JP2008188738A - Surface-coated cutting tool provided with hard coated layer achieving excellent chipping resistance in heavy cutting of hard-to-cut material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool provided with a hard coated layer, which achieves excellent chipping resistance in heavy cutting of a hard-to-cut material. <P>SOLUTION: This surface-coated cutting tool is provided with the hard coated layer constituted by: (a) a lower part layer formed by an N layer having average thickness of 1-5 μm and having varying composition (Cr, Al) in which Al content and Cr content vary continuously between the maximum Al content point and the minimum Al content point along the direction of layer thickness, respectively, or an N layer having varying composition (Cr, Al, M) (wherein, M is one kind or two kinds of additive components selected from among the elements, Si, B, Y, belonging to the 4a, 5a, 6a groups in the periodic table except Cr); and (b) an upper part layer formed by a composition inclined type acid vanadium nitride layer having an oxygen concentration distribution structure having a ratio of oxygen content increasing toward the direction of layer thickness, containing neither oxygen in the lowest face substantially, nor nitrogen in the uppermost surface substantially on a surface of a tool basic body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  This invention has excellent chipping resistance and lubrication with an excellent hard coating layer, especially when cutting difficult-to-cut materials such as stainless steel, high manganese steel, and mild steel under heavy cutting conditions such as high cutting and high feed. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits the properties.

  In general, for coated tools, throwaway inserts that are detachably attached to the tip of the cutting tool for turning and planing of various steel and cast iron materials, drilling of the work material, etc. Drills and miniature drills, and solid type end mills used for chamfering, grooving, shouldering, etc. of the work material, etc. A slow-away end mill tool that performs cutting work in the same manner as an end mill is known.

In addition, as a coated tool, on the surface of a tool base composed of tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) based cermet,
Composition formula: (Cr _1-P Al _P ) N or composition formula: ((Cr _1-Q M _Q ) _1-P Al _P ) N (where M is a periodic table 4a, 5a, 6a excluding Cr 1 or 2 or more kinds of additive components selected from group elements, Si, B, and Y, and P and Q indicate the content ratio of Al component and M component by atomic ratio)
Physical vapor deposition of a hard coating layer composed of a composite nitride layer of Cr and Al or a composite nitride layer of Cr, Al and M (hereinafter collectively referred to as (Cr, Al, M) N) And the (Cr, Al, M) N layer, which is a hard coating layer of the coated tool, has a high-temperature hardness due to Al as a constituent component, a high-temperature strength due to the Cr, The heat resistance is improved by the coexistence of Cr and Al. Furthermore, as the M component, one or two elements selected from the elements of groups 4a, 5a, and 6a of the periodic table excluding Cr, Si, B, and Y When containing more than seeds, the hard coating layer has improved wear resistance, high temperature oxidation resistance, and other characteristics, so it can be used for continuous cutting and intermittent cutting of various general steels and ordinary cast iron. It is also known to show excellent cutting performance when That.

Further, the above-mentioned coated tool, for example, the above-mentioned tool base is loaded into an arc ion plating apparatus which is a kind of physical vapor deposition apparatus shown schematically in FIG. Cr-Al alloy or Cr-Al-M alloy having a predetermined composition corresponding to the target composition of the hard coating layer (hereinafter collectively referred to as Cr-Al-M alloy) Is generated between the cathode electrode (evaporation source) 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, for example, a reaction atmosphere of 2 Pa, for example. On the other hand, a hard coating layer composed of a (Cr, Al, M) N layer of the target composition is applied to the surface of the tool base under the condition that a bias voltage of, for example, −100 V is applied. It is also known to be produced by vapor deposition.
JP 9-41127 A Japanese Patent Laid-Open No. 10-25566 JP 2004-106183 A JP 2004-269985 A Japanese Patent Laying-Open No. 2005-330539 JP 2006-82209 A

  In recent years, the use of FA for cutting devices has been remarkable. On the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting processing. As a result, cutting tools are affected as much as possible by the material type of the work material. There is a tendency to demand a cutting tool that can cut as many grades as possible, but in the above-mentioned conventional coated tools, this is applied to general steel such as low alloy steel and carbon steel, and ductile There is no problem when it is used for cutting of ordinary cast iron such as cast iron and gray cast iron, but it is difficult to cut stainless steel, high manganese steel, and mild steel, etc., which have high chip viscosity and are easy to weld to the tool surface. If cutting of the material (work material) is performed under heavy cutting conditions such as high cutting and high feed that locally apply a high load to the cutting edge, the work material and chips are generated by the heat generated during cutting. Is heated to high temperature As a result, the viscosity increases further, and the adhesiveness and reactivity to the hard coating layer surface further increase. As a result, the occurrence of chipping (slight chipping) at the cutting edge increases rapidly, which is the cause of this. At present, the service life is reached in a relatively short time.

