereof is to
provide a weld bead cutting device which is capable of cutting
a weld bead without forming a through hole in a pin and has a
low possibility of damage to a structure as well as having
excellent working efficiency and light weight, and a method of
removing a radial pin of a steam turbine using the weld bead
cutting device.
[0011]
The weld bead cutting device according to the present
invention is a weld bead cutting device for cutting a weld bead
formed on a periphery of one end portion of a pin having the
one end portion protruded from a surface of a structure and the
other end portion inserted into a hole formed in the structure,
5
including a cutting unit which cuts the weld bead formed on the
periphery of the pin, and a support unit which supports the
cutting unit on an end surface of the one end portion of the
pin such that the cutting unit is movable along the periphery
of the pin.
[0012]
According to the weld bead cutting device, since there
is provided the support unit which supports the cutting unit
which cuts the weld bead on the end surface of the pin (the end
surface of the one end portion) protruded from the surface of
the structure such that the cutting unit is movable along the
periphery of the pin, it is possible to cut the weld bead without
forming a through hole in the pin, and significantly improve
working efficiency.
In addition, the through hole is not formed in the pin
so that it is possible to reduce the possibility of damage to
the structure, and a small torque is sufficient for the weld
bead cutting device so that it is possible to adopt a lightweight
configuration using, e.g., an air grinder or the like.
[0013]
In the above-described weld bead cutting device, the
support unit preferably includes a support shaft provided to
stand on the end surface of the one end portion of the pin, a
coupling member which couples the cutting unit to the support
shaft, and a bearing which supports the coupling member such
6
that the coupling member is pivotable about the support shaft.
[0014]
In this manner, by supporting the cutting unit by using
the support unit including the support shaft, the coupling
member, and the bearing, it is possible to cause the cutting
unit to pivot about the support shaft together with the coupling
member to smoothly move the cutting unit along the periphery
of the pin. With this, it becomes easy to cut the weld bead
formed on the periphery of the pin without damaging the
structure.
[0015]
In the above-described weld bead cutting device, the
support shaft is preferably screwed to a screw hole formed in
the end surface of the one end portion of the pin, the screw
hole being a circle generally concentric with a circular shape
of a cross section of the pin.
[0016]
In this manner, the support shaft is screwed to the screw
hole which is formed in the end surface of the pin (the end
surface of the one end portion) protruded from the surface of
the structure and is the circle generally concentric with the
circular shape of the cross section of the pin, whereby it is
possible to move the cutting unit at a desired locus along the
periphery of the pin by causing the cutting unit to pivot about
the support shaft together with the coupling member. With this,
7
it is possible to prevent damage to the structure during the
cutting of the weld bead.
[0017]
In the above-described weld bead cutting device, the
cutting unit may have a cutting blade for cutting the weld bead
on a tip side in its longitudinal direction, and the cutting
unit may be attached to the coupling member such that an angle
formed by the longitudinal direction of the cutting unit and
the support shaft is not less than 0 degree and not more than
60 degrees.
In this case, the above-described weld bead cutting
device preferably includes an angle adjustment unit which
adjusts the angle formed by the longitudinal direction of the
cutting unit and the support shaft.
[0018]
In this manner, by setting the angle formed by the
longitudinal direction of the cutting unit and the support shaft
to not less than 0 degree and not more than 60 degrees, it is
possible to easily perform a cutting operation of the weld bead
using the cutting blade of the cutting unit. In addition, by
providing the angle adjustment unit, it is possible to bring
the cutting unit into contact with the weld bead at an
appropriate angle constantly in accordance with the progress
of the cutting operation of the weld bead.
[0019]
8
The above-described weld bead cutting device preferably
further includes a radial position adjustment unit which
adjusts a position of the cutting unit in a radial direction
of the pin.
In addition, the above-described weld bead cutting device
preferably further includes an axial position adjustment unit
which adjusts a position of the cutting unit in an axial
direction of the pin.
