JP2005297141A - Surface-coated throwaway tip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated throwaway tip having a prolonged service lifetime and excellent lubricity and abrasion resistance even under an operating environment to expose the cutting edge to a high-temperature state in high-speed/high-efficiency working. <P>SOLUTION: The surface-coated throwaway tip has a coated layer composed of an outermost layer and an inner layer on the surface of a base material. The inner layer has a titanium-containing layer comprising TiCN having a columnar tissue with an aspect ratio of at least 3 in which any one of respective orientation property indexes TC (220), TC (311), and TC (422) of crystal planes (220), (311), and (422) takes the maximum value of the orientation property index. The outermost layer is composed of aluminum nitride or aluminum carbonitride and contains over 0 and up to 0.5 atom% of chlorine. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a throw-away tip having a coating layer on a substrate surface. In particular, the present invention relates to a surface-coated throw-away tip that has excellent lubricity and wear resistance and is suitable for cutting steel and the like.

  In recent years, new cutting tool materials have been developed one after another in order to meet the demands for higher efficiency and higher precision in cutting. In such a material development flow, a ceramic coating technique for applying a ceramic coating layer on the surface of a tool base has become an indispensable technique for cutting tools.

As a coating layer for cutting tools used for high-speed and high-efficiency machining such as high-speed and high-feed, titanium-based ceramics such as titanium carbide (TiC), titanium nitride (TiN), and titanium carbonitride (Ti (C, N)), and alumina Oxide ceramics such as (Al ₂ O ₃ ) and zirconia (ZrO ₂ ) are widely used. For example, Patent Document 1 discloses a cutting tool including a coating layer that defines an orientation index of X-ray diffraction.

  In addition to the high-speed and high-efficiency machining, recently, a mist machining method in which cutting oil is extremely reduced to protect the global environment, or a dry machining method that does not use cutting oil has attracted attention. In order to cope with these processing methods, cutting tools having a coating layer having excellent welding resistance and a coating layer having a chip sliding function have been proposed (see Patent Documents 2 and 3). In addition, in order to improve characteristics such as heat dissipation, cutting tools including a coating layer made of aluminum nitride have been proposed (see Patent Documents 4 to 8).

Japanese Patent Laid-Open No. 11-124672 Japanese Patent Laid-Open No. 10-158861 JP 2003-225808 A Japanese Patent Publication No.59-27302 Japanese Patent No. 2861113 JP 2002-273607 A Japanese Patent Laid-Open No. 2003-19604 JP 2003-25112 A

  However, all of the above-mentioned conventional cutting tools have insufficient lubrication function in dry machining that does not use cutting oil, so the tool life is shortened, improving lubricity and extending the tool life. Is desired.

  Accordingly, a main object of the present invention is to provide a surface-coated throw-away tip with improved lubricity and longer tool life.

  In order to provide lubricity to the outermost layer that first contacts the work material during cutting, the present invention specifies the composition of the outermost layer to contain a specific element and to provide wear resistance to the inner layer. The above object is achieved by defining the composition, crystal structure and orientation.

That is, the present invention is a surface-coated throwaway chip having a coating layer on a substrate surface, the coating layer comprising an inner layer formed on the substrate and an outermost layer formed on the inner layer. The outermost layer and the inner layer satisfy the following.
<Inner layer>
The following titanium-containing layers are provided.
A layer made of TiCN that satisfies the following conditions (1) and (2)
(1) Has a columnar structure with an aspect ratio of 3 or more
(2) Any of the orientation indices TC (220), TC (311), and TC (422) on the (220), (311), and (422) planes of the crystal has the maximum value of the orientation index. <Outermost layer>
It consists of aluminum nitride or aluminum carbonitride, and contains chlorine in the outermost layer more than 0 and 0.5 atomic% or less

