JP4854359B2 - Surface coated cutting tool - Google Patents

Description

  The present invention relates to a surface-coated cutting tool having a hard coating layer formed on the surface, which has excellent fracture resistance and can also have excellent wear resistance.

Conventionally, surface-coated tools having a hard coating layer formed on the surface of a substrate have been used for various purposes. For example, cutting tools widely used for metal cutting work include a TiC layer, a TiN layer, a TiCN layer, an Al ₂ O ₃ layer, and a TiAlN layer on the surface of a hard substrate such as cemented carbide, cermet, or ceramic. A tool having a single hard coating layer or a plurality of hard coating layers is often used.

  On the other hand, with the recent improvement in cutting efficiency, further improvement in fracture resistance and wear resistance is required. In particular, there is an increasing number of cuttings in which a large impact such as heavy interrupted cutting of metal is applied to the cutting edge. Under such severe cutting conditions, the hard coating layer cannot withstand the large impact with conventional tools, and chipping and hard cutting are difficult. There is a problem in that the coating layer is easily peeled off, which triggers the tool life due to sudden tool damage such as chipping of the cutting edge or abnormal wear.

  Therefore, in order to improve the characteristics of the hard coating layer, Patent Document 1 discloses that a TiCN layer having the highest peak intensity on the (422) plane is formed as the first layer, thereby increasing the adhesion of the TiCN layer. In addition, it is described that the adhesion strength with other hard layers can be increased.

  Patent Document 2 describes that the orientation coefficient in the (422) plane and (311) plane of the crystal plane of the TiCN layer optimizes Tc422 and Tc311 to improve wear resistance and fracture resistance. Has been.

  Furthermore, in Patent Document 3, by gradually changing the ratio of the peak intensity of the (311) plane and the (200) plane in the X-ray diffraction analysis of the TiCN layer in the thickness direction, the wear resistance and fracture resistance of the TiCN layer are improved. It is described to improve.

  Furthermore, Patent Document 4 describes that the service life is prolonged by coating a TiCN layer having the highest peak intensity on the (111) plane.

Further, in Patent Document 5, when the aspect ratio of the crystal grain of the TiCN layer is 6 or more, the TiCN film having a fine columnar crystal structure including the TiCN layer is peeled off by a crack generated in the columnar crystal grain boundary. It is described that suppresses.
Japanese Patent Laid-Open No. 5-220604 JP 1999-140647 A Japanese Patent Laid-Open No. 1995-1000070 JP-A-8-90310 JP 2002-233902 A

  According to Patent Documents 1, 2, and 3, the TiCN layer exhibiting the highest peak intensity on the (422) plane has excellent adhesion to the substrate, wear resistance, and fracture resistance. However, only by optimizing the peak intensity of the crystal plane measured by the X-ray diffraction analysis of the TiCN layer in this way, cutting conditions that are more severe than the cutting conditions described in the examples of the same publication, particularly high-speed In severe cutting conditions that require wear resistance and edge strength, such as rough machining, there is still a problem that the tool life is shortened due to the occurrence of chipping of the cutting edge and the advancement of early wear. It was.

  In Patent Document 4, the TiCN layer having the highest peak intensity on the (111) plane can suppress flank wear. However, with such a configuration alone, there is a problem that it is weak against impact from the layer thickness direction, that is, impact in the vertical direction, and chipping and peeling of the hard coating layer occur.

  Furthermore, in the above-mentioned Patent Document 5, the TiCN film having a fine columnar crystal structure includes a layer in which columnar TiCN particles and granular TiCN particles are mixed as a second layer, and defines the aspect ratio of the third TiCN layer. In this way, peeling due to cracks generated at the columnar grain boundaries is suppressed. However, in such a configuration, there is a problem that it is weak against an impact from the layer thickness direction, and film peeling cannot be sufficiently suppressed.

  Therefore, the present invention has been made to solve the above problems, and exhibits high hardness and excellent wear resistance, which are the characteristics of the columnar crystal TiCN layer, and has high edge strength, particularly from the thickness direction of the layer. The purpose is to provide a surface-coated cutting tool that is strong against impact and has excellent chipping resistance. Especially, the tool cutting blade for cutting metal such as steel, especially high-speed roughing of cast iron is subjected to strong impact and wear resistance. An object of the present invention is to provide a surface-coated cutting tool having excellent chipping resistance and wear resistance even under severe cutting conditions that require high performance.