Therefore, the present inventors, from the above viewpoint, especially when cutting difficult-to-cut materials such as stainless steel, high manganese steel and mild steel under heavy cutting conditions such as high cutting and high feed, As a result of conducting research while focusing on the above conventional coated tools in order to develop a coated tool that exhibits excellent chipping resistance with a hard coating layer,
(A) The (Cr, Al, M) N layers constituting the hard coating layers of the conventional coated tool formed using a conventional arc ion plating apparatus as shown in FIG. The structure shown in FIG. 1 (a) is a schematic plan view and FIG. 1 (b) is a schematic front view. Arc ion plating apparatus, that is, a base mounting rotary table is provided at the center of the apparatus, and a Cr-Al-M alloy having a relatively high Al content is provided on one side and the other side is provided with the rotary table interposed therebetween. An arc ion plating apparatus in which a Cr—Al—M alloy having a low Al content is used as a cathode electrode (evaporation source) and is opposed to the central axis on the rotary table of the apparatus at a predetermined distance in the radial direction. A plurality of substrates are attached in a ring shape along the outer periphery of the substrate, and in this state, the atmosphere inside the apparatus is set as a nitrogen atmosphere, the rotary table is rotated, and the thickness of the hard coating layer formed by vapor deposition is made uniform. When the substrate itself rotates, arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides to form a (Cr, Al, M) N layer on the surface of the substrate. In the resultant (Cr, Al, M) N layer, the base body arranged in a ring shape on the rotary table is a cathode electrode of a Cr—Al—M alloy having a relatively high Al content on the one side. When the closest point to the evaporation source), the highest Al content point was formed in the layer, and the substrate was closest to the cathode electrode of the above-mentioned relatively low Al content Cr-Al-M alloy. Al in the layer at the time A low content point is formed, and by rotation of the rotary table, the highest Al content point and the lowest Al content point appear alternately in the layer thickness direction along the layer thickness direction, and the Al highest content point is The lowest Al content point, and the component concentration distribution structure in which the Al content continuously changes from the lowest Al content point to the highest Al content point.

(B) In the (Cr, Al, M) N layer (hereinafter referred to as composition change (Cr, Al, M) N layer) having the repeated continuous change component concentration distribution structure of (a), the above substrate is made of tungsten carbide ( In the following, after specifying a substrate made of a cemented carbide alloy or titanium carbonitride (hereinafter referred to as TiCN) based cermet (hereinafter collectively referred to as a cemented carbide substrate). The ratio of the Al content in the Cr-Al-M alloy that is the cathode electrode (evaporation source) on the side to the total amount of Cr and M is 0.70 to 0.95 in atomic ratio, and the other side The Al content in the Cr—Al—M alloy, which is the cathode electrode (evaporation source), is relatively low, and is also the ratio of the total amount of Cr and M, and the atomic ratio is 0.50 to 0.65. At the same time, the rotating tape on which the carbide substrate is mounted. By controlling the rotational speed of the cable,
The Al highest content point, the composition _{formula: (Cr 1-X Al X} ) N or composition _{formula: ((Cr 1-Z M} Z) 1-X Al X) N ( where, M is the period except for the Cr Table 4a, 5a, 6a group elements, Si, B, Y one or more additive components selected from among them, X represents Al content, Z represents M content Respectively, and the atomic ratio is 0.70 ≦ X ≦ 0.95, 0 <Z ≦ 0.30),
The Al minimum content point is the composition formula: (Cr _1−α Al _α ) N or the composition formula: ((Cr _1−γ M _γ ) _1−α Al _α ) N (where α is the Al content, γ Represents the content ratio of M, and the atomic ratio is 0.50 ≦ α ≦ 0.65, 0 <γ ≦ 0.30),
And the distance in the thickness direction between the adjacent Al highest content point and Al lowest content point adjacent to each other is 0.03 to 0.1 μm,
In the Al highest content point portion, the Al content is relatively high, so the high-temperature hardness is high. On the other hand, in the Al minimum content point portion, the Al content is higher than the Al highest content point portion. Since the Cr content is low and the Cr content is high, the strength becomes relatively higher, and the distance between the Al highest content point and the Al lowest content point is extremely small. While maintaining strength, it also has high temperature hardness and heat resistance, and further, among the elements of the periodic table 4a, 5a, 6a group excluding Cr, Si, B, Y as M component in the layer When one or more additive components selected from the above are contained, wear resistance, high-temperature oxidation resistance, etc. are further improved, and chipping resistance is improved.

(C) The above composition change (Cr, Al, M) N layer is formed as a lower layer with an average layer thickness of 1 to 5 μm, and an upper layer is formed thereon with vanadium oxide (vanadium oxide, depending on the degree of oxidation, Various compound forms such as VO, V ₂ O ₃ and VO ₂ can be used. However, when these layers are collectively referred to as VO), the VO layer has excellent lubricity, and as a result, heat is generated during cutting. Even when the work material (difficult-to-cut material) and its chips are heated at a high temperature, the cutting edge (the rake face and flank face and the cutting edge ridge line where these two surfaces intersect), the work material and the chip Always has excellent lubricity and welding resistance, the adhesiveness and reactivity of the work material and chips to the cutting edge surface are significantly reduced, and the lower layer (Cr, Al, M) N layer should be well protected.

(D) However, when a VO layer is provided directly on the lower layer composed of the composition change (Cr, Al, M) N layer, the composition change (Cr, Al, M) as the lower layer is provided. The adhesion between the N layer and the VO layer as the upper layer is not sufficient, and the high temperature strength of the VO layer itself as the upper layer is not sufficient, so that the adhesion between the lower layer and the upper layer of the hard coating layer is insufficient. Chipping cannot be sufficiently prevented due to insufficient high-temperature strength of the layer.

