JP5440346B2 - Surface coated cutting tool - Google Patents

Description

  The present invention, for example, cuts high hardness steel, such as a hardened material of alloy tool steel, under high-speed intermittent cutting conditions that are accompanied by high heat generation and an intermittent and impactful high load acts on the cutting edge. Even when the hard coating layer is used, the hard coating layer has excellent high-temperature hardness, high-temperature strength, and heat resistance, so that it exhibits excellent chipping resistance, chipping resistance, and peeling resistance. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent wear resistance.

  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, a substrate (hereinafter collectively referred to as tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet). A coated tool in which a composite nitride layer of Cr, Al, Ti, and B is formed as a hard coating layer on the surface of a tool base) is known, and this conventional coated tool has excellent wear resistance for a long time. It is known to exhibit over use (for example, refer to Patent Documents 1 and 2).

  Further, the conventional coated tool is, for example, a state in which a tool base is inserted into an arc ion plating (AIP) apparatus which is one type 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 simultaneously nitrogen gas is introduced into the apparatus as a reaction gas. It is manufactured by vapor-depositing a hard coating layer composed of a (Cr, Al, Ti, B) N layer having a desired layer thickness and composition.

JP 2003-71611 A JP 2006-315173 A

  In recent years, the performance of cutting devices has been dramatically improved, while there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and along with this, cutting tends to aim for higher speed. In conventional coated tools, when this is used under high-speed intermittent cutting conditions of high-hardness steel that is accompanied by particularly high heat generation and where intermittent and impact loads are applied to the cutting edge, chipping is applied to the hard coating layer. As a result, defects, peeling, etc. are likely to occur, and as a result, the service life is reached in a relatively short time.

  Therefore, from the viewpoints described above, the present inventors provide a high hardness steel such as a hardened material of an alloy tool steel, in particular, by providing a hard coating layer with excellent high temperature hardness and further excellent high temperature strength. Even when cutting is performed under high-speed intermittent cutting conditions that cause high heat generation and intermittent / impact loads on the cutting edge, it can be used for a long time without chipping, chipping, peeling, etc. In order to develop a coated tool exhibiting excellent wear resistance, the results of researches focusing on the crystal grain structure of the (Cr, Al, Ti, B) N layer constituting the hard coating layer are as follows. Obtained knowledge.

The Cr component, which is a component of the (Cr, Al, Ti, B) N layer that constitutes the hard coating layer of the conventional coated tool, improves the high temperature strength and is resistant to high temperature oxidation in the state where Cr and Al coexist. The Ti component has the effect of further improving the high temperature strength, the B component has the effect of improving the high temperature hardness, and the hard coating layer contains these components. By containing, predetermined chipping resistance, oxidation resistance, heat resistance, wear resistance and the like are exhibited.
By the way, in the conventional coated tool, no particular attention is paid to the crystal grain structure (grain size, form) of the hard coating layer formed of (Cr, Al, Ti, B) N. In References 1 and 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 (Cr, Al, Ti, B) N granular crystal structure and a relatively large grain size (Cr , Al, Ti, B) It has been found that a hard coating layer can be formed by an alternately laminated structure with a thin layer B composed of an N columnar crystal structure.
In addition, the thin layer A composed of the granular crystal structure is excellent in wear resistance and heat resistance, and the thin layer B composed of a columnar crystal structure is excellent in chipping resistance, chipping resistance, and heat resistance. And thin layer B have the same component composition and the same crystal structure, so that the adhesion strength between the thin layers is large and there is no risk of delamination. The hard coating layer is used for a long time without causing chipping, chipping, peeling, etc. even in high-speed intermittent cutting of high-hardness steel that generates intermittent heat on the cutting edge with high heat generation. They have found that they have excellent wear resistance.

