BURNISHING DEVICE AND BURNISHING METHOD USING IT
BACKGROUND OF THE INVENTION
The present invention relates to a burnishing device
and a burnishing method using it.
As a method for finishing a surface in order to
improve wear resistance and fatigue strength of a metal
material, burnishing is known. As a burnishing tool to be
used for the burnishing, there is a tool described in JP-
2005-288557-A (hereinafter referred to as Patent Document 1)
The burnishing tool described in Patent Document 1 is
a roller burnishing tool that includes a cylindrical shank,
a head, and a roller for compaction. The head is arranged
in the shank through a pivot shaft and pivots by work
pressing force. The burnishing tool further includes a
biasing unit, a biasing force adjusting unit, and a biasing
force converting unit. The biasing unit is arranged in the
cylindrical shank and biases in a shank axis direction. The
biasing force adjusting unit adjusts biasing force generated
by the biasing unit. The biasing force converting unit
transmits the biasing force to a head shaft and changes a
direction of the biasing force to a direction in which the
head shaft pivots. The burnishing tool controls the work
pressing force to be generated upon rolling compaction.
SUMMARY OF THE INVENTION
A part that connects turbine blades of a steam
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turbine or the like to a turbine rotor disk has a structure
in which an attachment base located on the side of the
turbine blades is engaged with an attachment base located on
the side of the turbine rotor disk. The connection part
balances centrifugal force applied to the turbine blades
upon an operation of the turbine and thus needs to have
sufficient fatigue resistance.
Although Patent Document 1 describes the fact that an
edge of the burnishing tool is pressed against an inner
surface of a cylindrical object, a unit for measuring
pressing force is not provided. If the invention described
in Patent Document 1 is applied to the part that connects
the turbine blades to the turbine rotor disk, there is a
problem that compressive residual stress is not reliably
formed on a processed part of an attachment base due to
displacement of the set attachment base or an error of a
dimension of the attachment base. Especially, for a portion
(such as the attachment base) of which the height and
inclination angle of a surface (to be processed) vary, an
error between an input position of the portion and the
actual position of the portion easily occurs. Thus, it is
likely that the portion may not be sufficiently processed by
the burnishing.
The present invention was devised to solve the
aforementioned problems, and an object of the invention is
to provide a burnishing device and a burnishing method that
enable burnishing to be reliably performed on a surface,
which is included in an object to be processed and is to be
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processed by burnishing and has a change in height and
inclination angle.
In order to solve the aforementioned problems,
configurations described in claims are used, for example.
The present specification includes multiple schemes
for solving the aforementioned problems. As an example of
the schemes, a burnishing device including a burnishing tool
having a pressing unit that rotationally presses a surface
of an object to be processed, the surface having a change in
height and inclination angle; a tool driving device
configured to move the burnishing tool; a strain sensor
configured to detect a strain amount of the burnishing tool;
and a computer configured to calculate pressing force to be
applied by the pressing unit in a normal direction of the
surface of the object to be processed, the calculation being
on the basis of the strain amount detected by the strain
sensor, calculate a correction amount of displacement of the
tool driving device in a pressing direction, the calculation
being on the basis of the calculated pressing force and
stored pressing force in advance, and output the correction
amount to the tool driving device.
According to the invention, the pressing force to be
applied by the pressing unit in the normal direction of the
surface of the object to be processed is calculated on the
basis of the strain amount of the burnishing tool, the
pressing unit presses the surface by the calculated pressing
force, and the burnishing processing can be reliably
performed on the surface, which is included in the object to
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be processed and has a change in height and inclination
angle. As a result, the service life of the object to be
processed can be increased.
Challenges, configurations, and effects other than
those described above are clarified by the following
description of embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view partially illustrating
turbine blades of a steam turbine to be processed using a
burnishing method by a burnishing device according to each
embodiment of the invention.
Fig. 2 is an enlarged perspective view of a part
indicated by a symbol A in Fig. 1, which shows a connection
of turbine blades and a turbine rotor disk in the steam
turbine.
Fig. 3 is an outline configuration diagram
illustrating a burnishing device according to a first
embodiment of the invention.
Fig. 4 is an enlarged perspective view illustrating a
roller of a burnishing tool that constitutes a part of the
burnishing device (illustrated in Fig. 3) according to the
first embodiment of the invention.
Fig. 5 is a diagram describing a burnishing process
to be performed by the burnishing device according to the
first embodiment of the invention.
Fig. 6 is a diagram illustrating the relationship
between deflection of a beam and displacement of an arm upon
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the burnishing performed by the burnishing device according
to the first embodiment of the invention.
Fig. 7 is a diagram illustrating the relationship
between pressing force and friction force that are applied
to an inclined surface (to be processed) and shearing force
and axial force that are applied to the beam upon the
burnishing performed by the burnishing device according to
the first embodiment of the invention.
Fig. 8 is a characteristic diagram illustrating
relationships of balance between the pressing force, the
friction force, the shearing force of the beam, and the
axial force of the beam upon the burnishing performed by the
burnishing device according to the first embodiment of the
invention.
Fig. 9 is a characteristic diagram illustrating the
relationship between the pressing force and the deflection
of the beam upon the burnishing performed by the burnishing
device according to the first embodiment of the invention.
Fig. 10 is a flowchart of a burnishing method to be
performed by the burnishing device according to the first
embodiment of the invention.
Fig. 11 is a diagram illustrating displacement of a
chucking of the burnishing tool that constitutes the part of
the burnishing device according to the first embodiment of
the invention.
Fig. 12 is a characteristic diagram illustrating the
relationship between the shearing force of the beam and the
deflection of the beam upon the burnishing performed by the
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burnishing device according to the first embodiment of the
invention.
Fig. 13 is a diagram illustrating a display screen of
a display unit that displays processing records of the
burnishing method performed by the burnishing device
according to the first embodiment of the invention.
Fig. 14 is a characteristic diagram illustrating the
relationship between pressing force and deflection of the
beam upon burnishing performed by the burnishing device
according to a second embodiment of the invention.
Fig. 15 is a flowchart of a burnishing method to be
performed by the burnishing device according to the second
embodiment of the invention.
Fig. 16 is a characteristic diagram illustrating the
relationship between shearing force of the beam and the
deflection of the beam upon the burnishing performed by the
burnishing device according to the second embodiment of the
invention.
Fig. 17 is a diagram illustrating a burnishing device
according to a third embodiment of the invention and the
relationship between pressing force and friction force that
are applied to an inclined surface (to be processed) and
shearing force and axial force that are applied to an axial
force shaft upon the burnishing.
Fig. 18 is a diagram describing the burnishing to be
performed on a blade attachment base of a turbine blade by
the burnishing device according to the third embodiment of
the invention.
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Fig. 19 is a characteristic diagram illustrating
relationships of balance between the pressing force, the
friction force, the shearing force of an axial force shaft,
and the axial force of the axial force shaft upon the
burnishing performed by the burnishing device according to
the third embodiment of the invention.
DESCTIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, a burnishing device and a burnishing
method according to first to third embodiments of the
invention are described with reference to the accompanying
drawings.
First, the configuration of a steam turbine to be
processed using the burnishing method by the burnishing
device according to the first to third embodiments of the
invention is described with reference to Figs. 1 and 2.
Fig. 1 is a perspective view partially illustrating
turbine blades of the steam turbine to be processed using
the burnishing method by the burnishing device. Fig. 2 is
an enlarged perspective view of a part indicated by a symbol
A in Fig. 1, which shows a connection of turbine blades and
a turbine rotor disk in the steam turbine.
In Fig. 1, the turbine 100 includes a rotor shaft 101,
the turbine rotor disk 102, and the plurality of turbine
blades 103. The turbine rotor disk 102 is attached to an
outer circumferential portion of the rotor shaft 101. The
turbine blades 103 are connected to an outer circumferential
portion of the turbine rotor disk 102 at intervals.
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As illustrated in Fig. 2, the part 104 that connects
the turbine rotor disk 102 to the turbine blades 103 has
such a structure: rotor attachment bases 105 of the turbine
rotor disk 102 are engaged with blade attachment bases 106
of the turbine blades 103, attachment bases 105 and 106 both
having Christmas tree shape in cross section.
During an operation of the turbine, the connected
rotor shaft 101 is rotated by causing the turbine blades 103
to receive .steam, and a generator (not illustrated)
generates power by rotational driving force of the rotor
shaft 101. In this case, centrifugal force acts on the
rotating turbine blades 103 and is supported by the
connection part 104 having the engagement structure.
Thereby, stress is concentrated at groove bottom portions
107 of the rotor attachment bases 105 and groove bottom
portions 108 of the blade attachment bases 106. Thus
generated locally high stress may cause damage such as a
fatigue crack or stress corrosion cracking under long-term
use.
As a technique for suppressing such damage,
burnishing, which suppresses the occurrence or progress of a
crack or the like by forming a compressive residual stress
layer on a surface, is effective. The burnishing has
advantages that the formed compressive residual stress layer
is deep, a processed surface is smooth, and the processing
cost is low.
First Embodiment
Next, the burnishing device according to the first
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embodiment of the invention is described with reference to
Figs. 3 to 6.
