JP2001322003A - Surface coated tungsten carbide group cemented carbide cutting tool having physically depositing hard coating layer with excellent chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface coated WC group cemented carbide cutting tool having a physically depositing hard coating layer with excellent chipping resistance. SOLUTION: In the surface coated WC group cemented carbide cutting tool made by physically depositing the hard coating layer constituted of a lower layer having average thickness of 0.1 to 10 μm and an upper layer having average thickness of 0.5 to 10 μm on the surface of a WC group cemented carbide substrate, the physically depositing lower layer is made of a Ti compound layer made of one kind or not less than two kinds of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer and a TiCNO layer and the physically depositing upper layer is made of an Al2O3 main body layer made by substituting a part of Al in a crystal structure of Al2O3 by one kind or not less than two kinds of Ta, V, Nb, W, Mo and Cr of 5 to 20 atomic percent of the total amount with Al to bring a solid solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hard coating layer formed by physical vapor deposition, which has a high compressive residual stress, so that the cutting edge of various steels can be cut even under heavy cutting conditions. A cutting tool made of surface-coated tungsten carbide-based cemented carbide (hereinafter abbreviated as coated cemented cutting tool) that can exhibit excellent cutting performance over a long period of time without occurrence of chipping or chipping (micro chipping). Things.

[0002]

2. Description of the Related Art Conventionally, generally, a lower layer having an average layer thickness of 0.1 to 10 μm is formed on a surface of a tungsten carbide-based cemented carbide substrate (hereinafter, abbreviated as a cemented carbide substrate) by physical vapor deposition. And an upper layer having a thickness of 0.5 to 10 μm, and wherein the lower layer of physical vapor deposition is formed of a carbide layer, a nitride layer, a carbonitride layer, a carbonitride layer, and a carbonitride layer of Ti (hereinafter, TiC layer). , A TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer), and the physical vapor deposition upper layer is made of aluminum oxide (hereinafter, Al ₂ O _3). Coated carbide cutting tools formed by forming a hard coating layer composed of layers are known, and these coated carbide cutting tools may be used for continuous cutting or intermittent cutting of various steels. It is well known. When the hard coating layer of the coated carbide cutting tool is, for example, a TiC layer, a TiN layer, or a TiCN layer, an arc ion plating apparatus which is a kind of a physical vapor deposition apparatus schematically shown in FIG. And generating an arc discharge between the anode electrode and the cathode electrode (evaporation source) on which Ti is set while the inside of the apparatus is heated to a temperature of, for example, 700 ° C. by a heater, and at the same time, as a reaction gas in the apparatus. A methane gas or a nitrogen gas, or a nitrogen gas and a methane gas are introduced. On the other hand, the cemented carbide substrate disposed opposite to the anode electrode and the cathode electrode at a predetermined interval is subjected to the cemented carbide under a condition that a bias voltage of -120 V is applied. It is also known to physically deposit the hard coating layer on the surface of a substrate. Further, when the hard coating layer is an Al ₂ O ₃ layer, in the arc ion plating apparatus of FIG. 1 as well, the cathode electrode is made of Al, the introduced reaction gas is made of oxygen, and Since the Al ₂ O ₃ layer to be formed is an insulating film, it is formed by applying a high-frequency voltage or a pulse voltage instead of a bias voltage to the superhard substrate.

[0003]

On the other hand, there has been a strong demand for energy saving and labor saving in cutting in recent years, and accordingly, cutting tools are not affected by cutting conditions as much as possible, that is, by changing cutting conditions. However, the conventional coated carbide cutting tools mentioned above tend to exhibit cutting performance that can respond sufficiently satisfactorily under any cutting conditions. When cutting is performed under cutting conditions, chipping or chipping is likely to occur in the cutting blade, and the service life is currently reached in a relatively short time.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoint, the conventional coated carbide cutting tool
In order to improve fracture resistance, especially above the hard coating layer
Al constituting the layer_TwoO _ThreeFocusing on the layers,
Fruit, Al_TwoO_ThreeWhen forming a layer by physical vapor deposition, A
Ta, V, Nb, W, Mo
And Cr, that is, an ionic radius of 0.57 Å
The ion radius of each is 0.68
Ngstrom Ta, 0.69 Angstrom
Nb, V of 0.65 angstroms, 0.68 angstroms
W of Ngstrom, M of 0.68 Angstrom
o and one of Cr of 0.64 Å
A species or two or more species of Al_TwoO_ThreeA in the crystal structure of
5 to 20 atoms in proportion to the total amount of part of l atoms and Al
%, Preferably 7 to 15 atomic%.
When the solid solution is contained, the resulting Al_TwoO_ThreeSubject
The layer is caused by increased intra-lattice strain due to large ion radius differences.
The usual physical vapor deposition Al_TwoO_ThreeLayer is affected by layer thickness
Although it has a compressive residual stress of 0.2 to 0.8 GPa,
Then, it has a compressive residual stress of 1-2 GPa,
In this way, the upper layer of the hard coating layer determines the compressive residual stress
High Al_TwoO_ThreeCoated carbide cutting tool composed of main layer
Is especially suitable for heavy cutting conditions for intermittent cutting of various steels.
Immediately for a long time without chipping or chipping
Research results show that it will exhibit excellent cutting performance
It was.

