JP2003200306A - Surface coated cemented carbide cutting tool having hard coating layer showing excellent biting property for material to be cut under heavy cutting condition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cemented carbide cutting tool having a hard coating layer showing excellent biting property for a material to be cut under a heavy cutting condition. <P>SOLUTION: This surface coated cemented carbide cutting tool is made by physically depositing the hard coating layer made of four or more alternate lamination layers of first thin layers and second thin layers having each average layer thickness of 0.2 to 1 μm by whole average layer thickness of 2 to 10 μm on the surface of a tungsten carbide group cemented carbide base body or a titanium carbonitride system cermet. When the first thin layer is shown by a composition formula: (Ti<SB>1-</SB>XAlX)N, the layer is made of a composite nitride layer of Ti and Al satisfying X: 0.30 to 0.70 in an atomic ratio by a measurement by an Auger spectroscopic analyzer in a thickness direction center part. The second thin layer is made of a mixed layer of aluminium oxide phases and titanium carbonitride phases in which the rate of the aluminium oxide phases is 35 to 65 mass% in the rate occupied in total amount with titanium carbonitride phases. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cutting hard materials such as steel and cast iron under heavy cutting conditions such as high cutting and high feed. Since the coating layer shows good biting properties to the work material, as a result, heat generation during cutting is reduced, and wear progress of the cutting edge is significantly suppressed,
The present invention relates to a cutting tool made of a surface-coated cemented carbide (hereinafter referred to as a coated cemented carbide tool) capable of exhibiting excellent cutting performance over a long period of time. 2. Description of the Related Art Generally, a cutting tool includes a throw-away tip which is removably attached to a tip of a cutting tool for turning or planing of a work material such as steel or cast iron. There are drills and miniature drills used for drilling and cutting work materials, and solid type end mills used for face milling, grooving, shoulder processing, etc. of the work material. A throw-away end mill tool or the like which is freely mounted and performs cutting in the same manner as the solid type end mill is known. [0003] Further, as a cutting tool, a substrate made of tungsten carbide (hereinafter, referred to as WC) -based cemented carbide or a titanium cermet (hereinafter, referred to as TiCN) -based cermet (hereinafter, collectively referred to as a cemented carbide substrate). On the surface)
Each of the first and second thin layers has an average layer thickness of 0.2 to 1 μm and is composed of four or more alternate layers. (A) The first thin layer has a composition formula: (Ti _1-x Al _X ) When represented by N, a composite nitride of Ti and Al satisfying X: 0.30 to 0.70 in atomic ratio as measured by an Auger spectrometer at the center in the thickness direction [hereinafter, (Ti , Al) N], and (b) the second thin layer is made of titanium nitride (hereinafter TiN).
Coated carbide tools formed by physical vapor deposition of a hard coating layer with an overall average layer thickness of 2 to 10 μm have been proposed for continuous cutting and intermittent cutting of various types of steel and cast iron. ing. [0004] Further, the coated carbide tool described above has a structure shown in FIG.
