JP3520098B2 - Diamond coated cutting tool - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to a diamond coating cutting machine.
Relates to cutting tools and, more particularly, after previously subjected to specific machining the cutting edge portion of the conductive substrate, by a vapor phase method, the wear resistance by performing the focus diamond coating on the cutting edge portion is significantly improved The coated diamond cutting tool .

[0002]

BACKGROUND OF THE INVENTION Diamond has the highest hardness of any existing material. Therefore, a cutting tool obtained by coating the surface of a base material for a cutting tool with a diamond film is drawing attention.

However, in order to enable more efficient or more precise cutting, it is necessary to improve the wear resistance of the diamond film in the cutting tool. Wear resistance is
When the adhesion of diamond to the substrate is sufficient,
It is determined by the film quality, crystal grain size, crystal orientation and film thickness of the diamond film. Among these, the most dominant factor is the film thickness, and in order to improve wear resistance and prolong the life, it is the most effective means to provide a thick film that is not easily worn.

However, if the thickness of the entire film is simply increased for the purpose of improving wear resistance, so-called coating time is required to be long, resulting in an increase in coating cost.
Not preferable. Therefore, it is conceivable to focus the diamond coating on the cutting edge portion. In this case, if the flatness of the rake face of the tip is impaired and the degree of swelling at such a cutting edge (edge) becomes too large,
When the tip is attached to the holder, the tip may be damaged by tightening pressure, or the tip may not be fixed properly, causing vibration (so-called chatter) during cutting, roughening the finished surface, chipping the tip, etc. Problem arises.

As is well known, when diamond is coated on a substrate made of cemented carbide by the microwave plasma CVD method, the diamond at the edge portion of the substrate becomes thicker than the other portions. Cheap. In other words, there is a problem that swelling is likely to occur on the rake face of the cutting edge.

Regarding improvement of the cutting edge portion of the diamond-coated cutting tool, in JP-A-62-171605, the width of the cutting edge corresponding to the line of intersection between the rake face and the flank of the substrate is 0.2 to 0.8 μm. By chamfering, a cutting tool that does not require "break-in" is obtained.

However, by chamfering only the tip of the cutting edge, it is not possible to eliminate the swelling of the diamond at the cutting edge portion due to excessive diamond formation at the cutting edge portion due to the concentration of plasma in the diamond thin film formation by the vapor phase method. .

Further, Japanese Patent Laid-Open No. 64-51202 proposes a method of chamfering the base material of the cutting edge portion to 0.01 to 0.08 mm. However, as in the above case, the cutting edge of diamond is Instability of attachment to the holder due to bulge in the part cannot be eliminated.

As a result of diligent research conducted by the present inventors based on the above circumstances, the shape of the base material is suitably deformed in advance by grinding or warping, and then the cutting edge portion is intensively coated with diamond to thereby form a cutting edge. It has been found that a diamond-coated cutting tool can be obtained in which the portion can be made into a film thickness, and furthermore, the diamond can be flatly coated as the entire chip, and as a result, the cutting life can be remarkably extended.
The present invention has been completed.

That is, an object of the present invention is to provide a diamond-coated cutting tool having a significantly long cutting life.

[0011]

The invention according to claim 1 for solving the above-mentioned problems is a cemented carbide or a cermet.
Inclined from the rake face of the base material made of
Forming an inclined inclined surface, and the angle of the inclined surface is
1 to 30 degrees with respect to the rake face, and the length of the inclined face
On the substrate having a size of 0.25 to 3 mm by diamond synthesis by the vapor phase method to form a diamond coating.
A diamond-coated cutting tool, characterized in that that,
The invention according to claim 2 is from a cemented carbide or cermet
Slope down from the rake face of the base material to the edge of the blade.
Is formed from a ridgeline of the blade.
The length of the curved surface toward the rake face is 0.25 to 3 mm
, And the and the substrate R of the curved surface satisfies the following equation, by performing a diamond synthesis by vapor-phase method diamond
Diamond coating characterized in that
It is a covering cutting tool , and Δt = R {1-cos (L / R)} (where Δt is the thickness t of the diamond film coated on the rake face of the cutting edge of the substrate and the rake face of the substrate) The difference from the thickness t0 of the diamond film in the central portion is shown, R shows the radius of curvature of the curved surface, and L shows the length from the blade tip on the curved surface.) The invention according to claim 3, da according to claim 1 or 2 is formed by chamfering the surface
A Iyamondo coated cutting tool, the invention of claim 4, claims 1 to 3 formed by the warp processing the inclined surface
Ah with a diamond coated cutting tool according to any one of
It

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a base material which is previously processed by a chamfering process or a warping process at the cutting edge portion thereof when manufacturing a diamond-coated cutting tool so that the thickness thereof decreases as it goes in the cutting edge direction. It is characterized in that when the diamond is coated on this base material, the cutting edge portion is mainly coated.

(1) Substrate As the substrate used in the present invention, a substrate having conductivity may be used, and a substrate made of cemented carbide, cermet or the like may be used. Preferred is, for example, WC-
JIS SPGN12 of 5% Co-2.5% TiC composition
A 0308 shaped cutting tip.

