JP2015066644A - Surface-coated cutting tool with hard coating layer showing excellent wear resistance and chipping resistance in high-speed cutting work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool which is excellent in chipping resistance and wear resistance.SOLUTION: There is provided the surface-coated cutting tool in which a hard coating layer with an average thickness of 1.0 to 10 μm is vapor-deposited on a surface of a tool base constituted of a WC-based alloy. In the surface-coated cutting tool, (a) the hard coating layer includes a compound nitride layer of Al and Ti and the Al content rate with respect to the total amount of Al and Ti in the layer is 0.65 to 0.75 (atomic ratio), and (b) in the range up to the position which is apart by 100 μm from the blade tip on a flank surface, the hard coating layer is lamination or alternative lamination of a thin layer A constituted of a cubic crystal structure only in which the crystal grain size length proportion of fine crystal grains of the grain size less than 0.1 μm is 50 to 90% and a thin layer B constituted of the mixture of a cubic crystal structure and a hexagonal crystal structure in which the proportion is 10 to 50%.

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, for surface-coated cutting tools, inserts that are used to attach and detachably attach to the tip of a cutting tool for turning or planing of various steels and cast irons, drilling of the work materials, etc. Drills and miniature drills, and solid type end mills used for chamfering, grooving, shouldering, etc. of the work material, and the inserts are detachably attached to the solid type end mills. Similarly, an insert-type end mill tool that performs cutting 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 carbon and nitride ((Ti, Al) (C, N)) layer of Ti and Al having a uniform composition is provided on the surface of a tool base) as a hard coating layer.
In addition, the (Ti, Al) (C, N) layer has one or more components selected from a small amount of Si, B, Zr, Y, V, W, Nb, and Mo (hereinafter referred to as M component). A coating tool in which a (Ti, Al, M) (C, N) layer containing and added is vapor-deposited is also known, high temperature hardness and heat resistance by Al of the hard coating layer, high temperature strength by the Ti, In addition, the high temperature oxidation resistance is improved in the state where Ti and Al coexist, and further, heat resistance plastic deformation property, heat conduction depending on the kind of M component added and added such as Si, B, Zr, Y, etc. It is known that characteristics such as heat resistance and high-temperature oxidation resistance are improved, and these coated tools are also known to be used for continuous cutting and intermittent cutting of various general steels and ordinary cast irons (patents) Reference 1).

  In addition, as other coated tools, for example, on the surface of a tool base composed of a WC-based cemented carbide or TiCN-based cermet, an alternating multilayer structure of cubic NbN and hexagonal NbN is formed as a hard coating layer. When the ratio of NbN of hexagonal structure in the entire film is 60 to 85%, the hard coating layer exhibits excellent lubricity and wear resistance when cutting high hardness steel etc. Is also known (see Patent Document 2).

  Furthermore, as another coated tool, for example, in the coated cutting tool in which a hard coating layer in which an A layer made of Cr nitride and a B layer made of TiAl nitride are alternately laminated is formed on a cutting tool base, the A layer is By having at least two types of crystal structures, it is possible to suppress an increase in frictional resistance due to adhesion and welding phenomena with the work material, and to prevent the occurrence of abnormal wear due to film peeling and thermal cracks. It is known that an adhesive film and a hard film excellent in oxidation resistance and abrasion resistance are combined, and as a result, a much longer tool life can be obtained in high-speed cutting (patent document) 3).

  Furthermore, a conventional coated tool as described above, for example, inserts a tool base into an arc ion plating (AIP) apparatus, which is one type of physical vapor deposition apparatus schematically shown in FIG. For example, in order to form a cathode electrode (for example, a (Cr, Al, M) N layer) in which an alloy corresponding to the composition of the hard coating layer is set in a state heated to a temperature of 500 ° C. For example, arc discharge is generated between the M alloy and (Ti-Al alloy) and the anode electrode in order to form an (Al, Ti) N layer under the condition of current: 90 A, and simultaneously reacts in the apparatus. Nitrogen gas is introduced as a gas to form a reaction atmosphere of 2 Pa, for example. On the other hand, a hard coating layer (for example, (( Al, T ) N layer, is also known to be produced by depositing (Cr, Al, M) N layer).

JP 2009-101491 A JP 2012-81548 A Japanese Patent No. 3404003

  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 a (Ti, Al, M) N layer or the like is deposited as a coating layer, there is no particular problem when this is used for cutting under normal conditions of steel or cast iron. When used under high-speed intermittent cutting conditions such as mild steel, stainless steel, high manganese steel, etc. that sometimes generate high heat and have a large impact / mechanical load on the cutting edge, the high temperature strength of the hard coating layer In addition, due to the lack of lubricity, the hard coating layer is prone to chipping, uneven wear, chipping, etc. In addition, a conventional coated tool in which a (Ti, Al) carbonitride layer is vapor-deposited as the hard coating layer In mild steel, Stainless steel, in the high-speed intermittent cutting conditions such as a high manganese steel, because does not wear resistance is satisfactory, in any of the conventional coated tools, at present, leading to a relatively short time service life.

