JP2012152866A - Cutting tool made of surface-coated cubic boron nitride based ultra-high pressure sintered material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool which exhibits excellent wear resistance, chipping resistance, and fusion resistance in high-speed continuous cutting and intermittent cutting of a cut material where a ferrite-phase such as ductile cast iron is greatly deposited.SOLUTION: A lower layer comprised of amorphous BN with an average layer thickness of 0.1-0.3 μm, an intermediate layer comprised of TiBN with an average layer thickness of 0.1-0.3 μm, and an upper layer comprised of TiAlN with an average layer thickness of 1.0-2.0 μm are sequentially vapor-deposited on the surface of a tool base made of a cBN based ultra-high pressure sintered material, and the upper layers of a rake face and a honing face are removed.

Description

  In the present invention, pearlite and ferrite phases are precipitated in cast iron and sintered alloys, and even when ductile cast iron and sintered alloys in which a large amount of ferrite phases are precipitated are hard-coated even when high-speed continuous cutting and intermittent cutting are performed. The layer is composed of cubic boron nitride (hereinafter referred to as cBN) -based ultra-high pressure sintered material that exhibits excellent lubricity and welding resistance, and can exhibit stable cutting performance over a long period of time. A surface-coated cutting tool made of a surface-coated cubic boron nitride-based ultra-high pressure sintered material with a hard coating layer formed on the surface of the cutting tool substrate (hereinafter referred to as a tool substrate) (hereinafter referred to as a coated cBN-based sintered tool) )).

  2. Description of the Related Art Conventionally, it is well known to use a cBN-based ultra-high pressure sintered material as a tool material having low affinity with a work material for cutting of an iron-based work material such as steel or cast iron.

Further, as shown in Patent Document 1, a cBN-based ultrahigh pressure sintered material is used as a tool base (hereinafter referred to as a cBN tool base), and nitrides of elements selected from Group 4a, 5a, and 6a elements and Al are formed on the surface thereof. (For example, a wear-resistant film made of TiAlN) is formed, and the wear-resistant film is made of BN, TiB, SiN _x (X = 0.5 to 1.33) having an amorphous structure, or the like. A cBN coated tool containing ultrafine compounds (hereinafter referred to as a conventional coated tool) is also known, and according to this conventional coated tool, wear resistance, lubricity, seizure resistance, and machining accuracy in machining are improved. However, it is known that the tool life will be improved.

  By the way, in the cBN coated tool, in general, in order to improve the fracture resistance, attempts have been made to increase the cBN content ratio in the cBN sintered body, but the cBN content ratio is, for example, about 70 vol% or more. In the case of increasing the thickness, the adhesion strength between the hard coating layer (for example, the wear-resistant coating made of TiAlN in the conventional coated tool) and the tool base tends to decrease, so that the severer the cutting condition, At present, chipping, chipping, peeling, welding, etc. are likely to occur and the tool life is not improved sufficiently.

Japanese Patent No. 3914687

  In recent years, FA has been remarkable for cutting devices, but on the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and accordingly, cutting is performed at higher speed conditions in addition to normal cutting conditions. However, in the conventional coated tool, there is no particular problem when various types of steel and cast iron are machined under normal conditions. When used for high-speed continuous cutting and interrupted cutting of work materials with a large amount of ferrite phase, such as steel and sintered alloys, high heat is generated during cutting, and the adhesion strength of the hard coating layer decreases due to high loads. Alternatively, due to the occurrence of welding or the like, the service life is reached in a relatively short period of time.

