JP5569740B2 - Surface coated cutting tool with excellent chipping resistance - Google Patents
Surface coated cutting tool with excellent chipping resistance Download PDFInfo
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- 239000010410 layer Substances 0.000 claims description 278
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 64
- 239000010936 titanium Substances 0.000 claims description 60
- 150000001875 compounds Chemical class 0.000 claims description 53
- 239000013078 crystal Substances 0.000 claims description 42
- 239000002245 particle Substances 0.000 claims description 32
- 239000011247 coating layer Substances 0.000 claims description 26
- 238000000151 deposition Methods 0.000 claims description 10
- 239000011195 cermet Substances 0.000 claims description 6
- 238000005229 chemical vapour deposition Methods 0.000 claims description 6
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 5
- 150000004767 nitrides Chemical class 0.000 claims description 5
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 claims description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 2
- 229910052719 titanium Inorganic materials 0.000 claims description 2
- 239000000843 powder Substances 0.000 description 21
- 239000000758 substrate Substances 0.000 description 11
- 238000003917 TEM image Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 8
- 239000011229 interlayer Substances 0.000 description 8
- 238000012545 processing Methods 0.000 description 8
- 229910000831 Steel Inorganic materials 0.000 description 7
- 230000020169 heat generation Effects 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- 229910001018 Cast iron Inorganic materials 0.000 description 6
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 5
- 230000008021 deposition Effects 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000007740 vapor deposition Methods 0.000 description 4
- 238000005422 blasting Methods 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 3
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 3
- 239000012495 reaction gas Substances 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 229920006311 Urethane elastomer Polymers 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000032798 delamination Effects 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
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- 238000005245 sintering Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910001141 Ductile iron Inorganic materials 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910001315 Tool steel Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 102220358403 c.89C>G Human genes 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
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- 238000004299 exfoliation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
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Description
本発明は、例えば鋼や鋳鉄などの被削材を、高熱発生かつ切刃に断続的に高負荷を伴い、作用する高速断続切削条件下で切削加工した場合でも、硬質被覆層がすぐれた層間密着強度を有するため、切刃にチッピング（微小欠け）の発生なく、長期の使用に亘ってすぐれた切削性能を発揮する表面被覆切削工具（以下、被覆工具という）に関するものである。 The present invention provides an excellent hard coating layer even when a work material such as steel or cast iron is machined under high-speed intermittent cutting that works with high heat generation and intermittently high load on the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent cutting performance over a long period of use without causing chipping (microchips) on the cutting edge because it has adhesion strength.
従来、炭化タングステン基超硬合金製基体（以下、超硬基体という）あるいはＴｉＣＮ基サーメット基体（以下、サーメット基体という。また、超硬基体とサーメット基体とを総称して、工具基体という）の表面に、
（ａ）下部層が、３〜２０μｍの全体平均層厚を有するＴｉＣ層、ＴｉＮ層、ＴｉＣＮ層、ＴｉＣＯ層およびＴｉＣＮＯ層のうちの１層または２層以上からなるＴｉ化合物層、
（ｂ）上部層が、１〜１５μｍの平均層厚を有し、化学蒸着形成された状態でα型の結晶構造を有する酸化アルミニウム（以下、Ａｌ２Ｏ３で示す）層、
上記（ａ）、（ｂ）からなる硬質被覆層を蒸着形成した被覆工具が広く知られており（例えば、特許文献１）、この被覆工具は、鋼や鋳鉄などの切削加工において、すぐれた耐摩耗性を発揮することが知られている。
また、被覆工具の耐欠損性、耐衝撃性、耐摩耗性等を向上させるため、硬質被覆層の下部層を構成するＴｉＣＮ層の粒子幅を０．０１〜０．５μｍとした被覆工具も知られている（例えば、特許文献２）。
Conventionally, the surface of a tungsten carbide-based cemented carbide substrate (hereinafter referred to as a cemented carbide substrate) or a TiCN-based cermet substrate (hereinafter referred to as a cermet substrate. The cemented carbide substrate and the cermet substrate are collectively referred to as a tool substrate). In addition,
(A) a Ti compound layer composed of one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer having a total average layer thickness of 3 to 20 μm,
(B) an aluminum oxide (hereinafter referred to as Al 2 O 3 ) layer having an average layer thickness of 1 to 15 μm and having an α-type crystal structure in a state where the upper layer is formed by chemical vapor deposition;
A coated tool in which a hard coating layer composed of the above (a) and (b) is formed by vapor deposition is widely known (for example, Patent Document 1), and this coated tool has excellent resistance to cutting in steel or cast iron. It is known to exhibit wear.
Also known is a coated tool in which the particle width of the TiCN layer constituting the lower layer of the hard coating layer is 0.01 to 0.5 μm in order to improve the fracture resistance, impact resistance, wear resistance, etc. of the coated tool. (For example, Patent Document 2).
近年の切削加工の省力化および省エネ化に対する要求は強く、これに伴い、切削加工はますます高速化、高効率化の傾向にあり、その反面、工具寿命の延命化を図るという点から硬質被覆層の厚膜化も求められているが、下部層としてＴｉ化合物層、上部層としてＡｌ２Ｏ３層からなる硬質被覆層を形成した従来被覆工具を用いて鋼、鋳鉄の高速断続切削加工を行うと、硬質被覆層に微小チッピング、層間剥離等を生じ、これを原因として、比較的短時間で使用寿命に至るのが現状である。 In recent years, there has been a strong demand for labor saving and energy saving of cutting work, and along with this, cutting work is becoming increasingly faster and more efficient. On the other hand, hard coating is required in order to extend the tool life. Although a thicker layer is also required, high-speed intermittent cutting of steel and cast iron is performed using a conventional coated tool in which a hard coating layer composed of a Ti compound layer as a lower layer and an Al 2 O 3 layer as an upper layer is formed. If it does, micro chipping, delamination, etc. will occur in the hard coating layer, and the present situation is that the service life is reached in a relatively short time due to this.
そこで、本発明者らは、被覆工具の耐チッピング性、耐剥離性を改善すべく、硬質被覆層の層構造について鋭意研究を行った結果、次のような知見を得た。 Therefore, as a result of intensive studies on the layer structure of the hard coating layer in order to improve the chipping resistance and peel resistance of the coated tool, the present inventors have obtained the following knowledge.
