JP2021151681A

JP2021151681A - Drill

Info

Publication number: JP2021151681A
Application number: JP2020052952A
Authority: JP
Inventors: 匡山本; Tadashi Yamamoto
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2020-03-24
Filing date: 2020-03-24
Publication date: 2021-09-30
Anticipated expiration: 2040-03-24

Abstract

To effectively suppress the occurence of burr at an opening portion during drilling through a through-hole without occurence of a defect or chipping of a cutting blade and clogging of a chip discharge groove with chips.SOLUTION: A chip discharge groove 5 is formed at an outer periphery of a tip end of a shaft-shaped drill body 1 having an axial line O rotatable in a drill rotation direction T about the axial line O. A cutting blade 3 is formed on a crossing ridge line portion between a wall surface of the chip discharge groove 5, which faces the drill rotation direction T, and a tip flank surface 4 of the drill body 1. The cutting blade 3 includes a main cutting blade 3b formed on an inner peripheral side of the drill body 1 and an auxiliary cutting blade 3c continuous with the main cutting blade 3b on an outer peripheral side of the drill body 1. An axial rake angle θ2 of the auxiliary cutting blade 3c is larger at a positive angle side than an axial rake angle θ1 of the main cutting blade 3b.SELECTED DRAWING: Figure 3

Description

本発明は、軸線回りにドリル回転方向に回転させられる上記軸線を中心とした軸状のドリル本体の先端部外周に切屑排出溝が形成され、この切屑排出溝の上記ドリル回転方向を向く壁面と上記ドリル本体の先端逃げ面との交差稜線部に切刃が形成されたドリルに関するものである。 In the present invention, a chip discharge groove is formed on the outer periphery of the tip of the axial drill body centered on the axis that is rotated in the drill rotation direction around the axis, and the wall surface of the chip discharge groove facing the drill rotation direction. The present invention relates to a drill in which a cutting edge is formed at an intersecting ridge line portion with the tip flank surface of the drill body.

このようなドリルによる穴明け加工において、金属や炭素繊維強化プラスチック（ＣＦＲＰ）、あるいは金属とＣＦＲＰを積層した積層材等に貫通穴をあける際に、貫通穴の抜け際の開口部に発生するバリを低減することが課題となる。 In drilling with such a drill, burrs generated in the opening when the through hole is removed when a through hole is made in metal, carbon fiber reinforced plastic (CFRP), or a laminated material in which metal and CFRP are laminated. Is an issue to reduce.

このようなバリを低減する手段として、切屑排出溝の捩れ角を大きくして切刃の軸方向すくい角を正角側に大きくすることにより、加工方向とは反対側の力を増大させてスラスト加重を抑えるとともに、切刃の刃物角を小さくして切れ味を向上させることが考えられる。 As a means of reducing such burrs, the twist angle of the chip discharge groove is increased and the axial rake angle of the cutting edge is increased to the conformal side to increase the force on the side opposite to the machining direction and thrust. It is conceivable to suppress the load and reduce the cutting edge angle of the cutting edge to improve the sharpness.

ところが、切屑排出溝の捩れ角を大きくすると、切屑排出溝の全長が長くなってしまって切屑排出性が損なわれ、切屑詰まりを生じるおそれがある。また、切刃の刃物角が小さくなると切刃強度が低下してしまい、切刃の欠損やチッピングによって早期にドリル寿命を迎えるおそれもある。 However, if the twist angle of the chip discharge groove is increased, the total length of the chip discharge groove becomes long, the chip discharge property is impaired, and chip clogging may occur. Further, if the blade angle of the cutting edge is reduced, the cutting edge strength is reduced, and there is a possibility that the drill life will be reached early due to the chipping or chipping of the cutting edge.

そこで、例えば特許文献１には、棒状のドリル本体と、このドリル本体の先端部に位置して、先端部に向かって見た場合に直線部を有する主切刃と、ドリル本体の外周に設けられた、主切刃の後方からドリル本体の後端部側に向かってドリル本体の回転軸の周りに螺旋状に延びている切屑排出溝と、主切刃に沿って主切刃と切屑排出溝との間に設けられた主すくい面とを備え、この主すくい面は、直線部に沿って設けられた平坦部と、この平坦部と切屑排出溝との間に位置して、切屑排出溝よりも凹んでいる凹部とを有しているドリルが記載されている。 Therefore, for example, in Patent Document 1, a rod-shaped drill body, a main cutting edge located at the tip of the drill body and having a straight portion when viewed toward the tip, and an outer periphery of the drill body are provided. A chip discharge groove that spirally extends around the rotation axis of the drill body from the rear of the main cutting edge toward the rear end side of the drill body, and the main cutting edge and chip discharge along the main cutting edge. It is provided with a main rake face provided between the groove and the main rake face, which is located between a flat portion provided along a straight portion and the flat portion and the chip discharge groove to discharge chips. A drill having a recess that is recessed from the groove is described.

このようなドリルでは、主すくい面に設けられた平坦部が切屑排出溝よりも凹んだ凹部に連なることにより、この平坦部における主切刃の直線部の軸方向すくい角は、切屑排出溝の捩れ角よりも正角側に大きくなる。従って、切屑排出溝の全長を長くすることなく、主切刃の直線部の切れ味を鋭くすることができる。 In such a drill, the flat portion provided on the main rake face is connected to a recess recessed from the chip discharge groove, so that the axial rake angle of the straight portion of the main cutting edge in this flat portion is the chip discharge groove. It becomes larger on the conformal side than the twist angle. Therefore, the sharpness of the straight portion of the main cutting edge can be sharpened without increasing the total length of the chip discharge groove.

特許第６３４３００５号公報Japanese Patent No. 6343005

ところが、この特許文献１に記載されたドリルでは、主切刃に隣接してドリル本体の後端部側に位置する副切刃を有しており、主すくい面の直線部に沿って設けられた上記平坦部は、この副切刃から離れていて、主切刃の外周端に達するように形成されてはおらず、主切刃の外周部で発生したバリを副切刃によって除去するようにしている。 However, the drill described in Patent Document 1 has a secondary cutting edge located adjacent to the main cutting edge on the rear end side of the drill body, and is provided along a straight portion of the main rake face. The flat portion is separated from the secondary cutting edge and is not formed so as to reach the outer peripheral edge of the main cutting edge, and the burr generated on the outer peripheral portion of the main cutting edge is removed by the secondary cutting edge. ing.

しかしながら、上述のような貫通穴の穴明け加工では、バリが生じ易いのは貫通穴の抜け際の開口部の周縁部分であり、このような部分を切削する主切刃の外周部に上記平坦部が形成されずに軸方向すくい角が正角側に大きくされていないと、主として貫通穴を形成する主切刃の切れ味が鈍ってしまい、発生したバリを副切刃によって完全に除去することは困難となる。 However, in the above-mentioned drilling of through holes, burrs are likely to occur at the peripheral edge of the opening at the time of exiting the through hole, and the above flat surface is formed on the outer peripheral portion of the main cutting edge for cutting such a portion. If the rake angle in the axial direction is not increased to the conformal side without forming a portion, the sharpness of the main cutting edge that mainly forms the through hole becomes dull, and the generated burr is completely removed by the secondary cutting edge. Becomes difficult.

その一方で、軸線回りの周速が遅いために大きなスラスト荷重が作用するドリル本体の内周部では、主切刃の直線部に平坦部が形成されているために刃物角は小さくなる。このため、このドリル本体内周部の主切刃の直線部に欠損やチッピング等が発生し易くなるおそれもある。 On the other hand, in the inner peripheral portion of the drill body on which a large thrust load acts due to the slow peripheral speed around the axis, the cutting edge angle becomes small because the flat portion is formed in the straight portion of the main cutting edge. Therefore, there is a possibility that the straight portion of the main cutting edge on the inner peripheral portion of the drill body is likely to be chipped or chipped.

本発明は、このような背景の下になされたもので、切刃の欠損やチッピング、切屑排出溝における切屑詰まりを生じることなく、貫通穴の抜け際の開口部におけるバリの発生を効果的に抑制することが可能なドリルを提供することを目的としている。 The present invention has been made under such a background, and effectively generates burrs at the opening when the through hole is pulled out without causing chipping of the cutting edge, chipping, and chip clogging in the chip discharge groove. It is intended to provide a drill that can be suppressed.

