The present invention relates to a sealing fin fixing
apparatus and a sealing fin fixing method of fixing a
sealing fin to a rotor in a rotary machine.
2. Description of the Related Art
[0002]
Rotary machines represented by steam turbines and gas
turbines include a sealing fin disposed in a clearance
defined between the outer circumferential surface of a rotor
and the inner circumferential surface of a stator for
preventing a working fluid such as steam, gas, or the like
from leaking through the clearance for thereby achieving
increased performance. The sealing fin is mounted on either
the rotor or the stationary body or on both the rotor and
the stator. When a sealing fin that is mounted on the rotor
is worn on its tip end by contact with the stator, the
clearance between the stator and the sealing fin increases,
lowering the sealing performance of the sealing fin and
increasing the leakage of the working fluid. It is
necessary to restore the clearance between the stator and
the sealing fin in order to recover the reduced sealing performance.
[0003]
Sealing fins on the rotor are roughly classified into
machined sealing fins and caulked sealing fins. A machined
sealing fin is formed by cutting off an outer
circumferential portion of a rotor blank, and is inseparable
from a rotor. When the machined sealing fin is worn, since
the machined sealing fin is integral with the rotor, it is
difficult to recover the worn portion of the machined
sealing fin, and it is extremely costly to replace the rotor
in its entirety because of the wear of the machined sealing
fin. The stator may be replaced with another stator having
a smaller inside diameter to make up for the wear to the tip
end of the machined sealing fin. However, the replacing
process is not practical from the standpoints of the sealing
performance and the period required to replace the stator as
well as the cost of the process.
[0004]
On the other hand, a caulked sealing fin is separate
from a rotor and fixedly fitted in a sealing groove defined
circumferentially in the outer circumferential surface of
the rotor. The caulked sealing fin has an inner
circumferential end portion inserted in the fin groove and
caulked and securely fixed to the rotor by a caulking wire.
Even if the tip end of the caulked sealing fin is damaged by
contact with the stator, the caulked sealing fin can be
replaced with a new one. It is not necessary to machine the
rotor in replacing the caulked sealing fin, and the sealing performance is renewed to the level of the new caulked
sealing fin. Furthermore, as the sealing width of a single
caulked sealing fin can be reduced, a plurality of caulked
sealing fins can be mounted in an axially packed array on
the rotor. In addition, it is known in the art that the
caulked sealing fin undergoes small axial vibrations upon
contact with the stator when the rotary machine starts up
and shuts off. Therefore, the clearance between the caulked
sealing fin and the stator can be reduced for better sealing
performance.
[0005]
However, when a sealing fin is manually secured to a
rotor by caulking with a chisel or an air hammer, it takes
time to install the sealing fin on the rotor. It is not
rare for some steam turbines to have more than one hundred
caulked sealing fins disposed between a shaft end and a vane
depending on the number of casings and vane arrays.
Therefore, a large amount of time and labor is required to
install sealing fins manually in steam turbines.
[0006]
Various ideas have been proposed to perform caulking
processes efficiently using caulking wires. For example,
JP-2006-233971-A discloses a sealing assembly that uses a
peening tool. JP-2010-43565-A reveals a caulking device
that travels on the outer circumferential surface of a
rotor.
Prior Art Document Patent Documents
[0007]
[Patent Document 1] JP-2006-233971-A
[Patent Document 2] JP-2010-43565-A
[0008]
According to the sealing assembly disclosed in JP2006-233971-A, since a peening device hits a caulking wire
against a rotor while the rotor is rotating about its
central axis, the spots where the caulking wire is impacted
by the peening device are circumferentially spaced around
the rotor. Consequently, the distance by which the caulking
wire is pressed into a sealing groove in the rotor, i.e.,
the radial distance between the surface of the rotor and the
surface of the caulking wire, hereinafter referred to as
“press-fit distance,” tends to have circumferentially
periodic variations. Inasmuch as the pullout strength of
sealing fins is closely related to the press-fit distance,
the variations in the press-fit distance are likely to cause
variations in the pullout strength of sealing fins.
