JP2019155570A - Surface-coated cutting tool having hard coating layer exerting excellent oxidation resistance and deposition resistance - Google Patents

Abstract

To provide a surface-coated cutting tool having a long service life even when using in such a cutting work that the temperature of a blade tip becomes high like the case of a heat resistant alloy.SOLUTION: In an objective surface-coated cutting tool, the upper and lower layers are formed on any tool substrate of WC-based hard metal, TiCN-based cermet and CBN-based superhigh pressure sintered body. The upper layer comprises an AlOlayer having an α type crystal structure, and the lower layer consists of a Ti-Al composite nitride layer or composite carbonitride layer including at least the crystalline layer of NaCl type face-centered cubic structure. The cutting tool satisfies T=0.0 to 5.0 μm, T=1.0 to 20.0 μm and T<Twhen defining the thickness in a blade tip edge of the upper layer as Tand that of the point separate from the blade tip edge by 500 μm in a cutting face direction as Tand besides, the tool satisfies T=0.0 to 5.0 μm, T=1.0 to 20.0 μm and T<Twhen defining the thickness in the blade tip edge of the lower layer as Tand that of the point separate from the blade tip edge by 500 μm in the cutting face direction as T.SELECTED DRAWING: Figure 1

Description

  In the present invention, when a heat resistant alloy having a high cutting edge is machined, the hard coating layer has excellent oxidation resistance and welding resistance, and further, occurrence of chipping, chipping, peeling, etc. is suppressed, and long-term The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent welding resistance after use.

Conventionally, for the purpose of improving the cutting performance of cutting tools, tungsten carbide (hereinafter referred to as WC) based cemented carbide, titanium carbonitride (hereinafter referred to as TiCN) based cermet or cubic boron nitride (hereinafter referred to as cBN). ) A Ti-Al composite nitride layer is coated as a hard coating layer on the surface of a tool substrate composed of a super-high-pressure sintered body (hereinafter collectively referred to as a substrate) by vapor deposition. There are formed coated tools, which are known to exhibit excellent wear resistance.
Although the conventional coated tool formed by coating the conventional Ti-Al based composite nitride layer is relatively excellent in wear resistance, it is hard to cause abnormal wear such as chipping when used under high-speed cutting conditions. Various proposals for improving the coating layer have been made.

For example, Patent Document 1 discloses that
A cutting tool having a plurality of layers in which a substrate made of cemented carbide, cermet or ceramics having a TiN layer and / or a TiCN layer bonding layer is coated with a hard material and deposited by CVD,
Ti _1-x Al _x N layer and / or Ti _1-x Al _x C layer and / or Ti _1-x Al _x CN layer (x is 0.65 to 0.95) and Al ₂ O ₃ outer layer A TiCN layer is disposed between
(Ti _1-x Al _x N, Ti _1-x Al _x CN, Ti _1-x Al _x C) A multilayer intermediate layer composed of one or more double layers or triple layers from the group of _n is the Al ₂ O ₃ is placed under the outer layer,
The outer layer has a thickness of 1 to 5 μm,
The thickness of the Ti _1-x Al _x N layer and / or the Ti _1-x Al _x C layer and / or the Ti _1-x Al _x CN layer is 1 to 5 μm,
The bonding layer or the intermediate layer has a thickness of 1 to 5 μm,
The Ti _1-x Al _x N layer, Ti _1-x Al _x C layer, or Ti _1-x Al _x CN layer contains up to 25% hexagonal AlN;
A cutting tool is described, and the coating layer is said to have a heat insulating effect.

In addition, in Patent Document 2,
A cutting tool having a plurality of layers coated with a hard material and formed by a CVD method on a substrate made of cemented carbide, cermet or ceramics,
The outer layer is made of Ti _1-x Al _x N, Ti _1-x Al _x C, and / or Ti _1-x Al _x CN (0.65 ≦ x ≦ 0.9), and the outer layer is in the range of 100 to 1100 MPa. A TiCN layer or an Al ₂ O ₃ layer is disposed under this outer layer,
The outer layer has a single phase having a cubic structure, or a maximum of 25% by mass of hexagonal AlN, or a maximum of 30% by mass of an amorphous component,
The chlorine content is 0.01-3 atomic%,
A cutting tool is described and is said to have heat resistance and cycle fatigue characteristics.

