JP3052586B2 - Surface-coated tungsten carbide based cemented carbide 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 therefore, has excellent wear resistance not only in continuous cutting of steel or cast iron, but also in intermittent cutting of these. The present invention relates to a surface-coated tungsten carbide (hereinafter, referred to as WC) based cemented carbide cutting tool.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Application Laid-Open No.
As described in JP-A-85-85 and JP-A-59-52703, the surface of a WC-based cemented carbide substrate or a surface in which the content of Co as a binder phase forming component is relatively large as compared with the inside of the substrate. Parts, that is, the carbide, nitride, carbonitride, carbonate, and carbonitride of Ti on the surface of the WC-based cemented carbide substrate having the Co-enriched surface by chemical vapor deposition or physical vapor deposition. , And aluminum oxide (hereinafter, TiC, TiN, TiCN, TiCO, TiCNO,
And Al ₂ O ₃ ).
A surface-coated WC-based cemented carbide cutting tool formed by forming a hard coating layer composed of at least two or more layers with an average layer thickness of 0.5 to 20 μm is used for continuous cutting of steel or cast iron, for example. Is well known.

In addition, WC having the above Co-enriched surface portion
The base cemented carbide base is compounded with, for example, a nitride powder such as TiN or a carbonitride powder such as TaCN and (Ti, W) CN as a raw material powder, and vacuum-sinters the compact under normal conditions. It is also known to be manufactured by a method such as

[0004]

On the other hand, in recent years, the FA technology and diversification of the cutting technology have been remarkable, and the resulting cutting tools exhibit excellent wear resistance both in continuous cutting and intermittent cutting. However, the conventional surface-coated WC-based cemented carbide cutting tool described above is susceptible to chipping of the cutting edge when used for interrupted cutting, and has a relatively short service life. At present.

[0005]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoint, the above-mentioned conventional surface-coated WC-based hard metal cutting tool has been focused on, and as a result of researching to improve the chipping resistance of the cutting tool, generally, for example, a hard coating layer is formed by a chemical vapor deposition method. When forming the TiCN layer as a reaction gas composition: volume%, TiCl ₄ : 1 to 5%, CH
_{4: 5~7%, N 2:} 20~30%, H 2: remainder, reaction temperature: 950 to 1050 ° C., atmospheric pressure: 50 to 200 Torr, is formed by the 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, that is, the reaction gas composition: by volume%, TiCl ₄ : 1 to 4%, CH
_{Under the conditions of 3} CN: 0.1 to 1%, N ₂ : 0 to 25%, H ₂ : residual, reaction temperature: 800 to 900 ° C., and atmospheric pressure: 30 to 200 torr, the resulting TiCN layer becomes (A) the lower side is a granular crystal structure, the upper side is a vertically elongated crystal structure , (b) the lower side is a granular crystal structure, the middle is a vertically elongated crystal structure,
The upper side has a granular crystal structure , (c) the lower side has a vertically-grown crystal structure, the upper side has a granular crystal structure , and any one of the above-mentioned (a) to (c) has a layer structure. (A) to (c) as a lower layer of the hard coating layer on the surface of the base cemented carbide substrate
Composed of a single layer composed of any one of the above-mentioned layer structures or a combination of two or more layers or a laminate of two or more layers
A TiC, TiC layer is formed under normal conditions (in this case, each having a granular crystal structure) on this lower layer.
N, TiCN, TiCO, TiCNO, and Al ₂ O
_The cutting tool made of a surface-coated WC-based cemented carbide formed by forming a hard coating layer consisting of one kind of single layer or two or more kinds of layers out of _{three as} an upper layer has excellent chipping resistance due to the lower layer. Research results have shown that, for example, not only continuous cutting of steel or cast iron, but also these interrupted cuts, which require chipping resistance, exhibit excellent wear resistance over a long period of time. It is.

The present invention has been made based on the results of the above-mentioned research, and is based on a WC-based cemented carbide substrate,
o A surface-coated WC-based cemented carbide cutting tool comprising a hard coating layer formed on the surface of a WC-based cemented carbide substrate having an enriched surface portion with an average layer thickness of 0.5 to 20 µm. The layers are a lower layer composed of a single layer of TiCN or a laminate of two or more layers, and TiC, TiN, TiCN, TiCO, T
iCNO and an upper layer composed of a single layer or two or more layers of Al ₂ O ₃ , and each of the lower layers is composed of: (a) a granular crystal structure on the lower side; The upper side is a vertically grown crystal structure , (b) the lower side is a granular crystal structure, the middle is a vertically elongated crystal structure,
The upper side has a granular crystal structure , (c) the lower side has a vertically-grown crystal structure, the upper side has a granular crystal structure , and any one of the above (a) to (c) has a layer structure.
The present invention is characterized by a surface-coated WC-based cemented carbide cutting tool having excellent chipping resistance.

