JP2019115955A - Surface-coated cutting tool - Google Patents

Abstract

To provide a surface-coated cutting tool exerting excellent lubricity, deposition resistance and chipping resistance in high-efficiency high-speed cutting process of hard-to-cut materials such as a Ti-based alloy.SOLUTION: There is provided a surface-coated cutting tool in which a below-mentioned hard coating layer is provided on the surface of a tool substrate comprising any one of tungsten carbide-based hard metal, titanium carbonitride-based cermet, cubic boron nitride sintered body and high-speed tool steel. The hard coating layer includes at least a composite nitride layer of Al, Cr, B, W, Mg and S, and when representing the composite nitride by (AlCrBWMgS)N, the nitride satisfies 0.4≤a≤0.85, 0.005≤b≤0.1, 0≤c≤0.1, 0.005≤d≤0.05 and 0.005≤e≤0.05 (here, each of a, b, c, d and e is an atomic ratio).SELECTED DRAWING: None

Description

  The present invention provides excellent lubricity with a hard coating layer in high-efficiency, high-speed cutting of difficult-to-cut materials such as Ti-based alloys and suppresses the occurrence of welding, chipping, etc. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exerts

In general, slow-away tips used as a coated tool to be removably attached to the tip of a cutting tool for turning or planing various work materials such as steel and cast iron, and drilling and cutting of the work material, etc. Known drills and miniature drills used, end mills used for facing and grooving of the work material, shoulder work, etc. Solid hob and pinion cutters used for cutting teeth of the work material and the like are known. There is.
And in order to improve the cutting performance of a coated tool, many proposals have been made conventionally.

For example, as shown in Patent Document 1, a composite nitride of Al and X (a kind of X: Cr, V, Mg), a composite carbide, a composite boride, and a composite carbon on the surface of a cemented carbide or high speed tool steel. Consisting of a nitride, a composite boronitride, a composite carboboride or a composite carbonitride boride, and the composition of Al and X is (Al _1-y X _y ) [wherein X: a kind of 0: Cr, V, Mg 0 < It has been proposed to improve the wear resistance of cutting tools etc. by forming a hard film having the composition shown by y ≦ 0.3], for example, a hard consisting of a composite boronitride of Al and Cr. It is disclosed that the film exhibits excellent wear resistance in cutting of S45C and SKD11.

Further, in Patent Document 2, as a hard film excellent in wear resistance and oxidation resistance, (Al _a , M _b , S i _c , B _d , Cr ₁ -ab _{c d} ) (C _{1- A} hard coating consisting of _e N _e ) has been proposed (where M is W and / or Mo) and 0.25 ≦ a ≦ 0.65, 0.05 ≦ b ≦ 0.35, 0.01 ≦ c + d ≦ 0.2, 0.5 ≦ e ≦ 1 (where a, b, c, d and e are atomic ratios) have been proposed, and in this hard film, W and / or Mo shown as element M Furthermore, by adding Si and / or B, the oxidation resistance can be enhanced and the hardness of the film is improved, so it is excellent in high-speed cutting such as SKD61 (HRC50), SKD11 (HRC60) and cutting of high hardness steel. It is disclosed that it exhibits excellent cutting performance and long life.

  Patent Document 3 discloses a hard film coated on the surface of a tool base in order to realize long life of a coated tool used under severe cutting conditions such as high speed cutting, high feed cutting, and high hardness of a work material. (MaLb) Xc layer (wherein the M component is at least one metal selected from Cr, Al, Ti, Hf, V, Zr, Ta, Mo, W, Y) Represents an element, and L represents at least one additional element selected from Mn, Cu, Ni, Co, B, Si and S, and a, b and c each represent 0.85 ≦ a ≦ 0. .99, 0.01 ≦ b ≦ 0.15, a + b = 1, and 1.00 <c ≦ 1.20 are proposed, and in this coated tool, the crystallite of the hard film is obtained by the addition of the L component. Size of the crystal becomes finer, the stability of the crystal increases, the high temperature hardness becomes higher, and the wear resistance It is disclosed that.