Furthermore, Patent Document 3 includes:
A surface-coated cutting tool comprising a substrate and a coating layer formed on the substrate surface,
The coating layer is composed of one or more layers,
In the cross section obtained by cutting the surface-coated cutting tool on a plane including a normal line of the surface of the coating layer at the center of the rake face and a ridge where two flank surfaces intersect, the thinnest edge portion of the cutting edge of the coating layer When the thickness of the part is T ₁ and the thickness at a point 1 mm away from the edge of the cutting edge in the rake face direction is T ₂ , T ₁ <T ₂ is satisfied, and
On the surface of the coating layer, when a point _a distance D _a away from the edge of the cutting edge in the rake face direction is a and a point a distance D _b away in the flank direction is b, the D _a is 0.05 mm ≦ D _a ≦ 0.5 mm is satisfied, and D _b satisfies 0.01 mm ≦ D _b ≦ 0.2 mm, and the coating layer from point a to point b has a thickness of 0.1T _{1 to} 0.9T from the surface. _{In a} region of 10% or more of the region E occupying ₁ , the deviation of crystal orientation of the crystal grains constituting the coating layer is 5 degrees or more and less than 10 degrees
A surface coated cutting tool is described.

Subsequently, Patent Document 4 describes:
Through an intermediate layer at a location related to cutting of the surface of the hard sintered base material containing 20% by volume or more of high-pressure phase boron nitride,
A first hard wear-resistant coating layer that is a (Ti, Al) N layer or a laminate of a TiN layer and an AlN layer, and an Al ₂ O ₃ layer or Al ₂ O on at least a part of the outer side of the first hard wear-resistant coating layer Having a second hard wear-resistant coating layer in which _three layers and a TiCN layer are laminated,
Furthermore, the part which participates in the cutting of the part corresponding to the rake face of the hard sintered base has the first hard wear-resistant coating layer and the second hard wear-resistant coating layer, and the part corresponding to the flank Has only the first hard wear-resistant coating layer,
The intermediate layer is at least one selected from TiN, TiC, TiCN and TiCN having a thickness of 0.05 to 5 μm,
At least a part of the outer surface of the first and second hard wear-resistant coating layers has a surface layer selected from TiC, TiN, TiCN and TiCNO having a film thickness of 0.1 to 5 μm, and is quenched. Used for steel and cast iron,
A hard wear layer composite coated cutting tool is described.

In addition, Patent Document 5 includes
Includes a rake face, a flank face, a cutting edge where the rake face and the flank face intersect, and an abrasion resistant multilayer coating made of aluminum oxide and including a layer deposited on a hard material layer A cutting tool made of ceramic, cermet or cemented carbide,
The coating includes one or more layers deposited over the aluminum oxide layer, this / these additional layers being removed with the aluminum oxide layer only at the flank, and the underlying hard material layer is at least Partially exposed,
Cutting tools are listed,
It is also described that the exposure of the hard material layer of the base is any one of mechanical removal, removal by fluid ejection, and removal by a laser.

Special table 2011-516722 gazette Special table 2011-513594 gazette JP 2012-20391 A JP-A-8-323506 JP-T-2007-528795

  Although Patent Documents 1 and 2 disclose that the cutting tool coating layer has heat insulation or heat resistance and cycle fatigue strength, the characteristics required for each of the edge line and the rake face as the cutting tool coating layer are disclosed. There is no disclosure of how to deal with this.

  In the cutting tool of Patent Document 3, since the film thickness of the coating layer of the cutting edge ridge line part that linearly approximates the flank and the rake face is thinned, and distortion occurs in the upper part of the coating layer, the cutting edge strength can be enhanced. As a result, while the coating layer can improve wear resistance and prevent the coating layer from falling off and chipping, Patent Document 3 is similar to Patent Documents 1 and 2, and the edge of the cutting edge as a cutting tool coating layer There is no disclosure about dealing with the characteristics required of each rake face.

