JP4787388B2 - Cutting tool with excellent fracture resistance and manufacturing method thereof - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は立方晶窒化硼素（ｃＢＮ）焼結体を用いた切削工具とその製造方法に関するものである。特に、耐摩耗性および耐欠損性が改良された切削工具に関するものである。
【０００２】
【従来の技術】
ｃＢＮはダイヤモンドに次ぐ高硬度物質であり、ｃＢＮ基焼結体は種々の切削工具、耐摩耗部品、耐衝撃部品などに使用されている。
【０００３】
この種の焼結体として、例えば特公昭62-25630号公報、特公昭62-25631号公報、特開平5-186272号公報に記載のものが挙げられる。
【０００４】
【発明が解決しようとする課題】
しかし、上記の各技術においても、強度の面で必ずしも十分ではない。例えば、上記の焼結体をバイトに用いた場合、強い衝撃が刃先に加わるような用途では、衝撃により刃先が欠損しやすく、その結果、工具寿命が安定しないという問題があった。
【０００５】
従って、本発明の主目的は、強度を向上することにより、耐欠損性に優れたｃＢＮ焼結体を備える切削工具とその製造方法を提供することにある。
【０００６】
【課題を解決するための手段】
本発明切削工具はｃＢＮ粒子を結合相で焼結した焼結体を備える耐欠損性に優れた切削工具である。この結合相は二次元的に見て連続した構成となっている。また、この結合相は周期律表4a,5a,6a族遷移金属の炭化物，窒化物，炭窒化物，硼化物、Ａｌの窒化物，硼化物，酸化物、Ｆｅ，Ｃｏ，Ｎｉの少なくとも1種の炭化物，窒化物，炭窒化物，硼化物、およびこれらの相互固溶体よりなる群から選択される1種以上を含む。さらに、結合相厚みの平均値は１．０μｍ以下で、その標準偏差は０．７以下である。ここで、結合相厚みとは焼結体中の任意の直線上で、ｃＢＮ粒子とｃＢＮ粒子の間の距離を意味する。一方、ｃＢＮの含有率は体積％で４５〜７０％である。そして、ｃＢＮ粒子の平均粒度は０．０１以上２．０μｍ未満である。この平均粒度とは、累積体積％が５０％となる粒径のことをいう。
【０００７】
従来のｃＢＮ焼結体（ｃＢＮ粒子が平均粒度０．０１〜２μｍ）は結合相厚みの標準偏差が０．７を越えている。すなわち、結合相の厚みのばらつきが大きく、結合相だけで大きな体積を占める部分がある。この部分は焼結体中で強度が弱い部分（欠陥）である。焼結体に衝撃が加わったときに、この部分は応力が集中しやすく、かつ強度が弱いため、ここを起点に破壊が発生しやすく、工具の耐欠損性が十分でない。
【０００８】
刃先に衝撃が加わる用途では、上述したように、衝撃により上記の欠陥の部分に応力が集中し、かつこの部分の強度が弱いために、ここと起点として破壊が発生し、刃先が欠損すると考えられる。
【０００９】
そこで、本発明工具の焼結体では結合相厚みのバラツキを従来の焼結体より小さくすることで、欠陥となる部分を少なくし、耐欠損性の改善を図っている。結合相の平均厚みとその標準偏差が上記規定値を越えると、結合相だけで大きな体積を占める部分が増え、耐欠損性の改善効果が少ない。また、結合相の平均厚みの下限は、結合相としての機能を発揮するため、０．２μｍ程度が好ましい。さらに、ｃＢＮ粒子が上記規定よりも微粒では粒子の耐熱性が劣って摩耗が発達しやすくなり、規定よりも粗粒ではｃＢＮ粒子自体が衝撃により劈開し、刃先が欠損して工具の耐欠損性が不足するので、ｃＢＮ粒子の粒度は０．０１−２μｍが適している。
【００１０】
本発明工具の焼結体を得るには、ｃＢＮに結合相材料を被覆したり、特殊な方法で原料を混合する。結合相材料の被覆は、焼結前に、化学蒸着法（ＣＶＤ法）や物理蒸着法（ＰＶＤ法）、無電解めっき法、あるいは機械的混合時の圧縮せん断力、摩擦力、衝撃力に誘起されたメカノケミカル的な反応を利用する方法が挙げられる。特殊な混合方法については、超音波混合法または分散材を用いたボールミル法が最適である。
【００１１】
なお、本発明工具の焼結体の焼結工程には、プラズマ焼結装置、ホットプレス装置または超高圧焼結装置などが利用できる。
【００１２】
【発明の実施の形態】
以下、本発明の実施の形態を説明する。
【００１３】
（実施例１）
７６重量％のＴｉの窒化物、１８重量％のＡｌ、３重量％のＣｏおよび３重量％のＮｉを混合し、真空中で１２００℃、３０分熱処理をした化合物を粉砕し、結合相粉末を作製した。この結合相粉末は、ＸＲＤ(X‐ray diffraction)ではＴｉＮ、Ｔｉ2ＡｌＮ、ＴｉＡｌ3 等のピークがみられた。この結合相粉末と平均粒径１μｍのｃＢＮ粉末を、ｃＢＮの体積含有率が６０体積％になるように表１に記載の方法で混合した。各混合法の詳細な条件は次の通りである。ここで、Ｎｏ．２において、ｃＢＮにＴｉＮを被覆するのは、ＲＦスパッタリングにより行った。被覆の平均厚みは４０ｎｍである。また、Ｎｏ．２の混合において分散材は用いていない。
【００１４】
超音波混合法→アセトン中にｃＢＮと結合材の粉末を投入し、２３．５ｋＨｚの超音波振動を付加して混合した。
ＢＭ法→ポットに直径１０mmのボールとｃＢＮ粉末および結合材粉末を入れ、２３５rpm 、３４０分、エチルアルコール中で湿式混合を行った。
分散材→分散材としてポリビニルアルコールを１．５重量％添加した。
【００１５】
【表１】
そして、その混合粉末を５GPa、１３００℃の超高圧、高温下で焼結した。得られた焼結体のＸＲＤはどれもｃＢＮ、ＴｉＮ、ＴｉＢ2、ＡｌＢ2、ＡｌＮ、Ａｌ2Ｏ3、ＷＣが観測された。
【００１７】
これら焼結体の組織を金属組織顕微鏡で1500倍にて撮影したところ、黒く見えるｃＢＮ粒子と白く見える結合相が観察された。この写真で任意の直線を引き、結合相厚みを測定した。この測定は、上記任意の直線状における結合相の厚み、つまりｃＢＮ粒子間の距離を２０点以上測定し、測定値の平均を求めることで行う。そして、各測定値から表１に記載の平均値と標準偏差を求めた。
