JP5979438B2 - Surface coated cutting tool - Google Patents

Description

The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool). More specifically, for example, mild steel, general steel, high-hardness steel, and the like are accompanied by high heat generation and a large mechanical load is applied to the cutting edge portion. The present invention relates to a coated tool that exhibits excellent chipping resistance and wear resistance when a hard coating layer is cut under such high-speed conditions.

  In general, coated tools are used for turning and planing of work materials such as various types of steel and cast iron, inserts that can be used detachably attached to the tip of a cutting tool, drilling processing of work materials, etc. There are drills, miniature drills, solid type end mills used for chamfering, grooving, shoulder processing, etc. of the work material, etc. Also, inserts are detachably attached and cutting is performed in the same way as solid type end mills Insert type end mill tools are known.

In recent years, there is a high demand for higher efficiency in cutting metal materials, and it is required to increase the cutting speed. For this reason, it is requested | required that a wear resistance and a fracture | rupture resistance should be improved with respect to the film which coat | covers the tool base | substrate surface of a cutting tool.
Therefore, various developments of the coating have been made to satisfy such requirements. For example, Patent Document 1 proposes to use a compound having a specific composition containing Al and Cr as such a coating (so-called AlCr-based coating).

  Further, Patent Document 2 forms a film on a tool base of a surface-coated cutting tool, and the film is formed by alternately laminating one or more first super multi-layer films and second super multi-layer films. The first super multi-layer film is formed by alternately laminating one or more layers of A1 and B layers, and the second super multi-layer film is composed of an A2 layer and a C layer. Are alternately stacked, each of the A1 layer and the A2 layer is composed of any one of TiN, TiCN, TiAlN, or TiAlCN, and the B layer is composed of TiSiN or TiSiCN, It discloses that the C layer is composed of AlCrN or AlCrCN, thereby providing a surface-coated cutting tool having a coating with reduced brittleness problems while maintaining heat resistance and wear resistance.

  Further, as another conventional coated tool, for example, an arc ion plating apparatus, which is one of physical vapor deposition apparatuses shown schematically in FIG. 2, is loaded with a tool base, and the tool base is heated to 450 ° C. with a heater. While being heated to a temperature, an arc discharge is generated between the anode electrode and a cathode electrode (evaporation source) on which an Al—Cr alloy having a predetermined composition is set under the condition of current: 100 A and simultaneously reacts in the apparatus. Nitrogen gas is introduced as a gas to form a nitrogen atmosphere. On the other hand, by evaporating evaporated particles on the surface of the tool base under the condition that a bias voltage of −200 V is applied (Al, Cr, for example) ) It is also known that a hard coating layer composed of an N layer is formed (see, for example, Patent Document 3).

JP-T-2006-524748 JP 2000-334606 A JP 2000-271699 A (page 8, paragraph [0055])

  However, the automation of cutting machines in recent years has been remarkable. On the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting, and as a result, cutting tools have as much influence as possible on the type of work material. There is a tendency to find a versatile tool that does not receive, that is, a cutting tool capable of cutting as many grades as possible. However, in a conventional coated tool using a coating layer composed of an (Al, Cr) N layer, this is not the case. Although there is no problem when used for cutting materials such as steel and cast iron at the normal cutting speed, mild steel, general steel, high hardness steel, etc. are accompanied by high heat generation and impact on the cutting edge. (Al, Cr) N layer is a high hardness film when it is cut under high-speed cutting conditions that have remarkable properties and weldability. However, due to its hardness and high residual stress, the film itself may collapse or peel off. Or this problem Fruit, occurs rapidly increased in defects in the cutting edge (small chipping), which is at present, leading to a relatively short time service life due.

For example, according to Patent Document 1, although it is possible to improve the wear resistance and fracture resistance to some extent, since the problem inherent to such an AlCr-based film shows brittleness, the film itself due to impact during cutting or the like. There was a problem of breaking or peeling.
Further, even according to the proposal in Patent Document 2, there are cases where the coating itself cannot be sufficiently prevented from being broken or peeled off under severe cutting conditions.
Therefore, the technical problem to be solved by the present invention, that is, the object of the present invention is to provide excellent wear resistance even when mild steel, general steel, high hardness steel, etc. are cut under high-speed cutting conditions with high heat generation. And providing a coated tool exhibiting fracture resistance.

