JP2012187675A

JP2012187675A - Twist drill

Info

Publication number: JP2012187675A
Application number: JP2011054239A
Authority: JP
Inventors: Kazuhisa Murata; 和久村田; Hiroshi Ikeuchi; 寛池内; Yasushi Ota; 康史大田
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2011-03-11
Filing date: 2011-03-11
Publication date: 2012-10-04

Abstract

PROBLEM TO BE SOLVED: To prevent a work material from being pulled to the rear end side of a drill body when drilling a through-hole, or a drill from being drawn to the work material, or the work material from being pulled to the rear end side of the drill body upon pulling the tip end part of the drill body from the through hole, in the case where a twist drill is attached to a drilling machine or a hand held electric drill for drilling a through-hole in a plate material or the like.SOLUTION: Along the outer periphery of the tip end part of the drill body 1 which is made to rotate, in a direction of the drill's rotation, around the axis line O, a chip discharge groove 4 is formed that is twisted spirally around the axis line O, while a cutting blade 5 is formed at the tip end side ridge line part of the wall surface directed in a drill rotation direction of the chip discharge groove 4. In addition, a relieving surface 8 of the drill body 1 that extends from the outer peripheral side ridge line part M of the foregoing wall surface toward the rear side in the drill's rotation direction has a margin part 9 formed thereon, which, at its rear end part, has its width in the peripheral direction gradually reduced as it extends toward the rear end side in the direction of the axis line O, with the width being intended to be reduced to zero within the range where the chip discharge groove 4 is formed.

Description

本発明は、ドリル本体の先端部外周に螺線状に捩れた切屑排出溝が形成されて、この切屑排出溝のドリル回転方向を向く壁面の先端側稜線部には切刃が、またこの壁面の外周側稜線部からドリル回転方向後方側に延びるドリル本体の二番取り面にはマージン部が形成されたツイストドリルに関するものである。 In the present invention, a chip discharge groove twisted in a spiral shape is formed on the outer periphery of the tip end portion of the drill body, and a cutting edge is formed on the tip side ridge line portion of the wall surface of the chip discharge groove facing the drill rotation direction. This invention relates to a twist drill in which a margin portion is formed on the second surface of the drill body extending from the outer peripheral side ridge line portion to the rear side in the drill rotation direction.

このようなツイストドリルをボール盤に取り付けて比較的薄い板材に貫通孔をあける際、被削材である板材はバイス等に固定するのが一般的であるが、バイス自体が固定されていない場合があり、そのような場合にはドリルが被削材を貫通したときに被削材が螺旋状の切屑排出溝に沿ってバイスごとドリル本体の後端側に引き寄せられそうになることがある。また、手持ちの電気ドリルに取り付けて使用する場合には、ドリルが被削材側に引き込まれそうになることもある。 When such a twist drill is attached to a drilling machine and a through hole is made in a relatively thin plate material, the plate material which is a work material is generally fixed to a vise or the like, but the vise itself may not be fixed. In such a case, when the drill penetrates the work material, the work material is likely to be drawn to the rear end side of the drill body along with the spiral chip discharge groove together with the vice. Moreover, when using it by attaching it to a hand-held electric drill, the drill may be drawn into the work material side.

これは、一般的なツイストドリルではドリル本体の二番取り面に形成されるマージン部が切屑排出溝の全長に亙って形成されているためであり、すなわちドリルの切刃が被削材を貫通した後はドリルと被削材とがこのマージン部で接触しているだけであるので、通常はドリル本体の後端側に向けてドリル回転方向の後方側に捩れる切屑排出溝およびマージン部に案内されるようにして、被削材がドリル本体後端側に引き寄せられたり、ドリルが被削材側に引き込まれたりするのである。 This is because in a general twist drill, the margin portion formed on the second face of the drill body is formed over the entire length of the chip discharge groove, that is, the cutting edge of the drill removes the work material. After drilling through, the drill and work material are only in contact with this margin, so usually the chip discharge groove and the margin that twist to the rear side in the drill rotation direction toward the rear end of the drill body As a result, the work material is drawn toward the rear end side of the drill body, or the drill is drawn into the work material side.

ここで、このようなツイストドリルにおいては、特許文献１、２に記載されているように、ドリル本体の切刃が形成される先端部の外径よりも後端部の外径を僅かに一段小さくした、いわゆるアンダーカットタイプのドリルが知られている。そして、このようなアンダーカットタイプのドリルを上述のような板材の貫通孔明け加工に用いると、外径の大きな先端部が被削材から抜け出たところで、後端部の二番取り面にマージン部が形成されていても貫通孔とは接触しなくなるので、被削材がドリル本体後端側に引き寄せられたり、ドリルが被削材側に引き込まれたりするのを防ぐことができる。 Here, in such a twist drill, as described in Patent Documents 1 and 2, the outer diameter of the rear end is slightly higher than the outer diameter of the front end where the cutting edge of the drill body is formed. A so-called undercut type drill which is small is known. When such an undercut type drill is used for the drilling of the plate material as described above, a margin is formed on the second surface of the rear end portion when the tip portion having a large outer diameter comes out of the work material. Even if the portion is formed, it does not come into contact with the through hole, so that it is possible to prevent the work material from being drawn toward the rear end side of the drill body and the drill from being drawn into the work material side.

特開２００４−１２２２８８号公報JP 2004-122288 A 特開２００４−２３７３７５号公報JP 2004-237375 A

しかしながら、このようなアンダーカットタイプのドリルは、上述のように大径の先端部に対して後端部が外径を一段小さくするように段差をもって形成されているため、被削材を貫通したドリル本体の先端部を貫通孔から引き抜く際に、この段差が被削材に当たって被削材がドリル本体ごとその後端側に引き寄せられたりする事態が生じるおそれがある。特に、手持ちの電気ドリルに取り付けて貫通孔明けをする際には、ドリル本体をその軸線に沿って正確に引き抜くことが難しいので、このような事態が生じる可能性が高い。 However, such an undercut type drill penetrates the work material because the rear end portion is formed with a step so as to make the outer diameter one step smaller than the large diameter tip portion as described above. When the front end of the drill body is pulled out from the through hole, there is a possibility that the step hits the work material and the work material is pulled together with the drill body toward the rear end. In particular, when drilling a through hole by attaching it to a hand-held electric drill, it is difficult to accurately pull out the drill body along its axis, so this situation is likely to occur.

