JPH10130821A - Hard-film-coated small-diameter shank tool made of high speed steel, excellent in wear resistance, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-diameter shank tool made of high speed steel, improved in adhesion between an (Al, Ti) (C, N) film and a base material while preventing deterioration in hardness of the base material and making the most of the characteristics of the film and also improved in oxidation resistance and wear resistance to a greater extent, and a useful method for producing such a small-diameter shank tool made of high speed steel. SOLUTION: A metallic intermediate layer having a chemical composition represented by Alx Ti1-x (where 0.05<=x<=0.75 is satisfied) is formed on the surface of a base material for a shank tool to 5-500nm thickness, and a hard film having a chemical composition represented by (Aly Ti1-y ) (Nz C1-z ) (where 0.56<=y<=0.75 and 0.6<=z<=1 are satisfied) is further formed on the above layer, by which the hard-film-coated shank tool is produced. At this time, a high speed steel, in which outside diameter D is <=5mm and the ratio between this outside diameter D and entire length L(mm), D/L, is regulated to <=0.09, is used as a base material, and the metallic intermediate layer and the hard film are formed by performing arc ion plating at -20 to -400V applied voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-diameter shaft tool such as a small-diameter drill and a small-diameter end mill made of high-speed steel, which is coated with a hard coating with good adhesion without lowering the hardness of the base material to improve the performance. The present invention relates to a high-speed steel small-diameter shaft tool coated with a hard film and a useful method for manufacturing such a tool.

[0002]

2. Description of the Related Art Cutting tools that require high wear resistance, such as high-speed steel tools and cemented carbide tools, use Ti
By forming a hard coating such as N or TiC, the wear resistance is improved. Comparing the wear resistance of TiN and TiC, TiN has better heat resistance (oxidation resistance) than TiC, and also suppresses crater wear on the tool rake face due to processing heat and frictional heat during cutting. Moreover, TiN has excellent adhesion to the base material. On the other hand, TiC is TiN
It has higher hardness and shows high durability against flank wear generated on the flank surface in contact with the work material. However, even with TiN having excellent oxidation resistance, the oxidation start temperature is 600.
C., and the Vickers hardness of TiC having a high hardness is about 2,300.

[0003] For these reasons, as a film having both excellent heat resistance and hardness as compared with TiN and TiC, for example, Japanese Patent Application Laid-Open No. 2-194159 discloses a composite nitride or composite carbonitride in which part of Ti is replaced by Al. (Hereinafter, these may be collectively referred to as (Al, Ti) (N, C)), which has an oxidation start temperature of about 8
It has been shown that at 00 ° C., a property of a Vickers hardness of about 3000 is exhibited.

However, the above (Al, Ti) (N,
C) The film has an internal stress of 2 compared to a film made of TiN.
The internal stress increases as the film becomes thicker for the purpose of improving abrasion resistance, and the internal stress causes cracks and peeling of the film. As a result, (Al, Ti)
The (N, C) film is generally used with a thickness smaller than that of TiN, and the fact is that its properties are not sufficiently exhibited.

For the purpose of improving the adhesion between the TiAlN film and the steel substrate, there has also been proposed a method of forming a Ti metal layer at an interface between the film and the substrate with a thickness of 0.5 μm or less (Japanese Patent Laid-Open Publication No. HEI 9 (1994)). No. 4-128362). In this technique, a Ti metal layer is formed as an intermediate layer to form a Ti diffusion layer on both the substrate and the film, thereby improving the adhesion between the substrate and the film. It cannot be said that the adhesion between the substrate and the film is sufficiently improved only by forming the film.

Under these technical backgrounds, the present inventors have been studying the adhesion of the hard coating.
As a part of the research, a hard coating member as disclosed in JP-A-7-310173 has been proposed. This technology is
A metal intermediate layer having a chemical composition represented by Al _x Ti _1-x (where 0.05 ≦ x ≦ 0.75) is formed on the surface of the base material in a thickness of 5 to 5 mm.
(Al _y Ti _1-y ) (N _z C _1-z ) (provided that 0.56 ≦
x ≦ 0.75, 0.6 ≦ y ≦ 1) By forming a hard film having a chemical composition represented by the following formula, the adhesion between the (Al, Ti) (N, C) film and the substrate is improved. Things.