[0009]
If the variations in the pullout strength of sealing
fins are large, then when the rotor undergoes intensive
centrifugal forces while the rotary machine is in operation,
the sealing fins may possibly start pulling out of their
sealing grooves from spots where the pullout strength is
lower. Moreover, increasing the rotational speed of the
rotor for the purpose of shortening the period of time required to install the sealing fins results in a reduction
in the pullout strength of the sealing fins because the
locations where the caulking wire is hammered by the peening
device are spaced apart more widely. Furthermore, when the
pullout strength has periodic variations, when the press-fit
distance of the caulking wire is inspected at a plurality of
circumferentially spaced locations on the caulking wire, the
spots where the pullout strength is lower may possibly be
overlooked.
[0010]
In addition, when the sealing assembly disclosed in
JP-2006-233971-A is to be used, construction work has to be
done on a large scale to install the sealing assembly on a
foundation. Furthermore, various actuators including an
actuator for driving the peening device needs to be
controlled in synchronism with the rotor as it rotates. For
hitting the caulking wire that has a small width of about
few millimeters with the peening device, it is necessary to
position the sealing assembly with respect to the rotor such
that the peening device hits the caulking wire along a
trajectory exactly along the caulking wire, a task that is
difficult to achieve and time-consuming.
[0011]
The caulking device disclosed in JP-2010-43565-A also
tends to cause variations in the pullout strength of a
caulking wire as it uses a peening device as is the case
with the sealing assembly disclosed in JP-2006-233971-A.
Moreover, the caulking device disclosed in JP-2010-43565-A is set on the outer circumferential surface of a rotor and
is movable on its own on the outer circumferential surface
of the rotor as it is held at rest. Vibrations caused by
the peening device as it operates are likely to adversely
affect a trajectory along which the peening device hits the
caulking wire, tending to make the trajectory unstable or
possibly bringing the trajectory out of alignment with the
caulking wire in extreme instances.
[0012]
It is therefore an object of the present invention to
provide a sealing fin fixing apparatus and a sealing fin
fixing method of fixing a sealing fin to a rotor in a
shortened period of time to minimize variations of the
pullout strength of the sealing fin.
SUMMARY OF THE INVENTION
[0013]
To achieve the above object, there is provided,
according to the present invention, a sealing fin fixing
apparatus for fixing a sealing fin in a sealing groove
defined in an outer circumference of a rotor of a rotary
machine, including: a headstock for setting a rotor thereon;
a Z-stage movable along a Z-axis extending parallel to a
rotational shaft of the headstock; an X-stage supported on
the Z-stage and movable along an X-axis in a direction
perpendicular to the Z-axis; a tool rest supported on the Xstage; and a caulking tool mounted on the tool rest, in
which the caulking tool includes a shank mounted on the tool rest and a pressing roller rotatably supported on the shank,
the pressing roller having a rotational shaft mounted on the
tool rest in a posture parallel to the rotational shaft of
the headstock, and while the pressing roller is being held
against a caulking wire inserted, together with the sealing
fin, in the sealing groove in the rotor that is set on the
headstock, the headstock is actuated to rotate the rotor,
thereby caulking the caulking wire to fix the sealing fin to
the rotor.
[0014]
According to the present invention, it is possible to
fix the sealing fin to the rotor in a shortened period of
time to minimize variations of the pullout strength of the
sealing fin.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front elevational view schematically
illustrating a sealing fin fixing apparatus according to a
first embodiment of the present invention;
FIG. 2 is a cross-sectional view taken along line II–
II of FIG. 1;
FIG. 3 is a cross-sectional view taken along line
III–III of FIG. 2;
FIG. 4 is a cross-sectional view taken along line IV–
IV of FIG. 2; and
FIG. 5 is a side elevational view schematically
illustrating a sealing fin fixing apparatus according to a
second embodiment of the present invention.

We claim:
1. A sealing fin fixing apparatus for fixing a
sealing fin (F) in a sealing groove (G) defined in an outer
circumference of a rotor (R) of a rotary machine, the
sealing fin fixing apparatus characterized by comprising:
a headstock (2) for setting the rotor thereon;
a Z-stage (5) movable along a Z-axis extending
parallel to a rotational shaft (2a) of the headstock;
an X-stage (6) supported on the Z-stage and movable
along an X-axis in a direction perpendicular to the Z-axis;
a tool rest (7) supported on the X-stage; and
a caulking tool (8) mounted on the tool rest, wherein
the caulking tool includes a shank (8a) mounted on
the tool rest and a pressing roller (8b) rotatably supported
on the shank, the pressing roller having a rotational shaft
mounted on the tool rest in a posture parallel to the
rotational shaft of the headstock, and
while the pressing roller is being held against a
caulking wire (W) inserted, together with the sealing fin,
in the sealing groove in the rotor that is set on the
headstock, the headstock is actuated to rotate the rotor,
thereby caulking the caulking wire to fix the sealing fin to
the rotor.
