U.S. patent application number 12/225157 was filed with the patent office on 2009-10-15 for removing method of hard coating film.
This patent application is currently assigned to OSG CORPORATION. Invention is credited to Yasuo Fukui, Hiroyuki Hanyu.
Application Number | 20090255805 12/225157 |
Document ID | / |
Family ID | 38580832 |
Filed Date | 2009-10-15 |
United States Patent
Application |
20090255805 |
Kind Code |
A1 |
Hanyu; Hiroyuki ; et
al. |
October 15, 2009 |
Removing Method of Hard Coating Film
Abstract
A hard coating film is efficiently etched by a krypton ion beam
of comparatively large mass, and then it is slowly etched by an
argon ion beam of small mass. As a result, a coating film removing
operation can be performed in a short time with suppressing an
influence of the coating film removal on a tool base material
(changes in shape and dimension) to the minimum. Since both krypton
and argon are an inert gas, even upon the surface of the tool base
material being exposed, the surface weakness by chemical erosion
can be completely prevented. As a result, even when a hard coating
film coated working tool is reproduced by re-coating the tool base
material with the hard coating film, the hard coating film is
coated by excellent adhesion strength.
Inventors: |
Hanyu; Hiroyuki;
(Toyokawa-shi, JP) ; Fukui; Yasuo; (Toyokawa-shi,
JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
OSG CORPORATION
TOYOKAWA-SHI
JP
|
Family ID: |
38580832 |
Appl. No.: |
12/225157 |
Filed: |
April 10, 2006 |
PCT Filed: |
April 10, 2006 |
PCT NO: |
PCT/JP2006/307589 |
371 Date: |
September 16, 2008 |
Current U.S.
Class: |
204/192.34 |
Current CPC
Class: |
B23K 15/08 20130101;
B23K 17/00 20130101 |
Class at
Publication: |
204/192.34 |
International
Class: |
C23F 4/00 20060101
C23F004/00 |
Claims
1-6. (canceled)
7. A removing method of hard coating film from a main body of a
hard coating film coated member, a surface of the main body being
coated with the hard coating film composing of a metal carbide, a
metal nitride, or a metal carbonitride in Group IIIb, IVa, Va, or
VIa of the periodic table of the elements, or composing of a solid
solution of these compounds the hard coating film being removed
from the main body by irradiating an ion beam onto the hard coating
film to etch the hard coating film, characterized by that: the
etching is performed by irradiating the ion beam created using an
inert gas as a working gas onto the hard coating film, the etching
comprising steps of: a first etching step of etching the hard
coating film by irradiating the ion beam created using a first
inert gas as a working gas onto the hard coating film; and a second
etching step of etching the hard coating film by irradiating the
ion beam created after switching of working gas from the first
inert gas to a second inert gas of which atomic weight is smaller
than the first inert gas onto the hard coating film.
8. The removing method of hard coating film according to claim 7,
wherein the first etching step uses any one of radon, xenon, and
krypton as the working gas, and the second etching step uses an
argon gas as the working gas.
9. The removing method of hard coating film according to claim 7,
wherein the main body is made of a super-hard alloy.
10. The removing method of hard coating film according to claim 7,
wherein the hard coating film coated member is a hard coating film
coated working tool in which at least a working part is coated with
the hard coating film.
11. The removing method of hard coating film according to claim 7,
wherein during the etching by the ion beam, an emitting member of
the ion beam and the hard coating film coated member are relatively
moved.
12. The removing method of hard coating film according to claim 7,
wherein the etching by the ion beam is performed at a final stage
of the hard coating film removal.
13. The removing method of hard coating film according to claim 7,
wherein the hard coating film has thickness of 1 .mu.m to 5
.mu.m.
14. The removing method of hard coating film according to claim 7,
wherein the first etching step uses the xenon gas, and the second
etching step uses the krypton gas.
15. The removing method of hard coating film according to claim 9,
wherein the surface of the main body is roughened and/or formed
with a foundation coating.
Description
TECHNICAL FIELD
[0001] The present invention relates to a removing method of hard
coating film made of, for example, TiAlN or TiCN, and; more
particularly, to the removing method of hard coating film with
almost no damaging a main body.