Fig. 3 is an outline configuration diagram
illustrating the burnishing device according to the first
embodiment of the invention. Fig. 4 is an enlarged
perspective view illustrating a roller of a burnishing tool
that constitutes a part of the burnishing device
(illustrated in Fig. 3) according to the first embodiment of
the invention. Fig. 5 is a diagram describing a burnishing
process to be performed by the burnishing device according
to the first embodiment of the invention. Fig. 6 is a
diagram illustrating the relationship between deflection of
a beam and displacement of an arm upon the burnishing
performed by the burnishing device according to the first
embodiment of the invention. Reference numerals that are
illustrated in Figs. 3 to 6 and the same as those
illustrated in Figs. 1 and 2 indicate the same parts as
those illustrated in Figs. 1 and 2, and a detailed
description thereof is omitted. In Figs. 3, 5, and 5, a
direction in which the burnishing tool is inserted is Xdirection,
a direction in which the groove bottom portions
of the rotor attachment bases extend is Y-direction, and a
direction in which the burnishing tool presses the rotor
attachment base is Z-direction.
The present embodiment describes an example in which
a surface processed inside of the rotor attachment base 105
of the rotor disk is subjected to burnishing. Prior to
burnishing, the surface processed is formed in a narrow
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inner surface shape and has a change in height and
inclination angle.
In Fig. 3, the burnishing device includes a
burnishing tool 1 and a tool driving device 2. The
burnishing tool 1 forms a compressive residual stress layer
on an object (rotor attachment bases 105) to be processed.
The tool driving device 2 moves the burnishing tool 1 in X-,
Y-, and Z-directions.
The burnishing tool 1 uses a beam scheme in
consideration of access to the groove bottom portions 107 of
the rotor attachment bases 105 having the narrow inner
surface. In the beam scheme, deflection reaction force of a
beam 11 is used to press an edge of the burnishing tool 1
against the surface to be processed. The burnishing tool 1
includes the beam 11, a fixing portion 12, and a roller 13.
The beam 11 can be inserted in a narrow portion of the rotor
attachment base 105. The fixing portion 12 is arranged at
one edge of the beam 11 in a longitudinal direction of the
beam 11. The roller 13 serves as a pressing unit that
presses the surface (to be processed) of the object to be
processed. As illustrated in Fig. 4, the roller 13 is
capable of rotating around an axial direction (X-direction)
parallel to the longitudinal direction of the beam 11.
The tool driving device 2 includes a base portion 21,
a Y-axis stage 22, a Y-axis driving device 23, a holding
portion 24, an arm 25, an X-axis driving device 26, an arm
holding portion 27, a Z-axis driving device 28, and a tool
gripping portion 29. The Y-axis stage 22 is capable of
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moving in Y-direction relative to the base portion 21. The
Y-axis driving device 23 moves the Y-axis stage 22. The
holding portion 24 stands on the Y-axis stage 22. The arm
25 is attached to the holding portion 24 and capable of
moving in X-direction. The X-axis driving device 26 moves
the arm 25 relative to the holding portion 24 in X-direction.
The arm holding portion 27 holds the arm 25 and is capable
of moving relative to the holding portion 24 in Z-direction.
The Z-axis driving device 28 moves the arm holding portion
27 relative to the holding portion 24 in Z-direction. The
tool gripping portion 29 is arranged at an edge of the arm
25.
The tool gripping portion 29 has a chucking hole 29a.
The burnishing tool 1 is fixed to the chucking hole 29a by
inserting the fixing portion 12 of the burnishing tool 1 in
the chucking hole 29a and bolting the fixing portion 12.
The burnishing tool 1 is moved in X-direction by the
X-axis driving device 26 and inserted in a gap between the
rotor attachment bases 105. Next, the burnishing tool 1 is
moved in Z-direction by the Z-axis driving device 28 and the
roller 13 of the burnishing tool 1 is pressed against the
groove bottom portion 107 of the rotor attachment base 105.
While the roller 13 is pressed against the groove bottom
portion 107, the burnishing tool 1 is moved in Y-direction
by the Y-axis driving device 23 and the roller 13 is moved
in a groove direction (Y-direction) while rotationally
pressing the groove bottom portion 107 (or processing one
line), as illustrated in Fig. 4.
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When the roller 13 finishes moving from one end to
the other end of the groove bottom portion 107 in Ydirection
while pressing the surface to be processed, the
roller 13 is moved in X-direction by a predetermined pitch p
by the X-axis driving device 26 as illustrated in Fig. 5.
In addition, the Z-axis driving device 28 is driven to cause
the roller 13 to be pressed against the groove bottom
portion 107 again and the roller 13 is moved from the other
end to one end of the groove bottom portion 107 in Ydirection
while pressing the groove bottom portion 107. By
repeating this operation, the burnishing is completed on the
overall groove bottom portion 107.
In this case, local plastic deformation occurs at a
contact portion of the surface (to be processed) by pressing
force F applied to the surface (to be processed) in a normal
direction of the surface by the roller 13, and compressive
residual stress is formed at the contact portion. The
pressing force F applied to the surface (to be processed) in
the normal direction correlates with the magnitude of the
compressive residual stress formed by the burnishing.
Necessary allowable pressing force Ft is determined
in advance to obtain predetermined compressive residual
stress or higher, and deflection v of the beam 11 is
controlled by the tool driving device 2 so that the pressing
force F is not lower than the allowable pressing force Ft.
A configuration that is provided to control the
deflection v of the beam 11 and effect of the configuration
are described below.
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beam 11 is represented by the following Equation (1) using
displacement u of the arm 25 of the tool driving device 2 in
Z-direction (pressing direction).
V = u - uO (x) (1)
In Equation (1), uO is standard displacement of the
arm 25 in Z-direction when the roller 13 starts contacting
the surface (to be processed) of the object (rotor
attachment base 105) to be processed. In Equation (1), uO
is a function of a coordinate x of the groove bottom portion
107 in X-direction.
In the present embodiment, therefore, the pressing
force F to be applied by the roller 13 is measured to
control the deflection v of the beam 11.
Returning to Fig. 3, strain sensors 14a and 14b are
arranged on upper and lower surfaces (both edges of the beam
11 in a shearing direction upon the burnishing) of the beam
11 in the vicinity of the fixing portion 12. The strain
sensors 14a and 14b are connected to the computer 3. The
strain sensors 14a and 14b detect the strain amounts of the
beam 11 and output detection signals corresponding to the
amounts of the strains to the computer 3.
The computer 3 is connected to a tool controller 4
that drives the X-axis driving device 26, Y-axis driving
device 23, and Z-axis driving device 28 of the tool driving
device 2 and controls the position of the arm 25. In
addition, the computer 3 is connected to an input unit 5, a
display unit 6, and an alarm unit 7. The input unit 5 is a
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keyboard or the like and provides a command to display data
measured upon the burnishing and provides a various commands
(from a user) such as processing requirements for the
burnishing and a control value of displacement u of the arm
25 of the tool driving device 2. The display unit 6
displays the data measured upon the burnishing and the like.
The alarm unit 7 provides an alarm sound.
The computer 3 includes an input/output (I/O) unit 31,
a storage unit 32, and a calculator 33. The storage unit 32
stores various characteristic diagrams and various set
values. The calculator 33 calculates, on the basis of the
detection values received from the strain sensors 14a and
14b and the characteristic diagrams, the pressing force F to
be applied by the roller 13 to the surface (to be processed)
in the normal direction of the surface to be processed. The
calculator 33 compares the calculated pressing force F with
a set value and calculates a correction amount 5u of the
displacement u of the arm 25 in the pressing direction on
the basis of the calculated pressing force F, the
characteristic diagrams, and the set value.
The storage unit 32 stores a characteristic diagram
(refer to Fig. 8 described later) indicating relationships
of balance between the pressing force F, friction force,
shearing force of the beam 11, and axial force of the beam
11 upon the burnishing in order for the calculator 33 to
calculate the pressing force F. In addition, the storage
unit 32 stores the allowable pressing force Ft that is the
set value to be used for the comparison with the calculated
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€ pressing force F and determination of whether the calculated
pressing force F is equal to or larger than pressing force
that enables predetermined compressive residual stress to be
formed. Furthermore, the storage unit 32 stores a
characteristic diagram indicating the relationship between
the pressing force and the deflection of the beam 11 and
stores allowable deflection vt (of the beam 11)
corresponding to the allowable pressing force Ft on the
characteristic diagram in order for the calculator 33 to
calculate the correction amount 5u of the displacement u of
the arm 25 (refer to Fig. 9 described later).
In addition, the storage unit 32 stores the
processing requirements (for the burnishing) input from the
input unit 5, the result of calculating the pressing force F
by the calculator 33, and the like.
