JP2734311B2 - Surface coated titanium carbonitride based cermet cutting tool with excellent chipping resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention has excellent chipping resistance, and as a result, even when used for high-speed cutting of steel or cast iron, for example, the cutting edge is chipped (minute chipping).
The present invention relates to a surface coated titanium carbonitride (hereinafter, referred to as TiCN) -based cermet-based cutting tool exhibiting excellent wear resistance without generation of cracks.

[0002]

2. Description of the Related Art Conventionally, generally, for example, Japanese Patent Application Laid-Open No. 54-11 / 1979
As described in Japanese Patent No. 7510, a TiCN-based cermet substrate and a surface portion having a relatively high content of Co or Ni as a binder phase forming component as compared with the inside of the substrate, that is, a binder phase-enriched surface portion, are used. On the surface of a TiCN-based cermet substrate having, using a chemical vapor deposition method or a physical vapor deposition method, Ti carbide, nitride, carbonitride, carbon oxide, and carbonitride,
And aluminum oxide [hereinafter referred to as TiC and Ti, respectively.
N, TiCN, TiCO, TiCNO, and Al ₂ O
₃₎ , a surface-coated TiCN-based cermet made by forming a hard coating layer composed of one kind of single layer or two or more kinds of multilayers with an average layer thickness of 0.5 to 20 μm, for example, steel. It is well known that it is used for continuous cutting and interrupted cutting of steel and cast iron.

[0003]

On the other hand, in recent years, high performance of cutting machines and labor saving of cutting work have been remarkable, and cutting work tends to be accelerated year by year. If the base cermet cutting tool is used for high-speed cutting of steel or cast iron, for example, chipping is likely to occur on the cutting edge due to insufficient toughness of the hard coating layer,
Wear due to chipping progresses, and the service life is reached in a relatively short time.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
In view of the above, the above-mentioned conventional surface-coated TiCN-based cermet cutting tool was focused on, and as a result of researching to improve the chipping resistance of the cutting tool, as a result, for example, as a hard coating layer by, for example, a chemical vapor deposition method, In forming the TiCN layer, the reaction gas composition: TiCl ₄ : 1 to 5% by volume, CH
_{4: 5~7%, N 2:} 20~30%, H 2: remainder, reaction temperature: 950 to 1050 ° C., atmospheric pressure: 50 to 200 Torr, is performed in conditions, TiCN layer formed granular crystal Although it is normal to have a structure, the reaction gas composition is set to a relatively low reaction temperature by setting the TiCN layer formation conditions in the second half process, intermediate process, or first half process of forming the TiCN layer having the granular crystal structure to a relatively low reaction temperature. The changed conditions, ie, the reaction gas composition; in volume%, TiCl ₄ : 1 to 4%, CH
_{3 CN: 0.1~1%, N 2} : 0~25%, H 2: remainder, reaction temperature: 800 to 900 ° C., atmospheric pressure: 30 to 200 Torr, when the conditions, TiCN layers of the results ,Respectively,
(A) a crystal structure that changes from a granular crystal structure to a vertically elongated crystal structure, (b) a crystal structure from a granular crystal structure to a vertically elongated crystal structure,
Further, it has a crystal structure that changes from the vertically-grown crystal structure to a granular crystal structure, (c) a crystal structure that changes from the vertically-grown crystal structure to a granular crystal structure, and any one of the above (a) to (c). And the above-mentioned known TiC
Any one of the crystal structures (a) to (c) above as a lower layer of the hard coating layer on the surface of the N-based cermet substrate,
Alternatively, a TiCN layer composed of a single layer composed of a combination of two or more layers or a laminate of two or more layers is formed, and a normal condition (in this case, a granular crystal structure is obtained in any case) is formed on this lower layer. ), TiC, TiN, TiCN, Ti
The cutting tool made of a surface-coated TiCN-based cermet formed by forming as an upper layer a hard coating layer comprising a single layer of CO, TiCNO and Al ₂ O ₃ or a multilayer of two or more of the above-mentioned lower layer As a result, it became possible to obtain excellent chipping resistance, and obtained a research result that high wear resistance is exhibited over a long period of time in high-speed cutting of steel or cast iron.

