JP4807575B2 - Cutting tool made of surface-coated cubic boron nitride-based ultra-high pressure sintered material that exhibits excellent wear resistance in high-speed cutting of hardened steel - Google Patents

Description

  The present invention has high-temperature hardness, high-temperature strength, and lubricity with an excellent hard coating layer, and is therefore used for high-speed cutting of high-hardness steel such as hardened alloy tool steel and bearing steel with high heat generation. In some cases, a surface-coated cubic boron nitride-based ultra-high pressure with a hard coating layer formed on the surface of a cutting tool base made of cubic boron nitride-based ultra-high pressure sintered material that exhibits excellent wear resistance The present invention relates to a cutting tool made of a sintered material (hereinafter referred to as a coated cBN-based sintered tool).

  In general, a coated cBN-based sintered tool can be attached to a throwaway tip that is detachably attached to the tip of a cutting tool for turning various work materials such as steel and cast iron, and the throwaway tip can be detachably attached. There are known slow-away end mills that are attached and cut in the same manner as solid type end mills used for chamfering, grooving, and shoulder machining.

  In addition, as the coated cBN-based sintered tool, titanium nitride (TiN) is formed on the surface of a tool body made of various cubic boron nitride-based ultrahigh pressure sintered materials (hereinafter referred to as cBN-based sintered materials). A coated cBN-based firing layer formed by vapor deposition of a surface coating layer such as a composite nitride layer of Ti, Si and B (boron), a composite nitride layer of Ti and Al, and a composite nitride layer of Cr and Si It is also known that knotting tools are known, and these are used for cutting various steels and cast irons, for example.

Further, the above-mentioned coated cBN-based sintered tool is loaded with the above-mentioned tool base in an arc ion plating apparatus which is one type of physical vapor deposition apparatus schematically shown in FIG. For example, in a state heated to 500 ° C., a cathode electrode (evaporation source) made of metal Ti, Ti—Al alloy, Ti—Si—B alloy, Cr—Si alloy having a predetermined composition, and an anode electrode, During this time, for example, a current of 90 A is applied to generate arc discharge, and at the same time, nitrogen gas is introduced into the apparatus as a reaction gas to obtain a reaction atmosphere of, for example, 2 Pa, while the tool base has, for example, −100 V A desired component such as a TiN layer, a (Ti, Al) N layer, a (Ti, Si, B) N layer, or a (Cr, Si) N layer is formed on the surface of the tool base under a condition where a bias voltage is applied. It is also known that are prepared by depositing a layer of growth.
JP-A-7-300649 JP-A-8-119774 JP 2003-340603 A JP 2003-340605 A

  In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting work. In the conventional coated cBN-based sintered tool, there is no particular problem when this is used for normal cutting of various carbon steels, low alloy steels, and cast iron. However, when this is used for cutting of high hardness steel having a hardness of 50 or higher, such as hardened material of alloy tool steel or bearing steel, particularly with high heat generation. When used under high-speed cutting conditions, due to insufficient high-temperature strength and high-temperature hardness of the hard coating layer, uneven wear that causes accelerated wear on the cutting edge or chipping on the cutting edge ( As a result, the service life is reached in a relatively short time.

In view of the above, the inventors of the present invention have a coated cBN base that exhibits excellent wear resistance with a hard coating layer in high-speed cutting of high-hardness steel such as hardened steel of alloy tool steel and bearing steel. As a result of research to develop a sintered tool,
(a) composite nitride of Cr and Si constituting the hard layer _{([Cr 1-X Si X} ] N) layer, the value of the content X (atomic ratio) of Si, 0.01 to 0.1 High-hardness steel with high-temperature heat, while having a predetermined high-temperature strength, excellent lubricity and high-temperature hardness within the range of, and having the wear resistance required under normal cutting conditions In a high-speed cutting process, a hard coating layer composed of a composite nitride [Cr _1-X Si _X ] N (X is 0.01 to 0.1 atomic ratio) of Cr and Si has insufficient high-temperature strength. Therefore, uneven wear and chipping are likely to occur.

