JP2010201576A - Surface coated cutting tool with hard coating layer exerting excellent chipping resistance and wear resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cutting tool the hard coating layer of which exerts excellent chipping resistance and wear resistance in heavy cutting work. <P>SOLUTION: The surface coated cutting tool has the hard coating layer on a surface of a tool base consisting of cemented carbide, cermet, and a boron nitride based ultra-high-pressure sintered material in cubic crystal form. When a lower layer is represented by a composition formula: (Cr<SB>1-X</SB>Al<SB>X</SB>)N, the lower layer is a Cr-Al complex nitride layer having X satisfying 0.4-0.7 (X is an atomic ratio). When an upper layer is represented by a composition formula: (Cr<SB>1-Y-Z</SB>Si<SB>Y</SB>W<SB>Z</SB>)N, the upper layer is a Cr-Si-W complex nitride layer having Y satisfying 0.05-0.3 and Z satisfying 0.2-0.5 (Y, Z is an atomic ratio). Both layers are formed by vapor deposition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention has an excellent lubrication effect because the hard coating layer is also excellent when used under severe cutting conditions such as heavy cutting, such as steel, which places a large mechanical load on the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits fracture resistance and wear resistance, and as a result exhibits excellent cutting performance over a long period of use.

  In general, for coated tools, inserts that are detachably attached to the tip of a cutting tool for turning of work materials such as various types of steel and cast iron, and the inserts are detachably attached to be used for chamfering and grooving. An insert type end mill that performs cutting processing in the same manner as a solid type end mill used for processing and shoulder processing is known.

Further, as a coated tool, tungsten carbide (hereinafter referred to as WC) based cemented carbide, titanium carbonitride (hereinafter referred to as TiCN) based cermet, or various types of cubic boron nitride (hereinafter referred to as cBN) based ultra high pressure. A composite nitride of Cr and Al satisfying (Cr _1-X Al _X ) N (wherein X is 0.40 to 0.70 in atomic ratio) on the surface of the tool body made of a sintered material ( Hereinafter, a coated tool formed by physically vapor-depositing a hard coating layer (denoted by (Cr, Al) N) has been proposed and used for continuous cutting and intermittent cutting of various steels and cast irons (Patent Literature) 1-3).
Also, there are coated tools that attempt to improve high-speed cutting performance by forming a composite nitride layer containing a predetermined amount of Cr, Si, and Mo as a hard coating layer on the surface of the tool base. It has been proposed (Patent Document 4).

JP 2004-50381A Japanese Patent No. 3669700 JP 2006-524748 A International Publication WO2006 / 005217 Pamphlet

  In recent years, the FA of cutting machines has been remarkable, and in addition, there are strong demands for labor saving, energy saving, cost reduction and efficiency for cutting, and with this, heavy cutting such as high feed and high cutting is required. However, with the above-mentioned conventional coated tools, there are no particular problems when various types of steel and cast iron are machined under normal conditions, but for heavy-duty machining that places a heavy load on the cutting edge. When it is used, welding is likely to occur at the cutting edge portion, which causes defects and leads to a service life in a relatively short time.

In view of the above, the present inventors have conducted intensive research in order to improve the fracture resistance of the conventional coated tool.
The inventors of the present invention, in the above-mentioned conventional coated tool in which the hard coating layer is composed of a single layer of Cr and Al composite nitride ((Cr, Al) N), has a (Cr, Al) N layer. If the upper layer is composed of a composite nitride of Cr, Si and W (hereinafter referred to as (Cr, Si, W) N) as a lower layer, a hard coating is generated due to the generation of high heat during cutting. The constituent components of Si and W are oxidized on the surface of the layer to be present on the surface of the layer in the form of silicon oxide and tungsten oxide, and the silicon oxide and tungsten oxide are excellent in lubrication. As a result, the chip flow during cutting is improved and the occurrence of chipping due to chip welding, peeling, etc. is suppressed, and as a result, excellent cutting performance is demonstrated over a long period of use. In particular, the hard cover of the drill When the layer is formed of a lower layer made of a (Cr, Al) N layer and an upper layer made of a (Cr, Si, W) N layer, the chip discharge performance is good due to the flute groove of the drill. Therefore, excellent cutting performance will be exhibited not only in wet cutting but also in dry cutting.
Was found.

