JP6011849B2

JP6011849B2 - Step drill

Info

Publication number: JP6011849B2
Application number: JP2012199268A
Authority: JP
Inventors: 一範北森
Original assignee: Nachi Fujikoshi Corp
Current assignee: Nachi Fujikoshi Corp
Priority date: 2012-09-11
Filing date: 2012-09-11
Publication date: 2016-10-19
Anticipated expiration: 2032-09-11
Also published as: JP2014054680A

Description

本発明は、繊維強化プラスチックと金属材料からなる接合材料を穴加工する際に用いられる段付きドリルに関する。 The present invention relates to a step drill used for drilling a bonding material made of a fiber reinforced plastic and a metal material.

一般的に、ドリルを用いて穴加工する時、被削材が繊維強化プラスチックの場合には、被削材が切れ刃などに引っ張られた状態になると、切削抵抗が大きくなり、加工穴の出口コーナや穴面に、繊維方向のバリや層間剥離（デラミネーション）が発生する。そのため、被削材が自動車分野や航空機分野などで部品用の素材として使用される繊維強化プラスチックの場合には、穴加工を施す際に高品位な加工穴が高精度に要求されることから、被削材にバリや層間剥離が発生するという問題がある場合においては、一つの目安として、穴加工時の切削抵抗を軽減する必要がある。また、被削材が繊維強化プラスチックと金属材料からなる接合材料の場合には、繊維強化プラスチックを加工する場合の切削抵抗を軽減させる必要があると同時に、金属材料を加工する場合に発生しやすい、ドリル刃先の摩耗や欠けを軽減させることも求められる。 Generally, when drilling with a drill, if the work material is fiber reinforced plastic, if the work material is pulled by a cutting edge, the cutting resistance increases and the exit of the work hole Burrs and delamination in the fiber direction occur at the corners and hole surfaces. Therefore, when the work material is fiber reinforced plastic used as a material for parts in the automotive field, aircraft field, etc., high-quality processed holes are required with high accuracy when drilling, When there is a problem that burrs and delamination occur in the work material, it is necessary to reduce the cutting resistance during drilling as a guide. Also, when the work material is a joining material made of fiber reinforced plastic and metal material, it is necessary to reduce cutting resistance when processing fiber reinforced plastic, and at the same time, it tends to occur when processing metal material It is also required to reduce wear and chipping of the drill blade tip.

例えば、プラスチック系の複合材からなる被削材を穴加工する場合、通常の金属加工用ドリルを用いると被削材の加工穴の出口コーナや穴面にバリやケバが発生する。そこで、特許文献１では、プラスチック系の内装壁面建材や天井建材などの複合材からなる被削材を穴加工する場合に用いるドリルが開示されている。このドリルは、先端の外周側に数ミリメートルほど突起している切れ刃（以下、突起刃という）を有し、外周コーナから軸心に至るまで平刃を有し、突起刃と平刃の間に逃げ部を形成している。このドリルを用いることで、円形状の輪郭を描くように被削材を切る穴加工を施すことでき、被削材に発生する負荷が抑えられ、バリやケバの発生が少ない穴加工をすることができる。さらに、突起刃のすくい面にチャンファを設けることで、突起刃に発生する切削抵抗が抑えられ、欠けの発生を防止することができる。 For example, when drilling a workpiece made of a plastic composite material, if a normal metal drill is used, burrs and burrs are generated at the exit corner and hole surface of the machining hole of the workpiece. Therefore, Patent Document 1 discloses a drill used for drilling a workpiece made of a composite material such as a plastic interior wall surface building material or a ceiling building material. This drill has a cutting edge projecting about several millimeters on the outer peripheral side of the tip (hereinafter referred to as a protruding blade), a flat blade from the outer corner to the axis, and between the protruding blade and the flat blade. The escape part is formed in. By using this drill, it is possible to perform drilling to cut the work material so as to draw a circular outline, the load generated on the work material can be suppressed, and drilling with less burr and fluffing can be performed Can do. Furthermore, by providing a chamfer on the rake face of the protruding blade, the cutting resistance generated in the protruding blade can be suppressed and the occurrence of chipping can be prevented.

また、被削材がＣＦＲＰ（炭素繊維強化プラスチック）に代表される繊維強化プラスチックの場合には、例えば、特許文献２では、小径部と大径部を有する段付きドリルが開示されている。この段付きドリルは、大径部の仕上げ刃がなす角度（以下、ステップ角と
いう）を９０°〜１６０°の範囲に設定し、ねじれ角を４０°以上に設定し、ドリル本体の表面にダイヤモンド被覆を施している。この段付きドリルを用いることで、バリが発生しない高品位な加工穴が高精度に形成され、さらに、ドリルの寿命も飛躍的に向上させることができる。 Further, when the work material is a fiber reinforced plastic represented by CFRP (carbon fiber reinforced plastic), for example, Patent Document 2 discloses a step drill having a small diameter portion and a large diameter portion. In this step drill, the angle (hereinafter referred to as the step angle) formed by the finishing blade of the large diameter part is set in the range of 90 ° to 160 °, the helix angle is set to 40 ° or more, and the surface of the drill body is diamond. A coating is applied. By using this stepped drill, a high-quality processed hole that does not generate burrs is formed with high accuracy, and the life of the drill can be dramatically improved.

