1591-五軸加工中心的數(shù)控編程后置處理研究（只有說明書）

1591-五軸加工中心的數(shù)控編程后置處理研究（只有說明書）,加工,中心,數(shù)控,編程,后置,處理,研究,鉆研,只有,說明書,仿單 致 謝本論文從論文的選題、資料的收集、分析以及研究工作的展開到形成論文初稿、修改直至最終定稿，都是在于斐老師的大力支持下完成的。于斐老師的悉心指導(dǎo)和中肯指正，凝結(jié)著智慧和辛勞，同時對我的本科論文的寫作給予了很大的幫助。盡管余老師的工作很忙，但每次老師都能對我的聯(lián)系和溝通做出及時的回復(fù)并對我遇到的難題給予認真的解答，使我更加有信心地完成論文的寫作，在這里真的非常感謝余斐老師。同時，對四年來為我們的成長付出心血的科技學(xué)院老師們表示感謝，也要感謝全體同窗，感謝他們在我的學(xué)習(xí)上所給予的關(guān)心、幫助和鼓勵。本文在寫作過程中，參閱了大量的相關(guān)研究著作，謹在此對他們的工作表示謝意。最后，對在百忙之中對我的論文進行評審并提出寶貴意見的各位專家、教授致以誠摯的謝意。通過立式六軸控制并應(yīng)用超聲振動加工銳角轉(zhuǎn)角這項研究提出了一種可以產(chǎn)生一個懸垂銳角轉(zhuǎn)角的新的加工方法. 對于傳統(tǒng)的加工方法，甚至是 3 到 5 軸放電加工而言，加工垂直面上的的銳角轉(zhuǎn)角是很難的，尤其是當(dāng)其表面有不同的角度的時候。這是受進給方向和機床的電極結(jié)構(gòu)必須與目標(biāo)的輪廓對稱的限制. 在本研究中,我們試圖采用新的加工方法來加工外表面的銳角轉(zhuǎn)角. 6 軸控制加工適用于以任意位置和任意姿勢順著工件設(shè)置一非回轉(zhuǎn)刀具。在切削過程中，當(dāng)?shù)毒哐刂M給方向切削時，超聲振動被應(yīng)用在刀具的切削邊緣. 當(dāng)進行切削的時候， 6 軸 (X、Y 、Z 、A、B 和 C)順著刀具在某一點的姿勢同時移動。從實驗結(jié)果中發(fā)現(xiàn)五軸控制超聲振動切削能在垂直面產(chǎn)生一銳角轉(zhuǎn)角。關(guān)鍵字:六軸控制切割、計算機輔助設(shè)計/計算機輔助制造系統(tǒng)，微型鉆,垂直銳角轉(zhuǎn)角,超聲振動刀具。1. 緒論 如果制造過程中的限制可以最小化或者消除，該產(chǎn)品的靈活性可極大發(fā)揮。如果象球頭立銑或者平頭銑刀這類回轉(zhuǎn)刀具用在加工一含有垂直銳角轉(zhuǎn)角的模具中，對于能清楚獲得有尖銳邊緣線的目標(biāo)形狀來說，這似乎是困難的。這是由于使用了與旋轉(zhuǎn)運動對稱的旋轉(zhuǎn)刀具的原因。在相鄰表面產(chǎn)生了類似圓弧的加工痕跡，如圖一所示。按照慣例，大部分垂面或者斜面可以靠將工件依照基準(zhǔn)設(shè)置在某一角度，并轉(zhuǎn)動整個基準(zhǔn)，或者靠將刀頭設(shè)置成某一角度并且進給切刀的頭部，如圖 2(a)所示. 在這個過程中,在工件底部的鋒利的邊緣和垂面被加工出來. 不過,如果對象是由兩個垂面組成的 OHSC 并且表面傾角是不一致的，由于在此過程中的切削方向是固定的并且僅僅局限于線性切割，目標(biāo)形狀是很難達到的。因此，這就需要大量的夾具和裝備來夾緊工件、使工件在機床上保持正確的位置并且在加工的過程中支撐工件。圖 2 含有懸垂面的銳角轉(zhuǎn)角的加工方法來生產(chǎn)這種外形的其他可能的方法就是多主軸放電加工(EDM)，如圖 2（b）所示. 然而,即使是用這種方法,也很難或者根本不可能生產(chǎn)出一含有不同角度的OHSC。這需要 6 個自由度來充分地執(zhí)行可以產(chǎn)生目標(biāo)形狀的加工。在以往的研究中,超聲波振動被應(yīng)用在車削可塑性材料和銑削玻璃纖維加強型材料上。應(yīng)用超聲波振動的切削力大大減少。然而，在先前的過程中，工件被旋轉(zhuǎn)或者移向切削刀具，后來一次加工被限制用 2 到 3 軸控制。在其他領(lǐng)域的研究中，多軸控制機床習(xí)慣于一步完成一次加工，這就產(chǎn)生了擁有高精度、高質(zhì)量和較少加工時間的工件成品。在這項研究中,使用非旋轉(zhuǎn)切削工具結(jié)合超聲振動的使用的 6 軸控制切削,如圖2(C)所示。 它適用于審查 OHSC 構(gòu)成方法的有效性。加工時，C 軸和X，Y，Z ，A 或者 B 軸同時使非旋轉(zhuǎn)刀具旋轉(zhuǎn).軸的運動是基于刀具的姿勢和已經(jīng)開發(fā)的 CAM 軟件所產(chǎn)生的切削點.CAM 系統(tǒng)產(chǎn)生一自由關(guān)聯(lián)的刀具路徑以保證切削過程的安全. 6 軸控制機床輕松地具備了加工 OHSC 的能力,是因為 6 個自由度使形成需要的產(chǎn)品外形得以充分發(fā)揮. 同時，考慮到點鉆刀具在切削操作中的尺寸和硬度，在使用超聲振動使切削力大大削減之后，其才得以利用。2. 實驗程序 實驗步驟如圖 3 所示,其中工件安裝在 6 軸控制加工的工作臺中心. bore byte tool 安裝在使用了轉(zhuǎn)接器的超聲振動刀具上. 該超聲振動刀具被圓周式的安裝在6 軸控制加工中心上.在以往的研究中,超聲波振動被應(yīng)用在車削可塑性材料和銑削玻璃纖維加強型材料上。應(yīng)用超聲波振動的切削力大大減少。然而，在先前的過程中，工件被旋轉(zhuǎn)或者移向切削刀具，后來一次加工被限制用 2 到 3 軸控制。在其他領(lǐng)域的研究中，多軸控制機床習(xí)慣于一步完成一次加工，這就產(chǎn)生了擁有高精度、高質(zhì)量和較少加工時間的工件成品。在這項研究中,使用非回轉(zhuǎn)切削工具結(jié)合超聲振動的使用的 6 軸控制切削,如圖 2(C)所示。 它適用于審查 OHSC 構(gòu)成方法的有效性。加工時，C 軸和X，Y，Z ，A 或者 B 軸同時使非旋轉(zhuǎn)刀具旋轉(zhuǎn).軸的運動是基于刀具的姿勢和已經(jīng)開發(fā)的 CAM 軟件所產(chǎn)生的切削點.CAM 系統(tǒng)產(chǎn)生一自由關(guān)聯(lián)的刀具路徑以保證切削過程的安全. 5 軸控制機床輕松地具備了加工 OHSC 的能力,是因為 6 個自由度使形成需要的產(chǎn)品外形得以充分發(fā)揮. 同時，考慮到點鉆刀具在切削操作中的尺寸和硬度，在使用超聲振動使切削力大大削減之后，其才得以利用。2.1 多軸機床工具和微型鉆孔器被用來研究的 6 軸加工中心如圖 4 所示。 加工中心準(zhǔn)備有多軸 CNC 加工刀具。該 6 軸控制機床有 3 個轉(zhuǎn)動軸 A，B 和 C。它是由 5 軸控制加工中心再在主軸上加上一個 C 功能軸組成的,這種 5 軸加工中心有 2 個旋轉(zhuǎn)軸，即旋轉(zhuǎn)的可傾斜工作臺的 A 軸和旋轉(zhuǎn)的可標(biāo)志工作臺的 B 軸。X、Y、Z 的最小位移為1 微米,A 、 B 和 C 軸的最小旋轉(zhuǎn)量是 0.35 弧度每秒.由于 OHSC 的切削,A 軸用來確定邊緣面和銳角的傾角角度、B 軸用來使工件轉(zhuǎn)動、C 軸用來確定刀具的切削方向,X、Y 軸來確定進給方向，同時，切削深度由 Z 軸確定. 圖 5 顯示了用于研究的非旋轉(zhuǎn)刀具(bore byte tool). 它通常是由經(jīng)常用于 6 軸控制切削的鎢炭化物組成的.刀具的總長和直徑分別為 70 毫米和 5 毫米. 2.2 超聲波振動工具圖 5 是一種商業(yè)上可用的用于研究的超聲振動刀具(SB-150:電化鈷). 該USV 應(yīng)用于切削工具。為了完成一次有效率的和有效的振動切削，振動方向必須與切削方向設(shè)置平行。 由于振動方向并不總是與進給方向平行,微型鉆孔器的姿勢就被設(shè)置了. 如同圖 7(a)描述的,刀具軸參數(shù) T 和刀具方向參數(shù) D 分別被任務(wù)中的的旋轉(zhuǎn)和傾斜所修正。這些被修改到修正刀具軸參數(shù) T 和修正刀具方向參數(shù)上，如圖 7（b）所示。