[0007] When a film or a metal intermediate layer is formed on the surface of a substrate, the purpose is to increase the adhesion.
Conventionally, bombardment cleaning of metal ions such as Ti and Al metals using vacuum arc discharge or the like in a coating furnace before vapor deposition has been generally adopted.

The above-mentioned metal ion bombard is described in, for example, “Practical Surface Technology” (Vol. 33, No. 6, 1986, No. 2).
As described in a paper on "multi-arc discharge ion plating" on page 8), the method is carried out by the arc method. Then, an arc discharge is performed at the cathode by using an apparatus introduced in this document, and sputter cleaning is performed by the generated metal ions before vapor deposition. In this case, the gas pressure is 10 ⁻⁴ Torr or less, and the applied voltage (bias voltage) applied to the substrate is −10.
It is generally about 00 to -1300V. Japanese Patent Publication No. 6-74497 discloses a method of cleaning a base material surface with a metal bombard and then forming a ceramic film by a melt deposition method. The applied voltage in this technique is set to -600 to -1000V. Have been.

[0009]

However, using a small-diameter shaft tool such as a small-diameter high-speed steel drill or end mill as a base material by arc ion plating (A).
When an (1, Ti) (N, C) film is deposited, it has been found that the following problems occur with the conventional techniques.

That is, in the arc ion plating method as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-310173, from the viewpoint of increasing the adhesion of the hard film, the arc ion plating method is performed in a range of -600 to -10.
Since a high voltage of about 00 V is applied, there is a problem that the temperature of the metal base material easily rises due to ion bombardment. In addition, even in the case of metal bombard as disclosed in Japanese Patent Publication No. 6-74497, cleaning of the base material surface is performed. Although the effect is large and the adhesion of the hard film is high, the same problem as described above occurs because the arc ion plating method of applying a high voltage of -600 to -1300 V is basically employed. In particular, when the outer diameter is D mm and the overall length is L mm, D is 5 mm.
mm and a D / L of 0.09 or less when applied to small-diameter shaft tools such as high-speed tool steel drills and end mills, the heat capacity of which is small. ), The temperature is excessively tempered as compared with the normal quenching / tempering state, so that the hardness of the tool base material is reduced and the cutting performance is reduced.

FIG. 1 shows the results of measuring the change in temperature at the tip of a drill when metal ion bombardment was performed by installing high-speed steel drills of various shapes in an arc ion plating apparatus. The measurement was performed using a two-color infrared radiation type surface thermometer in a measurement range of 300 ° C to 800 ° C.
The conditions of the metal ion bombard at this time are shown below. (Metal ion bombarding conditions) Ultimate vacuum: 3 × 10 ⁻⁵ Torr Arc evaporation source: One 60 mmφ Al target and one 60 mmφ Ti target were simultaneously used facing each other. Arc current: Al target 150 A, Ti target 100 A Bias voltage: 600 V Distance between target and drill: 100 mm Drill rotation speed: 1 rpm

As is apparent from FIG. 1, in the case of a drill having an outer diameter of 6 mm, the temperature rise of the drill bit due to the metal ion bombardment is moderate, and metal bombardment at a tempering temperature of a high speed steel drill of 550 ° C. or less is possible. On the other hand, when the outer diameter is D mm and the total length is L mm, D is 5 m
In a high-speed steel shaft drill having a D / L of 0.09 or less and a D / L of 0.09 or less, a sharp rise in temperature occurs, and it can be seen that a metal bombard cannot be sufficiently performed at 550 ° C. or less.

In order to respond to the recent increase in efficiency of cutting work, the above-mentioned properties are not sufficient, and the adhesion of the existing film to the substrate is improved, and the oxidation resistance and the wear resistance are improved. There is an urgent need to develop a hard coating that further improves the above and a method for producing the same.

The present invention has been made in view of such circumstances, and its object is to make use of the characteristics of the (Al, Ti) (C, N) film without causing a decrease in the hardness of the substrate. A high-speed steel small-diameter shaft tool with improved adhesion between the coating and the substrate while further improving oxidation resistance and wear resistance, and useful for manufacturing such a high-speed steel small-diameter shaft tool To provide a simple method.