This invention has been made based on the above findings,
`` On the surface of the cutting tool base made of cemented carbide, cermet or cubic boron nitride based ultra high pressure sintered body,
(A) As a lower layer, it has an average layer thickness of 0.5 to 5 μm,
Composition formula: (Cr _1-X Al _X ) N
X is a composite nitride layer of Cr and Al that satisfies 0.4 to 0.7 (where X represents an atomic ratio),
(B) As an upper layer, it has an average layer thickness of 0.5 to 5 μm,
Composition _{formula: (Cr 1-Y-Z} Si Y W Z) N
Y is 0.05 to 0.3, Z is 0.2 to 0.5 (provided that Y and Z indicate atomic ratios), a composite nitride layer of Cr, Si and W,
A surface-coated cutting tool (coated tool) in which a hard coating layer comprising the above (a) and (b) is formed by vapor deposition. "
It has the characteristics.

  In the (Cr, Al) N layer constituting the lower layer of the hard coating layer of the coated tool of the present invention, the Cr component improves the high temperature strength, while the Al component improves the high temperature hardness and heat resistance (high temperature characteristics). Therefore, if the X value indicating the content ratio of the Al component is 0.7 or more in terms of the total amount with the Cr component (atomic ratio), the proportion of Cr becomes relatively small. As a result, the high temperature strength of the layer itself is inevitably lowered, and as a result, chipping or the like is likely to occur. On the other hand, when the X value is less than 0.4, the ratio of Al becomes relatively small, which is desirable. Therefore, the X value is determined to be 0.4 to 0.7, and the average thickness of the lower layer is 0. If it is less than 5 μm, it is not sufficient to ensure the desired wear resistance. Min and whereas if the average layer thickness exceeds 5 [mu] m, since the peeling or chipping of the film is likely to occur, determined the average layer thickness and 0.5 to 5 [mu] m.

In the (Cr, Si, W) N layer constituting the upper layer of the hard coating layer of the coated tool of the present invention, the Cr component improves the high temperature strength, the Si component improves the heat resistance, and the W component increases the hardness. In addition, the N component has the effect of improving the strength of the layer, and by coexisting these components, the N component has high hardness, excellent strength, and excellent heat resistance.
Furthermore, both Si and W components exist as silicon oxide and tungsten oxide with excellent lubricity on the surface of the hard coating layer due to high heat during cutting, and the presence of these oxides improves chip flow. In addition, the occurrence of defects caused by chip welding, peeling, and the like is suppressed.
If the content ratio (Y value) of the Si component as the constituent component of the upper layer is less than 0.05, the desired heat resistance improvement effect cannot be expected, while the content ratio (Y value) exceeds 0.3. Then, since the lattice strain due to the Si atoms becomes too large and the desired high-temperature strength cannot be obtained, the Y value was set to 0.05 to 0.3 in terms of atomic ratio. Similarly, if the content ratio (Z value) of the W component, which is a constituent component of the upper layer, is less than 0.2, the desired lubricity improvement effect cannot be expected, while the content ratio (Z value) is 0. If it exceeds 5, the desired high-temperature strength can no longer be obtained due to a relative decrease in the Cr component content, so the Z value was determined to be 0.2 to 0.5 in terms of atomic ratio.
Furthermore, due to the high temperature during cutting, chromium oxide, tungsten oxide, and silicon oxide are formed on the surface of the upper layer, and in particular, silicon oxide that is dense and excellent in lubricity is formed on the surface of the upper layer. However, in order to obtain the desired lubricity, the content ratio of the Si component (Y value) and the content ratio of the W component (Z value) are set to 0.05 to 0.3 and 0.2 to 0.00, respectively. If it is out of this range, lubricity and chip evacuation will be reduced, and breakage resistance and wear resistance will be reduced in high-feed, high-cut heavy cutting. To come.
Further, if the average layer thickness of the upper layer is less than 0.5 μm, it is insufficient to ensure the desired wear resistance over a long period of use, while if the average layer thickness exceeds 5 μm, Since peeling and chipping are likely to occur, the average layer thickness was determined to be 0.5 to 5 μm.