該刀具軸參數(shù)和刀具方向參數(shù)的改變在刀位轉(zhuǎn)換中被實施。2.3 計算機輔助設(shè)計/計算機輔助制造系統(tǒng) 6 軸計算機輔助設(shè)計/計算機輔助制造系統(tǒng)的構(gòu)成如圖 8 所示。目標(biāo)輪廓的3D-CAD 數(shù)據(jù)形成于此。 ，必須根據(jù)目標(biāo)形狀來挑選微型鉆孔器類型. 中央處理器產(chǎn)生不相干涉的包含刀具與刀位信息的 CL 數(shù)據(jù)和有關(guān)目標(biāo)形狀的 3D—CAD 數(shù)據(jù)。圖 7 微型鉆的振動方向的調(diào)節(jié) 后處理將中央處理器產(chǎn)生的 CL 數(shù)據(jù)轉(zhuǎn)化為與加工中心的坐標(biāo)系統(tǒng)相匹配的 6 軸控制 NC 數(shù)據(jù)，這些信息由加工中心，設(shè)置信息，切削條件和振動條件組成。另外，為了保持加工中心的進給速度達到常數(shù)并使刀具路徑的背離最小化，要做所謂的線性操作。這就達到了保證產(chǎn)品表面，尤其是正在處理的曲面的光潔度的目的。在 CL 數(shù)據(jù)轉(zhuǎn)換成 NC 數(shù)據(jù)之前,必須首先檢查 CL 數(shù)據(jù)的干涉情況，以保證加工過程中的安全性. 如果在此階段檢查出干涉，要用中央處理器來對 CL 數(shù)據(jù)進行修改。3.制造帶有懸垂面的銳角轉(zhuǎn)角 3.1 確定刀具姿勢 為了表達 9 軸控制的超聲振動切削時整個刀具的姿勢，如圖 9 所示的微型鉆孔器的姿勢被切削點 P 的坐標(biāo)、刀具的軸矢量 T 和刀具方向矢量 D 所指定。這種 PTD 坐標(biāo)被轉(zhuǎn)換為 NC 數(shù)據(jù)并在加工過程中依次使用. 在應(yīng)用超聲振動的五軸控制切削中，刀具的運動和姿勢的決定必須考慮到振動的方向。 由于切削方向迅速的變化, 為了保持刀具角度與外形表面保持一致，刀具的姿勢要大幅度改變。3.2 刀具路徑的產(chǎn)生 產(chǎn)生 OHSC 的刀具路徑的方法可以描述如下： 該 OHSC 由兩個邊脊線組成，如圖 10 所示. 所謂的橫斷線被稱為底面脊線，交叉線被稱為邊脊線. 制造銳角轉(zhuǎn)角要求完成邊脊線和底面脊線。3.2.1 側(cè)面的刀具路徑的形成產(chǎn)生邊脊線的表面分別由左面和右面組成.在加工一銳角轉(zhuǎn)角的邊脊線過程中，加工左面和右面是必要的。圖 11 描述了產(chǎn)生 OHSC 的邊緣面的刀具軌跡輪廓的方法?；谖⑿豌@孔器的型號和目標(biāo)形狀的要求，首先要做的就是側(cè)面的加工和刀具進給方向的選擇。產(chǎn)生邊脊線的鄰接表面用參數(shù) u,v 表示。與參數(shù) v 等價的固定曲線，產(chǎn)生于從表面的上方到底部的區(qū)域內(nèi)。表面分離的數(shù)目輸入被輸入從而不斷產(chǎn)生切削點的數(shù)目。使用參數(shù) u 的評估，每個相關(guān)線的切削點產(chǎn)生，因此切削點之間的距離將被放在指定的評定里。在每個切削點改變刀具的姿勢,刀具在每一個從開始直到形成邊脊線間的切削點不斷移動. 雖然切削點之間彼此連接,為了獲取刀具路徑,由于刀具結(jié)構(gòu)和目標(biāo)產(chǎn)品的形狀的原因，僅靠一個方向而加工兩個相鄰邊是很難的。此外,刀具和工件之間可能發(fā)生干涉. 在這種情況下,刀具從加工左側(cè)面的路徑的起始點開始，結(jié)束于邊脊線形成的拐角處. 如此反復(fù),直至到達形面的底部.切削深度取決于曲面曲線總長度的分界線的數(shù)量.因為右側(cè)面仍然有類似圓弧的形狀在其拐角部分殘留，所以右側(cè)面上也要進行同樣的處理. 為了形成清晰的邊脊線，程序幾乎和加工左側(cè)面是一樣的,因而切削終止點和左側(cè)面的加工終點是一樣的。最后點左邊加工,形成了明顯的山脊線.右側(cè)面的加工也用左旋刀具來處理. 側(cè)面的刀具路徑形成過程中，為了使振動方向平行于進給方向矢量 F，刀具方向矢量 D 旋轉(zhuǎn)了 10 度。起點到終點的切削點的依次連接形成了刀具路徑 .切削過程中的刀具姿勢取決于切削點的法向量 N 和進給方向矢量 F. 刀具的進給方向矢量 D 和刀具軸線矢量 T 可分別表示為 D=F*N 和 T=N 。3.2.2 底面刀具路徑的形成圖 12 描述了形成 OHSC 的底部 ridgeline 的底面刀具路徑形方法. 在側(cè)面的刀具路徑形成之后，在刀具緊貼底部表面的地方，底部 ridgeline 的刀具路徑接著形成了。這里有兩種產(chǎn)生底部表面的刀具路徑的方法.一種是一步法如左上圖所示，另外的一種是多步法如右上圖所示。一步法中,刀具切削頂點直接接觸底部脊線的位置. 在這種操作中,刀具的傾角對于充分清除殘留在底部的類似圓弧的形狀并形成清晰的山脊線是必要的. 在刀具路徑形成的過程中，基于計算出來的與底面和切削刀具的清除角度相悖的傾角是 5 度，刀具的軸線矢量 T 要傾斜。決定切削起點和切削終點的方法同產(chǎn)生邊緣脊線刀具路徑的方法是一樣的.在多步法中,來自底面的斜度用參數(shù) U 和 V 表示。切削參考線的形成決定于從粗加工后類似圓弧形狀殘余的地方到底步山脊線的參考線之間的最短距離. 切割點的產(chǎn)生基于每個參考線上的參數(shù) v. 系統(tǒng)由在底面的刀具軸線矢量 N 和沿著切削參考線時刀具在切削點的進給矢量 F 來決定切削過程中刀具的姿勢。刀具軸矢量 T 和刀具方向矢量可以分別表達為 T=N 和 D=N*F. 切削起點因為近似圓弧形狀的殘留而得以呈現(xiàn)，并且它結(jié)束于已參考線上已形成的切削點的最后一點，沿著每個相鄰的切削點移動刀具就能形成刀具路徑. 4. 實驗結(jié)果 4.1 對切削力的影響切削力的測量是利用測力計電阻(9257B, Kistler Co ,Ltd),從而以 rms 的形式對切削力進行平均和對其處理。加工受用 USV 和不用 USV 的引導(dǎo)。習(xí)慣的切削條件如下：400mm/min 的進給速度，分別為 0.1，0.2，0.3 的切削深度。振動條件如下：19KHZ 的頻率，35 的振幅和 10 度的轉(zhuǎn)角。已得到的計算結(jié)果如m?表 1 所示。從中可看出有 USV 切削時的切削力與沒有 USV 時的比較起來是非常小的。由于切削力大大減小，刀具的硬度可以在整個切削過程中保持。4.2 OHSC 的加工 切削實驗也用于研究新的加工工藝方法的有效性. 用于實驗的工件的大小是 100×100×20 mm 并且其是一塊鋁合金(a5052JISC),它也是常用的以象鍛模，真空成型，橡膠成型等的低壓成型低成本鑄造材料。兩種類型的 OHSC 模型應(yīng)用在此實驗中 ,一種是帶有平面的 OHSC，另一種是帶有曲面的 OHSC. 側(cè)面由不同的傾角組成.位于切削起點的的表面傾角與切削終點的傾角是不同的。在此情況下 ，傾角在整個過程中不是統(tǒng)一的。圖 13(a)所示的是帶有平面的 OHSC 的模擬加工，為了用 5 軸控制切削執(zhí)行有效的切割，必須首先分別用直徑為 3mm 和 1.5mm 的球頭磨刀進行粗加工。加工進行到目標(biāo)產(chǎn)品的輪廓幾乎形成的時候.如圖 13（b）所示，由于類似圓弧形狀的殘留，目標(biāo)形狀的角度不能很清楚的得到，要用 USV 輔助的 6 軸切削對平面進行修整。在此過程中，可根據(jù)自己的選擇將左側(cè)面或者右側(cè)面首先加工出來。讓我們假定左側(cè)面已經(jīng)加工了. 列入表 2 的切削和振動情況用于開發(fā)的CAM 系統(tǒng)所產(chǎn)生的 NC 指令中。使用基于 NC 加工指令生成的凸輪發(fā)展計劃. 加工完表面一側(cè)后,下一步使用一步法加工底面。 列入表 2 的切削條件應(yīng)用于除了 9 度傾角和 1.5mm 的切削深度中. 切削深度取決于使用球頭磨刀進行粗加工時的類弧形殘留.用右旋刀具對左側(cè)面進行加工。完成了左側(cè)面的加工后,下一步對右表面進行加工，這一步的加工條件，除了使用左旋刀具之外，其它條件幾乎與加工左表面的條件一樣。