JPH04310302A - Cutting tool and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool having a thin film of high hardness formed on the surface of a base material, and a method for manufacturing the same.

0002

2. Description of the Related Art As this type of cutting tool, one in which a crystalline aluminum oxide thin film is formed on the surface of a base material such as metal or ceramics is known. In this case, a crystalline aluminum oxide thin film may be formed directly on the surface of the base material, but other thin films (for example, titanium thin film, titanium nitride thin film, titanium carbide thin film, etc.) may be formed as an intermediate layer between them.
may also form.

0003

[Problems to be Solved by the Invention] Incidentally, since the crystalline aluminum oxide thin film has a relatively large crystal grain size, its surface is rough (center line average roughness Ra is 0.3).
(on the order of μm), therefore, cutting tools having such crystalline aluminum oxide thin films formed on their surfaces have not always had sufficiently satisfactory cutting performance and durability.

[0004] In addition, crystalline aluminum oxide thin films have coarse crystal grains, which may result in missing particles, or grain boundaries may occur between the crystal grains, causing fractures or internal defects originating from the grain boundaries. There was a problem that it was easy to use.

Furthermore, although crystalline aluminum oxide thin films are generally formed by thermal CVD, crystalline aluminum oxide thin films have a slow film growth rate (approximately 2 to 3 angstroms/second), so it is difficult to increase the film thickness. However, the film forming process takes a long time. In addition, thermal CV
When using the D method, the film formation temperature is as high as 1000°C or higher, so the base material must of course be limited to heat-resistant materials that can withstand such high temperatures, and reheat treatment may be required after film formation. , the base material may be thermally deformed, or even
During the film formation process, interdiffusion occurs at the boundary between the base material and the crystalline aluminum oxide thin film (or the boundary between the intermediate layer and the crystalline aluminum oxide thin film if an intermediate layer is provided), and as a result, at the boundary between them, There was also the problem that embrittlement occurred and the thin film was likely to peel off.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a cutting tool that provides excellent cutting performance and durability, and a method for manufacturing the same.

[0007]

[Means for Solving the Problems] The cutting tool of the invention of claim 1 forms a crystalline aluminum oxide thin film on the surface of a base material made of metal or ceramics, and also forms an amorphous oxide film on the surface of the crystalline aluminum oxide thin film. It is characterized by forming a thin aluminum film.

[0008] Furthermore, in the manufacturing method of the invention of claim 2, when manufacturing the cutting tool of claim 1, the base material is heated to a predetermined film forming temperature and crystals are first formed on the surface of the base material by an ion plating method. This method is characterized by forming a crystalline aluminum oxide thin film, and then lowering the base material temperature and forming an amorphous aluminum oxide thin film on the surface of the crystalline aluminum oxide thin film using the same ion plating method.

[0009]

[Function] Although the hardness of an amorphous aluminum oxide thin film is lower than that of a crystalline aluminum oxide thin film, its surface is extremely smooth compared to a crystalline aluminum oxide thin film. Because of this, no noticeable grain boundaries occur, making it difficult for defects to occur inside the film. Therefore, cutting tools with such an amorphous aluminum oxide thin film formed as the outermost layer have excellent durability. becomes. In addition, since a highly hard crystalline aluminum oxide thin film is formed on the lower layer side of the amorphous aluminum oxide thin film, cutting performance and durability are maintained by the crystalline aluminum oxide thin film even after the amorphous aluminum oxide thin film is worn away. Ru. Furthermore, by forming both the crystalline aluminum oxide thin film and the amorphous aluminum oxide thin film by the ion plating method, the film forming temperature is lowered and the film forming rate is improved compared to the case of using the thermal CVD method.