本発明は、このような背景の下になされたもので、ボール盤や手持ちの電気ドリルに取り付けて板材等の被削材に貫通孔を明けるような場合に、ドリルが被削材を貫通したときに被削材がドリル本体後端側に引き寄せられたり、ドリルが被削材側に引き込まれたりすることがないのは勿論、こうして被削材を貫通したドリル本体の先端部を貫通孔から引き抜く際にも被削材がドリル本体後端側に引き寄せられるような事態が生じるのを防ぐことが可能なツイストドリルを提供することを目的としている。 The present invention is made under such a background, and when the drill penetrates the work material when it is attached to a drilling machine or a hand held electric drill and a through hole is made in the work material such as a plate material, etc. Of course, the work material will not be pulled to the rear end side of the drill body and the drill will not be drawn to the work material side, so the tip of the drill body that penetrates the work material is pulled out from the through hole. In particular, it is an object of the present invention to provide a twist drill capable of preventing a situation in which a work material is drawn toward the rear end side of the drill body.

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ドリル本体の先端部外周に上記軸線回りに螺旋状に捩れる切屑排出溝が形成され、この切屑排出溝のドリル回転方向を向く壁面の先端側稜線部に切刃が形成されるとともに、上記壁面の外周側稜線部から上記ドリル回転方向後方側に延びる上記ドリル本体の二番取り面にはマージン部が形成されており、このマージン部は、その後端部において上記軸線方向後端側に向かうに従い周方向の幅が漸次減少して、上記切屑排出溝が形成されている範囲で上記幅が０となるようにされていることを特徴とする。 In order to solve the above-mentioned problems and achieve such an object, the present invention provides a chip discharge groove that spirally twists around the axis on the outer periphery of the tip of the drill body that is rotated in the direction of drill rotation around the axis. And a cutting edge is formed on the tip side ridge line portion of the wall surface facing the drill rotation direction of the chip discharge groove, and the drill main body extends from the outer peripheral side ridge line portion of the wall surface to the rear side in the drill rotation direction. A margin portion is formed on the winding surface, and the margin portion gradually decreases in the circumferential direction toward the rear end side in the axial direction at the rear end portion, and the chip discharge groove is formed. In the range, the width is set to be zero.

このように構成されたツイストドリルでは、二番取り面に形成されたマージン部が、切屑排出溝が形成されている範囲でドリル本体の周方向の幅が０となるようにされており、すなわちマージン部が切屑排出溝の全長の途中までで途切れて、これよりも後端側はマージン部の外径よりも小径の二番取り面とされているので、このマージン部が形成された先端部が被削材の貫通孔から抜け出たところでドリル本体は被削材と接触しなくなる。このため、こうしてドリルが被削材を貫通したときに被削材がドリル本体後端側に引き寄せられたり、ドリルが被削材側に引き込まれたりするのを防ぐことができる。 In the twist drill configured as described above, the margin portion formed on the second face is configured such that the circumferential width of the drill body is zero in a range where the chip discharge groove is formed, The margin part is interrupted in the middle of the entire length of the chip discharge groove, and the rear end side is a second surface having a smaller diameter than the outer diameter of the margin part. When the drill comes out of the through hole of the work material, the drill body does not come into contact with the work material. For this reason, when the drill penetrates the work material in this way, it is possible to prevent the work material from being drawn toward the rear end side of the drill body and the drill from being drawn into the work material side.

その一方で、このマージン部は、このように周方向の幅が０になるその後端部においては、ドリル本体の軸線方向後端側に向かうに従いこの周方向の幅が漸次減少して幅が０になるようにされており、逆にこの幅が０になる位置から先端側に向けては漸次幅広となるようにされる。従って、被削材を貫通したドリルを引き抜く際には、まずこの幅が０になる位置が被削材に点接触し、次いでマージン部が貫通孔との接触幅を徐々に拡げながらドリル本体の先端部が引き抜かれることになるので、段差が当たる場合のように被削材がドリル本体後端側に引き寄せられるのを防ぐことができる。 On the other hand, the marginal portion gradually decreases in the circumferential direction toward the rear end side in the axial direction of the drill body at the rear end portion where the circumferential width becomes 0, and the width becomes 0. On the contrary, the width gradually increases from the position where the width becomes 0 toward the tip side. Therefore, when pulling out the drill that penetrates the work material, the position where the width becomes zero first makes point contact with the work material, and then the margin portion of the drill body gradually increases the contact width with the through hole. Since the tip portion is pulled out, it is possible to prevent the work material from being drawn toward the rear end side of the drill body as in the case where a step hits.

以上説明したように、本発明によれば、ドリル本体が被削材を貫通したときに被削材がドリル本体後端側に引き寄せられたりドリルが被削材側に引き込まれたりするのを防ぐことができるとともに、こうして被削材を貫通したドリルを引き抜く際にも被削材がドリルに当たって後端側に引き寄せられるのを防ぐことができ、ボール盤や手持ちの電気ドリルに取り付けて被削材に貫通孔明け加工を行う場合に円滑かつ安定した孔明け作業を促すことができる。 As described above, according to the present invention, when the drill body penetrates the work material, the work material is prevented from being pulled toward the rear end side of the drill body and the drill is not pulled into the work material side. In this way, when pulling out a drill that penetrates the work material, it can be prevented that the work material hits the drill and is pulled to the rear end side, and can be attached to a drilling machine or a hand-held electric drill. When performing through-drilling, smooth and stable drilling can be promoted.

本発明の第１の実施形態を示す側面図である。It is a side view which shows the 1st Embodiment of this invention. 図１に示す実施形態のドリル本体先端部の拡大側面図である。It is an enlarged side view of the drill main body front-end | tip part of embodiment shown in FIG. 図１に示す実施形態の拡大正面図である。It is an enlarged front view of embodiment shown in FIG. 本発明の第２の実施形態を示すドリル本体先端部の拡大側面図である。It is an expanded side view of the drill main body front-end | tip part which shows the 2nd Embodiment of this invention. 本発明の第３の実施形態を示すドリル本体先端部の拡大側面図である。It is an expanded side view of the drill main body front-end | tip part which shows the 3rd Embodiment of this invention. 本発明の第４の実施形態を示すドリル本体先端部の拡大側面図である。It is an expanded side view of the drill main body front-end | tip part which shows the 4th Embodiment of this invention. 本発明の第５の実施形態を示すドリル本体先端部の拡大側面図である。It is an expanded side view of the drill main body front-end | tip part which shows the 5th Embodiment of this invention. 本発明の第６の実施形態を示すドリル本体先端部の拡大側面図である。It is an enlarged side view of the drill main body front-end | tip part which shows the 6th Embodiment of this invention. 本発明の第７の実施形態を示すドリル本体先端部の拡大側面図である。It is an expanded side view of the drill main body front-end | tip part which shows the 7th Embodiment of this invention.