  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) In a conventional coated tool in which the hard coating layer is composed of an (Al, Ti) N layer, Al, which is a component of the hard coating layer, improves high-temperature hardness and heat resistance, and Ti improves high-temperature strength. At the same time, it exhibits the characteristics of improving high-temperature oxidation resistance in a state where Al and Ti coexist.

(B) When the content ratio of Al and Ti in the (Al, Ti) N layer constituting the hard coating layer of the conventional coated tool is expressed by _a composition formula: (Al _a Ti _1-a ) N, the Al content ratio When a is small (for example, 0.65> a), the (Al, Ti) N layer is a cubic (Al, Ti) N layer (hereinafter referred to as an fcc (Al, Ti) N layer). However, if the Al content ratio a is increased, for example, a ≧ 0.75, the crystal structure changes to a crystal structure in which a cubic structure and a hexagonal structure are mixed, and (Al, Ti) N layer (hereinafter referred to as fcc / hcp (Al, Ti) N layer) having a crystal structure in which a cubic structure and a hexagonal structure are mixed has improved lubrication characteristics. The fcc / hcp (Al, Ti) N layer is sufficient compared to the fcc (Al, Ti) N layer. Since the high-temperature hardness is not provided, the fcc / hcp (Al, Ti) N layer is vapor-deposited alone as a hard coating layer to obtain satisfactory wear resistance under high-speed interrupted cutting conditions. What you can't do.

(C) The fcc (Al, Ti) N layer having excellent high-temperature hardness is referred to as thin layer A, and the fcc / hcp (Al, Ti) N layer having excellent lubrication characteristics is referred to as thin layer B. When A and thin layer B are alternately laminated to form a hard coating layer having an alternating laminated structure of thin layer A and thin layer B, thin layer A and thin layer B are hard without harming their properties. Although the coating layer as a whole has excellent lubricity and exhibits predetermined wear resistance, it is especially useful for cutting in severe conditions such as high-speed intermittent cutting in which a large impact and mechanical load is applied to the cutting edge. Since the adhesion strength between the substrate and the hard coating layer is not sufficient, the hard coating layer is liable to be peeled off, chipped or chipped.

(D) As a result of diligent research focusing on the crystal grain sizes of the thin layers A and B constituting the alternate lamination, the crystal grain size of the thin layer A is more relative to the crystal grain size of the thin layer B. Even in severe cutting conditions such as high-speed interrupted cutting where a large impact and mechanical load is applied to the cutting edge, the hard coating layer as a whole has excellent high-temperature strength and excellent lubricity. Show excellent wear resistance for a long time without peeling, chipping or chipping.

(E) When a hard coating layer composed of an (Al, Ti) N layer by the conventional AIP method was formed, a magnetic field was applied between the tool base and the target, and the influence of the magnetic field on the structure of the hard coating layer was investigated. However, by forming the hard coating layer by the AIP method in a magnetic field of a predetermined strength, the grain size, formation region and distribution thereof of the hard coating layer can be adjusted, and the cutting blade Part, that is, a hard coating layer within 100 μm from the ridge line between the flank face and the rake face is formed as a mixed structure of granular crystal grains and fine crystal grains having a predetermined average grain size. It is possible to have a laminated or alternating laminated structure of a thin layer A in which the crystal grain length ratio of fine crystal grains of less than 1 μm is 50 to 90% and a thin layer B that is 10% or more and less than 50%. Hard A coated tool with a coating layer has excellent high-temperature hardness, high-temperature strength, high-temperature oxidation resistance, and excellent lubricity in high-speed intermittent cutting of difficult-to-cut materials such as mild steel, stainless steel, and high-manganese steel. And exhibiting wear resistance.

