553795 玫、發明說明 【發明所屬之技術領域】 本發明關於工具機主軸之工具固定裝置，尤其是關於將 用來對於牽引桿朝向工具固定側施力的氣體彈簧裝設於主 軸基端端面外上者。 【先前技術】 在對於工作件上施予機械加工的工具機的主軸前端側 部分，裝設有用來夾持工具的工具夾持部，該工具是利用 工具固定裝置而可固定或解除地被固定於工·具夾持部上。 一般之工具固定裝置，具有：牽引桿，可連接至工具的基 端部處；增能機構，能對於該牽引桿朝向工具固定側（主軸 的基端側）施力；及解除機構，對抗增能機構的增勢力將牽 引桿往固定解除側（主軸的前端側）驅動。 關於用來對於牽引桿朝向工具固定側施力之增能機構， 曾有各種架構的提案，或已被實用化之架構者，例如，本 發明之申請人即提出具有利用塡入壓縮氣體的氣體彈簧而 增勢力來對於牽引桿朝向工具固定側施力的增能機構之工 具固定裝置（參照日本特開2001-87910號公報）。在該工具 固定裝置中’延伸至主軸基端側部分形成間主軸基端面外 延伸的牽引桿延伸部，且在該牽引桿延伸部上，氣體彈簧 對於牽引桿朝向工具固定側施力。 另外’在工具固定裝置上，還裝設有對抗氣體彈簧的增 勢力往固定解除側驅動牽引桿的油壓汽缸，該油壓汽缸係 介由覆蓋氣體彈簧的罩件被固定於主軸組件的軸殼上，其 8 553795 氣體彈簧與油壓汽缸獨立構成，並非相互連結。 由於氣體彈簧裝設於主軸的基端端面外處，其不同於氣 體彈簧內建於主軸內的技術，可避免.使氣體工作室的汽缸 主體外徑減少於主軸直徑形成，故可加大汽缸主體內徑， 以使由主軸及工具固定裝置等所構成的主軸組件的長度縮 短。更且，可加大在氣體工作室內承受壓縮氣體的增勢力 之作用的承壓面積，即使將氣體工作室的氣壓設定爲較 低，亦可充分地確保固定工具用所需的增勢力。 此外，在該工具固定裝置中，亦裝設有氣壓檢測裝置， 可檢測到因壓縮氣體洩漏所致的氣體工作室內的氣壓降 低。 其次，針對通過本發明欲解決的問題加以說明。 在上述專利公報所述的工具固定裝置中，氣體彈簧和油 壓汽缸獨立構成，氣體彈簧與油壓汽缸並未相互連結，因 此，必須將這些氣體彈簧與油壓彈簧個別安裝於包含主軸 的主軸組件上，導致安裝作業較爲費時。 此外，在將氣體彈簧內建於主軸內的工具固定裝置中， 通常，爲了將工具牢固地固定於工具夾持部上，必須使封 入於氣體工作室內的壓縮氣體維持在高壓狀態，但是氣壓 越高壓縮氣體就越易於漏氣。並且，氣體工作室的氣壓降 低至預定氣壓以下時，就無法使工具更牢固地且準確地固 定於工具夾持部上。 這一點，上述公報的工具固定裝置，以將氣體彈簧裝設 於主軸的基端端面上來某種程度能改進上述的問題。但 553795 是，該工具固定裝置的氣體彈簧，雖然裝設有合成樹脂密 封件以防止壓縮氣體從氣體工作室外漏，但仍幾乎不能僅 用該密封件來長期密封壓縮氣體。還有，也曾提出對於密 封件上更加使用能實現活塞滑動部的潤滑之潤滑油，以防 止壓縮氣體的漏氣等技術，但是此時亦若潤滑油未充分地 供應至密封件週邊，即無法防止壓縮氣體的漏氣，使得氣 壓降低。此外，上述專利公報之工具固定裝置中爲檢測到 氣壓降低而可塡充壓縮氣體者，但是也導致塡充壓縮氣體 頻率的會增高。 更且，主軸因受到在機械加工時所產生的熱而呈現相當 高溫的狀態，並且若一直維持由主軸傳導來熱幾乎無法通 過氣體彈簧散熱的狀態，因壓縮氣體的熱膨脹而使氣壓過 於升高，以致增加漏氣量，或潤滑油溫度升高而使其黏度 降低，進而導致潤滑油的潤滑性及密封性能的降低。 本發明之目的在於：將氣體彈簧和用於固定或解除的流 體壓力汽缸相連結，構成爲緊湊而使其易於安裝於此等主 軸組件上；盡可能抑制漏氣而長期控制氣體彈簧的增勢力 的降低；促進氣體彈簧的散熱等。其他本發明之目的應可 由本發明的效果及實施形態記述中得知。 【發明內容】 本發明之工具機主軸之工具固定裝置，係爲可固定或解 除地固定工具機的主軸前端側部分所裝設的工具的工具固 定裝置，具有可連結至工具的基端部處的牽引桿；朝向工 具固定側對該牽引桿施力的增能機構；及對抗該增能機構 10 553795 的增勢力而將牽引桿往固定解除側驅動的解除機構，其特 徵爲：在上述牽引桿的基端側處，形成有向主軸基端端面 外延伸的牽引桿延伸部，上述增能機構具備有以與主軸一 體旋轉之方式連結至主軸基端上且在牽引桿延伸部上朝向 工具固定側對於牽引桿施力的氣體彈簧，上述解除機構， 係爲能在牽引桿延伸部往固定解除側驅動牽引桿之流體壓 力汽缸’具備有連結至上述氣體彈簧的基端上的流體壓力 汽缸。 ’ 工具處於被固定在主軸上狀態中，連結至工具基端部上 的牽引桿，是在向主軸基端面外延伸的牽引桿延伸部處利 用增能機構之氣體彈簧來朝向工具固定側產生較強增勢 力。從這一狀態中，利用解除機構的流體壓力汽缸對抗氣 體彈簧的增勢力將牽引桿朝向固定解除側驅動，就可解除 工具的固定狀態。在解除機構中，除了流體壓力汽缸外， 更包含有對於流體壓力汽缸提供工作流體的工作流體供應 源’以及用來連接流體壓力汽缸和工作流體供應源的接管 在此，流體壓力汽缸連結至氣體彈簧的基端上。亦即， 可使其等構成爲一種可將氣體彈簧和流體壓力汽缸予以預 先組裝的單一組件，因此可使增能機構及驅動裝置構成爲 緊湊，並且易於將氣體彈簧和流體壓力汽缸安裝於包含主 軸的主軸組件上。 接著，針對關於本發明的架構較佳形態加以說明。 a)亦可將上述氣體彈簧和流體壓力汽缸呈相對旋轉地連 11 553795 結。此時，流體壓力汽缸固定成不能旋轉，僅有氣體彈簧 與主軸呈一體地旋轉而構成。 b)氣體彈簧，具有：汽缸主體，套嵌於牽引桿延伸部上： 且以與主軸一體旋轉之方式連結至主軸基端上；汽缸孔， 形成於汽缸主體內；活塞部，裝設於牽引桿延伸部的長度 方向中間處且可移動指定行程地裝於汽缸孔內；及氣體工 作室，相對汽缸孔中的活塞部而形成於主軸側且封入有壓 縮氣體。從而，藉由氣體工作室內的壓縮氣體所致的增勢 力對於活塞部朝向工具固定側施力，以可使連結至牽引桿 上的工具固定於主軸上。 〇上述汽缸孔，亦可形成爲其直徑靠近主軸側越小的 錐形狀。此時，只要在氣體工作室內注入潤滑油用以使 活塞部和汽缸主體部之間予以潤滑，就可當進行機械加 工時有旋轉主軸及汽缸主體之際，使潤滑油受到離心力 而附著在汽缸孔內周面上，更且，潤滑油延著錐形狀的 汽缸孔移動，以使潤滑油供應至在活塞部和汽缸主體之 間所裝設的密封件處。 從而，潤滑油隨著主軸旋轉即供應至密封件處，能利 用密封件和潤滑油來準確地形成活塞部和汽缸主體之間 的密封狀態，加上可抑制密封件的磨損及老化以延長密 封件的壽命，可盡可能長期防止氣體工作室的漏氣，以 降低補充壓縮氣體頻率。 d)上述氣體彈簧，具有用以將裝設於氣體工作室內， 將活塞部朝向工具固定側增能的增能構件。此時，牽引 12 553795 桿延伸部，因受到氣體工作室的壓縮氣體的增勢力及增 能構件的增勢力朝向工具固定側施力，因此萬一有壓縮 氣體的漏氣而降低壓縮氣體所致的增勢力的情況發生， 仍可藉由螺旋彈簧的增勢力維持工具的固定狀態，可避 免工具在主軸旋轉中從主軸掉落。此外，可使氣體工作 室的氣壓減少增能構件的增勢力份量，可不易漏氣。 e)亦可將上述汽缸主體之直徑，構成爲與主軸略同或 大於主軸直徑。此時’由於能使汽缸主體內的氣體工作 室之直徑更加大，故即使縮短氣體工作室的長度，亦可 確保所需體積，更可縮短由主軸或工具固定裝置所構成 的主軸組件整體長度。此外，加大氣體工作室的直徑， 亦可使活塞部的氣壓承受面面積隨之增大，因此即使降 低氣體工作室的氣壓，仍可強力地固定工具，可使氣體 不易漏於氣體工作室中。 f )上述氣體彈簧，具有：密封件，用於在活塞部和汽 缸主體之間形成密封狀態；及潤滑油，在活塞部和汽缸 主體之間予以潤滑並用於密封壓縮氣體。此時，在活塞 部和汽缸主體之間，利用密封件和潤滑由來形成密封， 因此可盡可能抑制壓縮氣體漏於氣體工作室中。 £ )上述汽缸主體，具有塡充口，用於將壓縮氣體及潤 滑油塡入於氣體工作室內。從而，可將壓縮氣體及潤滑 油由該塡充α予以塡入。 h)亦可在上述汽缸主體外周部處設有散熱片。通過如 此使促進氣體彈簧的散熱而構成，可防止因機械加工時 13 553795 所產生的熱所引起的壓縮氣體膨脹而導致氣壓過於上 升，以致增加壓縮氣體的漏氣量。再加上，亦可抑制因 潤滑油升溫所致的油黏度降低，盡可能抑制潤滑油的潤 滑性能及密封性能之降低。 i)在上述流體壓力汽缸上，亦可裝設增勢力檢測裝置， 用以檢測在將牽引桿朝向固定解除側驅動時的氣體彈簧 的增勢力。每一次爲了解除工具的固定狀態，利用流體 壓力汽缸將牽引桿延伸部往固定解除側驅動時，可檢測 氣體彈簧的施力，因此能尙在機械加工之前周期性地檢 查是否因漏氣而降低施力，可防止處於降低增勢力狀態 中進行機械加工之虞。 【實施方式】 以下，針對爲了實施本發明的最佳形態加以說明。 本實施形態，係將本發明適用於加工中心中的一方案。 附帶而言，以圖1的上下左右作爲上下左右來加以說明。 如圖1、圖2所示，主軸組件1，具有：主軸2 ;軸殻3， 包含驅動馬達1 6用以使該主軸2呈旋轉驅動；工具固定裝 置4，將工具5呈可固定或解除地固定於主軸2上。工具 固定裝置4，具有··夾頭10，繫合於工具5基端部處；牽 引桿1 1，利用該夾頭1 0可連結至工具5的基端部處；增 能機構1 2，對於牽引桿1 1產生向上（工具固定側）增勢力； 解除機構1 3，對抗該增能機構1 2的增勢力而可將牽引桿 往下（固定解除側）驅動。 在主軸2前端部處，形成有直徑靠近前端處增大且呈錐 14 553795 形狀的工具保持部2 a，而在該工具保持部2 a處，可繫合 一種形成於工具5的基端側處且呈錐形狀的柄部5 a。主軸 2，係呈垂直姿態配設於軸殼3內，並使主軸2的兩端通過 軸承1 4、1 5呈旋轉自如地支撐於軸殻3上。在軸殼3的馬 達收納部3 a內，裝設有驅動馬達1 6將主軸2對於軸殻3 旋轉驅動。 在主軸2內部處，呈直排狀地形成有工具保持部2 a及連 至工具保持部2 a上端的收納孔2b。工具5，具有：柄部 5 a，可嵌入於工具保持部2 a內；小徑軸部5 b及被繫合部 5 c，均形成於柄部5 a的基端部處；大徑夾持部5 d，形成 於柄部5 a前端部處且當進行交換時由未圖示的自動工具 交換裝置來夾持。處於將工具5裝設於主軸2上的狀態中， 柄部5 a呈緊密地繫合於工具保持部2 a上，且被繫合部5 c 成爲與收納孔2b前端部對置的狀態。 在收納孔2b內部內裝有二個筒構件2 0、2 1，且在筒構 件2 0的前端部內側配設有夾頭1 〇。該夾頭1 〇係藉由分割 成多數個的夾頭分割部10a來夾持工具5的被繫合部5c。 在筒構件2 0、2 1內側，均配設有牽引桿1 1呈可上下滑 動。牽引桿11，具有牽引桿主體22，固定於該牽引桿主體 22的前端部處之連結體23。在牽引桿主體22的基端部側 處，形成有牽引桿延伸部2 4延伸至主軸2及軸殻3端面 外，而在牽引桿延伸部24上連結有增能機構1 2及解除機 構1 3。在牽引桿主體22的下端部處呈內嵌狀地螺合於連 結體23上，而在連結體23上，繫合有夾頭10及襯墊25。 15 553795 如圖1所示，在利用增能機構1 2來對於牽引桿1 1產生 向上增勢力的狀態中，夾頭1 0維持夾持工具5的被繫合部 5 c之狀態產生向上增勢力，能使工具5固定於工具保持部 2 a上。相對於此，如圖2所示，在利用解除機構1 3來將 牽引桿1 1往下驅動的狀態中，夾頭1 〇亦往下移動成爲夾 頭分割部1 0 a分開的狀態，可解除工具5的固定狀態。 在牽引桿主體2 2的內部處，形成有通路2 2 a用來使對 於工具5所供應的切削液流通，而在連結體2 3內部處亦設 有前端管26連至該通路22a處。在將工具5安裝於工具保 持部2 a上的狀態中，前端管2 6的前端部處推接至被繫合 部5 c上，並且，切削液係由未圖示的切削液供應裝置且通 過迴轉接頭2 7、通路2 2 a、前端管2 6供應至工具5處。 接著，針對增能機構1 2加以說明。 如圖1乃至圖4所示，增能機構12，具有氣體彈簧3 0 用以對於牽引桿1 1在牽引桿延伸部24處朝向工具固定側 施力。該氣體彈簧30，具有：汽缸主體31，套嵌於牽引桿 延伸部24上且以與主軸2—體旋轉之方式螺合連結至主軸 2基端部處；汽缸孔3 1 a，形成於汽缸主體3 1內；活塞部 3 2 ’沿著牽引桿延伸部24的長度方向中間部處呈一體地裝 設且可移動指定行程而裝設於汽缸孔3 1 a上；氣體工作室 3 3，對於汽缸孔3 1 a中的活塞部3 2下側（主軸側）形成且封 入有壓縮氣體3 4。 汽缸主體31，構成爲其直徑與主軸2大致相同，且在該 汽缸主體31的下端部處，螺合連結至主軸2上。在汽缸主 16 553795 體3 1下端部處的軸心處，形成有穿通孔3 1 b供使牽引桿延 伸部2 4穿通。在汽缸主體3 1的下端部處左右兩側的左右 對稱的位置處，二個塡充口 3 1 c，分別用以將壓縮氣體3 4 及後述的潤滑油供應至氣體工作室3 3內。當欲由主軸2 中卸下氣體彈簧30時，就能使壓縮氣體34由塡充口 31c 排放。 更且，如圖3、圖4所示，在汽缸主體3 1的內部形成有 連至穿通孔3 1 b上端處的汽缸孔3 1 a，其直徑呈向下（主軸 側）縮小的錐形狀。在該汽缸孔3 1 a上，呈滑動自如地裝設 有與牽引桿延伸部24 —體成形的活塞部32。在汽缸孔31a 和活塞部32上，以及在穿通孔3 1 b和牽引桿延伸部24之 間，分別裝設有合成樹脂密封件3 5、3 6。 在氣體工作室33內，封入有高壓（例如爲3〜7Mp a左右） 的壓縮氣體34(例如爲高壓氮氣），並通過該壓縮氣體34 對於活塞部32產生向上之增勢力。在此，由於汽缸主體 3 1的直徑構成爲與主軸2大致相同，故其與氣體彈簧3 0 內建於主軸2內的狀況相較，可加大形成於壓縮氣體3 4 內的氣體工作室33之直徑，且可縮短汽缸主體31的上下 方向長度更可縮短主軸組件1的長度。另外，可加大活塞 部3 2上氣壓承受面面積，即使稍微降低壓縮氣體3 4的氣 壓，仍可確保牢固地固定工具5所需的增勢力，同時亦可 降低氣壓不易壓縮氣體34漏於氣體工作室33中。 在該氣體工作室3 3內，封入有潤滑油3 7用以在牽引桿 延伸部2 4和汽缸主體3 1之間予以潤滑並可密封壓縮氣體 17 553795 3 4。該潤滑油3 7，藉由重力垂落自然地供應至牽引桿延伸 部2 4和穿通孔3 1 b之間的密封件3 6處，且與密封件3 6 一同形成牽引桿延伸部2 4和穿通孔3 1 b之間的密封狀態。 更且，如上述般，汽缸孔3 1 a形成爲向下縮小的錐形狀， 因此主軸2處於高速旋轉（例如爲高於2 0，0 0 0 s pm )時，潤 滑油3 7受高速旋轉所引起的離心力附著於汽缸孔3 1 a內周 面上，更且，已附著的潤滑油3 7沿著汽缸孔3 1 a往上移動 而供應至活塞部3 2和汽缸主體3 1之間的密封件3 5上，其 潤滑油3 7，在對於活塞部3 2和汽缸主體3 1之間予以潤滑 的同時，亦可與密封件3 5 —同形成汽缸主體3 1之間的密 封狀態。 其次，針對解除機構1 3加以說明。 如圖1〜圖4所示，解除機構13，具有可與氣體彈簧30 相對旋轉地連結至氣體彈簧3 0基端處之油壓汽缸40，而 氣體彈賛3 0和油壓汽缸4 0 ’構成爲一體組件可供尙未安 裝於主軸組件1之前預先組裝。油壓汽缸4 0，具有：油壓 汽缸主體4 1 ;筒狀活塞構件4 2，呈滑動自如地套嵌於牽引 桿延伸部2 4的活塞部3 2上側處，且具備有呈滑動自如地 裝設於油壓汽缸主體4 1的油壓汽缸孔4 1 a上的活塞部 4 2 a ;油室4 3，將活塞部4 2 a向下驅動。 油壓汽缸主體4 1，係利用呈沿著周方向分割的多數個連 結分割體44來，呈相對旋轉自如地連結至氣體彈簧30的 汽缸主體31基端處。