JP2011224715A - Surface-coated cutting tool with hard coating layer for exhibiting excellent abrasion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool with a hard coating layer for exhibiting excellent abrasion resistance, in the high speed intermittent cutting work of high hardness steel.SOLUTION: The surface-coated cutting tool is provided by depositing and forming the hard coating layer formed of (Al, Ti)N on a surface of a tool base body constituted of tungsten carbide group cemented carbide or titanium carbonitride group cermet. The hard coating layer is constituted as an alternate laminated structure of a thin layer A constituted of a granular crystal (Al, Ti)N and a thin layer B constituted of a columnar crystal (Al, Ti)N. The thin layer A and the thin layer B have layer thicknesses of 0.05-2 μm. The crystal grain size of the granular crystal is 30 nm or smaller, and the crystal grain size of the columnar crystal is 50-500 nm.

Description

  In the present invention, for example, a high hardness steel such as a hardened material of an alloy tool steel is cut under high-speed intermittent cutting conditions that cause high heat generation and an intermittent and impact load acts on the cutting edge portion. Even when the hard coating layer has excellent high-temperature hardness and high-temperature strength, it prevents the occurrence of chipping, chipping, peeling, etc., and surface-coated cutting that exhibits excellent wear resistance over a long period of use The present invention relates to a tool (hereinafter referred to as a coated tool).

  In general, surface-coated cutting tools include a throw-away tip that is detachably attached to the tip of a cutting tool for turning and planing of various steels and cast irons, and drilling of the work material. There are drills and miniature drills used for processing, etc., and solid type end mills used for chamfering, grooving, shoulder processing, etc. of the work material. A slow-away end mill tool that performs cutting work in the same manner as a type end mill is known.

  Conventionally, as one of surface-coated cutting tools, for example, as shown in Patent Document 1 and Patent Document 2, tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN). A coated tool in which an Al—Ti composite nitride layer is formed as a hard coating layer on the surface of a substrate composed of a base cermet (hereinafter collectively referred to as a tool substrate) is known. These coated tools are known to exhibit excellent wear resistance over long periods of use.

  Furthermore, the above-mentioned conventional coated tool is, for example, a state in which a tool base is inserted into an arc ion plating (AIP) apparatus, which is a kind of physical vapor deposition apparatus shown in FIG. An arc discharge is generated between the cathode electrode (evaporation source) having a composition corresponding to the composition of the hard coating layer and the anode electrode, and nitrogen gas is introduced as a reaction gas into the apparatus at the same time. , By depositing a hard coating layer made of an (Al, Ti) N layer having a desired layer thickness and composition.

Japanese Patent No. 2644710 JP 2009-56540 A

  In recent years, the performance of cutting devices has been dramatically improved, while on the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting, and with this, cutting tends to be faster. In the case of a coated tool, when it is used under high-speed intermittent cutting conditions of high-hardness steel that involves particularly high heat generation and intermittent and impact loads are applied to the cutting edge, chipping is applied to the hard coating layer. Defects, peeling, etc. are likely to occur, and as a result, the service life is reached in a relatively short time.

  Therefore, the present inventors, from the viewpoint as described above, with high-temperature hardness with a hard coating layer, as well as high-temperature steel with a particularly superior high-temperature strength, particularly high-hardness steel such as a hardened material of alloy tool steel, Even when cutting is performed under high-speed interrupted cutting conditions where intermittent and impact loads are applied to the cutting edge with high heat generation, it can be used for a long time without causing chipping, chipping or peeling. As a result of conducting research focusing on the crystal structure of the (Al, Ti) N layer that constitutes the hard coating layer in order to develop a coated tool that exhibits excellent wear resistance, the following knowledge was obtained. Obtained.