【００１８】
さらに、これら焼結体を切削工具に加工し、下記の条件で切削試験を実施し、欠損に至る工具寿命を測定したところ、表１に記載の結果が得られた。
【００１９】
切削試験条件：
被削材：ＳＣＭ４１５、ＨＲＣ５８−６２、φ１００mm×Ｌ３００mmで長手方向にＶ形状の溝が６本付けられた形状。
工具形状：ＳＮＧ４３２ ＮＬ−２５＊０．１５−０．２
ホルダー：ＦＮ１１Ｒ
切削条件：Ｖ＝１００m／min、ｄ＝０．２mm、ｆ＝０．１３mm／rev、ｄｒｙ
【００２０】
この結果から明らかなように、結合相厚さの平均値が１．０μm以下、その標準偏差が０．７以下の場合に工具寿命が倍程度に向上していることがわかる。また、このような結合相厚さを有する焼結体を作製するには、結合相材料を混合する際に、超音波混合法または分散材を用いたボールミル法が好ましいことがわかる。
【００２１】
（実施例２）
７３重量％のＴｉの窒化物、１９重量％のＡｌ、４重量％のＣｏおよび４重量％のＮｉを混合し、真空中で１２４０℃、３２分熱処理をした化合物を粉砕し、結合相粉末を作製した。ＸＲＤではＴｉＮ、Ｔｉ2ＡｌＮ、ＴｉＡｌ3等のピークがみられた。この結合相粉末と平均粒径０．５μmのｃＢＮ粉末を、ｃＢＮの体積含有率が６５％になるように超音波混合法と分散材を用いないボールミル（ＢＭ）法とで混合した。各混合法の詳細な条件は次の通りである。
【００２２】
超音波混合法→エチルアルコール中にｃＢＮと結合材の粉末を投入し、２２．３ｋＨｚの超音波振動を付加して混合した。
ＢＭ法→ポットに直径１０mmのボールとｃＢＮ粉末および結合材粉末を入れ、２１５rpm 、４５０分、アセトン中で湿式混合を行った。
【００２３】
そして、この粉末を４．８５GPa、１３１０℃の超高圧、高温下で焼結した。得られた焼結体のＸＲＤはどれもｃＢＮ、ＴｉＮ、ＴｉＢ2、ＡｌＢ2、ＡｌＮ、Ａｌ2Ｏ3、ＷＣが観察された。これら焼結体の組織を下記の方法で観察した。なお、下記の各方法において、結合相厚みの測定方法は実施例１と同様である。
1）金属組織顕微鏡にて1500倍で写真撮影したところ、黒く見えるcＢＮ粒子と白く見える結合相が観察された。この写真で任意の直線を引き、結合相厚みを測定した。
【００２４】
2）SEM(Scanning Electron Microscope)にて3000倍で写真撮影したところ、ｃＢＮ粒子と結合相が観察された。この写真で任意の直線を引き、結合相厚みを測定した。
【００２５】
3）TEM(Transmission Electron Microscope)にて10000倍で写真撮影したところ、ｃＢＮ粒子と結合相が観察された。この写真で任意の直線を引き、結合相厚みを測定した。
【００２６】
4）オージェ（Auger Electron Spectroscopy) にて10000倍で写真撮影したところ、ｃＢＮ粒子と結合相が観察された。この写真で任意の直線を引き、結合相厚みを測定した。
【００２７】
5）金属組織顕微鏡にて1500倍で撮影したところ、黒く見えるｃＢＮ粒子と白く見える結合相が観察された。これを画像解析し、ｃＢＮ粒子にあたる黒くみえる粒子の面積比率がｃＢＮの体積含有率と等しくなるように二値化し、結合相に相当する部分を特定し、結合相厚みを測定した。
【００２８】
6）金属組織顕微鏡にて1000倍で撮影したところ、黒く見えるｃＢＮ粒子と白く見える結合相が観察された。これを画像解析し、任意の直線上の輝度を測定したところ周期性が見られた。ある輝度で暗い部分（ｃＢＮ粒子に当たるところ）と明るい部分（結合相に当たるところ）にわけた場合、その比率がｃＢＮの体積含有率と等しくなるように輝度を決定し、明るい部分の長さを結合相厚みとした。
【００２９】
このようにして測定した結合相厚みの平均値と標準偏差を計算したところ表2のようになった。
【００３０】
【表２】
これら焼結体を切削工具に加工し、下記の条件で切削試験を実施し、欠損に至る工具寿命を測定したところ、超音波混合法の焼結体は約２０分、ボールミル法の焼結体は約５分で欠損した。従って、分散材を用いないボールミル法よりも超音波混合法により結合相材料を混合することが好ましいことがわかる。
【００３２】
切削試験条件：
被削材：ＳＣＭ４２０、ＨＲＣ５９−６１、φ100mm ×Ｌ300mm で長手方向にＶ形状の溝が８本付けられた形状。
工具形状：ＳＮＧ４３２ ＮＬ−２５＊０．１５−０．２
ホルダー：ＦＮ１１Ｒ
切削条件：Ｖ＝９０m／min、ｄ＝０．２３mm、ｆ＝０．１４mm／rev、dry
【００３３】
（実施例３）
９２重量％のＴｉの窒化物と１８重量％のＡｌを混合し、真空中で１２００℃、３０分熱処理をした化合物を粉砕し、結合相粉末を作製した。この粉末はＸＲＤではＴｉＮ、Ｔｉ2 ＡｌＮ、ＴｉＡｌ3等のピークがみられた。この結合相粉末を平均粒径１．５μｍのｃＢＮ粉末にｃＢＮの体積含有率が表３に記載の割合となるように被覆した。被覆はＲＦスパッタリングＰＶＤ装置を用いて行った。この被覆粉末をＴＥＭで観察したところ、ｃＢＮ粉末にＴｉＮが平均層厚４５ｎｍでほぼ均質に被覆されていることがわかった。このＴｉＮ被覆ｃＢＮ粒子および前記結合相粉末をボールミルで分散材を用いずに混合した。ＢＭ法による混合は、ポットに直径１０mmのボールとｃＢＮ粉末および結合材粉末を入れ、２３５rpm、５５０分、エチルアルコール中で湿式混合により行った。そして、この混合粉末を４．９GPa 、１３８０℃の超高圧、高温下で焼結した。得られた焼結体のＸＲＤはどれもｃＢＮ、ＴｉＮ、ＴｉＢ2、ＡｌＢ2、ＡｌＮ、Ａｌ2Ｏ3、ＷＣが観測された。
【００３４】
【表３】
これら焼結体の組織を金属組織顕微鏡にて1500倍で撮影したところ、黒く見えるｃＢＮ粒子と白く見える結合相が観察された。また、この写真で任意の直線を引き、結合相厚みを測定したところ、表３に示す平均値と標準偏差が得られた。