(E) When the VO layer is provided on the lower layer composed of the composition change (Cr, Al, M) N layer, the surface of the composition change (Cr, Al, M) N layer is substantially Vanadium nitride that does not contain oxygen (hereinafter referred to as VN) is formed by vapor deposition, and the vapor deposition is continued. As the thickness of the upper layer increases, the oxygen content of the vapor deposited layer is gradually increased. When the vapor deposition was performed so that vanadium oxide containing substantially no nitrogen was formed on the upper layer surface, the upper layer was a vanadium oxynitride layer as a whole. In view of the composition change in the layer thickness direction, the composition gradient having an oxygen (nitrogen) concentration distribution in which the oxygen content rate gradually increases along the layer thickness direction of the upper layer, while the nitrogen content rate gradually decreases. The upper layer of the mold is formed.

(F) And the upper layer made of the composition gradient type vanadium oxynitride is vanadium nitride substantially free of oxygen in the vicinity of the lower layer made of the composition change (Cr, Al, M) N layer, The adhesion strength with the lower layer is high, while the surface region of the composition gradient type upper layer is vanadium oxide that does not substantially contain nitrogen, so it has excellent lubricity and generates heat during cutting. (Hard-to-cut material) and its chips are heated at high temperature, ensuring excellent lubricity and welding resistance between the cutting edge and the work material and chips, and the composition graded acid Since the compositional change of oxygen (or nitrogen) along the layer thickness direction of the vanadium nitride layer is continuous, the mechanical and chemical property changes within the layer are also continuous. Discontinuous changes in mechanical and chemical properties occur like structures Therefore, the upper layer composed of the composition-gradient type vanadium oxynitride as a whole has excellent high-temperature strength, and the adhesiveness and reactivity of the work material and chips to the cutting edge surface are significantly reduced. Excellent chipping resistance in heavy cutting of difficult-to-cut materials with high heat generation and local high load on the cutting edge.

(G) The hard coating layer is, for example, an arc ion plating apparatus having a structure shown in a schematic plan view in FIG. 1A and a schematic front view in FIG. A rotary table is provided, a cathode electrode (evaporation source) is provided across the rotary table, and a metal V is disposed on one side as a cathode electrode (evaporation source), and along the rotary table and from the metal V A cathode electrode (evaporation source) of a Cr—Al—M alloy having a relatively high Al content is disposed on one side at a position 90 degrees apart, and a Cr—Al— layer having a relatively low Al content is disposed on the other side. Using a vapor deposition apparatus in which an M alloy is disposed as a cathode electrode (evaporation source) opposite to each other, a plurality of tool bases are ring-shaped along the outer peripheral portion at a predetermined distance in the radial direction from the central axis on the rotary table of the apparatus. In In this state, the rotating table is rotated by setting the atmosphere inside the apparatus as a nitrogen atmosphere, and the tool base itself is rotated for the purpose of uniformizing the thickness of the hard coating layer to be deposited, and firstly opposed to the surface. An arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode of each Cr—Al—M alloy, and a composition change (Cr, Al, M) N layer is formed as a lower layer on the surface of the tool base. After vapor deposition with an average layer thickness of 1-5 μm,
Arc discharge between the cathode electrode (evaporation source) and the anode electrode of the Cr—Al—M alloy is stopped, and then the metal as the cathode electrode (evaporation source) with the atmosphere inside the apparatus kept in a nitrogen gas atmosphere An arc discharge is generated between V and the anode electrode. First, vanadium nitride is deposited and formed.
After that, while the arc discharge between the cathode electrode (evaporation source) and the anode electrode of the metal V is continued, the atmosphere in the apparatus is changed to an oxygen-nitrogen mixed gas atmosphere, and gradually contains oxygen gas as the deposition proceeds. Vapor deposition is continued while increasing the ratio, and a composition gradient type vanadium oxynitride layer is deposited,
When the thickness of the vapor deposition layer approaches the predetermined target layer thickness, the oxygen gas content in the oxygen-nitrogen mixed gas atmosphere is further increased, and the vapor deposition layer is substantially formed on the outermost surface of the target layer thickness of vanadium oxynitride. By forming a vanadium oxide layer that does not contain nitrogen in
A hard coating layer composed of a composition change (Cr, Al, M) N layer as a lower layer and a composition gradient type vanadium oxynitride layer as an upper layer can be formed by vapor deposition.

(H) The coated tool formed by vapor-depositing the hard coating layer composed of the lower layer and the upper layer described above is particularly capable of cutting difficult-to-cut materials such as stainless steel, high manganese steel, and mild steel with high viscosity and adhesion. Even when processing is performed under heavy cutting conditions such as high cutting and high feed with high load, the composition change (Cr, Al, M) N layer as the lower layer has excellent high temperature hardness, heat resistance, and high temperature strength. Or when the layer contains an M component, the wear resistance, high-temperature oxidation resistance, etc. are further improved, and the oxygen content of the upper layer gradually increases along the layer thickness direction. It is composed of a composition-graded vanadium oxynitride layer having an oxygen concentration distribution structure. The upper layer has excellent adhesion to the lower layer and bonding strength, and the work material (difficult to cut) Material) Since it has lubricity and welding resistance, the hard coating layer consisting of such lower layer and upper layer as a whole has excellent lubricity, welding resistance and excellent high-temperature strength, wear resistance, heat resistance, etc. Because it is equipped with the excellent characteristics of, and the heavy cutting will be performed in a state where the adhesiveness and reactivity of the difficult-to-cut material and chips to the cutting blade surface are significantly reduced, The generation of chipping is eliminated and excellent wear resistance is exhibited over a long period of time.
The research results shown in (a) to (h) above were obtained.

