JP3371796B2 - Surface coated cemented carbide cutting tool with excellent fracture resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool made of surface-coated cemented carbide, excellent in chipping resistance and exhibiting excellent cutting performance over a long period. SOLUTION: This cutting tool made of surface-coated cemented carbide is obtd. by chemically vapor-depositing and/or physically vapor-depositing, on the surface of a WC base cemented carbide substrate, a hard coating layer having total overage layer thickness of 3 to 20 μm and composed, in order from the surface side of the substrate, of a TiN layer with a granular crystal structure having 0.1 to 2 μm average layer thickness, a TiCN layer with a longitudinally growing crystal structure having 1 to 15 μm average layer thickness, an Al2 O3 layer with a granular crystal structure having 0.5 to 15 μm average layer thickness and also having a crystal structure of the α type, κ type or the mixed type of α and κ and a TiN layre with a granular crystal structure having 0.1 to 3 μm average layer thickness. In this case, on the space between the TiCN layer and the Al2 O3 layer, a Ti2 O3 layer by chemical vapor deposition or physical vapor deposition showing an X-ray diffraction pattern in which the maximum diffraction peak height appears in the angle of diffraction (2θ) of 24.0±1 degrees by X-ray diffraction using CuKα ray as a radiation source is interposed by the average layer thickness of 0.1 to 2 μm.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an excellent fracture resistance and is particularly suitable for high-speed cutting of steel and cast iron, and heavy cutting such as high cutting and high feed. When used for cutting, a cutting tool made of a surface-coated cemented carbide (hereinafter referred to as a coated cemented carbide tool) that exhibits excellent cutting performance for a long period of time without chipping or chipping (small chipping) of the cutting edge ). 2. Description of the Related Art Conventionally, generally, for example, Japanese Patent Application Laid-Open No. 6-315
03, JP-A-6-316758, and JP-A-7-216549, etc.
A single layer of one of carbides, nitrides, and carbonitrides of metals of groups 4a, 5a, and 6a of the periodic table is formed on the surface of a tungsten carbide-based cemented carbide substrate (hereinafter, referred to as a cemented carbide substrate). A metal charcoal / nitride layer composed of two or more types of multiple layers,
An aluminum oxide (hereinafter, referred to as Al ₂ O ₃ ) layer, wherein each of the metal carbon nitride layer and the Al ₂ O ₃ layer has a granular crystal structure. among the titanium carbonitride (hereinafter, shown by TiCN) in layers also those having an elongated growth crystal structure, further wherein Al ₂
O ₃ layer α type, kappa-type or α and kappa mixed coating cemented carbide tool crystalline hard coating layer are those having a structure with an average layer thickness of 3~20μm formed by chemical vapor deposition and / or physical vapor deposition, It is also known that this coated carbide tool is used for continuous cutting or interrupted cutting of steel, cast iron, or the like. On the other hand, in recent years, high performance, high output, and FA of cutting equipment have been remarkable, and there is a strong demand for labor saving and energy saving of cutting work. However, the cutting process tends to be high speed and heavy cutting such as high cutting and high feed, but in the above-mentioned conventional coated carbide tools, if this is used for high speed cutting or heavy cutting, especially metal charcoal Due to insufficient adhesion between the nitride layer and the Al ₂ O ₃ layer, chipping or chipping is apt to occur in the cutting edge, and as a result, the service life is currently reached in a relatively short time. [0004] Therefore, the present inventors have proposed:
From the above viewpoint, we focused on a conventional coated carbide tool in which the hard coating layer was composed of a metal carbon / nitride layer and an Al ₂ O ₃ layer, and conducted research to improve the fracture resistance of the tool. As a result, the structure of the hard coating layer chemically vapor-deposited on the surface of the cemented carbide substrate was changed from the substrate surface side to a titanium nitride (hereinafter referred to as TiN) layer having a granular crystal structure and a TiCN layer having a vertically-grown crystal structure. An Al ₂ O ₃ layer having a granular crystal structure,
After specifying a TiN layer having a granular crystal structure,
As a hard coating layer between the N layer and the Al ₂ O ₃ layer,
In X-ray diffraction using Cuka radiation as a radiation source, as shown in FIG. 1, a chemical pattern showing an X-ray diffraction pattern in which the highest diffraction peak height appears at a diffraction angle (2θ) of 24.0 ± 1 degree.
