JP3236908B2 - Surface coated WC based cemented carbide cutting tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-coated WC base alloy comprising a WC-base superalloy as a base material and a hard layer containing at least one titanium carbonitride layer having a columnar structure on its surface. The present invention relates to a cemented carbide cutting tool, and this surface-coated WC-based cemented carbide cutting tool is an intermittent cutting (hereinafter referred to as a high efficiency cutting) such as a high-speed cutting, a high-feed cutting, and a milling cutting under more severe conditions. ) Shows excellent cutting performance over a long period of time.

[0002]

2. Description of the Related Art In recent years, cutting of a surface-coated WC-based cemented carbide obtained by forming a hard layer including at least one titanium carbonitride layer having a columnar structure on the surface of a WC-based cemented carbide substrate. Tools have been proposed. The titanium carbonitride layer in which the crystal grains have a columnar structure is formed by a medium temperature chemical vapor deposition method (hereinafter, MT-CVD method) in which a mixed gas containing an organic CN compound is used as a reaction gas and the vapor deposition is performed at a temperature of 700 to 900 ° C. The other layers are formed by a normal chemical vapor deposition method (hereinafter, referred to as a CVD method). In general, these hard layers are preferably formed on the surface of a WC-based cemented carbide substrate in which a double carbide composed of W, Co and C does not exist, and at least the hard layer is formed and It is said that it is preferable that a double carbide composed of W, Co and C does not exist on the surface.

For example, JP-A-6-8010 discloses that
Titanium carbonitride (hereinafter referred to as TiCN) having crystal grains having a columnar structure is formed on a WC-based cemented carbide substrate having a Co-enriched layer on its surface.
(Indicated by (L)) describes a surface-coated WC-based cemented carbide cutting tool formed by forming a hard layer including at least one layer, and the TiCN (L) layer is formed by an MT-CVD method, A titanium carbonitride (hereinafter, referred to as TiCN (P)) layer having a grain structure having a granular structure;
iC) layer, titanium nitride (hereinafter referred to as TiN)
It is also known that a layer and an aluminum oxide (hereinafter, referred to as Al ₂ O ₃ ) layer are formed by a normal CVD method.

[0004] The TiCN (L) layer has a thickness of 1-2.
0 μm, other layers are 0.1 to 10 μm
And it is also known that these surface-coated WC-based cemented carbide cutting tools are used for cutting various steels and the like.

[0005]

However, the conventional T
A surface-coated WC-based cemented carbide cutting tool formed with a hard layer including at least one iCN (L) layer has a high cutting speed of 300 m / min or more and a cutting speed of 0.5 mm / rev.
High feed cutting, intermittent cutting such as milling, etc.
When various steels and the like are efficiently cut under more severe conditions than in the past, abrasion or peeling is severe, chipping or the like is generated, and the tool life is shortened, which is not satisfactory.

[0006]

Means for Solving the Problems Accordingly, the present inventors have:
At least one TiCN (L) layer has a long cutting life even when cutting various steels at high efficiency under severer conditions than before.
As a result of research on obtaining a cutting tool made of a surface-coated WC-base cemented carbide formed with a hard layer including a layer, the peak intensity Iη (511) of the (511) plane by X-ray diffraction was Co (1).
11) With respect to the peak intensity ICo (111) of the plane, 0 <
TiCN is added to the surface of a substrate having a structure in which double carbides of W, Co and C in the range of Iη (511) / ICo (111) ≦ 0.8 are dispersed from the surface to the inside.
The surface-coated WC-based cemented carbide cutting tool formed by forming a hard layer including at least one (L) layer comprises a conventional WC-based cemented carbide substrate having no double carbide of W, Co and C, and a TiCN Research results have shown that the cutting life is further extended as compared with a surface-coated WC-based cemented carbide cutting tool having a hard layer containing at least one (L) layer.