In addition to the above-mentioned preferred cutting tips, examples of the cemented carbide that can be used in the method of the present invention include W, Mo, Cr, Co, Ni, Fe and T.
i, Zr, Hf, Nb, Ta, Al, B, Ga, Si and the like, cemented carbides composed of one or more kinds of metals, one or more kinds of these metals, carbon, nitrogen oxygen and / or Cemented carbides of various compositions such as boron (specifically, for example, WC, W-WC, WC-C,
WC system such as WC-C, Co-C system, Co-WC,
Co-W-WC, Co-WC-C, Co-W-WC-C
Co-W-C system, etc., TaC _x, etc. Ta-C system, TiC
Ti-C system _{etc., MoC x, Mo-MoC x} , MoC x
Mo-C system such as -C system, Si-C system such as SiC, Fe-
Fe-C system such as FeC _x system and Ti- system such as TiC-Ni system
Ni-C system, Ti-Co-C system such as TiC-Co system, T
Ti-N system such as iN system, Ta-N system such as TaN _x system, W
W-Ta-Co-C system such as C-TaC-Co-C system, W
W-Ti-Co-C system such as C-TiC-Co-C system, W
W-Ti-Ta- such as C-TiC-TaC-Co-C system
Co-C system, W-Ti-C-N system, W-Co-Ti-C
A wide variety of cemented carbides such as -N type) can be mentioned. Among these, as a particularly preferable example, for example, a WC-based cemented carbide suitable for a cutting tool and the like (specifically, for example, JIS B 4053 uses classification symbols P01, P10, P20, P30, P40, P50.
Such as P species, M10, M20, M30, M40 and other M species,
Carbide chips for cutting tools such as K01, K10, K20, K30, K40 and other cutting tools, V1 such as V1, V2, V3 for drawing dies, centers, cutting tools, etc. W-Co-C based cemented carbide such as WC-Co based hard alloy chips, W-Ti such as WC-TiC-TaC-Co based
-Ta-Co-C type cemented carbide, or those in which a part of Ta is changed to Nb) and the like. In addition, these may contain elements other than the above and additional components. The material and shape of the cemented carbide used may be appropriately selected depending on the purpose of use and the like.

Among the above-mentioned preferable base materials, Group IVA, Group VA and Group V of the Periodic Table (IUPAC) are preferable.
An example is a tungsten carbide based cemented carbide containing a metal belonging to Group IA and one or more metals selected from Si.

Specific examples of preferable tungsten carbide type cemented carbides include WC, W-WC, WC-C and W-WC-.
WC system such as C, WC-Co, WC-Co-W, WC-
W-Co system such as Co-C, WC-Co-WC, WC-
W-Ta- such as TaC-Co and WC-TaC-Co-C
Co system, WC-TiC-Co, WC-TiC-Co, W
W-Ti-Co system such as C-TiCN-Co, WC-Ta
WT such as C-Co, WC-TiC-TaC-Co-C
Cemented carbides such as i-Ta-Co-C system and WC-Nb-Co can be mentioned. The tungsten carbide based cemented carbide can be obtained from tungsten carbide, tantalum carbide, titanium carbide, etc. as described above. Examples of the tungsten carbide-based cemented carbide used in the present invention include Ti, Co, and T.
Those containing a metal such as a, Mo, Cr and Ni are preferable.

In the present invention, among the tungsten carbide type cemented carbide used as the base material, specific examples of preferable compositions are WC-TiC-Co, WC-TaC-Co and WC-Co, WC-Nbc-. An example is a cemented carbide of Co.

As the cemented carbide having the composition of WC-TiC-Co, tungsten carbide is 50 to 95% by weight, preferably 70 to 94% by weight, and titanium carbide is 1 to 30% by weight, preferably 2 to 20% by weight. And cobalt 2 to 20% by weight, preferably 4 to 10% by weight.

As a cemented carbide having a composition of WC-TaC-Co, 80 to 93% by weight of tungsten carbide, preferably 85 to 92% by weight, and 1 to 20% by weight of tantalum carbide, preferably 2 to 10% by weight. And 3 to 10% by weight, and preferably 4 to 6% by weight of cobalt.

As a cemented carbide having a composition of WC-Co, 90 to 98% by weight of tungsten carbide, preferably 9
Mention may be made of those containing 4 to 97% by weight and cobalt 2 to 10% by weight, preferably 3 to 6% by weight.

As the above-mentioned tungsten carbide, those used in conventional tools and the like can be used. Specifically, WC, WCx (where x is a positive real number other than 1, and is usually This x is a number greater than 1 or less than 1.) Stoichiometric compounds and non-stoichiometric compounds, or other elements such as oxygen bonded to these,
Those that have been replaced or invaded can be mentioned. Of these, WC is usually particularly preferably used.

These may be used alone or in combination of two or more, or may be used as a mixture of two or more, a composition with a solid solution and the like.

The above-mentioned titanium carbide is not particularly limited, and those used for producing ordinary alloys can be used. Specifically, TiC and TiCy (where y represents a positive real number other than 1 and usually y is 1
It is a number greater than or less than one. ), A stoichiometric compound and a non-stoichiometric compound, or a compound in which another element such as oxygen is bound, substituted or invaded. Of these, usually TiC
Are particularly preferably used.

The tantalum carbide is not particularly limited, and those used for producing ordinary alloys can be used. Specifically, TaC, TaCz (where z is a positive real number other than 1, and normally z is 1
It is a number greater than or less than one. ), A stoichiometric compound and a non-stoichiometric compound, or a compound in which another element such as oxygen is bound, substituted or invaded. Among these, usually TaC
Are particularly preferably used.

The above-mentioned cobalt is not particularly limited, but a simple metal can be preferably used.

The tungsten carbide, the titanium carbide,
The tantalum carbide and the cobalt do not need to be particularly pure, and may contain impurities as long as the objects of the present invention are not impaired.

For example, the above-mentioned tungsten carbide may contain a slight amount of impurities such as excess carbon, excess metal and oxide.

