JP2927181B2 - Surface coated tungsten carbide based cemented carbide cutting tool with excellent interlayer adhesion with 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, therefore, exhibits excellent cutting performance over a long period of time when used for cutting, for example, mild steel having a large cutting resistance. 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).

[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 titanium nitride (hereinafter, shown as TiN), a second layer made of titanium carbonitride (hereinafter, shown as TiCN) using a chemical vapor deposition method or a physical vapor deposition method, A third layer made of titanium (hereinafter, shown as TiCO) or titanium carbonitride (hereinafter, shown as TiCNO), and a fourth layer made of aluminum oxide (hereinafter, shown as Al ₂ O ₃ )
Coated hard cutting tool formed by forming a hard coating layer composed of a layer and, if necessary, a fifth layer made of TiN with a predetermined average layer thickness in the range of 3 to 30 μm, mainly comprises alloy steel or It is well known that it is used for turning or milling cast iron.

[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.
Particularly when used for cutting mild steel with high cutting resistance, the interlayer adhesion of the hard coating layer is not sufficient, so that the hard coating layer is liable to delamination and chipping, which causes a relatively short service life. At present.

[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. If the structure (preferably, a mixed structure in which the copper type crystal occupies 50% by volume or more and the remainder is composed of the alpha type crystal, or a structure substantially composed of the copper type crystal), the resulting hard coating layer has any interlayer. Adhesion is also remarkably improved. Therefore, even when cutting a work material having a high cutting resistance, chipping due to delamination does not occur, and excellent cutting performance is exhibited over a long period of time. The research results shown in (a) to (c) above were obtained.

The present invention has been made on the basis of the above research results, and includes a first layer made of TiN having a granular crystal structure and a vertically elongated crystal set on the surface of a cemented carbide substrate.
A second layer of TiCN having a texture, a third layer of TiCO or TiCNO having a granular crystal structure, and
Copper-type crystals account for more than 50% by volume, with the remainder being Alf
Mixed structure consisting of ァ -type crystals, or substantially copper-type
A hard coating layer composed of a fourth layer made of Al ₂ O ₃ having a crystal structure and a fifth layer made of TiN having a granular crystal structure formed as needed is formed by a usual chemical vapor deposition method and / or The present invention is characterized by a coated carbide cutting tool having a hard coating layer having excellent interlayer adhesion, formed by a physical vapor deposition method with a predetermined average layer thickness in a range of 3 to 30 μm.

The TiCN layer having a vertically elongated crystal structure of the second layer among the hard coating layers constituting the coated carbide cutting tool of the present invention is, for example, as described in JP-A-6-8010. Reaction gas composition:% by volume, TiCl ₄ : 1 to 10%, C
H ₃ CN: 0.1 to 5%, N ₂ : 0 to 35%, H ₂ : residual, reaction temperature: 850 to 950 ° C., atmospheric pressure: 30 to 200 torr. On the other hand, a TiCN layer having a granular crystal structure usually has a reaction gas composition: volume%, TiCl ₄ : 1 to 5%, CH
_{4: 2~7%, N 2:} 15~30%, H 2: remainder, reaction temperature: 950 to 1050 ° C., atmospheric pressure: 30～200Torr, is formed by the conditions. Further, the Al ₂ O ₃ layer having a structure mainly composed of a copper-type crystal is composed of a reaction gas: volume% and an Al phase of 1 to 120 minutes in the initial stage.
Cl _3: 1-20%, HCl if necessary: 1-20%
And / or _{H 2 S: 0.05~5%, H} 2: remainder,
Thereafter, AlCl ₃ : 1 to 20%, CO ₂ : 0.5
30%, optionally HCl: 1 to 20% and / or _{H 2 S: 0.05~5%, H} 2: remainder, reaction temperature: 850 to 1000 ° C., atmospheric pressure: 30～200Torr, conditions Is formed.

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 layer and a third TiCN layer.
Layer TiCO or TiCNO layer and fourth layer A
An l ₂ O ₃ layer and, if necessary, a fifth layer of TiN layer are sequentially deposited. When forming the second and subsequent layers, the cemented carbide is added to the first layer of TiN layer. In some cases, the C component in the base may diffuse and form a solid solution. In this case, the first layer exists as the TiCN layer after the formation of the hard coating layer.

