JP2001219303A - Surface-coated cemented carbide cutting tool with excellent wear resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-coated cemented carbide cutting tool with excellent wear resistance. SOLUTION: This surface-coated cemented carbide cutting tool is formed by physically deposition a tough and hard coating layer of 0.5 to 15 μm in average layer thickness, comprising one type of single layer or multiple layers of two types of a compound nitride and compound carbonitride of Ti and Al, on the surface of a tool base body formed of a tungsten carbide based cemented carbide or a titanium carbonitride based cermet. On that surface, as a wear resistant and hard coating layer, an aluminum oxide based layer of 0.5 to 15 μm in average layer thickness, formed by substitutive solution of a part of Al with one or two or more types of Ti, Zr, and Hf with a ratio of 0.01 to 10 atomic % in content relative to Al, with the crystal structure of an aluminum oxide held undisturbed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool made of a surface-coated cemented carbide which has excellent wear resistance and therefore exhibits excellent cutting performance over a long period of time, for example, in continuous cutting and interrupted cutting of steel. Hereinafter, referred to as a coated carbide cutting tool).

[0002]

2. Description of the Related Art Conventionally, for example, an arc ion plating apparatus, which is a kind of physical vapor deposition apparatus schematically shown in FIG.
In the state heated to a temperature of ° C., an arc discharge is generated between the anode electrode and a cathode electrode (evaporation source) on which a Ti-Al alloy having a predetermined composition is set, and at the same time, nitrogen gas as a reaction gas is introduced into the apparatus. Alternatively, nitrogen gas and methane gas are introduced, while tungsten carbide (hereinafter referred to as WC)
A tool base made of a base cemented carbide or a titanium cermet (hereinafter, referred to as TiCN) base cermet (hereinafter, collectively referred to as a cemented carbide tool base) is applied under a condition that a bias voltage of -120 V is applied, for example. As described in, for example, JP-A-62-56565, a composite nitride of Ti and Al [hereinafter, (Ti, A
1) N]] layer and composite carbonitride [hereinafter, (Ti,
Al) CN] coated superhard produced by physical vapor deposition of a tough hard coating layer consisting of one single layer or two or more layers of the above layers at an average layer thickness of 0.5 to 15 μm. Cutting tools are known.

[0003]

On the other hand, in recent years, FA and speed of cutting have been remarkable, and there is also a demand for labor saving and energy saving of cutting. As a result, the life of cutting tools has been extended. However, in the case of the above-mentioned conventional coated carbide cutting tool, the tough hard coating layer comprising the (Ti, Al) N layer and the (Ti, Al) CN layer has excellent strength. Although it has good toughness and good chipping resistance (the property that micro-chips are not likely to occur on the tool cutting edge), its wear life is not enough, so the service life can be reached in a relatively short time at present. is there.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoint, in order to improve the wear resistance of the above-mentioned conventional coated carbide cutting tool, the inventors focused on the hard coating layer constituting the cutting tool, and as a result of conducting research, (a) formed by the physical vapor deposition method The Al ₂ O ₃ layer as an ordinary hard coating layer is excellent in heat resistance and has high hardness, and is therefore desirable for improving wear resistance.
_{The 2} O ₃ layer constitutes the conventional coated carbide cutting tool described above (T
Since the adhesion to the (i, Al) N layer and the (Ti, Al) CN layer is poor, the coated carbide obtained by forming the Al ₂ O ₃ layer on the surface of the conventional coated carbide cutting tool is used. In cutting tools, especially when performing intermittent cutting with a high load on the tool cutting edge under heavy cutting conditions such as high cutting and high feed, the Al ₂ O ₃ layer is liable to peel off and can be put to practical use. Things impossible.

