JP3539210B2

JP3539210B2 - Head exchangeable cutting tool and method of manufacturing the same

Info

Publication number: JP3539210B2
Application number: JP15175398A
Authority: JP
Inventors: 高正嶋野; 昌之大川; 和哉山崎
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 1998-06-01
Filing date: 1998-06-01
Publication date: 2004-07-07
Anticipated expiration: 2018-06-01
Also published as: JPH11347811A

Description

【０００１】
【発明の属する技術分野】
本発明はシャンク部に対してヘッド部を着脱交換可能に装着したヘッド交換式切削工具及びその製造方法に関する。
【０００２】
【従来の技術】
従来、この種の切削工具の一例として、図１０及び図１１に示すようなボーリングバーがある。
このボーリングバー１は、図示しないマシニングセンタなどに保持されるシャンク部２に対してスローアウェイチップ３が取り付けられたヘッド部４が着脱交換可能に嵌合されて形成されている。この場合、シャンク部２は例えば剛性が高く高価な超硬合金で形成され、ヘッド部４は切屑の擦過などで摩耗や損傷しやすいために低廉なスチール等を用いて着脱交換可能とされている。
またヘッド部４を交換可能とすることで異なる種類の切刃を備えたヘッド部を装着できるようにしている。
このようなボーリングバー１のヘッド部４とシャンク部２の嵌合部５の構造は、例えばシャンク部２の先端面６の中央部に形成された凸部６ａを角柱形状に形成すると共に、ヘッド部４の基端面７の穴部７ａを角柱状凹部に形成して、凸部６ａを穴部７ａに嵌合させて先端面６と基端面７を当接させた状態でその周囲をろう付けするようになっている。
或いは、凸部６ａを略円柱状に形成して雄ねじを切り、穴部７ａを略円柱状の凹部に形成して凸部６ａの雄ねじと螺合する雌ねじを形成して嵌合するようにしていた。
また他の嵌合構造として、凸部６ａと穴部７ａを焼き嵌めしたものもあった。
【０００３】
【発明が解決しようとする課題】
しかしながら、このような嵌合部５の構造では、スローアウェイチップ３の切刃で回転する被削材の穴加工を行う際、切削抵抗の主分力が切刃に略直交する方向にかかり、これを主として凸部６ａ及び穴部７ａで受けるために比較的剛性の小さい鋼製のヘッド部４にかかる負荷が大きく、前者の場合には角柱状の穴部７ａの角に亀裂が入り、後者の場合には雌ねじと雄ねじの螺合部分が損傷しやすい等の欠点があり、ボーリングバー１の剛性が小さく、工具寿命が短かった。
また焼き嵌めの場合においても、ヘッド部４の穴部７ａを加熱して凸部６ａに嵌合した後、穴部７ａが常温まで温度低下して収縮すると、収縮誤差によってヘッド部４の基端面７がシャンク部２の先端面６から離間することがあり、そのためにボーリングバー１の保持強度と剛性が小さく、工具寿命が短かった。
【０００４】
本発明は、上述する問題点に鑑みてなされたもので、工具の剛性が高く工具寿命を向上できるヘッド交換式切削工具を提供することを目的とする。
【０００５】
【課題を解決するための手段】
本発明によるヘッド交換式切削工具は、切刃を備えたヘッド部とシャンク部とが嵌合されてなり、前記ヘッド部を交換可能としたヘッド交換式切削工具において、前記ヘッド部とシャンク部の一方に軸部とテーパ面を備え、他方に前記軸部に嵌合する穴部と前記テーパ面に嵌合するテーパ状部とを備え、
前記テーパ部が前記工具本体の中心軸線に対して傾斜させられると共に、前記軸部と穴部、前記テーパ面とテーパ状部のそれぞれ少なくともいずれか一方に締め代が設けられ、前記軸部と前記穴部の一方にはキーが設けられ、他方には前記キーに嵌合するキー溝が形成されているともに、前記キー溝の長手方向の面である側面が前記切刃の前切刃と略平行となるように形成されていることを特徴とする。
ヘッド部とシャンク部とを焼き嵌め嵌合して構成されているために、軸部と穴部、そしてテーパ面とテーパ状部が締め代圧によってそれぞれ押圧固定され、しかも２面で互いに拘束されるために互いの保持強度が高く、工具剛性が向上する。また切削抵抗による送り分力と主分力を受けて動剛性も向上する。
【０００６】
また軸部と穴部の一方にキーが設けられ、他方にキーに嵌合するキー溝が形成されていてもよい。
切刃による切削抵抗の主分力や送り分力がヘッド部を捻るようにかかっても、互いに嵌合するキーとキー溝によってその一部を受けることができて切削時の回転防止機能と工具の動剛性を強化でき、焼き嵌めによる二面拘束とキー及びキー溝嵌合とでシャンク部とヘッド部の一体化を高めて工具剛性を向上できる。
また、キー及びキー溝は、ヘッド部の切刃にかかる切削抵抗の主分力に略直交する方向に延在するようにしてもよい。
特にボーリングバーなどの旋削工具においては、工作機械等へのシャンク部の取り付け位置に対して切刃の位置決めをキーとキー溝とによって行うことができ、また切削抵抗の主分力を略直交する方向に配置されたキー及びキー溝で受けることになるために切削時の動剛性が一層向上する。
【０００７】
本発明によるヘッド交換式切削工具の製造方法は、切刃を備えたヘッド部とシャンク部とが嵌合されてなり、前記ヘッド部を交換可能としたヘッド交換式切削工具において、前記ヘッド部とシャンク部の一方に軸部とテーパ面を備え、他方に前記軸部に嵌合する穴部と前記テーパ面に嵌合するテーパ状部とを備え、前記軸部と穴部、前記テーパ面とテーパ状部のそれぞれ少なくともいずれか一方に締め代が設けられていて、前記軸部と穴部の一方にはキーが設けられ、他方には前記キーに嵌合するキー溝が形成されているともに前記キー溝の長手方向の面である側面が前記切刃の前切刃と略平行となるように形成され、前記穴部及び前記テーパ状部を加熱して前記軸部及び前記テーパ面と焼き嵌めするとともに前記キーと前記キー溝とを嵌合することを特徴とする。