0010

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the structure of a cutting tool according to an embodiment of the present invention, in which reference numeral 1 denotes a base material made of metal or ceramics, 2 a crystalline aluminum oxide thin film formed on the surface of the base material 1, 3 is the crystalline aluminum oxide thin film 2
It is an amorphous (non-crystalline) aluminum oxide thin film formed on the surface of. The thickness of the crystalline aluminum oxide thin film 2 and the amorphous aluminum oxide thin film 3 may be set as appropriate;
The latter is preferably set in the range of 20 μm, preferably 1 to 10 μm, and the latter is preferably set in the range of 0.1 to 20 μm, preferably 0.2 to 10 μm.

In the case shown in FIG. 1, a crystalline aluminum oxide thin film 2 is first formed on the surface of a base material 1, and then an amorphous aluminum oxide thin film 3 is formed on the surface of the base material 1. , 3, but by forming these thin films 2 and 3 continuously, the crystalline aluminum oxide thin film 2 becomes an amorphous aluminum oxide thin film as shown in FIG. It may be configured to change continuously to 3.

1 and 2 are examples in which the crystalline aluminum oxide thin film 2 is directly formed on the surface of the base material 1, but as shown in FIGS. 3 and 4, , another thin film 4 may be formed as an intermediate layer between the base material 1 and the crystalline aluminum oxide thin film 2.

[0013] Each of the above-mentioned cutting tools is, for example, a high frequency excitation type ion plating device as shown in FIG.
Using an arc discharge type ion plating apparatus as shown in FIG.
By sequentially forming the amorphous aluminum oxide thin film 3 and the amorphous aluminum oxide thin film 3, it can be manufactured efficiently.

The high frequency excitation type ion plating apparatus shown in FIG. 5 introduces a reactive gas G such as argon gas and oxygen gas into a vacuum chamber 5 from a gas introduction pipe 6 to maintain the inside of the vacuum chamber 5 at a predetermined pressure, for example 1 to 9. ×10
The evaporated material M (
Aluminum or aluminum oxide) is melted and evaporated by an electron gun 9, and the evaporated evaporation material M and reaction gas G are heated to
High frequency coil 11 to which a high frequency of 3.56 MHz is applied
The positive ions are ionized positively by the heater 1 while a negative voltage is applied by the DC power supply 12.
3, it is configured to be adsorbed onto the base material 1 which is being heated.

Furthermore, the arc discharge type ion plating apparatus shown in FIG.
6 to positively ionize the evaporation material M and the reaction gas G, and the other configurations are the same as the high frequency excitation type ion plating apparatus.

[0016]Whether using a high-frequency excitation type ion plating device or an arc discharge type ion plating device, the film forming temperature when forming the crystalline aluminum oxide thin film 2 is 450° C. or higher, for example, 550° C.
The film forming temperature when forming the amorphous aluminum oxide thin film 3 is lower than that, at 200 to 450°C.
Set within a range of degrees. This is because if the film formation temperature when forming the amorphous aluminum oxide thin film 3 is a high temperature of 450° C. or higher, the formed thin film may crystallize and become a crystalline aluminum oxide thin film.

Note that not only the film forming temperature but also the ionization of the evaporation material M and the reaction gas G may be controlled at the same time as necessary. That is, when forming the crystalline aluminum oxide thin film 2, ionization is relatively promoted, and when forming the amorphous aluminum oxide thin film 3, the ionization is relatively suppressed. 16, the operation of the electron gun 9, and the amount of introduced reaction gas G may be controlled.

In addition, as shown in FIGS. 2 and 4, when the crystalline aluminum oxide thin film 2 is continuously changed to the amorphous aluminum oxide thin film 3, the film is continuously changed so that the film forming temperature gradually decreases. All you have to do is change it to
In that case, the ionization of the evaporated material M and the reaction gas G may be continuously changed as needed so as to gradually become smaller.

Furthermore, as shown in FIGS. 3 and 4,
When forming another thin film 4 as an intermediate layer between the base material 1 and the crystalline aluminum oxide thin film 2, the thin film 4 is formed on the surface of the base material 1 in advance, and the surface of the thin film 4 is Crystalline aluminum oxide thin film 2 is prepared as described above.
, and further, an amorphous aluminum oxide thin film 3 may be formed on the surface thereof.