In view of the above, the present inventors, from the above-mentioned viewpoint, have excellent adhesion of the hard coating layer in high-speed continuous cutting and intermittent cutting of a work material in which a large amount of ferrite phase such as ductile cast iron and sintered alloy is precipitated. As a result of research to develop a coated cBN-based sintered tool that has strength, exhibits excellent lubricity and welding resistance, and exhibits excellent cutting performance over a long period of use. The following knowledge was obtained.
(A) A BN layer (hereinafter referred to as aBN) having an amorphous structure is formed as a lower layer on the surface of a cBN tool base made of a cBN-based ultrahigh pressure sintered material having a high content of cBN (70 vol% or more). Then, a composite compound of Ti, B, and N (hereinafter referred to as TiBN) is formed thereon as an intermediate layer, and further, a composite nitride of Ti and Al (hereinafter referred to as TiAlN) is further formed thereon. Was formed as an upper layer, the lower layer was found to have strong adhesion strength to both the cBN tool substrate and the intermediate layer, and the intermediate layer had excellent adhesion strength to the upper layer.

Therefore, the cBN coated tool in which the hard coating layer having the three-layer structure of the lower layer, the intermediate layer, and the upper layer is formed on the surface of the cBN tool base has excellent adhesion strength, and as a result, the ductile cast iron and In high-speed continuous cutting and intermittent cutting of work materials with a large amount of ferrite phase, such as sintered alloys, excellent resistance to long-term use without causing abnormal damage such as chipping, chipping and peeling. It has been found that the wear life can be demonstrated and the tool life can be extended.
(B) The TiAlN layer is excellent in wear resistance, but is inferior in welding resistance. For this reason, coating the flank surface leads to improved wear resistance, but welding occurs on the rake surface and honing surface that come into contact with the chips, resulting in large film peeling and wear, leading to chipping and chipping. Therefore, by exposing the TiBN layer with excellent welding resistance on the rake face and honing surface, welding hardly occurs, crater wear resistance is improved, and the flank face has a TiAlN layer with excellent wear resistance. By leaving as an upper layer, it exhibits excellent wear resistance and fracture resistance over a long period of use, and exhibits stable cutting performance. In other words, by removing the TiAlN layer, which is the upper layer of the rake face and honing face, and exposing the TiBN layer of the intermediate layer, the excellent lubricity and welding resistance of the TiBN layer are exhibited, and ductile cast iron and heat bonding Even when high-speed continuous cutting and intermittent cutting of work materials with a large amount of ferrite such as gold are deposited, welding is less likely to occur, crater wear resistance is improved, and excellent resistance to long-term use. It exhibits wear and fracture resistance and exhibits stable cutting performance.

The present invention has been made based on the above findings,
“(1) A cutting edge portion formed by honing a cross ridge line portion between a rake face and a flank face of a tool body having a cubic boron nitride-based ultrahigh pressure sintered material as a base material, and the tool In the surface-coated cubic boron nitride-based ultra-high pressure sintered material cutting tool in which a hard coating layer consisting of a lower layer, an intermediate layer and an upper layer is deposited in this order from the tool body side on the surface of the main body,
(A) the lower layer is an amorphous BN layer having an average layer thickness of 0.1 to 0.3 μm;
(B) The intermediate layer is a composite compound layer of Ti, B and N having an average layer thickness of 0.1 to 0.3 μm,
(C) The upper layer is a composite nitride layer of Ti and Al having an average layer thickness of 1.0 to 2.0 μm,
(D) The rake face and the honing face of the tool base are made of a surface-coated cubic boron nitride-based ultra-high pressure sintered material, wherein the intermediate layer is mainly exposed by removing the upper layer. Cutting tools.
(2) The intermediate layer is
Composition formula: Ti _{0.33 (1-X)} B _{0.67 (1-X)} N _X
Is a composite compound layer of Ti, B, and N having a composition ratio that satisfies the value of X (however, the atomic ratio) is 0.05 to 0.5,
The upper layer is
Composition formula: (Ti _1-Y Al _Y ) When represented by an N layer, a composite nitride layer of Ti and Al having a composition ratio in which the value of Y (however, the atomic ratio) satisfies 0.4 to 0.65. The cutting tool made of a surface-coated cubic boron nitride-based ultrahigh pressure sintered material according to (1).
(3) The surface-coated cubic nitriding according to (1) or (2), wherein the cubic boron nitride content of the cubic boron nitride-based ultrahigh pressure sintered material is 70% by volume or more. Cutting tool made of boron-based ultra-high pressure sintered material. "
It is characterized by.