【００３６】
さらに、これら焼結体を切削工具に加工し、下記の条件で切削試験を実施し、欠損に至る工具寿命を測定した。その結果も表３に示す。
【００３７】
切削試験条件：
被削材：ＳＣＭ４１５、ＨＲＣ５８−６２、φ100mm×Ｌ300mmで長手方向にＶ形状の溝が６本付けられた形状。
工具形状：ＳＮＧ４３２ ＮＬ−２５＊０．１５−０．２
ホルダー：ＦＮ１１Ｒ
切削条件：Ｖ＝１１０m／min、ｄ＝０．１５mm、ｆ＝０．０９mm／rev、dry
【００３８】
これらの結果からｃＢＮの含有率は４５から７０体積％が好ましいことがわかる。
【００３９】
（実施例４）
種々の組成の結合相原料粉末を混合し、真空中で１２７０℃、２８分熱処理をした化合物を粉砕し、結合相粉末を作製した。この結合相粉末と平均粒径１．８μmのｃＢＮ粉末をｃＢＮの体積含有率が６４％になるように分散材を用いたボールミル法で混合した。ＢＭ法による混合は、ポットに直径１０mmのボールとｃＢＮ粉末および結合材粉末を入れ、２４５rpm、７５０分、エチルアルコール中で湿式混合により行った。分散材としては、ポリビニルアルコールを1.8重量％添加した。そして、混合粉末を４．８GPa、１３３０℃の超高圧、高温下で焼結した。得られた焼結体のＸＲＤには表４に記載の化合物のピークが観測された。
【００４０】
【表４】
これら焼結体の組織を金属組織顕微鏡にて1000倍で観察したところ黒く見えるｃＢＮ粒子と白く見える結合相が観察された。この写真で任意の直線を引き、結合相厚みを測定したところ、表４に記載の平均値と標準偏差が得られた。
【００４２】
さらに、これら焼結体を切削工具に加工し、下記の条件で切削試験を実施し、欠損に至る工具寿命を測定したところ表４に記載の結果が得られた。
【００４３】
切削試験条件：
被削材：ＳＣＭ４１５、ＨＲＣ５８−６２、φ100mm×Ｌ300mmで長手方向にＶ形状の溝が６本付けられた形状。
工具形状：ＳＮＧ４３２ ＮＬ−２５＊０．１５−０．２
ホルダー：ＦＮ１１Ｒ
切削条件：ｄ＝０．１５mm、ｆ＝０．１１mm／rｅv、dry
【００４４】
Ｎｏ．１８〜２５のいずれの試料も、結合相厚さの平均値が１μｍ以下で、その標準偏差が０．７以下である。そして、工具寿命はいずれも３０分前後と好結果が得られている。また、これからわかるように、結合相として周期律表4a,5a,6a族遷移金属の炭化物，窒化物，炭窒化物，硼化物、Ａｌの窒化物，硼化物，酸化物、Ｆｅ，Ｃｏ，Ｎｉの少なくとも1種の炭化物，窒化物，炭窒化物，硼化物、およびこれらの相互固溶体よりなる群から選択される1種以上のものが良いことがわかる。
【００４５】
（実施例５）
７８重量％のＴｉの窒化物、１６重量％のＡｌ、４重量％のＣｏおよび２重量％のＮｉを混合し、真空中で１２６０℃、２０分熱処理をした化合物を粉砕し、結合相粉末を作製した。この粉末はＸＲＤではＴｉＮ、Ｔｉ2ＡｌＮ、ＴｉＡｌ3等のピークがみられた。この結合相粉末と表5に記載の平均粒径のｃＢＮ粉末をｃＢＮの体積含有率が５７％になるように超音波混合法により混合した。超音波混合は、エチルアルコール中にｃＢＮと結合材の粉末を投入し、２０．５ｋＨｚの超音波振動を付加して行った。そして、この混合粉末を５．０GPa、１４００℃の超高圧、高温下で焼結した。得られた焼結体のＸＲＤはどれもｃＢＮ、ＴｉＮ、ＴｉＢ2、ＡｌＢ2、ＡｌＮ、Ａｌ2Ｏ3、ＷＣが観察された。
【００４６】
【表５】
これら焼結体の組織を金属組織顕微鏡にて1500倍で撮影したところ黒く見えるｃＢＮ粒子と白く見える結合相が観察された。この写真で任意の直線を引き、結合相厚みを測定したところ、表５に記載の平均値と標準偏差が得られた。
【００４８】
さらに、これら焼結体を切削工具に加工し、下記の条件で切削試験を実施し、欠損に至る工具寿命を測定したところ表５に記載の結果が得られた。
【００４９】
切削試験条件：
被削材：ＳＣＭ４１５、ＨＲＣ５８−６２、φ100mm×Ｌ300mmで長手方向にＶ形状の溝が６本付けられた形状。
工具形状：ＳＮＧ４３２ ＮＬ−２５＊０．１５−０．２
ホルダー：ＦＮ１１Ｒ
切削条件：Ｖ＝１００m／mｉn、ｄ＝０．２１mm、ｆ＝０．１２mm／rev、dry
【００５０】
この結果から明らかなように、ｃＢＮの平均粒径が０．０１μｍ以上２μｍ未満の場合に欠損を抑制できていることがわかる。
【００５１】
【発明の効果】
以上説明したように、本発明によれば、焼結体における結合相の厚みのばらつきを小さくすることで、耐摩耗性および耐欠損性に優れたｃＢＮ焼結体の切削工具を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cutting tool using a cubic boron nitride (cBN) sintered body and a manufacturing method thereof . In particular, wear resistance and chipping resistance is relates again and again by cutting Engineering improved.
[0002]
[Prior art]
cBN is a high-hardness substance next to diamond, and cBN-based sintered bodies are used for various cutting tools, wear-resistant parts, impact-resistant parts and the like.
[0003]
Examples of this type of sintered body include those described in JP-B-62-25630, JP-B-62-25631, and JP-A-5-186272.