圖 13（d）顯示的是切削實驗的結(jié)果. 帶有曲面的 OHSC 的加工模型如圖 14（a）所示. 在加工含有曲面的 OHSC中如圖 14(b)所示的粗加工也應(yīng)完成。從粗加工到完工的操作順序和以前所描述的幾乎相同. 但是,為了使產(chǎn)品表面平滑要做所謂的線性化操作。 為了加工形成脊線的底面,要求進行多路徑的加工方法，因為這種方法適合曲面. 表二列出了用于此過程中的切削和振動情況。同樣，圖 14(c)和圖 14(d)分別是真實的加工和完成加工后的產(chǎn)品. 這次實驗的總時間是 112 分鐘，其中包括了粗加工時間。在整個過程中只用到一臺機床和一個工件。在無旋刀具的正常切削速度勝任了切削速率之后應(yīng)用超聲振動而提高切削速率，這一原因使切削效率大幅度改進。5. 結(jié)論 實驗結(jié)果顯示, 微型鉆孔器的使用是最佳的并且由于應(yīng)用超聲振動而使切削力的大大減少而使刀具的硬度能滿足切削的執(zhí)行。.由此而發(fā)現(xiàn)只用一臺機床就能應(yīng)付產(chǎn)品從粗加工到完成的整個過程，這就使由于象將工件從一臺機床到另外一臺這類潛在成本消耗得以消除。因此，為加工含有平面和曲面的 OHSC 的已開發(fā) CAM 軟件在這次研究中得以實驗上的驗證。參考資料 (1)西塞爾 J，一設(shè)計自動化裝置的設(shè)計方法，先進制造技術(shù)國際雜志,第 18 冊,第 11 號(2001),pp.790-793. (2)Moriwaki , TSHANMOTO，E 和 Inoue，應(yīng)用超音波振動的柔性玻璃切割，CIRP 年報,第 41 冊,第 1 號 (1992), pp.141-144. (3)Takeyama, H.、 Iijima, N，玻璃纖維加強型塑料的機械性能和超聲波加工的應(yīng)用，CIRP 年報, 第 37 冊, 第 1 號(1998),pp.93-95. (4)Shamoto, E. 、 Moriwaki, T，橢圓振動切削的研究、CIRP 年報,第 43 冊,第 1號(1994),pp.35-38. (5)Moriwaki,T ，Shamoto、E，橢圓振動切削的研究，CIRP 年報,第 44 冊,第 1號(1995),pp.31-34. (5)Takeuchi, Y.、 Suzuki, H，使用多控制軸機床制造的高效準(zhǔn)確性，日本和美國關(guān)于自動化的會議錄，美國機械工程師協(xié)會、ISCIEJ ，7-10,1995, 第 1 冊,pp.343-347. (7)Radzevich, S.P.、 Goodman, E .D，刻紋表面的多軸數(shù)控加工的效率，Nov.9-11，1998,pp42-55. (8)Morishige, K, Kase,K ， Takeuchi, Y，應(yīng)用在 5 軸控制加工的 2 維 C 空間的無干涉路徑的形成,先進制造技術(shù)國際期刊、第 13 冊、第 5 號(1997),pp.393-400. (9)Morishige, K, Kase,K ， Takeuchi, Y,使用用超音波振動刀具的五軸控制的特征線加工、精密工程(ICPE)第 10 次國際討論會、日本橫濱、七月，18-20,2001,pp.249-2553 1Manufacture of Overhanging Sharp Corner by Means of 6-Axis Control Machining with the Application of Ultrasonic Vibrationsfeliciano H.JAPITANA**,koichi MORISHIGE**,shugo YASUDA** and yoshimi TAKEUCHIThe study proposes a new machine method to creat an create an overhanging sharp corner. Sharp corners on overhanging surfaces are difficult to machine in conventional way or even in 3 to 5-aixs EDM especially if the surfaces have different angles. This is due to the limitation of the feed direction and the structure of the electrode wherein it must be symmetrical with the target shape. In present research, we try to machine the sharp corner with overhanging surfaces using the new machining method. The 6-axis control machining is applied to set a non-rotational tool at an arbitrary position with arbitrary position with arbitrary attitude against the workpiece. During cutting, the ultrasonic vibration is applied on the cutting edge of the tool, while the tool travels along the feed direction. As the cutting is performed, the 6-axis (X,Y,Z,A,B ) move simultaneously, depending on the tool attitude at a certain cutting point. Form the experimental results, it is shown that the 6-axis control ultrasonic vibration cutting is capable of producing a sharp overhanging surface. Key Words: 6-axis Controlled Cutting, CAD/CAM System, Bore Byte Tool, Overhanging Sharp Corner, Ultrasonic Vibration Cutting Tool 1. introductionThe flexibility of products may be extended greatly if the restriction in manufacturing process can be minimized or eliminated. If rotational tools such as ball end mills or square end mills are used in the production of a mould with an overhanging sharp corner (OHSC), it seems difficult to clearly obtain the target shape with sharp edge lines. This is due to the result of processing with the rotational tools, Which are symmetrical with the rotation. The arc-like radius remains are produced on adjoining surfaces, as shown in Fig.1Conventionally, most of overhanging or inclined surface can be machined by setting the workpiece at a certain angle in the vise, swivelling the universal vise, or by