[0015]

The method of manufacturing a high-speed steel small-diameter shaft tool according to the present invention, which has achieved the above objects, comprises the steps of: forming Al _x Ti _1-x (0.05 .Ltoreq.x.ltoreq.0.75) A metal intermediate layer having a chemical composition represented by the following formula:
(Al _y Ti _1-y ) (N _z C _1-z ) (provided that 0.56 ≦
y ≦ 0.75, 0.6 ≦ z ≦ 1) In producing a hard film-coated shaft tool by forming a hard film having a chemical composition represented by the following formula, the outer diameter D is 5 mm or less as the base material. A high-speed steel having a ratio (D / L) of the outer diameter D to the overall length L (mm) of 0.09 or less is used, and the metal intermediate layer and the hard coating are -20 to -400.
The gist lies in the fact that the formation is performed by performing arc ion plating with an applied voltage of V.

In the above-mentioned method of the present invention, it is preferable to use a substrate whose surface has been cleaned by ion bombard cleaning using glow discharge of gas. Further, as such ion bombardment cleaning, specifically, a method using glow discharge of argon gas can be mentioned.

The high-speed steel small-diameter shaft tool manufactured by the above method has a Vickers hardness (Hv) of 30 or less before and after the base material forms the metal intermediate layer and the hard coating, and The substrate has substantially no excessive tempered structure, and the hard film-coated high-speed steel small-diameter shaft tool can achieve the object of the present invention.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors assume that when the outer diameter is D mm and the total length is L mm, D is 5 mm or less and D / L
As a hard coating for improving wear resistance on the surface of base materials such as high-speed steel drills and end mills with a small diameter of 0.09 or less,
(Al, Ti) (C,
N) The conditions of the arc ion plating method were repeatedly studied for the purpose of forming a film with good adhesion without causing a decrease in the hardness of the substrate.

As a result, -20 was added to the surface of the high-speed steel base material.
Arc ion plating was performed at an applied voltage of -400 V, and Al _x Ti _1-x (however,
After forming a metal intermediate layer having a chemical composition represented by 0.05 ≦ x ≦ 0.75) with a thickness of 5 to 500 nm, (Al _y Ti _1-y ) (N _y C _1-Z )
(However, it has been found that the above-mentioned object is excellently achieved by forming a hard film having a chemical composition represented by (0.56 ≦ y ≦ 0.75, 0.6 ≦ Z ≦ 1), The present invention has been completed.

According to the present invention, in the first step, Al _x Ti _1-x (provided that 0.05 ≦ x ≦ 0.7
The metal intermediate layer having the chemical composition represented by 5) is formed to a thickness of 5
When forming at a thickness of up to 500 nm, arc ion plating is performed by applying a low voltage of -20 to -400 V. Therefore, even if the heat capacity of the base material is small, the temperature does not rise to about 550 ° C. or more due to ion bombardment. . as a result,
The high-speed steel as the base material has substantially no excessive tempered structure, and does not cause a decrease in the hardness of the base material. Specifically, a decrease in the hardness of the substrate is suppressed to a Vickers hardness (Hv) of 30 or less. The “excess tempered structure” means a structure that is more tempered than a structure that is normally quenched and tempered for high-speed steel.

With the above applied voltage, the sputtering
Hardly progresses, but rather metal deposition proceeds
Will be. Then, the composition of the metal intermediate layer is changed to Al_x 
Ti _1-x (However, 0.05 ≦ x ≦ 0.75), thickness is 5
５００500 nm, the subsequent second step
(Al_y Ti_1-y ) (N_z C_1-z ) (However,
0.56 ≦ y ≦ 0.75, 0.6 ≦ z ≦ 1)
Adhesion of the hard coating composed of chemical composition will be improved.
You. When forming this hard coating, the same as above
Voltage is -20 to -400V for the reason
There is a need.

As described above, in the present invention, when forming the metal intermediate layer and the hard coating, -20 to -4
It is necessary to perform arc ion plating by applying an applied voltage of 00V. When the applied voltage is higher than -400 V (when it is increased as a negative value), the outer diameter D is 5 m.
m or less, the ratio of this outer diameter D to the total length L (mm) (D / L)
In high-speed steel small-diameter tools having a small heat capacity, such as high-speed steel having a heat resistance of 0.09 or less, the temperature may rise to 550 ° C. or more due to ion bombardment. This causes a decrease in the hardness of the base material. On the other hand, if the applied voltage is lower than -20 V, the electric attraction effect itself at the time of ion plating is reduced, and the adhesion of the metal intermediate layer and the hard coating becomes poor.