This invention was made based on the above research results,
“(1) On the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) The lower layer has an average layer thickness of 1 to 5 μm, and along the layer thickness direction, Al highest content points and Al lowest content points are alternately present at predetermined intervals, and From the Al highest content point to the Al lowest content point, from the Al lowest content point to the Al highest content point has a component concentration distribution structure in which Al and Cr contents continuously change, respectively,
Furthermore, the Al highest content point is the composition formula: (Cr _1-X Al _X ) N (where X represents the content ratio of Al, and the atomic ratio is 0.70 ≦ X ≦ 0.95),
The Al minimum content point is a composition formula: (Cr _1−α Al _α ) N (where α represents the Al content ratio, and is an atomic ratio of 0.50 ≦ α ≦ 0.65),
And a composite nitride layer of Cr and Al in which the interval between the Al highest content point and the Al lowest content point adjacent to each other is 0.03 to 0.1 μm,
(B) As an upper layer, an acid having an average layer thickness of 1 to 5 μm and having an oxygen concentration distribution structure in which the oxygen content increases from the lower layer side of (a) toward the surface in the layer thickness direction. A vanadium oxynitride layer that is substantially free of oxygen at the lowermost surface of the vanadium oxynitride layer and substantially free of nitrogen at the outermost surface of the vanadium oxynitride layer;
A surface-coated cutting tool that exhibits a chipping resistance in which the hard coating layer is excellent in heavy cutting of difficult-to-cut materials, which is formed by forming the hard coating layer configured as described above in (a) and (b).
(2) On the surface of the tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) The lower layer has an average layer thickness of 1 to 5 μm, and along the layer thickness direction, Al highest content points and Al lowest content points are alternately present at predetermined intervals, and From the Al highest content point to the Al lowest content point, from the Al lowest content point to the Al highest content point has a component concentration distribution structure in which Al and Cr contents continuously change, respectively,
Further, the highest Al content point is the composition formula: ((Cr _1−Z M _Z ) _1−X Al _X ) N (where M is an element of groups 4a, 5a and 6a of the periodic table excluding Cr, One or more additive components selected from Si, B, and Y are shown, X is the Al content, Z is the M content, and the atomic ratio is 0.70 ≦ X ≦ 0.95, 0 <Z ≦ 0.30),
The Al minimum content point is the composition formula: ((Cr _1-γ M _γ ) _1-α Al _α ) N (where α represents the Al content rate, γ represents the M content rate, and the atomic ratio, 0.50 ≦ α ≦ 0.65, 0 <γ ≦ 0.30),
And a composite nitride layer of Cr, Al, and M, in which the interval between the Al highest content point and the Al lowest content point adjacent to each other is 0.03 to 0.1 μm,
(B) As an upper layer, an acid having an average layer thickness of 1 to 5 μm and having an oxygen concentration distribution structure in which the oxygen content increases from the lower layer side of (a) toward the surface in the layer thickness direction. A vanadium oxynitride layer that is substantially free of oxygen at the lowermost surface of the vanadium oxynitride layer and substantially free of nitrogen at the outermost surface of the vanadium oxynitride layer;
A surface-coated cutting tool that exhibits a chipping resistance in which the hard coating layer is excellent in heavy cutting of difficult-to-cut materials, which is formed by forming the hard coating layer configured as described above in (a) and (b).
(3) The additive component M is one or more selected from Si, B, and Y, and the hard coating layer is formed by heavy cutting of a difficult-to-cut material according to claim 2. A surface-coated cutting tool with excellent chipping resistance. "
It has the characteristics.

  Next, regarding the constituent layers of the hard coating layer of the coated tool of the present invention, the reason why the numerical values are limited as described above will be described.

A lower layer composed of a composition change (Cr, Al, M) N layer;
(A) Composition of the highest Al content point The composition component of the lower layer (Cr, Al, M) The Al component, which is a constituent component of the N layer, improves the high-temperature hardness of the hard coating layer. It has the effect of improving the high temperature strength and improving the heat resistance by coexistence of Cr and Al. Further, among the M components, elements of the periodic table 4a, 5a, 6a group excluding Cr, Si, B Has the effect of improving the wear resistance of the hard coating layer, and Y has the effect of improving the high temperature oxidation resistance of the hard coating layer, but the ratio of Al at the highest Al content point (X value) ) Exceeds 0.95 in the total amount of Cr and M (atomic ratio), the ratio of Cr becomes too small and the high-temperature strength decreases sharply, and chipping (small chipping) occurs on the cutting edge. On the other hand, the ratio (X value) is also less than 0.70 Then, the proportion of Al becomes too low, and the desired excellent high-temperature hardness and heat resistance cannot be ensured, and the proportion of the Z value indicating the M content in the total amount with Cr ( If the atomic ratio exceeds 0.30, the wear resistance and high-temperature oxidation resistance are improved, but the high-temperature strength required for heavy cutting of difficult-to-cut materials cannot be ensured and chipping occurs. Therefore, the X value is set to 0.70 to 0.95, and the Z value is set to 0.30 or less.

