JP2002011605A - Surface-coated cermet cutting tool with hard coating layer showing excellent wear resistance in high-speed cutting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent chipping of a cutting edge, and ensure excellent wear resistance, long-term excellent cutting performance, and a prolonged service life even in high-speed cutting on various types of steel, cast iron and the like. SOLUTION: A surface-coated cutting tool of cermet has a hard coating layer of an average layer thickness of 5 to 30 μm formed through chemical vapor deposition and/or physical vapor deposition over the surface of a cermet base comprising a tungsten carbide-based cemented carbide base or a titanium carbonitride-based cermet base. The hard coating layer each comprises one layer or two or more layers of a carbide layer, a nitride layer, a carbonitride layer, a carboxide layer and a carbonitroxide layer all of Ti and having a granular crystal structure; an aluminum oxids layer also having a granular crystal structure; and a composite nitride layer of Ti and V having a longitudinally grown crystal structure and a V content of 1 to 30 atomic % rated in the total amount of Ti and V.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool) in which a hard coating layer exhibits excellent wear resistance in high-speed cutting.

[0002]

2. Description of the Related Art Conventionally, a hard coating layer is generally formed on a surface of a cermet substrate made of a tungsten carbide (hereinafter, referred to as WC) -based cemented carbide substrate or a titanium cermet (hereinafter, referred to as TiCN) -based cermet substrate. A coated cermet tool formed by chemical vapor deposition and / or physical vapor deposition with an average layer thickness of ３０30 μm is known, and it is well known that this tool is used for continuous cutting and interrupted cutting of various steels and cast irons. is there.

In the above-mentioned coated cermet tool, the hard coating layer is generally made of a (a) Ti carbide (hereinafter referred to as TiC) layer or a nitride (hereinafter also referred to as TiC), each having a granular crystal structure. A TiN layer, a carbonitride (hereinafter TiCN) layer, a carbon oxide (hereinafter T
iCO) layer and carbonitride (hereinafter TiCN)
O) layer consisting of carbon, nitrogen and oxide (hereinafter referred to as T)
one or two or more layers of iC.NO.)
(B) an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer also having a granular crystal structure, and (c) a Ti carbonitride having a vertically elongated crystal structure (hereinafter referred to as 1-TiCN).
Layer, or (a), (b), and is composed of (c), the the Al ₂ O ₃ layer and l-TiC of these hard layer
The N layer is applied in a state where the thickness of the layer is relatively thick, while the TiC • NO layer is applied in a state where the thickness is relatively thin, and in this case, the Al ₂ O ₃ layer is thermally applied. Since the l-TiCN layer has high toughness while having excellent stability, the interaction between these two constituent layers allows the hard coating layer to have wear resistance and chipping resistance. On the other hand, it is well known that the TiC · N · O layer exists for the purpose of improving the adhesion between the Al ₂ O ₃ layer and the 1-TiCN layer on the surface of the cermet substrate and between the constituent layers of the hard coating layer. .

Further, as the Al ₂ O ₃ layer constituting the hard coating layer of the above-mentioned conventional coated cermet tool, those having an α-type crystal structure and those having a κ-type crystal structure are widely put into practical use. The above l- which also forms the hard coating layer
As described in, for example, JP-A-6-8010 and JP-A-7-328808, the TiCN layer uses a mixed gas containing an organic carbonitride as a reaction gas in a normal chemical vapor deposition apparatus, It is also known to be formed by chemical vapor deposition at a medium temperature range of 700 to 950 ° C.

[0005]

On the other hand, in recent years, the use of FA and high performance cutting equipment has been remarkable, and there has been a strong demand for labor saving, energy saving, and lower cost for the cutting work. Machining tends to be faster, but with the above-mentioned conventional coated cermet tools, there is no problem with continuous or interrupted cutting under normal conditions such as steel or cast iron, but especially continuous or interrupted cutting is performed at high speed. In such a case, the wear progress of the above-mentioned 1-TiCN layer, which is a constituent layer of the hard coating layer, is fast, and the service life is relatively short. Further extension of life is strongly desired.

[0006]

Means for Solving the Problems Accordingly, the present inventors have
In view of the above, research was conducted to develop a coated cermet tool in which a hard coating layer exhibits excellent wear resistance even when used for high-speed cutting of steel, cast iron, etc., and as a result, (a) ) In a normal chemical vapor deposition device, the reaction gas composition is
By _{volume%, TiCl 4: 0.5~5%,} C 3 H 8: 0.0
When a layer is formed under the conditions of 5 to 3%, Ar: 1 to 50%, H ₂ : residual, and the reaction atmosphere temperature: 700 to 950 ° C., and the reaction atmosphere pressure: 4 to 25 kPa, the vertically grown crystal is obtained. T with organization
An iC layer (hereinafter, referred to as an l-TiC layer) is formed.