  The inventors of the present invention have made extensive studies on the relationship between the coating layers as well as improving the properties of the coating layers so that the tool life can be further extended even in dry machining that does not use cutting oil. . As a result, it has been found that it is effective to extend the tool life by providing a coating film having excellent lubricity as the outermost layer and providing a coating film having excellent wear resistance in the inner layer. Specifically, as described above, a film made of nitrided aluminum containing a specific amount of chlorine is used as the outermost layer, so that lubricity can be imparted even in dry processing, resulting in resistance to welding. Property can be improved and peeling of the coating layer can be prevented. Moreover, by being excellent in lubricity, the cutting resistance applied to a tool can be reduced, and chipping resistance and chipping resistance can also be improved. Furthermore, by providing the inner layer with a film made of titanium carbonitride (TiCN) having a specific structure and orientation, the wear resistance can be further improved. In addition, by providing a film with excellent lubricity, it is possible to obtain a high-quality and high-accuracy work material product with less surface peeling due to the contact of the tool on the work material surface after cutting. The knowledge that it was possible was also obtained. Based on these findings, the present invention is defined.

  The reason why the tool life can be improved as described above is considered as follows at the present stage. In the first place, a film made of nitride-based aluminum has thermal stability and lubricity. In addition, when a certain amount of chlorine is included in such a film, the cutting edge temperature is about 900 ° C due to the cutting process when the cutting edge temperature tends to be high, such as dry machining and high-speed high-feed machining. When it becomes, it becomes easy to form a protective film on the tool surface. It is considered that this protective coating can improve lubricity and improve the welding resistance of the tool. A film made of specific TiCN constituting the inner layer is considered to be excellent in wear resistance because of its high hardness. Hereinafter, the present invention will be described in more detail.

(Coating layer)
<Outermost layer>
In the present invention, the outermost layer that first contacts the work material during cutting is made of an aluminum compound such as aluminum nitride or aluminum carbonitride. In the present invention, chlorine is contained in the nitride aluminum film. Specifically, more than 0 and 0.5 atomic% or less of chlorine is contained in the outermost layer. By containing 0.5 atomic% or less of chlorine in the outermost layer, a protective coating can be formed in a cutting environment at a high temperature, and lubricity can be improved. When chlorine is contained exceeding 0.5 atomic%, the strength of the coating layer is extremely lowered, and the film forming the outermost layer is easily peeled off. Further, if no chlorine is contained, no protective film is formed as described above. A particularly preferable chlorine content is 0.07 atomic% or more and 0.3 atomic% or less. As a method of adding chlorine exceeding 0 to 0.5 atomic% or less in the outermost layer, when using a chemical vapor deposition method (CVD method) such as a thermal CVD method or a plasma CVD method for forming a film made of nitrided aluminum, a reaction As the gas, a chlorine-containing gas such as hydrogen chloride (HCl) can be used. At this time, the content of hydrogen chloride may be more than 0 and less than 5.0% by volume, particularly 1.0% by volume or less, with the entire reaction gas being 100% by volume. In addition, when using a physical vapor deposition method (PVD method) such as an arc ion plating method or a magnetron sputtering method to form a film made of nitride-based aluminum, chlorine ions may be implanted by ion implantation after the film formation. Can be mentioned. At this time, the content of chlorine in the outermost layer may be adjusted by appropriately adjusting the injection amount.

  The outermost layer may further contain oxygen. That is, the outermost layer may be formed not only from aluminum nitride and aluminum carbonitride, but also from aluminum oxynitride and aluminum oxycarbonitride. By containing oxygen, it becomes easier to form a protective film.

  Such an outermost layer preferably has a film thickness of ½ or less of the total film thickness of inner layers described later. At this time, the coating layer can have a good balance between the protective film forming function (lubricating function) and the wear resistance. If it exceeds 1/2, the outermost layer becomes thick, and although it is excellent in lubricity, it tends to be worn out, so there is a risk of shortening the tool life. In particular, the thickness of the outermost layer is preferably 0.03 μm or more and 10 μm or less. If it is less than 0.03 μm, it is difficult to obtain a sufficient lubricating function, and if it exceeds 10 μm, the outermost layer is thicker than the inner layer as described above, and the wear resistance tends to be lowered. The measurement of the film thickness includes, for example, obtaining by cutting a throw-away tip having a coating layer and observing the cross section using an SEM (scanning electron microscope).