上記課題を解決して、このような目的を達成するために、本発明は、軸線回りにドリル回転方向に回転させられる上記軸線を中心とした軸状のドリル本体の先端部外周に切屑排出溝が形成され、この切屑排出溝の上記ドリル回転方向を向く壁面と上記ドリル本体の先端逃げ面との交差稜線部に切刃が形成されたドリルであって、上記切刃は、上記ドリル本体の内周側に形成される主切刃と、この主切刃のドリル本体外周側に連なる副切刃とを備え、上記副切刃の軸方向すくい角が上記主切刃の軸方向すくい角よりも正角側に大きいことを特徴とする。 In order to solve the above problems and achieve such an object, the present invention presents a chip discharge groove on the outer periphery of the tip of a shaft-shaped drill body centered on the above axis, which is rotated in the direction of rotation of the drill around the axis. Is formed, and a cutting edge is formed at the intersection ridge line portion between the wall surface of the chip discharge groove facing the direction of rotation of the drill and the tip flank surface of the drill body, and the cutting edge is the drill body of the drill body. A main cutting edge formed on the inner peripheral side and a secondary cutting edge connected to the outer peripheral side of the drill body of the main cutting edge are provided, and the axial rake angle of the secondary cutting edge is larger than the axial rake angle of the main cutting edge. Is also characterized by being large on the regular angle side.

このように構成されたドリルでは、切刃のうち主切刃のドリル本体外周側に連なる副切刃の軸方向すくい角が主切刃の軸方向すくい角よりも正角側に大きいので、切刃の外周端側において切れ味を鋭くすることができ、金属やＣＦＲＰ、あるいは金属とＣＦＲＰを積層した積層材に貫通穴をあける際に、この貫通穴の抜け際の開口部に発生するバリを削り取って抑制することができる。 In the drill configured in this way, the axial rake angle of the secondary cutting edge connected to the outer peripheral side of the drill body of the main cutting edge is larger on the regular angle side than the axial rake angle of the main cutting edge. The sharpness can be sharpened on the outer peripheral edge side of the blade, and when a through hole is made in a metal, CFRP, or a laminated material in which metal and CFRP are laminated, burrs generated in the opening when the through hole is removed are scraped off. Can be suppressed.

その一方で、切刃のうちドリル本体内周側の主切刃では、副切刃に比べて軸方向すくい角が負角側に大きいので刃物角を大きく確保して切刃強度を維持することができる。このため、大きなスラスト荷重が作用しても、欠損やチッピングが生じるのを防ぐことができて、ドリル寿命の延長を図ることが可能となる。また、切屑排出溝の捩れ角は、この主切刃の軸方向すくい角に合わせて設定すればよいので、切屑排出溝の全長が長くなるのも防ぐことができて、切屑詰まりも防止することができる。 On the other hand, among the cutting blades, the main cutting edge on the inner peripheral side of the drill body has a larger axial rake angle on the negative angle side than the secondary cutting edge, so a large blade angle should be secured to maintain the cutting edge strength. Can be done. Therefore, even if a large thrust load is applied, it is possible to prevent chipping and chipping, and it is possible to extend the drill life. Further, since the twist angle of the chip discharge groove may be set according to the axial rake angle of the main cutting edge, it is possible to prevent the total length of the chip discharge groove from becoming long and prevent chip clogging. Can be done.

ここで、上記副切刃の上記軸線に対する径方向の幅は、上記切刃の直径Ｄの０．０５×Ｄ〜０．２０×Ｄの範囲内とされていることが望ましい。この副切刃の軸線に対する径方向の幅が切刃の直径Ｄの０．０５×Ｄを下回ると、貫通穴の抜け際の開口部に発生するバリを確実に除去することが困難となるおそれがある一方、切刃の直径Ｄの０．２０×Ｄを上回ると、軸方向すくい角が正角側に大きくて刃物角が小さくなる副切刃が切刃の全長に占める部分が大きくなりすぎて欠損やチッピングを生じるおそれが生じる。 Here, it is desirable that the width of the auxiliary cutting edge in the radial direction with respect to the axis is within the range of 0.05 × D to 0.20 × D of the diameter D of the cutting edge. If the radial width of the secondary cutting edge with respect to the axis is less than 0.05 × D of the diameter D of the cutting edge, it may be difficult to reliably remove burrs generated in the opening when the through hole is removed. On the other hand, if the diameter D of the cutting edge exceeds 0.20 × D, the rake angle in the axial direction is large on the regular angle side and the blade angle is small. There is a risk of chipping or chipping.

また、上記副切刃の軸方向すくい角が１０°〜５０°の範囲内とされるとともに、上記主切刃の軸方向すくい角が０°〜４０°の範囲内とされていることが望ましい。これら副切刃と主切刃の軸方向すくい角が上記範囲内よりも正角側に大きいと、特に副切刃の刃物角が小さくなりすぎて欠損やチッピングが発生し易くなる一方、上記範囲内よりも負角側に大きいと、切削抵抗の増大を招くおそれがある。なお、これら副切刃と主切刃の軸方向すくい角はドリル本体の軸線に対する径方向に向けて変化していてもよく、この場合には副切刃と主切刃の外周端における軸方向すくい角が上記範囲内であればよい。 Further, it is desirable that the axial rake angle of the secondary cutting edge is within the range of 10 ° to 50 ° and the axial rake angle of the main cutting edge is within the range of 0 ° to 40 °. .. If the axial rake angles of the secondary cutting blade and the main cutting blade are larger than within the above range on the conformal side, the blade angle of the secondary cutting blade becomes too small, and chipping and chipping are likely to occur, while the above range. If it is larger on the negative angle side than inside, it may lead to an increase in cutting resistance. The axial rake angles of the secondary cutting edge and the main cutting edge may change in the radial direction with respect to the axial line of the drill body. In this case, the axial direction at the outer peripheral ends of the secondary cutting edge and the main cutting edge. The rake angle may be within the above range.

ここで、上記副切刃のすくい面は、上記ドリル回転方向側から見て、三角形状または四角形状に形成されていてもよい。このように構成することにより、切刃の軸方向すくい角が主切刃の軸方向すくい角に合わせた通常のドリルを製造した後に、副切刃の部分にだけドリル回転方向から見て三角形状に副切刃のすくい面を研ぎ付けるだけで、容易に副切刃の軸方向すくい角を主切刃よりも正角側に大きくすることができる。 Here, the rake face of the secondary cutting edge may be formed in a triangular shape or a quadrangular shape when viewed from the drill rotation direction side. With this configuration, after manufacturing a normal drill in which the axial rake angle of the cutting edge matches the axial rake angle of the main cutting edge, only the secondary cutting edge has a triangular shape when viewed from the drill rotation direction. By simply sharpening the rake face of the secondary cutting edge, the axial rake angle of the secondary cutting edge can be easily increased to the conformal side of the main cutting edge.

なお、このうち、副切刃のすくい面を、上記ドリル回転方向側から見て、四角形状に形成する場合には、上記軸線に対する径方向の幅が上記軸線方向の長さよりも大きくされた四角形状に形成することにより、切刃のうち軸方向すくい角が正角側に大きい部分を長くすることができるので、切削抵抗の低減を図ることができる。また、これとは逆に、上記軸線方向の長さが上記軸線に対する径方向の幅よりも大きくされた四角形状に形成した場合には、切刃に摩耗が生じたときに先端逃げ面を研磨して新たな切刃を研ぎ付ける再研磨量を大きく確保することができる。 Of these, when the rake face of the secondary cutting edge is formed into a quadrangular shape when viewed from the drill rotation direction side, the width in the radial direction with respect to the axis is larger than the length in the axis direction. By forming the shape, the portion of the cutting edge having a large axial rake angle on the conformal side can be lengthened, so that cutting resistance can be reduced. On the contrary, when the length in the axial direction is formed into a quadrangular shape in which the length in the axial direction is larger than the width in the radial direction with respect to the axial line, the tip flank surface is polished when the cutting edge is worn. Therefore, a large amount of re-polishing for sharpening a new cutting edge can be secured.

