JP3230374B2 - Surface-coated tungsten carbide-based cemented carbide cutting tool with excellent interlayer adhesion and fracture resistance with a hard coating layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hard coating layer having excellent interlayer adhesion and chipping resistance, and is therefore excellent over a long period of time when used for cutting, for example, mild steel having a high cutting resistance. The present invention relates to a cutting tool made of a surface-coated tungsten carbide-based cemented carbide that exhibits cutting performance (hereinafter referred to as a coated carbide cutting tool).

[0002]

2. Description of the Related Art Conventionally, as described in, for example, JP-B-57-1585 and JP-B-59-52703, a tungsten carbide-based cemented carbide substrate as a whole, For example, a tungsten carbide-based cemented carbide substrate having a surface portion having a relatively high content of Co or the like as compared with the inside of the substrate, that is, a tungsten carbide-based cemented carbide substrate having a binder phase-enriched zone on the surface portion A first layer made of a titanium nitride (hereinafter, shown as TiN) layer, a second layer made of a titanium carbonitride (hereinafter, shown as TiCN) layer using a chemical vapor deposition method or a physical vapor deposition method, A third layer composed of a titanium carbonate (hereinafter represented by TiCO) layer or a titanium carbonitride (hereinafter represented by TiCNO) layer, and a fourth layer composed of an aluminum oxide (hereinafter represented by Al ₂ O ₃ ) layer; More Coated hard cutting tool formed by forming a hard coating layer composed of a fifth layer of a TiN layer with a predetermined average layer thickness in the range of 3 to 30 μm, mainly for turning alloy steel or cast iron It is well known that it is used for milling and milling.

[0003]

On the other hand, in recent years, the use of FA in cutting machines has been remarkable, and in conjunction with the demand for labor saving in cutting work, cutting tools tend to be required to be versatile. For carbide cutting tools, there is no problem if this is used for cutting alloy steel or cast iron, etc.
Especially when used for cutting mild steel with high cutting resistance, the interlayer adhesion of the hard coating layer is not sufficient, so that delamination and chipping (minute chipping) are likely to occur in the hard coating layer. At present, the service life is reached in hours.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoint, the above-mentioned conventional coated carbide cutting tool was focused on, and a study was conducted to improve the interlayer adhesion of the hard coating layer constituting the cutting tool. In the hard coating layer constituting the cutting tool, there is no problem in the adhesion of the first TiN layer to the cemented carbide substrate, but the TiC of the first layer and the second layer
N layer, the second and third TiCO layers or TiCN
The interlayer adhesion of the O layer, the Al ₂ O ₃ layer of the _third and fourth layers, and the TiN layer of the fourth and fifth layers are all low, which causes delamination or chipping. Be easy. (B) In the hard coating layer constituting the conventional coated carbide cutting tool, the first TiN layer and the second TiCN layer
The layer, the third TiCO layer or the TiCNO layer, and the fifth TiN layer formed as required have a granular crystal structure, and the fourth Al ₂ O ₃ layer has an alpha crystal structure. Have. (C) In the hard coating layer constituting the above-mentioned conventional coated carbide cutting tool, the second TiCN layer has a vertically elongated crystal structure, and the fourth Al ₂ O ₃ layer mainly includes a copper type crystal. Structure, desirably 50% by volume of copper type crystal
Occupy the above, the remainder is a mixed structure consisting of alpha-type crystals,
Or if the structure is substantially composed of copper-type crystals,
The resulting hard coating layer has significantly improved interlayer adhesion, and therefore has no delamination or chipping even when cutting a work material having high cutting resistance, and has excellent cutting performance over a long period of time. To demonstrate. (D) The TiCN layer having the vertically elongated crystal structure constituting the second layer of the hard coating layer of (c) is divided into upper and lower layers by a TiN layer having one granular crystal structure, that is, the TiN divided layer The TiCN partition layer (T
When a structure having the iCN upper and lower division layers) is present, the chipping resistance of the cutting edge in heavy cutting such as high feed cutting and high depth cutting is remarkably improved. The research results shown in (a) to (d) above were obtained.

The present invention has been made on the basis of the above-mentioned research results, wherein (a) a first layer comprising a TiN layer having a granular crystal structure, and (b) a granular crystal on the surface of a cemented carbide substrate. A second layer composed of a TiCN upper and lower division layer having a vertically elongated crystal structure divided vertically by one TiN division layer having a structure, (c) a TiCO layer or a TiCN having a granular crystal structure
A third layer consisting of an O layer, (d) an Al ₂ O ₃ layer having a mixed structure composed of 50% by volume or more of copper-type crystals and the remainder composed of alpha-type crystals or a structure substantially composed of copper-type crystals. (E) a fifth layer of a TiN layer having a granular crystal structure, if necessary, and a hard coating layer composed of the above (a) to (e) in a predetermined range of 3 to 30 μm. The present invention is characterized by a coated carbide cutting tool having a hard coating layer formed by chemical vapor deposition and / or physical vapor deposition with an average layer thickness and having excellent interlayer adhesion and chipping resistance.

