JPH0680184B2 - Method for manufacturing surface-coated high-speed steel member for cutting tool or wear-resistant tool - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a surface-coated high-speed steel member for a cutting tool or a wear-resistant tool in which a hard coating layer is formed on the surface, and in particular, The present invention relates to a method for producing a surface-coated high-speed steel member for a cutting tool or a wear-resistant tool, which has a coating layer of a hard titanium compound excellent in adhesion on the surface, by using a physical vapor deposition method.

[Conventional technology]

Conventionally, high-speed steel (hereinafter referred to as "high speed steel") has high hardness and excellent toughness. It is widely used as a material for various wear resistant tools, but when a hard coating layer made of a titanium compound such as titanium carbide or titanium nitride is provided on the surface of this high speed steel, it is possible to improve the welding resistance, seizure resistance and wear resistance. In order to improve the workability and to dramatically increase the tool life, it has recently been actively practiced to provide such a coating layer on the surface of the high-speed steel to a thickness of 1 to 8 μm.

In order to manufacture a high speed member for cutting tools or wear resistant tools having such a surface coating layer of titanium carbide or titanium nitride by a reactive physical vapor deposition method, for example, first, a high speed steel substrate is pressurized in a reaction furnace. : After heating to a temperature below the tempering temperature of HSS in a vacuum atmosphere of 10 ^-5 to 10 ^-3 Torr,
Optionally subjecting the substrate to ion etching with argon at a pressure of 10 ^-4 to 10 ^-2 Torr, followed by a coating reaction with titanium carbide or titanium nitride while maintaining this temperature and pressure, i.e. the reactor The titanium metal vaporized by an electron beam in the reactor and the acetylene or nitrogen gas supplied into the reactor are positively ionized, respectively, and these positive ions are electrically charged on the negatively charged substrate. The films are attracted to form titanium carbide or titanium nitride films on the surface of the substrate, and then the substrate is cooled to room temperature by allowing it to cool or blowing argon gas into the reaction furnace.

[Problems to be solved by the invention]

However, titanium carbide, titanium nitride and titanium carbonitride (hereinafter referred to as TiC, TiN and TiCN, respectively) in the surface-coated HSS member manufactured by the above method are
In addition, for convenience, these are collectively referred to as titanium carbon / nitride) coatings have poor adhesion, so cutting tools or wear-resistant tool high speed steels coated with such coatings have tool life There was a problem that it was short.

[Findings based on research]

Therefore, as a result of various studies to solve such a problem, the present inventor has used a physical vapor deposition method to provide a coating layer made of a coating component of titanium carbon / nitride for a cutting tool or with an anti-corrosion property. In the case of coating on a high speed steel substrate for wear tools, after the vapor deposition of the coating layer on the substrate is finished, the substrate is heated to a temperature equal to or lower than the tempering temperature of the high speed steel by applying the reactive physical vapor deposition method. Cooling rate for cooling the machine to room temperature
It has been found that when the temperature is 50 to 100 ° C, a surface-coated high-speed steel member for cutting tools or wear-resistant tools having excellent adhesion can be obtained.

Such a result generally indicates that the thermal expansion coefficient of HSS is considerably larger than that of titanium carbon / nitride, so that when the substrate after film formation is cooled randomly, that is, relatively quickly to room temperature, as in the conventional case, Since the coating layer cannot sufficiently follow the rapid contraction of the HSS substrate, peeling or misalignment occurs between the substrate and the coating layer, or strain remains in the coating layer, whereas the substrate as described above If you cool it relatively slowly,
The HSS substrate gradually shrinks, and the compressive force generated at the interface with the coating layer gently acts on the coating layer due to the shrinkage, thereby making it difficult for the peeling, slipping, or strain to occur. Considered to be based.

[Means for solving problems]

This invention was invented on the basis of the above findings, and utilizes physical vapor deposition to provide any one or more coating components of TiC, TiN and TiCN for cutting tools or wear resistant tools. In the method for producing a surface-coated high-speed steel member for a cutting tool or a wear-resistant tool in which a coating layer comprising the coating component is adhered to the surface by coating on a high-speed steel substrate for use in After the vapor deposition is completed, the substrate that has been heated to a temperature not higher than the high temperature tempering temperature by applying the physical vapor deposition method,
The present invention relates to a method for producing a surface-coated high-speed steel member for a cutting tool or an abrasion resistant tool, which comprises cooling to room temperature at a cooling rate of 50 to 100 ° C. per hour.