The present invention has been made based on the above findings,
“(1) The surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet is composed of a composite nitride of Cr, Al, Ti, and B having a layer thickness of 0.8 to 5.0 μm. In surface-coated cutting tools in which a hard coating layer is formed by vapor deposition,
The hard coating layer is configured as an alternate laminated structure of a thin layer A composed of a granular crystal structure of a composite nitride of Cr, Al, Ti, and B and a thin layer B composed of a columnar crystal structure. B has a layer thickness of 0.05 to 2 μm, the average crystal grain size of the granular crystals constituting the thin layer A is 30 nm or less, and the average crystal grain of the columnar crystals constituting the thin layer B A surface-coated cutting tool having a diameter of 50 to 500 nm.
(2) The composite nitride of Cr, Al, Ti and B is
Composition _{formula: (Cr 1-X-Y} -Z Al X Ti Y B Z) N
In this case, 0.40 ≦ X ≦ 0.65, 0.01 ≦ Y ≦ 0.20, 0.005 ≦ Z ≦ 0.08 (where X, Y, and Z are atomic ratios) The surface-coated cutting tool according to (1), wherein the surface-coated cutting tool 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 made of the (Cr, Al, Ti, B) N layer has its crystal structure changed from cubic to hexagonal with an increase in Al content, and the film hardness is reduced. 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: (Cr 1-X-Y} -Z Al X Ti Y B Z) N
It is desirable to determine the Al content ratio so that X is 0.65 or less (where X is an atomic ratio). However, when X is less than 0.40, the crystal structure remains in a cubic structure, but due to the increase in the relative Cr content, the high temperature hardness of the (Cr, Al, Ti, B) N layer itself. Of the Cr, Ti, and B in the (Cr, Al, Ti, B) N layer constituting the hard coating layer, since it is difficult to ensure the minimum required wear resistance. It is preferable that the Al content ratio X (atomic ratio) in the total amount of the above satisfies 0.40 ≦ X ≦ 0.65.
In the composition formula, when the Ti content ratio Y is less than 0.01, improvement in the high temperature strength of the hard coating layer cannot be expected. On the other hand, when the Ti content ratio Y exceeds 0.20, Since the Cr content ratio decreases and the effect of improving high-temperature oxidation resistance due to the coexistence of Cr and Al decreases, the Ti content ratio Y (atomic ratio) in the total amount of Cr, Al and B is 0. It is desirable to satisfy .01 ≦ Y ≦ 0.20.
Further, when the B content ratio Z is less than 0.005, the effect of improving the heat resistance of the hard coating layer is small. On the other hand, when the B content ratio Z exceeds 0.08, the content of Cr and Ti is relatively small. Since the ratio decreases and the high temperature strength tends to decrease, the content ratio Z (atomic ratio) of B in the total amount of Cr, Al, and Ti satisfies 0.005 ≦ Y ≦ 0.08. It is desirable to be satisfied.

(B) Thin layer A
The thin layer A is made of (Cr, Al, Ti, B) N having a granular crystal structure, has excellent film hardness and heat resistance, 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 decreases, so the average crystal grain size of the granular crystal structure is set to 30 nm or less.
The “average crystal grain size” in the present invention is calculated by measuring with 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. In order to easily generate chipping and chipping by high-speed 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 (Cr, Al, Ti, B) N having a columnar crystal structure exhibits excellent high-temperature strength, toughness, and heat resistance, but the columnar crystal structure (Cr, Al, Ti) constituting the thin layer B , B) When the average crystal grain size of N exceeds 500 nm, the wear resistance is reduced due to the coarsening of the crystal grains. On the other hand, when the average crystal grain size is less than 50 nm, the chipping resistance and chipping resistance are improved. Since it was not observed, the average crystal grain size of (Cr, Al, Ti, B) N having a columnar crystal structure constituting the thin layer B 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 and wear resistance even in high-speed intermittent cutting 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.