The present invention has been made based on the above research results, and a hard coating layer is formed on the surface of a TiCN-based cermet substrate or a TiCN-based cermet substrate having a binder phase-enriched surface portion. In the cutting tool made of a surface-coated TiCN-based cermet formed with an average layer thickness of ２０20 μm, the hard coating layer is formed of a lower layer composed of a single layer of TiCN or a laminate of two or more layers, TiC, TiN, T
A single layer of iCN, TiCO, TiCNO, and Al ₂ O ₃ , or an upper layer composed of two or more layers, and all of the constituent layers of the lower layer are:
(A) a crystal structure that changes from a granular crystal structure to a vertically elongated crystal structure, (b) a crystal structure from a granular crystal structure to a vertically elongated crystal structure,
And (c) a crystal structure that changes from the vertically-grown crystal structure to a granular crystal structure, and any one of the above-mentioned (a) to (c). The present invention is characterized by a surface-coated TiCN-based cermet cutting tool having excellent chipping resistance.

In the cutting tool made of a surface-coated TiCN-based cermet according to the present invention, the average thickness of the hard coating layer is determined to be 0.5 to 20 μm because the thickness is 0.5 μm.
If the thickness is less than the above, the desired excellent wear resistance provided by the hard coating layer cannot be ensured. On the other hand, if the thickness exceeds 20 μm, chipping is likely to occur in the cutting edge.

[0007]

Next, a cutting tool made of a surface-coated TiCN-based cermet according to the present invention will be described in detail with reference to examples. As raw material powders, both TiCN powder having a predetermined average particle size in the range of 1 to 2 [mu] m, TiC powder, TiN powder, TaC powder, NbC powder, WC powder, Mo ₂ C powder, ZrC powder, Co powder, and Using Ni powder, these raw material powders were blended into the blending composition shown in Table 1, wet-mixed for 72 hours with a ball mill, dried, and then press-molded into a green compact. One part is vacuum-sintered at a predetermined temperature in the range of 1450 to 1500 ° C. for 1 hour in a vacuum of 10 ⁻² Torr to form a TiCN-based cermet substrate A having no binder phase-enriched surface portion To C, and the rest of the green compact is heated to 10 ⁻² torr in a vacuum atmosphere up to the sintering temperature.
After reaching a predetermined sintering temperature in the range of 450 to 1550 ° C., the atmosphere is maintained at 10 torr N ₂ atmosphere for 1 hour,
By subjecting the sintering to cooling from the sintering temperature in a vacuum of 10 ^-1 Torr, a TiCN-based cermet substrate having a binder phase-enriched surface portion having a maximum binder phase content and thickness also shown in Table 1 DF were manufactured respectively. The TiCN-based cermet substrates A to F obtained as a result all have a cutting tip shape of ISO • CNMG120408.

Next, the surface of each of the TiCN-based cermet substrates A to F is
The conditions for forming the granular crystal structure of N are as follows: reaction gas composition; volume%, TiCl ₃ : 3%, CH ₃ :
_{5%, N 2: 25%} , H 2: remainder, reaction temperature: 1020 ° C., atmospheric pressure: 100 Torr, and then, also the formation conditions of the longitudinal growth crystal structure of TiCN, the reaction gas composition; in volume%, TiCl ₄ : 1.5%, CH
₃ CN: 0.5%, N ₂ : 25%, H ₂ : residual, reaction temperature: 860 ° C., atmospheric pressure: 50 torr, and these forming conditions were appropriately changed during the formation of each constituent layer. A TiCN lower layer composed of a single layer or a laminate of two or more layers having the crystal structure shown in Table 2
Are formed with the average layer thickness shown in Table 2, and further have the composition and the average layer thickness shown in Table 2 under the normal conditions shown in Table 3 using the same ordinary chemical vapor deposition apparatus, and both have a granular crystal structure. By forming a covered upper layer, cutting tools made of a surface-coated TiCN-based cermet of the present invention (hereinafter, referred to as coated cutting tools of the present invention) 1 to 8 were produced.

Further, the hard coating layer having the composition and the average layer thickness shown in Table 4 on the surface of each of the TiCN-based cermet substrates A to F under the ordinary conditions also shown in Table 3 and having a granular crystal structure. , Cutting tools made of a conventional surface-coated TiCN-based cermet (hereinafter referred to as conventional coated cutting tools) 1 to 8 were respectively manufactured.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

[0014]

[Table 5]

[0015] Next, the resulting various coated cutting tool, work material: SCM440 (hardness: H _B 220), cutting speed:. 250 meters / min, Feed:. 0.2 mm / rev, cut : 1 mm, cutting time: dry high-speed cutting test of steel in 30 minutes, conditions as well as work material: FC30 (hardness: H _B 200), cutting speed:. 300 meters / min, feed: 0.2 mm / rev., depth of cut: 1 mm, cutting time: 30 minutes, a wet high-speed cutting test of cast iron was performed, and the flank wear width of the cutting edge was measured in each case. Table 5 shows the results of these measurements.