  In this outermost layer, the surface roughness of the portion in contact with the work material in the vicinity of the edge portion of the cutting edge is preferably 1.3 μm or less in Rmax with respect to 5 μm measured by a method of observing from the cutting tool cross section. As a result of investigations by the present inventors, it has been found that when the surface roughness of the contacted portion in the outermost layer becomes rougher than 1.3 μm, welding of the work material is likely to occur, and the lubricating effect is hardly exhibited. This surface roughness is the maximum surface when the outermost layer is formed, the substrate is cut and its cross-section is wrapped, and the uneven state of the film surface is observed within a standard length of 5 μm with a metal microscope or electron microscope. Roughness (Rmax) is assumed, and macroscopic swells are excluded. Further, the surface roughness can be controlled to some extent by the film forming conditions. For example, the higher the film formation temperature, the rougher the crystal structure, so that the surface roughness of the film surface becomes rougher. Therefore, lowering the film formation temperature can be mentioned. Thus, after film formation, Rmax can be 1.3 μm or less in the film formation completion state without performing special treatment, but after film formation, for example, polishing with a buff, brush, barrel, elastic grindstone, etc. It is also possible to change the surface roughness by applying or performing surface modification by microblasting, shot peening, or ion beam irradiation.

<Inner layer>
<Titanium-containing layer>
In this invention, the film | membrane which consists of TiCN is provided as an inner layer provided on a base material. In particular, the film made of TiCN has a columnar structure with an aspect ratio of 3 or more. This is because if the aspect ratio is less than 3, the wear resistance decreases under high-temperature cutting conditions, and the intended wear resistance cannot be improved in a granular structure.

In order to obtain a columnar structure, organic carbonitride such as CH ₃ CN, which can easily obtain a columnar structure, is used as the raw material gas, and the reaction atmosphere temperature (800 ° C to 950 ° C) and pressure (4.0 kPa to 80 kPa) are controlled. You can get it. In addition, when using a gas species other than organic carbonitrides, there are methods such as increasing the film formation rate, increasing the film formation temperature, and increasing the concentration of the source gas. In order to set the aspect ratio to 3 or more, for example, the average grain size of crystals is reduced (preferably 0.05 μm or more and 1.5 μm or less), and a film structure of a columnar structure is grown. Examples of the method include a method of appropriately changing the film formation conditions (film formation temperature, film formation pressure, gas composition, gas flow rate, gas flow rate, etc.) of the titanium-containing layer. Moreover, the method of changing suitably the surface state of the base material directly under or below a titanium containing layer, or the surface state of the coating film directly under or under a titanium containing layer is also mentioned. Specifically, for example, a titanium-containing layer is formed on the base material by appropriately changing the film formation conditions in a state where the surface roughness Zmax is controlled to be 0.05 μm or more and 1.5 μm or less. May be. Alternatively, a titanium-containing layer may be formed by appropriately changing the film formation conditions on the film in a state in which the surface roughness of the film, the chemical state of the particles, the particle diameter (especially 0.01 μm or more and 1.0 μm or less) are controlled A film may be formed.

  The aspect ratio may be measured as follows, for example. That is, the cross section of the coating layer is mirror-finished to etch the grain boundaries of the film structure of TiCN having a columnar structure. Then, at a place corresponding to 1/2 of the thickness of the film made of TiCN, the width of each crystal in the horizontal direction with the base material is defined as the particle size, and the average value is obtained by measuring the particle size of each crystal (the average value is Average particle size). The film thickness is divided by the obtained average particle diameter to calculate the ratio of the average particle diameter to the film thickness, and this calculated value may be used as the aspect ratio.

  The film made of TiCN further has a crystal plane having a specific crystal orientation. By having a specific film structure and a specific crystal orientation in this way, it is possible to improve wear resistance and extend the tool life even in severe cutting environments where the cutting edge becomes hot. Can do. Specifically, each orientation index (orientation strength coefficient) TC (220), TC (311), or TC (422) on the (220) plane, (311) plane, or (422) plane of the crystal is one of The maximum value of the orientation index is assumed. The orientation index TC is defined as follows.