  In Patent Document 4, there is a description that mechanical wear is dominant in the flank face, and that the rake face has a high thermal wear ratio. The physical properties required for the flank face and rake face of the coating layer, respectively. Disclosure has been made. However, the cutting object of the cutting tool described in Patent Document 4 is hardened steel or cast iron, and cannot sufficiently handle cutting of a heat-resistant alloy.

The cutting tool of Patent Document 5 focuses only on the rake face Al ₂ O ₃ and cannot sufficiently cope with cutting of a heat-resistant alloy.

  Therefore, an object of the present invention is to provide a coated tool having a long tool life without causing wear even when the cutting edge such as a heat-resistant alloy is used for cutting at a high temperature.

  As described above, the present inventor, even when used for cutting at a high temperature such as a heat-resistant alloy, exhibits oxidation resistance and welding resistance and suppresses occurrence of chipping, chipping, peeling, etc. From the viewpoint of providing a coated tool that has excellent wear resistance over the use of each of the above, the following new findings were obtained as a result of intensive studies on the required characteristics of the flank and edge of the coating layer. Obtained.

That is, when a composite nitride layer or composite carbonitride layer of Ti and Al is provided as the lower layer, and the layer thickness of the lower layer has a predetermined layer thickness at a predetermined position on the edge of the cutting edge and the rake face When a chemically stable Al ₂ O ₃ layer having a predetermined layer thickness thicker than the edge of the cutting edge is provided on the rake face side as an upper layer above the lower layer, the rake face has oxidation resistance and welding resistance. It has been found that the wear resistance is improved and the wear resistance is not lowered even if an Al ₂ O ₃ layer having a predetermined layer thickness thinner than the rake face side is provided on the edge of the cutting edge. .

This invention is made | formed based on the said knowledge, and is as follows.
“A hard coating comprising at least two layers of an upper layer (α) and a lower layer (β) on the surface of a tool base composed of either a WC-based cemented carbide, TiCN-based cermet or cBN-based ultrahigh pressure sintered body In a surface-coated cutting tool in which a layer is formed,
(A) The upper layer (α) comprises an Al ₂ O ₃ layer having an α-type crystal structure,
(B) The lower layer (β) is composed of a composite nitride or composite carbonitride layer of Ti and Al,
(C) The Ti and Al composite nitride or composite carbonitride layer includes at least a crystal layer having a NaCl-type face-centered cubic structure. (D) The thickness of the upper layer (α) at the edge of the cutting edge is T _α1 , When the thickness at a point 500 μm away from the edge of the cutting edge in the rake face direction is T _α2 , T _α1 satisfies 0.0 to 5.0 μm, T _α2 satisfies 1.0 to 20.0 μm, and T _α1 <T satisfies _α2 ,
(E) When the thickness of the lower layer (β) at the cutting edge ridge line is T _β1 and the thickness at a point 500 μm away from the cutting edge ridge line in the rake face direction is T _β2 , T _β1 and T _β2 are 1.0 to 20. A surface-coated cutting tool characterized by satisfying 0 μm and satisfying T _β2 <T _β1 .
(2) The surface-coated cutting tool according to (1), wherein the upper layer (α) contains 0.005 to 0.050 atomic% of chlorine.
(3) When the average composition of the composite nitride layer or composite carbonitride layer of Ti and Al in the lower layer (β) is represented by (Ti _1-X Al _X ) (C _Y N _1-Y ), The average content ratio X in the total amount of Ti and Al in Al and the average content ratio Y in the total amount of C and N in C (where X and Y are atomic ratios) are 0.60 ≦ X, respectively. The surface-coated cutting tool according to (1) or (2), wherein ≦ 0.95 and 0 ≦ Y ≦ 0.005 are satisfied.
(4) One or two or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer between the tool base and the lower layer (β) The surface-coated cutting tool according to any one of (1) to (3), wherein a bonding layer comprising a compound layer and having a total average layer thickness of 0.1 to 20.0 μm exists. "