被覆工具の硬質被覆層のうち、ＴｉＣ層、ＴｉＮ層、ＴｉＣＮ層、ＴｉＣＯ層およびＴｉＣＮＯ層のうちの１層または２層以上から形成されるＴｉ化合物層からなる下部層は、それ自身の具備するすぐれた高温強度によって硬質被覆層の高温強度向上に寄与し、また、Ａｌ２Ｏ３層からなる上部層は、耐酸化性と熱的安定性にすぐれ、さらに高硬度を有するが、高熱発生を伴い、切刃に高負荷が断続的に作用する高速断続切削では、下部層−上部層間の密着強度が十分でないため、これが微小チッピング、層間剥離発生の要因となる。
そこで、下部層−上部層の界面密着強度を高めるため、両層の密着界面領域の改質について、数多くの実験を重ねた結果、工具領域を切れ刃部、逃げ面部およびすくい面部からなる３領域に分けた際に、その領域ごとに下部層と上部層とが隣接する界面の結晶粒構造を改善することにより、下部層と上部層の界面密着強度が高められることを見出したのである。
具体的には、切れ刃部においては、Ａｌ２Ｏ３層直下の下部層を構成するＴｉ化合物層の平均粒子径を０．１μｍ以下にすると共に、下部層と上部層とが隣接する界面に存在する下部層側の結晶粒（Ｔｉ化合物）の数ａ１と上部層側の結晶粒（Ａｌ２Ｏ３）の数ｂ１との比率ｂ１／ａ１が、０．８≦ｂ１／ａ１≦１．２を満足するように下部層および上部層を蒸着形成するとともに、逃げ面部およびすくい面部においては、Ａｌ２Ｏ３層直下の下部層を構成するＴｉ化合物層の平均粒子径を０．１〜０．５μｍにすると共に、下部層と上部層とが隣接する界面に存在する下部層側の結晶粒（Ｔｉ化合物）の数ａ２と上部層側の結晶粒（Ａｌ２Ｏ３）の数ｂ２との比率ｂ２／ａ２が、４≦ｂ２／ａ２≦２０を満足するように下部層および上部層を蒸着形成することによって、工具領域全体にわたって下部層と上部層との界面に発生する歪みが緩和されることにより、下部層−上部層界面の層間密着性が高められる。
そして、その結果として、高熱発生を伴い、切刃に高負荷が断続的に作用する高速断続切削加工においても、チッピング、剥離の発生なく、長期の使用に亘って優れた耐摩耗性を発揮することができることを見出したのである。
Of the hard coating layer of the coated tool, the lower layer made of a Ti compound layer formed of one or more of the TiC layer, TiN layer, TiCN layer, TiCO layer and TiCNO layer is itself provided. Excellent high-temperature strength contributes to improving the high-temperature strength of the hard coating layer, and the upper layer composed of the Al 2 O 3 layer has excellent oxidation resistance and thermal stability and has high hardness, but generates high heat. Accordingly, in high-speed intermittent cutting in which a high load acts intermittently on the cutting edge, the adhesion strength between the lower layer and the upper layer is not sufficient, and this causes microchipping and delamination.
Therefore, in order to increase the adhesion strength between the lower layer and the upper layer, a number of experiments were conducted on the modification of the adhesion interface region between the two layers. It was found that the interface adhesion strength between the lower layer and the upper layer can be increased by improving the crystal grain structure of the interface where the lower layer and the upper layer are adjacent to each other.
Specifically, in the cutting edge portion, the average particle diameter of the Ti compound layer constituting the lower layer immediately below the Al 2 O 3 layer is 0.1 μm or less, and the lower layer and the upper layer are adjacent to the interface. The ratio b1 / a1 between the number a1 of the lower layer side crystal grains (Ti compound) and the number b1 of the upper layer side crystal grains (Al 2 O 3 ) is 0.8 ≦ b1 / a1 ≦ 1.2. The lower layer and the upper layer are formed by vapor deposition so as to satisfy the above conditions, and the average particle diameter of the Ti compound layer constituting the lower layer immediately below the Al 2 O 3 layer is 0.1 to 0. The ratio of the number a2 of the lower layer side crystal grains (Ti compound) and the number b2 of the upper layer side crystal grains (Al 2 O 3 ) existing at the interface where the lower layer and the upper layer are adjacent to each other to 5 μm b2 / a2 is lower layers Contact to satisfy 4 ≦ b2 / a2 ≦ 20 By depositing formed fine upper layer, by the distortion generated at the interface between the lower layer and the upper layer over the tool region is relaxed, the lower layer - interlayer adhesion of the upper layer interface is enhanced.
As a result, even in high-speed intermittent cutting with high heat generation and high load intermittently acting on the cutting edge, it exhibits excellent wear resistance over a long period of use without occurrence of chipping and peeling. I found out that I could do it.
本発明は、前記知見に基づいてなされたものであって、
「 炭化タングステン基超硬合金または炭窒化チタン基サーメットで構成された工具基体の表面に、下部層と上部層とからなる硬質被覆層を蒸着形成した表面被覆切削工具において、工具領域を切れ刃部、逃げ面部およびすくい面部からなる３領域に分けた際に、
（ａ）切れ刃部においては、
下部層は、Ｔｉの炭化物層、窒化物層、炭窒化物層、炭酸化物層および炭窒酸化物層のうちの１層または２層以上からなり、かつ、３〜２０μｍの全体平均層厚を有するＴｉ化合物層からなり、
上部層は、化学蒸着した状態で１〜１５μｍの平均層厚を有するα型の結晶構造を有するＡｌ２Ｏ３層からなり、
上記下部層と上記上部層とが隣接する界面に存在する上記Ｔｉ化合物層側の結晶粒の数ａ１と上記Ａｌ２Ｏ３層側の結晶粒の数ｂ１との比率ｂ１／ａ１が０．８≦ｂ１／ａ１≦１．２を満足し、さらに、上記Ａｌ２Ｏ３層直下のＴｉ化合物層の結晶粒の平均粒子径が０．１μｍ以下であることを満足し、
（ｂ）逃げ面部およびすくい面部においては、
下部層は、Ｔｉの炭化物層、窒化物層、炭窒化物層、炭酸化物層および炭窒酸化物層のうちの１層または２層以上からなり、かつ、３〜２０μｍの全体平均層厚を有するＴｉ化合物層からなり、
上部層は、化学蒸着した状態で１〜１５μｍの平均層厚を有するα型の結晶構造を有するＡｌ２Ｏ３層からなり、
上記下部層と上記上部層とが隣接する界面に存在する上記Ｔｉ化合物層側の結晶粒の数ａ２と上記Ａｌ２Ｏ３層側の結晶粒の数ｂ２との比率ｂ２／ａ２が４≦ｂ２／ａ２≦２０を満足し、さらに、上記Ａｌ２Ｏ３層直下のＴｉ化合物層の結晶粒の平均粒子径が０．１〜０．５μｍであることを満足する、
以上（ａ）および（ｂ）から構成された硬質被覆層を蒸着形成してなることを特徴とする表面被覆切削工具。」
に特徴を有するものである。
The present invention has been made based on the above findings,
`` In a surface-coated cutting tool in which a hard coating layer consisting of a lower layer and an upper layer is vapor-deposited on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet, When divided into three areas consisting of flank and rake face,
(A) In the cutting edge part,
The lower layer is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer, and has an overall average layer thickness of 3 to 20 μm. A Ti compound layer having
The upper layer is composed of an Al 2 O 3 layer having an α-type crystal structure having an average layer thickness of 1 to 15 μm in the state of chemical vapor deposition,
Ratio b1 / a1 between the number b1 of the Ti compound layer side of the number a1 and the the Al 2 O 3 layer side of the crystal grains the crystal grains at the interface of the the lower layer and the upper layer is adjacent 0.8 ≦ b1 / a1 ≦ 1.2 is satisfied, and further, the average particle diameter of the crystal grains of the Ti compound layer immediately below the Al 2 O 3 layer is 0.1 μm or less,
(B) In the flank face and the rake face part,
The lower layer is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer, and has an overall average layer thickness of 3 to 20 μm. A Ti compound layer having
The upper layer is composed of an Al 2 O 3 layer having an α-type crystal structure having an average layer thickness of 1 to 15 μm in the state of chemical vapor deposition,
The number of the Ti compound layer side of the crystal grains at the interface of the the lower layer and the upper layer is adjacent a2 and the the Al 2 O 3 layer side of the ratio b2 / a2 is 4 ≦ the number b2 of grain b2 Satisfying / a2 ≦ 20 , and further satisfying that the average particle diameter of the crystal grains of the Ti compound layer immediately below the Al 2 O 3 layer is 0.1 to 0.5 μm.
