JP2009101490A - Surface-coated cutting tool having hard coating layer exerting excellent lubricity and wear resistance in high-speed cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool having a hard coating layer exerting excellent lubricity and wear resistance in a high-speed continuous cutting. <P>SOLUTION: In this surface-coated cutting tool, the hard coating layer having a lower layer and an upper layer is vapor-deposited on the surface of a tool base formed of a tungsten carbide based sintered alloy or a titanium carbonitride based cermet. The lower layer is formed of a (Ti, Al) compound nitride or a compound carbonitride layer. The upper layer is formed of a (Cr, Al) compound nitride layer. The upper layer is formed in an alternately laminated structure in which thin layers A of cubic structures and thin layers B of cubic structures and hexagonal structures mixed with each other are laminated alternately. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, the hard coating layer has excellent high-temperature hardness, high-temperature strength, and high-temperature oxidation resistance, and also has excellent lubricity. Therefore, it is accompanied by high heat generation, and has a large intermittent and mechanical load. A surface-coated cutting tool that exhibits excellent wear resistance when used in high-speed intermittent cutting of such mild steel, stainless steel, high-manganese steel, etc., and exhibits excellent tool characteristics over a long period of time (hereinafter referred to as coated tool) It is about.

  In general, surface-coated cutting tools include a throw-away tip that is detachably attached to the tip of a cutting tool for turning and planing of various steels and cast irons, and drilling of the work material. There are drills and miniature drills used for processing, etc., and solid type end mills used for chamfering, grooving, shoulder processing, etc. of the work material. A slow-away end mill tool that performs cutting work in the same manner as a type end mill is known.

Conventionally, as one of the coated tools, for example, a substrate composed of tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) based cermet (hereinafter collectively referred to as these) A coated tool is known in which a uniform nitride ((Cr, Al) N) layer of Cr and Al having a uniform composition is provided on the surface of a tool base) as a hard coating layer.
Also known is a coated tool in which the above (Cr, Al) N layer is provided with a composite nitride of (Cr, Al, Si) N) containing Cr and Al and Si containing a small amount of Si. It is known that this coated tool is excellent in fracture resistance and wear resistance.
Furthermore, a coated tool in which the above (Cr, Al) N layer is provided with a composite nitride of (Cr, Al, B) N and Cr and Al and B containing a trace amount of B is also known, This coated tool is known to have excellent welding resistance, oxidation resistance, and wear resistance.

  As other coated tools, for example, a composite nitride ((Ti, Al) N) layer and a composite carbonitride ((Ti, Al) (C, N)) layer of Ti and Al are formed on the tool base surface. Or, in addition to this, a composite nitride layer mainly composed of Ti and Al containing a small amount of Si, B, Y, Zr, V and the like, a composite carbonitride layer (hereinafter collectively referred to as these, (Ti, Al) -based carbonitride layer) is also known, and the above (Ti, Al) -based carbonitride layer has excellent high-temperature strength, fracture resistance, and wear resistance. Is also known.

Furthermore, the above-mentioned various conventional coated tools are loaded with a tool base in an arc ion plating apparatus which is one of physical vapor deposition apparatuses shown schematically in FIG. 2, for example, at a temperature of 500 ° C., for example. In order to form a cathode electrode in which an alloy corresponding to the composition of the hard coating layer is set (for example, to form a (Cr, Al, Si) N layer, a Cr—Al—Si alloy, or ( In order to form a Ti, Al) N layer, an arc discharge is generated between the Ti-Al alloy) and the anode electrode, for example, at a current of 90 A, and simultaneously nitrogen gas is introduced into the apparatus as a reaction gas. Then, for example, a reaction atmosphere of 2 Pa, while a hard coating layer (for example, a (Ti, Al) N layer, for example) is applied to the tool base surface under the condition that a bias voltage of, for example, −100 V is applied to the tool base. (C , Al, Si) N layer) is also known to be produced by depositing.
JP 9-41127 A Japanese Patent No. 3781374 JP 2005-330539 A Japanese Patent No. 2793773 Japanese Patent No. 2793696 JP-A-8-199338

  In recent years, the performance of cutting machines has been remarkable. On the other hand, there are strong demands for labor saving and energy saving and further cost reduction for cutting work. In a conventional coated tool in which (Cr, Al) N layer, (Cr, Al, Si) N layer, (Cr, Al, B) N layer, etc. are deposited as a coating layer, this is the normal condition for steel or cast iron. There are no particular problems when used for cutting, but in particular, mild steel, stainless steel, high manganese steel, etc. that generate high heat during cutting and that have a large impact and mechanical load on the cutting edge. When used under high-speed intermittent cutting conditions, the hard coating layer lacks the high-temperature strength and lubricity, so the hard coating layer is prone to chipping, uneven wear, chipping, etc. (Ti, Al) carbonitride In conventional coated tools that are formed by vapor deposition, wear resistance is not satisfactory under high-speed interrupted cutting conditions such as mild steel, stainless steel, and high manganese steel. At present, the service life is reached.