Further, the lower layer made of the (Cr, Al) N layer and the upper layer made of the (Cr, Si, W) N layer are made of hard arc layers as shown in FIG. ) Apparatus (however, an AIP apparatus provided with a cathode electrode for forming a (Cr, Al) N layer and a cathode electrode for forming a (Cr, Si, W) N layer)
Substrate temperature: 450-600 ° C
Bias voltage: -30 to -70 V
Nitrogen partial pressure: 2-4 Pa
It can be formed by vapor deposition under the following vapor deposition conditions.

  In the coated tool of the present invention, the (Cr, Al) N layer constituting the lower layer of the hard coating layer exhibits excellent wear resistance during the cutting process, and the upper layer (Cr, Si, W). ) The N layer, especially silicon oxide and tungsten oxide formed on the surface layer, has excellent lubricity and improves chip discharge, so it is excellent in both heavy cutting and dry cutting. In addition to exhibiting chipping resistance, it exhibits excellent wear resistance over a long period of use.

It is a schematic explanatory drawing of the arc ion plating (AIP) apparatus used in carrying out vapor deposition formation of the hard coating layer of this invention coated tool and the conventional coated tool.

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

As raw material powders, WC powder, TiC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder, all having an average particle diameter of 1 to 3 μm, were prepared. And then wet-mixed with a ball mill for 72 hours, dried, and press-molded into a green compact at a pressure of 100 MPa. The green compact was vacuumed at 6 Pa at a temperature of 1400 ° C. for 1 hour. Sintered under holding conditions, and after sintering, tool edge A-1 made of WC-based cemented carbide with ISO standard and CNMG120408 insert shape by applying a honing process of R: 0.03 to the cutting edge portion. A-10 was formed.

Further, 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 The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour. After sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to meet ISO standards / Tool bases B-1 to B-6 made of TiCN-based cermet having an insert shape of CNMG120408 were formed.

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 attached to the arc ion plating apparatus shown in FIG. As a cathode electrode, a Cr—Al alloy, a Cr—Si—W alloy and a bombard cleaning metal Ti (not shown) having a predetermined composition are mounted. First, the inside of the apparatus is evacuated to 1 × 10 ⁻² Pa or less. The tool base is heated to 500 ° C. while maintaining a vacuum of −100 V, a −1000 V DC bias voltage is applied to the tool base, and 100 A is applied between the bombard cleaning metal Ti (not shown) and the anode electrode. Current is caused to flow to cause arc discharge, and the surface of the tool base is cleaned with Ti bombardment, and then nitrogen gas is introduced into the apparatus as a reactive gas to make a reaction atmosphere of 3 Pa. Apply a DC bias voltage of -50V to
First, an arc discharge is generated by flowing a current of 100 A between the cathode electrode and the anode electrode made of the Cr—Al alloy, so that the target composition and target layer thickness shown in Table 3 are formed on the surface of the tool base. (Cr, Al) N layer is deposited as a lower layer,
Next, an arc discharge is generated by flowing a current of 100 A between the cathode electrode and the anode electrode made of the Cr—Si—W alloy, and the target composition and target layer thickness shown in Table 3 are formed on the surface of the lower layer. The surface coating inserts of the present invention (hereinafter referred to as the present invention coated inserts) 1 to 16 as the present invention coated tools were produced by vapor deposition formation of the (Cr, Si, W) N layer as an upper layer.