The Ti component, which is a constituent component of the (Al, Ti) N layer constituting the hard coating layer of the above conventional coated tool, improves the high temperature strength, and the Al component has the effect of improving the high temperature hardness, And a hard coating layer exhibits predetermined | prescribed chipping resistance, abrasion resistance, etc. by containing these each component.
By the way, in the conventional coated tool, no particular attention is paid to the crystal grain structure (particle size, form) of the hard coating layer formed of (Al, Ti) N. Even in Patent Document 2, there is no mention of the crystal grain structure, and the relation between the crystal grain structure and the film forming conditions (for example, arc ion plating conditions) is not clarified.

Therefore, the present inventors diligently studied the relationship between the crystal grain structure and the film formation conditions, and by controlling the film formation conditions (for example, arc ion plating conditions) in the film formation process, For example, specifically, a thin layer A composed of a fine grain size (Al, Ti) N granular crystal structure and a relatively large grain size (Al, Ti) N It has been found that a hard coating layer can be formed by an alternately laminated structure with a thin layer B having a columnar crystal structure.
In addition, the thin layer A composed of the granular crystal structure is excellent in wear resistance, the thin layer B composed of a columnar crystal structure is excellent in chipping resistance and chipping resistance, and the thin layer A and the thin layer B are the same. Since the component composition is the same crystal structure, the adhesion strength between the thin layers is large and there is no risk of delamination, so the hard coating layer composed of the alternately laminated structure of the thin layers A and B is high. Exhibits excellent wear resistance over a long period of use without causing chipping, chipping, or peeling even under high-speed intermittent cutting conditions that generate intermittent heat and impact load on the cutting edge. I found out.

This invention has been made based on the above findings,
“(1 A hard coating layer made of a composite nitride of Al and Ti having a layer thickness of 0.8 to 5.0 μm is deposited on the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet. In the formed surface-coated cutting tool,
The hard coating layer is configured as an alternate laminated structure of thin layers A composed of a granular crystal structure of Al and Ti composite nitride and thin layers B composed of a columnar crystal structure, and each of the thin layers A and B is 0 The average crystal grain size of the granular crystals constituting the thin layer A is 30 nm or less, and the average crystal grain size of the columnar crystals constituting the thin layer B is 50 to A surface-coated cutting tool having a thickness of 500 nm.
(2) The composite nitride of Al and Ti is
Composition _{formula: (Al 1-X Ti X} ) N
The surface-coated cutting tool according to (1), wherein 0.40 ≦ X ≦ 0.65 (where X is an atomic ratio) is satisfied. "
It has the characteristics.

  Next, the hard coating layer of the coated tool of the present invention will be described in more detail.

(A) Composition of the hard coating layer The hard coating layer composed of the (Al, Ti) N layer has a crystal structure that changes from cubic to hexagonal due to an increase in the Al content ratio, and the film hardness decreases. In order to maintain at least a predetermined film hardness, the crystal structure needs to be cubic, and for that purpose, the composition of the hard coating layer is
Composition _{formula: (Al 1-X Ti X} ) N
When X exceeds 0.65 (where X is an atomic ratio), the high-temperature hardness becomes insufficient and wear resistance decreases, so X may be 0.65 or less. desirable. However, when X is less than 0.40, the crystal structure remains in a cubic form, but the high temperature strength of the (Al, Ti) N layer itself decreases due to the decrease in the relative Ti content, and chipping is caused. Since it becomes easy to generate defects, the content ratio X (atomic ratio) of Ti in the total amount of Al and Ti in the (Al, Ti) N layer constituting the hard coating layer is 0.40 ≦ X ≦ It is desirable to satisfy 0.65.