In view of the above, the present inventors, in particular, have high-temperature hardness, high-temperature strength, high-temperature, excellent hard coating layers, especially in high-speed intermittent cutting of difficult-to-cut materials such as mild steel, stainless steel, and high manganese steel. In order to develop a coated tool that has oxidation resistance and also exhibits excellent lubricity and wear resistance, the following findings were obtained as a result of research conducted focusing on the hard coating layer of the conventional coated tool.
(A) Hard coating layer is (Cr, Al) N layer, (Cr, Al, Si) N layer or (Cr, Al, B) N layer (hereinafter, these are collectively referred to as (Cr, Al) In a conventional coated tool composed of a nitride-based nitride layer), Al, which is a component of the hard coating layer, improves high-temperature hardness and heat resistance, Cr improves high-temperature strength, and Cr and Al coexist. There is an effect of improving high-temperature oxidation resistance in the state, and when Si is added as an additive component, the heat-resistant plastic deformability is improved, and when B is contained, there is an effect of improving thermal conductivity, And a hard coating layer shall exhibit the characteristics of a fracture resistance, welding resistance, oxidation resistance, and abrasion resistance by containing these each component.

(B) By the way, when the content ratio of Cr and Al in the (Cr, Al) -based nitride layer constituting the hard coating layer of the conventional coated tool is expressed by a composition formula: (Cr _1-X Al _X ) N When the Al content ratio X is small (for example, 0.65 ≧ X), the (Cr, Al) -based nitride layer is a cubic structure (Cr, Al) -based nitride layer (hereinafter referred to as fcc (Cr , Al) -based nitride layer), but when the Al content ratio X is increased, for example, X ≧ 0.75, the crystal structure is a mixture of a cubic crystal structure and a hexagonal crystal structure. (Cr, Al) -based nitride layer (hereinafter referred to as fcc / hcp (Cr, Al) -based nitride layer) having a crystal structure in which such a cubic structure and a hexagonal structure are mixed. Is improved in lubrication characteristics, but the fcc / hcp (Cr, A ) -Based nitride layer does not have sufficient high-temperature hardness as compared with the fcc (Cr, Al) -based nitride layer. Therefore, the fcc / hcp (Cr, Al) -based nitride layer is used as the hard coating layer. By vapor deposition alone, satisfactory wear resistance cannot be obtained under high-speed interrupted cutting conditions.

(C) Therefore, the fcc (Cr, Al) nitride layer having excellent high-temperature hardness is used as the thin layer A, and the fcc / hcp (Cr, Al) nitride layer having excellent lubrication characteristics. Is a thin layer B, and the thin layer A and the thin layer B are alternately laminated to form a hard coating layer composed of an alternating laminated structure of the thin layer A and the thin layer B. The hard coating layer as a whole will have excellent lubricity and exhibit the specified wear resistance without harming the characteristics of the high-speed intermittent cutting that imposes a large impact and mechanical load on the cutting edge. In the cutting of conditions, since the adhesion strength between the tool base and the hard coating layer is not sufficient, peeling, chipping and chipping of the hard coating layer are likely to occur.

(D) Therefore, a (Ti, Al) -based carbonitride layer having excellent high-temperature strength is interposed between and formed as a lower layer between the alternately laminated layers of the thin layers A and B and the tool base. The (Ti, Al) -based carbonitride layer itself has excellent high-temperature strength, and further has excellent adhesion to both the tool substrate and the alternate lamination, so that as a hard coating layer, (Ti, A coated tool in which an Al) -based carbonitride layer is deposited as a lower layer and an alternate stack of thin layers A and B is deposited as an upper layer is accompanied by high heat generation and large intermittent and mechanical Even when used for high-speed interrupted cutting of stainless steel, etc. where the load is applied, the hard coating layer as a whole has excellent high-temperature strength and excellent lubricity, and excellent resistance to peeling, chipping and chipping. Abrasion To become able to exert over the period.

This invention was made based on the above research results,
In a surface-coated cutting tool in which a lower layer and an upper layer are vapor-deposited as a hard coating layer on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) The lower layer has a layer thickness of 0.1 to 1.5 μm,
Composition formula: (Ti _1-QR Al _Q M _1R ) (C, N)
0.4 ≦ Q ≦ 0.65, 0 ≦ R ≦ 0.1 (where Q is the Al content by atomic ratio, and R is the total content of component M ₁ by atomic ratio) In addition, the component M ₁ represents one or more elements selected from Si, B, Zr, Y, V, W, Nb, and Mo), and a composite nitride of Ti, Al, and M ₁ Layer or composite carbonitride layer,
(B) The upper layer is a composite nitride layer of Cr and Al, which has a total layer thickness of 1 to 8 μm, and is composed of alternately laminated thin layers A and B each having a single layer thickness of 25 to 100 nm. In addition,
(C) The thin layer A is
Composition formula: (Cr _1-α-β Al _α M _2β ) N
0.25 ≦ α ≦ 0.65, 0 ≦ β ≦ 0.1 (where α is the Al content ratio by atomic ratio, β is the total content ratio of component M ₂ by atomic ratio) In addition, the component M ₂ is a composite nitride layer of Cr, Al, and M ₂ having a cubic structure satisfying one or two elements selected from Si or B)
(D) The thin layer B is
Composition formula: (Cr _1-γ-δ Al _γ M _3δ ) N
0.75 ≦ γ ≦ 0.95, 0 ≦ δ ≦ 0.1 (where γ is the Al content by atomic ratio, and δ is the total content of component M ₃ by atomic ratio) In addition, the component M ₃ represents one or two elements selected from Si or B), and X-rays from the (200) plane of the cubic crystal lattice measured for the thin layer B The ratio value I (f) / I (h) of the peak intensity I (f) of the diffraction intensity and the peak intensity I (h) of the X-ray diffraction intensity from the (100) plane of the hexagonal crystal lattice is 0. It is a composite nitride layer of Cr, Al and M ₃ in which a cubic structure and a hexagonal structure satisfying 1 ≦ I (f) / I (h) ≦ 11.5.
A surface-coated cutting tool characterized by that. "
It has the characteristics.