Trioxide titanium (hereinafter, Ti ₂ O indicated by ₃₎ having a granular crystal structure of the deposition formation when the intervening layer, the Ti ₂
Since the O ₃ layer has extremely high interlayer adhesion to both the TiCN layer and the Al ₂ O ₃ layer,
The resulting coated carbide tool exhibits excellent chipping resistance even when performing continuous and interrupted cutting of steel and cast iron under high-speed and heavy cutting conditions, and demonstrates excellent cutting performance over a long period of time. The research result was obtained. The present invention has been made on the basis of the above research results, and has a granular crystal structure of TiN having an average layer thickness of 0.1 to 2 μm on the surface of a cemented carbide substrate in order from the substrate surface side. Layer, TiCN layer with a longitudinal growth crystal structure having an average layer thickness of 1 to 15 μm, having an average layer thickness of 0.5 to 15 μm, and having an α-type, κ-type, or a mixed-type crystal structure of α and κ Al ₂ O ₃ layer of granular crystal structure, 0.1-3μ
TiN layer of granular crystal structure having an average layer thickness of m, in the coated cemented carbide tool with a hard coating layer constituted formed by chemical vapor deposition, between the TiCN layer and the the Al ₂ O ₃ layer, a hard
A coating layer having an average layer thickness of 0.1 to 2 μm and C
X-ray diffraction using ukα ray as a radiation source, 24.0 ± 1
A Ti ₂ O ₃ layer formed by chemical vapor deposition showing an X-ray diffraction pattern in which the highest diffraction peak height appears at a diffraction angle (2θ) in degrees is interposed, and the entire average layer thickness of the hard coating layer is ₃ to 20 μm. This is a feature of a coated carbide tool having improved fracture resistance due to the above. Next, the reason why the average layer thickness of the constituent layers of the hard coating layer and the overall average layer thickness of the coated carbide tool of the present invention are limited as described above will be described. (A) TiN Layer (Super Hard Substrate Side) The TiN layer has excellent adhesion to the surface of the super hard substrate, and prevents diffusion and transfer of the constituents of the super hard substrate into the hard coating layer during formation of the hard coating layer. This has the effect of suppressing the deterioration of the characteristics of the hard coating layer, but the thickness of the layer is 0.1 μm.
If it is less than 3, the above effect is not sufficiently exhibited, while the above effect is sufficient with a layer thickness of up to 2 μm. (B) TiCN layer The TiCN layer has excellent toughness and excellent abrasion resistance, so that it has excellent cutting performance over a long period without chipping or chipping of the cutting edge. Although it is indispensable to exert the effect, if the layer thickness is less than 1 μm, the above effect cannot be sufficiently exerted.
If the thickness exceeds 5 μm, the cutting edge is likely to undergo thermoplastic deformation,
Since this causes uneven wear, the layer thickness is set to 1 to 1
It was determined to be 5 μm. (C) Ti ₂ O ₃ layer The Ti ₂ O ₃ layer firmly adheres to both the TiCN layer and the Al ₂ O ₃ layer, so that lack of interlayer adhesion between these two causes chipping or chipping. If the layer thickness is less than 0.1 μm, the desired effect cannot be obtained. If the layer thickness exceeds 2 μm, chipping and chipping of the cutting edge are liable to occur. Therefore, the layer thickness was determined to be 0.1 to 2 μm. (D) Al ₂ O ₃ layer The Al ₂ O ₃ layer has excellent oxidation resistance and thermal stability,
Since it has high hardness, it is indispensable to improve the wear resistance of the tool together with the TiCN layer.
If the thickness is less than 5 μm, the desired wear resistance cannot be ensured. On the other hand, if the thickness exceeds 15 μm, chipping and chipping easily occur on the cutting edge.