また、上記副切刃は上記軸線方向先端側から見て上記主切刃よりも上記ドリル回転方向側に延びていてもよいが、上記副切刃は上記軸線方向先端側から見て上記主切刃よりも上記ドリル回転方向とは反対側に延びていることが、特に上述のように通常のドリルを製造した後に副切刃のすくい面を研ぎ付けて副切刃の軸方向すくい角を主切刃よりも正角側に大きくする場合に製造が容易となって望ましい。 Further, the sub cutting edge may extend toward the drill rotation direction side from the main cutting edge when viewed from the tip side in the axial direction, but the sub cutting edge may extend toward the tip side in the axial direction as viewed from the tip side in the axial direction. The fact that it extends in the direction opposite to the direction of rotation of the drill from the blade is mainly the axial rake angle of the secondary cutting edge by sharpening the rake face of the secondary cutting edge after manufacturing a normal drill as described above. It is desirable that the manufacturing is easy when the size is larger on the conformal side than the cutting edge.

なお、この場合には、上記主切刃と上記副切刃とは上記軸線方向先端側から見て段差をもっているとともに、上記副切刃と上記主切刃の間の段差部には上記軸線方向先端側から見て曲線状をなす接続部が形成されていることが、副切刃の径方向すくい角を主切刃と大きく変化させずに済むとともに、段差部が鋭くなって欠けが生じたりするのを防ぐことができて望ましい。 In this case, the main cutting blade and the sub cutting blade have a step when viewed from the tip side in the axial direction, and the step portion between the sub cutting blade and the main cutting blade has a step in the axial direction. The formation of a curved connection when viewed from the tip side does not require the radial rake angle of the secondary cutting edge to change significantly from that of the main cutting edge, and the stepped portion becomes sharp and chipped. It is desirable to be able to prevent it from happening.

ただし、上記副切刃は、上記軸線方向先端側から見て上記主切刃と折れ線状に連なっていたり、上記軸線方向先端側から見て上記主切刃に接する凸曲線状に形成されていたりしてもよい。この場合には、副切刃と主切刃の間に段差部が生じることがなくなるので、欠けを一層確実に防ぐことができるとともに、主切刃と副切刃によって生成される切屑が段差部で分断されることもなくなって、分断された切屑同士が絡まることによる切屑詰まりも防ぐことができる。 However, the auxiliary cutting edge may be connected to the main cutting edge in a polygonal line when viewed from the tip side in the axial direction, or may be formed in a convex curve shape which is in contact with the main cutting edge when viewed from the tip side in the axial direction. You may. In this case, since a stepped portion is not generated between the secondary cutting edge and the main cutting edge, chipping can be prevented more reliably, and the chips generated by the main cutting edge and the secondary cutting edge are the stepped portion. It is possible to prevent chip clogging due to entanglement of the divided chips.

一方、上記副切刃は、上記軸線方向先端側から見て上記主切刃から上記ドリル回転方向とは反対側に凹む凹曲線状に形成されていてもよい。この場合には、切屑は主切刃と副切刃とで分断されて生成されることになるが、副切刃によって生成された切屑は凹曲線に沿ってドリル本体の内周側に流れ出ることになるので、加工穴の内周面を傷付けるようなことがない。 On the other hand, the secondary cutting edge may be formed in a concave curved shape that is recessed from the main cutting edge to the side opposite to the drill rotation direction when viewed from the tip side in the axial direction. In this case, the chips are separated by the main cutting edge and the secondary cutting edge and generated, but the chips generated by the secondary cutting edge flow out to the inner peripheral side of the drill body along the concave curve. Therefore, the inner peripheral surface of the machined hole is not damaged.

以上説明したように、本発明によれば、切刃の欠損やチッピングを防いでドリル寿命の延長を図ることができるとともに、切屑排出溝における切屑詰まりを防止して安定した穴明け加工を行うことができ、さらに金属やＣＦＲＰ、あるいは金属とＣＦＲＰを積層した積層材に貫通穴をあける際に、この貫通穴の抜け際の開口部に発生するバリを副切刃によって削り取って抑制し、高品位の穴明け加工を行うことが可能となる。 As described above, according to the present invention, it is possible to prevent chipping and chipping of the cutting edge to extend the drill life, and prevent chip clogging in the chip discharge groove to perform stable drilling. Further, when making a through hole in a metal, CFRP, or a laminated material in which metal and CFRP are laminated, burrs generated in the opening at the time of exiting the through hole are scraped off by a secondary cutting edge to suppress it, resulting in high quality. It is possible to perform drilling.

本発明の第１の実施形態を示す軸線方向先端からから見たドリル本体の正面図である。It is a front view of the drill body seen from the tip in the axial direction which shows the 1st Embodiment of this invention. 図１における矢線Ｘ方向視の平面図である。It is a top view of the arrow X direction view in FIG. 図１における矢線Ｙ方向視の側面図である。It is a side view of the arrow line Y direction view in FIG. 本発明の第２の実施形態を示す軸線方向先端からから見たドリル本体の正面図である。It is a front view of the drill body seen from the tip in the axial direction which shows the 2nd Embodiment of this invention. 図４における矢線Ｘ方向視の平面図である。It is a top view of the arrow X direction view in FIG. 本発明の第３の実施形態を示す平面図である。It is a top view which shows the 3rd Embodiment of this invention. 本発明の第４の実施形態を示す軸線方向先端からから見たドリル本体の正面図である。It is a front view of the drill body seen from the tip in the axial direction which shows the 4th Embodiment of this invention. 本発明の第５の実施形態を示す軸線方向先端からから見たドリル本体の正面図である。It is a front view of the drill body seen from the tip in the axial direction which shows the 5th Embodiment of this invention. 本発明の第６の実施形態を示す軸線方向先端からから見たドリル本体の正面図である。It is a front view of the drill body seen from the tip in the axial direction which shows the 6th Embodiment of this invention.

図１〜図３は、本発明の第１の実施形態を示すものである。本実施形態のドリルは、そのドリル本体１が、超硬合金等の硬質材料により軸線Ｏを中心とした概略円柱軸状を形成されており、図示されない後端部は円柱状のままのシャンク部とされるとともに、先端部は切刃部２とされている。 1 to 3 show a first embodiment of the present invention. In the drill of the present embodiment, the drill body 1 is formed of a hard material such as cemented carbide in a substantially cylindrical shaft shape centered on the axis O, and the rear end portion (not shown) is a shank portion that remains cylindrical. At the same time, the tip portion is a cutting edge portion 2.

このようなドリルは、上記シャンク部が工作機械の主軸に把持されて軸線Ｏ回りにドリル回転方向Ｔに回転させられつつ該軸線Ｏ方向先端側に送り出され、切刃部２の先端に設けられた切刃３によって金属やＣＦＲＰ、あるいは金属とＣＦＲＰを積層した積層材に穴明け加工を行う。 In such a drill, the shank portion is gripped by the spindle of the machine tool, is rotated around the axis O in the drill rotation direction T, and is sent out to the tip side in the axis O direction, and is provided at the tip of the cutting edge portion 2. A drilling process is performed on a metal, CFRP, or a laminated material in which metal and CFRP are laminated by the cutting edge 3.

切刃部２の外周には、ドリル本体１の先端面である先端逃げ面４に開口して後端側（図２および図３において右側）に向かう切屑排出溝５が形成されている。本実施形態では、複数条（２条）の切屑排出溝５が周方向に等間隔にドリル本体１の後端側に向かうに従いドリル回転方向Ｔとは反対側に捩れるように形成されている。 A chip discharge groove 5 is formed on the outer periphery of the cutting edge portion 2 so as to open to the tip flank surface 4 which is the tip surface of the drill body 1 and to face the rear end side (right side in FIGS. 2 and 3). In the present embodiment, the chip discharge grooves 5 having a plurality of rows (2 rows) are formed so as to be twisted in the direction opposite to the drill rotation direction T as the chip discharge grooves 5 of the plurality of rows (2 rows) are directed toward the rear end side of the drill body 1 at equal intervals in the circumferential direction. ..