As the cermet used in the present invention,
For example, Ti, W, Mo, Cr, Ta, Nb, V, Z
Co, Ni, C on carbides and nitrides such as r and Hf
A cermet material containing a metal such as r, Mo or Fe as a sintering aid can be mentioned, and any material generally known as a cermet material can be used without particular limitation.

Specific examples include WC, Mo ₂ C and Cr _3.
C ₂ , TaC, NbC, VC, TiC, ZrC, Hf
C, TaN, NbN, VN, TiN, ZrN, HfN,
Ta (C, O), Ti (C, O), Ti (N, O),
(W, Ti) C, (W, Ta, Ti) C, (W, Ta,
Nb, Ti) C, Ti (C, N), Ti (C, N,
O), (Ti, Zr) C, (Ti, Zr) (C, N), etc., contains Co and / or Ni as a sintering aid, and Cr, Mo, Fe, etc. in addition to Co and / or Ni. You can list the things that you did.

If the cermet is expressed differently from the above, the following description is also possible. That is, as the cermet that can be used in the present invention, Ti
WC, TaC and TiN are added to C and Ni is used as a binder phase.
Or Mo added, for example TiC-TaC-
Ni, TiC-TaC-Mo, TiC-TaC-Ni-
Mo, TiC-TiN-Ni, TiC-TiN-Mo,
TiC-TiN-Ni-Mo, TiC-TiN-TaC
-WC-Ni, TiC-TiN-TaC-WC-Mo,
TiC-TiN-TaC-WC-Ni-Mo, TiN-
TaN-Ni, TiN-TaN-Mo, TiN-TaN
-Ni-Mo, TiC-TaN-Ni, TiC-TaN
-Mo, TiC-TaN-Ni-Mo, TiC-Ni,
TiC-Mo, TiC-Ni-Mo, TiC-Ni, T
iC-Mo, TiC-Ni-Mo, TiC-TaN-N
i, TiC-TaN-Mo, TiC-TaN-Ni-M
o etc. can be mentioned. Note that these may contain other elements or their carbides.

Among these, titanium carbide, tungsten carbide and titanium nitride cermets are preferably used. Particularly preferred are TiC, TiN, T
A cermet material that uses Ni, Co, or Mo as a sintering aid for iCN or the like can be given.

(2) Processing of Base Material In the present invention, the cutting edge portion of the base material used is processed into a special shape.

The cutting edge portion of the base material can be processed by chamfering, warping or a combination thereof.

-Chamfering-The chamfering will be described with reference to FIG. 1, which is a cross-sectional view of the blade tip portion of the chip before diamond coating.

In the chamfering process in the present invention, so-called chamfer honing is applied to the edge of the rake face 2 and the flank face 3 of the substrate 1, and the angle θ1 with respect to the rake face is set.
Is 1 to 30 °, preferably 3 to 20 °, and
The dimension from the blade tip (indicated by L1 in FIG. 1) is 0.25.
A sloping surface 4 of -3 mm, preferably 0.5-2 mm is formed on the rake face. Angle θ1 with respect to rake face is 1 °
Is less than, in order to maintain the flatness of the rake face,
Since only a thin diamond film can be coated, the cutting life is shortened, and if it exceeds 30 °, it is necessary to thicken the cutting edge more than necessary in order to offset it and flatten it. Since it takes a long time, the manufacturing cost is increased, which is not preferable. If the dimension L1 from the cutting edge portion is less than 0.25 mm, the thickness of the cutting edge is too small when thickening only the cutting edge without impairing the flatness of the entire substrate, and the cutting edge thick film There is a problem in that the effect of increasing the thickness cannot be sufficiently obtained. Conversely, even if the thickness is larger than 3 mm, the effect of extending the life cannot be obtained even if the thickness is increased beyond this, which is not preferable.

The chamfering process may be performed not only on the rake face but also on both the rake face and the flank face as shown in FIG. In this case, the inclined surface 5 formed on the flank is
It has an inclination of 0.05 to 15 °, preferably 0.1 to 10 ° (represented by an angle θ2 in FIG. 2) and has a dimension from the blade tip (indicated by L2 in FIG. 2) of 0.05 to. 1.5 mm,
An inclined surface is formed which is preferably 0.25 to 1 mm.
If the angle to the flank is less than 0.05 °, it is difficult to machine for chamfering, and if it is larger than 15 °, the clearance angle of the entire substrate changes, which is not preferable. Further, if the dimension from the cutting edge is less than 0.05 mm, the effect of canceling the thickness of the diamond film is lost, and conversely, if it is greater than 1.5 mm, the clearance angle of the entire substrate changes, which is not preferable. .

Further, in the present invention, the chamfered cross section does not have to be a straight line as shown in FIG. 1, but may be a curved line as shown in FIG. In this case, the arc length L
Is 0.25 to 3 mm, and the radius of curvature R varies depending on the film thickness t at the cutting edge of the diamond film to be coated, but is determined from the relationship of Δt = R {1-cos (L / R)}, for example. (However, Δt represents the difference between the thickness t of the diamond film coated on the rake face of the cutting edge of the substrate and the thickness t ₀ of the diamond film in the central portion of the rake face of the substrate, and R is the curvature Indicates the radius of curvature of the surface, and L indicates the length from the blade tip on the curved surface.).

-Warping-In the present invention, as a method for forming a curved surface satisfying the above expression on the rake face of the cutting edge, in addition to the above-mentioned chamfering, there is a method of warping and a combination thereof. Good. Further, in the present invention, "satisfying the expression" is used in a meaning including an error which does not hinder the technical effects of the present invention because some errors occur during processing.