穴部と軸部、そしてテーパ状部とテーパ面をそれぞれ焼き嵌めすることで締め代圧によって二面拘束することができ、工具の剛性を高めることができる。尚、焼き嵌めに際して、同時に軸部及びテーパ面を常温より冷却することとすれば、嵌合がより容易且つ確実になる。
【０００８】
また、穴部及びテーパ状部を軸部及びテーパ面に焼き嵌めする際、テーパ状部は収縮が進行する状態でテーパ面に嵌合させるようにしてもよい。
常温に戻った際に収縮寸法の誤差が生じることがあるが、テーパ状部とテーパ面は、ずれた状態でもずれが締め代寸法の範囲内であれば互いに当接して締め代圧が作用するから、両者の間に隙間が形成されることなく面拘束を確保できる。
尚、穴部と軸部の一方にキーが設けられ、他方にキーと嵌合するキー溝が設けられていることで焼き嵌め時に嵌合でき、切刃の位置決めと切削抵抗に対する回転防止機能が働き、工具剛性が一層向上する。
【０００９】
【発明の実施の形態】
以下、本発明の実施の形態について添付図面により説明する。図１乃至図５は第一の実施の形態によるボーリングバーに関するものであり、図１はボーリングバーの一部を断面で示す要部平面図、図２は図１に示すボーリングバーのＢ−Ｂ線断面図、図３は図１に示すボーリングバーのＣ部拡大図、図４はシャンク部を示すもので、（ａ）は側面図、（ｂ）は底面図、図５はヘッド部を示すもので、（ａ）は側面図、（ｂ）は底面図である。
図１乃至図３に示すボーリングバー１０は、シャンク部１１とヘッド部１２が嵌合部１３で焼き嵌め嵌合されて一体化されてなるものである。
特に図４に示すシャンク部１１は例えば超硬合金で構成され、略円柱状で、その外周面１１ａには図示しないマシニングセンタ等の工作機械に所定位置で保持されるための平面状の保持部１４が長手方向に沿って形成されている。
嵌合部１３の一方を成すシャンク部１１の（ヘッド部１２側の）先端部１５には、外周面１１ａより小径とされた同心で略円柱状の軸部１６が形成され、この軸部１６は円筒形状の周面１６ａと円形の先端面１６ｂとを有し、先端面１６ｂには略板状のキー１７が突出形成されている。キー１７はその長手方向の側面１７ａが保持面１４と略平行な位置に設けられ、ヘッド部１２の切刃の位置決めに用いられる。
また軸部１６と外周面１１ａとの間にはテーパ面１８がリング状に形成されている。テーパ面１８の傾斜角度θはシャンク部１１の中心軸Ｏに対する適宜の鋭角とされ、９０°に近い角度の方が好ましい（図３及び図４参照）。
【００１０】
特に図５に示すヘッド部１２は例えばスチール製とされ、略円柱状に形成されると共に先端部が切り欠かれて凹部２０とされ、その先端角部に凹状のチップ取付座２１が形成されてスローアウェイチップ２２がボルト等で固定されている。スローアウェイチップ２２の上面２３の先端側の稜辺は前切刃２３ａと横切刃２３ｂとされている。
ヘッド部１２の基端部２５は嵌合部１３の他方をなし、基端部２５にはシャンク部１１の軸部１６を焼き嵌め嵌合するための同心状に形成された略円筒状の穴部２６が形成されている。この穴部２６はヘッド部１２の外周面をなす円筒部によって概略構成され、内周面２６ａと底面２６ｂとを備え、底面２６ｂにはシャンク部１１のキー１７と嵌合するキー溝２７が形成されている。また穴部２６の開口部をなす自由端部は断面テーパ状とされたリング状のテーパ状部２８が形成されている。
このテーパ状部２８は図３に示すようにシャンク部１１のテーパ面１８と焼き嵌め嵌合されており、テーパ状部２８の中心軸Ｏに対する傾斜角度はテーパ面１８とほぼ同一の角度θに設定されている。
【００１１】
また穴部２６の内周面２６ａについて、軸部１６の外周面１６ａと焼き嵌めするために、常温において焼き嵌めの締め代分（例えば３０μｍ）だけ軸部１６の外径よりも小さい内径寸法に設定されている。また穴部２６のテーパ状部２８についても同様に軸部１６のテーパ面１８の対応する外径寸法よりも焼き嵌めの締め代分（例えば３０μｍ）だけ小さい内径寸法に設定されている。
尚、これとは逆に軸部１６の外周面１６ａとテーパ面１８の外形寸法を、穴部２６の内周面２６ａ及びテーパ状部２８の対応する内径寸法よりも締め代分だけ大きく形成してもよく、或いは両方に締め代を形成してもよい。
【００１２】
また、ヘッド部１２のキー溝２７は略板状の溝とされ、ボーリングバー１０で回転する被削材Ｗの穴加工を行う際、スローアウェイチップ２２の前切刃２３ａ及び横切刃２３ｂで受ける切削抵抗の主分力に直交する方向に、キー溝２７の長手方向の面である側面２７ａが位置している。換言すれば、図１に示すように前切刃２３ａ及び横切刃２３ｂによる被削材Ｗの切削加工ポイントにおける被削材Ｗの加工穴ｈの接線方向に主分力が生じ、この主分力に直交する方向にキー溝２７の側面２７ａが位置している。
またキー溝２７の側面２７ａと前切刃２３ａが略平行に位置することで、シャンク部１１に対する切刃２３ａ，２３ｂの位置決めがされている。
これによって、シャンク部１１の先端部１５とヘッド部１２の基端部２５が焼き嵌め嵌合された状態で、互いに嵌合する略板状のキー１７及びキー溝２７の各側面１７ａ，２７ａで切削抵抗の主分力を受けることができるようになっている。
【００１３】
本実施の形態によるボーリングバー１０は上述のように構成されており、次にその製造方法について説明する。
図４及び図５に示すようにヘッド部１２とシャンク部１１が分離された状態において、常温よりもヘッド部１２を加熱すると共にシャンク部１１を冷却した状態で、キー１７とキー溝２７の側面１７ａ，２７ａを一致させてヘッド部１２の基端部２５とシャンク部１１の先端部１５を焼き嵌め嵌合する。この場合、キー１７がキー溝２７と嵌合することで、ヘッド部１２の切刃２３ａ，２３ｂはシャンク部１１の保持部１４に対して周方向に位置決めされることになる。
