JP4165041B2

JP4165041B2 - Throw-away tip for drilling

Info

Publication number: JP4165041B2
Application number: JP2001208220A
Authority: JP
Inventors: 正治滝口
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2001-07-09
Filing date: 2001-07-09
Publication date: 2008-10-15
Anticipated expiration: 2021-07-09
Also published as: JP2003019613A

Description

【０００１】
【発明の属する技術分野】
本発明は、特にスローアウェイ式の穴明け工具等に取り付けられて穴明け加工に供するのに好適な穴明け加工用スローアウェイチップ（以下、チップと称する。）に関するものである。
【０００２】
【従来の技術】
この種のチップとしては、例えば特願平１１−４５４８２号に、図４および図５に示すようなものが提案されている。すなわち、これらの図に示すチップは、そのチップ本体１が略三角形（厳密には偏５角形）の平板状に形成されたものであって、その一方の三角形面がすくい面２とされるとともに一の側面が逃げ面３とされ、この逃げ面３と交差するすくい面２の辺稜部に切刃４が形成されたものであって、上記逃げ面３とチップ本体１の他の一の側面５とは、この切刃４の一端４ａ側の角部Ｃにおいて鋭角に交差する方向に配置されている。ここで、この角部Ｃにおいて上記すくい面２には、角部Ｃの先端側から上記側面５に沿って順に、この側面５とチップ本体１の着座面６とされる他方の三角形面とに平行な中心線を有して側面５側に向かうに従い凸曲しつつ上記着座面６側に向かう円筒面２ａと、この円筒面２ａに連なって上記角部Ｃ側から離間するに従い漸次***する***面２ｂとが形成されており、従って切刃４の一端４ａ側には、上記円筒面２ａと逃げ面３との交差稜線部に、上記中心線に沿って逃げ面３に対向する方向から見た場合（図４において矢線Ｅ方向に見た場合）に図５に示すように円弧状をなして凸曲する凸曲状切刃部４Ａが形成される。なお、切刃４の他端４ｂ側は、同方向から見た場合にこの切刃４の凸曲状切刃部４Ａがなす円弧に滑らかに接して上記着座面６に平行に延びる直線状切刃部４Ｂとされている。
【０００３】
このように構成されたチップは、図６に示すように、軸線Ｏ回りに回転される略円柱状のスローアウェイ式穴明け工具の工具本体７の先端に、軸線Ｏを挟んで互いに反対側に一つずつ取り付けられて穴明け加工に使用される。すなわち、この工具本体７の外周には、その先端から後端側に向けて軸線Ｏ回りに工具回転方向Ｔの後方側に捩れる一対の切屑排出溝８，８が軸線Ｏを挟んで互いに反対側に形成されるとともに、各切屑排出溝８の工具回転方向Ｔ側を向く壁面８ａの先端部にはそれぞれチップ取付座９が形成されており、上記チップはこれらのチップ取付座９に、そのすくい面２を工具回転方向Ｔ側に向けるとともに逃げ面３を工具先端側に向け、かつ上記側面５を工具内周側に向けるとともに着座面６をチップ取付座９の底面に着座させて、クランプネジ１０により着脱可能に取り付けられ、この取付状態で、上記切刃４の一端４ａは工具本体７先端の上記軸線Ｏ近傍に位置させられるとともに他端４ｂが工具本体７の先端外周に位置させられて、この切刃４に工具外周側に向かうに従い工具後端側に向かうように先端角が与えられ、さらに上記凸曲状切刃部４Ａが工具回転方向Ｔに凸となるようにされている。
【０００４】
従って、上記チップをこのように取り付けた穴明け工具では、こうして工具本体７の軸線Ｏ近傍に配置される切刃４の一端４ａ側が、凸曲状切刃部４Ａによって工具回転方向Ｔに凸となる曲線状に形成されることにより、回転速度が小さくなるために大きな負荷が作用するこの軸線Ｏ近傍において切刃の強度を確保することができる。なお、一対の切屑排出溝８，８先端のチップ取付座９，９に取り付けられたチップの軸線Ｏ近傍に位置させられた切刃４，４の一端４ａ，４ａ間には極小さな間隔があけられて、上記負荷のうちスラスト荷重の低減が図られているとともに、この間隔部の工具後端側の工具本体７先端中心部には、切屑排出溝８，８に連通する小さな凹所７ａが形成されており、このように切刃４，４の一端４ａ，４ａ間に間隔があけられることにより穴明け加工時に軸線Ｏに沿って成長する加工物のコアを、この凹所７ａに収容して切屑排出溝８から排出するようにされている。さらに、上記チップ取付座９の工具内周側には、工具後端側に向かうに従い工具外周側に向けて斜めに延びるように壁面９ａが形成されていて、両チップ取付座９，９の壁面９ａ，９ａにより、工具本体７先端部の上記凹所７ａより後端側には、上記軸線Ｏの周辺に工具後端側に向けて漸次厚くなる壁部が形成されて、この工具本体７の先端部における強度が確保されるように図られており、上記チップはその工具内周側に向けられる上記側面５をこの壁面９ａに当接させて取り付けられている。
【０００５】
【発明が解決しようとする課題】
ところで、このようにチップ取付座９の壁面９ａが工具後端側に向かうに従い工具外周側に向けて斜めに延びるように形成されて、この壁面９ａに側面５を当接させてチップ本体１が取り付けられていると、この側面５に平行とされた上記円筒面２ａの中心線もすくい面２に対向する平面視に工具後端側に向かうに従い工具外周側に向けて斜めに延びるように配設されることとなる。従って、この円筒面２ａと逃げ面３の交差稜線部に形成される切刃４の上記一端部４ａ側が円弧状をなすように見える方向、すなわち図４において矢線Ｅで示した方向も、各チップに関して図６に示すように、工具本体７の軸線Ｏ方向に沿って工具先端側から見た場合よりも、軸線Ｏについて該チップが取り付けられる側とは反対側の上記切刃４の一端４ａ側寄りの位置から工具外周後端側に向けて上記チップ本体１を見た方向となる。
【０００６】
しかしながら、このように円筒面２ａの中心線が工具後端側に向かうに従い工具外周側に向けて斜めに延びるように配設されて、切刃４の一端４ａ側が該一端４ａ側寄りの位置から工具外周後端側に向けてチップ本体１を見た場合に円弧状をなすように形成されていると、上述のように先端角が与えられた切刃４に直交する方向、すなわち切刃４によって生成された切屑がすくい面２上を流出する方向に沿って見たときには、上記円筒面２ａは切刃４から離間するに従い大きく湾曲して着座面６側に落ち込むこととなる。このため、切刃４によって生成された切屑は、切刃４の他端４ｂ側の直線状切刃部４Ｂによって生成された部分が該切刃４に直交する方向に流出するのに対し、一端４ａ側の凸曲状切刃部４Ａによって生成された部分は、上記円筒面２ａが落ち込む方向、すなわち工具内周側に向けて案内されて流れ出ることとなって、このように切刃４の一端４ａ側と他端４ｂ側とで異なる方向に流れ出ようとすることにより切屑がその幅方向に引き裂かれるように分断されてしまい、このうち凸曲状切刃部４Ａで生成された部分は、上記円筒面２ａに沿って工具内周側に案内されて工具本体１先端中心部の上記凹所７ａに流れ込んでしまうため、この凹所７ａで詰まりを生じてしまう。
【０００７】
また、このようにすくい面２の円筒面２ａが切刃４に直交する方向には大きく湾曲して着座面６側に落ち込むように形成されることにより、上記従来のチップでは、この切刃４に直交する断面における切刃４の一端４ａ側の凸曲状切刃部４Ａの刃先角が小さくなり、これに伴い刃先強度も小さくなってしまうという問題も生じる。特に、この切刃４の一端４ａ側は、チップが工具本体７に取り付けられた状態で軸線Ｏ近傍に配置されることにより、上述のように大きな負荷が作用する部分であるので、そのような部分において切刃４に刃先強度が確保されていないと、たとえこの切刃４の一端４ａ側を凸曲状切刃部４Ａとして工具回転方向Ｔに凸となる曲線状にしたとしても、加工物への食い付き時や穴明け加工中に欠けやチッピングが生じてしまい、その時点でチップ寿命が費えてしまってチップの交換を余儀なくされる結果となる。
【０００８】
本発明は、このような背景の下になされたもので、上述のように切刃の一端側に凸曲状切刃部が形成されたチップにおいて、この切刃部によって切屑が分断されて詰まりを生じるような事態を防ぐとともに、該切刃部における刃先強度も確保してチップ寿命の延長を図ることが可能なチップを提供することを目的としている。
【０００９】
【課題を解決するための手段】
