Patent Application
20090255805
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.
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.
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.
[Patent Literature 1] Japanese Patent Publication No. 2005-7555A
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.
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.
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.
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.
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.
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.
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.
In the fifth aspect of the present invention, the main body is made of a super-hard alloy.
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.
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.
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.
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.
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.
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.
12: Hard coating film coated working tool (Hard coating film coated member)
20: Tool base material (Main body)
24: Cutting part (Working part)
30: Hard coating film
Step S2: First etching step
Step S3: Second etching step
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.
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.
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.
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 μm to 5 μm. 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.
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.
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.
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.
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.
An embodiment of the present invention will be hereinafter described in detail with reference to the attached drawings.
As shown in
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 μm within the range from 1 μm to 5 μm.
The hard coating film removing apparatus 10 in
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.
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.
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.
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.
Next, referring to the flow chart of
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.
The etching treatment using the krypton ion beam is performed in a part (thickness: 3 μm) 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.
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.
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.
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.
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.
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.
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.
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.
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.
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 μm) 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.
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.
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 μm. 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
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.
Axial direction aa=15 mm
Radial direction ar=0.5 mm
As is apparent from the measurement result of
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.
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.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/307589 | 4/10/2006 | WO | 00 | 9/16/2008 |