  As a result of intensive research on the above problems, the present inventor reduced the particle width of the TiCN layer and made the surface of the hard coating layer appropriate, particularly in the impact from the layer thickness direction. It was possible to obtain a high-hardness and high-strength surface-coated cutting tool that was strong, excellent in chipping resistance and wear resistance.

That is, the surface-coated cutting tool of the present invention is the surface-coated cutting tool having a hard coating layer including a titanium carbonitride layer made of columnar particles extending perpendicularly to the substrate on the surface of the substrate. with particles width is 0.01 to 0.1 [mu] m, Ri Rsm is 18 30 .mu.m der which is measured in accordance with JIS B0601'01 of the hard coating layer, Rz of the hard coating layer 3 9 μm, the strongest peak of the titanium carbonitride layer in the X-ray diffraction analysis is a peak representing the (111) crystal plane, and the orientation in the (111) plane of the titanium carbonitride layer calculated by the following formula a surface-coated cutting tool, wherein the coefficient T _C is 1.1 or more.
T _C = [I (111) / I ₀ (111)] [1 / 8Σ (I (hkl) / I ₀ (hkl))] ⁻¹
However,
I (111): X-ray diffraction peak intensity measurement on (111) plane
I ₀ (111): JCPDS card number No. 6-0614 (titanium carbide) and no. Average value of standard X-ray diffraction peak intensity in the (111) plane of the crystal plane described in 6-0642 (titanium nitride)
Σ (I (hkl) / I ₀ (hkl)): [X-rays on (111), (200), (220), (311), (222), (331), (420), (422) planes Diffraction peak intensity measurement value] / [JCPDS card number no. 6-0614 (titanium carbide) and no. Sum of the values of the average value of standard X-ray diffraction peak intensities described in 6-0642 (titanium nitride)]

In addition, when the Rz of the hard coating layer is 3 to 9 μm, the grain growth direction of the TiCN layer can be optimized, and the strength of the TiCN layer against the impact from the thickness direction of the TiCN layer is improved. it welding can be prevented it is, is important because it can improve the chipping resistance and welding resistance of the surface-coated cutting tool.

Furthermore, when the strongest peak of the titanium carbonitride layer in the X-ray diffraction analysis is a peak representing the (111) crystal plane, the crystal bond of the titanium carbonitride layer is further stabilized, and the strength of the titanium carbonitride layer is increased. This is important because flank wear can be suppressed and flank wear can be suppressed.

Here, by orientation coefficient T _C in (111) plane of the titanium carbonitride layer which is calculated by the formula shown below is 1.1 or more, the contact area between the particles of the titanium carbonitride layer is increased Accordingly, the greater the energy required to break the titanium carbonitride layer, it is possible to further increase the strength of the titanium carbonitride layer is important because it can improve the abrasion resistance of the surface-coated cutting tool .
T _C = [I (111) / I ₀ (111)] [1 / 8Σ (I (hkl) / I ₀ (hkl))] ⁻¹
However,
I (111): X-ray diffraction peak intensity measurement on (111) plane
I ₀ (111): JCPDS card number No. 6-0614 (titanium carbide) and no. Average value of standard X-ray diffraction peak intensity in the (111) plane of the crystal plane described in 6-0642 (titanium nitride)
Σ (I (hkl) / I ₀ (hkl)): [X-rays on (111), (200), (220), (311), (222), (331), (420), (422) planes Diffraction peak intensity measurement value] / [JCPDS card number no. 6-0614 (titanium carbide) and no. Sum of the values of the average value of standard X-ray diffraction peak intensities described in 6-0642 (titanium nitride)]

Before by a range of aspect ratios of 10 to 500 particles constituting the Kisumi titanium nitride layer, it is possible to increase both the hardness and strength of the titanium carbonitride layer, both wear resistance and chipping resistance It is desirable because it can be made excellent.

  Further, it is desirable that the thickness of the titanium carbonitride layer be in the range of 3 to 10 μm because it is possible to prevent peeling of the hard coating layer and to obtain sufficient wear resistance.

