JP2001038504A - Surface coated cemented carbide cutting tool with hard coating layer exercising superior chipping resistance during highly efficient cutting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface coated cemented carbide cutting tool with a hard coating layer exercising superior chipping resistance during highly efficient cutting. SOLUTION: In a coated cemented carbide tool comprised by chemically and/or physically vapor-depositing a hard coating layer of an overall average layer thickness of 3 to 35 μm comprising a lower layer, a middle layer, and an upper layer on a surface of a WC base cemented carbide base substance, the lower layer is constituted by a Ti compound of an average thickness of 1 to 20 μm and the middle layer has a texture having an average thickness of 1 to 15 μm with K and ZrO2 distributed as a dispersed phase on a basis material of Al2O3. The upper layer is constituted by an outermost surface substrate layer represented by TiOX having an average thickness of 0.1 to 3 μm and an outermost surface layer comprising a Ti nitrogen oxide layer having an average thickness of 0.05 to 2 μm and represented by TiN1-Y(O)Y (in the formula, X represents 1.2 to 1.7 in atomic ratio in regard to Ti, and Y represents 0.01 to 0.4 in atomic ratio in regard to Ti).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a case where continuous cutting or intermittent cutting of various steels or cast irons is performed at a high cutting speed for high efficiency cutting, or the above-mentioned high speed cutting for further high efficiency cutting. Even when cutting at high speed under heavy cutting conditions such as high feed and high cutting depth, the hard coating layer exhibits excellent chipping resistance and is made of a surface coated cemented carbide cutting tool (hereinafter referred to as coated carbide tool). ).

[0002]

2. Description of the Related Art Conventionally, a tungsten carbide-based cemented carbide substrate (hereinafter referred to as a cemented carbide substrate) generally has, on the surface thereof, (a) an average layer thickness of 0.1 to 5 μm each as a lower layer, and , Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, oxide (hereinafter referred to as TiN) layer,
A Ti ₂ O ₃ layer, a carbonitride (hereinafter, shown as TiCN) layer, a carbon oxide (hereinafter, shown as TiCO) layer, a nitrogen oxide (hereinafter, shown as TiNO) layer, and a carbonitride ( (Hereinafter referred to as TiCNO) layer, and a Ti compound layer composed of one or more of these layers;
Aluminum oxide having an average layer thickness of μm (hereinafter referred to as Al
(Shown as ₂ O ₃ ) layer and (c) the upper layer itself has a golden surface tone, so that the average of 0.1 to 3 μm is used for the purpose of facilitating discrimination between before and after use of the tool. A Ti nitride (hereinafter, referred to as TiN) layer having a layer thickness;
Coated carbide tools are known which are obtained by chemical vapor deposition and / or physical vapor deposition of the hard coating layer composed of (c) with a total average layer thickness of 3 to 35 μm. It is also known to be used for continuous cutting and interrupted cutting of steel, cast iron, and the like.

In general, the Ti compound layer and the Al ₂ O ₃ layer constituting the hard coating layer of the coated carbide tool have a granular crystal structure, and the Al ₂ O ₃ layer has an α-type crystal structure. It is also well known that materials having a κ-type crystal structure are widely used for practical purposes.
As described in JP-A-8010 and JP-A-7-328808, TiCN constituting the Ti compound layer
The layer is vertically elongated by chemical vapor deposition at a medium temperature range of 700 to 950 ° C. using a mixed gas containing an organic carbonitride as a reaction gas with a normal chemical vapor deposition apparatus for the purpose of improving the toughness of the layer itself. It is also known to have a grown crystal structure and a relatively thick layer having an average layer thickness of 3 to 20 μm.