It can be manufactured using an arc ion plating apparatus having a structure shown in a schematic plan view in (a) and a schematic front view in (b). That is, the above-mentioned super-hard substrate is mounted on a rotary table in the arc ion plating apparatus, and a first thin layer forming Ti-Al alloy having various component compositions is used as a cathode electrode (evaporation source). The metal Ti for forming the second thin layer is mounted at a predetermined position in the apparatus (the installation position of the metal Ti in FIG. 1 is the same as the installation position of the illustrated Ti-Al ₂ O ₃ sintered body). After the inside of the apparatus is heated to a predetermined temperature by a heater while evacuating and maintaining a vacuum, a DC bias voltage of a predetermined voltage is applied to the carbide substrate rotating on the rotary table, and the metal of the cathode electrode is heated. An arc discharge is generated between Ti and the anode electrode,
Then, the surface of the cemented carbide substrate was cleaned by Ti bombarding, and nitrogen gas was introduced as a reaction gas into the apparatus to form a reaction atmosphere of a predetermined pressure, and a DC bias voltage applied to the cemented carbide substrate rotating on the rotary table was adjusted. As the predetermined voltage, the cathode electrode (the first thin layer forming Ti-Al
An arc discharge is generated between the alloy or the metal for forming the second thin layer Ti) and the anode electrode, so that the first thin layer and the second thin layer having a predetermined layer thickness are formed on the surface of the cemented carbide substrate. It is manufactured by vapor-depositing hard coating layers composed of alternating layers with a predetermined overall layer thickness. [0005] On the other hand, in recent years, the performance of cutting devices has been remarkably improved, and there has been a strong demand for labor saving and energy saving for the cutting process, and further, cost reduction. In general, there is a growing demand for versatile cutting tools that exhibit excellent cutting performance not only in continuous machining and intermittent machining under normal conditions, but also in heavy cutting conditions such as high cutting and high feed. However, in the above-mentioned conventional coated carbide tools, there is no problem when this is used for cutting under ordinary conditions such as steel or cast iron,
If this is used under heavy cutting conditions, especially the biting property of the hard coating layer on the work material is reduced, and the cutting edge slides off the work material surface, resulting in significant cutting heat and the temperature of the hard coating layer. At the same time, the wear of the hard coating layer is further accelerated, and the service life is relatively short. Means for Solving the Problems Accordingly, the present inventors have proposed:
In view of the above, the above-mentioned conventional coated carbide tools were focused on, and as a result of conducting research especially to suppress the temperature rise of the hard coating layer under heavy cutting conditions, the hard coating layer of the conventional coated carbide tools was obtained. The TiN layer, which is the second thin layer, is made of a relatively hard Al having a ratio of an aluminum oxide (hereinafter, referred to as Al ₂ O ₃ ) phase of 35 to 65 mass% in a total amount with the TiN phase. ₂ O ₃ phase (approx. 3000 kg in micro Vickers hardness)
f / mm 2) and a soft TiN phase (micro Vickers hardness of about 2000 kgf / mm 2), and the mixed layer and the first thin layer (Ti, Al) N layer 4
The hard coating layer is formed under the condition that the total layer thickness is 2 to 10 μm in a state where the individual layer thickness is a thin layer having an average layer thickness of 0.2 to 1 μm while the number of the layers is alternately laminated. With this configuration, the presence of the Al ₂ O ₃ phase in the second thin layer makes the hard coating layer have extremely good biting properties with respect to the work material. It is remarkably reduced, the generation of cutting heat is reduced, and the wear progress of the hard coating layer is suppressed, so that the coated carbide tool will exhibit excellent cutting performance over a long period of time. The research results were obtained. The present invention has been made on the basis of the above research results, and has a surface of a super-hard substrate of 2 to 10 μm.
The hard coating layer physically vapor-deposited with the overall average layer thickness of (a) is composed of four or more alternately laminated first and second thin layers each having an average layer thickness of 0.2 to 1 μm. When one thin layer is represented by a composition formula: (Ti _1-x Al _x ) N, the atomic ratio is measured by an Auger spectrometer at the center in the thickness direction.