さらに、被削材が繊維強化プラスチックと金属材料からなる接合材料の場合には、例えば、特許文献３では、金属加工用ドリルと同様な先端形状の小径部に切れ刃を有し、連続してステップ角を２０°〜３０°の範囲に設定している。さらにステップ角に連続して、フラット状の大径部に仕上げ刃を有し、小径部の切れ刃と大径部の仕上げ刃の最大径に径差を設け、ねじれ角を２０°〜３０°に設定しているドリルが開示されている。このドリルを用いることで、繊維強化プラスチックに施される加工穴の出口コーナや穴面に与えるダメージを実質的に問題がない程度に十分小さくし、層間剥離の発生確率を下げることができる。そのため、繊維強化プラスチックに対しては、高品位な加工穴が高精度に形成される。 Furthermore, in the case where the work material is a joining material made of fiber reinforced plastic and a metal material, for example, in Patent Document 3, a cutting edge is provided in a small-diameter portion having a tip shape similar to that of a drill for metal processing. The step angle is set in the range of 20 ° to 30 °. Furthermore, following the step angle, there is a finishing blade on the flat large diameter part, a difference in diameter is provided between the cutting edge of the small diameter part and the finishing blade of the large diameter part, and the twist angle is 20 ° to 30 °. A drill set in is disclosed. By using this drill, the damage given to the exit corner and hole surface of the processed hole made in the fiber reinforced plastic can be made sufficiently small to cause substantially no problem, and the occurrence probability of delamination can be lowered. Therefore, high-quality processed holes are formed with high accuracy for fiber-reinforced plastics.

特許第３０９８４６５号公報Japanese Patent No. 3098465 特開２００８−８３６号公報JP 2008-836 A 特公平７−４７２４３号公報Japanese Patent Publication No. 7-47243

しかし、特許文献１に開示されているドリルは、被削材が繊維強化プラスチックと金属材料からなる場合には、金属材料を加工する際に、ドリル先端の突起刃に応力が集中し、摩耗や欠けが発生し、穴加工が困難であるという問題があった。 However, in the drill disclosed in Patent Document 1, when the work material is made of a fiber reinforced plastic and a metal material, when the metal material is processed, stress concentrates on the protruding blade at the tip of the drill, and wear or There was a problem that chipping occurred and drilling was difficult.

また、特許文献２に開示されているドリルは、被削材が繊維強化プラスチックと金属材料からなる接合材料である場合において、繊維強化プラスチック側から穴加工を施すと、繊維強化プラスチックに対しては高品位な加工穴が高精度に形成されるが、金属材料に対しては穴加工時に、小径部の切れ刃や大径部の仕上げ刃に大きな切削抵抗がかかり、早期に刃先に欠けが発生する。刃先に欠けがあるドリルで、継続して金属材料へ穴加工を施すと、加工穴の出口コーナや穴面にバリが発生して、金属材料の加工穴出口の品質や精度を確保することが困難になるという問題があった。 Further, in the drill disclosed in Patent Document 2, when the work material is a joining material made of a fiber reinforced plastic and a metal material, when drilling is performed from the fiber reinforced plastic side, High-quality drilled holes are formed with high accuracy, but when cutting holes in metal materials, a large cutting resistance is applied to the small-diameter cutting edge and large-diameter finishing blade, resulting in early chipping of the cutting edge. To do. If drilling is continuously performed on a metal material with a drill with a chip on the cutting edge, burrs will be generated at the exit corner and hole surface of the processed hole, ensuring the quality and accuracy of the processed material hole exit. There was a problem that became difficult.

さらに、特許文献３に開示されているドリルは、小径部先端の刃先形状は金属加工用に特化しているが、ステップ角から大径部に至る仕上げ刃の刃先形状は金属加工用に適したものになっていない。そのため、特許文献２に開示されている段付きドリルと同様に、繊維強化プラスチックに対しては高品位な加工穴が高精度に形成されるが、金属材料の加工穴出口の品質や精度を確保することが困難になるという問題があった。 Furthermore, the drill disclosed in Patent Document 3 specializes in cutting edge shape at the tip of the small diameter portion for metal processing, but the cutting edge shape of the finishing blade from the step angle to the large diameter portion is suitable for metal processing. It is not a thing. For this reason, as with the step drill disclosed in Patent Document 2, high-quality processed holes are formed with high precision for fiber-reinforced plastics, but the quality and accuracy of the metal material processed hole exit are ensured. There was a problem that it was difficult to do.

そこで、本発明においては前述した問題点に鑑みて、被削材が繊維強化プラスチックと金属材料からなる接合材料であり、繊維強化プラスチック側から穴加工を施す際に、金属材料の加工穴出口におけるバリ高さを軽減することができ、かつ、高品位な加工穴を高精度に施すことができる段付きドリルを提供することを課題とする。 Therefore, in the present invention, in view of the above-described problems, the work material is a joining material made of a fiber reinforced plastic and a metal material, and when the hole is machined from the fiber reinforced plastic side, at the machining hole outlet of the metal material. It is an object of the present invention to provide a step drill capable of reducing the burr height and capable of providing a high-quality processed hole with high accuracy.

前述した課題を解決するために、本発明においては、被削材に最初に穴加工を施す切れ刃のすくい面にチャンファが設けられた小径部と、小径部のねじれ角よりも大きなねじれ角を有して仕上げ刃を備えた大径部と、を有する段付きドリルであって、大径部のステップ角を１８０°として、かつ大径部のねじれ角を３０°以下として、段付きドリルの外周コーナを通り軸心Ｏに平行な直線Ｐと、外周コーナを通りチャンファと小径部のマージンとで形成される稜線を含む直線Ｑとのなす角度δが、５°以上１５°以下である段付きドリルとした。本発明に係る段付きドリルを用いることで、被削材に穴加工を施す場合に、大径部の仕上げ刃による取り代が減少するため、過剰な切削抵抗が発生せず、刃先への負荷が軽減される。 In order to solve the above-described problems, in the present invention, a small diameter portion in which a chamfer is provided on a rake face of a cutting edge that is first subjected to hole machining in a work material, and a twist angle larger than the twist angle of the small diameter portion. A stepped drill having a large-diameter portion having a finishing blade and a step angle of the large-diameter portion of 180 ° and a twist angle of the large-diameter portion of 30 ° or less. A step in which an angle δ formed by a straight line P passing through the outer peripheral corner and parallel to the axis O and a straight line Q including a ridge line formed by the chamfer and the margin of the small diameter portion through the outer peripheral corner is 5 ° or more and 15 ° or less. A drill was attached. By using the step drill according to the present invention, when machining the work material, the machining allowance by the finishing blade of the large diameter portion is reduced, so that excessive cutting resistance does not occur and the load on the cutting edge Is reduced.