[0020]
In this manner, by providing the radial position
adjustment unit which adjusts the position of the cutting unit
in the radial direction of the pin or the axial position
adjustment unit which adjusts the position of the cutting unit
in the axial direction of the pin, it is possible to bring the
cutting unit into contact with the weld bead at an appropriate
position constantly in accordance with the progress of the
cutting operation of the weld bead.
[0021]
In the above-described weld bead cutting device, the
structure may be a turbine casing of a steam turbine, and the
pin may be a radial pin for positioning a blade ring, a dummy
ring, or an internal casing of the steam turbine with respect
to the turbine casing.
[0022]
The method of removing a radial pin of a steam turbine
9
according to the present invention is a method of removing a
radial pin for positioning a blade ring, a dummy ring, or an
internal casing of a steam turbine with respect to a turbine
casing of the steam turbine by using the above-described weld
bead cutting device, the radial pin having one end portion
protruded from an outer surface of the turbine casing and the
other end portion inserted into a hole formed in the turbine
casing and being fixed to the turbine casing by forming a weld
bead on a periphery of the protruded portion, the method
including the steps of attaching the cutting unit to an end
surface of the one end portion of the radial pin via the support
unit, cutting the weld bead while moving the cutting unit along
the periphery of the radial pin, and removing the radial pin
from the turbine casing after cutting the weld bead.
[0023]
According to the method of removing the radial pin, since
the cutting unit is attached to the end surface of the pin (the
end surface of the one end portion) protruded from the surface
of the turbine casing via the support unit and the cutting of
the weld bead is performed while the cutting unit is moved along
the periphery of the radial pin, it is possible to omit an
operation for forming a through hole in the radial pin, and
significantly improve working efficiency.
In addition, the through hole is not formed in the radial
pin so that it is possible to reduce the possibility of damage
10
to the turbine casing (particularly a through hole for attaching
the radial pin) , and a small torque is sufficient for the weld
bead cutting device so that it is possible to adopt a lightweight
configuration using, e.g., an air grinder or the like. Further,
the radial pin is not ruptured so that it is possible to reuse
the radial pin.
[0024]
In a conventional method of removing a radial pin of a
steam turbine, when the turbine casing corresponds to the upper
half portion of the casing, the turbine casing (the upper half
portion of the casing) has been hoisted using a crane and placed
over a dedicated machine installed on a floor in advance, a
through hole has been formed in the radial pin from the inside
the casing by a two-stage perforation operation using the
dedicated machine, and the cutting of the weld bead has been
performed by using a cutting blade inserted into the through
hole. Further, when a plurality of radial pins are sequentially
removed, it has been necessary to hoist and reverse the turbine
casing (the upper half portion of the casing) and move a machine
installation stand and the dedicated machine in order to
displace the position of the dedicated machine for the next
radial pin to be removed.
On the other hand, when the turbine casing corresponds
to the lower half portion of the casing, a base plate has been
placed on a horizontal dividing plane of the lower half portion
11
of the casing in spanning relation, the dedicated machine has
been installed on the base plate via the machine installation
stand, and the cutting of the weld bead has been performed
according to the same procedures as those in the case of the
upper half portion of the casing. In addition, when the removal
operation of the next radial pin is started, it has been
necessary to hoist the dedicated machine using the crane to move
the dedicated machine to the position of the next radial pin
to be removed.
[0025]
In contrast to this, in the above-described method of
removing the radial pin according to the present invention,
since the cutting of the weld bead is performed with the cutting
unit attached to the end surface of the pin (the end surface
of the one end portion) protruded from the surface of the turbine
casing via the support unit, the operation can be performed from
the outside of the turbine casing so that it is not necessary
to hoist the turbine casing (the upper half portion of the
casing) and place the turbine casing over the dedicated machine
using the crane, as in the conventional case.
In addition, as described above, since the weld bead
cutting device according to the present invention is
lightweight and portable, when the removal operation of the next
radial pin is started, it is sufficient to merely carry the weld
bead cutting device to the position of the next radial pin to
12
be removed, and it is not necessary to hoist or reverse the
turbine casing (the upper half portion of the casing), or move
the machine installation stand and the dedicated machine using
the crane.
