JP2011045954A

JP2011045954A - Cermet sintered body and cutting tool

Info

Publication number: JP2011045954A
Application number: JP2009196352A
Authority: JP
Inventors: Takashi Tokunaga; 隆司徳永
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2009-08-27
Filing date: 2009-08-27
Publication date: 2011-03-10

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cermet sintered body and a cutting tool having a structure with high cutting performance, suppressing deformation of the sintered body, and easy to produce even a complicated form. <P>SOLUTION: The cutting tool 1 is formed of the cermet sintered body of a composite structure composed of a first cermet 2 and a second cermet 3 arranged in the outer periphery and constituting a cutting blade 7, in which the first cermet 2 and the second cermet 3 are composed of a hard phase 5 formed of carbonitride and the like including one or more metal in the group 4, 5 or 6 of the periodic table and a binder phase 6 formed mainly of an iron group metal, the hard phase 5 is formed of a first hard phase 5a with a main composition of TiCN and a second hard phase 5b of a solid solution of composite carbonitride of one or more metal in the group 4, 5 or 6 of the periodic table and Ti, the existence ratio of the second hard phase 5b of the second cermet 3 is higher than that of the first cermet 2, and the existence ratio of the binder phase 6 of the first cermet 2 is lower than that of the second cermet 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明はサーメット焼結体および切削工具に関する。 The present invention relates to a cermet sintered body and a cutting tool.

現在、切削工具としてＴｉを主成分とするサーメット焼結体が広く使われている。サーメットの硬質相は芯部と周辺部とからなる有芯構造をとりやすいことが知られているが、例えば、特許文献１では、周辺部の面積割合が多いほど、鋳鉄との耐化学反応性が向上することが開示され、周辺部の平均粒径／芯部の平均粒径の比率を３〜８としたサーメットが記載されている。 At present, cermet sintered bodies mainly composed of Ti are widely used as cutting tools. Although it is known that the hard phase of cermet tends to have a cored structure composed of a core part and a peripheral part, for example, in Patent Document 1, as the area ratio of the peripheral part increases, the chemical reactivity with cast iron increases. Is disclosed, and cermets are described in which the ratio of the average particle diameter of the peripheral part / the average particle diameter of the core part is 3 to 8.

特開２００４−２８５４２１号公報JP 2004-285421 A

しかしながら、特許文献１のように周辺部の面積比率を多くするにはサーメットの焼成温度を高くする必要があるが、焼成温度を高くすると、焼成中に生じる金属原子の移動や窒素原子の拡散の影響で、焼結体が元の成形体の形状から大きく変形してしまうという問題があった。焼結体が変形した場合、焼結体の表面を研磨加工して形状を整える方法もあるが、製造コストがかさむとともに複雑な形状の切削工具の場合には研磨加工自体が困難であった。 However, as in Patent Document 1, in order to increase the area ratio of the peripheral part, it is necessary to increase the cermet firing temperature. However, if the firing temperature is increased, the movement of metal atoms and the diffusion of nitrogen atoms that occur during firing are increased. Due to the influence, there was a problem that the sintered body was greatly deformed from the shape of the original molded body. When the sintered body is deformed, there is a method of adjusting the shape by polishing the surface of the sintered body. However, the manufacturing cost increases, and in the case of a cutting tool having a complicated shape, the polishing process itself is difficult.

本発明は上記問題を解決するためのものであり、その目的は切削性能が高い組織を有するとともに、焼結体の変形を抑制できて複雑な形状でも容易に作製可能なサーメット焼結体および切削工具を提供することである。 The present invention is intended to solve the above-mentioned problems, and its purpose is to provide a cermet sintered body that has a structure with high cutting performance and that can suppress deformation of the sintered body and can be easily produced even in a complicated shape. Is to provide a tool.

本発明のサーメット焼結体は、第１サーメットと、該第１サーメットの外周に配置されて少なくとも切刃を構成する第２サーメットとが積層されてなり、
前記第１サーメットおよび前記第２サーメットは、周期表第４、５および６族金属のうちの１種以上の炭化物、窒化物、炭窒化物およびこれらの固溶体の中から選ばれた１種以上からなる硬質相と、主として鉄族金属からなる結合相とから構成され、前記硬質相は、ＴｉＣＮを主成分とする第１硬質相と、周期表第４、５および６族金属の少なくとも1種とＴｉとの複合炭窒化物固溶体の第２硬質相とからなり、
前記第２サーメットは前記第１サーメットよりも前記第２硬質相の存在割合が多く、前記第１サーメットは前記第２サーメットよりも前記結合相の存在割合が少ないものである。 The cermet sintered body of the present invention is formed by laminating a first cermet and a second cermet disposed on the outer periphery of the first cermet and constituting at least a cutting edge,
The first cermet and the second cermet may be one or more selected from one or more carbides, nitrides, carbonitrides, and solid solutions of the metals in Groups 4, 5, and 6 of the periodic table. The hard phase is composed of a first hard phase mainly composed of TiCN and at least one of Group 4, 5 and 6 metals of the periodic table. Comprising a second hard phase of a composite carbonitride solid solution with Ti,
The second cermet has a higher proportion of the second hard phase than the first cermet, and the first cermet has a lower proportion of the binder phase than the second cermet.

ここで、前記第２サーメットの厚みは０．５〜２ｍｍであることが望ましい。 Here, the thickness of the second cermet is preferably 0.5 to 2 mm.

また、前記第２サーメットには、表面側に、前記第２硬質相の存在割合が多く、かつ前記結合相の存在割合が少ない表面領域が存在することが望ましい。 Moreover, it is desirable that the second cermet has a surface region on the surface side in which the second hard phase is present in a large proportion and the binder phase is present in a small proportion.

さらに、前記第１サーメットの硬度が前記第２サーメットの硬度より高く、かつ前記第２サーメットの前記表面領域の硬度が前記第２サーメットの前記第１サーメット側の硬度よりも高いことが望ましい。 Furthermore, it is desirable that the hardness of the first cermet is higher than the hardness of the second cermet, and the hardness of the surface region of the second cermet is higher than the hardness of the second cermet on the first cermet side.

また、前記第１サーメットにおける前記硬質相の平均粒径が前記第２サーメットにおける前記硬質相の平均粒径より大きく、かつ前記第２サーメットの前記表面領域における前記硬質相の平均粒径が前記第２サーメットの前記第１サーメット側における前記硬質相の平均粒径よりも大きいことが望ましい。 The average particle size of the hard phase in the first cermet is larger than the average particle size of the hard phase in the second cermet, and the average particle size of the hard phase in the surface region of the second cermet is It is desirable that the average particle size of the hard phase on the first cermet side of 2 cermets be larger.

さらに、前記第１サーメットと前記第２サーメットとの境界に界面が存在し、かつ前記第２サーメットの前記表面領域と前記第１サーメット側の領域との境界には界面が存在しない構成となっている。 Further, an interface exists at the boundary between the first cermet and the second cermet, and no interface exists at the boundary between the surface region of the second cermet and the region on the first cermet side. Yes.

また、本発明の切削工具は、周期表第４、５および６族金属のうちの１種以上の炭化物、窒化物、炭窒化物およびこれらの固溶体の中から選ばれた１種以上からなる硬質相と、主として鉄族金属からなる結合相との焼結体から構成され、前記硬質相は、ＴｉＣＮを主成分とする第１硬質相と、周期表第４、５および６族金属の少なくとも1種とＴｉとの複合炭窒化物固溶体の第２硬質相とからなり、
切刃を含む逃げ面およびその近傍領域をＡ領域とし、該Ａ領域以外の領域である前記焼結体の内部およびすくい面の中央部位をＢ領域としたとき、前記Ａ領域では前記Ｂ領域よりも前記第２硬質相の存在割合が多く、前記Ｂ領域では前記Ａ領域よりも前記結合相の存在割合が少ないものである。 Further, the cutting tool of the present invention is a hard material composed of one or more selected from the group consisting of one or more carbides, nitrides, carbonitrides and solid solutions of the metals in Groups 4, 5 and 6 of the periodic table. The hard phase is composed of a first hard phase mainly composed of TiCN and at least one of Group 4, 5, and 6 metals of the periodic table. A second hard phase of a composite carbonitride solid solution of seeds and Ti,
When the flank including the cutting edge and the area near the flank are designated as A area, and the inside of the sintered body and the central part of the rake face other than the A area are designated as B area, the A area is more than the B area. The second hard phase has a large proportion, and the B region has a smaller proportion of the binder phase than the A region.