Furthermore, Patent Document 4, on the surface of the substrate made of tool steel and hard metal or the like, at least, the composition _{(Al a Mg b Cr c Me} d B e AX m Si k) α [N u C v O w] A tool provided with a hard layer having β [where, (a + b + c + d + e + m + k) = α, (u + v + w) = β, and (α + β) = 100, 40 ≦ α ≦ 60, Me is a chemical element periodic table,
-Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W;
And at least one element of the chemical element group consisting of
-H, Li, Na, K, Rb, Cs, Fr; and -Be, Ca, Sr, Ba; and-Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt , Cu, Ag, Au, Zn, Cd, Hg, Sc, Y, La, Ac; and-elements of lanthanoid series;
At least one element of the chemical element group consisting of: 0.004 ≦ m <60, and 0.4 ≦ a ≦ 58, and 0.04 ≦ b ≦ 12, and 18 ≦ c ≦ 42, 4 ≦ d ≦ 54, k is at most 24] has been proposed.
And, in particular, in paragraph 0021, the ratio of aluminum (Al) is limited to 0.4 ≦ a ≦ 58, and at the same time the ratio of magnesium (Mg) is limited to 0.04 ≦ b ≦ 12, and chromium (Cr) It is stated that limiting the ratio of to 18 ≦ c ≦ 42 significantly improves the hardness, residual compressive stress, oxidation resistance, and phase stability at temperatures up to 1200 ° C. or more for hard films. There is.

JP-A-9-41127 Unexamined-Japanese-Patent No. 2006-123159 JP 2008-31517 A Patent No. 5419393 gazette

In recent years, FA equipment for cutting equipment has been remarkable, while demands for labor saving, energy saving and cost reduction have been strong. Along with this, cutting processing tends to become faster and more efficient. At the same time, there is a tendency to demand a versatile cutting tool that can cut as many kinds of work materials as possible.
In the conventional coated tools proposed in the above-mentioned Patent Documents 1 to 4, no particular problem occurs if they are used for cutting under normal cutting conditions such as carbon steel and alloy steel, When used for high-efficiency, high-speed cutting of difficult-to-cut materials such as Ti-based alloys, the work material and chips are heated to a high temperature by heat generation during cutting, and the viscosity is increased. Weldability of the tool to the surface of the hard coating layer is further increased, and as a result, the occurrence of welding and chipping at the cutting edge increases sharply, which causes the service life to be reached in a relatively short time. is there.

  Therefore, in the present invention, in high-efficiency, high-speed cutting of difficult-to-cut materials such as Ti-based alloys with high heat generation, the coating suppresses occurrence of welding as well as chipping and exhibits excellent cutting performance over long-term use The purpose is to provide a tool.

From the above viewpoints, the inventors of the present invention have excellent lubricity with an excellent hard coating layer under high-efficiency, high-speed cutting conditions of difficult-to-cut materials such as Ti-based alloys, thereby providing excellent welding resistance and resistance In order to develop a coated tool that exhibits chipping properties, the following findings have been obtained as a result of intensive studies focusing on the component systems that make up the hard coating layer.
A hard coating layer consisting of a composite nitride layer of Al and Cr is provided on the surface of a tool base consisting of tungsten carbide base cemented carbide, titanium carbonitride base cermet, cubic boron nitride sintered body or high speed tool steel etc. Coated tools are well known as coated tools that are excellent in abrasion resistance because they have high temperature hardness and oxidation resistance.
The inventors of the present invention have found that, in a coated tool coated with a hard coating layer composed of a composite nitride layer of Al and Cr, the thermal conductivity is low by enhancing the lubricity of the hard coating layer during cutting, and the tool material Improve the applicability as a cutting tool to difficult-to-cut materials such as Ti-based alloys, which are materials with high chemical affinity with steel, and as a result, welding in high-efficiency cutting of difficult-to-cut materials such as Ti-based alloys It has been found that the occurrence of chipping and the like can be prevented, and a coated tool exhibiting excellent wear resistance can be obtained over a long-term use.

The specific measures for improving the lubricity of the hard coating layer comprising the composite nitride layer of Al and Cr are generally as follows.
First, a hard coating layer is formed particularly when cutting a Ti-based alloy having a low thermal conductivity by incorporating a specific amount of B having a low solid solubility in the Ti-based alloy as a material to be cut as a component of the hard coating layer. When the surface of the hard coating layer is oxidized due to high temperature conditions, lubricity can be imparted to the surface of the hard coating layer.
Also, by containing a specific amount of B and a specific amount of S or a specific amount of W as a hard coating layer constituent component, the lubricity improving effect by the B component when the hard coating layer is in a high temperature state In addition, the lubricity effect is enhanced in a wide temperature range of the hard coating layer from low temperature to high temperature.
In addition, Mg which is a component of the hard coating layer described in the patent document 4 is mainly added as a component for improving the hardness, residual compressive stress, oxidation resistance and phase stability of the hard coating layer. On the other hand, the high heat at the time of cutting increases the coefficient of friction with the Ti-based alloy, which is the material to be cut, and as a result, has the negative effect of reducing welding resistance and chipping resistance. is there. However, in the case of containing S simultaneously with Mg as a constituent of the hard covering layer, or when containing S and W simultaneously with Mg, the increase in the friction coefficient between the hard covering layer and the work material is suppressed, which is favorable. Since the lubricity can be maintained, it is possible to prevent the decrease in welding resistance and chipping resistance.

