JPH09141502A - Surface-coated tungsten-carbide-based cemented carbide having good chipping resistance in hard coated layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the tip of a tool from being broken or chipped even if heavy cutting such as large feed or large depth of cut is intermittently performed by making the mean thickness of aluminum oxiside multi-layers a specified value. SOLUTION: This alloy comprises Al2 O3 multi-layers comprising at least two alternately laminated layers of a Al2 O3 unit layer which is 0.5 to 3μm is mean thickness and contains S of 0.1 to 0.2atom% and a pure Al2 O3 unit layer which is 0.1 to 1μm in mean thickness and does not contain S substantially. The mean thickness of the Al2 O3 multi-layers is 1 to 10μm. When the mean thickness of the Al2 O3 multi-layers is over 10μm, the tip of the tool is apt to be broken or chipped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-coated tungsten carbide-based cemented carbide cutting tool having a hard coating layer having excellent fracture resistance (hereinafter referred to as coated carbide cutting tool).

[0002]

2. Description of the Related Art Conventionally, on the surface of a tungsten carbide based cemented carbide substrate (hereinafter referred to as a cemented carbide substrate), a Ti carbide (hereinafter referred to as TiC) has been formed by a chemical vapor deposition method or a physical vapor deposition method.
Layer), a nitride (hereinafter referred to as TiN) layer, a carbonitride (hereinafter referred to as TiCN) layer, a carbon oxide (hereinafter referred to as Ti)
CO) layer, nitric oxide (hereinafter referred to as TiNO)
Layer and one or more of carbon oxynitride (hereinafter, referred to as TiCNO) layers (hereinafter, these are collectively referred to as Ti carbon / nitrogen / oxide layers) and aluminum oxide (hereinafter, referred to as A).
The hard coating layer is composed of a l ₂ O indicated by ₃₎ layer, 10
A coated carbide cutting tool formed with an average layer thickness of up to 20 μm is known, and it is also well known that this coated carbide cutting tool is used for, for example, continuous cutting or interrupted cutting of steel or cast iron. It is about to be done. Also, JP-A-57-578
As described in Japanese Patent Laid-Open No. 65-65, in forming an Al ₂ O ₃ layer that constitutes a hard coating layer of a coated carbide cutting tool, sulfur is added for the purpose of increasing the deposition rate and enabling thick film formation. It is also practiced to use a reaction gas containing (S).

[0003]

On the other hand, the recent cutting process
There is a strong demand for high efficiency and labor saving of
No cutting, high speed, high feed and high depth of cut
Which is the tendency of heavy cutting, but the above conventional coated carbide cutting
In the tool, the Al of the hard coating layer constituting this _TwoO_Three
If the layer is formed into a thick film, especially with an S-containing reactive gas,
In the case of Al_TwoO_Three0.01 to 0.2 atomic% of the layer
S component is contained, and as a result, this S-containing Al
_TwoO_ThreeEmbrittlement of the layer is unavoidable, which causes high toughness.
Heavy cutting required, eg high feed and high depth of cut
When it is used for intermittent cutting of
(Small chips) easily occur, reaching the service life in a relatively short time
is the current situation.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoint, A constituting the hard coating layer is formed.
l_TwoO_ThreeThe layer contains 0.01 to 0.2 atomic% S component
Focusing on the conventional coated carbide cutting tool,_TwoO_Threelayer
As a result of conducting research to prevent embrittlement of Al,
_TwoO_ThreeThe S-containing Al_TwoO_ThreeAt least one of the layers
And pure Al containing substantially no S component_TwoO_ThreeFew layers
Al consisting of at least two alternating layers_TwoO _ThreeComposed of multiple layers
Then, the resulting Al_TwoO_ThreeThe multilayer is the pure Al_Two
O_ThreeIt is difficult to increase the thickness of a single layer, but alternate layers
S-containing Al_TwoO_ThreeIt is possible to thicken the film depending on the layer.
And the pure Al_TwoO_ThreeThe layer helps prevent embrittlement
Therefore, the Al_TwoO_ThreeMultiple layers,
Consists of one or more of the above Ti carbon / nitride / oxide layers
Coated carbide cutting tool formed by forming a hard coating layer,
Heavy cutting such as high feed and high depth of cut requiring high toughness
Even if the cutting is performed intermittently, chipping or chipping of the cutting edge
Raw, the Al_TwoO_ThreeIn addition to being a thick film
Therefore, it is said that excellent cutting performance will be exhibited over a long period of time.
I got the research results.

The present invention is based on the above research results.
What is done is, the surface of the cemented carbide substrate, Ti charcoal
Al and at least one of the nitrogen and oxide layers_TwoO_ThreeComposed of layers
Formed hard coating layer with an average layer thickness of 7 to 20 μm
In the coated carbide cutting tool consisting of_TwoO_Threelayer
Has an average layer thickness of 0.5 to 3 μm, and 0.01 to
S-containing Al containing 0.2 atomic% S component_TwoO_Threeunit
With at least one of the layers and an average layer thickness of 0.1 to 1 μm
Pure Al containing substantially no S component_TwoO_ThreeUnit layer
Al consisting of at least two alternating layers_TwoO_ThreeIn multiple layers
And comprises Al _TwoO_ThreeThe average layer thickness of multiple layers is 1 to 1
Characterized by a coated carbide cutting tool with a thickness of 0 μm
It is.

Next, the reason for limiting the numerical values as described above in the coated carbide cutting tool of the present invention will be described. (A) Average layer thickness of hard coating layer If the average layer thickness is less than 7 μm, desired abrasion resistance cannot be secured, while if the average layer thickness exceeds 20 μm, chipping or chipping occurs on the cutting edge. Therefore, the average layer thickness is 7 to 20 μm, preferably 10 to 1
It was set to 8 μm.