[0007] The present invention has been made based on the results of such research, and comprises a hard layer containing at least one titanium carbonitride layer having a columnar structure on the surface of a WC-based cemented carbide substrate. In the cutting tool made of a surface-coated WC-based cemented carbide formed by forming a WC, the WC-based cemented carbide substrate has a peak intensity Iη (511) of the (511) plane by X-ray diffraction peak of the (111) plane of Co. For intensity ICo (111), 0 <Iη (511) / ICo (111) ≦ 0.8
Coated WC having a structure in which a complex carbide of W, Co and C in the range of
It is characterized by a cutting tool made of a base cemented carbide.

A surface formed by forming a hard layer containing at least one titanium carbonitride layer having a columnar structure on the surface of a conventional WC-based cemented carbide substrate free of double carbides composed of W, Co and C. When performing high-efficiency cutting with a coated WC-based cemented carbide cutting tool, the cutting life is short,
The following reasons are considered.

That is, the conventional surface-coated WC-based cemented carbide cutting tool uses a WC-based cemented carbide free of double carbides of W, Co and C, so that the substrate is soft and soft. When performing high-efficiency cutting with a conventional surface-coated WC-based cemented carbide cutting tool with a base cemented carbide substrate, the soft substrate undergoes microdeformation, and when microdeformation occurs, the columnar shape grows in the thickness direction. It is considered that a crack is generated in the TiCN (L) layer composed of crystal grains and peels off, which causes a reduction in tool life.

On the other hand, the substrate of the surface-coated WC-based cemented carbide cutting tool of the present invention has a peak intensity Iη (511) of (511) plane from the surface to the inside by X-ray diffraction of C.
With respect to the peak intensity ICo (111) of the (111) plane of o, a double carbide composed of W, Co and C is in the range of 0 <Iη (511) / ICo (111) ≦ 0.8. , The deformation of the substrate is extremely small even when high-efficiency cutting under more severe conditions is performed. Therefore, cracking of the TiCN (L) layer due to the deformation of the substrate does not occur, and the tool life is further improved. It is expected to be improved.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A substrate having a structure in which a double carbide composed of W, Co and C is dispersed from the surface to the inside of a surface-coated WC-based cemented carbide cutting tool according to the present invention is a conventional WC-based cemented carbide. W powder is blended such that the proportion of the C content is smaller than the blending ratio of the raw material powder of the hard alloy, and the blended powder containing the W powder is press-molded to produce a green compact. It is manufactured by sintering. Also TiCN
The (L) layer is formed by a usual MT-CVD method.

The reason why the thickness of the TiCN (L) layer is set to 1 to 20 μm is that if it is thinner than 1 μm, the TiCN layer does not become columnar crystal grains and sufficient wear resistance cannot be obtained, while if it is thicker than 20 μm. This is because the crystal grains are coarsened to easily cause chipping and chipping, which is not preferable.

A WC-based cemented carbide substrate and TiCN
The reason for forming the TiN layer having a thickness of 0.1 to 1.5 μm between the (L) layers is to further improve the adhesion between the WC-based cemented carbide substrate and the TiCN (L) layer. However, TiN
If the thickness of the layer is less than 0.1 μm, the desired effect of improving the adhesion cannot be obtained. On the other hand, if the thickness exceeds 1.5 μm, the toughness is reduced and the chipping and chipping are more likely to occur.

[0014]

EXAMPLES As raw material powders, WC powder having an average particle diameter of 3 μm and (Ti, W) CN (TiC) having an average particle diameter of 1.3 μm were used.
/ TaN / WC = 24/20/56 wt% ratio), (Ta, Nb) C (TaC / Nb) having an average particle diameter of 1.3 μm.
C = 90/10 wt% ratio) powder, average particle size: 1.2 μm
And a W powder having an average particle diameter of 3 μm are prepared, and these raw material powders are mixed so as to have a compounding composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and press-formed. Thus, green compacts A-1 to C-3 were produced.

[0015]

[Table 1]

The compacts A-1 to C- shown in Table 1
3 is vacuum-sintered in a vacuum of 0.1 Torr at a temperature of 1400 ° C. for 1 hour to obtain a C standard of ISO standard.
WC-based cemented carbide substrates a to i having the shape defined in NMG120408 were produced.