It was determined to be 5 to 15 μm. (E) TiN layer Since the TiN layer itself has a golden color tone, it is formed for facilitating discrimination between before and after use of the tool. When the layer thickness is less than the above, the application of the color tone is insufficient, while the application of the color tone requires a layer thickness of up to 3 μm. Therefore, the layer thickness is set to 0.1 to 3 μm. (F) Overall average thickness of the hard coating layer If the thickness is 3 μm, the desired excellent wear resistance cannot be ensured. On the other hand, if the thickness exceeds 20 μm,
Since chipping and chipping easily occur in the cutting blade, the overall average layer thickness was determined to be 3 to 20 μm. Further, the Ti ₂ O ₃ layer constituting the hard coating layer of the coated cemented carbide tool of the present invention has a reaction gas composition—volume%
And TiCl ₄ : 0.4 to 10%, CO ₂ : 0.4 to 1
0%, Ar: 10~60%, H 2: remainder, ambient temperature: 800 to 1100 ° C., atmospheric pressure: 50～500Torr, can be formed in the condition. Next, the coated carbide tool of the present invention will be described in detail with reference to examples. Medium-sized WC powder having an average particle diameter of 2.8 μm, 4.9 μm as the raw material powder
m of coarse WC powder, 1.5 μm of (Ti, W) C (the same in weight ratio, hereinafter, TiC / WC = 30/70) powder,
1.2 μm (Ti, W) CN (TiC / TiN / W
C = 24/20/56) powder, 1.2 μm (Ta,
Nb) C (TaC / NbC = 90/10) powder and Co powder of 1.1 μm were prepared, and these raw material powders were blended in the composition shown in Table 1, wet-mixed in a ball mill for 72 hours, and dried. After that, ISO ・ CNMG12040
8 (for carbide substrates A to D) and SEEN42AFTN
Press molded into a green compact having the shape defined in No. 1 (for the super hard substrate E), and the green compact was vacuum-sintered under the conditions shown in Table 1 to produce super hard substrates A to E, respectively. Further, the above-mentioned super hard substrate B was subjected to 100 Torr CH.
After holding at a temperature of 1400 ° C. for 1 hour in a ₄ gas atmosphere, a slow cooling carburization treatment is performed, and after the treatment, carbon and Co adhering to the surface of the carbide substrate are removed from the surface by acid and barrel polishing. Maximum Co content at 11 μm: 1
A Co-enriched zone of 5.9% by weight and a depth of 42 μm was formed on the surface of the substrate. In addition, the above-mentioned carbide substrates A and D include:
As-sintered, a Co-enriched zone having a maximum Co content of 9.1% by weight and a depth of 23 μm was formed on the surface at a position 17 μm from the surface, and the remaining carbide substrates C and E were formed. Has no formation of the Co-enriched zone and has an overall homogeneous structure. Table 1 shows the internal hardness (Rockwell hardness A scale) of each of the carbide substrates A to E. Then, the surface of each of the superhard substrates A to E was honed, and was subjected to a conventional chemical vapor deposition apparatus, as shown in Table 2 (TiCN having a vertically elongated crystal structure in the table).