換言之，雖然氣體彈簧30呈與主軸 2 —體旋轉，但是不使油壓汽缸40旋轉而構成。在汽缸主 18 553795 體的上端部處，設有油壓供應口 4 1 b用以將油壓供應至油 室4 3內。更且，在油壓汽缸主體41的上端部處，設有位 置檢測開關4 5用以檢測到在工具5的固定狀態及固定解除 狀態時的牽引桿1 1位置，此外，在牽引桿延伸部2 4上設 有被檢測體4 6，其係被位置檢測開關4 5來檢測到者。 筒狀活塞構件4 2，係對於牽引桿延伸部2 4呈可上下滑 動且旋轉滑動地套嵌之。如圖3所示，氣體彈簧3 0的活塞 部3 2位於上限位置處，工具5處於被固定的狀態中，活塞 構件42的下端處，離由活塞部32上端處。在活塞構件42 的下端處，設有測力感應器4 7 (增勢力檢測裝置）以電性連 接至未圖示的控制單元上，一旦在由油壓汽缸40將牽引桿 延伸部2 4往固定解除側驅動時將活塞構件4 2往下驅動， 就使活塞部3 2的上端接觸於測力感應器4 7上，利用測力 感應器4 7檢測到氣體彈簧3 0的增勢力，如圖4所示。 在活塞部4 2 a的上側形成有油室4 3，一旦由未圖示的油 壓供應源提供有油壓，就使活塞部4 2 a往下驅動，再使活 塞構件4 2下端銜接至氣體彈簧3 0的活塞部3 2上端處，以 能使活塞部3 2對抗壓縮氣體3 4所致的增勢力向下驅動。 另外，在.活塞部42a下側處，形成有氣室48，而該氣室48 接至未圖示的儲壓器上，其塡充有氣壓較低的加壓氣。從 而，在油壓尙未供應至油室4 3內的狀態（工具固定狀態） 中，活塞部42a利用氣室48內的加壓氣產生向上增勢力， 以避免活塞部3 2和活塞構件4 2在氣體彈簧3 0與主軸一體 旋轉之際互相接觸而構成。 19 553795 首先，如圖1所示’在利用氣體工作室33內的壓縮氣體 3 4的增勢力來對於牽引桿1 1向上施力而將工具5固定於 工具保持部2a上的狀態中，對於油壓汽缸40的油室43 內供應油壓，就使油壓汽缸4 0的活塞構件4 2往下驅動， 更且，使活塞構件4 2通過測力感應器4 7銜接至氣體彈簧 3 0的活塞部3 2上’再對抗壓縮氣體3 4所致的增勢力，將 活塞構件42及活塞部3 2呈一體地往下驅動，使得牽引桿 1 1往下移動。於是，夾頭1 0亦往下移動就使夾頭分割部 1 〇 a成爲開放狀態，以可解除工具保持部2 a的工具5之固 定狀態（參見圖2)。此時，可利用測力感應器47來檢測到 氣體彈簧3 0的增勢力，就可檢測到氣體工作室3 3內的氣 壓狀態。 其次，利用自動工具交換裝置來將別的工具5安裝於工 具保持部2 a上之後，排放油室4 3內的油壓，氣體彈簧3 0 的活塞部3 2受到油室43的增勢力往下移動，亦使牽引桿 1 1及夾頭1 0向下移動，再由夾頭分割部1 0a夾持工具5 的被繫合部5c，更使牽引桿11往上移動，藉以使工具5 牢固地固定於工具保持部2a上。 維持這狀態，爲了進行對於受加工物品所做的機械加 工’使主軸2高速旋轉，就使氣體工作室3 3內的潤滑油 3 7受離心力附著於汽缸孔3 1 a的內周面上，更且，可使潤 '滑油3 7沿著形成爲直徑向下縮小的錐形狀的汽缸孔3 1 a 往上移動，因此能使潤滑油3 7供應至活塞構件和汽缸構件 之間的密封件3 5上，再通過密封件3 5和潤滑油3 7準確地 20 553795 形成活塞部3 2和汽缸主體3 1之間的密封狀態。相對於此， 潤滑油3 7藉由重力垂落自然地供應至位於穿通孔3 1 b和牽 引桿延伸部2 4之間的密封件3 6上’使得亦在穿通孔3 1 b 上準確地形成牽引桿延伸部2 4和汽缸主體3 1之間的密封 狀態。此外，潤滑油3 7具有相當高的黏稠性，且一旦有潤 滑油3 7供應至汽缸孔3 U和活塞部3 2之間’該潤滑油3 7， 與密封件3 5 —同藉由壓縮氣體3 4來向上增能，因此可使 汽缸孔3 1 a和活塞部3 2之間的潤滑油3 7不易垂落，使得 在停止主軸2中幾乎不降低密封件3 5的密封性能。 鲁 根據上述的工具固定裝置4，可獲得效果如下： 將油壓汽缸4呈相對旋轉地連結至氣體彈簧3 0的基端 上，再可使其等構成爲一種可尙未將其安裝於主軸組件1 上之前預先組裝的單一組件，因此可使增能機構1 2及解除 機構1 3構成爲緊湊，並且易於將增能機構1 2及解除機構 1 3安裝於主軸組件1上。 在氣體工作室3 3內，封入有潤滑油3 7用以對於牽引桿 延伸部2 4和汽缸主體3 1之間予以潤滑並能在壓縮氣體3 4 形成密封狀態，更且，汽缸孔3 1 a形成爲其直徑向下縮小 ， 的錐形狀，因此能使附著於汽缸孔3 1 a內周面上的潤滑油 3 7受到主軸2高速旋轉所引起的離心力沿著錐形狀的汽缸 孔3 1 a供應至密封件3 5上。從而，潤滑油3 7隨著主軸2 旋轉即供應至密封件3 5上，可使得利用密封件3 5及潤滑 油3 7準確地形成活塞部3 2和汽缸主體3 1之間的密封狀 態’且可抑制密封件的磨損及老化以延長密封件3 5的壽 21 553795 命，可盡可能長期防止壓縮氣體3 4漏於氣體工作室3 3中， 亦可降低補充壓縮氣體3 4頻率。 由於汽缸主體3 1構成爲其直徑與主軸2大致相同，故 可加大形成於汽缸主體3 1內部處的氣體工作室3 3直徑， 可使得縮短汽缸主體3 1的上下方向長度，亦可縮短主軸組 件1整體長度。此外，由於亦可加大承受壓縮氣體3 4的增 勢力的活塞部3 2承壓面積，即使將壓縮氣體3 4的氣壓設 定爲較低，亦可充分地確保能固定工具5所需的增勢力， 並且通過降低氣壓就可使壓縮氣體34不易漏於氣體工作 室33中。 每一次爲了解除工具5的固定，利用油壓汽缸4 0將牽 引桿延伸部2 4往固定解除側驅動時，能利用測力感應器 47來檢測到氣體彈簧30的增勢力，以可周期性地檢查是 否有因漏壓縮氣體3 4而降低增勢力的情形，可防止處於降 低增勢力狀態中進行機械加工之虞。 其次，針對對於上述實施形態上施予各種變化的變化形 態，加以說明。但是，針對具有與上述實施形態相同架構 者，附加與其相同元件符號且適當省略其說明。 1 ]如圖5所示，在工具固定裝置4A中，亦可在增能機 構1 2A的氣體彈簧3 0A的汽缸主體3 1 A外周部處形成散熱 片50。通過如此使促進氣體彈簧30A的散熱而構成，可防 止因機械加工時所產生的熱所引起的壓縮氣體3 4膨脹而 導致氣壓過於上升，以致增加壓縮氣體3 4的漏氣量。更 且，通過抑制因潤滑油3 7升溫所致的潤滑油3 7黏度降低’ 22 553795 盡可能抑制潤滑油3 7的潤滑性能及密封性能之降低。 2 ]當需要利用氣體彈簧3 0產生更大的增勢力時，可將汽 缸主體3 1構成爲其直徑大於主軸2的直徑。換言之，按牢 固地固定工具5所需的增勢力及所封入的壓縮氣體34氣 壓，可適當改變汽缸主體31的直徑。 3 ]亦可構成爲：裝設如旋轉彈簧等增能構件，取代對於 油壓汽缸4 0的氣室4 8內供應加壓氣，再利用該增能構件 所致的增勢力來對於活塞構件42產生向上增勢力，以避免 活塞構件42在主軸2旋轉時銜接至活塞部32上，當然， 亦可將供應油壓，藉由油壓來將活塞構件42往上驅動。 4]上述實施形態，雖然將本發明適用於豎立型加工中心 的主軸組件1中狀態，但是當然本發明亦適用於橫型加工 中心的主軸組件1中。在這種情況下，由於汽缸孔3 1 a形 成爲直徑靠近主軸側越小的錐形狀，故使氣體工作室3 3 內的潤滑油3 7在主軸2及汽缸主體3 1的旋轉中供應至活 塞部3 2和汽缸主體3 1之間的密封件3 5上，可使得利用密 封件35和潤滑油37準確地形成活塞部32和汽缸主體3 1 之間的密封狀態。 再者，針對本發明的另一實施形態加以說明。 如圖6所示，工具固定裝置4B，具有：牽引桿11B，可 連結至工具的基端部處；增能機構1 2B，對於牽引桿1 1 B 產生向上（工具固定側）之增勢力；及驅動機構13B，對抗 該增能機構12B的增勢力而可將牽引桿11B往下（固定解 除側）驅動。在牽引桿1 1 B的基端側處，形成有牽引桿延伸 23 553795 部60延伸至主軸2B基端的端面外。增能機構12B，具有 氣體彈簧30B將牽引桿1 1B在牽引桿延伸部60上產生向 下增勢力。驅動機構1 3 B，具有架構與上述實施形態略同 的油壓汽缸4 〇 B，而油壓汽缸4 0 B，係利用多數個連結分 割體44B，呈可相對旋轉地連結至氣體彈簧3 0B的基端 上，且使氣體彈簧3 0 B和油壓汽缸4 0 B構成爲單一組件。 氣體彈簧30B，具有：汽缸主體31B，套嵌於牽引桿延 伸部6 0上且以一體旋轉之方式固定性連結至主軸2 B基端 上；汽缸孔61，形成於汽缸主體31B內；活塞部32B，在 牽引桿延伸部24的長度方向中間部處呈一體地裝設且可 移動預定行程而裝設於汽缸孔6 1上；氣體工作室3 3 B，對 於汽缸孔6 1中的活塞部32B下側（主軸側）形成且封入有壓 縮氣體34;及螺旋彈簧62 (增能機構），安裝於該壓縮氣體 34B內且對於活塞部32B產生向下增勢力。 如同上述實施形態，汽缸孔6 1，係形成爲其直徑向下縮 小的錐形狀，而在汽缸孔6 1和活塞部3 2B之間，以及供 牽引桿延伸部60穿通的穿通孔63之間，分別安裝有密封 件3 5B、3 6B。更且，在氣體工作室33B內亦注入有潤滑 油37。螺旋彈簧62，係在氣體工作室33B內套嵌於牽引 桿延伸部60處，且銜接至形成於活塞部32B下端部處的 環狀彈簧承受部64上，以對於活塞部32B產生向上增勢 力。 換言之，牽引桿延伸部60處，係受氣體工作室33B內 的壓縮氣體34所致的增勢力，以及螺旋彈簧62所致的增 24 553795 勢力產生向上增勢力。從而，即使氣體工作室33B內的壓 縮氣體34爲較低，仍可確保牢固地固定工具所需的增勢 力，可使不易漏壓縮氣體3 4。此外，若萬一因漏有壓縮氣 體34而降低增勢力，仍可由螺旋彈簧62的增勢力來維持 工具固定狀態，因此可避免工具在機械加工中從主軸2B 掉落。 附帶而言，至於螺旋彈簧62的數量而言，其不限於一 件，可按牢固地固定工具所需增勢力適當變更螺旋彈簧62 的數量。更且，亦可採用如碟形彈簧等其他增能構件來取 代螺旋彈簧62。 本發明，不限於上述實施形態，應包含熟悉該項技術的 人員在不脫離本發明的精髓主旨範圍內所做的對於該等形 態附加各種改變而能實施者。 【圖式簡單說明】 圖1爲關於本發明的實施形態的工具機的主軸組件（工 具固定狀態）之縱向剖面圖。 圖2爲主軸組件（工具固定解除狀態）之縱向剖面圖。 圖3爲主軸組件的增能機構及解除機構（工具固定狀態） 之放大剖面圖。 圖4爲主軸組件的增能機構及解除機構（工具固定解除 狀態）之放大剖面圖。 圖5爲相當變化形態的圖3的圖。 圖6爲關於另一實施形態的主軸組件的增能機構及解除 機構之放大剖面圖。 25 553795 【元件符號說明】 1 主軸組件 2 主軸 2 a 工具保持部 2b 收納孔 3 軸殻 3a 馬達收納部 4 工具固定裝置 5工具 鲁 5 a 柄部 5 b 小徑軸部 5c 被繫合部 5 d 夾持部 10 夾頭 l〇a 夾頭分割部 11 牽引桿 0 12 增能機構 13 解除機構 ， 14' 15 軸承 16 驅動馬達 20 ' 21 筒構件 22 牽引桿主體 22a 通路 23 連結體 26 553795 24、 60 牽引桿延伸 25 襯 墊 26 刖 端 管 27 迴 轉 接 頭 3 0 氣 體 彈 簧 3 1 汽 缸 主 體 3 1a 、6 1 汽缸孔 3 1b 穿 通 孔 3 1c 塡 充 □ 32 活 塞 部 3 3 氣 體 工 作室 34 壓 縮 氣 體 35 ' 3 6 密封件 3 7 潤 滑 油 40 油 壓 汽 缸 4 1 油 壓 汽 缸主體 4 1a 油 壓 汽 缸孔 41b 油 壓 供 應口 42 活 塞 構 件 42a 活 塞 部 43 油 室 44 連 結 分 割體 45 位 置 檢 測開關 46 被 檢 測 體553795 Description of the invention [Technical field to which the invention belongs] The present invention relates to a tool fixing device for a main shaft of a power tool, and more particularly, to installing a gas spring for urging a traction rod toward a fixed side of the tool on an outer surface of a base end of the main shaft. By. [Prior Art] A tool holding portion for holding a tool is provided on a front end side of a main shaft of a machine tool for machining a work piece, and the tool is fixedly or releasably fixed by a tool fixing device. On the tool holder. A general tool fixing device has: a traction rod that can be connected to the base end of the tool; an energy-increasing mechanism that can apply force to the traction rod toward the fixed side of the tool (the base end side of the spindle); and a release mechanism to oppose the increase The increasing force of the energy driving mechanism drives the tow bar toward the unlocking side (front end side of the main shaft). Regarding the energy-enhancing mechanism for applying force to the tow bar toward the fixed side of the tool, there have been proposals of various structures, or those that have been put into practical use. For example, the applicant of the present invention proposes a gas having a compressed gas injected thereinto. A tool fixing device of an energizing mechanism for increasing a force to a traction rod toward a tool fixing side by a spring (refer to Japanese Patent Application Laid-Open No. 2001-87910). In the tool fixing device, the portion extending to the base end side of the main shaft forms a tow bar extension