That is, the coated tool of the present invention contains both B and S as a hard coating layer component, or further contains W as a hard coating layer component, in a hard coating layer consisting of a composite nitride layer of Al and Cr. In this way, by providing excellent lubricity in high-efficiency, high-speed cutting of difficult-to-cut materials such as Ti-based alloys, which have low thermal conductivity and high chemical affinity with the tool material, Weldability and chipping resistance can be improved, and as a result, excellent cutting performance can be exhibited over long-term use.

The present invention was made based on the above findings, and
“(1) Surface-coated cutting in which a hard coating layer is provided on the surface of a tool base consisting of any of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, cubic boron nitride sintered body and high-speed tool steel In the tool
The hard covering layer includes at least a composite nitride layer of Al, Cr, B, W, Mg, and S,
The compound nitride,
Compositional formula: (Al _a Cr _{1-ab c d} B _b W _c Mg _d S _e ) N
0.4 ≦ a ≦ 0.85, 0.005 ≦ b ≦ 0.1, 0 ≦ c ≦ 0.1,
Surface-coated cutting tool characterized by satisfying 0.005 ≦ d ≦ 0.05 and 0.005 ≦ e ≦ 0.05 (where a, b, c, d and e are all atomic ratios) .
(2) the composition _{formula: (Al a Cr 1-a} -b-c-d-e B b W c Mg d S e) the content a of Al in N is a 0.55 ≦ a ≦ 0.68 The surface-coated cutting tool according to the above (1), characterized in that it is satisfied. "
It is characterized by

  The present invention will be described in detail below.

Average layer thickness of the composite nitride layer of Al, Cr, B, W, Mg and S:
The hard coating layer of the present invention is at least a composite nitride of Al, Cr, B, W, Mg, and S (hereinafter, may be represented by "(Al, Cr, B, W, Mg, S) N") Layers, but if the average layer thickness of the (Al, Cr, B, W, Mg, S) N layer is less than 0.5 μm, sufficient wear resistance can not be exhibited over long-term use On the other hand, if the average layer thickness exceeds 10 μm, there is a possibility that abnormal damage such as chipping or defects may occur. Therefore, the average layer thickness of the (Al, Cr, B, W, Mg, S) N layer is 0. It is desirable to be 5 to 10 μm.

Composition of (Al, Cr, B, W, Mg, S) N layer:
The composition of the components constituting the (Al, Cr, B, W, Mg, S) N layer is
Compositional formula: (Al _a Cr _{1-ab c d} B _b W _c Mg _d S _e ) N
When it represents, it is 0.4 <= a <= 0.85 (preferably 0.6 <= a <= 0.8), 0.005 <= b <= 0.1, 0 <= c <= 0.1, 0.005 Although it is necessary to satisfy ≦ d ≦ 0.05 and 0.005 ≦ e ≦ 0.05 (where a, b, c, d and e are all atomic ratios), this is because of the following reasons by.

The Al component, which is the main component of the (Al, Cr, B, W, Mg, S) N layer, has the function of improving the high temperature hardness of the hard coating layer, and in particular, when the Cr component is simultaneously contained. The effect of Cr is to improve the high temperature strength and to improve the heat resistance by the coexistence of Cr and Al.
However, if the content ratio a of the Al component is less than 0.4, the content ratio of Al becomes too small, and the desired excellent high temperature hardness and heat resistance can not be ensured, while the content ratio of the Al component When a exceeds 0.85, the content ratio of Cr becomes too small and the high temperature strength decreases rapidly, and chipping (micro chipping) and the like are easily generated on the cutting edge, and a hexagonal crystal phase is generated. Since the high temperature hardness also decreases, the content ratio a of the Al component is set to 0.4 ≦ a ≦ 0.85.
In order to exhibit excellent wear resistance over long-term use while maintaining welding resistance and chipping resistance, it is preferable to satisfy 0.55 ≦ a ≦ 0.68.