BACKGROUND ART
[0002] A hard coating film coated member is known in which a
surface of a main body is coated or covered with a hard coating
film. The hard coating film is composed of a metal carbide, a metal
nitride, or a metal carbonitride in Group IIIb, IVa, Va, or VIa of
the periodic table of the elements, or composed of a solid solution
of these compounds. The hard coating film coated working tool, such
as an end mill, a tap, a drill, or a bit produced by coating the
surface of a tool base material (main body) made of a super-hard
alloy with the above-mentioned hard coating film has been proposed
in, for example, Patent Literature 1. At least a working part of
the working tool surface at which a cutting blade or the like is
provided, is coated. A PVD (physical vapor deposition) method, such
as an ion plating method, is employed for coating the hard coating
film.
[0003] In the thus structured hard coating film coated member, the
hard coating film may be worn out or damaged, or defective articles
may be produced or created by, for example, bad coating in a
production process. It is conceivable to remove the hard coating
film to thereby reuse the main body such as the tool base material.
That is, the hard coating film is chemically resolved with a wet
process by a hydrogen peroxide solution or the like, to be removed
from the main body.
[0004] [Patent Literature 1] Japanese Patent Publication No.
2005-7555A
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0005] However, when the hard coating film is removed using the
chemical reaction as mentioned above, the main body may be
precedingly i.e. in advance exposed partially because of
non-uniformity in thickness of the hard coating film or because of
a difference in a coating film removing speed, thus following
problems being caused. In this case, since the exposed surface of
the main body is also damaged by a treatment liquid, upon complete
removal of the hard coating film, the surface of the main body is
partially roughened or weakened. For example, when the main body is
made of a super-hard alloy, WC particles in a surface layer are
chemically eroded, so that the surface may be weakened, and a
change in shape of the main body, such as roundness or diameter
decrease of the edge of a cutting blade, may occur. When the thus
shape changed main body is re-coated with the hard coating film,
adhesive properties may be impaired resulting from the surface
weakness, so that the original coating performance (durability or
abrasion resistance) cannot be obtained, or the edge of the blade
may be rounded to thereby lower the cutting performance.
[0006] The present invention has been made in view of these
circumstances, and has an object to remove a hard coating film with
almost no damaging a main body of a hard coating film coated
member.
Means for Solving the Problems
[0007] For achieving the above object, a first aspect of the
present invention is related to a removing method of hard coating
film from a main body of a hard coating film coated member, a
surface of the main body being coated with the hard coating film
composing of a metal carbide, a metal nitride, or a metal
carbonitride in Group IIIb, IVa, Va, or VIa of the periodic table
of the elements, or composing of a solid solution of these
compounds.
[0008] The removing method of hard coating film is characterized by
that the hard coating film is removed from the main body by
irradiating an ion beam onto the hard coating film and etching the
hard coating film.
[0009] In second aspect of the present invention, the etching is
performed by irradiating the ion beam created using an inert gas as
a working gas onto the hard coating film.
[0010] In the third aspect of the present invention, the coating
film removing method is comprised of a first etching step of
etching the hard coating film by irradiating the ion beam created
using a first inert gas as a working gas onto the hard coating
film; and a second etching step of etching the hard coating film by
irradiating the ion beam created after switching of working gas
from the first inert gas to a second inert gas of which atomic
weight is smaller than the first inert gas onto the hard coating
film.
[0011] In the fourth aspect of the present invention, the first
etching step uses any one of radon, xenon, and krypton as the
working gas in, and the second etching step uses an argon gas as
the working gas.
[0012] In the fifth aspect of the present invention, the main body
is made of a super-hard alloy.
[0013] In the sixth aspect of the present invention, the hard
coating film coated member is a hard coating film coated working
tool in which at least a working part is coated with the hard
coating film.
Effects of the Invention
[0014] According to the removing method of hard coating film of the
first aspect of the present invention, the hard coating film i.e.
hard coating layer is removed from the main body mainly by the
sputtering i.e. sputtering phenomenon by irradiation of the ion
beam. Therefore, even if the surface of the main body is
precedingly exposed partially because of the thickness
non-uniformity in the hard coating film or because of the coating
film removing speed difference, following effects can be rendered.
The surface weakness of the main body by the chemical erosion can
be suppressed. Thanks to the small influence of the coating film
removal on the main body, changes in the shape and the dimension of
the main body become smaller, compared with a case in which the
hard coating film is removed mainly using the chemical
reaction.