The present invention has been made based on the above knowledge,
“(1) In a surface-coated cutting tool in which a hard coating layer is formed by vapor deposition on the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) The hard coating layer is composed of a composite nitride layer of Al and Ti having an average layer thickness of 1.0 to 10.0 μm, and Al content in the combined amount of Al and Ti in the composite nitride The ratio is 0.65 to 0.75 (however, atomic ratio),
(B) In the hard coating layer, the ratio of the crystal grain length of fine crystal grains having a grain size of less than 0.1 μm is 50% or more and 90% or less at a position within 100 μm from the intersecting ridge line portion of the flank and rake face. A thin layer A and a thin layer B having a crystal grain length ratio of fine crystal grains with a grain size of less than 0.1 μm of 10% or more and less than 50%, The surface is composed of a thin layer B,
(C) The crystal grains constituting the thin layer A have only a cubic crystal structure, and the crystal grains constituting the thin layer B are X-ray diffraction from the (200) plane of the cubic crystal lattice. The ratio value I (f) / I (h) of the peak intensity I (f) of the 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. A surface-coated cutting tool characterized in that a cubic crystal structure and a hexagonal crystal structure satisfying ≦ I (f) / I (h) ≦ 2.0 are mixed.
(2) The average layer thickness of the thin layer A and the thin layer B is 0.5 to 5.0 μm, respectively, at a position within 100 μm from the intersecting ridge line portion of the flank and rake face ( The surface-coated cutting tool according to 1).
(3) The total number of the thin layers A and B is 2 to 20 layers at a position within 100 μm from the intersecting ridge line portion of the flank and the rake face (1) or (2 ) Surface-coated cutting tool.
(4) The ratio of the total average layer thickness of the thin layer A to the average layer thickness of the hard coating layer is 50 to 70% at a position within 100 μm from the intersecting ridge line portion of the flank and rake face. The surface-coated cutting tool according to any one of (1) to (3). "
It has the characteristics.

Next, the hard coating layer of the coated tool of the present invention will be described in more detail.
The hard coating layer of the coated tool of the present invention is formed by vapor deposition on the surface of a tool substrate made of an ultra-hard tool material, that is, a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet, and has a composition formula: (Al _a Ti _{1-1 a} ) Thin layer A composed of only a cubic crystal structure having an average layer thickness of 0.5 to 5.0 μm composed of a component system of N (a = 0.65 to 0.75) and a composition formula: (Al _a Ti _{1 1 − a} ) From the thin layer B in which a cubic crystal structure having an average layer thickness of 0.5 to 5.0 μm and a hexagonal crystal structure are mixed, which is composed of a component system of N (a = 0.65 to 0.75) The main component is a composite nitride layer having a single layer or an alternately laminated structure.
Furthermore, it was found that the hard coating layer exhibits extremely good cutting performance when it has the following structure.
Further, this hard coating layer exhibits excellent characteristics even when the composite nitride layer alone is used, but by further forming a predetermined lower layer between the composite nitride layer and the tool base, The cutting performance can be further improved.

(A) Composition of hard coating layer:
Hard layer of the present invention, the composition _{formula: (Al a Ti 1-a} ) N (a = 0.65~0.75) composed of a composite nitride layer of Al and Ti consisting of component systems.
Here, when the Al content ratio a in the total amount of Al and Ti is less than 0.65, the oxidation resistance deteriorates due to the effect of Ti, which is not preferable. On the other hand, if it exceeds 0.75, the hardness decreases, so the wear resistance is deteriorated. Therefore, the Al content ratio a in the total amount of Al and Ti is set to 0.65 to 0.75.

(A) Crystal grains constituting the thin layer A:
The thin layer A can improve chipping resistance and wear resistance by containing fine crystal grains having a grain size of less than 0.1 μm. However, if the ratio of the crystal grain length is less than 50%, the crystal grains are coarsened and the grain boundaries are reduced, so that the chipping resistance is lowered. On the other hand, if it exceeds 90%, the hardness is extremely lowered, so that the wear resistance is lowered. Therefore, the ratio of the crystal grain length of fine crystal grains having a grain size of less than 0.1 μm contained in the thin layer A is determined to be 50 to 90%.

(C) Crystal grains constituting the thin layer B:
The thin layer B can improve chipping resistance and wear resistance by containing fine crystal grains having a grain size of less than 0.1 μm. However, if the ratio of the crystal grain length is less than 10%, the compressive residual stress increases, so that chipping is likely to occur. On the other hand, if it exceeds 50%, the hardness decreases, so the wear resistance decreases. Therefore, the ratio of the crystal grain length of fine crystal grains having a grain size of less than 0.1 μm contained in the thin layer B is determined to be 10 to 50%.