The reason why the hard coating according to the present invention can exhibit excellent wear resistance as compared with the conventional coating can be considered as follows. First, the metal intermediate layer formed between the film and the substrate without causing the hardness of the high-speed steel substrate to decrease as described above relieves the stress generated at the interface between the substrate and the hard film, It is considered that one of the reasons is to increase the adhesion by causing mutual diffusion. Further, the metal intermediate layer is coated with a hard coating [that is, (A)
l, Ti) (C, N) film] and A
1Ti metal (metal intermediate layer) and (Al, Ti) (C, N)
One of the possible reasons is that interdiffusion with the film occurs, and it is possible to form a carbon / nitride with higher density and excellent adhesion.

According to the present invention, the adhesion of the hard coating is significantly improved as compared with the conventional method of forming the Ti metal intermediate layer. Like Ti metal, the adhesion is enhanced by the effects of stress relaxation and mutual diffusion, and (Al, Ti) (C,
N) At the interface with the film, the interdiffusion is performed more densely because of the affinity higher than that of Ti metal (Al, Ti).
It is considered that the nucleus of the (C, N) film gives very excellent adhesion since it serves as a nucleus.

In carrying out the method of the present invention, it is preferable to use, as the substrate, a substrate whose surface has been cleaned by ion bombardment cleaning by gas glow discharge. The adhesion can be further increased. The ion bombard cleaning by glow discharge of such gas does not cause the above-described inconvenience caused by the metal ion bombard cleaning. That is, in ion bombardment cleaning by gas glow discharge, gas ions have a smaller mass than metal ions, so even if the bias voltage is set to about −400 to −800 V, which is generally implemented,
The ion bombard cleaning can be performed effectively without raising the substrate temperature to 550 ° C. or higher. Specifically, ion bombard cleaning by glow discharge of argon gas can be mentioned.

In the present invention, the composition of the metal film constituting the metal intermediate layer is such that 0.05 ≦ x in Al _x Ti _1-x .
It is necessary to satisfy ≦ 0.75. This is because x <0.
05, the Al content is too small, and (Al _y Ti
_1-y ) (N _z C _1-z ) (0.56 ≦ y ≦ 0.75,0.
Sufficient adhesion cannot be obtained between the hard coating represented by 6 ≦ z ≦ 1) and the metal intermediate layer. On the other hand, when x> 0.75, at the interface between the metal intermediate layer and the hard coating, a part y> 0.7
5 (Al _y Ti _1-y ) (N _z C _1-z ). That is, the (Al _y Ti _1-y ) (N _z C _1-z ) film has a cubic crystal structure in the composition range of x ≦ 0.75, but changes to hexagonal when y> 0.75. . Therefore, if the value of z exceeds 0.75, carbon / nitride having a different crystal structure is formed at the interface, thereby reducing the adhesion of the film. Hexagonal (Al, Ti) (N, C)
In this case, the film hardness is lowered, and sufficient wear resistance cannot be obtained. Note that the lower limit of x is preferably 0.25, and more preferably 0.56 or more. On the other hand, the upper limit of x is preferably 0.70, and more preferably 0.65 or less.

The thickness of the metal intermediate layer is 5 to 500 nm.
It is necessary to If this thickness is less than 5 nm,
The effect of forming the metal intermediate layer does not appear sufficiently, while 500
If it exceeds nm, cracks may occur in the metal intermediate layer due to impact force, and peeling of the hard coating may occur. The lower limit of the thickness of the metal intermediate layer is preferably 30 nm,
m or more is more desirable. The upper limit of the thickness of the metal intermediate layer is preferably 300 nm, and more preferably 150 nm or less.

In the present invention, the metal composition of the (Al _y Ti _{1 -y} ) (N _z C _{1 -z} ) film formed on the metal intermediate layer is in the range of 0.56 ≦ y ≦ 0.75. It is necessary. This is because when y <0.56, the oxidation resistance of the film is not sufficient, and when y> 0.75, the crystal structure changes and the film hardness decreases, so that sufficient abrasion resistance cannot be obtained. . In order to combine oxidation resistance and film hardness, y
Is preferably 0.58, more preferably 0.59 or more. The upper limit of y is set to 0.
70 is preferable, and it is more preferable that it is 0.65 or less.