切屑排出溝５のドリル回転方向Ｔを向く壁面の先端部は上記切刃３のすくい面６とされており、切刃３はこのすくい面６と先端逃げ面４との交差稜線部に切刃３が形成されている。ここで、先端逃げ面４は、ドリル本体１の外周側とドリル回転方向Ｔとは反対側に向かうに従いドリル本体１の後端側に向かうように傾斜しており、これによって切刃３には所定の先端角と逃げ角とが与えられる。 The tip of the wall surface of the chip discharge groove 5 facing the drill rotation direction T is the rake face 6 of the cutting edge 3, and the cutting edge 3 is formed at the intersecting ridge line between the rake face 6 and the tip flank surface 4. 3 is formed. Here, the tip flank surface 4 is inclined so as to face the rear end side of the drill body 1 toward the outer peripheral side of the drill body 1 and the side opposite to the drill rotation direction T, whereby the cutting edge 3 has an inclination. A predetermined tip angle and clearance angle are given.

なお、先端逃げ面４は、本実施形態ではドリル回転方向Ｔとは反対側に向かうに従い逃げ角が段階的に大きくなる第１、第２先端逃げ面４ａ、４ｂによって形成されている。このうち、第２先端逃げ面４ｂには、周方向に切屑排出溝５の間を通ってドリル本体１に形成されたクーラント孔１ａがそれぞれ開口している。 In the present embodiment, the tip flank surface 4 is formed by the first and second tip flank surfaces 4a and 4b in which the clearance angle gradually increases toward the side opposite to the drill rotation direction T. Of these, the coolant hole 1a formed in the drill body 1 is opened in the second tip flank surface 4b through the space between the chip discharge grooves 5 in the circumferential direction.

また、切刃部２の外周面には、切屑排出溝５のドリル回転方向Ｔ側を向く壁面のドリル回転方向Ｔとは反対側に隣接してマージン部７ａが形成されるとともに、このマージン部７ａのドリル回転方向Ｔとは反対側は、マージン部７ａよりも外径が僅かに小さくされた外周逃げ面７ｂとされている。 Further, on the outer peripheral surface of the cutting edge portion 2, a margin portion 7a is formed adjacent to the side opposite to the drill rotation direction T of the wall surface of the chip discharge groove 5 facing the drill rotation direction T side, and this margin portion is formed. The side of 7a opposite to the drill rotation direction T is an outer peripheral flank surface 7b whose outer diameter is slightly smaller than that of the margin portion 7a.

さらに、切屑排出溝５の先端内周部には、この先端内周部をドリル本体１の軸線Ｏ側に切り欠くようにしてシンニング部８が形成されている。このシンニング部８は、本実施形態では切刃３のすくい面の内周部から、切屑排出溝５のドリル回転方向Ｔとは反対側を向く壁面と外周逃げ面７ｂとが交差するヒール部にかけて延びている。 Further, a thinning portion 8 is formed in the tip inner peripheral portion of the chip discharge groove 5 so that the tip inner peripheral portion is cut out on the axis O side of the drill body 1. In the present embodiment, the thinning portion 8 extends from the inner peripheral portion of the rake face of the cutting edge 3 to the heel portion where the wall surface of the chip discharge groove 5 facing the side opposite to the drill rotation direction T and the outer peripheral relief surface 7b intersect. It is extending.

さらにまた、上記切刃３は、すくい面６のうち上記シンニング部８に形成されたシンニングすくい面６ａと先端逃げ面４との交差稜線部に形成されるシンニング刃３ａと、このシンニング刃３ａのドリル本体１の外周側に連なり、切屑排出溝５のドリル回転方向Ｔ側を向く壁面の内周側の主すくい面６ｂと先端逃げ面４との交差稜線部に形成される主切刃３ｂと、この主切刃３ｂのドリル本体１の外周側に連なり、切屑排出溝５のドリル回転方向Ｔ側を向く壁面の外周側の副すくい面６ｃと先端逃げ面４との交差稜線部に形成される副切刃３ｃとを備えている。 Furthermore, the cutting edge 3 includes a thinning blade 3a formed at the intersecting ridge between the thinning rake surface 6a formed on the thinning portion 8 and the tip flank surface 4 of the rake face 6, and the thinning blade 3a. A main cutting edge 3b formed at the intersection ridge between the main rake face 6b on the inner peripheral side of the wall surface of the chip discharge groove 5 facing the drill rotation direction T side and the tip relief surface 4 connected to the outer peripheral side of the drill body 1. , Which is connected to the outer peripheral side of the drill body 1 of the main cutting edge 3b, and is formed at the intersecting ridge line portion between the secondary rake face 6c on the outer peripheral side of the wall surface facing the drill rotation direction T side of the chip discharge groove 5 and the tip flank surface 4. It is equipped with a secondary cutting edge 3c.

ここで、上述のように切屑排出溝５はドリル本体１の後端側に向かうに従いドリル回転方向Ｔとは反対側に捩れているので、この切屑排出溝５のドリル回転方向Ｔ側を向く壁面をすくい面６とする主切刃３ｂと副切刃３ｃには正角の軸方向すくい角θ１、θ２が与えられる。そして、図３に示すように、副切刃３ｃの軸方向すくい角θ２は主切刃３ｂの軸方向すくい角θ１よりも正角側に大きくされている。 Here, as described above, the chip discharge groove 5 is twisted in the direction opposite to the drill rotation direction T toward the rear end side of the drill body 1, so that the wall surface of the chip discharge groove 5 faces the drill rotation direction T side. The main cutting edge 3b and the sub cutting edge 3c having a rake face 6 are provided with conformal rake angles θ1 and θ2. Then, as shown in FIG. 3, the axial rake angle θ2 of the secondary cutting edge 3c is made larger on the conformal side than the axial rake angle θ1 of the main cutting edge 3b.

また、本実施形態では、このうち副切刃３ｃの軸方向すくい角θ２は１０°〜５０°の範囲内とされるとともに、主切刃３ｂの軸方向すくい角θ１は４０°以下の範囲内とされていて、これらの範囲内でθ２＞θ１とされている。なお、主切刃３ｂの軸方向すくい角θ１と副切刃３ｃの軸方向すくい角θ２は、ドリル本体１の軸線Ｏに対する径方向に向けて変化していてもよく、図３に示したように主切刃３ｂと副切刃３ｃの外周端における軸方向すくい角θ１、θ２が上記範囲内であればよい。 Further, in the present embodiment, the axial rake angle θ2 of the secondary cutting edge 3c is within the range of 10 ° to 50 °, and the axial rake angle θ1 of the main cutting edge 3b is within the range of 40 ° or less. In these ranges, θ2> θ1. The axial rake angle θ1 of the main cutting edge 3b and the axial rake angle θ2 of the secondary cutting edge 3c may change in the radial direction with respect to the axis O of the drill body 1, as shown in FIG. The axial rake angles θ1 and θ2 at the outer peripheral ends of the main cutting edge 3b and the secondary cutting edge 3c may be within the above ranges.

また、本実施形態では軸線Ｏ方向先端側から見て、シンニング刃３ａは、先端逃げ面４における内周側の軸線Ｏの近傍からドリル回転方向に凸となる凸曲線状にドリル本体１の外周側に延びて主切刃３ｂの内周端に接しており、主切刃３ｂはシンニング刃３ａとの接点から直線状に外周側に延びている。これに対して、副切刃３ｃは軸線Ｏ方向先端側から見て主切刃３ｂよりもドリル回転方向Ｔとは反対側に延びている。 Further, in the present embodiment, when viewed from the tip side in the axis O direction, the thinning blade 3a has a convex curve shape that is convex in the drill rotation direction from the vicinity of the axis O on the inner peripheral side of the tip flank surface 4, and is the outer circumference of the drill body 1. It extends to the side and is in contact with the inner peripheral end of the main cutting blade 3b, and the main cutting blade 3b extends linearly from the contact point with the thinning blade 3a to the outer peripheral side. On the other hand, the sub cutting edge 3c extends from the main cutting edge 3b to the side opposite to the drill rotation direction T when viewed from the tip side in the axis O direction.

より詳しくは、本実施形態では軸線Ｏ方向先端側から見て図１に示すように、副切刃３ｃは主切刃３ｂに対して段差をもってドリル回転方向Ｔとは反対側に位置して平行に延びるように形成されている。また、副切刃３ｃと主切刃３ｂの間の段差部には曲線状をなす接続部３ｄが形成されていて、この接続部３ｄは本実施形態では凹円弧等の凹曲線状に形成されている。すなわち、主切刃３ｂと副切刃３ｃ、および主すくい面６ｂと副すくい面６ｃとは不連続である。 More specifically, in the present embodiment, as shown in FIG. 1 when viewed from the tip side in the O direction of the axis line, the secondary cutting edge 3c is located parallel to the main cutting edge 3b on the side opposite to the drill rotation direction T with a step. It is formed so as to extend to. Further, a curved connecting portion 3d is formed at the step portion between the secondary cutting blade 3c and the main cutting blade 3b, and this connecting portion 3d is formed in a concave curved shape such as a concave arc in the present embodiment. ing. That is, the main cutting edge 3b and the sub cutting edge 3c, and the main rake face 6b and the sub rake face 6c are discontinuous.

