JP4035068B2

JP4035068B2 - Cemented carbide rotating tool

Info

Publication number: JP4035068B2
Application number: JP2003048340A
Authority: JP
Inventors: 滋松下; 暢生吉田
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2003-02-25
Filing date: 2003-02-25
Publication date: 2008-01-16
Anticipated expiration: 2023-02-25
Also published as: JP2004255509A

Description

【０００１】
【発明の属する技術分野】
本発明は超硬合金製回転工具に関するものである。
【０００２】
【従来の技術】
従来より、金属の切削加工に広く用いられている超硬合金は、ＷＣ粒子を主体とする硬質相と、Ｃｏ等の鉄族金属の結合相からなるＷＣ−Ｃｏ系合金、もしくは上記ＷＣ−Ｃｏ系に周期律表第４ａ、５ａ、６ａ族金属の炭化物、窒化物、炭窒化物等の固溶体相を分散せしめた系が知られている。
【０００３】
一方、プリント基板加工用の素材としては、Ｃｒ（クロム）やＶ（バナジウム）等の粒成長抑制剤を添加したＷＣ粒子の粒径が１μｍより小さい、いわゆる超微粒超硬合金が主として用いられ、高硬度、高強度であることを活かして、耐欠損性および耐摩耗性に優れ、かつ穴位置精度の高いドリルが公用されている（例えば特許文献１参照）。
【０００４】
かかるプリント基板加工用のドリルについては、最近、プリント基板の高密度化に伴って加工される穴径が微細化する傾向にあり、ドリル径も小径化すること、および穴開け加工効率を高めるために、ドリルの回転速度を１００，０００ｒｐｍ以上に高めた高速切削化が要求されている（例えば特許文献２参照）。また、エンドミル加工等の他の回転工具においても同様な傾向にあり、高速切削化による加工効率の向上が求められている。
【０００５】
〔特許文献１〕
特開昭６１−１２８４７号公報
〔特許文献２〕
特開２００１−２３９４１１号公報
【０００６】
【発明が解決しようとする課題】
しかしながら、最近のドリル径の小径化および高速切削化の要求に対して、上記従来の超微粒超硬合金では、ドリル先端が切削によって高温となり、そのためにドリル先端がプリント基板中の銅配線と溶着しやすくなったり、加工くずの排出性が悪くなる影響で先端刃先がさらに摩耗しやすくなってしまい、刃先の摩耗に伴って切削抵抗が高くなり工具寿命が短くなる傾向にあるという問題があった。
【０００７】
したがって、本発明の目的は、ドリルの小径化や高速切削化においても耐摩耗性に優れ、長寿命の切削が可能な超硬合金製回転工具を提供することにある。
【０００８】
【課題を解決するための手段】
本発明者は、上記課題に対して検討した結果、工具の原料粉末の性状および焼成条件を制御するとともにドリル形状等の工具形状に加工した後にこの工具の表面を所定条件で酸化処理または酸素イオン注入処理などの方法にて酸素濃度の高い状態とすることによって、平均粒径０．５μｍ以下のＷＣ粒子とコバルトからなるとともに高温における酸化増量が少ない超硬合金にて工具を作製できる結果、コーティングを施すことなく工具表面の耐熱性、耐酸化性を高めることができ、かつ、耐摩耗性に優れた超硬合金製回転工具となることを知見した。
【０００９】