  In order for the orientation index (orientation strength coefficient) TC (220), TC (311), or TC (422) to reach the maximum value, the deposition conditions for the titanium-containing layer (deposition temperature, deposition pressure, gas composition) , Gas flow rate, gas flow rate, and the like). Moreover, the method of changing suitably the surface state of the base material directly under or below a titanium containing layer, or the surface state of the coating film directly under or under a titanium containing layer is also mentioned. Specifically, for example, a titanium-containing layer is formed on the base material by appropriately changing the film formation conditions in a state where the surface roughness Zmax is controlled to be 0.05 μm or more and 1.5 μm or less. May be. Alternatively, a titanium-containing layer may be formed on this film by appropriately changing the film formation conditions in a state in which the surface roughness of the film, the chemical state of the particles, the particle diameter, and the like are controlled.

  The diffraction intensity is preferably measured in a flat portion (smooth portion) of the base material so that reflection or the like is not caused by unevenness of the base material in the cross section of the base material. The identification of the X-ray diffraction intensity in the periodic table IVa, Va, VIa group metal carbonitride is not described in the JCPDS file (Powder Diffraction File Published by JCPDS International Center for Diffraction Data). Therefore, the identification of the diffraction intensity of the titanium-containing layer made of TiCN as the carbonitride is the diffraction data of the titanium (Ti) carbide as the metal, the diffraction data of the nitride, and the measured TiCN carbonitride It is preferable to obtain the surface index by comparing the diffraction data of the surface area, estimating each plane index, and measuring the diffraction intensity of the plane index.

<Compound layer>
When the inner layer is formed of a plurality of films, at least one film is the titanium-containing layer, and the other films are one or more selected from periodic table IVa, Va, VIa group metals, Al, Si, B It is preferable to be a compound layer composed of the first element and one or more second elements selected from B, C, N, O (However, when the first element is only B, the second element is Other than B). That is, when the inner layer is formed of a plurality of films, it is preferable that the inner layer is composed of the titanium-containing layer and the compound layer. This compound layer is different from the titanium-containing layer. That is, a film having a composition different from that of the titanium-containing layer may be used, and when the compound layer is a TiCN film, the structure or orientation may be changed.

  Each of the compound layers may be a single film or a plurality of films. In the case where the titanium-containing layer is composed of a plurality of films, it may be a film having different orientation. In the case where the compound layer is composed of a plurality of films, the composition and structure of each film may be different. Moreover, when providing a compound layer, you may make any of a titanium content layer and a compound layer into the base-material side. That is, it is good also as a titanium content layer, a compound layer, and an outermost layer in order from a base material side, and it is good also as a compound layer, a titanium content layer, and an outermost layer in order from a base material side. When the compound layer is the innermost layer, it is preferably a film made of titanium nitride (TiN) having high adhesion to the substrate. These titanium-containing layer and compound layer may be formed by any of CVD methods such as thermal CVD method and plasma CVD method, PVD methods such as arc ion plating method and magnetron sputtering method. You may form on well-known conditions.

  The film thickness of the entire coating layer composed of the outermost layer and the inner layer is preferably 0.1 μm or more and 30.0 μm or less. When the film thickness of the entire coating layer is less than 0.1 μm, it is difficult to obtain an effect of improving wear resistance. When the thickness exceeds 30.0 μm, the wear resistance can be improved by increasing the thickness of the coating layer. However, since the hardness becomes high, the chip tends to be damaged, and the life due to the chip tends to be increased, so that stable processing is likely to be difficult. In addition, after forming the coating layer which consists of the said outermost layer and inner layer on the surface of a base material, of course, surface treatments, such as a grinding | polishing process and a laser process, may be given to a cutting edge ridgeline part similarly to the past. The throw-away tip of the present invention does not significantly impair the properties of the coating layer by such surface treatment.

(Base material)
In the present invention, it is preferable to use a substrate composed of any one of WC-based cemented carbide, cermet, high speed steel, ceramics, cubic boron nitride sintered body, and silicon nitride sintered body. . In addition, when using a base material made of WC-based cemented carbide or cermet, the so-called de-β phase where the hard phase other than WC has disappeared, the binder-rich layer rich in the binder phase with the hard phase disappearing, and the binder phase reduced. The effect of the present invention is recognized even when a surface modification layer such as a cured surface layer is present on the surface of the substrate.

