JP5975342B2 - 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 required to improve wear resistance and chipping resistance with respect to the coating film covering the substrate surface of the 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 includes a coating formed on a tool base of a surface-coated cutting tool, and this coating is formed by alternately laminating one or more first super multi-layer films and two or more super multi-layer films. The first super multi-layer film is formed by alternately laminating one or more layers of A1 layers and B layers, and the second super multi-layer film is composed of A2 layers and C layers. Each of the A1 and A2 layers is composed of any one of TiN, TiCN, TiAlN, or TiAlCN, and the B layer is composed of TiSiN or TiSiCN. Disclosed is that the C layer is composed of AlCrN or AlCrCN to provide a surface-coated cutting tool having a coating with reduced brittleness problems while maintaining heat resistance and wear resistance. That.

  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, the tool base is vapor-deposited on the surface of the tool base, for example, under the condition that a bias voltage of −200 V is applied (Al, Cr). It is also known that a hard coating layer composed of an N layer is manufactured (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 work. 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) Therefore, the present inventors configure the hard coating layer from a lower layer made of a (Al, Cr) N layer having a low Young's modulus and an upper layer made of a (Al, Cr) N layer having a high Young's modulus. Therefore, the upper layer and the lower layer having different Young's moduli can complement the defects of the (Al, Cr) N layer, and a hard coating layer having excellent cutting performance that is not found in conventional coating layers can be obtained. New findings were obtained.
Based on such knowledge, the present invention was obtained as a result of detailed analysis of the relationship between the cutting performance and the composition of the upper layer, the lower layer, the crystal structure, the layer thickness, the Young's modulus, and the like. Has the following configuration.
Cubic compound nitride layer of Al and Cr containing Cr component 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% on the surface of the tool base. A low Young's modulus layer having a Young's modulus a of 150 GPa ≦ a ≦ 300 GPa (hereinafter referred to as a low Young's modulus (Al, Cr) N layer) is used as a lower layer with an average layer thickness of 0.5 to 1.0 μm. A composite nitride layer of Al and Cr that is formed and on which a Cr component is contained so that the Cr content in the total amount of Al and Cr is 25 to 50 atomic%; A high Young's modulus layer having a Young's modulus b of 500 GPa ≦ b ≦ 800 GPa (hereinafter referred to as a high Young's modulus (Al, Cr) N layer) is formed as an upper layer with an average layer thickness of 0.5 to 9.0 μm, Layer thickness of lower layer ≦ layer thickness of upper layer, and the total layer thickness is 1 By forming a layer having a thickness of 0.0 to 10 μm, the lower Young's modulus (Al, Cr) N layer of the lower layer exhibits excellent adhesion, fracture resistance, and abrasion resistance, and the high Young constituting the upper layer The rate (Al, Cr) N layer exhibits excellent wear resistance and heat resistance, and is excellent due to the bonding of the low Young's modulus (Al, Cr) N layer and the high Young's modulus (Al, Cr) N layer. Impact resistance, fracture resistance, and crack growth resistance are achieved. Furthermore, the upper and lower layers are both cubic, which improves the adhesion between the layers. The present inventors have obtained a new knowledge that it can exhibit the properties and wear resistance, and have completed the present invention based on such knowledge.