そして、シャンク部１１の軸部１６がヘッド部１２の穴部２６内に嵌合される際、ヘッド部１２とシャンク１１が徐々に常温に戻ると、穴部２６は収縮して縮径され軸部１６は拡径されるために、穴部２６の内周面２６ａに設けられた締め代の締め代圧によって軸部１６は穴部２６と強固に焼き嵌めされる。
【００１４】
これと同時に、ヘッド部１２の穴部２６の収縮が進行する状態で、穴部２６のテーパ状部２８がテーパ面１８に押しつけられ、締め代圧によって焼き嵌めされる。
この時、常温に戻る際の、ヘッド部１２の収縮とシャンク部１１の膨張による寸法誤差によって、テーパ状部２８とテーパ面１８との当接面が設計時と比較して若干の位置ずれを生じても、締め代寸法の範囲であれば、互いにテーパ状の面をなすためにずれた位置で面接触して締め代圧によって互いに面拘束される。この場合の締め代圧は位置ずれの分だけ設計時の締め代圧より小さくなるが、軸部１６と穴部２６との面拘束と合わせて二面拘束を実現できてボーリングバー１０全体の剛性を高くできる。
このようにして図１乃至図３に示すボーリングバー１０が製造される。
尚、上述の製造方法に代えてヘッド部１２の収縮が進行する前にシャンク部１１と焼き嵌めさせて、嵌合終了後に収縮させるようにしてもよい。
【００１５】
次にこのボーリングバー１０を用いて図１に示すように被削材Ｗの中ぐり加工を行う。
回転する被削材Ｗの下穴ｈが前切刃２３ａ及び横切刃２３ｂで切削されて穴加工される。この時、切刃２３ａ，２３ｂに作用する切削抵抗の主分力は切削加工ポイントにおける接線方向（図１において紙面に略直交する方向であって上から下方向）、例えば切刃２３ａ，２３ｂに略直交する方向に発生する。
そのため、主分力を受けるヘッド部１２がシャンク部１１に対して捻れる方向に応力が働くが、この主分力は嵌合部１３における主分力に略直交するキー１７及びキー溝２７の当接する各側面１７ａ，２７ａで受けることができる。同時に切削抵抗によるヘッド１２の回転防止機能を果たすこともできる。
また被削材Ｗ（または）ボーリングバー１０の送り方向に働く送り分力Ｆによっても、ヘッド１２を水平方向に捻る応力が働くが、これについては主分力と共に、穴部２６の内周面２６ａ及び軸部１６の外周面１６ａの拘束面と、テーパ状部２８及びテーパ面１８の拘束面とによって受けることができ、この点でもボーリングバー１０の動剛性が高くなる。
【００１６】
上述のように本実施の形態によれば、ヘッド部１２とシャンク部１１を、穴部２６の内周面２６ａ及び軸部１６の外周面１６ａと、テーパ状部２８及びテーパ面１８とで焼き嵌めしたから、ヘッド部１２の着脱交換が可能であり、異なる種類の刃先を備えたヘッド部１２やヘッド部１２の損傷に対応できる。
しかも、焼き嵌めによって二面拘束でき、切削抵抗の主分力や送り分力を受けることができてボーリングバー１０の剛性及び動剛性を向上できる。また嵌合部１３にキー及びキー溝嵌合を付加したことで、シャンク部１１の平面状の保持部１４に対して切刃２３ａ，２３ｂの位置決め精度を確保でき、更に切削抵抗の主分力受けと回転防止機能を強化でき、動剛性を一層向上できる。
また焼き嵌めによる二面拘束のうち、一の面拘束をテーパ状部２８とテーパ面１８とで行うために、ヘッド部１２及びシャンク部１１の収縮または膨張誤差によってテーパ状部２８とテーパ面１８の当接位置がずれても締め代圧によって互いに焼き嵌め結合でき、確実に工具剛性を向上できる。
【００１７】
次に本発明の第二の実施の形態を図６乃至図９により、上述の第一の実施の形態と同一の部分には同一の符号を用いて説明する。
図６はボーリングバーの一部破断正面図、図７は図６のＥ部拡大図、図８はシャンク部を示すもので、（ａ）は正面図、（ｂ）は先端面図、図９はヘッド部を示すもので、（ａ）は正面図、（ｂ）は底面図である。
本実施の形態によるボーリングバー３０では、図６及び図８に示すシャンク部１１の先端部１５において、外周面１１ａと軸部１６の接続面３１は中心軸Ｏに略直交するリング状の平面とされている。一方、軸部１６とキー１７との間には全周に亘ってテーパ面３２が形成され、テーパ面３２につづく小径の先端面３２ａ上に略板状のキー１７が形成されている。
また図６及び図９に示すヘッド部１２の基端部２５には穴部２６が形成され、その自由端部３３は中心軸Ｏに略直交するリング状の平面とされている。また穴部２６の内周面２６ａと底面２６ｂとの間にリング状のテーパ状部３４が形成されており、このテーパ状部３４はテーパ面３２と焼き嵌め嵌合されるようになっている。この場合、テーパ状部３４（またはテーパ面３２もしくは両方）に締め代が形成され、対応する内径がテーパ面３２の外径より締め代分だけ小さく設定されている。
穴部２６のテーパ状部３４と軸部１６のテーパ面３２は、図７に示すようにそれぞれ中心軸Ｏに対する傾斜角θが設定されている。
そして、底面２６ｂに略板状のキー溝２７が形成されている。
【００１８】
本実施の形態においても、穴部２６の内周面２６ａと軸部１６の外周面１６ａ、そしてテーパ状部３４とテーパ面３２について、焼き嵌めによって二面拘束できる。この場合、ヘッド部１２とシャンク部１１を焼き嵌めする際、ヘッド部１２の穴部２６の自由端部３３とシャンク部１１の接続面３２とに収縮誤差または膨張誤差が生じて隙間が生じても、上述のように二面拘束を達成できるから、確実に工具の剛性を向上できる。
【００１９】
尚、上述の実施の形態では、ヘッド部１２の材質をスチール、シャンク部１１の材質を超硬合金としたが、各部材の材質はこれに限定されることなく各種のものを採用できる。また必ずしも互いに異なる材質である必要はなく、同一の材質としてもよい。
また上述の説明では、シャンク部１１に軸部１６及びテーパ面１８，３２、ヘッド部１２に穴部２６及びテーパ状部２８，３４を形成したが、これとは逆にシャンク部１１に穴部２６及びテーパ状部２８，３４を形成し、ヘッド部１２に軸部１６及びテーパ面１８，３２を形成して互いに焼き嵌めするようにしてもよい。
