201134580 六、發明說明： 【發明所屬之技術領域】 本發明是關於鑽孔工具。 【先前技術】 近年來，隨著電子機器之顯著進化，對於印 之高密度組裝的要求越來越高。因此，例如專利 揭示般，印刷配線板（PCB )加工用的鑽孔工具 徑化發展，現在已進入刃部直徑未達0.4mm之 工具的量產化。 然而，這樣的鑽孔工具當無法在充分的周速 工的情況’會發生工具折損等的問題，這是已知 是極小徑鑽孔工具的情況，必須以更高轉速進行 得充分的周速，但若讓該鑽孔工具以高轉速進行 離心力會造成工具撓曲而產生旋轉振動（所謂動 〇 此外，將超硬合金製之主體部（具有刃部） 製等的柄部經由熔接接合（例如焊接）而構成的 合型的情況，由於柄部材料的縱彈性係數比超硬 相較於使用一個超硬合金材料將刃部（主體部） 成一體之整塊型（solid type )，其動態振動有 向。 亦即’如桌1 ( 1 )圖所示，一般在複合材 情況’當使用不鏽鋼等的鋼材製的柄部時，起因 刷配線板 文獻1所 不斷朝小 小徑鑽孔 下進行加 的。特別 旋轉以獲 旋轉，其 態振動） 和不鏽鋼 複合材接 合金小* 和柄部形 變大的傾 接合型的 於其縱彈 -5 - 201134580 性係數比超硬合金材小，已確認該工具的動態振動 的傾向。當動態振動變大的情況，鑽孔工具前端發 轉振動會使定位精度變差，結果造成孔位置精度降 第1 ( 1 )圖的之（a ) 、（ b )係例示孔位置 相對於所設定的鑽孔位置，將實際加工的孔位置偏 示於圖上（（a )( b )分別爲6000次衝孔的資料 軸（Y軸）和橫軸（X軸）的交點（圖的中心）表 量Ομιη。標示點越集中於圖中心孔表示位置精度越 般而言，在通常的轉速區進行之鑽孔加工，不管是 、複合材接合型任一者的情況，都是像（a )所圖 示點比較集中於圖的中心。另一方面，當動態振動 情況，如（b )所圖示般標示點無法集中於中心， 位置精度極端惡化的情況，會成爲近似環圈狀。此 第1 ( 1 )圖的（c )所示，動態振動越大，工具迄 損爲止的壽命（衝孔數（加工孔數））越短，這是 〇 在進行鑽孔加工時產生動態振動的情況，在從 定位置偏離的位置，工具的刀鋒會咬入被削材，隨 作業的進展刃部會撓曲，若到達設定深度而結束鑽 的話就將工具從被削材拔出，因此每次進行鑽孔和 都會對刃部的基部反覆地施加應力，如此造成疲勞 當動態振動變大的情況，由於位置偏差變大，刃部 會變大，因此上述應力也會增大，而導致折損壽命 因此，在高轉速區所使用的鑽孔工具，現狀是 有變大 生之旋 低。 π*Γ* 精度， 差量標 )，縱 示偏差 高，一 整塊型 示般標 變大的 而在孔 外，如 發生折 已知的 鑽孔設 著鑽孔 孔加工 拔出時 破壞。 的撓曲 變短。 以動態 -6 - 201134580 振動小的整塊型爲主流。 [專利文獻1 ]日本特開2 0 0 5 - 8 8 0 8 8號公報 【發明內容】 然而，在整塊型的情況，由於屬於稀有金屬之鎢的使 用量多，基於環境面、成本面的觀點，宜使用複合材接合 型。 此外，P C B加工用等之小徑的鑽孔工具，不僅是上述 離心力所造成的撓曲’加工時產生之橫方向（與工具軸垂 直的方向）之負荷所造成的撓曲也會影響孔位置精度，因 此一般是儘量採用哇提昇剛性的形狀。 具體的說，由於加工本身是沿工具軸方向進行，橫方 向的負荷是比端銑刀（end mill )等更小，即使是對工具 前端施加橫方向的負荷的情況，由於在直徑較小的刃部之 根部會產生應力集中，爲了提高孔位置精度，一般是進行 將刃部的刀腹厚度（w e b t h i c k n e s s )增大等的設計。 然而，在增大刀腹厚度的情況，雖然孔位置精度有提 高的傾向，但由於溝槽體積變小’會引起切屑堵塞或加工 孔內壁粗糙度變差，而發生工具折損、無法獲得良好的孔 品質等的問題。爲了確保溝槽體積並保有充分的剛性’雖 可採用將工具直徑增大的手段，但被加工的孔徑也會變大 ’如此並無法達成原先目的之高密度構裝。在要求高轉速 加工之極小徑工具，爲了在不改變工具直徑下抑制離心力 所造成的撓曲並同時抑制加工負荷所造成的撓曲，僅著眼 201134580 於刃部之設計難以獲得工具整體的剛性和動態振動的均衡 ’依據習知的複合材接合型’很難改善工具前端的動態振 動。 又第2圖係顯示習知PCB加工用之鑽頭的外形。圖 中的符號1’爲主體部，2’爲刃部，3’爲柄部，4’爲台階部 ，5’爲主體錐部’ 6’爲柄錐部，15’爲柄主體，第2(a) 圖係設有外徑一定的台階部4 ’之例子，第2 ( b )圖係未 設置台階部4 ’的例子（所謂筆直型）。 第2(a)圖’具體而言，是在刃部2’的基端部設置 越往基端側越大徑之錐狀的主體錐部5’，在該主體錐部 5’的基端連接設置外徑一定的台階部4’，藉此來構成主體 部1’；又在前述台階部4’的基端連接設置柄部3’。柄部 3 ’是在柄主體1 5 ’的前端設置越往前端側越小徑之錐狀的 柄錐部6 ’，該柄錐部6 ’是連接設置於前述台階部4 ’。 第2(b)圖係未設置台階部4’的型式之具體例，是 在大致相同直徑之刃部2 ’的基端連接設置柄部3 ’。柄部 3 ’是在柄主體1 5 ’的前端設置越往前端側越小徑之錐狀的 柄錐部6’，該柄錐部6’連接設置於前述刃部2’。亦即第 2(b)圖的形狀，不僅是台階部4’，連主體錐部5’也不 存在。 習知之複合材接合型，一般設計成使接合邊界位在柄 錐部6 ’的區域內。此外，一般設定成主體錐部5 ’的主體 錐角α ’爲1 5 °以上，柄錐部6 ’的柄錐角/3 ’爲20°以上。又 —般是將主體錐角α，和柄錐角冷’都設定在30°〜90°。該 201134580 等角度，並非根據後述本發明的技術思想之設定値，例如 配合安裝該鑽孔工具之鑽孔加工機的主軸夾頭（筒夾夾頭 )直徑而設定鑽孔工具的柄徑，對應於鑽孔加工機側之其 他的規範和規格，爲了從該柄徑縮徑至比柄徑更小徑的刃 部直徑而形成連接設置的設定角度而已。 本發明是有鑑於上述般的現狀，爲了提供一種環境性 及經濟性優異而極實用之鑽孔工具，是著眼於刃部和柄部 間的台階部，藉由改良台階部的形狀等，縱使是複合材接 合型的情況仍能儘量抑制高速旋轉時之動態振動。 參照附圖來說明本發明的要旨。 一種鑽孔工具，係包含主體部1和柄部3 ’該主體部 1是在工具主體的外周從工具前端朝向基端側形成一或複 數道螺旋狀的切屑排出溝槽且具有刃部2’該柄部3是在 基端側具有比前述刃部2更大徑的柄主體1 5 ;前述刃部2 是由以碳化鎢及鈷爲主成分之超硬合金構件所形成，另一 方面前述柄部3是由不鏽鋼構件所形成；此外’該超硬合 金構件及不鏽鋼構件是進行熔接接合’在前述刃部2和前 述柄主體1 5之間，設有其中途部的外徑比前述刃部2大 且比前述柄主體1 5小之台階部4 ;其特徵在於：前述台 階部4的外徑是設定成往基端側逐漸或連續地變大。 此外，本發明的鑽孔工具，是在請求項1所記載的鑽 孔工具中，前述台階部4是設置於前述主體部 此外，本發明的鑽孔工具，是在請求項2所記載的鑽 孔工具中，在前述台階部4設置：用來連接該台階部4前 -9- 201134580 端側的小徑部和該台階部基端側的大徑部之段差部7。 此外’本發明的鑽孔工具，是在請求項2所記載的鑽 孔工具中’在前述台階部4設置：從前端側朝向基端側外 徑漸增之前錐部8、25、26。 此外’本發明的鑽孔工具，是在請求項4所記載的鑽 孔工具中’前述前錐部8、25、26的錐角設定成比前述柄 部前端所設的柄錐部6的錐角更小。 此外’本發明的鑽孔工具，是在請求項i之任—項 所記載的鑽孔工具中’前述台階部4的前端側既定位置之 直徑D 1和基端側既定位置的直徑d 2之差除以該兩點間 的距離Lc的數値，當超硬合金構件所形成的部分從工具 前端起算未達9mm的情況以下式（1 )表示，又其爲 9mm〜12mm的情況以下式（2)表示： 0.03 ^ ( D2-D 1 ) /Lc ^ 0.26 (1) 0.0 1^ ( D2-D 1 ) /Lc ^ 0.1 5 ( 2 )。 此外’本發明的鑽孔工具，是在請求項6所記載的鑽 孔工具中’從工具前端起算4mm的位置之直徑爲i.5mm 以下。 此外，本發明的鑽孔工具，是在請求項6所記載的續 孔工具中，前述台階部4的重心位置是在從工具基端起算 之工具全長92.0%以下的位置，而且工具整體的重心位置 是在從工具基端起算之工具全長4 2.5 %以下的位置。 -10- 201134580 此外，本發明的鑽孔工具，是在請求項7 孔工具中，前述台階部4的重心位置是在從工 之工具全長92.0%以下的位置，而且工具整體 是在從工具基端起算之工具全長42.5 %以下的彳 此外，本發明的鑽孔工具，是在請求項 所記載的鑽孔工具中，前述台階部4的前端側 直徑D 1和基端側既定位置的直徑D2之差除 的距離Lc的數値，當超硬合金構件所形成的 前端起算未達9mm的情況以下式（3 )表： 9mm~ 12mm的情況以下式（4)表示： 0.03 g ( D2-D 1 ) /Lc ^ 0.1 5 ( 3 ) 0.0 1 g ( D2-D 1 ) /Lc ^ 0.1 ( 4 ) 〇 此外’本發明的鑽孔工具，是在請求項！ 鑽孔工具中，從工具前端起算4mm的位g 0 8mm以下。 此外’本發明的鑽孔工具，是在請求項1 $贊？L □：胃中，前述台階部4的重心位置是在從 算之工具全長82.5 %以下的位置，而且工具整 S胃&從工具基端起算之工具全長37.5%以下t &外’本發明的鑽孔工具，是在請求項！ Λ Π：胃中，前述台階部4的重心位置是在從 算之工具全長82.5 %以下的位置，而且工具整 所記載的鑽 具基端起算 的重心位置 丄 cm. V置。 4之任一項 既定位置之 以該兩點間 部分從工具 5，又其爲 0所記載的 之直徑爲 0所記載的 工具基端起 體的重心位 I勺位置。 1所記載的 工具基端起 體的重心位 -11 - 201134580 置是在從工具基端起算之工具全長37.5 %以下的位置β 此外’本發明的鑽孔工具，是在請求項8所記載的鑽 孔工具中’該鑽孔工具是印刷配線板加工用的鑽頭。 此外’本發明的鑽孔工具，是在請求項9所記載的鑽 孔工具中’該鑽孔工具是印刷配線板加工用的鑽頭。 此外’本發明的鑽孔工具，是在請求項1 2所記載的 鑽孔工具中，該鑽孔工具是印刷配線板加工用的鑽頭。 此外’本發明的鑽孔工具，是在請求項1 3所記載的 鑽孔工具中’該鑽孔工具是印刷配線板加工用的鑽頭。 本發明由於具備上述構造，即使是複合材接合型仍能 儘量抑制高速旋轉時的動態振動，而成爲環境性及經濟性 優異之極爲實用的鑽孔工具。 【實施方式】 針對本發明的較佳實施形態，根據圖式並配合本發明 的作用而簡單地作說明。 藉由鑽孔加工機之主軸夾頭（筒夾夾頭）來把持鑽孔 工具，利用該鑽孔工具進行旋轉切削加工。這時，使台階 部4的外徑往基端側逐漸或連續地變大，藉此使鑽孔工具 從筒夾夾頭突出之突出部的質量變小，且提高剛性，而能 減輕離心力及橫方向的負荷所造成的撓曲。而且，由於往 前端側質量變小，其重心位置變得靠筒夾夾頭側，藉由可 充分減輕離心力所造成的撓曲。如此，可減輕橫方向的負 荷及離心力所造成的撓曲雙方，縱使是複合材接合型仍能 -12- 201134580 儘量抑制高速旋轉時的動態振動。 [實施例] 根據圖式來說明本發明的具體實施例。 本實施例之鑽孔工具，係包含主體部1和柄部3 主體部1是在工具主體的外周從工具前端朝向基端側 一或複數道螺旋狀的切屑排出溝槽且具有刃部2，該 3是在基端側具有比前述刃部2更大徑的柄主體1 5 ; 刃部2是由以碳化鎢及鈷爲主成分之超硬合金構件所 ，另一方面前述柄部3是由不鏽鋼構件所形成；此外 超硬合金構件及不鏽鋼構件是進行熔接接合，在前述 2和前述柄主體1 5之間，設有其中途部的外徑比前 部2大且比前述柄主體1 5小之台階部4 ;而且前述 部4的外徑是設定成往基端側逐漸或連續地變大。 更具體的說，本實施例是具備主體部1和柄部3 部2直徑未達0.4mm之PCB加工用的鑽頭。該主體 在前端具有刃部2 (形成有用來對被削物實施鑽孔加 切刀），該柄部3是供鑽孔加工機的筒夾夾頭把持。 接著具體地說明各部位。 台階部4，是設置在主體部1的刃部2和柄部3 主體1 5之間，可和刃部2及柄部3分開形成，而將 分別進行熔接接合（例如焊接）而構成。亦即如前述 習知的複合材接合型，一般是將接合邊界設計在柄 6’的區域內，但在本實施例之接合邊界，可與習知同 設置在柄錐部6’的區域內，或設置於其他部位亦可 ，該 形成 柄部 前述 形成 ，該 刃部 述刃 台階 且刀 部1 工之 的柄 其等 般， 錐部 樣的 ，並 201134580 沒有特別的限定》 具體而言’主體部1，是在刃部2的基端部設置往基 端側變大徑之錐狀的主體錐部5，在該主體錐部5的基端 連接設置台階部4。柄部3，是在柄主體15的前端設置往 前端側變小徑之錐狀的柄錐部6，該柄錐部6的前端連接 設置於前述台階部4的基端，可採用前述構造，或者不設 置主體錐部5或柄錐部6或兩者而在刃部2和柄主體15 間設置台階部4亦可。 此外’（在柄錐部6將超硬合金製部分和不鏽鋼製部 分予以熔接接合）台階部4，可與主體部1同樣地爲超硬 合金製；（在主體錐部5將超硬合金製部分和不鏽鋼製部 分予以熔接接合）台階部4，可與柄部3同樣地爲不鏽鋼 製；此外’台階部4的前端側爲超硬合金製而基端側爲不 鏽鋼製亦可。另外，將超硬合金製部分和不鏽鋼製部分分 開形成’再將兩者熔接接合而構成亦可。 具體而言，當工具全長爲36〜40mm、柄主體15的直 徑（柄徑）爲2 · 6〜3.6 m m (更具體的是3 · 1 7 5 m m )的情況 ，台階部4之前端側既定位置的直徑D1和基端側既定位 置的直徑D2之差除以該兩點間的距離Lc之數値，由超 硬合金構件所形成的部分從刃部2的前端起算未達9mm (由超硬合金構件所形成的部分從工具前端起算的長度 Lb未達9mm)的情況，設定成以0.03S (D2-D1) /Leg 0.26表示；當Lb爲9mm〜12mm的情況設定成以0.01S ( D2-D1 ) /Lc g 0.1 5 表示。 -14- 201134580 此外，當柄徑爲2.6〜3.6mm的情況，從工具前端起算 4mm的位置之直徑設定爲1.5mm以下。 此外，當柄徑爲2.6〜3.6 mm的情況，台階部4之重心 位置是位於從工具基端起算之工具全長92.0%以下的位置 ，而且工具整體的重心位置是位於從工具基端起算之工具 全長4 2.5 %以下的位置。 另一方面，當工具全長爲 22〜34mm、柄徑爲 1_ 3〜2.5mm (更具體的是2mm )的情況，台階部4之前端 側既定位置的直徑D 1和基端側既定位置的直徑D2之差 除以該兩點間的距離Lc之數値，由超硬合金構件所形成 的部分從刃部2的前端起算未達9mm (由超硬合金構件 所形成的部分從工具前端起算的長度Lb未達9mm )的情 況，設定成以0.03S (D2-D1) /LcSO.15表示；當Lb爲 9mm〜12mm的情況設定成以0.01S (D2-D1) /LcSO.l表 不 ° 此外，當柄徑爲1 .3〜2.5mm的情況，從工具前端起算 4mm的位置之（台階部4)直徑設定爲0.8mm以下。 此外，當柄徑爲1 .3〜2.5 mm的情況，台階部4之重心 位置是位於從工具基端起算之工具全長82.5 %以下的位置 ，而且工具整體的重心位置是位於從工具基端起算之工具 全長37.5%以下的位置。 又PCB加工用的鑽頭之從筒夾夾頭突出的長度通常 爲15〜24mm左右，從使用超硬合金材之工具前端起算的 長度通常爲12mm以下。 -15- 201134580 使台階部4的外徑往基端側逐漸或連續地變大徑的形 狀’只要符合上述要件不管是什麼形狀皆可，例如包括： 第3圖所圖示之設置段差部7 (用來連接台階部4前端側 之小徑部和該台階部4基端側之大徑部）的構造、第4、 5圖所圖示之設置前錐部8 (從前端側朝向基端側外徑漸 增）的構造、未圖示之設置擴徑部（從前端側朝向基端側 呈曲線狀擴徑）的構造、其他構造、以及將其等予以組合 而成的構造。 第3圖顯示與第2 ( a )圖所示的習知形狀同樣地設 有主體錐部5和柄錐部6且設有上述段差部7的型式。第 3 ( a )圖的構造，作爲主體錐部5和柄錐部6之間的台階 部4，係設有第一直線部9、比該第一直線部9更大徑的 第二直線部1 〇、以及位於前述兩者間之往前端側變小徑 之錐狀的段差部7。此外，第3(b)圖的構造，係具有設 置在主體錐部5和柄錐部6之間的台階部4，且該台階部 4是在第一直線部9和第二直線部1 0和第三直線部1 1之 間分別設有段差部7。又本實施例之直線部是指直徑一定 的圓筒狀部分。 此外，在第3圖，上述前端側既定位置的直徑D1是 台階部4的前端位置的直徑；上述基端側既定位置的直徑 D2是台階部4的基端位置的直徑。另外’台階部4的基 端位置是與主體部1的基端位置相同。具體而言，在第3 (a )圖中，上述前端側既定位置的直徑D 1，是主體錐部 5的基端和第一直線部9的前端之連設部的直徑；上述基 -16- 201134580 端側既定位置的直徑D2，是第二直線部1 〇的基端和 部6的前端之連設部的直徑。在第3(b)圖中’上 徑D1，是主體錐部5的基端和第一直線部9的前端 設部的直徑；上述直徑D2，是第三直線部Π的基端 錐部6的前端之連設部的直徑。但關於上述直徑D2 該台階部4的基端位置（主體部1的基端位置）La 離工具前端8mm以上的位置時，是從工具前端起算 位置的直徑。 第4圖顯示與第2 ( a )圖所示的習知形狀同樣 有主體錐部5和柄錐部6且設有上述前錐部8的型式 第4 ( a )圖的構造，作爲主體錐部5和柄錐部 的台階部4，是設有前錐部8。又第4 ( b )圖的構造 爲主體錐部5和柄錐部6間的台階部4，是設有前端 線部1 2及前錐部8 (透過段差部7設置在該前端側 部12的基端側）。又第4 ( c )圖的構造，作爲主體 5和柄錐部6間的台階部4，是設有前錐部8和基端 線部1 3 (位於該前錐部8的基端側）。又第4 ( d ) 構造，作爲主體錐部5和柄錐部6間的台階部4，是 前端側直線部1 2及前錐部8 (透過段差部7設置在 端側直線部12的基端側），且在該前錐部8的基端 置基端側直線部1 3。又在第4圖中，前錐部8的錐 定成比柄錐部6的錐角更小的値。 此外’第4圖是與第3圖同樣的，上述前端側既 置的直徑D 1是台階部4的前端位置的直徑；上述基 柄錐 述直 之連 和柄 ’當 位於 8mm 地設 0 6間 ，作 側直 直線 錐部 側直 圖的 設有 該前 側設 角設 定位 端側 -17- 201134580 既定位置的直徑D2是台階部4的基端位置的直徑。另外 ，台階部4的基端位置是與主體部1的基端位置相同。具 體而言，在第4(a)圖中，上述直徑D1，是主體錐部5 的基端和前錐部8的前端之連設部的直徑；上述直徑D2 ，是前錐部8的基端和柄錐部6的前端之連設部的直徑。 在第4(b)圖中，上述直徑D1，是主體錐部5的基端和 前端側直線部1 2的前端之連設部的直徑；上述直徑D2， 是前錐部8的基端和柄錐部6的前端之連設部的直徑。在 第4(c)圖中，上述直徑D1，是主體錐部5的基端和前 錐部8的前端之連設部的直徑；上述直徑D2 ’是基端側 直線部1 3的基端和柄錐部6的前端之連設部的直徑。在 第4(d)圖中，上述直徑D1，是主體錐部5的基端和前 端側直線部1 2的前端之連設部的直徑；上述直徑D2 ’是 基端側直線部1 3的基端和柄錐部6的前端之連設部的直 徑。但關於上述直徑D2，當該台階部4的基端位置（主 體部1的基端位置）La位於離工具前端8 mm以上的位置 時，是從工具前端起算8 mm位置的直徑。 又在第3、4圖’上述直徑D1及D2的位置，由於工 具加工時例如加工工具（磨削磨石）的形狀變形等造成的 加工誤差，會有無法精密地界定其位置的情況。在此情況 ，可將上述直徑D1設定爲比既定位置（台階部4的前端 位置）更靠基端側的位置’將上述直徑D2設定爲比既定 位置（台階部4的基端位置）更靠前端側的位置’而採用 避開加工誤差區域的位置。 -18- 201134580 此外’本發明人等’根據後述見解進行各種實驗發現 出’不設置第3圖、第4圖所圖示之習知形狀的錐角較大 的主體錐部5 ’ （如第5 ( a ) ( b ) ( d )圖所圖示）在刃 部2的基端連接設置往基端側變大徑之錐角未達1 5。的（ 刃部連設）前錐部2 5，或不形成直線錐狀而在刃部2的 基端設置往基端側變大徑且朝工具軸側（工具中心側）變 凸之曲線狀的（刃部連設）曲面部，藉此作爲構成台階部 4的部位可獲得本發明的效果。又同樣的，不設置錐角較 大的柄錐部6 ’ （如第5 ( b ) ( c ) ( d )圖所圖示）在柄 部主體1 5的前端連接設置往前端側變小徑之錐角未達2 〇。 的（柄部連設）前錐部2 6 ’或不形成直線錐狀而在柄主 體1 5的前端設置往前端側變小徑且朝工具軸側變凸之曲 線狀的（柄部連設）曲面部，藉此作爲構成台階部4的部 位可獲得本發明的效果。 接著根據第5圖作具體的說明。 第5 ( a )圖的構造，作爲刃部2和柄錐部6間的台 階部4 ’是設置（刃部連設）前錐部2 5。又第5 ( b )圖 的構造，作爲刃部2和柄錐部6間的台階部4，是設有： 連接設置於刃部2基端之（刃部連設）前錐部2 5及連接 設置於該（刃部連設）前錐部25的基端之直線部1 4 ,且 在該直線部1 4的基端連接設置（柄連設）前錐部2 6 (連 接設置於柄主體1 5的前端）的前端。又第5 ( c )圖的構 造’作爲（設置於刃部2基端部）主體錐部5和柄主體 1 5間的台階部4 ’是設置（柄連設）前錐部26。此外， -19- 201134580 第5 ( d )圖的構造’作爲刃部2和柄錐部6間的台階部4 ，是將（刃部連設）前錐部25和（柄連設）前錐部26予 以直接連接。如此’第5(a)圖之形成於刃部2和柄錐 部6間的部位Ld成爲台階部4，第5 ( b ) ~ ( d )圖之形 成於刃部2和柄主體1 5間的部位Ld成爲台階部4。 此外，第5圖是與第3、4圖同樣的，上述前端側既 定位置的直徑D1爲台階部4的前端位置之直徑，上述基 端側既定位置的直徑D2爲台階部4的基端位置之直徑。 但是，設有前述（刃部連設）前錐部2 5 (錐角未達1 5 ° ) 或前述（刃部連設）曲面部（朝工具軸側變凸的曲線狀） 的工具，基於前述加工誤差可能存在等的形狀上的理由， 由於上述直徑D1之既定位置（台階部4的前端位置=刃 部2的基端位置）之界定有困難，上述直徑D1是從工具 前端起算之刃部2的標稱長度+lmm位置的直徑。又台階 部4的基端位置是與主體部1的基端位置相同》 具體而言，在第5(a)圖，上述直徑D1，是從工具 前端起算之刃部2的標稱長度+ lmm位置的直徑；上述直 徑D2，是（刃部連設）前錐部2 5的基端和柄錐部6的前 端之連設部的直徑。此外，在第5(b)圖，上述直徑D1 ，是從工具前端起算之刃部2的標稱長度+lmm位置的直 徑；上述直徑D2，是從工具前端起算8mm位置的直徑（ 其理由後述）。又在第5(c)圖，上述直徑D1，是（設 置於刃部2基端部）主體錐部5的基端和（柄連設）前錐 部26的前端之連設部的直徑，上述直徑D2，是從工具前 -20- 201134580 端起算8 mm位置的直徑（其理由後述）。此外，在第5 (d)圖，上述直徑D1，是從工具前端起算之刃部2的標 稱長度+ 1 mm位置的直徑；上述直徑D2，是從工具前端起 算8mm位置的直徑（其理由後述）。但關於上述直徑D2 ，當該台階部4的基端位置（主體部1的基端位置）La 位於離工具前端8mm以上的位置時，是從工具前端起算 8mm位置的直徑。因此，在第 5(b)〜（d)圖，上述直 徑D2的位置是從工具前端起算8mm位置的直徑，作爲在 柄主體1 5的前端連接設置（柄連設）前錐部2 6的構造， 在形成滿足上述本發明要件之形狀的情況，該台階部4的 基端位置La通常爲8inm以上的位置。 又在第5圖，在設有主體錐部5或柄錐部6的情況， 與第3、4圖的情況同樣的，上述直徑〇 1及D2的位置， 起因於前述的加工誤差，會有無法精密地界定其位置的情 況。在此情況’可將上述直徑D 1設定爲比既定位置（台 階部4的前端位置）更靠基端側的位置，將上述直徑D 2 設定爲比既定位置（台階部4的基端位置）更靠前端側的 位置’而採用避開加工誤差區域的位置。 以上的條件，是根據第6〜9圖所示的見解並進行第 1 0、1 1圖所示的實驗，將其結果整理而獲得的。 作爲鑽頭旋轉時之動態振動的要因（造成影響的因子 )’可列舉材料的縱彈性係數、質量、重心位置、剛性等 〇 首先’根據第6圖來說明縱彈性係數。所使用的超硬 -21 - 201134580 合金之縱彈性係數一般爲600GPa左右，不鏽鋼的縱彈性 係數爲200GPa左右，兩者差3倍左右。鑽頭的動態振動 ，是受到離心力造成的撓曲容易度（縱彈性係數）的影響 。鑽頭旋轉時產生的離心力，會對從筒夾夾頭突出之突出 部整體的根部（被筒夾夾頭把持的部分之前端邊界部分） 施加最大的應力。在相同形狀下，質量輕的複合型（複合 材接合型）之離心力小，施加於根部的應力變小，但構成 突出部根部之不鏽鋼的縱彈性係數差更多，因此容易撓曲 〇 第6圖中，（1)是整體都是超硬合金製的整塊型， (2 )是前端至柄錐部的前端側的一部分爲超硬合金製， 柄部爲不鏽鋼製之複合型；（3)是前端至台階部的前端 側一部分爲超硬合金製，其餘爲不鏽鋼製之複合型；將其 等之撓曲容易度（依據縱彈性係數）分成台階部和突出部 整體來進行比較時，在第6圖中，（1)爲台階部和突出 部都不容易撓曲，（2)爲超硬合金製的台階部不容易撓 曲，（3 )則變得都容易撓曲。第6圖的上部之比較相片 是（1 )和（3 )的比較，左側爲（1 )，右側爲（3 )，可 看出，在右側的工具，突出部的根部及台階部都具有大的 撓曲度。又第6圖之（1)〜（3)的外形形狀是與第2(a )圖相同的習知形狀。 根據第7圖來說明質量、重心位置。所使用之超硬合 金的密度一·般爲15xl03kg/m3左右’不鏽鋼的密度爲7.7x 103kg/m3左右，因此兩者差兩倍左右。鑽頭旋轉時所承受 -22- 201134580 的離心力是受質量的影響。又對於既定的離心力’是受重 心位置和應力集中部位之距離（兩者越近越難撓曲）的^ 響。 又與第6圖同樣的，在第7圖中，（1)是整體都是 超硬合金製的整塊型，（2 )是前端至柄錐部的前端側的 一部分爲超硬合金製，柄部爲不鏽鋼製之複合型；（3) 是前端至台階部的前端側一部分爲超硬合金製，其餘爲不 鏽鋼製之複合型。 將其等的撓曲容易度（依據質量）分成台階部和突出 部整體來進行比較時，在第7圖中，（1)是台階部及突 出部都容易撓曲’ （2)由於柄部是不鏽鋼製，其突出部 整體不容易撓曲，（3)則變成都不容易撓曲。 此外’將依據重心位置的撓曲容易度分成台階部和突 出部整體來進行比較時，在第7圖中，（])由於台階部 及突出部的重心位置都靠基端側’故都不容易撓曲；（2 )僅超硬合金製的台階部不容易撓曲，（3 )是台階部容 易撓曲’但突出部整體變得較難撓曲。 具體而言，不改變工具全長而將台階部加長的情況， 台階部的質量變重’產生於台階部的離心力變大。此外， 突出部的質量變輕，產生於突出部整體的離心力變小。另 一方面，若將台階部縮短，台階部的質量變輕，產生於台 階部的離心力變小。此外，突出部的質量變重，產生於突 出部整體的離心力變大。在第7圖的（1)〜（3)，是將 工具形狀和突出部長度設定爲相同而進行比較，因此質量 -23- 201134580 和重心位置是取決於工具所使用的材質、所使用的部位以 及其量。 此外，在複合型，前端側之超硬合金材使用量（從工 具前端起算之使用長度）越大，突出部的重心位置變得更 前端側，對於既定離心力的撓曲度變大。此外，關於台階 部的重心位置，在台階部的中途部將刃部側的超硬合金構 件和柄部側的不鏽鋼構件予以接合的情況，前端側的超硬 合金材使用量越大則重心位置變得更前端側，對於既定離 心力的撓曲度變大。 亦即，在複合型，重心位置改變和質量改變的意義相 同，因此實際上質量和重心位置會同時影響撓曲度。 接著根據第8圖來說明剛性。剛性受柄部直徑的影響 很大。在PCB加工用的鑽頭，柄徑是被限定的，材質的 縱彈性係數大致反映其剛性。關於台階部，其剛性是依形 狀、材質而改變。 第8圖之（1)〜（3)，是與第6圖、第7圖的（1) 〜（3)同樣的。第8圖的（4)，是將複合型（3)(前端 至台階部前端側的一部分爲超硬合金製，其餘爲不鏽鋼製 )之台階部長度增長的型式；第8圖的（5)，是將複合 型（3 )(前端至台階部前端側的一部分爲超硬合金製， 其餘爲不鏽鋼製）之台階部的直徑縮窄的型式。 將其等的撓曲容易度（依據剛性）分成台階部和突出 部整體進行比較時，在第8圖中，（1)是台階部及突出 部都不容易撓曲，（2)〜（4)由於柄部爲不鏽鋼製，突 -24- 201134580 出部整體容易撓曲，又（2)由於台階部整體爲超硬合金 製，台階部不容易撓曲，（3 )由於台階部比（4 ) ( 5 ) 粗或短而較難撓曲，（4 )由於台階部長（5 )由於台階部 細，因此變得容易撓曲。 以上，如第9圖所整理’在複合型之PCB加工用的 鑽頭，不僅是刃部，突出部整體和台階部雙方都會產生撓 曲’因此必須取得整體質量、重心位置的均衡、以及台階 部的質量、重心位置、剛性（形狀）之均衡’才能抑制撓 曲。 於是，在本實施例，針對台階部及突出部有以下的想 法，相對於習知例（1 )及習知例（3 )而達成實施例（2 )及實施例（4)的構造。第9圖的下部圖表，是將其等 的動態振動與超硬合金製的整塊型（形狀與習知例（1 ) (3 )相同）比較的結果。可看出實施例（2 ) ( 4 )都能 獲得接近整塊型的特性。 亦即’在台階部，藉由減輕質量，雖可降低所產生的 離心力而抑制動態振動’但由於剛性低而容易撓曲，爲了 保有剛性，必須形成外徑往基端側逐漸或連續地增大的形 狀’同時使台階部的重心位置在基端側。此外，將前端側 所使用之縱彈性係數高的超硬合金構件設計成較細，將縱 彈性係數低之不鏽鋼構件設計成較粗，藉此可保有剛性並 減輕質量。這與前述之從工具前端起算4mm的位置之直 徑設定成既定値（l_5mm以下或〇 8mm以下）有關。 此外’關於突出部，可將台階部增長、將台階部直徑 -25- 201134580 縮窄等，而將突出部整體輕量化，藉此減低所產生的離心 力且將重心位置設定於基端側。台階部的重心位置設定成 越靠基端側，越有利於抑制動態振動。這是關於：前述之 台階部4基端位置（主體部1的基端位置）La位在從工 具前端起算8mm位置的情況，上述D2爲從工具前端起算 8mm位置的直徑；以及，將台階部4的重心位置和工具 整體的重心位置設定在從工具基端起算之相對於工具全長 的比値所表示之既定位置。 第1 〇圖係顯示柄徑2 m m的情況之實驗條件及實驗結 果，第1 1圖係顯示柄徑3 · 1 7 5 mm的情況之實驗條件及實 驗結果。 工具前端之與柄部不同色的部分是超硬合金製部分， 該超硬合金製部分是一體地形成。該超硬合金製部分的基 端和不鏽鋼製部分的前端進行熔接接合。 工具的形狀和超硬合金使用量等雖有各種變化，只要 是能滿足上述條件的例子，都比不符合上述條件的習知例 更能抑制動態振動，這點已被確認。 此外，第1 〇圖的實施例N 〇. 1 0、1 1，台階部雖不是 往基端側直徑變大，但由於將台階部的形狀設定成重心位 置能滿足本實施例的條件，因此確認出較能抑制動態振動 。亦即確認出，藉由將重心位置設定成上述條件，可大幅 改善動態振動。 又關於動態振動，如第1 ( 2 )圖所圖示，是測定並 比較鑽孔工具以3 00krpm旋轉時的動態振動而進行評價。 -26- 201134580 在該第1(2)圖中’相當於第ι〇圖的習知例No 知形狀的複合材接合型（b )，是顯示習知形狀的 (a ) 5倍左右的動態振動；而依據相當於第1 〇圖 例No. 1之本實施例的複合材接合品（c ),則確認 習知形狀的複合材接合型（b )可大幅抑制動態振 第1 ( 2 )圖之右側圖表所示，這主要是藉由使重 靠近筒夾夾頭側（工具基端側）而獲得的效果。 本實施例由於採用上述構造，藉由鑽孔加工機 夾頭（筒夾夾頭）來把持鑽孔工具，且利用該鑽孔 進行旋轉切削加工時，可減少鑽孔工具之從筒夾夾 之突出部的質量並提高剛性，而能減輕離心力及橫 負荷所造成的撓曲。而且，藉由使前端側的質量變 使重心位置靠近筒夾夾頭側，如此可充分減輕離心 成的撓曲。因此，能減輕橫方向的負荷及離心力所 撓曲雙方，縱使是複合材接合型仍能儘量抑制高速 的動態振動。 如此，本實施例，縱使是複合材接合型仍能儘 高速旋轉時的動態振動，因此環境性及經濟性優異 實用。 【圖式簡單說明】 第1(1) ( 2 )圖係關於鑽孔工具的動態振動 說明圖。 第2(a) ( b )圖係說明習知形狀的槪略說明 .2之習 整塊型 的實施 出比起 動。如 心位置 的主軸 工具來 頭突出 方向的 小，而 力所造 造成的 旋轉時 量抑制 而極爲 之槪略 側視圖 -27- 201134580 第3(a) (b)圖係設有段差部之鑽孔工具 明側視圖。 第4(a)〜（d)圖係設有前錐部之鑽孔工 說明側視圖。 第5(a)〜（d)圖係設有前錐部之鑽孔工 說明側視圖。 第6圖係鑽孔工具之動態振動和縱彈性係數 槪略說明圖。 第7圖係鑽孔工具的動態振動和質量、重心 係之槪略說明圖。 第8圖係鑽孔工具的動態振動和剛性的關係 明圖。 第9圖係鑽孔工具的動態振動之槪略說明圖 第1 〇圖係顯示柄徑2mm的情況之鑽孔工具 件及實驗結果。 第1 1圖係顯示柄徑3.175mm的情況之鑽孔 驗條件及實驗結果》 【主要元件符號說明】 1 :主體部 2 :刃部 3 :柄部 4 :台階部 的槪略說 具的槪略 具的槪略 的關係之 位置的關 之槪略說 〇 的實驗條 工具的實 -28- 201134580 6 :柄錐部 7 :段差部 8 ' 25 、 26 : 1 5 :柄主體 D 1 :前端側 D2 :基端側 Lc :兩點間 前錐部 既定位置的直徑 既定位置的直徑 的距離 -29-201134580 VI. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention relates to a drilling tool. [Prior Art] In recent years, with the remarkable evolution of electronic devices, the demand for high-density assembly of printing has become higher and higher. Therefore, for example, as disclosed in the patent, the drilling tool for processing printed circuit board (PCB) has been developed in diameter, and now the diameter of the blade has not reached 0. Mass production of 4mm tools. However, such a drilling tool cannot cause problems such as tool breakage when it is not sufficient for a full-speed work, which is known as a very small-diameter drilling tool, and it is necessary to perform a full peripheral speed at a higher rotation speed. However, if the drilling tool is subjected to a centrifugal force at a high rotation speed, the tool will be deflected to generate a rotational vibration (so-called squeezing, and the shank portion made of a main body portion (having a blade portion) made of a super-hard alloy may be joined by fusion bonding ( For example, in the case of a combination of welding, since the longitudinal elastic modulus of the shank material is more solid than that of the hard part, the blade portion (body portion) is integrated into a solid type. Dynamic vibration is directional. That is, as shown in the table 1 (1), generally in the case of composite materials, when a handle made of steel such as stainless steel is used, the cause of the brushed wiring plate is continuously drilled toward the small diameter. Adding underneath. Special rotation for rotation, state vibration) and stainless steel composite joint gold small * and shank shape large tilt joint type in its longitudinal elastic -5 - 201134580 coefficient is smaller than super hard alloy Dynamic vibration tendency of the tool has been confirmed. When the dynamic vibration becomes large, the vibration of the front end of the drilling tool will deteriorate the positioning accuracy, resulting in a decrease in the accuracy of the hole position. (a) and (b) of the figure (1) show the position of the hole relative to the Set the drilling position and offset the actual machining hole position on the map ((a)(b) is the intersection of the data axis (Y axis) and the horizontal axis (X axis) of 6000 punches respectively (the center of the figure) The amount of Ομιη. The more concentrated the marked points are in the center of the figure, the more accurate the positional accuracy