JP2000158208A - Surface-covering tungsten carbide group cemented carbide alloy cutting tool having its hard covering layer exhibit excellent chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-covering cemented carbide alloy cutting tool having a hard cover layer exhibiting excellent chipping resistance. SOLUTION: This surface-covering cemented carbide alloy cutting tool is composed of a tungsten carbide group body having an outer surface which is covered by chemical or physical vapor deposition with a hard covering layer having a thickness of 5 to 25 μm in total average and composed of a Ti compound layer consisting of at least one selected from the group consisting of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, TiNO layer and a TiCON layer, which are all having a thickness of 0.1 to 5 μm in average, a TiCN layer having a thickness of 0.5 to 10 μm in average and having a longitudinally grown crystal structure, an Al2O2 layer having a thickness of 2 to 10 μm in average and having a longitudinally grown crystal structure, and a TiC layer having a thickness of 2 to 10 μm and having a longitudinally grown crystal structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for forming a hard coating layer by using a titanium nitride (hereinafter, referred to as l-TiN) layer having a vertically elongated crystal structure as a hard coating layer. This refers to a surface-coated cemented carbide cutting tool that demonstrates excellent chipping resistance without chipping or chipping (small chipping) of the cutting edge even under heavy cutting conditions (hereinafter referred to as coated carbide tool). is there.

[0002]

2. Description of the Related Art Conventionally, a tungsten carbide-based cemented carbide substrate (hereinafter referred to as a cemented carbide substrate) generally has (a)
Each of which has an average layer thickness of 0.1 to 5 μm and a granular crystal structure, a titanium carbide (hereinafter referred to as TiC) layer, a titanium nitride (hereinafter also referred to as TiN) layer, and a titanium carbonitride (hereinafter referred to as TiCN). ) Layer, titanium carbonate (hereinafter, T
(b) a Ti compound layer comprising one or more of an iCO) layer, a titanium oxynitride (hereinafter, shown as TiNO) layer, and a titanium carbonitride (hereinafter, shown as TiCNO) layer; A titanium carbonitride (hereinafter referred to as 1-TiCN) layer having an average layer thickness of 2 to 15 μm and a vertically grown crystal structure; and (c) an aluminum oxide having an average layer thickness of 0.5 to 10 μm and a granular crystal structure ( Hereinafter, Al
₂ O ₃ ) layer and ₅ to ₂ hard coating layers.
A coated carbide tool formed by chemical vapor deposition and / or physical vapor deposition with a total average layer thickness of 5 μm is known, and it is also known that this coated carbide tool is used for continuous or interrupted cutting of steel, cast iron, and the like. Have been. It is also well known that, generally, those having an α-type crystal structure, those having a κ-type crystal structure, and the like are widely and practically used as the Al ₂ O ₃ layer constituting the hard coating layer of the coated carbide tool. Further, the above-mentioned 1-TiCN layer is known, for example, from JP-A-6-8010 and JP-A-7-328808.
It is formed by performing chemical vapor deposition in a normal chemical vapor deposition apparatus at a medium temperature range of 700 to 950 ° C. using a mixed gas containing an organic carbonitride as a reaction gas.

[0003]

On the other hand, in recent years, there has been a strong demand for labor saving and energy saving for cutting work, and accordingly, cutting work has been carried out, for example, by increasing the depth of cut and feed in the cutting conditions to improve the cutting efficiency. There is a tendency for heavy cutting to be improved, but when the above-mentioned conventional coated carbide tool is used under heavy cutting conditions, chipping or chipping is likely to occur on the cutting edge due to insufficient toughness of the hard coating layer especially in interrupted cutting. The service life can be reached in a relatively short time.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoints, attention was paid to the hard coating layer of the conventional coated carbide tool, and as a result of researching to further improve the fracture resistance, the hard coating layer of the conventional coated carbide tool was obtained. Further, an l-TiN layer, that is, the above-described l-TiC
N layer, fracture surface structure and optical microscope structure are substantially the same T
When the iN layer is added as a constituent layer, the 1-TiN layer becomes
Since the vertically-grown crystal structure has a higher toughness than that of the granular crystal structure, the resulting coated carbide tool has a superior hard coating layer due to the 1-TiN layer even when the interrupted cutting is performed under heavy cutting conditions. As a result, it has been found that there is no chipping or chipping of the cutting edge, and that excellent cutting performance is exhibited over a long period of time.

