變速箱殼體銑面夾具設(shè)計(jì)【說明書+CAD+PROE】

變速箱殼體銑面夾具設(shè)計(jì)【說明書+CAD+PROE】,說明書+CAD+PROE,變速箱殼體銑面夾具設(shè)計(jì)【說明書+CAD+PROE】,變速箱,殼體,夾具,設(shè)計(jì),說明書,仿單,cad,proe 各位老師大家下午好！題目：變速箱殼體銑面夾具設(shè)計(jì)-江西農(nóng)業(yè)大學(xué)2009屆畢業(yè)設(shè)計(jì) 學(xué) 院：工 學(xué) 院 姓 名：陳 亮 學(xué) 號(hào)：20050416 專 業(yè)：機(jī)械設(shè)計(jì)制造及其自動(dòng)化 年 級(jí)：機(jī)制052班 指導(dǎo)教師：樊十全 一.設(shè)計(jì)任務(wù)本次設(shè)計(jì)為設(shè)計(jì)一變速箱殼體銑面手動(dòng)專用夾具，殼體是鑄件，毛坯材料為QT-450-10。要求年生產(chǎn)能力為5000件，為中批量生產(chǎn)。具體如下圖（1）：圖（1）二.銑床夾具的特點(diǎn)銑削加工的切削用量和切削力一般較大，切削力的大小和方向也是變化的，而且又是斷續(xù)切削，因而加工時(shí)沖擊和振動(dòng)較嚴(yán)重。所以對(duì)于此次所設(shè)計(jì)的夾具，要特別注意工件定位穩(wěn)定性和夾緊可靠性；夾緊裝置要能產(chǎn)生足夠的夾緊力，手動(dòng)夾緊時(shí)要有良好的自鎖能力；夾具上各組成元件的強(qiáng)度和剛度要高。另外，由于銑削的切屑較多，夾具上應(yīng)有足夠的排屑空間，應(yīng)盡量避免切屑堆積在定位支承面上。因此，定位支承面應(yīng)高出周圍的平面（可參考底板圖紙），而且在夾具體內(nèi)盡可能做出便于清除切屑和排出冷卻液的出口。三對(duì)加工工件進(jìn)行工藝分析在銑削端面前，變速箱殼體的上下表面與兩定位孔都已加工好。對(duì)于上下表面其加工精度要求保證平面度為0.28，粗糙度為6.3，兩表面間距離為165.15mm；對(duì)于兩定位孔則是先鉆，再通過鉸刀精鉸至10.20mm.在加工側(cè)端面時(shí)，側(cè)端面尺寸要求為，表面粗糙度為3.2，分析可知由銑削直接加工就可達(dá)到要求。四定位方案設(shè)計(jì)4.1工件與夾具體的定位工件與夾具體的定位是間接通過定位塊來實(shí)現(xiàn)的。定位塊通過自己本身及定位插銷12、四個(gè)內(nèi)六角圓柱頭螺釘16、襯套11實(shí)現(xiàn)與底板的定位。而對(duì)于工件與定位塊的定位，為限制工件沿Z軸的移動(dòng)自由度、工件繞X軸的轉(zhuǎn)動(dòng)自由度及工件繞Y軸的轉(zhuǎn)動(dòng)自由度，我們需用工件的下表面作為第一定位基準(zhǔn)；為限制工件沿X軸方向的移動(dòng)自由度、沿Y軸方向的移動(dòng)自由度，需將工件上內(nèi)孔1作為第二定位基準(zhǔn)；同時(shí)為限制工件繞Z軸的轉(zhuǎn)動(dòng)自由度，需將工件上內(nèi)孔2作為第三定位基準(zhǔn)，這樣就限制了工件的六個(gè)不定度，達(dá)到完全定位，而這種定位方式也就是我們常說的“一面兩孔”定位。4.2夾具體與機(jī)床的定位夾具體與機(jī)床的定位是通過兩個(gè)定向鍵9、內(nèi)六角圓柱頭螺釘10，以及T型螺桿與壓板將夾具體固定在機(jī)床導(dǎo)軌上，實(shí)現(xiàn)定位。具體情況如下圖（2）：圖（2）4.3定位誤差計(jì)算在機(jī)械加工中，產(chǎn)生加工誤差的因素很多，而其中與夾具相關(guān)的誤差有夾具相對(duì)于機(jī)床成形運(yùn)動(dòng)的位置誤差，夾具相對(duì)于刀具位置的誤差，工件在夾具中的定位誤差，工件在夾具中被夾緊時(shí)產(chǎn)生的夾緊誤差，夾具磨損所造成的加工誤差等，而我們此處的話，只對(duì)工件在夾具中的定位誤差做一簡單計(jì)算。對(duì)于一面兩孔的定位，如下圖（3）：圖（3）可查機(jī)床夾具設(shè)計(jì)手冊(cè)表1112得：基準(zhǔn)位置誤差：式中：為第一定位孔的公差，為圓柱銷的公差；為第二定位孔的公差，為菱形銷的公差；第一定位孔與圓柱銷間的最小間隙；第二定位孔與菱形銷間的最小間隙；為轉(zhuǎn)角誤差?；鶞?zhǔn)不重合誤差：又因圓柱銷尺寸為，菱形銷尺為，圓柱銷與定位孔1的配合為，菱形銷與定位孔2間的配合為。由此可得由此可知，此定位方式能夠滿足加工要求。