is. In the normal speed range, the drilling process is the same as in the case of any of the composite joining types. The illustrated points are concentrated in the center of the graph. On the other hand, in the case of dynamic vibration, as shown in (b), the marked points cannot be concentrated in the center, and the positional accuracy is extremely deteriorated, which becomes an approximate loop shape. As shown in (c) of the first (1) diagram, the larger the dynamic vibration, the shorter the life (the number of punched holes (the number of holes to be machined)) until the tool is damaged, which is the dynamic vibration generated when the drilling process is performed. The situation, in the position deviated from the fixed position, the blade of the tool When you bite into the material to be cut, the blade will flex as the work progresses. If the drill is finished at the set depth, the tool will be pulled out of the material to be cut. Therefore, each time the hole is drilled, the base of the blade is applied repeatedly. Stress, such as fatigue, when the dynamic vibration becomes large, the position of the blade becomes larger due to the larger positional deviation, so the above-mentioned stress also increases, resulting in a loss of life. Therefore, the drilling tool used in the high-speed region, The current situation is that there is a change in the rotation of the students. π*Γ* accuracy, difference mark), the vertical deviation is high, and the whole type shows that the standard is larger and outside the hole, such as the known drilling hole is set. The hole is damaged when it is pulled out. The deflection is shorter. The dynamic -6 - 201134580 small vibration type is the mainstream. [Patent Document 1] Japanese Laid-Open Patent Publication No. H0 5 - 8 8 0 8 8 [Invention] However, in the case of a monolithic type, since the amount of tungsten belonging to a rare metal is large, it is based on the environmental surface and the cost surface. From the point of view, it is advisable to use a composite joint type. In addition, the drilling tool for small diameters such as PCB processing is not only caused by the above-mentioned centrifugal force, but also the deflection caused by the load in the lateral direction (the direction perpendicular to the tool axis) generated during machining. Accuracy, so it is generally best to use wow to increase the rigidity of the shape. Specifically, since the machining itself is performed in the direction of the tool axis, the load in the lateral direction is smaller than that of the end mill, etc., even if a lateral load is applied to the front end of the tool, due to the smaller diameter. In the root portion of the blade portion, stress concentration occurs, and in order to improve the hole positional accuracy, it is generally designed to increase the webthickness of the blade portion. However, in the case of increasing the thickness of the blade, although the hole position accuracy tends to be improved, the groove volume becomes small, which may cause chip clogging or the roughness of the inner wall of the machined hole becomes deteriorated, and tool breakage occurs, and goodness cannot be obtained. Problems such as hole quality. In order to ensure the volume of the groove and to maintain sufficient rigidity, the means for increasing the diameter of the tool can be used, but the hole diameter to be processed is also increased. Thus, the high-density structure of the original purpose cannot be achieved. In the extremely small-diameter tool that requires high-speed machining, in order to suppress the deflection caused by the centrifugal force without changing the tool diameter and suppress the deflection caused by the machining load, it is difficult to obtain the rigidity of the whole tool only by focusing on the design of the blade at 201134580. The dynamic vibration equalization 'according to the conventional composite joint type' is difficult to improve the dynamic vibration of the tool front end. Fig. 2 is a view showing the appearance of a conventional drill bit for PCB processing. In the figure, the symbol 1' is the main body portion, 2' is the blade portion, 3' is the shank portion, 4' is the step portion, 5' is the main body taper portion '6' is the shank taper portion, and 15' is the shank main body, and the second portion is the shank main body. (a) The figure is an example in which the step portion 4' having a constant outer diameter is provided, and the second (b) diagram is an example in which the step portion 4' is not provided (so-called straight type). In the second (a) diagram, specifically, a tapered main body taper portion 5' having a larger diameter toward the proximal end side is provided at the proximal end portion of the blade portion 2', and the base end portion of the main body tapered portion 5' is provided. The main body portion 1' is formed by connecting a step portion 4' having a constant outer diameter, and a handle portion 3' is connected to the base end of the step portion 4'. The shank portion 3' is a tapered shank portion 6' which has a tapered shape toward the front end side at the tip end of the shank main body 15', and the shank portion 6' is connected to the step portion 4'. The second embodiment (b) is a specific example of a pattern in which the step portion 4' is not provided, and the handle portion 3' is connected to the base end of the blade portion 2' having substantially the same diameter. The shank portion 3' is a tapered shank portion 6' having a smaller diameter toward the distal end side at the distal end of the shank main body 15', and the shank portion 6' is connected to the blade portion 2'. That is, the shape of Fig. 2(b) is not only the step portion 4' but also the main body taper portion 5'. Conventional composite joint types are generally designed such that the joint boundary is in the region of the shank taper 6'. Further, generally, the main body taper angle α' of the main body taper portion 5' is set to be 15 or more, and the shank taper angle /3' of the shank taper portion 6' is 20 or more. Further, the main body taper angle α and the shank taper angle are generally set at 30° to 90°. The angle of the 201134580 is not set according to the technical idea of the present invention described later, for example, the diameter of the spindle chuck (clamp chuck) of the drilling machine to which the drilling tool is mounted is set, and the diameter of the drilling tool is set correspondingly. In other specifications and specifications on the side of the drilling machine, in order to reduce the diameter from the shank diameter to the diameter of the blade portion which is smaller than the shank diameter, a set angle of connection is formed. In view of the above-mentioned state of the art, in order to provide a drilling tool which is excellent in environmental and economical efficiency, it is a stepped portion between the blade portion and the shank, and the shape of the step portion is improved. In the case of a composite joint type, dynamic vibration at the time of high-speed rotation can be suppressed as much as possible. The gist of the present invention will be described with reference to the accompanying drawings. A drilling tool comprising a main body portion 1 and a shank portion 3'. The main body portion 1 is formed on the outer circumference of the tool body from the tool front end toward the base end side with one or a plurality of spiral chip discharge grooves and having a blade portion 2' The shank portion 3 has a shank main body 15 having a larger diameter than the blade portion 2 on the proximal end side, and the blade portion 2 is formed of a cemented carbide member mainly composed of tungsten carbide and cobalt. The shank 3 is formed of a stainless steel member; further, 'the superhard alloy member and the stainless steel member are welded and joined' between the blade portion 2 and the shank main body 15, and the outer diameter of the middle portion is provided to be larger than the edge The step portion 4 having a large portion 2 and smaller than the shank main body 15 is characterized in that the outer diameter of the step portion 4 is set to be gradually or continuously increased toward the proximal end side. Further, in the drilling tool according to the first aspect of the invention, the step portion 4 is provided in the main body portion, and the drilling tool according