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、概略多角形平板状をなすチップ本体の一方の多角形面がすくい面とされ、このすくい面の辺稜部に形成された切刃の一端を、軸線回りに回転される穴明け工具の工具本体先端の上記軸線近傍に位置させるとともに、上記切刃の他端を上記工具本体の先端外周に位置させ、上記切刃に工具外周側に向かうに従い工具後端側に向かう先端角が与えられて上記すくい面が工具回転方向に向けられるように取り付けられるチップであって、上記切刃の少なくとも一端側の上記すくい面上に、この切刃の一端側に向かうに従い上記チップ本体の他方の多角形面側に湾曲する凸曲状面を形成し、この凸曲状面の辺稜部に形成される上記切刃の一端側に、上記軸線方向よりも上記切刃の他端側寄りの位置から工具内周後端側に向けて上記チップ本体を見た場合に略円弧状をなして上記工具回転方向に凸となる凸曲状切刃部と、この凸曲状切刃部が略円弧状をなすように見える方向から見て、上記凸曲状切刃部の一端において該凸曲状切刃部に鈍角に交差して上記チップ本体の他方の多角形面側に延びる直線状の小切刃部とを形成したことを特徴とする。
【００１０】
従って、上記従来のチップのように切刃の一端側寄りの位置から工具外周後端側に向けてチップ本体を見た場合に切刃の一端側が円弧状をなすように形成されたのとは逆に、上記凸曲状切刃部が工具本体の軸線方向よりも切刃の他端側寄りの位置から工具内周後端側に向けてチップ本体を見た場合に略円弧状をなすようにされた本発明のチップでは、この略円弧状をなす凸曲状切刃部に連なってすくい面に形成される凸曲状面も、例えばこの凸曲状面を従来と同様に円筒面とした場合には、その中心線が工具本体の軸線に平行よりも切刃の他端側寄りの位置から工具後端側に向かうに従い工具内周側に向かうように傾斜して配置されることとなる。すなわち、この凸曲状面の中心線が延びる方向が、上述のように先端角が与えられた切刃に直交する方向に近づくこととなるので、この方向に沿った凸曲状面の他方の多角形面側への湾曲を緩やかにすることができ、このため上記凸曲状切刃部で生成された切屑が工具内周側へ案内されて流出するのを防いで切屑が分断されるのを防止することができるとともに、この凸曲状切刃部における切刃の刃先角も大きく確保することができて切刃強度の向上を図ることが可能となる。
【００１１】
ここで、この凸曲状切刃部が略円弧状をなすように見える方向から見た場合、すなわち工具本体の軸線方向よりも切刃の他端側寄りの位置から工具内周後端側に向けてチップ本体を見た場合において、該凸曲状切刃部は、上記切刃の他端が上記工具本体の軸線回りになす円の直径Ｄの２８％〜４２％の半径の略円弧状とされるとともに、その一端が、上記チップ本体の他方の多角形面から上記直径Ｄの５％〜１０％の高さに配置され、かつ、上記切刃の他端側はこの凸曲状切刃部に接して直線状に延びる直線状切刃部とされて、この直線状切刃部との接点と上記一端との間の該直線状切刃部に平行な方向における上記凸曲状切刃部の幅が、上記直径Ｄの１３％〜２０％とされるのが望ましい。これは、上記半径が小さすぎたり一端の高さが低すぎたり幅が大きすぎたりすると、凸曲状切刃部が略円弧状に見える方向を上述のようにしても凸曲状面の湾曲が急になって切屑の分断を確実に防ぐことができなくなるおそれがあり、逆に上記半径が大きすぎたり一端の高さが高すぎたり幅が小さすぎると、切刃全体が直線状に近くなって、工具本体の軸線近傍に回転方向に凸となる凸曲状切刃部を設けることによる切刃強度の向上効果自体が十分奏功されなくなるおそれが生じるからである。
【００１２】
また、切刃のうちでも最も工具本体の軸線近くに配設される凸曲状切刃部の一端側には最も大きな負荷が作用することとなるのに対し、本発明のチップでは、上記凸曲状切刃部が略円弧状をなすように見える方向から見た場合において、上記切刃の一端側には、この凸曲状切刃部の一端において該凸曲状切刃部に鈍角に交差してチップ本体の他方の多角形面側に延びる直線状の小切刃部を形成して、この部分の切刃の強度をさらに確実に確保している。なお、上記凸曲状切刃部も、上述のように工具本体の軸線方向よりも切刃の他端側寄りの位置から工具内周後端側に向けてチップ本体を見た場合において、略円弧状をなすように形成されていればよく、例えばこの凸曲状切刃部が複数の短い直線を円弧状に並ぶように連ねて形成されるようにしてもよい。また、このような場合の凸曲状切刃部の上記半径は、例えば上記複数の直線を近似した円弧の半径として得ることができる。
【００１３】
【発明の実施の形態】
図１ないし図３は、本発明の実施形態を示すものである。本実施形態のチップにおいても、そのチップ本体１１は、超硬合金等の硬質材料から形成されて略三角形、厳密には偏５角形の多角形平板状をなし、その一方の三角形面がすくい面１２とされるとともに一の側面が逃げ面１３とされ、この逃げ面１３と交差するすくい面１２の辺稜部に切刃１４が形成されている。また、この逃げ面１３とされる側面に隣接するチップ本体１１の他の一の側面１５は、切刃１４の一端１４ａ側の角部Ｃにおいて逃げ面１３と鋭角に交差する方向に配置されている。そして、このようなチップも、やはり上記従来のチップと同様、軸線Ｏ回りに回転させられるスローアウェイ式穴明け工具の工具本体７の切屑排出溝８先端に形成されたチップ取付座９に、その切刃１４の上記一端１４ａを軸線Ｏ近傍に位置させるとともに、切刃１４の他端１４ｂを工具本体１先端外周に位置させ、切刃４に工具外周側に向かうに従い工具後端側に向かう先端角が与えられるようにして、上記すくい面１２が工具回転Ｔ方向に向けられるとともに逃げ面１３が工具先端に向けられ、かつ上記側面１５がチップ取付座９の工具後端側に向かうに従い工具外周側に向けて延びる壁面９ａに当接させられた状態で、すくい面１２とは反対側の着座面１６とされる他方の三角形面が着座させられ、クランプネジ１０によって着脱可能に取り付けられる。
【００１４】
さらに、本実施形態でも、上記すくい面１２の角部Ｃ側には、上記着座面１６に平行に延びる中心線を有して該角部Ｃ側に向かうに従い凸曲しつつ着座面１６側に向かう円筒面１２ａが凸曲状面として形成されるとともに、この円筒面１２ａの後方には***面１２ｂが形成されていて、切刃１４の一端１４ａ側には、この円筒面１２ａと上記逃げ面１３との交差稜線部に凸曲状切刃部１４Ａが形成される一方、切刃１４の他端１４ｂ側はこの凸曲状切刃部１４Ａに滑らかに連なって着座面１６に平行に延びる直線状切刃部１４Ｂとされている。また、これら円筒面１２ａと***面１２ｂ以外のすくい面１２上には、切刃１４に連なって該切刃１４から離間するに従い一定の傾斜で上記着座面１６側に向かう傾斜面１２ｃが形成されるとともに、この傾斜面１２ｃを挟んで切刃１４とは反対側には、該傾斜面１２ｃから凹曲しながら***するブレーカ壁面１２ｄを介して上記着座面１６に平行な平坦面１２ｅが形成されており、傾斜面１２ｃとブレーカ壁面１２ｄの切刃４に直交する方向の幅は、該切刃１４に沿ってその他端１４ｂ側に向かうに従い漸次大きくなるようにされている。さらにまた、この切刃１４の他端１４ｂ側において上記逃げ面１３に交差するチップ本体１１の側面１７は該逃げ面１３に鈍角に交差して、上述のようにチップ本体１１が工具本体７のチップ取付座９に取り付けられた状態において、その工具回転方向Ｔ側の部分がこの工具本体７の軸線Ｏを中心とした円筒面となって、すくい面１２に対向する平面視に該軸線Ｏに平行に延びるようにされ、当該穴明け工具のマージンを形成するようにされている。また、上記すくい面１２から着座面１６にかけては、上記クランプネジ１０が挿通される取付孔１８が貫設されている。
【００１５】
そして、上述した従来のチップでは、その上記円筒面２ａの中心線が、上記逃げ面３に切刃４の一端４ａ側の角部Ｃで鋭角に交差する側面５にも平行とされていたのに対し、本実施形態のチップでは、その上記円筒面１２ａの中心線は、すくい面１２に対向する平面視において、逃げ面１３に切刃１４の他端１４ｂ側で鈍角に交差する上記側面１７に平行よりも逃げ面１３側に向かうに従い側面１７側に近づく方向に傾斜させられていて、切刃１４の一端１４ａ側の角部Ｃで逃げ面１３に鋭角に交差する側面１５には、この角部Ｃから離れた側で交差する方向に延びるように配設されている。従って、このようなチップを上述のように工具本体７に取り付けた状態においても、上記従来のチップでは、その円筒面２ａの中心線が工具後端側に向かうに従い工具外周側に向けて斜めに延びるように配設されて、切刃４の一端４ａ側の凸曲状切刃部４Ａが円弧状をなすように見える方向が、図１に矢線Ｅで示したように工具本体７の軸線Ｏ方向に沿って工具先端側から見た場合よりも切刃４の一端４ａ側寄りの位置から工具外周後端側に向けて上記チップ本体１を見た方向であったのに対し、本実施形態のチップでは、図１に矢線Ｆで示すように上記軸線Ｏ方向に工具先端側からチップ本体１１を見た場合よりも、図１に矢線Ｇや矢線Ｈで示すように切刃１４の他端１４ｂ側寄りの位置から工具内周後端側に向けてチップ本体１１を見た場合に、上記凸曲状切刃部１４Ａが円弧状をなして工具回転方向Ｔに凸となるようにされている。