本発明に係る段付きドリルは、被削材に最初に穴加工を施す切れ刃のすくい面にチャンファが設けられた小径部と、小径部のねじれ角よりも大きなねじれ角を有して仕上げ刃を備えた大径部と、を有する段付きドリルであって、大径部のステップ角を１８０°、大径部のねじれ角を３０°以下として、段付きドリルの外周コーナを通り軸心Ｏに平行な直線Ｐと、外周コーナを通りチャンファと小径部のマージンとで形成される稜線を含む直線Ｑとのなす角度δが、５°以上１５°以下である段付きドリルとしている。そうすることで、大径部の仕上げ刃による取り代が減少するため、過剰な切削抵抗が発生せず、刃先への負荷が軽減されることにより、被削材が繊維強化プラスチックと金属材料からなる接合材料である場合において、繊維強化プラスチック側から穴加工を施す場合に、金属材料の加工穴出口におけるバリ高さを軽減し、高品位な加工穴が高精度に形成されるという効果を奏する。 The step drill according to the present invention has a small-diameter portion in which a chamfer is provided on a rake face of a cutting edge for first drilling a work material, and a finishing blade having a twist angle larger than the twist angle of the small-diameter portion. A step drill having a large diameter portion, wherein the step angle of the large diameter portion is 180 ° and the torsion angle of the large diameter portion is 30 ° or less, passing through the outer periphery corner of the step drill, the axis O And a straight line Q including a ridge line formed by a chamfer and a margin of a small diameter portion through a peripheral corner and an angle δ between 5 ° and 15 °. By doing so, the machining allowance with the finishing blade of the large diameter part is reduced, so that excessive cutting resistance does not occur and the load on the cutting edge is reduced, so that the work material is made of fiber reinforced plastic and metal material. When the hole is drilled from the fiber-reinforced plastic side, the burr height at the hole outlet of the metal material is reduced, and a high-quality hole is formed with high accuracy. .

本発明の実施の形態の一例である段付きドリル１の正面図である。It is a front view of the step drill 1 which is an example of embodiment of this invention. 図１の段付きドリル１の左側面図である。It is a left view of the step drill 1 of FIG. 図２のＡ方向から見た段付きドリル１先端の斜視図である。FIG. 3 is a perspective view of the tip of a step drill 1 viewed from the direction A in FIG. 2. 図２の段付きドリル１先端の底面図である。FIG. 3 is a bottom view of the tip of the step drill 1 of FIG. 2. 切削試験を行った段付きドリルに発生した切削抵抗（スラスト）の測定結果である。It is a measurement result of the cutting resistance (thrust) which generate | occur | produced in the step drill which performed the cutting test. 切削試験を行った段付きドリルに発生した切削抵抗（トルク）の測定結果である。It is a measurement result of the cutting resistance (torque) which generate | occur | produced in the stepped drill which performed the cutting test.

本発明の実施の形態について、本発明に係る段付きドリル１を二つのねじれ溝８、８を有するツイストドリルに適用した場合について図面を参照して説明する。図１は本発明の実施の形態の一例である段付きドリル１の正面図、図２は図１の段付きドリル１の左側面図、図３は図２のＡ方向から見た段付きドリル１先端の斜視図、図４は図２の段付きドリル１先端の底面図である。 Embodiments of the present invention will be described with reference to the drawings in the case where the step drill 1 according to the present invention is applied to a twist drill having two twisted grooves 8 and 8. 1 is a front view of a step drill 1 as an example of an embodiment of the present invention, FIG. 2 is a left side view of the step drill 1 of FIG. 1, and FIG. 3 is a step drill viewed from the direction A of FIG. FIG. 4 is a bottom view of the tip of the step drill 1 of FIG.

段付きドリル１は、図１に示すように、小径部２０と大径部２１から構成され、小径部２０の直径Ｄ１は大径部２１の直径Ｄ２よりも小さくなるように設定されている。まず、小径部２０が最初に被削材に下穴をあけることで、大径部２１の仕上げ刃２２による取り代が減少し、大径部２１の仕上げ刃２２の切削抵抗が軽減され、穴加工時に発生しやすいチッピングや摩耗を防ぐ効果によりバリ高さが抑制される。 As shown in FIG. 1, the step drill 1 includes a small diameter portion 20 and a large diameter portion 21, and the diameter D <b> 1 of the small diameter portion 20 is set to be smaller than the diameter D <b> 2 of the large diameter portion 21. First, the small-diameter portion 20 first drills a pilot hole in the work material, so that the machining allowance by the finishing blade 22 of the large-diameter portion 21 is reduced, and the cutting resistance of the finishing blade 22 of the large-diameter portion 21 is reduced. The burr height is suppressed by the effect of preventing chipping and wear that are likely to occur during processing.