[0004]
[Problems to be solved by the invention]
However, each of the above technologies is not always sufficient in terms of strength. For example, when the above-mentioned sintered body is used for a cutting tool, there is a problem that the tool tip is easily lost due to the impact in an application in which a strong impact is applied to the tool tip, resulting in unstable tool life.
[0005]
Accordingly, a main object of the present invention is to provide a cutting tool including a cBN sintered body having excellent fracture resistance by improving strength and a method for manufacturing the cutting tool .
[0006]
[Means for Solving the Problems]
The cutting tool of the present invention is a cutting tool having excellent fracture resistance including a sintered body obtained by sintering cBN particles with a binder phase. This bonded phase has a continuous structure in two dimensions. In addition, this bonded phase is at least one of carbides, nitrides, carbonitrides, borides, Al nitrides, borides, oxides, Fe, Co, and Ni of the transition metal groups 4a, 5a, and 6a. 1 or more selected from the group consisting of carbides, nitrides, carbonitrides, borides, and their mutual solid solutions. Furthermore, the average value of the binder phase thickness is 1.0 μm or less, and its standard deviation is 0.7 or less. Here, the binder phase thickness means the distance between the cBN particles and the cBN particles on an arbitrary straight line in the sintered body. On the other hand, the content of cBN is 45 to 70% by volume. The average particle size of the cBN particles is 0.01 or more and less than 2.0 μm. The average particle size means a particle size at which the cumulative volume% is 50%.
[0007]
A conventional cBN sintered body (cBN particles have an average particle size of 0.01 to 2 μm) has a standard deviation of the binder phase thickness exceeding 0.7. That is, there is a large variation in the thickness of the binder phase, and there is a portion that occupies a large volume only with the binder phase. This part is a weak part (defect) in the sintered body. When an impact is applied to the sintered body, stress is easily concentrated in this portion and the strength is weak. Therefore, fracture is likely to occur from this point, and the fracture resistance of the tool is not sufficient.
[0008]
In applications where impact is applied to the cutting edge, as described above, stress concentrates on the above defective part due to impact and the strength of this part is weak. It is done.