In view of the above, the inventors of the present invention have excellent wear resistance and a hard coating layer, particularly when cutting of mild steel, general steel, high hardness steel and the like under high-speed cutting conditions. In order to develop a coated tool that has both fracture resistance, we conducted intensive research.
as a result,
(1) The (Al, Cr) N layer is a high-hardness film and is a material suitable for the hard coating layer. However, when formed by a conventional film formation method, the Young's modulus increases, and this is the cause. The toughness of the film decreases and the occurrence of defects increases.
(2) The present inventors have found that the Young's modulus of the (Al, Cr) N layer can be controlled with good reproducibility by adjusting the bias voltage and reaction atmosphere pressure during film formation. If the (Al, Cr) N layer is formed as a layer having a low Young's modulus, the high hardness of the (Al, Cr) N layer cannot be utilized, and the wear resistance is reduced.
(3) Accordingly, the inventors of the present invention have a hard coating layer composed of a thin layer A composed of an (Al, Cr) N layer having a low Young's modulus and an (Al, Ti) N layer superior in heat resistance and wear resistance. By alternately laminating the thin layer B, the disadvantages of the (Al, Cr) N layer with a low Young's modulus are complemented by the alternate laminating with the (Al, Ti) N layer, and excellent cutting that does not exist in the conventional coating layer A completely new finding was obtained that a hard coating layer having performance can be obtained.
The present invention was obtained as a result of detailed analysis of the relationship between the composition of the thin layer A and the thin layer B, the single layer average layer thickness, the Young's modulus, the total average layer thickness and the cutting performance based on such knowledge. Specifically, the configuration is as follows.
A composite nitride layer of Al and Cr in which a Cr component is contained on the surface of the tool base so that the content ratio of Cr in the total amount of Al and Cr as a hard coating layer is 25 to 50 atomic%. A low Young's modulus layer (hereinafter referred to as a low Young's modulus (Al, Cr) N layer) having a Young's modulus a of 150 GPa ≦ a ≦ 300 GPa is formed as a thin layer A with an average layer thickness of 0.1 to 1.0 μm. On top of this, a composite nitride layer of Al and Ti containing a Ti component so that the Ti content in the total amount of Al and Ti is 25 to 55 atomic% (hereinafter referred to as (Al, Ti) An (Al, Ti) N layer having a Young's modulus b of 400 GPa ≦ b ≦ 550 GPa is formed as a thin layer B with an average layer thickness of 0.1 to 1.0 μm, and further thereon A thin layer A and a thin layer B are sequentially formed, and the total average layer thickness is 1.0 to 10 μm Forming a layer having alternating layered structure that. As a result, the low Young's modulus (Al, Cr) N layer of the thin layer A exhibits excellent adhesion and fracture resistance, and the (Al, Ti) N layer constituting the thin layer B has excellent wear resistance. In addition to exhibiting heat resistance, the layers of different composition of the low Young's modulus (Al, Cr) N layer and (Al, Ti) N layer are formed as alternating layers, so that the grain growth of each layer becomes coarse Is prevented, particles are miniaturized, film strength is improved, and crack propagation and progress are prevented by this laminated structure, thereby improving chipping resistance and chipping resistance. By these synergistic effects, the inventors have obtained new knowledge that excellent chipping resistance, wear resistance, and heat resistance are exhibited, and based on such knowledge, the present invention has been completed.

The present invention has been made based on the research results,
“(1) In a surface-coated cutting tool in which a hard coating layer is formed on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
The hard coating layer is
(A) having an average layer thickness of 0.1 to 1.0 μm, and
Composition formula: (Al _1-x Cr _x ) N (where x represents the content ratio of Cr in the total amount of Al and Cr, and the atomic ratio is 0.25 ≦ x ≦ 0.50) Satisfied, a thin layer A composed of a composite nitride of Al and Cr having a Young's modulus a of 150 GPa ≦ a ≦ 300 GPa,
(B) having an average layer thickness of 0.1 to 1.0 μm, and
Composition formula: (Al _1-y Ti _y ) N (where y represents the content ratio of Ti in the total amount of Al and Ti, and the atomic ratio is 0.25 ≦ y ≦ 0.55) Satisfactory, thin layer B made of a composite nitride of Al and Ti with Young's modulus b of 400 GPa ≦ b ≦ 550 GPa,
(C) Immediately above the tool substrate is the thin layer A, and has an alternate laminated structure of the thin layer A and the thin layer B, and the total average layer thickness is 1.0 to 10 μm.
A surface-coated cutting tool characterized by satisfying the conditions (a) to (c). "
It is characterized by.