ここで、断面組織観察にて、前記Ａ領域における前記第１硬質相の面積比率をＳ_１Ａ、該第２硬質相の面積比率をＳ_２Ａとし、前記Ｂ領域における前記第１硬質相の面積比率をＳ_１Ｂ、前記第２硬質相の面積比率をＳ_２Ｂとしたとき、前記Ｓ_１Ａと前記Ｓ_２Ａとの比率（Ｓ_２Ａ／Ｓ_１Ａ）が２〜８であり、前記Ｓ_１Ｂと前記Ｓ_２Ｂとの比率（Ｓ_２Ｂ／Ｓ_１Ｂ）が０．３〜０．９５であることが望ましい。 Here, in cross-sectional structure observation, the area ratio of the first hard phase in the A region is S _1A , the area ratio of the second hard phase is S _2A, and the area ratio of the first hard phase in the B region the _{S 1B,} when the area ratio of the second hard phase was _{S 2B,} the a ratio _{_(S} 2A _/ S _1A) from 2 to 8 and _{S 1A} and the _{S 2A,} the _{S 1B} and the _{S 2B} The ratio (S _2B / S _1B ) is preferably 0.3 to 0.95.

また、前記Ａ領域は前記逃げ面から５〜１００μｍの厚みで存在することが望ましい。 Moreover, it is desirable that the region A exists with a thickness of 5 to 100 μm from the flank.

さらに、前記Ａ領域と前記Ｂ領域との間に、前記Ｂ領域よりも前記第２硬質相の存在割合が少なく、かつ前記Ａ領域よりも前記結合相の存在割合が多いＣ領域が、１０００μｍ以下の厚みで存在することが望ましい。 Furthermore, between the A region and the B region, the C region having a smaller proportion of the second hard phase than the B region and a larger proportion of the binder phase than the A region is 1000 μm or less. It is desirable that it exists in the thickness.

また、前記Ａ領域の硬度が前記Ｃ領域の硬度よりも高く、かつ前記Ｂ領域の硬度が前記Ｃ領域の硬度よりも高いことが望ましい。 Moreover, it is desirable that the hardness of the A region is higher than the hardness of the C region, and the hardness of the B region is higher than the hardness of the C region.

さらに、前記Ａ領域における前記硬質相の平均粒径が前記Ｃ領域における前記硬質相の平均粒径よりも大きく、かつ前記Ｂ領域における前記硬質相の平均粒径が前記Ｃ領域における硬質相の平均粒径よりも大きいことが望ましい。 Further, the average particle size of the hard phase in the A region is larger than the average particle size of the hard phase in the C region, and the average particle size of the hard phase in the B region is the average of the hard phase in the C region. Desirably larger than the particle size.

また、前記Ａ領域と前記Ｃ領域との境界に界面が存在せず、かつ前記Ｂ領域と前記Ｃ領域との境界には界面が存在する構成となっている。 Further, there is no interface at the boundary between the A region and the C region, and there is an interface at the boundary between the B region and the C region.

ここで、本発明のサーメット焼結体の製造方法における第１の実施態様は、異なる２種類の混合原料粉末を調製する工程と、成形金型の空洞部分の中央部に焼成時の収縮が小さい第１の混合原料粉末を充填して圧縮することにより、該第１の混合原料粉末からなる第１の粉末成形体を作製する工程と、前記成形金型の前記第１の粉末成形体の外周部に空隙を設けて、該空隙に前記第１の混合原料粉末よりも焼成時の収縮が大きい第２の混合原料粉末を充填して再度圧縮することにより、前記第１の混合原料粉末の外周部に前記第２の混合原料粉末が配置された複合成形体を作製する工程と、該複合成形体を焼成する工程とを具備する。 Here, in the first embodiment of the method for producing a cermet sintered body of the present invention, the step of preparing two different kinds of mixed raw material powder and the shrinkage at the time of firing are small in the central portion of the cavity portion of the molding die A step of producing a first powder molded body made of the first mixed raw material powder by filling and compressing the first mixed raw material powder, and an outer periphery of the first powder molded body of the molding die An outer periphery of the first mixed raw material powder is formed by providing a void in the portion, filling the void with the second mixed raw material powder having a larger shrinkage during firing than the first mixed raw material powder, and compressing again. A step of producing a composite molded body in which the second mixed raw material powder is disposed in the part, and a step of firing the composite molded body.

また、本発明のサーメット焼結体の製造方法における第２の実施態様は、異なる２種類の混合原料粉末を調製する工程と、成形金型の空洞部分の外周部に焼成時の収縮が大きい第２の混合原料粉末を充填して圧縮することにより、該第２の混合原料粉末からなる第２の粉末成形体を作製する工程と、前記成形金型の前記第２の粉末成形体の内側に空隙を設けて、該空隙に前記第２の混合原料粉末よりも焼成時の収縮が小さい第１の混合原料粉末を充填して再度圧縮することにより、前記第１の混合原料粉末の外周部に前記第２の混合原料粉末が配置された複合成形体を作製する工程と、該複合成形体を焼成する工程とを具備する。 The second embodiment of the method for producing a cermet sintered body according to the present invention includes a step of preparing two different kinds of mixed raw material powders and a large shrinkage during firing at the outer peripheral portion of the cavity portion of the molding die. A step of producing a second powder molded body made of the second mixed raw material powder by filling and compressing the mixed raw material powder of 2, and inside the second powder molded body of the molding die By providing a void, filling the void with the first mixed raw material powder whose shrinkage during firing is smaller than that of the second mixed raw material powder, and compressing again, the outer periphery of the first mixed raw material powder is formed. The method includes a step of producing a composite molded body in which the second mixed raw material powder is disposed, and a step of firing the composite molded body.

なお、前記第２の混合原料粉末の鉄族金属含有量を前記第１の混合原料粉末の鉄族金属含有量よりも多くする、ないしは前記第２の混合原料粉末の平均粒径を前記第１の混合原料粉末の平均粒径よりも小さくすることが望ましい。 The iron group metal content of the second mixed raw material powder is made larger than the iron group metal content of the first mixed raw material powder, or the average particle diameter of the second mixed raw material powder is set to the first mixed powder. It is desirable to make it smaller than the average particle diameter of the mixed raw material powder.

本発明のサーメット焼結体および切削工具によれば、結合相の存在割合が少ない第１サーメットの外周に、第２硬質相の存在割合が多い第２サーメットが配置された構造、すなわち、切刃を含む逃げ面およびその近傍領域をＡ領域、前記Ａ領域以外の領域である焼結体の内部およびすくい面の中央部位をＢ領域としたとき、前記Ａ領域では前記Ｂ領域よりも前記第２硬質相の存在割合が多く、前記Ｂ領域では前記Ａ領域よりも結合相の存在割合が少ない構成からなるので、サーメット焼結体の表面に存在する切刃は切削性能が高い第２サーメットの組織からなるとともに、基体を構成する第１サーメットは焼結による変形が小さいので、焼結体全体の変形を抑制できて複雑な形状でも容易に寸法精度の高い切削工具を作製できる。 According to the cermet sintered body and the cutting tool of the present invention, a structure in which the second cermet having a large content ratio of the second hard phase is arranged on the outer periphery of the first cermet having a small content ratio of the binder phase, that is, the cutting blade. When the flank and its neighboring region are the A region, the inside of the sintered body that is the region other than the A region and the central portion of the rake face are the B region, the A region has the second region than the B region. Since the hard phase has a high proportion and the B region has a smaller binder phase than the A region, the cutting edge present on the surface of the cermet sintered body has a high cutting performance. In addition, since the first cermet constituting the base body is hardly deformed by sintering, the deformation of the entire sintered body can be suppressed, and a cutting tool with high dimensional accuracy can be easily produced even in a complicated shape.

なお、断面組織観察にて、Ａ領域における前記第１硬質相の面積比率をＳ_１Ａ、該第２硬質相の面積比率をＳ_２Ａ、Ｂ領域における前記第１硬質相の面積比率をＳ_１Ｂ、該第２硬質相の面積比率をＳ_２Ｂとしたとき、前記Ｓ_１Ａと前記Ｓ_２Ａとの比率（Ｓ_２Ａ／Ｓ_１Ａ）が２〜８であり、前記Ｓ_１Ｂと前記Ｓ_２Ｂとの比率（Ｓ_２Ｂ／Ｓ_１Ｂ）が０．３〜０．９５であることが、切削性能を高くかつ変形を小さく抑制できる点で望ましい。 In cross-sectional structure observation, the area ratio of the first hard phase in the A region is S _1A , the area ratio of the second hard phase is S _2A , and the area ratio of the first hard phase in the B region is S _1B , When the area ratio of the second hard phase is S _2B , the ratio of S _1A to S _2A (S _2A / S _1A ) is 2 to 8, and the ratio of S _1B to S _2B ( S _2B / S _1B ) is preferably 0.3 to 0.95 in that cutting performance is high and deformation can be suppressed to a low level.