大径部２１と小径部２０の直径差（Ｄ２−Ｄ１）については、０．２ｍｍ以上１．０ｍｍ以下の範囲とすることが好ましい。大径部２１と小径部２０の直径差（Ｄ２−Ｄ１）の範囲を限定する理由は、０．２ｍｍ未満では大径部２１と小径部２０の直径差（Ｄ２−Ｄ１）が小さいため、大径部２１の仕上げ刃２２による取り代が少なくなり、先に小径部２０があけた下穴に発生したバリを、大径部２１の仕上げ刃２２で十分に除去することができないからである。また、１．０ｍｍを超えると、大径部２１の仕上げ刃２２による取り代が大きくなるため、大径部２１の仕上げ刃２２に過剰な切削抵抗がかかり、大径部２１の仕上げ刃２２の刃先にチッピング（小さな欠け）が発生するからである。そして、大径部２１の仕上げ刃２２の刃先にチッピングが発生した状態で、そのまま穴加工を継続すると、さらに切削抵抗が大きくなり、小径部２０の切れ刃５および大径部２１の仕上げ刃２２の刃先のチッピングの発生を助長して、チッピングが多数発生するため、大径部２１の仕上げ刃２２で加工された加工穴出口のバリ高さが大きくなるだけでなく、段付きドリルが折損することもありうる。 About the diameter difference (D2-D1) of the large diameter part 21 and the small diameter part 20, it is preferable to set it as the range of 0.2 mm or more and 1.0 mm or less. The reason for limiting the range of the diameter difference (D2-D1) between the large diameter portion 21 and the small diameter portion 20 is that the diameter difference (D2-D1) between the large diameter portion 21 and the small diameter portion 20 is small if less than 0.2 mm. This is because the machining allowance of the diameter portion 21 by the finishing blade 22 is reduced, and the burr generated in the pilot hole previously formed by the small diameter portion 20 cannot be sufficiently removed by the finishing blade 22 of the large diameter portion 21. Moreover, since the allowance with the finishing blade 22 of the large diameter part 21 will become large if it exceeds 1.0 mm, excessive cutting resistance will be applied to the finishing blade 22 of the large diameter part 21, and the finishing blade 22 of the large diameter part 21 will be applied. This is because chipping (small chipping) occurs at the cutting edge. Then, if the hole machining is continued as it is in the state where the tip of the finishing blade 22 of the large diameter portion 21 is chipped, the cutting resistance is further increased, and the cutting edge 5 of the small diameter portion 20 and the finishing blade 22 of the large diameter portion 21 are increased. Since the chipping of the cutting edge is promoted and many chippings occur, not only the burr height at the exit of the machining hole processed by the finishing blade 22 of the large diameter portion 21 is increased, but also the stepped drill is broken. It is also possible.

小径部２０のねじれ角α１ならびに大径部２１のねじれ角α２については、図１に示すように、ねじれ溝８の延長線Ｈと軸心Ｏがなす角度であり、切り屑の排出特性の点から、それぞれ１５°以上３０°以下、かつα１＜α２の範囲とすることが好ましい。小径部２０のねじれ角α１と大径部２１のねじれ角α２、それぞれの範囲が限定される理由は、ねじれ角が１５°未満では、切削加工時に発生する切り屑の排出特性が足りないことから、加工穴に切り屑が詰まると、段付きドリル１に大きな負荷が発生することで、摩耗が進行したり、折損したりするためである。また、３０°を超えると、大径部２１の仕上げ刃２２の刃先の厚みが小さくなり、大径部２１の仕上げ刃２２の刃先の耐久性が低下し、金属材料に切り込む場合に、大径部２１の仕上げ刃２２の刃先に発生する衝撃が大きくなり、大径部２１の仕上げ刃２２の刃先にチッピングが発生するためである。 The torsion angle α1 of the small diameter portion 20 and the torsion angle α2 of the large diameter portion 21 are angles formed by the extension line H of the torsion groove 8 and the axis O, as shown in FIG. Therefore, it is preferable that the angle is in the range of 15 ° to 30 ° and α1 <α2. The reason why the ranges of the twist angle α1 of the small diameter portion 20 and the twist angle α2 of the large diameter portion 21 are limited is that if the twist angle is less than 15 °, the discharge characteristics of chips generated during cutting are insufficient. This is because, when the processing hole is clogged with chips, a large load is generated on the stepped drill 1 so that wear progresses or breaks. Moreover, when it exceeds 30 °, the thickness of the cutting edge of the finishing blade 22 of the large diameter portion 21 is reduced, the durability of the cutting edge of the finishing blade 22 of the large diameter portion 21 is reduced, and a large diameter is used when cutting into a metal material. This is because the impact generated at the cutting edge of the finishing blade 22 of the portion 21 increases, and chipping occurs at the cutting edge of the finishing blade 22 of the large diameter portion 21.