According to the surface-coated tool of the present invention, in the surface-coated cutting tool having a hard coating layer including a titanium carbonitride layer made of columnar particles extending perpendicularly to the substrate on the surface of the substrate, the particles of the titanium carbonitride layer With a width of 0.01 to 0.1 μm and an Rsm of the hard coating layer of 18 to 30 μm, a high hardness and high strength titanium carbonitride layer that is particularly resistant to impact from the layer thickness direction, Since it becomes a hard coating layer with high wear resistance and chipping resistance, it is required to have wear resistance such as high-speed rough machining, and even for cutting conditions where a heavy load is applied to the cutting edge, Abrasion resistance can be increased, and chipping and peeling of the blade edge can be reduced.

  Therefore, it has excellent chipping resistance even under severe cutting conditions such as cutting of metals such as steel, especially high-speed roughing of cast iron, etc. A surface-coated cutting tool having wear resistance can be obtained.

  A throw-away tip type surface-coated cutting tool (hereinafter simply referred to as a tool) 1 for turning which is an embodiment of the present invention will be described.

  The tool 1 of the present invention comprises a substantially flat substrate having a rake face on the main surface and a flank face on the side face, and a cutting edge at the crossing ridge line between the rake face and the flank face.

  A hard coating layer is formed on the surface of the substrate by a known film formation method such as chemical vapor deposition (CVD) or physical vapor deposition (PVD). In the present embodiment, the film formation by CVD will be described as an example.

Here, the tool 1 of the present invention is a surface-coated cutting tool having a hard coating layer including a titanium carbonitride layer made of columnar particles extending perpendicularly to the substrate on the surface of the substrate. The width is 0.01 to 0.1 μm, and the Rsm of the hard coating layer is 18 to 30 μm.

  By adopting such a configuration, it is possible to change the growth direction of the titanium carbonitride layer particles along the waviness of the base material by optimizing the particle width of the titanium carbonitride layer particles and the Rsm of the hard coating layer. Therefore, the impact applied from the thickness direction of the layer can be dispersed, and chipping of the hard coating layer can be prevented.

  In other words, when the particle width of the titanium carbonitride layer particles is less than 0.01 μm, the adhesion between the titanium carbonitride layer and the substrate is reduced, and film peeling tends to occur. Will occur.

  On the other hand, when the particle width of the titanium carbonitride layer particles exceeds 0.5 μm, it becomes difficult for the titanium carbonitride layer particles to grow along the waviness of the base material, and the hardness of the titanium carbonitride layer becomes insufficient. Wear resistance will decrease.

Furthermore, if the Rsm of the hard coating layer is less than 18 μm, the columnar crystal aspect ratio is difficult to increase, the columnar crystal orientation tends to be random, the strength of the titanium carbonitride layer decreases, and the direction from the rake face direction is reduced. Chipping resistance due to impact or load is reduced.

  On the other hand, when the Rsm of the hard coating layer exceeds 30 μm, the growth direction of the titanium carbonitride layer crystal is substantially perpendicular to the boundary surface between the base material and the hard coating layer, and the thickness direction of the titanium carbonitride layer, that is, the base material It becomes difficult to suppress cracking in the direction perpendicular to the boundary surface of the hard coating layer, the strength of the titanium carbonitride layer also decreases, and chipping resistance due to impact and load from the layer thickness direction decreases.

  Here, as a method for measuring the particle width of the titanium carbonitride layer, the cut surface or fracture surface of the tool 1 including the titanium carbonitride layer is observed with a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like. In the obtained image, a line segment A parallel to the substrate is drawn at the middle part of the thickness of the titanium carbonitride layer, the number of intersections between the line segment A and the grain boundary of the titanium carbonitride layer is calculated, and the length of the line segment A Is divided by the number of intersections.

  The above measurement is performed at five or more locations at different measurement locations, and the average of the obtained values is taken as the average particle width of the titanium carbonitride layer.

  Further, as a method for measuring the surface roughness Rsm of the hard coating layer, the honing process part is in the range of 300 μm from the blade edge to the center of the rake surface on the surface of the hard coating layer, that is, the rake face which is the tool surface. In addition to the above, measurement was performed with a stylus type surface roughness measuring instrument in accordance with JIS B0601'01.