[0015] As a result, the main body can be re-used with no
modification or with only a slight modification thereof Thus, not
only the hard coating film-coated member can be reproduced at low
cost by being re-coated with the hard coating film, but the
adhesion strength of the hard coating film to the main body is
increased. Therefore, the original coating performance (durability,
abrasion resistance, etc.) which is the same as a new article can
be rendered.
[0016] According to the second aspect of the invention, the hard
coating film is etched by irradiation of the ion beam created using
the inert gas as the working gas, so that the hard coating film is
mechanically removed mainly by the sputtering using the ion
irradiation. Therefore, although the removing speed becomes slow,
the main body surface can be completely prevented from being
weakened by the chemical erosion even upon the surface being
exposed. As a result, the adhesion strength of the hard coating
film to the main body upon re-coating is further increased.
[0017] According to the third aspect of the present invention, in
the first etching step, the etching is performed using the first
inert gas having comparatively large atomic weight, so that the
hard coating film can be efficiently removed using the sputtering
of ions having the large mass. In the second etching step, etching
is performed using the second inert gas having comparatively small
atomic weight, so that the hard coating film is gradually removed
using the sputtering of ions having the small mass. Appropriately
setting the processing time period of the first and second steps
can shorten the time period required for the coating film removing
operation with suppressing the influence thereof on the main body
(changes in shape and dimension) to the minimum. Basically, the
working gas is sufficiently switched between the first and second
etching steps so that the both steps can be continuously performed,
with holding the hard coating film coated member in a predetermined
etching-treatment container.
[0018] According to the fifth aspect of the invention, when the
hard coating film is removed from the main body made of the
super-hard alloy using the chemical reaction by the hydrogen
peroxide solution, WC particles in the surface layer are chemically
eroded which leads to the weakened surface. However, by removing
the hard coating film mainly using the sputtering by the ion beam
of the present invention, the advantageous effects mentioned above
are achieved more remarkably. For example, weakness of the main
body surface is prevented, and the adhesion strength of the hard
coating film after the re-coating is increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic view showing one example of a hard
coating film removing apparatus advantageously used for carrying
out the removing method of the present invention.
[0020] FIGS. 2A and 2B illustrate one example of a hard coating
film coated working tool that is removed by the hard coating film
removing apparatus of FIG. 1, in which FIG. 2A is a front view, and
FIG. 2B is an enlarged sectional view of a surface part of a blade
coated with a hard coating film.
[0021] FIG. 3 is a flow chart explaining a process to be performed
for removing the hard coating film using the hard coating film
removing apparatus of FIG. 1.
[0022] FIG. 4 shows a measured result obtained by examining
durability of the hard coating film coated working tool. In the
working tool, the hard coating film is first removed from the tool
base material, and then the tool base material is re-coated with
another hard coating film according to the removing method of the
present invention. For comparison, reproduced articles produced by
removing the hard coating film according to conventional chemical
treatment (conventional method 1, conventional method 2) and a new
article are shown.
DESCRIPTION OF SYMBOLS
[0023] 12: Hard coating film coated working tool (Hard coating film
coated member)
[0024] 20: Tool base material (Main body)
[0025] 24: Cutting part (Working part)
[0026] 30: Hard coating film
[0027] Step S2: First etching step
[0028] Step S3: Second etching step
BEST MODE FOR CARRYING OUT THE INVENTION
[0029] The present invention is advantageously applied to a hard
coating film coated working tool, such as cutting tools including
an end mill, a drill, a tap or a bit, or rolling dies. Besides, the
present invention can be applied to the hard coating film removal
from various hard coating film coated members, such as a hard
coating film coated semiconductor device.
[0030] A super-hard alloy is suitably used as the tool base
material to be coated with the hard coating film, but other tool
base materials, such as high-speed tool steels, can be used. For
increasing the adhesive properties, a predetermined pre-treatment
can be performed for the main body, for example, such as a surface
roughening on the surface of the tool base material, or another
coating such as a foundation coating. In the hard coating film
coated semiconductor device, this process can be performed in the
same way.
[0031] The hard coating film coated member is sufficiently coated
with the hard coating film composed of at least a metal carbide, a
metal nitride, or a metal carbonitride in Group IIIb, IVa, Va, or
VIa of the periodic table of the elements, or composed of a solid
solution of these compounds. The hard coating film includes, for
example, TiAlN, TiCN, TiCrN, or TiN. Another coating, such as a
diamond coating or a DLC (Diamond-Like Carbon) coating, can be
provided on or under the hard coating film. When the foundation
layer of, for example, the diamond coating is provided, only the
hard coating film, such as a TiAlN coating can be removed by the
ion beam etching to leave the foundation layer.