(D) Crystal structure of thin layer B:
Since the thin layer B has both a cubic crystal structure and a hexagonal crystal structure, the cutting performance during high-speed cutting is improved. However, the peak intensity I (f) of the X-ray diffraction intensity (XRD) from the (200) plane of the cubic crystal lattice and the peak intensity of the X-ray diffraction intensity (XRD) from the (100) plane of the hexagonal crystal lattice. If the ratio value I (f) / I (h) of I (h) is 0.1 or less, it is not preferable because only the crystal grains having a cubic structure are formed and the lubricity during high-speed cutting is reduced. On the other hand, if it exceeds 2.0, the number of crystal grains having hexagonal crystals that are inferior in hardness compared to cubic crystals increases, so that the hardness decreases and the wear resistance deteriorates. Therefore, the peak intensity I (f) of the X-ray diffraction intensity (XRD) from the (200) plane of the cubic crystal lattice and the peak intensity of the X-ray diffraction intensity (XRD) from the (100) plane of the hexagonal crystal lattice. The ratio value I (f) / I (h) of I (h) was determined to be 0.1 to 2.0.
Since the thin layer A composed of the fcc (Ti, Al) N layer and the thin layer B composed of the fcc / hcp (Ti, Al) N layer are the same or similar hard coating layers, different component systems are used. Compared to the alternate lamination of thin layer A and thin layer B, the adhesion strength between thin layer A and thin layer B is also large, which not only contributes to improving the high temperature strength of the hard coating layer as a whole, but also delamination There is no fear of the occurrence.

(E) Average thickness of hard coating layer, thin layer A, and thin layer B:
If the average thickness of one layer is less than 0.5 μm, the thin layer A cannot sufficiently exhibit its excellent wear resistance over a long period of time, which causes a short tool life, while 5.0 μm If it exceeds, chipping is likely to occur. Therefore, it is necessary that the average layer thickness be 0.5 to 5.0 μm.
In addition, for the thin layer B, if the average layer thickness of one layer is less than 0.5 μm, the excellent wear resistance of itself cannot be sufficiently exhibited over a long period of time, causing a short tool life, If it exceeds 5.0 μm, chipping is likely to occur. Therefore, it is necessary that the average layer thickness be 0.5 to 5.0 μm.
Furthermore, with regard to the laminate formed by alternately laminating the thin layers A and the thin layers B or the alternate laminate, the total average layer thickness, that is, the average layer thickness of the hard coating layer is less than 1.0 μm, it was tangled. Lubricity and excellent wear resistance cannot be exhibited over a long period of time, which is not preferable. On the other hand, if it exceeds 10.0 μm, chipping tends to occur, which is not preferable. Therefore, it is necessary to make the average layer thickness 1.0 to 10.0 μm. By calculating the total number of thin layers A and B from this average layer thickness, the total number of layers is preferably 2 to 20. When the ratio of the thin layer A to the total average layer thickness is 70% or more, the wear resistance effect of the thin layer B cannot be exhibited, and when it is 50% or less, chipping is likely to occur. Therefore, the ratio of the thin layer A to the total layer thickness is preferably 50 to 70%.

(F) Lower layer The hard coating layer in the present invention is composed of a composite nitride layer of Al and Ti having the laminated or alternating laminated structure of the thin layers A and B as described above. As described above, this hard coating layer is a layer having excellent lubricity and excellent wear resistance, but is a composite nitride having such a laminated or alternating laminated structure directly on the surface of the tool substrate. The coated tool with the layer formed by vapor deposition is particularly difficult to cut with severe conditions such as high-speed interrupted cutting, where a large impact and mechanical load is applied to the cutting edge, especially with the tool base and the composite nitride layer consisting of laminated or alternating laminated structures. It is pointed out that peeling is likely to occur because the adhesion strength between them is not sufficient.
Therefore, as an embodiment of the present invention, in addition to the above-described configuration, for example, when a (Ti, Al) -based carbonitride layer having an excellent high-temperature strength is formed as a lower layer, (Ti In addition to having excellent high-temperature strength, the (Ti, Al) -based carbonitride layer is suitable for either a composite nitride layer having a laminated structure or an alternating laminated structure with a tool base. A coated tool having a hard coating layer in which a (Ti, Al) -based carbonitride layer is deposited as a lower layer between a tool base and a composite nitride layer is accompanied by high heat generation because it has excellent high adhesion. At the same time, even when used for high-speed interrupted machining such as stainless steel that is subjected to large intermittent and mechanical loads, the hard coating layer as a whole has excellent high-temperature strength and excellent lubricity, exfoliation, Defect, chipping To exert over the wear resistance excellent without causing long term, more preferred.

  In the coated tool of the present invention, the hard coating layer is a laminated or alternating laminated structure of at least a thin layer A composed of an fcc (Ti, Al) N layer and a thin layer B composed of an fcc / hcp (Ti, Al) N layer. In addition to excellent high-temperature hardness, high-temperature strength, and high-temperature oxidation resistance, it also has excellent lubricity, so it is especially mild steel, stainless steel, which generates high heat and is subject to large intermittent and mechanical loads. Even in high-speed intermittent cutting of difficult-to-cut materials such as high manganese steel, the hard coating layer exhibits excellent wear resistance over a long period of time without causing peeling, chipping, chipping, etc. It is huge.

