JP2007276079A - HIGH-HARDNESS MACHINING CUTTING TOOL MADE OF CUBIC BORON NITRIDE GROUP CERAMICS HAVING EXCELLENT BRAZING BONDING STRENGTH, AND Ag ALLOY BRAZING MAERIAL TO BE USED FOR THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-hardness machining cutting tool made of cubic boron nitride group ceramics having excellent brazing bonding strength and abrasion resistance and hardly dropping a brazed part even under the hard cutting condition, and also to provide an Ag alloy brazing material to be used for the cutting tool. <P>SOLUTION: A cutting blade tip 2 made of cubic boron nitride group ceramics is brazed to an alloy tip 3 made of tungsten carbide group hard metal by using the Ag alloy brazing material. The Ag alloy brazing material comprises Cu of 10-30%, Ti of 2-10% and Ni of 1-4% in mass%, and the residual part comprises Ag and unavoidable impurity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cubic boron nitride based ceramic cutting tool for high-hardness machining excellent in brazing joint strength, and a high-hardness machining excellent in brazing joint strength. The present invention relates to an Ag alloy brazing material suitably used for a cubic boron nitride based ceramic cutting tool.

Conventionally, a cutting edge tip made of cubic boron nitride base (cBN base) ceramic is formed as a tool for cutting a hard material, and this tip is made of tungsten carbide base (WC base) using an Ag alloy brazing material. A cutting tool formed by brazing a hard alloy base metal chip is known.
Further, as an example of an Ag alloy brazing material used when brazing the cutting edge tip to a WC-base cemented carbide base metal tip, it contains Cu: 20 to 40% in mass%, with the balance being Ag. What is made into the component composition which consists of an unavoidable impurity is known.

  Further, in the case of the Ag alloy brazing material having the above composition, when a cutting edge tip made of cBN-based ceramic is directly brazed to a base metal tip made of a WC-based cemented carbide, it can be joined with a high brazing strength that can withstand practical use. There is a possibility that it cannot be done. For this reason, using an ultra-high pressure sintering apparatus, an integral structure cutting edge tip composed of two layers of a cBN-based ceramics upper layer and a WC-based cemented carbide lower layer is formed. There has been proposed a cutting tool configured to be brazed to a WC-base cemented carbide base metal tip using By setting it as such a structure, since WC base cemented carbides are brazed, high brazing joining strength is ensured.

  However, in a cutting tool using a cutting blade tip having a two-layer integrated structure as described above, a binder phase forming component such as Co contained in the WC-based cemented carbide forming the lower layer during sintering of the cutting blade tip, Since it diffuses into the cBN-based ceramics forming the upper layer, there is a problem in that the progress of wear of the upper layer becomes remarkable during actual use, and the desired excellent wear resistance cannot be exhibited over a long period of time.

In order to improve such a problem of wear resistance, in a cutting tool in which a cutting tip made of cBN base ceramics is directly brazed to a base metal tip made of WC base cemented carbide using an Ag alloy brazing material, an Ag alloy is used. There has been proposed a cutting tool in which brazing material contains Cu: 10 to 40% and Ti: 1 to 20% by mass, and the balance is composed of Ag and inevitable impurities (for example, a patent) Reference 1).
JP-A-7-124804

  According to the cutting tool described in Patent Document 1, the above-described composition of the Ag alloy brazing material improves the wettability compared to the conventionally used Ag alloy brazing material. Even when the blade tip is directly brazed to the WC-base cemented carbide base metal tip, high brazing joint strength can be ensured. As a result, the cutting edge tip can be composed of only one layer made of cBN-based ceramics, so that components such as Co do not diffuse into the cBN-based ceramics by sintering with the WC-based cemented carbide. The wear resistance can be improved.

  However, with the component composition of the Ag alloy brazing material used in the cutting tool described in Patent Document 1, the wettability is never sufficient, and a cBN-based ceramic cutting tip and a WC-based cemented carbide base metal tip and Since the brazing material was not sufficiently distributed (around) to the joints, it was difficult to obtain high brazing joint strength.