(B) Thin layer A
The thin layer A is made of (Al, Ti) N having a granular crystal structure, has an excellent film hardness, and improves the wear resistance of the hard coating layer. However, if the average crystal grain size of the granular crystal structure exceeds 30 nm, the effect of improving the hardness of the film is reduced, so the average crystal grain size of the granular crystal structure is set to 30 nm or less.
The “average crystal grain size” as used in the present invention is measured and calculated by a transmission electron microscope (TEM) observation photograph on a plane orthogonal to the layer thickness direction (in other words, a plane parallel to the substrate surface). The average value of the crystal grain size is referred to, and the length of the crystal grain along the layer thickness direction is not called “average crystal grain size” in the present invention.
Further, if the layer thickness of the thin layer A is less than 0.05 μm, the effect of improving the wear resistance is small. On the other hand, if the layer thickness exceeds 2 μm, the cutting blade has a high hardness that causes intermittent and high impact loads. Since it becomes easy to generate chipping and chipping by heavy intermittent cutting of steel, the layer thickness of the thin layer A is set to 0.05 to 2 μm.

(C) Thin layer B
The thin layer B composed of (Al, Ti) N having a columnar crystal structure exhibits excellent high-temperature strength and toughness, but the average crystal grain size of (Al, Ti) N of the columnar crystal structure constituting the thin layer B is 500 nm. If the average particle diameter is less than 50 nm, the effect of improving chipping resistance and chipping resistance is not seen. Therefore, the thin layer B is formed. The average grain size of (Al, Ti) N having a columnar crystal structure was determined to be 50 to 500 nm.
Further, if the layer thickness of the thin layer B is less than 0.05 μm, the effect of improving chipping resistance and fracture resistance is small. On the other hand, if the layer thickness exceeds 2 μm, the wear resistance is significantly reduced. The layer thickness of B was set to 0.05 to 2 μm.

(D) Alternating lamination of thin layer A and thin layer B The hard coating layer of the present invention consisting of alternating lamination of thin layer A and thin layer B has the thin layer A having a granular crystal structure, while the thin layer B has a columnar crystal structure. However, although the crystal grain forms are different, since it is configured as a hard coating layer having the same component system and the same crystal structure (cubic crystal), it is possible to alternately stack thin layers A and B of different component systems. In comparison, the adhesion strength between the thin layer A and the thin layer B is large, and not only contributes to the high temperature strength improvement as the entire hard coating layer, but also there is no risk of delamination, etc., accompanied by high heat generation, In addition, it exhibits excellent chipping resistance, chipping resistance, and peel resistance even under high-speed intermittent cutting conditions in which intermittent and impact loads are applied to the cutting edge.
However, if the total thickness of the hard coating layer composed of the alternating layers of the thin layer A and the thin layer B is less than 0.8 μm, the excellent wear resistance of the hard coating layer cannot be exhibited over a long period of time, so that the tool life is short-lived. On the other hand, if the total layer thickness exceeds 5.0 μm, chipping and defects are likely to occur. Therefore, the total layer thickness is set to 0.8 to 5.0 μm.

  In the coated tool of the present invention, the hard coating layer has a thin layer A composed of an (Al, Ti) N layer having a granular crystal structure having excellent film hardness, and a columnar crystal structure having excellent high-temperature strength and toughness ( Since it is configured as an alternate laminated structure of thin layers B made of Al, Ti) N layers, the hard coating layer as a whole has excellent high temperature hardness and much higher temperature strength, and as a result, an alloy The hard coating layer has excellent chipping resistance and high resistance even under high-speed intermittent cutting conditions in which intermittent and impact loads are applied to the cutting edge part with high heat generation of hardened steel such as tool steel quenching materials. In addition to having chipping and peeling resistance, it exhibits excellent wear resistance over a long period of use.

The arc ion plating apparatus used for forming the hard coating layer which comprises a surface coating cutting tool is shown, (a) is a schematic plan view, (b) is a schematic front view.

  Next, the coated tool of the present invention will be specifically described with reference to examples.

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders are blended into the composition shown in Table 1, wet mixed by a ball mill for 72 hours, dried, and then pressed into a green compact at a pressure of 100 MPa. Medium, sintered at 1400 ° C for 1 hour, after sintering, WC-based carbide with honing of R: 0.03 on the cutting edge and chip shape of ISO standard CNMG120408 Alloy tool bases A-1 to A-10 were formed.