五夾緊方案設(shè)計(jì)此次設(shè)計(jì)，我們用螺旋夾緊機(jī)構(gòu)對(duì)工件進(jìn)行夾緊，螺旋夾緊機(jī)構(gòu)的結(jié)構(gòu)是由底板1、六角螺母2、可調(diào)支柱3、雙頭螺桿4、壓縮彈簧5、平墊圈6、移動(dòng)壓板7、平底螺母8、定向鍵9、螺釘10構(gòu)成。在對(duì)工件進(jìn)行夾緊前，可先將可調(diào)支柱、六角螺母、雙頭螺桿、平底螺母擰松，待工件裝上之后，通過壓板壓住工件，再分別擰緊可調(diào)支柱、六角螺母、雙頭螺桿、平底螺母，再加上定位塊、圓柱銷、菱形銷、襯套的定位，實(shí)現(xiàn)對(duì)工件的夾緊與松開。根據(jù)工件尺寸，對(duì)壓板的尺寸可初步擬定為厚度為25mm，長155mm，再據(jù)工件尺寸、壓板尺寸、雙頭螺桿尺寸大小，可選M20X2.5的平底螺母作為壓緊螺母。夾緊方案的確定如右圖（4）所示（局部圖）：圖（4）5.1銑削力的計(jì)算對(duì)于此零件，我們可用萬能銑床X62W對(duì)其進(jìn)行加工，所選銑刀為鑲齒套式面銑刀，刀具材料為高速鋼W18Cr4V.因工件材料為QT450-10,硬度為HBS185.則可查機(jī)床夾具設(shè)計(jì)手冊(cè)表129得：計(jì)算公式為：其中P-銑削力（N）；-在調(diào)整高速鋼銑刀銑削時(shí)，考慮工件材料及銑刀類型系數(shù)，其值查表1210選取,此處為=294；t-銑削深度(mm);-每齒進(jìn)給量（mm/齒）;D-為銑刀直徑（mm）;B-銑削寬度（mm）;z-為銑刀齒數(shù);-為用高速鋼銑削時(shí)，考慮工件材料機(jī)械性能不同的修正系數(shù)，對(duì)于QT450-10有.查金屬切削手冊(cè)表912可得Sz=0.3，查表97可得D125mm,Z=14,又因工件的銑削深度為2.5mm,銑削寬度為110mm.所以5.2夾緊力的計(jì)算查機(jī)械夾具設(shè)計(jì)手冊(cè)表1211可得夾緊力計(jì)算公式：其中K-安全系數(shù);P-切削力（N）;-為夾緊元件與工件間的摩擦系數(shù);L、H、l-工件受力大概尺寸，其中L=82.575mm，H165.15mm，l=52.5mm,具體如右圖（5）：圖（5）又因安全系數(shù)其中-考慮工件材料及加工余量均勻的基本安全系數(shù);-加工性質(zhì)系數(shù);-刀具鈍化程度系數(shù);-切削特點(diǎn)系數(shù);-夾緊力的穩(wěn)定性系數(shù);-手動(dòng)夾緊時(shí)的手柄位置系數(shù);-僅有力矩使工件與支承面接觸的情況系數(shù)。查機(jī)械夾具設(shè)計(jì)手冊(cè)表121和表122和表1212得:則代入夾緊力計(jì)算公式代入夾緊力計(jì)算公式因螺旋夾緊機(jī)構(gòu)是通過平底螺母來實(shí)現(xiàn)夾緊，若手柄長度為240mm，作用力為100N,則可查機(jī)械夾具設(shè)計(jì)手冊(cè)表1225得螺母夾緊力N。所以有，故此夾緊裝置能滿足加工所需的夾緊力，能保證工件的加工精度，是可行的。六夾具體設(shè)計(jì)與其它裝置設(shè)計(jì)6.1夾具體設(shè)計(jì)夾具體是夾具的基礎(chǔ)件。在夾具體上，要安裝組成該夾具所需要的各種元件、機(jī)構(gòu)和裝置等。設(shè)計(jì)時(shí)應(yīng)滿足以下基本要求：1、應(yīng)有足夠的強(qiáng)度和剛度；2、結(jié)構(gòu)簡單，具有良好的工藝性；3、尺寸要穩(wěn)定；4、便于排屑?；诖?，選夾具的結(jié)構(gòu)為鑄造結(jié)構(gòu)，材料為45鋼，根據(jù)工件、定位元件、夾緊裝置、對(duì)刀引導(dǎo)元件以及其他輔助機(jī)構(gòu)和裝置在總體上的配置，夾具體的外形尺寸大致可確定為長430mm，寬200mm,厚23mm,如下圖（6）所示：（具體見夾具體零件圖）圖（6）6.2其它裝置設(shè)計(jì)銑床夾具依靠夾具體底面和定向鍵側(cè)面與機(jī)床工作臺(tái)上平面及T型槽相連接，以保證定位元件對(duì)工作臺(tái)和導(dǎo)軌具有正確的相對(duì)位置。為了減小安裝時(shí)的偏斜角的誤差，安裝定向鍵時(shí)應(yīng)當(dāng)使它們靠向T型槽的同一側(cè)。對(duì)定向鍵的設(shè)計(jì)方案如下圖（7）所示（局部圖）：圖（7）七技術(shù)條件制定1.圓柱銷中心和菱形銷中心到D面的距離之差為105.01。