[0009]
Therefore, in the sintered body of the tool of the present invention, the variation in the binder phase thickness is made smaller than that of the conventional sintered body, so that the number of defective portions is reduced and the fracture resistance is improved. When the average thickness of the binder phase and its standard deviation exceed the above specified values, the portion occupying a large volume only with the binder phase increases, and the effect of improving the fracture resistance is small. Moreover, since the minimum of the average thickness of a binder phase exhibits the function as a binder phase, about 0.2 micrometer is preferable. In addition, if the cBN particles are finer than the above, the heat resistance of the particles is inferior and wear tends to develop. Therefore, the particle size of cBN particles is suitably 0.01-2 μm.
[0010]
In order to obtain a sintered body of the tool of the present invention, a binder phase material is coated on cBN, or raw materials are mixed by a special method. The coating of the binder phase material is induced by chemical vapor deposition (CVD), physical vapor deposition (PVD), electroless plating, or compressive shear force, friction force, and impact force during mechanical mixing before sintering. And a method utilizing a mechanochemical reaction. As a special mixing method, an ultrasonic mixing method or a ball mill method using a dispersing material is optimal.
[0011]
In addition, a plasma sintering apparatus, a hot press apparatus, an ultra-high pressure sintering apparatus, etc. can be utilized for the sintering process of the sintered compact of the tool of the present invention.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0013]
Example 1
76% by weight of Ti nitride, 18% by weight of Al, 3% by weight of Co, and 3% by weight of Ni were mixed, and the compound that had been heat-treated in a vacuum at 1200 ° C. for 30 minutes was pulverized to obtain a binder phase powder. Produced. In this binder phase powder, peaks such as TiN, Ti 2 AlN, TiAl 3 and the like were observed by XRD (X-ray diffraction). This binder phase powder and cBN powder having an average particle diameter of 1 μm were mixed by the method described in Table 1 so that the volume content of cBN was 60% by volume. The detailed conditions of each mixing method are as follows. Here, no. In step 2, cBN was coated with TiN by RF sputtering. The average thickness of the coating is 40 nm. No. No dispersing material is used in the mixing of 2.
[0014]
Ultrasonic mixing method-> cBN and binder powder were put into acetone and mixed with 23.5 kHz ultrasonic vibration.
BM method-> A ball having a diameter of 10 mm, a cBN powder, and a binder powder were placed in a pot, and wet mixing was performed in ethyl alcohol at 235 rpm for 340 minutes.
Dispersant → 1.5% by weight of polyvinyl alcohol was added as a dispersant.
[0015]
[Table 1]
Then, the mixed powder was sintered under 5 GPa, 1300 ° C., ultrahigh pressure and high temperature. Any resulting XRD of the sintered body cBN, TiN, TiB 2, AlB 2, AlN, Al 2 O 3, WC were observed.
[0017]
When the structures of these sintered bodies were photographed with a metallographic microscope at a magnification of 1500, cBN particles that appeared black and a binder phase that appeared white were observed. In this photograph, an arbitrary straight line was drawn and the binder phase thickness was measured. This measurement is performed by measuring 20 or more points of the thickness of the binder phase in the above arbitrary linear shape, that is, the distance between the cBN particles, and obtaining the average of the measured values. And the average value and standard deviation of Table 1 were calculated | required from each measured value.
[0018]
Furthermore, when these sintered bodies were processed into cutting tools, a cutting test was carried out under the following conditions, and the tool life leading to chipping was measured, the results shown in Table 1 were obtained.
[0019]
Cutting test conditions:
Work material: SCM415, HRC58-62, φ100mm × L300mm, with 6 V-shaped grooves in the longitudinal direction.
Tool shape: SNG432 NL-25 * 0.15-0.2
Holder: FN11R
Cutting conditions: V = 100 m / min, d = 0.2 mm, f = 0.13 mm / rev, dry
[0020]
As is apparent from this result, the tool life is improved by about twice when the average value of the binder phase thickness is 1.0 μm or less and the standard deviation is 0.7 or less. It can also be seen that, in order to produce a sintered body having such a binder phase thickness, an ultrasonic mixing method or a ball mill method using a dispersing material is preferable when mixing binder phase materials.
[0021]
(Example 2)
73% by weight of Ti nitride, 19% by weight of Al, 4% by weight of Co and 4% by weight of Ni were mixed, and the compound which had been heat-treated in vacuum at 1240 ° C. for 32 minutes was pulverized to obtain a binder phase powder. Produced. XRD showed peaks of TiN, Ti 2 AlN, TiAl 3 and the like. This binder phase powder and cBN powder having an average particle size of 0.5 μm were mixed by an ultrasonic mixing method and a ball mill (BM) method without using a dispersing material so that the volume content of cBN was 65%. The detailed conditions of each mixing method are as follows.
[0022]
Ultrasonic mixing method-> cBN and binder powder were put into ethyl alcohol, and 22.3 kHz ultrasonic vibration was added and mixed.
BM method-> A ball having a diameter of 10 mm, cBN powder and binder powder were put in a pot, and wet mixing was performed in acetone at 215 rpm for 450 minutes.
[0023]
Then, this powder was sintered at 4.85 GPa, an ultrahigh pressure of 1310 ° C., and a high temperature. Any resulting XRD of the sintered body cBN, TiN, TiB 2, AlB 2, AlN, Al 2 O 3, WC were observed. The structure of these sintered bodies was observed by the following method. In each of the following methods, the method for measuring the binder phase thickness is the same as in Example 1.
1) When photographed with a metallographic microscope at a magnification of 1500, cBN particles that look black and a binder phase that looks white were observed. In this photograph, an arbitrary straight line was drawn and the binder phase thickness was measured.