  In addition, when the breaker groove for chip disposal is provided on the rake face of the tool 1, the surface roughness Rsm of the hard coating layer is measured by the above method also in the breaker groove portion that is subjected to impact or load by cutting. There is no problem.

By setting the Rz of the hard coating layer to 3 to 9 μm, the grain growth direction of the TiCN layer can be optimized, and the strength of the TiCN layer against the impact from the thickness direction of the TiCN layer can be improved. And the chipping resistance of the surface-coated cutting tool can be improved.

  Here, if the Rz of the hard coating layer is less than 1 μm, the TiCN layer is weak against impact in the thickness direction of the TiCN layer, that is, the direction perpendicular to the interface between the base material and the coating, and the hard coating layer is cracked. It becomes easy.

  On the other hand, if the Rz of the hard coating layer is larger than 5 μm, the unevenness of the tool surface becomes large and welding is likely to occur.

  Note that the surface roughness Rz of the hard coating layer is measured on the surface of the hard coating layer, that is, on the rake face that is the tool surface, from the cutting edge to the rake face, in the same manner as the Rsm measurement method of the hard coating layer described above. In the range of 300 μm toward the center, it can be measured in accordance with JIS B0601′01 with a stylus type surface roughness measuring instrument in a portion other than the honing processed portion.

  Further, when the crystal plane showing the strongest peak of the titanium carbonitride layer in the X-ray diffraction analysis is other than the (111) plane, the bond between the particles of the titanium carbonitride layer becomes weak, and the strength of the titanium carbonitride layer decreases. The flank wear of the tool tends to increase.

By orientation coefficient T _c in (111) plane of the titanium carbonitride layer which is calculated by the formula shown below is 1.1 or more, by the increase in contact area between the particles of the titanium carbonitride layer, charcoal The energy required for breaking the titanium nitride layer is increased, the strength of the titanium carbonitride layer can be increased, and the wear resistance of the surface-coated cutting tool can be improved.
T _C = [I (111) / I ₀ (111)] [1 / 8Σ (I (hkl) / I ₀ (hkl))] ⁻¹
However,
I (111): X-ray diffraction peak intensity measurement on (111) plane
I ₀ (111): JCPDS card number No. 6-0614 (titanium carbide) and no. Average value of standard X-ray diffraction peak intensity in the (111) plane of the crystal plane described in 6-0642 (titanium nitride)
Σ (I (hkl) / I ₀ (hkl)): [X-rays on (111), (200), (220), (311), (222), (331), (420), (422) planes Diffraction peak intensity measurement value] / [JCPDS card number no. 6-0614 (titanium carbide) and no. Sum of the values of the average value of standard X-ray diffraction peak intensities described in 6-0642 (titanium nitride)]

In here, when measuring the crystal plane indicating the strongest peak by X-ray diffraction analysis of the titanium carbonitride layer, using the Kα line is measured up to 20 degrees to 150 degrees. The X-ray diffraction peak intensity in the range of 300 μm from the cutting edge and the cutting edge on the rake face toward the center of the rake face is measured by a fine X-ray diffraction analysis (micro XRD). In the case where the hard coating layer has a multilayer structure, it is possible to measure the exposed surface of the exposed TiCN layer by micro XRD after removing the layer above the TiCN layer by a method such as polishing.

  By setting the aspect ratio of the particles constituting the titanium carbonitride layer within a range of 10 to 500, both the hardness and strength of the titanium carbonitride layer can be increased, and both wear resistance and chipping resistance are excellent. Can be.

  Here, the method for measuring the aspect ratio can be calculated by dividing the layer thickness of the titanium carbonitride layer by the particle width calculated by the method for measuring particle width. The layer thickness of the titanium carbonitride layer is measured by observing an arbitrary cut surface or fractured surface including the titanium carbonitride layer with a scanning electron microscope (SEM), a transmission electron microscope (TEM), It is set as the average value of the layer thickness in each arbitrary five places.

  By making the thickness of the titanium carbonitride layer in the range of 3 to 10 μm, it is desirable because it prevents peeling of the hard coating layer and sufficient wear resistance can be obtained.