図１ないし図３は、本発明の第１の実施形態を示すものである。本実施形態において、ドリル本体１は、高速度工具鋼や超硬合金等の硬質材料によって一体に形成されて、軸線Ｏを中心とした外形略円柱の軸状をなし、その後端部（図１において右側部分）は円柱状のままのシャンク部２とされて、このシャンク部２がボール盤や手持ちの電気ドリルの回転軸に取り付けられたチャックに把持されることによりドリル本体１は軸線Ｏ回りにドリル回転方向Ｔに回転させられつつ軸線Ｏ方向先端側に送り出され、先端部（図１において左側部分）に設けられた刃部３によって被削材の孔明け加工に使用される。 1 to 3 show a first embodiment of the present invention. In the present embodiment, the drill body 1 is integrally formed of a hard material such as high-speed tool steel or cemented carbide, and has a substantially cylindrical shaft shape with an axis O as the center, and a rear end portion (FIG. 1). The right shank portion 2 is a cylindrical shank portion 2, and the shank portion 2 is gripped by a chuck attached to a rotary shaft of a drilling machine or a hand-held electric drill so that the drill body 1 is rotated around the axis O. While being rotated in the drill rotation direction T, it is fed to the front end side in the axis O direction, and is used for drilling a work material by the blade portion 3 provided at the front end portion (left side portion in FIG. 1).

この刃部３においては、ドリル本体１の先端部外周に、上記軸線Ｏ方向後端側に向かうに従い該軸線Ｏ回りにドリル回転方向Ｔの後方側に螺旋状に捩れる一対の切屑排出溝４が軸線Ｏに関して１８０°回転対称に形成され、この切屑排出溝４のドリル回転方向Ｔを向く壁面の先端側稜線部に、該壁面の先端部をすくい面とする切刃５が形成されている。切刃５には、内周側の軸線Ｏ近傍から外周側に向かうに従い軸線Ｏ方向後端側に向かうように先端角が与えられ、また刃部３の先端面（ドリル本体１の先端面）は、切刃５からドリル回転方向Ｔの後方側に向かうに従い軸線Ｏ方向後端側に向かうように逃げ角が与えられた先端逃げ面６とされている。 In this blade portion 3, a pair of chip discharge grooves 4 that are spirally twisted around the axis O toward the rear side in the drill rotation direction T toward the rear end side in the axis O direction on the outer periphery of the tip of the drill body 1. Are formed symmetrically with respect to the axis O by 180 °, and a cutting edge 5 having a rake face at the tip end of the wall surface is formed at the tip ridge line portion of the wall surface facing the drill rotation direction T of the chip discharge groove 4. . The cutting edge 5 is provided with a tip angle so as to go to the rear end side in the axis O direction from the vicinity of the axis O on the inner circumference side toward the outer circumference, and the tip face of the blade section 3 (tip face of the drill body 1). Is a tip flank 6 provided with a clearance angle so as to go from the cutting edge 5 toward the rear side in the axis O direction as it goes backward in the drill rotation direction T.

一方、ドリル本体１の周方向においてこれらの切屑排出溝４の間の部分はランド部７とされ、このランド部７の外周面、すなわち切屑排出溝４のドリル回転方向Ｔを向く上記壁面の外周側稜線部Ｍから上記ドリル回転方向Ｔの後方側に延びる部分は、二番取り面（外周逃げ面）８とされている。この二番取り面８は、その外径が上記切刃５の外径よりも小さくされて、該切刃５により形成された加工穴の内周との間に間隔があけられるようにされており、ただしドリル本体１先端部においてこの二番取り面８には、該二番取り面８から外周側に凸となるようにされて切刃５と等しい外径を有するマージン部９が形成されている。 On the other hand, a portion between the chip discharge grooves 4 in the circumferential direction of the drill body 1 is a land portion 7, and the outer peripheral surface of the land portion 7, that is, the outer periphery of the wall surface facing the drill rotation direction T of the chip discharge groove 4. A portion extending from the side ridge line portion M to the rear side in the drill rotation direction T is a second picking surface (outer peripheral flank) 8. The outer surface of the second cutting surface 8 is made smaller than the outer diameter of the cutting blade 5 so as to be spaced from the inner periphery of the machining hole formed by the cutting blade 5. However, a margin 9 having an outer diameter equal to that of the cutting edge 5 is formed on the second picking surface 8 at the tip of the drill body 1 so as to protrude from the second picking surface 8 to the outer peripheral side. ing.

すなわち、このマージン部９は、その外周面が切刃５と等しい外径を有する円筒面上に位置するように形成されたものであって、この外周面から上記二番取り面８にかけての境界部１０は、図３に示すようにマージン部９の外周面と鈍角に曲折して交差するとともに二番取り面８には滑らかに接するように延びる平面状や凹曲面状、凸曲面状または段状をなして軸線Ｏからの径が漸次小さくなるようにされている。なお、ドリル本体１の引き抜き時に被削材が引き寄せられるのを確実に防ぐには、上記境界部１０は平面状または凹曲面状または凸曲面状とされるのが望ましい。また、マージン部９は、切屑排出溝４のドリル回転方向Ｔ側を向く壁面先端部の上記すくい面と先端逃げ面６とに交差するように形成されていて、これらすくい面と先端逃げ面６、およびマージン部９の外周面との交点が切刃５の外周端とされる。 That is, the margin portion 9 is formed so that the outer peripheral surface thereof is located on a cylindrical surface having an outer diameter equal to that of the cutting edge 5, and the boundary from the outer peripheral surface to the second picking surface 8. As shown in FIG. 3, the portion 10 bends and intersects with the outer peripheral surface of the margin portion 9 at an obtuse angle and extends in a flat shape, a concave curved surface shape, a convex curved surface shape or a step shape so as to smoothly touch the second picking surface 8. Thus, the diameter from the axis O is gradually reduced. In order to reliably prevent the work material from being attracted when the drill body 1 is pulled out, the boundary portion 10 is preferably flat, concave, or convex. The margin portion 9 is formed so as to intersect the rake face and the tip flank 6 at the tip of the wall surface facing the drill rotation direction T of the chip discharge groove 4, and the rake face and the tip flank 6. , And the intersection with the outer peripheral surface of the margin portion 9 is the outer peripheral end of the cutting blade 5.