[0024]
2) When a photograph was taken with a scanning electron microscope (SEM) at a magnification of 3000, cBN particles and a binder phase were observed. In this photograph, an arbitrary straight line was drawn and the binder phase thickness was measured.
[0025]
3) When a photograph was taken with a TEM (Transmission Electron Microscope) at a magnification of 10,000, cBN particles and a binder phase were observed. In this photograph, an arbitrary straight line was drawn and the binder phase thickness was measured.
[0026]
4) When a photograph was taken at a magnification of 10,000 with an Auger Electron Spectroscopy, cBN particles and a binder phase were observed. In this photograph, an arbitrary straight line was drawn and the binder phase thickness was measured.
[0027]
5) When photographed at 1500 times with a metallographic microscope, cBN particles that look black and a binder phase that looks white are observed. This was image-analyzed, binarized so that the area ratio of black particles corresponding to cBN particles was equal to the volume content of cBN, the portion corresponding to the binder phase was identified, and the binder phase thickness was measured.
[0028]
6) When photographed at 1000 times with a metallographic microscope, cBN particles appearing black and a binder phase appearing white were observed. Image analysis of this and measurement of luminance on an arbitrary straight line showed periodicity. When it is divided into a dark part (where it hits cBN particles) and a bright part (where it hits the binder phase) at a certain brightness, the brightness is determined so that the ratio is equal to the volume content of cBN, and the length of the bright part is combined. The phase thickness was taken.
[0029]
The average value and the standard deviation of the binder phase thickness thus measured were calculated as shown in Table 2.
[0030]
[Table 2]
When these sintered bodies are processed into cutting tools, a cutting test is performed under the following conditions, and the tool life leading to fracture is measured, the sintered body of the ultrasonic mixing method is about 20 minutes, the sintered body of the ball mill method Was lost in about 5 minutes. Therefore, it can be seen that it is preferable to mix the binder phase material by the ultrasonic mixing method rather than the ball mill method without using the dispersing material.
[0032]
Cutting test conditions:
Work material: SCM420, HRC59-61, φ100mm × L300mm, with 8 V-shaped grooves in the longitudinal direction.
Tool shape: SNG432 NL-25 * 0.15-0.2
Holder: FN11R
Cutting conditions: V = 90 m / min, d = 0.23 mm, f = 0.14 mm / rev, dry
[0033]
(Example 3)
92% by weight of Ti nitride and 18% by weight of Al were mixed, and the compound that had been heat-treated at 1200 ° C. for 30 minutes in a vacuum was pulverized to produce a binder phase powder. This powder showed peaks of TiN, Ti 2 AlN, TiAl 3 and the like by XRD. This binder phase powder was coated on a cBN powder having an average particle size of 1.5 μm so that the volume content of cBN would be the ratio shown in Table 3. The coating was performed using an RF sputtering PVD apparatus. When this coated powder was observed with a TEM, it was found that TiN was coated almost uniformly with an average layer thickness of 45 nm on the cBN powder. The TiN-coated cBN particles and the binder phase powder were mixed with a ball mill without using a dispersing agent. Mixing by the BM method was performed by wet mixing in ethyl alcohol at 235 rpm for 550 minutes by putting a 10 mm diameter ball, cBN powder and binder powder into a pot. The mixed powder was sintered at 4.9 GPa, 1380 ° C. under high pressure and high temperature. Any resulting XRD of the sintered body cBN, TiN, TiB 2, AlB 2, AlN, Al 2 O 3, WC were observed.
[0034]
[Table 3]
When the structures of these sintered bodies were photographed with a metallographic microscope at a magnification of 1500, cBN particles that appeared black and a binder phase that appeared white were observed. Moreover, when arbitrary straight lines were drawn in this photograph and the binder phase thickness was measured, the average values and standard deviations shown in Table 3 were obtained.
[0036]
Furthermore, these sintered bodies were processed into cutting tools, a cutting test was carried out under the following conditions, and the tool life leading to chipping was measured. The results are also shown in Table 3.
[0037]
Cutting test conditions:
Work material: SCM415, HRC58-62, φ100mm × L300mm, with 6 V-shaped grooves in the longitudinal direction.
Tool shape: SNG432 NL-25 * 0.15-0.2
Holder: FN11R
Cutting conditions: V = 110 m / min, d = 0.15 mm, f = 0.09 mm / rev, dry
[0038]
From these results, it is understood that the content of cBN is preferably 45 to 70% by volume.
[0039]
Example 4
The binder phase raw material powders having various compositions were mixed, and the compound heat treated in vacuum at 1270 ° C. for 28 minutes was pulverized to produce binder phase powders. This binder phase powder and cBN powder having an average particle diameter of 1.8 μm were mixed by a ball mill method using a dispersing agent so that the volume content of cBN was 64%. Mixing by the BM method was carried out by wet mixing in ethyl alcohol at 245 rpm for 750 minutes with a 10 mm diameter ball, cBN powder and binder powder placed in a pot. As a dispersing agent, 1.8% by weight of polyvinyl alcohol was added. The mixed powder was sintered at 4.8 GPa, 1330 ° C. under high pressure and high temperature. The peaks of the compounds shown in Table 4 were observed in XRD of the obtained sintered body.
[0040]
[Table 4]
When the structures of these sintered bodies were observed with a metallographic microscope at a magnification of 1000, cBN particles that appeared black and a binder phase that appeared white were observed. When an arbitrary straight line was drawn in this photograph and the binder phase thickness was measured, the average values and standard deviations shown in Table 4 were obtained.