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. The film structure schematic of the hard coating layer of this invention is shown. The calculation method of the ratio of the crystal grain size length of the fine crystal grain with a grain size of less than 0.1 μm is shown.

In the surface-coated cutting tool of the present invention, a hard coating layer formed by vapor deposition on a tool base made of a superhard tool material such as a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet has a composition formula: (Al _a Ti _1-a ) N (a = 0.65 to 0.75) component system having an average layer thickness of 0.5 to 5.0 μm and a composition formula: (Al _a Ti _1-a ) N (a = 0.65 to 0.75), and a composite nitride layer having a laminated or alternating layered structure composed of a thin layer B having an average layer thickness of 0.5 to 5.0 μm comprising the component system The physical layer is a thin layer A in which the ratio of the crystal grain length of fine crystal grains having a grain size of less than 0.1 μm is 50% or more and 90% or less at a position within 100 μm from the intersecting ridge line portion of the flank and rake face. The proportion of crystal grain length of fine crystal grains having a grain size of less than 0.1 μm is 10% or more and 50 And the outermost surface layer is composed of the thin layer B, the crystal grains constituting the thin layer A have only a cubic crystal structure, and The crystal grains constituting the thin layer B are the X-ray diffraction intensity peak intensity I (f) from the (200) plane of the cubic crystal lattice and the X-ray diffraction intensity from the (100) plane of the hexagonal crystal lattice. Cubic crystal structure and hexagonal crystal in which the ratio value I (f) / I (h) of the peak intensity I (h) of the above satisfies 0.1 ≦ I (f) / I (h) ≦ 2.0 If it has a structure unique to the present invention that is mixed with the structure, and has the effect specific to the present invention that can achieve a longer life even in high-speed, strong intermittent cutting, its specific implementation The form of is not particularly limited.

  The peak intensity I (f) of the X-ray diffraction intensity from the (200) plane of the cubic crystal lattice referred to in the present invention appears at 2θ≈44.8 ° when X-ray diffraction by Kα irradiation is performed. X-ray diffraction intensity from the (200) plane, and the peak intensity I (h) of the X-ray diffraction intensity from the (100) plane of the hexagonal crystal lattice is the X-ray diffraction by Kα irradiation. X-ray diffraction intensity from the (200) plane appearing at 2θ≈59.3 °.

  Next, the embodiment of the coated tool of the present invention will be described more specifically based on Example 1.

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 of 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, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to obtain 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 was 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, a Ti cathode electrode for bombard cleaning is formed on one side, and a thin layer A having a predetermined component composition is formed on the other side A target (cathode electrode) made of an Al-Ti alloy and a target (cathode electrode) also made of an Al-Ti alloy for forming a thin layer B having a predetermined composition are arranged opposite to each other with a rotary table interposed therebetween.
(B) First, the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, the inside of the apparatus is heated to 500 ° C. with a heater, and then the direct current of −1000 V is applied to the tool base that rotates while rotating on the rotary table. A bias voltage is applied and a current of 100 A is passed between the Ti cathode electrode and the anode electrode to generate an arc discharge, thereby bombarding the tool substrate surface,
(C) Next, the flow rate of nitrogen gas as a reaction gas introduced into the apparatus is adjusted to make a reaction atmosphere of 2 Pa, and a DC bias voltage of −100 V is applied to a tool base that rotates while rotating on a rotary table. Then, various magnetic fields were applied so that the integrated magnetic force from the center of the surface of the Al-Ti alloy target for forming the thin layer A to the tool base was in the range of 45 to 100 mT × mm, and the Al for forming the thin layer A -A predetermined current in the range of 50 to 100 A is passed between the Ti alloy target and the anode electrode to generate arc discharge to form a thin layer A having a predetermined target layer thickness. The arc discharge is stopped, and instead, a predetermined current in the range of 50 to 100 A is passed between the Al-Ti alloy target for forming the thin layer B and the anode electrode to generate the arc discharge, and the predetermined target layer Thick To form a layer B.

(D) The composition and average layer thickness shown in Table 3 along the layer thickness direction are formed on the surface of the tool base by repeating the formation of the thin layer A and the thin layer B described in (c) a predetermined number of times. The hard coating layer is formed by vapor-depositing a hard coating layer composed of a laminate of the thin layers A and thin layers B or an alternately laminated structure, thereby forming an fcc (Al, Ti) N layer and an fcc / hcp (Al, Ti) N layer The surface-coated cemented carbide inserts (hereinafter referred to as the present invention-coated inserts) 1 to 16 as the surface-coated cutting tool of the present invention each having a laminated structure or an alternating laminated structure are manufactured.