(B) On the other hand, the composition _formula: a _{[Ti 1-Y Si Y]} N (Y in atomic ratio from 0.01 to 0.1) composite nitride layer excellent high-temperature hardness of Ti and Si represented by a further composite nitride of Cr and _{Si [Cr 1-X Si X} ] N (X is from 0.01 to 0.1 in atomic ratio), but is superior to the more high-temperature strength as compared with the layer, the Since the lubricity is not sufficient, in high-speed cutting of high-hardness steel with high heat generation, the hard coating layer is made of Ti and Si composite nitride [Ti _1-Y Si _Y ] N (Y is an atom Even if it is composed of only 0.01 to 0.1) layer, it cannot be said that it has sufficient wear resistance.

(C) [Cr _1-X Si _X ] N (where X is an atomic ratio) having a predetermined high-temperature strength in which the Si content in (a) is 1 to 10 atomic%, excellent high-temperature hardness, and excellent lubricity. 0.01-0.1) layer (hereinafter referred to as the thin layer A) and the lubricity is inferior to that of the thin layer A. On the other hand, it has excellent high-temperature hardness and is compared with the thin layer A. and Ti and Si composite nitride having a more excellent high-temperature strength _{[Ti 1-Y Si Y]} N (Y in atomic ratio from 0.01 to 0.1) layer (hereinafter, referred to as thin layer B) When the layers are alternately laminated with each layer having an average layer thickness of 0.01 to 0.3 μm, the hard coating layer having this alternately laminated structure has excellent lubricity and high temperature hardness of the thin layer A. Without compromising, the high temperature strength better than that of the thin layer B can be combined.
The research results shown in (a) to (c) above were obtained.

This invention was made based on the above research results,
In the surface-coated cubic boron nitride-based ultra-high pressure sintered material cutting tool in which a hard coating layer is vapor-deposited on the surface of the insert made of ultra-high pressure sintered material containing 30 to 95% by mass of boron nitride,
(A) The hard coating layer consists of a lower layer having an average layer thickness of 1.5 to 6 μm and an upper layer having an average layer thickness of 0.3 to 3 μm,
(B) a lower layer of the hard coating layer was vapor deposited, the composition _{formula: [Cr 1-X Si X} ] N ( provided that, X is atomic ratio, shows a 0.01 to 0.1) satisfies A composite nitride layer of Cr and Si,
(C) The upper layer of the hard coating layer is formed by vapor deposition on the surface of the lower layer, and each has an alternately laminated structure of thin layers A and B each having an average layer thickness of 0.01 to 0.3 μm. And
The thin layer A is a composite nitride layer of Cr and Si that satisfies the composition formula: [Cr _1-X Si _X ] N (where X represents an atomic ratio of 0.01 to 0.1),
The thin layer B is composed of a composite nitride layer of Ti and Si that satisfies the composition formula: [Ti _1-Y Si _Y ] N (where Y represents an atomic ratio of 0.01 to 0.1),
A surface-coated cubic boron nitride-based ultra-high pressure sintered cutting tool (coating) that exhibits excellent wear resistance in high-speed cutting of high-hardness steel. cBN-based sintering tool).

Next, the reason why the hard coating layer of the coated cBN-based sintered tool according to the present invention is numerically limited as described above will be described.
(A) Content of boron nitride (cBN) When the boron nitride (cBN) content in the insert made of ultra high pressure sintered material is less than 30% by mass, the hardness of the cBN sintered material is reduced, and the ultra high pressure When performing high-speed cutting of high-hardness steel using an insert made of sintered material, it becomes impossible to provide the minimum required hardness and wear resistance is reduced, while containing boron nitride (cBN) When the amount exceeds 95% by mass, it becomes difficult to ensure the adhesion strength between the cBN sintered material and the hard coating layer, and as a result, the hard coating layer is easily peeled off. Therefore, in this invention, boron nitride (cBN) is contained. The amount was determined to be 30 to 95% by mass.