The metal of Al or Ti in the (Al _y Ti _1-y ) (N _z C _1-z ) film gives an excellent wear-resistant film as a nitride or carbonitride. : C = 1: 0 to 0.6: 0.4 [N _z C _1-z : (0.
6 ≦ z ≦ 1)]. This is because z <
This is because when it is 0.6, the oxidation resistance of the film is reduced. The lower limit of z is preferably 0.8 in consideration of oxidation resistance.

Regarding the thickness of the (Al _y Ti _1-y ) (N _z C _1-z ) film, if it is too thin, the abrasion resistance is insufficient, while if it is too thick, cracks easily occur in the film due to impact force. 0.8 to 20 μm
m is preferable. Further, in order to make use of the characteristics of the cutting edge inherent in the tool base material and to obtain excellent wear resistance, the thickness of the hard coating is preferably 1 μm or more, more preferably 2 μm or more. On the other hand, the upper limit is preferably 12 μm,
It is more preferably at most 8 μm.

When the metal intermediate layer is formed, the metal intermediate layer is obtained by coating the metal components of Al and Ti ionized by an arc discharge using the cathode as an evaporation source in a vacuum under an applied voltage specified in the present invention. At this time, if a target having the same metal composition as the target coating composition is used, no deviation in the composition of the cathode material occurs, so that a coating having a stable composition is easily obtained.

On the other hand, (Al _y Ti _1-y ) (N _z C _1-z )
When a film is formed, metal components of Al and Ti ionized by arc discharge using a cathode as an evaporation source under an applied voltage specified in the present invention are mixed with an N ₂ atmosphere and / or
Alternatively, it can be obtained by performing ion plating in a nitriding and / or carbonizing atmosphere such as a CH ₄ atmosphere. At this time, if a target having the same metal composition as the intended coating composition is used, the composition of the cathode material can be reduced. Since no displacement occurs, a film having a stable composition is easily obtained. The gas pressure at the time of ion plating for forming the metal charcoal / nitride is not particularly limited, but is preferably about 1 × 10 ^-3 to 1 × 10 ^-1 Torr. It is easy to obtain a hard coating having excellent wear resistance.

Next, the present invention will be described with reference to Examples. However, the present invention is not limited to the following Examples, and it is needless to say that the present invention can be practiced with appropriate modifications within a range that can be adapted to the purpose described above. , All of which are included in the technical scope of the present invention.

[0034]

EXAMPLE 1 In order to investigate the temperature change of the substrate during arc ion plating, a high-speed steel drill (Vickers hardness 850) corresponding to JIS standard SKH51 was used. The outer diameter was 3 mm and the length was 70 mm. A cylindrical base material whose surface is mirror-polished in size is set in an arc ion plating apparatus, and various bias voltages are applied to the base material, and the base part of the base material when arc ion plating is performed. Was measured for temperature change. The result is shown in FIG. The measurement at this time was performed using a two-color infrared radiation type surface thermometer in a measurement range of 300 ° C to 800 ° C. The conditions of arc ion plating are shown below. (Arc ion plating conditions) Ultimate vacuum: 3 × 10 ⁻⁵ Torr Arc evaporation source: One 60 mmφ Al target and one 60 mm ATi target were simultaneously used facing each other. Arc current: Al target 150A, Ti target 100A Distance between target and drill: 100 mm Drill rotation speed: 1 rpm

As is clear from FIG. 2, when the bias voltage is set to -500 V or -1300 V as in the conventional case, the temperature of the front end of the base material rapidly rises to 550 ° C. or more, and the hardness of the base material decreases. It is expected to be. In contrast, the range defined by the present invention, -20 to -400
In arc ion plating at an applied voltage of V, the temperature rise at the base end of the base material is moderate, and arc ion plating can be sufficiently performed at a temperature lower than 550 ° C., the tempering temperature of a high-speed steel drill. Recognize.