[0026]
In the above-described method of removing the radial pin,
the cutting unit preferably has a cutting blade for cutting the
weld bead on a tip side in its longitudinal direction, and, in
the step of cutting the weld bead, the weld bead is preferably
roughly cut while the cutting unit is moved inwardly in a radial
direction of the radial pin in a state where the longitudinal
direction of the cutting unit is generally in parallel with the
support shaft, and then the weld bead is preferably cut in a
state where the longitudinal direction of the cutting unit is
inclined relative to the support shaft.
[0027]
In this manner, the weld bead is roughly cut while the
cutting unit is moved inwardly in the radial direction of the
radial pin in the state where the longitudinal direction of the
cutting unit is generally in parallel with the support shaft,
and then the weld bead is cut in the state where the longitudinal
direction of the cutting unit is inclined relative to the
support shaft, whereby it is possible to speedily remove the
weld bead with high precision.
[0028]
13
According to the present invention, since there is
provided the support unit which supports the cutting unit which
cuts the weld bead on the end surface of the pin (the end surface
of the one end portion) protruded from the surface of the
structure such that the cutting unit is movable along the
periphery of the pin, it is possible to cut the weld bead without
forming the through hole in the pin, and significantly improve
working efficiency.
In addition, the through hole is not formed in the pin
so that it is possible to reduce the possibility of damage to
the structure, and a small torque is sufficient for the weld
bead cutting device so that it is possible to adopt a lightweight
configuration using, e.g., an air grinder or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029]
FIG. 1 is a cross-sectional view showing an example of
a configuration of a weld bead cutting device;
FIG. 2 is a cross-sectional view showing another example
of the weld bead cutting device;
FIG. 3 is a view showing the removal of a radial pin of
a steam turbine by using the weld bead cutting device shown in
FIGS. 1 and 2;
FIG. 4 is an enlarged view showing a portion in the
vicinity of a weld bead in each stage of FIG. 3;
14
FIG. 5 is a cross-sectional view showing a configuration
of a weld bead cutting device according to a modification;
FIG. 6 is a cross-sectional view showing an example of
a configuration of each of an angle adjustment unit and an axial
position adjustment unit; and
FIG. Visa view showing the removal of a weld bead provided
on a periphery of a radial pin in a conventional method of
removing the radial pin in which FIG. 7(a) shows an entire
turbine casing, while FIG. 7(b) shows an enlarged portion in
the vicinity of the radial pin.
MODE FOR CARRYING OUT THE INVENTION
[0030]
A description is given hereinbelow of embodiments of the
present invention with reference to the accompanying drawings.
Note that the scope of the present invention is not limited to
dimensions, materials, shapes, and relative arrangements of
constituent parts described in the embodiments unless
specifically described, and they are only explanatory examples.
[0031]
FIG. 1 is a cross-sectional view showing an example of
a configuration of a weld bead cutting device. FIG. 2 is a
cross-sectional view showing another example of the weld bead
cutting device shown in FIG. 1.
Although a description is given hereinbelow of the weld
15
bead cutting device for cutting a weld bead 4 of a radial pin
2 used for positioning an in-casing structure (a blade ring,
a dummy ring, or an internal casing) 7 of a steam turbine with
respect to a turbine casing 1, the weld bead cutting device of
the present invention is not limited to the example, and can
be widely applied to a device for cutting a weld bead of a pin
which has a portion protruded from a surface of a structure and
has the weld bead formed on a periphery of the protruded portion.
[0032]
As shown in FIG. 1, a first end portion (corresponding
to "the other end portion") 2A of the radial pin 2 is inserted
into a through hole 3 formed in the turbine casing 1, and fitted
in a concave portion 8 provided in the in-casing structure (the
blade ring, the dummy ring, or the internal casing) 7. On the
other hand, a second end portion (corresponding to "one end
portion") 2B of the radial pin 2 is protruded from an outer
surface of the turbine casing 1, and the weld bead 4 is formed
on its periphery. By the weld bead 4, the radial pin 2 is fixed
to the turbine casing 1. In addition, the weld bead 4 in a steam
turbine also plays a role of sealing the internal space of the
turbine casing 1 to prevent the passage of a fluid (steam or
air) between the inside and the outside of the turbine casing
1 via the through hole 3.
