The present invention relates to a cutting tool hard film disposed as coating on a surface of a cutting tool and a hard film coated cutting tool provided with the hard film and particularly to an improvement for increasing both abrasion resistance and welding resistance.
Cutting tools such as drills and taps are provided and coated with a hard film to increase abrasion resistance. TiN-based, TiCN-based, TiAlN-based and AlCrN-based coatings are widely used for this cutting tool hard film and improvements are achieved for further increasing performance thereof. For example, this corresponds to an abrasion resistance member described in Patent Document 1.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-138209
However, a cutting tool with a hard film formed by the conventional technique as described above may have insufficient welding resistance at the time of cutting depending on a type of work material and a cutting condition. Therefore, a tool life may be shortened due to welding of work material etc., and room for improvement exists. Therefore, it is requested to develop a cutting tool hard film and a hard film coated cutting tool excellent in both abrasion resistance and welding resistance.
The present invention was conceived in view of the situations and it is therefore an object of the present invention to provide a cutting tool hard film and a hard film coated cutting tool excellent in both abrasion resistance and welding resistance.
To achieve the object, the first aspect of the invention provides a cutting tool hard film disposed as coating on a surface of a cutting tool, comprising: a hard phase that is a nitride phase, an oxide phase, a carbide phase, a carbonitride phase, or a boride phase containing at least one element out of group IVa elements, group Va elements, group VIa elements, Al, and Si; and a binding phase that is a phase containing at least one element out of Au, Ag, and Cu, wherein the cutting tool hard film has composite structure with the hard phase and the binding phase three-dimensionally arranged.
As described above, according to the first aspect of the invention, the cutting tool hard film comprises: a hard phase that is a nitride phase, an oxide phase, a carbide phase, a carbonitride phase, or a boride phase containing at least one element out of group IVa elements, group Va elements, group VIa elements, Al, and Si; and a binding phase that is a phase containing at least one element out of Au, Ag, and Cu, the cutting tool hard film has composite structure with the hard phase and the binding phase three-dimensionally arranged, and, therefore, since the structure is achieved with the hard phase bound by Au, Ag, and Cu, friction coefficient and cutting resistance can be reduced, and a high hardness film excellent in lubricity and welding resistance is acquired. Thus, the cutting tool hard film excellent in both abrasion resistance and welding resistance can be provided.
The second aspect of the invention provides the cutting tool hard film recited in the first aspect of the invention, wherein an average particle diameter of particles making up the hard phase is within a range of 1 nm to 100 nm. Consequently, since so-called nanocomposite structure is achieved with the hard phase bound by Au, Ag, and Cu at the nano-level, friction coefficient and cutting resistance can further be reduced, and the high hardness film excellent in lubricity and welding resistance is acquired.
The third aspect of the invention which depends from the first aspect of the invention or the second aspect of the invention provides a hard film coated cutting tool having the cutting tool hard film recited in the first aspect of the invention or the second aspect of the invention disposed as coating on a surface. Consequently, since the structure is achieved with the hard phase bound by Au, Ag, and Cu, friction coefficient and cutting resistance can be reduced, and a high hardness film excellent in lubricity and welding resistance is acquired. Thus, the hard film coated cutting tool excellent in both abrasion resistance and welding resistance can be provided.
A cutting tool hard film of the present invention is preferably applied to surface coating of various cutting tools including rotary cutting tools such as end mills, drills, face mills, forming mills, reamers, and taps, as well as non-rotary cutting tools such as tool bits. Although cemented carbide and high speed tool steel are preferably used as tool base material, i.e., material of a member provided with the hard film, other materials are also available and, for example, the cutting tool hard film of the present invention is widely applied to cutting tools made of various materials such as cermet, ceramics, polycrystalline diamond, single-crystal diamond, polycrystalline CBN, and single-crystal CBN.
The cutting tool hard film of the present invention is disposed as coating on a portion or the whole of the surface of a cutting tool and is preferably disposed on a cutting portion involved with cutting in the cutting tool. More preferably, the cutting tool hard film is disposed to coat at least a cutting edge or a rake surface in the cutting portion.