A surface-coated cutting tool obtained by vapor-depositing a hard coating layer composed of (a) and (b) above. "
It has the characteristics.
以下に、本発明の被覆工具の硬質被覆層について、詳細に説明する。
（ａ）下部層（Ｔｉ化合物層）
Ｔｉの炭化物（ＴｉＣ）層、窒化物（ＴｉＮ）層、炭窒化物（ＴｉＣＮ）層、炭酸化物（ＴｉＣＯ）層および炭窒酸化物（ＴｉＣＮＯ）層のうちの１層または２層以上からなるＴｉ化合物層は、硬質被覆層の下部層として存在し、自身の具備するすぐれた高温強度によって硬質被覆層の高温強度向上に寄与するが、その合計平均層厚が３μｍ未満では、前記作用を十分に発揮させることができず、一方その合計平均層厚が２０μｍを越えると、特に高熱発生を伴い、切刃に高負荷が断続的に作用する高速断続切削では熱塑性変形を起し易くなり、これが偏摩耗の原因となることから、その平均層厚を３〜２０μｍと定めた。
また、切れ刃部においては、Ａｌ２Ｏ３層直下のＴｉ化合物層の平均粒子径が０．１μｍを超えると、上部層（Ａｌ２Ｏ３層）と下部層Ａｌ２Ｏ３層直下のＴｉ化合物層と層間密着性が低下し、耐チッピング性が劣化するため、Ａｌ２Ｏ３層直下のＴｉ化合物層の平均粒子径は０．１μｍ以下と定めた。一方、逃げ面部およびすくい面部においては、Ａｌ２Ｏ３層直下のＴｉ化合物層の平均粒子径が０．５μｍを超えると、上部層（Ａｌ２Ｏ３層）と上部層Ａｌ２Ｏ３層直下のＴｉ化合物層と層間密着性が低下し、耐チッピング性が劣化し、また、結晶粒が粗大となって高温強度が低下し、耐摩耗性も劣化するために、Ａｌ２Ｏ３層直下のＴｉ化合物層の平均粒子径が０．１μｍより小さいと耐欠損性、耐衝撃性、耐摩耗性が低下するため、Ａｌ２Ｏ３層直下のＴｉ化合物層の平均粒子径は０．１〜０．５μｍと定めた。
ここで、切れ刃部および逃げ面部、すくい面部を上記範囲内とするために、工具基体に、切れ刃部以外を硬質ウレタンゴムなどでカバーし切れ刃部のみをウエットブラスト処理を施し、工具基体における切れ刃部の表面荒さをＲａ：０．２μｍ以下とした。ウエットブラスト処理の加工条件は、噴射研磨剤として、水との合量に占める割合で１５〜６０質量％の酸化アルミニウム微粒を配合した研磨液を噴射する。
なお、平均粒子径とは、透過型電子顕微鏡の断面観察により超硬基体表面と平行な方向に５０μｍに渡って線を引き、Ａｌ２Ｏ３層直下のＴｉ化合物層の結晶粒の結晶粒界との交点を数え、それら線分長さの平均から求めた粒子径である。
Below, the hard coating layer of the coating tool of this invention is demonstrated in detail.
(A) Lower layer (Ti compound layer)
Ti composed of one or more of Ti carbide (TiC) layer, nitride (TiN) layer, carbonitride (TiCN) layer, carbonate (TiCO) layer and carbonitride oxide (TiCNO) layer The compound layer exists as a lower layer of the hard coating layer and contributes to the improvement of the high temperature strength of the hard coating layer by its excellent high temperature strength. However, when the total average layer thickness is less than 3 μm, the above-described effect is sufficiently obtained. On the other hand, if the total average layer thickness exceeds 20 μm, high-temperature intermittent cutting, particularly with high heat generation and high load intermittently acting on the cutting blade, tends to cause thermoplastic deformation. Since it causes wear, the average layer thickness is determined to be 3 to 20 μm.
Moreover, in the cutting edge part, when the average particle diameter of the Ti compound layer immediately below the Al 2 O 3 layer exceeds 0.1 μm, the Ti layer immediately below the upper layer (Al 2 O 3 layer) and the lower layer Al 2 O 3 layer. Since the adhesion between the compound layer and the interlayer is lowered and chipping resistance is deteriorated, the average particle size of the Ti compound layer immediately below the Al 2 O 3 layer is determined to be 0.1 μm or less. On the other hand, in the flank face and the rake face part, when the average particle diameter of the Ti compound layer immediately below the Al 2 O 3 layer exceeds 0.5 μm, the upper layer (Al 2 O 3 layer) and the upper layer Al 2 O 3 layer immediately below and of Ti decreases compound layer and the interlayer adhesion, chipping resistance deteriorates, and high-temperature strength decreases becomes crystal grains coarse, wear resistance to deterioration, just below the Al 2 O 3 layer When the average particle size of the Ti compound layer is smaller than 0.1 μm, the chipping resistance, impact resistance, and wear resistance are reduced. Therefore, the average particle size of the Ti compound layer immediately below the Al 2 O 3 layer is 0.1 to 0. .5 μm.
Here, in order to make the cutting edge part, the flank face part, and the rake face part within the above range, the tool base is covered with hard urethane rubber other than the cutting edge part, and only the cutting edge part is subjected to wet blasting, and the tool base is provided. The surface roughness of the cutting edge portion was set to Ra: 0.2 μm or less. The processing conditions of the wet blast treatment are as follows. A polishing liquid in which 15 to 60% by mass of aluminum oxide fine particles are mixed as a spraying abrasive in a ratio to the total amount with water is sprayed.
The average particle diameter is a grain boundary of the crystal grain of the Ti compound layer directly under the Al 2 O 3 layer by drawing a line over 50 μm in a direction parallel to the surface of the carbide substrate by cross-sectional observation with a transmission electron microscope. Is the particle diameter obtained from the average of the lengths of the line segments.
