JPH0929511A - Cutting tool made of surface-coated tungsten carbide grouped hard metal wherein hard coating layer has excellent chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool made of surface-coated hard metal wherein a hard coating layer has excellent chipping resistance. SOLUTION: An Al2 O3 layer is given an average layer thickness of 1 to 15μm and a middle part of the Al2 O3 layer is caused to contain Si at a rate of 1 to 20weight% so as to cover a layer thickness range equivalent to 10 to 70% of the average layer thickness of the Al2 O3 layer, in the case of a cutting tool made of surface-coated hard metal comprizing a hard coating layer which is formed, over a surface of a hard metal base body, so as to have an average layer thickness of 2 to 20μm and composed of a Ti-compound layer constituting of a single layer of one kind or a plurality of layers of more than two kinds among TiC, TiN, TiCN, TiCO, TiNO, and TiCNO, and an Al2 O3 layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard coating layer having excellent fracture resistance, and therefore, when it is used for high-speed wet interrupted cutting of steel, for example, where a large mechanical thermal shock is applied to a cutting edge. Also, the cutting edge is chipped or chipped (small chip)
The present invention relates to a surface-coated tungsten carbide-based cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide cutting tool) that exhibits excellent wear resistance for a long period of time without occurrence of the above.

[0002]

2. Description of the Related Art Conventionally, a coated carbide cutting tool has been generally used for continuous cutting or intermittent cutting of steel or the like. Further, the above-mentioned coated carbide cutting tool is, for example, as described in Japanese Patent Publication No. 57-1585 and Japanese Patent Publication No. 59-52703,
A tungsten carbide-based cemented carbide substrate that is homogeneous throughout, and a surface portion in which the content of Co, etc., as a binder phase forming component is relatively high compared to the inside of the substrate, that is, the surface portion has a binder phase enriched zone. On the surface of a tungsten carbide-based cemented carbide substrate (hereinafter collectively referred to as cemented carbide substrate),
Using chemical vapor deposition or physical vapor deposition, Ti carbide, nitride, carbonitride, carbon oxide, oxynitride, and oxycarbonitride (hereinafter, respectively, TiC, TiN, TiCN, TiC
O, TiNO, and TiCNO), which is a hard layer composed of a Ti compound layer composed of one single layer or two or more multi-layers, and an Al oxide (hereinafter, Al ₂ O ₃ ) layer. It is known that the coating layer is formed with an average layer thickness of 5 to 20 μm.

[0003]

On the other hand, in recent years, there has been a strong demand for labor saving and energy saving of the cutting process, and accordingly, the cutting process tends to be speeded up. However, the conventional coated carbide cutting tool described above is used. Is used for wet intermittent high-speed cutting of steel or the like, which has a large mechanical thermal impact on the cutting edge, because the Al ₂ O ₃ layer constituting the hard coating layer does not have sufficient fracture resistance. Moreover, due to this, the cutting edge is liable to be chipped or chipped, and the service life is reached in a relatively short time.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoints, the above-mentioned conventional coated carbide cutting tool was focused on, and as a result of research to improve the fracture resistance of the Al ₂ O ₃ layer constituting the hard coated layer of the conventional coated carbide cutting tool, the above-mentioned conventional coated Al ₂ O ₃ that constitutes the hard coating layer of the carbide cutting tool
When Si is contained in the central portion of the layer over a predetermined thickness, the resulting Si portion-containing Al ₂ O ₃ layer has the above-mentioned S content.
The i-containing central portion has excellent fracture resistance, and the upper and lower portions substantially composed of Al ₂ O ₃ ensure excellent wear resistance and heat resistance, so that it is hard. The fracture resistance of the entire coating layer is improved without lowering the wear resistance, and the resulting coated carbide cutting tool exerts excellent fracture resistance for a long period of time even in machining with a large mechanical thermal shock. I got the research results.