(B) Constituting the above-mentioned conventional coated carbide cutting tool
(Ti, Al) N layer and (Ti, Al) CN layer
On the surface, the above Al_TwoO_ThreeForming layers by physical vapor deposition
In this case, Ti, Z having an ionic radius significantly larger than that of Al
r, and Hf, that is, the ion radius is 0.57 angstroms.
The ionic radius of each of the stroms of Al is 0.
76 Å Ti, 0.87 Å
Zr, and Hf of 0.84 Å
One or more of Al_TwoO_ThreeCrystal structure of
Is the ratio of part of the Al atoms in
0.01 to 10 atomic%, desirably 0.02 to 5 atomic%
When the solid solution is contained in a form substituted by the ratio of
l_TwoO_ThreeAl while retaining the crystal structure of_TwoO_Threemain
The body layer has significant intra-lattice strain due to large ion radius difference.
By increasing the normal physical vapor deposition Al _TwoO_ThreeLayer is also layer thickness
Affected, but compressive residual stress of 0.2-0.8 GPa
Have a compressive residual stress of 1.2 to 3 GPa
As described above, A having extremely high compressive residual stress
l_TwoO_ThreeThe main layer is composed of the (Ti, Al) N layer and the (T
i, Al) adheres very strongly to the CN layer, and_TwoO
_ThreeBecause the characteristics of
Surface of (Ti, Al) N layer and (Ti, Al) CN layer
And the Al_TwoO_ThreeCoating by physical vapor deposition of main layer
Carbide cutting tools are used, for example, for interrupted cutting of steel, especially tool cutting edges.
Cutting conditions such as high depth of cut and high feed with high load
Al_TwoO_ThreeNo peeling of main layer, long
To provide excellent wear resistance over time.
When. The research results shown in (a) and (b) above were obtained.
It is.

The present invention has been made based on the results of the above-mentioned research, and has the following features: (T)
one of the (i, Al) N layer and the (Ti, Al) CN layer
In a coated carbide cutting tool obtained by physical vapor deposition of a tough tough hard coating layer consisting of one kind of single layer or two kinds of multiple layers with an average layer thickness of 0.5 to 15 μm, the surface of the tough tough hard coating layer is
Further, as a wear-resistant hard coating layer, 0.01 to 10 atomic% of Ti, Zr, and 0.01% by weight of a part of Al with respect to the total amount of Al while maintaining the crystal structure of Al ₂ O _3. one or abrasion resistance formed by physical vapor deposition with an average layer thickness of 0.5~15μm the Al ₂ O ₃ based layer formed by replacing solid solution of two or more excellent coated cemented carbide cutting tools of the Hf It is characterized by the following.

The reason why the average thickness of the tough hard coating layer is set to 0.5 to 15 μm in the coated carbide cutting tool of the present invention is that if the thickness is less than 0.5 μm, the hard coating layer has a desired thickness. The toughness cannot be ensured, and as a result chipping and chipping (small chipping) easily occur on the cutting edge. On the other hand, if the thickness of the layer exceeds 15 μm, thermoplastic deformation is caused by high heat generated during cutting and cutting. This is based on the reason that uneven wear occurs on the blade, and the wear progresses rapidly due to this, and the average layer thickness of the wear-resistant hard coating layer (Al ₂ O ₃ main layer) When the thickness is 0.5 to 15 μm, if the layer thickness is less than 0.5 μm, the desired wear resistance cannot be secured, while if the layer thickness exceeds 15 μm, chipping or chipping occurs in the cutting edge. Because it ’s easier.

[0008] Further, A in the wear-resistant hard coating layer
The substitution content of Ti, Zr, and Hf is 0.1%.
The content ratio of 0.01 to 10 atomic% is 0.01% by weight.
If the content is less than atomic%, it is impossible to form a compressive residual stress capable of securing sufficient adhesion between the wear-resistant hard coating layer and the tough hard coating layer, while the content ratio is 15 atomic%. %, The compressive residual stress becomes too large and self-destruction easily occurs. Further, a TiN layer having an average thickness of 0.1 to 2 μm may be formed on the abrasion-resistant hard coating layer, if necessary, since the TiN layer has a golden color tone. In this case, the layer thickness is 0.1 μm, because the color tone makes it easy to distinguish the cutting tool before and after use.
If it is less than m, the application of the color tone is insufficient, while the application of the color tone is sufficient with an average layer thickness of up to 2 μm.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated carbide cutting tool of the present invention will be specifically described with reference to examples. WC powder having an average particle diameter of 1 to 3 μm,
TiC powder, ZrC powder, VC powder, TaC powder, Nb
A C powder, a Cr ₃ C ₂ powder, a TiN powder, a TaN powder, and a Co powder were prepared, and these raw material powders were blended in the composition shown in Table 1, wet-mixed in a ball mill for 72 hours, and dried. It is press-molded into a green compact at a pressure of 1.5 × 10 ⁸ Pa, and the green compact is heated in a vacuum at a temperature of 1400 ° C.
For 1 hour, and after sintering, add R:
Honing process of 0.05 and ISO standard / SPG
Carbide tool bases A1 to A8 made of a WC-based cemented carbide having a chip shape of A120408 were formed. In addition, as raw material powders, T powder having an average particle size of 0.5 to 2 μm is used.
iCN (TiC / TiN = 50/50 by mass ratio) powder,
Mo ₂ C powder, ZrC powder, NbC powder, TaC powder,
WC powder, Co powder, and Ni powder were prepared, and these raw material powders were blended in the composition shown in Table 2, wet-mixed in a ball mill for 24 hours, and dried, and then 9.8 × 10
^A green compact is press-molded at a pressure of ⁷ Pa, and the green compact is pressed in a nitrogen atmosphere of 1.3 × 10 ³ Pa at a temperature of 1540 ° C.
For 1 hour, and after sintering, add R:
Applying honing process of 0.03, ISO standard, CNM
Carbide tool bases B1 to B6 made of TiCN-based cermet having a chip shape of G120406 were formed.