The carbon content of the WC-base cemented carbide substrates a to i is measured, the presence or absence of the dispersion of the double carbide of W, Co and C from the surface to the inside is observed with a metallographic microscope, and the double carbide is further identified. The results are shown in Table 2. Furthermore, the peak intensity Iη of the (511) plane of the double carbide by X-ray diffraction
Peak intensity I of (111) plane of Co with respect to (511)
Co (111) ratio: Iη (511) / ICo (11
1) was measured, and the results are shown in Table 2.

[0018]

[Table 2]

A TiCN (L) layer, a TiCN (P) layer, a TiC
A layer, a TiN layer, and an Al ₂ O ₃ layer were formed, and coated cutting tools 1 to 18 of the present invention and conventional coated cutting tools 1 to 9 shown in Tables 3 to 5 were produced. FIG. 1 shows a metallographic micrograph of the coated cutting tool 11 of the present invention, and FIG. 2 shows a metallographic micrograph of the conventional coated cutting tool 6. As shown in FIG. 1, the coated cutting tool 11 of the present invention produced using a WC-based cemented carbide substrate h obtained by sintering a green compact C-2 containing 0.5% by weight of W powder. Is Co from the substrate surface to the inside.
_As shown in FIG. 2 of a metallographic micrograph of the conventional coated cutting tool 6, a green compact C-3 containing no W powder was sintered while having a structure in which ₃ W ₃ C was dispersed. It can be seen that Co ₃ W ₃ C is not dispersed in the obtained WC-based cemented carbide substrate i.

(A) Conditions for forming TiCN (L) layer Composition of reactive gas component: 2% by volume% TiCl ₄ -0.5%
CH ₃ CN-20% N ₂ -77.5% H ₂ Reaction temperature: 800 ° C. Reaction pressure: 40 Torr

(B) Conditions for forming TiCN (P) layer Composition of reactive gas component: 3.5% by volume of TiCl ₄ -7.
5% CH ₄ -30% N ₂ -59% H ₂ Reaction temperature: 1000 ° C. Reaction pressure: 120 Torr

(C) Conditions for forming TiC layer Composition of reactive gas component: 2% TiCl ₄ -6% CH by volume%
₄ -92% H ₂ Reaction Temperature: 1050 ° C. Reaction pressure: 150 Torr

(D) Conditions for forming TiN layer Composition of reaction gas component: 2% by volume% TiCl ₄ -25% N
₂ -73% H ₂ Reaction Temperature: 950 ° C. Reaction pressure: 200 Torr

(E) Conditions for forming Al ₂ O ₃ layer Composition of reaction gas component: 5% by volume AlCl ₃ -8% CO
₂ -87% H ₂ Reaction Temperature: 1000 ° C. Reaction pressure: 100 Torr

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

Using the coated cutting tools 1-2, 7-8, and 13-14 of the present invention shown in Tables 3 to 5, and the conventional coated cutting tools 1, 4, and 7, the following dry high-speed continuous cutting test was performed. Was.

[0029] Dry high-speed continuous cutting test Workpiece: SCM440 (hardness: H _B 250) Cutting speed: 350 meters / min feed Ri: 0.3 mm / blade cut: 1.5 mm Cutting time: 3min conditions dry steel in the High-speed continuous cutting was performed, the flank wear width of the cutting edge was measured, and the state of damage of the cutting edge was observed. The results are also shown in Table 6.

[0030]

[Table 6]

Using the coated cutting tools 3 to 4, 9 to 10 and 15 to 16 of the present invention shown in Tables 3 to 5, and the conventional coated cutting tools 2, 5 and 8, the following high-feed continuous cutting test was performed. Was.

The high-feed continuous cutting test Workpiece: SNCM439 (Hardness: H _B 270) Cutting speed: 110m / min feed Ri: 1.0 mm / blade cut: 1.5 mm Cutting Time: steel in 0.5min conditions Was performed, the amount of plastic deformation of the cutting edge was measured, and the damage state of the cutting edge was observed. The results are also shown in Table 7.