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 0.5 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) A lower layer consisting of a cubic composite nitride layer of Al and Cr satisfying and having a Young's modulus a of 150 GPa ≦ a ≦ 300 GPa;
(B) having an average layer thickness of 0.5 to 9.0 μm, and
Composition formula: (Al _1-y Cr _y ) N (where y represents the content ratio of Cr in the total amount of Al and Cr, and the atomic ratio is 0.25 ≦ y ≦ 0.50) An upper layer consisting of a cubic composite nitride layer of Al and Cr satisfying and having a Young's modulus b of 500 GPa ≦ b ≦ 800 GPa,
A surface-coated cutting tool comprising a laminated structure of a lower layer and an upper layer satisfying the conditions (a) and (b). "
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, crystal structure, average layer thickness and Young's modulus of (Al, Cr) N layer constituting the lower layer:
The Al component, which is a component of the (Al, Cr) N layer that constitutes the lower layer, improves the high temperature hardness of the hard coating layer, and the Cr component has the effect of improving the high temperature strength. When the x value indicating the ratio is less than 0.25 in the ratio with respect to the total amount of Al (atomic ratio, the same applies hereinafter), the content ratio of Al is relatively increased, so that the crystal structure is changed from cubic to hexagonal. In order to maintain at least a predetermined film hardness, the crystal structure needs to be cubic. For this purpose, the x value indicating the Cr content ratio needs to be 0.25 or more in terms of the ratio of the total amount with Al (atomic ratio, the same shall apply hereinafter). On the other hand, when the x value indicating the Cr content ratio exceeds 0.50, the Al content ratio is relatively reduced, and the high temperature hardness required for high-speed cutting cannot be ensured. The x value was determined to be 0.25 to 0.50 because it would be difficult to prevent the occurrence of.

In addition, if the average layer thickness of the (Al, Cr) N layer constituting the lower layer is less than 0.5 μm, it is insufficient to exhibit its excellent wear resistance over a long period of time, If the average layer thickness exceeds 1.0 μm, chipping is likely to occur at the cutting edge portion in the high-speed cutting, so the average layer thickness was determined to be 0.5 to 1.0 μm.
Furthermore, the amount of deformation of the coating when external stress is applied increases by causing the Young's modulus of the (Al, Cr) N layer constituting the lower layer to be 150 to 300 GPa, thereby causing cracks and the like. In order to prevent, 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, crystal structure, average layer thickness and Young's modulus of the (Al, Cr) N layer constituting the upper layer:
The (Al, Cr) N layer constituting the upper layer has excellent oxidation resistance and heat resistance, and also has excellent lubricity due to its constituent Cr component, and also by the Al component. Complements the high temperature hardness. Therefore, a low coefficient of friction is maintained even under high temperature cutting conditions, and excellent heat resistance is exhibited. However, the ratio of the y value indicating the Cr content to the total amount with Al (atomic ratio, the same applies hereinafter) If it is less than 0.25, the lubricity cannot be ensured, so that welding resistance cannot be expected. On the other hand, if the y value indicating the Cr content exceeds 0.50, Since the content ratio of Al is reduced and the high-temperature hardness required for high-speed cutting cannot be ensured, the wear resistance is also lowered, and it becomes difficult to prevent chipping. 0.25 to 0.50 (atomic ratio, the same applies hereinafter). Furthermore, by making the crystal structure of the (Al, Cr) N layer constituting the upper layer the same cubic crystal as that of the lower layer, the adhesion between the layers is improved, and the problem of deterioration of life due to delamination is eliminated.

Further, if the average layer thickness of the (Al, Cr) N layer constituting the upper layer is less than 0.5 μm, it is insufficient to exhibit its excellent oxidation resistance and heat resistance over a long period of time. On the other hand, if the average layer thickness exceeds 9.0 μm, the film will self-destruct due to impact during use in high-speed cutting, and chipping is likely to occur at the cutting edge. ˜9.0 μm.

  Furthermore, by setting the Young's modulus of the (Al, Cr) N layer constituting the upper layer to a high Young's modulus of 500 to 800 GPa, the wear resistance and heat resistance can be improved, and the effect of the lower layer can be achieved. In combination, excellent wear resistance and fracture resistance can be exhibited. Here, the reason why the Young's modulus is limited to 500 to 800 GPa is that when the Young's modulus is less than 500 GPa, the effect of improving the wear resistance and heat resistance is not sufficiently achieved, while when it is greater than 800 GPa Since chipping is likely to occur, chipping is likely to occur. Therefore, the Young's modulus of the upper layer is limited to 500 to 800 GPa from the viewpoint of improving the wear resistance and fracture resistance of the hard coating layer.