As a lower layer, a composite nitride layer or composite carbonitride layer of Ti and Al having a predetermined layer thickness is provided at a predetermined position on the edge of the cutting edge and the rake face, and the upper layer is exposed to a high temperature on the lower layer. By providing a chemically stable Al ₂ O ₃ layer with a predetermined layer thickness that is thicker than the edge of the cutting edge on the rake face side, the oxidation resistance and welding resistance on the rake face side are increased and wear resistance is improved. On the other hand, since the wear resistance is not lowered even if an Al ₂ O ₃ layer having a predetermined layer thickness is provided on the edge of the cutting edge, which is thinner than the rake face side, the life of the coated tool is significantly improved. The present invention has an effect.

In the surface-coated cutting tool of the present invention, the edge ridgeline and the rake face side upper layer (α-type Al ₂ O ₃ layer) and lower layer (Ti-Al composite nitride layer or composite carbonitride layer) It is a schematic diagram which shows thickness.

  The form for implementing this invention is demonstrated below.

Cutting edge ridge line In the present invention, the cutting edge ridge line approximates the rake face and the flank face with straight lines, and when the straight line is extended, the intersection A intersects both extension lines, and the distance from the cutting edge ridge line is The distance along the straight line from the intersection A of the straight line. The film thickness of the cutting edge ridge line refers to the film thickness at the intersection point B when a straight line is drawn so as to divide the angle formed by the straight line into two equal parts and set as the intersection point B with the insert surface.