  Next, the reason why the numerical values of the constituent layers of the hard coating layer of the coated tool of the present invention are limited as described above will be described.

(A) Composition and Young's modulus of (Al, Cr) N layer constituting thin layer A:
The Al component, which is a component of the (Al, Cr) N layer that constitutes the thin layer A, which is one layer of the alternately laminated structure, improves the high temperature hardness of the hard coating layer, and the Cr component improves the high temperature strength. However, when the x value (atomic ratio, the same applies hereinafter) indicating the Cr content in the total amount with Al is less than 0.25, the Al content is relatively increased, so that Since the structure changes from cubic to hexagonal and the film hardness decreases, in order to maintain at least the predetermined film hardness, the x value indicating the Cr content in the total amount with Al is set to 0. It needs to be 25 or more. On the other hand, when the x value indicating the Cr content in the total amount with Al exceeds 0.50, the Al content decreases relatively, ensuring high-temperature hardness required for high-speed cutting. The x value was determined to be 0.25 to 0.50 because it was difficult to prevent chipping from occurring.

  In addition, by making the Young's modulus of the (Al, Cr) N layer constituting the thin layer A a low Young's modulus of 150 to 300 GPa, the amount of deformation of the film increases when external stress is applied, and cracks are generated. Therefore, the chipping resistance can be improved. Here, the reason why the Young's modulus is limited to 150 to 300 GPa is that lowering the Young's modulus to less than 150 GPa is not preferable because the wear resistance is remarkably lowered. Since the properties are reduced, the coating is likely to collapse or peel off. Therefore, the Young's modulus is limited to 150 to 300 GPa in order to more effectively exert the function performed by the lower layer.

(B) Composition and Young's modulus of (Al, Ti) N layer constituting thin layer B layer:
The (Al, Ti) N layer of the thin layer B that constitutes an alternating laminated structure together with the thin layer A exhibits a uniform high temperature hardness and heat resistance and toughness throughout the entire layer, but by the Ti component that is a constituent component thereof, It has excellent high-temperature strength, and the Al component complements high-temperature hardness and heat resistance. Therefore, a low friction coefficient is maintained even under high-temperature cutting conditions, and excellent heat resistance is exhibited, but the y value (atomic ratio, the same applies hereinafter) indicating the Ti content in the total amount with Al is 0. If it is less than .25, high temperature strength cannot be secured, and abnormal damage is caused at the boundary portion of the cutting edge and defects are likely to occur, so a long life cannot be expected. If the y value indicating the Ti content ratio exceeds 0.55, the Al content ratio is relatively decreased, and not only the high-temperature hardness required for high-speed cutting cannot be secured, but also wear resistance. The y value was determined to be 0.25 to 0.55 because it is difficult to prevent the occurrence of chipping.

In addition, the (Al, Ti) N layer constituting the thin layer B is not limited to the work material and cutting conditions in order to sufficiently exhibit the expected fracture resistance, wear resistance, and heat resistance. When the Young's modulus is 400 to 550 GPa, the wear resistance, heat resistance, and fracture resistance of the (Al, Ti) N layer are more effectively exhibited. Therefore, in the present invention, the Young's modulus of the (Al, Ti) N layer of the thin layer B is set to 400 to 550 GPa.