すなわち、本発明の超硬合金製回転工具は、シャンク部、フルート部および切刃部を備えた超硬合金製回転工具であって、前記超硬合金が平均粒径０．５μｍ以下のＷＣ粒子間を５〜１５質量％のコバルトを主体とする結合相にて結合した組織からなるとともに、前記回転工具を大気中、室温から昇温速度１０℃／分で７００℃まで昇温して１時間保持した時の酸化増量が０．２ｍｇ／ｍｍ^２以下であり、かつ前記超硬合金の表面における酸素含有量が前記超硬合金の内部における酸素含有量に比べて多いことを特徴とするものである。
【００１０】
ここで、前記超硬合金の表面における硬度が前記超硬合金内部における硬度に比べて高いことによって、高温における耐酸化性、耐溶着性および耐摩耗性をより高めることができる。
【００１１】
また、前記超硬合金中に、バナジウム、クロム、タンタルおよびニオブを炭化物換算による総量で０．２〜３質量％の割合で含有せしめることにより、酸化増量を上記所定量以下にせしめることができるとともに、合金中の炭化タングステン粒子の粒径を微細化して合金の抗折強度を高めることができる。
【００１２】
【発明の実施の形態】
本発明の超硬合金製回転工具について、その一例であるドリルの概略側面図である図１を基に説明する。
【００１３】
図１のドリル１は、シャンク部２、フルート部３および切刃部４を備えた超硬合金からなり、本発明によれば、この超硬合金が平均粒径０．５μｍ以下のＷＣ粒子間を３〜１３質量％のコバルトを主体とする結合相にて結合した組織からなるものである。
【００１４】
本発明によれば、ドリル１を大気中、室温から昇温速度１０℃／分で７００℃まで昇温して１時間保持した時の酸化増量が０．２ｍｇ／ｍｍ^２以下、特に０．１５ｍｇ／ｍｍ^２以下、０．１２ｍｇ／ｍｍ^２以下であることが大きな特徴であり、これによって、ドリル１の先端が高温となった場合でもドリルの先端がプリント基板中の銅配線と溶着しやすくなったり、加工くずの影響によって摩耗しやすくなることなく、耐摩耗性に優れ、微細で高精度な穴開け加工が行えるドリルとなる。
【００１５】
すなわち、従来の超微粒超硬合金からなるドリルのように、酸化増量が０．２ｍｇ／ｍｍ^２を超えると、ドリルが高温となったときの耐溶着性および耐摩耗性が低下する恐れがある。
【００１６】
なお、上記のように、高温における酸化増量を低減する好適な方法としては、ドリル１の形状に加工した後、後述する所定の条件で酸化処理または酸素イオン注入処理を施す方法が挙げられる。
【００１７】
ここで、本発明によれば、ＷＣ粒子の平均粒径は０．５μｍ以下、特に０．１〜０．４μｍ、さらに０．２〜０．３μｍとすることが重要であり、これにより超硬合金の硬度および抗折強度を向上させることができ、耐摩耗性および耐折損性の高いドリルとなる。
【００１８】
また、本発明によれば、上記超硬合金においては、結合相をなすコバルトの含有量は５〜１５質量％であることがドリルとして必要な硬度および強度を満足するために必要であるが、小径化、穴位置精度の向上のためにドリルの変形を起こさない点では、結合相をなすコバルトの含有量は特に６〜１０質量％、さらには６〜８質量％であることが望ましい。
【００１９】
また、本発明によれば、上記表面処理によってドリル１の表面における酸素含有量がドリル１の内部における酸素含有量に比べて多くなるように制御することが重要であり、これによって、従来公知のコーティングのような高コスト化を招く手法を用いることなく、上述した高温における耐酸化性、耐溶着性および耐摩耗性の高いドリルとなる。
【００２０】
さらに、本発明によれば、上記表面処理によって、ドリル１の表面における硬度がドリル１の内部における硬度に比べて高くなることが望ましく、これによってドリル１の耐摩耗性をさらに高めることができる。