さらに、ドリル回転方向Ｔ側から見て図２に示すように、副すくい面６ｃは三角形状に形成されている。この副すくい面６ｃは、主すくい面６ｂに対してドリル回転方向Ｔとは反対側に凹む凹面状に形成されており、副切刃３ｃから離れてドリル本体１の後端側に向かうに従い主すくい面６ｂよりも大きな傾斜角でドリル回転方向Ｔとは反対側に凹んだ後に、凹曲面を描いて主すくい面６ｂに切れ上がるように形成されている。 Further, as shown in FIG. 2 when viewed from the drill rotation direction T side, the secondary rake face 6c is formed in a triangular shape. The sub rake face 6c is formed in a concave shape that is recessed in the direction opposite to the drill rotation direction T with respect to the main rake face 6b, and is mainly formed as it moves away from the sub cutting edge 3c toward the rear end side of the drill body 1. It is formed so as to be recessed on the side opposite to the drill rotation direction T at an inclination angle larger than that of the rake face 6b, and then cut off to the main rake face 6b by drawing a concave curved surface.

さらに、本実施形態では、副切刃３ｃの軸線Ｏに対する径方向の幅Ｗが、切刃３の直径（切刃３の外周端が軸線Ｏ回りになす円の直径）Ｄの０．０５×Ｄ〜０．２０×Ｄの範囲内とされている。なお、この副切刃３ｃの軸線Ｏに対する径方向の幅Ｗは、上記接続部３ｄも含む主切刃３ｂの外周端から副切刃３ｃの外周端までの幅であり、また副切刃３ｃがシンニング刃３ａに達することはない。 Further, in the present embodiment, the width W in the radial direction of the auxiliary cutting edge 3c with respect to the axis O is 0.05 × of the diameter of the cutting edge 3 (the diameter of the circle formed by the outer peripheral end of the cutting edge 3 around the axis O) D. It is within the range of D to 0.20 × D. The radial width W of the secondary cutting edge 3c with respect to the axis O is the width from the outer peripheral end of the main cutting edge 3b including the connection portion 3d to the outer peripheral end of the secondary cutting edge 3c, and the secondary cutting edge 3c. Never reaches the thinning blade 3a.

このように構成されたドリルにおいては、切刃３のうち主切刃３ｂのドリル本体１外周側に連なる副切刃３ｃの軸方向すくい角θ２が、主切刃３ｂの軸方向すくい角θ１よりも正角側に大きいので、切刃３の外周端側において切れ味を鋭くすることができる。このため、金属やＣＦＲＰ、あるいは金属とＣＦＲＰを積層した積層材に貫通穴を穴明け加工する際に、この貫通穴の抜け際の開口部に発生するバリを副切刃３ｃによって削り取って抑制することができ、高品位の穴明け加工を行うことができる。 In the drill configured as described above, the axial rake angle θ2 of the secondary cutting edge 3c connected to the outer peripheral side of the drill body 1 of the main cutting edge 3b among the cutting blades 3 is larger than the axial rake angle θ1 of the main cutting edge 3b. Is also large on the conformal side, so that the sharpness can be sharpened on the outer peripheral end side of the cutting edge 3. For this reason, when drilling a through hole in a metal, CFRP, or a laminated material in which metal and CFRP are laminated, burrs generated in the opening at the time of exiting the through hole are scraped off by the auxiliary cutting blade 3c to suppress it. It is possible to perform high-quality drilling.

その一方で、切刃３のうち副切刃３ｃよりもドリル本体１の内周側の主切刃３ｂでは、副切刃３ｃに比べて軸方向すくい角θ１が負角側に大きいので、刃物角を大きく確保することができる。従って、切刃強度を維持することができるので、大きなスラスト荷重が作用するドリル本体１の内周側でも、欠損やチッピングが生じるのを防ぐことができて、ドリル寿命の延長を図ることが可能となる。しかも、切屑排出溝５の捩れ角は、この主切刃３ｂの軸方向すくい角θ１に合わせて設定することができるので、切屑排出溝５の全長が長くなるのも防ぐことができ、切屑詰まりも防止することができる。 On the other hand, among the cutting blades 3, the main cutting edge 3b on the inner peripheral side of the drill body 1 with respect to the secondary cutting edge 3c has a larger axial rake angle θ1 on the negative angle side than the secondary cutting edge 3c, so that the cutting edge is cut. A large corner can be secured. Therefore, since the cutting edge strength can be maintained, it is possible to prevent chipping and chipping even on the inner peripheral side of the drill body 1 on which a large thrust load acts, and it is possible to extend the drill life. It becomes. Moreover, since the twist angle of the chip discharge groove 5 can be set according to the axial rake angle θ1 of the main cutting edge 3b, it is possible to prevent the total length of the chip discharge groove 5 from becoming long, and the chip clogging can be prevented. Can also be prevented.

また、本実施形態では、副切刃３ｃの軸線Ｏに対する径方向の幅Ｗが、切刃３の直径Ｄの０．０５×Ｄ〜０．２０×Ｄの範囲内とされているので、バリの発生を確実に抑制しつつ、欠損やチッピングも防止することができる。 Further, in the present embodiment, the width W in the radial direction of the secondary cutting edge 3c with respect to the axis O is within the range of 0.05 × D to 0.20 × D of the diameter D of the cutting edge 3, so that the burr It is possible to prevent defects and chipping while surely suppressing the occurrence of.

すなわち、この副切刃３ｃの幅Ｗが切刃３の直径Ｄの０．０５×Ｄを下回ると、貫通穴の抜け際の開口部に発生するバリを確実に除去することが困難となるおそれがある。その一方で、この副切刃３ｃの幅Ｗが切刃３の直径Ｄの０．２０×Ｄを上回ると、軸方向すくい角θ２が正角側に大きくて刃物角が小さくなる副切刃３ｃが切刃３の全長に占める部分が大きくなりすぎて欠損やチッピングを生じるおそれが生じる。 That is, if the width W of the secondary cutting edge 3c is less than 0.05 × D of the diameter D of the cutting edge 3, it may be difficult to reliably remove the burr generated in the opening when the through hole is removed. There is. On the other hand, when the width W of the secondary cutting edge 3c exceeds 0.20 × D of the diameter D of the cutting edge 3, the axial rake angle θ2 is large on the conformal side and the cutting edge angle is small. However, the portion of the cutting edge 3 that occupies the entire length becomes too large, which may cause a chipping or chipping.

また、本実施形態では、副切刃３ｃの軸方向すくい角θ２が１０°〜５０°の範囲内とされるとともに、主切刃３ｂの軸方向すくい角θ１が４０°以下の範囲内とされており、これによっても主切刃３ｂや副切刃３ｃの欠損やチッピングを防ぎつつ、切削抵抗が必要以上に増大するのを防ぐことができる。 Further, in the present embodiment, the axial rake angle θ2 of the secondary cutting edge 3c is set to be within the range of 10 ° to 50 °, and the axial rake angle θ1 of the main cutting edge 3b is set to be within the range of 40 ° or less. This also prevents the main cutting edge 3b and the sub cutting edge 3c from being chipped or chipped, and prevents the cutting resistance from increasing more than necessary.

すなわち、これら主切刃３ｂと副切刃３ｃの軸方向すくい角θ１、θ２がそれぞれ上記範囲内よりも正角側に大きいと、特に副切刃３ｃの刃物角が小さくなりすぎて欠損やチッピングが発生し易くなる一方、上記範囲内よりも負角側に大きいと、切削抵抗の増大を招くおそれがある。なお、主切刃３ｂの軸方向すくい角θ１は０°であってもよく、すなわち主切刃３ｂの軸方向すくい角θ１は、０°〜４０°の範囲であればよい。 That is, if the axial rake angles θ1 and θ2 of the main cutting blade 3b and the secondary cutting blade 3c are larger on the conformal side than within the above range, the blade angle of the secondary cutting blade 3c becomes too small, resulting in chipping or chipping. On the other hand, if it is larger on the negative angle side than within the above range, the cutting resistance may increase. The axial rake angle θ1 of the main cutting edge 3b may be 0 °, that is, the axial rake angle θ1 of the main cutting edge 3b may be in the range of 0 ° to 40 °.