to the present invention is the drill described in the claim 2 In the hole tool, the step portion 4 is provided with a stepped portion 7 for connecting the small diameter portion on the end side of the step portion 4 to the front end of the period of the period of the period of the step portion, and the large diameter portion on the base end side of the step portion. Further, the boring tool of the present invention is provided in the boring tool according to claim 2, wherein the step portion 4 is provided with the tapered portions 8, 25, 26 which are gradually increased from the front end side toward the proximal end side. Further, in the drilling tool of the present invention, in the drilling tool of claim 4, the taper angle of the front taper portions 8, 25, 26 is set to be larger than the taper of the shank portion 6 provided at the front end of the shank portion. The angle is smaller. Further, the drilling tool of the present invention is the diameter D 1 of the predetermined position on the front end side of the step portion 4 and the diameter d 2 of the predetermined position on the base end side in the drilling tool described in the item of claim i. The difference is divided by the number of distances Lc between the two points. When the portion formed by the cemented carbide member is less than 9 mm from the tip end of the tool, the following formula (1) indicates that it is 9 mm to 12 mm. 2) indicates: 0. 03 ^ ( D2-D 1 ) /Lc ^ 0. 26 (1) 0. 0 1^ ( D2-D 1 ) /Lc ^ 0. 1 5 ( 2 ). Further, the boring tool of the present invention is the diameter of the position of 4 mm from the front end of the tool in the boring tool described in claim 6. 5mm or less. Further, in the boring tool of the present invention, in the boring tool of claim 6, the position of the center of gravity of the step portion 4 is the total length of the tool from the base of the tool 92. The position below 0%, and the center of gravity of the tool as a whole is the total length of the tool from the base of the tool 4 2. Below 5%. -10- 201134580 Further, in the hole tool of the present invention, in the hole tool of the claim 7, the position of the center of gravity of the step portion 4 is 92. The position below 0%, and the tool as a whole is the total length of the tool from the base of the tool. In addition, the drilling tool of the present invention is the distance divided by the difference between the diameter D 1 of the tip end side of the step portion 4 and the diameter D2 of the predetermined position of the base end side in the drilling tool described in the claim. The number of Lc, when the front end of the superhard alloy member is less than 9mm, the following formula (3): 9mm~12mm The following formula (4) means: 0. 03 g ( D2-D 1 ) /Lc ^ 0. 1 5 ( 3 ) 0. 0 1 g ( D2-D 1 ) /Lc ^ 0. 1 ( 4 ) 〇 In addition, the drilling tool of the present invention is in the request item! In the drilling tool, the position g 0 8 mm or less of 4 mm is counted from the front end of the tool. In addition, the drilling tool of the present invention is in the request item 1 $ like? L □: In the stomach, the position of the center of gravity of the step portion 4 is at the total length of the tool. The position is less than 5%, and the tool is full of S stomach & the total length of the tool from the base of the tool is 37. 5% or less t & outside the drilling tool of the present invention is in the request item! Λ Π: In the stomach, the position of the center of gravity of the aforementioned step portion 4 is at the total length of the tool. The position below 5 %, and the center of gravity of the base end of the tool recorded by the tool 丄 cm. V set. Any of the four positions in the predetermined position is the position of the center of gravity of the tool base end from the tool 5 and the diameter of the tool described in the zero point. The center of gravity of the tool base end of the tool described in -11 - 201134580 is the total length of the tool from the base of the tool. 5% or less of the position β Further, the boring tool of the present invention is the boring tool described in claim 8, wherein the boring tool is a drill for processing a printed wiring board. Further, the boring tool of the present invention is the boring tool described in claim 9, wherein the boring tool is a drill for processing a printed wiring board. Further, the drilling tool of the present invention is the drilling tool according to claim 12, wherein the drilling tool is a drill for processing a printed wiring board. Further, the boring tool of the present invention is the boring tool described in claim 13, wherein the boring tool is a drill for processing a printed wiring board. According to the present invention, even if the composite material is joined, the dynamic vibration during high-speed rotation can be suppressed as much as possible, and the utility model is an extremely practical drilling tool which is excellent in environmental and economical efficiency. [Embodiment] A preferred embodiment of the present invention will be briefly described based on the drawings and in conjunction with the effects of the present invention. The drilling tool is held by a spindle chuck (collar chuck) of a drilling machine, and the drilling tool is used for the rotary cutting process. At this time, the outer diameter of the step portion 4 is gradually or continuously increased toward the proximal end side, whereby the mass of the protruding portion of the drilling tool protruding from the collet chuck is reduced, and the rigidity is improved, and the centrifugal force and the lateral force can be reduced. Deflection caused by the load in the direction. Further, since the mass toward the front end side becomes small, the position of the center of gravity becomes closer to the collet chuck side, and the deflection caused by the centrifugal force can be sufficiently reduced. In this way, both the load in the lateral direction and the deflection caused by the centrifugal force can be reduced, and even if the composite material is joined, the dynamic vibration at the time of high-speed rotation can be suppressed as much as possible. [Embodiment] A specific embodiment of the present invention will be described based on the drawings. The drilling tool of the present embodiment includes the main body portion 1 and the shank portion 3. The main body portion 1 is a chip discharge groove having a spiral or a plurality of spirals from the tool front end toward the base end side on the outer periphery of the tool body and having a blade portion 2, The 3 is a shank main body 15 having a larger diameter than the blade portion 2 on the proximal end side; the blade portion 2 is a superhard alloy member mainly composed of tungsten carbide and cobalt, and the shank portion 3 is Further, the stainless steel member is formed; in addition, the super-hard alloy member and the stainless steel member are welded and joined, and between the foregoing 2 and the shank main body 15 , an outer diameter of the middle portion is larger than the front portion 2 and is larger than the shank main body 1 5 small step portion 4; and the outer diameter of the portion 4 is set to gradually or continuously become larger toward the proximal end side. More specifically, the present embodiment is provided with the main body portion 1 and the shank portion 3 having a diameter of less than 0. 