[0010] Then, the carbide tool bases A1 to A8 and B1 to B6 are ultrasonically cleaned in acetone and dried, and each is charged into an arc ion plating apparatus shown in FIG. Ti-Al alloys with various component compositions are installed as electrodes (evaporation sources),
While the inside of the apparatus was evacuated and kept at a vacuum of 1.3 × 10 ⁻³ Pa, the inside of the apparatus was heated to 500 ° C. with a heater.
A gas was introduced into the apparatus to make an Ar atmosphere of 2.5 Pa,
In this state, a pulse bias voltage of -800 V is applied to the cemented carbide substrate to wash the surface of the cemented carbide substrate with Ar gas bombardment. Then, nitrogen gas or a mixture of nitrogen gas and methane gas is introduced into the apparatus as a reaction gas. And a pulsed bias voltage applied to the cemented carbide tool base was reduced to -200 V to generate an arc discharge between the cathode electrode and the anode electrode. Conventionally coated super hard tool substrates 1 to 22 were produced by forming a tough hard coating layer having the target composition and target layer thickness shown in Tables 3 and 4 on the respective surfaces of A8 and B1 to B6.

Next, the conventional coated carbide cutting tools 1 to 1
On the surface of each of the electrodes 22, Al— () containing a predetermined amount of one or more of Ti, Zr, and Hf as a cathode electrode (evaporation source) by the arc ion plating apparatus of FIG. While mounting the Ti, Zr, Hf) alloy and evacuating the inside of the apparatus to maintain a vacuum of 1.3 × 10 ⁻³ Pa, the inside of the apparatus is heated to a predetermined temperature within a range of 620 to 720 ° C. by a heater. In this state, the pulse bias voltage applied to the carbide substrate was set to -700 V, and then an arc discharge was generated between the cathode electrode and the anode electrode while introducing oxygen gas as a reaction gas into the apparatus. Al ₂ of target composition and target layer thickness of 5 and 6
The coated hard cutting tools 1 to 22 of the present invention were produced by forming a wear-resistant hard coating layer composed of an O ₃ main layer. Ti in the Al ₂ O ₃ main layer constituting the wear-resistant hard coating layer of the coated carbide cutting tools 1-2 of the present invention,
When the contents of Zr and Hf were quantitatively analyzed using an energy dispersive X-ray measuring apparatus, the contents were substantially the same as the target contents in Tables 5 and 6, and the Al ₂ O ₃
When the compressive residual stress of the main layer was measured using the X-ray stress measurement method, the results shown in Tables 5 and 6 were shown. Furthermore, the composition and layer thickness of each coating layer were also measured by Auger spectroscopy and an optical microscope, and the compositions and average layer thicknesses substantially the same as the target compositions and target layer thicknesses in Tables 3 to 6 (measured at five arbitrary locations) Average value).