【００２１】
また、本発明によれば、超硬合金中にＶ、Ｃｒ、ＴａおよびＮｂの群から選ばれる少なくとも１種の高融点金属を炭化物換算による総量で０．２〜３質量％、特に０．２〜２質量％の割合で含有せしめることが望ましく、これによって、上記条件での酸化増量をより低減することができるとともに、ＷＣ粒子を微粒化して合金の硬度、抗折強度を高め、かつ耐衝撃性を向上する効果がある。
【００２２】
さらに、本発明によれば、前記超硬合金の高温における酸化増量を低減するために、合金組織中、ＷＣ粒子の平均粒径に対して１／５以下の粒径である微粒ＷＣ粒子の数をＷＣ粒子全体の数に対して１０％以下、かつＷＣ粒子の平均粒径に対して３倍以上の粒径を有する粗粒の数がＷＣ粒子全体の数に対して１０％以下であることが望ましい。
【００２３】
（製造方法）
また、上述した超硬合金を製造するには、まず、例えば平均粒径０．０５〜０．５μｍのＷＣ粉末を８０〜９０質量％、平均粒径０．２〜０．８μｍの金属Ｃｏ粉末を３〜１５質量％に加えて、平均粒径０．３〜１．０μｍのＶＣ粉末、平均粒径０．８〜２．０μｍのＣｒ_３Ｃ_２粉末、平均粒径１．０〜２．５μｍのＴａＣ粉末、および平均粒径０．８〜２．０μｍのＮｂＣ粉末を炭化物換算による総量で０．５〜３．０質量％、さらには所望により、金属タングステン（Ｗ）粉末、あるいはカーボンブラック（Ｃ）を混合する。
【００２４】
本発明によれば、上記混合に際して、メタノール等の有機溶媒を加え、粉砕メディアとしてＷＣ平均粒径が０．２〜０．５μｍの超硬合金からなる粉砕ボール（φ３ｍｍ〜φ６ｍｍ）を用いて、５０〜８０時間振動ミル粉砕するか、あるいは４０〜６０時間アトライタ粉砕することが合金中のＷＣ粒子の粒径を制御する点で望ましい。
【００２５】
次に、上記混合粉末を用いて、プレス成形、鋳込成形、押出成形、冷間静水圧プレス成形等の公知の成形方法によって所定形状に成形した後、１３２０〜１３８０℃で０．５〜１時間真空焼成し、該焼成温度よりも５〜５０℃低い温度で０．５〜１時間熱間静水圧プレス焼成（ＳｉｎｔｅｒＨＩＰ）をして３〜６℃／分にて冷却する。
【００２６】
ここで、上記工程のうち、焼成温度が１３２０℃より低いと超硬合金の焼結性が低下してしまい、逆に焼成温度が１３８０℃より高いと炭化タングステン粒子が粒成長してしまい強度が低下するとともに、酸化増量が規定値を超えてしまい、工具が高温になった場合の耐酸化性、耐溶着性および耐摩耗性が低下する。また、熱間静水圧プレス焼成温度が最高保持温度より５℃以上低くないと、焼結が進行しすぎて合金の酸化増量が規定値を超えてしまい、逆に熱間静水圧プレス焼成温度が最高保持温度と比較して５０℃より低い場合、酸化増量が増して焼結性が低下してドリル寿命が低下する。
【００２７】
そして、本発明によれば、上記超硬合金をドリル等所定の工具形状に加工した後、２００℃〜４００℃で、大気中１時間保持の条件で酸化処理をするか、もしくは、エネルギー１００〜２００ＫｅＶ、注入量１×１０^１５ｉｏｎ／ｃｍ^２〜１×１０^１７ｉｏｎ／ｃｍ^２の条件で酸素イオン注入処理などを施すことにより、上述した超硬合金製回転工具を得ることができる。
【００２８】
また、上述した本発明の超硬合金製回転工具は、高硬度、高強度に優れるとともに、優れた耐摩耗性を有することから、特にプリント基板加工用ドリルとして好適に使用可能であるが、金属加工用のドリルやエンドミル等としても好適である。
【００２９】
【実施例】
（実施例）