The calculator 33 acquires the detection signals of
the strain sensors 14a and 14b, calculates the pressing
force F on the basis of the detection signals of the strain
sensors 14a and 14b and the characteristic diagram
(illustrated in Fig. 8 described later) stored in the
storage unit 32, and outputs the result of the calculation
to the storage unit 32 and the display unit 6. In addition,
the calculator 33 determines whether or not the calculated
pressing force F is lower than the allowable pressing force
Ft stored in the storage unit 32. If the calculator 33
determines that the calculated pressing force F is lower
than the allowable pressing force Ft, the calculator 33
outputs an alarm command signal to the alarm unit 7,
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calculates the correction amount 5u (of the displacement u
of the arm 25) causing the pressing force F to be equal to
or higher than the allowable pressing force Ft, and outputs
the result of calculating the correction amount 5u to the
display unit 6. Furthermore, the calculator 33 outputs, to
the tool controller 4, a correction displacement command to
change the displacement u of the arm 25 by the correction
amount 5u on the basis of the correction amount 6u (of the
displacement u of the arm 25) input from the input unit 5.
The input/output unit 31 receives the detection
signals of the strain sensors 14a and 14b and a command
signal of the input unit 5. In addition, the input/output
unit 31 outputs the result (received from the calculator 33)
of calculating the pressing force F to the display unit 6,
outputs the alarm command signal received from the
calculator 33 to the alarm unit 7, outputs the result
(received from the calculator 33) of calculating the
correction amount 6u of the displacement u of the arm 25 to
the display unit 6, and outputs the correction displacement
command received from the calculator 33 to the tool
controller 4.
Next, a specific method for calculating the pressing
force F (to be applied by the roller 13) by the calculator
33 on the basis of values measured by the strain sensors 14a
and 14b is described with reference to Figs. 7 and 8.
Fig. 7 is a diagram illustrating the relationship
between the pressing force and the friction force that are
applied to the inclined surface (to be processed) and the
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shearing force and the axial force that are applied to the
beam upon the burnishing performed by the burnishing device
according to the first embodiment of the invention. Fig. 8
is a characteristic diagram illustrating the relationships
of balance between the pressing force, the friction force,
the shearing force of the beam, and the axial force of the
beam upon the burnishing performed by the burnishing device
according to the first embodiment of the invention.
Reference numerals and symbols that are illustrated in Figs.
7 and 8 and the same as those illustrated in Figs. 1 to 6
indicate the same parts as those illustrated in Figs. 1 to 6,
and a detailed description thereof is omitted.
The shearing force W and axial force B of the beam 11
that are illustrated in Fig. 7 are calculated from the
following Equations (2) and (3) using strain amounts 8a and
8b measured by the strain sensors 14a and 14b, respectively.
W = (sb - 8a) / 2 • E -Z/L ••• (2)
B = (8a + 8b) / 2 • E • A ••• (3)
In Equations (2) and (3), E is a Young's modulus of
the beam 11, Z is a section modulus of the beam 11, A is a
cross-sectional area of the beam 11, and L is a distance
between the roller 13 and the strain sensors 14A and 14b.
At an edge portion of the beam 11, the pressing force
F applied by the roller 13 to the surface to be processed in
the normal direction of the surface to be processed, the
friction force f applied in the tangential direction of the
surface to be processed, the shearing force W of the beam 11,
and the axial force B of the beam 11 are balanced. When the
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inclination angle of the surface to be processed is 0
(absolute value), the following Equations (4) to (6) are
established on the basis of balance of force acting in
vertical and horizontal directions.
FcosG + fsinG = W ••• (4)
FsinG - fcosG = B ••• (5)
f = min{|j,F, FtanG} ••• (6)
In Equation (6), |a. is a coefficient of friction.
When the inclination angle G of the surface to be
processed is small, the shearing force W of the beam 11 is
generated on the basis of the deflection v of the beam 11,
the shearing force W and the pressing force F and the
friction force f are balanced, and the axial force B of the
beam 11 is 0. In this case, since the roller 13 does not
slide on the surface to be processed and the forces are
balanced, f4.F > FtanG and the friction force f is equal to
FtanG.
On the other hand, if the inclination angle 0 of the
surface to be processed is large, horizontal force of only
the pressing force F, the friction force f, and the shearing
force W of the beam 11 is not balanced, the roller 13 tries
to slide on the surface to be processed and the axial force
B is applied to the beam 11. In this case, since the roller
13 tries to slide on the surface to be processed, \iF < FtanG
and the friction force f is equal to |J,F.
The relationships of Equations (4) to (6) can be
represented by the characteristic diagram illustrated in Fig.
8. In Fig. 8, the ordinate indicates the ratio F/W of the
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pressing force F applied by the roller 13 to the shearing
force W of the beam 11, and the abscissa indicates the ratio
B/W of the axial force B of the beam 11 to the shearing
force W of the beam 11. In Fig. 8, a solid line A, a broken
line B, and a dotted line C are characteristic curved lines
obtained in the cases where the respective coefficients (J, of
friction are 0.15, 0.3, and 0.6. Here, an appropriate
coefficient ^ of friction is selected on the basis of
results measured by a separate examination.
Since the shearing force W and the axial force B are
calculated using Equations (2) and (3) from the values
measured by the strain sensors 14a and 14b, the ratio F/W
indicated by the ordinate is calculated using the
characteristic curved line A, B or C selected on the basis
of the result of examining the coefficient fx of friction
from the ratio B/W indicated by the abscissa and determined
by the calculated axial force B and the shearing force W.
The pressing force F can be calculated from the ratio F/W.
If the axial force B of the beam 11 is 0, the ratio
F/W indicated by the ordinate is not uniquely determined,
and a value (plot in Fig. 8) on a curved line is used in
order to estimate a low ratio F/W for safety. In this case,
if the coefficient |J, of friction is 0.6, an error of the
ratio F/W indicated by the ordinate is up to 14%.
In this manner, the pressing force F can be
calculated without measuring the inclination angle 6 for the
burnishing to be performed on the object (to be processed)
of which the inclination angle 9 of the surface (to be
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processed) such as the rotor attachment base 105 varies.
Next, a specific method for calculating the
correction amount 6u of the displacement u of the arm 25 by
the calculator 33 is described with reference to Fig. 9.
Fig. 9 is a characteristic diagram illustrating the
relationship between the pressing force and the deflection
of the beam upon the burnishing performed by the burnishing
device according to the first embodiment of the invention.
In Fig. 9, the ordinate indicates the pressing force F
applied by the roller 13, and the abscissa indicates the
deflection v of the beam 11. A characteristic curved line A
illustrated in Fig. 9 indicates the relationship between the
pressing force F and the deflection v of the beam when a
condition that causes the ratio F/W in Fig. 8 to be smallest
is selected.
In Fig. 9, the allowable pressing force Ft and the
allowable deflection vt corresponding to the allowable
pressing force Ft are set values to be used to obtain the
predetermined compressive residual stress.
Even if the standard displacement uO varies by the
maximum variation 6u0 during the time when one line of the
groove bottom portion 107 of the rotor attachment base 105
is processed, initial pressing force Fs and initial
deflection vs corresponding to the initial pressing force Fs
are set so that the pressing force F applied by the roller
13 is maintained at the allowable pressing force Ft or
higher.
The initial pressing force Fs is a standard value to
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be used to determine a start position of the displacement u
of the arm 25 for the processing of one line.
A variation in the standard displacement uO during
the processing of one line occurs due to rotational
displacement of the rotor attachment base 105 in Z-direction
upon setting of the rotor attachment base 105 and an error
of dimensions of the rotor attachment base 105. For example,
an initial value of the maximum variation 5u0 of the
standard displacement uO is set to 0.5 mm. When the
pressing force F applied by the roller 13 is lower than the
allowable pressing force Ft and the burnishing processing is
performed again, the maximum variation 5u0 is changed on the
basis of the correction value 5u of the displacement u of
the arm 25.
The allowable pressing force Ft, the allowable
deflection vt, the initial pressing force Fs, the initial
deflection vs, and the characteristic diagram are stored in
the storage unit 32.
In Fig. 9, the minimum deflection vmin is calculated
from the minimum pressing force Fmin that is lower than the
allowable pressing force Ft and among pressing force F
measured during the time when one line of the rotor
attachment base 105 is processed in the groove direction.
The correction amount 5u of the displacement u of the arm 25
is calculated according to the following Equation (7) using
the minimum deflection vmin, the initial deflection vs, and
the maximum variation 5u0 of the standard displacement uO.
5u = (vs - vmin) - 5uO ••• (7)
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In this manner, when the displacement u of the arm 25
is changed by the correction amount 5u, the pressing force F
becomes equal to or higher than the allowable pressing force
Ft, as is apparent from Fig. 9.
The characteristic curved line A illustrated in Fig.
9 indicates the relationship between the pressing force F
and the deflection v when the condition that causes the
ratio F/W indicated in the characteristic diagram of Fig. 8
to be smallest is selected. Since the shearing force W is
in proportion to the deflection v, the ratio F/v is also
smallest. The pressing force F calculated from the
characteristic curved line A is set to a low value for
safety.
Next, a burnishing method that is performed by the
burnishing device according to the first embodiment of the
invention is described with reference to Figs. 3 to 6 and 8
to 12.
Fig. 10 is a flowchart of the burnishing method to be
performed by the burnishing device according to the first
embodiment of the invention. Fig. 11 is a diagram
illustrating displacement of a chucking of the burnishing
tool that constitutes a part of the burnishing device
according to the first embodiment of the invention. Fig. 12
is a characteristic diagram illustrating the relationship
between the shearing force of the beam and the deflection of
the beam upon the burnishing performed by the burnishing
device according to the first embodiment of the invention.