  The present invention will be described below.

Cubic boron nitride based ultra-high pressure sintered material tool substrate (cBN tool substrate):
Boron nitride (cBN) in a tool base made of an ultra-high pressure sintered material is extremely hard and forms a dispersed phase in the sintered material, and this dispersed phase can improve wear resistance.

  In general, when the cBN content is 70 vol% or more, the hardness is improved, but the adhesion with the hard coating layer is reduced and the generation of defects is caused. Quality BN layer (aBN layer)) and intermediate layer (TiBN layer) are interposed, so that sufficient adhesion strength between the cBN tool substrate and the upper layer (TiAlN layer) can be secured. A cBN tool base having a high content of 70 vol% or more can be used as a cutting tool.

  In the present invention, from the viewpoint of providing a surface-coated cutting tool having excellent wear resistance and fracture resistance over a long period of use, the cBN content is preferably 70 vol% or more.

The other constituents of the cBN sintered body, for example, the binder phase, are selected from the group consisting of nitrides, carbides, borides, oxides of these periodic table VIa, Va, and VIa group elements, and solid solutions thereof. A ceramic binder of at least one selected type and an aluminum compound can be used.
Lower layer (amorphous BN layer (aBN layer)):
The lower layer has strong adhesion strength to both the cBN tool substrate and the intermediate layer (TiBN layer), but if the average layer thickness of the lower layer is less than 0.1 μm, the effect of improving adhesion strength is not sufficient, This is because the wear resistance is poor when the average layer thickness exceeds 0.3 μm, so the average layer thickness was determined to be 0.1 to 0.3 μm.

The lower aBN layer can be formed by RF sputtering in an argon-nitrogen mixed atmosphere with a hexagonal boron nitride (h-BN) sintered body as a target, for example.
Intermediate layer (TiBN layer):
The intermediate layer is composed of a composite compound layer of Ti, B and N. If the average layer thickness of the intermediate layer is less than 0.1 μm, the effect of improving the adhesion strength is not sufficient, while the average layer thickness is 0.3 μm. If it exceeds 1, the wear resistance tends to decrease, and satisfactory tool characteristics cannot be exhibited over a long period of use. Therefore, the average layer thickness was determined to be 0.1 to 0.3 μm.

This intermediate layer is mainly composed of a mixed layer of TiN + aBN + TiB ₂ (trace amount) when the N concentration is high, but since the content ratio of aBN and TiN is high, the lower layer (aBN layer) and the upper layer (TiAlN layer) Both have strong adhesion strength.

In particular, the intermediate layer (TiBN layer)
Composition formula: Ti _{0.33 (1-X)} B _{0.67 (1-X)} N _X
When the value of X (however, the atomic ratio) is a composition ratio that satisfies 0.05 to 0.5, the adhesion strength is further improved with respect to the lower layer and the upper layer.

The intermediate TiBN layer can be formed by DC sputtering, for example, in an argon-nitrogen mixed atmosphere with a TiB ₂ sintered body as a target.
Upper layer (TiAlN layer):
The upper layer composed of the TiAlN layer is a layer having excellent high temperature strength, high temperature hardness, heat resistance and high temperature oxidation resistance.
Composition formula: (Ti _1-Y Al _Y ) When expressed by an N layer, the most preferable characteristics are exhibited when the Y value (however, the atomic ratio) is a composition ratio satisfying 0.4 to 0.65. To do.

  That is, Ti, which is a constituent component of the upper layer, contributes to maintaining a predetermined high-temperature strength, and the Al component contributes to improvement in high-temperature hardness, heat resistance, and high-temperature oxidation resistance, but the Al content ratio Y is 0.1. If it exceeds 65, the high-temperature oxidation resistance is improved, but the wear resistance is lowered due to the relative decrease in the Ti content. On the other hand, if the Al content Y is less than 0.4, the high-temperature hardness and heat resistance are reduced. As a result, a decrease in wear resistance is observed, so the value of the Al content ratio Y is preferably set to 0.4 to 0.65.