[0005] The present invention has been made based on the above research results, and the surface of a cemented carbide substrate has a thickness of 0.1 to 1 mm.
A lower layer having an average layer thickness of 0 μm;
A hard coated layer composed of an upper layer having an average layer thickness of physical coating is used as a coated carbide cutting tool, and the lower layer of physical vapor deposition is formed of a TiC layer, a TiN layer, a TiCN layer, and a TiC layer.
An O layer and a Ti compound layer composed of one or more of TiCNO layers, and the physical vapor deposition upper layer is formed by combining a part of Al in the crystal structure of Al ₂ O ₃ with Al. Ta at a ratio of 5 to 20 atomic% in proportion,
A physical vapor-deposited hard coating layer composed of an Al ₂ O ₃ main layer formed by substituting and solid-dissolving one or more of V, Nb, W, Mo and Cr has excellent fracture resistance. The coated carbide cutting tool has features.

[0006] In the coated carbide cutting tool of the present invention, the average layer thickness of the physical vapor deposition lower layer (Ti compound layer) is set to 0.1.
The reason why the thickness is set to 1 to 10 μm is that if the layer thickness is less than 0.1 μm, it is not possible to secure the desired toughness of the hard coating layer, and as a result, the cutting edge is liable to be broken, while the layer thickness is 1 μm.
This is based on the reason that the wear progresses rapidly when the thickness exceeds 0 μm. The average thickness of the physical vapor deposition upper layer (Al ₂ O ₃ main layer) is 0.5 to 10 μm.
The reason is that if the layer thickness is less than 0.5 μm, the desired wear resistance cannot be secured, while the layer thickness is 10 μm
The reason is that if it exceeds, the cutting edge is likely to be chipped. In addition, Al in the physical vapor deposition upper layer
The substitution content of Ta, V, Nb, W, Mo, and Cr is set to 5 to 20 atomic% because if the content is less than 5 atomic%, a sufficient compressive residual stress is formed in the upper layer. On the other hand, if the content exceeds 20 atomic%, the compressive residual stress of the upper layer becomes too large and self-destruction is likely to occur.
Further, a TiN layer may be formed on the upper layer, if necessary, with an average thickness of 0.1 to 2 μm.
The reason is that the iN layer has a golden color tone, and this color tone makes it easy to distinguish between before and after the use of the tool.
In this case, if the layer thickness is less than 0.1 μm, 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.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated carbide cutting tool of the present invention will be specifically described with reference to examples. As raw material powders, WC powder having an average particle size of 2 μm and (T
i, W) C (weight ratio, the same applies hereinafter, TiC / WC = 30)
/ 70) Powder, 1.3 μm of (Ta, Nb) C (Ta
C / NbC = 90/10) powder, 2 μm Cr ₃ C ₂
A powder and a Co powder of the same 1.5 μm were prepared, and these raw material powders were blended in the blending composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and dried at 1.5 ton /
The green compact was pressed into a green compact having a shape determined by ISO-CNMG120404 at a pressure of ² cm ^2.
Vacuum sintering is performed under the conditions shown in Table 1. After sintering, R:
Carbide substrates A to E by performing a honing of 0.05
Was manufactured respectively. Further, Table 1 shows that the above-mentioned carbide substrate A
To E (Rockwell hardness A scale).