Next, among the various coated carbide cutting tools obtained as a result, the coated carbide cutting tools 1 to 16 of the present invention and the conventional coated carbide cutting tools 1 to 16 are described below. Work material: JIS S50C Round bar with four longitudinal grooves at equal intervals in the longitudinal direction, Cutting speed: 280 m / min., Feed: 0.3 mm / rev., Depth of cut: 2.8 mm, Cutting time: 10 minutes, Dry type of carbon steel Intermittent high-cut cutting test and work material: JIS SNCM440 lengthwise equally spaced round bar with four longitudinal grooves, cutting speed: 280 m / min., Feed: 0.4 mm / rev., Depth of cut: 1. 5mm, cutting time: 10 minutes, dry intermittent high feed cutting test of alloy steel under the following conditions:
For the coated carbide cutting tools 17 to 22 of the present invention and the conventionally coated carbide cutting tools 17 to 22, a work material: JIS
Stainless steel with SUS304 with 4 longitudinal grooves at regular intervals in the longitudinal direction, cutting speed: 350 m / min., Feed: 0.3 mm / rev., Cutting depth: 2.8 mm, cutting time: 10 minutes. Intermittent high depth of cut feed cutting test, and work material: JIS SCM440, a longitudinally spaced round bar with four longitudinal grooves, cutting speed: 400 m / min., Feed: 0.45 mm / rev., Depth of cut : 1.5mm, cutting time: 10 minutes, dry intermittent high feed cutting test of alloy steel under the following conditions:
In each cutting test, the flank wear width of the cutting edge was measured.
Table 7 shows the measurement results.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

[0016]

[Table 4]

[0017]

[Table 5]

[0018]

[Table 6]

[0019]

[Table 7]

[0020]

According to the results shown in Tables 3 to 7, in the coated carbide cutting tools 1 to 22 of the present invention, the Al ₂ O ₃ main layer constituting the wear-resistant hard coating layer is smaller than that of Al. Substituting and containing one or more of Ti, Zr, and Hf having a remarkably large ionic radius, thereby maintaining a remarkably high compressive residual stress and constituting a tough hard coating layer (Ti, Al) Since it becomes firmly adhered to the N layer and the (Ti, Al) CN layer, even if intermittent cutting of steel is performed under high cutting and high feed heavy cutting conditions, the Al ₂
While the O ₃ main layer exhibits excellent wear resistance without peeling, the conventional coated carbide cutting tools 1 to 22 are all caused by insufficient wear resistance of the tough hard coating layer. It is clear that the wear progresses rapidly under the severe conditions as described above. As described above, the coated cemented carbide cutting tool of the present invention is capable of producing various types of steel under ordinary conditions by the excellent wear resistance and adhesion of the Al ₂ O ₃ main layer constituting the wear resistant hard coating layer. continuous cutting and intermittent cutting, of course, extremely a severe cutting conditions even if the intermittent cutting in heavy cutting conditions of the high-cut and high-feed the Al ₂ O
_{(3) It} shows excellent wear resistance without peeling of the main layer and chipping or chipping of the cutting edge, and exhibits excellent cutting performance over a long period of time. It can respond satisfactorily to labor saving.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of an arc ion plating apparatus.

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[Procedure amendment]

[Submission date] April 10, 2000 (2004.1.
0)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008] Further, A in the wear-resistant hard coating layer
The substitution content of Ti, Zr, and Hf is 0.1%.
The content ratio of 0.01 to 10 atomic% is 0.01% by weight.
In less than atomic% can not form a compressive residual stress capable of ensuring sufficient adhesion between the toughness hard coating layer on the wear-resistant hard coating layer, while its content is 10 atom %, The compressive residual stress becomes too large and self-destruction easily occurs. Further, a TiN layer having an average thickness of 0.1 to 2 μm may be formed on the abrasion-resistant hard coating layer, if necessary, since the TiN layer has a golden color tone. In this case, the layer thickness is 0.1 μm, because the color tone makes it easy to distinguish the cutting tool before and after use.
If it is less than m, the application of the color tone is insufficient, while the application of the color tone is sufficient with an average layer thickness of up to 2 μm.

Claims (1)

[Claims] 1. A tool base comprising a tungsten carbide based cemented carbide or a titanium carbonitride based cermet,
Physically vapor-depositing a tough hard coating layer composed of one single layer or two or more multiple layers of a composite nitride layer of Ti and Al and a composite carbonitride layer with an average layer thickness of 0.5 to 15 μm. In a cutting tool made of a surface-coated cemented carbide, the surface of the tough hard coating layer is further treated as A wear-resistant hard coating layer while retaining the crystal structure of aluminum oxide.
1 to 0.01 to 10 in a proportion of the total amount with Al
One or more of atomic% of Ti, Zr and Hf
A hard-wearing surface-coated cemented carbide cutting tool having excellent wear resistance, characterized in that an aluminum oxide-based layer formed by substitutional solid solution of at least one kind is physically deposited with an average layer thickness of 0.5 to 15 μm.