（ｂ）上部層（Ａｌ２Ｏ３層）
上部層を構成するＡｌ２Ｏ３層は、高温硬さおよび耐熱性にすぐれ、高熱発生を伴い、切刃に高負荷が断続的に作用する高速切削加工において、基本的な役割として耐摩耗性を維持する。
Ｔｉ化合物層からなる下部層表面に、例えば、以下の手順でＡｌ2Ｏ３蒸着前処理を行い、ついで、通常条件でＡｌ2Ｏ３層を成膜することにより、本発明で規定する条件を満足するＡｌ2Ｏ３層を形成することができる。
Ａｌ2Ｏ３蒸着前処理は、以下の４段階からなり、
まず、
《第１段階》
反応ガス（容量％）： ＡｌＣｌ３ ０．５〜２％， 残部Ａｒ、
雰囲気圧力： ３０〜１００Ｔｏｒｒ、
処理温度： ７５０〜１０００℃、
処理時間： １〜３ｍｉｎ．、
の条件で下部層の表面改質を行った後、
《第２段階》
雰囲気圧力： ３０〜１００Ｔｏｒｒ、
雰囲気温度： ７５０〜１０００℃、
に維持した状態で、１〜３分間、Ａｒガスで炉内ガスをパージし、
《第３段階》
反応ガス（容量％）： ＣＯ２ １〜１０％， 残部Ａｒ、
雰囲気圧力： ３０〜１００Ｔｏｒｒ、
処理温度： ７５０〜１０００℃、
処理時間： ５〜２０ｍｉｎ、
の条件（但し、時間の経過とともに、反応ガス中のＣＯ２の含有割合を徐々に減少させる）で酸化処理を行い、
《第４段階》
雰囲気圧力： ３０〜１００Ｔｏｒｒ、
雰囲気温度： ７５０〜１０００℃、
に維持した状態で、１〜３分間、Ａｒガスで炉内ガスをパージする。
(B) Upper layer (Al 2 O 3 layer)
The Al 2 O 3 layer that constitutes the upper layer is excellent in high-temperature hardness and heat resistance, is accompanied by high heat generation, and wear resistance as a fundamental role in high-speed cutting processing in which a high load acts intermittently on the cutting edge To maintain.
For example, the Al 2 O 3 deposition pretreatment is performed on the surface of the lower layer made of the Ti compound layer by the following procedure, and then the Al 2 O 3 layer is formed under normal conditions, thereby satisfying the conditions defined in the present invention. A satisfactory Al 2 O 3 layer can be formed.
Al 2 O 3 deposition pretreatment consists of the following four stages:
First,
<< First stage >>
Reaction gas (volume%): AlCl 3 0.5-2%, balance Ar,
Atmospheric pressure: 30-100 Torr,
Processing temperature: 750 to 1000 ° C.
Processing time: 1-3 min. ,
After surface modification of the lower layer under the conditions of
<< Second stage >>
Atmospheric pressure: 30-100 Torr,
Atmospheric temperature: 750-1000 ° C.
In this state, the gas in the furnace is purged with Ar gas for 1 to 3 minutes.
《Third stage》
Reaction gas (volume%): CO 2 1-10%, balance Ar,
Atmospheric pressure: 30-100 Torr,
Processing temperature: 750 to 1000 ° C.
Processing time: 5-20 min,
The oxidation treatment is performed under the conditions (however, the content ratio of CO 2 in the reaction gas is gradually reduced as time passes)
<< Fourth Stage >>
Atmospheric pressure: 30-100 Torr,
Atmospheric temperature: 750-1000 ° C.
In this state, the furnace gas is purged with Ar gas for 1 to 3 minutes.
上記４段階のＡｌ２Ｏ３蒸着前処理を行った後、通常の成膜法でＡｌ２Ｏ３層を成膜することにより、本発明で規定する条件を満足するＡｌ２Ｏ３層を形成することができる。即ち、切れ刃部において、工具基体表面に垂直方向な断面における下部層（Ｔｉ化合物層）と上部層（Ａｌ２Ｏ３層）とが隣接する界面に存在する下部層側のＴｉ化合物結晶粒の数ａ１と上部層側のＡｌ２Ｏ３結晶粒の数ｂ１との比率ｂ１／ａ１を求めた場合に、ｂ１／ａ１が０．８以上で１．２以下となる界面形態を備えた上部層を蒸着形成することができる。
上記ａ１，ｂ１の比の値ｂ１／ａ１について、ｂ１／ａ１が０．８未満である場合には、切れ刃部の下部層−上部層界面におけるミスフィットを十分に緩和することができなくなり、一方、ｂ１／ａ１が１．２を超えると、Ａｌ２Ｏ３内の粒子間歪みが増大し、すぐれた層間密着性を発揮し得なくなるため、ｂ１／ａ１は、０．８≦ｂ１／ａ１≦１．２と定めた。
また、逃げ面部およびすくい面部において、工具基体表面に垂直方向な断面における下部層（Ｔｉ化合物層）と上部層（Ａｌ２Ｏ３層）とが隣接する界面に存在する下部層側のＴｉ化合物結晶粒の数ａ２と上部層側のＡｌ２Ｏ３結晶粒の数ｂ２との比率ｂ２／ａ２を求めた場合に、ｂ２／ａ２が４以上で２０以下となる界面形態を備えた上部層を蒸着形成することができる。
上記ａ２，ｂ２の比の値ｂ２／ａ２について、ｂ２／ａ２が４未満である場合には、逃げ面部およびすくい面部の下部層−上部層界面におけるミスフィットを十分に緩和することができなくなり、一方、ｂ２／ａ２が２０を超えると、Ａｌ２Ｏ３内の粒子間歪みが増大し、すぐれた層間密着性を発揮し得なくなるため、ｂ２／ａ２は、４≦ｂ２／ａ２≦２０と定めた。
ここで、下部層（Ｔｉ化合物層）と上部層（Ａｌ２Ｏ３層）とが隣接する界面に存在する下部層側のＴｉ化合物結晶粒の数ａ１、ａ２と上部層側のＡｌ２Ｏ３結晶粒の数ｂ１、ｂ２の測定は、下部層−上部層との界面１０箇所について、透過型電子顕微鏡を用い、５００００倍の暗視野観察による断面測定を行い、超硬基体表面に平行な直線距離を測定幅２５μｍとし、その範囲に存在するＡｌ２Ｏ３粒子と界面を有しているＴｉ化合物粒子の数およびＴｉ化合物粒子と界面を有しているＡｌ２Ｏ３粒子の数のそれぞれをカウントすることにより、求めることができる。
この様な界面形態を備えた上部層と下部層からなる本発明の硬質被覆層は、界面歪みが緩和されることによって、すぐれた層間密着性を有するようになり、高速断続切削加工における微小チッピングの発生、剥離の発生を抑制するようになる。
上部層の平均層厚が１μｍ未満では、長期の使用に亘って耐摩耗性を十分に発揮することができず、工具寿命の短命化を招き、一方、上部層の平均層厚が１５μｍを超えるようになると、切れ刃部にチッピング、欠損、剥離等が発生し易くなることから、上部層の平均層厚は、１〜１５μｍと定めた。
After performing the four-stage Al 2 O 3 deposition pretreatment, an Al 2 O 3 layer that satisfies the conditions defined in the present invention is formed by forming an Al 2 O 3 layer by a normal film formation method. can do. That is, in the cutting edge portion, the lower layer side Ti compound crystal grains existing at the interface adjacent to the lower layer (Ti compound layer) and the upper layer (Al 2 O 3 layer) in the cross section perpendicular to the tool base surface. An upper layer having an interface configuration in which b1 / a1 is 0.8 or more and 1.2 or less when the ratio b1 / a1 between the number a1 and the number b1 of Al 2 O 3 crystal grains on the upper layer side is obtained Can be formed by vapor deposition.