that extends outside the main shaft base end surface, and a gas spring urges the tow bar toward the tool fixing side on the tow bar extension. In addition, the tool fixing device is also provided with a hydraulic cylinder that drives the tow bar to the release side against the increasing force of the gas spring. The hydraulic cylinder is fixed to the shaft of the spindle assembly via a cover covering the gas spring. On the shell, its 8 553795 gas spring and hydraulic cylinder are formed independently and are not connected to each other. Because the gas spring is installed outside the base end face of the main shaft, it is different from the technology of the gas spring built in the main shaft, which can be avoided. The outer diameter of the cylinder body of the gas studio is reduced to the diameter of the main shaft, so the cylinder can be enlarged. The inner diameter of the main body is to shorten the length of the main shaft assembly composed of the main shaft and the tool fixing device. Furthermore, the pressure-bearing area that can withstand the increasing force of compressed gas in the gas working chamber can be increased, and even if the gas pressure of the gas working chamber is set to be low, the necessary increasing force for stationary tools can be sufficiently ensured. In addition, the tool fixing device is also equipped with a gas pressure detection device, which can detect the decrease of the gas pressure in the gas working chamber due to the leakage of compressed gas. Next, the problems to be solved by the present invention will be described. In the tool fixing device described in the above patent publication, the gas spring and the hydraulic cylinder are independently formed, and the gas spring and the hydraulic cylinder are not connected to each other. Therefore, these gas springs and hydraulic springs must be individually mounted on the main shaft including the main shaft. On the components, the installation is time consuming. In addition, in a tool fixing device in which a gas spring is built into a spindle, in order to firmly fix a tool to a tool holding portion, it is necessary to maintain a high pressure state of compressed gas enclosed in a gas working chamber. The more easily compressed gas will leak. In addition, when the air pressure of the gas working chamber drops below a predetermined air pressure, the tool cannot be more firmly and accurately fixed to the tool holding portion. In this regard, the tool fixing device of the above-mentioned publication can improve the above problems to some extent by installing a gas spring on the end surface of the base end of the main shaft. However, 553795 is the gas spring of the tool holder. Although it is equipped with a synthetic resin seal to prevent the compressed gas from leaking out of the gas working room, it is still almost impossible to seal the compressed gas with the seal alone for a long time. In addition, there have been proposed technologies such as the use of lubricants that can achieve lubrication of the piston sliding portion to prevent leakage of compressed gas, but at this time, if the lubricant is not sufficiently supplied to the periphery of the seal, that is, It is impossible to prevent the leakage of compressed gas, which reduces the pressure. In addition, in the tool fixing device of the above-mentioned patent publication, it is possible to charge a compressed gas in order to detect a decrease in air pressure, but it also causes the frequency of a compressed gas to be increased. In addition, the main shaft is in a relatively high temperature state due to the heat generated during machining, and if the state where the heat transmitted by the main shaft can hardly be dissipated by the gas spring is maintained, the air pressure is too high due to the thermal expansion of the compressed gas. As a result, the amount of air leakage is increased, or the viscosity of the lubricating oil is reduced due to the increase in the temperature of the lubricating oil, which in turn leads to a decrease in the lubricity and sealing performance of the lubricating oil. The purpose of the present invention is to connect a gas spring and a fluid pressure cylinder for fixing or releasing, and to make it compact so that it can be easily installed on these spindle assemblies; to suppress air leakage as much as possible and to control the increasing force of the gas spring for a long time Reduction; promote heat dissipation of gas springs. Other objects of the present invention should be known from the description of the effects and embodiments of the present invention. [Summary of the Invention] The tool fixing device of the main shaft of the machine tool of the present invention is a tool fixing device for fixing a tool mounted on a front end portion of the main shaft of the machine tool to be able to fix or release, and has a base end portion that can be connected to the tool. An energy-increasing mechanism that applies force to the traction rod toward the fixed side of the tool; and a release mechanism that drives the traction rod toward the fixed release side against the increasing force of the energy-enhancing mechanism 10 553795, which is characterized in that: At the base end side of the rod, a traction rod extension is formed which extends outside the end surface of the main shaft base end. The energy-enhancing mechanism is provided with a main shaft end that is integrally rotated with the main shaft and faces the tool on the tow rod extension The gas spring that applies force to the traction rod on the fixed side, and the release mechanism is a fluid pressure cylinder that can drive the traction rod on the extension side of the traction rod toward the fixed release side. The fluid pressure cylinder is provided with a fluid pressure cylinder connected to the base end of the gas spring. . '' When the tool is fixed on the spindle, the traction rod connected to the base end of the tool uses the gas spring of the energizing mechanism at the extension of the traction rod extending outside the base end surface of the spindle to produce a relatively large Increase your power. From this state, the fixed state of the tool can be released by driving the drawbar toward the fixed release side using the fluid pressure cylinder of the release mechanism against the increasing force of the gas spring. The release mechanism includes, in addition to the fluid pressure cylinder, a working fluid supply source for providing the working fluid to the fluid pressure cylinder, and a connection for connecting the fluid pressure cylinder and the working