[0033]

[Table 7]

Using the coated cutting tools 5 to 6, 11 to 12 and 17 to 18 of the present invention shown in Tables 3 to 5 and the conventional coated cutting tools 3, 6 and 9, the following intermittent cutting tests were performed.

[0035] Intermittent cutting test Workpiece: SNCM439 (Hardness: H _B 270) Cutting speed: 100 m / min feed Ri: 0.36 mm / rev cut: 3.0 mm Cutting Time: the intermittent cutting of steel in 2min conditions The damage of the cutting blade was observed, and the results are also shown in Table 8.

[0036]

[Table 8]

[0037]

According to the results shown in Table 6, the coated cutting tools 1 and 2 of the present invention and the conventional coated cutting tool 1 have the same hard layer formed. The coated cutting tools 1 and 2 of the present invention using a WC-based cemented carbide dispersed as a base from the surface to the inside are conventional coated cutting tools using a WC-based cemented carbide free of double carbide composed of W, Co and C as a substrate. It can be seen that excellent characteristics are shown as compared with No. 1.

Hereinafter, similarly, from the results shown in Tables 6 to 8, the coated cutting tools 3 to 4 of the present invention and the conventional coated cutting tool 2, the coated cutting tools of the present invention 5 to 6 and the conventional coated cutting tool 3 The coated cutting tools 7 to 8 of the present invention and the conventional coated cutting tool 4,
Coated cutting tools 9 to 10 of the present invention and conventional coated cutting tool 5, coated cutting tools 11 to 12 of the present invention and conventional coated cutting tool 6, coated coated tools of the present invention 13 to 14 and conventional coated cutting tool 7, coated coated cutting tool of the present invention It can be seen that the same results are obtained by comparing the coated cutting tools 15 and 16 with the conventional coated cutting tool 8, and the coated cutting tools 17 and 18 of the present invention and the conventional coated cutting tool 9 respectively.

As described above, according to the present invention, it is possible to provide a surface-coated WC-based cemented carbide cutting tool exhibiting superior cutting performance as compared with the conventional one, and can greatly contribute to the development of industry. .

[Brief description of the drawings]

FIG. 1 is a metallographic micrograph of a cross section of a substrate of a surface-coated WC-based cemented carbide cutting tool according to the present invention.

FIG. 2 is a metal microstructure photograph of a cross section of a substrate of a conventional surface-coated WC-based hard metal cutting tool.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-133346 (JP, A) JP-A-50-21944 (JP, A) JP-A-6-108254 (JP, A) JP-A-6-108254 65671 (JP, A) JP-A-7-136826 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23B 27/14 C22C 29/00-29/08 C23C 16/30- 16/40

Claims (4)

(57) [Claims] 1. A surface-coated WC-based cemented carbide cutting tool comprising a WC-based cemented carbide substrate and a hard layer containing at least one titanium carbonitride layer having a columnar structure formed on a surface of the WC-based cemented carbide substrate. The WC-based cemented carbide substrate was subjected to X-ray diffraction (511).
The peak intensity Iη (511) of the plane is 0 <Iη (51) with respect to the peak intensity ICo (111) of the (111) plane of Co.
1) W, C in the range of /ICo(111)≦0.8
A cutting tool made of a surface-coated WC-based cemented carbide, characterized by having a structure in which a double carbide composed of o and C is dispersed from the surface to the inside. 2. The surface-coated WC-based cemented carbide according to claim 1, wherein the hard layer is a single layer of a titanium carbonitride layer having a crystal structure having a columnar structure and having a thickness of 1 to 20 μm. Alloy cutting tool. 3. The hard layer has a thickness of 0.1 to 1.5 μm.
m and a multi-layer of a titanium carbonitride layer having a thickness of 1 to 20 μm in which crystal grains formed on the titanium nitride layer of the underlayer have a columnar structure. The cutting tool made of a surface-coated WC-based cemented carbide according to claim 1 or 2, characterized in that: 4. A surface coating W according to claim 1, 2 or 3.
A surface-coated WC-based cemented carbide cutting tool, wherein an outermost layer made of a titanium nitride layer or an aluminum oxide layer is further formed on a hard layer of the C-based cemented carbide cutting tool.