そして、このマージン部９は、図１および図２に示すようにその後端部において軸線Ｏ方向後端側に向かうに従い周方向の幅が漸次減少して、切屑排出溝４が形成されている範囲でこの幅が０となるようにされている。すなわち、マージン部９の外周面と、この外周面と二番取り面８との上記境界部１０との交差稜線Ｌが、マージン部９の後端部においては軸線Ｏに垂直な平面上に延びることなく少なくとも該軸線Ｏ方向に向けて後端側に延びて、切屑排出溝４のドリル回転方向Ｔを向く壁面の上記外周側稜線部Ｍと交差するようにされている。 As shown in FIGS. 1 and 2, the margin portion 9 has a range in which the circumferential width gradually decreases toward the rear end side in the axis O direction at the rear end portion, and the chip discharge groove 4 is formed. This width is set to zero. That is, the intersection ridge line L between the outer peripheral surface of the margin portion 9 and the boundary portion 10 between the outer peripheral surface and the second picking surface 8 extends on a plane perpendicular to the axis O at the rear end portion of the margin portion 9. Without extending at least the rear end side in the direction of the axis O, and intersecting the outer peripheral side ridge line portion M of the wall surface of the chip discharge groove 4 facing the drill rotation direction T.

ここで、この第１の実施形態では、マージン部９は、先端逃げ面６のうちドリル回転方向Ｔ側（切刃５側）の部分のみでこの先端逃げ面６と交差するようにされていて、こうして先端逃げ面６と交差した先端縁からマージン部９全体が後端側に向かうに従い上述のように周方向の幅が漸次減少して、上記交差稜線Ｌが上記壁面の外周側稜線部Ｍと交差する交点Ｎでこの幅が０となるようにされている。さらに、本実施形態ではこの交差稜線Ｌは全長に亙って軸線Ｏに略平行に直線状に延びており、従って本実施形態におけるマージン部９の外周面は図２に示すように略三角形状を呈することになる。 Here, in the first embodiment, the margin portion 9 intersects the tip flank 6 only at the portion of the tip flank 6 on the drill rotation direction T side (cutting blade 5 side). As described above, the width in the circumferential direction gradually decreases as described above from the front end edge intersecting the front end flank 6 toward the rear end side, and the cross ridge line L becomes the outer peripheral side ridge line portion M of the wall surface. This width is set to be 0 at the intersection point N that intersects with. Further, in the present embodiment, the intersecting ridge line L extends linearly substantially in parallel with the axis O over the entire length, and therefore the outer peripheral surface of the margin portion 9 in the present embodiment is substantially triangular as shown in FIG. Will be presented.

なお、上記交差稜線Ｌとの交点Ｎから後端側に向けて上記外周側稜線部Ｍは、上記境界部１０と切屑排出溝４のドリル回転方向Ｔを向く上記壁面との交差稜線として、軸線Ｏからの径が漸次小さくなるように略直線状や凹曲線状、凸曲線状または段状に延びた後、二番取り面８と上記壁面との交差稜線として、この二番取り面８と等しい径で切屑排出溝４に沿って螺旋状に延びることになる。なお、上記と同様にドリル本体１の引き抜き時に被削材が引き寄せられるのを確実に防ぐには、交点Ｎから後端側に向けて上記外周側稜線部Ｍは、直線状または凹曲線状または凸曲線状をなして延びるのが望ましい。 The outer peripheral side ridge line portion M from the intersection N with the intersection ridge line L toward the rear end side is an axis line as an intersection ridge line between the boundary portion 10 and the wall surface facing the drill rotation direction T of the chip discharge groove 4. After extending in a substantially straight line shape, a concave curve shape, a convex curve shape or a step shape so that the diameter from O gradually decreases, the second picking surface 8 is used as an intersecting ridge line between the second picking surface 8 and the wall surface. It will extend spirally along the chip discharge groove 4 with the same diameter. In order to reliably prevent the work material from being drawn when the drill body 1 is pulled out in the same manner as described above, the outer peripheral side ridge line portion M from the intersection N toward the rear end side is linear or concave curved or It is desirable to extend in a convex curve shape.

このような構成のツイストドリルを上述のようにボール盤や手持ちの電気ドリルに取り付けて板材のような被削材に貫通孔を明けるときには、切刃５が被削材に食い付いてから貫通するまでの間は、この切刃５と等しい外径とされたマージン部９が加工穴の内周に摺接しているため、刃部３の先端部が軸線Ｏに沿って案内されることになり、真円度や直進度の高い加工穴を形成することができる。 When the twist drill having such a structure is attached to a drilling machine or a hand-held electric drill as described above to make a through hole in a work material such as a plate material, the cutting blade 5 bites into the work material until it penetrates. Since the margin portion 9 having an outer diameter equal to that of the cutting blade 5 is in sliding contact with the inner periphery of the machining hole, the tip portion of the blade portion 3 is guided along the axis O, Machining holes with high roundness and straightness can be formed.

また、マージン部９は切屑排出溝４が形成された範囲で周方向の幅がなくなって潰えているので、切刃５が被削材を貫通して貫通孔が形成され、さらにマージン部９もこの貫通孔を通り抜けた後は、この貫通孔と刃部３の二番取り面８との間に間隔が生じてドリル本体１と被削材とが接触しなくなる。従って、被削材が切屑排出溝４に沿ってドリル本体１の後端側に引き寄せられたり、手持ちの電気ドリルを用いたときにドリル本体１ごと被削材側に引き込まれたりすることはない。 Further, since the margin portion 9 is crushed because the circumferential width disappears in the range in which the chip discharge groove 4 is formed, the cutting blade 5 penetrates the work material and a through hole is formed. After passing through the through hole, a gap is generated between the through hole and the second surface 8 of the blade portion 3, and the drill body 1 and the work material are not in contact with each other. Therefore, the work material is not drawn toward the rear end side of the drill main body 1 along the chip discharge groove 4, or is not drawn into the work material side together with the drill main body 1 when a hand-held electric drill is used. .