ところで、このようなドリルを製造する場合には、まず切刃３の軸方向すくい角を主切刃３ｂの軸方向すくい角θ１に合わせた通常のドリルを製造した後に、このドリルの副切刃３ｃの部分にだけドリル回転方向Ｔ側から見て副すくい面６ｃを研削によって研ぎ付けることにより、この副すくい面６ｃと先端逃げ面４との交差稜線部に副切刃３ｃを形成すればよい。 By the way, in the case of manufacturing such a drill, first, after manufacturing a normal drill in which the axial rake angle of the cutting edge 3 is matched with the axial rake angle θ1 of the main cutting edge 3b, the secondary cutting edge of this drill is manufactured. By sharpening the secondary rake face 6c when viewed from the drill rotation direction T side only on the portion 3c by grinding, the secondary cutting edge 3c may be formed at the intersecting ridgeline portion between the secondary rake face 6c and the tip flank surface 4. ..

そして、このような場合に、本実施形態では、副すくい面６ｃがドリル回転方向Ｔ側から見て三角形状に形成されているので、副すくい面６ｃを研ぎ付ける際の面積が小さくて済み、容易に副切刃３ｃの軸方向すくい角θ２を主切刃３ｂの軸方向すくい角θ１よりも正角側に大きくすることができる。 In such a case, in the present embodiment, since the secondary rake face 6c is formed in a triangular shape when viewed from the drill rotation direction T side, the area for sharpening the secondary rake face 6c can be small. The axial rake angle θ2 of the secondary cutting edge 3c can be easily made larger on the conformal side than the axial rake angle θ1 of the main cutting edge 3b.

ただし、本実施形態では、このように副すくい面６ｃがドリル回転方向Ｔ側から見て三角形状に形成されているが、四角形状に形成されていてもよい。この場合には、例えば図４および図５に示す本発明の第２の実施形態や、図６に示す第３の実施形態のように、ドリル回転方向Ｔ側から見て副すくい面６ｃが略一定の幅Ｗで延びる四角形（略平行四辺形）状に形成されていてもよい。このような第２、第３の実施形態でも、第１の実施形態と同様の効果を得ることができる。なお、これら第２、第３の実施形態や、後述する第４〜第６の実施形態でも、第１の実施形態と共通する部分には同一の符号を配して説明を省略する。 However, in the present embodiment, the secondary rake face 6c is formed in a triangular shape when viewed from the drill rotation direction T side in this way, but it may be formed in a quadrangular shape. In this case, as in the second embodiment of the present invention shown in FIGS. 4 and 5, and the third embodiment shown in FIG. 6, the secondary rake face 6c when viewed from the drill rotation direction T side is omitted. It may be formed in a quadrangle (substantially parallelogram) extending with a constant width W. Even in such second and third embodiments, the same effect as that of the first embodiment can be obtained. In the second and third embodiments and the fourth to sixth embodiments described later, the same reference numerals are given to the parts common to the first embodiment, and the description thereof will be omitted.

ここで、図４および図５に示す第２の実施形態では、副すくい面６ｃが、軸線Ｏに対する径方向の幅Ｗが軸線Ｏ方向の長さよりも大きくされた四角形状に形成されており、これによって切刃３のうち軸方向すくい角θ２が正角側に大きい副切刃３ｃを長くすることができるので、切削抵抗の低減を図ることができる。また、これとは逆に図６に示す第３の実施形態では、副すくい面６ｃが、軸線Ｏ方向の長さが軸線Ｏに対する径方向の幅Ｗよりも大きくされた四角形状に形成されており、切刃３に摩耗が生じたときに先端逃げ面４を研磨して新たな切刃３を研ぎ付ける再研磨を行うときに、再研磨量を大きく確保してドリル寿命を延長することができる。 Here, in the second embodiment shown in FIGS. 4 and 5, the secondary rake face 6c is formed in a quadrangular shape in which the width W in the radial direction with respect to the axis O is larger than the length in the axis O direction. As a result, the auxiliary cutting edge 3c having a large axial rake angle θ2 in the cutting edge 3 can be lengthened, so that the cutting resistance can be reduced. On the contrary, in the third embodiment shown in FIG. 6, the secondary rake face 6c is formed in a quadrangular shape in which the length in the axis O direction is larger than the radial width W with respect to the axis O. When the cutting edge 3 is worn, the tip flank surface 4 is polished and a new cutting edge 3 is sharpened. When re-polishing, a large amount of re-polishing can be secured to extend the drill life. can.

また、これら第１〜第３の実施形態では、副すくい面６ｃが主すくい面６ｂに対してドリル回転方向Ｔとは反対側に凹んだ凹面状に形成されて、副切刃３ｃは軸線Ｏ方向先端側から見て主切刃３ｂよりもドリル回転方向Ｔとは反対側に位置するように延びている。このため、上述のように通常のドリルを製造した後に、副すくい面６ｃを研削によって研ぎ付けることにより、容易に副切刃３ｃの軸方向すくい角θ２を主切刃３ｂの軸方向すくい角θ１よりも大きくすることができる。 Further, in these first to third embodiments, the secondary rake face 6c is formed in a concave shape recessed on the side opposite to the drill rotation direction T with respect to the main rake face 6b, and the secondary cutting edge 3c is formed on the axis O. It extends so as to be located on the side opposite to the drill rotation direction T from the main cutting edge 3b when viewed from the tip side in the direction. Therefore, by sharpening the secondary rake face 6c by grinding after manufacturing a normal drill as described above, the axial rake angle θ2 of the secondary cutting edge 3c can be easily changed to the axial rake angle θ1 of the main cutting edge 3b. Can be larger than.

ただし、このように副切刃３ｃを軸線Ｏ方向先端側から見て主切刃３ｂよりもドリル回転方向Ｔとは反対側に延びるように形成するのではなく、ドリル本体１を製造する際に、主すくい面６ｂの外周端部にドリル回転方向Ｔに突出する凸部を形成しておき、この凸部のドリル回転方向Ｔを向く壁面に副すくい面６ｃを形成して先端逃げ面４との交差稜線部に、主切刃３ｂの軸方向すくい角θ１よりも正角側に大きな軸方向すくい角θ２の副切刃３ｃを形成してもよい。 However, instead of forming the secondary cutting edge 3c so as to extend from the main cutting edge 3b to the side opposite to the drill rotation direction T when viewed from the tip side in the axis O direction in this way, when manufacturing the drill body 1. A convex portion protruding in the drill rotation direction T is formed at the outer peripheral end of the main rake surface 6b, and a sub rake surface 6c is formed on the wall surface of the convex portion facing the drill rotation direction T to form a tip flank surface 4 and A sub-cutting edge 3c having an axial rake angle θ2 larger than the axial rake angle θ1 of the main cutting edge 3b may be formed on the intersecting ridge line portion of the above.

また、第１〜第３の実施形態と同様に主すくい面６ｂの外周端部に主すくい面６ｂに対してドリル回転方向Ｔとは反対側に凹む凹面状の副すくい面６ｃを形成する場合でも、主すくい面６ｂに対して副すくい面６ｃが段差等を介して不連続となっていれば、副切刃３ｃは軸線Ｏ方向先端側から見て主切刃３ｂと一直線状に延びるように形成されていてもよい。 Further, as in the first to third embodiments, when a concave sub-rake face 6c that is recessed in the direction opposite to the drill rotation direction T is formed at the outer peripheral end of the main rake face 6b with respect to the main rake face 6b. However, if the secondary rake face 6c is discontinuous with the main rake face 6b via a step or the like, the secondary cutting edge 3c extends in a straight line with the main cutting edge 3b when viewed from the tip side in the O-direction of the axis. It may be formed in.