ここで、前記第２サーメットの厚みは０．５〜２ｍｍであることが望ましい。このとき、前記Ａ領域は前記逃げ面から５〜１００μｍの厚みで存在することが、切削性能が高くかつ変形が小さい切削工具が製造上容易に作製できる点で望ましい。 Here, the thickness of the second cermet is preferably 0.5 to 2 mm. At this time, it is desirable that the region A exists in a thickness of 5 to 100 μm from the flank because a cutting tool having high cutting performance and small deformation can be easily manufactured.

また、前記第２サーメットには、表面側に、前記第２硬質相の存在割合が多く、かつ結合相の存在割合が少ない表面領域が存在すること、すなわち前記Ａ領域と前記Ｂ領域との間に、前記Ｂ領域よりも前記第２硬質相の存在割合が少なく、かつ前記Ａ領域よりも結合相の存在割合が多いＣ領域が存在することによって、切削性能をさらに高めることができる点で望ましい。 The second cermet has a surface region on the surface side in which the second hard phase is present in a large proportion and the binder phase is present in a small proportion, that is, between the A region and the B region. Furthermore, it is desirable in that the cutting performance can be further improved by the presence of the C region in which the second hard phase is present in a smaller proportion than the B region and the binder phase is present in a greater proportion than the A region. .

さらに、前記第１サーメットの硬度が前記第２サーメットの硬度より高く、かつ前記第２サーメットの表面領域の硬度が前記第２サーメットの前記第１サーメット側の硬度よりも高いこと、すなわち、前記Ａ領域の硬度が前記Ｃ領域の硬度より高く、かつ前記Ｂ領域の硬度が前記Ｃ領域の硬度よりも高いことが、変形を防止できるとともに切刃の耐摩耗性を高めることができる点で望ましい。 Further, the hardness of the first cermet is higher than the hardness of the second cermet, and the hardness of the surface region of the second cermet is higher than the hardness of the second cermet on the first cermet side, that is, the A It is desirable that the hardness of the region is higher than the hardness of the C region and that the hardness of the B region is higher than the hardness of the C region in that deformation can be prevented and the wear resistance of the cutting edge can be improved.

また、前記第１サーメットにおける硬質相の平均粒径が前記第２サーメットにおける硬質相の平均粒径より大きく、かつ前記第２サーメットの表面領域における硬質相の平均粒径が前記第２サーメットの前記第１サーメット側における硬質相の平均粒径よりも大きいこと、すなわち、前記Ａ領域における硬質相の平均粒径が前記Ｃ領域における硬質相の平均粒径より大きく、かつ前記Ｂ領域における硬質相の平均粒径が前記Ｃ領域における硬質相の平均粒径よりも大きいことが、組織の制御が容易な点で望ましい。 The average particle size of the hard phase in the first cermet is larger than the average particle size of the hard phase in the second cermet, and the average particle size of the hard phase in the surface region of the second cermet is the same as that of the second cermet. Larger than the average particle size of the hard phase on the first cermet side, that is, the average particle size of the hard phase in the A region is larger than the average particle size of the hard phase in the C region, and It is desirable that the average particle size is larger than the average particle size of the hard phase in the C region because the structure can be easily controlled.

なお、本発明の製造方法、すなわち異なる２種類の混合原料粉末を調製し、先に第１の混合原料粉末または第２の混合原料粉末のみを充填して圧縮した後、成形金型の所定部分に空隙を設けて第２の混合原料粉末または第１の混合原料粉末を充填して再度圧縮することにより、前記第１の混合原料粉末の外周部に前記第２の混合原料粉末が配置された複合成形体を作製することによって、前記第１サーメットと前記第２サーメットとの境界に界面が存在し、かつ前記第２サーメットの表面領域と基体側の領域との境界には界面が存在しない構成、すなわち前記Ａ領域と前記Ｃ領域との境界に界面が存在せず、かつ前記Ｂ領域と前記Ｃ領域との境界には界面が存在する構成となっている。この製造方法によれば、切削性能が高くかつ焼成による変形が小さい切削工具を容易に製造できる。 The manufacturing method of the present invention, that is, two different kinds of mixed raw material powders are prepared, and after filling and compressing only the first mixed raw material powder or the second mixed raw material powder, a predetermined part of the molding die The second mixed raw material powder is disposed on the outer periphery of the first mixed raw material powder by filling the second mixed raw material powder or the first mixed raw material powder and compressing again. By producing a composite molded body, an interface exists at the boundary between the first cermet and the second cermet, and no interface exists at the boundary between the surface region of the second cermet and the region on the substrate side. That is, there is no interface at the boundary between the A region and the C region, and there is an interface at the boundary between the B region and the C region. According to this manufacturing method, a cutting tool having high cutting performance and small deformation due to firing can be easily manufactured.

なお、前記第２の混合原料粉末の鉄族金属含有量を前記第１の混合原料粉末の鉄族金属含有量よりも多くするか、または前記第２の混合原料粉末の平均粒径を前記第１の混合原料粉末の平均粒径よりも小さくすることが、各部位の焼成状態を制御できる点で望ましい。 In addition, the iron group metal content of the second mixed raw material powder is made larger than the iron group metal content of the first mixed raw material powder, or the average particle size of the second mixed raw material powder is set to the first It is desirable to make it smaller than the average particle size of the mixed raw material powder 1 because the firing state of each part can be controlled.

本発明のサーメット焼結体からなる切削工具の一例を示し、（ａ）概略斜視図、（ｂ）断面模式図である。An example of the cutting tool which consists of a cermet sintered compact of this invention is shown, (a) A schematic perspective view, (b) A cross-sectional schematic diagram. 本発明のサーメット焼結体の製造方法における成形方法を説明するための工程図（前半）である。It is process drawing for demonstrating the shaping | molding method in the manufacturing method of the cermet sintered compact of this invention (the first half). 図２の工程図の続き（後半）である。FIG. 3 is a continuation (second half) of the process diagram of FIG. 2. 本発明のサーメット焼結体の製造方法における他の成形方法を説明するための工程図（前半）である。It is process drawing (first half) for demonstrating the other shaping | molding method in the manufacturing method of the cermet sintered compact of this invention. 図４の工程図の続き（後半）である。FIG. 5 is a continuation (second half) of the process diagram of FIG. 4.

本発明のサーメット焼結体からなる切削工具の一例について、その（ａ）概略斜視図、（ｂ）断面模式図である図１を基に説明する。 An example of a cutting tool made of the cermet sintered body of the present invention will be described with reference to FIG. 1 which is a schematic perspective view (a) and a schematic cross-sectional view (b).

図１の切削工具１は、第１サーメット２と、第１サーメット２の外周に配置されて少なくとも切刃７を構成する第２サーメット３とから構成されている。そして、第１サーメット２および第２サーメット３は、周期表第４、５および６族金属のうちの１種以上の炭化物、窒化物、炭窒化物およびこれらの固溶体の中から選ばれた１種以上からなる硬質相と、主として鉄族金属からなる結合相とから構成され、硬質相は、ＴｉＣＮを主成分とする第１硬質相と、周期表第４、５および６族金属の少なくとも1種とＴｉとの複合炭窒化物固溶体の第２硬質相とからなる。 The cutting tool 1 of FIG. 1 is comprised from the 1st cermet 2 and the 2nd cermet 3 which is arrange | positioned at the outer periphery of the 1st cermet 2 and comprises the cutting blade 7. FIG. And the 1st cermet 2 and the 2nd cermet 3 are 1 type chosen from 1 or more types of carbide | carbonized_material, nitride, carbonitride, and these solid solutions of periodic table 4th, 5th, and 6th group metals. The hard phase is composed of a hard phase composed of the above and a binder phase mainly composed of an iron group metal. The hard phase is at least one of the first hard phase mainly composed of TiCN and the metals in Groups 4, 5, and 6 of the periodic table. And a second hard phase of a composite carbonitride solid solution of Ti.

そして、第２サーメット３は第１サーメット２よりも第２硬質相の存在割合が多く、第１サーメット２は第２サーメット３よりも結合相の存在割合が少ない構成となっている。 The second cermet 3 has a higher proportion of the second hard phase than the first cermet 2, and the first cermet 2 has a smaller proportion of the binder phase than the second cermet 3.