Lower layer (β) composed of a composite nitride layer or composite carbonitride layer of Ti and Al
The lower layer formed of a composite nitride layer or composite carbonitride layer of Ti and Al is formed using a thermal CVD apparatus so as to include at least a phase of a NaCl type face centered cubic structure.
As an example of film formation conditions,
Reaction gas composition (volume%)
Gas group A: NH ₃ : 0.8 to 1.6%, H ₂ : 45 to 55%
Gas group B: AlCl ₃ : 0.5 to 0.7%, Al (CH ₃ ) ₃ : 0.00 to 0.08%,
TiCl ₄ : 0.1 to 0.3%, N ₂ : 0.0 to 10.0%, H ₂ : residual reaction atmosphere pressure: 4.0 to 5.0 kPa
Reaction atmosphere temperature: 700-900 ° C
Can be mentioned.
Here, the gas group A and the gas group B are separated and supplied in the space in the reaction vessel of the thermal CVD apparatus until just before the film formation object, and the gas group A and the gas just before the film formation object. Allow Group B to mix and react. This is effective for uniformly forming gas species having high reaction activity over the film forming region, and detailed technical contents are disclosed in, for example, Japanese Patent Application Laid-Open No. 2015-131984.
Further, when the layer thickness of the lower layer is T _{β1 at} the edge of the blade edge and T _β2 at a point 500 μm away from the edge of the edge in the rake face direction, both T _β1 and T _β2 are 1.0 to 20.0 μm. It forms into a film so that it may become. Thereafter, the rake face is subjected to, for example, mechanical polishing or wet blasting so as to reduce the thickness of the lower layer so that the layer thickness satisfies T _β2 <T _β1 . The composite nitride or composite carbonitride layer of Ti and Al is high in hardness and has excellent wear resistance. Particularly, when T _β1 and T _β2 are 1.0 to 20.0 μm, the effect is obtained. Is prominently demonstrated. The reason is that if the layer thickness is less than 1.0 μm, the layer thickness is thin, so that sufficient wear resistance over a long period of use cannot be ensured. On the other hand, if the average layer thickness exceeds 20.0 μm, Ti and Al This is because the crystal grains of the composite nitride or composite carbonitride layer are likely to be coarsened and chipping is likely to occur.
Here, in combination with the thickness of the upper layer of T _α1 <T _α2 to be described later, even if the thickness of the lower layer is thinner than the edge of the cutting edge, From the knowledge that chipping properties are excellent, the layer thickness of the lower layer was defined as T _β1 > T _β2 .
In addition, the composition of the lower layer is the average content ratio X and C of C in the total amount of Ti and Al in the case where the average composition is represented by (Ti _1-X Al _X ) (C _Y N _1-Y ). The average content ratio Y in the total amount of N and N (where X and Y are both atomic ratios) preferably satisfy 0.60 ≦ X ≦ 0.95 and 0 ≦ Y ≦ 0.005, respectively. . The reason is that when the average content ratio X of Al is less than 0.60, the (Ti _1-X Al _X ) (C _Y N _1-Y ) layer is inferior in oxidation resistance, and cutting of heat-resistant alloy steel or the like If the average content ratio X of Al exceeds 0.95, the amount of precipitated hexagonal crystals inferior in hardness increases and the hardness decreases. This is because the wear resistance may be reduced. Further, when the average content Y of the C component contained in the (Ti _1-X Al _X ) (C _Y N _1-Y ) layer is in the range of 0 ≦ Y ≦ 0.005, the lubricity is further improved. alleviate the impact during cutting by chipping resistance of the resulting _{(Ti 1-X Al X)} (C Y N 1-Y) layer, chipping resistance is improved. On the other hand, when the average content ratio Y of the C component deviates from the range of 0 ≦ Y ≦ 0.005, the toughness of the (Ti _1-X Al _X ) (C _Y N _1-Y ) layer decreases, so that chipping resistance, It is not preferable because the chipping resistance is lowered. Therefore, the average content ratio Y of C is preferably 0 ≦ Y ≦ 0.005.
Note that the average content ratio X of Al in the composite nitride or composite carbonitride layer was measured by using an electron beam microanalyzer (Electron-Probe-Micro-Analyzer: EPMA) and the surface was polished. Irradiated from the surface side, it was determined from the average of 10 points of the analysis results of the characteristic X-rays obtained. About the average content rate Y of C, it calculated | required by secondary ion mass spectrometry (Secondary-Ion-Mass-Spectroscopy: SIMS). That is, the ion beam was irradiated in a range of 70 μm × 70 μm from the sample surface side, and the concentration in the depth direction was measured for the component emitted by the sputtering action. The average content ratio Y of C shows the average value of the depth direction about the composite nitride or composite carbonitride layer of Ti and Al.
In addition, it is necessary that crystal grains having a NaCl-type face-centered cubic structure in the (Ti _1-X Al _X ) (C _Y N _1-Y ) layer exist, and the area ratio is at least 40 areas. % Or more is preferable. As a result, there is a certain area ratio of crystal grains having a NaCl-type face-centered cubic structure with high hardness, and thus the hardness is improved. Further, when the area ratio is 60 areas or more, the crystal grains having the NaCl-type face-centered cubic structure are relatively higher than the crystal grains having the hexagonal crystal structure, thereby obtaining an effect that the hardness is further improved. be able to. This area ratio is more preferably 75 area% or more.