X: a (Ti, Al) N layer satisfying 0.30 to 0.70, and (b) a ratio of the second thin layer to the total amount of the Al ₂ O ₃ phase and the TiN phase in the second thin layer. The hard coating layer is composed of a mixed layer of Al ₂ O ₃ phase and TiN phase of 35 to 65% by mass, and the hard coating layer shows good biting property to the work material under heavy cutting conditions. It has features. Next, in the coated cemented carbide tool of the present invention, the reason why the composition of the first thin layer and the second thin layer constituting the alternate lamination of the hard coating layer and the average layer thickness are limited as described above. I do. (A) Composition of the first thin layer of the hard coating layer A in the (Ti, Al) N layer constituting the first thin layer
l are those containing for the purpose of enhancing the high-temperature hardness and heat resistance with respect to TiN having a high strength, therefore the composition _{formula: (Ti 1-X Al X} ) X value of N atomic ratio (hereinafter the same)
If the value is less than 0.3, the desired effects of improving the high-temperature hardness and heat resistance cannot be obtained. On the other hand, if the value X exceeds 0.7, the strength is sharply reduced and chipping easily occurs in the hard coating layer. For this reason, the value of X was determined to be 0.3 to 0.7. Note that the X value is desirably set to 0.4 to 0.6. (B) Composition of the second thin layer of the hard coating layer The Al ₂ O ₃ phase in the mixed layer constituting the second thin layer is:
The effect of contributing to the reduction in the generation of cutting heat by improving the bite of the hard coating layer on the work material, suppressing the slip phenomenon between the cutting edge and the work material surface even in cutting under heavy cutting conditions. However, if the proportion is less than 35% by volume relative to the total amount with the TiN phase, the desired effect cannot be obtained in the above-mentioned action,
On the other hand, if the proportion exceeds 65% by mass, the strength provided by the TiN phase sharply decreases and chipping easily occurs in the hard coating layer.
６５65 mass%, desirably 45 to 55 mass%. (C) Average thickness of the hard coating layer The average thickness of the first thin layer and the second thin layer constituting the alternate lamination of the hard coating layer is 0.2 to 1 μm, respectively.
When the average layer thickness of any of the thin layers is less than 0.2 μm, the characteristics of each thin layer, that is, the first
The hard coating layer cannot have sufficient hardness and excellent heat resistance due to the thin layer, and high strength and excellent work material biting property due to the second thin layer, while the average layer thickness exceeds 1 μm each. This is because the excellent properties of each thin layer are mutually inhibited. Further, in order to sufficiently provide the hard coating layer with the characteristics of the first thin layer and the second thin layer, it is empirically necessary to alternately laminate at least four layers.
The number of layers was four or more. Furthermore, the reason why the total average layer thickness of the hard coating layer is 1 to 10 μm is that the layer thickness is 2 μm.
With m, the desired excellent wear resistance cannot be ensured, while if the layer thickness exceeds 10 μm, chipping tends to occur on the cutting edge. Next, the coated carbide tool of the present invention will be specifically described with reference to examples. (Example 1) As raw material powders, WC powder, TiC powder, VC powder, and Ta each having an average particle size of 1 to 3 µm
C powder, NbC powder, Cr ₃ C ₂ powder, and Co powder were prepared, and these raw material powders were blended in the blending composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and then dried under a pressure of 100 MPa. Is pressed into a green compact, and the green compact is sintered at a temperature of 1400 ° C. for 1 hour in a vacuum of 6 Pa. After sintering, R: 0.05 is applied to the cutting edge portion.
Honing process, ISO standard, CNMG120
The cemented carbide substrates A1 to A10 made of a WC-based cemented carbide having a chip shape of 408 were formed. In addition, as raw material powders,
TiCN having an average particle size of 2 μm (by weight ratio TiC /
(TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder, Co powder, and Ni powder were prepared, and these raw material powders were blended into the composition shown in Table 2. After wet-mixing with a ball mill for 24 hours and drying, the mixture is pressed into a green compact at a pressure of 100 MPa, and the green compact is heated in a nitrogen atmosphere of 2 kPa at a temperature of:
Sintered under the condition of holding at 1500 ° C. for 1 hour, and after sintering, the cutting edge portion is subjected to a honing process of R: 0.03 to obtain a TiC having a chip shape conforming to ISO standard, CNMG120408.
Carbide substrates B1 to B6 made of N-based cermet were formed. Further, as a raw material powder, an average particle diameter is 1 μm.
m metal Ti powder and 0.1 μm Al ₂ O ₃ powder were prepared, and these raw material powders were blended at a predetermined blending ratio.