また、上述の実施の形態では、ボーリングバー１０について説明したが、これに限定されることなく、各種の切削工具、例えばバイト等他の旋削工具や、エンドミルやドリルなどの各種転削工具等にもに本発明を採用できる。
【００２０】
【発明の効果】
以上説明したように、本発明に係るヘッド交換式切削工具は、ヘッド部とシャンク部の一方は軸部とテーパ面を備え、他方は軸部に嵌合する穴部とテーパ面に嵌合するテーパ状部とを備え、軸部と穴部、テーパ面とテーパ状部のそれぞれ少なくともいずれか一方に締め代が設けられているから、ヘッド部とシャンク部とを焼き嵌め嵌合して、軸部と穴部、そしてテーパ面とテーパ状部が締め代圧によってそれぞれ押圧固定され、しかも二面で互いに拘束されるために互いの保持強度が高く、工具剛性が向上する。また切削抵抗による送り分力と主分力を受けて工具の動剛性も向上する。
【００２１】
また軸部と穴部の一方にキーが設けられ、他方にキーに嵌合するキー溝が形成されているから、切刃による切削抵抗の主分力や送り分力がヘッド部を捻るようにかかっても、互いに嵌合するキーとキー溝によって受けることができて切削時の回転防止機能と工具の動剛性を強化でき、焼き嵌めによる二面拘束とキー及びキー溝嵌合とでシャンク部とヘッド部の一体化を高めて嵌合強度を向上できる。また、キー及びキー溝は、ヘッド部の切刃にかかる切削抵抗の主分力に略直交する方向に延在するようにしたから、特にボーリングバーなどの旋削工具においては、工作機械等へのシャンク部の取り付け位置に対して切刃の位置決めをキーとキー溝とによって行うことができ、また切削抵抗の主分力を略直交する方向のキー及びキー溝で受けることになるために切削時の動剛性が一層向上する。
【００２２】
本発明によるヘッド交換式切削工具の製造方法は、ヘッド部とシャンク部の一方は軸部とテーパ面を備え、他方は軸部に嵌合する穴部とテーパ面に嵌合するテーパ状部とを備え、軸部と穴部、テーパ面とテーパ状部のそれぞれ少なくともいずれか一方に締め代が設けられていて、穴部及びテーパ状部を加熱して軸部及びテーパ面と焼き嵌めするから、穴部と軸部、そしてテーパ状部とテーパ面とをそれぞれ焼き嵌めすることで締め代圧によって二面拘束することができ、工具の剛性を高めることができる。
【００２３】
また、穴部及びテーパ状部を軸部及びテーパ面に焼き嵌めする際、テーパ状部は収縮が進行する状態でテーパ面に嵌合させるようにしたから、常温に戻った際に収縮寸法の誤差が生じることがあっても、テーパ状部とテーパ面はずれた状態でも、ずれが締め代寸法の範囲内であれば互いに当接して締め代圧が作用するから、両者の間に隙間が形成されることなく面拘束を確保できる。
【図面の簡単な説明】
【図１】本発明の第一の実施の形態によるボーリングバーの一部を断面で示す要部正面図である。
【図２】図１に示すボーリングバーのＢ−Ｂ線断面図である。
【図３】図１に示すボーリングバーのＣ部拡大図である。
【図４】第一の実施の形態によるボーリングバーのシャンク部を示すもので、（ａ）は側面図、（ｂ）は底面図である。
【図５】ボーリングバーのヘッド部を示すもので、（ａ）は側面図、（ｂ）は底面図である。
【図６】第二の実施の形態によるボーリングバーの一部破断正面図である。
【図７】図６に示すボーリングバーのＥ部拡大図である。
【図８】第二の実施の形態によるボーリングバーのシャンク部を示すもので、（ａ）は正面図、（ｂ）は先端面図である。
【図９】ボーリングバーのヘッド部を示すもので、（ａ）は正面図、（ｂ）は底面図である。
【図１０】従来のボーリングバーの一部破断正面図である。
【図１１】図１０におけるＡ−Ａ線断面図である。
【符号の説明】
１０，３０ボーリングバー
１１シャンク部
１２ヘッド部
１６軸部
１７キー
１８，３２テーパ面
２６穴部
２７キー溝
２８，３４テーパ状部
２３ａ前切刃
２３ｂ横切刃[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exchangeable cutting tool in which a head portion is detachably mounted on a shank portion and a method of manufacturing the same.
[0002]
[Prior art]
Conventionally, as an example of this type of cutting tool, there is a boring bar as shown in FIGS.
The boring bar 1 is formed such that a head portion 4 to which a throw-away tip 3 is attached is detachably fitted to a shank portion 2 held by a machining center or the like (not shown). In this case, the shank portion 2 is made of, for example, an expensive cemented carbide having high rigidity, and the head portion 4 is easily attached or detached by using inexpensive steel or the like because the head portion 4 is easily worn or damaged due to chip scraping. .
Further, by making the head portion 4 replaceable, a head portion having different types of cutting blades can be mounted.