FIGS. 1 and 2 show longitudinal section micrographs (magnification: 5000 times) of the surface portions of the coated cutting tool 7 of the present invention and the conventional coated cutting tool 7 by a scanning electron microscope. As shown, in FIG. 1 (the coated cutting tool of the present invention), the hard coating layer formed on the surface of the substrate (the lower part of FIG. 1) has a crystal structure that changes from a granular crystal structure to a vertically grown crystal structure. A lower layer of a TiCN layer, and a granular crystal structure of TiN
In FIG. 2 (conventionally coated cutting tool 7), the hard coating layer formed on the surface of the substrate (the lower part in FIG. 2) is made of TiCN having a granular crystal structure.
It is shown that it is composed of a layer (first layer) and a TiN layer (second layer).

[0017]

According to the results shown in Tables 1 to 5 and FIGS. 1 and 2, a single layer or a laminate of two or more layers of TiCN constituting the lower layer of the hard coating layer was formed from a granular crystal structure and a vertically elongated crystal. The present invention coating having a crystal structure that changes into a structure, or a crystal structure that changes from a granular crystal structure to a vertically-grown crystal structure, further from this vertically-grown crystal structure to a granular crystal structure, or a crystal structure that changes from a vertically-grown crystal structure to a granular crystal structure. Since all of the cutting tools 1 to 8 have excellent chipping resistance due to the above crystal structure,
Particularly when used for high-speed cutting of steel or cast iron requiring chipping resistance, it is superior to conventional coated cutting tools 1 to 8 which form a hard coating layer composed of a TiCN layer having a granular crystal structure. It is clear that it shows wear resistance.

As mentioned above, the surface-coated TiC of the present invention
N-base cermet cutting tools exhibit excellent wear resistance when used for high-speed cutting of steel or cast iron, for example, which requires chipping resistance, and exhibits excellent cutting performance over a long period of time. It is.

[Brief description of the drawings]

FIG. 1 is a vertical section micrograph of the surface of a coated cutting tool 7 of the present invention, taken by a scanning electron microscope.

FIG. 2 is a longitudinal section micrograph of the surface of a conventional coated cutting tool 7 taken by a scanning electron microscope.

Claims (2)

(57) [Claims] 1. A cutting tool made of a surface-coated titanium carbonitride-based cermet, wherein a hard coating layer is formed on the surface of a titanium carbonitride-based cermet substrate with an average layer thickness of 0.5 to 20 μm. , A lower layer composed of a single layer of titanium carbonitride or a laminate of two or more layers, and a single layer of one of carbides, nitrides, carbonitrides, carbonates, and carbonitrides of Ti, and aluminum oxide Alternatively, each of the constituent layers of the lower layer is composed of (a) a crystal structure that changes from a granular crystal structure to a vertically elongated crystal structure, and (b) a crystal structure that changes from a granular crystal structure. (C) a crystal structure that changes from a vertically-grown crystal structure to a granular crystal structure; and (c) a crystal structure that changes from a vertically-grown crystal structure to a granular crystal structure. Crystal Surface coating the titanium carbonitride based cermet cutting tool having excellent chipping resistance that wherein a granulation. 2. A hard coating layer having an average layer thickness of 0.5 to 20 μm is formed on the surface of a titanium carbonitride-based cermet substrate having a surface portion in which the content of a binder phase forming component is relatively high as compared with the inside of the substrate. A surface-coated titanium carbonitride-based cermet cutting tool formed of: a hard coating layer comprising: a lower layer comprising a single layer or two or more layers of titanium carbonitride; and a carbide, nitride, or carbonitride of Ti. , Carbon oxides, carbonitrides, and aluminum oxide, each of which is composed of an upper layer composed of a single layer or two or more layers. (a) a crystal structure that changes from a granular crystal structure to a vertically-grown crystal structure; (b) a crystal structure that changes from a granular crystal structure to a vertically-grown crystal structure, and further from this vertically-grown crystal structure to a granular crystal structure; (c) a vertically-grown crystal structure From granular A cutting tool made of a surface-coated titanium carbonitride-based cermet having excellent chipping resistance, having a crystal structure that changes to a crystal structure, and having any one of the above-mentioned crystal structures (a) to (c).