setting the tool head to a certain angle and feeding the cutting tool head, as shown in Fig.2(a). In this process, the overhanging surfaces and the sharp edges at the bottom are produced. However, if the target is an OHSC consisting of two overhanging side surfaces, and the inclination angle of surface is not uniform, the processing of the target shape is difficult to 2achieve since the cutting direction in the process is fixed and limited only to linear cutting. Thus ,it needs a lot of jigs and fixtures to hold a workpiece ,to position correctly with respect to a machine tool and to support it during machining.Fig.1 6-axis control machining using rotational tool3Fig.2 method of producing sharp corner with overhanging surfacesThe other possible method to produce such a shape is multi-axis Electric Discharge Machining (EDM), as shown in Fig.2(b).However, even using this method ,it is difficult or impossible to produce an OHSC with different angle .It needs 6 degrees of freedom to fully execute the machining of the required shape.In the previous researches, ultrasonic vibration (USV) was applied in turning of ductile material and milling of glassfiber-reinforced plastic. The cutting force with USV is considerably reduced. However , in the former process ,the workpiece is rotated or moves to towards the cutting tool, and in the latter, machining is limited only to 2 or 3 axis control one. In the other field of research, multi-axis control machine tool is used to complete a machining in one setup, which leads to the production of workpiece with high accuracy and quality and to the reduction in machining time.In this study, 6-axis control cutting using a non-rotational cutting tool with the application of ultrasonic vibration (USV) is used, as shown in Fig.2(c).It is applied to scrutinize the validity of the method in the fabrication of OHSC, The C-axis rotates the non-rotational tool simultaneously together with X,Y,Z,A or B axis during machining .The movement of the axes is based on the tool attitude and the cutting point generated by a developed CAM software. The CAM program generates a collision free tool path to assure the safety of the process. The 6-axis control machine tool provides easily the machining capability of OHSC, since 6degrees of freedom make the machining execute fully the required product shape. Also, with the application of USV, a bore byte tool is utilizded, considering its size and stiffness during machining operation since the cutting force is greatly reduced.2. Experimental procedureThe experiment steup is shown in Fig.3, wherein the workpiece is mounted on the table of the 6-axis control machining center. The bore 4byte tool is mounted in the USV tool using an adaptor. The USV tool is turn mounted on the main spindle of the 6-axis control machining center.Multi-axis control machine tool and bore byte toolThe 6-axis control machining center used in the study is shown in Fig.4. The machining center provides multi-axis CNC machine tools.The 6-axis control machine tool has 3 rotational axes A,B and C. It is constructed by adding the rotational function C on the main spindle of a 6-axis control machining center which has 2 rotational axes,namely;A, which is a rotary tilting table and B, which is the rotary index table. The minimum unit for translation movement X,Y and Z is 1 , and that of rotational one A,B and C is 0.36 arc second. m?In the case of cutting of OHSC, A axis is used for determination of side surface and the inclination angle of sharp corner ,B axis for workpiece