Such a structure of the head part 4 of the boring bar 1 and the fitting part 5 of the shank part 2 is such that, for example, a convex part 6a formed at the center of the tip end surface 6 of the shank part 2 is formed in a prismatic shape, and The hole 7a of the base end face 7 of the part 4 is formed in a prismatic recess, and the periphery is brazed in a state where the protrusion 6a is fitted into the hole 7a and the tip end face 6 and the base end face 7 are in contact with each other. It is supposed to.
Alternatively, the convex portion 6a is formed in a substantially columnar shape and a male screw is cut, and the hole portion 7a is formed in a substantially cylindrical concave portion to form a female screw to be screwed with the male screw of the convex portion 6a so as to be fitted. Was.
Further, as another fitting structure, there is a structure in which the convex portion 6a and the hole portion 7a are shrink-fitted.
[0003]
[Problems to be solved by the invention]
However, with such a structure of the fitting portion 5, when drilling a workpiece to be rotated with the cutting blade of the throw-away tip 3, the main component force of the cutting resistance is applied in a direction substantially orthogonal to the cutting blade. Since this is mainly received by the convex portion 6a and the hole portion 7a, the load on the relatively rigid steel head portion 4 is large. In the former case, the corner of the prismatic hole portion 7a is cracked, and the latter is cracked. In the case of (1), there is a drawback that the threaded portion between the female screw and the male screw is easily damaged, and the rigidity of the boring bar 1 is small, and the tool life is short.
Also, in the case of shrink fitting, after the hole 7a of the head portion 4 is heated and fitted into the convex portion 6a, when the temperature of the hole 7a decreases to room temperature and shrinks, the shrinkage error causes the base end surface of the head portion 4 to shrink. 7 may be separated from the tip end surface 6 of the shank portion 2, so that the holding strength and rigidity of the boring bar 1 are small and the tool life is short.
[0004]
The present invention has been made in view of the above-described problems, and has as its object to provide a head-replaceable cutting tool that has high rigidity of a tool and can improve tool life.
[0005]
[Means for Solving the Problems]
A head-replaceable cutting tool according to the present invention is a head-replaceable cutting tool in which a head portion having a cutting blade and a shank portion are fitted to each other, and the head portion is replaceable. One includes a shaft portion and a tapered surface, and the other includes a hole portion fitted to the shaft portion and a tapered portion fitted to the tapered surface.
The taper portion is inclined with respect to the center axis of the tool body, and at least one of the shaft portion and the hole portion, and at least one of the taper surface and the tapered portion, is provided with a margin, and the shaft portion and the A key is provided on one of the holes, and a key groove that fits into the key is formed on the other, and a side surface that is a longitudinal surface of the key groove is substantially the same as the front cutting edge of the cutting blade. It is characterized by being formed so as to be parallel.
Since the head portion and the shank portion are configured by shrink fitting, the shaft portion, the hole portion, and the tapered surface and the tapered portion are pressed and fixed by the interference pressure, and furthermore, are restrained by the two surfaces. Therefore, the mutual holding strength is high, and the tool rigidity is improved. Further, the dynamic rigidity is improved by receiving the feed component and the main component due to the cutting resistance.
[0006]
Further, a key may be provided on one of the shaft portion and the hole portion, and a key groove for fitting the key may be formed on the other.
Even if the main force or feed force of the cutting resistance by the cutting blade is applied to twist the head part, the key and key groove that fit each other can receive part of it, preventing rotation during cutting and tools. The rigidity of the shank portion and the head portion can be enhanced by the two-sided restraint by shrink fitting and the fitting of the key and the key groove, so that the tool rigidity can be improved.
Further, the key and the key groove may extend in a direction substantially orthogonal to the main component of the cutting resistance applied to the cutting blade of the head portion.
In particular, in a turning tool such as a boring bar, the positioning of the cutting blade with respect to the mounting position of the shank portion on the machine tool or the like can be performed by the key and the key groove, and the main component force of the cutting resistance is substantially orthogonal. The dynamic rigidity at the time of cutting is further improved since the key and the key groove arranged in the direction receive the key.
[0007]
The method of manufacturing a head-replaceable cutting tool according to the present invention is a head-replaceable cutting tool in which a head part having a cutting blade and a shank part are fitted together and the head part is replaceable. One of the shank portions has a shaft portion and a tapered surface, and the other has a hole portion fitted to the shaft portion and a tapered portion fitted to the tapered surface, and the shaft portion and the hole portion, and the tapered surface. A tightening margin is provided on at least one of the tapered portions, a key is provided on one of the shaft portion and the hole portion, and a key groove that fits into the key is formed on the other. A side surface, which is a longitudinal surface of the key groove, is formed so as to be substantially parallel to a front cutting edge of the cutting edge, and the hole and the tapered portion are heated to burn the shaft and the tapered surface. Fit and fit the key and the keyway And wherein the Rukoto.
By shrink-fitting the hole portion and the shaft portion, and the tapered portion and the tapered surface, the two surfaces can be restrained by the interference pressure, and the rigidity of the tool can be increased. If the shaft portion and the tapered surface are simultaneously cooled from room temperature during shrink fitting, the fitting becomes easier and more reliable.
[0008]
Further, when the hole and the tapered portion are shrink-fitted to the shaft portion and the tapered surface, the tapered portion may be fitted to the tapered surface while the shrinkage proceeds.
When the temperature returns to normal temperature, an error in the shrinkage dimension may occur. However, even if the tapered portion and the tapered surface are displaced, if the deviation is within the range of the interference dimension, the taper portion and the taper portion come into contact with each other and the interference pressure acts. Therefore, the surface constraint can be secured without forming a gap between the two.
The key is provided on one of the hole and the shaft, and the other is provided with a key groove for fitting with the key, so that it can be fitted at the time of shrink fitting. Work and tool rigidity are further improved.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 1 to 5 relate to a boring bar according to a first embodiment, FIG. 1 is a plan view of a main part showing a part of the boring bar in a cross section, and FIG. 2 is a BB of the boring bar shown in FIG. 3 is an enlarged view of a portion C of the boring bar shown in FIG. 1, FIG. 4 shows a shank portion, (a) is a side view, (b) is a bottom view, and FIG. 5 shows a head portion. (A) is a side view and (b) is a bottom view.