Reference numerals and symbols that are illustrated in Figs.
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10 to 12 and the same as those illustrated in Figs. 1 to 9
indicate the same parts as those illustrated in Figs. 1 to 9,
and a detailed description thereof is omitted. In Fig. 10,
the direction in which the burnishing tool is inserted is Xdirection,
the direction in which the groove bottom portions
of the rotor attachment bases extend is Y-direction, and the
direction in which the burnishing tool presses the rotor
attachment base is Z-direction.
As illustrated in Fig. 10, shearing force WO that is
higher than the maximum shearing force Wmax estimated to be
applied to the beam 11 upon the burnishing processing is
applied to the beam 11 before the burnishing processing (in
step SI) .
The maximum shearing force Wmax is shearing force
applied to the beam 11 due to the maximum variation of the
standard displacement uO during the time when one line of
the groove bottom portion 107 illustrated in Fig. 3 is
processed in the groove direction (Y-direction).
When shearing force that is equal to or higher than a
certain level is applied to the beam 11, the chucking is
displaced in the burnishing tool 1 inserted in and fixed to
the chucking hole 29a of the tool gripping portion 29, as
illustrated in Fig. 11. In Fig. 11, the burnishing tool 1
indicated by a two-dot chain line is in a state in which the
chucking is not displaced, and the burnishing tool 1
indicated by a solid line is in a state in which the
chucking is displaced.
If the shearing force WO that is higher than the
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maximum shearing force Wmax estimated to be applied to the
beam 11 upon the burnishing processing is applied to the
beam 11 in advance and the chucking of the burnishing tool 1
is displaced, further displacement of the chucking during
the burnishing processing can be suppressed by the
processing performed by the burnishing tool 1 in the state
in which the chucking is displaced.
If the shearing force WO is applied to the beam 11 in
advance and the chucking of the burnishing tool 1 is not
displaced, shearing force that is equal to or higher than
the shearing force WO is not applied to the beam 11 during
the processing, and it is considered that the chucking of
the burnishing tool 1 is not displaced.
It is, therefore, possible to suppress a reduction in
the pressing force F to a value lower than the allowable
pressing force Ft due to displacement of the chucking of the
burnishing tool 1 during the processing.
Next, a method for determining the maximum shearing
force Wmax of the beam 11 is described with reference to Fig,
12.
Fig. 12 is a characteristic diagram illustrating the
relationship between the shearing force of the beam 11 and
the deflection of the beam 11 upon the burnishing performed
by the burnishing device according to the first embodiment
of the invention. In Fig. 12, the ordinate indicates the
shearing force W of the beam 11, and the abscissa indicates
the deflection v of the beam 11. A solid line A illustrated
in Fig. 12 is a characteristic curved line indicating the
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relationship between the deflection of the beam and the
shearing force of the beam when the ratio B/W is 0 and
causes the ratio F/W to be smallest in Fig. 8.
It is assumed that the variation in the standard
displacement uO during the time when one line is processed
is in a range of ±0.5 mm. In this case, the maximum shearing
force Wmax is determined so that the deflection v is equal
to or larger than the allowable deflection vt while the
variation in the standard displacement uO is in the range of
±0.5 mm. In this case, the maximum variation 5u0 in the
standard displacement uO is set to an initial value of 0.5
mm.
Since the characteristic curved line A illustrated in
Fig. 12 indicates the relationship between the deflection of
the beam and the shearing force of the beam when the ratio
B/W is 0 and causes the ratio F/W to be smallest in Fig. 8,
the maximum shearing force Wmax (of the beam) calculated
from the characteristic curved line A is set to a high value
for safety.
Returning to Fig. 10, the X-axis driving device 26 of
the tool driving device 2 illustrated in Fig. 3 is driven to
move the beam 11 in X-direction. The edge of the beam 11 is
inserted in a gap between the rotor attachment bases 105,
and the roller 13 is set at an X-directional processing
start position at which the groove bottom portion 107 of the
rotor attachment base 105 starts to be processed (in step
S2) .
Next, the Z-axis driving device 28 is driven to move
25
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the beam 11 in Z-direction (pressing direction) and cause
the roller 13 to press the groove bottom portion 107 (in
step S3) . When the roller 13 presses the groove bottom
portion 107, the beam 11 is deflected, and the strain
sensors 14a and 14b detect strain amounts and output the
strain amounts to the calculator 33, as illustrated in Fig.
6. Every time the strain sensors 14a and 14b detect the
strain amounts after step S3, the strain sensors 14a and 14b
output the strain amounts to the calculator 33.
The calculator 33 acquires the strain amounts
detected by the strain sensors 14a and 14b, calculates the
pressing force F to be applied by the roller 13 on the basis
of the amounts of the strains and the characteristic diagram
(illustrated in Fig. 8) stored in the storage unit 32, and
outputs the result of calculating the pressing force F to
the display unit 6 (in step S4). Thus, the display unit 6
displays the pressing force F.
The displacement u of the arm 25 in Z-direction is
set so that the pressing force F applied by the roller 13 is
equal to the initial pressing force Fs (in step S5). As
described above, the initial pressing force Fs is set so
that even when the standard displacement uO varies by the
maximum variation 5u0 (the initial maximum variation is 0.5
mm), the pressing force F applied by the roller 13 is
maintained at the allowable pressing force Ft or higher.
While the displacement u of the arm 25 is maintained
in the state in which the pressing force F is equal to the
initial pressing force Fs, the Y-axis driving device 23 is
26
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driven to cause the roller 13 to process one line from one
end to the other end of the groove bottom portion 107 in Ydirection
(groove direction) (in step S6), as illustrated in
Fig. 4. During the time when the line is processed, the
deflection v of the beam 11 and the pressing force F applied
by the roller 13 vary with the variation in the standard
displacement uO.
The calculator 33 acquires the strain amounts
detected by the strain sensors 14a and 14b, calculates the
pressing force F on the basis of the strain amounts and the
characteristic diagram (illustrated in Fig. 8) stored in the
storage unit 32, and outputs the result of calculating the
pressing force F to the storage unit 32 and the display unit
6 (in step S7). Thus, the pressing force F applied upon the
processing of the line is stored in the storage unit 32 and
displayed by the display unit 6.
After the processing of the line is completed, the
calculator 33 determines whether or not the pressing force F
applied upon the processing of the line and stored in the
storage unit 32 is lower than the allowable pressing force
Ft stored in the storage unit 32 in advance (in step S8).
If the pressing force F is lower than the allowable pressing
force Ft, the process proceeds to step S9. If the pressing
force F is not lower than the allowable pressing force Ft,
the process proceeds to step S13.
If the pressing force F is lower than the allowable
pressing force Ft (Yes in step S8), the calculator 33
outputs the alarm command signal to the alarm unit 7 (in
27
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step S9) . Thus, the alarm unit 7 provides the alarm sound.
The alarm sound can notify the user that the pressing force
F applied upon the processing of the line is lower than the
allowable pressing force Ft.
In addition, the calculator 33 calculates the
correction amount 6u of the displacement u of the arm 25
from the characteristic diagram illustrated in Fig. 9 and
outputs the result of calculating the correction amount 5u
to the display unit 6 (in step S9). Thus, the correction
amount 5u of the displacement u of the arm 25 is displayed
by the display unit 6.
Specifically, the calculator 33 calculates the
correction amount 5u on the basis of: the minimum pressing
force Fmin that is among pressing force F applied upon the
processing of the line and stored in the storage unit 32 and
lower than the allowable pressing force Ft; the
characteristic diagram indicating the relationship between
the pressing force and the deflection of the beam and stored
in the storage unit 32 in advance; the initial deflection vs
in the storage unit 32 in advance; and the maximum variation
5u0 (initial value of 0.5 mm) of the standard displacement
uO in the storage unit 32 in advance (refer to Fig. 9).
After the calculation of the correction amount 5u, the
maximum variation 6u0 is changed to a variation of (5u0 + 5u)
The initial deflection vs and the initial pressing force Fs
that are indicated in the characteristic diagram illustrated
in Fig. 9 are changed on the basis of the change in the
maximum variation 6u0. Specifically, the initial deflection
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vs and the initial pressing force Fs are increased by an
increase in the maximum variation 5u0.
Next, the correction amount 5u displayed on the
display unit 6 is input to the computer 3 from the input
unit 5 (in step SIO).
The calculator 33 acquires the correction amount 6u
from the input unit 5 and controls the tool driving device 2
so that the displacement u of the arm 25 is equal to a value
of (u + 6u) (in step Sll). Specifically, the calculator 33
outputs, on the basis of the correction amount 5u input from
the input unit 5, the correction displacement command to
change the displacement u of the arm 25 by the correction
amount 5u to the tool controller 4 and drives the Z-axis
driving device 28 through the tool controller 4 so that the
displacement u of the arm 25 is equal to the value of (u +
6u) .
While the displacement u of the arm 25 is maintained
at the value of (u + 6u), the Y-axis driving device 23 is
driven so that the same line is processed again from the
other end to the one end in the direction opposite to the
direction of step S6 (in step S12).