[Specific Description of the Invention]

(1) Physical Vapor Deposition Method The physical vapor deposition method used in the present invention will be described by taking, for example, precipitation formation of a TiN film, as shown in the schematic explanatory view of FIG. In a reaction furnace 1 under a pressure of 10 ^-5 to 10 ^-3 Torr in a vacuum atmosphere, and after heating to a temperature not higher than the tempering temperature of HSS, the pressure: 10
After optionally ion-etching the substrate with argon at ^-4 to 10 ^-2 Torr, nitrogen gas 2 is introduced into the reaction furnace 1 in place of the argon to adjust the atmospheric pressure and temperature in the reaction furnace 1 to the above-mentioned values. The substrate 3 and the cooling copper crucible 4 which are arranged to face each other in the reaction furnace 1 while being maintained at the pressure and temperature.
A direct current voltage of several tens of volts is applied to the discharge electrode 5 provided between the discharge electrode 5 and the metal titanium 6 held in the crucible 4 to generate discharge between the discharge electrode 5 and the nitrogen gas. A plasma of gas 2 is formed between the discharge electrode 5 and the crucible 4, while the metal titanium 6 is irradiated with an electron beam 7 to dissolve and evaporate it, and the evaporated titanium is passed through the plasma. After ionizing into positive ions,
The nitrogen was positively ionized by the discharge and was also attached to the substrate 3 kept at a negative potential of 1500 V, and was also produced by the reaction of these titanium ions and nitrogen ions. A TiN coating is deposited on the surface of the substrate 3, and then the substrate 3 heated to a temperature not higher than the high temperature tempering temperature is allowed to cool or is cooled by an external heating means 8 to room temperature at a predetermined cooling rate.

(2) Cooling rate of the substrate After forming the carbon-nitride coating layer of titanium, cooling the substrate kept at a temperature below the HSS tempering temperature at a rate of more than 100 ° C / hr gives the desired excellent adhesion. When the surface-coated high speed steel member coated with the coating layer having the property is not obtained, and the cooling rate thereof is less than 50 ° C./hr, it takes too long to cool the substrate, and the above-mentioned effect is remarkably improved. In the present invention, the cooling rate of the substrate was set to 50 to 100 ° C./hr because it was not observed.

In the cooling rate of 50 to 100 ° C./hr specified in the present invention, the above-mentioned effect is remarkable when the thickness of the coating layer is 2 to 8 μm, and the TiC and TiN formed on the HSS substrate. When the film was investigated by X-ray diffraction analysis, when the cooling rate of the substrate was too fast, that is, when the cooling rate exceeded 100 ° C / hr, the (220) plane of the crystal composed of those titanium compounds was observed. The cooling rate: 50 to 1 in contrast to the d value of ± 0.04 with respect to the value of the ASTM card.
When the substrate is cooled at 00 ° C / hr, the d value is ± 0.0
It was 3 or less, and such a result indicates that the coating layer obtained according to the present invention causes less strain than the conventional one.

〔Example〕

Next, the present invention will be described with reference to the production of a cutting tool coated with a titanium carbon / nitride coating layer as an example, in comparison with a comparative example.

Example 1 As shown in FIG. 1, a reactor 1, a water-cooled copper crucible 4,
Utilizing a vapor deposition device provided with the discharge electrode 5 and the electric heater 8, and as the titanium 6, the reaction gas 2, and the substrate 3,
m3, PA 20 ° right 1 row, lead angle 2 ° 23 ', D _tf 3.5, outer diameter: 80m
SKH with the shape and dimensions of m x length: 150 mm x inner diameter: 31.75 mm
A 55 hob was used, and the reaction conditions were: furnace temperature: 5
Nitrogen or acetylene with a temperature of 00 ° C and a furnace pressure of 7 × 10 ^-4 Torr is used. Reaction gas flow rate: 250 ml / min and substrate potential:
After depositing TiN coating and TiC coating of the thickness shown in Table 1 on the surface of the hob by using −100 V, the reaction is performed to prevent the substrate held at 500 ° C. from being rapidly cooled. While the heat is supplied from the outside of the furnace 1 by the electric heater 8, the substrate is gradually cooled to room temperature (25 ° C.) at the cooling rate shown in Table 1 to obtain the surface-coated hobs 1 to 1 of the present invention.
6 were manufactured respectively, and the above 500 for comparison.
Comparative surface coated hobs 1-6 were prepared respectively by allowing the substrate held at 0 ° C. to cool and changing only its rate of temperature increase as shown in Table 1.