fluid supply source. Here, the fluid pressure cylinder is connected to the gas. The base of the spring. That is, it can be configured as a single component that can be preassembled with a gas spring and a fluid pressure cylinder, so that the energizing mechanism and the driving device can be made compact, and the gas spring and the fluid pressure cylinder can be easily installed in a On the spindle assembly. Next, a preferred embodiment of the architecture of the present invention will be described. a) The above-mentioned gas spring and fluid pressure cylinder can also be connected in a relatively rotating manner to 11 553795 knots. At this time, the fluid pressure cylinder is fixed so that it cannot rotate, and only the gas spring is integrally rotated with the main shaft. b) A gas spring, comprising: a cylinder main body, which is sleeved on the extension of the traction rod: and is connected to the base end of the main shaft in a manner that rotates integrally with the main shaft; a cylinder hole is formed in the main body of the cylinder; The rod extension is installed in the cylinder hole at the middle in the longitudinal direction and can be moved by a specified stroke; and the gas working chamber is formed on the main shaft side with respect to the piston portion in the cylinder hole and is enclosed with compressed gas. Accordingly, the increased force caused by the compressed gas in the gas working chamber is applied to the piston portion toward the tool fixing side, so that the tool connected to the tow bar can be fixed to the main shaft. 〇 The above-mentioned cylinder hole may be formed in a tapered shape as the diameter decreases toward the main shaft side. At this time, as long as the lubricating oil is injected into the gas working chamber to lubricate between the piston portion and the cylinder body portion, the lubricant can be attached to the cylinder by centrifugal force when the main shaft and the cylinder body are rotated during machining. Furthermore, the inner peripheral surface of the hole further moves the lubricating oil along the cone-shaped cylinder hole so that the lubricating oil is supplied to a seal provided between the piston portion and the cylinder body. Therefore, the lubricating oil is supplied to the seal as the spindle rotates, and the seal and the lubricating oil can be used to accurately form a seal between the piston portion and the cylinder body. In addition, it can suppress the wear and aging of the seal to prolong the seal. The life of the parts can be prevented as long as possible, and the frequency of replenishing compressed gas can be reduced. d) The gas spring is provided with an energy-enhancing member installed in a gas working chamber and energizing a piston portion toward a tool fixing side. At this time, the 12 553795 rod extension is pulled toward the fixed side of the tool due to the increasing force of the compressed gas from the gas working room and the increasing force of the energy-enhancing member. Therefore, if there is a leak of compressed gas, the compressed gas is reduced. In the case of the increase of force, the fixed state of the tool can still be maintained by the increase of the force of the coil spring, which can prevent the tool from falling from the spindle during the spindle rotation. In addition, the air pressure of the gas working chamber can be reduced by the weighting force of the energy-enhancing member, which makes it difficult to leak air. e) The diameter of the cylinder body may be configured to be slightly the same as or larger than the diameter of the main shaft. At this time, 'because the diameter of the gas working chamber in the cylinder body can be made larger, even if the length of the gas working chamber is shortened, the required volume can be ensured, and the overall length of the main shaft assembly composed of the main shaft or the tool fixing device can be shortened. . In addition, increasing the diameter of the gas working chamber can also increase the area of the air bearing surface of the piston. Therefore, even if the air pressure of the gas working chamber is reduced, the tool can be firmly fixed, making it difficult for the gas to leak into the gas working chamber. in. f) The gas spring includes: a sealing member for forming a sealed state between the piston portion and the cylinder body; and a lubricating oil for lubricating between the piston portion and the cylinder body and sealing the compressed gas. At this time, since a seal is formed between the piston portion and the cylinder body by means of a seal and lubrication, leakage of compressed gas into the gas working chamber can be suppressed as much as possible. £) The above-mentioned cylinder body has a filling port for pouring compressed gas and lubricant into the gas working chamber. Therefore, compressed gas and lubricating oil can be injected from the charge α. h) Radiating fins may also be provided at the outer periphery of the cylinder body. By structuring the heat dissipation of the gas spring in this way, it is possible to prevent the compressed gas from expanding due to the heat generated during machining 13 553795, which can cause the air pressure to rise too much, thereby increasing the leakage of compressed gas. In addition, it is also possible to suppress the decrease in oil viscosity caused by the temperature rise of the lubricating oil, and to suppress the deterioration of the lubricating performance and sealing performance of the lubricating oil as much as possible. i) The above-mentioned fluid pressure cylinder may be provided with a boosting force detecting device for detecting the boosting force of the gas spring when the tow bar is driven toward the fixed release side. In order to release the fixed state of the tool, the force of the gas spring can be detected when the tow bar extension is driven to the fixed release side by the fluid pressure cylinder. Therefore, it can be checked periodically before the machining process to determine whether it is lowered by air leakage. Applying force can prevent the possibility of machining in the state of reducing the increasing force. [Embodiment] Hereinafter, the best form for implementing this invention is demonstrated. This embodiment is one aspect in which the present invention is applied to a machining center. Incidentally, the up-down, left-right, and left-right directions in FIG. As shown in Figs. 1 and 2, the main shaft assembly 1 includes: a main shaft 2; a shaft housing 3 including a drive motor 16 for rotating the main shaft 2; and a tool fixing device 4 for fixing or releasing