For comparison purposes, each of the tool bases A-1 to A-10 and B-1 to B-6 was ultrasonically cleaned in acetone and dried, and then the arc ion plating shown in FIG. attached to the apparatus, as a cathode electrode (vapor source), equipped with a Cr-Al alloy and bombardment cleaning metals Ti having a predetermined composition, first, evacuating the apparatus was maintained at a vacuum of 1 × 10 -2 ^Pa However, after the inside of the apparatus was heated to 500 ° C. with a heater, a DC bias voltage of −1000 V was applied to the tool base, and a current of 100 A was passed between the bombard cleaning metal Ti and the anode electrode to cause arc discharge. The surface of the tool base is Ti bombarded, and nitrogen gas is introduced as a reaction gas into the apparatus to obtain a predetermined atmosphere within a range of 2 to 4 Pa. The direct current bias voltage applied to the tool substrate is set to a predetermined voltage within a range of −30 to −70 V, and an arc discharge is generated by causing an electric current of 80 A to flow between the cathode electrode Cr—Al alloy and the anode electrode. Therefore, comparative coating inserts 1 to 16 as comparative coating tools were formed by vapor-depositing (Cr, Al) N layers having the target composition and target layer thickness shown in Table 4 on the surface of the tool base as hard coating layers. Were manufactured respectively.

Next, for the present invention coated inserts 1-10 and comparative coated inserts 1-10, in a state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / S10C round bar,
Cutting speed: 135 m / min. ,
Cutting depth: 3.5 mm,
Feed: 0.12 mm / rev. ,
Cutting time: 50 minutes,
Dry heavy cutting test of carbon steel under the following conditions (referred to as cutting condition A),
Moreover, about the said this invention covering insert 11-16 and the comparison covering inserts 11-16, in the state which this was screwed with the fixing jig to the front-end | tip part of a tool steel tool,
Work material: JIS / S15C round bar,
Cutting speed: 145 m / min. ,
Cutting depth: 3.5 mm,
Feed: 0.14 mm / rev. ,
Cutting time: 50 minutes,
A dry continuous heavy cutting test of carbon steel under the above conditions (referred to as cutting condition B) was performed, and the flank wear width of the cutting edge was measured.
The measurement results of the cutting test under the cutting conditions A and B are shown in Table 5.

Further, as the raw material powder, both cubic boron nitride (cBN) powder having an average particle size in the range of 0.5 to 4 .mu.m, titanium nitride (TiN) powder, Al powder, aluminum oxide _(Al 2 _{O 3)} powder These raw material powders were blended in the blending composition shown in Table 6, wet-mixed with a ball mill for 80 hours, dried, and then had a size of diameter: 50 mm × thickness: 1.5 mm at a pressure of 120 MPa. The green compact is press-molded, and then the green compact is sintered in a vacuum atmosphere at a pressure of 1 Pa at a predetermined temperature within the range of 900 to 1300 ° C. for 60 minutes and pre-baked for cutting edge pieces. A WC-based cemented carbide support piece having a size of Co: 8% by mass, WC: remaining composition, and diameter: 50 mm × thickness: 2 mm was prepared as a sintered body. Normal super-high in a superposed state After charging into the pressure sintering machine, sintering at ultra high pressure at a predetermined temperature within the range of pressure: 5 GPa, temperature: 1200-1400 ° C., holding time: 0.8 hours, after sintering The upper and lower surfaces are polished with a diamond grindstone and divided into 3 mm regular triangles with a wire electric discharge machine, and Co: 5% by mass, TaC: 5% by mass, WC: remaining composition and CIS standard SNGA120412 The brazing part (corner part) of the WC-based cemented carbide insert body having a shape (thickness: 4.76 mm × one side length: 12.7 mm square) is mass%, Cu: 26%, Ti : 5%, Ni: 2.5%, Ag: Brazing using a brazing material of an Ag alloy having the remaining composition, and after processing the outer periphery to a predetermined dimension, the width of the cutting edge is 0.13 mm, angle : 25 ° honing is applied. The tool substrate C-1 through C-10 having the insert shape of ISO standard SNGA120412 by performing finish polishing was produced, respectively.