The present invention has been made on the basis of the above-mentioned research results, and is based on the following facts: (a) TiC having an average layer thickness of 0.1 to 5 μm and a granular crystal structure Layer, TiN layer, TiCN layer, TiCO layer,
One or two of a TiNO layer and a TiCNO layer
A Ti compound layer comprising at least one species, and (b) 2 to 15 μm
An l-TiCN layer having an average layer thickness of (c) 0.5 to 10
Al ₂ O ₃ with average layer thickness of μm and granular crystal structure
Hard coating formed by chemical vapor deposition and / or physical vapor deposition of a hard coating layer composed of a layer and (d) an l-TiN layer having an average layer thickness of 2 to 10 μm with an overall average layer thickness of 5 to 25 μm. It is characterized by a coated carbide tool having a layer exhibiting excellent wear resistance.

The hard coating of the coated carbide tool of the present invention
The l-TiN layer constituting the layer has a composition of the reaction gas: volume%
And TiCl_Four : 0.2-1%, N_Two: 5-10%, H
_Two : Remaining reaction atmosphere temperature: 1000 to 1100 ° C., reaction atmosphere pressure: 400 to 600 Torr.
The conditions for forming the N layer are as follows.
_Four : 2 to 10%, N_Two: 20-40%, H _Two : Remaining temperature of reaction atmosphere: 900 to 1050 ° C., pressure of reaction atmosphere: 50 to 300 Torr.
Concentration of the TiN forming component in the reaction gas as compared with that of
The temperature is relatively low and the reaction atmosphere pressure is high.

Further, the average layer thickness of the constituent layers in the hard coating layer of the coated carbide tool of the present invention is determined for the following reasons. That is, each of the Ti compound layers has a function of improving interlayer adhesion between constituent layers as a common property, and therefore, the average layer thickness is 0.1%.
If the average layer thickness is less than 5 μm, the desired average layer thickness cannot be ensured. On the other hand, if the average layer thickness exceeds 5 μm, chipping and chipping are likely to occur on the cutting edge. 0.1-5 μm. Also, Al ₂ O ₃
The layer has the function of improving the wear resistance of the hard coating layer, but if the average layer thickness is less than 0.5 μm, the desired excellent wear resistance cannot be secured. Exceeds 10 μm, chipping is likely to occur on the cutting edge. Therefore, the average layer thickness is set to 0.5 to 10 μm. Further, the l-TiCN layer has an effect of further improving the fracture resistance of the hard coating layer due to its own high toughness. If the average layer thickness is less than 2 μm, the desired effect of improving the fracture resistance is obtained. The average layer thickness is 15 μm
If the average thickness exceeds 2 mm, the abrasion resistance rapidly decreases. Therefore, the average layer thickness is set to 2 to 15 μm. Further, the l-TiN layer improves the fracture resistance of the hard coating layer due to its high toughness as described above, so that the coated carbide tool can be used to perform intermittent cutting under heavy cutting conditions. The blade has the effect of suppressing chipping and chipping. However, if the average layer thickness is less than 2 μm, the desired effect cannot be obtained. If the average layer thickness exceeds 10 μm, wear will occur. The average layer thickness was determined to be 2 to 10 μm because the progress of the process was rapidly accelerated. In addition, the reason why the total average layer thickness of the hard coating layer is set to 5 to 25 μm is that if the average layer thickness is less than 5 μm, the desired wear resistance cannot be secured, while the average layer thickness exceeds 25 μm. This is because the chipping and chipping of the cutting edge are likely to occur.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a coated carbide tool of the present invention
Will be specifically described with reference to examples. As raw material powder,
A WC powder having an average particle diameter of 0.5 to 5 μm;
(Ti, W) C (weight ratio, hereinafter the same, TiC / WC =
50/50) powder, (Ti, W) CN (by weight,
Same, TiC / TiN / WC = 24/20/56) powder
End, (Ta, Nb) C (TaC / NbC = 90/10)
Powder, Cr_ThreeC_TwoPrepare powder and Co powder,
The raw material powder is blended into the blending composition shown in Table 1,
After wet mixing in a mill for 72 hours and drying, this mixed powder
Is a pressure of a shape conforming to ISO standard SCNMG120408.
Press molding into a powder ^-2true of torr
A predetermined temperature in the range of 1350 to 1500 ° C. in an air atmosphere
Vacuum sintering for one hour at a time
The bodies A to E were manufactured respectively. In addition, the above-mentioned super-hard substrates A to
In C, as it is sintered, the surface part
Over a depth of 20 μm,
Co-enriched layer (strong
Toughness layer), and the remaining cemented carbide substrates D and E
No Co-enriched layer is formed and the overall structure is uniform
Was something.