Upper layer (α) made of Al ₂ O ₃ having an α-type crystal structure (hereinafter referred to as α-Al ₂ O ₃ )
The upper layer is formed again after adjusting the thickness of the lower layer. In the film formation of α-Al ₂ O ₃ , film formation is performed by changing the conditions in the initial nucleation stage and the subsequent growth stage, and then the cutting edge edge line is formed so as to satisfy the layer thickness described later, for example, mechanical Polishing or wet blasting is performed to reduce the thickness of the upper layer.
As an example of film formation conditions,
<Α-Al ₂ O ₃ initial nucleation stage>
Reaction gas composition (volume%): AlCl ₃ : 1.0 to 3.0%, CO ₂ : 1.0 to 5.0%, HCl: 0.3 to 1.0%, balance: H ₂
Reaction atmosphere pressure: 5.0 to 15.0 kPa
Reaction atmosphere temperature: 800-900 ° C
<Α-Al ₂ O ₃ growth stage>
Reaction gas composition (volume%): AlCl ₃ : 1.5 to 5.0%, CO ₂ : 2.0 to 8.0%, HCl: 3.0 to 8.0%, H ₂ S: 0.5 to 1.0%, the balance: _{H 2}
Reaction atmosphere pressure: 5.0 to 15.0 kPa,
Reaction atmosphere temperature: 800 to 900 ° C.
Can be mentioned.
Further, the thickness of the upper layer is T _{α1 at} the edge of the blade edge, and T _α2 at a point 500 μm away from the edge of the edge in the flank direction, T _α1 is 0.0 to 5.0 μm, and T _α2 is 1.0. ˜20.0 μm and T _α1 <T _α2 must be satisfied.
The reason why the thickness of the upper layer is in this range is that α-Al ₂ O ₃ does not affect the wear resistance and chipping resistance even if it is not present on the edge of the blade edge (even if T _α1 = 0.0 μm). T _{[alpha] 1} is there is a possibility that peeling or chipping of the upper layer caused exceeds 5.0 .mu.m, decreases the wear resistance of the composite nitride layer or a composite carbonitride layer of the formed Ti and Al by a CVD method Further, if T _α2 is less than 1.0 μm, the heat shielding effect by α-Al ₂ O ₃ is insufficient, the upper layer is easily worn out, and is a thermally unstable metastable phase. A certain Ti and Al composite nitride layer or composite carbonitride layer is exposed and wear resistance is impaired, and when T _α2 exceeds 20.0 μm, the heat shielding effect by α-Al ₂ O ₃ is saturated. is there. Further, T _α1 <T _α2 was defined based on the knowledge that the cutting edge ridge line is excellent in wear resistance and chipping resistance even when the Al ₂ O ₃ layer is thinner than the rake face side.
Further, when the α-Al ₂ O ₃ layer is formed at a relatively low temperature (800 to 900 ° C.), chlorine as a reaction gas component is mixed into the layer. Although mixing of chlorine into the α-Al ₂ O ₃ layer is not an essential requirement, if it is mixed, if the chlorine content contained in the layer is 0.005 atomic% or more, α-Al _{The 2} O ₃ layer comes to have lubricity, and when subjected to intermittent cutting in which mechanical impact acts on the cutting edge, it absorbs the mechanical impact and more effectively suppresses abnormal damage such as chipping. On the other hand, if the chlorine content exceeds 0.050 atomic% and is contained excessively, the wear resistance of the α-Al ₂ O ₃ layer is deteriorated. Accordingly, the chlorine content in the upper layer composed of the α-Al ₂ O ₃ layer is preferably 0.005 to 0.050 atomic%.

Bonding layer between substrate and Ti and Al composite nitride layer or composite carbonitride layer Ti carbide layer, nitrided between substrate and Ti and Al composite nitride layer or composite carbonitride layer A bonded layer having a total average layer thickness of 0.1 to 20.0 μm, comprising one or more Ti compound layers of a physical layer, a carbonitride layer, a carbonate layer and a carbonitride layer. When provided, the bond between the substrate and the composite nitride layer or composite carbonitride layer of Ti and Al is further improved.

  Next, the coated tool of the present invention will be specifically described with reference to examples. In the following examples, a coated tool using a WC-based cemented carbide as a tool base will be described. However, the same applies when a TiCN-based cermet or a cBN-based ultrahigh-pressure sintered body is used as the tool base.

As raw material powders, WC powder, TiC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared, and these raw material powders are blended as shown in Table 1. Blended into the composition, added with wax, mixed in a ball mill in acetone for 24 hours, dried under reduced pressure, pressed into a compact of a predetermined shape at a pressure of 98 MPa, and the compact was 1370 in a vacuum of 5 Pa. WC-based cemented carbide tool substrate A having a insert shape of SEMT13T3AGSN manufactured by Mitsubishi Materials Corporation after sintering under vacuum at a predetermined temperature within a range of 1470 ° C. for 1 hour. C was produced respectively.