The warp processing in the present invention produces a warp in the base material and obtains the same effect as the above-mentioned chamfering processing. That is, the dimension from the cutting edge of the substrate is 0.25 to
A 3.0 mm portion is formed with a curved surface that descends and inclines with respect to the rake surface, and the curvature radius of the curved surface at that time is warped so that R has a value that satisfies the following expression.

Δt = R {1-cos (L / R)} (where Δt is the thickness t of the diamond film coated on the rake face of the cutting edge of the substrate and the central portion of the rake face of the substrate) The difference from the thickness t _{0 of the} diamond film is shown, R shows the radius of curvature of the curved surface, and L shows the length from the blade tip of the curved surface generated by the warping process.) Even in this warping process, the substrate Dimension L from the blade edge of
However, when the thickness is less than 0.25 mm, the thickness of the blade can be increased without increasing the flatness of the substrate as a whole. It is not obtained, and even if it is larger than 3.0 mm, the effect of extending the life of the base material cannot be expected to be improved.

As the warp processing, the method is not limited as long as the inclined surface satisfying the above conditions is formed, but for example, heat treatment can be mentioned.

As the heat treatment, for example, in a heat-resistant container under an inert gas atmosphere under a predetermined pressure, on a floor plate or powder formed of a predetermined substance, the base material is kept at a predetermined temperature for a predetermined time. The method of heating can be mentioned.

Examples of the inert gas include rare gases such as argon and helium, and nitrogen gas. These inert gases and the like can be used alone or in combination of two or more.

The pressure of the inert gas is usually 10 ^-3 T
Orr to 2,000 atm (gauge pressure), preferably 1 Torr to 100 atm (gauge pressure).

As the predetermined substance constituting the floor plate or powder, a preferable substance varies depending on the material and shape of the base material, but for example, alumina, zirconia, magnesia, silicon nitride, aluminum nitride, boron nitride, silicon carbide, boron carbide. And carbon and the like. As a specific example, when a cemented carbide containing titanium is used as the material of the base material, if alumina is used as the material of the laying board, the amount of deformation is small, which is not suitable, but if silicon nitride or boron nitride is used. Appropriate deformation is obtained, which is convenient for warpage processing.

As the heat-resistant container, a container formed of the same substance as the substance constituting the floor plate or powder can be mentioned.

The heating temperature is usually 600 to 1,80.
It is selected from the range of 0 ° C, preferably 1,000 to 1,
It is selected from the range of 600 ° C.

The heating time is usually about 30 minutes to 5 hours, but it is not limited to this and may be appropriately determined according to the type and size of the substrate.

As a preferable warping condition, the total pressure is 1
1,350 to 1 in a BN crucible using a BN floor plate in an inert gas atmosphere such as a mixed gas of nitrogen and argon (provided that the nitrogen gas is 1 to 760 Torr) at 0 ^{-3 to} 2,000 atm. A method of treating at 800 ° C. for 0.5 to 5 hours is preferable, and a suitable warp can be generated.

When this warping process is performed, it is not necessary to perform the adhesion improving process as a pre-treatment described below. This is because the warp processing simultaneously exhibits the effect of improving the adhesion of the diamond film.

(3) Pretreatment In the present invention, it is desirable that the following pretreatment be performed before the diamond coating is applied to the chamfered or warped substrate.

-Adhesion improvement treatment-In order to improve the adhesion of the diamond film formed on the substrate, it is preferable to subject the substrate to heat treatment or etching treatment.

<Heat Treatment> In this heat treatment, the surface of the base material itself is altered by heating the base material, preferably the base material placed on a specific floor board, to a predetermined temperature under a predetermined atmosphere. By heating to a predetermined temperature in a predetermined atmosphere, a solid solution having irregularities on the surface of the base material is formed.

The heating temperature range of the substrate is usually 600 to 1,
It is selected from the range of 800 ° C., preferably 1,000 to
It is selected from the range of 1,600 ° C. When the heating temperature range is within the above range, the modification of the substrate surface is sufficiently promoted. If the heating temperature range is higher than 1,800 ° C,
The effect of modifying the substrate, which is commensurate with increasing the temperature, may not be seen.

The pressure during the heat treatment of the substrate is usually 1
The pressure is 0 ^-3 Torr to 2,000 atm (gauge pressure), preferably 1 Torr to 100 atm (gauge pressure).
When the pressure is within the above range, the effect of modifying the base material can be achieved much better.

As an atmosphere when the substrate is heat-treated,
It may be under high vacuum, but it should be performed under reduced pressure with a small amount of nitrogen gas, or under a mixed gas atmosphere of nitrogen gas and an inert gas such as argon so that the partial pressure of nitrogen gas is low. This is preferable because the effect of modifying the surface of the base material is large, especially when the thin film of diamond or the like is formed on the base material after the heat treatment to improve the adhesion between them.

The amount of nitrogen gas that contributes to the improvement of the adhesion between the substrate and the thin film such as diamond varies depending on the type of substrate, the heating temperature, the treatment time, etc. No, but usually 1 to 760 Torr
Is appropriately selected from the range of 1 to 200 To
rr.

The heat treatment time for the substrate is usually 30 minutes to 5 minutes.
Although it is about time, it is not limited to this and may be appropriately determined according to the type, size, etc. of the base material.

When the base material is heat-treated, particularly when the base material is placed on a floor plate made of a specific material and heat-treated,
Although the reason is not clear, the adhesion to a thin film such as diamond is improved without causing deformation or dimensional change of the substrate itself.

