JP2010125539A - Cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool having a long tool life even under such a cutting condition that an impact is intermittently applied to a cutting blade in such a case that a rotary tool is cut and processed. <P>SOLUTION: The cutting tool has a base body whose surface is coated with a coating layer comprising a nitride or a carbon nitride containing Ti and Al. When diffraction angles of diffraction peaks of a (111) surface and a (200) surface of the coating layer in the X ray diffraction measurement of the Cu-Kα line are 2θ<SB>(111)</SB>and 2θ<SB>(200)</SB>, respectively, the values 2θ<SB>(111)N</SB>and 2θ<SB>(200)N</SB>measured at the unpolished surface of the coating layer are detected at a side having a smaller angle of 0.1° or larger than the values 2θ<SB>(111)G</SB>and 2θ<SB>(200)G</SB>measured at a polished surface formed by obliquely polishing the coating layer with respect to a thickness direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cutting tool formed by forming a coating layer on the surface of a substrate.

  Since cutting tools are required to have wear resistance, slidability, and fracture resistance, various coating layers are formed on the surface of a hard substrate such as a WC-based cemented carbide or TiCN-based cermet to provide wear resistance for the tool. Techniques that improve the durability and fracture resistance are used.

  As the coating layer, a TiCN layer or a TiAlN layer is generally widely used, but various coating layers are being developed for the purpose of improving higher wear resistance and fracture resistance.

For example, Patent Document 1 discloses that the C / (C + N) ratio of the TiCN film is increased in the CVD method, and the diffraction angle 2θ of the diffraction peak in the X-ray diffraction measurement of the TiCN film is shifted to the lower angle side. . In Patent Document 2, the amorphous hard film AlM (NO) obtained by physical vapor deposition has an X-ray diffraction peak shifted to a low angle by increasing the N ₂ gas partial pressure during vapor deposition. Is disclosed. As in Patent Documents 1 and 2, it is known to control the characteristics of the coating layer by controlling the diffraction intensity in X-ray diffraction in the Ti-based coating layer.
JP 2008-87150 A JP 2006-32517 A

  However, in cutting tools used for machining rotary tools that are subject to intermittent impacts such as milling, drilling, and end milling, a coating in which the X-ray diffraction peak of the entire coating layer is shifted as in Patent Documents 1 and 2. In the layer, although the hardness and oxidation resistance of the coating layer can be increased, there is a problem that chipping and peeling of the coating layer are likely to occur at the cutting edge. Therefore, in order to prevent such peeling of the coating layer, the thickness of the coating layer is reduced to suppress chipping and peeling of the coating layer. As a result, the wear resistance of the coating layer was not sufficient.

  An object of the present invention is to provide a cutting tool having a long tool life even under cutting conditions in which impact is intermittently applied to the cutting edge, such as cutting of a rotary tool.

The cutting tool of the present invention is a cutting tool in which the surface of a base is coated with a coating layer made of a nitride or carbonitride containing Ti and Al, and X-ray diffraction measurement of Cu-Kα rays of the coating layer When the diffraction angles of the diffraction peaks on the (111) plane and (200) plane are 2θ ₍₁₁₁₎ and 2θ ₍₂₀₀₎ , respectively, the value 2θ _{(111) N} measured on the unpolished surface of the coating layer 2θ _{(200) N} is 0.1 ° or more in comparison with values 2θ _{(111) G} and 2θ _{(200) G} measured on a polished surface obtained by polishing the coating layer obliquely with respect to the thickness direction. It is detected on the low angle side.

  Here, it is desirable that the unpolished coating layer has a thickness of 4 to 15 μm.

Further, the values 2θ _{(111) N} and 2θ _{(200) N} when measured on the unpolished surface of the coating layer and the value 2θ when measured around the position where the coating layer remains 2 μm thick on the polished surface. When comparing _{(111) G} 2 μm, 2θ _{(200) G} 2 μm, the difference between 2θ _{(111) G} 2 μm and 2θ _{(111) N} is 0.2 to 0.6 °, and 2θ _{(200) G} It is desirable that the difference between 2 μm and 2θ _{(200) N} is 0.1 to 0.5 °.