[0004]

On the other hand, in recent years, there has been a strong demand for labor saving, energy saving, and further cost reduction in cutting, and with this, cutting tends to perform high efficiency cutting. In a conventional coated carbide tool, as described above, the upper layer (outermost layer) of the hard coating layer is composed of a TiN layer formed by vapor deposition for the purpose of identification before and after use, and this TiN layer is used as a work material. When the cutting speed is increased particularly for high efficiency cutting, the high speed cutting is accompanied by a high heat generation because of the strong adhesion to steel. And acts to locally peel off the TiN layer from the hard coating layer, where the TiN layer is an intermediate Al ₂ O ₃ layer, and the Al ₂ O ₃ layer is a lower layer Ti For compound layer Since all of these layers have excellent adhesion, these constituent layers are also locally peeled off together with the TiN layer, and as a result, chipping (small chipping) occurs at the cutting edge, and in a relatively short time. When the cutting at the above-mentioned high cutting speed is performed under heavy cutting conditions such as high feed and high cutting for the purpose of further high-efficiency cutting, particularly the Al constituting the hard coating layer is used. ₂ O ₃
At present, chipping on the cutting edge due to insufficient toughness of the layer (intermediate layer) is further accelerated, and further shortening of service life is inevitable.

[0005]

Means for Solving the Problems Accordingly, the present inventors have
From the viewpoints described above, in order to develop a coated carbide tool in which the hard coating layer exhibits excellent chipping resistance, focusing on the above-mentioned conventional coated carbide tools, as a result of conducting research,
(A) Oxidation of 0.1 to 10% by weight in the Al ₂ O ₃ layer (intermediate layer) constituting the hard coating layer of the above-mentioned conventional coated carbide tool, based on the total amount with Al ₂ O _3. Zirconium (hereinafter
(Indicated by ZrO ₂ ) as a disperse phase, the resulting Al ₂ O ₃ -based layer exhibits excellent thermal stability, heat resistance, and high hardness of Al ₂ O ₃ without loss. Toughness, and therefore this Al
A coated carbide tool with a ₂ O ₃ main layer as an intermediate layer of a hard coating layer is used for performing high-speed cutting at a high cutting speed under heavy cutting conditions such as high feed and high cutting. In addition, chipping caused by insufficient toughness of the intermediate layer is eliminated, and excellent wear resistance is exhibited over a long period of time.

(B) Al of the above (a)_TwoO_ThreeIn the base of Z
rO_TwoAl with dispersed phases_TwoO _ThreeThe main layer is, for example,
Using a chemical vapor deposition apparatus, the reaction gas composition
Cl_Three: 1-10%, ZrCl_Four: 0.01 to 10%, C
O_Two: 1 to 30%, H_TwoS: 0.02-2%, HCl:
0.5-10%, N_Two1 to 15%, H_Two: The rest, and then
And the reaction atmosphere temperature: 850 to 1050 ° C., and the reaction atmosphere pressure: 40 to 400 Torr.