The (Al, Cr) N layer constituting the lower layer and the (Al, Cr) N layer constituting the upper layer constituting the hard coating layer of the present invention are, for example, physically shown in a schematic explanatory diagram in FIG. A tool base is placed in an arc ion plating apparatus, which is a kind of vapor deposition apparatus, and the inside of the apparatus is heated to a temperature of, for example, 500 ° C. with a heater. A cathode electrode (evaporation source) made of an alloy is arranged, and an arc discharge is generated between the anode electrode and the Al—Cr alloy as the cathode electrode (evaporation source), for example, at a current of 100 A, and at the same time in the apparatus Nitrogen gas is introduced as a reaction gas to form a reaction atmosphere of, for example, 0.8 Pa. On the other hand, the tool base is vapor-deposited for a predetermined time under the condition that, for example, a bias voltage of −20 V is applied. Layer thickness, which is the lower layer of the Young's modulus (Al, Cr) layer is formed. Next, between the anode electrode and the Al—Cr alloy as the cathode electrode (evaporation source), for example, arc discharge is generated under the condition of current: 100 A, and at the same time, nitrogen gas is introduced into the apparatus as a reaction gas, For example, the reaction atmosphere is 3.0 Pa, and the tool substrate is vapor-deposited for a predetermined time, for example, under the condition that a bias voltage of −100 V is applied, thereby forming a predetermined Young's modulus with a predetermined target layer thickness on the lower layer. An (Al, Cr) N layer is formed as an upper layer. In this manner, the hard coating layer of the present invention having a two-layer structure can be formed by vapor deposition. That is, the Young's modulus of the (Al, Cr) N layer can be controlled by adjusting the reaction atmospheric pressure and the bias voltage applied to the tool substrate.

  According to one aspect of the coated tool of the present invention, the hard coating layer has a laminated structure of a lower layer made of a low Young's modulus (Al, Cr) N layer and an upper layer made of a high Young's modulus (Al, Cr) N layer. In addition, by making the Young's modulus of the (Al, Cr) N layer constituting the upper layer higher than that of the lower layer, the hard coating layer has excellent high temperature hardness, heat resistance, high temperature strength, wear resistance. As a whole, in addition to excellent high-temperature hardness, heat resistance, high-temperature strength, etc., it has excellent fracture resistance and welding resistance. Even in high-speed cutting with mild heat generation, such as mild steel, general steel, and high-hardness steel, and with high loads, 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 for demonstrating a prior art. The longitudinal cross-sectional film | membrane structural view of the hard coating layer which comprises this invention coated tool is shown.

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

As raw material powders, 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 used. Prepared, these raw material powders were blended in the blending 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. Sintered in vacuum at a temperature of 1400 ° C. for 1 hour. After sintering, tool bases A-1 to A-10 made of WC-base cemented carbide with ISO standard / CNMG120408 insert shape are formed. did.