また、別の見方をすれば、切削工具１は、切刃７を含む逃げ面９およびその近傍領域をＡ領域（第２サーメット３に相当）１１、Ａ領域１１以外の領域である焼結体の内部１０およびすくい面８の中央部位をＢ領域（第１サーメット２に相当）１２としたとき、Ａ領域１１ではＢ領域１２よりも第２硬質相の存在割合が多く、Ｂ領域１２ではＡ領域１１よりも結合相の存在割合が少ない構成からなっている。 From another point of view, the cutting tool 1 includes a sintered body in which the flank 9 including the cutting edge 7 and the vicinity thereof are the A region (corresponding to the second cermet 3) 11 and the region other than the A region 11. When the inner region 10 and the central portion of the rake face 8 are the B region (corresponding to the first cermet 2) 12, the A region 11 has a higher proportion of the second hard phase than the B region 12, and the B region 12 has A It has a configuration in which the existence ratio of the binder phase is smaller than that in the region 11.

上記構成によって、切刃７は切削性能が高い第２サーメット３の組織からなるとともに、基体を構成する第１サーメット２は焼結による変形が小さいので、焼結体全体の変形を抑制できて複雑な形状でも容易に寸法精度の高い切削工具１を作製できる。なお、図１の切削工具１のすくい面８の中央部にはネジ穴１４が形成されている。 With the above configuration, the cutting edge 7 is composed of the structure of the second cermet 3 having high cutting performance, and the first cermet 2 constituting the base body is less deformed by sintering, so that deformation of the entire sintered body can be suppressed and complicated. Even with a simple shape, the cutting tool 1 with high dimensional accuracy can be easily produced. In addition, the screw hole 14 is formed in the center part of the rake face 8 of the cutting tool 1 of FIG.

ここで、走査型電子顕微鏡観察した際には、第１硬質相は黒色の粒子として観察され、第２硬質相は灰白色の粒子、または白色の芯部の周辺に灰白色の周辺部が存在する有芯構造からなる粒子として観察される。なお、上記灰白色とは、写真撮影の条件によって白色に近い色調に見えることもあり、灰色に近い色調に見えることもある。ここで、第１硬質相はＴｉＣＮからなる黒色粒子であるがＣｏやＮｉを含有していても良い。また、第１硬質相の外周には、灰白色の第２硬質相からなる周辺部が存在した有芯構造をなしていてもよい。 Here, when observed with a scanning electron microscope, the first hard phase is observed as black particles, and the second hard phase is grayish white particles, or there are grayish white peripheral portions around the white core. Observed as particles consisting of a core structure. The grayish white color may appear to be a color tone close to white or may be a color tone close to gray depending on the conditions of photography. Here, the first hard phase is black particles made of TiCN, but may contain Co or Ni. Further, the outer periphery of the first hard phase may have a cored structure in which a peripheral portion made of the grayish white second hard phase is present.

なお、断面組織観察にて、Ａ領域１１における第１硬質相の面積比率をＳ_１Ａ、第２硬質相の面積比率をＳ_２Ａ、Ｂ領域における第１硬質相の面積比率をＳ_１Ｂ、第２硬質相の面積比率をＳ_２Ｂとしたとき、Ｓ_１ＡとＳ_２Ａとの比率（Ｓ_２Ａ／Ｓ_１Ａ）が２〜８であり、Ｓ_１ＢとＳ_２Ｂとの比率（Ｓ_２Ｂ／Ｓ_１Ｂ）が０．３〜０．９５であることが、切削性能を高くかつ変形を小さく抑制できる点で望ましい。 In the cross-sectional structure observation, the area ratio of the first hard phase in the A region 11 is S _1A , the area ratio of the second hard phase is S _2A , and the area ratio of the first hard phase in the B region is S _1B , second. When the area ratio of the hard phase is S _2B , the ratio of S _1A to S _2A (S _2A / S _1A ) is 2 to 8, and the ratio of S _1B to S _2B (S _2B / S _1B ) is It is desirable that it is 0.3 to 0.95 in that the cutting performance is high and the deformation can be suppressed small.

なお、切削工具１に含有される硬質相をなすＴｉを主成分とする周期表第４、５および６族金属の窒化物または炭窒化物の合計含有比率は、サーメット全体で見て８０〜９０質量％であることが望ましく、一方、結合相の含有比率は、サーメット全体で見て１０〜２０質量％であることによって、サーメットの硬度および靭性のバランスに優れたものとなる。そして、第１サーメット２においては、焼成における寸法変化の抑制の点で、硬質相の含有比率が９０〜９５質量％、結合相の含有比率が５〜１０質量％であることが望ましい。また、第２サーメット３においては、耐摩耗性の維持の点で、硬質相の含有比率が７５〜８５質量％、結合相の含有比率が１５〜２５質量％であることが望ましい。さらに、結合相としては、鉄族金属の総量に対してＣｏを６５質量％以上含有することが切削工具１の耐熱衝撃性を高めるために望ましい。なお、サーメットの焼肌面が平滑な面となるようにサーメットの良好な焼結性を維持するためには、鉄族金属としてＮｉを５〜５０質量％、特に１０〜３５質量％の割合で含有せしめることが望ましい。 In addition, the total content of the nitrides or carbonitrides of Periodic Table Group 4, 5 and 6 metals mainly composed of Ti which forms the hard phase contained in the cutting tool 1 is 80 to 90 in the whole cermet. On the other hand, the content ratio of the binder phase is preferably 10 to 20% by mass in the whole cermet, so that the balance of hardness and toughness of the cermet is excellent. And in the 1st cermet 2, it is desirable that the content rate of a hard phase is 90-95 mass% and the content rate of a binder phase is 5-10 mass% from the point of suppression of the dimensional change in baking. Moreover, in the 2nd cermet 3, it is desirable that the content rate of a hard phase is 75-85 mass% and the content rate of a binder phase is 15-25 mass% from the point of maintenance of abrasion resistance. Furthermore, as a binder phase, it is desirable to contain 65 mass% or more of Co with respect to the total amount of the iron group metal in order to improve the thermal shock resistance of the cutting tool 1. In addition, in order to maintain the favorable sinterability of the cermet so that the burned skin surface of the cermet becomes a smooth surface, Ni is contained in an amount of 5 to 50% by mass, particularly 10 to 35% by mass as an iron group metal. It is desirable to make it contain.

ここで、図１に記載する第２サーメット３の厚みｔは０．５〜２ｍｍであることが望ましい。このとき、Ａ領域１１は逃げ面９から５〜１００μｍの厚みで存在することが、切削性能が高くかつ変形が小さい切削工具１が製造上容易に作製できる点で望ましい。 Here, the thickness t of the second cermet 3 shown in FIG. 1 is preferably 0.5 to 2 mm. At this time, it is desirable that the A region 11 exists in a thickness of 5 to 100 μm from the flank 9 because the cutting tool 1 having high cutting performance and small deformation can be easily manufactured.

また、第２サーメット３には、表面側に、第２硬質相の存在割合が多く、かつ結合相の存在割合が少ない表面領域３Ｘが存在する構成、すなわち、Ａ領域１１とＢ領域１２との間に、Ｂ領域１２よりも第２硬質相の存在割合が少なく、かつＡ領域１１よりも結合相の存在割合が多いＣ領域１３が存在することによって、切削性能をさらに高めることができる点で望ましい。なお、断面組織観察にて、Ｃ領域１３における第１硬質相の面積比率をＳ_１Ｃ、第２硬質相の面積比率をＳ_２Ｃとしたとき、Ｓ_１ＣとＳ_２Ｃとの比率（Ｓ_２Ｃ／Ｓ_１Ｃ）は２〜８であり、Ｓ_１ＢとＳ_２Ｂとの比率（Ｓ_２Ｂ／Ｓ_１Ｂ）が０．３〜０．９５であることが、切削性能を高くかつ変形を小さく抑制できる点で望ましい。 Further, the second cermet 3 has a configuration in which the surface region 3X in which the second hard phase is present in a large amount and the binder phase is present in a small amount is present on the surface side, that is, the A region 11 and the B region 12 In the meantime, the presence of the C region 13 in which the second hard phase is present in a smaller proportion than in the B region 12 and the binder phase is present in a greater proportion than in the A region 11 makes it possible to further improve the cutting performance. desirable. Incidentally, in the cross-sectional structure observation, the first hard phase area ratio of _{S 1C} in C region 13, when the area ratio of the second hard phase was _{S _2C,} the ratio of _{S 1C} and the _{_S 2C _(S 2C} / _S _1C ) is 2 to 8, and the ratio of S _1B to S _2B (S _2B / S _1B ) is preferably 0.3 to 0.95 from the viewpoint of high cutting performance and small deformation. .