Next, the hard coating layer of the coated tool of the present invention will be described in more detail.
(A) Upper layer thin layer A
Composite nitride layer of Cr and Al cubic structure constituting the thin layer A (fcc (Cr, Al) N layer) or Cr and Al composite nitride layer of _{M 2 (fcc (Cr, Al} , M 2) N layer) acts as a layer that ensures the wear resistance of the hard coating layer in high-speed intermittent cutting with high heat generation.
As already stated, the composition of the (Cr, Al) N layer or (Cr, Al, M ₂ ) N layer is
Composition formula: (Cr _1-α Al _α ) N, or
Composition formula: (Cr _{1− (α + β)} Al _α M _2β ) N,
When the value of the Al content ratio α is α ≦ 0.65, a layer having a cubic structure (fcc) can be formed, and the wear resistance is maintained by this fcc structure. However, when the value of the Al content ratio α is α <0.25, the Cr content ratio is relatively increased, and even if the crystal structure is fcc, the fcc (Cr, Al) N layer, fcc ( Since the high-temperature hardness of the Cr, Al, M ₂ ) N layer itself tends to decrease sharply and it becomes difficult to ensure the minimum wear resistance required in high-speed interrupted cutting, the thin layer A The content ratio α of Al was determined as 0.25 ≦ α ≦ 0.65.
In addition, the Cr component, which is a constituent component of the fcc (Cr, Al) N layer and the fcc (Cr, Al, M ₂ ) N layer, improves the high-temperature strength of the thin layer A and improves the chipping resistance / In addition to contributing to deficiency, the coexistence with the Al component also contributes to improving high-temperature oxidation resistance.
Furthermore, fcc (Cr, _{Al, M} 2) If as a constituent of the N layer to contain _{M 2} component, the _{M 2} component can be contained one or two elements selected from Si or B, Si component, by improving the thermal plastic deformation resistance, addition, B component by improving the thermal conductivity, both contribute to improvement in wear resistance of the thin layer a, the content of M ₂ component β When the value (total value of Si content and B content) exceeds 0.1, the high temperature strength of the thin layer A decreases, so the content ratio β of the M ₂ component in the thin layer A is 0 ≦ β ≦ It was set as 0.1.

(B) Upper layer thin layer B
The thin layer B is composed of a composite nitride layer of Cr and Al (fcc / hcp (Cr, Al) N layer) of the thin layer B mixed with a cubic structure and a hexagonal structure, or a composite of Cr, Al and M ₃ . The nitride layer (fcc / hcp (Cr, Al, M ₃ ) N layer) is an fcc (Cr, Al) N layer, fcc (Cr, Al, M, M) in high-speed intermittent cutting of difficult-to-cut materials with high heat generation. ₂ ) By complementing the lack of lubricity of the thin layer A composed of the N layer, it acts as a layer that further improves the wear resistance.
fcc / hcp (Cr, Al) N layer, fcc / hcp (Cr, Al , M 3) consist of N layer which is a component of the thin layer B Cr, effects of _{M 3} component, Cr thin layer A, M It is the same as that of ₂ .
However, regarding Al, which is a constituent of the thin layer B, the composition of the fcc / hcp (Cr, Al) N layer and the fcc / hcp (Cr, Al, M ₃ ) N layer is
Composition formula: (Cr _1-γ Al _γ ) N, or
Composition formula: (Cr _{1− (γ + δ)} Al _γ M _3δ ) N,
In the case of
A thin layer B having a crystal structure (fcc / hcp) in which a cubic structure (fcc) and a hexagonal structure (hcp) are mixed is formed by setting the content ratio γ of Al to γ ≧ 0.75. This fcc / hcp structure ensures lubricity under high-speed cutting conditions with high heat generation, but when the Al content ratio γ is γ> 0.95, the relative Cr content ratio Decrease in the high-temperature strength of the fcc / hcp (Cr, Al) N layer and the fcc / hcp (Cr, Al, M ₃ ) N layer, and chipping and defects are likely to occur. The Al content ratio γ was determined to be 0.75 ≦ γ ≦ 0.95.
In addition, a thin layer comprising an fcc / hcp (Cr, Al) N layer and an fcc / hcp (Cr, Al, M ₃ ) N layer with an Al content ratio γ within the range of 0.75 ≦ γ ≦ 0.95. When X-ray diffraction was performed on the layer B, the ratio between the diffraction peak intensity I (f) from the (200) plane of the cubic structure and the diffraction peak intensity I (h) from the (100) plane of the hexagonal structure. The value I (f) / I (h) was 0.1 ≦ I (f) / I (h) ≦ 11.5 as shown in Tables 4, 5, 10, and 13.
In the case of containing the M ₃ component (Si or one or two elements selected from B) as a constituent of the thin layer B, as in the case of the thin layer A, Si component, a heat plastic deformation resistance In addition, the B component contributes to improving the wear resistance of the thin layer B by improving the thermal conductivity. However, while improving the wear resistance of the thin layer B, the high temperature strength of the thin layer B is simultaneously reduced. in order to prevent, as in the case of the thin layer a, the content ratio [delta] of M ₃ component in the thin layer B, it is necessary to be 0 ≦ δ ≦ 0.1.