Furthermore, when the peak intensities of the diffraction peaks of the (111) plane and (200) plane in the X-ray diffraction measurement when measured on the unpolished surface of the coating layer are P ₍₁₁₁₎ and P ₍₂₀₀₎ , respectively. The ratio P _{(200) N} / P _{(111) N} between the values P _{(111) N} and P _{(200) N} when measured on the unpolished surface of the coating layer is oblique to the thickness direction of the coating layer. It is desirable that it is larger than the ratio P _{(200) G} / P _{(111) G} of the value P _{(111) G} and P _{(200) G} when measured on the polished surface.

  Further, it is desirable that the coating layer is composed of an aggregate of columnar crystals, and the average crystal width of the columnar crystals on the surface side is larger than the average crystal width of the columnar crystals on the substrate side.

According to the cutting tool of the present invention, the diffraction angles of the diffraction peaks of the (111) plane and the (200) plane in the X-ray diffraction measurement of the Cu—Kα ray of the coating layer are 2θ ₍₁₁₁₎ , 2θ ₍₂₀₀₎ and When the values 2θ _{(111) N} and 2θ _{(200) N} measured on the unpolished surface of the coating layer are measured on a polished surface obtained by polishing the coating layer obliquely with respect to the thickness direction, The values 2θ _{(111) G} and 2θ _{(200) G} are detected on the lower angle side by 0.1 ° or more, respectively, so that the coating layer on the substrate side has good adhesion to the substrate, Peeling can be suppressed. On the other hand, on the surface side of the coating layer, the compressive stress generally increases and it tends to self-destruct, but for the coating layer of the present invention, the stress on the surface is relaxed and the fracture resistance of the coating layer is improved. Contribute.

  Here, it is desirable that the unpolished coating layer has a thickness of 4 to 15 μm because the diffraction angle of the diffraction peak of the coating layer can be easily controlled.

Further, the values 2θ _{(111) N} and 2θ _{(200) N} when measured on the unpolished surface of the coating layer and the value 2θ when measured around the position where the coating layer remains 2 μm thick on the polished surface. When comparing _{(111) G} 2 μm, 2θ _{(200) G} 2 μm, the difference between 2θ _{(111) G} 2 μm and 2θ _{(111) N} is 0.2 to 0.6 °, and 2θ _{(200) G} The difference between 2 μm and 2θ _{(200) N} is preferably 0.1 to 0.5 ° in order to increase the hardness of the coating layer and improve the wear resistance.

Furthermore, when the peak intensities of the diffraction peaks of the (111) plane and (200) plane in the X-ray diffraction measurement when measured on the unpolished surface of the coating layer are P ₍₁₁₁₎ and P ₍₂₀₀₎ , respectively. The ratio P _{(200) N} / P _{(111) N} between the values P _{(111) N} and P _{(200) N} when measured on the unpolished surface of the coating layer is oblique to the thickness direction of the coating layer. The toughness of the coating layer is greater than the ratio P _{(200) G} / P _{(111) G} of the value P _{(111) G} and P _{(200) G} measured on the polished surface. Desirable to improve.

  Further, the coating layer is composed of an aggregate of columnar crystals, and the average crystal width of the columnar crystals on the surface side is larger than the average crystal width of the columnar crystals on the substrate side, the wear resistance of the coating layer It is desirable in terms of enhancing the performance.

  The cutting tool of the present invention is configured such that the surface of the base is coated with a coating made of a nitride or carbonitride containing Ti and Al, and the ridge line portion between the rake face and the flank face is used as a cutting edge. .

And according to this invention, the diffraction angle of the diffraction peak of the (111) plane and the (200) plane in the X-ray diffraction measurement of the Cu-Kα ray of the coating layer of the cutting tool is 2θ ₍₁₁₁₎ 2θ _{( 200)} , the values 2θ _{(111) N} and 2θ _{(200) N} measured on the unpolished surface of the coating layer are measured on the polished surface obtained by polishing the coating layer obliquely with respect to the thickness direction. It is characterized in that it is detected on the lower angle side by 0.1 ° or more compared to the values 2θ _{(111) G} and 2θ _{(200) G.} As a result, the coating layer on the substrate side has good adhesion to the substrate, and the peeling of the coating layer can be suppressed. On the other hand, on the surface side of the coating layer, the internal stress is relaxed and self-destruction of the coating layer can be suppressed, which contributes to an improvement in the fracture resistance of the cutting tool. Note that when X-ray diffraction measurement is performed on the polished surface in the present invention, measurement is performed at a position that is 1/2 or less the thickness of the coating layer from the substrate side, that is, at a position close to the substrate side.