[0006] Among the hard coating layers constituting the coated carbide cutting tool of the present invention, the upper and lower division layers of TiCN having a vertically elongated crystal structure constituting the second layer are disclosed in, for example, Japanese Patent Application Laid-Open No.
No. 8010, reaction gas composition: volume%, TiCl ₄ : 1 to 10%, CH ₃ CN: 0.1 to 5
_{%, N 2: 0~35%,} H 2: remainder, reaction temperature: 850 to
It is desirable to form under the conditions of 950 ° C. and atmospheric pressure: 30 to 200 torr. On the other hand, a TiCN layer having a granular crystal structure usually has a reaction gas composition:
_{l 4: 1~5%, CH 4} : 2~7%, N 2: 15~35
%, H ₂ : remaining, reaction temperature: 950 to 1050 ° C., atmospheric pressure: 30 to 200 torr.
Further, Al ₂ having a structure mainly composed of copper type crystals
The O ₃ layer is a reaction gas:% by volume, and has an initial stage of 1-120.
Minutes are AlCl ₃ : 1-20%, optionally HCl:
1-20% and / or H ₂ S: 0.05~5%,
H ₂ : remaining, AlCl ₃ : 1 to 20%, CO 2
₂ : 0.5 to 30%, if necessary HCl: 1 to 20%
And / or _{H 2 S: 0.05~5%, H} 2: remainder, reaction temperature: 850 to 1000 ° C., atmospheric pressure: 30-20
It is formed under the condition of 0 torr.

The hard coating layer constituting the coated cemented carbide cutting tool of the present invention is formed by first depositing a first TiN layer on the surface of a cemented carbide substrate, then depositing a second TiCN lower section layer, TiN division layer, TiCN upper division layer, third layer TiCO layer or TiCNO layer, fourth layer Al ₂ O
It is formed by sequentially depositing _three layers and, if necessary, a fifth layer of TiN. When the second and subsequent layers are formed, the first layer of TiN is contained in the cemented carbide substrate. The C component may diffuse and form a solid solution.
The layer will be present as a TiCN layer after the formation of the hard coating.

Further, the hard coating layer has an average layer thickness of 3 to 3.
Preferably, the average layer thickness is 3 μm.
If the average layer thickness is less than 30 μm, the chipping resistance will rapidly decrease, and if the average layer thickness exceeds 30 μm, the first layer will not be able to secure desired wear resistance. The average thickness of the TiN layer is 0.1 to 5 μm.
m, those of the TiCN upper and lower division layers of the second layer and those of the TiN division layer are 3 to 20 μm and 0.1 to 5 μm, and the T of the third layer is
iCO layer or TiCNO layer is 0.01 to 2 μm, 4th
The Al ₂ O ₃ layer is 0.1 to 15 μm, and the fourth layer T
It is desirable that the iN layer has an average layer thickness of 0.1 to 5 μm.

[0009]

Next, the coated carbide cutting tool of the present invention will be described in detail with reference to examples. As raw material powder, medium-grain WC powder having an average particle diameter of 3 μm, coarse WC powder having an average particle diameter of 5 μm
Powder, 1.5 μm (Ti, W) C (weight ratio, same hereafter, TiC / WC = 30/70) powder, 1.2 μm
(Ti, W) CN (TiC / TiN / WC = 24/2)
0/56) powder, 1.3 μm (Ta, Nb) C (T
aC / NbC = 90/10) powder and 1.2 μm
Are prepared, and these raw material powders are blended in the composition shown in Table 1, and wet-mixed for 72 hours by a ball mill.
After drying, it is press-molded into a green compact having a shape defined in ISO • CNMG120408 (for cemented carbide substrates A and B) and SEEN42AFTN1 (for cemented carbide substrate C).
This green compact was vacuum-sintered under the conditions shown in Table 1 to produce cemented carbide substrates A to C. In the cemented carbide substrate B, the maximum Co content: 9% by weight and the depth:
A Co-enriched zone of 20 μm was formed, and the remaining cemented carbide substrates A and C did not have the Co-enriched zone and had an overall homogeneous structure. further,
Table 1 shows the internal hardness (Rockwell hardness A scale) of each of the cemented carbide substrates A to C.