In addition, as raw material powders, all are TiCN (weight ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and then pressed into a compact at a pressure of 100 MPa. The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to obtain ISO standard / CNMG120408. Tool bases B-1 to B-6 made of TiCN-based cermet having the following chip shape were formed.

(A) Next, each of the tool bases A-1 to A-10 and B-1 to B-6 is ultrasonically cleaned in acetone and dried, and then the arc ion plating shown in FIG. An Al—Ti alloy having a predetermined component composition is mounted as a cathode electrode (evaporation source) at a position spaced apart from the central axis on the rotary table in the apparatus along the outer periphery in a radial direction. Placed opposite to each other,
(B) First, the inside of the apparatus is heated to 500 ° C. with a heater while the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, and then the tool base that rotates while rotating on the rotary table is −1000 V. A DC bias voltage was applied, and an arc discharge was generated by flowing a current of 100 A between the cathode electrode and the anode electrode made of one Al—Ti alloy, and the tool base surface was bombard washed.
(C) Next, the pressure of nitrogen gas as a reaction gas introduced into the apparatus is adjusted to a condition within the range of 5 to 7 Pa as shown in Table 3, and the same as the tool base rotating while rotating on the rotary table. As shown in Table 3, with a DC bias voltage in the range of −100 to −300 V being applied, a predetermined current in the range of 50 to 100 A is passed between the cathode electrode and the anode electrode of the Al—Ti alloy. An arc discharge is generated, and a thin layer A composed of an (Al, Ti) N layer having a granular crystal structure having a predetermined layer thickness is formed on the surface of the tool base by vapor deposition.
(D) Next, the pressure of the nitrogen gas is adjusted to a condition in the range of 2 to 4 Pa as shown in Table 3, and the tool base that rotates while rotating on the rotary table is also set to -20 to 20 as shown in Table 3. In a state where a DC bias voltage in the range of −90 V is applied, a predetermined current in the range of 50 to 100 A is caused to flow between the cathode electrode and the anode electrode of the Al—Ti alloy to generate arc discharge, Forming a thin layer B composed of (Al, Ti) N layers having a columnar crystal structure of a predetermined layer thickness on the surface of the thin layer A;
(E) The formation of the thin layer A and the formation of the thin layer B are alternately repeated, so that the predetermined composition comprising the laminated structure of the thin layers A and B shown in Tables 4 and 5 on the surface of the tool base. The surface coated carbide throwaway tips (hereinafter referred to as the present invention coated carbide tips) 1 to 16 of the present invention were produced by vapor-depositing a hard coating layer having a predetermined crystal grain structure and a predetermined layer thickness, respectively.

  For comparison purposes, these tool bases A-1 to A-10 and B-1 to B-6 were ultrasonically cleaned in acetone and dried, respectively, and the arc ion plating shown in FIG. A Cr-Al-Ti alloy with a predetermined composition is attached as a cathode electrode (evaporation source), and the inside of the apparatus is first evacuated and maintained at a vacuum of 0.1 Pa or less with a heater. Is heated to 500 ° C., a DC bias voltage of −1000 V is applied to the tool base, and an arc discharge is generated by applying a current of 100 A between the Cr—Al—Ti alloy of the cathode electrode and the anode electrode. Thus, the surface of the tool base is bombarded and then nitrogen gas is introduced as a reaction gas into the apparatus to adjust the pressure conditions shown in Table 3 and rotate while rotating on the rotary table. In the state where the DC bias voltage shown in Table 3 is applied to the tool base, arc discharge is generated between the cathode electrode and the anode electrode of the Cr-Al-Ti alloy, and the tool bases A-1 to A- By vapor-depositing a hard coating layer composed of an (Al, Ti) N layer having the composition, crystal grain structure and layer thickness shown in Tables 6 and 7 on the surfaces of 10 and B-1 to B-6 Comparative surface coated carbide throwaway tips (hereinafter referred to as comparative coated carbide tips) 1 to 16 were produced.