After wet mixing with a ball mill for 24 hours and drying, 100
The green compact is press-molded at a pressure of MPa, and the green compact is sintered in a vacuum atmosphere of 0.5 Pa at a temperature of 1200 ° C. for 1 hour to obtain various ratios of Ti and Al _2. consisting O ₃ for the present invention the second thin layer forming Ti-Al ₂ O ₃
A sintered body was formed. Next, each of the above-mentioned super-hard substrates A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, and placed on a rotary table in an arc ion plating apparatus shown in FIG. mounting and, on the other hand as a cathode electrode (vapor source), a first thin layer forming Ti-Al alloy and the present invention described above the second thin layer forming Ti-Al ₂ O ₃ sintered body having various component compositions After mounting the metal at a predetermined position in the apparatus and also mounting metal Ti for bombarding, first heating the inside of the apparatus to 500 ° C. with a heater while evacuating the inside of the apparatus and maintaining a vacuum of 0.5 Pa, A DC bias voltage of -1000 V is applied to the carbide substrate rotating on the table to generate an arc discharge between the metal Ti of the cathode electrode and the anode electrode. And Kiyoshi, then with introducing nitrogen gas as a reaction gas into the apparatus and reaction atmosphere of 10 Pa, a cemented carbide substrate rotates on the turntable -30
0 V DC bias voltage is applied to the cathode electrode.
(The Ti-Al alloy for forming the first thin layer or the second
An arc discharge is generated between the Ti-Al ₂ O ₃ sintered body for forming a thin layer) and the anode electrode, so that the first composition having the target composition and target layer thickness shown in Table 3 is formed on the surface of the cemented carbide substrate. By depositing the thin layer and the second thin layer of the present invention in a combination shown in Table 4 and also by depositing a hard coating layer having the same number of layers as shown in Table 4, a schematic perspective view in FIG. And (b) a throw-away tip made of a surface-coated cemented carbide of the present invention as a coated carbide tool of the present invention having a shape shown in a schematic longitudinal sectional view (hereinafter referred to as the coated cemented carbide tip of the present invention) 1
~ 16 were each manufactured. For the purpose of comparison, the above-described Ti-Al ₂ O ₃ sintered body for forming a second thin layer of the present invention is replaced with the conventional metal Ti for forming a second thin layer. Under the same conditions as those for producing the coated superhard chips 1 to 16 of the present invention, the first thin layer having the target composition and the target layer thickness as shown in Table 3 and the conventional second thin layer were formed on the surface of the superhard substrate. By depositing a hard coating layer having the number of layers alternately shown in Table 5 in the combination shown in Table 5, a conventional surface coated cemented carbide alloy throwaway chip (hereinafter, referred to as a conventional coated carbide tool) Conventionally referred to as coated carbide tips) 1 to 16 were manufactured. Next, the coated carbide tips 1 to 1 according to the present invention will be described.
6 and the conventional coated carbide tips 1 to 16 were screwed to the tip of a tool steel bit with a fixing jig. Work material: JIS SCM440 round bar, Cutting speed: 250 m / min . Infeed: 4 mm Feed: 0.2 mm / rev. , Cutting time: 10 minutes, Dry high-cut continuous turning test of alloy steel under the following conditions: Work material: JIS S50C, 4 longitudinally-spaced round bars at regular intervals in the longitudinal direction, Cutting speed: 200 m / min. Infeed: 2 mm Feed: 0.4 mm / rev. , Cutting time: 10 minutes, Dry high-feed intermittent turning test of carbon steel under the following conditions: Work material: JIS-FC300, 4 longitudinally-spaced round bars with equally spaced longitudinal grooves, Cutting speed: 250 m / min. Infeed: 4 mm Feed: 0.2 mm / rev. Cutting time: 10 minutes, a dry high-cut intermittent turning test of cast iron was performed under the following conditions, and the flank wear width of the cutting edge was measured in each of the turning tests. Table 6 shows the measurement results. [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] [Table 6] Example 2 As raw material powder, average particle size:
Medium coarse WC powder having 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, 1.2 μm
NbC powder, 1.2 μm ZrC powder, 2.3 μm
m Cr ₃ C ₂ powder, 1.5 μm VC powder, 1.0
μm of (Ti, W) C powder and 1.8 μm of Co
Powders were prepared, and these raw material powders were respectively blended in the composition shown in Table 7, and further added with wax, and ball-mixed in acetone for 24 hours, and dried under reduced pressure.
