JP2001328006A - Surface-covered tungsten carbide group cemented carbide throw-away cutting tip with hard covering layer having excellent interlayer adhesion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a covered cemented carbide cutting tip with a hard covering layer having excellent interlayer adhesion. SOLUTION: The covered cemented carbide cutting tip is formed by chemically depositing and/or physically depositing (a) a TiN layer having the average layer thickness of 0.1 to 2 μm and a granular crystal structure as a first layer from the base body side, (b) a TiCN layer having the average layer thickness of 3 to 15 μm and a longitudinally long growth crystal structure as a second layer, (c) a TiC layer having the average layer thickness of 0.5 to 8 μm and a granular crystal structure as a third layer, (d) a (Ti, Al) CO layer having the average layer thickness of 0.3 to 3 μm and a granular crystal structure as a fourth layer and having the component concentration distribution of continuously and/or intermittently gradually reducing a Ti and C component being a constitutive component and continuously and/or intermittently gradually increasing an Al and O component being simularly the constitutive component along the layer thickness toward an upper side interface with an Al2O3 layer of a fifth layer from a lower side interface with the TiC layer of the third layer and (e) the hard covering layer composed of the Al2O3 layer having the average layer thickness of 1 to 8 μm and a granular crystal structure as the fifth layer on a surface of a WC group cemented carbide base body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high speed cutting of difficult-to-cut materials such as stainless steel and mild steel, and a surface coated tungsten carbide based cemented carbide with a hard coating layer exhibiting excellent interlayer adhesion. The present invention relates to a tip (hereinafter, referred to as a coated carbide cutting tip).

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 7-328
As described in JP-A-810, the surface of a tungsten carbide-based cemented carbide substrate (hereinafter referred to as a cemented carbide substrate)
(A) a titanium nitride (hereinafter also referred to as TiN) layer having an average layer thickness of 0.1 to 2 μm and a granular crystal structure as a first layer from the substrate side;
A titanium carbonitride (hereinafter, referred to as 1-TiCN) layer having an average layer thickness of 5 μm and a vertically grown crystal structure, and (c) a third layer having an average layer thickness of 0.5 to 8 μm and a granular crystal structure. Titanium carbide (hereinafter also indicated by TiC)
And (d) a titanium carbonate (hereinafter referred to as Ti) having an average layer thickness of 0.3 to 3 μm and a granular crystal structure as the fourth layer.
CO) layer and / or titanium carbonitride (hereinafter, referred to as "CO")
(Shown as TiCNO), and (d) the fifth layer, 1 to 8
A coated carbide cutting tip formed by chemical vapor deposition and / or physical vapor deposition of a hard coating layer composed of an aluminum oxide (hereinafter, referred to as Al ₂ O ₃ ) layer having an average layer thickness of μm and a granular crystal structure is known. It is also known that this coated carbide cutting tip is used for continuous cutting or interrupted cutting of steel, cast iron or the like. In general, as the Al ₂ O ₃ layer constituting the hard coating layer of the coated carbide cutting tip, those having an α-type crystal structure or those having a κ-type crystal structure may be widely put to practical use. The above-mentioned l-TiCN layer is known, for example, from JP-A-6-8010.
JP-A-6-57430 and the like, and using a mixed gas containing an organic carbonitride as a reaction gas in a normal chemical vapor deposition apparatus, and performing chemical vapor deposition at a medium temperature range of 700 to 950 ° C. It is formed by doing.

[0003]

On the other hand, in recent years, the performance and output of cutting devices have been remarkably improved, and there is also a strong demand for labor saving and energy saving for cutting work, and further cost reduction. Machining tends to speed up, but in the above-mentioned conventional coated carbide cutting tip, there is no problem if this is used to cut low alloy steel or cast iron under normal conditions, The cutting of difficult-to-cut materials such as stainless steel and mild steel, which are particularly viscous in terms of material and the cutting powder easily adheres to the surface of the cutting edge, thus increasing the cutting resistance to the cutting edge When performed under high-speed conditions that cause an increase in cutting resistance, the first to hard layers between the first layer of the hard coating layer and the super-hard substrate, both of which are made of a Ti compound
The three layers have excellent adhesion, but the TCO layer and the TiCNO layer constituting the fourth layer form the T layer constituting the third layer.
Since the adhesion to the iC layer and the Al ₂ O ₃ layer constituting the fifth layer is not sufficient, peeling easily occurs between these layers, and as a result, chipping or chipping (minute chipping) occurs in the cutting edge. However, as a result, at present, the service life is reached in a relatively short time.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoint, the above-mentioned conventional coated carbide cutting tip
To improve interlayer adhesion of hard coating layer in steel
As a result, the hard coating of the conventional coated carbide cutting tip
TiCO layer and TiCN present as fourth layer in overlayer
Instead of the O layer, the third layer is formed from the lower interface with the TiC layer.
5 layers of Al_Two O_Three Towards the upper interface with the layer and to the layer thickness
Along, the constituent components Ti and carbon (C) are continuous
And / or intermittent gradual decrease, also with constituents
Some Al and oxygen (O) are continuous and / or intermittent
Of Ti and Al having a component concentration distribution that gradually increases
Combined carbon oxide [hereafter referred to as (Ti, Al) CO] layer
Then, in the resulting coated carbide cutting insert,
The (Ti, Al) CO layer constituting the hard coating layer is
According to the concentration distribution of the constituent components as described above,
The lower interface portion in contact with the C layer was similar to the TiC layer.
Composition, while the fifth layer Al_Two O_Three Upper bounding layer
In the surface part, the Al_Two O_Three So that it has a composition similar to the layer
, The third TiC layer and the fifth layer
Al _Two O_Three Adhesion to the layer is significantly improved, and hard coating
The layers have a good overall adhesion between layers
Stainless steel and mild steel with extremely high cutting resistance to the cutting edge
Even when cutting hard-to-cut materials such as
Chipping and chipping caused by peeling are prevented,
Slow cutting performance will be exhibited over a long period of time
The research results were obtained.

The present invention has been made based on the above research results, and has (a) an average layer thickness of 0.1 to 2 μm as a first layer from the substrate side on the surface of the superhard substrate. A TiN layer, (b as a second layer, an l-TiCN layer having an average layer thickness of 3 to 15 μm, and (c) as a third layer,
A TiC layer having an average layer thickness of 0.5 to 8 μm; and (d) a fourth layer having an average layer thickness of 0.3 to 3 μm, and 5 layers of A
towards the upper interface with the l ₂ O ₃ layer and along the layer thickness,
The constituent components Ti and C gradually and continuously and / or intermittently decrease, and the constituent Al and O components also have a continuously and / or intermittently gradually increasing component concentration distribution (Ti, Al) CO layer, (d) As the fifth layer, Al ₂ O having an average layer thickness of 1 to 8 μm
_{The present invention is characterized} in that the hard coating layer is formed by chemical vapor deposition and / or physical vapor deposition of a hard coating layer composed of _three layers.

The average layer thickness of the constituent layers in the hard coating layer of the coated carbide cutting insert of the present invention is determined for the following reasons. (A) TiN layer The first TiN layer is made of a cemented carbide substrate and a second layer of l-Ti
Any of the CN layers is firmly adhered and has an effect of contributing to the improvement of interlayer adhesion. However, if the average layer thickness is less than 0.1 μm, desired excellent adhesion cannot be secured. Since the average layer thickness up to 2 μm is sufficient for adhesion, the average layer thickness is determined to be 0.1 to 2 μm.

(B) l-TiCN layer The second layer, l-TiCN layer, has excellent toughness due to its own vertically elongated crystal structure, which has an effect of improving the toughness of the entire hard coating layer. However, if the average layer thickness is less than 3 μm, the desired effect of improving the toughness of the hard coating layer cannot be obtained. On the other hand, if the average layer thickness exceeds 15 μm, cutting is difficult especially in high-speed cutting of the above-mentioned difficult-to-cut material where heat generation is remarkable. The average layer thickness was determined to be 3 to 15 μm because the thermoplastic deformation which causes the uneven blade wear easily occurs.

(C) TiC layer The third TiC layer is relatively composed of the above-described TiN layer and
-Since it has a higher hardness than the TiCN layer, it is present for the purpose of further improving wear resistance. However, if the average layer thickness is less than 0.5 μm, the desired effect of improving wear resistance cannot be obtained. On the other hand, if the average layer thickness exceeds 8 μm, chipping tends to occur on the cutting edge.
It was determined to be 5 to 8 μm.

(D) (Ti, Al) CO layer The fourth (Ti, Al) CO layer is composed of the third TiC layer and the fifth layer by changing the concentration of the constituents along the layer thickness as described above. the Al ₂ O ₃ layer than either firmly adhered in, there is a contributing effect to interlayer adhesion improvement, the average layer thickness is less than 0.3 [mu] m, it is impossible to secure a desired excellent adhesion On the other hand, when the average layer thickness exceeds 3 μm,
Since the embrittlement tendency appears in the hard coating layer and chipping easily occurs on the cutting edge, the average layer thickness is set to 0.3 to 3 μm.

(D) Al ₂ O ₃ layer The fifth Al ₂ O ₃ layer has an effect of improving the wear resistance of the hard coating layer. However, if the average layer thickness is less than 1 μm, desired excellent properties are obtained. Wear resistance cannot be secured,
On the other hand, if the average layer thickness exceeds 8 μm, chipping tends to occur on the cutting edge.
It was decided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated carbide cutting insert of the present invention will be specifically described with reference to examples. As a raw material powder, fine WC powder having an average particle size of 1.5 μm, 3.0 μm
Medium WC powder, 1.2 μm (Ti, W) CN (the same in mass ratio, hereinafter, TiC / TiN / WC = 24/20)
/ 56) powder, 1.3 μm of (Ta, Nb) C (Ta
C / NbC = 90/10) powder, 1.2 μm ZrC
Powder, 1.0 μm Cr powder, and 1.2 μm Co powder were prepared, and these raw material powders were blended in the composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and dried. The mixed powder was prepared according to the ISO standard CNMG1204.
08 was compacted into a green compact in the form of a throw-away tip, and the compact was vacuum-sintered under the conditions shown in Table 1 to produce carbide substrates A to E, respectively.

Further, 6.7 with respect to the above-mentioned super-hard substrate E.
After holding at a temperature of 1400 ° C. for 1 hour in a CH 4 gas atmosphere of kPa, performing carburizing treatment under slow cooling conditions, and removing carbon and Co adhering to the surface of the super-hard substrate after the treatment by acid and barrel polishing. Maximum C at 8 μm from surface
A Co-enriched zone having an o content of 14.2% by mass and a depth of 32 μm was formed on the surface of the substrate. In addition, each of the super-hard substrates C was 18 μm from the surface while being sintered.
At the position of maximum Co content: 9.3% by mass, depth: 22μ
m Co-enriched zone, the super hard substrate D has a maximum Co content of 13.5% by mass at a position 20 μm from the surface on the surface portion,
A Co-enriched zone having a depth of 27 μm was formed, and the remaining carbide substrates A and B did not have the Co-enriched zone and had a uniform structure throughout.
Further, Table 1 shows the internal hardness (Rockwell hardness A scale) of each of the carbide substrates A to E.

[0013] Then, in a state where these super-hard substrates A to E are processed and honed into a predetermined shape, the surface thereof is subjected to the conditions shown in Tables 2 to 4 using an ordinary chemical vapor deposition apparatus. By forming the hard coating layer having the target layer thickness (the flank of the cutting edge) shown in Tables 3 to 6, the coated carbide cutting tips 1 to 10 of the present invention and the conventionally coated carbide cutting tip 1
To 10 were respectively manufactured.

The thickness of the constituent layers of the hard coating layer was measured using a scanning electron microscope and an optical microscope (measuring the longitudinal section of the layers) for the various coated carbide cutting tips obtained as a result. Each of which has substantially the same average layer thickness (average value of five-point measurements) as the target layer thickness shown in Tables 3 to 6, and the constituent layers of the hard coating layer of the coated carbide cutting tips 1 to 10 of the present invention. For the composition along the layer thickness of the (Ti, Al) CO layer, the intermediate position between the layer thickness change points shown in Tables 3 and 4 was observed using an Auger electron spectrometer. 4 show substantially the same composition as the target composition shown in FIG. 4, and from these results, both the constituent components Ti and C along the layer thickness gradually and intermittently move from the lower interface toward the upper interface. Al and O
On the contrary, it was confirmed that each of the components showed a change in the component concentration that gradually increased intermittently.

Next, the coated carbide cutting tip 1 according to the present invention will be described.
Workpiece: JIS SUS304 round bar, Cutting speed: 300 m / min, Cutting depth: 1.2 mm, Feed: 0.3 mm / rev, Cutting time: 10 Minutes, Dry high-speed continuous cutting test of stainless steel under the following conditions: Work material: JIS SUS304, 4 longitudinally-spaced round bars at regular intervals in the longitudinal direction, Cutting speed: 300 m / min, Cutting depth: 1.2 mm, Feed : 0.27 mm / rev, Cutting time: 10 minutes, Dry high-speed interrupted cutting test of stainless steel under the following conditions: Work material: JIS S15C round bar, Cutting speed: 420 m / min, Cutting depth: 1. 2 mm, feed: 0.3 m / rev, cutting time: 10 minutes, dry high-speed continuous cutting test of mild steel under the following conditions: Work material: JIS S15C with four longitudinal grooves at regular intervals in the length direction Round bar, cutting speed: 420m / min, depth of cut: 1.2mm, feed: 0.27mm / rev, cutting time: 10min. The maximum flank wear width of the cutting blade was measured. Table 7 shows the measurement results.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

[Table 5]

[0021]

[Table 6]

[0022]

[Table 7]

[0023]

From the results shown in Tables 4 to 7, all of the coated carbide cutting tips 1 to 10 according to the present invention in which the fourth layer of the hard coating layer is composed of a (Ti, Al) CO layer are described in the above ( Ti,
Al) The CO layer is composed of the third TiC layer and the fifth Al ₂ layer.
Firmly adheres to any of the O ₃ layers, and the first layer of TiN
A first layer made of a Ti compound between the layer and the super-hard substrate;
Since the hard coating layer has excellent interlayer adhesion as a whole, in addition to the fact that high adhesion is secured between the three layers, stainless steel having a remarkably high cutting resistance to the cutting edge Even when cutting hard-to-cut materials such as steel and mild steel at high speeds, there is no chipping or chipping due to delamination of the hard coating layer, and excellent cutting performance is exhibited over a long period of time. The fourth layer is a TiCO layer and / or TiCNO
In the conventional coated carbide cutting tips 1 to 10 made of layers, the third of the TiCO layer and the TiCNO layer
Insufficient adhesion of the layer to the TiC layer and the fifth layer to the Al ₂ O ₃ layer causes delamination between the layers, which results in chipping and chipping of the cutting edge, resulting in a relatively short service life. It is clear that As described above, the coated carbide cutting tip of the present invention is not limited to continuous cutting and interrupted cutting under ordinary conditions such as steel and cast iron, and particularly, stainless steel and mild steel having high cutting resistance to the cutting edge. Even when difficult-to-cut materials are cut under high-speed cutting conditions, excellent cutting performance is exhibited over a long period of time.

Claims (1)

[Claims] 1. A titanium nitride layer having an average layer thickness of 0.1 to 2 μm and a granular crystal structure as a first layer from the substrate side, on the surface of a tungsten carbide-based cemented carbide substrate, As the second layer, a titanium carbonitride layer having an average layer thickness of 3 to 15 μm and a vertically grown crystal structure, (c) as the third layer, titanium carbide having an average layer thickness of 0.5 to 8 μm and a granular crystal structure (D) The fourth layer has an average layer thickness of 0.3 to 3 μm and a granular crystal structure, and oxidizes a fifth layer shown below from the lower interface with the third layer of titanium carbide. Towards the upper interface with the aluminum layer and along the layer thickness, the constituent components Ti and carbon decrease continuously and / or intermittently, and the constituent components Al and oxygen also change continuously and / or Or an intermittent A hard coating layer composed of a composite carbonate layer of Ti and Al having a partial concentration distribution, and (d) an aluminum oxide layer having an average layer thickness of 1 to 8 μm and a granular crystal structure as the fifth layer, by chemical vapor deposition. A throw-away cutting tip made of a surface-coated tungsten carbide-based cemented carbide with a hard coating layer having excellent interlayer adhesion, which is obtained by physical vapor deposition.