2.菱形銷相對(duì)于夾具體表面的垂直度要求為。3.夾具體側(cè)面與基準(zhǔn)面A的垂直度要求0.02，與基準(zhǔn)C與基準(zhǔn)D的公共連線的平行度要求為0.025。八夾具精度分析夾具誤差必須滿足如下公式：其中dw是定位誤差：dw=0.032;jw是基準(zhǔn)位置誤差：jw=0.004;jd是銑床夾具的對(duì)刀誤差：jd=ShS塞尺的制造誤差；h對(duì)刀塊工作表面至定位元件的尺寸公差。查表可知：S=0.014。因?yàn)閷?duì)刀塊是用就地加工法加工的，所以可以認(rèn)為：h=0。由此我們可知：jd=0.014。得=0.0350.035由此判定，夾具精度符合要求。九.夾具工作原理簡介下面我們來分析與說明它的工件原理:工件通過菱形銷、圓柱銷固定在定位塊上，而定位塊又通過定位插銷和內(nèi)六角圓柱頭螺釘與夾具體相聯(lián)，對(duì)于螺旋夾緊機(jī)構(gòu)是通過六角螺母固定在夾具體上。在夾具體的底平面上安裝定向鍵用于與銑床工件臺(tái)面的連接與定位。裝工件時(shí)，只要把平底螺母松開一點(diǎn)，并將移動(dòng)壓板向左移動(dòng)一點(diǎn)即可把工件放上去，擰緊即可，開始對(duì)工件的進(jìn)行銑面加工。卸載工件時(shí)，松開平底螺母，移動(dòng)壓板左移，即可卸載。本夾具操作簡單，省時(shí)省力，裝卸工件時(shí)只需靠平底螺母的松緊和移動(dòng)壓板的移動(dòng)即可輕松實(shí)現(xiàn)。對(duì)此夾具各個(gè)零件的裝配關(guān)系見下圖（8）：十.總結(jié)此次畢業(yè)設(shè)計(jì)是我們從大學(xué)理論學(xué)習(xí)走向?qū)嶋H工作應(yīng)用的重要一步。從最初的選題，開題到計(jì)算、繪圖直到完成設(shè)計(jì)。其間，查找資料，向老師請(qǐng)教，與同學(xué)交流，反復(fù)修改圖紙，每一個(gè)過程都是對(duì)自己能力的一次檢驗(yàn)和充實(shí)。在設(shè)計(jì)過程中,我對(duì)專業(yè)基礎(chǔ)知識(shí)有了一次系統(tǒng)的復(fù)習(xí)和鞏固，同時(shí)也學(xué)會(huì)了查找相關(guān)資料與標(biāo)準(zhǔn)，學(xué)會(huì)了分析數(shù)據(jù)，提高了自己的CADPRO-E的制圖能力，也能更熟練的運(yùn)用OFFICE辦公軟件，懂得了許多經(jīng)驗(yàn)公式的獲得是前人不懈努力的結(jié)果。但是畢業(yè)設(shè)計(jì)也暴露出自己專業(yè)基礎(chǔ)的很多不足之處，比如缺乏綜合應(yīng)用專業(yè)知識(shí)的能力，設(shè)計(jì)分析不全面,運(yùn)用各種工具不熟，等等，當(dāng)然這的話還在自己在以后的工作學(xué)習(xí)中不斷完善。致謝此次畢業(yè)設(shè)計(jì)可以圓滿地完成，我要感謝我的指導(dǎo)老師樊十全,感謝他在整個(gè)設(shè)計(jì)過程中給予我的指導(dǎo)和幫助,也要感謝吳彥紅老師中途對(duì)我CAD圖的指正，以及我周圍的同學(xué)朋友，感謝他們提出寶貴的意見和建議。另外，我還要感謝在大學(xué)期間所有傳授我知識(shí)的老師，是你們的悉心教導(dǎo)使我有了良好的專業(yè)基礎(chǔ)知識(shí)，這也是畢業(yè)設(shè)計(jì)得以完成的基礎(chǔ)。雖然大學(xué)即將結(jié)束,但學(xué)習(xí)是人一生的事,在以后的工作中,我一定努力學(xué)習(xí),不辜負(fù)老師同學(xué)對(duì)我的期待,也為社會(huì)做出自己的一份貢獻(xiàn)。江西農(nóng)業(yè)大學(xué)畢業(yè)設(shè)計(jì)(論文)任務(wù)書 設(shè)計(jì)（論文） 課題名稱 變速箱殼體銑面夾具設(shè)計(jì) 學(xué)生姓名 陳亮 院（系） 工學(xué)院 專 業(yè) 機(jī)制 指導(dǎo)教師 樊十全 職 稱 副教授 學(xué) 歷 本科 畢業(yè)設(shè)計(jì)（論文）要求： 1.設(shè)計(jì)態(tài)度端正，思路清晰，技術(shù)路線科學(xué)合理； 2.夾具應(yīng)能保證工件的加工精度要求； 3.夾具結(jié)構(gòu)應(yīng)力求簡單、合理，便于制造、裝配、調(diào)整、檢驗(yàn)、維修等； 4夾具應(yīng)操作簡便、省力、安全可靠； 5.