さらに、第１サーメット２の硬度が第２サーメット３の硬度より高く、かつ第２サーメット３の表面領域３Ｘの硬度が第２サーメット３の基体側３Ｙの硬度よりも高い構成、すなわち、Ａ領域１１の硬度がＣ領域１３の硬度より高く、かつＢ領域１２の硬度がＣ領域１３の硬度よりも高いことが、変形を防止できるとともに切刃７の耐摩耗性を高めることができる点で望ましい。 Furthermore, the hardness of the first cermet 2 is higher than the hardness of the second cermet 3 and the hardness of the surface region 3X of the second cermet 3 is higher than the hardness of the substrate side 3Y of the second cermet 3, that is, the A region 11 It is desirable that the hardness of the cutting region 7 is higher than the hardness of the C region 13 and the hardness of the B region 12 is higher than the hardness of the C region 13 in that deformation can be prevented and the wear resistance of the cutting edge 7 can be improved.

また、第１サーメット２における硬質相の平均粒径が第２サーメット３における硬質相の平均粒径より大きく、かつ第２サーメット３の表面領域３Ｘにおける硬質相の平均粒径が第２サーメットの基体側３Ｙにおける硬質相の平均粒径よりも大きい構成、すなわち、Ａ領域１１における硬質相の平均粒径がＣ領域１３における硬質相の平均粒径より大きく、かつＢ領域１２における硬質相の平均粒径がＣ領域１３における硬質相の平均粒径よりも大きいことが、組織の制御が容易な点で望ましい。 Further, the average particle size of the hard phase in the first cermet 2 is larger than the average particle size of the hard phase in the second cermet 3, and the average particle size of the hard phase in the surface region 3X of the second cermet 3 is the base of the second cermet. Configuration larger than the average particle size of the hard phase in the side 3Y, that is, the average particle size of the hard phase in the A region 11 is larger than the average particle size of the hard phase in the C region 13, and the average particle of the hard phase in the B region 12 It is desirable that the diameter is larger than the average particle diameter of the hard phase in the C region 13 because the structure can be easily controlled.

なお、上記切削工具１は、下記製造方法にて作製することから、第１サーメット２と第２サーメット３との境界に界面が存在し、かつ第２サーメットの表面領域３Ｘと基体側領域３Ｙとの境界には界面が存在しない構成、すなわちＡ領域１１とＣ領域１３との境界に界面が存在せず、かつＢ領域１２とＣ領域１３との境界には界面が存在する構成となる。 In addition, since the said cutting tool 1 is produced with the following manufacturing method, an interface exists in the boundary of the 1st cermet 2 and the 2nd cermet 3, and the surface area | region 3X and base | substrate side area | region 3Y of a 2nd cermet In other words, there is a configuration in which no interface exists at the boundary between the two regions, that is, there is no interface at the boundary between the A region 11 and the C region 13, and a boundary exists between the B region 12 and the C region 13.

（製造方法）
次に、上述したサーメット焼結体からなる切削工具の製造方法について説明する。
原料として、２種類の混合原料粉末を準備する。
第２の混合原料粉末は低温で焼結する組成からなり、具体的には、平均粒径０．６〜１．０μｍ、望ましくは０．８〜１．０μｍのＴｉＣＮ粉末と、平均粒径０．１〜２μｍの上述した他の周期表第４、５および６族金属の炭化物粉末、窒化物粉末または炭窒化物粉末のいずれか１種と、平均粒径１．０〜３．０μｍのＣｏ粉末と平均粒径０．３〜０．８μｍのＮｉ粉末との少なくとも１種と、所望により平均粒径０．５〜１０μｍのＭｎＣＯ_３粉末を混合した混合原料粉末とする。 (Production method)
Next, the manufacturing method of the cutting tool which consists of a cermet sintered compact mentioned above is demonstrated.
Two kinds of mixed raw material powders are prepared as raw materials.
The second mixed raw material powder is composed of a composition sintered at a low temperature. Specifically, the TiCN powder having an average particle diameter of 0.6 to 1.0 μm, desirably 0.8 to 1.0 μm, and an average particle diameter of 0 Any one of carbide powder, nitride powder, or carbonitride powder of Group 4, 5, and 6 metals of the above-mentioned other periodic table of 1-2 μm described above, and Co having an average particle diameter of 1.0-3.0 μm A mixed raw material powder in which at least one of powder and Ni powder having an average particle size of 0.3 to 0.8 μm and optionally MnCO ₃ powder having an average particle size of 0.5 to 10 μm are mixed is used.

一方、第１の原料粉末は第２の混合原料粉末よりも焼成温度の高い組成からなり、平均粒径１．０〜２．０μｍ、望ましくは１．１〜１．５μｍのＴｉＣＮ粉末と、平均粒径０．１〜２μｍの上述した他の周期表第４、５および６族金属の炭化物粉末、窒化物粉末または炭窒化物粉末のいずれか１種と、平均粒径１．０〜３．０μｍのＣｏ粉末と平均粒径０．３〜０．８μｍのＮｉ粉末との少なくとも１種と、所望により平均粒径０．５〜１０μｍのＭｎＣＯ_３粉末を混合した混合原料粉末とする。 On the other hand, the first raw material powder has a composition having a higher firing temperature than the second mixed raw material powder, and an average particle size of 1.0 to 2.0 μm, preferably 1.1 to 1.5 μm of TiCN powder, and an average Any one of carbide powders, nitride powders, or carbonitride powders of other Group 4, 5, and 6 metals of the above-described periodic table having a particle size of 0.1 to 2 μm, and an average particle size of 1.0 to 3. A mixed raw material powder is prepared by mixing at least one kind of 0 μm Co powder and Ni powder having an average particle diameter of 0.3 to 0.8 μm, and optionally MnCO ₃ powder having an average particle diameter of 0.5 to 10 μm.

ここで、前記第２の混合原料粉末の鉄族金属含有量が前記第１の混合原料粉末の鉄族金属含有量よりも多いか、または前記第２の混合原料粉末の平均粒径が前記第１の混合原料粉末の平均粒径よりも小さいことが望ましい。 Here, the iron group metal content of the second mixed raw material powder is larger than the iron group metal content of the first mixed raw material powder, or the average particle size of the second mixed raw material powder is the first mixed powder. It is desirable that it is smaller than the average particle diameter of one mixed raw material powder.

なお、上記第１および第２の混合原料粉末中にＴｉＣ粉末やＴｉＮ粉末を添加することもあるが、これらの原料粉末は焼成後のサーメットにおいてＴｉＣＮを構成する。 In addition, although TiC powder and TiN powder may be added to the first and second mixed raw material powders, these raw material powders constitute TiCN in the cermet after firing.

次に、上記異なる２種類の混合原料粉末を用いて切削工具形状に成形する。成形方法の詳細について、図２、３の工程図に基づいて説明する。 Next, the two different kinds of mixed raw material powders are formed into a cutting tool shape. Details of the molding method will be described based on the process diagrams of FIGS.

まず、プレス金型２１のダイス２２の中心にある貫通孔内に下パンチ２３を嵌め込んで第１空隙部２５を作る。下パンチ２３は、中心に存在して切削工具１のネジ穴１４を形成するための第１下パンチ２３ａと、第１下パンチ２３ａの外周に存在して第１サーメット２を成形するための第２下パンチ２３ｂと、第２下パンチ２３ｂの外周に存在して第２サーメット３を成形するための第３下パンチ２３ｃとから構成される。上記第１空隙部２５は第１サーメット２を充填して成形するための空間であり、第１下パンチ２３ａと第３下パンチ２３ｃの先端はダイス２２の上面と同じ高さとし、第２下パンチ２３ｂのみが下に下がった配置として第１空隙部２５が形成される。この第１空隙部２５中にフィーダ２７を用いて焼成時の収縮が小さい第１の混合原料粉末２８を充填する（図２（ａ）（ｂ）参照）。そして、第１空隙部２５中に充填された第１の混合原料粉末２８の上方から上パンチ２４を下降させて加圧圧縮することにより、第１混合原料粉末成形体２９を作製する（図２（ｃ）参照）。このとき、上パンチ２４の下降と同期させて第１下パンチ２３ａと第３下パンチ２３ｃは下降させる。その後、上パンチ２４を上方に後退させる（図２（ｄ）参照）。 First, the lower punch 23 is fitted into the through hole at the center of the die 22 of the press die 21 to create the first gap portion 25. The lower punch 23 is present at the center to form a first lower punch 23a for forming the screw hole 14 of the cutting tool 1 and a first punch for forming the first cermet 2 on the outer periphery of the first lower punch 23a. 2 lower punches 23b and a third lower punch 23c for forming the second cermet 3 that exists on the outer periphery of the second lower punch 23b. The first gap 25 is a space for filling and forming the first cermet 2, and the tips of the first lower punch 23 a and the third lower punch 23 c are the same height as the upper surface of the die 22, and the second lower punch The 1st space | gap part 25 is formed as arrangement | positioning in which only 23b went down. The first gap material 25 is filled with the first mixed raw material powder 28 having a small shrinkage during firing by using a feeder 27 (see FIGS. 2A and 2B). And the 1st mixed raw material powder compact | molding | casting 29 is produced by dropping the upper punch 24 from the upper direction of the 1st mixed raw material powder 28 with which it filled in the 1st space | gap part 25, and compressing by pressure (FIG. 2). (See (c)). At this time, the first lower punch 23 a and the third lower punch 23 c are lowered in synchronization with the lowering of the upper punch 24. Thereafter, the upper punch 24 is retracted upward (see FIG. 2D).