[0032] The hard coating film is suitably provided according to a
PVD method, such as an arc ion plating method or a sputtering
method, but another coating method such as a plasma CVD method can
be employed. The thickness of the hard coating film is
appropriately set depending on for example the kind thereof. For
example, a desirable thickness of the hard coating film is about 1
.mu.m to 5 .mu.m. A multilayered hard coating film can be employed
in which two or more kinds of hard coating films are alternately
stacked with each other. Thus, various modes can be employed.
[0033] Preferably, the ion beam etching is performed with moving
the ion beam gun emitting the ion beam relative to the hard coating
film coated member if necessary so that the ion beam can be
uniformly irradiated onto the hard coating film. Parts or areas
other than the coated part of the hard coating film to be etched is
preferably masked with a masking agent, such as photoresist.
[0034] The working gas is the ion source for creating the ion beam,
and is ionized to be irradiated onto the hard coating film. The
inert gas is used as the working gas in a second aspect of the
present invention, but the ion beam etching can be performed by
gases other than the inert gas in the first aspect of the present
invention. When using gas which is chemically active with the hard
coating film, the hard coating film is removed by the chemical
reaction in addition to the sputtering. Thus, the main body is more
effectively suppressed from being damaged, compared with a
conventional example in which the hard coating film is removed
based on the wet process mainly using a chemical reaction.
[0035] Although the hard coating film can be removed merely by the
ion beam etching, another coating film removing technique may be
used together therewith. In detail, for suppressing damage of the
main body such as the tool base material or the like, the ion beam
etching is preferably employed at least in the last stage of the
coating film removing process. The hard coating film is efficiently
roughened by another coating-film removing technique prior to the
ion beam etching, and then it is gradually removed by the ion beam
etching using the working gas such as the inert gas. Thus, the hard
coating film removing can be performed in various modes.
[0036] In the fourth aspect of the present invention, any one of
radon, xenon, and krypton is used in the first etching step, and
the argon gas is used in the second etching step. Since the atomic
weight relation among these gases can be expressed as
radon>xenon>krypton>argon, the gases can be used in
various manners. In the third aspect of the present invention, for
example, the xenon gas is used in the first etching step, and the
krypton gas is used in the second etching step. Noted that neon and
helium included in the inert gas is, due to the small mass thereof,
unsuitably used for etching in the present invention.
EMBODIMENT
[0037] An embodiment of the present invention will be hereinafter
described in detail with reference to the attached drawings.
[0038] FIG. 1 is a schematic view of a hard coating film removing
apparatus 10 which removes the hard coating film according to the
coating film removing method of the present invention, using an ion
beam etching apparatus. A hard coating film coated working tool 12
is disposed on a rotary table 18 within an etching treatment
container 16 concentrically with a center line S of the table 18 by
a chuck 14. The hard coating film coated working tool 12,
corresponding to a claimed hard coating film coated member, is an
end mill in FIG. 1.
[0039] As shown in FIGS. 2A and 2B, a tool base material 20 made of
a super-hard alloy i.e. cemented carbide is integrally provided
with a shank 22 and a cutting part 24. The cutting part 24 has an
outer cutting edge 26 and an end cutting edge 28 each serving as a
part of a cutting blade. A surface of the cutting part 24 is coated
with a hard coating film 30 by the coating technique including a
PVD method such as an arc ion plating method.
[0040] The hard coating film 30 is composed of the metal carbide,
the metal nitride or the metal carbonitride in Group IIIb, IVa, Va
or VIa of the periodic table of the elements, or composed of the
solid solution of these compounds. In this embodiment, TiAlN is
provided in the form of a single layer, which has the thickness of
about 3 .mu.m within the range from 1 .mu.m to 5 .mu.m.
[0041] FIG. 2A is a front view of the hard coating film coated
working tool 12 viewed from a direction perpendicular to its axis,
and FIG. 2B is an enlarged sectional view of the surface of the
cutting part 24 coated with the hard coating film 30. The shaded
portion in FIG. 2A shows the hard coating film 30 and the hard
coating film coated working tool 12 is disposed on the rotary table
18, with the cutting part 24 coated with the hard coating film 30
being directed upward. The working tool 12 is a used article of
which hard coating film 30 has been worn out or damaged due
repeated use, or is a defective article produced by for example a
bad coating operation of the hard coating film 30 during the
production process. Here, only one hard coating film coated working
tool 12 is disposed concentrically with the rotary table 18 in FIG.