Next, the coated carbide chips 1 to 16 of the present invention and the comparative coated carbide chip 1 are compared with the above-mentioned various coated carbide chips, all of which are screwed to the tip of the tool steel tool with a fixing jig. About ~ 16
Work material: JIS / SKD61 hardened material (HRC52) in the longitudinal direction, four equally spaced round bars,
Cutting speed: 60 m / min. ,
Cutting depth: 0.25 mm,
Feed: 0.1 mm / rev. ,
Cutting time: 45 minutes,
Dry high-speed intermittent cutting test of alloy steel under the conditions (cutting condition A) (normal cutting speed is 30 m / min),
Work material: JIS / SKD61 hardened material (HRC52) in the longitudinal direction, four equally spaced round bars,
Cutting speed: 55 m / min. ,
Cutting depth: 0.2 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 5 minutes,
Dry high-speed intermittent cutting test of alloy steel under the conditions (cutting condition A) (normal cutting speed is 30 m / min),
Work material: JIS / SUJ2 hardened material (HRC60), 4 longitudinally spaced round bars with equal intervals in the length direction,
Cutting speed: 50 m / min. ,
Cutting depth: 0.15 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 4 minutes,
Dry high-speed intermittent cutting test of bearing steel under the following conditions (cutting condition A) (normal cutting speed is 30 m / min),
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 8.

As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, ZrC of 1.2 μm Powder, 2.3 μm Cr ₃ C ₂ powder, 1.5 μm VC powder, 1.0 μm (Ti, W) C [by mass ratio, TiC / WC = 50/50] powder, and 1 .8 μm Co powder was prepared, each of these raw material powders was blended in the blending composition shown in Table 9, and then added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and then pressed into a predetermined shape at a pressure of 100 MPa. The green compacts were press-molded, and these green compacts were heated to a predetermined temperature in the range of 1370 to 1470 ° C. at a rate of temperature increase of 7 ° C./min in a 6 Pa vacuum atmosphere. After holding at temperature for 1 hour, sintering under furnace cooling conditions 3 types of sintered carbide forming round bar sintered bodies having diameters of 6.5 mm, 10.5 mm, and 20.5 mm were formed, and further, the above three types of round bar sintered bodies were ground by grinding. In the combinations shown in Table 9, the diameter × length of the cutting edge portion was 6 mm × 13 mm, 10 mm × 22 mm, and 20 mm × 45 mm, respectively, and each had a four-blade square shape with a twist angle of 30 degrees. WC base cemented carbide tool bases (end mills) C-1 to C-8 were produced.

  Then, the surfaces of these carbide substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone and dried, and then charged into the arc ion plating apparatus shown in FIG. A thin layer A having a granular crystal structure was formed by alternately depositing thin layers A and B having the composition, crystal grain structure and layer thickness shown in Table 10 along the layer thickness direction under the same conditions as in Example 1. And surface-coated carbide end mills (hereinafter referred to as the present invention-coated carbide end mills) 1 to 8 each having a hard coating layer composed of an alternately laminated structure of a thin layer B having a columnar crystal structure.

  For the purpose of comparison, the surfaces of the tool bases (end mills) C-1 to C-8 are ultrasonically cleaned in acetone and dried, and then mounted on the arc ion plating apparatus shown in FIG. Then, under the same conditions as in Example 1, a hard coating layer composed of an (Al, Ti) N layer having the composition, crystal grain structure and layer thickness shown in Table 11 is also deposited, thereby making the comparative surface coating super Hard end mills (hereinafter referred to as comparative coated carbide end mills) 1 to 8 were produced.