The present invention has been made based on the above-mentioned research results, and Ti is formed on the surface of a cemented carbide substrate.
C, TiN, TiCN, TiCO, TiNO, and T
A coated carbide formed by forming a hard coating layer composed of a Ti compound layer composed of one single layer or two or more multilayers of iCNO and an Al ₂ O ₃ layer with an average layer thickness of 5 to 20 μm. In a cutting tool, Al ₂ O ₃ constituting the hard coating layer
The average layer thickness of the layer is 1 to 15 μm, and the Al ₂ O _{3 is used.}
In the central part of the layer, the average layer thickness of the Al ₂ O ₃ layer is 10 to 10
It is characterized by a coated carbide cutting tool having an excellent fracture resistance in which a hard coating layer is formed by containing Si in a proportion of 1 to 20% by weight over a layer thickness corresponding to 70%.

In the coated carbide cutting tool of the present invention, the above-mentioned Si portion-containing Al ₂ O ₃ constituting the hard coating layer is formed.
The Si-containing central portion of the layer is formed by a conventional chemical vapor deposition apparatus or a physical vapor deposition apparatus in a reaction gas composition: volume%, Al
_{Cl 3: 1~20%, CO 2} : 0.5~30%, SiC
l ₄ : 0.001-0.2%, HCl: 1 if necessary
20% and / or H ₂ S: 0.05~5%,
H ₂ : remaining, reaction temperature: 850 to 1050 ° C., atmospheric pressure: 30 to 200 torr
In this case, if the Si content ratio is less than 1% by weight, the desired effect of improving the fracture resistance cannot be obtained, while the Si content ratio is 2% or less.
If it exceeds 0% by weight, the wear resistance will decrease, so the Si content is 1 to 20% by weight, preferably 5%.
Need to be up to 12% by weight. Further, the Ti compound layer constituting the hard coating layer is formed under normal conditions by a chemical vapor deposition method and / or a physical vapor deposition method.
When the N layer is used, the first
In some cases, the C component that constitutes the cemented carbide substrate may diffuse and form a solid solution in the TiN layer of the layer, and in this case, the first layer partially or wholly consists of TiCN. further,
The average layer thickness of the hard coating layer is set to 5 to 20 μm because the desired excellent wear resistance cannot be secured when the average layer thickness is less than 5 μm, and when the average layer thickness exceeds 20 μm. This is because the cutting edge is likely to be chipped or chipped, and the Si portion-containing Al ₂
The average layer thickness of the O ₃ layer is set to 1 to 15 μm as described above. This means that when the average layer thickness is less than 1 μm, S
The layer thickness of the i-containing central portion is less than 10% of this, that is, less than 0.1 μm, and it becomes impossible to secure the desired excellent fracture resistance, while when the average layer thickness exceeds 15 μm. In some cases, the layer thickness of the Si-containing central portion exceeds 10.5 μm, which corresponds to 70% of the thickness, and in this case, the wear resistance is unavoidably deteriorated. Partially containing Al ₂ O
The average layer thickness of the _three layers is 5 to 10 μm, and the layer thickness of the Si-containing central portion is preferably 30 to 50% in terms of the ratio to the average layer thickness of the Si portion-containing Al ₂ O ₃ layer. In addition, the TiCN layer of the Ti compound layer constituting the hard coating layer,
For example, assuming that the vertically elongated crystal structure described in JP-A-6-8010 is used, TiC having a normal granular crystal structure.
The cutting performance is much better than that of the N layer.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the coated carbide cutting tool of the present invention will be specifically described by way of Examples. As a raw material powder, a medium-grain WC powder having an average particle diameter of 3 μm, the same as 5 μm
Coarse-grained WC powder, 1.5 μm (Ti, W) C (weight ratio, the same below, TiC / WC = 30/70) powder, 1.2 μm (Ti, W) CN (TiC / TiN) / WC
= 24/20/56) powder, the same 1.3 μm (Ta, N
b) C (TaC / NbC = 90/10) powder and 1.2 μm Co powder were prepared.
And wet-mixed with a ball mill for 72 hours, dried, and then subjected to ISO • CNMG120408.
(For cemented carbide base bodies A to D) and the same SEEN42AFT
N1 (for cemented carbide substrate E) was press-molded into a powder compact having a shape determined, and the powder compact was vacuum-sintered under the conditions shown in Table 1 to manufacture cemented carbide substrates A to E, respectively. . Further, with respect to the cemented carbide base material B, 100 torr of CH
_{In a 4} gas atmosphere, the temperature is maintained at 1400 ° C for 1 hour, and then a gradual cooling carburizing treatment is performed. After the carburizing treatment, carbon and Co adhering to the substrate surface are removed by acid and barrel polishing to a depth of 11 μm from the surface. Maximum Co content at position: 1
A Co-enriched zone showing 5.3 wt% and having a depth of 22 μm was formed on the surface of the substrate. In addition, the cemented carbide base A
In and D, as-sintered, a Co-rich zone having a maximum Co content of 9.2 wt% at a depth of 16 μm from the surface and a depth of 22 μm was formed on the surface of the substrate. The remaining cemented carbide substrates C and E contain the Co
There was no formation of enriched zones and the whole had a homogeneous structure. Further, Table 1 shows the internal hardness (Rockwell hardness A scale) of each of the cemented carbide substrates AE.