(B) Composition of the lowest Al content point As described above, the highest Al content point is excellent in high-temperature hardness, but on the other hand, the high-temperature strength is inferior. For this purpose, the Al content is relatively high, and the Al minimum content points that have high high-temperature strength are alternately interposed in the thickness direction. Therefore, the Al content (α value) is If the ratio (atomic ratio) in the total amount of Cr and M exceeds 0.65, the desired excellent high-temperature strength cannot be ensured, while the content ratio (α value) is less than 0.50. Since the ratio of Cr is relatively large and the Al minimum content point cannot be provided with a desired high temperature hardness, the α value is set to 0.50 to 0.65, and About the content ratio (γ value) of M component Is a γ value for the same reasons specified to 0.30 as in the Al highest containing point.

(C) Interval between the highest Al content point and the lowest Al content point If the distance is less than 0.03 μm, it is difficult to clearly form each point with the above composition. High temperature characteristics and high temperature strength cannot be ensured, and if the distance exceeds 0.1 μm, each point has a defect, that is, the highest Al content point is insufficient high temperature strength, and the lowest Al content point is high temperature. Insufficient characteristics appear locally in the layer, which makes it easier for chipping to occur at the cutting edge and promotes the progress of wear. Therefore, the interval is set to 0.03 to 0.1 μm. It was.

(D) Average layer thickness If the average layer thickness is less than 1 μm, the desired wear resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 5 μm, chipping tends to occur on the cutting edge. The average layer thickness was determined to be 1 to 5 μm.

A compositionally graded upper layer comprising a vanadium oxynitride layer (VNO layer);
The composition-graded vanadium oxynitride layer (VNO layer) that forms the upper layer of the hard coating layer has different oxygen (nitrogen) content along the layer thickness direction, so its characteristics are also oxygen (nitrogen) content. Vanadium nitride that does not substantially contain oxygen is formed near the surface of the lower layer (the lowermost surface of the upper layer). The adhesion strength is also high. On the other hand, on the surface (near) of the upper layer, the vanadium oxide substantially containing no nitrogen (that is, the N content ratio N / (N + O) in the total amount with O is an atomic ratio). (Less than 0.1 vanadium oxide), it has excellent lubricity and welding resistance, and has extremely low adhesion and reactivity to work materials (hard-to-cut materials) and chips. State where the work material is heated at high temperature during cutting From being maintained without also changes, which is the lower layer (Cr, Y) to protect the N layer from the high temperature heated workpiece and chips, it exerts an action to suppress this chipping occurred.
In the present invention, “the lowermost surface of the vanadium oxynitride layer does not substantially contain oxygen” or “near the surface of the lower layer (the lowermost surface of the upper layer) substantially contains oxygen. `` No vanadium nitride '' means that the oxygen content is measured in a region having a measurement width of 0.1 to 0.2 μm on the upper layer side from the interface between the upper layer and the lower layer in the lowermost region of the upper layer adjacent to the lower layer. When measured, the oxygen content detected in the region (that is, the ratio of O content to the total content with N content (= O / (N + O), where the atomic ratio) is 0.1 or less. In addition, “the vanadium oxynitride layer is substantially free of nitrogen” or “the vanadium oxide substantially free of nitrogen is present on the surface of the upper layer (nearly)” Measured when measuring the oxygen content of the upper layer surface. Oxygen content (i.e., the ratio of O content relative to the total amount of the N content (= O / (N + O), provided that means that atomic ratio) is 0.9 or more.
Also, if the average layer thickness of the upper layer is less than 1 μm, even if the upper layer is provided, improvement in lubricity and welding resistance cannot be expected, while if the average layer thickness exceeds 5 μm and becomes too thick. Since the chipping tends to occur, the average layer thickness is set to 1 to 5 μm.

  In the coated tool of the present invention, the composition change (Cr, Al, M) N layer of the lower layer constituting the hard coating layer has excellent high temperature hardness, heat resistance, high temperature strength, or even better resistance. Since the upper layer composed of the vanadium oxynitride layer of the composition gradient type has excellent lubricity (surface slipperiness), welding resistance, and high temperature strength, it has wear resistance and high temperature oxidation resistance. The hard coating layer as a whole has excellent high-temperature hardness, heat resistance, high-temperature strength, etc., as well as excellent lubricity and welding resistance. Manganese steel and even mild steel such as mild steel are accompanied by a large heat generation, and show excellent chipping resistance even during heavy-duty machining with high load, and exhibit excellent wear resistance over a long period of time. Is.

  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 in 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, and after sintering, tool bases A-1 to A-10 made of WC-based cemented carbide with ISO standard / CNMG120408 chip shape were formed. .