Although the amorphous aluminum oxide thin film 3 as the outermost layer in the above-mentioned cutting tool has a lower hardness than the crystalline aluminum oxide thin film 2, since the amorphous aluminum oxide thin film 3 is non-crystalline, it is not crystalline. Its surface is extremely smooth compared to the aluminum oxide thin film 2. That is, as mentioned above, while the conventional crystalline aluminum oxide thin film has coarse crystal grains and its center line average roughness Ra is about 0.3 μm,
The amorphous aluminum oxide thin film 3 has a center line average roughness Ra of approximately 0.02 to 0.04 μm, which is sufficiently smooth. Moreover, since the amorphous aluminum oxide thin film 3 is non-crystalline and no noticeable grain boundaries occur, defects are unlikely to occur inside the film.
A cutting tool in which the outermost layer is formed has a sufficiently reduced frictional resistance generated between the cutting tool and the workpiece during cutting.

Furthermore, since the crystalline aluminum oxide thin film 2 formed on the lower layer side of the amorphous aluminum oxide thin film 3 is formed at a relatively low temperature by the ion plating method, it can be formed by the conventional thermal CVD method. The crystal grains are smaller than those in the case, making it dense and less likely to cause internal defects. When the amorphous aluminum oxide thin film 3 is worn out, the crystalline aluminum oxide thin film 2 maintains cutting performance and durability. As shown, the wear resistance is improved compared to the conventional one, and excellent cutting performance and durability can be obtained.

The above cutting tool also has a crystalline aluminum oxide thin film 2 and an amorphous aluminum oxide thin film 3.
It is efficiently manufactured by sequentially depositing both of these films using the ion plating method, but the film formation temperature at that time is lower than that of the conventional method of depositing a crystalline aluminum oxide thin film using the thermal CVD method. Therefore, the heat resistance required for the base material 1 is reduced, the range of application of the base material 1 is expanded, heat treatment after film formation is not required, and thermal deformation of the base material 1 is reduced. Furthermore, during film formation, mutual diffusion between the base material 1 (or other thin film 4 as an intermediate layer) and the crystalline aluminum oxide thin film 2 becomes difficult to occur, and therefore the interface between them As a result, peeling of each thin film is less likely to occur.

Furthermore, when forming the crystalline aluminum oxide thin film 2 and the amorphous aluminum oxide thin film 3 by the ion plating method, a film forming rate of about 30 to 50 angstroms/second can be obtained, and the thermal It is possible to form a film at a much higher speed than when using the CVD method, and as a result, productivity can be greatly improved and product costs can be reduced.

Tests conducted to demonstrate the wear resistance of the cutting tool of the present invention and their results will be described below.

(Test Example) The following five samples A, B,
C, D, and E were prepared and cut under the following cutting conditions, and then the flank wear amount of each was measured. The measurement results are shown in FIG. Sample A (product of the present invention): A throw-away chip in which a crystalline aluminum oxide thin film was formed on the surface of the base material by an ion plating method, and an amorphous aluminum oxide thin film was also formed on the surface by the same ion plating method. Sample B (comparative product): A throw-away chip in which only a thin crystalline aluminum oxide film was formed on the surface of the base material by ion plating. Sample C (comparative product): Throw-away chip with only an amorphous aluminum oxide thin film formed on the surface of the base material by ion plating. Sample D (conventional product): Throw-away chip with only a crystalline aluminum oxide thin film formed on the surface of the base material by thermal CVD. Sample E (conventional product): Throw-away chip with only a thin titanium nitride film formed on the surface of the base material by thermal CVD. Cutting conditions: Work material S45C, cutting speed 250 m/min, feed 0.46 mm/rev. , depth of cut 1.5 mm, cutting time 9 minutes (3 measurements taken every 3 minutes). From the test results shown in FIG. 7, Sample A, which is a product of the present invention, has a smaller amount of flank wear than Samples D and E, which are conventional products, and Samples B and C, which are comparative products.
It was confirmed that it has excellent durability.