the tool 5 Ground is fixed on the main shaft 2. The tool fixing device 4 has a chuck 10, which is connected to the base end of the tool 5; a traction rod 11 can be connected to the base end of the tool 5 by using the chuck 10; An upward force is generated for the tow lever 11 (tool fixing side); the release mechanism 13 is capable of driving the tow lever downward (fixed release side) against the increasing force of the energy increase mechanism 12. At the front end portion of the main shaft 2, a tool holding portion 2 a having a diameter increasing toward the front end and having a cone shape of 14 553795 is formed, and at the tool holding portion 2 a, a type formed on the base end side of the tool 5 may be combined. And a tapered shank 5 a. The main shaft 2 is disposed inside the shaft housing 3 in a vertical posture, and both ends of the main shaft 2 are rotatably supported on the shaft housing 3 through bearings 14 and 15. In the motor housing portion 3a of the shaft housing 3, a drive motor 16 is installed to rotate and drive the main shaft 2 to the shaft housing 3. Inside the main shaft 2, a tool holding portion 2a and a receiving hole 2b connected to the upper end of the tool holding portion 2a are formed in a row. The tool 5 has: a shank portion 5 a that can be embedded in the tool holding portion 2 a; a small-diameter shaft portion 5 b and an engaged portion 5 c are formed at the base end portion of the shank portion 5 a; a large-diameter clip The holding portion 5 d is formed at the front end portion of the shank portion 5 a and is held by an automatic tool exchange device (not shown) during exchange. In a state where the tool 5 is mounted on the main shaft 2, the shank portion 5a is tightly coupled to the tool holding portion 2a, and the engaged portion 5c is in a state facing the front end portion of the receiving hole 2b. Two tube members 20 and 21 are installed inside the accommodation hole 2b, and a collet 10 is arranged inside the front end portion of the tube member 20. The chuck 10 is configured to clamp the to-be-engaged portion 5c of the tool 5 by the chuck dividing portion 10a divided into a plurality of pieces. On the inside of the barrel members 20 and 21, a traction rod 11 is provided to be able to move up and down. The tow bar 11 includes a tow bar body 22, and a connecting body 23 fixed to a front end portion of the tow bar body 22. At the base end side of the towbar main body 22, a towbar extension 24 is formed to extend beyond the end faces of the main shaft 2 and the shaft housing 3, and an energy-enhancing mechanism 12 and a release mechanism 1 are connected to the towbar extension 24. 3. The lower end portion of the tow bar main body 22 is screwed into the coupling body 23 in an inset shape, and the chuck 10 and the gasket 25 are coupled to the coupling body 23. 15 553795 As shown in FIG. 1, in the state where the energy-increasing mechanism 12 is used to generate upward force on the traction rod 11, the chuck 10 maintains the state of the engaged portion 5 c of the holding tool 5 and increases upward. The force can fix the tool 5 to the tool holding portion 2a. In contrast, as shown in FIG. 2, in a state where the traction lever 11 is driven downward by the release mechanism 13, the chuck 10 is also moved downward to a state where the chuck splitting portion 10 a is separated, and The fixed state of the tool 5 is released. A passage 22a is formed inside the drawbar main body 22 to circulate the cutting fluid supplied to the tool 5, and a front end pipe 26 is also connected to the passage 22a inside the connecting body 23. In a state where the tool 5 is mounted on the tool holding portion 2 a, the front end portion of the front end pipe 26 is pushed to the engaged portion 5 c, and the cutting fluid is supplied from a cutting fluid supply device (not shown) and It is supplied to the tool 5 through the rotary joint 27, the passage 2 2a, and the front pipe 2 6. Next, the energy-enhancing mechanism 12 will be described. As shown in FIG. 1 to FIG. 4, the energy-increasing mechanism 12 has a gas spring 30 for urging the traction rod 11 toward the tool fixing side at the traction rod extension 24. The gas spring 30 includes a cylinder main body 31, which is sleeved on the traction rod extension 24 and is screwed and connected to the base end of the main shaft 2 in a manner of rotating with the main shaft 2; a cylinder hole 3 1 a is formed in the cylinder Inside the main body 3 1; the piston portion 3 2 ′ is integrally installed at the middle portion along the length direction of the tow bar extension portion 24 and is movable on the cylinder hole 3 1 a; the gas working chamber 3 3, A compressed gas 3 4 is formed on the lower side (main shaft side) of the piston portion 3 2 in the cylinder hole 3 1 a. The cylinder main body 31 is configured to have a diameter substantially the same as that of the main shaft 2 and is screwed to the main shaft 2 at a lower end portion of the cylinder main body 31. A through hole 3 1 b is formed at the shaft center of the lower end portion of the cylinder main body 16 553795 body 3 1 for passing through the tow bar extension portion 2 4. At the lower left and right sides of the cylinder main body 31, at the left and right symmetrical positions, two filling ports 3 1 c are respectively used to supply the compressed gas 3 4 and the lubricating oil described later to the gas working chamber 3 3. When the gas spring 30 is to be detached from the main shaft 2, the compressed gas 34 can be discharged through the filling port 31c. Furthermore, as shown in FIG. 3 and FIG. 4, a cylinder hole 3 1 a connected to the upper end of the through hole 3 1 b is formed inside the cylinder body 3 1, and the diameter of the cylinder hole 3 1 a is reduced toward the main shaft side. . A piston portion 32 integrally formed with the tow bar extension portion 24 is slidably mounted on the cylinder hole 3 1 a. Synthetic resin seals 3 5 and 36 are provided on the cylinder hole 31a and the piston portion 32, and between the through hole 3 1 b and the tow bar extension portion 24, respectively. In the gas working chamber 33, a high-pressure (for example, about 3 to 7 MPa) compressed gas 34 (for example, high-pressure nitrogen) is sealed, and the compressed gas 34 generates an upward increasing force for the piston portion 32. Here, since the diameter of the cylinder body 3 1 is substantially the same as that of the main shaft 2, it is possible to enlarge the gas working chamber formed in the compressed gas 3 4 compared with the state in which the gas spring 30 is built in