次に、第１混合原料粉末成形体２９の上面と第１下パンチ２３ａの先端面とをダイス２２の上面位置に合わせるとともに第３下パンチ２３ｃを下降させて、第２空隙部３０を形成する（図３（ｅ）参照）。それから、フィーダ２７を用いて第２空隙部３０に第２の混合原料粉末３２を充填する（図３（ｆ）（ｇ）参照）。そして、第２空隙部３０に充填した第２の混合原料粉末３２を上方から上パンチ２４を下降させるとともに下方から第３下パンチ２３ｃを上昇させて加圧圧縮することにより、薄板状の第１混合原料粉末成形体２９の外周に枠状の第２の混合原料粉末３２からなる第２混合原料粉末成形体３３が配置された複合成形体３５を形成することができる。 Next, the upper surface of the first mixed raw material powder compact 29 and the tip surface of the first lower punch 23a are aligned with the upper surface position of the die 22, and the third lower punch 23c is lowered to form the second gap 30. (See FIG. 3 (e)). Then, the second mixed raw material powder 32 is filled into the second gap 30 using the feeder 27 (see FIGS. 3F and 3G). Then, the second mixed raw material powder 32 filled in the second gap 30 is compressed by lowering the upper punch 24 from the upper side and raising the third lower punch 23c from the lower side to compress and compress it. A composite molded body 35 in which a second mixed raw material powder molded body 33 made of a frame-shaped second mixed raw material powder 32 is disposed on the outer periphery of the mixed raw material powder molded body 29 can be formed.

なお、本発明は上記方法に限定されるものではなく、図４，５の他の成形方法を示す工程図のように、先に枠状の第２混合原料粉末成形体３３を形成した後、その内側に第１混合原料粉末成形体２９を形成して複合成形体３５を形成することができる。ここで、第１サーメット２の成形体（第１混合原料粉末成形体２９）の充填密度を高めて、第１サーメット２および切削工具１全体の変形を防止する点では、第１サーメット２を先に成形する方法が望ましい。 In addition, this invention is not limited to the said method, After forming the frame-shaped 2nd mixed raw material powder compact | molding body 33 previously like the process drawing which shows the other shaping | molding methods of FIG. A composite molded body 35 can be formed by forming the first mixed raw material powder molded body 29 inside thereof. Here, the first cermet 2 is the first in terms of increasing the packing density of the molded body of the first cermet 2 (first mixed raw material powder molded body 29) and preventing deformation of the first cermet 2 and the cutting tool 1 as a whole. The method of forming into a desirable shape.

その他の成形方法としては、第１の原料粉末のみを用いてプレス成形した成形体の表面に第１の原料粉末を含むスラリーを塗布する方法も挙げられるが、切削工具の切刃における寸法精度を高めるとともに切刃における焼結体の密度を高めるためには、両粉末を積層した状態でプレス成形する方法が好適である。 Other molding methods include a method in which a slurry containing the first raw material powder is applied to the surface of a molded body that is press-molded using only the first raw material powder. In order to increase the density of the sintered body at the cutting edge, a method of press molding in a state where both powders are laminated is preferable.

その後、上記成形体を焼成することにより、上述した所定組織のサーメットを作製することができる。具体的な焼成条件の一例としては、
（ａ）１０５０〜１２５０℃まで昇温し、
（ｂ）窒素（Ｎ_２）等の不活性ガスを３０〜２０００Ｐａ充填した雰囲気で０．１〜２℃／分の昇温速度で１３００〜１４５０℃まで昇温し、
（ｃ）真空雰囲気で３〜１５℃／分の昇温速度で１５２０〜１６００℃まで昇温するとともに、真空雰囲気のまま、または不活性ガスを充填した雰囲気で０．５〜２時間維持し、
（ｄ）６〜１５℃／分の冷却速度で冷却する工程にて焼成する。なお、焼成温度が１５２０℃より低いと、サーメット焼結体の全体として変形はしないがサーメットの表面に焼結が進行してできる複合炭窒化物固溶体である第２硬質相の存在比率が高いＡ領域が形成されずに、サーメット焼結体の表面における耐摩耗性が低下する。 Then, the cermet of the predetermined structure | tissue mentioned above can be produced by baking the said molded object. As an example of specific firing conditions,
(A) The temperature is raised to 1050 to 1250 ° C.
(B) In an atmosphere filled with an inert gas such as nitrogen (N ₂ ) of 30 to 2000 Pa, the temperature is increased to 1300 to 1450 ° C. at a temperature increase rate of 0.1 to 2 ° C./min,
(C) While raising the temperature to 1520 to 1600 ° C. at a rate of 3 to 15 ° C./min in a vacuum atmosphere, maintaining the vacuum atmosphere or an atmosphere filled with an inert gas for 0.5 to 2 hours,
(D) Firing is performed at a cooling rate of 6 to 15 ° C./min. When the firing temperature is lower than 1520 ° C., the cermet sintered body is not deformed as a whole, but the abundance ratio of the second hard phase that is a composite carbonitride solid solution formed by sintering on the surface of the cermet is high. The area is not formed, and the wear resistance on the surface of the cermet sintered body is lowered.

そして、所望により、サーメットの表面に被覆層を成膜する。被覆層の成膜方法として、イオンプレーティング法やスパッタリング法等の物理蒸着（ＰＶＤ）法が好適に適応可能である。 Then, if desired, a coating layer is formed on the surface of the cermet. A physical vapor deposition (PVD) method such as an ion plating method or a sputtering method can be suitably applied as the coating layer forming method.

マイクロトラック法による測定で平均粒径（ｄ_５０値）が２．０μｍのＴｉＣＮ粉末、平均粒径１．１μｍで表１のＣ量のＷＣ粉末、平均粒径１．５μｍのＴｉＮ粉末、平均粒径２μｍのＴａＣ粉末、平均粒径１．５μｍのＮｂＣ粉末、平均粒径１．８μｍのＺｒＣ粉末、平均粒径１．０μｍのＶＣ粉末、平均粒径２．４μｍのＮｉ粉末、および平均粒径１．９μｍのＣｏ粉末を用いて、表１に示す割合で調製した第１の混合原料粉末をステンレス製ボールミルと超硬ボールを用いて、イソプロピルアルコール（ＩＰＡ）を添加して湿式混合し、パラフィンを３質量％添加、混合した後、スプレードライヤにて顆粒とした。 TiCN powder having an average particle diameter (d ₅₀ value) of 2.0 μm as measured by the microtrack method, WC powder having an average particle diameter of 1.1 μm and the amount of C shown in Table 1, TiN powder having an average particle diameter of 1.5 μm, an average particle TaC powder having a diameter of 2 μm, NbC powder having an average particle diameter of 1.5 μm, ZrC powder having an average particle diameter of 1.8 μm, VC powder having an average particle diameter of 1.0 μm, Ni powder having an average particle diameter of 2.4 μm, and an average particle diameter Using a 1.9 μm Co powder, the first mixed raw material powder prepared in the ratio shown in Table 1 was wet-mixed using a stainless steel ball mill and a carbide ball to which isopropyl alcohol (IPA) was added. Was added and mixed, and then granulated with a spray dryer.

同様に、上記原料粉末を用いて表１に示す第２の混合原料粉末を調製し、バインダを混合して、スプレードライヤにて第２の混合原料粉末の顆粒を作製した。 Similarly, the 2nd mixed raw material powder shown in Table 1 was prepared using the said raw material powder, the binder was mixed, and the granule of the 2nd mixed raw material powder was produced with the spray dryer.

そして、この成形用の混合原料粉末を用いて、図２、３の方法で、最後に上パンチを降下させて２００ＭＰａの圧力で加圧してＳＥＫＲ１２０３ＡＦＥＮ（チップ厚み３．１８ｍｍ）の工具形状にプレス成形した。 Then, by using the mixed raw material powder for molding, the upper punch is finally lowered and pressurized with a pressure of 200 MPa by the method shown in FIGS. 2 and 3, and is pressed into a tool shape of SEKR1203AFEN (chip thickness 3.18 mm). did.