(C) Alternating lamination of thin layer A and thin layer B If the single layer thickness is less than 25 nm (0.025 μm), the thin layer A can sufficiently exhibit its excellent wear resistance over a long period of time. However, when the layer thickness exceeds 100 nm (0.1 μm), chipping is likely to occur. Therefore, the layer thickness is 25-100 nm (0.025-0. 1 μm).
Further, for the thin layer B, if the layer thickness is less than 25 nm (0.025 μm), the lack of lubricity of the thin layer A cannot be supplemented, while the layer thickness is 100 nm (0.1 μm). If it exceeds, chipping is likely to occur. Therefore, the thickness of one layer is required to be 25 to 100 nm (0.025 to 0.1 μm).
Furthermore, the alternate lamination formed by alternately laminating the thin layer A and the thin layer B, when the total layer thickness is less than 1 μm, exhibits its own excellent lubricity and excellent wear resistance over a long period of time. Therefore, if the total layer thickness exceeds 8 μm, chipping is likely to occur. Therefore, the total layer thickness is set to 1 to 8 μm.
Note that a thin layer A composed of an fcc (Cr, Al) N layer, an fcc (Cr, Al, M ₂ ) N layer, an fcc / hcp (Cr, Al) N layer, and an fcc / hcp (Cr, Al, M _3). ) Since the thin layer B consisting of N layers is the same or a similar hard coating layer of the component system, the thin layer A and the thin layer B are compared with the alternate lamination of the different component system thin layer A and the thin layer B. The adhesion strength between them is also high, contributing not only to the improvement of the high-temperature strength of the entire hard coating layer, but also the possibility of delamination.

(D) Lower layer The upper layer composed of the alternately laminated structure of the thin layer A and the thin layer B is a layer having excellent lubricity and excellent wear resistance as described above. Coated tools with such alternating layers deposited directly on top of each other, especially in severe cutting conditions such as high-speed intermittent cutting in which a large impact / mechanical load is applied to the cutting edge, Since the adhesion strength between the layers is not sufficient, there is a drawback that the upper layer is easily peeled off, but when the (Ti, Al) -based carbonitride layer excellent in high-temperature strength itself is interposed as a lower layer, In addition to the (Ti, Al) -based carbonitride layer having excellent high-temperature strength, the (Ti, Al) -based carbonitride layer has excellent high adhesion to both the tool base and the alternating lamination. Therefore, (Ti, Al) -based carbonitride A coated tool with a hard coating layer deposited as a lower layer between the tool base and alternating phase is a high-speed intermittent cutting process such as stainless steel that is accompanied by high heat generation and a large intermittent and mechanical load. Even when it is used for, the hard coating layer as a whole has excellent high-temperature strength, excellent lubricity, and excellent wear resistance without peeling, chipping or chipping over a long period of time. To come.
Here, the (Ti, Al) carbonitride layer is
Composition formula: (Ti _1-QR Al _Q M _1R ) (C, N)
When the Q value indicating the content ratio of Al is less than 0.4, the high temperature hardness decreases, leading to deterioration of wear resistance, and when the Q value exceeds 0.65, Since a sufficient decrease in Ti content makes it impossible to ensure sufficient high-temperature strength, the Al content ratio Q is determined to be 0.4 ≦ Q ≦ 0.65. In addition, (Ti, Al) -based carbonitride contains M ₁ component (provided that component M ₁ is one or more elements selected from Si, B, Zr, Y, V, W, Nb or Mo) If added is contained are shown), the content ratio R value of M ₁ component exceeds 0.1, the relative decrease of the Ti content or Al content, and high-temperature hardness required for the lower layer Since it is difficult to ensure high-temperature strength in a well-balanced manner, the R value (total content ratio of M ₁ component) was determined as 0 ≦ R ≦ 0.1.
Incidentally, Si component is M ₁ component, heat plastic deformation resistance, B component thermally conductive, Zr component heat plastic deformation resistance, Y component high temperature oxidation resistance, V component lubricity, W component heat dissipation The Nb component improves high-temperature wear resistance, and the Mo component improves welding resistance, both of which contribute to improving the properties of the lower layer.
Also, if the layer thickness of the lower layer is less than 0.1 μm, the effect of improving the adhesion strength between the upper layer composed of alternating layers and the tool substrate cannot be expected. On the other hand, if the layer thickness exceeds 1.5 μm, the thermoplasticity Since uneven wear due to deformation is likely to occur, the thickness of the lower layer is determined to be 0.1 to 1.5 μm.

