JP4152055B2 - Chip-shaped cutting tool made of surface-coated cemented carbide with excellent heat-resistant plastic deformation with excellent hard coating layer in high-speed cutting of difficult-to-cut materials with high heat generation - Google Patents

Description

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【発明の効果】
表５〜７に示される結果から、ｌ−ＴｉＢＣＮ層を硬質被覆層の構成層とする本発明被覆超硬工具１〜６は、いずれも前記ｌ−ＴｉＢＣＮ層を平均層厚で４〜１３μ m に厚膜化したにもかかわらず、すぐれた耐熱塑性変形性を具備することから、ステンレス鋼や軟鋼の切削加工を高い発熱を伴う高速で行っても、硬質被覆層の塑性変形が抑制され、この結果切刃部の摩耗は正常摩耗となり、すぐれた耐摩耗性を長期に亘って発揮するのに対して、ｌ−ＴｉＣＮ層を構成層とする従来被覆超硬工具１〜６は、いずれも前記ｌ−ＴｉＣＮ層が切削時の高い発熱で塑性変形を起し、この結果切刃部に偏摩耗が発生し、これが摩耗進行を著しく促進することが明らかである。
上述のように、この発明の被覆超硬工具は、各種の鋼や鋳鉄などの通常の条件での切削加工は勿論のこと、特にステンレス鋼や軟鋼などの難削材の高速切削加工でもすぐれた切削性能を発揮し、汎用性のある切削性能を示すものであるから、切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。[0001]
BACKGROUND OF THE INVENTION
This invention is particularly resistant to heat and plastic deformation due to its excellent hard coating layer against the high heat generated when cutting difficult-to-cut materials such as stainless steel and mild steel that exhibit high cutting resistance due to its high viscosity. Since the uneven wear is remarkably suppressed by this, a surface-coated cemented carbide chip-shaped cutting tool (hereinafter referred to as a coated carbide tool) that exhibits excellent cutting performance over a long period of time. It is about.
[0002]
[Prior art]
Conventionally, generally, a hard coating layer is chemically formed with an average layer thickness of 5 to 30 μm on the surface of a chip-shaped tool base (hereinafter simply referred to as a tool base) made of tungsten carbide base cemented carbide or titanium carbonitride base cermet. A coated carbide tool formed by vapor deposition is known.
[0003]
Also, the hard coating layer,
(A) All have a grain crystal structure, Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer, carbonate ( Hereinafter, one or two or more layers of Ti charcoal / nitrogen / oxide layers composed of a layer represented by TiCO and a carbonitride (hereinafter represented by TiCNO) layer,
(B) an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer having a granular crystal structure,
(C) a Ti carbonitride (hereinafter referred to as 1-TiCN) layer having a vertically elongated crystal structure,
(A), (b), and (c), and the layer thickness of the TiC • N • O layer is relatively thin, while the Al ₂ O ₃ layer and l-TiCN layer are relatively Coated cemented carbide tools applied in a thick state are also known, and it is well known that this is used for continuous cutting and intermittent cutting of various steels and cast irons.
[0004]
Further, as the Al ₂ O ₃ layer constituting the hard coating layer of the above conventional coated carbide tool, those having an α-type crystal structure and those having a κ-type crystal structure are widely put into practical use and are also hard. The above-mentioned l-TiCN layer constituting the coating layer is, for example, organic carbonitriding as a reaction gas in a normal chemical vapor deposition apparatus as described in JP-A-6-8010 and JP-A-7-328808. It is also known that it is formed by chemical vapor deposition at a medium temperature range of 700 to 950 ° C. using a mixed gas containing an object, and the layer itself has excellent toughness.
[0005]
[Problems to be solved by the invention]
On the other hand, there are strong demands for labor saving and energy saving and cost reduction for cutting in recent years, and along with this, cutting tends to increase in speed. There is no problem when it is used for cutting under normal conditions such as steel and cast iron, but this is particularly suitable for high-speed cutting of difficult-to-cut materials such as stainless steel and mild steel, which are highly viscous and have high cutting resistance. If used, this cutting involves the generation of extremely high heat, so there is no problem with the Al ₂ O ₃ layer, which has excellent heat resistance even if it is made thicker. However, the l-TiCN layer with poor heat resistance is likely to be thermoplastically deformed, and this causes uneven wear on the cutting edge surface, resulting in a service life in a relatively short time. Currently.
[0006]
[Means for Solving the Problems]
In view of the above, the present inventors, in view of the above, generate uneven wear on the cutting edge surface even when used for high-speed cutting of difficult-to-cut materials such as stainless steel and mild steel, particularly with high heat generation. As a result of conducting research for the purpose of improving the heat-resistant plastic deformation property, focusing on the l-TiCN layer in the hard coating layer of the coated carbide tool, in particular, in order to develop a coated carbide tool having no coating,
(1) When forming the l-TiCN layer, which is a constituent layer of the hard coating layer of the above-mentioned conventional coated carbide tool, with a normal chemical vapor deposition apparatus, a condition in which boron chloride is blended in the reaction gas, for example, concrete In
Reactive gas composition in volume%
TiCl ₄ : 0.2 to 10%,