さらに、この成形体を焼成炉に投入して、（ａ）１０℃／分の昇温速度で１２００℃まで昇温し、（ｂ）窒素（Ｎ_２）を１０００Ｐａ充填した雰囲気で０．５℃／分の昇温速度で１４００℃まで昇温し、（ｃ）真空雰囲気で７℃／分の昇温速度で表２に示す温度まで昇温するとともに、その状態で１時間維持し、（ｄ）１０℃／分の冷却速度で冷却する工程にて焼成する焼成条件で焼成した。 Furthermore, this molded body was put into a firing furnace, (a) heated to 1200 ° C. at a heating rate of 10 ° C./min, (b) 0.5 ° C. in an atmosphere filled with 1000 Pa of nitrogen (N ₂ ). (C) The temperature was raised to 1400 ° C. at a rate of temperature rise / minute, (c) the temperature was raised to a temperature shown in Table 2 at a rate of temperature rise of 7 ° C./min in a vacuum atmosphere, and maintained in that state for 1 hour, (d ) It baked on the baking conditions baked in the process cooled at the cooling rate of 10 degrees C / min.

得られたサーメットについて、走査型電子顕微鏡（ＳＥＭ）観察を行い、１００００倍の写真にて、表面および内部のそれぞれ任意５箇所について市販の画像解析ソフトを用いて８μｍ×８μｍの領域で画像解析を行い、硬質相の存在状態、表面領域の存在を確認するとともにこれらの面積比率を算出した。結果は表２に示した。 The obtained cermet was observed with a scanning electron microscope (SEM), and image analysis was performed in a region of 8 μm × 8 μm using a commercially available image analysis software for each of the surface and the interior at a 10000 × magnification. And the presence of the hard phase and the presence of the surface region were confirmed, and the area ratios were calculated. The results are shown in Table 2.

次に、得られたサーメット製の切削工具を用いて以下の切削条件にて切削試験を行った。また、金属顕微鏡を用いてサーメットの側面（逃げ面）形状をトレースし、側面の中央部における膨らみ量を算出した。結果は表３に併記した。
被削材：Ｓ４５Ｃ
切削速度：１８０ｍ／分
送り：０．１５ｍｍ／刃
切込み：１．５ｍｍ
切削状態：湿式（水溶性切削液使用）
評価方法：摩耗量が０．２ｍｍに達するまでの時間 Next, a cutting test was performed under the following cutting conditions using the obtained cermet cutting tool. Moreover, the side surface (flank) shape of the cermet was traced using the metal microscope, and the bulge amount in the center part of the side surface was calculated. The results are also shown in Table 3.
Work material: S45C
Cutting speed: 180 m / min Feed: 0.15 mm / blade cutting: 1.5 mm
Cutting condition: wet (use water-soluble cutting fluid)
Evaluation method: Time until the wear amount reaches 0.2 mm

表１〜３より、第１サーメットの結合相量が第２サーメットの結合相量が多い試料Ｎｏ．５では、焼結体の変形量が大きくて工具本体への装着にがたつきが発生した。また、第２サーメットの結合相量が第１サーメットの結合相量よりも少ない試料Ｎｏ．６では、切削加工中にチッピングが発生した。さらに、焼成温度が１５２０℃よりも低く表面の固溶体の存在割合が内部と同じ試料Ｎｏ．７では、切削評価において摩耗量が大きいものであった。さらには、第１サーメットが過焼結した試料Ｎｏ．８では変形量が大きくなった。 From Tables 1 to 3, sample No. 1 in which the amount of the binder phase in the first cermet is large in the amount of the binder phase in the second cermet. In No. 5, the amount of deformation of the sintered body was large, and rattling occurred on the tool body. Further, the sample No. 2 in which the amount of the binder phase of the second cermet is smaller than the amount of the binder phase of the first cermet. In No. 6, chipping occurred during the cutting process. Furthermore, the sample No. 1 whose firing temperature is lower than 1520 ° C. and the ratio of the solid solution on the surface is the same as the inside. In No. 7, the amount of wear was large in the cutting evaluation. Furthermore, sample No. 1 in which the first cermet was oversintered. In 8, the amount of deformation increased.

これに対し、本発明の範囲内の組織となったサーメットからなる試料Ｎｏ．１〜４では、優れた耐摩耗性を発揮するとともに耐欠損性も良好であり、工具寿命が長いものであった。 On the other hand, Sample No. consisting of cermet having a structure within the scope of the present invention. Nos. 1 to 4 exhibited excellent wear resistance, good fracture resistance, and long tool life.

１切削工具
２第１サーメット
３第２サーメット
３Ｘ第２サーメットの表面領域
３Ｙ第２サーメットの基体側領域
７切刃
８すくい面
９逃げ面
１０内部
１１Ａ領域
１２Ｂ領域
１３Ｃ領域
１４ネジ穴
２１プレス金型
２２ダイス
２３下パンチ
２３ａ第１下パンチ
２３ｂ第２下パンチ
２３ｃ第３下パンチ
２４上パンチ
２５第１空隙部
２７フィーダ
２８第１の混合原料粉末
２９第１混合原料粉末成形体
３０第２空隙部
３２第２の混合原料粉末
３３第２混合原料粉末成形体
３５複合成形体 DESCRIPTION OF SYMBOLS 1 Cutting tool 2 1st cermet 3 2nd cermet 3X 2nd cermet surface area | region 3Y 2nd cermet base | substrate side area | region 7 Cutting edge 8 Rake face 9 Internal surface 11 A area | region 12 B area | region 13 C area | region 14 Screw hole 21 Press die 22 Die 23 Lower punch 23a First lower punch 23b Second lower punch 23c Third lower punch 24 Upper punch 25 First gap portion 27 Feeder 28 First mixed raw material powder 29 First mixed raw material powder compact 30 First 2 void portion 32 second mixed raw material powder 33 second mixed raw material powder molded body 35 composite molded body

Claims

第１サーメットと、該第１サーメットの外周に配置される第２サーメットとの複合構造からなり、
前記第１サーメットおよび前記第２サーメットは、周期表第４、５および６族金属のうちの１種以上の炭化物、窒化物、炭窒化物およびこれらの固溶体の中から選ばれた１種以上からなる硬質相と、主として鉄族金属からなる結合相とから構成され、前記硬質相は、ＴｉＣＮを主成分とする第１硬質相と、周期表第４、５および６族金属の少なくとも1種とＴｉとの複合炭窒化物固溶体の第２硬質相とからなり、
前記第２サーメットは前記第１サーメットよりも前記第２硬質相の存在割合が多く、前記第１サーメットは前記第２サーメットよりも前記結合相の存在割合が少ないサーメット焼結体。 It consists of a composite structure of a first cermet and a second cermet arranged on the outer periphery of the first cermet,
The first cermet and the second cermet may be one or more selected from one or more carbides, nitrides, carbonitrides, and solid solutions of the metals in Groups 4, 5, and 6 of the periodic table. The hard phase is composed of a first hard phase mainly composed of TiCN and at least one of Group 4, 5 and 6 metals of the periodic table. Comprising a second hard phase of a composite carbonitride solid solution with Ti,
The second cermet is a cermet sintered body having a higher proportion of the second hard phase than the first cermet and the first cermet having a lower proportion of the binder phase than the second cermet.

前記第２サーメットの厚みは０．５〜２ｍｍである請求項１記載のサーメット焼結体。 The cermet sintered body according to claim 1, wherein the second cermet has a thickness of 0.5 to 2 mm.

前記第２サーメットには、表面側に、前記第２硬質相の存在割合が多く、かつ前記結合相の存在割合が少ない表面領域が存在する請求項１または２記載のサーメット焼結体。 3. The cermet sintered body according to claim 1, wherein the second cermet has a surface region on the surface side where the second hard phase is present in a large proportion and the binder phase is present in a small proportion.

前記第１サーメットの硬度が前記第２サーメットの硬度より高く、かつ前記第２サーメットの前記表面領域の硬度が前記第２サーメットの前記第１サーメット側の硬度よりも高い請求項３記載のサーメット焼結体。 The cermet firing according to claim 3, wherein the hardness of the first cermet is higher than the hardness of the second cermet, and the hardness of the surface region of the second cermet is higher than the hardness of the second cermet on the first cermet side. Union.