4mm drill bit for PCB processing. The main body has a blade portion 2 at the front end (formed with a boring cutter for the workpiece to be cut), and the shank portion 3 is held by a collet chuck for the drilling machine. Next, each part will be specifically described. The step portion 4 is provided between the blade portion 2 of the main body portion 1 and the main body 15 of the shank portion 3, and is formed separately from the blade portion 2 and the shank portion 3, and is separately welded (e.g., welded). That is, as in the conventional composite joining type described above, the joint boundary is generally designed in the region of the shank 6', but in the joint boundary of the present embodiment, it can be disposed in the region of the shank taper portion 6' as is conventionally known. Or the other part may be formed, the shank is formed as described above, the blade is stepped, and the shank of the knives 1 is tapered, and the 201134580 is not particularly limited. The main body portion 1 is provided with a tapered main body tapered portion 5 having a large diameter toward the proximal end side at the proximal end portion of the blade portion 2, and a step portion 4 is connected to the proximal end of the main body tapered portion 5. The shank portion 3 is provided with a tapered shank portion 6 having a small diameter toward the distal end side at the distal end of the shank main body 15, and the distal end of the shank portion 6 is connected to the proximal end of the step portion 4, and the above-described configuration can be adopted. Alternatively, the step portion 4 may be provided between the blade portion 2 and the shank main body 15 without providing the main body tapered portion 5 or the shank tapered portion 6 or both. Further, (the step portion 4 is welded and joined to the shank taper portion 6 and the stainless steel portion), and the step portion 4 can be made of a superhard alloy similarly to the main body portion 1 (the main tapered portion 5 is made of a super hard alloy) The portion 4 and the stainless steel portion are welded to each other. The step portion 4 may be made of stainless steel similarly to the shank portion 3, and the front end side of the step portion 4 may be made of a superhard alloy and the base end side may be made of stainless steel. Further, the superhard alloy portion and the stainless steel portion may be formed separately, and the two may be welded and joined. Specifically, when the total length of the tool is 36 to 40 mm, the diameter (shank diameter) of the shank main body 15 is 2 · 6 to 3. In the case of 6 mm (more specifically, 3 · 1 7 5 mm ), the difference between the diameter D1 of the predetermined position of the front end side of the step portion 4 and the diameter D2 of the predetermined position of the base end side is divided by the distance Lc between the two points.値, the portion formed by the super-hard alloy member is not more than 9 mm from the front end of the blade portion 2 (the length Lb of the portion formed of the super-hard alloy member from the tip end of the tool is less than 9 mm), and is set to be 0. 03S (D2-D1) /Leg 0. 26 indicates; when Lb is 9mm~12mm, it is set to 0. 01S ( D2-D1 ) /Lc g 0. 1 5 means. -14- 201134580 In addition, when the shank diameter is 2. 6~3. In the case of 6 mm, the diameter of the 4 mm position from the front end of the tool is set to 1. 5mm or less. In addition, when the shank diameter is 2. 6~3. In the case of 6 mm, the center of gravity of the step 4 is located at the full length of the tool from the base of the tool 92. The position below 0%, and the overall center of gravity of the tool is located at the base of the tool from the base end. Below 5%. On the other hand, when the tool is 22~34mm in length and the shank diameter is 1_3~2. In the case of 5 mm (more specifically, 2 mm), the difference between the diameter D 1 of the predetermined position on the front end side of the step portion 4 and the diameter D2 of the predetermined position on the base end side is divided by the distance Lc between the two points, and is super hard. The portion formed by the alloy member is set to 0. The length of the portion of the blade portion 2 is less than 9 mm (the length Lb from the tip of the tool is less than 9 mm). 03S (D2-D1) /LcSO. 15 indicates; when Lb is 9mm~12mm, it is set to 0. 01S (D2-D1) /LcSO. l The table does not ° In addition, when the shank diameter is 1. 3~2. In the case of 5 mm, the diameter of the step (step portion 4) from the front end of the tool is set to 0. 8mm or less. In addition, when the shank diameter is 1. 3~2. In the case of 5 mm, the center of gravity of the step portion 4 is located at the full length of the tool from the base of the tool 82. Below 5 % of the position, and the overall center of gravity of the tool is located at the base of the tool from the base end. Below 5%. Further, the length of the drill for PCB processing from the collet chuck is usually about 15 to 24 mm, and the length from the tip of the tool using the super-hard alloy material is usually 12 mm or less. -15- 201134580 A shape in which the outer diameter of the step portion 4 is gradually or continuously increased toward the proximal end side as long as it conforms to the above-described requirements, regardless of the shape, for example, includes: the step portion 7 illustrated in Fig. 3 (the structure for connecting the small-diameter portion on the distal end side of the step portion 4 and the large-diameter portion on the proximal end side of the step portion 4), and the front tapered portion 8 as shown in Figs. 4 and 5 (from the front end side toward the base end) The structure in which the side outer diameter is gradually increased, the structure in which the diameter-enlarged portion (the curved diameter is expanded from the tip end side toward the base end side), the other structure, and the structure in which these are combined are not shown. Fig. 3 shows a pattern in which the main body taper portion 5 and the shank taper portion 6 are provided in the same manner as the conventional shape shown in Fig. 2(a), and the step portion 7 is provided. In the structure of the third (a) diagram, as the step portion 4 between the main body tapered portion 5 and the shank taper portion 6, a first straight portion 9 and a second straight portion 1 having a larger diameter than the first straight portion 9 are provided. And a stepped portion 7 having a tapered shape which is reduced in diameter toward the front end side between the two. Further, the configuration of Fig. 3(b) has a step portion 4 provided between the body tapered portion 5 and the shank tapered portion 6, and the step portion 4 is at the first straight portion 9 and the second straight portion 10 and A step portion 7 is provided between the third straight portions 1 1 , respectively. Further, the straight portion of this embodiment means a cylindrical portion having a constant diameter. Further, in Fig. 3, the diameter D1 of the predetermined position on the distal end side is the diameter of the distal end position of the step portion 4, and the diameter D2 of the predetermined position on the proximal end side is the diameter of the proximal end position of the step portion 4. Further, the base end position of the step portion 4 is the same as the base end position of the main body portion 1. Specifically, in the third (a) diagram, the diameter D 1 of the predetermined position on the distal end side is the diameter of the connecting portion between the proximal end of the main body tapered portion 5 and the distal end of the first straight portion 9; 201134580 The diameter D2 of the end position is the diameter of the connecting portion of the base end of the second straight portion 1 和 and the front end of the portion 6. In the third figure (b), the upper diameter D1 is the diameter of the proximal end of the main body tapered portion 5 and the distal end portion of the first straight portion 9; the diameter D2 is the base end tapered portion 6 of the third straight portion Π The diameter of the connecting portion of the front end. However, when the position of the base end of the step portion 4 (the base end position of the main body portion 1) La is 8 mm or more from the tip end of the tool, the diameter D2 is the diameter from the tip end of the tool. Fig. 4 is a view showing the structure of the fourth type (a) of the main tapered portion 5 and the shank tapered portion 6 and having the front tapered portion 8 as in the conventional shape shown in Fig. 2(a) as a main cone. The step portion 4 of the portion 5 and the shank taper portion is provided with a front taper portion 8. Further, the structure of the fourth (b) is a step portion 4 between the main body tapered portion 5 and the shank tapered portion 6, and is provided with a front end line portion 1 2 and a front tapered portion 8 (the transmission step portion 7 is provided at the front end side portion 12). The base side of the base). Further, in the structure of the fourth (c), the step portion 4 between the main body 5 and the shank taper portion 6 is provided with the front tapered portion 8 and the proximal end portion 13 (located on the proximal end side of the front tapered portion 8). . Further, in the fourth (d) structure, the step portion 4 between the main body tapered portion 5 and the shank taper portion 6 is the front end side