The boring bar 10 shown in FIGS. 1 to 3 has a shank portion 11 and a head portion 12 which are shrink-fitted and fitted by a fitting portion 13 to be integrated.
In particular, the shank portion 11 shown in FIG. 4 is made of, for example, a cemented carbide, has a substantially cylindrical shape, and has a flat holding portion 14 on its outer peripheral surface 11a for being held at a predetermined position on a machine tool such as a machining center (not shown). Are formed along the longitudinal direction.
A concentric, substantially cylindrical shaft portion 16 having a smaller diameter than the outer peripheral surface 11a is formed at a tip portion 15 (on the side of the head portion 12) of the shank portion 11 which forms one of the fitting portions 13. Has a cylindrical peripheral surface 16a and a circular tip surface 16b, and a substantially plate-like key 17 is formed on the tip surface 16b so as to protrude. The key 17 is provided at a position where the side surface 17 a in the longitudinal direction is substantially parallel to the holding surface 14, and is used for positioning the cutting blade of the head portion 12.
A tapered surface 18 is formed in a ring shape between the shaft portion 16 and the outer peripheral surface 11a. The inclination angle θ of the tapered surface 18 is set to an appropriate acute angle with respect to the central axis O of the shank portion 11, and is preferably an angle closer to 90 ° (see FIGS. 3 and 4).
[0010]
In particular, the head portion 12 shown in FIG. 5 is made of, for example, steel, is formed in a substantially columnar shape, and has a concave portion 20 formed by cutting off a distal end portion, and a concave tip mounting seat 21 is formed at a corner portion of the distal end. The indexable tip 22 is fixed with bolts or the like. The ridge on the tip side of the upper surface 23 of the throw-away tip 22 has a front cutting edge 23a and a horizontal cutting edge 23b.
The base end 25 of the head portion 12 forms the other of the fitting portion 13, and the base end portion 25 has a concentrically formed substantially cylindrical hole for shrink-fitting the shaft portion 16 of the shank portion 11. A part 26 is formed. The hole portion 26 is roughly constituted by a cylindrical portion forming the outer peripheral surface of the head portion 12, has an inner peripheral surface 26 a and a bottom surface 26 b, and a key groove 27 for fitting with the key 17 of the shank portion 11 is formed on the bottom surface 26 b. Have been. A ring-shaped tapered portion 28 having a tapered cross section is formed at a free end of the hole 26 which forms an opening.
As shown in FIG. 3, the tapered portion 28 is shrink-fitted to the tapered surface 18 of the shank portion 11, and the inclination angle of the tapered portion 28 with respect to the center axis O is substantially the same as the taper surface 18. Is set.
[0011]
In addition, the inner peripheral surface 26a of the hole 26 is shrink-fitted to the outer peripheral surface 16a of the shaft portion 16 so that the inner diameter thereof is smaller than the outer diameter of the shaft portion 16 by an interference (for example, 30 μm) at normal temperature. Is set. Similarly, the tapered portion 28 of the hole 26 is also set to have an inner diameter smaller than the corresponding outer diameter of the tapered surface 18 of the shaft 16 by the shrink fit (for example, 30 μm).
Conversely, the outer dimensions of the outer peripheral surface 16a and the tapered surface 18 of the shaft portion 16 are formed larger than the corresponding inner diameters of the inner peripheral surface 26a of the hole portion 26 and the tapered portion 28 by the amount of the interference. Alternatively, the interference may be formed on both.
[0012]
In addition, the key groove 27 of the head portion 12 is a substantially plate-like groove, and when drilling a workpiece W that is rotated by the boring bar 10, the key groove 27 is formed by the front cutting edge 23 a and the horizontal cutting blade 23 b of the throw-away tip 22. A side surface 27a, which is a surface in the longitudinal direction of the key groove 27, is located in a direction orthogonal to the main component force of the received cutting resistance. In other words, as shown in FIG. 1, a main component force is generated in the tangential direction of the processing hole h of the work material W at the cutting point of the work material W by the front cutting edge 23a and the horizontal cutting blade 23b. The side surface 27a of the keyway 27 is located in a direction orthogonal to the force.
Further, since the side surface 27a of the key groove 27 and the front cutting edge 23a are positioned substantially in parallel, the positioning of the cutting edges 23a and 23b with respect to the shank portion 11 is performed.
Thus, in a state in which the distal end portion 15 of the shank portion 11 and the base end portion 25 of the head portion 12 are shrink-fitted, the substantially plate-like key 17 and the side surfaces 17a, 27a of the key groove 27 which are fitted to each other. It can receive the main component of cutting force.
[0013]
The boring bar 10 according to the present embodiment is configured as described above. Next, a method of manufacturing the same will be described.
As shown in FIGS. 4 and 5, in a state where the head portion 12 and the shank portion 11 are separated from each other, the side surfaces of the key 17 and the key groove 27 are heated while the head portion 12 is heated at room temperature and the shank portion 11 is cooled. The base end portion 25 of the head portion 12 and the front end portion 15 of the shank portion 11 are shrink-fitted so that 17a and 27a are aligned. In this case, when the key 17 is fitted into the key groove 27, the cutting blades 23a and 23b of the head portion 12 are positioned in the circumferential direction with respect to the holding portion 14 of the shank portion 11.
When the shaft portion 16 of the shank portion 11 is fitted into the hole portion 26 of the head portion 12, when the head portion 12 and the shank 11 gradually return to room temperature, the hole portion 26 shrinks to reduce its diameter. Since the diameter of the portion 16 is increased, the shaft portion 16 is firmly shrink-fitted into the hole portion 26 by the interference pressure of the interference provided on the inner peripheral surface 26 a of the hole portion 26.
[0014]
At the same time, the tapered portion 28 of the hole 26 is pressed against the tapered surface 18 in a state where the contraction of the hole 26 of the head 12 progresses, and the shrink fit is performed by the interference pressure.