【００１６】
なお、このように凸曲状切刃部１４Ａが円弧状をなすように見える方向から見た場合において、この凸曲状切刃部１４Ａがなす円弧の半径Ｒは、切刃１４の他端１４ｂが工具本体１１の軸線Ｏ回りになす円の直径Ｄ、すなわち上記スローアウェイ式穴明け工具の切刃外径の２８％〜４２％とされている。また、このとき、この凸曲状切刃部１４Ａの一端１４ｃは、チップ本体１１の着座面１６とされる他方の多角形面から上記直径Ｄの５％〜１０％の高さＡに配置され、かつ、上記凸曲状切刃部１４Ａと上記直線状切刃部１４Ｂとの接点１４ｄと上記一端１４ｃとの間の該直線状切刃部１４Ｂに平行な方向における凸曲状切刃部１４Ａの幅Ｂは、上記直径Ｄの１３％〜２０％とされている。さらに、側面１５の上記高さＡ方向略中央部には、着座面１６に垂直とされた幅狭の平坦面１５ａが該側面１５に沿って延びるように形成されていて、この平坦面１５ａが逃げ面１３と交差することにより、切刃１４の一端１４ａ側には、凸曲状切刃部１４Ａの上記一端１４ｃにおいて該凸曲状切刃部１４Ａに鈍角に交差して着座面１６側に延びる直線状の小切刃部１４Ｃが形成されている。なお、この平坦面１５ａと着座面１６およびすくい面１２の上記平坦面１２ｅとの間の部分の側面１５は、これら平坦面１５ａ，１２ｅ、着座面１６に鈍角に交差するようにされている。
【００１７】
従って、このように構成されたチップにおいては、該チップを上述のようにスローアウェイ式穴明け工具の工具本体７に取り付けた状態において、工具内周側の切刃１４の一端１４ａ側の凸曲状切刃部１４Ａが、工具本体７の軸線Ｏ方向よりも切刃１４の他端１４ｂ側寄りの位置から工具内周後端側に向けてチップ本体１１を見た場合に円弧状をなすようにされており、この凸曲状切刃部１４Ａに連なってすくい面１２の工具先端内周側に配設される凸曲状面としての円筒面１２ａも、その中心線が上述のように工具本体７の軸線Ｏに平行よりも切刃１４の他端１４ｂ側寄りの位置から工具後端側に向かうに従い工具内周側に向かうように傾斜して配置される。すなわち、この円筒面１２ａの中心線の延びる方向が、工具外周側に向かうに従い工具後端側に向かうように先端角が与えられた切刃１４に直交する方向に従来よりも近くなり、これによりこの切刃１４に直交する方向における円筒面１２ａの着座面１６側への湾曲を緩やかにすることができるので、この切刃１４によって生成された切屑のうち上記凸曲状切刃部１４Ａによって生成された部分が、工具内周側に案内されて直線状切刃部１４Ｂによって生成された部分から分断されたりするのを防ぐことができ、こうして分断された切屑が工具先端中心部において詰まりを生じたりするのを防止することができる。
【００１８】
ここで、図３（Ｅ）〜（Ｈ）は、それぞれ図１において矢線Ｅ〜Ｈ方向から見たときに凸曲状切刃部１４Ａが等しい半径の円弧状をなしている場合の、上述のような先端角が与えられた切刃１４に直交するチップ本体１１の角部Ｃ側のＸＸ断面を示すものであって、このうち図３（Ｆ）は図１に矢線Ｆで示すように上記軸線Ｏ方向に工具先端側からチップ本体１１を見た場合に凸曲状切刃部１４Ａが円弧状をなしている参考例のチップのＸＸ断面図であり、図３（Ｇ）、（Ｈ）は図１に矢線Ｇ、Ｈで示すように上記矢線Ｆよりも切刃１４の他端１４ｂ側寄りの位置から工具内周後端側に向けてチップ本体１１を見た場合に凸曲状切刃部１４Ａが円弧状をなしている上記実施形態のチップのＸＸ断面図であり、一方、図３（Ｅ）は、工具本体７の軸線Ｏ方向に沿って工具先端側から見た場合よりも切刃１４の一端１４ａ側寄りの位置から工具外周後端側に向けて上記チップ本体１１を見た場合に凸曲状切刃部１４Ａが円弧状をなす、従来のチップのＸＸ断面に相当するものである。しかるに、これら図３（Ｅ）〜（Ｈ）に示されるように、従来のチップの断面に相当する図３（Ｅ）では、切刃１４に直交する方向に沿った円筒面１２ａの着座面１６側への湾曲が大きく、このため凸曲状切刃部１４Ａによって生成された切屑がこの湾曲によって円筒面１２ａに案内されるように工具内周側に引き込まれ、直線状切刃部１４Ｂによって生成された切屑部分から分断されて切屑詰まりを生じてしまうのに対し、本実施形態によるチップの断面においては、凸曲状切刃部１４Ａがなす円弧の半径が同じであっても、図３（Ｇ）、（Ｈ）に示されるようにこの円筒面１２ａの湾曲が小さく、従って切屑が凸曲状切刃部１４Ａで生成された部分と直線状切刃部１４Ｂで生成された部分とで分断されることがなくなり、すくい面１２に設けられた傾斜面１２ｃおよびブレーカ壁面１２ｄによる効果とも相俟って、全体的に上記角部Ｃを中心にカールさせられて切屑詰まりを生じることなく切屑排出溝８に送り出され、円滑に排出・処理される。
【００１９】
また、このように切刃１４に直交する方向に沿った円筒面１２ａの湾曲が緩やかになることにより、上記構成のチップにおいては、やはり図３（Ｇ）、（Ｈ）に示されるように、この切刃１４に直交する方向に沿った断面における切刃１４（凸曲状切刃部１４Ａ）の刃先角αを、やはり図３（Ｅ）の従来のチップより大きくすることが可能となる。このため、工具先端中心部の軸線Ｏ近傍に配設されることとなる切刃１４の一端１４ａ側の凸曲状切刃部１４Ａにより高い切刃強度を与えることが可能となり、この凸曲状切刃部１４Ａが工具回転方向Ｔに凸となっていることとも相俟って、回転速度が小さくなるために大きな負荷が作用するこの軸線Ｏ近傍の切刃１４の一端１４ａ側に欠損やチッピングが生じたりするのを防止し、チップ寿命の延長を図って安定した穴明け加工を促すことが可能となる。
【００２０】
しかも、本実施形態では、この凸曲状切刃部１４Ａの一端１４ｃにさらに直線状の小切刃部１４Ｃが形成されており、従って切刃１４の一端１４ａはこの小切刃部１４Ｃ上に形成されることとなる。そして、この小切刃部１４Ｃは、凸曲状切刃部１４Ａが円弧状をなすように見える方向から見た場合において、この凸曲状切刃部１４Ａにその一端１４ｃで鈍角に交差してチップ本体１１の着座面１６側に延びるように形成されており、従って上述のように高い切刃強度が与えられた凸曲状切刃部１４Ａにおいても、特に軸線Ｏ近傍に配置されて最も大きな負荷が作用するその一端１４ｃには一層高い切刃強度が与えられるので、本実施形態のチップによれば、切刃１４の一端１４ａ側における欠損やチッピングをより確実に防止してチップ寿命のさらなる延長を促すことが可能となる。
【００２１】
なお、本実施形態では上述のように、凸曲状切刃部１４Ａが円弧状をなすように見える方向から見た場合において、この円弧の半径Ｒが切刃１４の他端１４ｂが軸線Ｏ回りになす円の直径Ｄの２８％〜４２％となるように、またこの凸曲状切刃部１４Ａの上記一端１４ｃがチップ本体１１の着座面１６から上記直径Ｄの５％〜１０％の高さＡに位置するように、さらに該方向視における一端１４ｃから直線状切刃部１４Ｂとの接点１４ｄまでの凸曲状切刃部１４Ａの幅Ｂが上記直径Ｄの１３％〜２０％となるように、それぞれ設定されているが、これは、上記直径Ｄすなわち切刃１４の外径に対して上記半径Ｒが小さすぎたり、凸曲状切刃部１４Ａの一端１４ｃの高さＡが低すぎたり、あるいは幅Ｂが大きすぎたりすると、上述のように凸曲状切刃部１４Ａが円弧状に見える方向を軸線Ｏに平行あるいはこれよりも切刃１４の他端１４ｂ側寄りとしても、切刃１４に直交する方向に沿った円筒面１２ａの着座面１６側への湾曲が大きく急になって切屑の分断を確実に防止することができなくなるおそれがあるからである。その一方で、逆に半径Ｒが大きすぎたり、一端１４ｃの高さＡが高すぎたり、幅Ｂが小さすぎると、凸曲状切刃部１４Ａの湾曲が小さくなりすぎて切刃１４全体が直線状に近くなり、この凸曲状切刃部１４Ａを工具本体７の軸線Ｏ近傍に設けて工具回転方向Ｔに凸となるようにすることにより切刃強度の向上を図るといった効果自体が却って十分奏功されなくなるおそれが生じるため、これら凸曲状切刃部１４Ａの半径Ｒ、高さＡ、および幅Ｂは、本実施形態のように設定されるのが望ましく、さらに上記直径Ｄの大きさに応じて、次表１に示す範囲内に設定されるのがより望ましい。ただし、この表１の高さＡ、幅Ｂ、半径Ｒの欄において、上段は直径Ｄに対する一例としての設定値を、また下段は直径Ｄに対する好適な比率を示している。
【００２２】
【表１】