When b1 / a1 is less than 0.8 for the ratio b1 / a1 of the a1, b1, the misfit at the lower layer-upper layer interface of the cutting edge cannot be sufficiently relaxed, On the other hand, if b1 / a1 exceeds 1.2, the inter-particle strain in Al 2 O 3 increases and it becomes impossible to exhibit excellent interlayer adhesion, so b1 / a1 is 0.8 ≦ b1 / a1 ≤1.2 .
Further, in the flank face and the rake face part, the lower layer side Ti compound crystal exists at the interface where the lower layer (Ti compound layer) and the upper layer (Al 2 O 3 layer) are adjacent to each other in the cross section perpendicular to the tool base surface. If the calculated ratio b2 / a2 between the number a2 the number of the upper layer side of the Al 2 O 3 crystal grains b2 grain, depositing a top layer having a surface form composed of 20 or less in b2 / a2 is 4 or more Can be formed.
When b2 / a2 is less than 4 for the ratio b2 / a2 of the above a2 and b2, it becomes impossible to sufficiently relieve misfit at the lower layer-upper layer interface of the flank face and the rake face part, On the other hand, if b2 / a2 exceeds 20, the strain between particles in Al 2 O 3 increases and it becomes impossible to exhibit excellent interlayer adhesion. Therefore, b2 / a2 is determined as 4 ≦ b2 / a2 ≦ 20. It was.
Here, the numbers a1 and a2 of the Ti compound crystal grains on the lower layer side existing at the interface where the lower layer (Ti compound layer) and the upper layer (Al 2 O 3 layer) are adjacent to each other and Al 2 O 3 on the upper layer side The number of crystal grains b1 and b2 is measured by measuring a cross section by dark field observation at 50000 times using a transmission electron microscope at 10 points of the interface between the lower layer and the upper layer, and a straight line parallel to the surface of the carbide substrate. The distance is a measurement width of 25 μm, and the number of Ti compound particles having an interface with Al 2 O 3 particles existing in the range and the number of Al 2 O 3 particles having an interface with Ti compound particles are respectively determined. It can be obtained by counting.
The hard coating layer of the present invention consisting of an upper layer and a lower layer having such an interface form has excellent interlaminar adhesion due to the relaxation of the interface strain, and microchipping in high-speed intermittent cutting processing. Generation and exfoliation are suppressed.
If the average layer thickness of the upper layer is less than 1 μm, the wear resistance cannot be sufficiently exhibited over a long period of use, leading to a shortened tool life, while the average layer thickness of the upper layer exceeds 15 μm. As a result, chipping, chipping, peeling, and the like are likely to occur at the cutting edge, so the average layer thickness of the upper layer was determined to be 1 to 15 μm.
この発明の被覆工具は、硬質被覆層として、Ｔｉ化合物層からなる下部層とＡｌ２Ｏ３層からなる上部層を蒸着形成したものにおいて、切れ刃部においては、下部層と上部層との隣接界面に存在する下部層側のＴｉ化合物結晶粒の数ａ１と上部層側のＡｌ２Ｏ３結晶粒の数ｂ１との比率ｂ１／ａ１が０．８≦ｂ１／ａ１≦１．２を満足する界面構造を構成し、さらに、Ａｌ２Ｏ３層直下のＴｉ化合物層の結晶粒の平均粒子径を０．１μｍ以下とし、逃げ面部およびすくい面部においては、下部層と上部層との隣接界面に存在する下部層側のＴｉ化合物結晶粒の数ａ２と上部層側のＡｌ２Ｏ３結晶粒の数ｂ２との比率ｂ２／ａ２が４≦ｂ２／ａ２≦２０を満足する界面構造を構成し、さらに、Ａｌ２Ｏ３層直下のＴｉ化合物層の結晶粒の平均粒子径を０．１〜０．５μｍとしていることから、特に、下部層と上部層間の層間密着性が高められ、その結果、例えば鋼、鋳鉄などの、高熱発生を伴い、切れ刃部に高負荷が断続的に作用する高速断続切削加工に用いた場合でも、硬質被覆層がすぐれた層間密着強度を有するため、切れ刃部に微小チッピング、剥離等の発生なく、長期の使用に亘ってすぐれた耐摩耗性を発揮することができる。 In the coated tool of the present invention, as a hard coating layer, a lower layer made of a Ti compound layer and an upper layer made of an Al 2 O 3 layer are formed by vapor deposition. In the cutting edge portion, the lower layer and the upper layer are adjacent to each other. A ratio b1 / a1 between the number a1 of Ti compound crystal grains on the lower layer side present at the interface and the number b1 of Al 2 O 3 crystal grains on the upper layer side satisfies 0.8 ≦ b1 / a1 ≦ 1.2 . The interface structure is configured, and the average particle diameter of the crystal grains of the Ti compound layer immediately below the Al 2 O 3 layer is 0.1 μm or less, and the flank face and the rake face part are adjacent to the interface between the lower layer and the upper layer. configure interface structure the ratio b2 / a2 between the Al 2 O 3 number of grains b2 of Ti compound crystal grains number a2 and the upper layer side of the lower layer side satisfies 4 ≦ b2 / a2 ≦ 20 present, Furthermore, crystals of the Ti compound layer immediately below the Al 2 O 3 layer Since the average particle diameter of 0.1 to 0.5 μm is particularly improved, the interlaminar adhesion between the lower layer and the upper layer is enhanced, and as a result, for example, steel, cast iron, etc., with high heat generation, the cutting edge portion Even when used for high-speed intermittent cutting where high loads act intermittently, the hard coating layer has excellent interlaminar adhesion strength, so there is no microchipping or peeling at the cutting edge and it can be used for a long time. Excellent wear resistance can be demonstrated.
つぎに、この発明の被覆工具を実施例により具体的に説明する。 Next, the coated tool of the present invention will be specifically described with reference to examples.