Cr component in (b) a hard coating layer Cr and Si composite nitride layer of constituting the lower layer _{[Cr 1-X Si X]} N contributes to the improvement of retention and lubricity of predetermined high temperature strength, addition, Si Since the component contributes to the improvement of the high temperature hardness, the Cr and Si composite nitride layer [Cr _1-X Si _X ] N (where X is an atomic ratio, 0) constituting the lower layer of the hard coating layer. .01 to 0.1) is a layer having a predetermined high-temperature strength, excellent high-temperature hardness, and lubricity, and has high wear resistance of the cutting edge during high-speed cutting of high-hardness steel. The role to secure is basically taken. However, when the Si content ratio X exceeds 10 atomic%, the high temperature hardness of the lower layer increases and wear resistance improves, but the high temperature strength and lubricity rapidly decrease due to a decrease in the Cr content ratio. Therefore, chipping is likely to occur. On the other hand, if the Si content ratio X is less than 1 atomic%, the high-temperature hardness decreases, so that the wear of the cutting edge during high-speed cutting of high-hardness steel. Since the progress is rapidly promoted and the wear resistance cannot be sufficiently secured, the value of the Si content ratio X is set to 0.01 to 0.1.
In addition, if the average thickness of the lower layer is less than 1.5 μm, the predetermined high-temperature strength and excellent high-temperature hardness and lubricity cannot be imparted to the hard coating layer over a long period of time, resulting in a short tool life. On the other hand, if the average layer thickness exceeds 6 μm, chipping is likely to occur. Therefore, the average layer thickness was set to 1.5 to 6 μm.
Note that a thin layer of titanium nitride (TiN) can be interposed between the base and the lower layer in order to ensure sufficient adhesion between the insert base made of the ultra-high pressure sintered material and the lower layer. The thin layer of TiN has little effect of improving the adhesion when the layer thickness is less than 0.01 μm, and on the other hand, even if the layer thickness exceeds 0.5 μm, further improvement in adhesion cannot be expected. The thickness of the TiN layer interposed between the substrate and the lower layer is preferably 0.01 μm or more and 0.5 μm or less.

(C) Upper layer thin layer A
Composite nitride layer of Cr and Si constituting a thin layer A of the top layer _{[Cr 1-X Si X]} N ( provided that, X is atomic ratio, shows a 0.01 to 0.1), the lower layer The layer has substantially the same high-temperature strength, excellent high-temperature hardness and lubricity, and has the effect of ensuring the wear resistance of the cutting edge during high-speed cutting of high-hardness steel.

(D) Upper layer thin layer B
A thin layer B composed of a composite nitride layer of Ti and Si that satisfies the composition formula: [Ti _1-Y Si _Y ] N (wherein Y represents an atomic ratio of 0.01 to 0.1) In the upper layer composed of the alternately laminated structure of the thin layer A and the thin layer B, the main purpose is to supplement the characteristics (high temperature strength) that the thin layer A lacks.
As already mentioned, the upper layer thin layer A is a layer having a predetermined high-temperature strength and excellent high-temperature hardness and lubricity, but under the condition of high-speed cutting of high-hardness steel with high heat generation, Its high temperature strength is not sufficient.
Therefore, the Ti and Si composite nitride [Ti _1-Y Si _Y ] having excellent high-temperature hardness and superior high-temperature strength as compared with the thin layer A as the thin layer B of the upper layer. N (Y is an atomic ratio of 0.01 to 0.1) layers are alternately arranged with the thin layers A to form an alternate laminated structure, thereby making up for the lack of high-temperature strength of the adjacent thin layers A. The upper layer having the excellent high temperature strength of the thin layer B is formed without impairing the excellent high temperature hardness and lubricity of the thin layer A.
The Ti component in the composite nitride layer [Ti _1-Y Si _Y ] N of Ti and Si contributes to the improvement of the high temperature strength, and the Si component contributes to the improvement of the high temperature hardness. layer composite nitride layer of Ti and _{Si [Ti 1-Y Si Y} ] N (Y is from 0.01 to 0.1 in atomic ratio) layer, having a high-temperature strength superior with excellent high-temperature hardness of However, it has the effect of improving the wear resistance of the cutting edge during high-speed cutting of high hardness steel. However, when the Si content Y exceeds 10 atomic%, the high temperature hardness of the thin layer B increases, but the high temperature strength decreases due to the decrease in the Ti content, whereas the Si content Y When the content is less than 1 atomic%, although the hardness at high temperature is excellent, the chipping suppression effect at the cutting edge and the wear progress suppression effect become unsatisfactory due to a decrease in the relative high temperature strength. Was determined to be 0.01 to 0.1.