  In recent years, the strength of a material to be cut such as a metal machined using a cutting tool has been remarkably improved, and therefore the temperature during cutting tends to increase. For this reason, when using a cutting tool in which the cutting edge tip is brazed to the WC-based cemented carbide base metal tip using the Ag alloy brazing material having the above-described composition, deep cutting into the workpiece When severe processing such as the above is performed, the cutting edge tip may be peeled off and scattered from the WC-base cemented carbide base metal tip, making it impossible to process.

  The present invention has been made in view of the above circumstances, and has excellent wear resistance, and the brazing portion is difficult to fall off even under severe cutting conditions, and has high brazing joint strength. It is an object of the present invention to provide an Ag alloy brazing material suitably used for a boron-based ceramic cutting tool and a cubic boron nitride-based ceramic cutting tool for high hardness machining excellent in brazing joint strength.

  The cubic boron nitride-based ceramic cutting tool for high-hardness machining with excellent brazing joint strength according to the present invention comprises a cubic boron nitride-based ceramic cutting blade tip, a tungsten carbide-based cemented carbide base metal tip, and an Ag alloy brazing. A cubic boron nitride-based ceramic cutting tool formed by brazing using a material, wherein the Ag alloy brazing material is, by mass, Cu: 10 to 30%, Ti: 2 to 10%, Ni: 1 to 4% is contained, and the balance is made of Ag and inevitable impurities.

According to the above configuration, the Ag alloy brazing material has a component composition containing Ti: 2 to 10% and Ni: 1 to 4% by mass, respectively, thereby improving the wettability of the brazing material. The spread (around) of the brazing material at the joint is improved.
This improves the brazing strength between the cBN-based ceramic cutting edge tip and the WC-base cemented carbide base metal tip.

  The cubic boron nitride based ceramic cutting tool for high hardness machining excellent in brazing joint strength according to the present invention is the cubic boron nitride based ceramic cutting tool for high hardness machining excellent in brazing joint strength according to claim 1. And the surface is coat | covered with any 1 type, or 2 or more types chosen from the group of TiN, TiAlN, and TiCN.

  According to the above configuration, the strength of the cutting tool is further improved by coating the cutting tool with the above-described material, and in particular, between the cBN-based ceramic cutting edge tip and the WC-based cemented carbide base metal tip. The bonding strength becomes stronger.

  The Ag alloy brazing material used in the cutting tool of the present invention is an Ag alloy brazing material that brazes a ceramic cutting edge tip to a tungsten carbide based cemented carbide base metal tip, and is Cu: 10 in mass%. -30%, Ti: 2 to 10%, Ni: 1 to 4%, respectively, and the balance is made of Ag and inevitable impurities.

According to the above configuration, the Ag alloy brazing material has a component composition containing Ti: 2 to 10% and Ni: 1 to 4% in mass%, so that the wettability is improved and the joint portion is formed. The spreadability of brazing filler metal in is improved.
For this reason, when this Ag alloy brazing material is used to braze and join a cBN-based ceramic cutting edge tip and a WC-based cemented carbide base metal tip, the brazing joint strength becomes strong.

According to the cutting tool made of cubic boron nitride based ceramics for high hardness machining having excellent brazing joint strength according to the present invention, the cBN based ceramic cutting edge tip is made of a WC based cemented carbide base metal tip due to the above-described configuration and action. Therefore, even when a high-strength material to be cut is deep-cut, the peeling and dropping of the cutting edge tip from the base metal tip, breakage, and the like are unlikely to occur.
Therefore, it is possible to obtain a long-life cutting tool that is excellent in workability of the workpiece and has high durability.

  Embodiments of a cubic boron nitride based ceramic cutting tool for high hardness machining excellent in brazing joint strength according to the present invention and an Ag alloy brazing material used for the cutting tool will be described below with reference to the drawings. .