夾具設(shè)計(jì)圖紙量應(yīng)達(dá)到A01.5張以上。 6.編制設(shè)計(jì)說明書1份。（5000字左右） 畢業(yè)設(shè)計(jì)（論文）內(nèi)容與技術(shù)參數(shù)： 1.設(shè)計(jì)及繪制夾具裝配圖； 2.設(shè)計(jì)及繪制夾具零件圖； 3.編制設(shè)計(jì)說明書1份； 4.繪制加工件的零件圖或工序圖。 畢業(yè)設(shè)計(jì)（論文）工作計(jì)劃： 1.（2008年11月）下達(dá)任務(wù)； 2.（2008年12月）詳細(xì)閱讀加工件零件圖、了解產(chǎn)品生產(chǎn)工藝過程；（現(xiàn)場參觀） 3.（2009年3月） 收集設(shè)計(jì)資料、擬定夾具的結(jié)構(gòu)方案； 4.（2009年3月）設(shè)計(jì)及繪制夾具裝配圖、夾具零件圖、按規(guī)定格式和要求編制設(shè)計(jì)說明書； 5.（5月上旬）打印圖紙、制作答辯演示文件、準(zhǔn)備畢業(yè)答辯。 接受任務(wù)日期 2008 年 11 月10 日 要求完成日期 2009年 4 月 30 日 學(xué) 生 簽 名 年 月 日 指導(dǎo)教師簽名 年 月 日 院長（主任）簽名 年 月 日 變速箱殼體銑面夾具設(shè)計(jì) 學(xué)校代碼： 10410 學(xué) 號(hào): 20050416 本 科 畢 業(yè) 設(shè) 計(jì) 題目： 變速箱殼體銑面夾具設(shè)計(jì) 學(xué) 院： 工 學(xué) 院 姓 名： 陳亮 學(xué) 號(hào)： 20050416 專 業(yè)： 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 年 級(jí)： 機(jī)制052班 指導(dǎo)教師： 樊十全 二OO九年 五 月 摘 要 為對(duì)變速箱殼體端面銑削加工，我們進(jìn)行此次專用夾具設(shè)計(jì)。變速箱零件為鑄件，零件形狀復(fù)雜，在定位時(shí)，選一面兩銷的定位方式定位，并以操作簡單的手動(dòng)夾緊方式夾緊，其機(jī)構(gòu)設(shè)計(jì)簡單，方便且能滿足要求。 關(guān)鍵詞：變速箱殼體，銑面加工，專用夾具，設(shè)計(jì) Design of Clamping Device for The Gearbox Shell Face Milling Abstract: This design is about the shell of the gearbox face milling clamp design.The parts is casting ,and it have complex shape.When processesing,we need take it in right position,so we chooses locate mode which two sells at the same time, and operates the simple manual clamp way clamp, its organization design is simple, the convenience also can satisfy the request. e35BQK ? Key words:Shell of The Gearbox,Milling Face, Unit Clamp,Design of Clamping Device. 目 錄 一.前言 - 1 - 二．設(shè)計(jì)任務(wù) - 2 - 三．銑床夾具的主要類型與特點(diǎn) - 3 - 3.1 銑床夾具的主要類型 - 3 - 3.2 銑床夾具的特點(diǎn) - 3 - 四．對(duì)加工工件進(jìn)行工藝分析 - 3 - 五．定位方案設(shè)計(jì) - 3 - 5.1 工件與夾具體的定位 - 3 - 5.2 夾具體與機(jī)床的定位 - 4 - 5.3 定位誤差計(jì)算 - 4 - 六．夾緊方案設(shè)計(jì) - 6 - 6.1銑削力的計(jì)算 - 7 - 6.2 夾緊力的計(jì)算 - 8 - 七．夾具體與其它裝置設(shè)計(jì) - 10 - 7.1 夾具體設(shè)計(jì) - 10 - 7.2 其它裝置設(shè)計(jì) - 11 - 八．技術(shù)條件制定 - 12 - 九．夾具精度分析 - 12 - 十.夾具工作原理簡介 - 13 - 十一.