原料粉末として、いずれも２〜４μｍの平均粒径を有するＷＣ粉末、ＴｉＣ粉末、ＺｒＣ粉末、ＶＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｃｒ3Ｃ2粉末、ＴｉＮ粉末、ＴａＮ粉末、およびＣｏ粉末を用意し、これら原料粉末を、表１に示される配合組成に配合し、さらにワックスを加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、９８ＭＰａの圧力で所定形状の圧粉体にプレス成形し、この圧粉体を５Ｐａの真空中、１３７０〜１４７０℃の範囲内の所定の温度に１時間保持の条件で真空焼結し、焼結後、切れ刃部にＲ：０．０７ｍｍのホーニング加工を施すことによりＩＳＯ・ＣＮＭＧ１６０４１２に規定するスローアウエイチップ形状をもったＷＣ基超硬合金製の工具基体Ａ〜Ｆをそれぞれ製造した。 WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr 3 C 2 powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 2 to 4 μm are prepared as raw material powders. These raw material powders were blended into the composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact with a predetermined shape at a pressure of 98 MPa. Then, this green compact was vacuum sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour, and after sintering, the cutting edge portion was honed with R: 0.07 mm. By processing, tool bases A to F made of a WC-based cemented carbide having a throwaway tip shape defined in ISO · CNMG 160412 were produced.
また、原料粉末として、いずれも０．５〜２μｍの平均粒径を有するＴｉＣＮ（質量比でＴｉＣ／ＴｉＮ＝５０／５０）粉末、Ｍｏ2Ｃ粉末、ＺｒＣ粉末、ＮｂＣ粉末、ＴａＣ粉末、ＷＣ粉末、Ｃｏ粉末、およびＮｉ粉末を用意し、これら原料粉末を、表２に示される配合組成に配合し、ボールミルで２４時間湿式混合し、乾燥した後、９８ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を１．３ｋＰａの窒素雰囲気中、温度：１５４０℃に１時間保持の条件で焼結し、焼結後、切れ刃部分にＲ：０．０７ｍｍのホーニング加工を施すことによりＩＳＯ規格・ＣＮＭＧ１６０４１２のチップ形状をもったＴｉＣＮ基サーメット製の工具基体ａ〜ｆを形成した。 In addition, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo 2 C powder, ZrC powder, NbC powder, TaC powder, WC powder, all having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder 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 pressed into a compact at a pressure of 98 MPa. The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour. After sintering, the cutting edge portion was subjected to a honing process of R: 0.07 mm. Tool bases a to f made of TiCN-based cermet having standard / CNMG 160412 chip shapes were formed.
ついで、切れ刃部以外を硬質ウレタンゴム等でカバーし、切れ刃部のみに水との合量に占める割合で１５〜６０質量％の酸化アルミニウム微粒を配合した研磨液を噴射してウエットブラスト処理を施し、
ついで、これらの工具基体Ａ〜Ｆおよび工具基体ａ〜ｆのそれぞれを、通常の化学蒸着装置に装入し、まず、表３（表３中のｌ−ＴｉＣＮは特開平６−８０１０号公報に記載される縦長成長結晶組織をもつＴｉＣＮ層の形成条件を示すものであり、これ以外は通常の粒状結晶組織の形成条件を示すものである）に示される条件にて、表５に示される組み合わせおよび目標層厚でＴｉ化合物層を硬質被覆層の下部層として蒸着形成する。
ついで、表４に示される条件にて、下部層の表面にＡｌ2Ｏ３蒸着前処理を施し、
ついで、表３に示される条件にて、表５に示される組み合わせおよび目標層厚で、Ａｌ2 Ｏ3 層を上部層として蒸着形成する、
ことにより本発明被覆工具１〜１３をそれぞれ製造した。
Next, the part other than the cutting edge part is covered with hard urethane rubber or the like, and wet blasting is performed by spraying a polishing liquid containing 15 to 60% by mass of aluminum oxide fine particles in the ratio of the total amount with water only on the cutting edge part. And
Next, each of the tool bases A to F and the tool bases a to f was charged into a normal chemical vapor deposition apparatus. First, Table 3 (l-TiCN in Table 3 is disclosed in JP-A-6-8010). The combinations shown in Table 5 under the conditions shown in Table 5 are the conditions for forming the TiCN layer having the vertically grown crystal structure described, and the other conditions for forming the normal granular crystal structure. And the Ti compound layer is vapor-deposited as the lower layer of the hard coating layer with the target layer thickness.
Next, under the conditions shown in Table 4, the surface of the lower layer was subjected to pretreatment for deposition of Al 2 O 3 ,
Next, under the conditions shown in Table 3, the Al 2 O 3 layer is deposited as an upper layer with the combinations and target layer thicknesses shown in Table 5,
By this, this invention coated tool 1-13 was manufactured, respectively.
また、比較の目的で、工具基体の表面にウエットブラスト処理およびＡｌ2Ｏ３蒸着前処理を施さない以外は、本発明被覆工具１〜１３と全く同様にして、下部層（Ｔｉ化合物層）および上部層（Ａｌ2 Ｏ3 層）を蒸着形成することにより、表６に示される従来被覆工具１〜１３をそれぞれ製造した。 For the purpose of comparison, the lower layer (Ti compound layer) and the surface of the tool base are the same as in the present coated tools 1 to 13 except that the surface of the tool base is not subjected to wet blasting and pretreatment for deposition of Al 2 O 3. Conventional coating tools 1 to 13 shown in Table 6 were produced by vapor-depositing the upper layer (Al 2 O 3 layer), respectively.
次に、上記の本発明被覆工具１〜１３と従来被覆工具１〜１３の硬質被覆層の切れ刃部と逃げ面部において下部層と上部層との界面近傍１０箇所について、透過型電子顕微鏡（５００００倍）による暗視野観察による断面測定を行い、超硬基体表面に平行な直線距離を測定幅２５μｍとし、その範囲に存在するＡｌ2Ｏ３粒子と界面を有しているＴｉ化合物粒子の数ａおよびＴｉ化合物粒子と界面を有しているＡｌ2Ｏ３粒子の数ｂをカウントし、ｂ／ａの値を求めた。
表５および表６に、上記で求めたａ，ｂ，ｂ／ａの値を示す。なお、いずれの被覆工具も逃げ面部とすくい面部のａ，ｂ，ｂ／ａの値は、ほぼ同じ値であることが確認できたので、逃げ面部の値のみを示し、すくい面部の値については、表示を割愛した。
Next, a transmission electron microscope (50000) was formed at 10 points in the vicinity of the interface between the lower layer and the upper layer in the cutting edge portion and flank portion of the hard coating layer of the present invention coated tools 1-13 and the conventional coated tools 1-13. The number of Ti compound particles having an interface with Al 2 O 3 particles existing in the range of a linear distance parallel to the surface of the carbide substrate with a measurement width of 25 μm. The number b of Al 2 O 3 particles having an interface with the Ti compound particles was counted, and the value of b / a was determined.
Tables 5 and 6 show the values of a, b, and b / a determined above. In addition, since it was confirmed that the values of a, b, and b / a of the flank face and the rake face part were almost the same value in any of the coated tools, only the value of the flank face part is shown. I omitted the display.