  Here, it is desirable that the unpolished coating layer has a thickness of 4 to 15 μm because the diffraction angle of the diffraction peak of the coating layer can be easily controlled.

Further, the values 2θ _{(111) N} and 2θ _{(200) N} when measured on the unpolished surface of the coating layer and the value 2θ when measured around the position where the coating layer remains 2 μm thick on the polished surface. When comparing _{(111) G} 2 μm, 2θ _{(200) G} 2 μm, the difference between 2θ _{(111) G} 2 μm and 2θ _{(111) N} is 0.2 to 0.6 °, and 2θ _{(200) G} The difference between 2 μm and 2θ _{(200) N} is preferably 0.1 to 0.5 ° in order to increase the hardness of the coating layer and improve the wear resistance.

Furthermore, when the peak intensities of the diffraction peaks of the (111) plane and (200) plane in the X-ray diffraction measurement when measured on the unpolished surface of the coating layer are P ₍₁₁₁₎ and P ₍₂₀₀₎ , respectively. The ratio P _{(200) N} / P _{(111) N} between the values P _{(111) N} and P _{(200) N} when measured on the unpolished surface of the coating layer is oblique to the thickness direction of the coating layer. The toughness of the coating layer is greater than the ratio P _{(200) G} / P _{(111) G} of the value P _{(111) G} and P _{(200) G} measured on the polished surface. Desirable to improve.

  Further, the coating layer is composed of an aggregate of columnar crystals, and the average crystal width of the columnar crystals on the surface side is larger than the average crystal width of the columnar crystals on the substrate side, the wear resistance of the coating layer It is desirable in terms of enhancing the performance.

The coating may be composed of simple Ti _1-a Al _a N. For example, Ti _1-a-b Al _a M _b (C _x N _1-x ) (where M is Ti 1 or more selected from Group 4, 5 and 6 elements of the periodic table, rare earth elements and Si, and 0 ≦ a <1, 0 <b ≦ 1, and 0 ≦ x ≦ 1. May be. Among them, Ti _1-a-b Al _a M _b (C _x N _1-x ) (where M is one or more selected from Group 4, 5, 6 elements, rare earth elements and Si in the periodic table excluding Ti) Yes, 0.4 ≦ a ≦ 0.65, 0 ≦ b ≦ 0.3, and 0 ≦ x ≦ 1) is desirable from the viewpoint of improving oxidation resistance, wear resistance, and fracture resistance. Further, among the above _{composition, Ti 1-a-b-} c-d Al a M b W c Si d (C x N 1-x) ( however, M is the periodic table excluding Ti 4, 5, 6 1 or more selected from group elements, rare earth elements and Si, and 0.4 ≦ a ≦ 0.65, 0 ≦ b ≦ 0.3, and 0 ≦ x ≦ 1). In the composition region, the oxidation start temperature is high, the oxidation resistance is high, the wear resistance at the time of cutting is improved, and chipping that is likely to occur at the tip of the cutting edge can be suppressed, and the fracture resistance is high. Further, the metal M is at least one selected from Nb, Mo, Ta, Hf, and Y. Among them, the inclusion of Nb or Mo is desirable in terms of the most excellent wear resistance and oxidation resistance.

  Furthermore, C and N, which are non-metallic components of the coating, are excellent in hardness and toughness required for the cutting tool. In order to suppress excessive generation of droplets generated on the coating surface, x (C content ratio) ) Is particularly desirable in the range 0 ≦ x ≦ 0.5. The composition of the coating can be measured by energy dispersive X-ray spectroscopy (EDS) analysis or X-ray photoelectron spectroscopy (XPS).

  In addition, as a substrate, tungsten carbide, a cemented carbide or cermet composed of a hard phase mainly composed of titanium carbonitride and a binder phase mainly composed of an iron group metal such as cobalt and nickel, silicon nitride, , Hard materials such as ceramics mainly composed of aluminum oxide, hard phases made of polycrystalline diamond or cubic boron nitride, and bonded phases such as ceramics and iron group metals under super high pressure, etc. Are preferably used.

(Production method)
Next, the manufacturing method of the surface coating cutting tool of this invention is demonstrated.