  Further, as the hard coating layer formed on the tool 1, in addition to the titanium carbonitride layer, metals of Group 4, 5, 6 elements, aluminum, zirconium, hafnium carbide, nitride, oxide, carbonitride By using a multilayer film in which layers of carbon oxide, nitrogen oxide, and carbonitride oxide are laminated, the strength, hardness and oxidation resistance of the hard coating layer and the adhesion of the titanium carbonitride layer are further improved. be able to.

  In particular, the lowermost layer made of titanium nitride is formed on the surface of the substrate, and by forming the titanium carbonitride layer directly on the lowermost layer, the adhesion of the titanium carbonitride layer can be improved, It is desirable because it is possible to prevent the base material components from diffusing into the titanium carbonitride layer and reducing the strength and hardness of the titanium carbonitride layer.

  Furthermore, when the strongest peak in the X-ray diffraction analysis of the lowermost layer is a peak representing the (111) crystal plane, the adhesion of the titanium carbonitride layer can be improved, and the titanium carbonitride formed directly above The strongest peak in the X-ray diffraction analysis of the layer can be easily adjusted to the (111) crystal plane.

  Examples of the hard material constituting the substrate used in the tool 1 of the present invention include a cemented carbide or a cermet in which a hard phase is bonded with a bonded phase made of an iron group metal such as cobalt (Co) and / or nickel (Ni). A hard alloy consisting of As the hard phase, for example, selected from the group of tungsten carbide (WC), titanium carbide (TiC) or TiCN (TiCN) and, if desired, carbides, nitrides, and carbonitrides of Group 4, 5, and 6 metals of the periodic table It consists of at least one kind.

As other examples of the hard material constituting the substrate, for example, silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ ) ceramic sintered body, cubic boron nitride (cBN), and diamond are mainly used. The super-hard sintered body and the like can also be applied.

  As the tool of the present invention, it is desirable to use the hard alloy because high cutting performance can be exerted on a wide variety of work materials.

(Production method)
Next, a method for manufacturing the above-described surface-coated cutting tool according to an embodiment of the present invention will be described.

  First, metal powder, carbon powder, etc. are appropriately added to metal powders, nitrides, carbonitrides, oxides, and other inorganic powders that can be formed by firing the hard alloy described above, and mixed powders are prepared. .

  Here, according to the present invention, the produced mixed powder is molded into a predetermined tool shape by die press molding to produce a molded body. The surface roughness, Rsm, of the die surface used at this time is 7 -28 μm, preferably the surface state when the produced molded body is sintered is adjusted within the range of the present invention by using a material in which Rz is adjusted in the range of 0.8-4 μm in addition to Rsm. Can be adjusted easily.

  Next, the produced compact is fired in a vacuum or in a non-oxidizing atmosphere to produce a substrate made of the hard material described above.

  Then, polishing or honing of the cutting edge portion is performed on the surface of the base as desired. At this time, using a relatively soft abrasive such as silicon carbide, the blade edge treatment is performed by adjusting the angle so that only the blade edge hits the grinding wheel. As a result, the surface state of the sintered body after firing can be prevented from changing on the surface of the substrate, and a tool having a hard coating layer having a surface configuration within the scope of the present invention can be created. it can.

Next, a hard coating layer is formed on the surface of the produced sintered body by, for example, chemical vapor deposition (CVD). First, a mixed gas composed of titanium chloride (TiCl ₄ ) gas of 0.1 to 10% by volume, nitrogen (N ₂ ) gas of 5 to 60% by volume, and the balance of hydrogen (H ₂ ) gas as a reaction gas composition is prepared. Then, it is introduced into the reaction chamber, and a TiN layer as a base layer is formed in the chamber under conditions of 800 to 1000 ° C. and 10 to 30 kPa.

Next, as a reaction gas composition, titanium chloride (TiCl ₄ ) gas is 0.1 to 10% by volume, nitrogen (N ₂ ) gas is 5 to 60% by volume, and methane (CH ₄ ) gas is 0 to 0 by volume%. 0.1% by volume, 0.1% to 2% by volume of acetonitrile (CH ₃ CN) gas, a flow rate ratio of TiCl 4 gas to acetonitrile gas in the range of 0.5 to 6, and the remainder from hydrogen (H ₂ ) gas The mixed gas is adjusted and introduced into the reaction chamber, and a TiCN layer is formed under conditions of a film formation temperature of 780 to 950 ° C. and 5 to 25 kPa.