Here, a method of calculating the integrated magnetic force will be described below. The magnetic flux density is measured at intervals of 10 mm on a straight line from the center of the Al—Ti alloy target to the position of the tool base with a magnetic flux density meter. The magnetic flux density is expressed in units of mT (millitesla), and the distance from the target surface to the position of the tool base is expressed in units of mm (millimeters). Furthermore, when the distance from the target surface to the position of the tool base is the horizontal axis and the magnetic flux density is represented by a graph of the vertical axis, a value corresponding to the area is defined as an integrated magnetic force (mT × mm). Here, the position of the tool base is the position closest to the Al—Ti alloy target. The magnetic flux density was measured in a state in which a magnetic field was formed and not discharged in advance under atmospheric pressure.
In the AIP apparatus shown in FIG. 2, when the tool base is closest to the Al—Ti alloy target, it is mounted and supported so that a part or all of the flank and the Al—Ti alloy target surface are horizontal. .

The calculation method of the ratio of the crystal grain size length of fine crystal grains having a grain size of less than 0.1 μm is as follows. A section on the flank side is cut out from the tool base blade edge, and the section is observed with an SEM. FIG. 4 shows an outline of the cross section. In the intermediate region between the boundaries of thin layer A and thin layer B (if the respective thin layer is present on the surface and interface, the intermediate region between the surface and interface and the boundary between thin layers A and B), A straight line is drawn parallel to the surface of the tool substrate, and the distance between crystal grain boundaries on the straight line is defined as the crystal width. The crystal width of the crystal existing in the range of 100 μm width centered at the position 50 μm away from the intersecting ridge line part of the flank and rake face is measured, and the crystal width relative to the sum of the total crystal widths measured is less than 0.1 μm The sum of the crystal widths was defined as “the ratio of the crystal grain length of fine crystal grains having a grain diameter of less than 0.1 μm at a position ranging from the intersecting ridge line portion to 100 μm (length%)”.
The method for calculating the film thickness is described below. As shown in FIG. 4, a flank side cross section is cut out from the tool base blade edge, the cross section is observed with an SEM, and film thicknesses at positions 25 μm, 50 μm and 75 μm away from the intersecting ridge line portion of the flank and rake face are obtained. The average value of the three points was taken as the average film thickness.
The composition of the hard coating layer was calculated from an average value of five points measured using EPMA at a position ranging from the intersecting ridge line portion to 100 μm.

  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 apparatus was charged and an Al—Ti alloy was mounted as a cathode electrode (evaporation source). First, the apparatus was heated to 500 ° C. with a heater while evacuating the apparatus and maintaining a vacuum of 0.1 Pa or less. Thereafter, a DC bias voltage of −1000 V is applied to the tool base, and a current of 100 A is passed between the Al—Ti alloy of the cathode electrode and the anode electrode to generate an arc discharge so that the surface of the tool base is made of Al—Ti. After bombard cleaning with an alloy, nitrogen gas is introduced into the apparatus as a reaction gas to make a reaction atmosphere of 3 Pa, and the bias voltage applied to the tool base is lowered to −100 V, and Al—Ti An arc discharge was generated between the gold cathode electrode and the anode electrode, and the compositions and layer thicknesses shown in Table 4 were formed on the surfaces of the tool bases A-1 to A-10 and B-1 to B-6. By forming a hard coating layer composed of an fcc (Al, Ti) N layer having a single phase / single crystal structure by vapor deposition, comparative surface coated carbide inserts (hereinafter referred to as comparative coated inserts) 1 to 16 are formed. Each was manufactured.

Next, in the state where each of the various coated inserts is screwed with a fixing jig to the tip of the tool steel tool, the present invention inserts 1 to 16 and the comparative coated inserts 1 to 16,
Work material: JIS / SUS316 lengthwise equidistant 4 round grooved round bars,
Cutting speed: 250 m / min. ,
Cutting depth: 2.5mm,
Feed: 0.25 mm / rev. ,
Cutting time: 4 minutes
A dry continuous high-speed cutting test of stainless steel under the conditions (cutting condition A) (normal cutting speed is 150 m / min.),
Work material: JIS / SS400 lengthwise equidistant 4 round bars with flutes,
Cutting speed: 220 m / min. ,
Cutting depth: 3.0mm,
Feed: 0.15 mm / rev. ,
Cutting time: 6 minutes,
Dry continuous high-speed cutting test of mild steel under the conditions (cutting condition B) (normal cutting speed is 180 m / min.),
Work material: JIS · SCMnH2 lengthwise equidistant four round grooved round bars,
Cutting speed: 250 m / min. ,
Cutting depth: 2.0mm,
Feed: 0.25 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 5.

  Next, another embodiment of the coated tool of the present invention will be described based on Example 2.