The process returns to step S7, and the calculator 33
acquires strain amounts detected by the strain sensors 14a
and 14b, calculates the pressing force F, and outputs the
result of calculating the pressing force F to the storage
unit 32 and the display unit 6 (in step S7) . Thus, the
pressing force F applied upon the reprocessing of the line
is stored in the storage unit 32 and displayed on the
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display unit 6.
Next, after the line is reprocessed in step S12, the
calculator 33 determines whether or not the pressing force F
applied upon the reprocessing of the line and stored in the
storage unit 32 is lower than the allowable pressing force
Ft stored in the storage unit 32 in advance (in step S8).
If the pressing force F is not lower than the
allowable pressing force Ft (No in step S8), the X-axis
driving device 26 is driven to shift the roller 13 by a
predetermined pitch p in X-direction as illustrated in Fig.
5 and set the roller 13 in order to process the next line in
the opposite direction (in step S13). In this case, the
roller 13 is set in order to prepare to process the next
line. In the present embodiment, the roller 13 is shifted
by the pitch p in X-direction upon the completion of the
processing of each of lines from one end to the other end of
the line in Y-direction, and each of the lines is processed
in Y-direction from the other end to one end of the line so
that the overall groove bottom portion 107 is processed by
the burnishing processing.
Next, it is determined whether or not the roller 13
has reached at an X-directional processing end position at
which the processing is completed (in step S14). If the
roller 13 has yet to reach the X-directional processing end
position (No in step S14), the process returns to step S3,
and the next line is processed by repeating the
aforementioned procedure. On the other hand, if the roller
13 reaches the X-directional processing end position (Yes in
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^
step S14), the processing is completed.
The initial pressing force Fs to be set in step S5
for the next line varies for the following two cases. The
initial pressing force Fs to be set in the case where the
all answers to step S8 for the processing of previous lines
are negative (or in the case where all the previous lines
are not reprocessed) is different from the initial pressing
force Fs to be set in the case where an answer to step S8
for the processing of at least one previous line is positive
(or in the case where at least one previous line is
reprocessed).
If all the previous lines are not reprocessed, the
initial pressing force Fs to be set in step S5 for the next
line is equal to the initial pressing force Fs set in step
S5 for the previous lines.
On the other hand, if at least one of the previous
line is reprocessed, the initial pressing force Fs to be set
in step S5 for the processing of the next line is equal to
the initial pressing force Fs changed in step S9 for the
processing of the previous line.
As described above, the burnishing can be performed
on the surface (to be processed), which is included in the
object to be processed and of which the height and
inclination angle vary, without measuring the inclination
angle 9, while a part that is insufficiently pressed is not
left.
In steps S9 to Sll, the correction amount 6u
calculated by the calculator 33 is output to the display
31
^
unit 6, displayed on the display unit 6, and input to the
computer 3 from the input unit 5, and the calculator 33
outputs the correction displacement command to the tool
controller 4 on the basis of the input correction amount 5u
and controls the displacement u of the arm 25 through the
tool controller 4. The correction amount 5u calculated by
the calculator 33, however, may not be input to the computer
3 from the input unit 5, and the calculator 33 may output
the correction displacement command to the tool controller 4
on the basis of the result of calculating the correction
amount 5u and control the displacement u of the arm 25
through the tool controller 4.
Besides, in the aforementioned example, steps SI to
S3, S5, S6, SIO, and S12 to S14 are manually performed, but
may be automatically performed by control of the computer.
Next, results of outputting processing records
displayed on the display unit that constitutes a part of the
burnishing device according to the first embodiment of the
invention are described with reference to Fig. 13.
Fig. 13 is a diagram illustrating a display screen of
the display unit that displays the processing records of the
burnishing method performed by the burnishing device
according to the first embodiment of the invention.
The display unit 6 displays the pressing force F
applied by the roller 13 on X- and Y-coordinates upon the
processing, while the displayed pressing force F is
distinguished by colors indicating the magnitude of the
pressing force F. Thus, the user can clearly confirm that a
32
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part that is insufficiently pressed does not exist.
The standard displacement uO and deflection v at both
ends in Y-direction, the number of times of reprocessing, a
processing direction, the predetermined pitch p, and a
processing speed are also displayed for each of processed
lines. Thus, a processing state can be checked in detail
when necessary.
As described above, according to the burnishing
device according to the first embodiment of the invention
and the burnishing method to be performed by the burnishing
device, the pressing force F to be applied by the pressing
unit 13 in the normal direction of the surface (to be
processed) of the object 105 to be processed is calculated
on the basis of the strain amounts of the burnishing tool 1,
and the pressing unit 13 presses the surface (to be
processed) on the basis of the calculated pressing force F.
The burnishing processing can be reliably performed on the
surface (to be processed), which is included in the object
105 to be processed and which has a change in height and
inclination angle. As a result, the service life of the
object 105 to be processed can be increased.
According to the present embodiment, since the
displacement u of the arm 25 is controlled on the basis of
the pressing force F calculated on the basis of the strain
amounts detected by the strain sensors 14a and 14b, it is
not necessary that information of the shape of the rotor
attachment base 105 be input to the tool driving device 2.
In addition, even if a detailed shape of an object to be
33
^^ll
processed is not clear, the object can be processed.
Further, according to the present embodiment, the
relationships of balance between the pressing force F
applied by the roller 13 to the surface (to be processed) of
which the inclination angle 9 varies, the friction force f
applied in the tangential direction of the surface to be
processed, the shearing force W of the beam 11, and the
axial force B of the beam 11 are calculated as the
characteristic relationships between the pressing force F,
the shearing force W of the beam 11, and the axial force B
of the beam 11, as illustrated in Fig. 8. Thus, the
pressing force F to be applied by the roller 13 in the
normal direction of to the surface (to be processed) of
which the inclination angle 9 varies can be calculated
without measuring the inclination angle 9.
According to the present embodiment, the burnishing
tool 1 uses a beam scheme in which the roller 13 presses the
surface using the deflection reaction force of the beam.
Thus, the burnishing tool 1 can reliably perform the
burnishing processing on the object (such as the rotor
attachment base 105) that is to be processed having a narrow
inner surface.
According to the present embodiment, since the
measured pressing force F is distinguished by the colors
indicating the magnitude of the pressing force F and
displayed, the quality of the burnishing can be easily
managed in detail when necessary.
Second Embodiment
34
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Next, the burnishing device according to the second
embodiment of the invention is described with reference to
Figs. 3, 8, and 14.
Fig. 14 is a characteristic diagram illustrating the
relationship between the pressing force F and deflection of
the beam upon the burnishing performed by the burnishing
device according to the second embodiment of the invention.
Reference symbols that are illustrated in Fig. 14 and the
same as those illustrated in Figs. 1 to 13 indicate the same
parts as those illustrated in Figs. 1 to 13, and a detailed
description thereof is omitted.
The second embodiment is different in the following
point from the first embodiment. In the first embodiment,
the burnishing is performed while the displacement u of the
arm 25 is fixed, and if a processing failure is detected,
the displacement u of the arm 25 is corrected on the basis
of the measured pressing force F and the burnishing is
performed again. In the second embodiment, however, the
displacement u of the arm 25 is sequentially corrected on
the basis of the pressing force F measured during the
processing.
The computer 3 that constitutes a part of the
burnishing device according to the second embodiment
includes the input/output (I/O) unit 31, the storage unit 32,
and the calculator 33 (refer to Fig. 3). The storage unit
32 stores various characteristic diagrams and various set
values in advance. The calculator 33 calculates the
pressing force F to be applied by the roller 13 in the
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normal direction of the surface (to be processed) on the
basis of values detected by the strain sensors 14a and 14b
and the characteristic diagrams and calculates a deflection
correction amount 5 of the deflection v of the beam 11 on
the basis of the calculated pressing force F, the
characteristic diagrams, and the set values.
The storage unit 32 stores the characteristic diagram
indicating the relationships of balance between the pressing
force, the friction force, the shearing force of the beam 11,
and the axial force of the beam 11 upon the burnishing, in
order for the calculator 33 to calculate the pressing force
F (refer to Fig. 8). In addition, in order for the
calculator 33 to calculate the correction amount 5v of the
deflection v of the beam 11, the storage unit 32 stores a
characteristic diagram indicating the relationship between
the pressing force and the deflection of the beam 11, the
allowable pressing force Ft, allowable deflection vt (of the
beam 11) corresponding to the allowable pressing force Ft on
the characteristic diagram, target pressing force Fm set
from the characteristic diagram in order for the pressing
force F to be applied by the roller 13 to be equal to or
higher than the allowable pressing force Ft, and a target
control value vm corresponding to the target pressing force
Fm and provided for the deflection v (refer to Fig. 14
described later).