Press molding at a pressure of 0 MPa into various green compacts of a predetermined shape, and pressing these green compacts in a vacuum atmosphere of 6 Pa at 7 ° C. /
The temperature was raised to a predetermined temperature in the range of 1370 to 1470 ° C. at a heating rate of 1 minute, kept at this temperature for 1 hour, and then sintered under the condition of furnace cooling to obtain a sample having a diameter of 8 mm, 13 mm and 26 mm. Kinds of round bar sintered bodies for forming a cemented carbide substrate are formed, and the above three kinds of round bar sintered bodies are subjected to grinding processing in a combination shown in Table 7 to obtain the diameter × length of the cutting edge portion. Is 6mm × 1 each
3mm, 10mm x 22mm, and 20mm x 45m
Carbide substrate C-1 to C-8 for end mill having dimension of m
Was manufactured respectively. Next, these cemented carbide substrates C-1 to C-8
Each was washed with ultrasonic waves in acetone and dried, and then charged into an arc ion plating apparatus also shown in FIG. 1, and the surfaces thereof were shown in Table 3 under the same conditions as in Example 1 above. The first thin layer of the target composition and the target layer thickness to be combined with the second thin layer of the present invention in the combination shown in Table 8,
Also, by depositing a hard coating layer having the same number of layers as shown in Table 8, a schematic front view in FIG.
(B) End mill made of surface-coated cemented carbide of the present invention (hereinafter referred to as coated carbide end mill of the present invention) 1 as a coated carbide tool of the present invention having the shape shown in the schematic cross-sectional view of the cutting edge portion. 8 were each produced. For the purpose of comparison, the cemented carbide substrate C-
1 to C-8 were each subjected to ultrasonic cleaning in acetone and dried, and then charged into an arc ion plating apparatus also shown in FIG.
Of the target composition and the target layer thickness shown in Table 3 under the same conditions as the manufacturing conditions of the conventional coated carbide tips 1 to 16 in FIG.
The combination of the thin layer and the conventional second thin layer as shown in Table 9,
Also, by depositing the hard coating layers having the number of layers alternately shown in Table 9, end mills made of conventional surface-coated cemented carbide as conventional coated carbide tools (hereinafter referred to as conventional coated carbide end mills) 1 to 8 Was manufactured respectively. Next, the coated carbide end mill 1 of the present invention will be described.
-8 and the conventional coated carbide end mills 1-8, the coated carbide end mills 1-3 of the present invention and the conventional coated carbide end mills 1-3 are: work material: plane dimension: 100 mm × 250 mm, thickness: 5
JIS SNCM439 plate material of 0 mm, rotation speed: 2000 min ^-1 , axial cut: 10 mm, feed: 100 mm / min. For the dry high-groove cutting test of the alloy steel under the following conditions, the coated carbide end mills 4 to 6 of the present invention and the conventional coated carbide end mills 4 to 6, the work material: plane dimension: 100 mm × 250 mm, thickness: 5
JIS FC300 plate material of 0 mm, rotation speed: 2200 min ^-1 , axial cut: 8 mm, feed: 120 mm / min. For the dry high-groove cutting test of the cast iron under the following conditions, the coated carbide end mills 7, 8 of the present invention and the conventional coated carbide end mills 7, 8 are as follows: Work material: plane dimension: 100 mm × 250 mm, thickness: 5
0 mm JIS SKD61 (hardness: HRC52) plate material, rotational speed: 1500 min ^-1 , axial cut: 6 mm, feed: 70 mm / min. Dry high-groove cutting test of hardened steel under the following conditions:
In each of the groove cutting tests, the cutting groove length was measured until the flank wear amount of the outer peripheral edge reached 0.1 mm, which is a standard for the service life. Tables 8 and 9 show the measurement results.