(C) On the surface of the Al ₂ O ₃ main layer of (a), first, as an underlayer, a reaction gas composition was prepared by volume%.
_{TiCl 4: 0.2~10%, CO 2} : 0.1~10%,
Ar: 5 to 60%, H ₂ : remaining, reaction atmosphere temperature: 800 to 1100 ° C., reaction atmosphere pressure: 30 to 500 torr, and an average layer thickness of 0.1 to 3 μm. And the ratio of oxygen to Ti is 1.25 to 1.
90, that is, when represented by the composition formula: TiO _W , the atomic ratio to W: Ti is 1.25 to
1.90, a Ti oxide layer satisfying 1.90 is formed.
On the oxide layer, as the outermost surface layer, under the usual conditions, that is, the reaction gas composition is set to TiCl ₄ : 0.2 to
_{10%, N 2: 4~60%} , H 2: remainder, and then, and, Temperature of reaction atmosphere: 800 to 1100 ° C., reaction atmosphere pressure: 30～650Torr, between the conditions, the average layer 0.05~2μm T with thickness
When the iN layer is formed, oxygen of the Ti oxide layer constituting the underlayer diffuses during the formation of the outermost surface layer, so that a Ti nitride oxide layer is formed. In this case, the Ti nitride oxide layer is formed. In the subsequent outermost surface underlayer, the oxygen ratio is 1.2 to 1.7 in atomic ratio to Ti, that is, when represented by the composition formula: TiO _x , the atomic ratio to X: Ti is 1.2 to 1.7.
1.7, while the outermost surface layer has a diffusion oxygen ratio of 0.0 as an atomic ratio to Ti.
1 to 0.4, namely, composition _{formula: TiN 1-Y (O)} Y, in the case where expressed (however, O in parenthesis indicates the diffusion of oxygen from the outermost base layer), Y: atom to Ti It becomes a Ti nitride oxide layer satisfying a ratio of 0.01 to 0.4,
In the resulting coated carbide tool in which the Ti nitride oxide layer and the Ti oxide layer are chemically and / or physically deposited as the outermost surface layer and the outermost surface underlayer of the hard coating layer, the Ti nitride oxide layer and the Ti oxide layer are particularly preferable. Since the layer has a golden surface tone equivalent to that of the above-mentioned TiN layer, it is possible to identify before and after use of the tool, and since it has extremely low adhesion to various steels as work materials, it has a high efficiency. Even when cutting is performed under the condition that the cutting speed is increased for the purpose of cutting, chipping heated at a high temperature is prevented from adhering, so that chipping of the cutting blade is remarkably suppressed, and the above-mentioned (a) Al ₂ Excellent cutting performance over a long period of time in combination with the effect of suppressing chipping due to the improvement in toughness of the hard coating layer provided by the O ₃ main layer. The research results shown in (a) to (c) above were obtained.

The present invention has been made on the basis of the above research results, and has a hard coating layer comprising a lower layer, an intermediate layer, and an upper layer on the surface of a superhard substrate, having a total average layer thickness of 3 to 35 μm. (A) the lower layers each having an average layer thickness of 0.1 to 20 μm, and a TiC layer;
TiN layer, Ti ₂ O ₃ layer, TiCN layer, TiCO layer, Ti
A Ti compound layer comprising one or more of a NO layer and a TiCNO layer, and (b) the intermediate layer has an average layer thickness of 1 to 15 μm and is made of an Al ₂ O ₃ substrate. To the total amount with Al ₂ O ₃ , 0.1 to 10
Composed of Al ₂ O ₃ main layer having a tissue ZrO ₂ weight% is distributed as a dispersed phase, (c) a said upper layer has an average layer thickness of 0.1 to 3 m, and the composition formula: When represented by TiO _x , the atomic ratio to X: Ti is 1.2 to 1.2.
1.7, an outermost underlayer consisting of a Ti oxide layer satisfying 1.7, an average layer thickness of 0.05 to 2 μm, and represented by the composition formula: TiN _1-Y (O) _Y. (However, O in parentheses indicates oxygen diffused from the outermost surface underlayer). The outermost surface layer of a Ti nitride layer satisfying an atomic ratio of 0.01 to 0.4 with respect to Y: Ti. The present invention is characterized by a coated carbide tool having a hard coating layer which exhibits excellent chipping resistance by high-efficiency cutting.

Next, the reason why the numerical values of the hard coating layer in the coated cemented carbide tool of the present invention are limited as described above will be described. (1) Distribution Ratio of ZrO ₂ in Al ₂ O ₃ Main Layer of Intermediate Layer As described above, fine ZrO ₂ distributed as a dispersed phase in an Al ₂ O ₃ base material has excellent thermal properties of Al ₂ O _3. Stability,
It has the effect of improving toughness without impairing heat resistance and high hardness. However, if its distribution ratio is less than 0.1% by weight in the total amount with Al ₂ O ₃ , the weight at a high cutting speed is low. At the time of cutting, sufficient toughness cannot be ensured to suppress the occurrence of chipping on the cutting edge. On the other hand, if the distribution ratio exceeds 10% by weight, the above-mentioned effect caused by the base material of Al ₂ O ₃ is obtained. since so it appears decline in properties, 0.1 to 10 wt% as a percentage of the distribution ratio to the total amount of the Al ₂ O _3, preferably defined as 0.3 to 6% by weight.