At this time, due to a dimensional error due to the contraction of the head portion 12 and the expansion of the shank portion 11 when the temperature returns to the normal temperature, the contact surface between the tapered portion 28 and the tapered surface 18 is slightly displaced as compared with the design. Even if it occurs, if it is within the range of the interference dimensions, the surfaces are in contact with each other at shifted positions to form tapered surfaces, and are mutually restrained by interference pressure. In this case, the interference pressure is smaller than the designed interference pressure by the displacement, but the two-sided constraint can be realized in combination with the surface constraint between the shaft portion 16 and the hole portion 26, and the rigidity of the entire boring bar 10 can be improved. Can be higher.
Thus, the boring bar 10 shown in FIGS. 1 to 3 is manufactured.
Instead of the above-described manufacturing method, the head portion 12 may be shrink-fitted to the shank portion 11 before the shrinkage proceeds, and may be shrunk after the fitting is completed.
[0015]
Next, the boring bar 10 is used to perform boring of the workpiece W as shown in FIG.
The prepared hole h of the rotating work material W is cut by the front cutting edge 23a and the horizontal cutting edge 23b to form a hole. At this time, the main component of the cutting resistance acting on the cutting blades 23a and 23b is applied to the tangential direction at the cutting point (a direction substantially orthogonal to the paper surface in FIG. 1 and downward from the top), for example, to the cutting blades 23a and 23b. It occurs in a direction that is substantially orthogonal.
For this reason, a stress acts in a direction in which the head portion 12 receiving the main component force is twisted with respect to the shank portion 11, and this main component force is applied to the key 17 and the key groove 27 that are substantially orthogonal to the main component force in the fitting portion 13. It can be received on each of the side faces 17a and 27a that come into contact. At the same time, a function of preventing rotation of the head 12 due to cutting resistance can be achieved.
Further, a stress that twists the head 12 in the horizontal direction is also exerted by the feed component F acting in the feed direction of the work material W (or) the boring bar 10. 26 and the constraining surface of the outer peripheral surface 16a of the shaft portion 16 and the constraining surfaces of the tapered portion 28 and the tapered surface 18, which also increase the dynamic rigidity of the boring bar 10.
[0016]
As described above, according to the present embodiment, the head portion 12 and the shank portion 11 are sintered by the inner peripheral surface 26a of the hole 26, the outer peripheral surface 16a of the shaft portion 16, and the tapered portion 28 and the tapered surface 18. Since the head portion 12 is fitted, the head portion 12 can be attached and detached and replaced, and it is possible to cope with the head portion 12 having different types of cutting edges and damage to the head portion 12.
In addition, two surfaces can be restrained by shrink fitting, and the main component force and the feed component force of the cutting resistance can be received, so that the rigidity and dynamic rigidity of the boring bar 10 can be improved. In addition, since the key and the key groove fitting are added to the fitting portion 13, the positioning accuracy of the cutting blades 23a and 23b with respect to the flat holding portion 14 of the shank portion 11 can be ensured, and further, the main component force of the cutting resistance. The receiving and rotation preventing functions can be strengthened, and the dynamic rigidity can be further improved.
In order to perform one surface constraint of the two-sided constraint by shrink fitting on the tapered portion 28 and the tapered surface 18, an error in contraction or expansion of the head portion 12 and the shank portion 11 causes the tapered portion 28 and the tapered surface 18. Can be shrink-fitted to each other by the interference pressure even if the contact positions are shifted, and the tool rigidity can be reliably improved.
[0017]
Next, a second embodiment of the present invention will be described with reference to FIGS. 6 to 9 using the same reference numerals for the same parts as those in the first embodiment.
6 is a partially cutaway front view of the boring bar, FIG. 7 is an enlarged view of a portion E in FIG. 6, FIG. 8 shows a shank portion, (a) is a front view, (b) is a front end view, and FIG. 5A and 5B show a head portion, FIG. 5A is a front view, and FIG. 5B is a bottom view.
In the boring bar 30 according to the present embodiment, at the tip end portion 15 of the shank portion 11 shown in FIGS. 6 and 8, the connection surface 31 between the outer peripheral surface 11 a and the shaft portion 16 is a ring-shaped flat surface substantially orthogonal to the central axis O. Have been. On the other hand, a tapered surface 32 is formed over the entire circumference between the shaft portion 16 and the key 17, and the substantially plate-shaped key 17 is formed on a small-diameter distal end surface 32 a following the tapered surface 32.
A hole 26 is formed in the base end 25 of the head 12 shown in FIGS. 6 and 9, and the free end 33 is a ring-shaped plane substantially perpendicular to the central axis O. Further, a ring-shaped tapered portion 34 is formed between the inner peripheral surface 26a and the bottom surface 26b of the hole 26, and the tapered portion 34 is shrink-fit to the tapered surface 32. . In this case, an interference is formed in the tapered portion 34 (or the tapered surface 32 or both), and the corresponding inner diameter is set smaller than the outer diameter of the tapered surface 32 by the interference.
As shown in FIG. 7, the taper portion 34 of the hole 26 and the taper surface 32 of the shaft portion 16 are each set at an inclination angle θ with respect to the central axis O.
A substantially plate-like key groove 27 is formed on the bottom surface 26b.
[0018]
Also in the present embodiment, the inner peripheral surface 26a of the hole 26 and the outer peripheral surface 16a of the shaft portion 16, and the tapered portion 34 and the tapered surface 32 can be restrained on two sides by shrink fitting. In this case, when the head portion 12 and the shank portion 11 are shrink-fitted, a contraction error or an expansion error occurs between the free end portion 33 of the hole portion 26 of the head portion 12 and the connection surface 32 of the shank portion 11, and a gap occurs. However, since the two-sided constraint can be achieved as described above, the rigidity of the tool can be reliably improved.
[0019]
In the above-described embodiment, the material of the head portion 12 is steel, and the material of the shank portion 11 is a cemented carbide. However, the material of each member is not limited thereto, and various materials can be adopted. Further, the materials need not necessarily be different from each other, and may be the same.