[First Embodiment]
Hereinafter, the cubic boron nitride-based ceramic cutting tool for high-hardness machining (hereinafter sometimes abbreviated as a cutting tool) having excellent brazing joint strength according to the present invention, and an Ag alloy brazing material (hereinafter referred to as a cutting tool for ceramics) (hereinafter referred to as a cutting tool). A first embodiment (which may be abbreviated as an Ag alloy brazing material) will be described in detail with reference to FIGS.

<Cubic boron nitride based ceramic cutting tool>
As shown in FIG. 1, the cutting tool 1 of the present embodiment includes a cubic boron nitride-based (cBN-based) ceramic cutting blade tip (hereinafter sometimes abbreviated as a cutting blade tip) 2, a tungsten carbide group ( WC-based cBN-based ceramic cutting tool formed by brazing a cemented carbide base metal chip (hereinafter also referred to as base metal chip) 3 with an Ag alloy brazing material (see reference numeral 4 in FIG. 1). The Ag alloy brazing material contains, in mass%, Cu: 10 to 30%, Ti: 2 to 10%, Ni: 1 to 4%, and the balance of Ag and inevitable impurities. It is said that.

The cutting edge tip 2 functions as a cutting portion when a workpiece is machined using the cutting tool 1, and is formed in a substantially triangular shape in plan view in the example shown in FIG.
The cutting edge tip 2 is made of cubic boron nitride group (cBN group) ceramics, and has high hardness and high mechanical and thermal characteristics. It can be used for high hardness processing.

  The cutting edge tip 2 in the illustrated example is formed in a substantially triangular shape in plan view, but is not limited to this, for example, depending on the shape of a base metal chip to which the cutting edge tip is brazed and joined. Can be determined as appropriate.

The base chip 3 is a pedestal for the cutting edge chip 2 and functions as a mounting portion to the cutting machine. In the example shown in FIG. 1, the base chip 3 is formed in a substantially rectangular rhombus shape in plan view. At the top of the triangle, a step-shaped joint 3a for installing and brazing the cutting edge tip 2 is provided.
The base metal chip 3 is made of a tungsten carbide group (WC group) cemented carbide and contains Co or the like as a binder phase forming component.
In the example shown in FIG. 1, the base metal tip 3 is formed in a substantially rectangular rhombus shape in plan view, but is not limited thereto, and the base metal tip 3, that is, the cutting tool 1 is fixed, for example, in a triangular shape. It can be determined as appropriate according to the shape specifications of the cutting machine to be performed.

The Ag alloy brazing material (see reference numeral 4 in FIG. 1) is a brazing material for brazing and joining the cutting edge tip 2 to the base metal tip 3.
The Ag alloy brazing material of the present invention has excellent brazing properties and brazing joint strength by using the component composition described in detail later. The brazing joint strength is improved by brazing the cBN-based ceramic cutting blade tip 2 to the WC cemented carbide base metal tip 3 using the Ag alloy brazing material of the present invention.

<Ag alloy brazing material used for cutting tools>
Hereinafter, the reasons for limitation of the component composition of the Ag alloy brazing material of the present invention will be described.
The Ag alloy brazing material of the present invention contains Ag, and contains Cu, Ti, and Ni as main constituent elements individually in specified amounts. In addition, content of each element described below is mass% unless otherwise specified, and includes an upper limit and a lower limit unless otherwise specified. Therefore, for example, 10 to 50% means 10% or more and 50% or less.

"Cu" 10-50%
Cu (copper) has an effect of lowering the melting point of the Ag alloy brazing material and enabling brazing at a low temperature.
If the Cu content is less than 10% by mass, it is difficult to obtain the effect of the above-described action. If the Cu content exceeds 40%, the Ag content is relatively low, and high bonding is achieved by Ag. Since strength falls rapidly, the content was specified in the range of 10 to 40%.
Moreover, the more preferable range of Cu content is 20 to 30%.