  First, a tool-shaped substrate is produced using a conventionally known method. Next, a film is formed on the surface of the substrate. As a film forming method, a physical vapor deposition (PVD) method such as an ion plating method or a sputtering method can be suitably applied. The details of an example of the film forming method will be described. When a film is formed by an ion plating method, metal titanium (Ti), metal aluminum (Al), metal M (where M is a periodic table excluding Ti). It is used for a metal target or a composite alloy target containing one or more selected from Group 4, 5, 6 elements, rare earth elements and Si) independently.

According to the present invention, the composition of the metal evaporated in the early stage of film formation and the composition of the metal evaporated in the late stage of film formation are changed so that the composition of the metal evaporated in the later stage of film formation is different from the composition of the metal evaporated in the early stage of film formation. The composition is set so that the content ratio of the metal having a large ionic radius is increased. At this time, according to the present invention, as a film forming condition, using this target, the metal source is evaporated and ionized by arc discharge or glow discharge, and at the same time, nitrogen (N ₂ ) gas or carbon of the nitrogen source is used. Conditions for reacting with the source methane (CH ₄ ) / acetylene (C ₂ H ₂ ) gas can be suitably employed. At this time, the film formation is started by setting the bias voltage at the initial stage of film formation to 100 to 200 V, and the film is formed by setting the bias voltage at the latter stage of film formation to 20 to 75 V lower than the bias voltage at the initial stage of film formation. . In addition, the temperature of the substrate at the initial stage of film formation is set to 400 to 500 ° C. and film formation is started, and the temperature of the substrate at the latter stage of film formation is set to 500 to 650 ° C. higher than the temperature of the substrate at the initial stage of film formation. To form a film. Thereby, the crystal structure of the coating layer to be formed can be controlled, and the diffraction angle of the X-ray diffraction peak can be controlled within the above-described range.

In film formation, a film is formed by an ion plating method or a sputtering method using an inert gas such as nitrogen (N ₂ ) gas or argon (Ar) gas.

10% by mass of metallic cobalt (Co) powder, 0.2% by mass of vanadium carbide (VC) powder, chromium carbide (Cr ₃ C ₂ ) powder with respect to tungsten carbide (WC) powder having an average particle size of 0.5 μm Was added and mixed at a ratio of 0.8% by mass, and molded into a milling insert (KYOSERA throw-away tip BDMT11T304-JT) and fired. After the grinding process, the surface was washed in the order of alkali, acid, and distilled water to produce an insert substrate.

  Then, the substrate was set in an arc ion plating apparatus equipped with the target shown in Table 1, and the substrate was heated to the temperature shown in Table 1 to form the coating shown in Table 1. Three main targets are set on the side wall surface of the chamber, and one sub target is set on the upper wall surface of the chamber, and the film formation is completed when half of the film formation time has passed, up to half the film formation time. In the first half of the film formation, the film was formed using only the main target, and in the second film formation, the film was formed using both the main target and the sub target. The film forming conditions other than those shown in Table 1 were constant at an arc current of 150 A in an atmosphere of nitrogen gas at a total pressure of 4 Pa.

The resulting insert performs tissue observation at a magnification 50,000 fold with Keyence scanning electron microscope (VE8800), crystal shape and thickness of the film constituting the coating _{(t r,} t _f) was confirmed. In addition, using the EDAX analyzer (AMETEK EDAX-VE9800) attached to the apparatus, the composition of the film is quantitatively analyzed by the ZAF method, which is a kind of energy dispersive X-ray spectroscopy (EDS) analysis method, at an acceleration voltage of 15 kV. Ti / (Ti + Al), which is the ratio of Ti and Al, was calculated for each of the rake face and the flank face (Ti _r , Ti _f ). For elements that could not be measured by this method, a PHI X-ray photoelectron spectrometer (Quantum2000) was used, and the X-ray source was irradiated with monochrome AlK (200 μm, 35 W, 15 kV) to a measurement region of about 200 μm. Measurements were made. The results are shown in Table 2.