rotation ,C axis for determination of cutting tool direction, X and Y axis for the determination of feed direction of feed direction while the depth of cut is determined by Z axis. Fig 6 shows the non-rotational cutting tool (bore byte tool) used in the study. It is made of tungsten carbide usually used here in 6-axis control cutting. The total length and diameter of the tool are 70mm and 6mm respectively.5Ultrasonic vibration toolFif.6 is a commercially available USV tool (SB-160:Taga Electric Co). used in the study. The USV is applied on the cutting edge of the tool.In order to perform an efficient and effective vibration cutting, the vibration direction must be set parallel to the cutting direction. Since the vibration direction is not always parallel with the feed direction, the tool attitude of the bore byte tool is subjected to arrangement. As illustrated in fig.7(a), the tool axis vextor T and the tool direction vector D and modified by arranging the rolling and the inclination angle respectively. These are converted into modified tool axis vector T and modified tool direction vector D, as shown in fig.7(b). The transformation of the tool axis vector and the tool direction vector are carried out in cutter location (CL) conversion.6CAD/CAM systemThe configuration of 6-axis CAD/CAM system is shown in fig.8, where 3D-CAD data of the target shape is generated . The type of bore byte tool must be selected, based on the target shape. The main processor generates the collision free CL data on the bases of tool information and tool orientation as well as 3D-CAD data of the target shape.7The post processor converts CL data generated by the main processor into 6-axis control NC data suitable for the coordinate system of the machining center with reference to the structure information of the machining center, setting information, cutting condition and vibration condition. In addition, so-called linearization operation is dine in order to keep the feed rate to the machining center structure constant and to minimize the tool path deviation. It leads to assure the smoothness of the product surface especially in dealing with curve surfaces.Before converting CL data into NC data, CL data must be firstly 8checked for collision to assure the safety of the machining process .If the collision is detected in this stage, the modification of CL data is carried out, using the main processor.3. Manufacture of Sharp Corner with Overhanging Surface3.1Determination of tool attitudeIn order to expresshe entire tool attitude for 9-axis control ultrasonic vibration cutting, the tool attitude of the bore byte tool, as shown in Fig.9, is appointed by the coordinates P for cutting point, the tool axis vector T and the tool direction vector D. These PTD coordinates are converted to NC data, and are in turn used in machining operation. In 6-axis control cutting with application of ultrasonic vibration, the movement and the attitude of the tool must be determined in consideration of the vibration direction. Since the cutting direction changes rapidly, the tool attitude changes a lot to keep the tool angle constant to the surface shape.3.2Generation of tool path The tool path generating method for OHSC can be described as follows; the OHSC is composed with two ridgelines, as illustrated in Fig.10. The intersecting line is called as a bottom ridgeline and the cross section line is called as a side ridgeline .Finishing the side ridgeline as well as the bottom ridgeline is required to make a sharp corner.93.2.1Generation of