JPH05123904A - Cutting tool made of hard layer coat tungsten carbide hard metal - Google Patents

Abstract

PURPOSE:To provide a cutting tool made of hard layer coat WC base cemented carbide excellent in cutting ductile cast iron. CONSTITUTION:(1) A cutting tool made of hard layer coat WC cemented carbide comprises the surface of a WC cemented carbide alloy base made of Co: 4.0:7.0weight%, carbide other than WC: 3.0weight% or less, and WC: remainder, whose mean grain size is 0.5 to 3mum, coated with a single hard layer made of TiC or TiCN whose mean crystal grain size is 0.01 to 0.5mum and mean layer thickness of 5 to 20mum. (2) A cutting tool is made of hard layer coat WC cemented carbide comprising the hard layer of a cutting tool made of a hard layer coat WC cemented carbide alloy used as a lower layer, and the surface of this lower layer coated with an upper layer composed of single layer made of one out of TiCO, TiCNO, TiN and aluminum oxide or plural layers, whose mean thickness 0.1 to 1.0mum, made of two or more of them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard layer coated tungsten carbide based cemented carbide cutting tool which exhibits excellent performance when used for cutting cast iron, particularly ductile cast iron.

[0002]

2. Description of the Related Art Generally, tungsten carbide (hereinafter referred to as WC
A hard layer-coated WC-based superstructure obtained by coating the surface of a base cemented carbide substrate with a hard layer composed of a single layer of TiC or TiCN (hereinafter referred to as a hard layer) by a chemical vapor deposition method or a physical vapor deposition method. Hard metal cutting tools are known.

Further, the hard layer is used as a lower layer, and TiCO and TiCN formed on the lower layer and the lower layer.
Made of WC-based cemented carbide with a hard layer formed by forming a coating layer having an average layer thickness of 0.5 to 10 μm, which is composed of an upper layer consisting of a single layer of O, TiN, and Al ₂ O ₃ or a plurality of layers thereof. Cutting tools are also known.

[0004]

The above-mentioned conventional hard layer-coated WC-based cemented carbide cutting tool is generally used for cutting steel and shows excellent characteristics, but its structure is ferrite or pearlite When high-strength and high-hardness cast iron in which graphite is mixed with hard phase and soft phase are mixed, particularly ductile cast iron is cut using the above conventional hard layer-coated WC-based cemented carbide cutting tool, The cutting edge of the cutting tool is subject to severe wear and intermittent impact, the hard layer is easily peeled off, chipping, cracks, etc. easily occur, abnormal wear occurs early and there is a problem that sufficient service life cannot be obtained ..

[0005]

Therefore, the present inventors have
From such a viewpoint, as a result of conducting research to obtain a hard layer-coated WC-based cemented carbide cutting tool that has a long service life even when cutting ductile cast iron, as a result, the grain size of WC is as fine as possible within a range of 0.5 to 3 μm. The content of Co is 4.0% to 7.0% by weight and the content of carbides other than WC is as low as 3.0% by weight or less. On the surface of this substrate, a single layer of TiC or TiCN consisting of a fine and uniform thick single layer is formed, and the average crystal grain size is 0.01 to 0.
A hard layer-coated WC-based cemented carbide cutting tool with a hard layer having a thickness within the range of 5 μm and a thickness of 5 to 20 μm is accompanied by severe wear and intermittent impact like ductile cast iron. We have obtained the knowledge that the tool has a sufficiently long life even for cutting.

The present invention has been made on the basis of such findings, and Co: 4.0 to 7.0% by weight, WC
Carbides other than: 3.0% by weight or less, WC: Cutting formed by coating the surface of a WC-based cemented carbide substrate consisting of the balance with a hard layer having a mean layer thickness of 5 to 20 μm consisting of a single layer of TiC or TiCN In the tool, the average grain size of WC contained in the WC-based cemented carbide substrate is in the range of 0.5 to 3 μm, and the average grain size of the crystal grains of the hard layer is 0.01 to.
It is characterized by a hard layer-coated WC-based cemented carbide cutting tool within a range of 0.5 μm. Further, the hard layer-coated WC-based cemented carbide cutting tool of the present invention has a hard layer formed on the surface of a substrate as a lower layer, and TiCO, TiCNO, TiN and Al ₂ O ₃ are formed on the lower layer. It is also possible to form a coating layer having an average layer thickness of 0.1 to 10 μm, which is composed of a layer or an upper layer composed of a plurality of layers thereof.