(B) S-containing Al_TwoO_ThreeAverage layer of unit layer
Thickness If the average layer thickness is less than 0.5 μm, film formation by this
Since it is not possible to fully utilize the speedup and thickening of the film,
On the other hand, if the average layer thickness exceeds 3 μm, Al_TwoO _ThreeMultiple layers
Since the brittleness tendency appears in the average layer
The thickness is set to 0.5 to 3 μm, preferably 1 to 2.5 μm
Was.

(C) S content of S-containing Al ₂ O ₃ unit layer If the S content is less than 0.01 at%, the desired effects cannot be obtained for speeding up the film formation and increasing the film thickness. If the content exceeds 0.2 atom%, embrittlement of the material itself becomes significant, so the content is defined as 0.01 to 0.2 atom%, preferably 0.03 to 0.08 atom%. It was

(D) Average Layer Thickness of Pure Al ₂ O ₃ Unit Layer If the average layer thickness is less than 0.1 μm, the desired toughness cannot be ensured in the Al ₂ O ₃ multilayer, while the average layer thickness is less than that. When the thickness exceeds 1 μm, the film forming rate suddenly decreases, so the average layer thickness was set to 0.1 to 1 μm, preferably 0.3 to 0.7 μm.

(E) Average Layer Thickness of Al ₂ O ₃ Multilayer If the average layer thickness is less than 1 μm, the hard coating layer cannot be provided with excellent heat plastic deformation resistance and wear resistance. If the layer thickness exceeds 10 μm, chipping or chipping is likely to occur at the cutting edge, so the average layer thickness is set to 1 to 10 μm, preferably 3 to 7 μm.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the coated carbide cutting of the present invention
The tool will be specifically described by way of examples. As raw material powder
Average particle size: 3 μm WC powder, 1.5 μm (T
i, W) C [weight ratio TiC / WC = 30/70) powder
Finally, 1.2 μm of (Ti, W) CN [TiC / TiN
/ WC = 24/20/56) powder, Ta of 1.3 μm
C powder and 1.2 μm Co powder were used.
The raw material powder was blended to the blending composition shown in Table 1 and
Wet-mix for 72 hours and dry, then 1 ton / cm ^Twoof
It is pressed into a green compact with pressure, and this green compact is 1 × 10
^-2Sintered in a torr vacuum at a temperature of ℃ for 1 hour and IS
Throw-away tip type of O standard CNMG120408
Carbide substrates A to D each having a shape were manufactured. About
Then, on each surface of the above-mentioned cemented carbide substrates A to D
Table 3 and 4 under the conditions shown in Table 2
A hard coating layer of the indicated composition and average layer thickness can be formed.
By the present invention coated carbide cutting tools 1-8 and conventional coating
Carbide cutting tools 1 to 8 were manufactured.

Then, with respect to various coated cemented carbide cutting tools obtained as a result, a round bar containing four longitudinal grooves with equal intervals in the work material: SCM440 (hardness: H _B 230), cutting speed: 220 m / Min, feed: 0.4 mm / rev., Depth of cut: 1.5 mm, cutting time: 10 minutes, dry high-feed intermittent cutting test of steel, and work material: SCM439 (hardness: H _B 270) square bar, cutting speed: 160 m / min, feed: 0.3 mm / rev., Depth of cut: 3 mm, cutting time: 10 minutes
In each test, the flank wear width of the cutting edge was measured. Table 5 shows the results of these measurements.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

[0016]

[Table 4]

[0017]

[Table 5]

[0018]

From the results shown in Table 5, the coated carbide cutting tools 1 to 8 of the present invention show that Al of the hard coating layer which constitutes them.
Despite being a thick film, the ₂ O ₃ multi-layer has excellent toughness, so even if high-feed cutting and high-cut cutting are performed with interrupted cutting, the cutting edge does not chip or chip, which is excellent. Whereas the conventional coated carbide cutting tools 1 to 8 show wear resistance, chipping and chipping occur in the cutting edge in a relatively short time due to the thick film S-containing Al ₂ O ₃ layer,
It is clear that it will reach the end of its useful life. As described above, the coated carbide cutting tool of the present invention can make the Al ₂ O ₃ multilayer of the hard coating layer constituting the thick film, and the Al ₂ O ₃ multilayer of this thick film is Due to its excellent toughness, the hard coating layer exhibits excellent fracture resistance even under severe cutting conditions, and exhibits excellent cutting performance over a long period of time, thus improving cutting efficiency and saving labor. It is possible to fully satisfy the demands for

Claims (1)

[Claims] 1. A tungsten carbide-based cemented carbide substrate having one surface selected from a Ti carbide layer, a nitride layer, a carbonitride layer, a carbon oxide layer, a oxynitride layer, and a oxycarbonitride layer. Above, a hard coating layer composed of an aluminum oxide layer,
In a surface-coated tungsten carbide-based cemented carbide cutting tool formed to have an average layer thickness of 7 to 20 μm, the aluminum oxide layer constituting the hard coating layer is 0.
At least one S-containing aluminum oxide unit layer having an average layer thickness of 5 to 3 μm and containing 0.01 to 0.2 atomic% of sulfur (S), and an average layer thickness of 0.1 to 1 μm. Characterized in that it is composed of an aluminum oxide multi-layer consisting of at least two layers of a pure aluminum oxide unit layer which does not substantially contain S component and has an average layer thickness of 1 to 10 μm. A surface-coated tungsten carbide-based cemented carbide cutting tool having a hard coating layer with excellent fracture resistance.