In addition, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, mix these raw material powders into the composition shown in Table 2, wet mix for 24 hours with a ball mill, dry, and press-mold into green compact at 100 MPa pressure Then, the green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, a tool base B made of TiCN-based cermet having an ISO standard / CNMG120408 chip shape was obtained. -1 to B-6 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. Attached along the outer periphery at a predetermined distance in the radial direction from the central axis on the rotary table in the apparatus, and provided with cathode electrodes (evaporation sources) on opposite sides across the rotary table. Has a metal V as a cathode electrode (evaporation source), and has a relatively high Al content on the one side of the position along the rotary table and 90 degrees away from the metal V. The cathode electrode (evaporation source) of the alloy is disposed opposite to the other side as a cathode electrode (evaporation source) of a Cr-Al-M alloy having a relatively low Al content,
(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 an arc discharge is generated by flowing a current of 100 A between the cathode electrode and the anode electrode of each of the Cr—Al—M alloys. -Bombarded with M alloy,
(C) Next, nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 4 Pa, a DC bias voltage of −100 V is applied to the tool base that rotates while rotating on the rotary table, and An arc discharge is generated by passing a current of 120 A between each of the Cr—Al—M alloys of the cathode electrode and the anode electrode, so that Table 3 and Table 4 are formed on the surface of the tool base along the layer thickness direction. The highest Al content point and the lowest Al content point of the target composition shown in FIG. 3 are alternately repeated at the target intervals shown in Tables 3 and 4, and from the highest Al content point to the lowest Al content point, the lowest Al content point. The composition change (Cr, Al, having a component concentration distribution structure in which the Al (Cr) content continuously changes from the content point to the Al maximum content point and having the target layer thicknesses also shown in Tables 3 and 4 M) N Was vapor deposited as the lower layer of the hard coating layer with an average layer thickness of 1 to 5 [mu] m, the stop arc discharge between the cathode electrode (vapor source) and the anode electrode of each Cr-Al-M alloy,
(D) Then, with the atmosphere in the apparatus kept in a nitrogen gas atmosphere, an arc discharge was generated between the metal V as the cathode electrode (evaporation source) and the anode electrode, and first, vanadium nitride was deposited and formed.
(E) Thereafter, the arc atmosphere between the cathode electrode (evaporation source) of the metal V and the anode electrode is continued, the atmosphere in the apparatus is changed to an oxygen-nitrogen mixed gas atmosphere, and gradually, as the deposition proceeds. Vapor deposition is continued while increasing the oxygen gas content ratio, and a composition gradient type vanadium oxynitride layer is deposited,
(F) When the thickness of the vapor deposition layer approaches the predetermined target layer thickness, the oxygen gas content in the oxygen-nitrogen mixed gas atmosphere is further increased, and vapor deposition is performed on the outermost surface of the target layer thickness of vanadium oxynitride. And forming a vanadium oxide layer substantially free of nitrogen (the value of O / (N + O) by the atomic ratio on the layer surface is 0.9 or more), and oxynitriding with the target layer thicknesses shown in Tables 3 and 4 After vapor deposition of the vanadium layer, the arc discharge between the metal V and the anode electrode is stopped,
By the said (a)-(f), this invention surface covering throwaway tip (henceforth this invention coating tip) 1-39 as this invention coating tool was manufactured, respectively.

  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 is charged and a Cr-Al-M alloy having a predetermined composition is attached as a cathode electrode (evaporation source). First, the inside of the device is evacuated and kept at a vacuum of 0.1 Pa or less, and the inside of the device is heated with a heater. After heating to 500 ° C., a DC bias voltage of −1000 V is applied to the tool base, and a current of 100 A is passed between the cathode electrode Cr—Al—M alloy and the anode electrode to generate arc discharge, Thus, the surface of the tool base is bombarded with the Cr—Al—M alloy, 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 base. The voltage is lowered to -100 V to generate an arc discharge between each cathode electrode and anode electrode having the predetermined composition, whereby each of the tool bases A-1 to A-10 and B-1 to B-6 is generated. A surface-coated throwaway tip as a comparative coating tool (by coating a hard coating layer comprising (Cr, Al, M) N layers having the target compositions and target layer thicknesses shown in Tables 5 and 6 on the surface) (Hereinafter referred to as comparative coated chips) 1 to 16 were produced.

Next, with the various coated chips described above, the present coated chips 1 to 32 and the comparative coated chips 1 to 16 are all screwed to the tip of the tool steel tool with a fixing jig.
Work material: JIS · SCMnH1 lengthwise equidistant four round grooved round bars,
Cutting speed: 240 m / min. ,
Cutting depth: 4 mm,
Feed: 0.55 mm / rev. ,
Cutting time: 5 minutes,
Of high manganese steel under the above conditions (cutting condition A), a dry intermittent high cutting test (normal cutting is 1.5 mm),
Work material: JIS / SUS304 round bar,
Cutting speed: 250 m / min. ,
Incision: 2.7 mm,
Feed: 0.52 mm / rev. ,
Cutting time: 10 minutes,
Stainless steel dry continuous high-cut cutting test under normal conditions (cutting condition B) (normal cutting is 1.5 mm),
Work material: JIS-S11C lengthwise equal 4 round grooved round bars,
Cutting speed: 250 m / min. ,
Infeed: 3.6 mm,
Feed: 0.63 mm / rev. ,
Cutting time: 5 minutes,
Was performed in a dry interrupted high feed cutting test (normal feed is 0.25 mm / rev.), And the flank wear width of the cutting edge was measured in any cutting test. . The measurement results are shown in Tables 7 and 8.

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 .8 μm Co powder was prepared, each of these raw material powders was blended in the blending composition shown in Table 9, and then added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and then pressed into a predetermined shape 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 Then, three types of round rod sintered bodies for forming a tool base having diameters of 8 mm, 13 mm, and 26 mm were formed, and further, the three types of round rod sintered bodies were ground by grinding as shown in Table 9. 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.

  Subsequently, the surfaces of these tool bases (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. Under the same conditions as in Example 1, the Al minimum content point and the Al maximum content point of the target composition shown in Table 10 along the layer thickness direction alternately and repeatedly exist at the target interval shown in Table 10, and It has a component concentration distribution structure in which the Al (Cr) content continuously changes from the highest Al content point to the lowest Al content point, from the lowest Al content point to the highest Al content point, and is also shown in Table 10 Change in composition of target layer thickness (Cr, Al, M) The lower layer composed of N layer, and the target layer thickness also shown in Table 10, and the value of O / (N + O) by the atomic ratio on the layer surface is 0 .9 or more composition gradient By depositing form a hard coat layer of the mold Vanadium nitride layer, the present invention present invention surface coating cemented carbide end mills of the coated tool (hereinafter, referred to as the present invention coated end mill) 1-27 were prepared, respectively.