tool path for side surface The surface that makes a side ridgeline is composed with left and right surfaces respectively. In producing a side ridgeline of the sharp corner, machining of left and right surfaces is necessary. The outline of the tool path generation method for side surfaces of the OHSC is described in Fig.11.The side to be machined and the tool feed direction must be selected at first, based on the type of bore byte tool and the target shape. The adjoining surfaces that make a side ridgeline, is expressed with parameters u and v. The fix curve , which is equal to parameter v, is generated on the side from the upper part of the surface to the bottom. The division number of surface is input to sequentially generate the number of cutting points. Each cutting point on a reference line are generated, using the value of parameter u, so that the distance between the cutting points may settle below in the specified value.Changing the tool attitude at every point of the cutter location ,the tool moves sequentially on each cutting point from the start point until the side ridgeline is formed. Although the cutting point is connected each other in order to acquire the tool path, it is difficult to process both adjoining sides by one direction due to the tool structure and the target product shape. In addition , the collision may take place between the tool and the workpiece. In this situation, the tool starts from the start point of the tool path to process the left side surface, and ends at the corner where the ridgeline is to be formed. Thus is repeated until it reaches to the bottom surface. The depth of cut is based in the division number of the total length of curve for curve surface. The same thing is done on the right side surface since there is still an arc-like remain at the corner part of the side surface. The procedure is almost the same as with the processing of the left side surface, however the cutting end point is the same with the end point of the left side processing, to form the clear ridgeline .Processing of the right side surfaces is 10also done using the left hand tool.The tool direction vector D during the tool path generation for side surfaces is rotated by 10degrees to make the vibration direction parallel to the feed direction vector F. The tool path is generated by connecting the cutting points in order from the starting point to the end point. The tool attitude during cutting is determined from the normal vector N and the tool feed direction vector F at the cutting point. The tool feed direction vector D and the tool axis vector T can be expressed as D=F*N and T=N respectively.3.2.2Generation of tool path for bottom surface11Figure 12 describes that tool path generating method for bottom surface that makes the bottom surface that makes the bottom ridgeline of the OHSC. After generating the tool path for side surfaces, the tool path for bottom ridgeline is successively generated, where the tool is inclined to the bottom surfaces. There are two methods of generating a tool path for bottom surfaces; one is one-path method shown on the upper left part, and the other multi-path method shown in the upper right part of the figure. In one –path method ,the cutting tip of the tool directly makes contact with the location of the bottom ridgeline. In this operation, the tool inclination angle is necessary to fully remove the arc-like remains on the bottom surface and to form a clear ridgeline. During the tool path generation, the tool axis vector T is inclined, based on the