図１には、本発明被覆工具１の切れ刃部における下部層と上部層との界面の透過型電子顕微鏡写真より作成した界面構造模式図を示す。
図２には、本発明被覆工具１の逃げ面部における下部層と上部層との界面の透過型電子顕微鏡写真より作成した界面構造模式図を示す。
図３には、従来被覆工具１の切れ刃部における下部層と上部層との界面の透過型電子顕微鏡写真より作成した界面構造模式図を示す。
図４には、従来被覆工具１の逃げ面部における下部層と上部層との界面の透過型電子顕微鏡写真より作成した界面構造模式図を示す。
In FIG. 1, the interface structure schematic diagram created from the transmission electron micrograph of the interface of the lower layer and upper layer in the cutting-blade part of this invention coated tool 1 is shown.
In FIG. 2, the interface structure schematic diagram created from the transmission electron micrograph of the interface of the lower layer and upper layer in the flank part of this invention coated tool 1 is shown.
In FIG. 3, the interface structure schematic diagram produced from the transmission electron micrograph of the interface of the lower layer and upper layer in the cutting-blade part of the conventional coated tool 1 is shown.
In FIG. 4, the interface structure schematic diagram created from the transmission electron micrograph of the interface of the lower layer and upper layer in the flank part of the conventional coated tool 1 is shown.
また、本発明被覆工具１〜１３および従来被覆工具１〜１３の硬質被覆層の下部層のＴｉ化合物について、透過型電子顕微鏡の断面観察により超硬基体表面と平行な方向に５０μｍに渡って線を引き、Ａｌ２Ｏ３層直下のＴｉ化合物層の結晶粒の結晶粒界との交点を数え、それら線分長さの平均から平均粒子径を求めた。
表５に、測定した平均粒子径を示す。
Moreover, about the Ti compound of the lower layer of the hard coating layer of this invention coated tool 1-13 and the conventional coated tool 1-13, it is a line over 50 micrometers in the direction parallel to the surface of a carbide substrate by cross-sectional observation of a transmission electron microscope. And the intersection of the crystal grains of the Ti compound layer immediately below the Al 2 O 3 layer with the crystal grain boundary was counted, and the average particle diameter was determined from the average of the line segment lengths.
Table 5 shows the measured average particle diameter.
さらに、本発明被覆工具１〜１３および従来被覆工具１〜１３の硬質被覆層の各構成層の厚さを、走査型電子顕微鏡を用いて測定（縦断面測定）したところ、いずれも目標層厚と実質的に同じ平均層厚（５点測定の平均値）を示した。 Furthermore, when the thicknesses of the constituent layers of the hard coating layers of the present coated tools 1 to 13 and the conventional coated tools 1 to 13 were measured using a scanning electron microscope (longitudinal cross section measurement), all of the target layer thicknesses were measured. The average layer thickness (average value of 5-point measurement) was substantially the same.
つぎに、上記の本発明被覆工具１〜１３および従来被覆工具１〜１３について、いずれも工具鋼製バイトの先端部に固定治具にてネジ止めした状態で、
[切削条件Ａ]
被削材：ＪＩＳ・ＳＮＣＭ４２０の長さ方向等間隔４本縦溝入の丸棒、
切削速度： ３６０ｍ／ｍｉｎ．、
切り込み： ０．９５ｍｍ、
送り： ０．４０ｍｍ／ｒｅｖ．、
切削時間： １５分、
の条件でのニッケルクロムモリブデン鋼の乾式高速断続切削試験（通常の切削速度は２００ｍ／ｍｉｎ．）、
[切削条件Ｂ]
被削材：ＪＩＳ・ＦＣＤ５００の長さ方向等間隔４本縦溝入の丸棒、
切削速度： ３４０ｍ／ｍｉｎ．、
切り込み： ０．９５ｍｍ、
送り： ０．５０ｍｍ／ｒｅｖ．、
切削時間： １５分、
の条件でのダクタイル鋳鉄の乾式高速断続切削試験（通常の切削速度は１８０ｍ／ｍｉｎ．）、
[切削条件Ｃ]
被削材：ＪＩＳ・Ｓ３０Ｃの長さ方向等間隔４本縦溝入の丸棒、
切削速度： ３８５ｍ／ｍｉｎ．、
切り込み： ０．９０ｍｍ、
送り： ０．８ｍｍ／ｒｅｖ．、
切削時間： １５分、
の条件での炭素鋼の乾式高速断続切削試験（通常の切削速度は２５０ｍ／ｍｉｎ．）
を行い、いずれの切削試験でも切刃の逃げ面摩耗幅を測定した。
この測定結果を表７に示した。
Next, for the present invention coated tools 1-13 and the conventional coated tools 1-13, both are screwed with a fixing jig to the tip of the tool steel tool,
[Cutting conditions A]
Work material: JIS / SNCM420 lengthwise equal 4 round grooves with vertical grooves,
Cutting speed: 360 m / min. ,
Cutting depth: 0.95mm,
Feed: 0.40 mm / rev. ,
Cutting time: 15 minutes,
Dry high-speed intermittent cutting test of nickel chrome molybdenum steel under the conditions (normal cutting speed is 200 m / min.),
[Cutting conditions B]
Work material: JIS / FCD500 lengthwise equal length 4 round bar with groove,
Cutting speed: 340 m / min. ,
Cutting depth: 0.95mm,
Feed: 0.50 mm / rev. ,
Cutting time: 15 minutes,
Dry high-speed intermittent cutting test (normal cutting speed is 180 m / min.) Of ductile cast iron under the conditions of
[Cutting conditions C]
Work material: JIS / S30C lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 385 m / min. ,
Cutting depth: 0.90mm,
Feed: 0.8 mm / rev. ,
Cutting time: 15 minutes,
Carbon steel dry high-speed intermittent cutting test under normal conditions (normal cutting speed is 250 m / min.)
In each cutting test, the flank wear width of the cutting edge was measured.
The measurement results are shown in Table 7.