總結(jié) - 14 - 參 考 文 獻(xiàn) - 15 - 致 謝 - 16 - 一.前言 夾具最早出現(xiàn)在18世紀(jì)后期，隨著科學(xué)技術(shù)的不斷進(jìn)步，夾具已從一種輔助工具發(fā)展成為門類齊全的工藝裝備。 在機(jī)床上對(duì)工件進(jìn)行加工時(shí),為了保證加工表面相對(duì)其它表面的尺寸和位置精度,首先需要使工件在機(jī)床上占有準(zhǔn)確的位置,并在加工過程中能承受各種力的作用而始終保持這一準(zhǔn)確位置不變。前者稱為工件的定位,后者稱為工件的夾緊,這一整個(gè)過程統(tǒng)稱為工件的裝夾。在機(jī)床上裝夾工件所使用的工藝裝備稱為機(jī)床夾具。而機(jī)床夾具按專業(yè)化程度可分為通用夾具、專用夾具、組合夾具、成組夾具。它在保證產(chǎn)品優(yōu)質(zhì)、高產(chǎn)、低成本，充分發(fā)揮現(xiàn)有設(shè)備的潛力，以便工人掌握復(fù)雜或精密零件加工技術(shù)，以減輕繁重的體力勞動(dòng)等諸方面起著巨大的作用。因此，機(jī)床夾具的設(shè)計(jì)和使用是促進(jìn)生產(chǎn)迅速發(fā)展的重要工藝措施之一。 夾具通常由定位元件（確定工件在夾具中的正確位置）、夾緊裝置 、對(duì)刀引導(dǎo)元件(確定刀具與工件的相對(duì)位置或?qū)б毒叻较?、分度裝置（使工件在一次安裝中能完成數(shù)個(gè)工位的加工，有回轉(zhuǎn)分度裝置和直線移動(dòng)分度裝置兩類）、連接元件以及夾具體（夾具底座）等組成。 對(duì)于此次要加工的變速箱，由于傳統(tǒng)銑削變速箱殼體端面所使用的夾具復(fù)雜、生產(chǎn)效率低、工人工作強(qiáng)度大、夾具通用性低等特點(diǎn)，故需設(shè)計(jì)一種能滿足現(xiàn)代化生產(chǎn)的專用夾具。 當(dāng)然，由于自己知識(shí)的缺陷，設(shè)計(jì)時(shí)考慮的不夠周全，存在一些錯(cuò)誤，還請(qǐng)各位老師和同學(xué)指正，我將做到虛心接受，努力提高自己。 二．設(shè)計(jì)任務(wù) 設(shè)計(jì)題目：變速箱殼體銑面夾具設(shè)計(jì) 姓 名 陳亮 班 級(jí) 機(jī)制052 學(xué)號(hào) 20050416 設(shè)計(jì)題目 變速箱殼體銑面夾具設(shè)計(jì) 指導(dǎo)老師 樊十全 零件名稱 變速箱殼體 材料 QT450-10 生產(chǎn)類型 中批量生產(chǎn) 毛坯 鑄件 生產(chǎn)綱領(lǐng) 年生產(chǎn)量 5000 件 設(shè)計(jì)任務(wù) 零件簡圖如下圖2-1，本工序銑削加工變速箱殼體側(cè)端面，設(shè)計(jì)銑床手動(dòng)專用夾具。 圖2-1 三．銑床夾具的主要類型與特點(diǎn) 3.1 銑床夾具的主要類型 銑床夾具主要用于加工零件上的平面、凹槽、鍵槽、缺口、花鍵、齒輪及各種成形面等。由于銑削加工通常是夾具隨工作臺(tái)一起作進(jìn)給運(yùn)動(dòng)，有時(shí)也作圓周進(jìn)給運(yùn)動(dòng)，因此銑床夾具的結(jié)構(gòu)，按進(jìn)給方式不同銑床夾具可分為直線進(jìn)給式、圓周進(jìn)給式和靠模進(jìn)給式三種類型。 3.2 銑床夾具的特點(diǎn) 銑削加工的切削用量和切削力一般較大，切削力的大小和方向也是變化的，而且又是斷續(xù)切削，因而加工時(shí)沖擊和振動(dòng)較嚴(yán)重。所以對(duì)于此次所設(shè)計(jì)的夾具，要特別注意工件定位穩(wěn)定性和夾緊可靠性；夾緊裝置要能產(chǎn)生足夠的夾緊力，手動(dòng)夾緊時(shí)要有良好的自鎖能力；夾具上各組成元件的強(qiáng)度和剛度要高。 另外，由于銑削的切屑較多，夾具上應(yīng)有足夠的排屑空間，應(yīng)盡量避免切屑堆積在定位支承面上。因此，定位支承面應(yīng)高出周圍的平面（可參考底板圖紙），而且在夾具體內(nèi)盡可能做出便于清除切屑和排出冷卻液的出口。 四．對(duì)加工工件進(jìn)行工藝分析 在銑削端面前，變速箱殼體的上下表面與兩定位孔都已加工好。對(duì)于上下表面其加工精度要求保證平面度為0.28，粗糙度為6.3，兩表面間距離為165.15mm；對(duì)于兩定位孔則是先鉆，再通過鉸刀精鉸至10 mm. 