Moreover, the film thickness of the coating layer was measured from the scanning electron microscope SEM photograph. Then, a micro X-ray diffraction analysis was performed, and the peak intensity ratio I (400) / I (331) was measured. The collimator diameter was 0.3 mmφ, and measurement was performed at the center of the flat portion of each surface. The radiation source was Cu-Kα ray, and the output was 45 kV, 110 mA, incident angle 2.0 °, Cu-Kα ray, Step · 0.02 °, Time · 2 sec. P _r and _pf were calculated from diffraction peaks obtained by X-ray diffraction analysis. The results are shown in Table 3.

Furthermore, the cutting test was done on the following cutting conditions using the obtained insert. The results are shown in Table 3.
Cutting method: Shoulder (milling)
Work material: SKD11
Cutting speed: 150 m / minute feed: 0.12 mm / blade cutting: lateral cutting 10 mm, depth cutting 3 mm
Cutting state: Dry evaluation method: At the time of cutting for 20 minutes, the flank wear amount and the chipping state at the cutting edge are measured.

  However, the amount of wear at the time of failure was measured for samples that were lost 20 minutes before the processing time.

From Tables 1 to 3, Sample No. 2 in which 2θ _{(200) N} and 2θ _{(200) G} were detected at the same diffraction angle. No. 11 and 2θ _{(200) N} 2θ _{(200) G} was detected on the higher angle side than sample No. In No. 12, chipping occurred in the coating layer and it was lost early. Sample No. in which the peak shift was small and the difference of 2θ _{(200) G} was smaller than 0.1 ° than 2θ _{(200) N.} In No. 13, the wear progressed quickly. Sample No. consisting of a single tissue from the substrate side to the surface. No. 14 was insufficient in wear resistance and fracture resistance. For both 2θ _{(111) G} and 2θ _{(200) G} , sample No. 2 detected at a higher angle than 2θ _{(111) N} and 2θ _{(200) N.} In No. 15, chipping occurred early in the coating layer due to self-destruction, and the wear progressed quickly.

On the other hand, the sample numbers of 2θ _{(111) N} and 2θ _{(200) N} detected on the lower angle side compared to 2θ _{(111) G} and 2θ _{(200) G} , respectively. In Nos. 1 to 10, the chipping resistance and wear resistance were good and the cutting performance was excellent.

Claims (5)

A cutting tool in which the surface of a substrate is coated with a coating layer made of a nitride or carbonitride containing Ti and Al, the (111) plane for X-ray diffraction measurement of Cu-Kα rays of the coating layer, and When the diffraction angles of the diffraction peaks of the (200) plane are 2θ ₍₁₁₁₎ and 2θ ₍₂₀₀₎ , respectively, the values 2θ _{(111) N} and 2θ _{(200) N} when measured on the unpolished surface of the coating layer are , Each of which is detected on the lower angle side by 0.1 ° or more compared to the values 2θ _{(111) G} and 2θ _{(200) G} measured on a polished surface obtained by polishing the coating layer obliquely with respect to the thickness direction. A cutting tool characterized by that.   The cutting tool according to claim 1, wherein a thickness of the unpolished coating layer is 4 to 15 μm. The coating layer of the values 2 [Theta] ₍₁₁₁₎ when measured at unpolished surface _N, 2θ ₍₂₀₀₎ N and the value of when the coating layer at the polishing surface was measured of a position remaining 2μm thickness 2 [Theta] _{(111 )} When comparing _G 2 μm, 2θ _{(200) G} 2 μm, the difference between 2θ _{(111) G} 2 μm and 2θ _{(111) N} is 0.2 to 0.6 °, and 2θ _{(200) G} 2 μm The cutting tool according to claim 2, wherein a difference from 2θ _{(200) N} is 0.1 to 0.5 °. When the peak intensities of diffraction peaks on the (111) plane and (200) plane in the X-ray diffraction measurement when measured on the unpolished surface of the coating layer are P ₍₁₁₁₎ and P ₍₂₀₀₎ , respectively, The ratio P _{(200) N} / P _{(111) N} between the values P _{(111) N} and P _{(200) N as} measured on the unpolished surface of the layer polishes the coating layer obliquely with respect to the thickness direction. The ratio P _{(200) G} / P _{(111) G} between the values P _{(111) G} and P _{(200) G} when measured on the polished surface is larger. Any cutting tool.   5. The covering layer is composed of an aggregate of columnar crystals, and an average crystal width of the columnar crystals on the surface side is larger than an average crystal width of the columnar crystals on the substrate side. The cutting tool of any one of.