小径部２０のねじれ角α１が大径部２１のねじれ角α２よりも小さく（α１＜α２）なるように設定される理由は、小径部２０のねじれ溝８よりも大径部２１のねじれ溝８の切り屑の排出特性を高くするためである。例えば、ねじれ溝を成形する一般的な製造方法は、ねじれ溝がドリルを一周する長さ（以下、リードという）を設定値とし、ねじれ角をθ、ドリル直径をＤ、リードをＬ、円周率をπとすると、「θ＝ｔａｎ^−１（πＤ／Ｌ）」なる関係式が成立する。そのため、ドリル直径Ｄを大きくするとねじれ角θも大きくすることができる。そして、ドリルを製造する際にリードＬを一定にすると、小径部２０の直径Ｄ１よりも大径部２１の直径Ｄ２が大きい（Ｄ１＜Ｄ２）ため、小径部２０のねじれ角α１が大径部２１のねじれ角α２よりも小さく（α１＜α２）なるように設定することができ、かつ、段付きドリル１の切り屑の排出特性を高くすることもできる。ねじれ溝８を形成する際に小径部２０から大径部２１まで一工程で加工できる点と、穴加工時の切り屑の排出特性を向上させることができる点を考慮して、小径部２０のねじれ角α１が大径部２１のねじれ角α２よりも小さく（α１＜α２）なるように、ねじれ角を限定することが望ましい。 The reason why the twist angle α1 of the small diameter portion 20 is set to be smaller than the twist angle α2 of the large diameter portion 21 (α1 <α2) is that the twist groove 8 of the large diameter portion 21 is larger than the twist groove 8 of the small diameter portion 20. This is to increase the discharge characteristics of chips. For example, in a general manufacturing method for forming a twisted groove, a length (hereinafter referred to as a lead) that the twisted groove makes a round of the drill is set as a set value, a twist angle is θ, a drill diameter is D, a lead is L, a circumference When the rate is π, the relational expression “θ = tan ⁻¹ (πD / L)” is established. Therefore, when the drill diameter D is increased, the twist angle θ can be increased. When the lead L is made constant when manufacturing the drill, the diameter D2 of the large diameter portion 21 is larger than the diameter D1 of the small diameter portion 20 (D1 <D2), so that the twist angle α1 of the small diameter portion 20 is the large diameter portion. 21 can be set to be smaller than the twist angle α2 (α1 <α2), and the chip discharge characteristics of the step drill 1 can be enhanced. In consideration of the point that the small-diameter portion 20 to the large-diameter portion 21 can be processed in one step when forming the twisted groove 8, and the point that the chip discharge characteristics can be improved during drilling. It is desirable to limit the twist angle so that the twist angle α1 is smaller than the twist angle α2 of the large diameter portion 21 (α1 <α2).

小径部２０については、図２および図３に示すように、先端に位置するチゼルエッジ２を含むチゼルエッジコーナ３から外周コーナ６へ延びる稜線である切れ刃５を有し、シンニング面４と隣り合うすくい面３２と、すくい面３２とシンニング面４を介して隣り合う逃げ面３０を有し、シンニング面４はチゼルエッジコーナ３とねじれ溝８に面取りを施すように形成されている。また、小径部２０の切れ刃５は逃げ面３０とシンニング面４およびすくい面３２が隣り合うことで形成された稜線で、小径部２０の切れ刃５と、小径部２０の切れ刃５に隣接するすくい面３２に面取りを施してチャンファ３１が形成されている。つまり、チャンファ３１は図３に示すように、シンニング面４および逃げ面３０に隣接しており、切れ刃５の一部と外周コーナ６を含む領域である。小径部２０の切れ刃５のすくい面３２にチャンファ３１を設ける理由は、小径部２０の切れ刃５が被削材、特に金属材料に切り込む場合に、小径部２０の切れ刃５の刃先にかかる切削抵抗を軽減するためである。 As shown in FIGS. 2 and 3, the small-diameter portion 20 has a cutting edge 5 that is a ridge line extending from the chisel edge corner 3 including the chisel edge 2 located at the tip to the outer periphery corner 6, and is adjacent to the thinning surface 4. The rake face 32 has a flank 30 adjacent to the rake face 32 and the thinning surface 4, and the thinning face 4 is formed to chamfer the chisel edge corner 3 and the twisted groove 8. The cutting edge 5 of the small diameter portion 20 is a ridge formed by the flank 30, the thinning surface 4 and the rake face 32 being adjacent to each other, and is adjacent to the cutting edge 5 of the small diameter portion 20 and the cutting edge 5 of the small diameter portion 20. A chamfer 31 is formed by chamfering the rake face 32. That is, as shown in FIG. 3, the chamfer 31 is an area that is adjacent to the thinning surface 4 and the flank 30 and includes a part of the cutting edge 5 and the outer corner 6. The reason why the chamfer 31 is provided on the rake face 32 of the cutting edge 5 of the small diameter part 20 is that the cutting edge 5 of the small diameter part 20 is applied to the cutting edge of the cutting edge 5 of the small diameter part 20 when cutting into the work material, particularly a metal material. This is for reducing cutting resistance.

また、チャンファ３１の角度δについては、図４に示すように、段付きドリル１の外周コーナ６を通り軸心Ｏと平行な直線Ｐと、外周コーナ６を通りチャンファ３１と小径部２０のマージンとで形成される稜線を含む直線Ｑと、のなす角度であり、５°以上１５°以下とすることが望ましい。チャンファ３１の角度δの範囲が限定される理由は、５°未満では、小径部２０の切れ刃５の刃先が金属材料に切り込む切削力が足りないため穴加工を施すことができず、１５°を超えると、小径部２０の切れ刃５の刃先の厚みが小さく耐久性が不十分になり、チッピングが発生するためである。 As for the angle δ of the chamfer 31, as shown in FIG. 4, a straight line P passing through the outer peripheral corner 6 of the step drill 1 and parallel to the axis O, and the margin between the chamfer 31 and the small diameter portion 20 through the outer peripheral corner 6. And an angle formed by a straight line Q including a ridge line formed by and is preferably 5 ° or more and 15 ° or less. The reason why the range of the angle δ of the chamfer 31 is limited is that if it is less than 5 °, the cutting edge 5 of the small-diameter portion 20 has insufficient cutting force to cut into the metal material, so that the hole processing cannot be performed. This is because the thickness of the cutting edge 5 of the cutting edge 5 of the small diameter portion 20 is small and the durability becomes insufficient, and chipping occurs.