そして、さらにこのようにマージン部９が貫通孔を通り抜けた後にドリル本体１をこの貫通孔から引き抜く際にも、マージン部９はその後端部において上記周方向の幅が後端側に向かうに従い漸次減少して０となるようにされており、こうしてドリル本体１を引き抜くときに貫通孔は、この幅が０となる上記交差稜線Ｌと外周側稜線部Ｍとの交点Ｎからドリル本体１のマージン部９と１つの二番取り面８について１点で接触し、徐々にマージン部９との周方向の接触幅が長くなるようにして引き抜かれることになる。 Further, when the drill body 1 is pulled out from the through hole after the margin portion 9 has passed through the through hole in this way, the margin portion 9 is gradually increased in the rear end portion as the circumferential width toward the rear end side. When the drill body 1 is pulled out in this way, the through-hole becomes a margin of the drill body 1 from the intersection N of the intersecting ridge line L and the outer peripheral ridge line part M when the width becomes 0. The portion 9 and the single second-handed surface 8 are brought into contact with each other at one point, and are gradually pulled out so that the circumferential contact width with the margin portion 9 becomes longer.

このため、上述したアンダーカットタイプのドリルを引き抜く場合のようにドリル本体の軸線に垂直な平面上に延びる段差が一気に被削材に接触して貫通孔の開口部周縁に引っ掛かりを生じるようなことがなく、ボール盤での孔明け加工の場合においてドリル本体１を引き抜く際に被削材が持ち上げられたり、手持ちドリルでの孔明け作業の場合において被削材が作業者側に引き寄せられたりするのを防ぐことができる。従って、上記構成のツイストドリルによれば、このような貫通孔明け加工を、円滑かつ安定して行うことが可能となる。 For this reason, a step extending on a plane perpendicular to the axis of the drill body, as in the case of pulling out the undercut type drill described above, comes into contact with the work material at a stretch and causes a catch at the periphery of the opening of the through hole. In the case of drilling with a drilling machine, the work material is lifted when the drill body 1 is pulled out, or in the case of drilling work with a hand-held drill, the work material is drawn to the operator side. Can be prevented. Therefore, according to the twist drill having the above-described configuration, it is possible to perform such a through-hole drilling process smoothly and stably.

なお、こうして形成されたマージン部９の図２に示す軸線Ｏ方向の長さＡ、すなわち切刃５の外周端となるマージン部９の外周面と先端逃げ面６および切屑排出溝４のドリル回転方向Ｔを向く上記壁面との交点と、この壁面の上記外周側稜線部Ｍと上記交差稜線Ｌとの交点Ｎとの軸線Ｏ方向の間隔は、これが長すぎると被削材の厚さによっては刃部３が被削材を貫通した後に軸線Ｏ方向後端側に被削材が引き寄せられてしまうおそれがあるので、切刃５の外径Ｄに対して２×Ｄ程度の長さまでとされるのが望ましい。 The length A of the margin portion 9 formed in this way in the direction of the axis O shown in FIG. 2, that is, the outer peripheral surface of the margin portion 9 serving as the outer peripheral end of the cutting blade 5, the tip flank 6 and the drill rotation of the chip discharge groove 4 The distance in the direction of the axis O between the intersection with the wall surface facing the direction T and the intersection N between the outer peripheral ridge line portion M and the intersection ridge line L of the wall surface is too long depending on the thickness of the work material. Since the work material may be drawn toward the rear end side in the axis O direction after the blade portion 3 penetrates the work material, the length is set to about 2 × D with respect to the outer diameter D of the cutting blade 5. Is desirable.

一方、このマージン部９の周方向の最大の幅は、これが小さすぎると上述のように切刃５が被削材に食い付いてから貫通するまでの間に刃部３を真っ直ぐ案内することができなくなるおそれがあるので、図３に示すように軸線Ｏ方向先端視におけるマージン部９の外周面の周方向の両端（本実施形態では切刃５の外周端と上記交差稜線Ｌまたは交点Ｎ）と軸線Ｏとを結ぶ直線の挟角αとして、２５°以上とされるのが望ましい。 On the other hand, if the marginal portion 9 has a maximum circumferential width that is too small, the blade 3 can be guided straight between the cutting edge 5 biting into the work material and penetrating as described above. Since there is a possibility that it cannot be performed, as shown in FIG. 3, both ends in the circumferential direction of the outer peripheral surface of the margin portion 9 when viewed from the front in the direction of the axis O It is desirable that the included angle α of the straight line connecting the axis line O and the axis O is 25 ° or more.

さらに、本実施形態では、上記交差稜線Ｌが軸線Ｏに平行に延びるようにされており、すなわち図２に示すようにマージン部９後端部の上記交点Ｎで交差する交差稜線Ｌと切屑排出溝４のドリル回転方向Ｔを向く壁面の上記外周側稜線部Ｍとの交差角βが、図１に示す切屑排出溝４の捩れ角θと略等しくされているが、この交差角βが小さすぎるとマージン部９後端部の交点Ｎ手前でマージン部９の周方向の幅が小さくなりすぎて、やはり刃部３を真っ直ぐ案内することができなくなったり、マージン部９の強度が損なわれたりするおそれがある。 Furthermore, in the present embodiment, the intersecting ridge line L extends in parallel to the axis O, that is, as shown in FIG. 2, the intersecting ridge line L intersecting with the intersecting point N at the rear end of the margin portion 9 and chip discharge. The intersection angle β of the wall surface of the groove 4 facing the drill rotation direction T with the outer peripheral ridge line portion M is substantially equal to the twist angle θ of the chip discharge groove 4 shown in FIG. 1, but this intersection angle β is small. If it is too large, the circumferential width of the margin portion 9 becomes too small before the intersection N of the rear end portion of the margin portion 9, so that the blade portion 3 cannot be guided straight or the strength of the margin portion 9 is impaired. There is a risk.

その一方で、この交差角βが大きすぎて、例えば交差稜線Ｌが交点Ｎから先端側に向かうに従いドリル回転方向Ｔの後方側に向けて大きく傾斜して延びるようにされていると、被削材を貫通した刃部３先端部を引き抜く際に、アンダーカットタイプのドリルの場合と同様にマージン部９と二番取り面８との境界部１０が貫通孔の開口部周縁に引っ掛かりやすくなって被削材がドリル本体１後端側に引き寄せられるおそれが生じる。このため、上記交差角βは切屑排出溝４の捩れ角θ（°）に対してθ−１０°〜θ＋５０°程度の範囲とされるのが望ましい。 On the other hand, if this crossing angle β is too large, for example, the crossing ridge line L extends from the crossing point N toward the front end side with a large inclination toward the rear side of the drill rotation direction T, When pulling out the tip of the blade portion 3 penetrating the material, the boundary portion 10 between the margin portion 9 and the second picking surface 8 is easily caught on the periphery of the opening portion of the through hole, as in the case of the undercut type drill. There is a possibility that the work material is drawn toward the rear end side of the drill body 1. For this reason, it is desirable that the crossing angle β is in a range of about θ-10 ° to θ + 50 ° with respect to the twist angle θ (°) of the chip discharge groove 4.

次に、図４ないし図９は、それぞれ本発明の第２ないし第７の実施形態を示すものであり、第１の実施形態と共通する構成要素には同一の符号を配して説明を簡略化する。このうち、まず図４に示す第２の実施形態では、ドリル本体１の先端側におけるマージン部９の周方向の幅が第１の実施形態よりも長くされていて、先端逃げ面６と二番取り面８との交差稜線部の全長がマージン部９との交差稜線とされた全周マージンとされており、さらにランド部７ヒール側の切屑排出溝４のドリル回転方向Ｔ後方側を向く壁面にもマージン部９が交差して、上記交差稜線Ｌが周方向に隣接する一方の切屑排出溝４のこのドリル回転方向Ｔ後方側を向く壁面の外周側稜線部から他方の切屑排出溝４のドリル回転方向Ｔを向く壁面の外周側稜線部Ｍに亙って延びている。 Next, FIGS. 4 to 9 show the second to seventh embodiments of the present invention, respectively, and the same reference numerals are assigned to the same components as those of the first embodiment, and the description will be simplified. Turn into. Among these, first, in the second embodiment shown in FIG. 4, the width in the circumferential direction of the margin portion 9 on the distal end side of the drill body 1 is made longer than that in the first embodiment. A wall surface facing the rear side in the drill rotation direction T of the chip discharge groove 4 on the heel side of the land portion 7, with the entire length of the intersecting ridge line portion with the chamfering surface 8 being the entire rim line that is an intersection ridgeline with the margin portion 9 Also, the margin portion 9 intersects, and the cross ridge line L of the one chip discharge groove 4 adjacent to the circumferential direction extends from the outer peripheral side ridge line portion of the wall surface facing the rear side in the drill rotation direction T of the other chip discharge groove 4. It extends over the outer peripheral side ridge line portion M of the wall surface facing the drill rotation direction T.

また、この第２の実施形態や上記第１の実施形態では、マージン部９の外周面とこの外周面から二番取り面８に至る境界部１０との交差稜線Ｌが軸線Ｏに平行な一直線状とされていたのに対し、図５ないし図９に示す第３ないし第７の実施形態では、これらの図に示すように上記交差稜線Ｌが折れ線状とされている。このうち、図５ないし図８に示す第３ないし第６の実施形態では、マージン部９は第１の実施形態と同様に先端逃げ面６のうちドリル回転方向Ｔ側（切刃５側）の部分のみでこの先端逃げ面６と交差するようにされている。 Further, in the second embodiment and the first embodiment, the intersecting ridge line L between the outer peripheral surface of the margin portion 9 and the boundary portion 10 extending from the outer peripheral surface to the second picking surface 8 is a straight line parallel to the axis O. On the other hand, in the third to seventh embodiments shown in FIGS. 5 to 9, the intersecting ridge line L is a polygonal line as shown in these drawings. Of these, in the third to sixth embodiments shown in FIGS. 5 to 8, the margin portion 9 is located on the drill rotation direction T side (cutting blade 5 side) of the tip flank 6 as in the first embodiment. Only the portion intersects the tip flank 6.

さらに、このうち図５および図６に示す第３および第４の実施形態では、交差稜線Ｌがこの先端逃げ面６との交点から軸線Ｏに平行に直線状に後端側に延びた後、例えば切屑排出溝４の捩れ角θと略等しい捩れ角でドリル回転方向Ｔ側に向かうに従いドリル本体１の先端側に向けて延び、先端逃げ面６に達する手前で再び軸線Ｏに平行に後端側に向けて延びて、切屑排出溝４のドリル回転方向Ｔを向く壁面の外周側稜線部Ｍと交点Ｎで交差するようにされており、ドリル本体１の先端部を左側に向けたときの側面視においてこれら図５および図６に示すように逆Ｚ字状をなしている。 Furthermore, in the third and fourth embodiments shown in FIGS. 5 and 6, after the intersecting ridge line L extends from the intersection with the tip flank 6 in a straight line parallel to the axis O to the rear end side, For example, the tip end of the drill body 1 extends toward the tip side of the drill body 1 at a twist angle substantially equal to the twist angle θ of the chip discharge groove 4 and reaches the tip flank 6, and is again parallel to the axis O before reaching the tip relief surface 6. When the tip end of the drill body 1 is directed to the left side, it extends to the side and intersects the outer peripheral side ridge line portion M of the wall surface facing the drill rotation direction T of the chip discharge groove 4 at the intersection N. In the side view, as shown in FIGS. 5 and 6, an inverted Z-shape is formed.

そして、第３の実施形態では、第１の実施形態と同様にこの交点Ｎに至る部分がマージン部９の後端部とされて、該交点Ｎでマージン部９が潰えてその周方向の幅が０とされているのに対し、第４の実施形態ではこの交点Ｎよりも、交差稜線Ｌが先端逃げ面６との交点から軸線Ｏに平行に直線状に後端側に延びる部分の方が軸線Ｏ方向後端側に位置してマージン部９の後端部とされており、こうして交差稜線Ｌが先端逃げ面６との交点から後端側に延びる部分と、この部分からドリル回転方向Ｔ側に向かうに従いドリル本体１の先端側に向けて延びる部分との曲折点Ｐでマージン部９が潰えてその周方向の幅が０となるようにされている。 In the third embodiment, as in the first embodiment, the portion reaching the intersection N is set as the rear end of the margin portion 9, and the margin portion 9 is crushed at the intersection N so that the width in the circumferential direction is reduced. However, in the fourth embodiment, the intersection ridge line L extends from the intersection with the front end flank 6 in a straight line parallel to the axis O toward the rear end rather than the intersection N in the fourth embodiment. Is located on the rear end side of the axis O direction and is the rear end portion of the margin portion 9, and thus the cross ridge line L extends from the intersection with the front end flank 6 to the rear end side, and the drill rotation direction from this portion The margin portion 9 is crushed at the bending point P with the portion extending toward the tip side of the drill body 1 toward the T side so that the circumferential width becomes zero.