1, but a plurality of hard coating film coated working tools 12 can
be disposed parallel to the center line S to perform the coating
film removing process simultaneously. The tool base material 20
corresponds to a claimed main body, and the cutting part 24
corresponds to a claimed working part.
[0042] The hard coating film removing apparatus 10 in FIG. 1 etches
the hard coating film 30 by the ion beams emitted from a pair of
ion beam guns 32a and 32b having an ion creating source, to remove
the hard coating film 30. A working gas supply device 40 supplies a
working gas serving as an ion source of an ion beam to the ion beam
guns 32a and 32b. In this embodiment, the krypton gas and the argon
gas which is smaller than the krypton gas in the atomic weight can
be switched to be selectively supplied. The ion beam guns 32a and
32b selectively irradiate the krypton ion beam and the argon ion
beam depending on the kind of the working gas.
[0043] The internal pressure of the etching treatment container 16
is reduced by a vacuum pump 42. In this embodiment, the pressure is
set at 0.1 Pa, and the ion acceleration voltage is set at 3.0 kV.
The distance from the ion beam guns 32a and 32b to the hard coating
film coated working tool 12 is about 200 mm. A bias of 50 kHz and
500 V is applied by a bias power source 44 onto the hard coating
film coated working tool 12 coated with the hard coating film. The
ion source current is 500 mA.
[0044] The rotary table 18 is rotatingly driven around the center
line by a rotation driving unit 46 having an electric motor and a
decelerator S at a predetermined rotational speed, so that the hard
coating film coated working tool 12 is rotated (turned) together
with the rotary table 18 around its axis. Thus, the ion beam is
substantially evenly irradiated onto the entire circumferential
periphery of the cutting part 24. An upward-downward movable base
48 is disposed above the rotary table 18. Accordingly, the ion beam
guns 32a and 32b are disposed via biaxial irradiation-angle
adjusting devices 34a and 34b, respectively, to be adjusted in the
posture, i.e., the beam irradiation angle thereof with respect to
the hard coating film coated working tool 12. The upward-downward
movable base 48 is additionally provided with an approach-estranged
device that allows the ion beam guns 32a and 32b to proceed i.e.
approach to or recede i.e. estrange from the hard coating film
coated working tool 12 together with the irradiation-angle
adjusting devices 34a and 34b in accordance with, for example, the
diameter of the hard coating film coated working tool 12.
[0045] The upward-downward movable base 48 is linearly moved upward
and downward by an axially moving device 50, i.e., in a direction
parallel to the axis (center line S) of the hard coating film
coated working tool 12 fixed to the rotary table 18. For example,
the axially moving device 50 has a feeding screw rotatingly driven
in both forward and backward directions by an electric motor. An
electronic control device 52 having a microcomputer controls the
rotation driving unit 46 and the axially moving device 50 to
rotatingly drive the hard coating film coated working tool 12
around its axis to thereby move the ion beam guns 32a and 32b
upward and downward. Thus, the ion beam is irradiated onto the
entire circumferential periphery and the entire length of the
cutting part 24 coated with the hard coating film 30.
[0046] The irradiation time period of the ion beam is appropriately
set depending on the length of the cutting part 24 or the thickness
of the hard coating film 30. A masking agent such as photoresist is
provided on part i.e. area other than the coated part i.e. area of
the hard coating film 30, that is, at the shank 22, if necessary,
to prevent the shank 22 from being etched by the ion beam.
[0047] Next, referring to the flow chart of FIG. 3, a removing
process of the hard coating film 30 using the hard coating film
removing apparatus 10 will be explained. In step S1 of FIG. 3,
after the hard coating film-coated working tool 12 is disposed on
the rotary table 18, the internal pressure of the etching treatment
container 16 is reduced down to about 0.1 Pa by a vacuum pump 42.
In step S2, with drivingly rotating the hard coating film-coated
working tool 12 around its axis, the ion beam guns 32a and 32b are
moved upward and downward by the rotation driving unit 46 and the
axially moving device 50.