In order to form the hard layer or the lower layer of the hard layer-coated WC-based cemented carbide cutting tool of the present invention, first, a WC-based cemented carbide substrate having a predetermined WC particle size and composition is chemically vapor deposited. It is formed by charging in an apparatus and performing chemical vapor deposition at a temperature lower than a normal chemical vapor deposition reaction temperature by 50 to 100 ° C. for a long time.

Next, the reason why the base and hard layer of the hard layer coated WC-based cemented carbide cutting tool of the present invention are limited as described above will be explained.

(1) WC contained in a WC-based cemented carbide substrate
The average grain size of WC contained in the substrate used in the hard layer-coated WC-based cemented carbide cutting tool of the present invention is less than 0.5 μm, because the toughness of the substrate decreases, while the average grain size of 3
TiC or Ti formed on the substrate when the thickness exceeds μm
The average grain size of the hard layer consisting of a single layer of CN also becomes large, which is not preferable. Therefore, the average particle size of WC contained in the WC-based cemented carbide substrate is set to 0.5 to 3 μm.

(2) WC contained in WC-based cemented carbide substrate
Amount of added carbides other than WC If the added amount of carbides other than WC exceeds 3% by weight, the toughness is rather deteriorated, which is not preferable. Therefore, the addition amount of carbides other than WC contained in the WC-based cemented carbide substrate is set to 3% by weight or less.

(3) Co contained in the WC-based cemented carbide substrate
The addition amount of Co is added as a binder phase forming component, but if its content is less than 4.0% by weight, the toughness of the WC-based cemented carbide substrate is lowered, which is not preferable. If it is contained in excess of 10%, wear resistance is lowered, which is not preferable. Therefore, Co contained in the WC-based cemented carbide substrate
The addition amount of was determined to be 4.0 to 7.0% by weight.

(4) Average particle size and film thickness of hard layer composed of single layer of TiC or TiCN Even if the average particle size of hard layer composed of single layer of TiC or TiCN is less than 0.01 μm, it also exceeds 0.5 μm. However, sufficient wear resistance was not obtained, and the film thickness was 5μ.
If it is less than m, sufficient wear resistance cannot be obtained, while 20 μm
If it exceeds m, the toughness decreases, which is not preferable. Therefore, the average particle size of the hard layer consisting of a single layer of TiC or TiCN is 0.01 to 0.5 μm, and the film thickness is 5 to 20 μm.
Stipulated in.

(5) Thickness of upper layer If the thickness of the upper layer is less than 0.1 μm, no effect is obtained.
If it exceeds μm, the toughness decreases, which is not preferable. Therefore, the film thickness of the upper layer is set to 0.1 to 10 μm. ,

[0014]

EXAMPLES Next, the hard layer-coated WC-based cemented carbide cutting tool of the present invention will be specifically described based on Examples.

Example 1 As raw material powders, WC powders having different average particle sizes shown in Table 1, (Ti, W) C powders having an average particle size of 1.0 μm, average particle size: 1.0 μm A (Ti, Ta, W) C powder having the following formula, a TaC powder having an average particle size of 1.0 μm are prepared, and these raw material powders are compounded so as to have the compounding composition shown in Table 1. Are mixed and then press-molded to produce a green compact, and by sintering these green compacts, a sintered body having a composition substantially the same as the above-mentioned composition is produced, and these sintered bodies are ground. JIS standard SNG4
Make a throwaway tip with a shape corresponding to 32,
The throwaway chips were used as the present invention substrates A to E and comparative substrates F to J. Inventive substrates A to E shown in Table 1
Are substrates satisfying the conditions of the present invention, while comparative substrates F to J are substrates not satisfying the conditions of the present invention, and values deviating from the conditions of the present invention are marked with *. ..