  As described above, according to the surface-coated throw-away tip of the present invention, by providing a coating layer excellent in both lubricity and wear resistance, the cutting edge such as dry processing and high speed / high efficiency processing is exposed to a high temperature state. Even under the usage environment, it has excellent cutting performance and can prolong the tool life.

  Embodiments of the present invention will be described below.

(Test Example 1)
After blending material powders with a composition of WC: 86% by mass, Co: 8.0% by mass, TiC: 2.0% by mass, NbC: 2.0% by mass, ZrC: 2.0% by mass, wet-mixed for 72 hours in a ball mill and dried Then, it was press-molded into a compacted body with a breaker shape. The green compact was sintered in a sintering furnace in a vacuum atmosphere at 1420 ° C. for 1 hour to obtain a sintered body. The edge of the edge of the sintered body was subjected to SiC brush honing treatment and chamfered to obtain a throw-away tip base material made of WC-based cemented carbide of ISO · SNMG120408.

A coating layer was formed on the surface of the substrate using a thermal CVD method which is a chemical vapor deposition method. In this test, TiN (0.5), columnar structure TiCN (6), TiBN (0.5), and κ-Al ₂ O ₃ (2) are formed as the inner layer in order from the substrate side, and AlN (3) is formed as the outermost layer. (The numerical value in parentheses is the film thickness (unit: μm)). Table 1 shows the film formation conditions of each film, specifically, the composition (volume%) of the reaction gas, the pressure (kPa) during film formation, and the film formation temperature (° C.). The film thickness was adjusted by the film formation time. In this test, the TiCN film was formed so as to have a columnar structure with an aspect ratio of 4.2 and the (311) plane of the orientation index TC had the maximum value (corresponding to a titanium-containing layer). Specifically, the reaction gas is CH ₃ CN, the temperature is set to 900 ° C., the pressure is set to 8 kPa, and the surface roughness of the TiN film formed in the lower layer of the TiCN film is set to about 0.1 μm at Zmax. The film formation conditions (gas composition, pressure, temperature) were determined. As the AlN film forming the outermost layer, samples having different chlorine contents were prepared by changing the film forming conditions as shown in Table 1. Table 2 shows the chlorine content of the outermost layer. Specifically, the outermost layer containing more than 0 and 0.5 atomic percent or less of chlorine, the one containing more than 0.5 atomic percent of chlorine and the one not containing the same chlorine were prepared. As shown in Table 1, the chlorine content was changed by changing the ratio of hydrogen chloride (HCl) in the reaction gas. Further, the pressure during film formation and the film formation temperature were appropriately changed depending on the amount of hydrogen chloride. Furthermore, when the outermost layer contained chlorine of more than 0 and 0.5 atomic percent or less, the surface roughness of the portion that contacted the work material in the vicinity of the edge of the edge of the outermost layer was examined. The Rmax was 1.3 μm or less with respect to the reference length of 5 μm measured by the above method. Specifically, for example, Sample 1-2 was 0.6 μm. The chlorine content was measured by XPS (X-ray Photoelectron Spectroscopy). It can also be done by Spectrometry).

  Using the surface-coated throwaway tip having the outermost layer shown in Table 2, continuous cutting was performed under the cutting conditions shown in Table 3, and the processing time until the tool life was reached was measured. In the peel resistance test, cutting was repeatedly performed, and the tool life was determined when the flank wear amount due to film peeling reached 0.3 mm or more. In the wear resistance test, the tool life was determined when the flank wear amount was 0.3 mm or more. The test results are shown in Table 4.

  As a result, as shown in Table 4, samples 1-1 to 1-3 having an aluminum nitride film containing chlorine of more than 0 and 0.5 atomic% or less as the outermost layer have excellent lubricity even in dry processing It can be seen that the anti-peeling property is improved by improving the welding resistance and lowering the cutting resistance. Further, it can be seen that these samples 1-1 to 1-3 are excellent in wear resistance by providing a specific inner layer. Furthermore, these samples 1-1 to 1-3 did not cause chipping, and were excellent in chipping resistance and chipping resistance. From these facts, it can be seen that Samples 1-1 to 1-3 have a long machining time and an extended tool life.