The B component and the S component in the (Al, Cr, B, W, Mg, S) N layer improve the lubricity of the hard coating layer by the generation of high heat during cutting.
However, when the content ratio b of the B component is less than 0.005, the effect of improving the lubricity is not sufficient.
On the other hand, when the content ratio b of the B component exceeds 0.1, it becomes brittle and chipping tends to occur.
If the content d of the Mg component is less than 0.005, the hardness, residual compressive stress, oxidation resistance and phase stability of the hard coating layer can not be improved, while the content d of the Mg component is When it exceeds 0.05, in order to raise the coefficient of friction with Ti alloy which is a work material, chipping resistance falls conversely.
If the content ratio e of the S component is less than 0.005, the decrease in lubricity due to the addition of the Mg component can not be sufficiently compensated, while if the content ratio e of the S component exceeds 0.05, hard coating The layer itself becomes brittle and chipping resistance is reduced.
Therefore, the content ratio b of the B component, the content ratio d of the Mg component, and the content ratio e of the S component are respectively 0.005 ≦ b ≦ 0.1, 0.005 ≦ d ≦ 0.05, and 0.005 ≦ It is assumed that e ≦ 0.05 (wherein a, b, d and e each represent an atomic ratio).

Further, (Al, Cr, B, W, Mg, S) to the N layer, when further containing a W component as a constituent component, Magneli phase _W n _O of lubricating properties at 550 ° C. or higher _{3n- (1)} , and since the magneli phase has a melting point at 680 ° C (see G. Gassner et al. “Surface & Coatings Technology” 201 (2006) 3335-3341), these liquefy due to heat generation during cutting. The lubricity of the hard coating layer surface is improved.
However, when the content ratio c of the W component exceeds 0.1, the hardness of the hard coating layer decreases and the wear resistance decreases, so the content ratio c of the W component is 0 ≦ c ≦ 0.1. I assume.
As described above, by containing a specific amount of B, S, or W, which is a lubricity improving component, in the hard coating layer, high-efficiency, high-speed cutting of difficult-to-cut materials such as Ti-based alloys The hard coating layer surface can be provided with lubricity in a wide temperature range up to a high temperature, and as a result, the welding resistance and chipping resistance of the coated tool can be improved.

  In the (Al, Cr, B, W, Mg, S) N layer, the content ratio (atomic ratio) of the N component to the total amount of the components constituting the layer is 0.50 which is the stoichiometric ratio The present invention is not limited, and a range equivalent to this can be obtained, for example, a range of 0.40 or more and 0.60 or less.

Incidentally, in Patent Document 4 mentioned above (Japanese Patent No. 5419393), when expressed in a hard coating layer (composition formula component composition similar to the present _{invention, (Al a Mg b Cr c} Me d B e AX m Si _k ) α [N _u C _v O _w ] β) is disclosed, but in Patent Document 4, the content ratio of Al is set for the purpose of the hardness, residual compressive stress, oxidation resistance, and phase stability of the layer. The content ratio of Cr is 0.4 to 58, and the content ratio of Cr is 18 to 42. At the same time, the content ratio of Mg is set to 0.04 to 12, but it does not contain the S component which is an essential component in the present invention.
Therefore, in the case of using a coated tool coated with a hard coating layer containing Mg disclosed in Patent Document 4 for high-efficiency, high-speed cutting of difficult-to-cut materials such as Ti-based alloys, The coefficient of friction between magnesium oxide (melting point of about 2850 ° C of MgO) generated by high heat during cutting and titanium oxide (melting point of about 1850 ° C of TiO ₂ ) formed by oxidation of Ti-based alloy which is a work material is large Therefore, not only the lubricity of the hard coating layer can not be improved, but the hard coating layer is damaged by friction and chipping, breakage, peeling and the like are easily generated, so the tool life is rather shortened.
However, by containing the S component so that the content ratio e of the hard coating layer of the present invention satisfies 0.005 ≦ e ≦ 0.05, magnesium sulfide having lubricity is applied to the tool surface at the time of cutting. By being present, generation of frictional heat can be reduced, generation of magnesium oxide and the like can be suppressed, occurrence of damage to the hard coating layer can be prevented by the lubricity of the S component, and tool life can be prolonged.