In the coated tool of the present invention, the upper layer of the hard coating layer includes a thin layer A composed of at least an fcc (Cr, Al) N layer and an fcc (Cr, Al, M ₂ ) N layer, and an fcc / hcp (Cr, Constructed as an alternating layered structure of thin layers B consisting of Al) N layers and fcc / hcp (Cr, Al, M ₃ ) N layers, excellent lubrication in addition to excellent high-temperature hardness, high-temperature strength and high-temperature oxidation resistance Furthermore, the lower layer of the hard coating layer includes a (Ti, Al) N layer, a (Ti, Al) CN layer, a (Ti, Al, M ₁ ) N layer, and a (Ti, Al, M _1). ) It is composed of a (Ti, Al) carbonitride layer such as a CN layer, and has excellent high-temperature strength and excellent adhesion strength. Hard even in high-speed intermittent cutting of difficult-to-cut materials such as stainless steel and high manganese steel Covering layer is peeled, defect, without causing chipping or the like, and exhibits over a superior wear resistance to long term.

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

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders are blended into the composition shown in Table 1, wet mixed by a ball mill for 72 hours, dried, and then pressed into a green compact at a pressure of 100 MPa. Medium, sintered at 1400 ° C for 1 hour, after sintering, WC-based carbide with honing of R: 0.03 on the cutting edge and chip shape of ISO standard CNMG120408 Alloy tool bases A-1 to A-10 were formed.

In addition, as raw material powders, all are TiCN (weight ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and then pressed into a compact at a pressure of 100 MPa. The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour. After sintering, the cutting edge portion was subjected to a honing process of R: 0.03 and ISO standard / CNMG120408. Tool bases B-1 to B-6 made of TiCN-based cermet having the following chip shape were formed.

(A) Next, each of the tool bases A-1 to A-10 and B-1 to B-6 is ultrasonically cleaned in acetone and dried, and then the arc ion plating shown in FIG. Cr-Al for forming a thin layer A having a predetermined composition as a cathode electrode (evaporation source) on one side is mounted along the outer peripheral portion at a predetermined distance in the radial direction from the central axis on the rotary table in the apparatus. (-M ₂ ) alloy, as a cathode electrode (evaporation source) on the other side, Cr-Al (-M ₃ ) alloy for forming a thin layer B, which also has a predetermined component composition, is arranged oppositely across the rotary table, Furthermore, a cathode electrode (evaporation source) made of a Ti—Al (−M ₁ ) alloy for forming a lower layer is disposed at a position 90 ° apart from both of the cathode electrodes (evaporation source).
(B) 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 0.1 Pa or less, and then the tool base that rotates while rotating on the rotary table is −1000 V. A DC bias voltage is applied, and a current of 100 A is passed between the lower layer forming Ti—Al (−M ₁ ) alloy and the anode electrode to generate an arc discharge. Bombarded with (-M ₁ ) alloy,
(C) 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 a DC bias voltage of −100 V is applied to the tool base that rotates while rotating on the rotary table. In this state, a predetermined current in a range of 50 to 100 A is passed between the cathode electrode and the anode electrode of the lower layer forming Ti—Al (−M ₁ ) alloy to generate arc discharge, and the tool A lower layer having a predetermined composition and a predetermined layer thickness shown in Table 3 is formed on the surface of the substrate.
(D) Subsequently, a predetermined current in the range of 50 to 100 A is passed between the cathode electrode and the anode electrode of the Cr—Al (—M ₂ ) alloy for forming the thin layer A to generate arc discharge, A thin layer A having a predetermined layer thickness is formed on the surface of the layer, and after the thin layer A is formed, the arc discharge is stopped. Instead, the cathode and anode of the thin layer B forming Cr—Al (−M ₃ ) alloy Similarly, a predetermined current in the range of 50 to 100 A is passed between the electrodes to generate arc discharge to form a thin layer B having a predetermined thickness, then the arc discharge is stopped, and the thin layer A forming Cr is again formed. -Al (-M ₂₎ and formation of the thin layer a by arc discharge between the cathode electrode and the anode electrode of the alloy, the thin layer B forming Cr-Al (-M ₃₎ arc between the cathode electrode and the anode electrode of the alloy Alternately and repeatedly forming the thin layer B by discharge, Wherein the surface of the tool substrate, by a hard coating layer comprising alternate lamination of the thin layer A and the thin layer B having the composition and layer thicknesses shown in Tables 4 and 5 along the thickness direction formed by evaporation Te,
The hard coating layer is composed of a lower layer composed of a (Ti, Al) -based carbonitride layer, an alternate stack of fcc (Cr, Al, M ₂ ) N layers and fcc / hcp (Cr, Al, M ₃ ) N layers. The present invention surface-coated carbide throwaway tips (hereinafter referred to as the present invention coated carbide tips) 1 to 16 as the surface coated cutting tool of the present invention comprising the upper layer were produced.