表１に示す平均粒径の炭化タングステン（ＷＣ）粉末、平均粒径０．６μｍの金属コバルト（Ｃｏ）粉末および平均粒径０．７μｍのＶＣ粉末、平均粒径１．５μｍのＣｒ_３Ｃ_２粉末、平均粒径２．０μｍのＴａＣ粉末、平均粒径２．０μｍのＮｂＣ粉末を表１に示す比率で添加し、溶媒としてメタノールを、粉砕メディアとして、平均粒径０．３μｍのＷＣ粒子を主体とする超微粒子超硬合金からなる直径５ｍｍのボールを加えて振動ミル混合し、乾燥した後、プレス成形により丸棒形状に成形し、焼成温度より５００℃以上低い温度から１０℃／分の速度で昇温して、表１に示す条件で焼成して超硬合金を作製した。
【００３０】
得られた超硬合金を２枚刃形状のドリル形状に加工し、一部の試料については、
大気雰囲気中、３００℃で１時間の酸化処理（昇降温速度１０℃／分）、またはエネルギー１５０ＫｅＶ、注入量１×１０^１７ｉｏｎ／ｃｍ^２の条件で酸素イオン注入を施した（試料Ｎｏ．１〜４、７）。
【００３１】
得られたドリルに対して、大気中、昇温速度１０℃／分で７００℃まで昇温して１時間保持する熱処理を施し、処理前後での重量差から酸化増量を算出した。なお、酸化増量の算出に当たりドリルの比表面積は図面形状から算出して求めた。また、上記ドリルのシャンク部の表面およびシャンク部を２分割した内部におけるビッカース硬度を測定した。さらに、オージェ分析によってドリルの表面から内部に向かって酸素濃度の変化を測定した。結果は表１に示した。
【００３２】
また、前記超硬合金製ドリル形状にて、下記条件によってプリント基板の孔あけ加工テストを行い、テスト後、ＳＥＭ観察によって摩耗量を測定した。
【００３３】
＜条件＞
被削材：ＦＲ４・６層板、１．６ｍｍ厚、３枚重ね
ドリル形状：φ０．１５ｍｍアンダーカットタイプ
回転数：１２０ｋｒ．ｐ．ｍ．
送り速度：２．４ｍ／分
穴あけ数：３，０００ｈｉｔｓ
【表１】

【００３４】
表１の結果より、表面処理を施さなかった試料Ｎｏ．５、６では酸化増量が０．２ｍｇ／ｍ^２より多く、耐摩耗性が低下した。また、焼成条件が所定の条件から外れる試料Ｎｏ．７においても酸化増量が０．２ｍｇ／ｍ^２より多く、耐摩耗性が低下した。
【００３５】
これに対して、本発明に従い、所定の原料を用い所定の条件にて焼成して表面処理を施すことによって、大気中、室温から昇温速度１０℃／分で７００℃まで昇温して１時間保持した時の酸化増量が０．２ｍｇ／ｍｍ^２以下である試料Ｎｏ．１〜４では、摩耗量５０μｍ以下の優れた耐摩耗性を示すものであった。
【００３６】
【発明の効果】
以上詳述したとおり、本発明の超硬合金製回転工具によれば、工具の原料粉末の性状および焼成条件を制御するとともにドリル形状等の工具形状に加工した後にこの工具の表面を所定条件で酸化処理または酸素イオン注入処理などの方法にて酸素濃度の高い状態とする方法等によって、平均粒径０．５μｍ以下のＷＣ粒子とコバルトからなり、大気中、室温から昇温速度１０℃／分で７００℃まで昇温して１時間保持した時の酸化増量が０．２ｍｇ／ｍｍ^２以下に制御され、かつ前記超硬合金の表面における酸素含有量が前記超硬合金の内部における酸素含有量に比べて多い本発明の超硬合金製回転工具は、コーティングを施すことなく工具表面の耐熱性、耐酸化性を高めることができ、かつ、耐摩耗性に優れた性能を発揮する超硬合金製回転工具である。
【図面の簡単な説明】
【図１】本発明の超硬合金製回転工具の一例であるドリルの概略側面図である。
【符号の説明】
１ドリル
２シャンク部
３フルート部
４切刃部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cemented carbide rotary tool.
[0002]
[Prior art]
Conventionally, a cemented carbide widely used for metal cutting is a WC-Co alloy composed of a hard phase mainly composed of WC particles and a binding phase of an iron group metal such as Co, or the above WC-Co. There is known a system in which solid solution phases such as carbides, nitrides, carbonitrides and the like of Group 4a, 5a, and 6a metals of the periodic table are dispersed in the system.
[0003]
On the other hand, as a material for processing a printed circuit board, a so-called ultrafine cemented carbide is mainly used in which the particle size of WC particles to which a grain growth inhibitor such as Cr (chromium) or V (vanadium) is added is smaller than 1 μm. Taking advantage of its high hardness and high strength, a drill having excellent fracture resistance and wear resistance and high hole position accuracy is in public use (see, for example, Patent Document 1).
[0004]
With respect to drills for processing such printed circuit boards, the diameter of holes processed in recent years tends to become finer as the density of printed circuit boards increases, so that the drill diameter can be reduced and the drilling efficiency can be increased. In addition, high-speed cutting is required in which the rotation speed of the drill is increased to 100,000 rpm or more (see, for example, Patent Document 2). In addition, other rotating tools such as end milling tend to have the same tendency, and improvement in machining efficiency by high-speed cutting is required.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 61-12847 [Patent Document 2]
JP-A-2001-239411 [0006]
[Problems to be solved by the invention]
However, in response to the recent demand for drill diameter reduction and high-speed cutting, the above-mentioned conventional ultra-fine cemented carbide has a high temperature at the drill tip due to cutting, so the drill tip is welded to the copper wiring in the printed circuit board. There is a problem that the cutting edge of the tip is more likely to wear due to the ease of cutting and the chip scraping performance becomes worse, and the cutting resistance tends to increase with the wear of the cutting edge and the tool life tends to be shortened. .
[0007]
Accordingly, an object of the present invention is to provide a cemented carbide rotating tool that is excellent in wear resistance and can be cut for a long life even when the diameter of the drill is reduced or the cutting speed is increased.
[0008]
[Means for Solving the Problems]
As a result of studying the above problems, the inventor has controlled the properties and firing conditions of the raw material powder of the tool, and after processing the tool surface into a tool shape such as a drill shape, the surface of the tool is subjected to oxidation treatment or oxygen ions under predetermined conditions. As a result of being able to produce a tool with a cemented carbide consisting of WC particles with an average particle size of 0.5 μm or less and cobalt and having a low oxidation increase at high temperatures by making the oxygen concentration high by a method such as injection treatment, coating It has been found that the heat resistance and oxidation resistance of the tool surface can be improved without applying a tempering tool and that the rotating tool is made of cemented carbide with excellent wear resistance.
[0009]
That is, the cemented carbide rotating tool of the present invention is a cemented carbide rotating tool having a shank portion, a flute portion, and a cutting edge portion, and the cemented carbide is a WC particle having an average particle size of 0.5 μm or less. It consists of a structure bonded with a binder phase mainly composed of 5 to 15% by mass of cobalt, and the rotary tool is heated from room temperature to 700 ° C. at a heating rate of 10 ° C./min in the air for 1 hour. which oxidation weight gain at the time of holding is equal to or 0.2 mg / mm ² Ri der less, and the oxygen content in the surface of the cemented carbide larger than the oxygen content in the interior of the cemented carbide It is.
[0010]
Here, the hardness at the surface of the pre-Symbol cemented carbide higher than the hardness at the inside of the cemented carbide, it is possible to improve the oxidation resistance, welding resistance and wear resistance at high temperatures.
[0011]
Further, by adding vanadium, chromium, tantalum and niobium in the cemented carbide in a ratio of 0.2 to 3% by mass in terms of carbide, the oxidation increase can be reduced to the above predetermined amount or less. The bending strength of the alloy can be increased by reducing the particle size of the tungsten carbide particles in the alloy.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The cemented carbide rotary tool of the present invention will be described with reference to FIG. 1 which is a schematic side view of a drill as an example.
[0013]
The drill 1 in FIG. 1 is made of a cemented carbide provided with a shank part 2, a flute part 3 and a cutting edge part 4, and according to the present invention, the cemented carbide is formed between WC particles having an average particle size of 0.5 μm or less. Is made of a structure in which 3 to 13% by mass of cobalt as a main component is bound.
[0014]
According to the present invention, when the drill 1 is heated from room temperature to 700 ° C. at a heating rate of 10 ° C./min in the atmosphere and held for 1 hour, the oxidation increase is 0.2 mg / mm ² or less, particularly 0.15 mg. / Mm ² or less and 0.12 mg / mm ² or less, which makes it easy to weld the tip of the drill to the copper wiring in the printed circuit board even when the tip of the drill 1 becomes hot. In addition, the drill is excellent in wear resistance and can perform fine and high-precision drilling without being easily worn by the influence of processing waste.
[0015]
That is, when the amount of increase in oxidation exceeds 0.2 mg / mm ² , as in a drill made of a conventional ultra-fine cemented carbide, there is a risk that the welding resistance and wear resistance when the drill reaches a high temperature may be reduced. .
[0016]
As described above, as a suitable method for reducing the increase in oxidation at high temperatures, there is a method in which after processing into the shape of the drill 1, an oxidation treatment or an oxygen ion implantation treatment is performed under a predetermined condition described later.
[0017]
Here, according to the present invention, it is important that the average particle diameter of the WC particles is 0.5 μm or less, particularly 0.1 to 0.4 μm, and more preferably 0.2 to 0.3 μm. The hardness and bending strength of the alloy can be improved, resulting in a drill with high wear resistance and high bending resistance.
[0018]
Further, according to the present invention, in the cemented carbide, it is necessary for the content of cobalt forming the binder phase to be 5 to 15% by mass in order to satisfy the hardness and strength required as a drill, In view of preventing the deformation of the drill in order to reduce the diameter and improve the hole position accuracy, the content of cobalt constituting the binder phase is particularly preferably 6 to 10% by mass, and more preferably 6 to 8% by mass.
[0019]
In addition, according to the present invention, it is important to control the oxygen content on the surface of the drill 1 to be higher than the oxygen content in the drill 1 by the surface treatment. The drill having high oxidation resistance, welding resistance, and wear resistance at the above-described high temperature can be obtained without using a method that causes high cost such as coating.
[0020]
Furthermore, according to the present invention, it is desirable that the hardness on the surface of the drill 1 is higher than the hardness in the drill 1 by the surface treatment, and thereby the wear resistance of the drill 1 can be further improved.
[0021]
According to the present invention, at least one refractory metal selected from the group of V, Cr, Ta and Nb in the cemented carbide is 0.2 to 3% by mass, particularly 0.2% in terms of carbide. It is desirable to make it contained in a ratio of ˜2% by mass, which can further reduce the increase in oxidation under the above-mentioned conditions, and atomize the WC particles to increase the hardness and bending strength of the alloy, and impact resistance There is an effect to improve the performance.
[0022]
Furthermore, according to the present invention, in order to reduce the increase in oxidation of the cemented carbide at a high temperature, the number of fine WC particles having a particle size of 1/5 or less of the average particle size of the WC particles in the alloy structure. 10% or less of the total number of WC particles, and the number of coarse particles having a particle size 3 times or more the average particle size of WC particles is 10% or less of the total number of WC particles. Is desirable.
[0023]
(Production method)
In order to produce the above cemented carbide, first, for example, a WC powder having an average particle size of 0.05 to 0.5 μm is 80 to 90% by mass, and a metal Co powder having an average particle size of 0.2 to 0.8 μm. Is added to 3 to 15% by mass, a VC powder having an average particle size of 0.3 to 1.0 μm, a Cr ₃ C ₂ powder having an average particle size of 0.8 to 2.0 μm, and an average particle size of 1.0 to 2. 5 μm TaC powder and NbC powder having an average particle diameter of 0.8 to 2.0 μm in terms of carbide in a total amount of 0.5 to 3.0% by mass, and further, if desired, metallic tungsten (W) powder or carbon black Mix (C).
[0024]
According to the present invention, during the mixing, an organic solvent such as methanol is added, and a grinding ball (φ3 mm to φ6 mm) made of a cemented carbide having a WC average particle size of 0.2 to 0.5 μm is used as a grinding medium. In order to control the particle size of the WC particles in the alloy, vibration milling for 50 to 80 hours or attritor grinding for 40 to 60 hours is desirable.
[0025]
Next, the mixture powder is molded into a predetermined shape by a known molding method such as press molding, casting molding, extrusion molding, cold isostatic pressing, and then 0.5 to 1 at 1320 to 1380 ° C. Vacuum baking is performed for a period of time, and hot isostatic pressing (Sinter HIP) is performed at a temperature 5 to 50 ° C. lower than the baking temperature for 0.5 to 1 hour, followed by cooling at 3 to 6 ° C./min.
[0026]
Here, among the above steps, when the firing temperature is lower than 1320 ° C., the sinterability of the cemented carbide decreases, and conversely, when the firing temperature is higher than 1380 ° C., the tungsten carbide particles grow and the strength is increased. In addition to the decrease, the oxidation increase exceeds the specified value, and the oxidation resistance, welding resistance, and wear resistance when the tool becomes high temperature decreases. If the hot isostatic press firing temperature is not lower than the maximum holding temperature by 5 ° C. or more, the sintering proceeds too much and the oxidation increase of the alloy exceeds the specified value, and conversely the hot isostatic press firing temperature is When the temperature is lower than 50 ° C. compared to the maximum holding temperature, the amount of increase in oxidation increases, the sinterability decreases, and the drill life decreases.
[0027]
And according to this invention, after processing the said cemented carbide alloy into predetermined tool shapes, such as a drill, it oxidizes on the conditions hold | maintained at 200 degreeC-400 degreeC for 1 hour in air | atmosphere, or energy 100- The cemented carbide rotary tool described above can be obtained by performing an oxygen ion implantation process or the like under the conditions of 200 KeV and an injection amount of 1 × 10 ¹⁵ ion / cm ² to 1 × 10 ¹⁷ ion / cm ² .
[0028]
The above-described cemented carbide rotary tool of the present invention is excellent in high hardness and high strength, and has excellent wear resistance, so that it can be suitably used as a drill for processing printed circuit boards. It is also suitable as a machining drill or end mill.
[0029]
【Example】
(Example)
Tungsten carbide (WC) powder having an average particle size shown in Table 1, metallic cobalt (Co) powder having an average particle size of 0.6 μm, VC powder having an average particle size of 0.7 μm, and Cr ₃ C _{2 having} an average particle size of 1.5 μm. Powder, TaC powder having an average particle diameter of 2.0 μm, and NbC powder having an average particle diameter of 2.0 μm are added in the ratio shown in Table 1, methanol as a solvent, and WC particles having an average particle diameter of 0.3 μm as a grinding medium. A ball having a diameter of 5 mm made of a superfine particle cemented carbide as a main component is added, mixed with a vibration mill, dried, then formed into a round bar shape by press molding, and from a temperature lower than the firing temperature by 500 ° C. to 10 ° C./min. The temperature was raised at a rate and fired under the conditions shown in Table 1 to produce a cemented carbide.
[0030]
The obtained cemented carbide was processed into a 2-blade drill shape, and some samples were
Oxygen ion implantation was performed in an air atmosphere at 300 ° C. for 1 hour (temperature increase / decrease rate of 10 ° C./min) or with an energy of 150 KeV and an injection amount of 1 × 10 ¹⁷ ions / cm ² (Sample No. 1). -4, 7).