straight portion 1 2 and the front tapered portion 8 (the transmission step portion 7 is provided at the base of the end side straight portion 12) The end side) is provided with a proximal end side straight portion 13 at the proximal end of the front tapered portion 8. Further, in Fig. 4, the taper of the front taper portion 8 is set to be smaller than the taper angle of the shank taper portion 6. Further, Fig. 4 is the same as Fig. 3, and the diameter D 1 which is provided on the front end side is the diameter of the front end position of the step portion 4; the above-mentioned base shank is connected straight and the shank ' is located at 8 mm. The diameter D2 of the predetermined position is set to the diameter of the base end position of the step portion 4, which is provided on the side straight side of the straight straight taper portion. Further, the base end position of the step portion 4 is the same as the base end position of the main body portion 1. Specifically, in the fourth (a) diagram, the diameter D1 is the diameter of the connecting portion between the proximal end of the body tapered portion 5 and the front end of the front tapered portion 8, and the diameter D2 is the base of the front tapered portion 8. The diameter of the connecting portion of the end and the front end of the shank taper portion 6. In the fourth figure (b), the diameter D1 is the diameter of the connecting portion between the proximal end of the main body tapered portion 5 and the distal end side straight portion 12; the diameter D2 is the base end of the front tapered portion 8 and The diameter of the connecting portion of the front end of the shank taper portion 6. In the fourth (c), the diameter D1 is the diameter of the connecting portion between the proximal end of the body tapered portion 5 and the front end of the front tapered portion 8, and the diameter D2' is the base end of the proximal end side straight portion 13 The diameter of the connecting portion with the front end of the shank taper portion 6. In the fourth (d) diagram, the diameter D1 is the diameter of the connecting portion between the proximal end of the main body tapered portion 5 and the distal end side straight portion 12; the diameter D2' is the proximal end side straight portion 13 The diameter of the connecting portion of the base end and the front end of the shank taper portion 6. However, with respect to the above-described diameter D2, when the base end position of the step portion 4 (the base end position of the main body portion 1) La is located at a position of 8 mm or more from the tip end of the tool, it is a diameter of 8 mm from the tip end of the tool. Further, in the positions of the diameters D1 and D2 of Figs. 3 and 4, the machining error due to the deformation of the shape of the machining tool (grinding grindstone) during machining of the tool may not precisely define the position. In this case, the diameter D1 can be set to a position closer to the proximal end than the predetermined position (the distal end position of the step portion 4). The diameter D2 is set to be closer to the predetermined position (the proximal end position of the step portion 4). The position on the front end side is used to avoid the position of the machining error area. -18-201134580 In addition, the 'inventors of the present invention' conducted various experiments based on the findings described later, and found that 'the body cone portion 5' having a large taper angle of the conventional shape shown in Figs. 3 and 4 is not provided. 5 ( a ) ( b ) ( d ) is shown in the figure). The taper angle at which the base end of the blade portion 2 is connected to the base end side is less than 15 . The front taper portion 25 is connected to the tool end side (tool center side) and has a curved shape at the base end side of the blade portion 2 at the base end of the blade portion 2. The curved surface portion is connected to the blade portion, whereby the effect of the present invention can be obtained as the portion constituting the step portion 4. Similarly, the shank taper 6' having a larger taper angle is not provided (as shown in the fifth (b) (c) (d) diagram). The front end of the shank main body 15 is connected to the front end side to be small. The cone angle of the trail is less than 2 inches. The front taper portion 2 6 ′ is not formed in a straight tapered shape, and is provided at the front end of the shank main body 15 with a small diameter toward the front end side and convex toward the tool shaft side (handle joint) The curved surface portion is provided, whereby the effect of the present invention can be obtained as the portion constituting the step portion 4. Next, a detailed description will be made based on Fig. 5. In the structure of Fig. 5(a), the step portion 4' between the blade portion 2 and the shank taper portion 6 is provided (the blade portion is connected) to the front taper portion 25. Further, in the structure of the fifth (b), the step portion 4 between the blade portion 2 and the shank taper portion 6 is provided with a front tapered portion 25 that is connected to the base end of the blade portion 2 (the blade portion is connected) and The straight portion 14 is disposed at the base end of the front taper portion 25 (the blade portion is connected), and the front taper portion 26 is connected to the base end of the straight portion 14 (the handle is connected to the handle) The front end of the front end of the main body 15. Further, the configuration of Fig. 5(c) is as (provided at the base end portion of the blade portion 2) the step portion 4' between the main body taper portion 5 and the stem main body 15 is provided (handle connected) front taper portion 26. In addition, -19-201134580 The structure of Fig. 5(d) is used as the step portion 4 between the blade portion 2 and the shank taper portion 6, and the front taper portion 25 and the (handle connecting) front taper are connected (the blade portion is connected). The part 26 is directly connected. The portion Ld formed between the blade portion 2 and the shank portion 6 in the fifth drawing (a) is the step portion 4, and the fifth (b) to (d) is formed between the blade portion 2 and the shank main body 15 The portion Ld becomes the step portion 4. In addition, in the fifth drawing, similarly to the third and fourth figures, the diameter D1 of the predetermined position on the distal end side is the diameter of the distal end position of the step portion 4, and the diameter D2 of the predetermined position on the proximal end side is the base end position of the step portion 4. The diameter. However, the above-described (blade-connected) front taper portion 25 (the taper angle is less than 15°) or the aforementioned (blade-connected) curved surface portion (curved shape that is convex toward the tool shaft side) is provided based on The above-mentioned machining error may have a shape or the like. Since the predetermined position of the diameter D1 (the front end position of the step portion 4 = the base end position of the blade portion 2) is difficult to define, the diameter D1 is a blade from the front end of the tool. The nominal length of section 2 + the diameter of the position of 1 mm. Further, the base end position of the step portion 4 is the same as the base end position of the main body portion 1. Specifically, in the fifth (a) view, the diameter D1 is the nominal length of the blade portion 2 from the tip end of the tool + lmm The diameter of the position; the diameter D2 is the diameter of the connecting portion of the base end of the front tapered portion 25 and the front end of the shank taper portion 6 (the blade portion is connected). Further, in the fifth (b) diagram, the diameter D1 is a diameter at a nominal length of the blade portion 2 from the tip end of the tool + 1 mm; and the diameter D2 is a diameter at a position of 8 mm from the tip end of the tool (the reason will be described later) ). Further, in the fifth (c), the diameter D1 is the diameter of the connecting portion of the base end of the main body tapered portion 5 and the front end of the front tapered portion 26 (provided at the base end portion of the blade portion 2). The diameter D2 is a diameter of 8 mm from the front of the tool -20-201134580 (the reason is described later). Further, in the fifth (d) diagram, the diameter D1 is a diameter from