(2) Average Layer Thickness of Intermediate Layer The Al ₂ O ₃ main layer constituting the intermediate layer has excellent oxidation resistance, thermal stability and high hardness due to the Al ₂ O ₃ base, and ZrO ₂ . Although it has excellent toughness, if the average layer thickness is less than 1 μm, the desired wear resistance and toughness cannot be secured, while the average layer thickness is 1 μm.
If it exceeds 5 μm, chipping and chipping easily occur in the cutting blade, so the average layer thickness is set to 1 to 15 μm, preferably 2 to 10 μm.

(3) Percentage of diffusion oxygen (Y value) of Ti nitride layer constituting the outermost surface layer of the upper layer The Y value is set to 0.01 to 0.40 in atomic ratio with respect to Ti. If the value is less than 0.01, the desired effect cannot be ensured in suppressing adhesion to chips, while if the value exceeds 0.40, pores are easily formed in the layer,
This is because it is difficult to stably form a sound outermost layer.

(4) Ratio of oxygen (W value and X value) in the outermost surface underlayer of the upper layer As described above, the Ti nitride layer constituting the outermost layer is first formed by:
As the underlayer, the ratio of oxygen was set to 1.
Forming a Ti oxide layer with 25 to 1.90 (W value);
Then, a TiN layer is formed by evaporating the TiN layer on the underlayer under normal conditions.
The diffusion of oxygen from the underlayer during the formation of the iN layer is indispensable.
When the value is less than 1.25, the diffusion reaction of oxygen into the TiN layer is sharply reduced, and the ratio (Y value) of the diffused oxygen in the outermost surface layer is set to 0.01 or more in atomic ratio to Ti. On the other hand, if the W value exceeds 1.90, the ratio of the diffused oxygen in the outermost surface layer exceeds 0.40 in atomic ratio to Ti, so that the W value is increased to 1.25. In this case, the ratio of oxygen (X value) in the outermost surface underlayer after the formation of the outermost surface layer
Takes a value in the range of 1.2 to 1.7 in atomic ratio to Ti. In other words, the X value of the outermost underlayer after the formation of the outermost layer satisfies 1.2 to 1.7. In this case, the Y value of the outermost surface layer satisfies 0.01 to 0.40.

(5) Average Layer Thickness of Constituent Layers Excluding the Intermediate Layer of the Hard Coating Layer First, the Ti compound layer constituting the lower layer has a common property that it is strongly adhered to any of the constituent layers. As a result, excellent interlayer adhesion between the constituent layers is ensured. In this case, if the average crystal layer thickness is less than 0.1 μm, the desired excellent interlayer adhesion can be obtained. In a TiCN layer having a vertically-grown crystal structure that cannot be secured and has excellent toughness, an average layer thickness of 3 μm or more is required to secure desired toughness. If the average layer thickness exceeds 5 μm, and in the TiCN layer having the vertically-grown crystal structure, if the average layer thickness exceeds 20 μm, all of the grains grow rapidly and chipping easily occurs on the cutting edge. Become TiCN from, the average layer thickness, than that of the granular crystal structure 0.1 to 5 [mu] m, the longitudinal growth crystal structure
The layer was determined to have a thickness of 3 to 20 μm, that is, an average layer thickness of 0.1 to 20 μm as a Ti compound layer. Further, the average layer thickness of the outermost layer and the outermost underlying layer constituting the hard coating layer is set to 0.05 to 2 μm and 0.1 to 3 μm, respectively, because the average layer thickness is less than 0.05 μm and 0 to 2 μm. .
If the thickness is less than 1 μm, the former cannot achieve a desired surface color tone (golden color), and the latter has insufficient oxygen supply to the outermost surface layer. Is based on the reason that the oxygen supply effect of 2 μm can be sufficiently achieved with an average layer thickness of 3 μm. Furthermore, the average thickness of the hard coating layer is 3 to 35 μm.
The reason for this is that if the layer thickness is 3 μm, the desired excellent wear resistance cannot be secured, while the layer thickness is 35 μm.
If it exceeds m, chipping and chipping of the cutting edge are likely to occur.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated carbide tool of the present invention will be specifically described with reference to examples. As the raw material powder, WC powder having a predetermined average particle diameter in the range of 0.5 to 4 μm, (Ti, W) C (the same in weight ratio, T
iC / WC = 30/70) powder, (Ti, W) CN (T
iC / TiN / WC = 24/20/56) powder, (T
a, Nb) C (TaC / NbC = 90/10) powder, C
An r ₃ C ₂ powder and a Co powder were prepared, and these raw material powders were blended in the blending composition shown in Table 1, and were mixed with a ball mill to obtain a powder.
After being wet-mixed for one hour and dried, it is pressed into a green compact of a predetermined shape at a pressure of 1 ton / cm 2, and this green compact is vacuum-sintered under the conditions shown in Table 1 to obtain ISO.
-Carbide bases A to F each having a throw-away tip shape specified in CNMG120412 were manufactured.

