JPH0377272B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing a surface-coated high-speed steel member for a cutting tool, which has a hard coating layer formed on the surface, and particularly relates to a method for manufacturing a surface-coated high-speed steel member for a cutting tool, which has a hard coating layer formed on the surface. The present invention relates to a method for manufacturing surface-coated high-speed steel members for cutting tools with excellent durability using a reactive physical vapor deposition method. [Prior Art] Conventionally, high-speed steel (hereinafter referred to as high-speed steel) has been widely used as a material for cutting tools because it has high hardness and excellent toughness that can withstand high-speed cutting. Providing a hard coating layer made of a titanium compound such as titanium or titanium nitride improves welding resistance, seizure resistance, and wear resistance, and dramatically extends tool life. Providing a coating layer on the surface of high speed steel is also widely used industrially. For example, coating chips are coated with a titanium carbide or titanium nitride layer of approximately 2 μm on the surface of throwaway chips using reactive physical vapor deposition. It is widespread. HSS members for cutting tools having such a surface coating layer of titanium carbide or titanium nitride are manufactured by first applying pressure to the HSS base using a reactive physical vapor deposition method.
Temperature: 400 to 10 ^-5 to ^{10 -3} Torr vacuum atmosphere
After heating to 450°C, the substrate is optionally ion-etched with argon at a pressure of 10 ^-4 to ^{10 -2} Torr, followed by coating with titanium carbide or titanium nitride while maintaining this temperature and pressure. In other words, the metal titanium vaporized by an electron beam or the like and the acetylene or nitrogen gas supplied into the coating furnace are ionized into Ti ⁺ and C ⁺ or N ⁺ , respectively, and these ions are made negative. It is manufactured by electrically attracting titanium carbide or titanium nitride onto a charged substrate to form a coating on the surface of the substrate. [Problems to be Solved by the Invention] However, when a titanium compound such as titanium carbide or titanium nitride is coated on a high speed steel substrate at 400 to 450°C as described above, the coating layer formed by these titanium compounds Since there is almost no direct bonding between the HSS and the HSS substrate and there is almost no diffusion of the coating layer into the substrate, the coating layer has poor adhesion, and the surface-coated HSS cutting tool obtained in this way is likely to peel off during cutting. , so there was a drawback that the tool life was short. [Findings based on research] Therefore, the inventors of the present invention have conducted various studies to solve these problems, and as a result, (1) titanium carbide, titanium nitride, titanium carbonitride, titanium carbonitride, and titanium carbonate. Titanium oxide (hereinafter referred to as TiC, TiN, TiCN, TiCNO, and TiCO, respectively; for convenience, they are collectively referred to as titanium carbon, nitride, and oxide) is deposited on a high-speed steel substrate by a reactive physical vapor deposition method. When coating a steel, if the temperature of the substrate is higher than the tempering temperature of the high speed steel, the direct reaction between the coating layer and the substrate due to the transformation of the high speed steel and the diffusion of the coating layer into the substrate will be promoted, and the relationship between the two will increase. (2) Since the tempering temperature of high speed steel is generally as low as 530 to 650°C, if the temperature of the substrate is extremely increased or the increased temperature is maintained for a long period of time, the tempering temperature of high speed steel will be reduced. The temperature is 560~650℃, and the coating time is 2~650℃.
10 minutes is suitable; (3) If the above coating does not provide a sufficiently thick coating layer, use this as a preliminary coating, and then apply the main coating to the coating layer formed by this preliminary coating. By forming the main coating layer with a total thickness of 0.5 to 10 μm on the pre-coating layer, a coating layer with excellent adhesion as a whole can be obtained, resulting in a cutting tool with dramatically extended tool life. (4) Even if the substrate temperature during the main coating applied after the preliminary coating is slightly higher than before, there is no adverse effect on the high speed steel, and the material is compatible with the preliminary coating layer. A coating layer is obtained, and a suitable temperature for the main coating is 450 to 500°C. (5) Even if the main coating is started after the preliminary coating is completed and the temperature is lowered depending on the temperature of the preliminary coating, the adhesion is maintained as described above. We have discovered that an excellent coating layer can be obtained. [Means for solving the problem] This invention was invented based on the above knowledge, and uses reactive physical vapor deposition to deposit titanium with charcoal.
A cutting tool for which a coating layer made of the coating component is formed on the surface by coating a high-speed steel substrate for a cutting tool with any one coating component selected from nitrates and oxides. In a method for manufacturing a surface-coated high-speed steel member, the temperature of the substrate is raised to 560 to 650°C in vacuum, and then the coating component is immediately applied to the substrate at this temperature for 2 to 10 minutes.
Preliminary coating is carried out for a few minutes to form a precoating layer made of the coating component on the surface of the substrate, and then after the precoated substrate is cooled down to a temperature of 450 to 500°C, or during the cooling and the After cooling, the same coating component as that used to form the preliminary coating layer is main coated on the preliminary coating layer to form a main coating layer made of the coating component on the surface of the preliminary coating layer. Thus, the total thickness of the preliminary coating layer and the main coating layer is 0.5 to 0.5.