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 powders were prepared, each of these raw material powders was blended in the composition shown in Table 6, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and then shaped 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 kinds of sintered carbide rod forming bodies for forming a carbide substrate having diameters of 8 mm, 13 mm, and 26 mm were formed, and further, the above three kinds of round rod sintered bodies were ground and shown in Table 6. WC-based cemented carbide with a 4-blade square shape with a cutting blade portion diameter × length of 6 mm × 13 mm, 10 mm × 22 mm, and 20 mm × 45 mm, and a twist angle of 30 degrees. Tool bases (end mills) C-1 to C-8 were manufactured.

  Subsequently, the surfaces of these carbide substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone and dried, and charged into the arc ion plating apparatus shown in FIG. A hard coating is formed by vapor-depositing a composite nitride layer of Al and Ti having the composition shown in Table 7 along the layer thickness direction and a laminated or alternating layered structure with the target layer thickness along the same layer thickness direction as in Example 1. The present invention as a surface-coated cutting tool according to the present invention, wherein the layer has a laminated or alternating laminated structure of a thin layer A composed of an fcc (Al, Ti) N layer and a thin layer B composed of an fcc / hcp (Al, Ti) N layer Surface coated carbide end mills (hereinafter referred to as the present invention coated end mills) 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 depositing a hard coating layer made of an (Al, Ti) N layer having a single-phase / single-crystal structure having the composition and layer thickness shown in Table 8 under the same conditions as in Example 1 above. Thus, comparative surface-coated carbide end mills (hereinafter referred to as comparative coated end mills) 1 to 8 were produced.

Next, of the present invention coated end mills 1 to 8 and comparative coated end mills 1 to 8, the present invention coated carbide end mills 1 to 3 and comparative coated carbide end mills 1 to 3 are:
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS / SS400 plate material,
Cutting speed: 50 m / min. ,
Groove depth (cut): 3 mm
Table feed: 350 mm / min. ,
The dry-type high-speed grooving test of mild steel under the conditions (normal cutting speed is 30 m / min.), And the coated end mills 4 to 6 and the comparative coated end mills 4 to 6 of the present invention,
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS / SUS304 plate material,
Cutting speed: 55 m / min. ,
Groove depth (cut): 4mm,
Table feed: 350 mm / min. ,
A stainless steel dry high-speed grooving test (normal cutting speed is 40 m / min.) Was performed, and the coated end mills 7 and 8 and the comparative coated end mills 7 and 8 were
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS / SCMnH2 plate material,
Cutting speed: 45 m / min. ,
Groove depth (cut): 8mm,
Table feed: 200 mm / min. ,
The high-manganese steel dry high-speed grooving test under the conditions (normal cutting speed is 35 m / min.)
In any of the groove cutting tests described above, 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 7 and 8, respectively.

  Next, another embodiment of the coated tool of the present invention will be described based on Example 3.

  The diameters produced in Example 2 were 8 mm (for forming the carbide substrates C-1 to C-3), 13 mm (for forming the carbide substrates C-4 to C-6), and 26 mm (for the 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. Dimensions of the substrates D-1 to D-3), 8 mm × 22 mm (carbide substrates D-4 to D-6), and 16 mm × 45 mm (carbide substrates D-7 and D-8), and the twist angle thereof 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. Then, under the same conditions as in Example 1, the composite coating layer having the composition and layer thickness shown in Table 9 and the composite nitride layer consisting of alternating layers is formed by vapor deposition, so that the hard coating layer becomes fcc (Al, The present surface-coated carbide drill (hereinafter referred to as the present invention) as a surface-coated cutting tool of the present invention composed of a composite nitride layer composed of laminated or alternating layers of Ti) N layers and fcc / hcp (Al, Ti) N layers. Invented coated drills) 1-8 were produced.

  For the purpose of comparison, the surfaces of the tool bases (drills) D-1 to D-8 are subjected to honing, ultrasonically cleaned in acetone and dried, and the arc ions shown in FIG. A hard coating composed of an (Al, Ti) N layer having a single-phase / single-crystal structure having the composition and layer thickness shown in Table 10 under the same conditions as in Example 1 and charged in the plating apparatus By depositing the layers, comparative surface-coated carbide drills (hereinafter referred to as comparative coated drills) 1 to 8 were produced.