For comparison purposes, these tool bases A-1 to A-10 and B-1 to B-6 were ultrasonically cleaned in acetone and dried, respectively, and the arc ion plating shown in FIG. The device was charged and Cr—Al—M ₂ alloy was mounted as a cathode electrode (evaporation source). First, the inside of the device was evacuated and kept at a vacuum of 0.1 Pa or less, and the inside of the device was heated to 500 ° C. with a heater. Then, a DC bias voltage of -1000 V is applied to the tool base, and an arc discharge is generated by applying a current of 100 A between the Cr-Al (-M ₂ ) alloy of the cathode electrode and the anode electrode. It is allowed, with have bombarded cleaned tool substrate surface in the Cr-Al (-M ₂₎ alloy, followed by introduction of nitrogen gas as a reaction gas into the apparatus and reaction atmosphere of 3 Pa, mark on the tool base body The bias voltage to be reduced to -100 V, to generate arc discharge between the cathode electrode and the anode electrode of the Cr-Al (-M ₂₎ alloy, said tool substrate A-1 to A-10 and with B- 1 to B-6 are vapor-deposited with a hard coating layer composed of an fcc (Cr, Al, M ₂ ) N layer having a single-phase / single-crystal structure having the composition and layer thickness shown in Table 6 Thus, comparative surface coated carbide throwaway tips (hereinafter referred to as comparative coated carbide tips) 1 to 16 were produced.

Next, the coated carbide chips 1 to 16 of the present invention and the comparative coated carbide chip 1 are compared with the above-mentioned various coated carbide chips, all of which are screwed to the tip of the tool steel tool with a fixing jig. About ~ 16
Work material: JIS / SS400 lengthwise equidistant 4 round bars with flutes,
Cutting speed: 200 m / min. ,
Cutting depth: 2.5 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 5 minutes,
Dry continuous high speed cutting test of mild steel under the conditions (cutting condition A) (normal cutting speed is 180 m / min.),
Work material: JIS / SUS304 lengthwise equidistant four round grooved round bars,
Cutting speed: 230 m / min. ,
Incision: 2 mm,
Feed: 0.25 mm / rev. ,
Cutting time: 5 minutes,
A dry continuous high-speed cutting test of stainless steel under the conditions (cutting condition B) (normal cutting speed is 150 m / min.),
Work material: JIS / SCMnH12, 4 longitudinally spaced round bars with equal intervals in the length direction,
Cutting speed: 240 m / min. ,
Incision: 2 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 5 minutes,
The dry continuous high-speed cutting test (normal cutting speed is 150 m / min.) Of high manganese steel under the above conditions (cutting condition C), and the flank wear width of the cutting edge was measured in any cutting test. . The measurement results are shown in Table 7.

As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, ZrC of 1.2 μm Powder, 2.3 μm Cr ₃ C ₂ powder, 1.5 μm VC powder, 1.0 μm (Ti, W) C [by mass ratio, TiC / WC = 50/50] powder, and 1 Prepare 8 μm Co powder, mix these raw material powders with the composition shown in Table 8, add wax, ball mill in acetone for 24 hours, dry under reduced pressure, and press at a pressure of 100 MPa. The green compacts were press-molded, and these green compacts were heated to a predetermined temperature in the range of 1370 to 1470 ° C. at a rate of temperature increase of 7 ° C./min in a 6 Pa vacuum atmosphere. After holding at temperature for 1 hour, sintering under furnace cooling conditions Three types of sintered carbide rod-forming bodies for forming a cemented carbide substrate having diameters of 8 mm, 13 mm, and 26 mm were formed, and further, the above three types of round rod sintered bodies were ground and shown in Table 8. In combination, the diameter x length of the cutting edge is 6 mm x 13 mm, 10 mm x 22 mm, and 20 mm x 45 mm, respectively, and each is made of a WC-based cemented carbide with a 4-flute square shape with a twist angle of 30 degrees Tool bases (end mills) C-1 to C-8 were produced.

Then, the surfaces of these carbide substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone and dried, and then charged into the arc ion plating apparatus shown in FIG. By vapor-depositing the composition shown in Table 9 along the layer thickness direction, the lower layer of the layer thickness, and the upper layer composed of the alternating layers of the composition and layer thickness shown in Table 10 along the layer thickness direction under the same conditions as in Example 1. The hard coating layer is composed of a lower layer made of a (Ti, Al) carbonitride layer, an alternating layer of fcc (Cr, Al, M ₂ ) N layer and fcc / hcp (Cr, Al, M ₃ ) N layer. The surface-coated carbide end mills of the present invention (hereinafter referred to as the present invention coated carbide end mills) 1 to 8 as the surface-coated cutting tool of the present invention composed of an upper layer comprising 1 to 8 were produced.