"Ti" 2-12%
Ti (titanium) improves the wettability of the Ag alloy brazing material to the cBN-based ceramic cutting edge tip and the WC-base cemented carbide base metal tip, and has the effect of improving the brazing joint strength.
If the Ti content is less than 2% by mass, the effect of the above-described action is difficult to obtain, and if it exceeds 12%, the brazing joint strength decreases, so the content is 2 to 12%. Stipulated in the range.
A more preferable range of the Ti content is 2 to 5%.

"Ni" 1-4%
Ni (nickel) remarkably improves the wettability of the Ag alloy brazing material to the cBN-based ceramic cutting edge tip and the WC-base cemented carbide base metal tip, and improves the spread of the brazing material at the joint. It has the effect of improving the adhesion strength.
If the Ni content is less than 1% by mass, the effect of the above-described action is difficult to obtain, and if it exceeds 4%, the working temperature during brazing increases, and cBN groups resulting from brazing Damage to the ceramic cutting edge tip is likely to occur.

As described above, according to the cubic boron nitride-based ceramic cutting tool 1 for high-hardness machining excellent in brazing joint strength of the present embodiment, the cutting tip 2 made of cBN-based ceramic is obtained by the above-described configuration and operation. Is firmly brazed to the base metal tip 3 made of the WC-base cemented carbide, so that the cutting edge tip 2 is the base metal tip 3 even when a high-strength workpiece is deep-cut. It will not peel off, fall off or break.
Therefore, it is possible to obtain a long-life cutting tool that is excellent in workability of the workpiece and has high durability.
Moreover, according to the Ag alloy brazing material used for the cutting tool of the present embodiment, the brazing filler metal component has the above-described component composition, and in particular, by containing Ni in a range of 1 to 4% by mass%, wettability is achieved. A brazing material that is excellent and has a good distribution (around) of the brazing material at the joint can be obtained.
Therefore, by making the cutting tool a structure in which the cutting edge tip is brazed and joined to the base metal tip using the Ag alloy brazing material of the present embodiment, the workability of the cutting material of the cutting tool is improved, Durability is improved and long life can be realized.

In the example shown in FIG. 1, the entire cutting edge tip 2 is made of cBN-based ceramics, but the cutting tool of the present invention is not limited to this.
For example, as in the cutting tool 10 shown in FIG. 2, a cutting edge tip 21 having a structure in which two layers of a cBN layer 21a and a cemented carbide layer 21b made of a CO base are integrally formed by ultra-high pressure sintering is used. Even in this case, by using the Ag alloy brazing material of the present invention, it is possible to braze to a base metal chip 3 described later with high bonding strength.

  Here, the cutting tool 10 is such that the cemented carbide layer 21b becomes a brazed joint portion to the base metal chip 3 and brazes between the CO-based cemented carbide alloys, so that the brazed joint strength is increased. However, as described above, components such as Co may diffuse from the cemented carbide layer 21b into the cBN layer 21a during the ultra-high pressure sintering process. For this reason, when considering the wear resistance and the like of the cutting edge tip, it is preferable to use the cutting edge tip 1 having a single layer structure as a whole made of cBN-based ceramics as shown in FIG.

The cutting edge tip is a single-layered cutting edge tip 2 made of cBN-based ceramics as shown in FIG. 1, and when the cutting edge tip 2 is brazed to the base metal tip 3, the brazing temperature is an ultrahigh pressure. It is performed in a vacuum at a relatively low temperature range, for example, at a temperature of 800 to 1100 ° C. compared to the temperature at the time of sintering. For this reason, the binder phase formation part such as Co in the WC-based cemented carbide constituting the base metal chip 3 does not diffuse and move into the cutting edge chip 2, and the excellent mechanical properties of the cBN-based ceramics, etc. Will not be damaged. Therefore, the cutting tool 1 (cutting edge tip 2) of this embodiment can exhibit excellent wear resistance over a long period of time.
Further, by brazing the cutting edge tip 2 to the base metal tip 3 using the Ag alloy brazing material of the present embodiment, even if brazing between the cBN base ceramic and the WC base cemented carbide is high. Brazing joint strength can be realized.