The present invention provides a method for manufacturing the surface-coated high-speed steel member for a cutting tool, characterized in that the substrate is coated with a coating layer of 10 μm. Next, the reason why the preliminary coating temperature, preliminary coating time, main coating temperature, and coating layer thickness are each limited as described above in this invention will be described. (a) Pre-coating temperature If the pre-coating temperature is lower than 560°C, the direct reaction between the pre-coating layer and the substrate and the diffusion of the coating layer into the substrate will not be achieved sufficiently, so that the desired adhesion between the two will not be achieved. On the other hand, if the temperature exceeds 650°C, the nice material will become dull and soft during the 2 to 10 minutes of pre-coating, so the pre-coating temperature should be set at 560°C to 560°C.
The temperature was set at 650℃. (b) Pre-coating time If the pre-coating time is less than 2 minutes,
Even if the substrate is heated to the above pre-coating temperature, the direct reaction between the pre-coating layer and the substrate and the diffusion of the coating layer into the substrate do not proceed sufficiently, so that the desired adhesion between the two cannot be achieved. On the other hand, if the heating time exceeds 10 minutes, the high speed steel will become dull and soft even if the substrate is kept at the above temperature. (c) Main coating temperature Generally, the smaller the difference between the substrate temperature during main coating and that during pre-coating, the better the pre-coating layer and main coating layer will fit together, resulting in a highly durable coating layer. At the same time, the coating temperature was slightly lower than before, i.e. 50°C.
In this invention, the coating temperature is set at 450-500°C, instead of the conventional coating temperature of 400-450°C, since there is no adverse effect on the HSS even if the temperature is increased. (d) Thickness of the coating layer If the total thickness of the coating layer is less than 0.5 μm, it will not be possible to obtain a surface-coated HSS member for a cutting tool that exhibits excellent cutting performance, while if it exceeds 10 μm, the cutting performance will be poor. Since no particular improvement effect could be obtained, the thickness was determined to be 0.5 to 10 μm. This invention is accomplished by a reactive physical vapor deposition process conventionally commonly used to deposit titanium carbon-nitrogen-oxide coatings on the surface of high-speed steel substrates, including acetylene, nitrogen or monoxide. A gas such as carbon is introduced and the temperature is 10 ^-4 to 10 ^-2 Torr
Metallic titanium is evaporated using an electron beam in a coating furnace maintained at a pressure of
Ions such as Ti ⁺ , N ⁺ , C ⁺ , O ⁺ are generated, and these cations are deposited on a high-speed steel substrate loaded with negative charge by electrical attraction, thereby causing the substrate to A film of carbon, nitride, and oxide of titanium is formed on the surface. The present invention can be applied to the production of surface-coated high speed steel members for various cutting tools, and can be particularly advantageously used for the production of coating chips specific to throw-away chips. [Example] Next, the present invention will be explained by using Examples and comparing with Comparative Examples. Steel type: SKH2 high speed tempering temperature: 560~580
Hardness obtained by tempering at °C:
We manufactured a large number of throw-away chips with a shape of TPP322 from high speed steel with HRC (Rockwell hardness C scale) 64, and using these chips as the base,
After raising the temperature of this substrate to a temperature between 560 and 600°C in a coating furnace maintained at a vacuum level of 10 ^-5 Torr, immediately at this temperature any one of carbon, nitride, and oxide of titanium is coated. Coating chip 1 of the present invention is prepared by pre-coating seeds on the surface of the substrate for 5 to 10 minutes, then cooling the substrate to 450-500°C, and then main-coating with the same coating components as those used in the preliminary coating. - 8, and as an alternative method of the present invention, the main coating is started while the substrate temperature is lowered to 480 ° C. in the above production method, and before preliminary coating in the above production method, the substrate temperature: Coating chips 9 and 10 of the present invention were respectively manufactured by a method that differed from the above manufacturing method only in that etching with argon was carried out at 600 DEG C. for 10 to 20 minutes. Furthermore, for comparison, in the method for manufacturing coating chips 1 to 8 of the present invention, the manufacturing conditions were outside the scope of the present invention, and etching was performed at a temperature of 450 to 500°C for 10 to 20 minutes. In addition to manufacturing comparative coating chips 1 and 2 (deviating conditions are indicated with *), the substrate was heated to 450°C in a coating furnace maintained at a vacuum level of 10 ^-5 Torr, and then at the same temperature. Conventional coating chips 1-5 were prepared by the conventional method of etching the substrate with argon, followed by coating with carbon-nitrogen-oxide of titanium at that temperature. In each of the above methods, during etching, the substrate voltage: -1.5KV, Ar pressure: 10 ^-2 Torr
When coating, the base voltage is -0.8KV.
It was hot. The reaction gas for forming the coating layer of each titanium compound and the furnace pressure during coating were as shown in Table 1 below.