(Test Example 2)
Prepare the same cemented carbide base material used in Test Example 1, and apply the coating layer on the surface of the obtained base material using the thermal CVD method under the film formation conditions (gas composition, pressure, temperature) shown in Table 1 Formed. In this test, TiN (0.5), columnar structure TiCN (4) or granular structure TiCN (4), TiBN (0.5), Al ₂ O ₃ -ZrO ₂ (2) in order from the substrate side, and AlN as the outermost layer ^{* 1} (Sample 1-3 in Table 2) was formed (the value in parentheses is the film thickness (unit: μm)). The film thickness was adjusted by the film formation time. In this test, the columnar structure TiCN film changes the pressure and temperature during film formation as shown in Table 1, and also changes the surface roughness and gas conditions of the TiN film formed under the TiCN film. Thus, the surface having the maximum aspect ratio and orientation index was changed. Specifically, CH ₃ CN is used as the reaction gas, for example, the gas temperature is 920 ° C., the pressure is 6 kPa, and the CH ₃ CN as the reaction gas is gradually introduced so that the aspect ratio of the TiCN film is 3 or more. . In addition, the surface roughness of the base material is controlled to 0.09 μm in Zmax, and the TiCN film is formed while controlling the aspect ratio on the outside (the side away from the base material) of this base material. The maximum value of the orientation index was TC (422). In addition, all the surface roughness of the part that contacts the work material near the edge of the edge of the outermost layer is 0.4 μm in Rmax with respect to the reference length of 5 μm measured by the method of observing from the tool cross section. In the sample, after forming the outermost layer, the surface of the outermost layer was polished. Table 5 shows the surface of the TiCN film having the maximum morphology, aspect ratio, and orientation index TC.

  Using a surface-coated throwaway tip having a TiCN film shown in Table 5 as an inner layer, continuous cutting was performed under the following cutting conditions, and the processing time until the tool life was reached was measured. The tool life was determined when the flank wear amount was 0.3 mm or more. The test results are also shown in Table 5.

Work material: SUS material Abrasion resistance test with a round bar Speed: V = 200m / min
Feed: f = 0.2mm / rev.
Cutting depth: d = 1.5mm
Cutting oil: None

  As a result, as shown in Table 5, the sample has a columnar structure TiCN film in which the inner layer has an aspect ratio of 3 or more and the orientation index TC (311), TC (220), or TC (422) has the maximum value. Nos. 2-1 to 2-3 are excellent in wear resistance even in dry processing, and the tool life is extended. The long tool life is considered to be due to the outermost layer having excellent lubricity and the inner layer having excellent wear resistance.

(Test Example 3)
Prepare the same cemented carbide base material used in Test Example 1, and apply the coating layer on the surface of the obtained base material using the thermal CVD method under the film formation conditions (gas composition, pressure, temperature) shown in Table 1 Formed. In this test, the columnar structure TiCN film was controlled in film formation conditions so that the aspect ratio was 3 or more and the orientation index TC (311), TC (220), or TC (422) had the maximum value ( Applicable to titanium-containing layer). Table 6 shows the composition, film thickness, and film thickness of the entire coating layer (total film thickness). In Table 6, the first film, the second film,...

  Using a surface-coated throw-away tip having a coating layer shown in Table 6, continuous cutting was performed under the following cutting conditions, and the processing time until the tool life was reached was measured. The tool life was determined when the flank wear amount was 0.3 mm or more. The test results are also shown in Table 6.

Work material: SCM435 15-second repeated wear resistance test with a round bar Speed: V = 180 m / min
Feed: f = 0.2mm / rev.
Cutting depth: d = 1.5mm
Cutting oil: None

  As a result, as shown in Table 6, a nitride-based aluminum film containing a specific amount of chlorine is used as the outermost layer, and an aspect ratio of 3 or more, orientation index TC (311), TC (220), TC (422) Samples 3-1 to 3-12, 3-16 to 3-19, and 3-21, which have a TiCN film with a columnar structure with the maximum value in the inner layer, have excellent lubricity and excellent wear resistance. I understand that.

  Further, the results shown in Table 6 indicate that the outermost layer is preferably 0.03 μm or more and the total film thickness is preferably 0.1 μm or more and 30 μm or less. Further, it is understood that the outermost layer is preferably 1/2 or less of the total thickness of the inner layer.