前記第１サーメットにおける前記硬質相の平均粒径が前記第２サーメットにおける前記硬質相の平均粒径より大きく、かつ前記第２サーメットの前記表面領域における前記硬質相の平均粒径が前記第２サーメットの前記第１サーメット側における前記硬質相の平均粒径よりも大きい請求項３または４記載のサーメット焼結体。 The average particle size of the hard phase in the first cermet is larger than the average particle size of the hard phase in the second cermet, and the average particle size of the hard phase in the surface region of the second cermet is the second cermet. The cermet sintered body according to claim 3 or 4, wherein the cermet sintered body is larger than an average particle diameter of the hard phase on the first cermet side.

前記第１サーメットと前記第２サーメットとの境界に界面が存在し、かつ前記第２サーメットの前記表面領域と前記第１サーメット側の領域との境界には界面が存在しない請求項３乃至５のいずれか記載のサーメット焼結体。 6. The interface according to claim 3, wherein an interface exists at a boundary between the first cermet and the second cermet, and no interface exists at a boundary between the surface region of the second cermet and the region on the first cermet side. Any one of the cermet sintered bodies.

周期表第４、５および６族金属のうちの１種以上の炭化物、窒化物、炭窒化物およびこれらの固溶体の中から選ばれた１種以上からなる硬質相と、主として鉄族金属からなる結合相との焼結体から構成され、前記硬質相は、ＴｉＣＮを主成分とする第１硬質相と、周期表第４、５および６族金属の少なくとも1種とＴｉとの複合炭窒化物固溶体の第２硬質相とからなり、
切刃を含む逃げ面およびその近傍領域をＡ領域とし、該Ａ領域以外の領域である前記焼結体の内部およびすくい面の中央部位をＢ領域としたとき、前記Ａ領域では前記Ｂ領域よりも前記第２硬質相の存在割合が多く、前記Ｂ領域では前記Ａ領域よりも前記結合相の存在割合が少ない切削工具。 A hard phase composed of one or more carbides, nitrides, carbonitrides, and solid solutions thereof selected from Group 4, 5, and 6 metals of the periodic table, and mainly composed of an iron group metal. It is composed of a sintered body with a binder phase, and the hard phase is a composite carbonitride of Ti with a first hard phase mainly composed of TiCN, at least one of Group 4, 5, and 6 metals of the periodic table and Ti. Consisting of a second hard phase of solid solution,
When the flank including the cutting edge and the area near the flank are designated as A area, and the inside of the sintered body and the central part of the rake face other than the A area are designated as B area, the A area is more than the B area. A cutting tool in which the second hard phase is present in a large proportion and the binder region is present in the B region less than the A region.

断面組織観察にて、前記Ａ領域における前記第１硬質相の面積比率をＳ_１Ａ、前記第２硬質相の面積比率をＳ_２Ａとし、前記Ｂ領域における前記第１硬質相の面積比率をＳ_１Ｂ、前記第２硬質相の面積比率をＳ_２Ｂとしたとき、前記Ｓ_１Ａと前記Ｓ_２Ａとの比率（Ｓ_２Ａ／Ｓ_１Ａ）が２〜８であり、前記Ｓ_１Ｂと前記Ｓ_２Ｂとの比率（Ｓ_２Ｂ／Ｓ_１Ｂ）が０．５〜１．５である請求項７記載の切削工具。 In cross-sectional structure observation, the area ratio of the first hard phase in the A region is S _1A , the area ratio of the second hard phase is S _2A, and the area ratio of the first hard phase in the B region is S _1B. When the area ratio of the second hard phase is S _2B , the ratio of S _1A to S _2A (S _2A / S _1A ) is 2 to 8, and the ratio of S _1B to S _2B The cutting tool according to claim 7, wherein (S _2B / S _1B ) is 0.5 to 1.5.

前記Ａ領域は前記逃げ面から５〜１００μｍの厚みで存在する請求項７または８記載の切削工具。 The cutting tool according to claim 7 or 8, wherein the region A exists in a thickness of 5 to 100 µm from the flank.

前記Ａ領域と前記Ｂ領域との間に、前記Ｂ領域よりも前記第２硬質相の存在割合が少なく、かつ前記Ａ領域よりも前記結合相の存在割合が多いＣ領域が存在する請求項７または８記載の切削工具。 The region C between the A region and the B region includes a C region in which the second hard phase is present in a smaller proportion than the B region and the binder phase is present in a greater proportion than the A region. Or the cutting tool of 8.

前記Ａ領域の硬度が前記Ｃ領域の硬度よりも高く、かつ前記Ｂ領域の硬度が前記Ｃ領域の硬度よりも高い請求項１０記載の切削工具。 The cutting tool according to claim 10, wherein the hardness of the A region is higher than the hardness of the C region, and the hardness of the B region is higher than the hardness of the C region.

前記Ａ領域における前記硬質相の平均粒径が前記Ｃ領域における前記硬質相の平均粒径よりも大きく、かつ前記Ｂ領域における前記硬質相の平均粒径が前記Ｃ領域における前記硬質相の平均粒径よりも大きい請求項１０または１１記載の切削工具。 The average particle size of the hard phase in the A region is larger than the average particle size of the hard phase in the C region, and the average particle size of the hard phase in the B region is an average particle of the hard phase in the C region. The cutting tool according to claim 10 or 11, wherein the cutting tool is larger than the diameter.

前記Ａ領域と前記Ｃ領域との境界に界面が存在せず、かつ前記Ｂ領域と前記Ｃ領域との境界には界面が存在する請求項１０乃至１２のいずれか記載の切削工具。 The cutting tool according to any one of claims 10 to 12, wherein an interface does not exist at a boundary between the A region and the C region, and an interface exists at a boundary between the B region and the C region.

異なる２種類の混合原料粉末を調製する工程と、
成形金型の空洞部分の中央部に焼成時の収縮が小さい第１の混合原料粉末を充填して圧縮することにより、該第１の混合原料粉末からなる第１の粉末成形体を作製する工程と、前記成形金型の前記第１の粉末成形体の外周部に空隙を設けて、該空隙に前記第１の混合原料粉末よりも焼成時の収縮が大きい第２の混合原料粉末を充填して再度圧縮することにより、前記第１の混合原料粉末の外周部に前記第２の混合原料粉末が配置された複合成形体を作製する工程と、
該複合成形体を焼成する工程とを具備するサーメット焼結体の製造方法。 Preparing two different mixed raw material powders;
A step of producing a first powder molded body made of the first mixed raw material powder by filling and compressing the first mixed raw material powder having a small shrinkage at the time of firing in the central part of the cavity of the molding die And forming a void in the outer periphery of the first powder compact of the molding die, and filling the void with the second mixed raw material powder having a larger shrinkage during firing than the first mixed raw material powder. And recompressing to produce a composite molded body in which the second mixed raw material powder is arranged on the outer periphery of the first mixed raw material powder;
A method for producing a cermet sintered body comprising a step of firing the composite molded body.

異なる２種類の混合原料粉末を調製する工程と、
成形金型の空洞部分の外周部に焼成時の収縮が大きい第２の混合原料粉末を充填して圧縮することにより、該第２の混合原料粉末からなる第２の粉末成形体を作製する工程と、前記成形金型の前記第２の粉末成形体の内側に空隙を設けて、該空隙に前記第２の混合原料粉末よりも焼成時の収縮が小さい第１の混合原料粉末を充填して再度圧縮することにより、前記第１の混合原料粉末の外周部に前記第２の混合原料粉末が配置された複合成形体を作製する工程と、
該複合成形体を焼成する工程とを具備するサーメット焼結体の製造方法。 Preparing two different mixed raw material powders;
A step of producing a second powder molded body made of the second mixed raw material powder by filling the outer peripheral portion of the cavity portion of the molding die with the second mixed raw material powder having a large shrinkage during firing and compressing it. And providing a void inside the second powder molded body of the molding die, and filling the void with the first mixed raw material powder that has smaller shrinkage during firing than the second mixed raw material powder. By compressing again, producing a composite molded body in which the second mixed raw material powder is arranged on the outer periphery of the first mixed raw material powder;
A method for producing a cermet sintered body comprising a step of firing the composite molded body.

前記第１の混合原料粉末の鉄族金属含有量を前記第２の混合原料粉末の鉄族金属含有量よりも多くする請求項１４または１５記載のサーメット焼結体の製造方法。 The method for producing a cermet sintered body according to claim 14 or 15, wherein the iron group metal content of the first mixed raw material powder is larger than the iron group metal content of the second mixed raw material powder.

前記第１の混合原料粉末の平均粒径を前記第２の混合原料粉末の平均粒径よりも小さくする請求項１４乃至１６のいずれか記載のサーメット焼結体の製造方法。 The method for producing a cermet sintered body according to any one of claims 14 to 16, wherein an average particle diameter of the first mixed raw material powder is made smaller than an average particle diameter of the second mixed raw material powder.