  The coated tool of the present invention comprises a thin layer A composed of a granular crystal structure (Cr, Al, Ti, B) N layer having excellent coating hardness and heat resistance, and excellent high-temperature strength and toughness. Since it is configured as an alternating layered structure of thin layers B composed of (Cr, Al, Ti, B) N layers having a columnar crystal structure exhibiting heat resistance, the entire hard coating layer has excellent high-temperature hardness, heat resistance, In addition, it has excellent high-temperature strength, and as a result, it generates high heat from hardened steel such as hardened material of alloy tool steel, and high-speed intermittent operation that causes intermittent and impact loads on the cutting edge. Also in cutting, the hard coating layer has excellent chipping resistance, chipping resistance, and peel resistance, and also 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. Attached along the outer periphery at a position that is a predetermined distance in the radial direction from the central axis on the rotary table in the apparatus, a Cr—Al—Ti—B alloy having a predetermined component composition as a cathode electrode (evaporation source), for example, , Facing each other across the rotary table,
(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 is applied, and a current of 100 A is passed between a cathode electrode and an anode electrode made of one Cr—Al—Ti—B alloy to generate an arc discharge.
(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 applied, a predetermined value in the range of 50 to 100 A is provided between the cathode electrode and the anode electrode of the Cr—Al—Ti—B alloy. To generate an arc discharge to deposit a thin layer A composed of (Cr, Al, Ti, B) N layers having a granular crystal structure on the surface of the tool base,
(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. With a DC bias voltage in the range of −90 V applied, a predetermined current in the range of 50 to 100 A is passed between the cathode electrode and the anode electrode of the Cr—Al—Ti—B alloy to cause arc discharge. And forming a thin layer B composed of (Cr, Al, Ti, B) 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. Insert the Cr-Al-Ti-B alloy of a predetermined composition as a cathode electrode (evaporation source), and first evacuate the apparatus and keep it at a vacuum of 0.1 Pa or less with a heater. After heating the inside of the apparatus to 500 ° C., a DC bias voltage of −1000 V was applied to the tool base, and a current of 100 A was passed between the Cr—Al—Ti—B alloy of the cathode electrode and the anode electrode. Arc discharge is generated, the tool substrate surface is bombarded, nitrogen gas is introduced into the apparatus as the reaction gas, and the pressure conditions shown in Table 3 are adjusted, and the tool rotates on the rotary table. Arc power is generated between the cathode electrode and the anode electrode of the Cr-Al-Ti-B alloy in the state where the DC bias voltage shown in Table 3 is applied to the rotating tool substrate, and the tool substrate A- Hard surfaces comprising (Cr, Al, Ti, B) N layers having compositions, crystal grain structures and layer thicknesses shown in Tables 6 and 7 on the respective surfaces of 1 to A-10 and B-1 to B-6 Comparative surface-coated cemented carbide throwaway chips (hereinafter referred to as comparative coated cemented carbide chips) 1 to 16 were produced by depositing a coating layer, respectively.

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 screwed to the tip of the tool steel tool with a fixing jig. About ~ 16
Work material: JIS · SKD61 quenching material (HRC55) lengthwise equidistant four round grooved round bars,
Cutting speed: 55 m / min. ,
Cutting depth: 0.25 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 6 minutes,
Dry high-speed cutting test of alloy steel under the conditions (cutting condition A) (normal cutting speed is 30 m / min.),
Work material: JIS · SKD11 quenching material (HRC60) in the longitudinal direction, four equally spaced round bars,
Cutting speed: 60 m / min. ,
Cutting depth: 0.25 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 4 minutes,
Dry high-speed cutting test of alloy steel under the following conditions (cutting condition B) (normal cutting speed is 25 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: 0.2 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 5 minutes,
The dry high speed cutting test (normal cutting speed is 30 m / min.) Of the bearing steel under the above conditions (cutting condition C) was performed, and the flank wear width of the cutting edge was measured in any cutting test. 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.

  Subsequently, the surfaces of these carbide substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone and dried, and then loaded into the arc ion plating apparatus shown in FIG. Under the same conditions as in Example 1, thin layer A and thin layer B having the composition, crystal grain structure and layer thickness shown in Table 10 along the layer thickness direction were alternately deposited to form thin layer A having a granular crystal structure and Surface-coated carbide end mills of the present invention (hereinafter referred to as the present invention coated carbide end mills) 1 to 8 having a hard coating layer composed of an alternating laminated structure with a thin layer B having a columnar crystal structure were produced.