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, that of the second TiCN layer is 3 to 20 μm, that of the third TiCO layer or TiCNO layer is 0.01 to 2 μm,
The fourth Al ₂ O ₃ layer has a thickness of 0.1 to 15 μm,
The TiN layer of the layer preferably 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 substrate A to D) and SEEN42AFTN1 (for cemented carbide substrate E),
The green compacts were vacuum-sintered under the conditions shown in Table 1 to produce cemented carbide substrates A to E. Further, the cemented carbide substrate B is kept in a 100 torr CH ₄ gas atmosphere at a temperature of 1400 ° C. for 1 hour, and then subjected to a slow cooling carburizing treatment. After the treatment, carbon and carbon adhering to the substrate surface are removed.
By removing o by acid and barrel polishing, a Co-enriched zone having a maximum Co content of 15% by weight and a depth of 40 μm was formed at a position 10 μm from the surface in the surface layer portion of the substrate.
In the cemented carbide substrates A and D, a Co-enriched zone having a maximum Co content of 9% by weight and a depth of 20 μm was formed at a position of 15 μm from the surface in the surface layer portion as sintered. The remaining cemented carbide substrates C and E have the above C
o There was no formation of an enriched zone and the tissue had an overall homogeneous structure. Further, Table 1 shows that the cemented carbide substrates A to E
Of each sample (Rockwell hardness A scale).

Next, the surfaces of these cemented carbide substrates A to E are honed, and the compositions and the compositions shown in Tables 3 to 6 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 an average layer thickness, coated carbide cutting tools 1 to 7 of the present invention and conventional coated carbide cutting tools 1 to 7 were produced, respectively. In addition,
FIG. 1 shows a micrograph (5000 times) of a metal carbide microscope of the coated carbide cutting tool 1 of the present invention. Next, the coated carbide cutting tools 1 to 5 of the present invention and the conventional coated carbide cutting tool 1
About ~ 5, work material: round bar of mild steel, cutting speed: 280m / min., Feed: 0.23mm / rev., Depth of cut: 2mm, cutting time: 30min., Continuous cutting test of mild steel, And work material: Square bar of mild steel, Cutting speed: 260m / min., Feed: 0.23mm / rev., Depth of cut: 1.5mm, Cutting time: 40min. In each cutting test, the flank wear width of the cutting edge was measured. Tables 4 and 6 show the measurement results. The coated carbide cutting tools 6 and 7 of the present invention and the conventional coated carbide cutting tools 6 and 7 include: work material: square bar of mild steel; cutting speed: 260 m / min .; feed: 0.33 mm / tooth; Milling of mild steel was performed under the following conditions: cutting depth: 2.5 mm, cutting time: 40 min., And the flank wear width of the cutting edge 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 7 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,
Conventionally, the coated carbide cutting tools 1 to 7 clearly show that the interlayer adhesion in the hard coating layer is insufficient, and delamination and chipping occur in the cutting of mild steel, resulting in a relatively short service life. is there. As described above, the coated cemented carbide cutting tool according to the present invention has a hard coating layer having excellent interlayer adhesion, so that it can cut not only alloy steel and cast iron, but also mild steel having a high cutting resistance. Even when used for cutting, excellent cutting performance is exhibited over a long period of time.

[Brief description of the drawings]

FIG. 1 is a micrograph (5000 ×) of a surface portion of a coated carbide cutting tool 1 according to the present invention, which is taken with a metallographic microscope.

Continuation of front page (72) Inventor Kenichi Uno 1511 Furamagi, Ishishita-cho, Yuki-gun, Ibaraki Pref. Mitsubishi Materials Corporation Tsukuba Works (56) References JP-A-6-8008 (JP, A) JP-A Sho 52 -100376 (JP, A) JP-B-61-15149 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23B 27/14

Claims (2)

(57) [Claims] 1. 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, the surface of which is made of titanium nitride having a granular crystal structure. One layer, vertically grown crystal structure
A second layer made of titanium carbonitride having a third layer made of titanium carbonate or titanium carbonitride having a granular crystal structure.
Layers and copper-type crystals account for more than 50% by volume
Mixed structure consisting of alpha-type crystals, or substantially
A hard coating layer formed of a fourth layer made of aluminum oxide having a copper-type crystal structure and having a predetermined average layer thickness in a range of 3 to 30 μm. The hard coating layer has excellent interlayer adhesion. Surface-coated tungsten carbide based cemented carbide cutting tool. 2. 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 portion thereof, comprising titanium nitride having a granular crystal structure on the surface thereof. One layer, vertically grown crystal structure
A second layer made of titanium carbonitride having a third layer made of titanium carbonate or titanium carbonitride having a granular crystal structure.
Layers and copper-type crystals account for more than 50% by volume
Mixed structure consisting of alpha-type crystals, or substantially
A hard coating layer composed of a fourth layer made of aluminum oxide having a copper-type crystal structure and a fifth layer made of titanium nitride having a granular crystal structure is formed with a predetermined average layer thickness in a range of 3 to 30 μm. A cutting tool made of a surface-coated tungsten carbide-based cemented carbide having a hard coating layer having excellent interlayer adhesion.