[0016]

[Table 1]

Ti is deposited on the surfaces of the gold substrates A to E of the present invention under the following conditions for a predetermined time by chemical vapor deposition.
A hard layer was formed consisting of a single layer of C and TiCN with the average grain size and average layer thickness shown in Table 2.

[Chemical Vapor Deposition Conditions for Hard Layer of the Present Invention] (a) In the case of TiC layer Temperature: 950 ° C., pressure: 100 torr, reaction gas composition: 4% TiCl ₄ -8% CH ₄ -88% H
₂ (b) In case of TiCN layer Temperature: 930 ° C., pressure: 100 torr, composition of reaction gas: 4% TiCl ₄ -8% CH ₄ -4% N ₂
-84% H ₂

Further, for comparison, each of Comparative Substrates F to J is composed of a single layer of TiC and TiCN under the above [chemical vapor deposition conditions of the hard layer of the present invention] and has the average particle size and the average layer thickness shown in Table 3. Comparative coated cutting tools 1 to 5 coated with hard layers satisfying the conditions of the present invention were prepared, and the average particle size and average shown in Table 3 which did not satisfy the conditions of the present invention on the substrates A to D of the present invention under the following conditions. Comparative coated cutting tools 6-9 coated with a hard layer having a layer thickness were produced.

[Chemical vapor deposition conditions for comparative hard layer] (a) In the case of TiC layer Temperature: 1030 ° C., pressure: 100 torr, reaction gas composition: 4% TiCl ₄ -5% CH ₄ -91% H
₂ (b) TiCN layer Temperature: 1000 ° C., pressure: 100 torr, reaction gas composition: 4% TiCl ₄ -3% CH ₄ -4% N ₂
-89% H ₂

The average grain size of the crystal grains of the hard layer is measured by the Heyn method, and a fracture surface of the hard layer is taken by SEM photograph, and the diameter (L) of the circle drawn on the photograph is cut. The average number of particles (N) was measured, and L / N was defined as the average diameter of particles = average particle size. However, in this case, when particles at both ends were cut at the boundary, the number was calculated as 1/2.

With respect to the coated cutting tools 1 to 10 of the present invention and the comparative coated cutting tools 1 to 9 thus obtained, the work material: FCD70 (ductile cast iron), the cutting speed: 250 m / min, the feed: 0.3 m / rev. , Depth of cut: 2 mm, cutting time: 10 min. A high-speed continuous cutting test was conducted under the conditions of: no cooling oil, the flank wear width of the cutting edge was measured, and the cutting edge condition was also observed. The results are shown in Tables 2 and 3.

[0023]

[Table 2]

[0024]

[Table 3]

From the results shown in Tables 2 and 3, Co: 4.0 to 7.0% by weight of the present invention, carbides other than WC: 3.0% by weight or less, WC: balance, and average WC The grain size is in the range of 0.5 to 3 μm. The surface of the substrate of the present invention is a single layer of TiC or TiCN, and the average grain size of the crystal grains of the hard layer is in the range of 0.01 to 0.5 μm. Each of the coated cutting tools 1 to 10 of the present invention, which is formed by coating a hard layer having an average layer thickness of 5 to 20 μm, shows normal wear after cutting for 10 minutes, whereas comparative bases F to J which do not satisfy the conditions of the present invention. Comparative coated cutting tools 1 to 5 coated with hard layers satisfying the conditions of the present invention and comparative coated cutting tools 6 to 9 coated with hard layers not satisfying the conditions of the present invention on substrates A to D of the present invention are all 10 Chipping occurs within minutes, and in a short time It can be seen that leads to life.

Example 2 The hard layer of the coated cutting tools 1 to 10 of the present invention obtained in Example 1 was used as a lower layer, and Tables 4 to 5 were further formed on the lower layer.
An upper layer composed of a single layer of TiCO, TiN, TiCNO and Al ₂ O ₃ having a thickness shown in FIG. 18 was produced.