  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. Then, under the same conditions as in Example 1, the hard coating layer composed of the (Cr, Al, M) N layer having the target composition and the target layer thickness shown in Table 12 is vapor-deposited. Surface-coated carbide end mills (hereinafter referred to as comparative coated end mills) 1 to 10 were produced.

Next, with respect to the present invention coated end mills 1 to 27 and comparative coated end mills 1 to 10,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SCMnH1 plate material,
Cutting speed: 65 m / min. ,
Groove depth (cut): 4.8 mm,
Table feed: 260 mm / min,
High-manganese steel dry-type high-grooving groove cutting test under normal conditions (cutting condition D) (normal groove depth is 3 mm),
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Cutting speed: 70 m / min. ,
Groove depth (cut): 4 mm,
Table feed: 250 mm / min,
Stainless steel dry high feed groove cutting test under normal conditions (cutting condition E) (normal table feed is 120 mm / min),
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / S11C plate,
Cutting speed: 60 m / min. ,
Groove depth (cut): 9 mm,
Table feed: 160 mm / min,
Dry high-cut groove cutting test of mild steel under normal conditions (cutting condition F) (normal groove depth is 5 mm),
In each groove cutting test, 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 11 and 12, respectively.

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

  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 condition as in Example 1 above, the lowest Al content point and the highest Al content point of the target composition shown in Table 13 along the layer thickness direction are alternately set at the target interval shown in Table 13. It has a component concentration distribution structure that repeatedly exists and the Al (Cr) content continuously changes from the Al highest content point to the Al lowest content point, from the Al lowest content point to the Al highest content point, and The composition change (Cr, Al, M) N layer of the target layer thickness also shown in Table 13 and the target layer thickness also shown in Table 13 and O / (N + O depending on the atomic ratio on the layer surface) ) Value is 0.9 or more The surface-coated carbide drills (hereinafter referred to as the present invention-coated drills) 1 to 27 as the present invention-coated tools are respectively formed by vapor-depositing a hard coating layer composed of a composition-gradient type vanadium oxynitride layer. 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. A hard coating layer composed of a (Cr, Al, M) N layer having the target composition and target layer thickness shown in Table 15 is formed by vapor deposition under the same conditions as in Example 1 above. Thus, surface coated carbide drills (hereinafter referred to as comparative coated drills) 1 to 10 as comparative coated tools were manufactured, respectively.

Next, about the said invention coated drill 1-27 and the comparative coated drill 1-10,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SCMnH1 plate material,
Cutting speed: 80 m / min. ,
Feed: 0.52 mm / rev,
Hole depth: 10 mm,
Wet high feed drilling test of high manganese steel under the above conditions (cutting condition G) (normal feed is 0.2 mm / rev),
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Cutting speed: 110 m / min. ,
Feed: 0.5 mm / rev,
Hole depth: 10 mm,
Stainless steel wet high feed drilling test under normal conditions (cutting condition H) (normal feed is 0.2 mm / rev),
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / S11C plate,
Cutting speed: 60 m / min. ,
Feed: 0.5 mm / rev,
Hole depth: 7 mm,
Wet high feed drilling test of mild steel under normal conditions (cutting condition I) (normal feed is 0.2 mm / rev),
In each wet high-speed drilling test (using water-soluble cutting oil), the number of drilling processes until the flank wear width of the tip cutting edge surface reached 0.3 mm was measured. The measurement results are shown in Tables 14 and 15, respectively.

As a result, the composition change (Cr, Al, M) constituting the hard coating layers of the present coated chips 1 to 39, the present coated end mills 1 to 27, and the present coated drills 1 to 27 as the present coated tools obtained. ) The composition of the lowest Al content point and the highest Al content point of the N layer (lower layer) was measured by energy dispersive X-ray analysis using a transmission electron microscope. The composition was substantially the same as the highest content point.
Further, the composition of the hard coating layer composed of the (Cr, Al, M) N layers of the comparative coating tips 1 to 16, the comparative coating end mills 1 to 10 and the comparative coating drills 1 to 10 as the comparative coating tool is changed to transmission electron. When measured by an energy dispersive X-ray analysis method using a microscope, each showed substantially the same composition as the target composition.

  Further, for the composition gradient type vanadium oxynitride layer constituting the upper layer of the hard coating layer of the coated tool of the present invention, the area of the lowermost surface of the upper layer is measured by the Auger electron spectroscopic analysis on the cross-section polished surface of the hard coating layer. When the oxygen content was measured at 0.1 to 0.2 μm, the oxygen content detected in the region (that is, the ratio of O content to the total content with N content by atomic ratio (= O / ( N + O)) was 0.1 or less, and it was confirmed that the lowermost surface of the upper layer was composed of substantially vanadium nitride containing no oxygen. When the oxygen content on the outermost surface of the layer was measured, the ratio of O content to the total content with N content by atomic ratio (= O / (N + O)) was 0.9 or more in all cases, and the upper layer The outermost surface of the substrate substantially contains nitrogen. It was confirmed that are formed in the vanadium oxide does not.