The hard phase is made of nitride, oxide, carbide, carbonitride, or boride containing at least one element out of group IVa elements, group Va elements, group VIa elements, Al, and Si, or mutual solid solution thereof Specifically, the hard phase is a phase comprising TiN, TiAlN, TiAlCrVSiB, ZrVO, HfCrCN, NbN, CrN, MoSiC, AlN, SiN, etc.
Although the cutting tool hard film of the present invention is preferably disposed by, for example, a PVD method such as an arc ion plating method, an ion beam deposition method, a sputtering method, a PLD (Pulse Laser Deposition) method, and an IBAD (Ion Beam Assisted Deposition) method, other film formation methods such as a plating method, a liquid quenching method, and a gas aggregation method are also employable.
A preferred embodiment of the present invention will now be described in detail with reference to the drawings. In the drawings used in the following description, portions are not necessarily precisely depicted in terms of dimension ratio, etc.
The binding phase 26 is a phase comprising Au, Ag, or Cu containing unavoidable impurities, or mutual solid solution thereof. The hard phase 24 is made of nitride, oxide, carbide, carbonitride, or boride containing at least one element out of group IVa elements, group Va elements, group VIa elements, Al, and Si, or mutual solid solution thereof, and contains unavoidable impurities. Therefore, specifically, the hard phase 24 is a phase (dispersed phase) comprising TiN, TiAlN, TiAlCrVSiB, ZrVO, HfCrCN, NbN, CrN, MoSiC, AlN, SiN, etc. Preferably, an average particle diameter of the particles making up the hard phase 24 is within a range of 1 nm to 100 nm. For example, the average particle diameter of the particles making up the hard phase 24 is calculated for a plurality of particles (particulate elements) making up the hard phase 24 randomly extracted from a microscope photograph as depicted in
Subsequently, for example, the hard phase 24 in the hard film 22 is formed in a sputtering process. For example, a constant negative bias voltage (e.g., about −50 to −60 V) is applied by a power source 40 to a target 38 such as Si making up the hard phase 24 while a constant negative bias voltage (e.g., about −100 V) is applied by the bias power source 34 to the tool base material 20 so as to cause the argon ions Ar+ to collide with the target 38, thereby beating out constituent material such as Si. Reactant gas such as nitrogen gas (N2) and hydrocarbon gas (CH4, C2H2) is introduced into the chamber 32 at predetermined flow rates in addition to argon gas, and nitrogen atoms N and carbon atoms C combine with Si etc. beaten out from the target 38 to form SiN etc., which are attached as the hard phase 24 in the hard film 22 to the surface of the tool base material 20. This treatment is executed alternately with treatment of the sputtering process using Ag etc. making up the binding phase 26 as the target 38 to form the hard film 22 having the composition as depicted in
Other preferably used methods of forming the hard film 22 on the surface of the tool base material 20 include, for example, a well-known plating method (plating technique), a liquid quenching method in which molten alloy acquired by melting the metal making up the hard film 22 is quenched faster than a rate causing crystal nucleation to acquire amorphous alloy, and a gas aggregation method in which nanoparticles acquired by evaporating and aggregating the metal making up the hard film 22 in He gas are deposited on a substrate cooled by liquid nitrogen to solidify and form nano-fine powder scraped off from the substrate.
A drilling test conducted by the present inventors for verifying an effect of the present invention will then be described.
[Machining Conditions]
Tool shape: φ3 cemented carbide drill
Work material: Inconel (registered trademark) 718
Cutting machine: vertical type M/C
Cutting speed: 10 m/min
Feed speed: 0.1 mm/rev
Machining depth: 33 mm (blind)
Step amount: non-step
Cutting oil: oil-based
As depicted in
Particularly, the inventive product 2 includes the hard phase 24 comprising SiN and the binding phase 26 comprising Ag with the average particle diameter of 22.7 nm for the hard phase 24 and the film thickness of 4.1 μm, and results in the machined hole number of 41; the inventive product 9 includes the hard phase 24 comprising MoSiC and the binding phase 26 comprising Ag and Au with the average particle diameter of 94.6 nm for the hard phase 24 and the film thickness of 5.1 μm, and results in the machined hole number of 38; the inventive product 1 includes the hard phase 24 comprising CrN and the binding phase 26 comprising Au with the average particle diameter of 1.0 nm for the hard phase 24 and the film thickness of 2.6 μm, and results in the machined hole number of 36; the inventive product 4 includes the hard phase 24 comprising TiN and the binding phase 26 comprising Au and Cu with the average particle diameter of 100.0 nm for the hard phase 24 and the film thickness of 5.8 μm, and results in the machined hole number of 33; the inventive product 7 includes the hard phase 24 comprising TiAlCrVSiB and the binding phase 26 comprising Ag, Cu, and Au with the average particle diameter of 66.9 nm for the hard phase 24 and the film thickness of 3.5 μm, and results in the machined hole number of 31; and, therefore, it can be seen that these inventive products result in the machined hole numbers equal to or greater than 30 when the flank wear width is 0.2 mm and exhibit particularly favorable cutting performance.