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. As an Al-Cr alloy having a predetermined composition for forming the lower layer, and as the second electrode, an Al-Cr alloy having a predetermined composition for forming the upper layer is disposed,
(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 lower layer of 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 3.0 to 9.0 Pa, and a DC bias voltage of −50 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—Cr alloy electrode, which is an electrode (evaporation source), and an anode electrode to generate an arc discharge, and (Al) as an upper layer of the target composition and target layer thickness shown in Table 3 , Cr) N layer was deposited.
A hard coating layer was formed on the tool substrate by vapor deposition according to the above (a) to (d), and surface coated inserts (hereinafter referred to as the present coated inserts) 1 to 16 as the coated tools of the present invention were produced.
The Young's modulus of each layer was controlled by controlling the bias voltage and the nitrogen partial pressure as described above. That is, the lower layer is formed with a low bias voltage and a low nitrogen partial pressure, and the upper layer is formed with a high bias voltage and a high nitrogen partial pressure, so that the Young's modulus of the lower (Al, Cr) N layer is reduced. The Young's modulus of the (Al, Cr) N layer of the upper layer can be controlled to a high Young's modulus with a low Young's modulus. The formation conditions (bias voltage, nitrogen partial pressure) of each layer 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 upper layer and lower layer 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, 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 plate shown in FIG. The device is loaded with two kinds of Al-Cr alloys having a predetermined composition as cathode electrodes (evaporation sources). First, the device is evacuated and kept at a vacuum of 0.1 Pa or less with a heater. After heating the inside to 500 ° C., a DC bias voltage of −1000 V is applied to the tool base, and a current of 150 A is passed between the Al—Cr alloy of the cathode electrode and the anode electrode to generate arc discharge. Accordingly, the surface of the tool base is bombarded with the Al—Cr alloy, and then nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of 0.5 to 9.0 Pa and applied to the tool base. The bias voltage is set to -20 to -500 V, arc discharge is generated between each cathode electrode and anode electrode having a predetermined composition, and the target composition and target layer thickness shown in Table 4 are formed on the surface of the tool base. After vapor-depositing the (Al, Cr) N layer as the lower layer, the arc discharge between the cathode electrode (evaporation source) and the anode electrode was stopped, and subsequently the atmosphere in the apparatus was 0.5 to 9.0. A DC bias voltage of −20 to −500 V is applied to a tool base that rotates while rotating on a rotary table while being held in a nitrogen atmosphere, and an Al—Cr alloy electrode that is a cathode electrode (evaporation source), an anode electrode, A current of 120 A was passed between them to generate arc discharge, and an (Al, Cr) N layer as an upper layer having a target composition and a target layer thickness shown in Table 4 was formed by evaporation. Therefore, on each surface of the tool bases A-1 to A-10 and B-1 to B-6, a lower layer composed of an (Al, Cr) N layer having a target composition and a target layer thickness shown in Table 4; Surface coated inserts (hereinafter referred to as comparative coated inserts) 1 to 8 as comparative coated tools were manufactured by vapor-depositing a conventional hard coated layer composed of an upper layer composed of an Al, Cr) N layer, respectively. . The formation conditions (bias voltage, nitrogen partial pressure) of each layer are also shown in Table 4. Further, the Young's modulus and crystal structure of the lower and upper layers 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.

Next, with the various coated inserts, all of the present invention coated inserts 1 to 16 and comparative coated inserts 1 to 8 in a state where all the tool inserts are screwed to the tip of the tool steel tool with a fixing jig.
Work material: JIS S10C (HB200) round bar,
Cutting speed: 240 m / min. ,
Cutting depth: 2.5mm,
Feed: 0.35 mm / rev. ,
Cutting time: 8 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: 220 m / min. ,
Cutting depth: 2.5 mm,
Feed: 0.3 mm / rev. ,
Cutting time: 6 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: 70 m / min. ,
Cutting depth: 0.3mm,
Feed: 0.15 mm / rev. ,
Cutting time: 4 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 under the same conditions, the target composition, target layer thickness, Young's modulus shown in Table 7, the lower layer consisting of (Al, Cr) N layer of crystal structure, and the target composition, target layer thickness shown in Table 7, A hard coating layer composed of an upper layer composed of a Young's modulus and a crystal structure (Al, Cr) N layer is formed by vapor deposition, so that the surface coated carbide end mill of the present invention as the coated tool of the present invention (hereinafter referred to as this 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, A hard coating layer composed of a lower layer made of a Cr) N layer and an upper layer made of an (Al, Cr) N layer having the target composition, target layer thickness, Young's modulus, and crystal structure shown in Table 8 is also deposited. By forming, surface coated carbide end mills (hereinafter referred to as comparative coated end mills) 1 to 5 as comparative coated tools were manufactured, respectively.
Next, for the present invention coated end mills 1-10 and comparative coated end mills 1-5,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / S10C (HB200) plate material,
Cutting speed: 250 m / min. ,
Groove depth (cut): 5.0 mm,
Table feed: 1600 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: 180 m / min. ,
Groove depth (cut): 3.0 mm,
Table feed: 1500 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: 70 m / min. ,
Groove depth (cut): 1.0 mm,
Table feed: 230 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. Under the same conditions as in Example 1, the lower layer composed of the (Al, Cr) N layer having the target composition, target layer thickness and Young's modulus shown in Table 9, and the target composition and target shown in Table 9 The surface coated carbide drill of the present invention as the coated tool of the present invention (hereinafter, coated by the present invention) is formed by vapor-depositing a hard coating layer comprising an upper layer composed of an (Al, Cr) N layer having a layer thickness and Young's modulus. (Referred to as drills) 1 to 10 were produced.