(B) The l-TiC layer obtained in (a) has high toughness due to the vertically-grown crystal structure and high hardness inherent to the TiC layer, but exhibits desired wear resistance by high-speed cutting. Although the hardness is still insufficient, vanadium tetrachloride (hereinafter, referred to as VCl ₄ ) was blended into the reaction gas used for forming the l-TiC layer by the same ordinary chemical vapor deposition apparatus. The conditions, ie, the reaction gas composition, in volume%, T
_{iCl 4: 0.5~5%, VCl 4} : 0.01~0.5
_{%, C 3 H 8: 0.05~3} %, Ar: 1~50%,
When the layer is formed under the following conditions: H ₂ : remaining, reaction atmosphere temperature: 700 to 950 ° C., reaction atmosphere pressure: 4 to 25 kPa, the vertically grown crystal in which the V component is contained in the l-TiC layer A composite carbide layer of Ti and V in the structure [hereinafter, referred to as an l- (Ti, V) C layer] is formed.

(C) l- (Ti, obtained in (b) above)
V) In the C layer, assuming that the ratio of the V component contained in the C layer is 1 to 30 atomic% in the total amount with the Ti component, in addition to the high hardness of the l-TiC layer, The hardness of the layer itself is further improved by the action of
Since it has the same high toughness as the N layer and has a higher hardness than the N layer, the above-mentioned l-(-) is used instead of the l-TiCN layer constituting the hard coating layer of the conventional coated cermet tool. The coated cermet tool in which the Ti, V) C layer is applied as a constituent layer of the hard coating layer has excellent wear resistance even in high-speed cutting of steel or cast iron, for example, and is excellent over a long period of time. Demonstrate cutting performance. The research results shown in (a) to (c) above were obtained.

The present invention has been made based on the results of the above research, and is based on a WC-based cemented carbide substrate or TiC
On the surface of a cermet substrate composed of an N-based cermet substrate,
In a coated cermet tool obtained by chemical vapor deposition and / or physical vapor deposition of a hard coating layer with an average layer thickness of 5 to 30 μm, the hard coating layer may be formed by (a) a TiC layer, a TiN layer, a T
T composed of an iCN layer, a TiCO layer, and a TiCNO layer
one or more of iC / NO layers, (b) A
l ₂ O ₃ layer, (c) a ratio of V to Ti with respect to the total amount of 1 to 1
A 1- (Ti, V) C layer containing 30 atomic%, a coating comprising a hard coating layer having excellent wear resistance in high-speed cutting, comprising the above (a), (b) and (c). The cermet tool has features.

In the coated cermet tool of the present invention, the V of the l- (Ti, V) C layer constituting the hard coating layer
In the total content with the Ti component is 1 to 3
The reason why 0 atomic% is set is that if the ratio is less than 1 atomic%, the desired effect of further improving the hardness of the layer itself caused by the V component cannot be obtained. This is because the formation of the grown crystal structure is disturbed, and the content is desirably set to 3 to 15 atomic%. The reason why the average thickness of the hard coating layer is set to 5 to 30 μm is that if the layer thickness is 5 μm, the desired excellent wear resistance cannot be secured. This is because chipping and chipping easily occur in the blade.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated cermet 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 pressed into a green compact at a pressure of 120 MPa, and the green compact is pressed in a vacuum of 6 Pa at a temperature of 1410.
C. for 1 hour under vacuum, and after sintering, the cutting edge is subjected to a honing process of R: 0.05 mm to have a chip shape of ISO standard CNMG120408, and W
Cermet substrates A1 to A8 composed of a C-base cemented carbide were formed.

In addition, as raw material powders,
TiCN having an average particle size of 2 μm (TiC /
(TiN = 50/50) 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 into the composition shown in Table 2. After being wet-mixed in a ball mill for 24 hours, dried and pressed into a green compact at a pressure of 100 MPa, the green compact was fired in a nitrogen atmosphere of 1.3 kPa at a temperature of 1500 ° C. for 1 hour. After sintering and sintering,
The cutting edge portion was subjected to a honing process of R: 0.03 mm to form cermet bases B1 to B6 having a chip shape of ISO standard CNMG120412 and made of a TiCN-based cermet.

Then, these cermet substrates A-1 to A-1
On the surfaces of A-8 and B-1 to B-6, using a general chemical vapor deposition apparatus, under conditions shown in Tables 3 and 4, TiC.
N · O layer and Al ₂ O ₃ layer, and furthermore l- (Ti, V) C
Tables 5 and 6
The coated cermet tools 1 to 14 of the present invention and the conventional coated cermet tools 1 to 14 were produced by forming the target layer thicknesses and combinations shown in Table 1 below.