  On the other hand, if the average thickness of the upper layer is less than 1.0 μm, the high temperature hardness, heat resistance and high temperature oxidation resistance possessed by itself cannot be imparted to the hard coating layer over a long period of time, resulting in a short tool life. When the average layer thickness exceeds 2.0 μm, defects tend to occur, so the average layer thickness was set to 1.0 to 2.0 μm.

  The upper layer made of the TiAlN layer can be formed by a commonly used arc ion plating (AIP) method.

  In addition, the TiAlN layer that constitutes the upper layer is easily welded when cutting a work material with a large amount of ferrite phase, such as ductile cast iron or sintered alloy, so the rake face and the upper part of the honing face are wet. The TiBN layer having excellent lubricity and welding resistance is exposed by removing by blasting.

  As described above, in the coated cBN-based sintered tool of the present invention, the cBN mixing ratio of cBN is preferably 70 vol% or more. Between the layers, an aBN layer is formed as a lower layer, and a TiBN layer is formed as an intermediate layer, and the upper layer of the rake face and the honing surface is removed to expose the intermediate layer, thereby providing particularly excellent adhesion strength. In addition, because it combines high-temperature hardness, toughness, impact resistance, lubricity, and welding resistance, it is accompanied by high heat generation in the work material in which ferrite phases such as ductile cast iron and sintered alloy are precipitated, and Even under high-speed continuous cutting and intermittent cutting conditions in which a high load acts on the cutting edge, the hard coating layer does not cause peeling or welding, and can be used over a long period of use. The abrasion resistance can be exhibited chipping resistance.

Vapor deposition apparatus provided with an arc ion plating (AIP) apparatus, an RF magnetron sputtering (RF-SP) apparatus, and a DC sputtering (DC-SP) apparatus used to form a hard coating layer constituting the coated tool of the present invention (A) is a schematic plan view, (b) is a schematic front view. Sectional drawing of the front-end | tip part of the covering cBN group sintered tool of this invention is shown.

  The coated cBN-based sintered tool of the present invention will be described below based on examples.

As the raw material powder, cBN powder, TiN powder, AlN powder, TiC powder, TiCN powder, Ti ₃ Al powder, Ti ₂ Al powder, TiAl ₃ powder, Al having an average particle diameter in the range of 0.5 to 4 μm. Powder, Al ₂ O ₃ powder, Co powder, WC powder are prepared, these raw material powders are blended in the blending composition shown in Table 1, wet-mixed by a ball mill for 80 hours, dried, and then subjected to a diameter of 120 MPa at a pressure of 120 MPa. 50 mm × thickness: pressed into a green compact with a dimension of 1.5 mm, and then this green compact is held at a predetermined temperature in the range of 900 to 1300 ° C. for 60 minutes in a vacuum atmosphere at a pressure of 1 Pa. The pre-sintered body for cutting edge pieces was sintered under the conditions described above, and this pre-sintered body was prepared separately, Co: 8% by mass, WC: remaining composition, and diameter: 50 mm × thickness: 2 mm W with dimensions In a state of being superposed on the base cemented carbide support piece, the sample was inserted into a normal ultra-high pressure sintering apparatus, and maintained at a predetermined temperature within a range of pressure: 4 GPa, temperature: 1200 to 1400 ° C., which are normal conditions. : Sintered under high pressure for 0.8 hours, and after sintering, the upper and lower surfaces were polished with a diamond grindstone, and divided into equilateral triangles with a side of 3 mm using a wire electric discharge machine or diamond cutting machine. : WC based cemented carbide insert having 5 mass%, TaC: 5 mass%, WC: remaining composition and shape of CIS standard TNGA160408 (thickness: 4.76 mm × one side length: 12.7 mm square) The brazing part (corner part) of the main body is brazed using a brazing material of an Ag alloy having a composition of Cu: 26%, Ti: 5%, Ni: 2.5%, and Ag: the remainder. Perimeter processing After that, the cutting edge portion is subjected to honing processing with a width of 0.13 mm and an angle of 25 °, and further subjected to finish polishing, thereby having an ISO standard TNGA160408 insert shape and a cBN content ratio of 70 vol% or more. The cBN tool bases A to F shown in FIG.