(C) The average layer thickness of the thin layers A and B and the total average layer thickness of the hard coating layer:
The hard coating layer of the present invention has an alternate laminated structure in which thin layers A and thin layers B having different compositions are alternately laminated, thereby preventing the growth of particles in each layer from being coarsened. In addition to reducing the size of the particles and improving the film strength, the lamination structure prevents crack propagation and progress, thereby improving the chipping resistance and chipping resistance. When the average layer thickness is less than 0.1 μm, it is difficult to clearly form each thin layer as having a predetermined composition, and the above-mentioned excellent characteristics possessed by each thin layer cannot be exhibited. On the other hand, if each layer thickness exceeds 1.0 μm, the chip strength and chipping resistance decrease due to the decrease in film strength due to the coarsening of the particles. Was determined to be 0.1 to 1.0 μm.
In addition, when the total average layer thickness of the hard coating layer is less than 1.0 μm, the excellent chipping resistance and chipping resistance provided by the above-described alternate laminated structure cannot be sufficiently exhibited, while when it exceeds 10 μm. On the contrary, since chipping and defects are likely to occur, the total average layer thickness of the hard coating layer was determined to be 1.0 to 10 μm.

In addition, although not specifically limited, the crystal structure of the (Al, Cr) N layer constituting the thin layer A and the crystal structure of the (Al, Ti) N layer constituting the thin layer B are the same cubic crystal. By doing so, the adhesion between the layers is improved, and the problem of deterioration of the life due to delamination is solved, which is preferable.

The (Al, Cr) N layer constituting the thin layer A constituting the hard coating layer of the present invention and the (Al, Ti) N layer constituting the thin layer B are shown schematically in FIG. 1, for example. In a state where a tool base is loaded into an arc ion plating apparatus which is a kind of physical vapor deposition apparatus, and the inside of the apparatus is heated to a temperature of, for example, 500 ° C. with a heater.
(A) A cathode electrode (evaporation source) made of an Al—Cr alloy having a predetermined composition is disposed in the apparatus, and a current of, for example, 110 A is provided between the anode electrode and the Al—Cr alloy as the cathode electrode (evaporation source). At the same time, arc discharge was generated, and simultaneously nitrogen gas was introduced into the apparatus as a reaction gas to obtain a reaction atmosphere of, for example, 0.8 Pa. On the other hand, a bias voltage of, for example, −20 V was applied to the tool base. By depositing for a predetermined time under conditions, an (Al, Cr) layer which is a thin layer A having a predetermined target layer thickness and Young's modulus is formed.
(B) Next, for example, an arc discharge is generated between the anode electrode and the Al—Ti alloy as the cathode electrode (evaporation source) under the condition of current: 110 A, and at the same time, nitrogen gas is introduced into the apparatus as a reaction gas. Then, for example, the reaction atmosphere is set to 3.0 Pa, and the tool base is deposited on the thin layer A for a predetermined time under a condition in which a bias voltage of, for example, −100 V is applied. The (Al, Ti) N layer which is the thin layer B is formed.
By repeating the steps (a) and (b) alternately until a predetermined total target layer thickness is obtained, the hard coating layer of the present invention can be formed by vapor deposition. That is, the Young's modulus of the (Al, Cr) N layer constituting the thin layer A can be controlled by adjusting the reaction atmospheric pressure and the bias voltage applied to the tool base.

  According to one aspect of the coated tool of the present invention, the hard coating layer has an alternately laminated structure of a thin layer A composed of a low Young's modulus (Al, Cr) N layer and a thin layer B composed of an (Al, Ti) N layer. By virtue of the synergistic effect of the excellent fracture resistance and adhesion exhibited by the thin layer A and the excellent high temperature hardness and heat resistance and toughness exhibited by the thin layer B, the hard coating layer has excellent high temperature hardness, Because it has heat resistance, high temperature strength, wear resistance, lubricity, impact resistance, chipping resistance, chipping resistance, as a result, it is accompanied by large heat generation, especially mild steel, general steel, high hardness steel, etc. Even in high-speed cutting with a high load, it exhibits excellent wear resistance and fracture resistance over a long period of time.

The arc ion plating apparatus used for forming the hard coating layer which comprises this invention coated tool and a comparative coated tool is shown, (a) is a schematic plan view, (b) is a schematic front view. It is a schematic explanatory drawing of the conventional arc ion plating apparatus explaining a prior art. It is a longitudinal cross-sectional film | membrane structural view of the hard coating layer which comprises this invention coated tool.

  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, and after sintering, tool bases A-1 to A-10 made of WC-base cemented carbide having an ISO standard / CNMG120408 insert shape were formed. .