The (Al, Cr, B, W, Mg, S) N layer of the present invention described above is, for example, an arc ion plating (hereinafter referred to as "AIP") apparatus shown in FIG. 1 which is a kind of physical vapor deposition. It is possible to form a film using
(A) First, inside the AIP device with the tool substrate made of tungsten carbide base cemented carbide, titanium carbonitride base cermet, cubic boron nitride sintered body or high speed tool steel cleaned and dried The rotary table is mounted along the outer circumference at a position radially spaced from the central axis by a predetermined distance.
(B) The inside of the apparatus is heated to 500 ° C. with a heater while exhausting the inside of the apparatus and maintaining the vacuum at 10 ⁻² Pa or less, and then the atmosphere of Ar gas of 0.5 to 2.0 Pa is set, A DC bias voltage of -200 to -1000 V is applied to a tool base rotating on a table while rotating, and the tool base surface is bombarded with argon ions for 5 to 30 minutes.
(C) Then, while maintaining the inside of the apparatus at a vacuum of 10 ⁻² Pa or less, the inside of the apparatus is maintained at a temperature of 620 ° C. to 650 ° C. with a heater. Next, an arc discharge is generated, for example, under the condition of a current of 50 A, between a cathode electrode (evaporation source) made of an Al-Cr-B-W-Mg-S alloy of a predetermined composition and an anode electrode arranged in the device. At the same time, nitrogen gas as a reaction gas is introduced into the apparatus to make a reaction atmosphere of, for example, 3 Pa, while the tool substrate is vapor deposited under a condition where a bias voltage of, for example, -50 V is applied. A (Al, Cr, B, W, Mg, S) N layer of a target composition and a target average layer thickness is formed on the surface of the substrate.
The coated tool of the present invention can be produced by the above steps (a) to (c).

  The coated tool of the present invention is hard when used for high-efficiency, high-speed cutting of difficult-to-cut materials such as Ti-based alloys, which have low thermal conductivity and high chemical affinity with the tool material. Since the (Al, Cr, B, W, Mg, S) N layer of the covering layer has excellent lubricity in a wide temperature range from low temperature to high temperature, it is possible to suppress the occurrence of welding, chipping, etc. As well as being able to exhibit excellent cutting performance over long-term use.

The schematic explanatory drawing of the arc ion plating apparatus which forms the hard coating layer of this invention coated tool into a film is shown, (a) is a top view, (b) shows a side view.

Below, an Example demonstrates the coating tool of this invention concretely.
In the following examples, the case where the coated tool of the present invention is used in milling is described, but the use in turning, drilling, etc. is not excluded at all.
Although the case where WC base cemented carbide is used as the tool base will be described, the same is true even when TiCN base cermet, cubic boron nitride sintered body, and high speed tool steel are used as the tool base. An effect is obtained.

Prepare WC powder, Cr ₃ C ₂ powder and Co powder all having an average particle diameter of 1 to ₃ μm as raw material powders, mix these raw material powders with the composition shown in Table 1, and add wax. Ball mill mixed in acetone for 24 hours, dried under reduced pressure, press-formed into a green compact of a predetermined shape at a pressure of 98 MPa, and press-molded this green compact in a vacuum of 5 Pa at a predetermined temperature in the range of 1370 ° -1470 ° C. It vacuum-sintered on the conditions hold | maintained at temperature for 1 hour, and manufactured the tool base | substrate made from WC base cemented carbide which had the insert shape of ISO standard SEEN1203AFEN after sintering.

(A) The tool base is mounted along the outer peripheral portion at a predetermined distance in the radial direction from the central axis on the rotary table of the AIP device, and Al-Cr-B-W- of the predetermined composition is placed in the AIP device. Place a target (cathode electrode) made of Mg-S alloy,
(B) First, the tool substrate is heated to 500 ° C. with a heater while exhausting the inside of the apparatus and maintaining vacuum, and then a DC bias voltage of -1000 V is applied to the tool substrate rotating while rotating on the rotary table. Bombard the tool substrate surface with argon ions for 5 to 30 minutes,
(C) Next, introduce nitrogen gas as a reaction gas into the apparatus to make the nitrogen pressure shown in Table 2 and maintain the temperature of the tool base rotating while rotating on the rotary table within the temperature range shown in Table 2 Together with the DC bias voltage shown in Table 2 and generating an arc discharge by passing an arc current shown in Table 2 between the Al-Cr-B-W-Mg-S alloy target and the anode electrode By forming a layer of Al, Cr, B, W, Mg, S) N by vapor deposition, a coated tool of the present invention (hereinafter referred to as "the tool of the present invention") 1 to 9 provided with a hard coating layer shown in Table 3 is produced. did.