[0042]
Furthermore, when these sintered bodies were processed into cutting tools, a cutting test was performed under the following conditions, and the tool life leading to fracture was measured, the results shown in Table 4 were obtained.
[0043]
Cutting test conditions:
Work material: SCM415, HRC58-62, φ100mm × L300mm, with 6 V-shaped grooves in the longitudinal direction.
Tool shape: SNG432 NL-25 * 0.15-0.2
Holder: FN11R
Cutting conditions : d = 0.15 mm, f = 0.11 mm / lev, dry
[0044]
No. In any of the samples 18 to 25, the average value of the binder phase thickness is 1 μm or less, and the standard deviation thereof is 0.7 or less. And the tool life is about 30 minutes, and good results are obtained. As can be seen, the binder phase includes carbides, nitrides, carbonitrides, borides, Al nitrides, borides, oxides, Fe, Co, Ni of the periodic table 4a, 5a, 6a transition metals. It can be seen that at least one kind selected from the group consisting of at least one kind of carbide, nitride, carbonitride, boride, and their mutual solid solution is good.
[0045]
(Example 5)
78% by weight of Ti nitride, 16% by weight of Al, 4% by weight of Co and 2% by weight of Ni were mixed, and the compound which had been heat-treated in vacuum at 1260 ° C. for 20 minutes was pulverized. Produced. This powder showed peaks of TiN, Ti 2 AlN, TiAl 3 and the like by XRD. This binder phase powder and cBN powder having an average particle size described in Table 5 were mixed by an ultrasonic mixing method so that the volume content of cBN was 57%. Ultrasonic mixing was performed by adding cBN and binder powder in ethyl alcohol and applying ultrasonic vibration of 20.5 kHz. And this mixed powder was sintered under 5.0 GPa, 1400 degreeC ultrahigh pressure, and high temperature. Any resulting XRD of the sintered body cBN, TiN, TiB 2, AlB 2, AlN, Al 2 O 3, WC were observed.
[0046]
[Table 5]
When the structures of these sintered bodies were photographed with a metallographic microscope at a magnification of 1500, cBN particles that look black and a binder phase that looks white were observed. When an arbitrary straight line was drawn in this photograph and the binder phase thickness was measured, the average values and standard deviations shown in Table 5 were obtained.
[0048]
Furthermore, when these sintered bodies were processed into cutting tools, a cutting test was performed under the following conditions, and the tool life leading to fracture was measured, the results shown in Table 5 were obtained.
[0049]
Cutting test conditions:
Work material: SCM415, HRC58-62, φ100mm × L300mm, with 6 V-shaped grooves in the longitudinal direction.
Tool shape: SNG432 NL-25 * 0.15-0.2
Holder: FN11R
Cutting conditions: V = 100 m / min, d = 0.21 mm, f = 0.12 mm / rev, dry
[0050]
As is clear from this result, it can be seen that defects can be suppressed when the average particle size of cBN is 0.01 μm or more and less than 2 μm.
[0051]
【The invention's effect】
As described above, according to the present invention, a cutting tool of a cBN sintered body having excellent wear resistance and fracture resistance can be obtained by reducing the variation in the thickness of the binder phase in the sintered body. .
Claims (3)
前記結合相が二次元的に見て連続しており、
この結合相は、周期律表4a,5a,6a族遷移金属の炭化物，窒化物，炭窒化物，硼化物、Ａｌの窒化物，硼化物，酸化物、Ｆｅ，Ｃｏ，Ｎｉの少なくとも1種の炭化物，窒化物，炭窒化物，硼化物、およびこれらの相互固溶体よりなる群から選択される1種以上を含み、
ｃＢＮの含有率が体積％で４５−７０％で、
ｃＢＮ粒子の平均粒度が０．０１以上２．０μm未満であり、
結合相厚みの平均値が１．０μm以下で、その標準偏差が０．７以下であり、
この工具は、１１０m／min以下の速度で切削加工するための工具であることを特徴とする耐欠損性に優れた切削工具。A cutting tool having excellent fracture resistance, comprising a sintered body obtained by sintering cBN particles in a binder phase,
The bonded phase is continuous in two dimensions,
This binder phase includes at least one of carbides, nitrides, carbonitrides, borides, Al nitrides, borides, oxides, Fe, Co, and Ni of the transition metal groups 4a, 5a, and 6a. Including one or more selected from the group consisting of carbides, nitrides, carbonitrides, borides, and their mutual solid solutions,
The cBN content is 45-70% by volume,
the average particle size of the cBN particles is 0.01 or more and less than 2.0 μm,
The average value of the binder phase thickness is 1.0 μm or less, and its standard deviation is 0.7 or less,
This tool is a tool for cutting at a speed of 110 m / min or less, and is a cutting tool excellent in fracture resistance.
（1）超音波混合法
（2）分散材を用いたボールミル法
（3）この原料粉末のｃＢＮ粒子が前記結合相材料で被覆された粒子を、分散材を用いないボールミル法で混合する方法 2. The cutting tool with excellent fracture resistance according to claim 1, obtained by mixing raw material powder composed of cBN particles and binder phase powder by any of the following methods.
(1) Ultrasonic mixing method (2) Ball mill method using dispersion material
(3) A method of mixing particles obtained by coating cBN particles of the raw material powder with the binder phase material by a ball mill method without using a dispersing agent.