the main shaft 2. The diameter of 33 can shorten the length of the cylinder main body 31 in the vertical direction, and can further shorten the length of the spindle assembly 1. In addition, the area of the pressure bearing surface on the piston portion 32 can be increased, and even if the pressure of the compressed gas 34 is slightly reduced, the boosting force required to firmly fix the tool 5 can be ensured, and the pressure of the compressed gas 34 can be reduced. Gas Studio 33. In this gas working chamber 3 3, a lubricating oil 3 7 is sealed to lubricate between the tow bar extension 2 4 and the cylinder body 31 and to seal the compressed gas 17 553795 3 4. The lubricating oil 3 7 is naturally supplied to the seal 36 between the tow bar extension 2 4 and the through hole 3 1 b by gravity drop, and together with the seal 3 6 forms the tow bar extension 2 4 and Sealed state between the through holes 3 1 b. Furthermore, as described above, the cylinder hole 3 1 a is formed in a tapered shape that is reduced downward, so that when the main shaft 2 is rotating at a high speed (for example, higher than 20,000, 0 0 s pm), the lubricating oil 37 is subjected to high speed rotation The resulting centrifugal force is attached to the inner peripheral surface of the cylinder hole 3 1 a. Furthermore, the attached lubricating oil 3 7 moves upward along the cylinder hole 3 1 a and is supplied between the piston portion 3 2 and the cylinder body 31. The lubricating oil 3 7 on the sealing member 3 5 can lubricate between the piston portion 32 and the cylinder body 31, and can also form a sealed state between the cylinder body 31 with the sealing member 3 5 . Next, the release mechanism 13 will be described. As shown in FIG. 1 to FIG. 4, the release mechanism 13 has a hydraulic cylinder 40 connected to the base end of the gas spring 30 so as to be relatively rotatable with the gas spring 30, and the gas spring 30 and the hydraulic cylinder 40 ′ It is configured as an integrated unit that can be pre-assembled before being mounted on the spindle unit 1. The hydraulic cylinder 40 includes a hydraulic cylinder main body 41 and a cylindrical piston member 4 2 which is slidably fitted on the upper side of the piston portion 32 of the tow bar extension 2 4 and is provided with a free sliding The piston portion 4 2 a is installed on the hydraulic cylinder hole 4 1 a of the hydraulic cylinder body 41, and the oil chamber 43 is driven downward by the piston portion 4 2 a. The hydraulic cylinder main body 41 is connected to the base end of the cylinder main body 31 that is relatively rotatably connected to the gas spring 30 by a plurality of connecting divided bodies 44 divided in the circumferential direction. In other words, although the gas spring 30 rotates integrally with the main shaft 2, it is configured without rotating the hydraulic cylinder 40. At the upper end of the cylinder main body 18 553795, an oil pressure supply port 4 1 b is provided for supplying oil pressure into the oil chamber 43. Furthermore, a position detection switch 45 is provided at the upper end portion of the hydraulic cylinder main body 41 to detect the position of the tow bar 11 in the fixed state and the unlocked state of the tool 5, and in addition, at the extension of the tow bar A test object 4 6 is provided on 2 4, which is detected by a position detection switch 45. The cylindrical piston member 4 2 is fitted on the tow bar extension portion 24 so as to be able to slide up and down and rotate. As shown in Fig. 3, the piston portion 32 of the gas spring 30 is located at the upper limit position, and the tool 5 is in a fixed state. The lower end of the piston member 42 is separated from the upper end of the piston portion 32. At the lower end of the piston member 42, a load cell 4 7 (power increase detection device) is provided to be electrically connected to a control unit (not shown). Once the tow bar extension 2 4 is moved by the hydraulic cylinder 40 When the fixed release side is driven, the piston member 4 2 is driven downward, so that the upper end of the piston portion 32 is in contact with the load cell 47, and the force sensor 4 7 is used to detect the increasing force of the gas spring 30, such as Shown in Figure 4. An oil chamber 4 3 is formed on the upper side of the piston portion 4 2 a. Once oil pressure is supplied from a hydraulic pressure supply source (not shown), the piston portion 4 2 a is driven downward, and then the lower end of the piston member 4 2 is connected to At the upper end of the piston portion 32 of the gas spring 30, the piston portion 32 can be driven downwards against the increasing force caused by the compressed gas 34. In addition, an air chamber 48 is formed at the lower side of the piston portion 42a, and the air chamber 48 is connected to a pressure accumulator (not shown), and the air chamber 48 is filled with a pressurized gas having a relatively low air pressure. Therefore, in a state where the hydraulic pressure 尙 is not supplied into the oil chamber 43 (tool fixed state), the piston portion 42 a generates an upward force using the pressurized gas in the air chamber 48 to avoid the piston portion 32 and the piston member 4. 2 is constituted by contacting the gas spring 30 with the main shaft while rotating integrally. 19 553795 First, as shown in FIG. 1, in a state where the force of the compressed gas 34 in the gas working chamber 33 is used to apply upward force to the tow lever 11 and the tool 5 is fixed to the tool holding portion 2 a, The hydraulic pressure is supplied to the oil chamber 43 of the hydraulic cylinder 40, so that the piston member 42 of the hydraulic cylinder 40 is driven downward, and the piston member 42 is connected to the gas spring 3 0 through the load cell 4 7 The piston portion 32 of the upper portion is further opposed to the increasing force caused by the compressed gas 34, and the piston member 42 and the piston portion 32 are driven downward as a whole, so that the tow rod 11 is moved downward. Then, the chuck 10 is also moved downward, so that the chuck splitting section 10a is opened, and the fixed state of the tool 5 of the tool holding section 2a can be released (see Fig. 2). At this time, the force increase sensor 47 can be used to detect the increasing force of the gas spring 30, and the gas pressure state in the gas working chamber 33 can be detected. Next, after the other tool 5 is mounted on the tool holding portion 2 a using an automatic tool exchange device, the oil pressure in the oil chamber 43 is discharged, and the piston portion 32 of the gas