Next, the tool bases C-1 to C-10 are ultrasonically cleaned in acetone and dried, and then mounted on the vapor deposition apparatus shown in FIG. 1, and a Cr—Al alloy having a predetermined composition is used as a cathode electrode. A Cr—Si—W alloy and a bombard cleaning metal Ti (not shown) are mounted, and the tool base is first heated to 500 ° C. while evacuating the apparatus and maintaining a vacuum of 1 × 10 ⁻² Pa or less. After that, a bias voltage of −200 V was applied to the tool base, Ar gas was introduced to form an atmosphere of 2 Pa, and the surface of the tool base was cleaned with Ar ion bombardment. Nitrogen gas is introduced as a reaction gas to make a reaction atmosphere of 3 Pa, a DC bias voltage of −20 V is applied to the tool base,
First, an arc discharge is generated by flowing a current of 100 A between the cathode electrode and the anode electrode made of the Cr—Al alloy, and the target composition and target layer thickness shown in Table 7 are formed on the surface of the tool base. (Cr, Al) N layer is deposited as a lower layer,
Next, a current of 100 A is passed between the cathode electrode and the anode electrode made of the Cr—Si—W alloy to generate an arc discharge, and the target composition and target layer thickness shown in Table 7 are formed on the surface of the lower layer. The surface-coated cBN-based inserts of the present invention (hereinafter referred to as the present invention-coated inserts) 21 to 30 as the present invention-coated tools were produced by vapor-depositing the (Cr, Si, W) N layer as the upper layer, respectively. .

For comparison purposes, each of the tool bases C-1 to C-10 is ultrasonically cleaned in acetone and dried, and then loaded into the normal arc ion plating apparatus shown in FIG. Then, as a cathode electrode, a Cr—Al alloy having a composition corresponding to Table 4 and a bombard cleaning metal Ti (not shown) are mounted, and the apparatus is first evacuated to a vacuum of 1 × 10 ⁻² Pa or less. While holding, the inside of the apparatus was heated to 500 ° C. with a heater, a −200 V DC bias voltage was applied to the tool base, and Ar gas was introduced into the apparatus to create an atmosphere of 2 Pa. Ti bombardment is performed, and then nitrogen gas is introduced into the apparatus as a reaction gas to obtain a predetermined atmosphere within a range of 2 to 4 Pa, and a bias voltage applied to the tool base is within a range of −30 to −70 V. And a current of 80 A is passed between the cathode electrode Cr—Al alloy and the anode electrode to generate an arc discharge, and the target composition shown in Table 8 is formed on the surface of the tool base. And a comparative surface coating cBN-based sintered insert (hereinafter referred to as a comparative coating insert) 21 to 30 as a comparative coating tool by vapor-depositing and forming a hard coating layer composed of a (Cr, Al) N layer having a target layer thickness. Manufactured.

Next, the present invention coated inserts 21 to 30 and comparative coated inserts 21 to 30 will be described below in a state where each of the various coated inserts is screwed to the tip of the tool steel tool with a fixing jig. A cutting test was performed under the cutting conditions C shown.
[Cutting conditions C]
Work material: JIS / SUJ2 (high frequency quenching material) round bar,
Cutting speed: 120 m / min. ,
Cutting depth: 0.4 mm,
Feed: 0.14 mm / rev. ,
Cutting time: 10 minutes,
Dry continuous heavy cutting test of hardened steel under the conditions of
The flank wear width (mm) of the cutting blade was measured. The measurement results are shown in Table 9.

  From the results shown in Tables 5 and 9, the coated inserts 1 to 16 and 21 to 30 of the present invention all have wear resistance, lubricity, and fracture resistance with excellent hard coating layers. On the other hand, even when used in heavy cutting where a large mechanical load is applied, the hard coating layer does not generate any defects and exhibits excellent wear resistance over a long period of time. It is clear that Comparative Coated Inserts 1-16, 21-30, which are composed of (Cr, Al) N layers, have defects in the hard coating layer, are inferior in wear resistance, and reach the service life in a short time. It is.

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 [50/50 by mass ratio] powder, and 1.8 μm Co Prepare powders, mix each of these raw material powders with the composition shown in Table 10, add wax, ball mill mix in acetone for 24 hours, dry under reduced pressure, and then press various pressures of a predetermined shape at a pressure of 100 MPa. The powder compact is press-molded, and these green compacts are heated to a predetermined temperature in the range of 1370 to 1470 ° C. at a heating rate of 7 ° C./min in a vacuum atmosphere of 6 Pa, and this temperature is maintained for 1 hour. After holding, sintering under the condition of furnace cooling, the diameter is 8 m, 13 mm, and 26 mm of three types of cemented carbide substrate-forming round bar sintered bodies were formed, and further, from the above three types of round bar sintered bodies, by grinding, in combinations shown in Table 10, Carbide substrate for end mill D- having a shape of a 4-blade square with a diameter x length of the cutting edge of 6 mm x 13 mm, 10 mm x 22 mm, and 20 mm x 45 mm, respectively, and a twist angle of 30 degrees. 1 to D-8 were produced.