Although including the hard phase 24 that is a nitride phase, an oxide phase, a carbide phase, a carbonitride phase, or a boride phase containing at least one element out of group IVa elements, group Va elements, group VIa elements, Al, and Si, and the binding phase 26 that is a phase containing at least one element out of Au, Ag, and Cu, all the test products 1 to 7 have an average particle diameter of the particles making up the hard phase 24 deviating from the range of 1 nm to 100 nm and do not satisfy the requirement of claim 2 of the present invention. In particular, the test products 1, 4, 6, and 7 have a smaller average particle diameter of the particles making up the hard phase 24 less than 1 nm and the test products 2, 3, and 5 have an average particle diameter of the particles making up the hard phase 24 larger than 100 nm. If a hard film has an average particle diameter of the particles making up the hard phase 24 deviating from the range of 1 nm to 100 nm as described above, the hard film cannot have preferred nanocomposite structure with the hard phase 24 dispersively (diffusively) disposed in the binding phase 26 or, in other words, does not have composite structure with the hard phase 24 and the binding phase 26 three-dimensionally arranged. Therefore, none of the test products 1 to 7 satisfies the requirement of claim 1 of the present invention. None of the test products 8 and 9 has the binding phase 26 that is a phase containing at least one element out of Au, Ag, and Cu, and satisfies the requirement of claim 1 of the present invention. As apparent from the test results depicted in
It is considered that this is because a hard film not satisfying the requirement of claim 1 or 2 of the present invention has insufficient welding resistance and reaches the end of life earlier due to welding, peeling, etc.
As described above, this embodiment includes the hard phase 24 that is a nitride phase, an oxide phase, a carbide phase, a carbonitride phase, or a boride phase containing at least one element out of group IVa elements, group Va elements, group VIa elements, Al, and Si, and the binding phase 26 that is a phase containing at least one element out of Au, Ag, and Cu, and has composite structure with the hard phase 24 and the binding phase 26 three-dimensionally arranged and, therefore, since the structure is achieved with the hard phase 24 bound by Au, Ag, and Cu, friction coefficient and cutting resistance can be reduced, and a high hardness film excellent in lubricity and welding resistance is acquired. Thus, the cutting tool hard film 22 excellent in both abrasion resistance and welding resistance can be provided.
An average particle diameter of the particles making up the hard phase 24 is within the range of 1 nm to 100 nm and, therefore, since so-called nanocomposite structure is achieved with the hard phase 24 bound by Au, Ag, and Cu at the nano-level, friction coefficient and cutting resistance can further be reduced, and the high hardness hard film 22 excellent in lubricity and welding resistance is acquired.
This embodiment provides the drill 10 as a hard film coated cutting tool having the hard film 22 disposed as coating on a surface and, therefore, since the structure is achieved with the hard phase 24 bound by Au, Ag, and Cu, friction coefficient and cutting resistance can be reduced, and a high hardness film excellent in lubricity and welding resistance is acquired. Thus, the drill 10 excellent in both abrasion resistance and welding resistance can be provided.
Although the preferred embodiment of the present invention has been described in detail with reference to the drawings, the present invention is not limited thereto and is implemented with various modifications applied within a range not departing from the spirit thereof.
10: drill (hard film coated cutting tool) 12: cutting edge 14: shank 16: body 18: flutes 20: tool base material 22: hard film (cutting tool hard film) 24: hard phase 26: binding phase 30: sputtering apparatus 32: chamber 34: bias power source 36: controller 38: target 40: power source
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2012/059012 | 4/2/2012 | WO | 00 | 10/1/2014 |