In the above description, the shaft 16 and the tapered surfaces 18 and 32 are formed in the shank 11, and the hole 26 and the tapered portions 28 and 34 are formed in the head 12. Conversely, the hole 16 is formed in the shank 11. 26 and the tapered portions 28 and 34 may be formed, and the shaft portion 16 and the tapered surfaces 18 and 32 may be formed on the head portion 12 and shrink-fitted to each other.
Further, in the above-described embodiment, the boring bar 10 has been described. However, the present invention is not limited to the boring bar, and may be applied to various cutting tools, for example, other turning tools such as cutting tools, and various rolling tools such as end mills and drills. In particular, the present invention can be adopted.
[0020]
【The invention's effect】
As described above, in the head replaceable cutting tool according to the present invention, one of the head portion and the shank portion has the shaft portion and the tapered surface, and the other fits into the hole portion fitted to the shaft portion and the tapered surface. A taper portion is provided, and a tightening margin is provided in at least one of the shaft portion and the hole portion, and at least one of the taper surface and the taper portion, so that the head portion and the shank portion are shrink-fitted and fitted to each other. The portion and the hole, and the tapered surface and the tapered portion are pressed and fixed by the interference pressure, and are restrained by the two surfaces, so that the holding strength of each other is high and the tool rigidity is improved. Further, the dynamic rigidity of the tool is improved by receiving the feed component and the main component due to the cutting resistance.
[0021]
A key is provided on one of the shaft and the hole, and a key groove is formed on the other, so that the main component and the feed component of the cutting resistance by the cutting blade twist the head. Even if it is applied, it can be received by the key and key groove that fit each other, the rotation prevention function during cutting and the dynamic rigidity of the tool can be strengthened, and the two-sided constraint by shrink fitting and the key and key groove fitting make the shank part The fitting strength can be improved by increasing the integration of the head and the head. In addition, since the key and the key groove extend in a direction substantially orthogonal to the main component of the cutting resistance applied to the cutting edge of the head portion, particularly in a turning tool such as a boring bar, the key and the key groove are not easily applied to a machine tool or the like. The cutting blade can be positioned with respect to the shank mounting position by the key and the key groove, and the main component of the cutting resistance is received by the key and the key groove in directions substantially orthogonal to each other. Dynamic rigidity is further improved.
[0022]
According to the method for manufacturing a head-changeable cutting tool according to the present invention, one of the head portion and the shank portion has a shaft portion and a tapered surface, and the other has a hole portion fitted to the shaft portion and a tapered portion fitted to the tapered surface. Since a tightening margin is provided on at least one of the shaft portion and the hole portion, and at least one of the tapered surface and the tapered portion, the hole portion and the tapered portion are heated to shrink fit with the shaft portion and the tapered surface. By shrink-fitting the hole and the shaft, and the tapered portion and the tapered surface, the two surfaces can be restrained by the interference pressure, and the rigidity of the tool can be increased.
[0023]
Also, when shrink-fitting the hole and the tapered portion to the shaft portion and the tapered surface, the tapered portion was fitted to the tapered surface in a state where the shrinkage progressed. Even if an error occurs, even if the tapered portion and the tapered surface are displaced, if the deviation is within the range of the interference allowance, they will come into contact with each other and the interference will act, so a gap will be formed between the two. The surface constraint can be secured without being performed.
[Brief description of the drawings]
FIG. 1 is a partial front view showing a part of a boring bar according to a first embodiment of the present invention in cross section.
FIG. 2 is a sectional view taken along line BB of the boring bar shown in FIG.
FIG. 3 is an enlarged view of a portion C of the boring bar shown in FIG.
4A and 4B show a shank portion of the boring bar according to the first embodiment, wherein FIG. 4A is a side view and FIG. 4B is a bottom view.
5A and 5B show a head portion of a boring bar, wherein FIG. 5A is a side view and FIG. 5B is a bottom view.
FIG. 6 is a partially cutaway front view of a boring bar according to a second embodiment.
FIG. 7 is an enlarged view of a portion E of the boring bar shown in FIG. 6;
FIGS. 8A and 8B show a shank portion of a boring bar according to a second embodiment, wherein FIG. 8A is a front view and FIG.
9A and 9B show a head portion of a boring bar, wherein FIG. 9A is a front view and FIG. 9B is a bottom view.
FIG. 10 is a partially cutaway front view of a conventional boring bar.
11 is a sectional view taken along line AA in FIG.
[Explanation of symbols]
10, 30 Boring bar 11 Shank portion 12 Head portion 16 Shaft portion 17 Key 18, 32 Tapered surface 26 Hole 27 Key groove 28, 34 Tapered portion 23a Front cutting edge 23b Horizontal cutting edge

Claims

In a head exchange type cutting tool in which a head portion having a cutting blade and a shank portion are fitted, and the head portion is replaceable.
One of the head portion and the shank portion includes a shaft portion and a tapered surface, and the other includes a hole portion fitted to the shaft portion and a tapered portion fitted to the tapered surface,
The tapered portion is inclined with respect to the center axis of the tool body, and at least one of the shaft portion and the hole portion, or the tapered surface and the tapered portion, is provided with an interference,
A key is provided on one of the shaft portion and the hole portion, and a key groove that fits into the key is formed on the other,
A head-replaceable cutting tool, wherein a side surface, which is a surface in a longitudinal direction of the key groove, is formed to be substantially parallel to a front cutting edge of the cutting edge.

In a head exchange type cutting tool in which a head portion having a cutting blade and a shank portion are fitted, and the head portion is replaceable.
One of the head portion and the shank portion includes a shaft portion and a tapered surface, and the other includes a hole portion fitted to the shaft portion and a tapered portion fitted to the tapered surface,
A tightening margin is provided on at least one of the shaft portion and the hole portion, and at least one of the tapered surface and the tapered portion,
One of the shaft portion and the hole portion is provided with a key, and the other is provided with a key groove for fitting the key, and a side surface that is a longitudinal surface of the key groove has a front cutting edge of the cutting blade. It is formed so as to be substantially parallel to the blade,
A method for manufacturing a head-replaceable cutting tool, comprising heating the hole and the tapered portion to shrink fit the shaft and the tapered surface and fitting the key and the key groove.