[0031]
The obtained drill was heat-treated in the atmosphere at a temperature rising rate of 10 ° C./min up to 700 ° C. and held for 1 hour, and the increase in oxidation was calculated from the weight difference before and after the treatment. In calculating the increase in oxidation, the specific surface area of the drill was calculated from the shape of the drawing. Moreover, the Vickers hardness in the inside which divided | segmented the surface of the shank part of the said drill and the shank part into 2 parts was measured. Furthermore, the change in oxygen concentration was measured from the surface of the drill toward the inside by Auger analysis. The results are shown in Table 1.
[0032]
Further, a drilling test of the printed circuit board was performed under the following conditions using the cemented carbide drill shape, and the amount of wear was measured by SEM observation after the test.
[0033]
<Conditions>
Work material: FR4 / 6-layer plate, 1.6 mm thick, 3-ply drill shape: φ0.15 mm undercut type Rotation speed: 120 kr. p. m.
Feeding speed: 2.4m / min Number of drilling holes: 3,000hits
[Table 1]

[0034]
From the results in Table 1, the sample No. which was not subjected to the surface treatment. In Nos. 5 and 6, the increase in oxidation was more than 0.2 mg / m ² , and the wear resistance was lowered. In addition, the sample No. whose firing condition deviates from the predetermined condition. Also in No. 7, the oxidation increase was more than 0.2 mg / m ² and the wear resistance was lowered.
[0035]
On the other hand, according to the present invention, the surface treatment is performed by firing under a predetermined condition using a predetermined raw material to raise the temperature from room temperature to 700 ° C. at a temperature rising rate of 10 ° C./min. Sample No. whose oxidation increase when held for time was 0.2 mg / mm ² or less. Nos. 1 to 4 exhibited excellent wear resistance with an abrasion amount of 50 μm or less.
[0036]
【The invention's effect】
As described in detail above, according to the cemented carbide rotating tool of the present invention, the properties and firing conditions of the raw material powder of the tool are controlled, and the surface of the tool is subjected to a predetermined condition after being processed into a tool shape such as a drill shape. It consists of WC particles with an average particle size of 0.5 μm or less and cobalt by a method such as oxidation treatment or oxygen ion implantation treatment, etc., and a temperature rising rate from the room temperature to 10 ° C./min. When the temperature is raised to 700 ° C. and held for 1 hour, the increase in oxidation is controlled to 0.2 mg / mm ² or less , and the oxygen content on the surface of the cemented carbide is the oxygen content in the interior of the cemented carbide. The cemented carbide rotary tool of the present invention, which is more in number than the cemented carbide, can improve the heat resistance and oxidation resistance of the tool surface without coating, and exhibits excellent performance in wear resistance. Production It is a tool.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a drill which is an example of a cemented carbide rotary tool of the present invention.
[Explanation of symbols]
1 Drill 2 Shank 3 Flute 4 Cutting Edge

Claims

A cemented carbide rotary tool having a shank part, a flute part and a cutting edge part, wherein the cemented carbide is mainly composed of 5 to 15% by mass of cobalt between WC particles having an average particle size of 0.5 μm or less. It consists of a structure bonded in the binder phase, and the oxidation increase when the rotary tool is heated from the room temperature to 700 ° C. at a heating rate of 10 ° C./min and held for 1 hour in the atmosphere is 0.2 mg / mm ^2. hereinafter der is, and cemented carbide rotary tools oxygen content on the surface of the cemented carbide and wherein the larger than the oxygen content in the interior of the cemented carbide.

Cemented carbide rotary tool of claim 1 Symbol placement hardness at the surface of the cemented carbide may be higher than the hardness in the interior of the cemented carbide.

In said cemented carbide, claim wherein V, Cr, that at least one selected from the group of Ta and Nb allowed to contain in a proportion of 0.2 to 3 wt% in total by carbide conversion 1 or 2 The cemented carbide rotary tool described.