  Moreover, when the average layer thickness of each layer which comprises said hard coating layer was cross-sectional measured using the scanning electron microscope, all showed the substantially same average value (average value of five places) as target layer thickness. .

  From the results shown in Tables 7 to 15, the coated tools of the present invention are all heavy cutting conditions such as high cutting and high feed of difficult-to-cut materials such as stainless steel, high manganese steel, and mild steel, which are particularly highly viscous and sticky. Even in the cutting process, the composition change (Cr, Al, M) N layer, which is the lower layer of the hard coating layer, is firmly adhered and bonded to the surface of the tool base, and has excellent high temperature hardness, heat resistance, high temperature strength, Or, in addition to this, the upper layer having a superior wear resistance and high-temperature oxidation resistance and having a composition-gradient type vanadium oxynitride layer provides the strength of the upper layer itself and the bonding strength to the lower layer. As well as being maintained, excellent lubricity and welding resistance between the work material and the chips are secured, so that excellent wear resistance is exhibited over a long period of time without occurrence of chipping. Hard cover In the comparative coated tool in which the layer is composed of a (Cr, Al, M) N layer and does not have a composition-gradient type vanadium oxynitride layer, the work material (difficult to cut) is difficult in heavy cutting of the difficult-to-cut material. It is clear that chipping occurs at the cutting edge and the service life is reached in a relatively short time because the adhesiveness and reactivity between the material) and the chips and the hard coating layer are further increased. .

  As described above, the coated tool of the present invention exhibits excellent chipping resistance not only for cutting of general steel and ordinary cast iron, but particularly for heavy cutting of the above difficult-to-cut materials, and for a long time. Since it shows excellent cutting performance, it can fully satisfactorily cope with the FA of the cutting apparatus, labor saving and energy saving of cutting, and cost reduction.

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

Claims (3)

On the surface of the tool base composed of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
(A) The lower layer has an average layer thickness of 1 to 5 μm, and along the layer thickness direction, Al highest content points and Al lowest content points are alternately present at predetermined intervals, and From the Al highest content point to the Al lowest content point, from the Al lowest content point to the Al highest content point has a component concentration distribution structure in which Al and Cr contents continuously change, respectively,
Furthermore, the Al highest content point is the composition formula: (Cr _1-X Al _X ) N (where X represents the content ratio of Al, and the atomic ratio is 0.70 ≦ X ≦ 0.95),
The Al minimum content point is a composition formula: (Cr _1−α Al _α ) N (where α represents the Al content ratio, and is an atomic ratio of 0.50 ≦ α ≦ 0.65),
And a composite nitride layer of Cr and Al in which the interval between the Al highest content point and the Al lowest content point adjacent to each other is 0.03 to 0.1 μm,
(B) As an upper layer, an acid having an average layer thickness of 1 to 5 μm and having an oxygen concentration distribution structure in which the oxygen content increases from the lower layer side of (a) toward the surface in the layer thickness direction. A vanadium oxynitride layer that is substantially free of oxygen at the lowermost surface of the vanadium oxynitride layer and substantially free of nitrogen at the outermost surface of the vanadium oxynitride layer;
A surface-coated cutting tool that exhibits a chipping resistance in which the hard coating layer is excellent in heavy cutting of difficult-to-cut materials, which is formed by forming the hard coating layer configured as described above in (a) and (b). On the surface of the tool base composed of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
(A) The lower layer has an average layer thickness of 1 to 5 μm, and along the layer thickness direction, Al highest content points and Al lowest content points are alternately present at predetermined intervals, and From the Al highest content point to the Al lowest content point, from the Al lowest content point to the Al highest content point has a component concentration distribution structure in which Al and Cr contents continuously change, respectively,
Further, the highest Al content point is the composition formula: ((Cr _1−Z M _Z ) _1−X Al _X ) N (where M is an element of groups 4a, 5a and 6a of the periodic table excluding Cr, One or more additive components selected from Si, B, and Y are shown, X is the Al content, Z is the M content, and the atomic ratio is 0.70 ≦ X ≦ 0.95, 0 <Z ≦ 0.30),
The Al minimum content point is the composition formula: ((Cr _1-γ M _γ ) _1-α Al _α ) N (where α represents the Al content rate, γ represents the M content rate, and the atomic ratio, 0.50 ≦ α ≦ 0.65, 0 <γ ≦ 0.30),
And a composite nitride layer of Cr, Al, and M, in which the interval between the Al highest content point and the Al lowest content point adjacent to each other is 0.03 to 0.1 μm,
(B) As an upper layer, an acid having an average layer thickness of 1 to 5 μm and having an oxygen concentration distribution structure in which the oxygen content increases from the lower layer side of (a) toward the surface in the layer thickness direction. A vanadium oxynitride layer that is substantially free of oxygen at the lowermost surface of the vanadium oxynitride layer and substantially free of nitrogen at the outermost surface of the vanadium oxynitride layer;
A surface-coated cutting tool that exhibits a chipping resistance in which the hard coating layer is excellent in heavy cutting of difficult-to-cut materials, which is formed by forming the hard coating layer configured as described above in (a) and (b).   The additive component M is one or more selected from Si, B, and Y, wherein the hard coating layer has excellent resistance to hard cutting in heavy cutting of difficult-to-cut materials. Surface coated cutting tool that demonstrates chipping properties.

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