ついで、図１に示される成膜装置、即ち、ＴｉＢ_２焼結体ターゲットおよびｈ−ＢＮ焼結体ターゲットを備えたスパッタリング装置と、Ｔｉ−Ａｌ合金ターゲットを備えたアークイオンプレーティング装置を併設した成膜装置の内部にｃＢＮ工具基体を装着し、
前記ｃＢＮ工具基体を、アセトン中で超音波洗浄し、乾燥した状態で、前記装置内に自転公転自在に支持装着し、
（ａ）まず、装置内を真空排気して０．５Ｐａの真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、Ａｒガスを導入し、１．５ＰａのＡｒガス雰囲気とし、ｃＢＮ工具基体１に−１００Ｖの直流バイアス電圧を印加して、前記ｃＢＮ工具基体をＡｒガスボンバード洗浄し、
（ｂ）ついで、前記装置内に、ＡｒとＮ_２との混合ガス（Ａｒ／Ｎ_２＝５０％）を導入し、作動圧を３．３Ｐａになるように制御し、前記回転テーブル上で自転しながら回転するｃＢＮ工具基体側に−２０Ｖの直流バイアス電圧を印加し、ｈ−ＢＮ焼結体ターゲット側に５００Ｗの１３．５６ＭＨｚの周波数の高周波を印加することにより、ｃＢＮ工具基体の上に表２に示される目標膜厚のａＢＮ層（下部層）を形成し、
（ｃ）ついで、前記装置内をＡｒとＮ_２との混合ガス（Ａｒ／Ｎ_２＝５０％）雰囲気に維持し、かつ、作動圧を３．３Ｐａ，５００℃に維持したまま、前記回転テーブル上で自転しながら回転するｃＢＮ工具基体に−１００Ｖの直流バイアス電圧を印加して、ＴｉＢ_２焼結体のターゲットに直流電源を用いてスパッタを行うことにより、前記ａＢＮ層（下部層）の表面に表２に示される目標層厚、所定組成のＴｉＢＮ層からなる中間層（ＴｉＢＮ層）を形成し、
（ｄ）ついで、装置内を５００℃とした状態で、ｃＢＮ工具基体に−１５〜−２５Ｖの直流バイアス電圧を印加して、Ｔｉ−Ａｌ合金カソード電極とアノード電極との間に１２０Ａの電流を流してアーク放電を発生させ、前記中間層（ＴｉＢＮ層）の表面に表３に示される目標層厚、所定組成のＴｉＡｌＮ層からなる上部層を形成することにより、
ＩＳＯ規格ＴＮＧＡ１６０４０８に規定するスローアウエイチップ形状の本発明被覆ｃＢＮ基焼結工具１〜６を作製した。
（ｅ）さらに、図２の断面図に示すように、スローアウエイチップ形状の本発明被覆ｃＢＮ基焼結工具のすくい面とホーニング面の上部層をウエットブラスト処理により、中間層を露出させる。ウエットブラスト処理は、噴射研磨材を含有した液体（一般には水）である研磨液を被処理物に噴射して研磨を行なうものであり、弾性砥石やブラシを用いた機械加工はもとより、乾式のブラスト処理と比べても、液体が被処理物との間で噴射研磨材の運動エネルギーを減衰させるため、加工エネルギーの比較的弱いソフトな加工となる。このため、本発明のような最外層の除去に用いることにより、露出されられた中間層表面への研磨傷の発生も少なく抑えることができ、例えば、算術平均粗さＲａで０．１μｍ以下の表面粗さの平滑なすくい面およびホーニング面を形成することができる。