(E) Upper layer thin layer A and thin layer B one layer average layer thickness, upper layer average layer thickness Upper layer thin layer A and thin layer B, each layer average layer thickness is less than 0.01 μm, respectively The excellent characteristics of the thin layer cannot be exhibited. As a result, the high temperature strength, high temperature hardness and lubricity superior in the upper layer cannot be secured, and the average layer thickness of each layer is 0. If the thickness exceeds 3 μm, the disadvantages of each thin layer, that is, if it is thin layer A, insufficient high-temperature strength will appear locally, and if thin layer B, insufficient lubricity will appear locally in the layer. And the average layer thickness of each layer was determined to be 0.01 to 0.3 μm.
That is, the thin layer B is provided to further improve the high-temperature strength of the thin layer A, but the average layer thickness of each of the thin layers A and B is 0.01 to 0.3 μm. If it is within the range, the upper layer composed of the alternately laminated structure of the thin layer A and the thin layer B is as if it is a single layer having excellent lubricity in addition to excellent high temperature strength and high temperature hardness. However, when the average layer thickness of each of the thin layer A and the thin layer B exceeds 0.3 μm, the high temperature strength of the thin layer A or the relative lubricity of the thin layer B is insufficient in the layer. Since it appears locally and the upper layer as a whole cannot exhibit good characteristics as one layer, the average layer thickness of each of the thin layers A and B is 0.01 to 0.3 μm. It was determined.
Excellent high-temperature strength and high-temperature hardness by forming on the lower layer surface an upper layer composed of an alternating laminated structure in which the average layer thickness of the thin layers A and B is in the range of 0.01 to 0.3 μm. In addition, a hard coating layer having excellent lubricity can be obtained.
Moreover, when the average layer thickness of the upper layer (that is, the total layer thickness of the thin layers A and B constituting the alternate laminated structure) is less than 0.3 μm, high-speed cutting of high-hardness steel is performed. Sufficient high-temperature hardness, lubricity and high-temperature strength required for processing cannot be imparted to the upper layer, resulting in a short tool life. On the other hand, if the average layer thickness exceeds 3 μm, chipping occurs. Since it becomes easy, the average layer thickness was determined to be 0.3 to 3 μm.

In the coated cBN-based sintered tool of the present invention, a slightly different interference color may be generated depending on the thickness of the coating layer on the outermost surface, and the tool appearance may be uneven. In such a case, unevenness of the appearance of the tool can be prevented by thickly depositing a titanium nitride (TiN) layer or a Ti / Si composite nitride (TiSiN) layer. At that time, if the average layer thickness of the TiN layer or TiSiN layer is less than 0.2 μm, uneven appearance cannot be prevented, and if the average layer thickness is up to 2 μm, uneven appearance can be sufficiently prevented. The average layer thickness of the titanium (TiN) layer or the composite nitride of Ti and Si (TiSiN) layer may be 0.2 to 2 μm.
In addition, the surface roughness of the coated cBN-based sintered tool base of the present invention is desirably 0.05 to 1.0 in terms of Ra. If the surface roughness Ra is 0.05 or more, an improvement in adhesion strength between the substrate and the hard coating layer due to the anchor effect can be expected. On the other hand, if Ra exceeds 1.0, the finished surface of the work material This is because the accuracy is adversely affected.