[0033]
A weld bead cutting device 10 shown in FIG. 1 includes
16
a cutting portion (a cutting unit) 12 which cuts the weld bead
4 formed on the periphery of the radial pin 2, and a support
portion (a support unit) 20 which supports the cutting portion
12 on the radial pin 2.
[0034]
The cutting portion 12 has a cutting blade 14 for cutting
the weld bead 4 on a tip side in its longitudinal direction,
and, e.g., an air grinder driven by factory air or the like can
be used as the cutting portion 12.
[0035]
The support portion 20 which supports the cutting portion
12 has a support shaft 22 which is provided to stand on an end
surface 2C of the one end portion 2B of the radial pin 2, a
coupling member 24 which couples the cutting portion 12 to the
support shaft 22, a bearing 26 which supports the coupling
member 24 such that the coupling member 24 is pivotable about
the support shaft 22, and a fitting member 28 which fits over
the one end portion 2B of the radial pin 2.
[0036]
The support shaft 22 extends through the coupling member
24 and the fitting member 28, and is screwed to a screw hole
9 provided in the end surface 2C of the one end portion 2B of
the radial pin 2.
[0037]
The screw hole 9 is preferably formed in the end surface
17
•
2C as a circle generally concentric with a circular shape of
a cross section of the radial pin 2. With this, by causing the
cutting portion 12 to pivot about the support shaft 22 together
with the coupling member 24, it is possible to move the cutting
portion 12 (the cutting blade 14) at a desired locus along the
periphery of the radial pin 2. Therefore, it is possible to
prevent damage to the turbine casing 1 during the cutting of
the weld bead 4,
[0038]
The coupling member 24 has a screw-nut system (a radial
position adjustment unit) 30 therein, and is capable of
adjusting the position of the cutting portion 12 (the cutting
blade 14) in a radial direction of the radial pin 2. With this,
in accordance with the progress of a cutting operation of the
weld bead 4, it is possible to bring the cutting blade 14 of
the cutting portion 12 into contact with the weld bead 4 at an
appropriated position constantly.
[0039]
The screw-nut system 30 has a handle 32 attached to its
end portion, and includes a feed screw 34 which extends along
the radial direction of the radial pin 2, and a feed nut 36 to
which the cutting portion 12 is attached. The feed screw 34
is held to the coupling member 24 by a bearing which is not shown
so as to be rotatable with the handle 32. According to the
screw-nut system 30, when a torque is inputted to the feed screw
18
34 via the handle 32, the cutting portion 12 moves in the radial
direction of the radial pin 2 (a "cutting portion movement
direction" shown in FIG. 1) together with the feed nut 36 as
the feed screw 34 rotates.
[0040]
The bearing 26 is provided between the coupling member
24 and the fitting member 28, and supports the coupling member
24 such that the coupling member 24 is pivotable about the
support shaft 22 relative to the fitting member 28.
Note that, since the fitting member 28 fits over the one
end portion 2B of the radial pin 2, the fitting member 28 is
basically immovable during the pivoting of the coupling member
24. Specifically, the one end portion 2B of the radial pin 2
has a polygonal shape (e.g., a hexagonal shape) having the axial
direction of the radial pin 2 as its center, the fitting member
28 has a concave portion 29 in a shape corresponding to the
polygonal shape, and the fitting member 28 is locked by the one
end portion 2B of the radial pin 2.
[0041]
In this manner, by supporting the cutting portion 12 by
using the support portion 20 including the support shaft 22,
the coupling member 24, and the bearing 26, it is possible to
cause the cutting portion 12 to pivot about the support shaft
22 together with the coupling member 24 to smoothly move the
cutting blade 14 of the cutting portion 12 along the periphery
19
of the radial pin 2. With this, it becomes easy to cut the weld
bead 4 formed on the periphery of the radial pin 2 without
damaging the turbine casing 1.