Respectively. [Table 7] [Table 8] [Table 9] (Example 3) The diameter produced in Example 2 was 8 mm (for forming the cemented carbide substrates C-1 to C-3) and 13 m.
m (for forming the super-hard substrate C-4 to C-6), and 26 mm
Using the three types of round bar sintered bodies (for forming the cemented carbide substrates C-7 and C-8), the three types of round bar sintered bodies were subjected to grinding to obtain the diameter × length of the groove forming portion. Are 4 mm × 13 mm (carbide substrate D-1 to D-3) and 8 mm × 22 mm (carbide substrate D
-4 to D-6), and a carbide substrate D- for a drill having dimensions of 16 mm × 45 mm (carbide substrates D-7 and D-8).
1 to D-8 were produced respectively. Next, these super-hard substrates D-1 to D-8
Was washed ultrasonically in acetone and dried, and then charged into an arc ion plating apparatus shown in FIG. 1 on the surface of these super-hard substrates under the same conditions as in Example 1 above. The first of the target composition and the target layer thickness shown in FIG.
By depositing the thin layer and the second thin layer of the present invention in a combination shown in Table 10 and a hard coating layer having the same number of laminated layers as shown in Table 10, a schematic front view is shown in FIG. And (b) a drill made of a surface-coated cemented carbide of the present invention as a coated carbide tool of the present invention having the shape shown in the schematic cross-sectional view of the groove forming portion (hereinafter referred to as the coated carbide drill of the present invention) 1 To 8 were each manufactured. For the purpose of comparison, the above-mentioned carbide substrate D-
1 to D-8 were each subjected to ultrasonic cleaning in acetone, dried, and charged into an arc ion plating apparatus also shown in FIG.
Of the target composition and the target layer thickness shown in Table 3 under the same conditions as the manufacturing conditions of the conventional coated carbide tips 1 to 16 in FIG.
The thin layer and the conventional second thin layer are combined in the manner shown in Table 11 and the hard coating layer having the alternate number of layers also shown in Table 11 is deposited to form the conventional surface coated super hard tool as the conventionally coated super hard tool. Drills made of hard alloy (hereinafter referred to as conventional coated carbide drills) 1 to 8 were manufactured, respectively. Next, the coated carbide drills of the present invention 1 to 8
Of the coated carbide drills 1 to 8 of the present invention, the coated carbide drills 1 to 3 and the coated carbide drills 1 to 3 of the present invention are as follows: Work material: plane dimension: 100 mm × 250 thickness: 50 mm
JIS S50C plate material, Cutting speed: 120 m / min. , Feed: 0.4 mm / rev, wet high feed drilling cutting test of carbon steel under the conditions of: coated carbide drills 4 to 6 of the present invention and conventional coated carbide drill 4
About 6: Work material: Plane dimensions: 100 mm x 250 mm, thickness: 5
0 mm JIS SCM440 plate material, Cutting speed: 140 m / min. , Feed: 0.4 mm / rev, Wet high-feed drilling cutting test of alloy steel under the following conditions: coated carbide drills 7 and 8 of the present invention and conventional coated carbide drills 7 and 8 Dimensions: 100mm x 250mm, thickness: 5
0 mm JIS FC250 plate material, Cutting speed: 150 m / min. , Feed: 0.4mm / rev, Wet cutting test of high feed drilling of cast iron under the following conditions, respectively, and any wet high speed drilling cutting test (both tests use water-soluble cutting oil) The number of holes drilled until the flank wear width of the surface reached 0.3 mm was measured. The measurement results are shown in Tables 10 and 11, respectively. [Table 10] [Table 11] The coated carbide tips 1-16, the coated end mills 1-8, and the coated drill 1 of the present invention as the resulting coated carbide tools of the present invention.