  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. In the same process as in Example 1, using the formation conditions (bias voltage, nitrogen partial pressure) shown in Table 10, the target composition, target layer thickness, Young's modulus and An upper layer composed of a lower layer composed of an (Al, Cr) N layer having a crystal structure and an upper layer composed of an (Al, Cr) N layer having a target composition, target layer thickness, Young's modulus and crystal structure shown in Table 10 Surface-coated cemented carbide drills (hereinafter referred to as comparative coated drills) 1 to 5 as this comparative coated tool were produced by vapor-depositing a hard coating layer made of

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: 130 m / min. ,
Feed: 0.35 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: 100 m / min. ,
Feed: 0.3 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: 35 m / min. ,
Feed: 0.15 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.

  The resulting coated inserts 1 to 16 as the present invention coated tool, the present coated end mills 1 to 10 and the lower layer constituting the hard coating layer of the present coated drill 1 to 10 (Al, Cr) ) The composition of the N layer and the upper layer (Al, Cr) N layer, and the lower layer of the comparative coated inserts 1-8, comparative coated end mills 1-5, and comparative coated drills 1-5 as comparative coated tools The composition of a hard coating layer composed of an (Al, Cr) N layer and an upper (Al, Cr) N layer was measured by energy dispersive X-ray analysis using a transmission electron microscope. The composition was substantially the same as the 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 formed a hard coating layer composed of a lower layer and an upper layer having a predetermined composition and target layer thickness, and as a result, a lower Young's modulus (Al, In a state where the Cr) N layer is tightly bonded to the surface of the tool base, it has excellent fracture resistance, high temperature hardness, high temperature strength, and the Young's modulus of the upper (Al, Cr) N layer is high. Rate improves wear resistance and improves the impact resistance, chipping resistance, and crack progress resistance by the synergistic effect of stacking the upper and lower layers with different Young's modulus. Even in high-speed cutting of steel, high hardness steel, etc., excellent fracture resistance is ensured, and chipping does not occur, and excellent wear resistance is exhibited over a long period of time. On the other hand, although it has a laminated structure of the lower layer and the upper layer as the hard coating layer, the Young's modulus of the (Al, Cr) N layer of the lower layer and the upper layer is not controlled, the composition of each layer, the target In comparative coated tools whose layer thickness deviates from the range specified in the present invention, wear resistance is not sufficient and high film toughness is reduced in high-speed cutting such as mild steel, general steel, and hard steel. For this reason, chipping occurs at the cutting edge, and it is clear that 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 0.5 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) A lower layer consisting of a cubic composite nitride layer of Al and Cr satisfying and having a Young's modulus a of 150 GPa ≦ a ≦ 300 GPa;
(B) having an average layer thickness of 0.5 to 9.0 μm, and
Composition formula: (Al _1-y Cr _y ) N (where y represents the content ratio of Cr in the total amount of Al and Cr, and the atomic ratio is 0.25 ≦ y ≦ 0.50) An upper layer consisting of a cubic composite nitride layer of Al and Cr satisfying and having a Young's modulus b of 500 GPa ≦ b ≦ 800 GPa,
A surface-coated cutting tool comprising a laminated structure of a lower layer and an upper layer satisfying the conditions (a) and (b).