The conditions for forming the upper layer by the chemical vapor deposition method are as follows. (A) In case of TiN layer Temperature: 980 ° C., pressure: 100 torr, Reaction gas composition: 4% TiCl ₄ -8% N ₂ -88% H ₂ (b) In case of TiCO layer Temperature: 1000 ° C., pressure: 100 torr, Reaction gas composition: 4% TiCl ₄ -6% CO-90% H ₂ (c) In the case of TiCNO layer Temperature: 1000 ° C., pressure: 100 torr Reaction gas composition: 4% TiCl ₄ -3% CO-3% N ₂ −
90% H ₂ (d) Al ₂ O ₃ layer Temperature: 1000 ° C., Pressure: 100 torr, Reaction gas composition: 3% AlCl ₃ -5% CO ₂ -92% H
₂

The coated cutting tools 11 to 18 of the present invention thus produced were also subjected to a high-speed continuous cutting test under the same conditions as those of the high-speed continuous cutting test carried out in Example 1, and the results are shown in Table 4. ~ Shown in Table 5.

[0029]

[Table 4]

[0030]

[Table 5]

From the results shown in Tables 4 to 5, TiCO and Ti were further formed on the surfaces of the coated cutting tools 1 to 10 of the present invention.
Similarly, the coated cutting tools 11 to 18 of the present invention in which an upper layer composed of one single layer of N, TiCNO and Al ₂ O ₃ or an upper layer composed of two or more types of multilayers are also normal for cutting of ductile cast iron. It can be seen that it shows wear.

[0032]

From the results shown in Tables 2 to 5, Co:
4.0-7.0% by weight, carbides other than WC: 3.0% by weight or less, WC: average layer thickness consisting of a single layer of TiC or TiCN on the surface of a WC-based cemented carbide substrate consisting of the balance: 5
A cutting tool having a hard layer of ˜20 μm coated thereon,
The average grain size of WC contained in the WC-based cemented carbide substrate is in the range of 0.5 to 3 μm, and the average grain size of the crystal grains of the hard layer is in the range of 0.01 to 0.5 μm. Hard layer-coated WC-based cemented carbide cutting tool, and further, a hard layer formed on the surface of this substrate is used as a lower layer, and TiCO, TiCNO, TiN and Al ₂ O ₃ are formed on the lower layer.
The coated cutting tool of the present invention formed with a coating layer having an average layer thickness of 0.1 to 10 μm composed of an upper layer composed of a single layer or a plurality of layers of the present invention, is capable of cutting ductile cast iron for a long time. A comparative coated cutting tool which does not cause chipping and shows excellent cutting performance, but does not satisfy the conditions of the present invention,
It can be seen that chipping occurs in a short time and reaches the end of life.

Therefore, by using the hard layer-coated WC-based cemented carbide cutting tool of the present invention, it is possible to reduce the number of times of exchanging the cutting tool as compared with the conventional one, and it is possible to obtain an excellent industrial effect.

Claims (2)

[Claims] 1. Co: 4.0 to 7.0% by weight, carbides other than tungsten carbide: 3.0% by weight or less, tungsten carbide: Ti carbide on the surface of a tungsten carbide based cemented carbide substrate consisting of the balance. Alternatively, a cutting tool formed by coating a hard layer having an average layer thickness of 5 to 20 μm consisting of a single layer of carbonitride, wherein the tungsten carbide-based cemented carbide substrate has an average grain size of tungsten carbide of 0.5. The average grain size of the crystal grains of the hard layer is 0.01 to 0.5 μm.
A hard-layer-coated tungsten carbide based cemented carbide cutting tool characterized by being in the range of m. 2. The hard layer of the tungsten carbide based cemented carbide cutting tool coated with a hard layer according to claim 1, which is used as a lower layer, and titanium carbonate, titanium oxycarbonitride, titanium nitride and titanium nitride are formed on the surface of the lower layer. Average layer thickness consisting of one single layer or two or more multiple layers of aluminum oxide: 0.1 to 1
A hard-layer-coated tungsten carbide-based cemented carbide cutting tool, characterized by coating an upper layer of 0 μm.