In addition, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, mix these raw material powders into the composition shown in Table 2, wet mix for 24 hours with a ball mill, dry, and press-mold into green compact at 100 MPa pressure Then, this green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, a tool substrate B made of TiCN base cermet having an ISO standard / CNMG120408 insert shape was used. -1 to B-6 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 apparatus shown in FIG. A first electrode is provided with two cathode electrodes (evaporation sources) that are mounted along the outer peripheral portion at a predetermined distance in the radial direction from the central axis on the inner rotary table, and that face each other across the rotary table. An Al—Cr alloy having a predetermined composition for forming the thin layer A, and an Al—Ti alloy having a predetermined composition for forming the thin layer B as the second electrode,
(B) First, the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, and the inside of the apparatus is heated to 500 ° C. with a heater, and then rotated to a tool base that rotates while rotating on a rotary table. A DC bias voltage is applied, and an arc discharge is generated by flowing a current of 100 A between the Al—Cr alloy (cathode electrode) and the anode electrode, and the tool base surface is bombard washed.
(C) Next, nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 0.5 to 1.0 Pa, and a tool base that rotates while rotating on a rotary table is set to −20 to −30 V. A direct current bias voltage was applied and a current of 120 A was passed between the Al—Cr alloy of the cathode electrode and the anode electrode to generate an arc discharge, and the target composition shown in Table 3 was formed on the surface of the tool base. After vapor-depositing the (Al, Cr) N layer as the thin layer A having the target layer thickness, the arc discharge between the cathode electrode (evaporation source) and the anode electrode is stopped,
(D) Subsequently, the atmosphere in the apparatus is maintained in a nitrogen atmosphere of 0.5 to 9.0 Pa, and a DC bias voltage of −20 to −150 V is applied to the tool base that rotates while rotating on the rotary table, and the cathode A current of 120 A is passed between an Al—Ti alloy electrode, which is an electrode (evaporation source), and an anode electrode to generate an arc discharge, and a thin layer B having a target composition and a target layer thickness shown in Table 3 ( An Al, Ti) N layer was deposited.
By alternately repeating the steps (c) and (d), a hard coating layer having an alternate laminated structure having a total target layer thickness shown in Table 3 is formed on the tool substrate by vapor deposition, and the surface coating insert ( Hereinafter, the present invention coated inserts) 1 to 16 were produced.
The Young's modulus of the thin layer A was controlled by controlling the bias voltage and the nitrogen partial pressure as described above. That is, by setting a low bias voltage and a low nitrogen partial pressure, the Young's modulus of the (Al, Cr) N layer of the thin layer A can be controlled to a low Young's modulus. The Young's modulus of the (Al, Ti) N layer of the thin layer B was controlled by controlling the bias voltage and the nitrogen partial pressure as described above. That is, it can control to 400-550 GPa by forming into a film in the range of -20-150V and 0.5-9.0Pa. The conditions for forming the thin layer A and the thin layer B (bias voltage, nitrogen partial pressure) and Young's modulus are also shown in Table 3.
The Young's modulus was measured by a nanoindentation method using a nanoindenter (trademark of MTS Systems). Furthermore, about the thin layer A and the thin layer B of this invention covering insert 1-16, the crystal structure was specified using the X-ray-diffraction apparatus. The results are also shown in Table 3.

For comparison purposes,
(A) 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 in the arc ion plating apparatus shown in FIG. Attached along the outer periphery at a predetermined distance in the radial direction from the central axis on the rotary table, two cathode electrodes (evaporation sources) facing each other across the rotary table are arranged, and the first electrode is An Al—Cr alloy having a predetermined composition for forming the thin layer A and an Al—Ti alloy having a predetermined composition for forming the thin layer B are disposed as the second electrode,
(B) First, the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, and the inside of the apparatus is heated to 500 ° C. with a heater, and then rotated to a tool base that rotates while rotating on a rotary table. A DC bias voltage is applied, and an arc discharge is generated by flowing a current of 100 A between the Al—Cr alloy (cathode electrode) and the anode electrode, and the tool base surface is bombard washed.
(C) Next, nitrogen gas is introduced into the apparatus as a reaction gas to obtain a reaction atmosphere of 0.5 to 9.0 Pa, and a tool base rotating while rotating on a rotary table is set to −20 to −500 V. A direct current bias voltage was applied, and a current of 120 A was passed between the Al—Cr alloy of the cathode electrode and the anode electrode to generate an arc discharge, and the target composition shown in Table 4 was formed on the surface of the tool base. After vapor-depositing the (Al, Cr) N layer as the thin layer A having the target layer thickness, the arc discharge between the cathode electrode (evaporation source) and the anode electrode is stopped,
(D) Subsequently, the atmosphere in the apparatus is maintained in a nitrogen atmosphere of 0.5 to 9.0 Pa, and a DC bias voltage of −20 to −150 V is applied to the tool base that rotates while rotating on the rotary table, and the cathode A current of 120 A is passed between the Al—Ti alloy electrode, which is an electrode (evaporation source), and the anode electrode to generate an arc discharge, and the thin film B having the target composition and the target layer thickness shown in Table 4 ( An Al, Ti) N layer was deposited.
By alternately repeating the steps (c) and (d), a hard coating layer having an alternate laminated structure having a total target layer thickness shown in Table 4 is formed on the tool substrate by vapor deposition. (Referred to as a coated insert of the present invention) 1 to 8 were produced. The formation conditions (bias voltage, nitrogen partial pressure) of each layer are also shown in Table 4. Furthermore, the Young's modulus and crystal structure of the comparative coated inserts 1 to 8 were measured by the same method as described above. The results are also shown in Table 4.

Work material: JIS S10C (HB200) round bar,
Cutting speed: 300 m / min. ,
Cutting depth: 2.5mm,
Feed: 0.4 mm / rev. ,
Cutting time: 14 minutes
Of carbon steel under the above conditions (cutting conditions A) (normal cutting speed and feed are 200 m / min. And 0.3 mm / rev., Respectively),
Work material: JIS / SCM415 (HB280) round bar,
Cutting speed: 280 m / min. ,
Cutting depth: 3.0 mm,
Feed: 0.3 mm / rev. ,
Cutting time: 10 minutes,
Dry high-speed high-cut cutting test of alloy steel under the following conditions (cutting condition B) (normal cutting speed and cutting are 190 m / min. And 2.0 mm., Respectively),
Work material: JIS / SCM420H (HRC61) round bar,
Cutting speed: 100 m / min. ,
Cutting depth: 0.35mm,
Feed: 0.2 mm / rev. ,
Cutting time: 7 minutes
(High cutting speed, cutting and feed are 60 m / min., 0.2 mm., 0 respectively) .1 mm / rev.),
The flank wear width of the cutting edge was measured in any high-speed cutting test. The measurement results are shown in Tables 5 and 6.

As in Example 1, all of WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder having an average particle diameter of 1 to 3 μm. The raw material powder consisting of the above is blended in the composition shown in Table 1, wet mixed for 72 hours with a ball mill, dried, and then pressed into a green compact at a pressure of 100 MPa. , Temperature: Sintered at 1400 ° C. for 1 hour to form a round tool sintered body for forming a tool base having a diameter of 13 mm. WC-base cemented carbide tool bases (end mills) A-1 to A-10 having a four-blade square shape with a diameter x length of 10 mm x 22 mm and a twist angle of 30 degrees were manufactured, respectively. .

  Then, the surfaces of these tool bases (end mills) A-1 to A-10 were ultrasonically cleaned in acetone and dried, and then charged into the arc ion plating apparatus shown in FIG. 1, the target composition, target layer thickness, Young's modulus, thin layer A composed of (Al, Cr) N layer of crystal structure shown in Table 7, and target composition, target layer thickness shown in Table 7 The coated tool of the present invention is formed by vapor-depositing a hard coating layer having a target total layer thickness shown in Table 7 having an alternately laminated structure with a thin layer B made of an (Al, Ti) N layer having a Young's modulus and a crystal structure. The present invention surface-coated carbide end mills (hereinafter referred to as the present invention-coated end mills) 1 to 10 were produced.

For comparison purposes, the surfaces of the tool bases (end mills) A-1 to A-5 are ultrasonically cleaned in acetone and dried, and then loaded into the arc ion plating apparatus shown in FIG. In the same process as in Example 1, using the formation conditions (bias voltage, nitrogen partial pressure) shown in Table 8, the target composition, target layer thickness, Young's modulus, crystal structure (Al, Table 8 consisting of an alternating layered structure of thin layer A consisting of Cr) N layers and thin layer B consisting of (Al, Ti) N layers of the target composition, target layer thickness, Young's modulus and crystal structure shown in Table 8 Surface-coated carbide end mills (hereinafter referred to as comparative coated end mills) 1 to 5 as comparative coated tools were produced by vapor-depositing a hard coating layer having a target total layer thickness shown in FIG.
Next, for the present invention coated end mills 1-10 and comparative coated end mills 1-5,
Work material-Plane dimension: 100 mm x 250 mm, thickness: 50 mm JIS S10C (HB200) plate material,
Cutting speed: 300 m / min. ,
Groove depth (cut): 5.0 mm,
Table feed: 2000 mm / min. ,
Carbon steel dry high-speed grooving test under normal conditions (cutting conditions D) (normal cutting speed and table feed are 200 m / min. And 1400 mm / min., Respectively),
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SCM415 (HB280) plate material,
Cutting speed: 250 m / min. ,
Groove depth (cut): 3.0 mm,
Table feed: 1800 mm / min. ,
(High cutting speed and table feed are 150 m / min. And 1400 mm / min., Respectively)
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SCM420H (HRC61) plate material,
Cutting speed: 100 m / min. ,
Groove depth (cut): 1.0 mm,
Table feed: 300 mm / min. ,
(High cutting speed and table feed are 50 m / min and 210 mm / min, respectively)
In each high-speed groove cutting test, 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 also shown in Tables 7 and 8, respectively.

  The round bar sintered body with a diameter of 13 mm manufactured in Example 2 was used, and from this round bar sintered body, the dimensions of the groove forming part diameter × length were 8 mm × 22 mm and the twist angle by grinding. WC-base cemented carbide tool bases (drills) A-1 to A-10 having a 30-degree two-blade shape were produced, respectively.

  Next, the cutting edges of these tool bases (drills) A-1 to A-10 are subjected to honing, ultrasonically cleaned in acetone, and dried to the arc ion plating apparatus shown in FIG. The thin film A composed of the (Al, Cr) N layer having the target composition, target layer thickness, and Young's modulus shown in Table 9 under the same conditions as in Example 1, and the target composition also shown in Table 9 By subjecting the present invention to vapor deposition of a hard coating layer having the target total layer thickness shown in Table 9, which consists of an alternately laminated structure with the thin layer B consisting of the (Al, Ti) N layer having the target layer thickness and Young's modulus. The surface-coated carbide drills of the present invention (hereinafter referred to as the present invention-coated drills) 1 to 10 as coated tools were produced, respectively.

  For comparison purposes, the surfaces of the tool bases (drills) A-1 to A-5 are subjected to honing, ultrasonically cleaned in acetone and dried, and the arc ion plate shown in FIG. The target composition, target layer thickness, Young's modulus, and crystal shown in Table 10 were charged in the same process as in Example 1 using the formation conditions (bias voltage and nitrogen partial pressure) shown in Table 10 in the same process as Example 1. Alternating lamination of thin layer A composed of (Al, Cr) N layers having a structure and thin layer B composed of (Al, Ti) N layers having a target composition, target layer thickness, Young's modulus and crystal structure shown in Table 10 Surface-coated carbide drills (hereinafter referred to as comparative coated drills) 1 to 5 as comparative coated tools were manufactured by vapor-depositing a hard coated layer having a target total layer thickness shown in Table 10 having a structure. .

Next, for the present invention coated drills 1-10 and comparative coated drills 1-5,
Work material-Plane dimension: 100 mm x 250 mm, thickness: 50 mm JIS S10C (HB200) plate material,
Cutting speed: 170 m / min. ,
Feed: 0.40 mm / rev. ,
Hole depth: 6mm,
Carbon steel dry high speed drilling test under normal conditions (cutting condition G) (normal cutting speed and feed are 100 m / min. And 0.3 mm / rev., Respectively),
Work material-Plane dimension: 100 mm x 250 mm, thickness: 50 mm JIS / SCM415 (HB280) plate material,
Cutting speed: 130 m / min. ,
Feed: 0.35 mm / rev. ,
Hole depth: 6mm,
(High cutting speed and feed are 80 m / min. And 0.25 mm / rev., Respectively)
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SCM420H (HRC61) plate material,
Cutting speed: 50 m / min. ,
Feed: 0.20 mm / rev. ,
Hole depth: 6mm,
(High cutting speed and feed rate are 30 m / min. And 0.12 mm / rev., Respectively)
In each dry high-speed drilling test, 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 also shown in Table 9 and Table 10, respectively.