[Table] Table 2 shows the manufacturing method type, pre-coating temperature and time, main coating temperature, and coating layer components and thickness for each chip thus obtained. Next, we measured the Rockwell hardness C scale (HRC) of these chips and uncoated chips, and conducted a cutting test under the following conditions to evaluate the tool life _.
The cutting time until reaching 0.3 mm was measured and this was taken as the tool life. Cutting conditions

【table】

〔Effect of the invention〕

From the results shown in Table 2, the tool life of conventional coating chips is 15 to 30 minutes;
In contrast to chips 4 and 5, where the coating layer peeled off during cutting, the coating layer did not peel off during cutting with the coating chips of the present invention, and the tool life was extended.
In comparative coating chips 1 and 2, which were manufactured by a method in which the pre-coating time was too long or the temperature was too high, the HSS became dull and softened during cutting. As a result, tool life was extremely short. As is clear from the above description, according to the present invention, it is possible to obtain an industrially useful effect of obtaining a surface-coated HSS member for a cutting tool that has extremely excellent wear resistance and therefore has an extremely long tool life. can.

Claims (1)

[Claims] 1 Using a reactive physical vapor deposition method, any one coating component selected from titanium carbide, titanium nitride, titanium carbonitride, titanium carbonitride, and titanium carbonate is applied to high-speed steel for cutting tools. In a method for manufacturing a surface-coated high-speed steel member for a cutting tool, in which a coating layer made of the coating component is formed on the surface by coating the substrate, the substrate is heated in a vacuum at a temperature of 560 to 650°C. After raising the temperature to
Immediately, the coating component is precoated on the substrate at this temperature for 2 to 10 minutes to form a precoating layer of the coating component on the surface of the substrate, and then the precoated substrate is heated at a temperature of 450. After the temperature has been lowered to ~500°C, or during and after the temperature decrease, the same coating component as that used to form the preliminary coating layer is main-coated on the preliminary coating layer to form the preliminary coating layer. Forming a main coating layer made of the coating component on the surface of the coating layer, thereby coating the substrate with a coating layer consisting of the preliminary coating layer and the main coating layer and having a total thickness of 0.5 to 10 μm. A method for producing the surface-coated high-speed steel member for a cutting tool, characterized in that: