JP2001310202A - Surface covered cermet made cutting tool on which hard covered layer displays excellent chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface covered cermet made cutting tool on which a hard covered layer displays excellent chipping resistance. SOLUTION: This surface covered cermet made cutting tool made by chemically depositing and/or physically depositing a hard covered layer constituted of a lower layer of a Ti compound layer made of a single layer of one kind or a multiple layer of not less than two kinds of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer and a TiCNO layer basically and an upper layer of an AL2O3 layer on a surface of a tool base body constituted of WC group cemented carbide or TiCN group cermet in average layer thickness of 3-20 μm is constituted by chemically depositing or physically depositing a V carbide nitride layer made of a single layer of one kind or a multiple layer of not less than two kinds of a VC layer, a VN layer and a VCN layer as the extreme outer layer on a surface of an AL2O3 layer constituting an upper layer of the hard covered layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cutting tool made of a surface-coated cermet (hereinafter, referred to as a cutting tool) in which a hard coating layer exhibits excellent chipping resistance, especially in high-speed interrupted cutting of steel or cast iron.
Coated cermet tool).

[0002]

2. Description of the Related Art Conventionally, a surface of a tool base composed of a cemented carbide based on tungsten carbide (hereinafter referred to as WC) or a cermet based on titanium carbonitride (hereinafter referred to as TiCN) has basically Carbide (hereinafter, referred to as TiC) layer, nitride (hereinafter, also referred to as TiN) layer, carbonitride (hereinafter, referred to as TiCN) layer, carbonate (hereinafter, referred to as T)
iCO) layer and carbonitride (hereinafter TiCN)
O), a hard coating composed of a lower layer of a Ti compound layer consisting of one kind of single layer or two or more layers, and an upper layer of an aluminum oxide (hereinafter, Al ₂ O ₃ ) layer. Coated cermet tools are known in which the layers are formed by chemical vapor deposition and / or physical vapor deposition with an average layer thickness of 3 to 20 μm. The coated cermet tools are used for continuous or interrupted cutting of, for example, various steels and cast irons. It is also known that

In general, a Ti compound layer and Al ₂ O ₃ constituting a hard coating layer of the above-mentioned coated cermet tool are generally used.
It is also well known that the layer has a granular crystal structure, and the Al ₂ O ₃ layer is widely and practically used, for example, those having an α-type crystal structure or those having a κ-type crystal structure. As described in JP-A-6-8010 and JP-A-7-328808, a TiCN layer constituting the Ti compound layer is formed by a normal chemical vapor deposition apparatus for the purpose of improving the toughness of the layer itself. It is also known that a mixed gas containing an organic carbonitride is used as a reaction gas and formed by chemical vapor deposition at a medium temperature range of 700 to 950 ° C. to have a vertically elongated crystal structure.

[0004]

In recent years, the performance of cutting equipment has been remarkably improved, but on the other hand, there has been a strong demand for labor saving, energy saving, and further cost reduction in cutting work. In the above-mentioned conventional coated cermet tool, there is no problem when it is used for continuous cutting or interrupted cutting under normal conditions such as steel or cast iron. When used in severe high-speed intermittent cutting, that is, high-speed intermittent cutting in which a thermal mechanical impact is applied to the cutting edge at an extremely fast pitch, natural cutting occurs in the Al ₂ O ₃ layer that forms the upper layer of the hard coating layer. Due to the myriad of micro cracks that may be generated, chipping (micro chipping) is likely to occur in the cutting edge (hard coating layer), and as a result, the service life can be reached in a relatively short time. In .

[0005]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoints, especially when used for high-speed interrupted cutting of steel and mild steel, etc., as a result of conducting research to develop a coated cermet tool in which the hard coating layer exhibits excellent chipping resistance, Conventionally, on the surface of coated cermet tools,
Using a normal chemical vapor deposition apparatus or physical vapor deposition apparatus, a V (vanadium) carbide (hereinafter, referred to as VC) layer, a nitride (hereinafter, also referred to as VN) layer, a carbonitride (hereinafter, referred to as VC)
N), a V-carbon / nitride layer consisting of one single layer or two or more layers of 0.1 to 5 μm as an outermost layer.
When the chemical vapor deposition or physical vapor deposition is performed with an average layer thickness of m, the resulting coated cermet tool heats the cutting edge portion by heat generated during cutting, and the temperature of the cutting edge portion in high-speed intermittent cutting accompanied by high heat generation. Since the temperature reaches about 700 ° C. or higher, the V-carbon / nitride layer composed of the VC layer, the VN layer, and the VCN layer constituting the outermost layer is oxidized to vanadium oxide (hereinafter, referred to as “Vanadium oxide”).
V ₂ O ₅ ), and this V ₂ O ₅ has a low melting point of 668 ° C., and therefore melts to form A which forms the upper layer of the hard coating layer.
Infiltrating the myriad of fine cracks in the l ₂ O ₃ layer,
_The thermal mechanical impact on the ₂ O ₃ layer is remarkably reduced, and as a result, the chipping caused by the fine cracks is significantly suppressed. Therefore, excellent cutting performance over a long period of time even in high-speed interrupted cutting involving high heat generation and impact. The research results showed that they would be able to demonstrate

The present invention has been made based on the results of the above-mentioned research, and basically has a T-substrate made of a WC-based cemented carbide or a TiCN-based cermet on the surface thereof.
iC layer, TiN layer, TiCN layer, TiCO layer, and T
A hard coating layer composed of a lower layer of a Ti compound layer composed of one kind of single layer or two or more layers of the iCNO layer and an upper layer of an Al ₂ O ₃ layer is chemically coated with an average layer thickness of 3 to 20 μm. In a coated cermet tool formed by vapor deposition and / or physical vapor deposition, one of a VC layer, a VN layer and a VCN layer is further formed as an outermost layer on the surface of the Al ₂ O ₃ layer constituting the upper layer of the hard coating layer. Hard coating layer has excellent chipping resistance, obtained by chemical vapor deposition or physical vapor deposition of V carbon / nitride layer consisting of a single kind of layer or two or more kinds of multiple layers with an average layer thickness of 0.1 to 5 μm. The present invention is characterized in that a coated cermet tool is used.

In the coated cermet tool of the present invention, the average thickness of the outermost layer is set to 0.1 to 5 μm. If the average layer thickness is less than 0.1 μm, desired chipping resistance is secured. On the other hand, the effect of imparting chipping resistance is based on the reason that the average layer thickness of 5 μm can be sufficiently satisfied. further,
The reason why the average layer thickness of the hard coating layer is set to 3 to 20 μm is that if the layer thickness is 3 μm, the desired excellent wear resistance cannot be secured. This is because chipping and chipping easily occur.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the coated cermet tool of the present invention will be specifically described with reference to examples. As the raw material powder, WC powder, (Ti, W) C (the same hereinafter, TiC / WC = 30/70 by mass ratio) powder having a predetermined average particle size in the range of 0.5 to 4 μm, and ( Ti, W) C
N (TiC / TiN / WC = 24/20/56) powder,
(Ta, Nb) C (TaC / NbC = 90/10) powder, Cr ₃ C ₂ powder, and Co powder were prepared, and these raw material powders were blended into the blending composition shown in Table 1 and wet-processed in a ball mill for 72 hours. After mixing and drying, the mixture is pressed into a green compact having a predetermined shape at a pressure of 98 MPa.
a) Vacuum sintering is performed at 1410 ° C. for 1 hour in the vacuum of a. After sintering, the cutting edge is subjected to a honing process of R: 0.03 mm to form a throw-away tip shape specified in ISO • CNMG120408. Tool bases A to F made of WC-based cemented carbide were prepared.

Further, as raw material powders,
TiCN having an average particle size of 2 μm (TiC /
(TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder, Co powder, and Ni powder were prepared, and these raw material powders were blended into the composition shown in Table 2. After wet-mixing with a ball mill for 24 hours and drying, the mixture is pressed into a green compact at a pressure of 98 MPa, and the green compact is fired in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour. After sintering and sintering,
Honing processing of R: 0.03 mm was performed on the cutting edge portions to form tool bases a to f made of TiCN-based cermet having a chip shape of ISO standard, CNMG120412.

Next, on the surfaces of the tool bases A to F and the tool bases a to f, a conventional chemical vapor deposition apparatus was used, and Table 3 (l-TiCN in Table 3 is described in JP-A-6-8010. Under the conditions shown in Table 4 under the conditions shown in Table 4 under the conditions shown in Table 4 below. By forming a hard coating layer comprising a thick Ti compound layer and an Al ₂ O ₃ layer, and further forming a V carbon / nitride layer as the outermost layer, the coated cermet tools 1 to 5 of the present invention
12 were each manufactured. For the purpose of comparison, as shown in Table 5, conventional coated cermet tools 1 to 12 were manufactured under the same conditions except that the V-carbon / nitride layer as the outermost layer was not formed.

The resulting coated cermet tools 1 to 12 of the present invention and the conventional coated cermet tools 1 to 1
For 2, observation of this hard coating layer and the outermost layer using Auger spectrometer was (a longitudinal section of the layer observed) and, respectively, the hard coating layer Ti compound layer and Al ₂
It was confirmed that it was composed of an O ₃ layer and the outermost layer was composed of a V-carbon / nitride layer. When the thicknesses of the constituent layers and the outermost layer of the hard coating layer of these coated cermet tools were measured using a scanning electron microscope (also in the vertical section), the average thickness was substantially the same as the target layer thickness. The layer thickness (average value of five-point measurements) is shown.

Next, the coated cermet tools 1 to 6 according to the present invention and the conventional coated cermet tools 1 to 6 were screwed to the tip of a tool steel tool with a fixing jig. For No. 6, the work material: JIS SCM440, a longitudinally spaced round bar with four longitudinal grooves, cutting speed: 300 m / min, cutting depth: 1.5 mm, feed: 0.4 mm / rev, cutting time: 10 Dry high-speed intermittent cutting test of alloy 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: 1.5 mm, Feed : 0.3 mm / rev, cutting time: 10 minutes, and a dry high-speed interrupted cutting test of stainless steel was performed.

Further, the coated cermet tools 7-1 of the present invention.
2 and the conventional coated cermet tools 7 to 12, the work material: JIS SCM440, a longitudinally-elongated round bar with four longitudinal grooves, cutting speed: 350 m / min, cutting depth: 0.5 mm, feed: 0. 4 mm / rev, cutting time: 10 minutes, dry high-speed intermittent cutting test of alloy steel under the following conditions: Work material: JIS SUS304, 4 longitudinally-spaced round bars at regular intervals in the longitudinal direction, Cutting speed: 350 m / min , Depth of cut: 0.5 mm, feed: 0.3 mm / rev, cutting time: 10 minutes, dry high-speed intermittent cutting test of stainless steel under the following conditions: In all cutting tests, the flank wear width of the cutting edge is measured. did. Table 6 shows the measurement results.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

[0017]

[Table 4]

[0018]

[Table 5]

[0019]

[Table 6]

[0020]

As can be seen from the results shown in Tables 4 to 6, the coated cermet tools 1 to 12 of the present invention in which the V-carbon / nitride layer was formed as the outermost layer had extremely high thermal mechanical shock and high heat generation. In the accompanying high-speed intermittent cutting of steel, the V-carbon / nitride layer is oxidized to V ₂ O ₅ , which melts and turns into countless fine cracks in the Al ₂ O ₃ layer that forms the upper layer of the hard coating layer. As a result, the thermal mechanical impact on the Al ₂ O ₃ layer is reduced, so that the occurrence of chipping of the cutting edge due to fine cracks in the Al ₂ O ₃ layer is significantly suppressed,
On the other hand, in the conventional coated cermet tools 1 to 12 without the formation of the V-carbon / nitride layer, fine cracks in the Al ₂ O ₃ layer are thermally damaged in high-speed interrupted cutting, while exhibiting excellent wear resistance. It is apparent that it cannot withstand a mechanical shock, which causes chipping to be easily generated in the cutting edge portion, which leads to a short service life in a relatively short time. As mentioned above,
The coated cermet tool of the present invention can be used not only for continuous cutting and interrupted cutting under ordinary conditions such as various types of steel and cast iron, but also for cutting conditions involving extremely high thermal mechanical shock and high heat generation. Excellent cutting performance is exhibited even in severe high-speed intermittent cutting. Therefore, it is possible to satisfactorily cope with high performance of a cutting device, labor saving and energy saving of cutting work, and cost reduction.

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Claims (1)

[Claims] 1. A tool base comprising a tungsten carbide based cemented carbide or a titanium carbonitride based cermet,
A lower layer of a Ti compound layer consisting of a single layer or a multilayer of two or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer; The hard coating layer composed of the upper layer of the aluminum oxide layer is 3 to 20;
In a surface-coated cemented carbide cutting tool formed by chemical vapor deposition and / or physical vapor deposition with an average layer thickness of μm, a carbide of V as an outermost layer on the surface of the aluminum oxide layer constituting the upper layer of the hard coating layer Chemical vapor deposition or physical vapor deposition of a V-carbon / nitride layer comprising a single layer or a multilayer of two or more of a layer, a nitride layer, and a carbonitride layer with an average layer thickness of 0.1 to 5 μm. A cutting tool made of surface-coated cermet, in which a hard coating layer exhibiting excellent chipping resistance.