また、図７に示す第５の実施形態では、上記交差稜線Ｌが先端逃げ面６との交点から軸線Ｏに平行に後端側に延びた後、軸線Ｏに垂直な平面に沿うようにドリル回転方向Ｔ側に延び、次いで再び軸線Ｏに平行に後端側に向けて延びて、切屑排出溝４のドリル回転方向Ｔを向く壁面の外周側稜線部Ｍと交点Ｎで交差するようにされ、第３の実施形態と同様にこの交点Ｎに至る部分がマージン部９の後端部とされて、後端側に向かうに従い周方向の幅が漸次減少して０となるようにされている。 Further, in the fifth embodiment shown in FIG. 7, the intersection ridge line L extends from the intersection with the tip flank 6 to the rear end side in parallel to the axis O, and then drills along a plane perpendicular to the axis O. It extends to the rotation direction T side, and then extends again toward the rear end side in parallel with the axis O, and intersects the outer peripheral side ridge line portion M of the chip discharge groove 4 facing the drill rotation direction T at the intersection N. As in the third embodiment, the portion reaching the intersection N is set as the rear end portion of the margin portion 9, and the width in the circumferential direction is gradually reduced to zero toward the rear end side. .

さらに、図８に示す第６の実施形態では、交差稜線Ｌが先端逃げ面６との交点から軸線Ｏに平行に後端側に延びた後、例えば切屑排出溝４の捩れ角θと略等しい捩れ角でドリル回転方向Ｔの後方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延び、さらに再び軸線Ｏに平行に後端側に延びるように曲折して、切屑排出溝４のドリル回転方向Ｔを向く壁面の外周側稜線部Ｍと交点Ｎで交差するようにされており、従ってやはりこの交点Ｎに至る部分が、後端側に向かうに従い周方向の幅が漸次減少して０となるマージン部９の後端部とされている。 Further, in the sixth embodiment shown in FIG. 8, after the intersecting ridge line L extends from the intersection with the front end flank 6 to the rear end side in parallel to the axis O, for example, substantially equal to the twist angle θ of the chip discharge groove 4. The drill of the chip discharge groove 4 extends to the rear end side of the drill body 1 as it goes to the rear side of the drill rotation direction T at a twist angle, and is further bent to extend to the rear end side in parallel with the axis O. It intersects with the outer peripheral side ridge line portion M of the wall surface facing the rotation direction T at the intersection N. Therefore, the width reaching the intersection N is gradually decreased toward the rear end side, and the circumferential width gradually decreases to 0. This is the rear end portion of the margin portion 9.

一方、これら第１ないし第６の実施形態では、１つの二番取り面８においてマージン部９が１つであったのに対し、図９に示す第７の実施形態は、二番取り面８のドリル回転方向Ｔ側とその後方側との両側にマージン部９が形成された、いわゆるダブルマージンタイプとされている。 On the other hand, in the first to sixth embodiments, there is one margin portion 9 on one second picking surface 8, whereas in the seventh embodiment shown in FIG. This is a so-called double margin type in which margin portions 9 are formed on both sides of the drill rotation direction T side and the rear side thereof.

このうち、二番取り面８のドリル回転方向Ｔ側に形成された第１マージン部９Ａは、上記交差稜線Ｌが先端逃げ面６との交点から、例えば切屑排出溝４の捩れ角θと略等しい捩れ角でドリル回転方向Ｔの後方側に向かうに従いドリル本体１の後端側に向けて捩れるように延び、次いで軸線Ｏに平行に後端側に延びるように曲折して、当該二番取り面８のドリル回転方向Ｔ側に隣接する切屑排出溝４のドリル回転方向Ｔを向く壁面の外周側稜線部Ｍと交点Ｎで交差するようにされている。 Among these, the first margin portion 9A formed on the drilling direction T side of the second picking surface 8 is substantially the same as the twist angle θ of the chip discharge groove 4 from the intersection of the intersecting ridge line L with the tip flank 6, for example. It extends so as to twist toward the rear end side of the drill body 1 toward the rear side in the drill rotation direction T at an equal twist angle, and then bends so as to extend toward the rear end side in parallel with the axis O. It intersects with the outer peripheral side ridge line portion M of the wall surface facing the drill rotation direction T of the chip discharge groove 4 adjacent to the chamfering surface 8 on the drill rotation direction T side at the intersection N.

また、二番取り面８のドリル回転方向Ｔ後方側（ヒール側）の第２マージン部９Ｂは、上記交差稜線Ｌが先端逃げ面６との交点から、やはり例えば切屑排出溝４の捩れ角θと略等しい捩れ角でドリル回転方向Ｔの後方側に向かうに従いドリル本体１の後端側に向けて捩れるように延び、次いで軸線Ｏに平行に先端側に延びるように曲折して、当該二番取り面８のドリル回転方向Ｔ後方側に隣接する切屑排出溝４のドリル回転方向Ｔ後方側を向く壁面の外周側稜線部と交差するようにされている。 Further, the second margin portion 9B on the rear side (heel side) of the drilling direction T of the second picking surface 8 is, for example, a twist angle θ of the chip discharging groove 4 from the intersection of the intersecting ridge line L with the tip flank 6. Extending to the rear end side of the drill body 1 toward the rear side in the drill rotation direction T at a twist angle substantially equal to that of the drill body, and then bending to extend to the front end side in parallel to the axis O. It intersects with the outer peripheral side ridge line part of the wall surface facing the drill rotation direction T rear side of the chip discharge groove 4 adjacent to the drill rotation direction T rear side of the cutting surface 8.