Next, the film forming apparatus shown in FIG. 1, that is, a sputtering apparatus provided with a TiB ₂ sintered body target and an h-BN sintered body target, and an arc ion plating apparatus provided with a Ti—Al alloy target were provided. A cBN tool base is mounted inside the film forming apparatus,
The cBN tool base is ultrasonically cleaned in acetone and dried and supported and mounted in the apparatus so as to rotate and revolve.
(A) First, the inside of the apparatus is heated to 500 ° C. with a heater while the inside of the apparatus is evacuated and kept at a vacuum of 0.5 Pa, and then Ar gas is introduced to form an Ar gas atmosphere of 1.5 Pa. A DC bias voltage of −100 V is applied to the tool base 1, and the cBN tool base is cleaned with Ar gas bombardment.
(B) Next, a mixed gas of Ar and N ₂ (Ar / N ₂ = 50%) is introduced into the apparatus, the operating pressure is controlled to 3.3 Pa, and the rotation on the rotary table is performed. While applying a DC bias voltage of −20 V to the rotating cBN tool base side and applying a high frequency of 13.56 MHz of 500 W to the h-BN sintered body target side, ABN layer (lower layer) having a target film thickness shown in FIG.
(C) Next, the rotary table is maintained while maintaining the inside of the apparatus in a mixed gas atmosphere of Ar and N ₂ (Ar / N ₂ = 50%) and maintaining the operating pressure at 3.3 Pa and 500 ° C. The surface of the aBN layer (lower layer) is formed by applying a DC bias voltage of −100 V to the cBN tool substrate rotating while rotating on the surface and performing sputtering using a DC power source on the target of the TiB ₂ sintered body. An intermediate layer (TiBN layer) composed of a TiBN layer having a target layer thickness and a predetermined composition shown in Table 2 is formed.
(D) Next, with the inside of the apparatus at 500 ° C., a DC bias voltage of −15 to −25 V is applied to the cBN tool base, and a current of 120 A is applied between the Ti—Al alloy cathode electrode and the anode electrode. By causing an arc discharge to flow, and forming an upper layer composed of a TiAlN layer having a predetermined composition and a target layer thickness shown in Table 3 on the surface of the intermediate layer (TiBN layer),
The present invention coated cBN-based sintered tools 1 to 6 having a throwaway tip shape defined in ISO standard TNGA160408 were produced.
(E) Further, as shown in the cross-sectional view of FIG. 2, the intermediate layer is exposed by wet blasting of the rake face and the upper layer of the honing face of the present invention coated cBN-based sintered tool having a throwaway tip shape. The wet blast treatment is performed by injecting a polishing liquid, which is a liquid (generally water) containing an abrasive material, onto a workpiece, and is a dry process as well as machining using an elastic grindstone or brush. Even when compared with the blasting process, the liquid attenuates the kinetic energy of the jetting abrasive between the object and the object to be processed, so that soft processing with relatively weak processing energy is achieved. For this reason, by using it for the removal of the outermost layer as in the present invention, it is possible to reduce the occurrence of polishing scratches on the exposed intermediate layer surface. For example, the arithmetic average roughness Ra is 0.1 μm or less. A rake surface and a honing surface having a smooth surface roughness can be formed.

  The thickness of the intermediate layer after removal of the outermost layer is 0.15 to 0.25 μm.

  For comparison, a hard coating layer is formed on the cBN tool bases 1 to 6 used in the examples by the same method as described above, and the step (e) is not performed. That is, the rake face and the honing face are not formed. Without removing the upper layer, comparative coated cBN-based sintered tools 1 to 6 were produced in which a hard coating layer having the target composition and thickness shown in Table 2 was formed by vapor deposition.

  For the inventive coated cBN-based sintered tools 1-6 and comparative coated cBN-based sintered tools 1-6, the film composition of the lower layer (aBN layer), the intermediate layer (TiBN layer) and the upper layer (TiAlN layer) When measured by Auger electron spectroscopy, each showed substantially the same composition as the target composition.