Next, of the present invention coated carbide end mills 1-8 and comparative coated carbide end mills 1-8,
About this invention coated carbide end mills 1-3 and comparative coated carbide end mills 1-3,
Work material-Plane: 100 mm × 250 mm, thickness: 50 mm JIS / SKD61 (hardened material (HRC52)) plate material,
Cutting speed: 50 m / min. ,
Groove depth (cut): 0.6 mm,
Table feed: 250 mm / min,
A dry grooving test of the alloy steel under the conditions (normal cutting speed is 30 m / min)
For the coated carbide end mills 4-6 of the present invention and the comparative coated carbide end mills 4-6,
Cutting speed: 55 m / min. ,
Groove depth (cut): 1.5 mm,
Table feed: 300 mm / min,
A dry grooving test of the alloy steel under the conditions (normal cutting speed is 30 m / min)
For the coated carbide end mills 7 and 8 of the present invention and the comparative coated carbide end mills 7 and 8,
Work material-plane: 100 mm × 250 mm, thickness: 50 mm JIS / SUJ2 (hardened material (HRC60)) plate material,
Cutting speed: 45 m / min. ,
Groove depth (cut): 3 mm,
Table feed: 200 mm / min,
A dry groove cutting test of the bearing steel under the conditions (normal cutting speed is 25 m / min)
In any of the above groove cutting tests, the cutting groove length was measured until the flank wear width of the outer peripheral edge of the cutting edge reached 0.1 mm, which is a guide for the service life.
The measurement results are shown in Table 10 and Table 11, respectively.

The diameters produced in Example 2 above were 6.5 mm (for forming carbide substrates C-1 to C-3), 10.5 mm (for forming carbide substrates C-4 to C-6), and 20.5 mm. Using three types of round bar sintered bodies (for forming carbide substrates C-7 and C-8), from these three types of round bar sintered bodies, the diameter x length of the groove forming portion was obtained by grinding. 4 mm × 13 mm (Carbide substrates D-1 to D-3), 8 mm × 22 mm (Carbide substrates D-4 to D-6), and 16 mm × 45 mm (Carbide substrates D-7 and D-8), respectively. And WC-based cemented carbide tool bases (drills) D-1 to D-8 each having a two-blade shape with a twist angle of 30 degrees were manufactured.

  Next, the cutting edges of these tool bases (drills) D-1 to D-8 are subjected to honing, ultrasonically cleaned in acetone, and dried to the arc ion plating apparatus shown in FIG. Under the same conditions as in Example 1 above, thin layers A and B having the composition, crystal grain structure and layer thickness shown in Table 12 were alternately deposited, and the thin layer A having a granular crystal structure and Surface-coated carbide drills of the present invention (hereinafter referred to as the present invention-coated carbide drills) 1 to 8 having a hard coating layer composed of an alternately laminated structure with a thin layer B having a columnar crystal structure were manufactured.

  For comparison purposes, honing is applied to the surfaces of the tool bases (drills) D-1 to D-3, D-4 to D-6, D-7, and D-8, and ultrasonic waves are obtained in acetone. In the washed and dried state, the same was inserted into the arc ion plating apparatus shown in FIG. 1 and the composition, crystal grain structure and layer thickness shown in Table 13 were also obtained under the same conditions as in Example 1 above ( Comparative surface-coated carbide drills (hereinafter referred to as comparative coated carbide drills) 1 to 8 were manufactured by vapor-depositing a hard coating layer composed of an Al, Ti) N layer.