  Then, these end mill carbide substrates D-1 to D-8 and the test pieces were ultrasonically cleaned in acetone and dried, and charged in the arc ion plating apparatus shown in FIG. Under the same conditions as the formation conditions of the (Cr, Al) N layer and the (Cr, Si, W) N layer in the inventive coated inserts 1 to 16 of Example 1 above, the target composition and target layer thickness shown in Table 11 are obtained. By forming the (Cr, Al) N layer and the (Cr, Si, W) N layer as the lower layer and the upper layer of the hard coating layer, the end mill made of the surface coated cemented carbide of the present invention as the coated tool of the present invention ( (Hereinafter referred to as the present invention coated end mill) 1 to 8 were produced.

  For comparison purposes, the (Cr, Al) N layer is vapor-deposited as a hard coating layer under the same conditions as the (Cr, Al) N layer formation conditions in the comparative coating inserts 1 to 16 of Example 1 above. Then, comparative surface coated cemented carbide end mills (hereinafter referred to as comparative coated end mills) 1 to 8 as comparative coated tools as shown in Table 11 were produced.

Next, of the present invention coated end mills 1-8 and comparative coated end mills 1-8,
About this invention coated end mills 1-3 and comparative coated end mills 1-3,
Work material: Plane dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / S45C plate,
Cutting speed: 150 m / min. ,
Groove depth (cut): 3.5 mm,
Table feed: 500 mm / min. ,
Carbon steel dry grooving test,
About this invention coated end mills 4-6 and comparative coated end mills 4-6,
Work material: Plane size: 100 mm × 250 mm, thickness: 50 mm JIS / SUS316 plate material,
Cutting speed: 50 m / min. ,
Groove depth (cut): 5.0 mm,
Table feed: 450 mm / min. ,
Stainless steel dry grooving test, under the conditions of
For the coated end mills 7 and 8 and the comparative coated end mills 7 and 8,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Cutting speed: 48 m / min. ,
Groove depth (cut): 10 mm,
Table feed: 320 mm / min. ,
Stainless steel dry grooving test, under the conditions of
In each 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 shown in Table 11, respectively.

  The diameters manufactured in Example 3 above were 8 mm (carbide substrates D-1 to D-3 for end mills), 13 mm (carbide substrates D-4 to D-6 for end mills), and 26 mm (carbide substrates for end mills). D-7 and D-8) were used, and from these three types of round bar sintered bodies, the diameter x length of the groove forming portion was 4 mm x 13 mm (by grinding). Drilling carbide substrates E-1 to E-3), 8 mm × 22 mm (drilling carbide substrates E-4 to E-6), and 16 mm × 45 mm (drilling carbide substrates E-7 and E-8) And the carbide substrates E-1 to E-8 for drills each having a two-blade shape with a twist angle of 30 degrees were manufactured.

  Next, honing is performed on the cutting blades of these carbide substrates E-1 to E-8 for drilling, ultrasonic cleaning is performed in acetone together with the above test pieces, and the state is also shown in FIG. In the arc ion plating apparatus, the same conditions as those for forming the (Cr, Al) N layer and the (Cr, Si, W) N layer in the coated inserts 1 to 16 of the present invention of Example 1 were used. As the coated tool of the present invention, the (Cr, Al) N layer and (Cr, Si, W) N layer having the target composition and the target layer thickness shown in FIG. 12 are deposited as the lower layer and the upper layer of the hard coating layer. The surface-coated cemented carbide drills (hereinafter referred to as the present invention-coated drills) 1 to 8 of the present invention were produced.