大径部２１については、図１に示すように、小径部２０との境界（段付き部）に二つの仕上げ刃２２、２２を有し、大径部２１の二つの仕上げ刃２２、２２は軸心Ｏを基準にして対称の関係にあり、大径部２１の二つの仕上げ刃２２、２２がなす角度をステップ角βとしている。大径部２１の仕上げ刃２２のステップ角βについては、小径部２０が最初に被削材に下穴をあけることで発生するバリを除去する性能を確保する点から１８０°に設定する。大径部２１の仕上げ刃２２のステップ角βが１８０°に設定される理由は、１８０°未満では、大径部２１の仕上げ刃２２が被削材へ切り込む切削力が弱いため、大径部２１で加工された加工穴の出口に新たなバリが発生するためである。また、１８０°を超えると、大径部２１の仕上げ刃２２の刃先の厚みが小さくなり、耐久性が不十分になる。さらに、被削材に極度に強く切り込むため仕上げ刃２２に大きな衝撃が発生し、大径部２１の仕上げ刃２２の刃先にチッピングが発生するためである。 About the large diameter part 21, as shown in FIG. 1, it has the two finishing blades 22 and 22 in the boundary (stepped part) with the small diameter part 20, and the two finishing blades 22 and 22 of the large diameter part 21 are The angle between the two finishing blades 22 and 22 of the large-diameter portion 21 is a step angle β that is symmetrical with respect to the axis O. The step angle β of the finishing blade 22 of the large-diameter portion 21 is set to 180 ° from the viewpoint of ensuring the performance of removing the burrs generated when the small-diameter portion 20 first drills a pilot hole in the work material. The reason why the step angle β of the finishing blade 22 of the large-diameter portion 21 is set to 180 ° is that if it is less than 180 °, the cutting force that the finishing blade 22 of the large-diameter portion 21 cuts into the work material is weak. This is because a new burr is generated at the exit of the processed hole processed at 21. If it exceeds 180 °, the thickness of the cutting edge of the finishing blade 22 of the large-diameter portion 21 becomes small, and the durability becomes insufficient. In addition, since the cutting blade 22 is extremely strongly cut, a large impact is generated on the finishing blade 22 and chipping occurs on the cutting edge of the finishing blade 22 of the large diameter portion 21.

また、同様に図１に示すように、大径部２１の仕上げ刃２２の延長線Ｉと、大径部２１の外周コーナ７を通り軸心Ｏと垂直な直線Ｊとがなす角度をγ（大径部２１の仕上げ刃２２の逃げ角）としている。大径部２１の仕上げ刃２２の逃げ角γについては、大径部２１の仕上げ刃２２の刃先の耐久性を確保する点から５°以上１５°以下の範囲に限定することができる。大径部２１の仕上げ刃２２の逃げ角γの範囲が限定される理由は、５°未満では、大径部２１の仕上げ刃２２が被削材へ切り込む場合に、大径部２１の仕上げ刃２２の刃先への負荷が大きくなり、また、１５°を超えると、大径部２１の仕上げ刃２２の刃先の耐久性が不十分であるために、チッピングが発生するためである。 Similarly, as shown in FIG. 1, the angle formed between the extension line I of the finishing blade 22 of the large diameter portion 21 and the straight line J passing through the outer peripheral corner 7 of the large diameter portion 21 and perpendicular to the axis O is γ ( The clearance angle of the finishing blade 22 of the large diameter portion 21). The clearance angle γ of the finishing blade 22 of the large diameter portion 21 can be limited to a range of 5 ° or more and 15 ° or less from the viewpoint of ensuring the durability of the cutting edge of the finishing blade 22 of the large diameter portion 21. The reason why the clearance angle γ of the finishing blade 22 of the large-diameter portion 21 is limited is that the finishing blade of the large-diameter portion 21 is less than 5 ° when the finishing blade 22 of the large-diameter portion 21 cuts into the work material. This is because when the load on the cutting edge 22 becomes large and exceeds 15 °, chipping occurs due to insufficient durability of the cutting edge of the finishing blade 22 of the large diameter portion 21.

なお、本発明に係る段付きドリルは、材質は超硬合金または高速度工具鋼である。また、必要に応じて、先端部に油穴を設けることやＴｉＡｌＮ系やＤＬＣ系のコーティング膜を工具表面に施すこともできる。 The step drill according to the present invention is made of cemented carbide or high-speed tool steel. If necessary, an oil hole can be provided at the tip, or a TiAlN-based or DLC-based coating film can be applied to the tool surface.