The layer is equivalent to the TiCN layer described in JP-A-6-8010) under the conditions shown in Table 3 to form a hard coating layer having the composition and average thickness shown in Table 3. coated carbide tools 1-5, and Ti ₂ O ₃ layers formed without a comparison coated cemented carbide tools 1 to 5 were prepared respectively. FIG. 1 shows the X-ray diffraction pattern of the coated carbide tool 2 of the present invention immediately after the Ti ₂ O ₃ layer was formed. Similar results were obtained with the coated carbide tools 1, 3, 4, and 5 of the present invention. Indicated. Next, for the coated carbide tools 1-4 of the present invention and the comparative coated carbide tools 1-4, a work material: a round bar of JIS SCM440 (hardness: HB 220), a cutting speed: 350 m / min. Infeed: 2 mm Feed: 0.2 mm / rev. , Cutting time: 10 minutes, Dry continuous high-speed cutting test of alloy steel under the following conditions: Work material: JIS SNCM439 (Hardness: HB250)
Round bar, Cutting speed: 200 m / min. Infeed: 2 mm Feed: 0.8 mm / rev. , Cutting time: 2 minutes, Dry continuous high-feed cutting test of alloy steel under the following conditions: Work material: JIS SNCM439 (Hardness: HB250)
Square material, Cutting speed: 250 m / min. Infeed: 2 mm Feed: 0.2 mm / rev. The cutting intermittent high-speed cutting test of the alloy steel was performed under the following conditions: cutting time: 5 minutes, and the flank wear width of the cutting edge was measured in each cutting test. Table 4 shows the results of these measurements. In addition, the coated carbide tools 1 and 4 of the present invention and the comparative coated carbide tools 1 and 4 are described below. Work material: JIS FC300 round bar, Cutting speed: 450 m / min. Infeed: 2 mm Feed: 0.3 mm / rev. A dry continuous high-speed cutting test was performed on the cast iron under the following conditions: cutting time: 10 minutes, and the flank wear width of the cutting edge was also measured. The measurement results are shown in Table 4. Further, for the coated carbide tool 5 of the present invention and the comparative coated carbide tool 5, a work material: a square material of JIS SNCM439 having a size of 100 mm in width × 500 mm in length, and a use condition: a cutter having a diameter of 125 mm and a single edge Mounting, cutting speed: 250 m / min. , Depth of cut: 2 mm, feed: 0.2 mm / tooth, cutting time: 2 passes (cutting time of 1 pass: 4.5 minutes), dry dry high speed milling test of alloy steel under the following conditions:
The flank wear width of the cutting blade was measured. The measurement results are also shown in Table 4. [Table 1] [Table 2] [Table 3] [Table 4] According to the results shown in Tables 3 and 4, all of the coated carbide tools 1 to 5 of the present invention were interposed between the TiCN layer of the hard coating layer and the Al ₂ O ₃ layer. Even in high-speed cutting and heavy-duty cutting of alloy steel and cast iron, which are subjected to severe cutting conditions due to the action of the Ti ₂ O ₃ layer, they are much more effective than the comparative coated carbide tools 1-5 in which the Ti ₂ O ₃ layer is not formed. It is clear that it exhibits excellent fracture resistance. As described above, the coated cemented carbide tool of the present invention is not limited to continuous cutting and interrupted cutting under ordinary conditions such as steel and cast iron, and even if these cuttings are performed under high-speed conditions or heavy cutting conditions, It exhibits excellent fracture resistance and exhibits excellent cutting performance over a long period of time, and contributes to labor saving and energy saving in cutting.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing an X-ray diffraction pattern immediately after forming a Ti ₂ O ₃ layer of a coated carbide tool 2 of the present invention.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuya Yanagita 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Mitsubishi Materials Corporation General Research Laboratory (56) References JP-A-11-152570 (JP, A) JP-A-10-18039 (JP, A) JP-A-8-187605 (JP, A) JP-B 5-47624 (JP, B2) JP-B-56-52108 (JP, B2) (58) Fields investigated (Int) .Cl. ⁷ , DB name) B23B 27/14 C23C 16/40

Claims (1)

(57) Claims: 1. A titanium nitride layer having a granular crystal structure having an average layer thickness of 0.1 to 2 µm on a surface of a tungsten carbide-based cemented carbide substrate in order from the substrate surface side. A titanium carbonitride layer having a vertical growth crystal structure having an average layer thickness of 1 to 15 μm, an average layer thickness of 0.5 to 15 μm, and α-type and κ-type;
Or aluminum oxide layer of granular crystal structure having a mixed crystal structure of the α and kappa, titanium nitride layer of granular crystal structure having an average layer thickness of 0.1 to 3 m, in the hard coating layer formed by chemical vapor deposition In the surface-coated cemented carbide cutting tool, the titanium carbide layer and the aluminum oxide layer,
It has an average layer thickness of 0.1 to 2 μm as a hard coating layer , and is 24.0 in X-ray diffraction using Cuka radiation as a radiation source.
A titanium oxide layer formed by chemical vapor deposition showing an X-ray diffraction pattern exhibiting the highest diffraction peak height at a diffraction angle (2θ) of ± 1 degree is interposed, and the total average layer thickness of the hard coating layer is 3 to 2
A cutting tool made of a surface-coated cemented carbide having excellent fracture resistance, characterized in that the thickness is 0 μm .