BCl ₃ : 0.03 to 1%
CH ₃ CN: 0.05~1%,
Ar: 5 to 50%
N ₂ : 30% or less as required
H ₂ : Remaining
And
Reaction atmosphere temperature: 700 to 950 ° C.
Reaction atmosphere pressure: 4 to 70 kPa,
When the layer is formed under the above conditions, a Ti borocarbonitride layer containing a B (boron) component in the l-TiCN layer is formed.
[0007]
(2) The Ti borocarbonitride layer obtained in (1) above has a vertically elongated crystal structure similar to the l-TiCN layer, and thus has excellent toughness.
Composition formula: TiBxCyNz,
(Wherein B represents boron, C represents carbon, and N represents nitrogen), the above layer formation conditions were adjusted, and the central portion in the thickness direction was measured with an Auger spectrometer. Atomic ratio to Ti,
x: 0.03-0.13,
y: 0.56-0.62
z: 0.25 to 0.40 (where x + y + z = 1),
When the Ti borocarbonitride (hereinafter referred to as 1-TiBCN) layer having a vertically elongated crystal structure is obtained, the heat resistance is remarkably improved, and the average layer thickness is 4 to 4. while thickened to 13μ m, it will be provided with excellent heat plastic deformation resistance.
[0008]
(3) The 1-TiBCN layer having an average layer thickness of 4 to 13 μm is applied as a hard coating layer together with the Al ₂ O ₃ layer having an average layer thickness of 2 to 11 μm, and the hard coating layer The
Between (a) a tool body and the l-TiBCN layer, the above TiC layer in which the mean layer thickness and 0.2～3.5Myu m none, one layer of TiN layer, and TiCN layer or Layers (hereinafter collectively referred to as TiC / TiN / TiCN layers),
(B) Any of the above-mentioned TiCO layer and TiCNO layer having an average layer thickness of 0.2 to 1 μm (hereinafter referred to as a TiCO / TiCNO layer) between the l-TiBCN layer and the Al ₂ O ₃ layer. )
(C) On the surface of the Al ₂ O ₃ layer, the TiN layer having an average layer thickness of 0.2 to 0.8 μm,
High-speed cutting accompanied by high heat generation of hard-to-cut materials such as stainless steel and mild steel with coated carbide tools with an average layer thickness of 8.1 to 28.1 μm Even when the l-TiBCN layer is used in a thick state as described above for processing, the l-TiBCN layer itself has excellent heat plastic deformation as described above, and also constitutes a hard coating layer. The Al ₂ O ₃ layer is also excellent in heat plastic deformation, while the other TiC / TiN / TiCN layers and TiCO / TiCNO layers do not have sufficient heat plastic deformation, but the l-TiBCN layer and Since the layer thickness is relatively thin compared to the Al ₂ O ₃ layer, the thermoplastic deformation of the hard coating layer is remarkably suppressed, and as a result, the occurrence of uneven wear on the cutting edge surface is eliminated. The surface does not maintain normal wear Et al, to exert excellent cutting performance over a long period of time.
The research results shown in (1) to (3) above were obtained.
[0009]
The present invention has been made based on the above research results, and the above-mentioned l-TiBCN layer having an average layer thickness of 4 to 13 μm and the average layer thickness of 2 to 11 μm on the surface of the tool base. A hard coating layer formed by chemical vapor deposition of an Al ₂ O ₃ layer as a constituent layer with an average layer thickness of 8.1 to 28.1 μm is used.
(A) between the tool substrate and the l-TiBCN layer, TiC / TiN / TiCN layer having an average layer thickness of both 0.2~3.5μ m,
(B) A TiCO / TiCNO layer having an average layer thickness of 0.2 to 1 μm between the l-TiBCN layer and the Al ₂ O ₃ layer,
(C) a TiN layer having an average layer thickness of 0.2 to 0.8 μm on the surface of the Al ₂ O ₃ layer;
And the l-TiBCN layer is
Composition formula: TiBxCyNz,
(Wherein B represents boron, C represents carbon, and N represents nitrogen), the central portion in the thickness direction was measured with an Auger spectroscopic analyzer.
x: 0.03-0.13,
y: 0.56-0.62
z: 0.25 to 0.40 (where x + y + z = 1),
It is characterized by a coated cemented carbide tool exhibiting heat-resistant plastic deformation with an excellent hard coating layer in high-speed cutting of difficult-to-cut materials with high heat generation.
[0010]
In the coated carbide tool of the present invention, the ratio (x) of boron (B) in the l-TiBCN layer constituting the hard coating layer was set to 0.03 to 0.13 in terms of atomic ratio to Ti. in the ratio is less than 0.03, particularly when thick film into 4～13Myu m in average thickness, occurs if no heat plastic deformation reliable improvement in properties is obtained caused by B, whereas the ratio This is because, if the value exceeds 0.13, a tendency to decrease in the excellent toughness brought about by the vertically grown crystal structure appears.
Further, carbon (C) constituting the l-TiBCN layer has an effect of increasing the hardness of the layer and thereby improving the wear resistance, but the ratio (y) is also 0.56 in terms of atomic ratio to Ti. If the ratio is less than 0.62, the desired hardness cannot be ensured in the layer. On the other hand, if it exceeds 0.62, the toughness of the layer itself is unavoidably reduced due to a relatively small proportion of nitrogen (N). Therefore, the ratio (y) was similarly determined to be 0.56 to 0.62 in terms of atomic ratio to Ti.