calculated inclination angle against the bottom surface and the clearance angle of the cutting tool, which is 6 degrees.The method of determining the cutting start point as well as the cutting end point is the same as that of generating a tool path for side ridgeline.In multi-path method, the pitch from the bottom surface is expressed by use of parameters u and v. The generation range of a cutting reference line is determined from the shortest distance between the arc-like remains after rouging and the reference line of the bottom ridgeline. Cutting points is generated on the basis of 12parameter v in each reference line. The systems determines the tool attitude during cutting from the tool axis vector N at the bottom surface and the tool feed vector F at cutting point along a cutting reference line. The tool axis vector T and the tool direction vector D can be express as T=N and D=N*F respectively. The cutting start point is assumed near the arc-like radius remains and it ends at the last point of the generated cutting point in the reference line. Moving the tool along each neighboring cutting point can make the tool path.4. Experimental ResultsEffect on cutting forceThe cutting force was measured by use of piezoelectric dynamometer (9267B,Kistler Co,Ltd), thus averaging the measured cutting force and processing it in the root mean square(rms) manner. table1 measured cutting forceMachining was conducted both with USV and without USV. The cutting conditions used are as follows: feed speed of 400mm/min and different depth of cut of 0.1,0.2,and 0.3mm respectively. The vibration conditions are in the following; frequency of 19kHz, amplitude of 36 and rolling angle of 10 degrees. The acquired m?result is shown in Table1. It can be seen that the cutting force in cutting with USV is much smaller as compared to cutting without USV. Since the cutting force was greatly reduced, the stiffness of the tool can be maintained all throughout the process.Machining of OHSCThe cutting experiment was also made in order to scrutinize the validity of the new machining method. The workpiece size used for the experiment is 100×100×20 mm and the material is an aluminimu alloy(JIS A6062), which is also commonly used for low cost mould with low molding pressurre such as blow moulding, vacuum forming, rubber moulding,etc. Two types of OHSC model were tired in the experiment, one is OHSC with plane surface and the other is OHSC with curve surface. The side surfaces consist of different inclination angle. The inclination angle o the surface at the cutting start point is not the same as the 13inclination angle at the cutting end point. In this condition, the inclination angle is not uniform all thoughout.Shown in Fig.13(a) is the machining model for OHSC with plane surfaces, rugh cutting must be at firdt done in order to perform an effcient cutting by 6-axis control machining, using the rotational ball end mill with a radius of 3mm and 1.6mm respectively. Machining is carried out until the target product shape is almost obtained. Since the target sharp corner is not clearly obtained due to the arc-like remains, as shown in Fig .13(b), finishing will be performed, using the 6-axis control cutting with the application of theUSV. with plane surface. In this process ,the left side or right side surface is firstly machined, depending on the choice.14Let us assume that the left side surface is machined. The cutting and vibration conditions listed in Table 2 were used in machining on the basis of NC instructions generated by the