さらに、上記第１〜第３の実施形態では、主切刃３ｂと副切刃３ｃとが軸線Ｏ方向先端側から見て段差をもっていて、この副切刃３ｃと主切刃３ｂの間の段差部には軸線Ｏ方向先端側から見て曲線状をなす接続部３ｄが形成されている。このため、上述のように副切刃３ｃを軸線Ｏ方向先端側から見て主切刃３ｂと平行とすることができて、副切刃３ｃの径方向すくい角を主切刃３ｂの径方向すくい角に対して大きく変化させずに済むので、切屑の流出方向が主切刃３ｂと副切刃３ｃで異なる方向となるのを抑制することができるとともに、段差部（接続部３ｄ）が鋭くなって欠けが生じたりするのを防ぐことが可能となる。 Further, in the first to third embodiments, the main cutting edge 3b and the auxiliary cutting edge 3c have a step when viewed from the tip side in the axis O direction, and the step between the secondary cutting edge 3c and the main cutting edge 3b. A connecting portion 3d having a curved shape when viewed from the tip side in the O-direction of the axis is formed in the portion. Therefore, as described above, the secondary cutting edge 3c can be parallel to the main cutting edge 3b when viewed from the tip side in the axis O direction, and the radial rake angle of the secondary cutting edge 3c can be set in the radial direction of the main cutting edge 3b. Since it is not necessary to make a large change with respect to the rake angle, it is possible to prevent the outflow direction of chips from being different between the main cutting edge 3b and the secondary cutting edge 3c, and the stepped portion (connecting portion 3d) is sharp. It is possible to prevent chipping from occurring.

なお、これら第１〜第３の実施形態のように、主切刃３ｂと副切刃３ｃとが軸線Ｏ方向先端側から見て段差部を介して連なるように形成するのではなく、図７に示す第４の実施形態のように、副切刃３ｃを軸線Ｏ方向先端側から見て主切刃３ｂと折れ線状に連なってドリル回転方向Ｔとは反対側に延びていたり、図８に示す第５の実施形態のように、副切刃３ｃを軸線Ｏ方向先端側から見て主切刃３ｂに接する凸曲線状に形成されてドリル回転方向Ｔとは反対側に延びていたりしてもよい。 It should be noted that the main cutting edge 3b and the sub cutting edge 3c are not formed so as to be continuous with each other via the stepped portion when viewed from the tip side in the O-direction of the axis as in the first to third embodiments. As in the fourth embodiment shown in FIG. 8, the secondary cutting edge 3c is connected to the main cutting edge 3b in a curved line when viewed from the tip side in the axis O direction and extends in the direction opposite to the drill rotation direction T, or is shown in FIG. As in the fifth embodiment shown, the secondary cutting edge 3c is formed in a convex curve shape in contact with the main cutting edge 3b when viewed from the tip side in the O-direction of the axis, and extends in the direction opposite to the drill rotation direction T. May be good.

このような第４、第５の実施形態によれば、副切刃３ｃと主切刃３ｂの間に、第１〜第３の実施形態のような段差部（接続部３ｄ）が形成されることがなくなるので、切刃３の欠けを一層確実に防ぐことができる。また、特に第４の実施形態では、主切刃３ｂと副切刃３ｃによって生成される切屑が段差部で分断されることもなくなるので、分断された切屑同士が絡まることによって切屑詰まりが生じるのも防ぐことができる。 According to the fourth and fifth embodiments, a step portion (connecting portion 3d) as in the first to third embodiments is formed between the sub cutting edge 3c and the main cutting edge 3b. Since this is not the case, it is possible to more reliably prevent the cutting edge 3 from being chipped. Further, particularly in the fourth embodiment, since the chips generated by the main cutting blade 3b and the secondary cutting blade 3c are not separated at the step portion, the divided chips are entangled with each other, resulting in chip clogging. Can also be prevented.

一方、図９に示す第６の実施形態のように、副切刃３ｃは、軸線Ｏ方向先端側から見て主切刃３ｂからドリル回転方向Ｔとは反対側に凹む凹曲線状に形成されていてもよい。このような第６の実施形態によれば、切屑は主切刃３ｂと副切刃３ｃとで分断されて生成されることになるが、副切刃３ｃによって生成された切屑は凹曲線状の副切刃３ｃに沿ってドリル本体１の内周側に流れ出ることになるので、加工穴の内周面が切屑によって傷付けられるのを防ぐことができる。 On the other hand, as in the sixth embodiment shown in FIG. 9, the auxiliary cutting edge 3c is formed in a concave curved shape recessed from the main cutting edge 3b to the side opposite to the drill rotation direction T when viewed from the tip side in the axis O direction. You may be. According to such a sixth embodiment, the chips are generated by being divided by the main cutting edge 3b and the auxiliary cutting edge 3c, but the chips generated by the auxiliary cutting edge 3c have a concave curve shape. Since it flows out to the inner peripheral side of the drill body 1 along the secondary cutting edge 3c, it is possible to prevent the inner peripheral surface of the machined hole from being damaged by chips.

次に、本発明の実施例を挙げて、本発明の効果について説明する。本実施例では、上述した第１の実施形態に基づき、切刃３の直径Ｄが１／４ｉｎｃｈ（６．３５ｍｍ）、主切刃３ｂの軸方向すくい角θ１が３０°、副切刃３ｃの軸方向すくい角θ２が４０°、副切刃３ｃの軸線Ｏに対する径方向の幅Ｗが切刃３の直径Ｄに対して０．１２×Ｄのドリルを製造した。 Next, the effect of the present invention will be described with reference to examples of the present invention. In this embodiment, the diameter D of the cutting edge 3 is 1/4 inch (6.35 mm), the axial rake angle θ1 of the main cutting edge 3b is 30 °, and the secondary cutting edge 3c is based on the first embodiment described above. A drill having an axial rake angle θ2 of 40 ° and a width W of the auxiliary cutting edge 3c in the radial direction with respect to the axis O of 0.12 × D with respect to the diameter D of the cutting edge 3 was manufactured.

また、この実施例に対する比較例として、副切刃３ｃおよび副すくい面６ｃが形成されていないこと以外は実施例と同じドリルも製造した。なお、これら実施例のドリルと比較例のドリルのドリル本体１の表面には、ダイヤモンドコーティングを施してある。 Further, as a comparative example with respect to this example, the same drill as in the example was manufactured except that the secondary cutting edge 3c and the secondary rake face 6c were not formed. The surface of the drill body 1 of the drills of these examples and the drills of the comparative examples is coated with diamond.

そして、これら実施例のドリルと比較例のドリルを用いて、厚さ１０ｍｍのＣＦＲＰと厚さ５ｍｍのアルミニウム板材とを積層した積層材に、まず切削速度１００ｍ／ｍｉｎ、送り速度０．０２ｍｍ／ｒｅｖの条件でノンステップ加工により貫通穴を同数ずつ形成する穴明け加工を行い、その際のバリの高さを測定した。なお、この穴明け加工の際には、クーラント孔１ａから圧縮空気を噴出した。 Then, using the drills of these examples and the drills of the comparative examples, first, a cutting speed of 100 m / min and a feed speed of 0.02 mm / rev are applied to a laminated material obtained by laminating a CFRP having a thickness of 10 mm and an aluminum plate material having a thickness of 5 mm. Under the above conditions, drilling was performed to form the same number of through holes by non-step processing, and the height of burrs at that time was measured. During this drilling process, compressed air was ejected from the coolant hole 1a.

その結果、比較例のドリルによる穴明け加工では、バリの高さは０．０１ｉｎｃｈ〜０．０１５ｉｎｃｈであったのに対して、実施例のドリルによる穴明け加工では、バリの高さは、バリが発生していないものも含めて０．０１ｉｎｃｈ以下であった。この結果により、本発明によれば、上述のようにバリの発生を確実に抑制することが可能であることが分かる。なお、これら実施例のドリルおよび比較例のドリルでは、切刃３の欠損やチッピングは認められなかった。 As a result, the height of the burr was 0.01 inch to 0.015 inch in the drilling process of the comparative example, whereas the burr height was the burr in the drilling process of the example. It was 0.01 inch or less including those in which. From this result, it can be seen that according to the present invention, it is possible to reliably suppress the occurrence of burrs as described above. In the drills of these examples and the drills of the comparative examples, no chipping or chipping of the cutting edge 3 was observed.