Further, nitrogen (N) constituting the l-TiBCN layer has an effect of contributing to improvement of toughness in combination with the vertically grown crystal structure of the layer, but the ratio (z) is also the atomic ratio with respect to Ti. If less than 0.25, the layer may not have a sufficient toughness improving effect. On the other hand, if it exceeds 0.40, the proportion of carbon (C) is relatively small and the hardness of the layer itself is reduced. Since a decreasing tendency appears and the wear resistance decreases, the ratio (z) was similarly set to 0.25 to 0.40 in terms of atomic ratio to Ti.
Note that in the l-TiBCN layer, the atomic ratio is equal to Ti and (B + C + N), so x + y + z = 1.
Further, the average layer thickness of the hard coating layer is set to 8.1 to 28.1 μm because if the layer thickness is less than 8.1 μm, the film thickness is insufficient and the desired excellent wear resistance is maintained for a long time. On the other hand, if the layer thickness exceeds 28.1 μm, the cutting edge is likely to be chipped or chipped.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated carbide tool of the present invention will be specifically described with reference to examples.
As raw material powders, WC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared, and these raw material powders are shown in Table 1. After blending into the blended composition, wet mixing with a ball mill for 72 hours, drying, and press-molding into a green compact at a pressure of 1.5 × 10 ⁸ Pa, the green compact is heated to 1400 ° C. at a temperature of 1400 ° C. Sintered under the condition of holding time, and after sintering, the cutting edge portion was subjected to honing processing of R: 0.05, and a tool base A-2 made of WC-based cemented carbide having a chip shape of ISO standard / CNMG120408 , A-5, and A-8 .
[0012]
In addition, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, NbC powder, TaC powder, WC powder, Co having an average particle diameter of 0.5 to 2 μm. Powders and Ni powders are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and then pressed at a pressure of 9.8 × 10 ⁷ Pa. The green compact was sintered in a nitrogen atmosphere of 1.3 × 10 ³ Pa at a temperature of 1540 ° C. for 1 hour, and after sintering, the cutting edge portion had R: 0.03 The tool bases B-1, B-4, and B-6 made of TiCN base cermet having the ISO standard / CNMG120212 chip shape were formed.
[0013]
Next, a normal chemical vapor deposition apparatus was used in a state where the surfaces of these tool bases A-2, A-5, and A-8 , and B-1, B-4, and B-6 were honed. Under the conditions shown in Tables 3 and 4, TiC / TiN layer / TiCN layer, TiCO / TiCNO layer , and Al ₂ O ₃ layer having the target composition also shown in Tables 3 and 4, and further 1-TiBCN layer or 1 -The present coated carbide tools 1-6 and the conventional coated carbide tools 1-6 were produced by forming a hard coating layer composed of a TiCN layer with the target layer thicknesses and combinations shown in Tables 5 and 6 , respectively.
[0014]
This result of the present invention coated cemented carbide tool 1-6 and the layers constituting the respective hard layer of the conventional coated cemented carbide tools 1 to 6, where the composition was measured using Auger spectroscopy apparatus, the target composition and substantially The same composition was shown and the thickness was measured by cross-section using a scanning electron microscope. As a result, all showed an average layer thickness (average value of 5-point measurement) substantially the same as the target layer thickness.
[0015]
Next, for the above-described coated carbide tools 1 to 6 and the conventional coated carbide tools 1 to 6 , in a state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SUS304 round bar,
Cutting speed: 250 m / min. ,
Incision: 1.5mm,
Feed: 0.2 mm / rev. ,
Cutting time: 10 minutes,
Stainless steel dry-type high-speed continuous turning test,
Work material: JIS / SUS304 lengthwise equidistant four round grooved round bars,
Cutting speed: 200 m / min. ,
Cutting depth: 1mm,
Feed: 0.2 mm / rev. ,
Cutting time: 5 minutes
Stainless steel dry high-speed intermittent turning test,
Work material: JIS / S15C round bar,
Cutting speed: 500 m / min. ,
Cutting depth: 2mm,
Feed: 0.3 mm / rev. ,
Cutting time: 10 minutes,
Dry high-speed continuous turning test of mild steel under the conditions of
Work material: JIS-S15C lengthwise equal length 4 round grooved round bar,
Cutting speed: 250 m / min. ,
Cutting depth: 1mm,
Feed: 0.2 mm / rev. ,
Cutting time: 5 minutes
A dry high-speed intermittent turning test of mild steel was performed under the conditions described above, and the maximum flank wear width of the cutting edge was measured in any turning test. The measurement results are shown in Table 7.
[0016]
[Table 1]