上記ｃＢＮ粒子と結合相粉末とを以下のいずれかの方法でｃＢＮの含有率が体積％で４５−７０％となるように混合する工程と、
（1）超音波混合法
（2）分散材を用いたボールミル法
（3）この原料粉末のｃＢＮ粒子が前記結合相材料で被覆された粒子を、分散材を用いないボールミル法で混合する方法
混合された原料粉末を焼結して、結合相厚みの平均値を１．０μm以下、その標準偏差を０．７以下とし、１１０m／min以下の速度で切削加工するための工具を得る工程とを備えることを特徴とする耐欠損性に優れた切削工具の製造方法。CBN particles having an average particle size of 0.01 or more and less than 2.0 μm, and carbides, nitrides, carbonitrides, borides, Al nitrides, borides, oxides of group 4a, 5a, 6a of the periodic table Preparing at least one binder phase powder selected from the group consisting of at least one carbide of Fe, Co, Ni, nitride, carbonitride, boride, and their mutual solid solutions;
Mixing the cBN particles and the binder phase powder by any of the following methods so that the cBN content is 45-70% by volume;
(1) Ultrasonic mixing method (2) Ball mill method using dispersion material
(3) A method in which the particles of cBN particles of the raw material powder coated with the binder phase material are mixed by a ball mill method without using a dispersing material. The mixed raw material powder is sintered, and the average value of the binder phase thickness is determined. And a step of obtaining a tool for cutting at a speed of 110 m / min or less, with a standard deviation of 0.7 μm or less and a standard deviation of 0.7 or less, and a method for producing a cutting tool with excellent fracture resistance .
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22368098A JP4787388B2 (en) | 1998-07-22 | 1998-07-22 | Cutting tool with excellent fracture resistance and manufacturing method thereof |
| US09/357,970 US6316094B1 (en) | 1998-07-22 | 1999-07-21 | Cubic boron nitride sintered body |
| KR1019990029426A KR100333459B1 (en) | 1998-07-22 | 1999-07-21 | cBN Sintered Body |
| RU99116051/02A RU2220929C2 (en) | 1998-07-22 | 1999-07-21 | Sintered blanc from boron nitride with cubic lattice (options) |
| EP99305813A EP0974566B1 (en) | 1998-07-22 | 1999-07-22 | Cubic boron nitride sintered body |
| DE69917993T DE69917993T2 (en) | 1998-07-22 | 1999-07-22 | Cube boron nitride sintered body |
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| JP22368098A JP4787388B2 (en) | 1998-07-22 | 1998-07-22 | Cutting tool with excellent fracture resistance and manufacturing method thereof |
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| JP2008133578A Division JP2008208027A (en) | 2008-05-21 | 2008-05-21 | cBN SINTERED COMPACT |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR101226376B1 (en) * | 2004-10-29 | 2013-01-24 | 엘리먼트 씩스 (프로덕션) (피티와이) 리미티드 | Cubic boron nitride compact |
| CN101218189B (en) * | 2005-07-15 | 2013-04-03 | 住友电工硬质合金株式会社 | Composite sintered compact |
| EP1922429B2 (en) * | 2005-08-16 | 2019-01-23 | Element Six Abrasives S.A. | Fine grained polycrystalline abrasive material |
| JP5157056B2 (en) * | 2005-09-22 | 2013-03-06 | 株式会社タンガロイ | Cubic boron nitride sintered body, coated cubic boron nitride sintered body, and cutting tool for hardened steel comprising the same |
| ZA200803807B (en) * | 2005-10-28 | 2009-10-28 | Element Six Production Pty Ltd | Cubic boron nitride compact |
| WO2007110770A2 (en) | 2006-03-29 | 2007-10-04 | Element Six (Production) (Pty) Ltd | Polycrystalline abrasive compacts |
| US8999023B2 (en) | 2006-06-12 | 2015-04-07 | Sumitomo Electric Hardmetal Corp. | Composite sintered body |
| JP5078061B2 (en) * | 2006-10-13 | 2012-11-21 | 住友電気工業株式会社 | Cubic boron nitride sintered body |
| WO2012029440A1 (en) | 2010-09-01 | 2012-03-08 | 住友電工ハードメタル株式会社 | Cubic boron nitride sintered compact tool |
| KR101414910B1 (en) | 2010-10-19 | 2014-07-04 | 스미또모 덴꼬오 하드메탈 가부시끼가이샤 | Tool comprising sintered cubic boron nitride |
| KR101848941B1 (en) | 2010-10-27 | 2018-04-13 | 스미또모 덴꼬오 하드메탈 가부시끼가이샤 | Sintered cubic boron nitride compact and sintered cubic boron nitride compact tool |
| JP5126702B1 (en) * | 2011-09-12 | 2013-01-23 | 三菱マテリアル株式会社 | Cutting tool made of cubic boron nitride based sintered material |
| JP5305056B1 (en) | 2012-05-16 | 2013-10-02 | 三菱マテリアル株式会社 | Cutting tool made of cubic boron nitride based sintered body |
| JP5784679B2 (en) * | 2013-08-12 | 2015-09-24 | エレメント シックス アブラシヴェス エス．エー． | Polycrystalline abrasive molding |
| JP6355124B2 (en) | 2014-04-25 | 2018-07-11 | 住友電工ハードメタル株式会社 | Surface coated boron nitride sintered body tool |
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1998
- 1998-07-22 JP JP22368098A patent/JP4787388B2/en not_active Expired - Lifetime
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