The composition and thickness of the hard coating layer of the conventional coated carbide tips 1-16, the conventional coated carbide end mills 1-8, and the conventionally coated carbide drills 1-8 as the conventional coated carbide tools, When measured using a dispersive X-ray measurement device, an Auger spectrometer, and a scanning electron microscope, the composition and the average layer thickness are substantially the same as the target compositions and the target layer thicknesses in Tables 3 to 11 (measured at any five locations). (Comparison with the average value). According to the results shown in Tables 3 to 11, all of the coated carbide tools of the present invention can be used for cutting steel or cast iron under heavy cutting conditions such as high cutting and high feed. In particular, the presence of the Al ₂ O ₃ phase in the second thin layer constituting the hard coating layer improves the biting property with respect to the work material, so that the cutting edge does not slip on the work material surface and has excellent wear resistance. On the other hand, in the case of the conventional coated carbide tool in which the Al ₂ O ₃ phase does not exist in the second thin layer of the hard coating layer, the hard coating layer has a biting property to the work material under heavy cutting conditions. Poorly, the cutting edge slides off the surface of the work material, and as a result, remarkable cutting heat is generated, so that the temperature of the hard coating layer increases, and the wear of the hard coating layer is further accelerated, and the cutting time is relatively short. It is evident that time will lead to a service life. As described above, the coated carbide tool of the present invention can be used not only for cutting under ordinary conditions such as various kinds of steel and cast iron, but also especially for cutting under heavy cutting conditions such as high cutting and high feed. Since it exhibits excellent abrasion resistance, it can sufficiently satisfactorily save labor and energy and also reduce costs in cutting.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic explanatory view of an arc ion plating apparatus. FIG. 2A is a schematic perspective view of a coated carbide tip, and FIG.
1 is a schematic vertical sectional view of a coated carbide tip. FIG. 3 (a) is a schematic front view of a coated carbide end mill,
(B) is a schematic transverse sectional view of the cutting blade portion. FIG. 4A is a schematic front view of a coated carbide drill, and FIG.
FIG. 3 is a schematic cross-sectional view of the groove forming portion.

Continuation of front page    (72) Inventor Kazuki Izumi             1511 Furamagi, Ishishita-cho, Yuki-gun, Ibaraki Prefecture             Mitsubishi Materials Corporation Tsukuba Works F-term (reference) 3C037 CC02 CC09 CC11 FF04                 3C046 FF03 FF05 FF10 FF13 FF16                       FF19 FF25                 4K029 AA04 BA58 BA64 BB02 BC02                       BD05 CA04 EA01

Claims (1)

Claims: 1. A surface of a tungsten carbide-based cemented carbide substrate or a titanium carbonitride-based cermet substrate having a thickness of 2 to 10 μm.
The hard coating layer physically vapor-deposited with the total average layer thickness of (a) comprises four or more alternately laminated first and second thin layers each having an average layer thickness of 0.2 to 1 μm; When one thin layer is represented by the composition formula: (Ti _1-x Al _x ) N, the atomic ratio X: 0.30 to 0.70 is measured by an Auger spectrometer at the center in the thickness direction. (B) an aluminum oxide in which the second thin layer is 35 to 65% by mass in a ratio of the aluminum oxide phase to the total amount of the titanium nitride phase. A cutting tool made of a surface-coated cemented carbide having a hard coating layer characterized by being composed of a mixed layer of a titanium phase and a titanium nitride phase, and exhibiting good biteability to a work material under heavy cutting conditions.