次に、これら実施例のドリルと比較例のドリルを用いて、上記と同じ積層材に、切削速度は１００ｍ／ｍｉｎのまま、送り速度を上記条件の５倍の０．１０ｍｍ／ｒｅｖとした高能率条件で、同じくノンステップ加工により貫通穴を同数ずつ形成する穴明け加工を行い、その際のバリの高さを測定した。 Next, using the drills of these examples and the drills of the comparative example, the same laminated lumber as above was used, and the cutting speed was kept at 100 m / min, and the feed rate was set to 0.10 mm / rev, which was five times the above conditions. Under efficiency conditions, the same number of through holes were drilled by non-step processing, and the height of burrs at that time was measured.

その結果、比較例のドリルによる穴明け加工では、バリの高さは０．０１５ｉｎｃｈ〜０．０２ｉｎｃｈと上記の場合よりも大きくなっていたのに対して、実施例のドリルによる穴明け加工では、バリの高さは、上記と同じくバリが発生していないものも含めて０．０１ｉｎｃｈ以下であった。この結果により、本発明によれば、上述のような高能率条件における穴明け加工においても、バリの発生を確実に抑制することが可能であることが分かる。 As a result, in the drilling with the drill of the comparative example, the height of the burr was 0.015 inch to 0.02 inch, which was larger than the above case, whereas in the drilling with the drill of the example, the height of the burr was larger than that in the above case. The height of the burrs was 0.01 inch or less, including those without burrs as described above. From this result, it can be seen that according to the present invention, it is possible to reliably suppress the generation of burrs even in the drilling process under the above-mentioned high efficiency conditions.

１ドリル本体
１ａクーラント孔
２切刃部
３切刃
３ａシンニング刃
３ｂ主切刃
３ｃ副切刃
３ｄ接続部
４先端逃げ面
４ａ第１先端逃げ面
４ｂ第２先端逃げ面
５切屑排出溝
６すくい面
６ａシンニングすくい面
６ｂ主すくい面
６ｃ副すくい面
７ａマージン部
７ｂ外周逃げ面
８シンニング部
Ｏドリル本体１の軸線
Ｔドリル回転方向
θ１主切刃３ｂの軸方向すくい角
θ２副切刃３ｃの軸方向すくい角
Ｗ副切刃３ｃの軸線Ｏに対する径方向の幅
Ｄ切刃３の直径 1 Drill body 1a Coolant hole 2 Cutting edge part 3 Cutting edge 3a Thinning blade 3b Main cutting edge 3c Secondary cutting edge 3d Connection part 4 Tip flank surface 4a 1st tip flank surface 4b 2nd tip flank surface 5 Chip discharge groove 6 Scoop surface 6a Thinning rake surface 6b Main rake surface 6c Sub rake surface 7a Margin part 7b Outer peripheral relief surface 8 Thinning part O Drill body 1 axis T Drill rotation direction θ1 Main cutting edge 3b axial rake angle θ2 Secondary cutting edge 3c axial direction Puncture angle W Width of the secondary cutting edge 3c in the radial direction with respect to the axis O D Diameter of the cutting edge 3

Claims

軸線回りにドリル回転方向に回転させられる上記軸線を中心とした軸状のドリル本体の先端部外周に切屑排出溝が形成され、この切屑排出溝の上記ドリル回転方向を向く壁面と上記ドリル本体の先端逃げ面との交差稜線部に切刃が形成されたドリルであって、
上記切刃は、上記ドリル本体の内周側に形成される主切刃と、この主切刃のドリル本体外周側に連なる副切刃とを備え、
上記副切刃の軸方向すくい角が上記主切刃の軸方向すくい角よりも正角側に大きいことを特徴とするドリル。 A chip discharge groove is formed on the outer periphery of the tip of the axial drill body centered on the axis that is rotated in the drill rotation direction around the axis, and the wall surface of the chip discharge groove facing the drill rotation direction and the drill body A drill with a cutting edge formed at the intersection ridge with the tip flank.
The cutting edge includes a main cutting edge formed on the inner peripheral side of the drill body and a sub cutting edge connected to the outer peripheral side of the drill body of the main cutting edge.
A drill characterized in that the axial rake angle of the secondary cutting edge is larger on the conformal side than the axial rake angle of the main cutting edge.

上記副切刃の上記軸線に対する径方向の幅が、上記切刃の直径Ｄの０．０５×Ｄ〜０．２０×Ｄの範囲内とされていることを特徴とする請求項１に記載のドリル。 The first aspect of the present invention, wherein the width of the secondary cutting edge in the radial direction with respect to the axis is within the range of 0.05 × D to 0.20 × D of the diameter D of the cutting edge. Drill.

上記副切刃の軸方向すくい角が１０°〜５０°の範囲内とされるとともに、上記主切刃の軸方向すくい角が０°〜４０°の範囲内とされていることを特徴とする請求項１または請求項２に記載のドリル。 The axial rake angle of the secondary cutting edge is within the range of 10 ° to 50 °, and the axial rake angle of the main cutting edge is within the range of 0 ° to 40 °. The drill according to claim 1 or 2.

上記副切刃のすくい面は、上記ドリル回転方向側から見て、三角形状または四角形状に形成されていることを特徴とする請求項１から請求項３のうちいずれか一項に記載のドリル。 The drill according to any one of claims 1 to 3, wherein the rake face of the secondary cutting edge is formed in a triangular shape or a quadrangular shape when viewed from the drill rotation direction side. ..

上記副切刃のすくい面は、上記ドリル回転方向側から見て、上記軸線に対する径方向の幅が上記軸線方向の長さよりも大きくされた四角形状に形成されていることを特徴とする請求項１から請求項３のうちいずれか一項に記載のドリル。 A claim that the rake face of the secondary cutting edge is formed in a quadrangular shape in which the width in the radial direction with respect to the axis is larger than the length in the axis direction when viewed from the drill rotation direction side. The drill according to any one of claims 1 to 3.

上記副切刃のすくい面は、上記ドリル回転方向側から見て、上記軸線方向の長さが上記軸線に対する径方向の幅よりも大きくされた四角形状に形成されていることを特徴とする請求項１から請求項３のうちいずれか一項に記載のドリル。 A claim characterized in that the rake face of the secondary cutting edge is formed in a quadrangular shape in which the length in the axial direction is larger than the radial width with respect to the axis when viewed from the drill rotation direction side. The drill according to any one of claims 1 to 3.

上記副切刃は上記軸線方向先端側から見て上記主切刃よりも上記ドリル回転方向とは反対側に延びていることを特徴とする請求項１から請求項６のうちいずれか一項に記載のドリル。 The sub-cutting edge is any one of claims 1 to 6, characterized in that the sub-cutting edge extends from the main cutting edge to the side opposite to the drill rotation direction when viewed from the tip side in the axial direction. Described drill.

上記主切刃と上記副切刃とは上記軸線方向先端側から見て段差をもっているとともに、上記副切刃と上記主切刃の間の段差部には上記軸線方向先端側から見て曲線状をなす接続部が形成されていることを特徴とする請求項７に記載のドリル。 The main cutting blade and the sub cutting blade have a step when viewed from the tip side in the axial direction, and the step portion between the sub cutting blade and the main cutting blade has a curved shape when viewed from the tip side in the axial direction. The drill according to claim 7, wherein a connecting portion is formed.

上記副切刃は、上記軸線方向先端側から見て上記主切刃と折れ線状に連なっていることを特徴とする請求項７に記載のドリル。 The drill according to claim 7, wherein the secondary cutting edge is connected to the main cutting edge in a polygonal line when viewed from the tip side in the axial direction.

上記副切刃は、上記軸線方向先端側から見て上記主切刃に接する凸曲線状に形成されていることを特徴とする請求項７に記載のドリル。 The drill according to claim 7, wherein the secondary cutting edge is formed in a convex curve shape in contact with the main cutting edge when viewed from the tip side in the axial direction.

上記副切刃は、上記軸線方向先端側から見て上記主切刃から上記ドリル回転方向とは反対側に凹む凹曲線状に形成されていることを特徴とする請求項７に記載のドリル。 The drill according to claim 7, wherein the secondary cutting edge is formed in a concave curved shape that is recessed from the main cutting edge to the side opposite to the drill rotation direction when viewed from the tip side in the axial direction.