As an example of the heat treatment, a mixed gas of nitrogen and argon having a total pressure of 10 atm (internal nitrogen gas: 100 Tor) is used.
r) It is preferable to perform the treatment at 1,400 ° C. for 1 hour in the atmosphere.

<Etching Treatment> Examples of the method of etching the surface of the base material include wet etching and dry etching.

Examples of wet etching include etching treatment with acid and electrolytic etching.

The acid used in the etching treatment with an acid is not particularly limited, and examples thereof include nitric acid, sulfuric acid, hydrochloric acid, and hydrofluoric acid. In addition, the above acid,
One kind may be used alone, or two or more kinds may be mixed and used.

Among the above acids, a mixed acid of nitric acid and hydrofluoric acid and a mixed acid obtained from hydrogen fluoride and nitric acid are particularly preferable.

The case of using a mixed acid of nitric acid and hydrofluoric acid or a mixed acid obtained from hydrogen fluoride and nitric acid will be described in detail below as an example of the acid etching treatment. However, the acid etching treatment in the present invention is not limited to this.

Hydrogen fluoride itself can be used as hydrogen fluoride when preparing a mixed acid obtained from hydrogen fluoride and nitric acid, or in the form of hydrofluoric acid which is an aqueous solution of hydrogen fluoride. It can also be used.

When the above-mentioned mixed acid is used, the content of hydrogen fluoride in the mixed acid obtained from hydrogen fluoride and nitric acid is usually 5 to 50, assuming that hydrogen fluoride is not decomposed. Mol%, preferably 10-40 mol%
Is. The nitric acid concentration in this mixture is:
It is usually 5 to 65 mol%, preferably 15 to 60 mol%. When hydrogen fluoride and nitric acid are contained in the mixed acid within the above range, the coating layer can be formed on the substrate layer treated with such mixed acid with good adhesion.

In order to contain hydrogen fluoride within the above range, when hydrofluoric acid is used, 1
Hydrofluoric acid containing 0 to 50%, preferably 20 to 46% hydrogen fluoride is preferred. Also, as nitric acid,
Nitric acid having a concentration of 30 to 70%, particularly 30 to 61% is preferable. From a practical point of view, the mixed acid obtained from hydrogen fluoride and nitric acid is preferably a mixture consisting essentially of hydrofluoric acid and nitric acid, and if necessary, other inorganic acids such as sulfuric acid may be mixed. It is also possible to use mixtures which consist of When a mixture consisting essentially of hydrofluoric acid and nitric acid is adopted, it is preferable to adjust the respective concentrations of hydrofluoric acid and nitric acid so that the contents of hydrogen fluoride and nitric acid are as described above.

The etching treatment with an acid is usually
Various methods such as a method of immersing the base material in the acid and a method of spraying the acid on the surface of the base material can be adopted. In short, it suffices that the predetermined surface of the base material on which the intermediate layer is provided can be brought into contact with the acid.

The temperature of the etching treatment with the acid is not particularly limited, but for example, when the above-mentioned mixed acid is used, it is usually preferably 20 to 100 ° C., particularly 50 to 9 ° C.
5 ° C is preferred. If the treatment temperature is lower than 20 ° C,
Since etching takes time, Co or the like may not be sufficiently etched. Further, when the treatment temperature is higher than 100 ° C., the controllability becomes poor because the etching of the surface of the base material progresses violently.

The etching time with the acid is not particularly limited as long as the etching is sufficiently performed. For example, when the above mixed acid is used, it is usually 0.5.
Seconds to 300 seconds are preferable, and 1 second to 120 seconds is particularly preferable. If the treatment time is shorter than 0.5 seconds, the etching treatment may be insufficient. On the other hand, if the time is longer than 300 seconds, the strength of the substrate may decrease due to excessive progress of the etching process.

On the other hand, examples of the electrolytic solution for electrolytic etching include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid and hydrofluoric acid, and alcohols. These may be used alone or in combination of two or more.

Among the above-mentioned electrolytic solutions, a solution containing hydrogen fluoride, sulfuric acid and alcohol is suitable for the method of the present invention.

Hydrogen fluoride itself can be used as hydrogen fluoride when preparing a solution containing hydrogen fluoride, sulfuric acid, and alcohol, or hydrogen fluoride which is an aqueous solution of hydrogen fluoride can be used. It can also be used in the form.

From a practical point of view, the solution containing hydrogen fluoride, sulfuric acid and alcohol is preferably a mixture obtained by mixing alcohol with hydrofluoric acid and sulfuric acid, and if necessary, with another inorganic acid. It is also possible to mix nitric acid, hydrochloric acid and the like.

Hereinafter, as an example of electrolytic etching, a case where the electrolytic solution is a solution containing hydrogen fluoride, sulfuric acid and alcohol will be described in detail. However, the electrolytic etching employed in the method of the present invention is not limited to this.

The concentration of hydrogen fluoride in the solution containing hydrogen fluoride, sulfuric acid and alcohol is usually 1 to 3 mol%, preferably 1 to 2 mol%.

When a solution consisting of hydrogen fluoride, sulfuric acid and alcohol is prepared substantially using hydrofluoric acid, hydrofluoric acid is added so that the concentration of hydrogen fluoride after mixing falls within the above range. It is better to prepare and use it.

The sulfuric acid concentration in the solution of hydrogen fluoride, sulfuric acid and alcohol is usually 5 to 10 mol%, preferably 6 to 8 mol%.

The alcohol is not particularly limited as long as it does not impair the object of the present invention, and examples thereof include methanol, ethanol, propanol and butanol. Among them, methanol is particularly preferable.