2. The sealing fin fixing apparatus as claimed in
claim 1, further comprising:
a holding roller (11) for contacting the caulking
wire before the pressing roller contacts the caulking wire. 3. The sealing fin fixing apparatus as claimed in
claim 1, further comprising:
a cutting tool (9) for, in place of the caulking
tool, being mounted on the tool rest.
4. The sealing fin fixing apparatus as claimed in
claim 1, further comprising:
a measuring instrument (10) fixed to either the
caulking tool or the tool rest, for measuring an outer
diameter of the caulking wire or the sealing fin.
5. A caulking tool (8) for being mounted on a cutter
holder of a lathe, as part of a sealing fin fixing apparatus
for fixing a sealing fin (F) in a sealing groove (G) defined
in an outer circumference of a rotor (R) of a rotary
machine, the caulking tool characterized by comprising:
a shank (8a) mounted on the tool rest; and
a pressing roller (8b) rotatably supported on the
shank.
6. A sealing fin fixing method of fixing a sealing
fin (F) in a sealing groove (G) defined in an outer
circumference of a rotor (R) of a rotary machine, the method
characterized by comprising:
setting the rotor on a headstock (2) of a lathe;
installing a caulking tool (8) including a shank (8a)
and a pressing roller (8b) rotatably supported on the shank,
on a tool rest (7) of the lathe in such a posture that the
pressing roller has a rotational shaft extending parallel to
a central axis of the rotor; and
caulking a caulking wire (W) to fix the sealing fin to the rotor by actuating the headstock to rotate the rotor
while the pressing roller is being held against the caulking
wire inserted, together with the sealing fin, in the sealing
groove in the rotor that is set on the headstock.
7. The sealing fin fixing method as claimed in claim
6, further comprising:
installing a cutting tool (9) on the tool rest and
machining the sealing groove in the outer circumference of
the rotor, wherein
after the sealing groove is machined in the outer
circumference of the rotor, the cutting tool installed on
the tool rest is changed to the caulking tool, and the
caulking tool is installed on the tool rest without
dislodging the rotor from the headstock.
8. The sealing fin fixing method as claimed in claim
7, further comprising:
installing the cutting tool on the tool rest and
cutting a surface of a rotor blank fixed to the headstock,
thereby finishing an outer profile of the rotor, wherein
after the outer profile of the rotor is finished, the
sealing groove is machined in the outer circumference of the
rotor without dislodging the rotor from the headstock.
9. The sealing fin fixing method as claimed in claim
6, further comprising:
attaching a measuring instrument (10) to either the
caulking tool or the tool rest and measuring an outer
diameter of the rotor, the caulking wire, or the sealing fin
with the measuring instrument, wherein the outer diameter of the rotor, the caulking wire,
or the sealing fin is measured with the measuring instrument
without dislodging the rotor from the headstock before or
after the caulking wire is caulked.
10. The sealing fin fixing method as claimed in claim
6, wherein
rotational circumferential speed of the headstock is
constant regardless of a diameter of the rotor, in caulking
the caulking wire to fix the sealing fin to the rotor by
actuating the headstock to rotate the rotor while the
pressing roller is being held against the caulking wire
inserted, together with the sealing fin, in the sealing
groove in the rotor that is set on the headstock.
11. The sealing fin fixing method as claimed in claim
6, wherein
a procedure in which the caulking tool is held
against the caulking wire and the rotor is rotated through
one revolution is repeated a plurality of times, in caulking
the caulking wire to fix the sealing fin to the rotor by
actuating the headstock to rotate the rotor while the
pressing roller is being held against the caulking wire
inserted, together with the sealing fin, in the sealing
groove in the rotor that is set on the headstock.
12. A lathe modifying method of modifying a lathe
into a sealing fin fixing apparatus for fixing a sealing fin
(F) in a sealing groove (G) defined in an outer
circumference of a rotor (R) of a rotary machine, the method
characterized by comprising: fabricating a caulking tool (8) including a shank
(8a) and a pressing roller (8b) rotatably supported on the
shank; and
installing the caulking tool on a tool rest (7) of
the lathe in such a posture that the pressing roller has a
rotational shaft extending parallel to a central axis of the
rotor.