  In the coated cBN-based sintered tool of the present invention, the hard coating layer is composed of an upper layer and a lower layer, and the upper layer of the hard coating layer has an excellent laminated structure of the thin layer A and the thin layer B. Since it has excellent lubricity as well as high temperature hardness, it exhibits excellent wear resistance over a long period of time without chipping in the hard coating layer even in high-speed cutting of high-hardness steel, especially with high heat generation. Is.

  Next, the coated cBN-based sintered tool of the present invention will be specifically described with reference to examples.

As raw material powders, cubic boron nitride (cBN) powder, titanium carbide (TiC) powder, titanium nitride (TiN) powder, titanium carbonitride (TiCN) powder each having an average particle size in the range of 0.5 to 4 μm , Tungsten carbide (WC) powder, Al powder, Co powder, Ti ₃ Al powder that is an intermetallic compound powder of Ti and Al, TiAl powder, and TiAl ₃ powder, and a composite metal nitride having a composition formula: Ti ₂ AlN Prepare powder, TiB ₂ powder, aluminum nitride (AlN) powder, aluminum boride (AlB ₂ ) powder, aluminum oxide (Al ₂ O ₃ ) powder, and blend these raw material powders into the composition shown in Table 1, After wet mixing with a ball mill for 80 hours and drying, a green compact having a diameter of 50 mm × thickness of 1.5 mm was preliminarily formed at a pressure of 120 MPa. Then, the green compact is sintered in a vacuum atmosphere at a pressure of 1 Pa at a predetermined temperature within a range of 900 to 1300 ° C. for 60 minutes to obtain a presintered body for a cutting blade piece. This pre-sintered body is overlaid with a separately prepared WC-based cemented carbide support piece having dimensions of Co: 8% by mass, WC: remaining composition, and diameter: 50 mm × thickness: 2 mm. In an ordinary ultra high pressure sintering apparatus, the normal pressure is 5 GPa, the temperature is 1200 ° C. within a predetermined temperature range of 1200 to 1400 ° C., and the holding time is 0.8 hours. After sintering, the upper and lower surfaces are polished with a diamond grindstone and divided into a regular triangle shape with a side of 3 mm by a wire electric discharge machine, and Co: 5% by mass, TaC: 5% by mass, WC: remaining composition And CIS standard SNGA12041 shape (thickness: 4 In the brazed part (corner part) of the WC-based cemented carbide chip body having a 76 mm × one side length: 12.7 mm regular triangle), by mass%, Cu: 30%, Zn: 28%, Ni: After brazing using a brazing material of Ag alloy having a composition of 2%, Ag: remaining, and processing the outer periphery to a predetermined dimension, the cutting edge is subjected to a honing process of width: 0.15 mm, angle: 25 ° Further, by performing finish polishing, tool bases A to J each having a chip shape of ISO standard SNGA12041 were manufactured.