表５〜７に示される結果から、本発明被覆工具１〜１３は、切れ刃部において、下部層と上部層との隣接界面に存在する下部層側のＴｉ化合物結晶粒の数ａ１と上部層側のＡｌ２Ｏ３結晶粒の数ｂ１との比率ｂ１／ａ１が０．８≦ｂ１／ａ１≦１．２を満足する界面構造を構成し、さらに、Ａｌ２Ｏ３層直下のＴｉ化合物層の結晶粒の平均粒子径を０．１μｍ以下としているとともに、逃げ面部およびすくい面部において、下部層と上部層との隣接界面に存在する下部層側のＴｉ化合物結晶粒の数ａ２と上部層側のＡｌ２Ｏ３結晶粒の数ｂ２との比率ｂ２／ａ２が４≦ｂ２／ａ２≦２０を満足する界面構造を構成し、さらに、Ａｌ２Ｏ３層直下のＴｉ化合物層の結晶粒の平均粒子径を０．１〜０．５μｍとしていることから、特に、下部層と上部層間の層間密着性が高められ、その結果、鋼および鋳鉄の高熱発生を伴い、切刃に高負荷が断続的に作用する高速断続切削加工に用いた場合でも、硬質被覆層がすぐれた層間密着強度を有するため、切刃に微小チッピング、剥離等の発生なく、長期の使用に亘ってすぐれた耐摩耗性を発揮することができる。
しかるに、硬質被覆層の下部層と上部層との間に本発明のような界面構造が形成されていない従来被覆工具１〜１３においては、高速断続切削条件下では、硬質被覆層の層間密着強度が不十分であるために、硬質被覆層に微小チッピング、欠損、剥離等が発生し、比較的短時間で使用寿命に至ることが明らかである。
From the results shown in Tables 5 to 7, according to the present invention coated tools 1 to 13, the number of Ti compound crystal grains on the lower layer side existing at the adjacent interface between the lower layer and the upper layer and the upper layer in the cutting edge portion A Ti compound layer immediately below the Al 2 O 3 layer, in which the ratio b1 / a1 to the number b1 of Al 2 O 3 crystal grains on the side satisfies 0.8 ≦ b1 / a1 ≦ 1.2 ; The average particle diameter of the crystal grains is 0.1 μm or less, and the number a2 of Ti compound crystal grains on the lower layer side existing on the adjacent interface between the lower layer and the upper layer and the upper layer side in the flank face and the rake face part The ratio b2 / a2 with the number b2 of Al 2 O 3 crystal grains of the above satisfies the relationship 4 ≦ b2 / a2 ≦ 20, and the average grain size of the Ti compound layer immediately below the Al 2 O 3 layer Since the particle diameter is 0.1 to 0.5 μm, Interlayer adhesion between the upper layer and the upper layer is improved, and as a result, even when used for high-speed intermittent cutting with high load acting on the cutting edge with high heat generation of steel and cast iron, the hard coating layer Since it has an excellent interlayer adhesion strength, it can exhibit excellent wear resistance over a long period of use without the occurrence of minute chipping, peeling, etc. on the cutting edge.
However, in the conventional coated tools 1 to 13 in which the interface structure as in the present invention is not formed between the lower layer and the upper layer of the hard coating layer, the interlayer adhesion strength of the hard coating layer under high-speed intermittent cutting conditions. Is insufficient, it is clear that micro-chipping, chipping, peeling, etc. occur in the hard coating layer and the service life is reached in a relatively short time.
上述のように、この発明の被覆工具は、鋼および鋳鉄の特に高い発熱を伴い切刃に対して高負荷が断続的に作用する高速断続切削加工においてすぐれた耐チッピング性、耐摩耗性を示し、長期の使用に亘ってすぐれた切削性能を発揮するものであるから、切削装置の高性能化並びに切削加工の省力化および省エネ化、さらに低コスト化が十分期待できるものである。 As described above, the coated tool of the present invention exhibits excellent chipping resistance and wear resistance in high-speed intermittent cutting with high load intermittently acting on the cutting blade with particularly high heat generation of steel and cast iron. Since it exhibits excellent cutting performance over a long period of use, high performance of the cutting device, labor saving and energy saving of the cutting work, and further cost reduction can be sufficiently expected.
Claims (1)
（ａ）切れ刃部においては、
下部層は、Ｔｉの炭化物層、窒化物層、炭窒化物層、炭酸化物層および炭窒酸化物層のうちの１層または２層以上からなり、かつ、３〜２０μｍの全体平均層厚を有するＴｉ化合物層からなり、
上部層は、化学蒸着した状態で１〜１５μｍの平均層厚を有するα型の結晶構造を有するＡｌ２Ｏ３層からなり、
上記下部層と上記上部層とが隣接する界面に存在する上記Ｔｉ化合物層側の結晶粒の数ａ１と上記Ａｌ２Ｏ３層側の結晶粒の数ｂ１との比率ｂ１／ａ１が０．８≦ｂ１／ａ１≦１．２を満足し、さらに、上記Ａｌ２Ｏ３層直下のＴｉ化合物層の結晶粒の平均粒子径が０．１μｍ以下であることを満足し、
（ｂ）逃げ面部およびすくい面部においては、
下部層は、Ｔｉの炭化物層、窒化物層、炭窒化物層、炭酸化物層および炭窒酸化物層のうちの１層または２層以上からなり、かつ、３〜２０μｍの全体平均層厚を有するＴｉ化合物層からなり、
上部層は、化学蒸着した状態で１〜１５μｍの平均層厚を有するα型の結晶構造を有するＡｌ２Ｏ３層からなり、
上記下部層と上記上部層とが隣接する界面に存在する上記Ｔｉ化合物層側の結晶粒の数ａ２と上記Ａｌ２Ｏ３層側の結晶粒の数ｂ２との比率ｂ２／ａ２が４≦ｂ２／ａ２≦２０を満足し、さらに、上記Ａｌ２Ｏ３層直下のＴｉ化合物層の結晶粒の平均粒子径が０．１〜０．５μｍであることを満足する、
以上（ａ）および（ｂ）から構成された硬質被覆層を蒸着形成してなることを特徴とする表面被覆切削工具。 In a surface-coated cutting tool in which a hard coating layer composed of a lower layer and an upper layer is vapor-deposited on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet, When divided into three areas consisting of flank and rake face,
(A) In the cutting edge part,
The lower layer is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer, and has an overall average layer thickness of 3 to 20 μm. A Ti compound layer having
The upper layer is composed of an Al 2 O 3 layer having an α-type crystal structure having an average layer thickness of 1 to 15 μm in the state of chemical vapor deposition,
Ratio b1 / a1 between the number b1 of the Ti compound layer side of the number a1 and the the Al 2 O 3 layer side of the crystal grains the crystal grains at the interface of the the lower layer and the upper layer is adjacent 0.8 ≦ b1 / a1 ≦ 1.2 is satisfied, and further, the average particle diameter of the crystal grains of the Ti compound layer immediately below the Al 2 O 3 layer is 0.1 μm or less,
(B) In the flank face and the rake face part,
The lower layer is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer, and has an overall average layer thickness of 3 to 20 μm. A Ti compound layer having
The upper layer is composed of an Al 2 O 3 layer having an α-type crystal structure having an average layer thickness of 1 to 15 μm in the state of chemical vapor deposition,
The number of the Ti compound layer side of the crystal grains at the interface of the the lower layer and the upper layer is adjacent a2 and the the Al 2 O 3 layer side of the ratio b2 / a2 is 4 ≦ the number b2 of grain b2 Satisfying / a2 ≦ 20 , and further satisfying that the average particle diameter of the crystal grains of the Ti compound layer immediately below the Al 2 O 3 layer is 0.1 to 0.5 μm.
A surface-coated cutting tool obtained by vapor-depositing a hard coating layer composed of (a) and (b) above.
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