In the cutting tool made of a surface-coated WC-base cemented carbide according to the present invention, the average thickness of the hard coating layer is set to 0.5 to 0.5.
The reason for setting the thickness to 20 μm is that when the layer thickness is less than 0.5 μm,
This is because the desired excellent abrasion resistance provided by the hard coating layer cannot be ensured, while if the layer thickness exceeds 20 μm, the cutting edge tends to be chipped.

[0008]

Next, a cutting tool made of a surface-coated WC-based cemented carbide according to the present invention will be described in detail with reference to examples. WC powder having an average particle size of 3 μm as raw material powder;
μm (Ti, W) C powder (TiC / WC = 3 by weight ratio)
0/70), 1.2 μm (Ti, W) CN powder (T
iC / TiN / WC = 24/20/56 by weight), 1.3 μm (Ta, Nb) C powder (TaC / NbC =
Weight ratio 90/10), and the same 1.2 μm Co powder were prepared, and these raw material powders were blended in the blending composition shown in Table 1, wet-mixed in a ball mill for 72 hours, and dried.
It is pressed into a green compact and then this green compact is 1 × 10
Vacuum sintering at a temperature of 1450 ° C. for 1 hour in a vacuum of ⁻² Torr to obtain ISO / CNMG12040
8, WC-based cemented carbide substrates A to C and C
oEnriched surface (maximum Co content: 11% by weight, thickness: 2
WC-based cemented carbide substrate D having a thickness of 0 μm). The WC-based cemented carbide substrate C was added to a 100 Torr methane gas atmosphere at a temperature of 1400.
Carburizing treatment at 1 ° C for 1 hour
Enriched surface (maximum Co content: 17% by weight, thickness: 40
μm).

Then, these WC-based cemented carbide substrates A to
Using a conventional chemical vapor deposition apparatus, the conditions for forming a granular crystal structure of TiCN on the surface of D were as follows: reaction gas composition: volume%, TiCl ₄ : 3%, CH ₄ :
_{5%, N 2: 25%} , H 2: remainder, reaction temperature: 950 ° C., atmospheric pressure: 100 Torr, and then, also the formation conditions of the longitudinal growth crystal structure of TiCN, the reaction gas composition: by 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 formation conditions were appropriately changed during the formation of each constituent layer. TiCN of single layer or two or more layers laminated with a layer structure <br/> Concrete shown in Table 2
The lower layer is also formed with the average layer thickness shown in Table 2, and also has the composition and average layer thickness shown in Table 2 under the usual conditions shown in Table 3 using a conventional chemical vapor deposition apparatus, Further, cutting tools made of a surface-coated WC-based cemented carbide of the present invention (hereinafter, referred to as coated cutting tools of the present invention) 1 to 8 were produced by forming an upper layer having a granular crystal structure.

Further, the WC-based cemented carbide substrates A to D have the composition and the average layer thickness shown in Table 4 under the ordinary conditions also shown in Table 3 and have a granular crystal structure. Conventional surface coating WC by forming a coating layer
Base cemented carbide cutting tools (hereinafter referred to as conventional coated cutting tools) 1 to 8 were manufactured, respectively.

[0011]

[Table 1]

[0012]

[Table 1]

[0013]

[Table 3]

[0014]

[Table 4]

[0015]

[Table 5]

[0016] Next, the resulting various coated cutting tool, work material: SNCM439 (Hardness: H _B 250) round bar, Cutting speed:. 180 m / min, Feed: 0.2 mm / rev A dry continuous cutting test of steel was performed under the following conditions: cutting depth: 1.5 mm, cutting time: 30 minutes, flank wear width of the cutting edge was measured, and work material: SNCM439 (hardness: H _B No. 260), a cutting speed: 100 m / min., A feed: 0.35 mm / rev., A cutting depth: 3 mm, a dry intermittent cutting test of steel was performed, and a cutting time until a service life was measured. Table 5 shows the measurement results.
It was shown to.