Next, of the present invention coated carbide drills 1-8 and comparative coated carbide drills 1-8,
About this invention coated carbide drills 1-3 and comparative coated carbide drills 1-3,
Work material-Plane: 100 mm × 250 mm, thickness: 50 mm JIS / SKD61 (hardened material (HRC52)) plate material,
Cutting speed: 40 m / min. ,
Feed: 0.15 mm / rev,
Hole depth: 10 mm,
Wet high speed cutting test of alloy steel under the conditions (normal cutting speed is 20 m / min)
About this invention coated carbide drills 4-6 and comparative coated carbide drills 4-6,
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS SKD11 (hardened material (HRC60)) plate material,
Cutting speed: 55 m / min. ,
Feed: 0.1 mm / rev,
Hole depth: 15 mm,
Wet high speed cutting test of alloy steel under the conditions (normal cutting speed is 25 m / min)
About the coated carbide drills 7 and 8 of the present invention and the comparative coated carbide drills 7 and 8,
Work material-plane: 100 mm × 250 mm, thickness: 50 mm JIS / SUJ2 (hardened material (HRC60)) plate material,
Cutting speed: 60 m / min. ,
Feed: 0.2 mm / rev,
Hole depth: 30 mm,
The bearing steel was subjected to a wet drilling high-speed cutting test (normal cutting speed is 30 m / min) under the conditions of
In any of the above wet high-speed drilling tests (using water-soluble cutting oil), the number of drilling processes until the flank wear width of the cutting edge surface reached 0.3 mm was measured. The measurement results are shown in Tables 12 and 13, respectively.

The present invention coated carbide tips 1 to 16, the present invention coated carbide end mills 1 to 8, the present invention coated carbide drills 1 to 8, and the comparative surface coated cutting tool as the surface coated cutting tool of the present invention obtained as a result. The composition of hard coating layers of comparative coated carbide tips 1-16, comparative coated carbide end mills 1-8, comparative coated carbide drills 1-8 as energy dispersive X-ray analysis using a transmission electron microscope As a result of measurement, each showed substantially the same composition as the target composition.
Moreover, when the average layer thickness of each said hard coating layer was cross-sectional measured with the transmission electron microscope, all showed the average value (average value of five places) substantially the same as target layer thickness.

  Furthermore, the (Al, Ti) N layer constituting the thin layer A and the thin layer B of the surface-coated cutting tool of the present invention and the (Al, Ti) N layer constituting the hard coating layer of the comparative surface-coated cutting tool, The crystal grain structure was determined by a transmission electron microscope, and the results are shown in Tables 4-7 and 10-13.

  From the results shown in Tables 8 and 10-13, the surface-coated cutting tool of the present invention has a thin layer A that exhibits excellent wear resistance and a thin layer B that exhibits excellent chipping resistance and fracture resistance. In addition, the interlaminar structure is also high, and the interlaminar adhesion strength is also high. As a result, excellent chipping resistance even in high-speed intermittent cutting of high-hardness steel in which intermittent and impact loads are applied to the cutting edge. In addition to exhibiting chipping resistance and excellent wear resistance over a long period of use, the hard coating layer has a single crystal grain structure consisting of only granular crystals or columnar crystals (Al, Ti) N. It is apparent that the coated tool composed of layers is inferior in any of chipping resistance, chipping resistance, peeling resistance, and abrasion resistance, and therefore reaches the service life in a relatively short time.

  As described above, the surface-coated cutting tool of the present invention is subjected to intermittent and impact loads on the cutting edge, in addition to cutting under normal cutting conditions such as various types of steel and cast iron. Even high-speed intermittent cutting of high-hardness steel exhibits excellent cutting performance over a long period of time, so it is sufficient for high-performance cutting equipment, labor-saving and energy-saving of cutting, and cost reduction It can respond to satisfaction.

Claims (2)

A hard coating layer made of a composite nitride of Al and Ti having a layer thickness of 0.8 to 5.0 μm was deposited on the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet. In surface coated cutting tools,
The hard coating layer is configured as an alternate laminated structure of thin layers A composed of a granular crystal structure of Al and Ti composite nitride and thin layers B composed of a columnar crystal structure, and each of the thin layers A and B is 0 The average crystal grain size of the granular crystals constituting the thin layer A is 30 nm or less, and the average crystal grain size of the columnar crystals constituting the thin layer B is 50 to A surface-coated cutting tool having a thickness of 500 nm. The composite nitride of Al and Ti is
Composition _{formula: (Al 1-X Ti X} ) N
The surface-coated cutting tool according to claim 1, wherein 0.40 ≦ X ≦ 0.65 (where X is an atomic ratio) is satisfied.

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