[0042]
Note that, in the example shown in FIG. 1, although the
cutting portion 12 is attached to the coupling member 24 such
that the longitudinal direction thereof is along the axial
direction of the radial pin 2 (the axial direction of the support
shaft 22), as shown in FIG. 2, the cutting portion 12 may be
attached to the coupling member 24 in a state where the cutting
portion 12 is inclined relative to the axial direction of the
radial pin 2 (the axial direction of the support shaft 22).
Herein, a weld bead cutting device 60 shown in FIG. 2 has the
same configuration as that of the weld bead cutting device 10
of FIG. 1 except for the attachment implementation (an angle)
of the cutting portion 12, and hence the description of the
components which are the same as those of the weld bead cutting
device 10 is omitted by retaining the same reference numerals.
[0043]
In addition, in terms of facilitation of the cutting
operation of the weld bead 4 using the cutting blade 14, the
cutting portion 12 is preferably attached to the coupling member
24 such that an angle a (see FIG. 2) formed by the longitudinal
direction of the cutting portion 12 and the axial direction of
the support shaft 22 is not less than 0 degree and not more than
20
60 degrees. Note that, in the weld bead cutting device 10 shown
in FIG. 1, the angle a formed by the longitudinal direction
of the cutting portion 12 and the axial direction of the support
shaft 22 is 0 degree.
[0044]
Next, a description is given of a method of removing the
radial pin 2 of the steam turbine by using the weld bead cutting
device 10 shown in FIGS. 1 and 2. FIG. 3 is a view showing the
removal of the radial pin 2 of the steam turbine. FIG. 4 is
an enlarged view showing the portion in the vicinity of the weld
bead 4 in each stage of FIG. 3.
[0045]
First, as shown in FIG. 3, the weld bead cutting device
10 is attached to the end surface 2C of the one end portion 2B
of the radial pin 2.
Specifically, as shown in FIG. 1, the coupling member 24,
the fitting member 28, and the bearing 26 are pre-assembled
together, and the cutting portion 12 is attached to the coupling
member 24 in advance. Subsequently, the one end portion 2B of
the radial pin 2 is fitted in the concave portion 2 9 of the
fitting member 28. In this state, the support shaft 22 is
inserted into through holes (not shown) provided in the coupling
member 24 and the fitting member 28, and is screwed to the screw
hole 9 provided in the one end portion 2B of the radial pin 2.
[0046]
21
#
Then, in a state where the longitudinal direction of the
cutting portion 12 is generally in parallel with the support
shaft 22, while the cutting portion 12 is moved inwardly in the
radial direction of the radial pin 2 (a direction of an arrow
of FIG. 4) , the weld bead 4 is roughly cut by causing the cutting
portion 12 (the cutting blade 14) to pivot along the periphery
of the radial pin 2. With this, most of the weld bead 4 is
removed, but the weld bead 4 having entered into a gap between
the through hole 3 of the turbine casing 1 and the one end portion
2B of the radial pin 2 remains without being removed.
[0047]
Thereafter, as shown in FIG. 3, instead of the weld bead
cutting device 10, the weld bead cutting device 60 is attached
to the end surface 2C of the one end portion 2B of the radial
pin 2. The specific attachment procedures are the same as those
in the case of the weld bead cutting device 10.
Subsequently, in a state where the longitudinal direction
of the cutting portion 12 is inclined relative to the support
shaft 22, the cutting portion 12 (the cutting blade 14) is caused
to pivot along the periphery of the radial pin 2, and the
remaining weld bead 4 is cut.
[0048]
In this manner, the weld bead 4 is roughly cut by using
the weld bead cutting device 10 while the cutting portion 12
is moved inwardly in the radial direction of the radial pin 2
22
in the state where the longitudinal direction of the cutting
portion 12 is generally in parallel with the support shaft 22,
and then the weld bead 4 is cut by using the weld bead cutting
device 60 in the state where the longitudinal direction of the
cutting portion 12 is inclined relative to the support shaft
22, whereby it is possible to speedily remove the weld bead 4
with high precision.