さらに、この第７の実施形態では、上記第１マージン部９Ａの後端部が第２マージン部９Ｂよりも軸線Ｏ方向後端側に位置していて、これら第１、第２マージン部９Ａ、９Ｂを合わせたマージン部９の周方向の幅が、この第１マージン部９Ａの後端部で後端側に向かうに従い漸次減少して０となり、マージン部９が潰えるようにされている。なお、これら第１、第２マージン部９Ａ、Ｂの上記交差稜線Ｌが軸線Ｏに平行に延びる部分は、１つの直線に沿って延びるようにされている。 Further, in the seventh embodiment, the rear end portion of the first margin portion 9A is located on the rear end side in the axis O direction with respect to the second margin portion 9B, and the first and second margin portions 9A, 9A, The width in the circumferential direction of the margin portion 9 combined with 9B gradually decreases to 0 toward the rear end side at the rear end portion of the first margin portion 9A so that the margin portion 9 is crushed. Note that a portion where the intersecting ridge line L of the first and second margin portions 9A and 9B extends in parallel to the axis O extends along one straight line.

このように構成された第２ないし第７の実施形態のツイストドリルにおいても、マージン部９の後端部は、上述したようにいずれも後端側に向かうに従い周方向の幅が漸次減少して０となるようにされており、従って第１の実施形態と同様に加工穴が被削材を貫通するまでは刃部３の先端部を軸線Ｏに沿って真っ直ぐ案内しつつも、加工穴が貫通してマージン部９が貫通孔から抜け出た後は、被削材がドリル本体１後端側に引き寄せられるのを防ぐことができる。 Also in the twist drills of the second to seventh embodiments configured in this way, the rear end portion of the margin portion 9 is gradually reduced in the circumferential width toward the rear end side as described above. Therefore, as in the first embodiment, until the machining hole penetrates the workpiece, the tip of the blade 3 is guided straight along the axis O while the machining hole is It is possible to prevent the work material from being drawn toward the rear end side of the drill body 1 after passing through and the margin portion 9 comes out of the through hole.

そして、さらにこの刃部３を貫通孔から引き抜くときに、例えば第５の実施形態のように交差稜線Ｌが軸線Ｏに垂直な平面に沿って延びる部分を有していても、これよりも先にマージン部９は周方向の幅が０となる位置から貫通孔と接触して、徐々に周方向の接触幅が長くなるようにされて、引き抜かれることになるため、この貫通孔の開口部周縁と引っ掛かりを生じるようなことがない。従って、ボール盤においてドリル本体１を引き抜く際に被削材が持ち上げられたり、手持ちの電気ドリルでの孔明け作業の場合において被削材が作業者側に引き寄せられたりするのを防ぐことができ、円滑かつ安定した貫通孔明け加工を行うことが可能となる。 Further, when the blade portion 3 is further pulled out from the through hole, even if the intersecting ridge line L has a portion extending along a plane perpendicular to the axis O as in the fifth embodiment, for example, Further, the margin portion 9 comes into contact with the through-hole from the position where the circumferential width becomes 0, and the circumferential contact width gradually becomes longer and is pulled out. There is no such thing as getting stuck on the periphery. Therefore, it is possible to prevent the work material from being lifted when the drill body 1 is pulled out from the drilling machine, or from being pulled toward the operator in the case of drilling work with a hand-held electric drill, Smooth and stable through-hole drilling can be performed.

なお、これら第１ないし第７の実施形態では、ドリル本体１先端側の刃部３に一対の切屑排出溝４が軸線Ｏに関して１８０°回転対称に形成されて、そのドリル回転方向Ｔを向く壁面の先端側稜線部に切刃５が形成された２枚刃のツイストドリルに本発明を適用した場合について説明したが、切屑排出溝４や切刃５は３つ以上であってもよく、またこれら切屑排出溝４の幅やランド部７の幅などが全て同一である必要はない。 In these first to seventh embodiments, the pair of chip discharge grooves 4 are formed in the blade portion 3 on the tip end side of the drill body 1 in a 180-degree rotational symmetry with respect to the axis O, and the wall surface faces the drill rotation direction T. Although the case where the present invention is applied to the two-blade twist drill in which the cutting edge 5 is formed on the tip side ridge line portion of the cutting edge 5 is described, the number of the chip discharge grooves 4 and the cutting edges 5 may be three or more. The widths of the chip discharge grooves 4 and the land portions 7 are not necessarily the same.

１ドリル本体
３刃部
４切屑排出溝
５切刃
６先端逃げ面
７ランド部
８二番取り面
９マージン部
１０境界部
Ｏドリル本体１の軸線
Ｔドリル回転方向
Ｌマージン部の外周面と境界部との交差稜線
Ｍ切屑排出溝４のドリル回転方向Ｔを向く壁面の外周側稜線部
Ｎ交差稜線Ｌと外周側稜線部Ｍとの交点 DESCRIPTION OF SYMBOLS 1 Drill main body 3 Cutting edge part 4 Chip discharge groove 5 Cutting edge 6 Tip flank 7 Land part 8 Fitting surface 9 Margin part 10 Boundary part O Drill body 1 axis T Drill rotation direction L The outer peripheral surface and boundary part of a margin part Crossing ridgeline M with the outer peripheral side ridgeline part of the wall surface facing the drill rotation direction T of the chip discharge groove 4 N

Claims

軸線回りにドリル回転方向に回転させられるドリル本体の先端部外周に上記軸線回りに螺旋状に捩れる切屑排出溝が形成され、この切屑排出溝のドリル回転方向を向く壁面の先端側稜線部に切刃が形成されるとともに、上記壁面の外周側稜線部から上記ドリル回転方向後方側に延びる上記ドリル本体の二番取り面にはマージン部が形成されており、このマージン部は、その後端部において上記軸線方向後端側に向かうに従い周方向の幅が漸次減少して、上記切屑排出溝が形成されている範囲で上記幅が０となるようにされていることを特徴とするツイストドリル。 A chip discharge groove that is helically twisted around the axis is formed on the outer periphery of the tip of the drill body that is rotated in the drill rotation direction around the axis, and the tip ridge of the wall surface facing the drill rotation direction of the chip discharge groove A cutting edge is formed, and a margin part is formed on the second face of the drill body extending from the outer peripheral side ridge line part of the wall surface to the rear side in the drill rotation direction. The twist drill is characterized in that the width in the circumferential direction gradually decreases toward the rear end side in the axial direction so that the width becomes 0 in a range where the chip discharge groove is formed.