在加工側(cè)端面時(shí)，側(cè)端面尺寸要求為，表面粗糙度為3.2，分析可知由銑削直接加工就可達(dá)到要求。 五．定位方案設(shè)計(jì) 5.1 工件與夾具體的定位 工件與夾具體的定位是間接通過定位塊來實(shí)現(xiàn)的。定位塊通過自己本身及定位插銷12、四個(gè)內(nèi)六角圓柱頭螺釘16、襯套11實(shí)現(xiàn)與底板的定位。而對(duì)于工件與定位塊的定位，為限制工件沿Z軸的移動(dòng)自由度、工件繞X軸的轉(zhuǎn)動(dòng)自由度及工件繞Y軸的轉(zhuǎn)動(dòng)自由度，我們需用工件的下表面作為第一定位基準(zhǔn)；為限制工件沿X軸方向的移動(dòng)自由度、沿Y軸方向的移動(dòng)自由度，需將工件上內(nèi)孔1作為第二定位基準(zhǔn)；同時(shí)為限制工件繞Z軸的轉(zhuǎn)動(dòng)自由度，需將工件上內(nèi)孔2作為第三定位基準(zhǔn)，這樣就限制了工件的六個(gè)不定度，達(dá)到完全定位，而這種定位方式也就是我們常說的“一面兩孔” 定位。 5.2 夾具體與機(jī)床的定位 夾具體與機(jī)床的定位是通過兩個(gè)定向鍵9、內(nèi)六角圓柱頭螺釘10，以及T型螺釘與壓板將夾具體固定在機(jī)床導(dǎo)軌上，實(shí)現(xiàn)定位。 定位方案示意具體情況如下圖5-1： 圖5-1 5.3 定位誤差計(jì)算 在機(jī)械加工中，產(chǎn)生加工誤差的因素很多，而其中與夾具相關(guān)的誤差有夾具相對(duì)于機(jī)床成形運(yùn)動(dòng)的位置誤差，夾具相對(duì)于刀具位置的誤差，工件在夾具中的定位誤差，工件在夾具中被夾緊時(shí)產(chǎn)生的夾緊誤差，夾具磨損所造成的加工誤差等，而我們此處的話，只對(duì)工件在夾具中的定位誤差做一簡單計(jì)算。 定位誤差由基準(zhǔn)位置誤差和基準(zhǔn)不重合誤差組成?；诖?，對(duì)于一面兩孔的定位，如下圖5-2： 圖5-2 可查《機(jī)床夾具設(shè)計(jì)手冊(cè)》表1－1－12得： 基準(zhǔn)位置誤差 （5.1） （5.2） 式中：為第一定位孔的公差，為圓柱銷的公差； 為第二定位孔的公差，為菱形銷的公差； ——第一定位孔與圓柱銷間的最小間隙； ——第二定位孔與菱形銷間的最小間隙； ——為轉(zhuǎn)角誤差。 又因圓柱銷尺寸為，菱形銷尺寸為，圓柱銷與定位孔1的配合為， 菱形銷與定位孔2間的配合為，兩定位孔尺寸為。 由此可得 對(duì)于基準(zhǔn)不重合的誤差有： （5.3） 則定位誤差 （5.4） ＝ = 由此可知，此定位方式能夠滿足加工要求。 六．夾緊方案設(shè)計(jì) 由于螺旋夾緊機(jī)構(gòu)具有結(jié)構(gòu)簡單、制造容易、夾緊可靠、擴(kuò)力比大、夾緊行程不受限制等特點(diǎn)，所以在手動(dòng)夾緊裝置中被廣泛使用，而對(duì)于此次設(shè)計(jì)，即可用螺旋夾緊機(jī)構(gòu)對(duì)工件進(jìn)行夾緊，在這螺旋夾緊機(jī)構(gòu)的結(jié)構(gòu)是由底板1、六角螺母2、可調(diào)支柱3、雙頭螺桿4、壓縮彈簧5、平墊圈6、移動(dòng)壓板7、平底螺母8構(gòu)成。在對(duì)工件進(jìn)行夾緊前，可先將可調(diào)支柱、六角螺母、雙頭螺桿、平底螺母擰松，待工件裝上之后，通過壓板壓住工件，再分別擰緊可調(diào)支柱、六角螺母、雙頭螺桿、平底螺母，再加上定位塊、圓柱銷、菱形銷、襯套的定位，實(shí)現(xiàn)對(duì)工件的夾緊與松開。 根據(jù)工件尺寸，對(duì)移動(dòng)壓板的尺寸可初步擬定為厚度為25mm，長155mm，再據(jù)工件尺寸、壓板尺寸、雙頭螺桿尺寸大小，可選M20X2.5的平底螺母作為壓緊螺母。 夾緊方案的確定如下圖6-1所示（局部圖）： 圖6-1 6.1銑削力的計(jì)算 對(duì)于此零件，我們可用萬能銑床X62W對(duì)其進(jìn)行加工，所選銑刀為鑲齒套式面銑刀，刀具材料為高速鋼W18Cr4V. 因工件材料為QT450-10,硬度為185HBS.則可查《機(jī)床夾具設(shè)計(jì)手冊(cè)》表1－2－9得： 計(jì)算公式為： （6.1） 其中P---銑削力（N）； ---在調(diào)整高速鋼銑刀銑削時(shí)，考慮工件材料及銑刀類型系數(shù)，其值查表1－2－10選取, 此處為=294； t---銑削深度(mm)，指銑刀刀齒切入和切出工件過程中，接觸弧在垂直走刀方向平面中測得的投影長度; ---每齒進(jìn)給量（mm/齒）; D---為銑刀直徑（mm）; B---銑削寬度（mm），指平行于銑刀軸線方向測得的切削尺寸; z---為銑刀齒數(shù); ---為用高速鋼銑削時(shí)，考慮工件材料機(jī)械性能不同的修正系數(shù)，對(duì)于QT450-10：。 