[0049]
Then, the radial pin 2 from which the weld bead 4 has been
completely removed is struck with a hammer or the like to be
removed from the through hole 3 of the turbine casing 1, a hook
is attached to the radial pin 2 by utilizing the screw hole 9
provided in the end surface 2C of the one end portion 2B of the
radial pin 2, and the radial pin 2 is hoisted using a crane.
In this manner, the radial pin 2 is removed from the through
hole 3 of the turbine casing 1.
[0050]
As has been described above, each of the weld bead cutting
devices 10 and 60 of the present embodiment has the cutting
portion 12 which cuts the weld bead 4 formed on the periphery
of the radial pin 2, and the support portion 20 which supports
the cutting portion 12 on the end surface 2C of the one end
portion 2B of the radial pin 2 such that the cutting portion
12 is movable along the periphery of the radial pin 2. In
addition, the support portion 20 includes the support shaft 22
23
which is provided to stand on the end surface 2C of the one end
portion 2B of the radial pin 2, the coupling member 24 which
couples the cutting portion 12 to the support shaft 22, and the
bearing 26 which supports the coupling member 24 such that the
coupling member 24 is pivotable about the support shaft 22.
[0051]
Thus, in each of the weld bead cutting devices 10 and 60,
since there is provided the support portion 20 which supports
the cutting portion 12 (the cutting blade 14) which cuts the
weld bead 4 on the end surface 2C of the radial pin 2 (the end
surface of the one end portion 2B) such that the cutting portion
12 is movable along the periphery of the radial pin 2, it is
possible to cut the weld bead 4 without forming the through hole
in the radial pin 2, and significantly improve working
efficiency.
In addition, the through hole is not formed in the radial
pin 2 so that it is possible to reduce the possibility of damage
to the turbine casing 1 (specifically, the through hole 3) , and
a small torque is sufficient for the cutting portion 12 of each
of the weld bead cutting devices 10 and 60 so that it is possible
to adopt a lightweight configuration using, e.g., an air grinder
or the like.
[0052]
In the present embodiment, the description has been given
of the method of removing the radial pin in which, after the
24
weld bead cutting device 10 is attached to the end surface 2C
of the one end portion 2B of the radial pin 2 in the beginning
and the weld bead 4 is roughly cut while the cutting portion
12 is moved inwardly in the radial direction of the radial pin
2 in the state where the longitudinal direction of the cutting
portion 12 is generally in parallel with the support shaft 22,
the weld bead cutting device 60 is attached to the end surface
2C of the one end portion 2B of the radial pin 2 instead of the
weld bead cutting device 10, the weld bead 4 is cut in the state
where the longitudinal direction of the cutting portion 12 is
inclined relative to the support shaft 22, and lastly the radial
pin 2 from which the weld bead 4 has been completely removed
is removed from the through hole 3 of the turbine casing 1.
[0053]
According to the method of removing the radial pin, since
the weld bead 4 is cut by using each of the weld bead cutting
devices 10 and 60 and attaching the cutting portion 12 to the
end surface 2C of the radial pin 2 (the end surface of the one
end portion 2B) protruded from the outer surface of the turbine
casing 1 via the support portion 20, it is possible to perform
the operation from the outside of the turbine casing 1.
In addition, since the weld bead cutting devices 10 and
60 are lightweight and portable, when the removal operation of
the next radial pin 2 is started, it is sufficient to merely
carry the weld bead cutting devices 10 and 60 to the position
25
m
of the next radial pin 2 to be removed, and it is not necessary
to hoist or reverse the turbine casing 1, or move the machine
installation stand and the dedicated machine using the crane.