  As a result of cutting all the chips of Samples 3-1 to 3-21 and measuring the surface roughness of the outermost layer in contact with the work material in the vicinity of the edge of the cutting edge at a reference length of 5 μm, Sample 3- All the chips except 21 had a Rmax of 1.3 μm or less, but Sample 3-21 had a Rmax of 1.7 μm. Therefore, when polishing the surface roughness of the outermost layer of sample 3-21 with the # 1500 diamond paste in the vicinity of the edge of the edge of the cutting edge, the surface roughness after polishing was measured by the same method. It was 0.52 μm. As a result of a cutting test using the polished tip under the same cutting conditions, the tool life was 24 min. This is considered to be because the unevenness of the portion in contact with the work material in the vicinity of the edge of the edge of the cutting edge is reduced and the cutting resistance is lowered. In addition, when the surface roughness was measured in the same manner for Sample 3-3, the Rmax was 0.76 μm, but when the edge was polished and cut again in the same manner as described above, the tool life was 48 min, which was greatly improved. It was.

(Test Example 4)
A surface-coated chip in which the base material is changed to the following, and a coating layer having the same composition as sample 3-2 in Table 6 is formed by a known PVD method, and then chlorine is contained in the outermost layer using an ion implantation method. A cutting test was performed under the same cutting conditions as in Test Example 3. In any case, the chlorine content in the outermost layer was 0.18 atomic%.
1 JIS standard: P20 cermet cutting tip (T1200A manufactured by Sumitomo Electric Hardmetal Corporation)
2 Ceramic cutting tips (Sumitomo Electric Hardmetal Co., Ltd. W80)
3 Cutting tip made of silicon nitride (NS260 manufactured by Sumitomo Electric Hard Metal Co., Ltd.)
4 Cubic boron nitride cutting tip (BN250 manufactured by Sumitomo Electric Hard Metal Co., Ltd.)
As a result, it was confirmed that all the coated chips were excellent in lubricity and excellent in wear resistance. From this, it can be seen that the tool life can be improved as described above.

  The surface-coated throw-away tip of the present invention is particularly suitable for cutting under a cutting condition in which the cutting edge temperature is high, such as dry machining, high speed, and high feed machining.

Claims (7)

In the surface-coated throw-away tip having a coating layer on the substrate surface,
The coating layer is composed of an inner layer formed on the substrate and an outermost layer formed on the inner layer,
The inner layer is
It has a columnar structure with an aspect ratio of 3 or more, and any one of the orientation indices TC (220), TC (311), and TC (422) of the (220) plane, (311) plane, and (422) plane of the crystal is It has a titanium-containing layer made of TiCN that takes the maximum value of the orientation index,
The outermost layer is
A surface-coated throw-away tip comprising aluminum nitride or aluminum carbonitride and containing chlorine in an outermost layer of more than 0 and 0.5 atomic% or less.   2. The surface-coated throwaway tip according to claim 1, wherein the outermost layer further contains oxygen. Further, the inner layer includes one or more first elements selected from periodic table IVa, Va, VIa group metals, Al, Si, and B, and one or more second elements selected from B, C, N, and O. 3. The surface-coated throw-away tip according to claim 1, further comprising a compound layer made of an element.
However, the compound layer is a layer different from the titanium-containing layer. When the first element is only B, the second element is other than B.   4. The surface-coated throw-away tip according to claim 1, wherein the thickness of the outermost layer is 1/2 or less of the total thickness of the inner layers.   The surface-coated throwaway tip according to any one of claims 1 to 4, wherein the outermost layer has a thickness of 0.03 µm to 10 µm, and the entire coating layer has a thickness of 0.1 µm to 30 µm.   In the outermost layer, the surface roughness of the portion in contact with the work material in the vicinity of the edge portion of the cutting edge is 1.3 μm or less in Rmax with respect to 5 μm measured by a method of observing from the cutting tool cross section. Item 6. The surface-coated throwaway tip according to any one of Items 1 to 5.   The base material is composed of any one of WC-based cemented carbide, cermet, high-speed steel, ceramics, cubic boron nitride sintered body, and silicon nitride sintered body. The surface-coated throw-away tip according to any one of the above.