[Second Embodiment]
A second embodiment of the cubic boron nitride based ceramic cutting tool for high hardness machining excellent in brazing joint strength of the present invention will be described below with reference to FIG.
In the following description, the same components as those in the first embodiment are denoted by common reference numerals, and detailed description thereof is omitted.

  The cubic boron nitride based ceramic cutting tool 11 for high hardness machining excellent in brazing joint strength of the present embodiment has a surface of the cBN based ceramic cutting tool 1 as described in the first embodiment, TiN, TiAlN, It is covered with a coating layer 20 composed of any one or two or more selected from the group of TiCN, and is roughly configured.

As described above, the coating layer 20 is made of TiN, TiAlN, TiCN, or the like. In the example illustrated in FIG. 3, the coating layer 20 is provided so as to cover the entire surface of the cutting tool 1.
As a method for coating the coating layer 20, various selections such as PVD coating can be used.
By using the cutting tool 11 coated with the above-mentioned material as the cutting tool, the strength of the entire cutting tool is further improved, and in particular, the cutting edge tip 2 made of cBN-based ceramics and the base made of WC-based cemented carbide. The bonding strength between the gold chip 3 becomes stronger.

  In addition, in the cutting tool 11 of this embodiment, although the coating layer 20 is provided so that the whole surface of the cutting tool 1 may be covered, it is not limited to this. For example, the coating layer can be configured to be provided only on the periphery of the joint 3 a of the cutting edge tip 2 and the base metal tip 3 of the cutting tool 1 and can be determined as appropriate.

The cubic boron nitride-based ceramic cutting tool 11 for high-hardness machining with excellent brazing joint strength according to the present embodiment can be used for machining a workpiece under particularly severe cutting conditions by the above-described configuration and operation. Further, peeling and dropping of the cutting edge tip 2 from the base metal tip 3, breakage, etc. are unlikely to occur.
Therefore, it is possible to obtain a long-life cutting tool that is excellent in workability of the workpiece and has high durability.

Hereinafter, the present invention will be described in more detail with respect to the cubic boron nitride based ceramic cutting tool for high hardness machining excellent in brazing joint strength of the present invention and the Ag alloy brazing material used for the cutting tool. The present invention is not limited to this embodiment.
In this example, first, a cutting edge tip and a base metal tip are prepared with a predetermined component composition, and an Ag alloy brazing material is prepared with each component composition shown in Tables 1 to 3 below. A cutting tool as shown in FIG. And each evaluation test demonstrated below was done.

[Production of cutting tools]
First, cBN powder, TiC powder, TiN powder, Al ₂ O ₃ powder, AlN powder, and TiB ₂ powder each having an average particle diameter in the range of 1 to 1.5 μm are prepared as raw material powders. The powder was blended into a predetermined component composition and mixed, and then pressed into a green compact having a diameter of 20 mmφ × thickness of 2 mm. Next, the green compact after molding was sintered under the conditions of a temperature: 1300 ° C., a pressure: 5.5 GPa, and a time: 30 minutes using an ultrahigh pressure generator. A cutting edge tip using a coating (coating) cBN as a base material, which is used in each example and comparative example, by cutting into a plane shape: a regular triangle with a side length of 4 cm × thickness: 2 mm. Produced.

In addition, as raw material powders, WC powder, TiC powder, TaC powder, VC powder, Cr ₃ C ₂ powder, and Co powder, all having an average particle diameter in the range of 0.5 to 4 μm, are prepared. Were mixed in a predetermined component composition and mixed, and then pressed into a green compact having a predetermined shape. Next, the green compact after molding was sintered in a vacuum at a temperature of 1370 ° C. for 30 minutes. Planar shape: regular triangle with a side length of 15.9 mm × thickness: 4.76 mm The sintered body was formed. Then, a notch having a depth of 2 mm corresponding to the shape of the cutting edge tip is formed in one corner of any one of the upper and lower parallel surfaces of the sintered body using a grinding machine. Base metal chips used in Examples and Comparative Examples were produced.