【００２３】
さらに、本実施形態では凸曲状切刃部１４Ａを工具本体７の軸線Ｏ方向先端側からチップ本体１１を見た場合、またはこれよりも切刃１４の他端１４ｂ側寄りの位置から工具内周後端側に向けてチップ本体１１を見た場合に円弧状をなして工具回転方向Ｔに凸曲するように形成しているが、この凸曲状切刃部１４Ａは、かかる方向から見た場合に概略円弧状をなすように形成されていればよく、例えば複数の短い直線を円弧状に連ねて凸曲状切刃部１４Ａを形成したりしてもよい。なお、このような場合の凸曲状切刃部１４Ａの上記半径Ｒは、これら複数の直線を近似した円弧の半径として得られる。また、本実施形態では切刃１４の一端１４ａ側のみにこの凸曲状切刃部１４Ａを形成しているが、切刃１４の全長がこの凸曲状切刃部１４Ａとされていてもよい。
【００２４】
【発明の効果】
以上説明したように、本発明によれば、切刃の一端側に形成されて工具本体先端の回転軸線近傍に配置される凸曲状切刃部を、この軸線方向よりも切刃の他端側寄りの位置から工具内周後端側に向けて見た場合に、略円弧状をなして工具回転方向に凸となるように形成することにより、この凸曲状切刃部に連なるすくい面の凸曲状面が、先端角が与えられた切刃に直交する方向に沿ってなす着座面側への湾曲を緩やかにすることができ、これによりこの凸曲状切刃部によって生成された切屑が分断されて詰まりを生じたり、あるいは該凸曲状切刃部の刃先強度が損なわれて欠損やチッピングを生じたりするような事態を防止し、チップ寿命の延長と円滑な切屑処理とを可能にして安定した穴明け加工を促すことができる。
【図面の簡単な説明】
【図１】本発明の一実施形態を示す、工具本体７の先端部に取り付けた穴明け加工用スローアウェイチップのすくい面１２に対向する方向から見た平面図である。
【図２】図１に示す穴明け加工用スローアウェイチップの矢線Ｆ方向視の側面図である。
【図３】（Ｅ）〜（Ｈ）は、それぞれ図１において矢線Ｅ〜Ｈ方向視に見たときに凸曲状切刃部１４Ａが円弧状をなす場合のＸＸ断面図である。ただし、（Ｅ）は従来の穴明け加工用スローアウェイチップに相当する。
【図４】従来の穴明け加工用スローアウェイチップのすくい面２に対向する方向から見た平面図である。
【図５】図４および図６における矢線Ｅ方向視の従来の穴明け加工用スローアウェイチップの側面図である。
【図６】従来の穴明け加工用スローアウェイチップを取り付けたスローアウェイ式穴明け工具の平面図である。
【符号の説明】
７工具本体
１１チップ本体
１２すくい面
１２ａ円筒面（凸曲状面）
１３逃げ面
１４切刃
１４Ａ凸曲状切刃部
１４Ｂ直線状切刃部
１４Ｃ小切刃部
１４ａ切刃１４の一端
１４ｂ切刃１４の他端
１４ｃ凸曲状切刃部１４Ａの一端
１４ｄ凸曲状切刃部１４Ａと直線状切刃部１４Ｂとの接点
１６着座面（チップ本体の他方の多角形面）
Ｏ工具本体７の軸線
Ｔ工具回転方向
Ｄ切刃１４の他端１４ｂが軸線Ｏ回りになす円の直径
Ｒ円弧状をなす方向からみた場合の凸曲状切刃部１４Ａの半径
Ａ凸曲状切刃部１４Ａの一端１４ｃの着座面１６からの高さ
Ｂ円弧状をなす方向からみた場合の凸曲状切刃部１４Ａの幅[0001]
BACKGROUND OF THE INVENTION
The present invention particularly relates to a drilling throw-away tip (hereinafter referred to as a tip) suitable for being drilled by being attached to a throw-away drilling tool or the like.
[0002]
[Prior art]
For example, Japanese Patent Application No. 11-45482 has proposed a chip of this type as shown in FIGS. That is, the chips shown in these drawings are such that the chip body 1 is formed in a substantially triangular (strictly, pentagonal) flat plate shape, and one of the triangular surfaces is a rake face 2. One side surface is a flank 3, and a cutting edge 4 is formed on a side ridge portion of the rake face 2 that intersects the flank 3, and the flank 3 and the other one of the chip body 1. The side surface 5 is arranged in a direction intersecting an acute angle at a corner portion C on the one end 4 a side of the cutting blade 4. Here, in the corner portion C, the rake face 2 is formed in order from the tip end side of the corner portion C along the side face 5 to the side face 5 and the other triangular face which is the seating face 6 of the chip body 1. A cylindrical surface 2a that has a parallel center line and curves toward the side surface 5 while being curved toward the seating surface 6 side, and a bulge that gradually rises as the distance from the corner C side continues to the cylindrical surface 2a. The surface 2b is formed on the one end 4a side of the cutting edge 4, so that the crossing ridge line portion between the cylindrical surface 2a and the flank 3 is seen from the direction facing the flank 3 along the center line. In this case (when viewed in the direction of arrow E in FIG. 4), a convex cutting edge portion 4A that is curved in a circular arc shape as shown in FIG. 5 is formed. Note that the other end 4b side of the cutting edge 4 is a linear cutting edge that extends in parallel to the seating surface 6 while smoothly touching the arc formed by the convex cutting edge 4A of the cutting edge 4 when viewed from the same direction. It is set as the blade part 4B.
[0003]
As shown in FIG. 6, the tip configured as described above is disposed on the opposite side of the axis O at the tip of the tool body 7 of the substantially cylindrical throw-away drilling tool rotated about the axis O. Installed one by one and used for drilling. That is, on the outer periphery of the tool body 7, a pair of