In this case, a counter electrode is provided in the solution of hydrogen fluoride, sulfuric acid and alcohol so that the base material is the positive electrode and the counter electrode is the negative electrode, and the surface of the base material is Perform electrolytic etching.

The material of the electrode is not particularly limited as long as it does not generate a substance which inhibits the surface of the base material during electrolytic etching, such as gas, and is not particularly limited.
Examples thereof include stainless steel.

The voltage in the electrolytic etching is usually preferably 3 to 10 V, and particularly preferably 4 to 10 V.
When the voltage is lower than 3V, the etching rate is slow and inefficient. When the voltage is higher than 10 V, the etching rate becomes too fast and the controllability is poor.
It may etch more than necessary.

[0084] current in the electrolytic etching is preferably current per unit area is 0.01~5A / cm ^2, in particular, 0.1~1A / cm ² is preferred. If the current per unit area is less than 0.01 A / cm ² , etching will not be performed sufficiently. Further, if the current per unit area is larger than 5 A / cm ² , etching may proceed excessively and the strength of the substrate may be lowered.

The processing time in the electrolytic etching is
Although it cannot be determined unconditionally depending on the shape of the base material and the magnitude of the electric current, it is usually preferably 0.1 to 60 minutes, and particularly preferably 1 to 30 minutes.

Examples of the dry etching include plasma etching.

In the plasma etching treatment, for example, an inert gas such as argon or nitrogen gas, carbon tetrafluoride, hydrogen gas, oxygen gas, carbon monoxide gas, carbon dioxide gas, methanol gas, water vapor, or these And a plasma such as a mixture thereof. Among them, argon, hydrogen gas and oxygen gas are particularly preferable.

The method for plasma conversion is not particularly limited, and plasma processing methods by various methods such as a plasma conversion method used for a general vapor phase synthesis method of diamond or diamond film can be applied. Specifically, for example, microwave plasma CVD method, high frequency plasma C
The VD method, the hot filament method, the ECR method and the like, or a combination method thereof and the like can be mentioned. Among these, the microwave plasma CVD method and the high frequency plasma CVD method are particularly preferable. Further, if the same CVD method as that used in the vapor phase synthesis of diamond, which will be described later, is adopted, it is convenient in terms of device configuration.

The reaction conditions for the etching treatment with plasma may be those conventionally used. For example, the processing pressure is 10 to 100.
A range of torr is preferred. When the pressure is higher than the above range, the controllability of the treatment is poor, and when it is low, the treatment takes time. The temperature of the surface of the intermediate layer is 500 to 1,10.
Within the range of 0 ° C, preferably 700 to 900 ° C. When the temperature is higher than the above range, the controllability of the treatment is poor and the reproducibility is poor, and when the temperature is low, the treatment takes a long time. The processing time is 1 minute to 200 minutes, preferably 60 minutes.

In the method of the present invention, the etching treatment as described above removes the metal such as cobalt that causes a harmful binding phase when forming the diamond film on the substrate, and Unevenness and pores are generated on the surface of the base material. As a result, at the time of synthesizing the diamond film by the vapor phase method, which will be described later, the produced diamond film enters the surface irregularities and pores, and the diamond film having excellent adhesion to the base material can be synthesized.

-Substrate scratching treatment-The scratching treatment is not particularly limited as long as it is a method capable of scratching the surface of the substrate. For example, an abrasive is dispersed in an organic solvent such as acetone. Examples of the method include a method in which the substrate is placed in the solution and ultrasonic cleaning is performed, a hand polishing method in which the substrate is placed on a support table coated with an abrasive and the substrate and the abrasive are manually rubbed together.

Examples of the polishing agent used for the scratching treatment include diamond powder and SiC powder. Among them, diamond powder is particularly preferable.

When the above ultrasonic cleaning is carried out, the dispersion concentration of the abrasive in the organic solvent is 0.05 to 1
It is preferably 0 g / 100 cc. If the dispersion concentration of the abrasive is less than 0.05 g / 100 cc, the effect of scratching is not sufficient. Further, the dispersion concentration of the polishing agent is 10
Even if it exceeds g / 100 cc, no further effect can be obtained.

The cleaning time for the ultrasonic cleaning is usually 15 seconds to 2 hours, preferably 30 seconds to 60 hours.
Minutes are preferred. If the cleaning time is less than 15 seconds,
The surface of the substrate may not be sufficiently scratched. Further, when the cleaning time is longer than 2 hours, the effect is equivalent to the effect obtained when the cleaning is performed for 2 hours, and further effect due to the long cleaning may not be obtained.

In the case of carrying out the ultrasonic cleaning, it is preferable that after the ultrasonic cleaning, the substrate is cleaned with an organic solvent such as acetone for several minutes to remove the polishing agent adhering to the substrate.

Further, in the above hand polishing method, generally, the polishing agent is dispersed in an organic solvent such as water or alcohol, and the obtained dispersion solution is applied onto a support such as glass. Then, the substrate is placed on a support table coated with the dispersion solution, and the substrate and the dispersion solution are manually rubbed and polished.

In the above hand polishing method, the polishing time is usually preferably 10 seconds to 5 minutes. If the polishing time is shorter than 10 seconds, sufficient surface treatment cannot be performed. If the polishing time is longer than 5 minutes, the surface of the substrate may be scratched more than necessary and the substrate may be scraped off.

(4) Diamond Synthesis In the present invention, the surface of the substrate is coated with a thin layer of diamonds.

The diamonds referred to here include, in addition to diamond, diamond partially containing diamond-like carbon and diamond-like carbon.