Next, an intermediate layer is formed as desired. For example, when a TiCNO layer is formed as an intermediate layer, titanium chloride (TiCl ₄ ) gas is 0.1 to 3% by volume, methane (CH ₄ ) gas is 0.1 to 10% by volume, carbon dioxide (CO ₂ ) A mixed gas composed of 0.01 to 5% by volume of gas, 0 to 60% by volume of nitrogen (N ₂ ) gas, and the remaining hydrogen (H ₂ ) gas is prepared and introduced into the reaction chamber. 800-1100 ° C., 5-30 kPa.

Subsequently, an Al ₂ O ₃ layer is formed. As a method for forming the Al ₂ O ₃ layer, ₃ to 20% by volume of aluminum chloride (AlCl ₃ ) gas, 0.5 to 3.5% by volume of hydrogen chloride (HCl) gas, and carbon dioxide (CO ₂ ) gas 0.01 to 5.0% by volume, hydrogen sulfide (H ₂ S) gas is 0 to 0.01% by volume, and the balance is hydrogen (H ₂ ) gas. 10 kPa is desirable.

In order to form a surface layer (TiN layer), the reaction gas composition is titanium chloride (TiCl ₄ ) gas of 0.1 to 10% by volume, nitrogen (N ₂ ) gas of 5 to 60% by volume, and the remainder is hydrogen. A mixed gas composed of (H ₂ ) gas may be adjusted and introduced into the reaction chamber, and the inside of the chamber may be set to 800 to 1100 ° C. and 5 to 85 kPa.

  Then, if desired, at least the cutting edge portion of the surface of the formed hard coating layer is polished. By this polishing process, the residual stress remaining in the hard coating layer is released, and the tool is further excellent in fracture resistance.

  The present invention is not limited to the above embodiment. For example, in the above description, the case where the chemical vapor deposition (CVD) method is used as the film forming method has been described. It may be formed by a physical vapor deposition (PVD) method.

  For example, even when a TiCN layer is formed by an ion plating method, by controlling the structure of the TiCN layer within the above-described range, it is possible to produce a tool having excellent fracture resistance and excellent wear resistance. it can.

7% by mass of metallic cobalt (Co) powder with an average particle size of 1.5 μm, 0.5% by mass of titanium carbide (TiC) powder with an average particle size of 2.0 μm, 1.0 carbonized with titanium nitride (TiN) powder Tungsten carbide (3.0% by mass of tantalum (TaC) powder, 1.0% by mass of zirconium carbide (ZrC) powder, 1.5% by mass of niobium carbide (NbC) powder, and the remainder having an average particle size of 1.5 μm ( WC) Each was added and mixed in a proportion of powder. The obtained mixed powder was molded into a cutting tool shape (CNMA12041) by press molding using a mold having the surface roughness shown in Table 1, and a molded body was produced. Thereafter, the obtained compact was subjected to a binder removal treatment and fired at 1500 ° C. for 1 hour in a vacuum of 0.01 Pa to produce a cemented carbide. Further, the prepared cemented carbide was subjected to cutting edge processing (Honing R) under the processing conditions shown in Table 1, and the base material sample No. 1 to 7 base materials were produced.

Next, a hard coating layer composed of a multilayer film having a structure shown in Table 2 was formed on the base material by CVD, and various sample coating layers were formed. 1 to 8 tools were produced. The deposition conditions for each layer in Table 2 are shown in Table 3.

About the obtained tool, the layer above the TiCN layer was removed from the hard coating layer by polishing, and the exposed surface of the TiCN layer in the vicinity of the blade edge was subjected to X-ray diffraction measurement. For X-ray diffraction measurement, X-ray output was performed using Cu-Kα ray at a voltage of 40 kV and a current of 200 mA using a micro X-ray diffractometer PSPC / MDG-2000 manufactured by Rigaku Corporation. The collimator diameter was 30 μm Micro X-ray diffraction measurement was performed under the conditions of sampling time of 11990 seconds and step width of 0.02 °. In the diffraction chart, the crystal plane showing the strongest peak of the titanium carbonitride layer was determined using the data subjected to the Kα ray removal treatment. Also, the measured peak intensity by applying the above equation to calculate the orientation coefficient T _C in (111) crystal plane of TiCN layer. The results are shown in Table 4.