spring 30 is received by the increasing force of the oil chamber 43. Downward movement also moves the traction lever 11 and the collet 10 downward, and then the clamped part 5c of the clamped part 5c of the tool 5 is clamped by the chuck splitting part 10a, and the traction lever 11 is moved upward, so that the tool 5 It is firmly fixed to the tool holding part 2a. Maintaining this state, in order to perform a machining process on the workpiece, 'the spindle 2 is rotated at a high speed, the lubricant 3 7 in the gas working chamber 3 3 is attached to the inner peripheral surface of the cylinder hole 3 1 a by centrifugal force, Furthermore, the lubricant 3 7 can be moved upward along the cylinder hole 3 1 a formed in a tapered diameter, and the lubricant 3 7 can be supplied to the seal between the piston member and the cylinder member. On the part 35, the seal state between the piston part 32 and the cylinder body 31 is formed by the seal part 35 and the lubricating oil 3 7 accurately 20 553795. In contrast, the lubricating oil 3 7 is naturally supplied to the seal 3 6 located between the through-hole 3 1 b and the drawbar extension 24 by gravity, so that it is also accurately formed on the through-hole 3 1 b. Sealed state between the tow bar extension 24 and the cylinder body 31. In addition, the lubricating oil 3 7 has a relatively high viscosity, and once the lubricating oil 3 7 is supplied between the cylinder bore 3 U and the piston portion 32 2, the lubricating oil 3 7 is compressed with the seal 35. The gas 34 increases energy upward, so that the lubricating oil 3 7 between the cylinder bore 3 1 a and the piston portion 32 cannot be easily dropped, so that the sealing performance of the seal 35 is hardly reduced when the main shaft 2 is stopped. According to the above-mentioned tool fixing device 4, the following effects can be obtained: The hydraulic cylinder 4 is connected to the base end of the gas spring 30 in a relatively rotating manner, and then it can be constructed into a type that can be installed on the main shaft The single component previously assembled on the module 1 can make the energizing mechanism 12 and the releasing mechanism 13 compact, and it is easy to mount the energizing mechanism 12 and the releasing mechanism 13 on the spindle assembly 1. In the gas working chamber 3 3, a lubricating oil 3 7 is sealed to lubricate between the tow bar extension 2 4 and the cylinder main body 31 and to form a sealed state in the compressed gas 3 4. Furthermore, the cylinder hole 3 1 a is formed into a tapered shape with a diameter decreasing downward, so that the lubricating oil 3 7 attached to the inner peripheral surface of a a can be subjected to the centrifugal force caused by the high-speed rotation of the main shaft 2 along the tapered cylinder hole 3 1 a is supplied to the seal 35. Therefore, the lubricant 3 7 is supplied to the seal 35 as the spindle 2 rotates, so that the seal between the piston portion 3 2 and the cylinder body 31 can be accurately formed by the seal 35 and the lubricant 37. In addition, the wear and aging of the seals can be suppressed to prolong the life of the seals 3 5 21 553795. The compressed gas 34 can be prevented from leaking into the gas working room 3 3 for as long as possible, and the frequency of supplemental compressed gas 34 can be reduced. Since the cylinder main body 31 is configured to have a diameter substantially the same as that of the main shaft 2, the diameter of the gas working chamber 3 3 formed inside the cylinder main body 31 can be increased, which can shorten the length of the cylinder main body 31 in the vertical direction, and also shorten the length of the cylinder main body 31. Spindle assembly 1 overall length. In addition, since the pressure-bearing area of the piston portion 32 that can withstand the increasing force of the compressed gas 34 can also be increased, even if the pressure of the compressed gas 34 is set to a low value, it is possible to sufficiently ensure that the required increase of the tool 5 can be fixed. Force, and by reducing the pressure, the compressed gas 34 can be prevented from leaking into the gas working chamber 33 easily. In order to release the fixing of the tool 5 each time, when the tow bar extension 24 is driven toward the fixed release side by the hydraulic cylinder 40, the force increase sensor 47 can be used to detect the increasing force of the gas spring 30 so as to be able to periodically It is possible to prevent the possibility of mechanical processing in the state of decreasing the increasing force by checking whether the increasing force is reduced due to the leakage of the compressed gas 34. Next, a description will be given of a modified form in which various changes are applied to the above embodiment. However, components having the same structure as those of the above-mentioned embodiment are denoted by the same reference numerals and explanations thereof are appropriately omitted. 1] As shown in FIG. 5, in the tool fixing device 4A, a heat sink 50 may be formed at the outer peripheral portion of the cylinder body 3 1A of the gas spring 30A of the booster mechanism 12A. By structuring the heat radiation of the gas spring 30A in this way, it is possible to prevent the compressed gas 34 from being expanded due to the heat generated during the machining process, which may cause the pressure to rise too much, thereby increasing the leakage of the compressed gas 34. Furthermore, by suppressing the decrease in viscosity of the lubricating oil 37 due to the temperature rise of the lubricating oil 37, 22 22553795 suppresses the decrease in the lubricating performance and sealing performance of the lubricating oil 37 as much as possible. 2] When it is necessary to use the gas spring 30 to generate a greater boosting force, the cylinder body 31 can be configured to have a diameter larger than that of the main shaft 2. In other words, the diameter of the cylinder body 31 can be appropriately changed in accordance with the increasing force required to firmly fix the tool 5 and the pressure of the compressed gas 34 to be enclosed. 3] It can also be constituted by: installing an energy-enhancing member such as a rotary spring, instead of supplying pressurized gas to the air chamber 48 of the hydraulic cylinder 40, and then using the boosting force caused by the energy-enhancing member to provide piston members An upward increasing force is generated at 42 to prevent the piston member 42 from engaging with the piston portion 32 when the main shaft 2 rotates. Of course, the supply of oil pressure may also be used to drive the piston member 42 upward by the oil pressure. 