本発明に係る段付きドリル（以下、本発明品という）および従来の段付きドリル（以下、従来品という）を用いて以下の加工条件で切削試験を行った。切削試験に用いた本発明品および従来品は、材質は超硬合金、小径部の直径４．４ｍｍ、大径部の直径４．８ｍｍ、ドリル全長８０ｍｍ、シャンク径６ｍｍ、チャンファの角度１０°、先端角１２０°とすることを共通仕様とした。また、本発明品は、小径部のねじれ角１７°、大径部のねじれ角１９°、ステップ角１８０°とする段付きドリルとした。従来品は、小径部のねじれ角４５°、大径部のねじれ角４７°、ステップ角１６０°とする段付きドリルとした。
・被削材：ＣＦＲＰ（炭素繊維強化プラスチック）とＴｉ（チタン）合金の接合材料
・被削材の肉厚：１５ｍｍ（ＣＦＲＰ；１０ｍｍ、Ｔｉ；５ｍｍ）
・被削材の接合方法：ボルトによる対角２点締めつけ固定
・切削油：水溶性油剤
・加工態様：ＣＦＲＰ側からＴｉ合金側への貫通穴加工
・切削速度：１７．８ｍｍ／ｍｉｎ
・送り量：０．０５ｍｍ／ｒｅｖ
・送り速度：５９．０ｍｍ／ｍｉｎ
・回転数：１１８０ｍｉｎ^―１ A cutting test was performed under the following processing conditions using a step drill according to the present invention (hereinafter referred to as the present product) and a conventional step drill (hereinafter referred to as a conventional product). The product of the present invention and the conventional product used in the cutting test are made of cemented carbide, a diameter of the small diameter portion of 4.4 mm, a diameter of the large diameter portion of 4.8 mm, an overall length of the drill of 80 mm, a shank diameter of 6 mm, a chamfer angle of 10 °, A common specification is that the tip angle is 120 °. The product of the present invention was a stepped drill having a small-diameter portion twist angle of 17 °, a large-diameter portion twist angle of 19 °, and a step angle of 180 °. The conventional product was a step drill with a twist angle of 45 ° for the small diameter portion, a twist angle of 47 ° for the large diameter portion, and a step angle of 160 °.
Work material: Bonding material of CFRP (carbon fiber reinforced plastic) and Ti (titanium) alloyThickness of work material: 15 mm (CFRP; 10 mm, Ti; 5 mm)
-Joining method of work materials: Fixing by tightening two diagonal points with bolts-Cutting oil: Water-soluble oil- Machining mode: Drilling through holes from the CFRP side to the Ti alloy side-Cutting speed: 17.8 mm / min
・ Feed amount: 0.05mm / rev
・ Feeding speed: 59.0 mm / min
・ Rotation speed: 1180 min ^-1

切削試験後の被削材へ与えた影響、段付きドリルの各部位への影響および切削抵抗を確認した結果について、表１および表２ならびに図５および図６を用いて説明する。切削試験後の被削材の加工穴（接合していた被削材を分離して、ＣＦＲＰとＴｉ合金の入口側及び出口側の加工穴）については目視よる外観観察とバリ高さの測定を、段付きドリルの各部位については拡大鏡による外観観察を行った。また、切削抵抗の測定は切削試験と同時に行った。 The effects on the work material after the cutting test, the effects on each part of the step drill, and the results of confirming the cutting resistance will be described with reference to Tables 1 and 2 and FIGS. 5 and 6. Machining holes in the work material after the cutting test (separated work materials that have been joined together, machining holes on the CFRP and Ti alloy inlet side and outlet side) are visually observed and burr height is measured. The appearance of each step of the step drill was observed with a magnifier. The cutting resistance was measured simultaneously with the cutting test.

表１は切削試験後の被削材の加工穴の入口側と出口側のバリ高さを測定した結果である。表２は切削試験後の段付きドリルの小径部および大径部の各部位におけるチッピング及び摩耗の発生状況を観察した結果をまとめた表である。 Table 1 shows the results of measuring the burr height on the entrance side and the exit side of the machining hole of the work material after the cutting test. Table 2 is a table summarizing the results of observing the occurrence of chipping and wear at each of the small diameter part and the large diameter part of the step drill after the cutting test.

切削試験後の被削材へ与えた影響に関しては、表１に示すように、本発明品を用いて穴加工を施した被削材では、ＣＦＲＰとＴｉ合金の入口側および出口側のバリ高さは０．０２〜０．０７ｍｍであり、０．１ｍｍ未満と良好であった。しかし、従来品を用いて穴加工を施した被削材では、Ｔｉ合金出口側のバリ高さが０．１ｍｍを超え、高いところでは約１．５ｍｍもあったため、穴加工後に新たにバリを除去する工程が必要になった。 Regarding the influence on the work material after the cutting test, as shown in Table 1, in the work material drilled using the product of the present invention, the burr heights on the inlet side and the outlet side of CFRP and Ti alloy are high. The thickness was 0.02 to 0.07 mm, which was good at less than 0.1 mm. However, in the work material that has been drilled using conventional products, the burr height on the Ti alloy outlet side was more than 0.1 mm, and it was about 1.5 mm at high places. A process to remove was necessary.

また、段付きドリルの各部位への影響に関しては、表２に示すように、本発明品では小径部のチゼルエッジ、切れ刃、外周コーナ、マージン、および大径部の仕上げ刃、外周コーナ、マージンにおいて、チッピング及び大きな摩耗は認められなかった。しかし、従来品ではチゼルエッジ以外の各部位でチッピング及び摩耗が観察された。例えば、小径部の切れ刃と外周コーナ、および大径部の仕上げ刃と外周コーナにおいてはチッピングが観察され、さらに、小径部と大径部のマージンにおいては大きな摩耗が観察された。以上より、本発明品は各部位でのチッピング及び摩耗を低減することで、金属材料の加工穴出口におけるバリ高さを軽減することができ、かつ、高品位な加工穴を高精度に施すことができた。 In addition, as shown in Table 2, with respect to the influence on each part of the step drill, the present invention product has a small-diameter chisel edge, a cutting edge, a peripheral corner, a margin, and a large-diameter finishing blade, a peripheral corner, and a margin. No chipping or significant wear was observed. However, in the conventional product, chipping and wear were observed in each part other than the chisel edge. For example, chipping was observed in the cutting edge and outer peripheral corner of the small diameter portion, and finishing blade and outer peripheral corner of the large diameter portion, and further, large wear was observed in the margin of the small diameter portion and the large diameter portion. As described above, the product of the present invention can reduce the burr height at the processing hole outlet of the metal material by reducing chipping and wear at each part, and can provide a high-quality processing hole with high accuracy. I was able to.