[0017]
[Table 2]

[0018]
[Table 3]

[0019]
[Table 4]

[0020]
[Table 5]

[0021]
[Table 6]

[0022]
[Table 7]

[0023]
【The invention's effect】
From the results shown in Table 5~7, l-TiBCN layer present invention coated cemented carbide 1 to 6, the layers constituting the hard layer of the, 4~13μ m both in average layer thickness of the l-TiBCN layer In spite of having increased film thickness, it has excellent heat-resistant plastic deformation, so even if cutting of stainless steel or mild steel is performed at high speed with high heat generation, plastic deformation of the hard coating layer is suppressed, As a result, the wear of the cutting edge portion becomes normal wear and exhibits excellent wear resistance over a long period of time, whereas the conventional coated carbide tools 1 to 6 having the l-TiCN layer as the constituent layers are all It is clear that the l-TiCN layer undergoes plastic deformation due to high heat generation during cutting, and as a result, uneven wear occurs at the cutting edge, which significantly accelerates the progress of wear.
As described above, the coated carbide tool of the present invention is excellent not only for cutting under normal conditions such as various steels and cast iron, but also for high-speed cutting of difficult-to-cut materials such as stainless steel and mild steel. Since it exhibits cutting performance and exhibits versatile cutting performance, it can sufficiently satisfy the labor-saving and energy-saving of cutting, and further cost reduction.

Claims (1)

On the surface of a chip-shaped tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet, a vertically grown crystal structure and a Ti boron carbonitride layer having an average layer thickness of 4 to 13 μm, a granular crystal structure, and A surface-coated cemented carbide chip-shaped cutting tool formed by chemical vapor deposition of a hard coating layer comprising an aluminum oxide layer having an average layer thickness of 2 to 11 μm as a constituent layer with an average layer thickness of 8.1 to 28.1 μm. , The hard coating layer,
(A) between the chip-shaped tool substrate and the Ti boron carbon nitride layer, both having an average layer thickness of the granular crystal structure and 0.2～3.5Myu m, carbide layer of Ti, a nitride layer, And one or two of the carbonitride layers,
(B) Between the Ti borocarbonitride layer and the aluminum oxide layer, each of a Ti carbonate layer and a carbonitride oxide layer having a granular crystal structure and an average layer thickness of 0.2 to 1 μm. One of them,
(C) a titanium nitride layer having a granular crystal structure and an average layer thickness of 0.2 to 0.8 μm on the surface of the aluminum oxide layer;
And the Ti borocarbonitride layer is
Composition formula: TiBxCyNz,
(Wherein B represents boron, C represents carbon, and N represents nitrogen), the central portion in the thickness direction was measured with an Auger spectroscopic analyzer.
x: 0.03-0.13,
y: 0.56-0.62
z: 0.25 to 0.40 (where x + y + z = 1),
Having a composition satisfying
A chip-shaped cutting tool made of a surface-coated cemented carbide that exhibits excellent heat-resistant plastic deformation with a hard coating layer in high-speed cutting of difficult-to-cut materials with high heat generation.