4] In the above embodiment, although the present invention is applied to the spindle assembly 1 of the vertical machining center, the present invention is also applicable to the spindle assembly 1 of the horizontal machining center. In this case, since the cylinder hole 3 1 a is formed in a tapered shape with a diameter decreasing toward the main shaft side, the lubricating oil 3 7 in the gas working chamber 3 3 is supplied to the rotation of the main shaft 2 and the cylinder body 31. The seal 35 between the piston portion 32 and the cylinder body 31 can be used to accurately form a sealed state between the piston portion 32 and the cylinder body 31 by using the seal 35 and the lubricant 37. In addition, another embodiment of the present invention will be described. As shown in FIG. 6, the tool fixing device 4B has a traction rod 11B that can be connected to the base end of the tool; an energy-enhancing mechanism 12B generates an upward (tool fixing side) increasing force for the traction rod 1 1 B; And the driving mechanism 13B can drive the tow bar 11B downward (fixed release side) against the increasing force of the energy increasing mechanism 12B. At the base end side of the tow bar 1 1 B, a tow bar extension 23 553795 is formed to extend beyond the end face of the base end of the main shaft 2B. The energy-increasing mechanism 12B has a gas spring 30B that generates a downwardly increasing force on the tow bar extension 1 60 on the tow bar extension 60. The driving mechanism 1 3 B has a hydraulic cylinder 4 0B having a structure similar to that of the above embodiment, and the hydraulic cylinder 4 0 B is relatively rotatably connected to the gas spring 3 0B by using a plurality of connecting divisions 44B. On the base end, the gas spring 3 0 B and the hydraulic cylinder 4 0 B are configured as a single component. The gas spring 30B includes a cylinder body 31B, which is fitted on the extension 60 of the tow bar and is fixedly connected to the base end of the main shaft 2 B in a manner of integral rotation; a cylinder hole 61 is formed in the cylinder body 31B; a piston portion 32B, which is integrally installed at the middle portion in the longitudinal direction of the towbar extension 24 and can be moved on the cylinder hole 61 by a predetermined stroke; the gas working chamber 3 3 B, for the piston portion in the cylinder hole 61 A compressed gas 34 is formed and enclosed in the lower side of the 32B (the main shaft side), and a coil spring 62 (energizing mechanism) is installed in the compressed gas 34B and generates a downward increasing force on the piston portion 32B. As in the above-mentioned embodiment, the cylinder hole 61 is formed in a tapered shape having a reduced diameter, and between the cylinder hole 61 and the piston portion 3 2B, and between the through hole 63 through which the tow bar extension 60 passes. , Respectively installed with seals 3 5B, 3 6B. Furthermore, a lubricating oil 37 is also injected into the gas working chamber 33B. The coil spring 62 is sleeved at the extension portion 60 of the tow bar 60 in the gas working chamber 33B, and is connected to the annular spring receiving portion 64 formed at the lower end portion of the piston portion 32B, so as to generate upward force for the piston portion 32B. . In other words, the towbar extension 60 is caused by the increasing force caused by the compressed gas 34 in the gas working room 33B and the increasing force caused by the coil spring 62 24 553795. Therefore, even if the compressed gas 34 in the gas working chamber 33B is low, the increasing force required to securely fix the tool can be ensured, and the compressed gas 34 can be prevented from leaking easily. In addition, if the increasing force is reduced due to the leakage of the compressed gas 34, the fixed force of the tool can still be maintained by the increasing force of the coil spring 62, so that the tool can be prevented from falling from the spindle 2B during machining. Incidentally, as for the number of the coil springs 62, it is not limited to one piece, and the number of the coil springs 62 can be appropriately changed according to the increasing force required to firmly fix the tool. Moreover, other energizing members such as a disc spring may be used instead of the coil spring 62. The present invention is not limited to the above-mentioned embodiments, and should include those who can implement the modifications made to those forms by those skilled in the art without departing from the spirit and scope of the present invention. [Brief Description of the Drawings] Fig. 1 is a longitudinal sectional view of a spindle assembly (tool fixed state) of a machine tool according to an embodiment of the present invention. Fig. 2 is a longitudinal sectional view of the main shaft assembly (in a state where the tool fixing is released). FIG. 3 is an enlarged sectional view of an energy increasing mechanism and a releasing mechanism (a tool is fixed) of a spindle assembly. Fig. 4 is an enlarged cross-sectional view of the energizing mechanism and the releasing mechanism of the spindle assembly (the tool is released from the fixed state). FIG. 5 is a diagram of FIG. 3 in a considerably modified form. Fig. 6 is an enlarged sectional view of an energy increasing mechanism and a releasing mechanism of a spindle assembly according to another embodiment. 25 553795 [Explanation of component symbols] 1 Spindle assembly 2 Spindle 2 a Tool holding part 2b Storage hole 3 Shaft housing 3a Motor storage part 4 Tool fixing device 5 Tool Lu 5 a Handle 5 b Small-diameter shaft part 5c Coupling part 5 d Clamping section 10 Collet 10a Collet dividing section 11 Traction rod 0 12 Energizing mechanism 13 Release mechanism, 14 '15 Bearing 16 Drive motor 20' 21 Bar member 22 Traction rod body 22a Passage 23 Connecting body 26 553795 24 、 60 Tow bar extension 25 Gasket 26 刖 End pipe 27 Swivel joint 3 0 Gas spring 3 1 Cylinder body 3 1a 、 6 1 Cylinder hole 3 1b Through hole 3 1c Filling 32 Piston part 3 3 Gas working room 34 Compressed gas 35 '3 6 Seal 3 7 Lubricating oil 40 Hydraulic cylinder 4 1 Hydraulic cylinder body 4 1a Hydraulic cylinder hole 41b Hydraulic pressure supply port 42 Piston member 42a Piston part 43 Oil chamber 44 Connecting division 45 Position detection switch 46 Test body
27 553795 47 測力感應器 48 氣室 50 散熱片 62 螺旋彈簧 63 穿通孔 64 彈簧承受部27 553795 47 Load cell 48 Air chamber 50 Heat sink 62 Coil spring 63 Through hole 64 Spring receiving part
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