  As a result of this, it is a thin layer A constituting the hard coating layer of the present invention coated inserts 1-16 as the present invention coated tool, the present coated end mill 1-10, and the present coated drill 1-10 (Al, Cr) N layer and thin layer B (Al, Ti) N layer composition, comparative coated inserts 1-8 as comparative coated tools, comparative coated end mills 1-5, and comparative coated drills 1-5 hard The composition of the (Al, Cr) N layer, which is the thin layer A and the (Al, Ti) N layer, which is the thin layer B constituting the coating layer, is measured by energy dispersive X-ray analysis using a transmission electron microscope. As a result, each showed substantially the same composition as the target composition.

  Moreover, when the average layer thickness of each layer which comprises the said hard coating layer was cross-sectional measured using the scanning electron microscope, all showed the average layer thickness (average value of five places) substantially equal to target layer thickness. .

  From the results shown in Tables 3 to 10, the coated tool of the present invention has an alternately laminated structure including a thin layer A having a predetermined composition, a target layer thickness, and a Young's modulus, and a thin layer B having a predetermined composition and a target layer thickness. As a result of forming a hard coating layer, the thin layer A (Al, Cr) N layer having a low Young's modulus is firmly adhered and bonded to the surface of the tool substrate, providing excellent fracture resistance, high temperature hardness, and high temperature strength. In addition, the (Al, Ti) N layer, which is a thin layer B, improves heat resistance and wear resistance, and has an impact resistance due to a synergistic effect by alternately laminating thin layers A and B having different compositions. As a result of improving chipping resistance and crack progress resistance, excellent chipping resistance is ensured even in high-speed cutting such as mild steel, general steel, and high hardness steel, and chipping does not occur and excellent long-term resistance. Exhibits abrasion. On the other hand, as the hard coating layer, although it has an alternate laminated structure of thin layers A and thin layers B having different compositions, the Young's modulus of the (Al, Cr) N layer of the thin layer A is not controlled. In the comparative coated tool whose composition of each layer and target layer thickness deviate from the range specified in the present invention, the wear resistance is not sufficient in high-speed cutting such as mild steel, general steel, high hardness steel, etc. It is clear that chipping occurs at the cutting edge due to the lowering of the toughness, and the service life is reached in a relatively short time.

  As described above, the coated tool of the present invention is excellent in wear resistance and fracture resistance not only in cutting of general work materials, but also in high-speed cutting of soft steel, general steel, hard steel, etc. Since it exhibits excellent cutting performance and exhibits excellent cutting performance over a long period of time, it can satisfactorily respond to automation of the cutting apparatus, labor saving and energy saving of cutting, and cost reduction.

Claims (1)

In a surface-coated cutting tool formed by forming a hard coating layer on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
The hard coating layer is
(A) having an average layer thickness of 0.1 to 1.0 μm, and
Composition formula: (Al _1-x Cr _x ) N (where x represents the content ratio of Cr in the total amount of Al and Cr, and the atomic ratio is 0.25 ≦ x ≦ 0.50) Satisfied, a thin layer A composed of a composite nitride of Al and Cr having a Young's modulus a of 150 GPa ≦ a ≦ 300 GPa,
(B) having an average layer thickness of 0.1 to 1.0 μm, and
Composition formula: (Al _1-y Ti _y ) N (where y represents the content ratio of Ti in the total amount of Al and Ti, and the atomic ratio is 0.25 ≦ y ≦ 0.55) A thin layer B composed of a composite nitride layer of Al and Ti satisfying and having a Young's modulus b of 400 GPa ≦ b ≦ 550 GPa;
(C) Immediately above the tool substrate is the thin layer A, and has an alternate laminated structure of the thin layer A and the thin layer B, and the total average layer thickness is 1.0 to 10 μm.
A surface-coated cutting tool characterized by satisfying the conditions (a) to (c).