Then, the surfaces of these cemented carbide substrates A to E were subjected to honing, using a conventional chemical vapor deposition apparatus, under the conditions shown in Table 2 under the conditions shown in Table 2 and the compositions shown in Tables 3 and 4. The coated carbide cutting tools 1 to 10 of the present invention and the conventional coated carbide cutting tools 1 to 10 were manufactured by forming a hard coating layer having an average layer thickness.

Next, the above-mentioned coated carbide cutting tool 1 of the present invention.
~ 8 and conventional coated carbide cutting tools 1-8, work material: round bar of SCM440, cutting speed: 355 m / min.,
Cut: 2.5 mm, Feed: 0.28 mm / re
v., Cutting time: 20 minutes, wet continuous cutting test of steel, Work material: SCM440 square bar, Cutting speed: 230 m
/ Min., Depth of cut: 1.5 mm, feed: 0.23
mm / rev., cutting time: 30 minutes, a wet intermittent high-speed cutting test of steel was performed, and the flank wear width of the cutting edge was measured in each cutting test. Further, regarding the coated carbide cutting tools 9 and 10 of the present invention and the conventional coated carbide cutting tools 9 and 10, the work material is a square material of SCM440, the cutting speed is 355 m.
/ Min., Depth of cut: 2.5 mm, feed: 0.28
mm wet / milling, cutting time: 30 minutes, a wet milling high-speed cutting test of steel was performed, and the flank wear width of the cutting edge was similarly measured. Table 5 shows the results of these measurements.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

[0014]

[Table 5]

[0015]

From the results shown in Tables 3 to 5, the coated carbide cutting tools 1 to 10 of the present invention are all Al containing Si portion.
_{Since the} hard coating layer has excellent fracture resistance due to the Si-containing central portion in the ₂ O ₃ layer, not only dry continuous cutting but also wet intermittent high speed cutting of steel with particularly large mechanical thermal shock is achieved. While the blade exhibits excellent wear resistance without chipping or chipping, in the conventional coated carbide cutting tools 1-10, the Al ₂ O ₃ layer constituting the hard coating layer causes the above It is clear that in the wet intermittent high-speed cutting, the cutting edge is chipped or chipped, and the service life is reached in a relatively short time. As described above, in the coated carbide cutting tool of the present invention, since the hard coating layer has excellent fracture resistance, not only ordinary continuous cutting and interrupted cutting, but particularly wet interrupted with a large mechanical thermal shock. It exhibits excellent fracture resistance even at high-speed cutting, and exhibits excellent cutting performance over a long period of time.

Claims (1)

[Claims] 1. A Ti carbide, a nitride, a carbonitride on the surface of a tungsten carbide-based cemented carbide substrate which is wholly homogeneous, or a tungsten carbide-based cemented carbide substrate which has a binder phase enriched zone on the surface. A hard coating layer composed of a Ti compound layer and an Al oxide layer, which is composed of a single layer of carbon oxide, a nitrogen oxide, and a multi-layer of two or more of carbon monoxide, 5
In the surface-coated tungsten carbide based cemented carbide cutting tool formed with an average layer thickness of ˜20 μm, the average layer thickness of the Al oxide layer constituting the hard coating layer is 1
˜15 μm, and in the central part of the Al oxide layer,
The hard coating layer is characterized by containing Si in an amount of 1 to 20% by weight over a layer thickness corresponding to 10 to 70% of the average layer thickness of the Al oxide layer. A surface-coated tungsten carbide based cemented carbide cutting tool.