[0048] Simultaneously, the krypton gas serving as the working gas
is supplied from the working-gas supply device 40 to the ion beam
guns 32a and 32b, so that the krypton ion beam is irradiated onto
the hard coating film 30 to etch it. Here, the krypton gas which is
the inert gas does not chemically react with the hard coating film
30 made of TiAlN. Therefore, the hard coating film 30 is
mechanically removed mainly based on the sputtering by irradiating
the krypton ions. Thanks to a comparatively large atomic weight of
83.80 of krypton, the irradiating krypton ions having the large
mass can remove the hard coating film 30 efficiently by the
sputtering.
[0049] The etching treatment using the krypton ion beam is
performed in a part (thickness: 3 .mu.m) correctly coated with the
hard coating film 30 only during a predetermined time (e.g., about
20 hours). The predetermined time period is. determined so that the
etching completes before the surface of the tool base material 20
is exposed resulted from complete removal of the hard coating film
30. However, in the actual step S2, the surface of the tool base
material 20 is partially exposed depending on the state of the hard
coating film 30. Step S2 corresponds to a claimed first etching
step.
[0050] Thereafter, step S3 is performed to switch the working gas
from the krypton gas to the argon gas to be supplied from the
working-gas supply device 40 to the ion beam guns 32a and 32b.
Thus, the argon ion beam is irradiated onto the hard coating film
30 to etch it. The argon gas which is the inert gas does not
chemically react with the hard coating film 30 made of TiAlN,
similar to step S2 mentioned above. Therefore, the hard coating
film 30 is mechanically removed mainly using the sputtering by
irradiation of the argon ions.
[0051] Herein, due to the comparatively small atomic weight of
39.95 of argon, the hard coating film 30 is comparatively slowly
removed using the sputtering by irradiation of the argon ions
having the small mass. The etching treatment using the argon ion
beam is performed only during a predetermined time period (e.g.,
about 10 hours) for completely removing the hard coating film 30.
Step S3 corresponds to a claimed second etching step.
[0052] The series of etching steps are completed in this way. Then,
the tool base material 20 of which hard coating film 30 has been
removed is taken out from the etching treatment container 16. The
outer cutting edge 26 and the end cutting edge 28 are re-ground if
necessary. Thereafter, the cutting part 24 is coated with the hard
coating film 30 made of TiAlN using the coating technique, such as
the arc ion plating method. In this way, the hard coating film
coated working tool 12 is reproduced.
[0053] In this embodiment, etching by irradiation of the ion beam
onto the hard coating film 30 can remove the hard coating film 30
from the tool base material 20 using mainly the sputtering.
Therefore, even when the surface of the tool base material 20 is
precedingly exposed partially because of the thickness
non-uniformity of the hard coating film 30 or because of the
coating-film removing speed difference, the present invention can
render following excellent advantages compared with a case in which
the hard coating film is removed mainly by the chemical reaction.
The first advantage is that the surface weakness by the chemical
erosion can be prevented. The second advantage is that the
influence of the coating-film removal on the tool base material 20
becomes small, so that the changes in the shape and the dimension
of the tool base material 20 can be reduced.
[0054] Therefore, the tool base material 20 can be re-used with no
modification or only slight modification. The hard coating film
coated member 12 can be reproduced at low cost by re-coating the
hard coating film 30 on the tool base material 20. As a result, the
adhesive strength of the hard coating film 30 to the tool base
material 20 is increased, so that the original coating performance
(durability, abrasion resistance, etc.) similar to that of a new
article can be obtained.
[0055] In particular, this embodiment uses the krypton gas and the
argon gas, both being the inert gas, as the working gas creating
the ion beam. Therefore, the hard coating film 30 is mechanically
removed mainly by the sputtering with the ion irradiation without
the chemical reaction of the gas with the hard coating film 30.
Therefore, the surface of the tool base material 20, even upon
being exposed, is not weakened by chemical erosion, although the
coating-removal speed becomes slow. As a result, the adhesion
strength of the re-coated hard coating film 30 is further
increased.
[0056] Noted that, when the hard coating film is removed from the
tool base material 20 made of the super-hard alloy by the chemical
reaction using the hydrogen peroxide solution, WC particles in the
surface layer may be chemically eroded to weaken the surface of the
tool base material 20. However, in the present invention, the hard
coating film is removed by the sputtering with the ion beam using
the inert gas serving as the working gas. As a result, the
advantageous effects mentioned above are achieved more remarkably,
which includes avoidance of the weakened surface of the tool base
material 20, and increase in the adhesion strength of the hard
coating film 30 after the re-coating.