chip discharge grooves

8, 8 twisted to the rear side in the tool rotation direction T around the axis O from the front end to the rear end side are opposite to each other across the axis O. The tip mounting seats 9 are formed at the tip portions of the wall surfaces 8a facing the tool rotation direction T of each chip discharge groove 8 and the chips are formed on the tip mounting seats 9, respectively. The rake face 2 faces the tool rotation direction T side, the flank face 3 faces the tool tip side, the side face 5 faces the tool inner peripheral side, and the seating face 6 sits on the bottom surface of the tip mounting seat 9 to clamp The screw 10 is detachably attached, and in this attached state, the one end 4a of the cutting blade 4 is positioned in the vicinity of the axis O at the tip of the tool body 7 and the other end 4b is positioned at the outer periphery of the tip of the tool body 7. This cut 4 point angle is given to face the tool rear side toward the tool outer peripheral side, and is further to the convexly curved shape cutting edge 4A is convex toward the tool rotational direction T.
[0004]
Therefore, in the drilling tool to which the chip is attached in this way, the one end 4a side of the cutting blade 4 arranged in the vicinity of the axis O of the tool body 7 is thus convex in the tool rotation direction T by the convex cutting blade portion 4A. By forming the curved shape, the strength of the cutting edge can be ensured in the vicinity of the axis O where a large load acts because the rotational speed is reduced. It should be noted that a very small gap is provided between the

ends

4a, 4a of the cutting blades 4, 4 positioned in the vicinity of the axis O of the chip mounted on the

chip mounting seats

9, 9 at the tips of the pair of

chip discharge grooves

8, 8. Of these loads, the thrust load is reduced, and a small recess 7a communicating with the

chip discharge grooves

8 and 8 is formed at the center of the tip of the tool body 7 on the tool rear end side of the gap portion. In this way, the core of the workpiece that grows along the axis O during the drilling process is accommodated in the recess 7a by forming a gap between the