  Furthermore, after preparing a molten Ag alloy having the composition shown in the following Tables 1 to 3 in a normal electric furnace, it is cast into an ingot and rolled to form a 0.2 mm thick Ag alloy brazing material arc. Were prepared.

And the cutting edge chip | tip and the base metal chip | tip were brazed and joined by the combination shown to the following Tables 1-3 using each Ag alloy brazing material arc. In this case, the brazing treatment was performed under a condition of holding in a vacuum at a temperature of 950 ° C. for 5 minutes.
In this way, a cBN-based ceramic cutting blade using an Ag alloy brazing material (see reference numeral 4) of each component composition for the WC-base cemented carbide base metal chip 3 as shown by reference numeral 1 in FIG. Cutting tools (bite) of each Example (1-17) and Comparative Example (1-16) formed by brazing the chip 2 were produced.
In addition, about the cutting tools of Examples 9-11 and Comparative Examples 8-9, the coating layer of the component composition shown in Table 2 was provided on the cutting tool surface like the cutting tool of the code | symbol 11 shown in FIG. .

[Evaluation test items]
Using the cutting tools of Examples 1 to 17 and Comparative Examples 1 to 16, using a round bar (φ80 mm) of a carburized and quenched material (hardness: HR C60) of SCM415 as the material to be cut, the following cutting conditions An evaluation test was conducted.
In Examples 1 to 5 and Comparative Examples 1 to 5, a slit width of 8 mm × depth of 20 mm along the round bar length direction is intermittently formed in a total of 8 locations on the outer periphery of the SCM 415. In each of the other examples and comparative examples, a test was performed using a round bar to-be-cut material without slits.
In all the evaluation tests described below, dry cutting was performed without using cutting oil.

<Intermittent cutting test: Evaluation with a round bar with intermittent slit formation>
Using the cutting tools of Examples 1 to 5 and Comparative Examples 1 to 5, a round bar having slits formed intermittently as described above was used as a workpiece, cutting speed: 120 m / min., Feed: 0.15 mm / rev., cutting: A dry cutting process was performed under the condition of 1.0 mm, and the time required until the cutting edge chip was damaged (peeling, etc.) was measured.
The results are shown in Table 1 below.

<Continuous cutting test: Evaluation by continuous cutting and presence / absence of coating layer>
Using the cutting tools of Examples 6 to 11 and Comparative Examples 6 to 10, a round bar without slits was used as a workpiece, cutting speed: 200 m / min., Feed: 0.15 mm / rev., Cutting: The dry continuous cutting was performed under the condition of 1.0 mm, and the time required until the cutting edge chip was damaged was measured.
The results are shown in Table 2 below.

<Continuous cutting test: Evaluation by Ni content of Ag alloy brazing material>
Using the cutting tools of Examples 12 to 17 and Comparative Examples 11 to 16, a round bar without slits was used as a material to be cut, cutting speed: 200 m / min., Feed: 0.15 mm / rev., Cutting: Dry continuous cutting was performed under the condition of 1.0 mm, and the time required until the cutting tip was damaged and the processing could not be continued or was difficult was measured.
The results are shown in Table 3 below.

[Evaluation results]
As shown in Table 1, in the intermittent cutting test for cutting a round bar formed with intermittent slits, the cutting tool of the present invention shown in Examples 1 to 5 is the conventional Ag alloy brazing material shown in Comparative Examples 1 to 5. Compared with the cutting tool produced using the cutting tool, the cutting time until the cutting edge tip is damaged and machining becomes difficult is longer.
From the above results, it is clear that the cutting tool of the present invention is excellent in durability in intermittent cutting.