  The X value of the intermediate layer and the X value of the upper layer in Table 2 indicate the average value of the composition of each layer (average value of five locations).

  Further, when the layer thicknesses of the respective layers of the present coated cBN-based sintered tools 1 to 6 and the comparative coated cBN-based sintered tools 1 to 6 were measured using a transmission electron microscope, both were substantially equal to the target layer thickness. The same average value (average value of 5 locations) was shown.

  These measured values are shown in Table 2.

前記本発明被覆ｃＢＮ基焼結工具１〜６および比較被覆ｃＢＮ基焼結工具１〜６を用い、以下の切削条件で切削加工試験を実施した。
《切削条件１》
被削材：ＦＣＤ７００、
切削速度： ３５０ ｍ／ｍｉｎ、
送り： ０．２ ｍｍ／ｒｅｖ、
切込み： ０．１５ ｍｍ、
切削時間： １５ 分
の条件でのダクタイル鋳鉄の乾式・高速連続切削加工試験。逃げ面摩耗量が０．５ｍｍに達するまでの切削時間を工具の寿命とする。（通常の切削条件は、切削速度：２５０ｍ／ｍｉｎ、切り込み：０．２ｍｍ、送り：０．１５ｍｍ／ｒｅｖ）、
《切削条件２》
被削材： ０．５Ｃ−１．５Ｃｕ−４Ｎｉ−０．５Ｍｏ−残Ｆｅ
切削速度： １９０ ｍ／ｍｉｎ、
送り： ０．１５ ｍｍ／ｒｅｖ、
切込み： ０．２ ｍｍ、
切削時間： １５ 分
の条件での焼結合金の湿式・断続切削加工試験。刃先が欠損するまでの切削時間を工具寿命とする。（通常の切削条件は、切削速度：１５０ｍｍ／ｍｉｎ、切り込み：０．１ｍｍ、送り：０．１５ｍｍ／ｒｅｖ）。

Using the coated cBN-based sintered tools 1 to 6 and comparative coated cBN-based sintered tools 1 to 6 of the present invention, a cutting test was performed under the following cutting conditions.
<< Cutting conditions 1 >>
Work material: FCD700,
Cutting speed: 350 m / min,
Feed: 0.2 mm / rev,
Cutting depth: 0.15 mm,
Cutting time: Dry and high-speed continuous cutting test of ductile cast iron under the condition of 15 minutes. The cutting time until the flank wear amount reaches 0.5 mm is defined as the tool life. (Normal cutting conditions are cutting speed: 250 m / min, cutting: 0.2 mm, feed: 0.15 mm / rev),
<< Cutting conditions 2 >>
Work Material: 0.5C-1.5Cu-4Ni-0.5Mo-Remaining Fe
Cutting speed: 190 m / min,
Feed: 0.15 mm / rev,
Cutting depth: 0.2 mm,
Cutting time: Wet / intermittent cutting test of sintered alloy under the condition of 15 minutes. The cutting time until the cutting edge is broken is defined as the tool life. (Normal cutting conditions are cutting speed: 150 mm / min, cutting: 0.1 mm, feeding: 0.15 mm / rev).

  Table 3 shows the measurement results of the cutting test under the above cutting conditions 1 and 2.

表２および表３に示される結果から、本発明被覆ｃＢＮ基焼結工具１〜６は、７０ｖｏｌ％以上のｃＢＮを含有するｃＢＮ工具基体表面に、ａＢＮ層からなる下部層、ＴｉＢＮ層からなる中間層を介して、ＴｉＡｌＮ層からなる上部層を形成するとともに、すくい面およびホーニング面の上部層を除去したことによって、ｃＢＮ含有割合の高い工具基体に対しても、硬質被覆層は特にすぐれた付着強度を備え、さらに、高温硬さ、靭性、耐衝撃性、潤滑性、耐溶着性を兼ね備えることから、ダクタイル鋳鉄や焼結合金などのフェライト相が多く析出した被削材の、高熱発生を伴い、かつ、切刃に対して高負荷が作用する高速連続切削および断続切削条件下で用いた場合であっても、前記硬質被覆層に、欠損、剥離、溶着等の発生はなく、長期の使用に亘って、すぐれた耐摩耗性、耐欠損性を発揮することができる。