  For comparison purposes, the (Cr, Al) N layer is vapor-deposited as a hard coating layer under the same conditions as the (Cr, Al) N layer formation conditions in the comparative coating inserts 1 to 16 of Example 1 above. Thus, comparative surface-coated cemented carbide drills (hereinafter referred to as comparative coated drills) 1 to 8 as comparative coated tools as shown in Table 12 were produced.

Next, of the present invention coated drills 1-8 and comparative coated drills 1-8, for the present invention coated drills 1-3 and comparative coated drills 1-3,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SS400 plate material,
Cutting speed: 70 m / min. ,
Feed: 0.15 mm / rev. ,
Hole depth: 12 mm
Wet drilling test of mild steel under the conditions of
About this invention coated drill 4-6 and comparative coated drill 4-6,
Work material: Plane size: 100 mm × 250 mm, thickness: 50 mm JIS / SUS316 plate material,
Cutting speed: 38 m / min. ,
Feed: 0.08 mm / rev. ,
Hole depth: 16 mm
Stainless steel dry drilling cutting test,
About this invention covering drills 7 and 8 and comparative covering drills 7 and 8,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SCMnH2 plate material,
Cutting speed: 40 m / min. ,
Feed: 0.12 mm / rev,
Hole depth: 20 mm
Wet drilling test of high manganese steel under the conditions of
In each drilling cutting 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 shown in Table 12.

(Cr, Al) N layer of this invention coated insert 1-16, 21-30, this invention coated end mill 1-8, and this invention coated drill 1-8 as this invention coated tool obtained as a result, (Cr , Si, W) N layer, and the composition of the (Cr, Al) N layer of comparative coated inserts 1-16, 21-30, comparative coated end mills 1-8, and comparative coated drills 1-8 as comparative coated tools. When measured using an Auger spectroscopic analyzer, each showed substantially the same composition as the target composition.
The thicknesses of the (Cr, Al) N layer, (Cr, Si, W) N layer of the present invention coated tool and the (Cr, Al) N layer of the comparative coated tool were measured using a scanning electron microscope. When the cross-section was measured, all showed an average layer thickness (average value of 5-point measurement) substantially the same as the target value.

  From the results shown in Tables 5, 9, 11, and 12, the coated tool of the present invention has excellent wear resistance with the (Cr, Al) N layer constituting the lower layer of the hard coating layer, The (Cr, Si, W) N layer that constitutes the upper layer of the hard coating layer has excellent lubricity, chip flowability, and chip dischargeability. In contrast, the comparative coated tools show improved fracture resistance and wear resistance in heavy cutting operations that require a large mechanical load such as high cutting and high feed. It is clear that the service life is reached in a relatively short time.

  As described above, the coated tool of the present invention naturally exhibits excellent tool characteristics in continuous cutting and intermittent cutting of various steels, and also has a large mechanical load on the cutting blade such as high cutting and high feeding. Even under such heavy cutting conditions, the lower layer made of the (Cr, Al) N layer has excellent wear resistance, and the upper layer made of the (Cr, Si, W) N layer has excellent lubricity, Because it has chip flowability and chip discharge performance, it exhibits excellent cutting performance over a long period of time, fully satisfying the demands of FA of cutting equipment, labor saving and energy saving of cutting processing, and cost reduction It can respond.

Claims (1)

On the surface of the cutting tool base made of cemented carbide, cermet or cubic boron nitride based ultra high pressure sintered body,
(A) As a lower layer, it has an average layer thickness of 0.5 to 5 μm,
Composition formula: (Cr _1-X Al _X ) N
X is a composite nitride layer of Cr and Al that satisfies 0.4 to 0.7 (where X represents an atomic ratio),
(B) As an upper layer, it has an average layer thickness of 0.5 to 5 μm,
Composition _{formula: (Cr 1-Y-Z} Si Y W Z) N
Y is 0.05 to 0.3, Z is 0.2 to 0.5 (provided that Y and Z indicate atomic ratios), a composite nitride layer of Cr, Si and W,
A surface-coated cutting tool in which a hard coating layer comprising the above (a) and (b) is formed by vapor deposition.

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