[0026] A detailed study of this test result shows that at the beginning of cutting, sample C has a smaller amount of wear than sample B, but as the cutting time increases, sample B becomes less worn than sample C. The amount of wear is reduced. In other words, if the cutting time is short, sample C with an amorphous aluminum oxide thin film is more durable, but if the cutting time is long, sample B with a crystalline aluminum oxide thin film is more durable. You will be better at it. Sample A, which is a product of the present invention, combines the advantages of both, and while the cutting time is short, durability is ensured by the amorphous aluminum oxide thin film 3 formed on the outermost layer, while the cutting time is long. After the amorphous aluminum oxide thin film 3 is worn out, durability is further ensured by the crystalline aluminum oxide thin film 2 having higher hardness, and as a result, excellent durability can be obtained regardless of the length of cutting time.

[0027]

[Effect of the invention] As explained in detail above, claim 1
In the cutting tool of the invention, a crystalline aluminum oxide thin film is formed directly or indirectly through another thin film as an intermediate layer on the surface of a base material made of metal or ceramics, and the crystalline aluminum oxide thin film is Since it is made by forming an amorphous aluminum oxide thin film on the surface of the thin film, it is non-crystalline, so the surface is extremely smooth, and defects are hard to occur inside the film. In addition, after the amorphous aluminum oxide thin film is worn out due to long-term cutting, durability is further ensured by the crystalline aluminum oxide thin film with higher hardness, resulting in excellent cutting performance and durability. This has the effect that it is possible to obtain the following.

Further, in the manufacturing method of the invention of claim 2, the base material is heated to a predetermined film forming temperature, a crystalline aluminum oxide thin film is first formed on the surface of the base material by an ion plating method, and then the base material temperature is Since the amorphous aluminum oxide thin film is layered on the surface of the crystalline aluminum oxide thin film using the same ion plating method, both the crystalline aluminum oxide thin film and the amorphous aluminum oxide thin film can be formed continuously. It is possible to form a film at high speed and has excellent productivity, and since the film formation temperature is sufficiently lower than that of the conventional thermal CVD method, the heat resistance of the base material is reduced. Not only does the range of application expand, but it also has excellent effects such as making it difficult for mutual diffusion to occur between the base material and the thin film during film formation, making it difficult for embrittlement at the interface and peeling of the thin film to occur.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing the structure of a cutting tool that is an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing the structure of a cutting tool according to another embodiment of the present invention.

FIG. 3 is a partial cross-sectional view showing the structure of a cutting tool that is still another embodiment of the present invention.

FIG. 4 is a partial cross-sectional view showing the structure of a cutting tool that is still another embodiment of the present invention.

FIG. 5 is a diagram showing an example of an ion plating apparatus for manufacturing the cutting tool of the present invention.

FIG. 6 is a diagram showing another example of the ion plating apparatus for manufacturing the cutting tool of the present invention.

FIG. 7 is a diagram showing the results of a wear resistance test of a product of the present invention, a comparative product, and a conventional product.

[Explanation of symbols]

1 Base material 2 Crystalline aluminum oxide thin film 3 Amorphous aluminum oxide thin film 4 Thin film (
middle class).

Claims (2)

[Claims] [Claim 1] A crystalline aluminum oxide thin film is formed from the vapor phase on the surface of a base material made of metal or ceramics, and an amorphous aluminum oxide thin film is formed from the vapor phase on the surface of the crystalline aluminum oxide thin film. A cutting tool featuring: 2. The method for manufacturing a cutting tool according to claim 1, wherein the base material is heated to a predetermined film-forming temperature and a crystalline aluminum oxide thin film is first formed on the surface of the base material by an ion plating method, A method for manufacturing a cutting tool, comprising: then lowering the temperature of the base material and forming an amorphous aluminum oxide thin film overlying the surface of the crystalline aluminum oxide thin film using the same ion plating method.