The calculator 33 acquires the detection signals of
the strain sensors 14a and 14b, calculates the pressing
force F to be applied by the roller 13 on the basis of the
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detection signals of the strain sensors 14a and 14b and the
characteristic diagram (illustrated in Fig. 8) stored in the
storage unit 32, and outputs the result of calculating the
pressing force F to the storage unit 32 and the display unit
6. In addition, the calculator 33 sequentially calculates
the deflection correction amount 6v of the deflection v of
the beam 11 on the basis of the calculated pressing force F
and the target pressing force Fm stored in the storage unit
32 so that the pressing force F is equal to the target
pressing force Fm, as described later. Then, the calculator
33 sequentially outputs the correction displacement command
to change the displacement u of the arm 25 by the deflection
correction amount 5v to the tool controller 4.
Next, a specific method for calculating the
correction amount to be used to sequentially correct the
displacement u of the arm 25 during the processing is
described with reference to Fig. 14.
Fig. 14 is a characteristic diagram illustrating the
relationship between the pressing force and the deflection
of the beam upon the burnishing performed by the burnishing
device according to the second embodiment of the invention.
In Fig. 14, the ordinate indicates the pressing force F to
be applied by the roller 13, and the abscissa indicates the
deflection v of the beam 11. In Fig. 14, a solid line A is
a characteristic curved line indicating the relationship
between the pressing force and the deflection of the beam
when a condition that causes the ratio F/W (illustrated in
Fig. 8) to be smallest is selected.
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In Fig. 14, the allowable pressing force Ft and the
allowable deflection vt corresponding to the allowable
pressing force Ft are values set to obtain the predetermined
compressive residual stress.
If the maximum deviation from a target value of the
deflection v is indicated by 6vmax, the target pressing
force Fm and the target control value Ann of the deflection v
corresponding to the target pressing force Fm are set in
order to control the deflection v of the beam 11 so that the
pressing force F to be applied by the roller 13 is
maintained at the allowable pressing force Ft or higher.
The allowable pressing force Ft, the allowable
deflection vt, the target pressing force Fm, the target
control value vm, and the characteristic diagram are stored
in the storage unit 32.
To calculate the correction amount of the
displacement u of the arm 25, the difference 5F (= F - Fm)
obtained by subtracting the target pressing force Fm from
the pressing force F calculated on the basis of the
detection signals of the strain sensors 14a and 14b and the
characteristic diagram illustrated in Fig. 8 is calculated.
Next, the deflection correction amount 5v (of the deflection
V of the beam 11) that corresponds to the difference 6F is
calculated. The deflection correction amount 5v is equal to
the correction amount of the displacement u of the arm 25.
As is apparent from Fig. 14, when the displacement u
of the arm 25 is changed by the deflection correction amount
6v, the deflection v of the beam 11 becomes equal to the
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target control value vm.
The characteristic curved line A illustrated in Fig.
14 indicates the relationship between the pressing force F
and the deflection v when the condition that causes the
ratio F/W to be smallest is selected on the characteristic
diagram illustrated in Fig. 8. Since the shearing force W
is in proportion to the deflection v, the ratio F/v is also
smallest. Thus, the pressing force F calculated from the
characteristic curved line A is set to a low value for
safety.
Next, a burnishing method to be performed by the
burnishing device according to the second embodiment of the
invention is described with reference to Figs. 3, 8, and 14
to 16.
Fig. 15 is a flowchart of the burnishing method to be
performed by the burnishing device according to the second
embodiment of the invention. Fig. 16 is a characteristic
diagram indicating the relationship between the shearing
force of the beam and the deflection of the beam upon the
burnishing performed by the burnishing device according to
the second embodiment of the invention. Reference symbols
that are illustrated in Figs. 15 and 16 and the same as
those illustrated in Figs. 1 to 14 indicate the same parts
as those illustrated in Figs. 1 to 14, and a detailed
description thereof is omitted. In Fig. 15, the direction
in which the burnishing tool is inserted is X-direction, the
direction in which the groove bottom portions of the rotor
attachment bases extend is Y-direction, and the direction in
39
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which the burnishing tool is pressed against the rotor
attachment base 105 is Z-direction.
As illustrated in Fig. 15, the shearing force WO that
is higher than the maximum shearing force Wmax estimated to
be applied to the beam 11 upon the processing is applied to
the beam 11 before the burnishing processing (in step S21).
A method for determining the maximum shearing force
Wmax of the beam 11 is described below with reference to Fig.
16.
Fig. 16 is a characteristic diagram illustrating the
relationship the shearing force of the beam and the
deflection of the beam upon the burnishing performed by the
burnishing device according to the second embodiment of the
invention. In Fig. 16, the ordinate indicates the shearing
force W of the beam, and the abscissa indicates the
deflection v of the beam 11. In Fig. 16, a solid line A is
a characteristic curved line indicating the relationship
between the shearing force of the beam and the deflection of
the beam under the condition that the ratio B/W is 0 and
causes the ratio F/W to be smallest.
The maximum shearing force Wmax is determined as the
shearing force to be applied to the beam 11 when the
deflection v of the beam 11 is estimated to be shifted by up
to a value 5vmax from the target control value vm.
Since the characteristic curved line A illustrated in
Fig. 16 indicates the relationship between the shearing
force of the beam and the deflection of the beam under the
condition that the ratio B/W is 0 and causes the ratio F/W
40
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to be smallest in Fig. 8, the maximum shearing force Wmax
(of the beam) calculated from the characteristic curved line
A is set to a high value for safety.
Returning to Fig. 15, in the same manner as the first
embodiment, the beam 11 illustrated in Fig. 3 is moved in Xdirection,
the edge of the beam 11 is inserted in a gap
between the rotor attachment bases 105, and the roller 13 is
set on the groove bottom portion 107 of the rotor attachment
base 105 at the X-directional processing start position at
which the processing starts to be performed (in step S22).
In addition, the beam 11 is moved in Z-direction (pressing
direction) and the roller 13 is pressed against the groove
bottom portion 107 (in step S23). When the roller 13
presses the groove bottom portion 107, the beam 11 is
deflected, and the strain sensors 14a and 14b detect the
strain amounts of the beam 11 and output the strain amounts
to the calculator 33.
In the same manner as the first embodiment, the
calculator 33 acquires the strain amounts detected by the
strain sensors 14a and 14b, calculates the pressing force F
on the basis of the strain amounts and the characteristic
diagram (illustrated in Fig. 8) stored in the storage unit
32, and outputs the result of calculating the pressing force
F to the display unit 6 (in step S24) . Thus, the pressing
force F is displayed on the display unit 6.
The displacement u of the arm 25 in Z-direction is
set so that the pressing force F to be applied by the roller
13 is equal to the target pressing force Fm (in step S25).
41
0 As described above, the target pressing force Fm is set so
that the pressing force F applied by the roller 13 can be
maintained at the allowable pressing force Ft or higher even
if the deflection v of the beam 11 is shifted by up to the
value 5vmax from the target control value vm.
The roller 13 is moved on the groove bottom portion
107 in Y-direction (groove direction) and processes the
groove bottom portion 107 (in step S26). During the
processing, the deflection v of the beam 11 and the pressing
force F applied by the roller 13 change with a variation in
the standard displacement uO.
In the same manner as the first embodiment, the
calculator 33 acquires the strain amounts detected by the
strain sensors 14a and 14b, calculates the pressing force F
on the basis of the strain amounts and the characteristic
diagram (illustrated in Fig. 8) stored in the storage unit
32, and outputs the result of calculating the pressing force
F to the storage unit 32 and the display unit 6 (in step
S27) . Thus, the pressing force F is stored in the storage
unit 32 and displayed on the display unit 6.
During the processing, the calculator 33 calculates
the deflection correction amount 5v of the deflection v of
the beam 11 from the pressing force F and the characteristic
diagram illustrated in Fig. 14 (in step S28). Specifically,
the calculator 33 calculates the difference 5F (= F - Fm)
between the calculated pressing force F and the target
pressing force Fm stored in the storage unit 32 and
calculates the correction amount 5v of the deflection v of
42
the beam 11 on the basis of the difference 6F and the
characteristic diagram indicating the relationship between
the pressing force and the deflection of the beam and stored
in the storage unit 32 (refer to Fig. 14).
After the calculation of the deflection correction
amount 5v, the calculator 33 controls the tool driving
device 2 so that the displacement u of the arm 25 is equal
to a value of (u + 5v) (in step S29), Specifically, the
calculator 33 outputs, to the tool controller 4 on the basis
of the calculated deflection correction amount 5v, a
correction displacement command to change the displacement u
of the arm 25 by the deflection correction amount 5v and
drives the Z-axis driving device 28 through the tool
controller 4 so that the displacement u of the arm 25 is
equal to the value of (u + 5v).
Next, it is determined whether or not the roller 13
has reached an end to be processed in Y-direction (in step
S30) . If the roller 13 has yet to reach the end to be
processed in Y-direction, the process returns to step S27.
If the roller 13 has reached the end to be processed in Ydirection,
the process proceeds to step S31.
If the roller 13 has yet to reach the end to be
processed in Y-direction (No in step S30), the processing in
Y-direction is continuously performed by causing the process
to return to step S26 and repeating the aforementioned
procedure until the roller 13 reaches the end to be
processed in Y-direction.