The resulting coated cermet tool 1 of the present invention
When the content ratio of the V component in the 1- (Ti, V) C layer constituting the hard coating layer of No. 14 was measured using an Auger spectrometer, the content ratio was substantially the same as the target content ratio. The thicknesses of the constituent layers of the hard coating layers of the coated cermet tools 1 to 14 of the present invention and the conventional coated cermet tools 1 to 14 were respectively measured in cross section by using a scanning electron microscope. The same average layer thickness (average value of five points measurement) was shown.

Next, the coated cermet tool 1 of the present invention will be described.
-14, and the conventional coated cermet tools 1-14, which were screwed to the tip of a tool steel bit with a fixing jig. Work material: JIS SCM415 round bar, Cutting speed: 500 m / min , Depth of cut: 2 mm, feed: 0.2 mm / rev, cutting time: 5 minutes, dry high-speed continuous turning test of alloy steel under the following conditions: Work material: JIS FC300 round bar, Cutting speed: 500 m / min , Depth of cut: 2 mm, feed: 0.2 mm / rev, cutting time: 5 minutes, dry high-speed continuous turning test of cast iron under the following conditions: Work material: JIS / SCM440 lengthwise regular interval 4 Dry high-speed intermittent turning test of alloy steel under the conditions of this vertical grooved round bar, cutting speed: 300 m / min, depth of cut: 1.5 mm, feed: 0.2 mm / rev, cutting time: 5 minutes Work material: Round bar with four vertical grooves at regular intervals in the longitudinal direction of JIS / FC300, Cutting speed: 300 m / min, Cutting depth: 1.5 mm, Feed: 0.2 mm / rev, Cutting time: 5 minutes A dry high-speed intermittent turning test of cast iron was performed under the conditions, and the maximum flank wear width of the cutting edge was measured in each turning test. Table 7 shows the measurement results.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

[Table 5]

[0021]

[Table 6]

[0022]

[Table 7]

[0023]

From the results shown in Tables 5 to 7, it can be seen that 1-Ti
The coated cermet tools 1 to 14 according to the present invention in which the l- (Ti, V) C layer is a constituent layer of the hard coating layer instead of the CN layer, the l- (Ti, V) C layer has high toughness and Because of its extremely high hardness, even when continuous and interrupted cutting of alloy steel or cast iron is performed at high speed, the hard coating layer shows excellent wear resistance and enables a longer service life. On the other hand, the conventional coated cermet tools 1 to 14 having the l-TiCN layer as a constituent layer show rapid wear progress due to insufficient hardness of the l-TiCN layer in high-speed cutting of alloy steel or cast iron, Obviously, the service life is reached in a relatively short time. As described above, the coated cermet tool of the present invention is not limited to continuous cutting and intermittent cutting under ordinary conditions such as various types of steel and cast iron, and in particular, even when these cuttings are performed at high speed, the chipping of the cutting edge can be performed. Demonstrates excellent wear resistance without chipping or chipping, shows excellent cutting performance over a long period of time, and extends the service life. Satisfactorily, and can contribute to labor saving, energy saving, and cost reduction in cutting.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C23C 28/04 C23C 28/04 // C22C 29/02 C22C 29/02 Z F term (Reference) 3C046 FF03 FF05 FF10 FF13 FF16 FF19 FF22 FF25 4K029 AA02 BA02 BA03 BA17 BA44 BA54 BA55 BA60 BB02 BC02 BD05 4K030 AA03 AA10 AA17 BA02 BA18 BA19 BA36 BA38 BA41 BA43 BB12 CA03 FA10 JA01 JA06 4K044 AA09 BA18 BC01BB13

Claims (1)

[Claims] 1. A surface obtained by chemical vapor deposition and / or physical vapor deposition of a hard coating layer with an average thickness of 5 to 30 μm on the surface of a cermet substrate comprising a tungsten carbide-based cemented carbide substrate or a titanium carbonitride-based cermet substrate. In the coated cermet cutting tool, the hard coating layer comprises: (a) a carbide layer, a nitride layer, a carbonitride layer, a carbonitride layer, and a carbonitride layer of Ti, each having a granular crystal structure. (B) an aluminum oxide layer also having a granular crystal structure, (c) a vertically elongated crystal structure, and V being the total amount of Ti The hard coating layer is excellent in high-speed cutting, characterized by being composed of a composite carbide layer of Ti and V containing 1 to 30 atomic% in a ratio to the above, characterized by the above (a), (b) and (c). Develops wear resistance Surface-coated cermet cutting tool to be.