developed CAM program. After machining the side surface, the bottom surfaces is machined in the next step, using the one path method. The cutting conditions listed in Table 2 were also used except for the inclinations angle of 9 degrees and the depth of cut of about 1.6mm. The depths of cut were based on the arc-like remains of the ball end mill used during roughing.Machining of the left side surfaces is done, using the right hang tool.After finishing the machining of the left side surface, the right side is processed in the next step under almost the same conditions as the processing of the left side except that the tool used is a left hand too. Shown in Fig.13(d) is the result of machining experiment.The machining model for OHSC with curve surfaces is shown in Fig.14(a). In machining OHSC with curve surface, roughing must also be performed, as shown in Fig.14(b). The sequence of operation from roughing to finishing is almost the same as described previously. However, so-called linearization operation is required to make the product surface smooth. To process the bottom surface that makes the ridgeline, the multi-path method was emplyed since the method is suitable in curved surfaces. Table 2 lists the cutting and vibration conditions used in the process. Also, shown in Fig.14(c) and Fig.14(d) are the actual machining and the product after finishing process respectively. The total machining time with this experiment is 112 minutes including rough cutting time. Only one machine was used as well as one steup of the workpiece in the entire process.The cutting effciency has been drastically improved due to the increase of cutting speed by applying of ultrasonic vibration since the normal cutting speed of non rotational cutting tools is equal to the feed rate.15ConclusionThe experimental results show that the usage of bore byte tool is maximized and that the tool stiffness is enough to carry out machining due to the significant reduction of cutting force by applying the ultrasonic vibrations. It is found that only one machine can cope with machining of the product from roughing to fingshing , which leads to the potential of cost saving since the extra process like set-up from one machine to another can be eliminated. As a result, the validity of the developed CAM to machine OHSCs with plane and curve surface is experimentally confirmed throughout the study.references(1)Cecil, J A Clamping Design Approach for Automated Fixture Design, The International Journal of Advanced Manufacturing Technology, Vol.18, No.11(2001),pp.790-793.(2)Moriwaki, T, Shanmoto ,E. and Inoue, K,Ultrapresicion Ductile Cutting of Glass by Applying Ultrasonic Vibration, Annals of the CIRP,Vol.41, No.1(1992),pp.141-144.(3)Takeyama, H. and Iijima, N, Machinability of Glassfiber Reinforced Plastics and Application of Ultrasonic Machining, Annals of the CIRP, Vol.37, No.1(1998), pp.93-96.16(4)Shamoto, E. and Moriwaki, T, Study on Elliptical Vibration Cutting, Annals of the CIRP, Vol.43,No.1(1994),pp.36-38.(5)Moriwaki ,T. and Shamoto, E,Ultrasonic Elliptical Vibration Cutting ,Annals of the CIRP, Vol.44,No.1 (1996),pp.31-34.(6)Takeuchi, Y. and Suzuki, H. Efficient and Accurate Manufacturing by means of Multi-Axis Control Machine Tools, Proceedings of the Japan-USA Symposium on Flexible Automation, ASME and ISCIEJ, Boston, Massachusetts, July 7-10,1996,Vol.1,pp.343-347.(7)Radzevich, S.P. and Goodman, E .D, Efficiency of Multi-Axis NC Machining of Sculptured Surface, Proceedings of the International Conference on Sculptured Surface