For the purpose of comparison, the surfaces of the tool bases (end mills) C-1 to C-8 are ultrasonically cleaned in acetone and dried, and then mounted on the arc ion plating apparatus shown in FIG. And a hard coating layer comprising a (Cr, Al, M ₂ ) N layer having a single-phase / single-crystal structure having the composition and layer thickness shown in Table 11 under the same conditions as in Example 1 above. By vapor deposition, comparative surface-coated carbide end mills (hereinafter referred to as comparative coated carbide end mills) 1 to 8 were produced.

Next, of the present invention coated carbide end mills 1-8 and comparative coated carbide end mills 1-8,
About this invention coated carbide end mills 1-3 and comparative coated carbide end mills 1-3,
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS / SCMnH2 plate material,
Cutting speed: 50 m / min. ,
Groove depth (cut): 2 mm,
Table feed: 300 mm / min,
The high-manganese steel dry high-speed grooving test under the conditions (normal cutting speed is 30 m / min.)
For the coated carbide end mills 4-6 of the present invention and the comparative coated carbide end mills 4-6,
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS / SS400 plate material,
Cutting speed: 55 m / min. ,
Groove depth (cut): 1.5 mm,
Table feed: 350 mm / min,
A dry high-speed grooving test of mild steel under the conditions (normal cutting speed is 40 m / min.),
For the coated carbide end mills 7 and 8 of the present invention and the comparative coated carbide end mills 7 and 8,
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS / SUS304 plate material,
Cutting speed: 45 m / min. ,
Groove depth (cut): 5 mm,
Table feed: 400 mm / min,
A dry high-speed grooving test of stainless steel under the conditions (normal cutting speed is 35 m / min.),
In any of the above groove cutting tests, the cutting groove length was measured until the flank wear width of the outer peripheral edge of the cutting edge reached 0.1 mm, which is a guide for the service life.
The measurement results are shown in Tables 10 and 11, respectively.

The diameters produced in Example 2 above were 8 mm (for forming carbide substrates C-1 to C-3), 13 mm (for forming carbide substrates C-4 to C-6), and 26 mm (for carbide substrates C-). 7,
3 types of round bar sintered bodies (for C-8 formation) were used, and from these three types of round bar sintered bodies, the diameter x length of the groove forming part was 4 mm x 13 mm (carbide) by grinding. Bases D-1 to D-3), 8 mm × 22 mm (Carbide bases D-4 to D-6), and 16 mm × 45 mm (Carbide bases D-7 and D-8), and the twist angle WC base cemented carbide tool bases (drills) D-1 to D-8 each having a 30-degree two-blade shape were produced.

Next, the cutting edges of these tool bases (drills) D-1 to D-8 are subjected to honing, ultrasonically cleaned in acetone, and dried to the arc ion plating apparatus shown in FIG. In the same conditions as in Example 1 above, by depositing the composition shown in Table 12 and the lower layer of the layer thickness and the composition shown in Table 13 and the upper layer consisting of the alternating lamination of the layer thickness, The hard coating layer is composed of a lower layer composed of a (Ti, Al) -based carbonitride layer, an alternate stack of fcc (Cr, Al, M ₂ ) N layers and fcc / hcp (Cr, Al, M ₃ ) N layers. The surface-coated carbide drills of the present invention (hereinafter referred to as the present invention-coated carbide drills) 1 to 8 as the surface-coated cutting tool of the present invention composed of the upper layer were manufactured.

For the purpose of comparison, the surface of the tool base (drill) D-1 to D-8 is subjected to honing, ultrasonically cleaned in acetone and dried, and the arc ions shown in FIG. From a (Cr, Al, M ₂ ) N layer having a single-phase / single-crystal structure having the composition and layer thickness shown in Table 14 under the same conditions as in Example 1 above. Comparative surface-coated carbide drills (hereinafter referred to as comparative-coated carbide drills) 1 to 8 were produced by vapor-depositing the hard coating layer.

Next, of the present invention coated carbide drills 1-8 and comparative coated carbide drills 1-8,
About this invention coated carbide drills 1-3 and comparative coated carbide drills 1-3,
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS / SUS304 plate material,
Cutting speed: 40 m / min. ,
Feed: 0.25 mm / rev,
Hole depth: 8 mm,
Wet stainless steel under high-speed wet drilling test (normal cutting speed is 25 m / min.)
About this invention coated carbide drills 4-6 and comparative coated carbide drills 4-6,
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS / SCMnH2 plate material,
Cutting speed: 45 m / min. ,
Feed: 0.2 mm / rev,
Hole depth: 25 mm,
A high-speed wet drilling test of high-manganese steel under normal conditions (normal cutting speed is 30 m / min.)
For the coated carbide drills 7 and 8 and the comparative coated carbide drills 7 and 8 of the present invention,
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS / SS400 plate material,
Cutting speed: 50 m / min. ,
Feed: 0.3 mm / rev,
Hole depth: 35 mm,
A high-speed wet drilling test of mild steel under the conditions (normal cutting speed is 35 m / min.),
In any of the above wet high-speed drilling tests (using water-soluble cutting oil), the number of drilling processes until the flank wear width of the cutting edge surface reached 0.3 mm was measured. The measurement results are shown in Tables 13 and 14, respectively.