a nominal length of the blade portion 2 from the tip end of the tool + 1 mm; and the diameter D2 is a diameter of 8 mm from the tip end of the tool (the reason) Later). However, regarding the diameter D2, when the base end position of the step portion 4 (the base end position of the main body portion 1) La is located at a position of 8 mm or more from the tip end of the tool, it is a diameter of 8 mm from the tip end of the tool. Therefore, in the fifth (b) to (d), the position of the diameter D2 is a diameter of 8 mm from the tip end of the tool, and the front tapered portion 26 is connected to the front end of the handle body 15 (handle connected). In the case where the shape satisfying the above-described requirements of the present invention is formed, the base end position La of the step portion 4 is usually at a position of 8 inm or more. Further, in the fifth drawing, when the main body taper portion 5 or the shank taper portion 6 is provided, as in the case of Figs. 3 and 4, the positions of the diameters 〇1 and D2 are caused by the aforementioned machining errors. It is not possible to precisely define its position. In this case, the diameter D 1 can be set to a position closer to the proximal end side than the predetermined position (the distal end position of the step portion 4), and the diameter D 2 can be set to be larger than the predetermined position (the base end position of the step portion 4). The position at the front end side is used to avoid the position of the machining error area. The above conditions are obtained by arranging the results shown in Figs. 6 to 9 and performing the experiments shown in Figs. The cause of the dynamic vibration (the factor causing the influence) when the drill is rotated is exemplified by the longitudinal elastic modulus, the mass, the position of the center of gravity, the rigidity, and the like of the material. First, the longitudinal elastic modulus will be described based on Fig. 6 . The super-hardness used in the -21 - 201134580 alloy is generally about 600 GPa, and the longitudinal elastic coefficient of stainless steel is about 200 GPa, which is about 3 times. The dynamic vibration of the drill bit is affected by the ease of deflection (longitudinal elastic coefficient) caused by the centrifugal force. The centrifugal force generated when the drill bit rotates exerts the maximum stress on the entire root portion of the protruding portion that protrudes from the collet chuck (the portion of the front end portion of the portion gripped by the collet chuck). In the same shape, the centrifugal force of the lightweight composite type (composite joint type) is small, and the stress applied to the root portion is small, but the difference in the longitudinal elastic modulus of the stainless steel constituting the root portion of the protruding portion is more, so that it is easy to bend. In the figure, (1) is a monolithic type made of super-hard alloy as a whole, and (2) a part of the front end to the front end side of the shank taper is made of super-hard alloy, and the handle is made of stainless steel; (3) A part of the front end to the front end side of the step portion is made of a super-hard alloy, and the rest is made of a stainless steel composite type; when the flexibility of the deflection (according to the longitudinal elastic coefficient) is divided into the step portion and the entire protruding portion for comparison, In Fig. 6, (1), the step portion and the protruding portion are not easily deflected, and (2) the step portion made of cemented carbide is not easily bent, and (3) is easily deflected. The comparison photograph of the upper part of Fig. 6 is a comparison of (1) and (3), the left side is (1), and the right side is (3). It can be seen that the tool on the right side, the root portion and the step portion of the protruding portion have large The degree of deflection. Further, the outer shape of (1) to (3) of Fig. 6 is the same conventional shape as that of Fig. 2(a). The mass and center of gravity position will be described based on Fig. 7. The density of the superhard alloy used is generally about 15x10kg/m3. The density of the stainless steel is 7. 7x 103kg/m3 or so, so the difference between the two is about twice. The centrifugal force that the bit is subjected to when rotating -22- 201134580 is affected by the mass. Further, the predetermined centrifugal force ' is the distance between the center of gravity and the stress concentration portion (the closer the two are, the more difficult it is to flex). In the same manner as in Fig. 6, in Fig. 7, (1) is a monolithic type made of a superhard alloy as a whole, and (2) a part of the tip end to the tip end side of the shank taper is made of a superhard alloy. The handle is made of a stainless steel composite type; (3) a part of the front end to the front end side of the step portion is made of super-hard alloy, and the rest is made of stainless steel. When the ease of deflection (depending on the mass) is divided into the entire step portion and the protruding portion, in the seventh diagram, (1) the step portion and the protruding portion are easily deflected' (2) due to the handle portion. It is made of stainless steel, and the entire protruding portion is not easily deflected, and (3) is not easily deflected. In addition, when comparing the ease of deflection according to the position of the center of gravity into the entire step portion and the protruding portion, in Fig. 7, ()) since the center of gravity of the step portion and the protruding portion are both at the base end side, It is easy to bend; (2) only the stepped portion made of cemented carbide is not easily deflected, and (3) the stepped portion is easily deflected', but the entire protruding portion becomes difficult to bend. Specifically, when the step portion is lengthened without changing the entire length of the tool, the mass of the step portion becomes heavy, and the centrifugal force generated in the step portion becomes large. Further, the mass of the protruding portion becomes light, and the centrifugal force generated in the entire protruding portion becomes small. On the other hand, if the step portion is shortened, the mass of the step portion becomes light, and the centrifugal force generated in the step portion becomes small. Further, the mass of the protruding portion becomes heavier, and the centrifugal force generated in the entire protruding portion becomes large. In (1) to (3) of Fig. 7, the tool shape and the length of the protrusion are set to be the same, and therefore the quality is -23-201134580 and the position of the center of gravity depends on the material used and the part used. And its amount. In addition, in the composite type, the amount of use of the superhard alloy material on the front end side (the length used from the tip end of the tool) is larger, and the position of the center of gravity of the protruding portion becomes the front end side, and the degree of deflection for a predetermined centrifugal force becomes large. Further, in the center of gravity of the step portion, the cemented carbide member on the blade side and the stainless steel member on the shank side are joined in the middle portion of the step portion, and the position of the center of gravity is larger as the amount of the superhard alloy material on the distal end side is larger. When it becomes the front end side, the deflection degree with respect to a predetermined centrifugal force becomes large. That is, in the composite type, the change in the position of the center of gravity and the change in the mass have the same meaning, so that the mass and the position of the center of gravity actually affect the degree of deflection at the same time. Next, the rigidity will be described based on Fig. 8. The rigidity is greatly affected by the diameter of the shank. In the drill bit for PCB processing, the shank diameter is limited, and the longitudinal elastic modulus of the material roughly reflects its rigidity. Regarding the step portion, the rigidity is changed depending on the shape and the material. (1) to (3) of Fig. 8 are the same as (1) to (3) of Fig. 6 and Fig. 7. (4) of Fig. 8 is a pattern in which the length of the step portion of the composite type (3) (the front end to the tip end side of the step portion is made of a super hard alloy and the others are made of