Then, in order to investigate the wear resistance of these surface-coated hobs, the work material: round bar of JIS SCM3, (hardness: H _R C 9-13) Manufactured gear: number of teeth 21, dimension: outer diameter 70 mm × Thickness 20 mm x inner diameter 30 mm Cutting speed: 160r.pm (40m / min), feed: 2mm / w rev., Cutting direction: climbing cut, intermittent cutting test was carried out under the following conditions. The wear width was measured and the results are shown in Table 1.

Example 2 grades: SKH2 HSS tempering temperature: 560 to 580 was collected using cowpea to tempering at ° C., hardness: H _R C64 form a high-speed steel having: TPP322 produced a number of slow-Au H. class tap, these The same coating conditions as in Example 1 were used with the chips of No. 1 as the substrate, and the Ti having the thickness shown in Table 2 was used.
After depositing a coating layer consisting of N, TiC and TiCN (where C / N ratio = 4/6, in which case a mixed gas of acetylene and nitrogen is used as the reaction gas) on the chip surface, 50
By cooling the chip maintained at 0 ° C. at the cooling rates shown in Table 2, the surface-coated chips 1 to
9 and comparative surface coating chips 1-9 respectively I made it.

Then, in order to investigate the wear resistance of these surface coated chips, a cutting test was conducted under the following conditions, and V _B wear was 0.3 mm.
The tool life was the cutting time required to reach the above value, and the time was measured. The results are shown in Table 2.

Cutting Conditions Workpiece: SNCM8, H _B: 250, Holder: P22R-44, Cutting speed: V = 60m / min, d = 1.5mm, f = 0.1mm / rev ..

〔The invention's effect〕

From the results shown in Table 1, comparing the surface-coated hob of the present invention and the comparative surface-coated hob having the same material and the same thickness as each other, the third maximum wear width of the hob surface at the time of cutting 12.6 m is The invention surface-coated hobs were significantly smaller, and it was found that the comparative surface-coated hobs 3 and 6 peeled off the coating layer during the cutting and immediately after the start of the cutting, respectively. Comparing the inventive surface-coated chip with the comparative surface-coated chip, the inventive surface-coated chip had a significantly longer tool life than the comparative surface-coated chip, and the comparative surface-coated chips 6 and 9 had the coating layer peeled off immediately after the start of cutting. It can be seen from the results of Examples 1 and 2 that the hobs and chips manufactured according to the present invention are remarkable in both the hobs and the throwaway chips. It can be seen that includes a superior abrasion resistance.

As is clear from the above description, according to the present invention, the adhesion is remarkably improved, and thus a surface-coated high-speed steel member for cutting tools or wear-resistant tools with significantly improved wear resistance is obtained. An industrially useful effect of providing these surface-coated high-speed steel members having a remarkably long tool life can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an outline of an apparatus used for carrying out the method of the present invention. In the figure, 1 ... Reactor, 2 ... Reactive gas, 3 ... Substrate, 4 ... Crucible, 5 ... Discharge electrode, 6 ... Metal titanium, 7 ... Electron beam, 8 ... Electric heater.

Claims (1)

[Claims] 1. A high speed steel substrate for cutting tools or wear resistant tools, which is coated with at least one of titanium carbide, titanium nitride and titanium carbonitride by a physical vapor deposition method. In the method for producing a surface-coated high-speed steel member for a cutting tool or a wear-resistant tool, wherein a coating layer comprising the coating component adheres to the surface by coating, vapor deposition of the coating layer on the substrate After completion, the substrate that had been heated to a temperature below the high speed steel tempering temperature by application of the physical vapor deposition method, 50
A method for producing a surface-coated high-speed steel member for a cutting tool or an abrasion resistant tool, which comprises cooling to room temperature at a cooling rate of -100 ° C.