Lower parts constituting the hard coating layers of the present coated carbide tips 1 to 16, the present coated carbide end mills 1 to 8, and the present coated carbide drills 1 to 8 as the surface coated cutting tool of the present invention obtained as a result. The composition of each of the layer, thin layer A and thin layer B is also compared with comparative coated carbide tips 1-16, comparative coated carbide end mills 1-8 and comparative coated carbide drills 1-8 as comparative surface coated cutting tools. When the composition of the hard coating layer was measured by an energy dispersive X-ray analysis method using a transmission electron microscope, the composition was substantially the same 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.

Furthermore, the thin layer A and the thin layer B of the surface-coated cutting tool of the present invention, the (Cr, Al, M ₂ ) N layer, the (Cr, Al, M ₃ ) N layer of the composition constituting the thin layer B, and the comparative surface-coated cutting tool are hard. Regarding the (Cr, Al, M ₂ ) N layer having the composition constituting the coating layer, the crystal structure of each layer was determined by X-ray diffraction, and the results are shown in Tables 4 to 6, 10, 11, 13, and 14.
For the (Cr, Al, M ₃ ) N layer having the composition constituting the thin layer B of the surface-coated cutting tool of the present invention, the diffraction peak intensity I from the (200) plane of the cubic structure measured by X-ray diffraction is used. The ratio values I (f) / I (h) between (f) and the diffraction peak intensity I (h) from the (100) plane of the hexagonal crystal structure are also shown in Tables 4, 5, 10, and 13. .

From the results shown in Tables 3 to 7 and 9 to 14, the surface-coated cutting tool of the present invention has a hard coating layer consisting of a lower layer and an upper layer of an alternately laminated structure of thin layers A and B. The layer has a high interlaminar adhesion strength, in particular the thin layer A has excellent wear resistance, the thin layer B has excellent lubricity, and the lower layer has excellent high temperature strength and a tool. Since the adhesion strength of the hard coating layer to the substrate is increased, the hard coating layer has these excellent characteristics as a whole, resulting in high heat generation and a large impact on the cutting edge.・ Excellent wear resistance even in high-speed interrupted cutting of difficult-to-cut materials such as mild steel, stainless steel, and high manganese steel that are subjected to mechanical load, while the hard coating layer has a single phase / single crystal structure _(Cr, Al, _M 2) consisting of N layer coated tool In particular, it is clear that chipping and chipping occur at the cutting edge due to insufficient lubricity of the hard coating layer and insufficient high-temperature strength, and that wear progresses faster and reaches the service life in a relatively short time. .

  As described above, the surface-coated cutting tool of the present invention is not only used for cutting under normal cutting conditions such as various types of steel and cast iron, but also generates high heat and has a large impact on the cutting edge.・ Even in high-speed intermittent cutting of difficult-to-cut materials such as mild steel, stainless steel, and high manganese steel that are subjected to mechanical load, they exhibit excellent wear resistance and show excellent cutting performance over a long period of time. It is possible to satisfactorily meet the demands for high performance 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 surface coating cutting 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 a surface-coated cutting tool in which a lower layer and an upper layer are vapor-deposited as a hard coating layer on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
(A) The lower layer has a layer thickness of 0.1 to 1.5 μm,
Composition formula: (Ti _1-QR Al _Q M _1R ) (C, N)
0.4 ≦ Q ≦ 0.65, 0 ≦ R ≦ 0.1 (where Q is the Al content by atomic ratio, and R is the total content of component M ₁ by atomic ratio) In addition, the component M ₁ represents one or more elements selected from Si, B, Zr, Y, V, W, Nb, and Mo), and a composite nitride of Ti, Al, and M ₁ Or composite carbonitride layer,
(B) The upper layer is a composite nitride layer of Cr and Al, which has a total layer thickness of 1 to 8 μm, and is composed of alternately laminated thin layers A and B each having a single layer thickness of 25 to 100 nm. In addition,
(C) The thin layer A is
Composition formula: (Cr _1-α-β Al _α M _2β ) N
0.25 ≦ α ≦ 0.65, 0 ≦ β ≦ 0.1 (where α is the Al content ratio by atomic ratio, β is the total content ratio of component M ₂ by atomic ratio) In addition, the component M ₂ is a composite nitride layer of Cr, Al, and M ₂ having a cubic structure satisfying one or two elements selected from Si or B)
(D) The thin layer B is
Composition formula: (Cr _1-γ-δ Al _γ M _3δ ) N
0.75 ≦ γ ≦ 0.95, 0 ≦ δ ≦ 0.1 (where γ is the Al content by atomic ratio, and δ is the total content of component M ₃ by atomic ratio) In addition, the component M ₃ represents one or two elements selected from Si or B), and (e), further, from the (200) plane of the cubic crystal lattice measured for the thin layer B The ratio value I (f) / I (h) of the peak intensity I (f) of the X-ray diffraction intensity and the peak intensity I (h) of the X-ray diffraction intensity from the (100) plane of the hexagonal crystal lattice is , 0.1 ≦ I (f) / I (h) ≦ 11.5, a mixed nitride layer of Cr, Al, and M ₃ in which a cubic structure and a hexagonal structure are mixed.
A surface-coated cutting tool characterized by that.

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