次に、図５は切削試験を行った段付きドリルに発生した切削抵抗（スラスト）の測定結果であり、図６は切削抵抗（トルク）の測定結果である。また、両図において縦軸は切削抵抗（図５：スラスト、図６：トルク）、横軸は加工時間を示し、図５および図６ともに本発明品の測定結果を太く濃い曲線で、従来品の測定結果を細く薄い曲線で示している。 Next, FIG. 5 is a measurement result of cutting resistance (thrust) generated in a stepped drill subjected to a cutting test, and FIG. 6 is a measurement result of cutting resistance (torque). In both figures, the vertical axis represents cutting resistance (FIG. 5: thrust, FIG. 6: torque), the horizontal axis represents machining time, and the measurement results of the present invention are thick and dark curves in both FIG. 5 and FIG. The measurement results are shown by thin and thin curves.

切削抵抗（スラスト）に関しては、図５に示すように加工開始から終了まで従来品と本発明品のスラストの最大値は共に約３００Ｎであり、差は認められなかった。しかし、加工時間が２５秒以降から３０秒までの間においては従来品と本発明品とのスラストに差が認められ、従来品が９０Ｎ以上であるのに対し、本発明品は２０Ｎ以下であり、本発明品は従来品と比較すると、切削抵抗（スラスト）が８０％以上低減された。 Regarding the cutting resistance (thrust), as shown in FIG. 5, the maximum value of the thrust of the conventional product and the product of the present invention was about 300 N from the start to the end of processing, and no difference was recognized. However, in the processing time from 25 seconds to 30 seconds, there is a difference in thrust between the conventional product and the present invention product, while the conventional product is 90 N or more, while the present product is 20 N or less. In the product of the present invention, cutting resistance (thrust) was reduced by 80% or more compared to the conventional product.

また、切削抵抗（トルク）に関しては、図６に示すように加工開始から加工時間が２０秒までは、従来品と本発明品とのトルクに差は認められなかった。しかし、加工時間が２０秒以降で約２０Ｎ・ｃｍの差が認められ、さらに加工が進んで加工時間が２５秒においては、従来品、本発明品ともにトルクが最大値に達した。そして、従来品の最大トルクは１３０Ｎ・ｃｍ以上であるのに対し、本発明品の最大トルクは約８０Ｎ・ｃｍであり、本発明品は従来品と比較すると、切削抵抗（最大トルク）が約４０％低減された。 Regarding the cutting resistance (torque), as shown in FIG. 6, no difference was found in torque between the conventional product and the present invention product until the machining time was 20 seconds from the machining start. However, a difference of about 20 N · cm was recognized after the machining time of 20 seconds, and when the machining progressed and the machining time was 25 seconds, the torque reached the maximum value for both the conventional product and the present invention product. The maximum torque of the conventional product is 130 N · cm or more, whereas the maximum torque of the product of the present invention is about 80 N · cm. The product of the present invention has a cutting resistance (maximum torque) of about 80 N · cm. 40% reduction.

このことから、本発明品は小径部の切れ刃や外周コーナ、及び大径部の仕上げ刃や外周コーナに発生した衝撃（スラスト）が小さかったために、チッピングが少なく、段付きドリルと被削材が接する場合に発生したトルクが小さくなり、最大トルクが抑えられた。また、本発明品は最大トルクを従来品よりも低く抑えられたため、段付きドリルの各部位の温度上昇が抑えられ、摩耗による損傷も少なくなり、金属材料の加工穴出口におけるバリ高さを軽減することができ、かつ、高品位な加工穴を高精度に施すことができた。 For this reason, the product of the present invention has less chipping because the impact (thrust) generated on the cutting edge and outer peripheral corner of the small diameter part and the finishing blade and outer peripheral corner of the large diameter part is small. The torque generated when the contact is reduced, and the maximum torque was suppressed. In addition, since the maximum torque of the product of the present invention is kept lower than that of the conventional product, the temperature rise of each part of the step drill is suppressed, damage due to wear is reduced, and the burr height at the hole outlet of the metal material is reduced. And high-quality drilled holes could be made with high accuracy.

なお、被削材が繊維強化プラスチックと金属材料からなる接合材料である場合において、繊維強化プラスチック側から穴加工を施す場合だけでなく、金属材料側から穴加工を施す場合にも高品位な加工穴が高精度に形成されること、また、チッピングや摩耗が軽減されたことによって段付きドリルの寿命が向上されることは言うまでもない。 In addition, when the work material is a bonding material consisting of fiber reinforced plastic and metal material, high-quality processing is possible not only when drilling from the fiber reinforced plastic side but also when drilling from the metal material side. Needless to say, the hole is formed with high precision, and the life of the step drill is improved by reducing chipping and wear.

１段付きドリル
５切れ刃
２０小径部
２１大径部
３１チャンファ
３２すくい面
α１小径部２０のねじれ角
α２大径部２１のねじれ角
β ステップ角 1 Step drill 5 Cutting edge 20 Small diameter portion 21 Large diameter portion 31 Chamfer 32 Rake face α1 Torsion angle α2 of small diameter portion 20 Torsion angle β of large diameter portion 21 Step angle

Claims

A small-diameter portion provided with a chamfer on the rake face of the cutting edge for first drilling the work material, a large-diameter portion having a torsion angle larger than the torsion angle of the small-diameter portion and having a finishing blade, A step angle of the large-diameter portion is 180 °, and a twist angle of the large-diameter portion is 30 ° or less, passing through an outer peripheral corner of the step drill, and an axis O An angle δ formed by a straight line P parallel to the straight line Q and a straight line Q including a ridge line formed by the chamfer and the margin of the small diameter portion through the outer peripheral corner is 5 ° or more and 15 ° or less. Step drill.