JP2001341016A - Twist drill for cutting stainless steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a twist drill for cutting stainless steel with excellent durability by adopting a tool profile of a sharper edge when drilling a comparatively ductile material to be cut such as stainless steel and adopting a shape without applying load to a drill main body in a high speed cutting of 25 m or more. SOLUTION: This coated cemented carbide stainless steel twist drill is constituted of a helix angle: 30 to 45 deg. and a curvature of an edge groove bottom part continuous to a cutting face: 0.4 to 1.0 of a drill diameter and a groove width ratio: 50 to 70% in a cross section diagram perpendicular to the axis.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】本願発明は、延性のある被削材、
例えば、軟鋼、ステンレス鋼等の難削材の穴明け工具に
関し、特に高速度鋼を用いたステンレス鋼の穴あけ工具
にする。BACKGROUND OF THE INVENTION The present invention relates to a ductile work material,
For example, the present invention relates to a drilling tool made of a difficult-to-cut material such as mild steel and stainless steel, and particularly to a drilling tool made of stainless steel using high-speed steel.

【０００２】[0002]

【従来の技術】従来、延性のある被削材、特にステンレ
ス鋼の穴あけ工具には多種多様なドリルが提案されてい
る。ステンレス鋼の穴加工においては、図１に示すよう
な、３０度前後のねじれ角を有する一般的なツイストド
リルでも切削できるが、加工硬化するために削りにく
く、切屑が分断されにくいという特性があり、切屑排出
性（切削動力）や穴精度（拡大代、特に被削材の入口で
の拡大代）が悪くなるという欠点がある。しかも、切削
点の温度を下げ、工具寿命の延長を図り、切削抵抗を下
げるため、切屑排出溝のねじれ角は３０度前後と大きく
設定されている。これを改良したものに特開平９−１１
０１５号公報に記載の穴あけ工具が有る。特開平９−１
１０１５号公報には、先端刃のみ、ねじれ角を大きく
し、切れ味は良くした例である。2. Description of the Related Art Conventionally, various kinds of drills have been proposed for a drilling tool made of a ductile work material, particularly a stainless steel. In the drilling of stainless steel, as shown in Fig. 1, a general twist drill having a twist angle of about 30 degrees can be cut, but it has the property that it is hard to cut due to work hardening, and it is difficult to cut chips. In addition, there is a disadvantage that the chip discharging property (cutting power) and the hole accuracy (enlargement allowance, particularly enlargement allowance at the entrance of the work material) are deteriorated. In addition, the torsion angle of the chip discharge groove is set to be as large as about 30 degrees in order to lower the temperature of the cutting point, prolong the tool life, and lower the cutting resistance. An improved version of this is disclosed in JP-A-9-11.
No. 015 discloses a drilling tool. JP-A-9-1
Japanese Patent Publication No. 1015 is an example in which only the tip blade has a large torsion angle and good sharpness.

【０００３】更に、ステンレス鋼を切削する際のチゼル
部の形状は、前記と同じ理由により、シャープな形状で
あるＸ型シンニングが用いられるが、切削抵抗の軽減や
求心性の向上を目的にＸ型シンニングを改良してその段
差を無くし、スムーズな切屑排出が行えるようにした特
開平１１−２６７９１２号の例が有る。また、先端刃も
凹状として、切り屑処理性を高めている。また、ステン
レス鋼の穴明け加工では、切り屑形態も重要な課題であ
る。切り屑形態は遷移折段型と称される切り屑が最も扱
いやすく排出性も良いが、特に、ステンレス切削で切り
屑の形態に着目した例はほとんどない。[0003] Furthermore, for the same reason as described above, a sharp X-type thinning is used as the shape of the chisel when cutting stainless steel. However, X-type thinning is used for the purpose of reducing cutting resistance and improving centripetality. Japanese Patent Application Laid-Open No. H11-267912 discloses an example in which the mold thinning is improved to eliminate the step, thereby enabling smooth chip discharge. In addition, the tip blade is also concave so as to enhance chip disposal. In drilling stainless steel, the form of chips is also an important issue. Regarding the chip form, a chip called a transition folding step type is the easiest to handle and has good dischargeability, but there is hardly any example focusing on the chip form in stainless steel cutting.

【０００４】[0004]

【発明が解決しようとする課題】ステンレス切削におけ
る切り屑としては、一般の鋼と同様、遷移折段型の切り
屑が得られるが、先端切れ刃の損傷により切り屑の形態
が崩れるため、損傷を防止する検討が多く、適切な形状
となっているか検討されていないのが現状である。その
ため、ステンレス鋼の穴明け加工を進めると、切削初期
は切り屑も分断されるが、穴数が増えるに従い、切り屑
が連続するようになり、しばらく継続すると寿命とな
る。この過程で、工具側の損傷は先端切れ刃の外周端部
に集中して発生する。この切り屑が連続するまえの形態
を長持ちさせるため、特に、すくい面から刃溝形状に着
目した。As cutting chips in stainless steel cutting, transition step type chips can be obtained as in the case of general steel, but the shape of the chips is broken due to damage of the tip cutting edge, so that damage is caused. There are many studies to prevent this, and it has not been studied whether the shape is appropriate. For this reason, when the drilling of stainless steel is advanced, the chips are also separated at the beginning of cutting, but as the number of holes increases, the chips become continuous, and if they continue for a while, the life is extended. In this process, damage on the tool side is concentrated on the outer peripheral end of the leading edge. In order to extend the form before the chips continue, attention was paid particularly to the shape of the blade groove from the rake face.

【０００５】上記課題を解決するために、本願発明で
は、ステンレス鋼の様に比較的延性のある被削材の穴明
け加工に際して、より一層のシャープエツジな刃型を適
用し、２５ｍ以上の高速切削において、ドリル本体に負
荷のかからない形状を採用することにより、耐久性に優
れたステンレス切削用ツイストドリルを提供することを
目的とする。[0005] In order to solve the above-mentioned problems, the present invention employs a sharper edge cutter for drilling a relatively ductile work material such as stainless steel, and has a high speed of 25 m or more. An object of the present invention is to provide a stainless steel twist drill having excellent durability by adopting a shape in which a load is not applied to a drill body in cutting.

【０００６】[0006]

【課題を解決するための手段】本発明によるツイストド
リルは、被覆した超硬質合金製からなるステンレス製ツ
イストドリルにおいて、ねじれ角を３０〜４５度とし、
軸直角断面図におけるすくい面とに連なる刃溝底部の曲
率をドリル刃径の０．４〜１．０倍、溝幅比を５０〜７
０％、としたことを特徴とするステンレス切削用ツイス
トドリルである。The twist drill according to the present invention is a stainless steel twist drill made of a coated super-hard alloy and having a twist angle of 30 to 45 degrees.
The curvature of the bottom of the blade groove connected to the rake face in the cross section perpendicular to the axis is 0.4 to 1.0 times the drill blade diameter, and the groove width ratio is 50 to 7
It is a stainless steel twist drill characterized by being 0%.

【０００７】先ず、刃溝底部の曲率半径は一般的にドリ
ル外径の０．１５〜０．３５倍程度が用いられている。
この曲率半径は小さいほど切り屑がカールし、大きいほ
どカール径が大きく、切り屑としては分断されにくくな
る。そのため、強ねじれとの相乗効果により曲率半径を
０．４０〜１．０倍として、切り屑を分断させるように
すると、０．４０倍以上においても遷移折段型の切り屑
が得られ、且つ、大きな曲率でカールさせるため、ドリ
ルにかかる負荷が軽減され、分断された切り屑が長く継
続するようになる。更に、ツイストドリルの軸方向すく
い角であるねじれ角は、大きく採れば切れ味をよくでき
るが、その反面、強度が低下する。ねじれ角が３０度未
満だと切削抵抗が大きく拡大代が大きくなり、穴精度が
低下し、ねじれ角が４５度を超えると、切り屑排出の妨
げになるため３０度〜４５度の範囲とした。First, the radius of curvature at the bottom of the blade groove is generally about 0.15 to 0.35 times the outer diameter of the drill.
The smaller the radius of curvature is, the more the chips are curled, and the larger the radius of curvature is, the larger the curl diameter is, and it is difficult to separate the chips as chips. For this reason, when the radius of curvature is set to 0.40 to 1.0 times by a synergistic effect with strong torsion to break the chips, even at 0.40 times or more, transition step-shaped chips are obtained, and In addition, since the curl is performed with a large curvature, the load applied to the drill is reduced, and the cut chips continue for a long time. Further, the twist angle, which is the rake angle in the axial direction of the twist drill, can be made sharper by taking a large value, but the strength is reduced. If the torsion angle is less than 30 degrees, the cutting resistance is large and the margin for enlargement is large, the hole accuracy is reduced, and if the torsion angle exceeds 45 degrees, the chip discharge is hindered, so the range was 30 to 45 degrees. .

【０００８】次に、曲率半径の大きさを０．４〜１．０
倍としたのは、ドリルの内壁を用いてカールさせるので
はなく、被切削面である被削材を内壁と同様に用いて切
り屑処理を行うことを前提としたもので、そのため大き
な刃溝を使って、切り屑処理ができ、０．４０倍未満で
は、切り屑処理にかかる負荷が大きく寿命が短くなり、
１．０倍を超えると切り屑の排出する方向が制御しずら
くなるため０．４０〜１．０倍の範囲とした。Next, the radius of curvature is set to 0.4 to 1.0.
The reason for double is that it is assumed that instead of curling using the inner wall of the drill, the chip processing is performed using the work material that is the surface to be cut in the same way as the inner wall, and therefore a large blade groove Can be used for chip processing. If it is less than 0.40 times, the load on chip processing is large and the life is shortened.
If it exceeds 1.0 times, it becomes difficult to control the direction in which chips are discharged, so the range was 0.40 to 1.0 times.

【０００９】溝幅比は（断面図における、切屑排出溝の
溝幅を工具外周長さで除し、百分率で表す。）５０〜７
０％とした。ここで、溝幅比５０％未満では、強ねじれ
と相まって溝幅が狭くなり切屑詰まりを引き起こすこと
になり、７０％を超えると、溝幅が広い分、ランド部が
薄くなりすぎ不安定となるため、溝幅比は５０〜７０％
の範囲とした。更に、大きな溝幅比は、溝のヒール部の
形状により調整することもできる。ヒール部の先端を円
弧状に形成することにより、溝幅比を大きくとり、前述
のような切り屑の内壁との接触を少なめることができ
る。ドリルの芯厚は、０．１０Ｄ〜０．３０Ｄの範囲と
した。０．１０Ｄ未満では工具剛性が不足して、穴加工
時の被削材入口の拡大代の精度が悪くなり、０．３０Ｄ
を越えると溝自体のスペースを狭くなりすぎるため、壁
との接触が増え、切削抵抗が大きくなると共に切屑排出
性が悪くなり、切屑詰まりを起し易くなるめである。The groove width ratio is 50 to 7 (in the sectional view, the groove width of the chip discharge groove is divided by the tool outer peripheral length and expressed as a percentage).
0%. Here, if the groove width ratio is less than 50%, the groove width becomes narrow in combination with strong torsion, causing chip clogging. If it exceeds 70%, the land portion becomes too thin and unstable due to the wide groove width. Therefore, the groove width ratio is 50-70%
Range. Furthermore, a large groove width ratio can be adjusted by the shape of the heel portion of the groove. By forming the tip of the heel portion in an arc shape, the groove width ratio can be increased and the contact of the chip with the inner wall as described above can be reduced. The core thickness of the drill was in the range of 0.10D to 0.30D. If it is less than 0.10D, the rigidity of the tool is insufficient, and the precision of the enlargement allowance of the work material entrance at the time of drilling becomes poor.
Exceeding the limit causes the space of the groove itself to be too narrow, increasing the contact with the wall, increasing the cutting resistance, deteriorating the chip discharge property, and easily causing chip clogging.

【００１０】本発明のツイストドリルは、高速度鋼を用
いて説明してきたが、より好ましくは粉末ハイスのほう
が良い。通常の溶製ハイスに比して炭化物の粒度が細か
いため、ねじれ角が強い本発明のドリルには好都合であ
る。また、溶製ハイスでもねじれを生かし、ホーニング
の大小により適用することができる。更に、ステンレス
鋼等の延性に富む材料には被覆が必須なものであり、本
発明においても公知な被膜、例えば、ＴｉＮやＴｉＡｌ
Ｎ等の物理蒸着法を用いて行われる膜が適している。特
に、切り屑の溶着や圧着を生じやすい先端刃のチゼル近
傍には、潤滑性に富むＣｒ窒化物、ＤＬＣ及び２硫化モ
リブデン等の固体潤滑剤等の被膜も有効である。Although the twist drill of the present invention has been described using high-speed steel, powdered high-speed steel is more preferred. Since the carbide has a finer grain size as compared with the ordinary ingot high-speed steel, it is advantageous for the drill of the present invention having a large torsion angle. In addition, it can be applied to the size of the honing by making use of the torsion even in the melted high speed steel. Further, a coating is indispensable for a highly ductile material such as stainless steel, and a coating known in the present invention, for example, TiN or TiAl
A film formed using a physical vapor deposition method such as N is suitable. In particular, a coating of a solid lubricant such as Cr nitride, DLC, and molybdenum disulfide, which are rich in lubricity, is effective in the vicinity of the chisel of the tip blade where chip welding and pressure bonding are likely to occur.

【００１１】３０〜４５度のねじれ角を採用することに
より、切れ味がよく高い穴精度が得られる。更に、穴精
度をより高めるため、シンニング形状を、より求心性の
高い形状とする事が好ましい。例えば、図５の様に、シ
ンニング角度を大きく採り、図４に示すように、軸方向
のすくい角を−５度以上の負角とし、刃溝まで十分な距
離を、滑らかに結ぶように設けることにより、切り屑詰
まりを防止することができる。以下、実施例に基づき、
本発明を具体的に説明する。By using a twist angle of 30 to 45 degrees, sharpness and high hole accuracy can be obtained. Further, in order to further improve the hole accuracy, it is preferable to make the thinning shape a shape with higher centripetality. For example, as shown in FIG. 5, a large thinning angle is adopted, and as shown in FIG. 4, the rake angle in the axial direction is set to a negative angle of -5 degrees or more, and a sufficient distance to the blade groove is provided so as to be smoothly connected. This can prevent chip clogging. Hereinafter, based on the examples,
The present invention will be specifically described.

【００１２】[0012]

【実施例】図３は、本発明の実施例によるドリルの正面
図、図４は、図３に示すドリルの９０度回転させた上面
図、図５は、図３の先端視である。本実施例によるツイ
ストドリル１は、高速度鋼（粉末ハイス）製、刃径６ｍ
ｍ、２枚刃、ねじれ角２は４０度で、ＴｉＡｌＮを被覆
した。図５に示すように、軸線Ｏの周りの先端切れ刃３
が設けられている。また、図６に示す軸直角断面図にお
ける曲率半径Ｒはドリル外径の６０％の曲率で結んでい
る。先端切れ刃３のシンニングはＸ型とした。FIG. 3 is a front view of a drill according to an embodiment of the present invention, FIG. 4 is a top view of the drill shown in FIG. 3 rotated by 90 degrees, and FIG. 5 is a front view of FIG. The twist drill 1 according to the present embodiment is made of high-speed steel (powder high-speed steel) and has a blade diameter of 6 m.
m, two blades, helix angle 2 was 40 degrees, and TiAlN was coated. As shown in FIG. 5, the tip cutting edge 3 around the axis O
Is provided. In addition, the radius of curvature R in the cross section perpendicular to the axis shown in FIG. 6 is connected at a curvature of 60% of the outer diameter of the drill. The thinning of the tip cutting edge 3 was X-shaped.

【００１３】次に、本発明によるドリル、図１に示すね
じれ角３０度の従来例１、図２に示す従来例２とについ
て、各種被削材の切削性能に関する試験を行った。尚、
従来ドリルは、同一径でＴｉＡｌＮ被覆を行った試料を
用いた。切削試験にあたっては、被削材として、ＳＵＳ
３０４を用い、穴加工深さ３Ｄとし、切削油剤は水溶性
のエマルジョンタイプを用い、切削速度２５ｍ／ｍｉ
ｎ、送り量０．１５ｍｍ／ｒｅｖで行い、切れ刃のチッ
ピング状態、摩耗量・摩耗状態を一定数ごとに確認し、
穴あけを継続した。また、１穴目の加工で拡大代を測定
し、更に、定常摩耗域で測定した。先ず、１００穴加工
したとき、本発明例のは、切り屑形態としては図７に示
すように、処理性の良いカールされた切り屑が得られ、
拡大代は、入り口、中央とも０．０２ｍｍと良好であ
り、チッピングもなく正常な摩耗を示したが、従来例１
では切削速度が速すぎるため、１穴も加工できずに寿命
となった。従来例２のドリルも、外周側部にチッピング
を生じた。そのため拡大代は、０．０９ｍｍと大きくな
った。Next, the drill according to the present invention, a conventional example 1 having a twist angle of 30 degrees shown in FIG. 1, and a conventional example 2 shown in FIG. 2 were subjected to tests on cutting performance of various work materials. still,
Conventionally, a drill having the same diameter and coated with TiAlN was used. In the cutting test, use SUS
Using 304, the drilling depth is 3D, the cutting fluid is a water-soluble emulsion type, and the cutting speed is 25 m / mi.
n, feed rate 0.15mm / rev, check the chipping state of the cutting edge, the amount of wear and the state of wear every fixed number,
Drilling was continued. In addition, the allowance for enlargement was measured in the processing of the first hole, and further, it was measured in the steady wear region. First, when 100 holes are machined, according to the example of the present invention, as the chip form, as shown in FIG.
The enlargement allowance was as good as 0.02 mm at the entrance and at the center, showing normal wear without chipping.
In this case, the cutting speed was too high, so that one hole could not be machined, and the life was shortened. The drill of Conventional Example 2 also had chipping on the outer peripheral side. Therefore, the enlargement allowance was as large as 0.09 mm.

【００１４】更に、試験を継続し、２００穴、４００
穴、６００穴、８００穴、１０００穴、１５００穴と続
けたが、切れ刃に徐々に溶着がみられるようになり、そ
の脱落等により逃げ面最大摩耗量が０．２ｍｍ程度とな
ったため、切削試験を止めた。１５００穴加工での拡大
代も０．０３ｍｍと良好であった。また、切り屑の形態
もほとんど変化が無く、１５００穴加工時の切り屑を図
８に示すが、図７の切り屑と大差なく、切り屑がドリル
本体に巻き付いてトラブルようなこともなく、分断され
た切り屑が得られた。Further, the test was continued, and 200 holes, 400 holes
Holes, 600 holes, 800 holes, 1000 holes, and 1500 holes were continued. However, welding was gradually observed on the cutting edge, and the maximum wear amount of the flank became about 0.2 mm due to the falling off. The test was stopped. The enlargement allowance in the processing of 1500 holes was as good as 0.03 mm. Also, there is almost no change in the form of the chip, and the chip at the time of 1500 hole processing is shown in FIG. 8, but there is no much difference from the chip in FIG. A fragmented chip was obtained.

【００１５】次に、曲率半径のＲの大きさをドリル外径
の２０％、３０％、４０％、５０％、６０％、８０％、
１００％の試料を製作し、同様に切削試験を行った。そ
の結果、１００穴目までで、切り屑が連なるようになっ
たのは２０％の曲率半径のみで他は良好で、正常な摩耗
を示した。更に試験を継続し、更に５００穴まで試験を
継続すると、３０％で切り屑形態が変化し、連続する切
り屑が排出されようになった。他の試料は正常な摩耗を
示した。Next, the magnitude of the radius of curvature R is set to 20%, 30%, 40%, 50%, 60%, 80%,
A 100% sample was manufactured and a cutting test was performed in the same manner. As a result, up to the 100th hole, only 20% of the radius of curvature led to continuous cutting chips, and the others were good and showed normal wear. When the test was further continued and the test was further continued up to 500 holes, the chip morphology changed at 30%, and continuous chips began to be discharged. Other samples showed normal wear.

【００１６】尚、上述の実施例においては高速度鋼を用
いて説明したが、これに限定されることなく、超硬ソリ
ッドタイプやスローアウェイタイプのドリル等であって
も、同様に本発明を適用できる。Although the above embodiment has been described using high-speed steel, the present invention is not limited to this, and the present invention is similarly applicable to a solid carbide type or a throw-away type drill. Applicable.

【００１７】[0017]

【発明の効果】上記のように、本発明に係る穴明け工具
を用いることにより、切削抵抗が小さく、穴精度（拡大
代）の良い加工が行え、また、切り屑がからみつき能率
を落とすようなトラブルが無く、優れた工具寿命を発揮
する。As described above, by using the drilling tool according to the present invention, it is possible to perform machining with small cutting resistance and high hole accuracy (enlargement allowance), and also to reduce the efficiency with which chips are entangled and reduce efficiency. Demonstrate excellent tool life without any trouble.

【図面の簡単な説明】[Brief description of the drawings]

【図１】図１は、従来例のツイストドリルの正面図を示
す。FIG. 1 is a front view of a conventional twist drill.

【図２】図２は、他の従来例のツイストドリルの正面図
を示す。FIG. 2 is a front view of another conventional twist drill.

【図３】図３は、本発明例の実施例のドリルの正面図を
示す。FIG. 3 shows a front view of a drill according to an embodiment of the present invention.

【図４】図４は、図３の要部拡大図を示す。FIG. 4 is an enlarged view of a main part of FIG. 3;

【図５】図５は、図３の先端視を示す。FIG. 5 shows a front view of FIG. 3;

【図６】図６は、図３のＡ−Ａ線の軸直角断面図を示
す。FIG. 6 is a sectional view taken along the line AA of FIG. 3 at right angles to the axis;

【図７】図７は、本発明例の１００穴加工時の切り屑を
示す。FIG. 7 shows chips when machining 100 holes according to the example of the present invention.

【図８】図８は、本発明例の１５００穴加工時の切り屑
を示す。FIG. 8 shows cutting chips at the time of machining a 1500 hole according to the present invention.

【符号の説明】[Explanation of symbols]

１ ツイストドリル ２ ねじれ角 ３ 先端切れ刃 Ｒ 曲率半径 DESCRIPTION OF SYMBOLS 1 Twist drill 2 Helix angle 3 Tip cutting edge R Curvature radius

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】被覆した超硬質合金製からなるステンレス
製ツイストドリルにおいて、ねじれ角を３０〜４５度と
し、軸直角断面図におけるすくい面に連なる刃溝底部の
曲率をドリル刃径の０．４０〜１．０倍、溝幅比を５０
〜７０％、としたことを特徴とするステンレス切削用ツ
イストドリル。1. A stainless steel twist drill made of a coated super-hard alloy, wherein the torsion angle is 30 to 45 degrees, and the curvature of the bottom of the blade groove connected to the rake face in the cross section perpendicular to the axis is 0.40 of the drill blade diameter. ~ 1.0 times, groove width ratio 50
A twist drill for stainless steel cutting, characterized in that: 【請求項２】請求項１記載のステンレス切削用ツイスト
ドリルにおいて、該被覆がＴｉＮ、ＴｉＡｌＮ等の硬質
皮膜からなることを特徴とするステンレス切削用ツイス
トドリル。2. The twist drill for stainless steel cutting according to claim 1, wherein said coating is made of a hard film such as TiN or TiAlN. 【請求項３】請求項１記載のステンレス切削用ツイスト
ドリルにおいて、該超硬質合金が高速度鋼からなること
を特徴とするステンレス切削用ツイストドリル。3. The twist drill for stainless steel cutting according to claim 1, wherein said super-hard alloy is made of high-speed steel.