Next, a CVD apparatus is used on the surfaces of these tool bases A to C. First, under the conditions shown in Tables 2 and 3, the lower base layer has a predetermined composition (Ti _1-X Al _X ) ( After the C _Y N _1-Y ) layer was formed by vapor deposition until the target layer thickness was reached, a part of the lower layer on the rake face was removed by wet blasting. Then, an Al ₂ O ₃ layer that is an upper layer is formed under the conditions shown in Table 2 and Table 3, and then a part of the upper layer of the cutting edge ridge line is removed from the cutting edge ridge line by wet blasting. Present invention coated tools 1-15 were produced. In addition, about this invention coated tools 6-15, before forming a lower layer, the bonding layer shown in Table 4 was formed by the well-known method.

  For comparison purposes, the lower layer is formed on the surfaces of the tool bases A to D under the conditions shown in Tables 2 and 3 in the same manner as the coated tools 1 to 15 of the present invention, and the upper layer is formed by vapor deposition. Comparative coated tools 1 to 15 shown in Table 5 were manufactured without partial removal of the layer by the wet blast method. In addition, about the comparison coating tools 6-15, before forming a lower layer, the bonding layer shown in Table 5 was formed by the well-known method.

T _α1 , T _α2 , T _β1 , and T _β2 are measured for the cross-sections of the constituent layers of the inventive coated tools 1 to 15 and comparative coated tools 1 to 15 using a scanning electron microscope (5000 magnifications). did.

  Next, with respect to the present invention coated tools 1 to 15 and comparative coated tools 1 to 15, the heat-resistant alloy in a state in which each of the various coated tools is clamped to the tip of a tool steel cutter having a cutter diameter of 125 mm by a fixing jig. , Ni-19Cr-19Fe-3Mo-0.9Ti-0.5Al-5.1 (Nb + Ta) alloy age hardened material wet face milling, center cut cutting test, cutting edge flank wear width Was measured. The results are shown in Table 6.

Cutting test: wet face milling, center cut cutting cutter diameter: 125mm
Work material: The above heat-resistant alloy Block material having a width of 100 mm and a length of 400 mm Rotational speed: 127 min ⁻¹
Cutting speed: 50 m / min
Cutting depth: 1.0mm
Single blade feed: 0.12 mm / tooth Cutting time: 5 minutes

As raw material powders, WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared. After blending into the composition shown in Table 7, adding wax, ball mill mixing in acetone for 24 hours, drying under reduced pressure, press molding into a green compact of a predetermined shape at a pressure of 98 MPa. In a 5 Pa vacuum, vacuum sintering is performed at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour, and after sintering, the cutting edge is subjected to a honing process of R: 0.03 mm. Tool bases α to γ made of WC-base cemented carbide having the insert shape of CNMG120408 were manufactured.

  Next, using the CVD apparatus on the surface of these tool bases α to γ and tool base δ, the book shown in Table 8 under the conditions shown in Table 2 and Table 3 in the same manner as in Examples 1-15. Invention coated tools 16-30 were produced. In addition, about this invention coated tools 21-30, before forming a lower layer, the bonding layer shown in Table 8 was formed by the well-known method.

  Further, for the purpose of comparison, on the surfaces of the tool bases α to γ and the tool base δ, an ordinary CVD apparatus was used, and the conditions shown in Tables 2 and 3 were used in the same manner as in Comparative Examples 1 to 15. Comparative coated tools 16-30 shown in 9 were produced. In addition, about the comparison coating tools 21-30, the bonding layer shown in Table 9 was formed by the well-known method before forming a lower layer.

Measure T _α1 , T _α2 , T _β1 , and T _β2 using a scanning electron microscope (magnification 5000 times) for the cross-section of each component layer of the inventive coated tool 16-30 and comparative coated tool 16-30. did.

  Next, in the state where each of the various coated tools is screwed to the tip of the tool steel tool with a fixing jig, the invention coated tools 16 to 30 and the comparative coated tools 16 to 30 are heat resistant alloy, Ni A wet continuous cutting test was performed on the age-hardened material of a -19Cr-19Fe-3Mo-0.9Ti-0.5Al-5.1 (Nb + Ta) alloy, and the flank wear width of the cutting edge was measured in all cases.