  For comparison purposes, the surfaces of the tool bases (end mills) C-1 to C-8 were ultrasonically cleaned in acetone and dried, and then loaded into the arc ion plating apparatus shown in FIG. Then, under the same conditions as in Example 1, a comparative coating surface was obtained by vapor-depositing a hard coating layer consisting of a (Cr, Al, Ti, B) N layer having the composition, crystal grain structure and layer thickness shown in Table 11 as well. Coated carbide 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 plate of JIS SKD61 (hardened material (HRC55)),
Cutting speed: 55 m / min. ,
Groove depth (cut): 0.5 mm,
Table feed: 200 mm / min,
A dry high-speed 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,
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS SKD11 (hardened material (HRC60)) plate material,
Cutting speed: 45 m / min. ,
Groove depth (cut): 0.8 mm,
Table feed: 180 mm / min,
A dry high-speed 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: 40 m / min. ,
Groove depth (cut): 2.5 mm,
Table feed: 250 mm / min,
A dry high-speed grooving 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 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 (ultraviolet). 3 types of round bar sintered bodies (for forming hard base bodies C-7 and C-8) are used, and from these 3 types of round bar sintered bodies, the diameter x length of the groove forming portion is determined by grinding. Dimensions of 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) In addition, 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, thin layer A and thin layer B having the composition, crystal grain structure and layer thickness shown in Table 12 were alternately deposited to form thin layer A and columnar structure of granular crystal structure. 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 alternating laminated structure with a thin layer B having a crystal structure were manufactured.

  For comparison purposes, honing is performed on the surfaces of the tool bases (drills) D-1 to D-3, D-4 to D-6, D-7, and D-8, and ultrasonic cleaning is performed in acetone. Then, in the dry state, the same was charged into the arc ion plating apparatus shown in FIG. 1, and under the same conditions as in Example 1, the composition, crystal grain structure and layer thickness (Cr, 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, B) 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 plate of JIS SKD61 (hardened material (HRC55)),
Cutting speed: 50 m / min. ,
Feed: 0.12 mm / rev,
Hole depth: 10 mm,
Wet high-speed drilling 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: 0.18 mm / rev,
Hole depth: 20 mm,
Wet high-speed drilling 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: 65 m / min. ,
Feed: 0.12 mm / rev,
Hole depth: 30 mm,
A wet high-speed drilling test of the bearing steel under the conditions (normal cutting speed is 30 m / min.),
In any of the wet high-speed drilling tests (using water-soluble cutting oil), the number of drilling processes until the flank wear width of the tip 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 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 thin layer A and thin layer B of the present invention surface-coated cutting tool (Cr, Al, Ti, B) N layer and the comparative surface-coated cutting tool hard coating layer (Cr, Al, Ti, B) About N layer, the crystal grain structure of each layer was calculated | required with the transmission electron microscope, and the result was shown to 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 is a thin layer A having a hard coating layer with excellent wear resistance and heat resistance, and a thin layer with excellent chipping resistance and heat resistance. High-speed intermittent cutting of high-hardness steel, which has an alternating layered structure with layer B and also has high interlayer adhesion strength, resulting in high heat generation and intermittent and impact loads on the cutting edge. However, while having excellent chipping resistance and wear resistance, the hard coating layer is composed of a single crystal grain structure (Cr, Al, Ti, B) N layer composed of only granular crystals or columnar crystals. It is apparent that the coated tool reaches the service life in a relatively short time because of its poor chipping resistance and wear resistance.

  As described above, the surface-coated cutting tool of the present invention is not only for cutting under normal cutting conditions such as various types of steel and cast iron, but particularly accompanied by high heat generation and intermittent with respect to the cutting edge.・ Even in high-speed intermittent cutting of high-hardness steel that is subjected to shock loads, it exhibits excellent cutting performance over a long period of time. It is possible to cope with the reduction of cost and cost.

Claims (2)

A hard coating layer made of a composite nitride of Cr, Al, Ti, and B having a layer thickness of 0.8 to 5.0 μm is formed on the surface of the tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet. In the surface-coated cutting tool formed by vapor deposition,
The hard coating layer is configured as an alternate laminated structure of a thin layer A composed of a granular crystal structure of a composite nitride of Cr, Al, Ti, and B and a thin layer B composed of a columnar crystal structure. B has a layer thickness of 0.05 to 2 μm, the average crystal grain size of the granular crystals constituting the thin layer A is 30 nm or less, and the average crystal grain of the columnar crystals constituting the thin layer B A surface-coated cutting tool having a diameter of 50 to 500 nm. The composite nitride of Cr, Al, Ti and B is
Composition _{formula: (Cr 1-X-Y} -Z Al X Ti Y B Z) N
In this case, 0.40 ≦ X ≦ 0.65, 0.01 ≦ Y ≦ 0.20, 0.005 ≦ Z ≦ 0.08 (where X, Y, and Z are atomic ratios) The surface-coated cutting tool according to claim 1, wherein the surface-coated cutting tool is satisfied.

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