Various methods have been heretofore known for forming a thin layer of diamonds, and there is no particular limitation. In the method of the present invention, a carbon source gas is used as shown below. The vapor phase synthesis method can be preferably adopted.

Examples of the carbon source gas include paraffinic hydrocarbons such as methane, ethane, propane and butane; olefinic hydrocarbons such as ethylene, propylene and butylene; acetylene hydrocarbons such as acetylene and allylene; butadiene. Diolefin hydrocarbons such as allene; cyclopropane, cyclobutane, cyclopentane,
Alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as cyclobutadiene, benzene, toluene, xylene, and naphthalene; ketones such as acetone, diethyl ketone, benzophenone; alcohols such as methanol and ethanol; other oxygen-containing compounds Hydrocarbons; amines such as trimethylamine and triethylamine; other nitrogen-containing hydrocarbons; carbon dioxide gas, carbon monoxide, carbon peroxide and the like. Further, the above various compounds may be mixed and used.

Among these, preferred are paraffinic hydrocarbons such as methane, ethane and propane, alcohols such as ethanol and methanol, ketones such as acetone and benzophenone, amines such as trimethylamine and triethylamine, carbon dioxide, and It is carbon oxide, and carbon monoxide is particularly preferable.

Incidentally, these may be used alone,
You may use together 2 or more types as mixed gas.

These may be mixed with an active gas such as hydrogen or an inert gas such as helium, argon, neon, xenon or nitrogen.

A known method for forming the thin layer of diamonds, for example, a CVD method, a PVD method, a PCVD method,
Alternatively, various diamond thin-layer vapor phase synthesis methods such as a combination thereof can be used. Among them, various hot filament methods including EACVD method and various methods including thermal plasma method are usually used. DC plasma CV
Microwave plasma CVD including D method and thermal plasma method
The method etc. can be used conveniently.

The conditions for forming the thin layer of diamonds are not particularly limited, and the reaction conditions usually used in the above vapor phase synthesis method can be applied.

For example, the reaction pressure is usually 10 ^-6
-10 ³ Torr is preferable, and especially 1-800 Torr
It is preferably within the range.

When the reaction pressure is lower than 10 ^-6 Torr, the formation rate of a thin layer of diamonds may be slow. If it is higher than 10 ³ Torr, 10
There is no more effect than that obtained at ³ Torr.

The surface temperature of the base material cannot be unconditionally specified because it depends on the means for activating the raw material gas and the like, but it is usually 300 to 1,000 ° C., preferably 450 to 950 ° C. It should be within the range.

If this temperature is lower than 300 ° C.,
Formation of a thin layer of crystalline diamonds may be inadequate. Further, when the temperature exceeds 1,000 ° C., although depending on the concentration of the carbon source gas and the like, etching of the formed thin layer of diamonds and graphitization of diamond are likely to occur.

The reaction time is not particularly limited, and it is preferable to appropriately set it so that the thin layer of diamonds has a desired thickness in accordance with the formation rate of the thin layer of diamonds.

The thickness of the thin layer of diamonds formed on the surface of the base material cannot be uniformly determined because it depends on the purpose of use of the diamond-coated member and the like, but in the case of tools, it is usually 5 μm or more, preferably , 10 to 50
A value of μm or more is suitable. If the thin layer of diamonds is too thin, it may not be possible to sufficiently coat the surface of the substrate.

As described above, according to the method of the present invention,
A diamond coated member can be manufactured.

[0114]

【Example】

(Examples 1 to 3, Comparative Example) WC-5% Co-2.5% T
Using JIS SPGN120308 sharp-edged cutting chips having an iC composition as a base material, the base material processing and the adhesion improving treatment were performed on each of Examples 1 to 3 and Comparative Example.

That is, in Example 1, the blade edge portion of the base material is machined so that the blade edge portion of the base material is lowered at an angle of 2 degrees with respect to the rake face.
An inert gas atmosphere (mixed gas of N ₂ and Ar, which forms an inclined flat surface having a dimension (L1) of 2 mm from the tip of the blade and contains nitrogen and argon. However, N ₂ 100 Tor
r. At a total pressure of 10 atm), heat treatment was performed at 1,400 ° C. for 1 hour to improve adhesion.

For Example 2, the dimension (L1) from the tip of the cutting edge where the cutting edge portion of the base material was machined to descend at an angle of 2 degrees with respect to the rake face was machined. Forms an inclined flat surface of 1 mm and an inclined surface having a dimension (L2) from the tip of the blade of 1 mm, which is inclined at an angle of 5 degrees with respect to the flank in the blade edge portion of the base material, and is Inert gas atmosphere containing argon (mixed gas of N ₂ and Ar. However, N ₂ 100T
orr. Adhesion improvement treatment was performed at 1,400 ° C. for 1 hour at a total pressure of 10 atm.

In Example 3, the cutting edge portion of the base material was not machined, the base material was housed on a BN floor plate placed in a crucible of BN, and an inert gas atmosphere containing nitrogen and argon was used. (A mixed gas of N ₂ and Ar. However, N ₂ 70
Torr. It was heated to 1,400 ° C. for 1 hour at a total pressure of 10 atm), and warped so that the portion having a dimension L from the blade edge of 19.7 mm had a radius of curvature of 5,000 mm. In Comparative Example 1, the base material was not specially processed, and an inert gas atmosphere containing nitrogen and argon (N ₂ and Ar) was used.
Mixed gas with. However, N ₂ 100 Torr. Total pressure 10
Adhesion improving treatment was carried out at 1,400 ° C. for 1 hour.