In this manner, the calculator 33 sequentially
43
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calculates the pressing force F on the basis of the strain
amounts detected by the strain sensors 14a and 14b,
calculates the correction amount 5v of the deflection v of
the beam 11 on the basis of the result of calculating the
pressing force F, and sequentially controls the displacement
u of the arm 25 on the basis of the deflection correction
amount 5v so that the displacement u of the arm 25 is equal
to the value of (u + 6v) during the processing of one line.
Thus, the displacement u of the arm 25 is sequentially
controlled so that the pressing force F applied by the
roller 13 is maintained at the target pressing force Fm. In
other words, the processing in Y-direction is progressed
while feedback control is performed so as to maintain the
pressing force F at the target pressing force Fm.
When the roller 13 reaches the end to be processed in
Y-direction (Yes in step S30), the roller 13 is shifted by
the predetermined pitch p in X-direction and set to process
the next line in the opposite direction (in step S31). In
this case, the roller 13 is set in order to prepare to
process the next line. In the present embodiment, the
roller 13 is shifted by the pitch p in X-direction upon the
completion of the processing of each of the lines in Ydirection,
and the lines are processed in the opposite
direction so that the overall groove bottom portion 107 is
processed by the burnishing.
Next, it is determined whether or not the roller 13
has reached the X-directional processing end position at
which the processing is completed (in step S32). If the
44
^
roller 13 has yet to reach the X-directional processing end
position at which the processing is completed (No in step
S32), the process returns to step S23, and the next line is
processed by repeating the aforementioned procedure. If the
roller 13 has reached the X-directional processing end
position at which the processing is completed (Yes in step
S32), the processing is completed.
In the aforementioned example, steps S21 to S23, S25,
S26, S31, and S32 are manually performed, but may be
automatically performed by control of the computer.
As described above, the burnishing device and the
burnishing method performed by the burnishing device
according to the second embodiment can obtain effects that
are the same as those obtained in the first embodiment.
According to the present embodiment, since the
displacement u of the arm 25 is sequentially corrected
during the processing of one line so that the pressing force
F applied by the roller 13 is maintained at the target
pressing force Fm during the processing of one line, a step
of reprocessing a line due to insufficiency of the pressing
force F applied by the roller 13 is not necessary, and the
time for the processing can be reduced. In addition, it is
possible to prevent the roller 13 from excessively pressing
the object 105 to be processed and prevent the object 105 to
be processed from being damaged due to the processing.
Third Embodiment
Next, a burnishing device according to a third
embodiment of the invention is described with reference to
45
^
Figs. 17 to 19.
Fig. 17 is a diagram illustrating the burnishing
device according to the third embodiment of the invention
and the relationship between the pressing force and the
friction force that are applied to the inclined surface to
be processed and shearing force and axial force that are
applied to an axial force shaft upon the burnishing. Fig.
18 is a diagram describing the burnishing performed on a
blade attachment base of a turbine blade by the burnishing
device according to the third embodiment of the invention.
Fig. 19 is a characteristic diagram indicating relationships
of balance between the pressing force, the friction force,
the shearing force of the axial force shaft, and the axial
force of the axial force shaft upon the burnishing by the
burnishing device according to the third embodiment of the
invention. Reference numerals and symbols that are
illustrated in Figs. 17 to 19 and the same as those
illustrated in Figs. 1 to 16 indicate the same parts as
those illustrated in Figs. 1 to 16, and a detailed
description thereof is omitted.
While the burnishing tool 1 that constitutes a part
of the burnishing device according to the first embodiment
uses deflection reaction force of the beam and presses the
edge of the tool against the object to be processed in the
first embodiment, a burnishing tool 50 (illustrated in Fig.
17) that is included in the burnishing device according to
the third embodiment of the invention uses axial force to
press an edge of the tool against the object to be processed
46
^
in the third embodiment.
The burnishing tool 50 includes the axial force shaft
51, a fixing portion 52, a roller 53, and a spring mechanism
54 for displacement absorption. The fixing portion 52 is
arranged at one end of the axial force shaft 51 in a
longitudinal direction of the axial force shaft 51. The
roller 53 is arranged on a surface of the other end of the
axial force shaft 51 in the longitudinal direction of the
axial force shaft and serves as a pressing unit that presses
the surface (to be processed) of the object to be processed.
The spring mechanism 54 is arranged in the axial force shaft
51. The burnishing tool 50 uses the axial force of the axial
force shaft 51 to cause the roller 53 to press the surface
to be processed.
The roller 53 is capable of rotating around an axial
direction perpendicular to the longitudinal direction of the
axial force shaft 51.
The spring mechanism 54 has a function of using a
spring 55 included in spring mechanism 54 to absorb a
variation in the height of the surface to be processed
during the processing, preventing the pressing force F
applied by the axial force shaft 51 from excessively varying,
and stabilizing the pressing force F.
Strain sensors 56a and 56b are arranged on upper and
lower surfaces (both end portions of the axial force shaft
51 in a shearing direction during the burnishing) of a
central portion in the longitudinal direction of the axial
force shaft 51.
47
^
In the present embodiment, as illustrated in Fig. 18,
the burnishing can be performed on the object (such as the
blade attachment base 106 of the turbine blade 103), which
is to be processed and in which the burnishing tool 50 can
be inserted in the same direction as the pressing direction.
Next, a specific method for calculating the pressing
force to be applied by the roller 53 from values measured by
the strain sensors 56a and 56b is described with reference
to Figs. 17 to 19.
In the present embodiment, a method for pressing the
surface (to be processed) using the axial force of the axial
force shaft 51 is used instead of the deflection reaction
force of the beam 11 that constitutes a part of the
burnishing device according to the first embodiment, and the
following equations for calculating the pressing force F
from values measured by the strain sensors 56a and 56b are
used, unlike the first embodiment.
The axial force Bs of the shaft 51 and the shearing
force Ws of the shaft 51 are calculated according to the
following Equations (8) and (9) using strain amounts sa, sb
measured by the strain sensors 56a and 56b.
Bs = (8a + 8b) / 2 • Es • As •" (8)
Ws = (sa - sb) / 2 • Es • Zs/Ls ••• (9)
In Equations (8) and (9), Es is a Young's modulus of
the axial force shaft 51, Zs is a section modulus of the
axial force shaft 51, As is a cross-sectional area of the
axial force shaft 51, and Ls is a distance between an edge
of the roller 53 and the strain sensors 56a and 56b.
48
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At an edge portion of the axial force shaft 51, the
pressing force F applied by the roller 53 in the normal
direction of the surface to be processed, the friction force
f applied in the tangential direction of the surface to be
processed, the axial force Bs of the shaft 51, and the
shearing force Ws of the shaft 51 are balanced. When the
inclination angle of the surface to be processed is
indicated by 9 (absolute value), the following Equations
(10) to (12) are established on the basis of balance of
force acting in the vertical and horizontal directions.
FcosG + fsine = Bs ••• (10)
FsinG - fcosG = Ws ••• (11)
f = min{|j,F, FtanS} •" (12)
In Equation (12), |i is a coefficient of friction.
If the inclination angle 0 of the surface to be
processed is small, a vertical force component of the
pressing force F and the friction force f are balanced and
the shearing force Ws of the shaft 51 is 0. In this case,
since the roller 53 does not slide on the surface to be
processed and the force is balanced, \xF > FtanG and the
friction force f is FtanG.
On the other hand, if the inclination angle G of the
surface to be processed is large, the vertical force
components of the pressing force F and the friction force f
are not balanced, the roller 53 tries to slide on the
surface to be processed, and the shearing force Ws of the
shaft 51 occurs. In this case, since the roller 53 tries to
slide on the surface to be processed, \iF < FtanG and the
49
^
friction force f is [iF.
The relationships of Equations (10) to (12) can be
represented as the characteristic diagram illustrated in Fig.
19. In Fig. 19, the ordinates indicates the ratio F/Bs of
the pressing force F applied by the roller 53 to the axial
force Bs of the shaft 51, and the abscissa indicates the
ratio Ws/Bs of the shearing force Ws of the shaft 51 to the
axial force Bs of the shaft 51. In Fig. 19, a solid line A,
a broken line B, and a dotted line C are characteristic
curved lines obtained in the cases where the coefficient \x
of friction are 0.15, 0.3, 0.6, respectively. An
appropriate coefficient \x of friction is selected on the
basis of results measured by a separate examination.
The axial force Bs of the shaft 51 and the shearing
force Ws of the shaft 51 are calculated using Equations (8)
and (9) on the basis of the values measured by the strain
sensors 56a and 56b. Thus, the ratio F/Bs (indicated by the
ordinate) is calculated from the ratio Ws/Bs (indicated by
the abscissa) determined by the axial force Bs and shearing
force Ws that are calculated using a characteristic curved
line that is selected on the basis of the results of
examining the coefficient \i of friction from among the
characteristic curved lines A, B, and C indicated in the
characteristic diagram illustrated in Fig. 19. The pressing
force F can be calculated from the ratio F/Bs.
If the shearing force Ws of the shaft 51 is 0, the
ratio F/Bs is not uniquely determined. Thus, a value (plot
in Fig. 19) on a curved line is used in order to estimate a
50
^
low value for safety. In this case, an error of the ratio
F/Bs (indicated by the ordinate) is up to 14% even when the
coefficient |a of friction is 0.6.