[0054]
Although the embodiment of the present invention has been
described in detail thus far, the present invention is not
limited thereto, and it will be evident that various
modifications and changes may be made without departing from
the gist of the present invention,
[0055]
For example, in the embodiment described above, although
the description has been given of the example in which the
cutting portion 12 is supported on the end surface 2C of the
radial pin 2 by the support portion 20 including the support
shaft 22, the coupling member 24, the bearing 26, and the fitting
member 28, the support portion which supports the cutting
portion 12 is not limited to this example, and various
configurations thereof can be adopted as shown below.
[0056]
FIG. 5 is a cross-sectional view showing a configuration
of a weld bead cutting device according to a modification. A
weld bead cutting device 70 shown in the drawing is the same
as the weld bead cutting device 10 described in the first
embodiment except for the configuration of the support portion
which supports the cutting portion 12 so that the description
26
m
of the components which are the same as those of the weld bead
cutting device 10 is omitted by retaining the same reference
numerals.
[0057]
As shown in FIG. 5, a support portion 72 of the weld bead
cutting device 70 has the support shaft 22 which is provided
to stand on the end surface 2C of the one end portion 2B of the
radial pin 2, a sleeve 74 which is provided on the periphery
of the support shaft 22 along the support shaft 22, the coupling
member 24 which couples the cutting portion 12 to the support
shaft 22 (the sleeve 74) , and the bearings 26 which support the
coupling member 24 such that the coupling member 24 is pivotable
about the support shaft 22. According to the support portion
72 having such configuration, similarly to the support portion
20 described in the above embodiment, it is possible to smoothly
move the cutting blade 14 of the cutting portion 12 along the
periphery of the radial pin 2.
[0058]
Further, the support portion which supports the cutting
portion 12 can have any configuration as long as the support
portion can support the cutting portion 12 on the end surface
2C of the radial pin 2 such that the cutting portion 12 is movable
along the periphery of the radial pin 2. For example, a slide
bearing may be used instead of the bearing 2 6, and the bearing
26 itself may be omitted. When the bearing 26 is omitted, one
27
#
of a circular concave portion and a circular convex portion is
provided in a member which does not rotate, the other one of
the concave and convex portions is provided in a member which
rotates, and rotation is regulated by fitting the concave and
convex portions of the members to each other, whereby it is
possible to cause the cutting portion 12 to properly pivot along
a predetermined locus.
[0059]
Furthermore, in the embodiment described above, although
the description has been given of the example in which the
position of the cutting portion 12 in the radial direction of
the radial pin 2 is adjusted by the screw-nut system (the radial
position adjustment unit) 30 in the weld bead cutting device
10, there may be provided an angle adjustment unit which adjusts
an angle formed by the longitudinal direction of the cutting
portion 12 and the support shaft 22, and an axial position
adjustment unit which adjusts the position of the cutting
portion 12 in the axial direction of the support shaft 22.
[0060]
FIG. 6 is a cross-sectional view showing an example of
a configuration of each of the angle adjustment unit and the
axial position adjustment unit. As shown in the drawing, to
the feed nut 36 of the screw-nut system 30, a cutting portion
holder 82 is attached via a backing plate 80. The cutting
portion holder 82 fixes the cutting portion 12 by holding the
28
cutting portion 12 in a circular hole formed by disposing a first
plate portion 82A and a second plate portion 82B having
semicircular grooves such that the respective semicircular
grooves oppose each other, and tightening the first and second
plate portions 82A and 82B by using a pair of bolts (the axial
position adjustment unit) 84. In addition, the cutting portion
holder 82 is fixed to the backing plate 80 using the bolts 84.
The backing plate 80 is fixed to the feed nut 36 using a bolt
(the angle adjustment unit) 86.
[0061]
After the backing plate 80 is rotated about the bolt 86
by a desired angle in a state where the bolt 86 is loosened,
the bolt 86 is tightened and the cutting portion holder 82 and
the cutting portion 12 are attached to the backing plate 80,
whereby it is possible to adjust the angle formed by the
longitudinal direction of the cutting portion 12 and the support
shaft 22.