Cutting test: Wet continuous cutting of heat-resistant alloy Work material: Round bar of the above heat-resistant alloy Cutting speed: 80 m / min
Cutting depth: 1.2mm
Feed: 0.2mm / rev
Cutting time: 5 minutes Table 10 shows the results of the cutting test.

From the results shown in Tables 6 and 10, in the coated tool of the present invention, the thickness of the upper edge (α) made of α-Al ₂ O _{3 at} the cutting edge ridge line is T _α1 , 500 μm away from the cutting edge ridge line in the rake face direction. When the thickness at the point is T _α2 , T _α1 satisfies 0.0 to 5.0 μm, T _α2 satisfies 1.0 to 20.0 μm, and satisfies T _α1 <T _α2 and is a composite of Ti and Al. the thickness at the cutting edge of the lower layer β a nitride layer or a composite carbonitride layer T _.beta.1, when the thickness at a point distant 500μm the rake face direction from the edge line and _{T β2,} T β1, T β2 1 By satisfying 0.0-20.0 μm, it is excellent in chipping resistance and chipping resistance even when it is used for cutting where the cutting edge is hot like cutting of heat-resistant alloy. Excellent wear resistance It is clear.

  On the other hand, the comparative coated tools 1 to 30 that do not satisfy the invention-specific matters of the present invention are used for high-speed intermittent cutting in which high heat is generated and intermittent and impact high loads act on the cutting edge. It is clear that the life is shortened in a short time due to occurrence of chipping, chipping or the like.

  As described above, the coated tool of the present invention can be used not only for cutting heat-resistant alloy steel, but also as a coated tool for various work materials, and has excellent chipping resistance and wear resistance over a long period of use. Therefore, it can sufficiently satisfy the high performance of the cutting device, the labor saving and energy saving of the cutting work, and the cost reduction.

Claims (4)

A hard coating layer including at least two layers of an upper layer (α) and a lower layer (β) on the surface of a tool base composed of either a WC-based cemented carbide, a TiCN-based cermet, or a cBN-based ultrahigh pressure sintered body In the surface-coated cutting tool in which is formed,
(A) The upper layer (α) comprises an Al ₂ O ₃ layer having an α-type crystal structure,
(B) The lower layer (β) is composed of a composite nitride or composite carbonitride layer of Ti and Al,
(C) The Ti and Al composite nitride or composite carbonitride layer includes at least a crystal layer having a NaCl-type face-centered cubic structure. (D) The thickness of the upper layer (α) at the edge of the cutting edge is T _α1 , When the thickness at a point 500 μm away from the edge of the cutting edge in the rake face direction is T _α2 , T _α1 satisfies 0.0 to 5.0 μm, T _α2 satisfies 1.0 to 20.0 μm, and T _α1 <T satisfies _α2 ,
(E) When the thickness of the lower layer (β) at the cutting edge ridge line is T _β1 and the thickness at a point 500 μm away from the cutting edge ridge line in the rake face direction is T _β2 , T _β1 and T _β2 are 1.0 to 20. A surface-coated cutting tool characterized by satisfying 0 μm and satisfying T _β2 <T _β1 .   The surface-coated cutting tool according to claim 1, wherein the upper layer (α) contains 0.005 to 0.050 atomic% of chlorine. When the average composition of the composite nitride layer or composite carbonitride layer of Ti and Al in the lower layer (β) is expressed as (Ti _1-X Al _X ) (C _Y N _1-Y ), Ti of Al The average content ratio X in the total amount of Al and Al and the average content ratio Y in the total amount of C and N in C (where X and Y are both atomic ratios) are 0.60 ≦ X ≦ 0. 95, 0 ≦ Y ≦ 0.005 is satisfied, The surface-coated cutting tool according to claim 1 or 2.   Between one or two or more Ti compound layers of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer between the tool base and the lower layer (β) The surface-coated cutting tool according to claim 1, wherein a bonding layer having a total average layer thickness of 0.1 to 20.0 μm is present.

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