Example 2 In order to examine the adhesion of the coating, a high speed steel (Vickers hardness 850) corresponding to JIS standard SKH51 was used, and the outer diameter was 3
mm × Length: A cylindrical base material having a size of 70 mm and having a mirror-polished surface was charged into an arc discharge type ion plating apparatus, heated to 400 ° C., and the cathode was evaporated in a vacuum, and Various bias voltages of 0 to -1000 V were applied to the base material, and metal intermediate layers having various compositions and thicknesses were formed by ion plating with metal ions. In this case, for some of the samples, Ar gas was introduced as a reaction gas prior to ion plating with metal ions, and 7 × 10 ⁻² To
An atmosphere of rr was applied, and a bias voltage of -400 V was applied to the substrate to cause glow discharge of Ar gas, thereby performing ion bombard cleaning of the substrate.

Thereafter, while further evaporating the cathode, N ₂ gas or N ₂ / CH ₄ mixed gas is introduced as a reaction gas, the atmosphere is set to 7 × 10 ^-3 Torr, and a bias of -150 V is applied to the base material. By applying a voltage, a high-speed tool steel substrate coated with 3 μm of films having various compositions shown in Table 1 below was produced. The composition of the film was determined by electron probe X-ray microanalysis and Auger electron spectroscopy, and the thickness of the metal intermediate layer was determined by a cross-sectional image using a transmission electron microscope and a high-resolution scanning electron microscope. The composition of the metal intermediate layer was determined by an energy dispersive X-ray analysis method in a transmission electron microscope and Auger electron spectroscopy of a prototype member having only a metal intermediate layer formed on a substrate. When the crystal structure of the film obtained in this example was examined by X-ray diffraction, it was confirmed that all of the films showed the same diffraction pattern as TiN and were cubic.

Using a conical diamond indenter having a tip diameter of 0.2 mm, a load speed of 100 N / min was applied to a position 10 mm from the tip of the coating coating portion of these prototype members.
When a scratch test was performed under the conditions of a scratching speed of 10 mm / min, the results shown in Table 1 below were obtained.

[0039]

[Table 1]

As is clear from Table 1, (A)
It can be seen that all of the (1, Ti) (C, N) films (Nos. 1, 17) have poor adhesion. No. No. 2 is a comparative example in which the Al ratio of the metal intermediate layer is too small. 9 is a comparative example in which the Al ratio of the metal intermediate layer is too large, No. 7 is a comparative example in which the thickness of the metal intermediate layer is too thin. No. 8 is a comparative example in which the thickness of the metal intermediate layer is too large. Nos. 13 and 14 are comparative examples in which the bias voltage at the time of forming the metal intermediate layer was too high. Reference numeral 15 is a comparative example in which the bias voltage at the time of forming the metal intermediate layer is too small. In each case, the value of the critical load at which the film peels from the substrate in the scratch test is poor, and the object of the present invention cannot be achieved. On the other hand, Nos. Satisfying the requirements specified in the present invention. Those of 3 to 6, 10 to 12, and 16 show high critical load values, and it can be seen that the adhesion of the film is excellent.

Example 3 Using the same prototype member as in Example 2, the hardness was measured at a position of 0.5 mm from the outer periphery at a cross section of 1 mm from the tip using a Vickers hardness meter with a load of 10 kg. The results obtained are shown in Table 1 above.

As is clear from Table 1, the comparative example No.
In Nos. 13 and 14, since the bias voltage at the time of forming the metal intermediate layer was too large, the high-speed steel base material was exposed to a high temperature and was excessively tempered, causing a significant decrease in hardness of Hv30 or more. In contrast, Examples 3 to 6, 10 to 12, and 16
Indicates that substantially no excessive tempered structure is generated, and the hardness of the high-speed steel hardly decreases.

Example 4 A high-speed steel equivalent to JIS standard SKH51 was used as a substrate, a straight drill having an outer diameter of 2 mm and a length of 55 mm according to JIS was produced, and this drill was used as a substrate. In the same manner as in Example 1, a metal intermediate layer shown in Table 2 below was formed, and a hard coating was formed thereon with a thickness of 2 μm.

Using each of the three drills coated with the hard coating obtained, a cutting test was performed under the following conditions, and the number of drills up to the life was measured. The average of the obtained results is also shown in Table 2 below. (Cutting conditions) Work material: S55C (hardness HB230) Hole depth: 8 mm, through hole Cutting speed: 30 m / min Feed: 0.10 mm / rev Cutting oil: emulsion

[0045]

[Table 2]

As is clear from Table 2, 3, 4,
In the example of No. 6, the number of perforations is larger than that of the conventional example (Nos. 1 and 2), and it can be seen that excellent wear resistance is obtained. On the other hand, No. No. 5 is a comparative example in which the bias voltage at the time of forming the metal intermediate layer was too small. No. 7 is a comparative example in which the bias voltage at the time of forming the metal intermediate layer is too large, and it can be seen that the number of holes is small and the wear resistance is not sufficient.