[0009] Then, the surface of each of these superhard substrates A to E is subjected to honing processing, and is subjected to the composition shown in Tables 3 and 4 under the conditions shown in Table 2 using an ordinary chemical vapor deposition apparatus. Forming a hard coating layer having a target layer thickness (a flank of a cutting edge) so that the hard coating layer has an l-TiN layer as a constituent layer;
Conventional coated carbide tools 1 to 10 having no iN layer were manufactured. The thickness of the constituent layers of the hard coating layer of the various coated carbide tools obtained as a result was measured using an optical microscope. As a result, the thickness was substantially equal to the target layer thickness shown in Tables 3 and 4. The same average layer thickness was shown.

Next, the coated carbide tools 1 to 10 according to the present invention will be described.
And the conventional coated carbide tools 1 to 10; Work material: JIS SCM440 lengthwise round bar with four longitudinal grooves, Cutting speed: 100 m / min. Infeed: 5.0 mm Feed: 0.3 mm / rev. , Cutting time: 15 minutes, Dry high-incision intermittent cutting test of alloy steel under the following conditions: Work material: JIS SCM439 Round bar with four longitudinal grooves at regular intervals in the longitudinal direction, Cutting speed: 100 m / min . Infeed: 2.5 mm Feed: 0.45 mm / rev. , Cutting time: 15 minutes, Dry high-feed intermittent cutting test of alloy steel was performed under the following conditions, and the maximum flank wear width of the cutting edge was measured in each cutting test. Table 5 shows the measurement results.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

[Table 4]

[0015]

[Table 5]

[0016]

From the results shown in Tables 3 to 5, the coated carbide tools 1 to 10 of the present invention in which the l-TiN layer is present as a constituent layer in the hard coating layer are all hardened by the l-TiN layer. Since the coating layer has high toughness,
Even in intermittent cutting under heavy cutting conditions where fracture resistance is required, the cutting edge exhibits excellent wear resistance without chipping or chipping, whereas the l-TiN layer does not exist in the hard coating layer. In conventional coated carbide tools 1 to 10, in interrupted cutting under heavy cutting conditions, the cutting edge is chipped or chipped due to insufficient toughness of the hard coating layer, resulting in a relatively short service life. Is evident. As mentioned above,
The coated cemented carbide tool of the present invention exhibits excellent chipping resistance, not only when performing continuous cutting or interrupted cutting under ordinary conditions such as steel or cast iron, but also especially when performing interrupted cutting under heavy cutting conditions. In addition, since excellent cutting performance is exhibited over a long period of time, it can sufficiently cope with labor saving and energy saving of cutting.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuhiro Kono 1511 Furamagi, Ishishita-cho, Yuki-gun, Ibaraki Pref. BA18 BB01 BB02 BC01 CA13 CA14

Claims (1)

[Claims] 1. A surface of a tungsten carbide-based cemented carbide substrate, comprising: (a) a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, each having an average layer thickness of 0.1 to 5 μm and a granular crystal structure; A Ti compound layer comprising one or more of a titanium carbonate layer, a titanium oxynitride layer, and a titanium carbonitride oxide layer; and (b) a carbon having an average layer thickness of 2 to 15 μm and a vertically elongated crystal structure. A titanium nitride layer, (c) an aluminum oxide layer having an average layer thickness of 0.5 to 10 μm and a granular crystal structure, and (d) a titanium nitride layer having an average layer thickness of 2 to 10 μm and a vertically grown crystal structure. And a hard coating layer formed by chemical vapor deposition and / or physical vapor deposition with a total average layer thickness of 5 to 25 μm. Alloy cutting tool.