Next, the surfaces of these superhard substrates A to F were honed, and a conventional chemical vapor deposition apparatus was used. Tables 2 to 4 (l-TiCN in Table 2 was
No. 010, which has a vertically elongated crystal structure
Under the conditions shown in Tables 5 and 6, under the conditions shown in Tables 5 and 6. (Ti compound layer), an intermediate layer (Al ₂ O ₃ main layer), and an upper layer (a top surface layer composed of a diffusion oxygen-containing Ti oxynitride layer and a top surface underlayer composed of a diffusion oxygen supply Ti oxide layer) ), The coated superhard tools 1 to 10 of the present invention are manufactured respectively, the intermediate layer is an Al ₂ O ₃ layer, and the upper layer is TiN.
Conventional coated carbide tools 1 to 1
10 were each manufactured.

The distribution ratio of ZrO ₂ in the Al ₂ O ₃ main layer, which is the intermediate layer of the hard coating layers of the coated carbide tools 1 to 10 of the present invention obtained as a result, was measured by using an electron probe microanalyzer (EPMA). ) Shows substantially the same value as the target value shown in Table 3, and the oxygen content (Y value and X value) of the outermost surface layer and the outermost underlayer constituting the upper layer. Was measured using an Auger emission spectrometer, and the values shown in Table 7 were obtained. In addition, all the coated carbide tools had a golden surface tone, and the constituent layers constituting the hard coating layer also showed substantially the same average layer thickness as the target layer thickness.

Next, the coated carbide tools of the present invention 1 to 10
Workpiece: JIS S30C (hardness: HB168) round bar, Cutting speed: 355 m / min. Infeed: 1.5 mm Feed: 0.2 mm / rev. Cutting time: 5 minutes Dry high-speed continuous cutting test of carbon steel under the following conditions: Work material: JIS SNCM439 (Hardness: HB245)
Round bar with four longitudinal grooves at equal intervals in the longitudinal direction, Cutting speed: 300 m / min. Notch: 1.7 mm Feed: 0.25 mm / rev. Cutting time: 5 minutes Dry high-speed intermittent cutting test of alloy steel under the following conditions: Work material: JIS SCM440 (hardness: HB180) round bar, Cutting speed: 250 m / min. Infeed: 1.7 mm Feed: 0.7 mm / rev. , Cutting time: 5 minutes, Dry high-feed, high-speed continuous cutting test of alloy steel under the following conditions: Work material: JIS S25C (hardness: HB162), round bar with four longitudinal grooves at regular intervals in the longitudinal direction, Cutting Speed: 250 m / min. Infeed: 7.3 mm Feed: 0.25 mm / rev. , Cutting time: 5 minutes, Dry high-cut high-speed intermittent cutting test of carbon steel under the following conditions:
And the maximum flank wear width of the cutting edge was measured in each cutting test. Table 7 shows the measurement results.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

[Table 6]

[0024]

[Table 7]

[0025]