(A) Next, each of the tool bases A to J is ultrasonically cleaned in acetone and dried, and then in a radial direction from the central axis on the rotary table in the arc ion plating apparatus shown in FIG. For forming a thin layer B of the upper layer having a component composition corresponding to the target composition shown in Table 2 as a cathode electrode (evaporation source) on one side at a position separated by a predetermined distance The Ti-Si alloy is used as the cathode electrode (evaporation source) on the other side, and the upper layer thin layer A and the lower layer forming Cr-Si each having a component composition corresponding to the target composition shown in Table 2 are also used. An alloy is placed opposite to the rotary table.
(B) First, while the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, the inside of the apparatus is heated to 500 ° C. with a heater, and then Ar gas is introduced to create an atmosphere of 0.7 Pa. A DC bias voltage of −200 V is applied to the tool base that rotates while rotating on the table, and the tool base surface is bombarded with argon ions.
(C) Nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 3 Pa, a DC bias voltage of −100 V is applied to the tool base rotating while rotating on the rotary table, and the thin layer A current of 100 A is passed between the A and Cr-Si alloy for forming the lower layer and the anode electrode to generate an arc discharge, so that the target composition and target layer thickness shown in Table 2 ( (Cr, Si) N layer is deposited as a lower layer of the hard coating layer,
(D) Next, the flow rate of nitrogen gas as a reaction gas introduced into the apparatus is adjusted to obtain a reaction atmosphere of 2 Pa, and within a range of −10 to −100 V on the tool base that rotates while rotating on the rotary table. With a predetermined DC bias voltage applied, a predetermined current in a range of 50 to 200 A is passed between the cathode electrode and the anode electrode of the Ti-Si alloy for forming the thin layer B to generate arc discharge. Then, a thin layer B having a predetermined layer thickness is formed on the surface of the tool base, and after the thin layer B is formed, the arc discharge is stopped. Instead, the cathode of the Cr-Si alloy for forming the thin layer A and the lower layer is used. Similarly, a predetermined current in the range of 50 to 200 A is passed between the electrode and the anode electrode to generate arc discharge to form a thin layer A having a predetermined layer thickness. Then, the arc discharge is stopped and the thin layer B is again formed. Ti-Si for forming The formation of the thin layer B by arc discharge between the gold cathode electrode and the anode electrode and the formation of the thin layer A by arc discharge between the cathode electrode and the anode electrode of the thin layer A and the Cr-Si alloy for forming the lower layer are alternately performed. Table 2 shows the upper layer composed of the alternate lamination of the thin layer A and the thin layer B having the target composition and the single target layer thickness along the layer thickness direction on the surface of the tool base. The present invention-coated cBN-based sintered tools 1 to 9 were produced by vapor deposition with the total layer thickness (average layer thickness) shown.

  For comparison purposes, each of the tool bases A to J described above is ultrasonically cleaned in acetone and dried, and then charged into a normal arc ion plating apparatus shown in FIG. As the (evaporation source), a Cr—Si alloy having a component composition corresponding to the target composition shown in Table 3 was mounted, and first, the heater was evacuated and kept at a vacuum of 0.1 Pa or less. After heating the inside of the apparatus to 500 ° C., Ar gas is introduced to make an atmosphere of 0.7 Pa, and a DC bias voltage of −200 V is applied to the tool base that rotates while rotating on the table. The tool substrate surface is bombarded with argon ions, and then nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of 3 Pa, and a via applied to the tool substrate. The voltage was lowered to −100 V to generate an arc discharge between the cathode electrode and the anode electrode of the Cr—Si alloy, so that the target composition shown in Table 3 and the surface of each of the tool bases A to J were Conventionally coated cBN-based sintered tools 1 to 9 were respectively produced by vapor-depositing a hard coating layer composed of a target layer thickness (Cr, Si) N layer.

Next, according to the present invention, the coated cBN-based sintered tools 1 to 9 and the conventional coated cBN-based sintered tools, in a state where all of the above-mentioned coated cBN-based sintered tools are screwed to the tip of the tool steel tool with a fixing jig. For cBN-based sintered tools 1-9,
Work material: JIS / SCM415 quenching material (hardness: HRC60) round bar,
Cutting speed: 330 m / min. ,
Cutting depth: 0.08 mm,
Feed: 0.06 mm / rev. ,
Cutting time: 8 minutes,
Dry continuous high-speed cutting test of the alloy tool steel under the conditions (cutting condition A) (normal cutting speed is 200 m / min.),
Work material: JIS / SUJ2 hardened material (hardness: HRC61) round bar,
Cutting speed: 300 m / min. ,
Cutting depth: 0.12 mm,
Feed: 0.05 mm / rev. ,
Cutting time: 6 minutes,
Dry continuous high-speed cutting test of bearing steel under the following conditions (referred to as cutting condition B) (normal cutting speed is 150 m / min.),
Work material: JIS / SKD61 hardened material (hardness: HRC61) round bar,
Cutting speed: 240 m / min. ,
Cutting depth: 0.10 mm,
Feed: 0.06 mm / rev. ,
Cutting time: 5 minutes,
Dry continuous high-speed cutting test of die steel under the above conditions (referred to as cutting condition C) (normal cutting speed is 90 m / min.)
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 4.