In addition, after the cutting portion 12 is moved along
its longitudinal direction by a desired amount in a state where
the bolts 84 are loosened, the bolts 84 are tightened, whereby
it is possible to adjust the position of the cutting portion
12 (the cutting blade 14) in the axial direction of the support
shaft 22.
[0062]
With this, it is possible to bring the cutting portion
29
12 into contact with the weld bead 4 at an appropriate angle
and position constantly in accordance with the progress of the
cutting operation of the weld bead 4. Further, when the
configuration is adopted in which the angle formed by the
longitudinal direction of the cutting portion 12 and the support
shaft 22 can be adjusted using the bolt 86, as described m the
above embodiment, the necessity to replace the weld bead cutting
device 10 with the weld bead cutting device 60 is obviated so
that it is possible to reliably remove the weld bead 4 by using
the single weld bead cutting device.

CLAIMS
1. A weld bead cutting device for cutting a weld bead
formed on a periphery of one end portion of a pin having the
one end portion protruded from a 'surface of a structure and the
other end portion inserted into a hole formed in the structure,
comprising:
a cutting unit which cuts the weld bead formed on the
periphery of the pin; and
a support unit which supports the cutting unit on an end
surface of the one end portion of the pin such that the cutting
unit is movable along the periphery of the pin.
2. The weld bead cutting device according to claim 1,
wherein the support unit includes:
a support'Shaft provided to stand on the end surface of
the one end portion of the pin;
a coupling member which couples the cutting unit to the
support shaft; and
a bearing which supports the coupling member such that
the coupling member is pivotable about the support shaft.
3. The weld bead cutting device according to claim 2,
wherein the support shaft is screwed to a screw hole formed in
the end surface of the one end portion of the pin, the screw
hole being a circle generally concentric with a circular shape
31

of a cross section of the pin.
4. The weld bead cutting device according to claim,
wherein
the cutting unit has a cutting blade for cutting the weld
bead on a tip side in-its longitudinal direction, and
the cutting unit is atta9hed to the coupling member such
that an angle formed by the longitudinal d*r€rction of the
cutting unit and the support shaft is not less than 0 degree
and not more than 60 degrees.
5. The weld bead cutting device according to claim,
further comprising:
an angle adjustment unit which adjusts the ailgle formed
by the longitudinal direction of the cutting unit and the
support shaft.
6. The weld bead cutting device according to claim 1,.
further comprising:
a radial position adjustment unit which adjusts a
position of the cutting unit in a radial direction of the pin.
7. The weld bead cutting device according to claim 1,
further comprising:
an axial position adjustment unit which adjusts a
32

position of the cutting unit in an axial direction of the pin. -
8. The weld bead cutting device according to claim 1,
9
wherein
the structure is a turbine casing of a steam turbine, and
the pin is a radial pin for positioning a blade ring, a
dummy ring, or an internal casing of the steam turbine with
respect to the turbine casing.
9. A method of removing a radial pin for positioning a
blade ring, a dummy ring, or an internal casing of a steam turbine
with respect to a turbine casing of the steam turbine by using
the weld bead cutting device according to claim 1, the radial
pin having one end portion protruded from an outerlsurface' of
the turbine casdng and the other end portion inserted into a
hole formed in the turbine casing and being fixed to the turbine
casing by forming a weld bead on a periphery of the protruded
portion, the method compr^ising the steps of: -
attaching the cutting unit to an end surface of the one
end portion of the radial pin via the support unit;
cutting the weld bead while moving the cutting unit along
the periphery of the radial pin; and
removing the radial pin from the turbine casing after
cutting the weld bead.
33
10. The method of removing a radial pin of a steam turbine '
according to cljaim 9, wherein
the cutting unit has a cutting blade for cutting the weld
bead on a tip side in its longitudinal direction, and
in the step of cutting the weld bead, the weld bead is
roughly cut while the cutting unit is moved inwardly in a radial
direction of the radial pin in,a state where the longitudinal
direction of the cutting unit is generally in-psftrallel with the
support shaft, and then the weld bead is cut in a state where
the longitudinal direction of the cutting unit is inclined
relative to the support shaft.