ends

4a, 4a of the cutting blades 4, 4. The chips are discharged from the chip discharge groove 8. Furthermore, a wall surface 9a is formed on the inner peripheral side of the tip mounting seat 9 so as to extend obliquely toward the outer peripheral side of the tool toward the rear end side of the tool. 9a and 9a, a wall portion gradually increasing toward the rear end side of the tool is formed around the axis O on the rear end side of the recess 7a at the front end portion of the tool main body 7. The tip is designed to ensure strength, and the tip is attached with the side surface 5 facing the inner peripheral side of the tool in contact with the wall surface 9a.
[0005]
[Problems to be solved by the invention]
By the way, the wall surface 9a of the chip mounting seat 9 is formed so as to extend obliquely toward the outer peripheral side of the tool as it goes to the tool rear end side. When attached, the center line of the cylindrical surface 2a parallel to the side surface 5 is also arranged so as to extend obliquely toward the tool outer peripheral side toward the tool rear end side in a plan view facing the rake surface 2. Will be established. Therefore, the direction in which the one end 4a side of the cutting edge 4 formed at the intersecting ridge line portion of the cylindrical surface 2a and the flank 3 appears to form an arc, that is, the direction indicated by the arrow E in FIG. As shown in FIG. 6 with respect to the tip, one end 4a of the cutting blade 4 on the side opposite to the side on which the tip is attached with respect to the axis O, as compared with the case where the tip is attached along the direction of the axis O of the tool body 7. The tip body 1 is viewed from the side position toward the tool outer peripheral rear end side.
[0006]
However, it is arranged so that the center line of the cylindrical surface 2a extends obliquely toward the outer peripheral side of the tool as it goes toward the rear end side of the tool, and the one end 4a side of the cutting blade 4 is located from the position closer to the one end 4a side. When the chip body 1 is formed so as to form an arc shape when viewed toward the rear end side of the outer periphery of the tool, the direction perpendicular to the cutting edge 4 given the tip angle as described above, that is, the cutting edge 4 When the chips generated by the above are viewed along the direction of flowing out on the rake face 2, the cylindrical surface 2 a is greatly curved as it is separated from the cutting edge 4 and falls to the seating surface 6 side. For this reason, the chip generated by the cutting edge 4 flows out in a direction perpendicular to the cutting edge 4 while the part generated by the linear cutting edge 4B on the other end 4b side of the cutting edge 4 flows out in one direction. The portion generated by the convex curved cutting edge portion 4A on the 4a side flows out while being guided toward the direction in which the cylindrical surface 2a falls, that is, toward the inner peripheral side of the tool. By trying to flow out in different directions on the 4a side and the other end 4b side, the chips are divided so as to be torn in the width direction, and the portion generated by the convex curved cutting edge portion 4A is as described above. Since it is guided along the cylindrical surface 2a to the inner peripheral side of the tool and flows into the recess 7a at the center of the tip of the tool body 1, the recess 7a is clogged.
[0007]
In addition, since the cylindrical surface 2a of the rake face 2 is formed so as to be greatly curved in the direction orthogonal to the cutting edge 4 and fall to the seating face 6 side, the cutting edge 4 is formed in the conventional tip. The cutting edge angle of the convex curved cutting edge portion 4A on the one end 4a side of the cutting edge 4 in the cross section orthogonal to the angle becomes small, and this causes a problem that the strength of the cutting edge is also reduced. In particular, the one end 4a side of the cutting blade 4 is a portion where a large load acts as described above by being disposed in the vicinity of the axis O in a state where the tip is attached to the tool body 7, If the cutting edge 4 does not have sufficient edge strength at the portion, even if the one end 4a side of the cutting edge 4 is formed as a convex cutting edge 4A and is curved in the tool rotation direction T, the workpiece is processed. Chipping or chipping occurs during biting or drilling, at which point the chip life is consumed and the chip must be replaced.
[0008]
The present invention has been made under such a background. In a chip in which a convex curved cutting edge portion is formed on one end side of the cutting edge as described above, chips are divided by this cutting edge portion and clogged. It is an object of the present invention to provide a chip that can prevent a situation such as the occurrence of the problem and can secure a cutting edge strength at the cutting edge portion to extend the chip life.
[0009]
[Means for Solving the Problems]
In order to solve the above problems and achieve such an object, according to the present invention, one polygonal surface of a chip body having a substantially polygonal flat plate shape is a rake face, and a side ridge portion of the rake face is formed. One end of the formed cutting blade is positioned in the vicinity of the axis of the tip of the tool body of the drilling tool rotated about the axis, and the other end of the cutting blade is positioned on the outer periphery of the tip of the tool body. A tip which is attached so that a tip angle toward the tool rear end side is given to the blade toward the tool rear end side so that the rake face is directed in the tool rotation direction, and the rake face on at least one end side of the cutting edge A convex curved surface that is curved on the other polygonal surface side of the chip body as it goes toward one end side of the cutting blade is formed on the cutting blade formed on the side ridge portion of the convex curved surface. On one end side, the above axial direction than Convex-curved cutting edge that forms a substantially arc shape and is convex in the tool rotation direction when the tip body is viewed from the position near the other end side of the cutting edge toward the rear end side of the inner periphery of the tool When viewed from a direction in which the convex curved cutting edge portion appears to form a substantially arc shape, the convex curved cutting edge portion intersects an obtuse angle at one end of the convex curved cutting blade portion. A linear cutting edge extending toward the other polygonal surface; Is formed.
[0010]
Therefore, when the tip body is viewed from the position near the one end side of the cutting blade toward the tool outer peripheral rear end side as in the conventional tip, the one end side of the cutting blade is formed so as to form an arc shape. Conversely, the convex curved cutting edge is in the axial direction of the tool body. than When the tip body is viewed from the position near the other end side of the cutting blade toward the rear end side of the inner periphery of the tool, in the tip of the present invention that is formed in a substantially arc shape, the convex curved cutting blade having the substantially arc shape Convex-curved surface formed on the rake face that continues to the part, for example, when this convex-curved surface is a cylindrical surface as in the prior art, its center line is parallel to the axis of the tool body than It will be inclined and arranged so that it may go to the tool inner circumference side as it goes to the tool rear end side from the position near the other end side of the cutting blade. That is, the direction in which the center line of the convex curved surface extends is closer to the direction perpendicular to the cutting edge having the tip angle as described above, so that the other convex curved surface along this direction is the other direction. The curve toward the polygonal surface can be made gentle, so that the chips generated by the convex curved cutting edge portion are guided to the tool inner peripheral side and flowed out, and the chips are divided. Can be prevented, and the cutting edge angle of the cutting edge in the convex curved cutting edge can be ensured to be large, so that the strength of the cutting edge can be improved.
[0011]
Here, when viewed from the direction in which the convex curved cutting edge portion appears to be substantially arc-shaped, that is, the axial direction of the tool body than When the tip body is viewed from the position near the other end side of the cutting edge toward the rear end side of the inner periphery of the tool, the convex cutting edge portion is a circle formed by the other end of the cutting edge about the axis of the tool body. And one end thereof is arranged at a height of 5% to 10% of the diameter D from the other polygonal surface of the chip body, The other end side of the cutting blade is a linear cutting blade portion extending linearly in contact with the convex curved cutting blade portion, and the contact point between the linear cutting blade portion and the one end is The width of the convex curved cutting edge in the direction parallel to the linear cutting edge is preferably 13% to 20% of the diameter D. This is because if the radius is too small, the height of one end is too low, or the width is too large, the convex curved surface is curved even if the direction in which the convex cutting edge portion appears to be substantially arc-shaped as described above. If the above radius is too large, the height of one end is too high, or the width is too small, the entire cutting edge will be almost linear. This is because there is a possibility that the effect of improving the cutting edge strength by providing the convex curved cutting edge portion which is convex in the rotation direction in the vicinity of the axis of the tool body will not be sufficiently achieved.
[0012]
Moreover, the largest load will act on the one end side of the convex curved cutting blade part arrange | positioned among the cutting blades most near the axis line of a tool main body. On the other hand, in the chip of the present invention, When viewed from the direction in which the convex curved cutting edge portion appears to be substantially arc-shaped, the one end side of the cutting blade is connected to the convex curved cutting edge portion at one end of the convex curved cutting blade portion. A straight small cutting edge that intersects the obtuse angle and extends to the other polygonal surface of the chip body is formed to ensure the strength of the cutting edge in this area more reliably. is doing. In addition, the convex curved cutting edge is also in the axial direction of the tool body as described above. than When the tip body is viewed from the position near the other end side of the cutting edge toward the rear end side of the inner periphery of the tool, it may be formed so as to form a substantially arc shape. Short straight lines may be formed so as to be arranged in an arc. Further, the radius of the convex curved cutting edge in such a case can be obtained as, for example, the radius of an arc approximating the plurality of straight lines.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show an embodiment of the present invention. Also in the chip of this embodiment, the chip body 11 is formed of a hard material such as cemented carbide and has a substantially triangular shape, strictly, a pentagonal polygonal flat plate shape, and one of the triangular faces is a rake face. 12 and one side surface is a flank 13, and a cutting edge 14 is formed at a ridge portion of the rake face 12 intersecting the flank 13. Further, the other side surface 15 of the chip body 11 adjacent to the side surface which is the flank 13 is arranged in a direction intersecting the flank 13 at an acute angle at the corner C on the one end 14a side of the cutting blade 14. Yes. Such a tip is also attached to the tip mounting seat 9 formed at the tip of the chip discharge groove 8 of the tool body 7 of the throw-away type drilling tool rotated around the axis O similarly to the conventional tip. The one end 14a of the cutting blade 14 is positioned in the vicinity of the axis O, the other end 14b of the cutting blade 14 is positioned at the outer periphery of the tip of the tool body 1, and the tip toward the tool rear end as the cutting blade 4 moves toward the outer periphery of the tool. As the angle is given, the rake face 12 is directed in the tool rotation T direction, the flank face 13 is directed to the tip of the tool, and the side face 15 is directed to the tool rear end side of the tip mounting seat 9 as the tool outer periphery The other triangular surface which is the seating surface 16 opposite to the rake surface 12 is seated in a state of being in contact with the wall surface 9a extending toward the side, and can be attached and detached by the clamp screw 10 It is attached.
[0014]
Furthermore, also in this embodiment, the rake face 12 has a center line extending in parallel to the seating surface 16 on the corner C side and is curved toward the corner C side while being curved toward the seating surface 16 side. The facing cylindrical surface 12a is formed as a convex curved surface, and a raised surface 12b is formed behind the cylindrical surface 12a, and the cylindrical surface 12a and the flank are disposed on one end 14a side of the cutting edge 14. A convex cutting edge portion 14A is formed at a crossing ridge line portion with 13 and the other end 14b side of the cutting blade 14 is a straight line extending smoothly in parallel with the seating surface 16 while continuously connecting to the convex bending cutting blade portion 14A. The cutting edge portion 14B is formed. Further, on the rake face 12 other than the cylindrical face 12a and the raised face 12b, there is formed an inclined face 12c that continues to the cutting edge 14 and moves toward the seating face 16 with a constant inclination as the distance from the cutting edge 14 increases. In addition, a flat surface 12e parallel to the seating surface 16 is formed on the side opposite to the cutting edge 14 across the inclined surface 12c via a breaker wall surface 12d that is bulged from the inclined surface 12c. The width of the inclined surface 12c and the breaker wall surface 12d in the direction perpendicular to the cutting edge 4 is gradually increased along the cutting edge 14 toward the other end 14b. Furthermore, the side surface 17 of the chip body 11 intersecting the flank 13 on the other end 14b side of the cutting blade 14 intersects the flank 13 at an obtuse angle, and the chip body 11 is attached to the tool body 7 as described above. In the state of being attached to the tip mounting seat 9, the portion on the tool rotation direction T side becomes a cylindrical surface centered on the axis O of the tool body 7, and the axis O is seen in a plan view facing the rake face 12. It extends in parallel and forms a margin for the drilling tool. Further, a mounting hole 18 through which the clamp screw 10 is inserted penetrates from the rake face 12 to the seating face 16.
[0015]
In the above-described conventional chip, the center line of the cylindrical surface 2a is parallel to the side surface 5 intersecting the flank 3 at an acute angle at the corner C on the one end 4a side of the cutting edge 4. On the other hand, in the chip of this embodiment, the center line of the cylindrical surface 12a intersects the flank 13 with the obtuse angle on the other end 14b side of the cutting edge 14 in the plan view facing the rake surface 12. Parallel to than The side surface 15 that is inclined toward the side surface 17 side as it goes toward the flank surface 13 and intersects the flank surface 13 at an acute angle at the corner portion C on the one end 14a side of the cutting edge 14 is formed from the corner portion C. It arrange | positions so that it may extend in the direction which cross | intersects in the distant side. Therefore, even when such a tip is attached to the tool body 7 as described above, in the above-described conventional tip, the center line of the cylindrical surface 2a is inclined toward the tool outer peripheral side toward the tool rear end side. The direction in which the convex cutting edge 4A on the one end 4a side of the cutting edge 4 appears to form an arc is the axis of the tool body 7 as indicated by the arrow E in FIG. This is the direction in which the tip body 1 was viewed from the position closer to the one end 4a side of the cutting blade 4 toward the tool outer peripheral rear end side than when viewed from the tool front end side along the O direction. In the form of the tip, when the tip body 11 is viewed from the tool tip side in the direction of the axis O as indicated by the arrow F in FIG. than, When the tip body 11 is viewed from the position near the other end 14b side of the cutting blade 14 toward the rear end side of the inner periphery of the tool as indicated by the arrow line G or arrow line H in FIG. 1, the convex curved cutting edge portion 14A. Has an arc shape and is convex in the tool rotation direction T.
[0016]
In addition, in the case where the convex curved cutting edge portion 14A is viewed from a direction that looks like an arc shape in this way, , The radius R of the arc formed by the convex curved cutting edge portion 14A is the diameter D of the circle formed by the other end 14b of the cutting edge 14 about the axis O of the tool body 11, that is, outside the cutting edge of the throw-away drilling tool. It is 28% to 42% of the diameter. At this time, one end 14c of the convex curved cutting edge portion 14A is disposed at a height A of 5% to 10% of the diameter D from the other polygonal surface which is the seating surface 16 of the chip body 11. Further, the convex curved cutting edge 14A in a direction parallel to the linear cutting edge 14B between the contact 14d between the convex curved cutting edge 14A and the linear cutting edge 14B and the one end 14c. The width B is set to 13% to 20% of the diameter D. Further, a narrow flat surface 15a that is perpendicular to the seating surface 16 is formed so as to extend along the side surface 15 at a substantially central portion of the side surface 15 in the height A direction. By intersecting with the flank 13, the one end 14 a of the cutting edge 14 is crossed at an obtuse angle with the convex cutting edge 14 A at the one end 14 c of the convex cutting edge 14 A toward the seating surface 16. An extending linear cutting edge portion 14C is formed. A side surface 15 of the portion between the flat surface 15a and the seating surface 16 and the flat surface 12e of the rake face 12 intersects the