From the results shown in Tables 5 to 7, it can be seen that the uppermost layer constituting the upper layer of the hard coating layer reacts with oxygen diffused from the underlayer during the formation of the TiN layer to form Ti oxynitride. The coated cemented carbide tools 1 to 10 according to the present invention, which are composed of a material layer and the intermediate layer is composed of an Al ₂ O ₃ main layer, can be used for cutting the steel with high heat even at a high cutting speed. The layer has a very low affinity for high-temperature heated chips, and since the chips do not adhere to the Ti-nitride layer, there is no chipping on the cutting edge, and for the purpose of further high-efficiency cutting, Even if the cutting at the high cutting speed is performed under high feed and high cutting conditions under heavy cutting conditions, since the Al ₂ O ₃ main layer has excellent toughness, chipping does not occur on the cutting edge, Demonstrates excellent wear resistance, but hard coating In the conventional coated carbide tools 1 to 10 in which the upper layer (outermost layer) of the covering layer is a TiN layer and the intermediate layer is an Al ₂ O ₃ layer, the cutting at a high cutting speed is all Powder easily adheres to the TiN layer,
Since the layer is peeled off by the cutting powder together with the other constituent layers, chipping is likely to occur on the cutting blade, leading to a service life in a relatively short time, and especially in addition to the cutting at the high cutting speed, When the cutting conditions are heavy cutting with high feed and high depth of cut, chipping is accelerated due to insufficient toughness of the Al ₂ O ₃ layer as the intermediate layer, and the service life is further shortened. It is clear that is inevitable. As described above, the coated cemented carbide tool of the present invention performs these cuttings at a high cutting speed with the aim of high efficiency cutting as well as continuous cutting and interrupted cutting of various steels and cast irons under normal conditions. Even under severe conditions, high-speed and high-cut heavy-duty cutting at high cutting speeds is possible, with the ability to identify before and after use, and excellent cutting edges without chipping. Since the wear resistance is exhibited over a long period of time, it is possible to satisfactorily cope with the labor saving and energy saving of the cutting process and the cost reduction.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takashi Oshika 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Inside Mitsubishi Materials Research Institute (72) Inventor Toshiaki Ueda 1-297 Kitabukurocho, Omiya City, Saitama Mitsubishi F-term in Reference Materials Research Laboratory (reference) 3C046 FF03 FF10 FF17 FF19 FF22 FF25 4K029 AA04 BA41 BA44 BA48 BA54 BA55 BA60 BB02 BC00 BD05 EA01 4K030 BA18 BA35 BA36 BA38 BA41 BA43 BA46 BB12 CA03 JA01 LA01 LA22

Claims (1)

[Claims] 1. A hard coating layer comprising a lower layer, an intermediate layer and an upper layer is formed on the surface of a tungsten carbide-based cemented carbide substrate by chemical vapor deposition and / or physical vapor deposition with a total average layer thickness of 3 to 35 μm. A cutting tool made of a surface-coated cemented carbide is used. (A) The lower layers each have an average layer thickness of 0.1 to 20 μm, and a carbide layer, a nitride layer, an oxide layer, and a carbonitride of Ti. (B) the intermediate layer is an average layer having a thickness of 1 to 15 μm. Having a thickness,
And an aluminum oxide base layer comprising an aluminum oxide main layer having a structure in which 0.1 to 10% by weight of zirconium oxide is distributed as a dispersed phase in a proportion of the total amount of the aluminum oxide and the aluminum oxide. When the layer has an average layer thickness of 0.1 to 3 μm and is represented by the composition formula: TiO _x , the Ti oxide satisfies the following: X: an atomic ratio to Ti of 1.2 to 1.7. A layer having an average thickness of 0.05 to 2 μm and a composition formula: TiN _1-Y (O) _Y , where O in parentheses is (Indicating oxygen diffused from the surface underlayer), and an outermost surface layer composed of a Ti nitride layer satisfying an atomic ratio of 0.01 to 0.4 with respect to Y: Ti. Table with hard coating layer showing excellent chipping resistance in cutting Coated cemented carbide cutting tools.