  As a result, the composition of the hard coating layers of the present coated cBN-based sintered tools 1 to 9 and the conventional coated cBN-based sintered tools 1 to 9 are analyzed by energy dispersive X-ray analysis using a transmission electron microscope. As a result of measurement, each showed substantially the same composition as the target composition.

  Further, when the average layer thickness of the constituent layers of the hard coating layer was subjected to cross-sectional measurement using a transmission electron microscope, all showed the same average value (average value of five locations) as the target layer thickness.

  From the results shown in Tables 2 to 4, all of the coated cBN-based sintered tools of the present invention have a hard coating layer, and alternate layers of thin layer A and thin layer B each having an average layer thickness of 0.01 to 0.3 μm. An upper layer having an average layer thickness (total layer thickness) of 0.3 to 3 μm having a laminated structure and a lower layer having an average layer thickness of 1.5 to 6 μm. In addition, the lower layer has a predetermined high-temperature strength, excellent high-temperature hardness, and lubricity, and is accompanied by high heat generation of high-hardness steel such as alloy tool steel and hardened material of bearing steel. Even with high-speed cutting, excellent wear resistance is exhibited without occurrence of chipping, whereas the conventional coated cBN-based sintered tool whose hard coating layer is a single (Ti, Si) N layer is particularly hard. Chipping occurs due to insufficient high-temperature strength of the coating layer. It is clear that lead to use life.

  As described above, the coated cBN-based sintered tool of the present invention can be used not only for cutting under normal cutting conditions such as various steels and cast iron, but also for high-speed cutting with high heat generation of high-hardness steel. Because it shows excellent wear resistance and cutting performance over a long period of time, it can fully satisfy the high performance of cutting equipment, labor saving and energy saving of cutting, and cost reduction. .

The arc ion plating apparatus used for forming the hard coating layer which comprises the coated cBN group sintered tool of this invention is shown, (a) is a schematic plan view, (b) is a schematic front view. It is a schematic explanatory drawing of a normal arc ion plating apparatus.

Claims (1)

In the surface-coated cubic boron nitride-based ultra-high pressure sintered material cutting tool in which a hard coating layer is vapor-deposited on the surface of the insert made of ultra-high pressure sintered material containing 30 to 95% by mass of boron nitride,
(A) The hard coating layer consists of a lower layer having an average layer thickness of 1.5 to 6 μm and an upper layer having an average layer thickness of 0.3 to 3 μm,
(B) a lower layer of the hard coating layer was vapor deposited, the composition _{formula: [Cr 1-X Si X} ] N ( provided that, X is atomic ratio, shows a 0.01 to 0.1) satisfies A composite nitride layer of Cr and Si,
(C) The upper layer of the hard coating layer is formed by vapor deposition on the surface of the lower layer, and each has an alternately laminated structure of thin layers A and B each having an average layer thickness of 0.01 to 0.3 μm. And
The thin layer A is a composite nitride layer of Cr and Si that satisfies the composition formula: [Cr _1-X Si _X ] N (where X represents an atomic ratio of 0.01 to 0.1),
The thin layer B is composed of a composite nitride layer of Ti and Si that satisfies the composition formula: [Ti _1-Y Si _Y ] N (where Y represents an atomic ratio of 0.01 to 0.1). A surface-coated cubic boron nitride-based ultra-high pressure sintered material cutting tool that exhibits excellent wear resistance in high-speed cutting of high-hardness steel with a hard coating layer formed by vapor deposition.

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