In the present embodiment, the pressing force F can
be calculated without measuring the inclination angle 0 for
the burnishing performed on the object (to be processed) of
which the inclination angle 0 of the surface (to be
processed) (such as the blade attachment base 106) varies.
For the procedure of the burnishing method performed
in the present embodiment, the burnishing method used in the
first and second embodiments can be used. In this case,
since the axial force Bs of the shaft 51 is used to press
the surface to be processed, the axial force Bs of the shaft
51 is used for a variation in the pressing direction of the
burnishing tool, instead of the shearing force W of the beam
11. Note that the deflection reaction force of the beam is
used to press the surface to be processed in the first and
second embodiments.
As described above, the burnishing device according
to the third embodiment of the invention uses the method for
pressing the surface using the axial force of the axial
force shaft 51. Thus, the burnishing processing can be
reliably performed on a surface (to be processed) of an
object (such as the blade attachment base 106 of the turbine
blade 103) in which the burnishing tool can be inserted in
the same direction as the pressing direction, while the
height and inclination angle of the surface to be processed
vary.
51
^
others
Although the first embodiment describes the example
in which the rotor attachment base 105 of the rotor disk 102
is used as the object to be processed, the blade attachment
base 106 of the turbine blade 103 may be used as the object
to be processed.
In addition, although the first to third embodiments
describe the example in which the rotor attachment base 105
of the rotor disk 102 and the blade attachment base 106 of
the turbine blade 103 are processed, an object that is to be
processed and has a surface which has a change in height and
inclination angle may be processed. The burnishing devices
according to the first to the third embodiment are effective
to process, for example, a device that is a bearing housing
of a vehicle part or the like and has a corner portion in
order to improve the strength of the device.
Although the roller is used as a pressing unit in
each of the first to third embodiments, it is sufficient if
the pressing unit forms a compressive residual stress layer
on an object to be processed, and a ball may be used as the
pressing unit.
In addition, it is sufficient if the tool driving
device 2 according to the first to third embodiments can
control the burnishing tool in at least X-, Y- and Zdirections.
It is to be noted that the present invention is not
limited to the aforementioned embodiments, but covers
various modifications. While, for illustrative purposes.
52
^h
those embodiments have been described specifically, the
present invention is not necessarily limited to the specific
forms disclosed. Thus, partial replacement is possible
between the components of a certain embodiment and the
components of another. Likewise, certain components can be
added to or removed from the embodiments disclosed.
Note also that some or all of the aforementioned
components, functions, processors, and the like can be
implemented by hardware such as an integrated circuit or the
like. Alternatively, those components, functions, and the
like can be implemented by software as well. In the latter
case, a processor can interpret and execute the programs
designed to serve those functions. The programs, associated
data tables, files, and the like can be stored on a
stationary storage device such as a memory, a hard disk, and
a solid state drive (SSD) or on a portable storage medium
such as an integrated circuit card (ICC), an SD card, and a
DVD.
Further note that the control lines and information
lines shown above represent only those lines necessary to
illustrate the present invention, not necessarily
representing all the lines required in terms of products.
Thus, it can be assumed that almost all the components are
in fact interconnected.
53

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6DEL13
What is claimed is
1 3 NOV 2013
1. A burnishing device comprising:
a burnishing tool having a pressing unit that
rotationally presses a surface of an object to be processed,
the surface having a change in height and inclination angle;
a tool driving device configured to move the
burnishing tool;
a strain sensor configured to detect a strain amount
of the burnishing tool; and
a computer configured to
calculate pressing force to be applied by the
pressing unit in a normal direction of the surface of the
object to be processed, the calculation being on the basis
of the strain amount detected by the strain sensor,
calculate a correction amount of displacement
of the tool driving device in a pressing direction, the
calculation being on the basis of the calculated pressing
force and stored pressing force in advance, and
output the correction amount to the tool
driving device.
2. The burnishing device according to claim 1,
wherein the computer includes:
a storage unit configured to store
a characteristic diagram indicating
relationships of balance between the pressing force to be
applied by the pressing unit during burnishing, friction
54
ORIGINAL • py p -
^ force acting in a tangential direction of the surface of the
object to be processed, shearing force of the burnishing
tool, and axial force of the burnishing tool,
allowable pressing force enabling predetermined
compressive residual stress to be formed, and 1 7 Mnw OAlT
a characteristic diagram indicating
relationships between the pressing force to be applied by
the pressing unit and deflection of the burnishing tool; and
a calculator configured to
calculate the pressing force on the basis of
the strain amount and the characteristic diagram indicating
the relationships of the balance,
compare the calculated pressing force with the
allowable pressing force,
calculate, if the calculated pressing force is
lower than the allowable pressing force, the correction
amount on the basis of the characteristic diagram indicating
the relationship between the pressing force to be applied by
the pressing unit and the deflection of the burnishing tool
and the minimum pressing force lower than the allowable
pressing force, and
output the correction amount to the tool
driving device.
3. The burnishing device according to claim 1,
wherein the computer includes:
a storage unit configured to store
a characteristic diagram indicating
55
^
ORIGINAL ; 3 5 4 6 DEL 1 3
relationships of balance between the pressing force to be
applied by the pressing unit during burnishing, friction
force acting in a tangential direction of the surface of the
object to be processed, shearing force of the burnishing
tool, and axial force of the burnishing tool,
1 3 NOV 7m
allowable pressing force enabling predetermmea
compressive residual stress to be formed,
a characteristic diagram indicating
relationships between the pressing force to be applied by
the pressing unit and deflection of the burnishing tool, and
target pressing force to be used for the
pressing force applied by the pressing unit to maintain at
the allowable pressing force or higher; and
a calculator configured to
calculate the pressing force on the basis of
the strain amount and the characteristic diagram indicating
the relationships of the balance,
calculate the correction amount on the basis
of the characteristic diagram indicating the relationship
between the pressing force to be applied by the pressing
unit and the deflection of the burnishing tool, the
calculated pressing force, and the target pressing force,
and
output the correction amount to the tool
driving device.
4. The burnishing device according to claim 2 or 3,
wherein the burnishing tool includes:
56
ORIGINAL 3346f5Ei-i3
a beam capable of being inserted in a narrow portion
of the object to be processed; and | 2 II/M. -.
• 5IVOV 2013
the pressing unit arranged on an edge of the beam and
capable of rotating around an axial direction parallel to a
longitudinal direction of the beam.
5. The burnishing device according to claim 2 or 3,
wherein the burnishing tool includes:
an axial force shaft; and
the pressing unit arranged on an edge of the axial
force shaft and capable of rotating around an axial
direction perpendicular to a longitudinal direction of the
axial force shaft.
6. The burnishing device according to claim 1,
wherein:
the tool driving device is driven to correct, on the
basis of the calculated correction amount, displacement in a
direction in which the surface of the object to be processed
is pressed upon the next processing.
7. The burnishing device according to claim 1,
wherein:
the computer outputs a control command signal to the
tool driving device so that the calculated pressing force is
equal to the stored pressing force in advance.
8. A burnishing method to be performed by a
57
^
ORIGINAL ; S 3 4 6 ^^L J 5
burnishing device, the burnishing device comprising:
a burnishing tool having a pressing unit that f 2 MOl/ OAiv
rotationally presses a surface of an object to be processed,
the surface having a change in height and inclination angle,
a tool driving device configured to move the
burnishing tool,
a strain sensor configured to detect a strain amount
of the burnishing tool, and
a computer configured to
calculate pressing force to be applied by the
pressing unit in a normal direction of the surface of the
object to be processed, the calculation being on the basis
of the strain amount detected by the strain sensor,
calculate a correction amount of displacement
of the tool driving device in a pressing direction, the
calculation being on the basis of the calculated pressing
force and stored pressing force in advance, and
output the correction amount to the tool
driving device, the method comprising the steps of:
causing the pressing unit to press the surface of
the object to be processed and moving the pressing unit so
that the pressing force applied by the pressing unit is
equal to predetermined pressing force;
rotationally moving the pressing unit in a
direction in which the surface of the object to be processed
is processed;
calculating the pressing force to be applied by
the pressing unit on the basis of the strain amount detected
58
' fi
ORICINAL
•
:o346Da23
by the strain sensor during the rotational pressing of the
pressing unit in the processing direction; I 3 f^Q]/ Onil
calculating the correction amount on the basis of
the calculated pressing force and the stored pressing force;
and
controlling the tool driving device so that the
displacement of the tool driving device in the pressing
direction is corrected on the basis of the calculated
correction amount.
9. The burnishing method according to claim 8,
wherein:
the step of calculating the correction amount is
performed if the calculated pressing force is lower than the
stored pressing force.
10. The burnishing method according to claim 8,
wherein:
the step of correcting the displacement of the tool
driving device in the pressing direction is sequentially
performed during the step of rotationally moving the
pressing unit in the processing direction.
11. A burnishing device, substantially as herein
described with reference to accompanying drawings and
examples.
12. A burnishing method to be performed by a
59
ORIGINAL , ^ ^ .^
rein described burnishing device, substantially as herein described wwiitthh
reference to accompanying drawings and examples.