flat surfaces

15a and 12e and the seating surface 16 at an obtuse angle.
[0017]
Therefore, in the tip configured as described above, when the tip is attached to the tool body 7 of the throw-away type drilling tool as described above, the convex curve on the one end 14a side of the cutting edge 14 on the inner peripheral side of the tool. -Shaped cutting edge portion 14A is in the direction of axis O of tool body 7 than When the chip body 11 is viewed from the position near the other end 14b side of the cutting edge 14 toward the rear end side of the inner periphery of the tool, it forms an arc shape, and the rake face continues to the convex curved cutting edge portion 14A. The cylindrical surface 12a as a convex curved surface disposed on the inner peripheral side of the tool tip 12 is also parallel to the axis O of the tool body 7 as described above. than The cutting edge 14 is disposed so as to be inclined toward the inner peripheral side of the tool from the position closer to the other end 14b side toward the tool rear end side. That is, the direction in which the center line of the cylindrical surface 12a extends becomes closer to the direction perpendicular to the cutting edge 14 provided with the tip angle so as to go to the tool rear end side toward the tool outer peripheral side. Since the curvature of the cylindrical surface 12a toward the seating surface 16 in the direction orthogonal to the cutting edge 14 can be made gentle, it is generated by the convex curved cutting edge portion 14A among the chips generated by the cutting edge 14. Can be prevented from being separated from the portion generated by the linear cutting edge portion 14B by being guided to the inner peripheral side of the tool, and thus the separated chips cause clogging at the center of the tool tip. Can be prevented.
[0018]
Here, FIGS. 3E to 3H are the above-described cases where the convex cutting edge portion 14A has an arc shape with an equal radius when viewed from the directions of arrows E to H in FIG. 3 shows an XX cross section on the corner C side of the chip body 11 orthogonal to the cutting edge 14 provided with a tip angle as shown in FIG. When the tip body 11 is viewed from the tool tip side in the direction of the axis O It is XX sectional drawing of the chip | tip of the reference example whose convex-curved cutting-blade part 14A has comprised circular arc shape, 3 (G) and 3 (H), as indicated by arrows G and H in FIG. 1, the tip body 11 from the position closer to the other end 14b side of the cutting edge 14 than the arrow F toward the rear end side of the inner periphery of the tool. 14A is an XX cross-sectional view of the tip of the above embodiment in which the convex cutting edge portion 14A has an arc shape, while FIG. 3E is along the axis O direction of the tool body 7. When the tip body 11 is viewed from the position closer to the one end 14a side of the cutting blade 14 toward the tool outer peripheral rear end side than when viewed from the tool front end side, the convex curved cutting blade portion 14A forms an arc shape. This corresponds to the XX cross section of a conventional chip. However, as shown in FIGS. 3E to 3H, in FIG. 3E corresponding to the cross section of the conventional chip, the seating surface 16 of the cylindrical surface 12a along the direction orthogonal to the cutting edge 14 is obtained. Therefore, chips generated by the convex curved cutting edge portion 14A are drawn to the inner peripheral side of the tool so as to be guided to the cylindrical surface 12a by this bending, and generated by the linear cutting edge portion 14B. In the cross section of the chip according to the present embodiment, even if the radius of the circular arc formed by the convex cutting edge portion 14A is the same, the chip is cut off from the cut chip portion and the chip is clogged. (G), As shown in (H), the curvature of the cylindrical surface 12a is small, so that the chips are divided into a portion generated by the convex curved cutting edge portion 14A and a portion generated by the linear cutting blade portion 14B. In combination with the effect of the inclined surface 12c and the breaker wall surface 12d provided on the rake face 12, the chip discharge groove 8 is curled around the corner C as a whole without causing chip clogging. It is sent out and discharged and processed smoothly.
[0019]
In addition, since the curvature of the cylindrical surface 12a along the direction orthogonal to the cutting edge 14 becomes gentle in this way, the chip having the above-described configuration also has the configuration shown in FIG. (G), As shown in FIG. 3H, the cutting edge angle α of the cutting edge 14 (convex curved cutting edge portion 14A) in the cross section along the direction perpendicular to the cutting edge 14 is converted to the conventional tip shown in FIG. It becomes possible to make it larger. For this reason, it becomes possible to give a high cutting edge strength to the convex curved cutting edge portion 14A on the one end 14a side of the cutting blade 14 to be disposed in the vicinity of the axis O at the center of the tool tip. Combined with the fact that the cutting edge portion 14A is convex in the tool rotation direction T, the rotational speed is reduced, so that a large load acts on the one end 14a side of the cutting edge 14 in the vicinity of the axis O where chipping or chipping occurs. Can be prevented and stable drilling can be promoted by extending the chip life.
[0020]
In addition, in the present embodiment, a straight small cutting edge portion 14C is further formed at one end 14c of the convex curved cutting edge portion 14A. Therefore, the one end 14a of the cutting blade 14 is formed on the small cutting edge portion 14C. Will be formed. The small cutting edge portion 14C intersects the convex curved cutting edge portion 14A at an obtuse angle at one end 14c when viewed from the direction in which the convex cutting edge portion 14A appears to form an arc shape. The convex curved cutting edge portion 14A, which is formed so as to extend toward the seating surface 16 side of the chip body 11 and thus has a high cutting edge strength as described above, is particularly arranged in the vicinity of the axis O and is the largest. Since the end 14c to which the load acts is given a higher cutting edge strength, according to the chip of this embodiment, chipping and chipping on the one end 14a side of the cutting edge 14 can be more reliably prevented and the chip life can be further increased. It is possible to encourage extension.
[0021]
In the present embodiment, as described above, when the convex curved cutting edge portion 14A is viewed from a direction that appears to form an arc shape, the radius R of this arc is the other end 14b of the cutting blade 14 around the axis O. Further, the one end 14c of the convex cutting edge portion 14A is higher than the seating surface 16 of the chip body 11 by 5% to 10% of the diameter D so as to be 28% to 42% of the diameter D of the circle. Further, the width B of the convex curved cutting edge portion 14A from the one end 14c to the contact point 14d with the linear cutting edge portion 14B in the direction view is 13% to 20% of the diameter D so as to be positioned at A. The radius R is too small with respect to the diameter D, that is, the outer diameter of the cutting edge 14, or the height A of the one end 14c of the convex cutting edge 14A is low. If it is too large or the width B is too large, it is convex as described above. Even if the direction in which the cutting edge portion 14A looks like an arc is parallel to the axis O or closer to the other end 14b side of the cutting edge 14, the cylindrical face 12a along the direction perpendicular to the cutting edge 14 is directed to the seating surface 16 side. This is because there is a risk that the curving of the steel may become sharp and sharp, and the fragmentation of chips cannot be reliably prevented. On the other hand, if the radius R is too large, the height A of the one end 14c is too high, or the width B is too small, the curvature of the convex cutting edge portion 14A becomes too small, and the entire cutting edge 14 is formed. The effect itself of improving the cutting edge strength by providing the convex curved cutting edge portion 14A in the vicinity of the axis O of the tool main body 7 so as to be convex in the tool rotation direction T is rather reversed. Since there is a possibility that it will not be successful enough, it is desirable that the radius R, height A, and width B of these convex curved cutting edge portions 14A are set as in the present embodiment, and the size of the diameter D is further set. Accordingly, it is more desirable to set within the range shown in Table 1 below. However, in the columns of height A, width B, and radius R in Table 1, the upper row shows an example set value for the diameter D, and the lower row shows a suitable ratio for the diameter D.
[0022]
[Table 1]