Next, these super hard substrates A to E are ultrasonically cleaned in an alkaline detergent and an alcohol solution, and are charged in a dried state into an arc ion plating apparatus shown in FIG. Source)
Fitted with Ti. Before the lower layer is formed, also in the upper layer formation, Al ₂ O ₃ Ta in main layer formation, V, Nb,
Al— (Ta, V, Nb, W, Mo, Cr) containing a predetermined amount of one or more of W, Mo, and Cr
At the time of forming the alloy and further the Al ₂ O ₃ layer, Al was mounted, and the inside of the apparatus was evacuated and kept at a vacuum of 1 × 10 ⁻⁵ torr, while the inside of the apparatus was heated to a predetermined temperature in the range of 620 to 720 ° C. predetermined voltage while heating, the bias voltage applied to the carbide substrate in the range of -100 to-260 V in the Ti compound layer formed constituting the lower layer, Al ₂
The upper layer of the O ₃ main layer is formed at −700 V, and the upper layer is formed of Al.
_In the case of a ₂ O ₃ layer, the voltage is set to −150 V. Then, one or more of methane gas, nitrogen gas, and oxygen gas are introduced into the apparatus as a reaction gas according to the composition of the hard coating layer, An arc discharge is generated between the cathode electrode and the anode electrode, whereby the cemented carbide substrate A
To E, the physical vapor deposition lower layer (Ti compound layer) and the physical vapor deposition upper layer (Al ₂ O ₃ main layer or Al ₂ O) having the compositions and average layer thicknesses shown in Tables 2 and _3.
By forming a hard coating layer consisting of _three layers), the coated carbide cutting tools 1 to 7 of the present invention and the conventionally coated carbide cutting tool 1
To 7 were each manufactured. In the conventional coated carbide cutting tools 1 to 7, the physical vapor deposition upper layer of the hard coating layer constituting each of them does not contain any component of Ta, V, Nb, W, Mo and Cr. The contents of Ta, V, Nb, W, Mo and Cr in the Al ₂ O ₃ main layer constituting the physical vapor deposition upper layer of the hard coating layer were quantitatively analyzed using an energy dispersive X-ray measuring apparatus. . The measurement results are shown in Table 2.

[0009] Next, with respect to the various coated carbide cutting tools obtained as a result, a work material: SNCM439 (hardness: HB240), a round bar with four longitudinal grooves at regular intervals in the longitudinal direction, cutting speed: 350 m / min., feed: 0.3 mm / rev., depth of cut: 3 mm, cutting time: 10 minutes, dry intermittent high depth of cut test of alloy steel, and work material: SCM440 (hardness: HB210) 4 rounded bars with longitudinal grooves at equal intervals in the longitudinal direction, Cutting speed: 320 m / min., Feed: 0.42 mm / rev., Cutting depth: 1.5 mm, Cutting time: 10 min. Perform dry intermittent high feed cutting test,
In each cutting test, the flank wear width of the cutting edge was measured.
Table 4 shows the measurement results.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

[0014]

From the results shown in Tables 2 to 4, in the coated carbide cutting tools 1 to 7 according to the present invention, the Al ₂ O ₃ main layer constituting the physical vapor deposition upper layer of the hard coating layer is lower than that of Al. Ta, V, Nb, W, Mo and Cr having large ionic radii
One or more of the above, which results in the retention of extremely high compressive residual stress, so that even when interrupted cutting of steel is performed under high cutting and high feed heavy cutting conditions, the cutting edge is chipped or chipped. While excellent cutting performance is exhibited without the occurrence of cracks, conventional coated carbide cutting tools 1 to 7
In any case, since the compressive residual stress of both the Ti compound layer and the Al ₂ O ₃ layer constituting the hard coating layer is small, chipping or chipping of the cutting edge occurs under the severe conditions described above. It is clear that the working life is relatively short and the service life is reached. As described above, the coated cemented carbide cutting tool according to the present invention has the A layer constituting the upper layer of the hard coating layer.
Due to the extremely high compressive residual stress of the l ₂ O ₃ main layer, continuous cutting and intermittent cutting of various steels under normal conditions, as well as intermittent cutting under extremely severe cutting conditions, with high cutting and high feed weights, can be performed. The cutting edge shows excellent chipping resistance even under cutting conditions, and exhibits excellent cutting performance over a long period of time. It can sufficiently cope with energy saving and labor saving in cutting. It is.

[Brief description of the drawings]

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

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Claims (1)

[Claims] 1. A lower layer having an average layer thickness of 0.1 to 10 μm on a surface of a tungsten carbide-based cemented carbide substrate,
A surface-coated tungsten carbide based cemented carbide cutting tool formed by physical vapor deposition of a hard coating layer composed of an upper layer having an average layer thickness of 0.5 to 10 μm. A carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a Ti compound layer composed of one or more of carbonitride layers, and the physical vapor deposition upper layer is made of aluminum oxide. T in a ratio of 5 to 20 atomic% as a proportion of a part of Al in the crystal structure to the total amount with Al
a physical vapor-deposited hard coating layer composed of an aluminum oxide-based layer which is substituted and solid-solved with one or more of a, V, Nb, W, Mo and Cr, and has excellent fracture resistance. A cutting tool made of a surface-coated tungsten carbide-based cemented carbide having a surface.