After each of the above treatments, the surface of the substrate was coated with diamond by the microwave plasma CVD method under the following conditions. The conditions of the microwave plasma CVD method are shown below.

Time: 8 hours Gas: CO / H ₂ = 30/40, 100 SCCM Reactor pressure: 40 Torr Blade temperature: 950 ° C. Substrate position: Chip rake face 2 m from the center of the applicator
lower by m.

With respect to the obtained diamond-coated cutting tip, the distribution of swelling on the rake face, the thickness of the diamond film and the cutting life were evaluated. Each evaluation item will be described below.

-Distribution of Ridge on Rake Face-Even if the height of ridge on the rake face of the cutting edge portion caused by diamond coating is exactly the same, different distributions do not have the same effect on cutting life.

Hereinafter, description will be made with reference to FIGS. 4 and 5.

FIG. 4 and FIG. 5 are sectional views of the diamond-coated cutting tip in which the ridges of the same height are formed on the rake face of the cutting edge (for the purpose of simplifying the display of the diamond film and the substrate, The distinction of the cross-section of the diamond film is omitted, and the swelling of the diamond film is exaggerated in comparison with the chip for the sake of explanation. Board 6 is shown).

Comparing the diamond-coated cutting chips of both figures, the chip of FIG. 4 is not preferable because it clearly has a problem that it is more easily chipped than the chip of FIG.

Therefore, in order to quantitatively evaluate the distribution of the rising, the flatness rate shown by the following equation was defined, and the distribution of the rising was evaluated.

Flatness rate; F = a (S / S ₀ ) × 100 (%) Here, each parameter is as follows. S is the area of the color change area when the tip is pressed against the pressure-sensitive paper with the rake face facing down, and S _O is the area of the color change area when the chip with a flat rake surface is pressed. This is the calculated value of the area of the rake face that can be formed. a is a parameter used to give a positive / negative sign, and is set to +1 when the color gamut is outside the central portion, that is, when the edge is higher than the center, and when the color gamut is in the central portion, that is, However, when the center portion was higher than the edge, it was set to -1. In the case of completely flat, the flatness rate was 100%.

The evaluation results are shown in Table 1 as the flatness rate of the rake face.

-Thickness of the diamond film at the blade edge-Cut the cross section of the tip with a diamond cutter,
The film thickness of the diamond at the tip of the tip was measured by SEM observation. The results are shown in Table 1 as the blade diamond film thickness.

-Cutting life-To evaluate the cutting life of the prepared diamond-coated tip, the diamond-coated tip was attached to a tool holder and aluminum alloy was turned in the cylinder longitudinal direction. Cutting at a cutting speed of 760 m / min, feed of 0.2 mm / rev, and depth of cut of 0.7, the flank wear width is maximum 30
The cutting distance when reaching 0 μm was measured.

Cutting is performed at each corner of the cutting tip,
The average value of the four cutting distances is shown in Table 1 as the cutting life.

[0131]

[Table 1]

[0132]

According to the present invention, the cutting edge portion of the conductive base material is processed into a specific shape in advance,
In the diamond coating by the vapor phase method, it is possible to focus the diamond coating on the cutting edge portion without causing swelling on the rake face of the cutting edge portion. As a result, it is possible to obtain a diamond-coated cutting tool having excellent wear resistance and stability of attachment to a holder or the like, and having a significantly improved cutting life.

[Brief description of drawings]

FIG. 1 is an explanatory view showing chamfering processing in the present invention.

FIG. 2 is an explanatory diagram showing an example of chamfering processing according to the present invention.

FIG. 2 is an explanatory view showing another example of chamfering processing in the present invention.

FIG. 4 is an explanatory diagram of evaluation methods of examples and comparative examples in the present invention.

FIG. 5 is an explanatory diagram of an evaluation method of examples and comparative examples in the present invention.

[Explanation of sign]

1 ... Base material, 2 ... Rake surface, 3 ... Flank surface, 4
... Chamfer formed on rake face, 5 ... Chamfer formed on flank, 6 ... Plate, 7 ... Diamond-coated cutting tip

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Sohiro Nagasa               Idemitsu Mate, 1660 Kamizumi, Sodegaura-shi, Chiba               Real Co., Ltd.                (56) References Japanese Patent Laid-Open No. 62-271605 (JP, A)                 JP 64-51202 (JP, A)                 JP-A-4-146005 (JP, A)

Claims (4)

(57) [Claims] 1. A substrate made of cemented carbide or cermet
From the rake face to the ridgeline of the blade
The angle of the inclined surface with respect to the rake surface
1 to 30 degrees, and the length of the inclined surface is 0.25 to
On a base material which is 3mm, diamond synthesized by the vapor phase method
A diamond-coated cutting tool characterized by being formed by performing a diamond coating . 2. A substrate made of cemented carbide or cermet
A curved surface that descends from the rake face toward the ridge of the blade
The curved surface formed from the ridgeline of the blade
The length toward the rake face is 0.25-3 mm,
A diamond coating is formed by performing diamond synthesis by the vapor phase method on a substrate whose curved surface R satisfies the following formula.
A diamond-coated cutting tool characterized by comprising: Δt = R {1-cos (L / R)} (where Δt is the thickness t of the diamond film coated on the rake face of the cutting edge of the substrate and the diamond film in the central portion of the rake face of the substrate) The difference from the thickness t0 is shown, R shows the radius of curvature of the curved surface, and L shows the length from the blade tip on the curved surface.) 3. The diamond-coated cutting tool according to claim 1, wherein the inclined surface is formed by chamfering. 4. The diamond-coated cutting according to claim 1, wherein the inclined surface is formed by warping.
Tool .