查《金屬切削手冊(cè)》表9－12可得，查表9－7可得D＝125mm,Z=14,又因工件的銑削深度為2.5mm,銑削寬度為110mm. 所以 6.2 夾緊力的計(jì)算 查《機(jī)械夾具設(shè)計(jì)手冊(cè)》表1－2－11可得 夾緊力計(jì)算公式 （6.2） 其中K---安全系數(shù); P---為切削力（N）; ---為夾緊元件與工件間的摩擦系數(shù); L、H、l---工件受力大概尺寸，其中L＝82.575mm，H＝165.15mm，l=52.5mm,具體如下圖6-2： 圖6-2 又因安全系數(shù) （6.3） 其中---考慮工件材料及加工余量均勻的基本安全系數(shù); ---加工性質(zhì)系數(shù); ---刀具鈍化程度系數(shù); ---切削特點(diǎn)系數(shù); ----夾緊力的穩(wěn)定性系數(shù); ----手動(dòng)夾緊時(shí)的手柄位置系數(shù); ----僅有力矩使工件與支承面接觸的情況系數(shù)。 查《機(jī)械夾具設(shè)計(jì)手冊(cè)》表1－2－1和表1－2－2和表1－2－12得: 。 則 代入夾緊力計(jì)算公式 因螺旋夾緊機(jī)構(gòu)是通過平底螺母來實(shí)現(xiàn)夾緊，若手柄長度為240mm，作用力為100N,則可查《機(jī)械夾具設(shè)計(jì)手冊(cè)》表1－2－25得螺母夾緊力N。 所以有<，故此夾緊裝置能滿足加工所需的夾緊力，能保證工件的加工精度，是可行的。 七．夾具體與其它裝置設(shè)計(jì) 7.1 夾具體設(shè)計(jì) 夾具體是夾具的基礎(chǔ)件。在夾具體上，要安裝組成該夾具所需要的各種元件、機(jī)構(gòu)和裝置等。設(shè)計(jì)時(shí)應(yīng)滿足以下基本要求： 1、應(yīng)有足夠的強(qiáng)度和剛度：保證在加工過程中，夾具體在夾緊力、切削力等的作用下，不致產(chǎn)生不允許的變形和振動(dòng)； 2、結(jié)構(gòu)簡單，具有良好的工藝性：在保證強(qiáng)度和剛度的條件下，力求結(jié)構(gòu)簡單，體積小，重量輕，特別是對(duì)于移動(dòng)或翻轉(zhuǎn)的夾具，其重量不應(yīng)太大（一般不超過10KG），以便于操作； 3、尺寸要穩(wěn)定：對(duì)于鑄造夾具體，要進(jìn)行時(shí)效處理，對(duì)于焊接夾具體，要進(jìn)行退火處理，以消除內(nèi)應(yīng)力，以保證夾具體加工尺寸的穩(wěn)定； 4、便于排屑：為防止加工中切屑積在定位元件工作表面或其他裝置中，而影響工件的正確定位和夾具的正常工作，在設(shè)計(jì)夾具體時(shí)，要考慮切屑的排除問題。 基于此，選夾具的結(jié)構(gòu)為鑄造結(jié)構(gòu)，材料為45鋼，夾具體進(jìn)行時(shí)效處理，根據(jù)工件、定位元件、夾緊裝置、對(duì)刀－引導(dǎo)元件以及其他輔助機(jī)構(gòu)和裝置在總體上的配置，夾具體的外形尺寸大致可確定為長430mm，寬200mm,厚23mm。 如下圖7-1所示：（具體見夾具體零件圖）： 圖7-1 7.2 其它裝置設(shè)計(jì) 銑床夾具依靠夾具體底面和定向鍵側(cè)面與機(jī)床工作臺(tái)上平面及T型槽相連接，以保證定位元件對(duì)工作臺(tái)和導(dǎo)軌具有正確的相對(duì)位置。為了減小安裝時(shí)的偏斜角的誤差，安裝定向鍵時(shí)應(yīng)當(dāng)使它們靠向T型槽的同一側(cè)。 對(duì)定向鍵的設(shè)計(jì)方案如下圖7-2所示（局部圖）： 圖7-2 對(duì)定向鍵的直角部分都倒1*45°的倒角，在夾具體與定向鍵的連接部分中的直角開出凹槽，如圖中的小凹槽。定向鍵與夾具體采用螺釘連接，對(duì)于定向鍵的大小，根據(jù)銑床工作臺(tái)最大行程700*260*320，我們可以確定向鍵的尺寸，具體見定向鍵零件圖。 八．技術(shù)條件制定 1.圓柱銷中心和菱形銷中心到D面的距離之差為116.01mm。 2. 菱形銷相對(duì)于夾具體表面的垂直度要求為。 3.夾具體側(cè)面與基準(zhǔn)面A的垂直度要求0.02，與基準(zhǔn)C與基準(zhǔn)D的公共連線的平行度要求為0.025。 