[0023]
Further, in the present embodiment, when the cutting main body 11 is viewed from the tip end side of the tool body 7 with respect to the axis O direction of the tool body 7 or from the position closer to the other end 14b side of the cutting blade 14 than this, When the chip body 11 is viewed toward the rear end side, it is formed in an arc shape so as to bend in the tool rotation direction T. This convex cutting edge portion 14A is viewed from this direction. For example, the convex cutting edge portion 14A may be formed by connecting a plurality of short straight lines in an arc shape. In addition, the radius R of the convex curved cutting edge portion 14A in such a case is obtained as a radius of an arc that approximates the plurality of straight lines. Further, in the present embodiment, the convex curved cutting edge portion 14A is formed only on the one end 14a side of the cutting blade 14, but the entire length of the cutting blade 14 may be the convex curved cutting blade portion 14A. .
[0024]
【The invention's effect】
As described above, according to the present invention, the convex curved cutting blade portion formed on one end side of the cutting blade and disposed in the vicinity of the rotation axis at the tip of the tool body is arranged in this axial direction. than When viewed from the position near the other end side of the cutting edge toward the rear end side of the inner periphery of the tool, it is formed in a substantially arc shape so as to be convex in the tool rotation direction. The convex curved surface of the continuous rake face can moderate the curvature toward the seating surface along the direction perpendicular to the cutting edge provided with the tip angle. Prevents the situation where the generated chips are divided and clogged, or the cutting edge strength of the convex cutting edge part is lost and chipping or chipping occurs, extending the chip life and smoothing the chips. It is possible to facilitate processing and stable drilling.
[Brief description of the drawings]
FIG. 1 is a plan view of an embodiment of the present invention as seen from a direction facing a rake face 12 of a throw-away tip for drilling attached to the tip of a tool body 7. FIG.
2 is a side view of the throw-away tip for drilling shown in FIG. 1 as viewed in the direction of arrow F. FIG.
FIGS. 3E to 3H are cross-sectional views taken along line XX when the convex curved cutting edge portion 14A has an arc shape when viewed in the direction of arrows E to H in FIG. However, (E) corresponds to a conventional throw-away tip for drilling.
FIG. 4 is a plan view seen from a direction facing a rake face 2 of a conventional throw-away tip for drilling.
5 is a side view of a conventional throwing tip for drilling as viewed in the direction of arrow E in FIGS. 4 and 6. FIG.
FIG. 6 is a plan view of a throw-away drilling tool to which a conventional throw-away tip for drilling is attached.
[Explanation of symbols]
7 Tool body
11 Chip body
12 Rake face
12a Cylindrical surface (convex curved surface)
13 Flank
14 Cutting blade
14A Convex cutting edge
14B Straight cutting edge
14C small cutting edge
14a One end of the cutting edge 14
14b The other end of the cutting blade 14
14c One end of convex curved cutting edge portion 14A
14d Contact point between convex cutting edge 14A and linear cutting edge 14B
16 Seating surface (the other polygonal surface of the chip body)
O Tool body axis 7
T Tool rotation direction
D Diameter of the circle formed around the axis O by the other end 14b of the cutting blade 14
R Radius of the convex cutting edge 14A when viewed from the direction of the arc
A Height from the seating surface 16 of the one end 14c of the convex curved cutting edge portion 14A
B Width of convex curved cutting edge 14A when viewed from the direction of the arc

Claims

概略多角形平板状をなすチップ本体の一方の多角形面がすくい面とされ、このすくい面の辺稜部に形成された切刃の一端を、軸線回りに回転される穴明け工具の工具本体先端の上記軸線近傍に位置させるとともに、上記切刃の他端を上記工具本体の先端外周に位置させ、上記切刃に工具外周側に向かうに従い工具後端側に向かう先端角が与えられて上記すくい面が工具回転方向に向けられるように取り付けられる穴明け加工用スローアウェイチップであって、上記切刃の少なくとも一端側の上記すくい面上には、この切刃の一端側に向かうに従い上記チップ本体の他方の多角形面側に湾曲する凸曲状面が形成されていて、この凸曲状面の辺稜部に形成される上記切刃の一端側に、上記軸線方向よりも上記切刃の他端側寄りの位置から工具内周後端側に向けて上記チップ本体を見た場合に略円弧状をなして上記工具回転方向に凸となる凸曲状切刃部と、この凸曲状切刃部が略円弧状をなすように見える方向から見て、上記凸曲状切刃部の一端において該凸曲状切刃部に鈍角に交差して上記チップ本体の他方の多角形面側に延びる直線状の小切刃部とが形成されていることを特徴とする穴明け加工用スローアウェイチップ。A tool body of a drilling tool in which one polygonal surface of a chip body having a substantially polygonal flat plate shape is a rake face, and one end of a cutting blade formed on a side ridge portion of the rake face is rotated around an axis. The tip is positioned in the vicinity of the axis, the other end of the cutting blade is positioned on the outer periphery of the tip of the tool body, and a tip angle toward the tool rear end is given to the cutting blade toward the outer periphery of the tool. A throw-away tip for drilling that is attached so that the rake face is directed in the direction of rotation of the tool, and on the rake face on at least one end side of the cutting edge, the tip is arranged toward the one end side of the cutting edge. A convex curved surface that is curved on the other polygonal surface side of the main body is formed, and the cutting blade is formed on one end side of the cutting blade formed on the side ridge portion of the convex curved surface rather than the axial direction. From the position near the other end of the tool A convex curved shape cutting edge that protrudes above the tool rotation direction a substantially arc shape when viewed the chip body toward the end side, as the convex curved shape cutting edge is formed in a substantially arc shape A linear small cutting edge portion extending at an obtuse angle to the convex curved cutting edge portion at one end of the convex curved cutting edge portion and extending to the other polygonal surface side of the chip body when viewed from the viewing direction. A throw-away tip for drilling, characterized by being formed.

上記凸曲状切刃部が略円弧状をなすように見える方向から見た場合において、該凸曲状切刃部は、上記切刃の他端が上記工具本体の軸線回りになす円の直径Ｄの２８％〜４２％の半径の略円弧状とされるとともに、その一端が、上記チップ本体の他方の多角形面から上記直径Ｄの５％〜１０％の高さに配置され、かつ、上記切刃の他端側はこの凸曲状切刃部に接して直線状に延びる直線状切刃部とされて、この直線状切刃部との接点と上記一端との間の該直線状切刃部に平行な方向における上記凸曲状切刃部の幅が、上記直径Ｄの１３％〜２０％とされていることを特徴とする請求項１に記載の穴明け加工用スローアウェイチップ。 When viewed from a direction in which the convex curved cutting edge portion appears to be substantially arc-shaped, the convex curved cutting edge portion is a diameter of a circle formed by the other end of the cutting blade around the axis of the tool body. D has a substantially arc shape with a radius of 28% to 42% of D, and one end thereof is disposed at a height of 5% to 10% of the diameter D from the other polygonal surface of the chip body, and The other end side of the cutting blade is a linear cutting blade portion extending linearly in contact with the convex curved cutting blade portion, and the linear shape between the contact point with the linear cutting blade portion and the one end. The throw-away tip for drilling according to claim 1, wherein a width of the convex curved cutting blade portion in a direction parallel to the cutting blade portion is 13% to 20% of the diameter D. .