FIGS. 1 and 2 show longitudinal microstructure photographs (magnification: 7000 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 7 of the present invention), a hard coating layer formed on the surface of the substrate (the lower part of FIG. 1) has a granular crystal structure on the lower side and a vertically grown crystal structure on the upper side.
A lower layer of a TiCN layer having a layer structure, a TiCNO layer (first layer) having a granular crystal structure, an Al ₂ O ₃ layer (second layer) having a granular crystal structure, a TiCN layer (third layer) having a granular crystal structure, And a top layer composed of a TiN layer (fourth layer) having a granular crystal structure, and FIG. 2 (conventionally coated cutting tool 7) includes a hard coating layer formed on the surface of a substrate (lower part of FIG. 2). , A TiCN layer (first layer) having a granular crystal structure,
iC layer (second layer), Al ₂ O ₃ layer (third layer), and T
It is shown that it is composed of an iN layer (fourth layer).

[0018]

From the results shown in Tables 1-5 and FIGS according to the present invention, a single layer or a laminate of two or more of the TiCN constituting the lower layer of the hard coating layer, (a) the lower is granular crystals set
Weave, upper side: vertically elongated crystal structure, (b) lower side: set of granular crystals
Weave, middle is vertically grown crystal structure, upper side is granular crystal structure,
(C) a vertically elongated crystal structure on the lower side, a granular crystal structure on the upper side,
Each of the coated cutting tools 1 to 8 of the present invention having a layer structure of any one of (a) to (c) above has a conventional coating formed by forming a hard coating layer having a granular crystal structure in continuous cutting of steel. It shows superior wear resistance compared to cutting tools 1 to 8, and even in interrupted cutting of steel, conventional coated cutting tools 1 to 8 reach a long service life in a relatively short time due to chipping generated on the cutting edge. On the other hand, it is clear that they show much better chipping resistance and show excellent wear resistance over a long period of time.

As described above, the cutting tool made of a surface-coated WC-base cemented carbide according to the present invention has excellent chipping resistance, and therefore is required to have not only chipping resistance as well as continuous cutting of steel and cast iron, for example. In addition, they exhibit excellent wear resistance even in these interrupted cuttings, and exhibit excellent cutting performance over a remarkably long period.

[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.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-26404 (JP, A) JP-A-61-297003 (JP, A) JP-A-2-122049 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B23B 27/14 B23P 15/28 C23C 16/30 C23C 28/04

Claims (2)

(57) [Claims] 1. A surface-coated tungsten carbide-based cemented carbide cutting tool comprising a tungsten carbide-based cemented carbide substrate and a hard coating layer formed on the surface of the substrate with an average thickness of 0.5 to 20 μm. The layers are a lower layer consisting of a single layer or a stack of two or more layers of titanium carbonitride, and one of titanium carbide, nitride, carbonitride, carbonate, and carbonitride, and aluminum oxide. Each of the lower layers is composed of a single layer or an upper layer composed of two or more types of layers, and (a) a granular crystal structure on the lower side , a vertically elongated crystal structure on the upper side , and (b) a lower side on the lower side. Granular crystal structure, middle is vertically elongated crystal structure,
The upper side has a granular crystal structure , (c) the lower side has a vertically-grown crystal structure, the upper side has a granular crystal structure , and any one of the above (a) to (c) has a layer structure.
A cutting tool made of tungsten carbide-based cemented carbide with excellent surface resistance and excellent chipping resistance. 2. A hard coating layer is formed on the surface of a tungsten carbide-based cemented carbide substrate having a surface portion where the content of Co as a binder phase forming component is relatively large as compared with the inside of the substrate.
In a cutting tool made of a surface-coated tungsten carbide-based cemented carbide formed with an average layer thickness of ２０20 μm, the hard coating layer is a lower layer composed of a single layer of titanium carbonitride or a laminate of two or more layers; It is composed of an upper layer composed of a single layer of at least one of carbides, nitrides, carbonitrides, carbonates, and carbonitrides, and aluminum oxide, and a constitution of the lower layer. Each of the layers is composed of (a) a granular crystal structure on the lower side , a vertically elongated crystal structure on the upper side , (b) a granular crystal structure on the lower side, and a vertically elongated crystal structure in the middle,
The upper side has a granular crystal structure , (c) the lower side has a vertically-grown crystal structure, the upper side has a granular crystal structure , and any one of the above (a) to (c) has a layer structure.
A cutting tool made of tungsten carbide-based cemented carbide with excellent surface resistance and excellent chipping resistance.