stainless steel) is increased; (5) of Fig. 8 This is a type in which the diameter of the step portion of the composite type (3) (the front end to the tip end side of the step portion is made of a super hard alloy and the others are made of stainless steel) is narrowed. When the ease of deflection (depending on the rigidity) is divided into the step portion and the entire protruding portion for comparison, in Fig. 8, (1) the step portion and the protruding portion are not easily deflected, (2) ~ (4) Because the handle is made of stainless steel, the protrusion is easy to flex as a whole, and (2) because the step is made of super-hard alloy as a whole, the step is not easy to bend, and (3) due to the step ratio (4) (5) It is thick or short and difficult to flex, and (4) Since the step (5) is thin due to the step, it becomes easy to flex. As described above, the drill for the PCB processing in the composite type is not only the blade portion, but also the deflection of both the entire projection and the step portion. Therefore, it is necessary to obtain the overall mass, the balance of the center of gravity, and the step portion. The balance of mass, center of gravity, and rigidity (shape) can suppress deflection. Then, in the present embodiment, the following assumptions are made for the step portion and the protruding portion, and the structures of the embodiment (2) and the embodiment (4) are achieved with respect to the conventional example (1) and the conventional example (3). The lower graph of Fig. 9 is a result of comparing the dynamic vibrations thereof and the monolithic type (the shape is the same as the conventional example (1) (3)) made of a cemented carbide. It can be seen that the embodiments (2) (4) can obtain characteristics close to the monolith type. That is, in the step portion, by reducing the mass, the centrifugal force generated can be reduced to suppress the dynamic vibration. However, since the rigidity is low, the deflection is easy. In order to maintain the rigidity, the outer diameter must be gradually or continuously increased toward the base end side. The large shape 'at the same time positions the center of gravity of the step portion on the proximal end side. In addition, the super-hard alloy member having a high longitudinal elastic modulus used on the front end side is designed to be thin, and the stainless steel member having a low longitudinal elastic modulus is designed to be thick, thereby maintaining rigidity and reducing quality. This is related to the above-described diameter from the front end of the tool of 4 mm, which is set to be a predetermined value (l_5 mm or less or 〇8 mm or less). Further, with respect to the protruding portion, the step portion can be enlarged, the step portion diameter -25-201134580 can be narrowed, and the like, and the entire protruding portion can be made lighter, whereby the centrifugal force generated can be reduced and the center of gravity position can be set to the proximal end side. The position of the center of gravity of the step portion is set to be closer to the base end side, which is advantageous for suppressing dynamic vibration. This is a case where the base end position of the step portion 4 (the base end position of the main body portion 1) is located at a position of 8 mm from the tip end of the tool, and the above D2 is a diameter of 8 mm from the tip end of the tool; and the step portion is formed. The position of the center of gravity of 4 and the position of the center of gravity of the tool as a whole are set at a predetermined position indicated by the ratio of the tool length from the tool base end. The first plot shows the experimental conditions and experimental results for the case where the shank diameter is 2 m m, and the first graph shows the experimental conditions and experimental results for the case where the shank diameter is 3 · 1 7 5 mm. The portion of the front end of the tool that is different in color from the shank is a portion made of a super-hard alloy, and the portion made of the super-hard alloy is integrally formed. The base end of the superhard alloy portion and the front end of the stainless steel portion are welded to each other. Although the shape of the tool, the amount of use of the cemented carbide, and the like are various, as long as the above conditions can be satisfied, it is confirmed that the dynamic vibration can be suppressed more than the conventional example which does not satisfy the above conditions. In addition, the embodiment of the first diagram N 〇. In the case of the step portion, the diameter of the step portion is not increased to the base end side. However, since the shape of the step portion is set to the center of gravity, the condition of the present embodiment can be satisfied. Therefore, it is confirmed that the dynamic vibration can be suppressed more. That is, it was confirmed that the dynamic vibration can be greatly improved by setting the position of the center of gravity to the above condition. Further, regarding the dynamic vibration, as shown in Fig. 1 (2), the dynamic vibration when the drilling tool was rotated at 300 rpm was measured and compared. -26-201134580 In the first (2) diagram, the composite material joint type (b) of the conventional example No. corresponding to the first figure is a dynamic display of about 5 times the (a) of the conventional shape. Vibration; and based on the equivalent of the first 〇 legend No. In the composite joint (c) of the present embodiment, it is confirmed that the composite joint type (b) of the conventional shape can largely suppress the dynamic vibration shown in the right graph of the first (2) diagram, mainly by The effect obtained by moving closer to the collet chuck side (tool base end side). In the present embodiment, since the drilling tool is held by the drilling machine chuck (clamp chuck) by using the above configuration, and the rotary cutting process is performed by using the drilling hole, the drilling tool can be reduced from the collet folder The quality of the protrusions is increased and the rigidity is reduced, and the deflection caused by the centrifugal force and the lateral load can be reduced. Further, by making the center of the front end side closer to the collet chuck side, the centrifugal deflection can be sufficiently reduced. Therefore, both the lateral load and the centrifugal force can be reduced, and the high-speed dynamic vibration can be suppressed as much as possible even in the composite joining type. As described above, in the present embodiment, the dynamic vibration when the composite material joining type can be rotated at a high speed is excellent in environmental and economical efficiency. [Simple description of the diagram] The 1st (1) (2) diagram is a diagram showing the dynamic vibration of the drilling tool. The 2(a)(b) diagram illustrates a brief description of the conventional shape. 2 The practice of the whole block type is compared with the start. The spindle tool at the center of the heart is small in the direction in which the head protrudes, and the amount of rotation caused by the force is suppressed and the side view is extremely -27- 201134580. 3(a) (b) is a hole with a step Tool side view. Figures 4(a) to (d) show a side view of the driller with the front taper. Figures 5(a) to (d) show a side view of the driller with the front taper. Figure 6 is a diagram showing the dynamic vibration and longitudinal elastic modulus of the drilling tool. Figure 7 is a schematic diagram of the dynamic vibration and mass of the drilling tool and the center of gravity. Figure 8 is a diagram showing the relationship between dynamic vibration and rigidity of a drilling tool. Figure 9 is a schematic diagram of the dynamic vibration of the drilling tool. Figure 1 shows the drilling tool and experimental results for the case of a shank diameter of 2 mm. Figure 1 shows the shank diameter 3. "Drilling test conditions and experimental results in the case of 175mm" [Explanation of main component symbols] 1 : Main body part 2: Blade part 3: Handle part 4: The position of the stepped part The stalk of the experiment strip tool -28- 201134580 6 : shank taper 7 : step section 8 ' 25 , 26 : 1 5 : shank body D 1 : front end side D2 : base end side Lc : two The diameter of the diameter of the predetermined position of the front taper between the points is -29-