From the results shown in Table 2 and Table 3, the coated cBN-based sintered tools 1 to 6 of the present invention have a lower layer composed of an aBN layer and an intermediate layer composed of a TiBN layer on the surface of a cBN tool substrate containing 70 vol% or more of cBN. By forming the upper layer composed of the TiAlN layer through the layer and removing the upper layer of the rake face and the honing face, the hard coating layer has a particularly excellent adhesion even to a tool substrate having a high cBN content ratio. In addition to high strength, high-temperature hardness, toughness, impact resistance, lubricity, and welding resistance, it is accompanied by high heat generation in work materials with many ferrite phases precipitated, such as ductile cast iron and sintered alloys. In addition, even when used under high-speed continuous cutting and intermittent cutting conditions in which a high load acts on the cutting edge, the hard coating layer is free from defects, peeling, welding, etc. Over the use, excellent wear resistance can be exhibited chipping resistance.

  On the other hand, in the comparative coated cBN-based sintered tools 1 to 6 that do not remove the upper layer of the rake face and the honing face, the lubricity and welding resistance are not sufficient, so the work material and the TiAlN layer Therefore, chipping is likely to occur due to peeling of the coating film, and lubricity is poor between the work material and the TiAlN layer, so crater wear is likely to occur, and wear resistance, It is apparent that the service life is reached in a relatively short time due to the poor fracture resistance.

  As described above, the coated cBN-based sintered tool of the present invention has a large amount of ferrite phase such as ductile cast iron and sintered alloy, as well as cutting under normal cutting conditions such as various steels and cast iron. Even in high-speed continuous cutting and intermittent cutting of work materials, the hard coating layer has excellent adhesion strength, lubricity, and excellent wear resistance, fracture resistance, and welding resistance. Since it exhibits stable cutting performance over time, it can sufficiently satisfactorily cope with higher performance of the cutting device, labor saving and energy saving of cutting, and cost reduction.

Claims (3)

A cutting edge portion is formed on the surface of the tool body with honing at the intersection ridge line portion of the rake face and flank face of the tool body using a cubic boron nitride-based ultrahigh pressure sintered material as a base material. In the cutting tool made of surface-coated cubic boron nitride-based ultra-high pressure sintered material in which a hard coating layer consisting of a lower layer, an intermediate layer and an upper layer is vapor-deposited in order from the tool body side,
(A) the lower layer is an amorphous BN layer having an average layer thickness of 0.1 to 0.3 μm;
(B) The intermediate layer is a composite compound layer of Ti, B and N having an average layer thickness of 0.1 to 0.3 μm,
(C) The upper layer is a composite nitride layer of Ti and Al having an average layer thickness of 1.0 to 2.0 μm,
(D) The rake face and the honing face of the tool base are made of a surface-coated cubic boron nitride-based ultra-high pressure sintered material, wherein the intermediate layer is mainly exposed by removing the upper layer. Cutting tools. The intermediate layer is
Composition formula: Ti _{0.33 (1-X)} B _{0.67 (1-X)} N _X
Is a composite compound layer of Ti, B, and N having a composition ratio that satisfies the value of X (however, the atomic ratio) is 0.05 to 0.5,
The upper layer is
Composition formula: (Ti _1-Y Al _Y ) When represented by an N layer, a composite nitride layer of Ti and Al having a composition ratio in which the value of Y (however, the atomic ratio) satisfies 0.4 to 0.65. The surface-coated cubic boron nitride-based ultrahigh pressure sintered material cutting tool according to claim 1.   3. The surface-coated cubic boron nitride group according to claim 1, wherein the cubic boron nitride content of the ultrahigh pressure sintered material of the cubic boron nitride is 70% by volume or more. Cutting tool made of ultra high pressure sintered material.

Images