About the (Al, Cr, B, W, Mg, S) N layer of the present invention tools 1 to 9, the compositional analysis of the cross section of each layer perpendicular to the surface of the tool base is a transmission electron microscope-energy dispersive X-ray spectroscopic analysis (TEM-EDS) was performed.
That is, for the (Al, Cr, B, W, Mg, S) N layer of the present invention tools 1 to 9, in the observation range of 20 μm parallel to the surface of the tool base, 0.01 μm or less of the upper layer Elemental mapping of spatial resolution was performed, and the composition of the coated (Al, Cr, B, W, Mg, S) N layer was measured.
Furthermore, the average layer thickness of the (Al, Cr, B, W, Mg, S) N layer was measured using a scanning electron microscope (SEM).
These measured values are shown in Table 3 respectively.

  Next, for the purpose of comparison, the AIP apparatus is used to deposit on the surface of the tool base in the same manner as in steps (a) to (c) of Example 1 under the conditions shown in Table 4. Comparative coated tools (hereinafter referred to as "comparative tools") 1 to 9 provided with (Al, Cr, B, W, Mg, S) N layers having compositions and target average layer thicknesses shown in Table 5 were produced.

For the comparative tools 1 to 9, the composition analysis of the (Al, Cr, B, W, Mg, S) N layer is performed in the same manner as in Example 1, and the (Al, Cr, B, W, W, The average layer thickness of the Mg, S) N layer was measured.
Table 5 shows these values respectively.

Furthermore, for reference, using the AIP apparatus, a (Al, Cr, B, W, Mg) N layer, which is one component system shown in the above-mentioned Patent Document 4, is formed on the surface of the tool base. The conventional coated tools (hereinafter referred to as "conventional tools") provided with (Al, Cr, B, W, Mg) N layers of the compositions and target average layer thicknesses shown in Table 5 by vapor deposition under the conditions shown in Made.
While analyzing the composition of the (Al, Cr, B, W, Mg) N layer and measuring the average layer thickness of the (Al, Cr, B, W, Mg) N layer in the same manner as in Example 1. did.
Table 5 shows these values respectively.

Next, the tools according to the present invention 1 to 9, the comparative tools 1 to 9 and the conventional tool were subjected to wet face milling, which is a kind of intermittent cutting, and a center cut cutting test to observe the damage state of the cutting edge.
Cutting test: wet face milling, center cut cutting,
Work material: JIS · Ti-6Al-4V alloy (60 types) Block material width 60mm, length 250mm,
Cutter diameter: 85 mm,
Cutting speed: 75 m / min. ,
Cut: 4 mm,
Feeding: 0.2 mm / rev. ,
Cutting time: 18 minutes,
Table 6 shows the results of the cutting test.

From the results shown in Table 6, according to the tools 1 to 9 of the present invention, since the hard coating layer consisting of the (Al, Cr, B, W, Mg, S) N layer has excellent lubricity, the Ti-based alloy is high. In addition to exhibiting excellent welding resistance and chipping resistance in efficiency and high speed cutting, it exhibits excellent cutting performance over long-term use.
On the other hand, the comparative tools 1 to 9 and the conventional tool do not have sufficient lubricity of the hard coating layer, so the occurrence of welding and chipping has a short tool life.

The coated tool of the present invention exhibits high deposition resistance and chipping resistance in high-efficiency and high-speed cutting of difficult-to-cut materials such as Ti-based alloys, and enables prolongation of service life, Of course, it is also possible to use for cutting of other work material and cutting under other conditions.

Claims (2)

In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base consisting of any of tungsten carbide base cemented carbide, titanium carbonitride base cermet, cubic boron nitride sintered body and high speed tool steel,
The hard covering layer includes at least a composite nitride layer of Al, Cr, B, W, Mg, and S,
The compound nitride,
Compositional formula: (Al _a Cr _{1-ab c d} B _b W _c Mg _d S _e ) N
0.4 ≦ a ≦ 0.85, 0.005 ≦ b ≦ 0.1, 0 ≦ c ≦ 0.1,
Surface-coated cutting tool characterized by satisfying 0.005 ≦ d ≦ 0.05 and 0.005 ≦ e ≦ 0.05 (where a, b, c, d and e are all atomic ratios) . The composition _{formula: (Al a Cr 1-a} -b-c-d-e B b W c Mg d S e) the content a of Al in N shall satisfy the 0.55 ≦ a ≦ 0.68 The surface-coated cutting tool according to claim 1, characterized in that