[0057] Additionally, in this embodiment, step S2 performs the
etching by the krypton gas. Therefore, the sputtering of the
krypton ions having the comparatively large mass can efficiently
remove the hard coating film 30. Additionally, step S3 performs the
etching using the argon gas. Therefore, the sputtering of the argon
ions having the small mass can gradually remove the hard coating
film 30. The time period required to remove the hard coating film
can be shortened by appropriately setting the processing time of
the first and second steps with suppressing influence of the
coating film removal on the tool base material 20 (changes in shape
and dimension) to the minimum.
[0058] For example, in step S2, the processing time is set to the
maximum as long as the tool base material 20 is not exposed at the
coated part i.e. area (hard coating film thickness: 3 .mu.m)
correctly coated with the hard coating film 30. In step S3, the
processing time is set to the minimum as long as the remaining
parts of the hard coating film 30 left in step S2 is completely
removed.
[0059] What is required between steps S2 and S3 is to switch the
working gas. Accordingly, steps S2 and S3 can be continuously
performed with holding the hard coating film coated working tool 12
in the etching treatment container 16.
[0060] Four test pieces were prepared in total for two-flute end
mills each having a tool diameter D of 10 mm. In these test pieces,
the cutting part 24 of the tool base material 20 made of a
super-hard alloy is coated with the hard coating film 30 made of
TiAlN having thickness of 3 .mu.m. Cutting operation was performed
under following processing conditions. The four test pieces or
articles include an invented test piece reproduced according to the
coating film removing method of the present invention, a
conventional test piece 1 and a conventional test piece 2 according
to the conventional coating film removing method, and a new
article. After the cutting, the wear width VB (mm) of the flank
surface was examined to obtain a test or measured result shown in
FIG. 4.
[0061] The test piece according to the film coating film removing
method of the present invention was prepared using the tool base
material 20 without modifications by re-coating the hard coating
film 30 thereon. Here, the processing time period in step S2 is set
in 20 hours and the processing time period in step S3 is set in 10
hours. The conventional test pieces 1 and 2 were prepared by
re-coating with the hard coating film 30 on the tool base material
20 of which coating film was removed by the chemical treatment
using the hydrogen peroxide solution.
<<Processing Conditions>>
[0062] Tool: Two-flute super-hard end mill, .phi.10 [0063] Cutting
speed: 34.5 m/minute [0064] Feeding speed: 0.03 mm/blade [0065]
Cutting:
[0066] Axial direction aa=15 mm
[0067] Radial direction ar=0.5 mm [0068] Coolant: Air blow [0069]
Processing Kind: Side face (Down) [0070] Material to be cut: SKD61
(40HRC)
[0071] As is apparent from the measurement result of FIG. 4, the
coating film removing method of the present invention can reduce
the wear width VB of the flank surface to half that of the
conventional article 1 or 2, which renders the excellent abrasion
resistance same as that of the new article. Presumable reason is
that the adhesion strength of the hard coating film 30 to the tool
base material 20 is equivalent to that of the new article, and the
cutting blade shape of the outer cutting edge 26 is equivalent to
that of the new article, which leads to the more excellent cutting
performance.
[0072] The embodiment of the present invention has been described
in detail with reference to the attached drawings as above.
However, noted that this is merely one embodiment. The present
invention can be embodied in variously modified and improved modes
according to the knowledge of those skilled in the art.
INDUSTRIAL APPLICABILITY
[0073] According to the hard coating film removing method of the
present invention, etching by irradiation of the ion beam onto the
hard coating film can remove the hard coating film from the main
body mainly by the sputtering. For this reason, compared with the
case in which the hard coating film is removed mainly by the
chemical reaction, the surface weakness by the chemical erosion is
suppressed, and the influence of the coating film removal on the
main body becomes smaller. Changes in the shape and the dimension
of the main body become smaller. As a result, the main body can be
re-used with no modification or with only the slight modification.
Thus, the re-coating with the hard coating film can reproduce the
hard coating film-coated member at low cost, and can increase the
adhesion strength of the hard coating film, so that the original
coating performance which is the same as that of the new article
can be rendered. That is, the present invention is advantageously
used when removing the hard coating film of the hard coating film
coated member such as the end mill the tap or the drill, and
reusing the main body such as the tool base material, to thereby
reproduce hard coating film coated member.
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