Then, the surfaces of these cemented carbide substrates A to C are honed, and the compositions and compositions shown in Tables 3 to 5 are obtained by using an ordinary chemical vapor deposition apparatus under the conditions shown in Table 2. By forming a hard coating layer having a crystal structure and further an average layer thickness, coated carbide cutting tools 1 to 4 of the present invention and conventional coated carbide cutting tools 1 to 4 were produced, respectively. Next, regarding the coated carbide cutting tools 1 and 2 of the present invention and the conventional coated carbide cutting tools 1 and 2, a work material: a round bar of mild steel, a cutting speed: 210 m / min, a feed: 0.38 mm / rev, Cutting depth: 2 mm, cutting time: 30 min, high feed continuous cutting test of mild steel, and work material: round bar of mild steel, cutting speed: 210 m / min, feed: 0.23 mm / rev, cutting depth: 4 mm A continuous cutting test of mild steel was performed under the following conditions: cutting time: 40 min, and the flank wear width of the cutting edge was measured in each cutting test. Tables 4 and 6 show the results of these measurements. In addition, the coated carbide cutting tools 3 and 4 of the present invention and the conventional coated carbide cutting tool 3,
For No. 4, work material: mild steel square bar, cutting speed: 260 m / min, feed: 0.33 mm / tooth, depth of cut: 3 mm, cutting time: 40 min, milling of mild steel, and escape of the cutting edge The surface wear width was measured. The measurement results are also shown in Tables 4 and 6.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

[Table 4]

[0015]

[Table 5]

[0016]

[Table 6]

[0017]

According to the results shown in Tables 3 to 6, the coated carbide cutting tools 1 to 4 according to the present invention show that delamination or chipping of the hard coating layer occurs in the hard coating layer despite the cutting of mild steel having high cutting resistance. While showing no abrasion and excellent wear resistance,
It is apparent that the conventional coated carbide cutting tools 1 to 4 have insufficient interlayer adhesion in the hard coating layer, cause chipping when cutting mild steel, and reach a service life in a relatively short time. As described above, the coated carbide cutting tool according to the present invention has a hard coating layer having excellent interlayer adhesion and chipping resistance, so that not only cutting of alloy steel or cast iron, but also cutting resistance. Even when used for cutting mild steel with high hardness, it exhibits excellent cutting performance over a long period of time.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Uno 1511 Furamagi, Ishishita-cho, Yuki-gun, Ibaraki Pref. Mitsubishi Materials Corporation Tsukuba Works (56) Reference JP-A-6-8008 (JP, A) Kaihei 3-26404 (JP, A) Patent 2660180 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23B 27/14 B23P 15/28 C23C 16/30-16/40

Claims (2)

(57) [Claims] 1. Titanium nitride having a granular crystal structure on the surface of a tungsten carbide based cemented carbide substrate which is entirely homogeneous, or a tungsten carbide based cemented carbide substrate having a binder phase enriched zone in a surface layer portion. First consisting of layers
(B) a second layer comprising vertically divided titanium carbonitride layers having a vertically elongated crystal structure divided vertically by one titanium nitride division layer having a granular crystal structure, and (c) carbonic acid having a granular crystal structure. A third layer comprising a titanium oxide layer or a titanium carbonitride layer, (d) a mixed structure comprising 50% by volume or more of a kappa-type crystal and the remainder comprising an α-type crystal or a structure substantially comprising a kappa-type crystal. A fourth layer made of an aluminum oxide layer having a hard coating layer composed of the above (a) to (d) 3 to 30
A hard coating layer characterized by being formed by chemical vapor deposition and / or physical vapor deposition with a predetermined average layer thickness in the range of μm, and made of a surface-coated tungsten carbide-based cemented carbide having excellent interlayer adhesion and chipping resistance. tool. 2. Titanium nitride having a granular crystal structure on the surface of a tungsten carbide-based cemented carbide substrate which is entirely homogeneous, or a tungsten carbide-based cemented carbide substrate having a binder phase-enriched zone in a surface layer. First consisting of layers
(B) a second layer comprising vertically divided titanium carbonitride layers having a vertically elongated crystal structure divided vertically by one titanium nitride division layer having a granular crystal structure, and (c) carbonic acid having a granular crystal structure. A third layer comprising a titanium oxide layer or a titanium carbonitride layer, (d) a mixed structure comprising 50% by volume or more of a kappa-type crystal and the remainder comprising an alpha-type crystal or a structure substantially comprising a kappa-type crystal. (E) a fifth layer made of a titanium nitride layer having a granular crystal structure.
The hard coating layer composed of (a) to (e) is
A hard coating layer characterized by being formed by chemical vapor deposition and / or physical vapor deposition with a predetermined average layer thickness in the range of μm, and made of a surface-coated tungsten carbide-based cemented carbide having excellent interlayer adhesion and chipping resistance. tool.