  Further, for the obtained tool, the surface roughness Rz and Rsm of the hard coating layer were measured with a stylus type surface roughness measuring instrument in accordance with JIS B0601'01. The results are shown in Table 4. Further, the particle width of TiCN particles was calculated by the above method, and the average particle width is shown in Table 4 as the particle width of TiCN.

  Further, the aspect ratio of the TiCN particles was calculated by measuring the layer thickness of the TiCN layer as described above and using the layer thickness and the particle width of the TiCN. The results are shown in Table 4.

  Then, using this cutting tool, a continuous cutting test and an intermittent cutting test were performed under the following conditions to evaluate the wear resistance and fracture resistance.

(Continuous cutting conditions)
Work Material: Ductile Cast Iron Sleeve Material (FCD700)
Tool shape: CNMA120204
Cutting speed: 250 m / min Feeding speed: 0.3 mm / rev
Cutting depth: 2mm
Cutting time: 20 minutes Others: Use of water-soluble cutting fluid Evaluation item: After cutting for 20 minutes, observe the cutting edge with a microscope and measure the amount of flank wear and tip wear (intermittent cutting conditions)
Work material: Ductile cast iron 4-slot sleeve material (FCD700)
Tool shape: CNMA120204
Cutting speed: 250 m / min Feeding speed: 0.3 to 0.5 mm / rev
Cutting depth: 2mm
Other: Use of water-soluble cutting fluid Evaluation item: Number of impacts leading to breakage
Observe the peeling state of the hard coating layer of the cutting edge with a microscope at the point of impact 1000 times

Table 4 shows that the sample width of the titanium carbonitride layer particles or the surface roughness Rsm of the hard coating layer is not within the scope of the present invention. In Nos. 6 to 8, chipping occurred early on the cutting edge, and both wear resistance and fracture resistance were insufficient. In Tables 2 and 4, Sample No. 1-3 is a reference example, sample No. 6-8 shows a comparative example sample.

  On the other hand, according to the present invention, in accordance with the present invention, Sample No. In Nos. 1 to 5, the chipping of the cutting edge hardly occurred, and excellent wear resistance and fracture resistance were exhibited, and the cutting performance was excellent.

Claims (3)

In the surface-coated cutting tool having a hard coating layer including a titanium carbonitride layer composed of columnar particles extending perpendicularly to the substrate on the surface of the substrate, the particle width of the titanium carbonitride layer is 0.01 to 0.1 μm. with it, the Rsm is measured according to JIS B0601'01 the hard layer Ri is 18 30 .mu.m der, Rz of the hard coating layer 3～9Myuemu, said titanium carbonitride layer of X-ray diffraction analysis of the strongest peak, that (111) with a peak representing a crystal plane, orientation coefficient T _C in (111) plane of the titanium carbonitride layer which is calculated by the formula shown below is 1.1 or more A surface-coated cutting tool.
T _C = [I (111) / I ₀ (111)] [1 / 8Σ (I (hkl) / I ₀ (hkl))] ⁻¹
However,
I (111): X-ray diffraction peak intensity measurement on (111) plane
I ₀ (111): JCPDS card number No. 6-0614 (titanium carbide) and no. Average value of standard X-ray diffraction peak intensity in the (111) plane of the crystal plane described in 6-0642 (titanium nitride)
Σ (I (hkl) / I ₀ (hkl)): [X-rays on (111), (200), (220), (311), (222), (331), (420), (422) planes Diffraction peak intensity measurement value] / [JCPDS card number no. 6-0614 (titanium carbide) and no. Sum of the values of the average value of standard X-ray diffraction peak intensities described in 6-0642 (titanium nitride)] The surface-coated cutting tool according to claim 1 , wherein an aspect ratio of particles constituting the titanium carbonitride layer is in a range of 10 to 500. The surface-coated cutting tool according to claim 1 or 2 , wherein a layer thickness of the titanium carbonitride layer is in a range of 3 to 10 µm.