Moreover, as shown in Table 2, in the continuous cutting test which cuts a round bar without a slit, the cutting tool of the present invention (without the coating layer) shown in Examples 6 to 8 is damaged by the cutting edge tip. The cutting time until it becomes difficult is all 80 seconds or more, while the cutting tool (without the coating layer) manufactured using the conventional Ag alloy brazing material shown in Comparative Examples 6 and 7 has a cutting edge tip. The cutting time until the processing was impossible due to damage was 65 seconds or less.
From the above results, it is clear that the cutting tool of the present invention is excellent in durability in continuous cutting.
Furthermore, the cutting tool of the present invention whose surface is covered with a coating layer made of TiAlN shown in Examples 9 to 11 has a cutting time of 200 seconds or longer until the cutting edge tip is damaged and machining becomes difficult. On the other hand, when the surface of the cutting tool produced using the conventional Ag alloy brazing material shown in Comparative Examples 8 to 10 was coated with a coating layer made of TiAlN, the cutting edge tip was damaged and the processing was not successful. The cutting time until it was possible was in the range of 130-170 seconds.
From the above results, it is clear that the cutting tool of the present invention in which the coating layer is provided on the surface has continuous durability in continuous cutting.

Moreover, as shown in Table 3, the cutting tools of Examples 12 to 17 in which the content of Ni contained in the Ag alloy brazing material is in the range of 1 to 4% by mass are as follows. The cutting time until damage and machining became difficult was 38 seconds or more.
In contrast, in the cutting tools of Comparative Examples 11 and 12 and Comparative Examples 13 to 16 in which the Ni content in the Ag alloy brazing material is outside the range defined in the present invention, the cutting edge tip is damaged and the cutting tool is damaged. Cutting time until it became impossible was in the range of 12 to 33.4 seconds.
From the above results, the cutting tool of the present invention in which the cutting tip is brazed to the base metal tip using the Ag alloy brazing material having the composition defined in the present invention and containing Ni in the range of 1 to 4%. However, it is clear that it is excellent in durability.

  From the results of the evaluation tests described above, it is clear that the cubic boron nitride based ceramic cutting tool for high hardness machining excellent in brazing joint strength of the present invention has excellent durability and long life. In addition, it is apparent that the Ag alloy brazing material used in the cutting tool of the present invention has high wettability, good spread of the brazing material, and excellent brazing joint strength.

It is the schematic explaining an example of the cubic boron nitride base ceramic cutting tool for high-hardness processing excellent in the brazing joint strength of this invention. It is the schematic explaining the other example of the cubic boron nitride base ceramic cutting tool for high-hardness processing excellent in the brazing joint strength of this invention. It is the schematic explaining the other example of the cubic boron nitride base ceramic cutting tool for high-hardness processing excellent in the brazing joint strength of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 10, 11 ... Cubic boron nitride group (cBN group) ceramic cutting tool (cutting tool), 2, 21 ... Cubic boron nitride group (cBN group) ceramic cutting edge chip (cutting edge chip), 3 ... Carbonization Tungsten-base (WC-base) cemented carbide base metal chip (base metal chip), 4 ... Ag alloy brazing material, 20 ... coating layer

Claims (3)

A cubic boron nitride-based ceramic cutting tool formed by brazing a cubic boron nitride-based ceramic cutting blade tip to a tungsten carbide-based cemented carbide base metal tip using an Ag alloy brazing material,
The Ag alloy brazing material contains, by mass%, Cu: 10 to 30%, Ti: 2 to 10%, Ni: 1 to 4%, respectively, and the balance is made of Ag and inevitable impurities. Cubic boron nitride based ceramic cutting tool for high hardness machining with excellent brazing joint strength. A cubic boron nitride based ceramic cutting tool for high-hardness machining excellent in brazing joint strength according to claim 1,
A cubic boron nitride-based ceramic cutting tool for high-hardness machining excellent in brazing joint strength, characterized in that the surface is coated with one or more selected from the group consisting of TiN, TiAlN, and TiCN . An Ag alloy brazing material for brazing a ceramic cutting edge chip to a tungsten carbide base cemented carbide base metal chip,
It is excellent in brazing joint strength characterized by containing Cu: 10 to 30%, Ti: 2 to 10%, Ni: 1 to 4%, and the balance consisting of Ag and inevitable impurities. Ag alloy brazing material used for high-hardness ceramic cutting tools.

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