Example 5 Using a high-speed steel equivalent to JIS SKH55 as a base material, a two-flute end mill having an outer diameter of 3 mm was manufactured, and this end mill was used as a base material in the same manner as in Example 1, A metal intermediate layer shown in Table 3 below was formed, and a hard film was formed thereon by 2 μm.
m.

Using one of the obtained hard film-coated end mills, a cutting test was performed under the following conditions, and the cutting length up to breakage was measured. Table 3 also shows the obtained results. (Cutting conditions) Work material: S50C (hardness HB220) Cutting method: Grooving, depth 1 mm x width 3 mm Cutting speed: 40 m / min Feed: 100 mm / min Cutting oil: emulsion

[0049]

[Table 3]

As is clear from Table 3, 3,5
It can be seen that the example of Example 1 has a longer cutting length than the conventional examples (Nos. 1 and 2) and that excellent wear resistance is obtained.
On the other hand, no. No. 4 is a comparative example in which the bias voltage at the time of forming the metal intermediate layer is too small. 6 is a comparative example in which the bias voltage when forming the metal intermediate layer is too large;
In each case, the cutting length is short and the wear resistance is not sufficient.

[0051]

The present invention is configured as described above.
The hard film-coated high-speed steel small-diameter shaft tool improved in oxidation resistance and wear resistance by extremely excellent adhesion without reducing the hardness of the tool base material.

[Brief description of the drawings]

FIG. 1 is a graph showing a change in temperature at the tip of a drill when metal ion bombardment is performed on a high-speed steel drill having various shapes.

FIG. 2 is a graph showing a temperature change at a front end portion of a base material when various bias voltages are applied to the base material to perform arc ion plating.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Hayasaki 179-1 Kanegasaki Nishiike, Uozumi-cho, Akashi-shi, Hyogo Prefecture Shinko Kobelco Tool Co., Ltd.

Claims (4)

[Claims] 1. A metal intermediate layer having a chemical composition represented by Al _x Ti _1-x (where 0.05 ≦ x ≦ 0.75) is provided on a base material surface of a shaft tool with a thickness of 5 to 5 mm.
(Al _y Ti _1-y ) (N _z C _1-z ) (provided that 0.56 ≦
y ≦ 0.75, 0.6 ≦ z ≦ 1) In producing a hard film-coated shaft tool by forming a hard film having a chemical composition represented by the following formula, the outer diameter D is 5 mm or less as the base material; A high-speed steel having a ratio (D / L) of the outer diameter D to the total length L (mm) of 0.09 or less is used, and the metal intermediate layer and the hard coating are arc ionized at an applied voltage of -20 to -400V. A method for producing a hard film-coated high-speed steel small-diameter shaft tool having excellent wear resistance, which is formed by plating. 2. The method according to claim 1, wherein the base material is one whose surface has been cleaned by ion bombardment cleaning by gas glow discharge. 3. The method according to claim 2, wherein said ion bombarding cleaning is performed by glow discharge of argon gas. 4. A metal intermediate layer having a chemical composition represented by Al _x Ti _1-x (where 0.05 ≦ x ≦ 0.75) is provided on a base material surface of a shaft tool with a thickness of 5 to 5 mm.
(Al _y Ti _1-y ) (N _z C _1-z ) (provided that 0.56 ≦
y ≦ 0.75, 0.6 ≦ z ≦ 1) A hard film having a chemical composition represented by the following formula is formed. As the substrate, the outer diameter D is 5 mm or less, and the outer diameter D and the total length L In addition to using a high-speed steel having a (mm) ratio (D / L) of 0.09 or less, the base material has a Vickers hardness (Hv) of 30 or less in hardness before and after forming the metal intermediate layer and the hard coating. A small-diameter shaft tool made of a high-speed steel coated with a hard film having excellent wear resistance, wherein the tool has the following characteristics and the substrate has substantially no excessive tempered structure.