Next, of the present invention coated drills 1-8 and comparative coated 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 / SUS316 plate material,
Cutting speed: 45 m / min. ,
Feed: 0.2 mm / rev. ,
Hole depth: 12mm,
A wet high-speed drilling test of stainless steel under the conditions (normal cutting speed is 25 m / min.), And the inventive coated drills 4-6 and comparative coated drills 4-6 are
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS / SCMnH2 plate material,
Cutting speed: 50 m / min. ,
Feed: 0.3 mm / rev. ,
Hole depth: 25mm,
The high-manganese steel wet high speed drilling cutting test under the conditions (normal cutting speed is 30 m / min.), And the inventive coated drills 7 and 8 and the comparative coated drills 7 and 8 are
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS / SS400 plate material,
Cutting speed: 55 m / min. ,
Feed: 0.15 mm / rev. ,
Hole depth: 50mm,
A high-speed wet drilling test of mild steel under the conditions (normal cutting speed is 35 m / min.),
In any of the wet high-speed drilling tests (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 9 and 10, respectively.

Thin layer A and thin layer B constituting the hard coating layers of the present invention coated inserts 1-16, the present coated end mills 1-8, and the present coated drills 1-8 as the present surface coated cutting tool obtained as a result. The composition of the hard coating layers of comparative coated inserts 1 to 16, comparative coated end mills 1 to 8 and comparative coated carbide drills 1 to 8 as comparative surface coated cutting tools, and transmission electron microscope When measured by the energy dispersive X-ray analysis method used, each showed substantially the same composition as the target composition.
Moreover, when the average layer thickness of each structural layer of the said hard coating layer was measured using the transmission electron microscope, all showed the average value (average value of five places) substantially the same as target layer thickness. .

Further, regarding the (Al, Ti) N layer constituting the thin layer A and thin layer B of the surface-coated cutting tool of the present invention and the (Al, Ti) N layer constituting the hard coating layer of the comparative surface-coated cutting tool, the crystal structure Were determined by X-ray diffraction, and the results are shown in Tables 3, 4, 7-10.
For the (Al, Ti) 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 (f) from the (200) plane of the cubic structure measured by X-ray diffraction. The values I (f) / I (h) of the diffraction peak intensity I (h) from the (100) plane of the hexagonal crystal structure are also shown in Tables 3, 7, and 9.

  From the results shown in Tables 3 to 5 and 7 to 10, the surface-coated cutting tool of the present invention is a composite nitride layer in which the hard coating layer is formed by laminating or alternately laminating thin layers A and B, The composite nitride layer has a high interlayer 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. In addition to improving the adhesion strength of the hard coating layer to the tool base, the hard coating layer as a whole combines these excellent characteristics, resulting in high heat generation and against the cutting edge. High wear resistance even in high-speed intermittent machining of difficult-to-cut materials such as mild steel, stainless steel, and high manganese steel that are subject to large impacts and mechanical loads.・ From (Al, Ti) N layer of single crystal structure It is clear that the coated tool has chipping and chipping at the cutting edge due to insufficient lubricity and high-temperature strength of the hard coating layer, and wear progresses quickly and reaches the service life in a relatively short time. It is.

  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.

Claims (4)

In a surface-coated cutting tool in which a hard coating layer is vapor-deposited on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) The hard coating layer is composed of a composite nitride layer of Al and Ti having an average layer thickness of 1.0 to 10.0 μm, and Al content in the combined amount of Al and Ti in the composite nitride The ratio is 0.65 to 0.75 (however, atomic ratio),
(B) In the hard coating layer, the ratio of the crystal grain length of fine crystal grains having a grain size of less than 0.1 μm is 50% or more and 90% or less at a position within 100 μm from the intersecting ridge line portion of the flank and rake face. A thin layer A and a thin layer B having a crystal grain length ratio of fine crystal grains with a grain size of less than 0.1 μm of 10% or more and less than 50%, The surface is composed of a thin layer B,
(C) The crystal grains constituting the thin layer A have only a cubic crystal structure, and the crystal grains constituting the thin layer B are X-ray diffraction from the (200) plane of the cubic crystal lattice. The ratio value I (f) / I (h) of the peak intensity I (f) of the 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. Cubic crystal structure and hexagonal crystal structure satisfying ≦ I (f) / I (h) ≦ 2.0 are mixed,
A surface-coated cutting tool characterized by that. The average layer thickness of the thin layer A and the thin layer B is 0.5 to 5.0 μm, respectively, at a position within 100 μm from the intersecting ridge line part of the flank and rake face.
The surface-coated cutting tool according to claim 1. The total number of layers of the thin layer A and the thin layer B is 2 to 20 layers at a position within 100 μm from the intersecting ridge line portion of the flank and rake face.
The surface-coated cutting tool according to claim 1, wherein the surface-coated cutting tool is provided. The ratio of the total average layer thickness of the thin layer A to the average layer thickness of the hard coating layer is 50 to 70% at a position within 100 μm from the intersecting ridge line portion of the flank and rake face.
The surface-coated cutting tool according to any one of claims 1 to 3, wherein the surface-coated cutting tool is provided.