九．夾具精度分析 夾具誤差必須滿足如下公式： （9.1） dw是定位誤差：dw=0.032; jw是基準(zhǔn)位置誤差：jw=0.004; jd是銑床夾具的對(duì)刀誤差： Δjd =δS＋δh （9.2） δS——塞尺的制造誤差；δh——對(duì)刀塊工作表面至定位元件的尺寸公差。查《機(jī)床夾具設(shè)計(jì)手冊(cè)》塞尺基本尺寸可知：δS=0.014。因?yàn)閷?duì)刀塊是用就地加工法加工的，所以可以認(rèn)為：δh=0。由此我們可知：jd=0.014 得 =0.035 0.035< 可知,夾具精度符合要求。 十.夾具工作原理簡介 下面我們來分析與說明它的工件原理:工件通過菱形銷、圓柱銷固定在定位塊上，而定位塊又通過定位插銷和內(nèi)六角圓柱頭螺釘與夾具體相聯(lián)，對(duì)于螺旋夾緊機(jī)構(gòu)是通過六角螺母固定在夾具體上。在夾具體的底平面上安裝定向鍵用于與銑床工件臺(tái)面的連接與定位。裝工件時(shí)，只要把平底螺母松開一點(diǎn)，并將移動(dòng)壓板向左移動(dòng)一點(diǎn)即可把工件放上去，擰緊即可，開始對(duì)工件的進(jìn)行銑面加工。卸載工件時(shí)，松開平底螺母，移動(dòng)壓板左移，即可卸載。操作簡單，省時(shí)省力，裝卸工件時(shí)只需靠平底螺母的松緊和移動(dòng)壓板的移動(dòng)即可輕松實(shí)現(xiàn)。通過上述分析得出 :本套夾具定位準(zhǔn)確可靠 ,拆卸工件方便 ,加工質(zhì)量穩(wěn)定 ,提高了生產(chǎn)效率 ,降低了生產(chǎn)成本 ,減輕了工人的勞動(dòng)強(qiáng)度 是可行的。 對(duì)此夾具各個(gè)零件的裝配關(guān)系見下圖10-1： 圖10-1 十一.總結(jié) 此次畢業(yè)設(shè)計(jì)是我們從大學(xué)理論學(xué)習(xí)走向?qū)嶋H工作應(yīng)用的重要一步。從最初的選題，開題到計(jì)算、繪圖直到完成設(shè)計(jì)。其間，查找資料，向老師請(qǐng)教，與同學(xué)交流，反復(fù)修改圖紙，每一個(gè)過程都是對(duì)自己能力的一次檢驗(yàn)和充實(shí)。 在設(shè)計(jì)過程中,我對(duì)專業(yè)基礎(chǔ)知識(shí)有了一次系統(tǒng)的復(fù)習(xí)和鞏固，同時(shí)也學(xué)會(huì)了查找相關(guān)資料與標(biāo)準(zhǔn)，學(xué)會(huì)了分析數(shù)據(jù)，提高了自己的CAD\PRO-E的制圖能力，也能更熟練的運(yùn)用OFFICE辦公軟件，懂得了許多經(jīng)驗(yàn)公式的獲得是前人不懈努力的結(jié)果。?但是畢業(yè)設(shè)計(jì)也暴露出自己專業(yè)基礎(chǔ)的很多不足之處，比如缺乏綜合應(yīng)用專業(yè)知識(shí)的能力，設(shè)計(jì)分析不全面,運(yùn)用各種工具不熟，等等，當(dāng)然這的話還在自己在以后的工作學(xué)習(xí)中不斷完善。 總之, 通過這次設(shè)計(jì)，我了解了變速箱殼體銑面的加工方法，熟悉了變速箱殼體銑面夾具的設(shè)計(jì)步驟，鍛煉了自己工程設(shè)計(jì)的實(shí)踐能力，也培養(yǎng)了自己獨(dú)立思考分析問題的意識(shí),相信這對(duì)于我以后的工作學(xué)習(xí)是有很大幫助。 參 考 文 獻(xiàn) [1] 王啟平主編. 機(jī)床夾具設(shè)計(jì)[M]. 哈爾濱工業(yè)大學(xué)出版社，2005 [2] 東北重機(jī),洛陽工學(xué)院，一汽職工大學(xué)編.機(jī)械夾具設(shè)計(jì)手冊(cè)[M].上海科學(xué)技術(shù)出版社，1990 [3] 陸劍中.孫家寧主編. 金屬切削原理與刀具[M]. 機(jī)械工業(yè)出版社，2005 [4] 刑閩芳主編. 互換性與技術(shù)測量[M]. 清華大學(xué)出版社.2000 [5] 王秀倫主編. 機(jī)床夾具設(shè)計(jì)[M]. 國防工業(yè)出版社. 1983 [6] 曾志新,呂明主編. 機(jī)械制造技術(shù)基礎(chǔ)[M]. 武漢理工大學(xué)出版社.2001 [7] 楊忠明，朱家誠主編.機(jī)械設(shè)計(jì)[M].武漢理工大學(xué)出版社.2001 [8] 吳宗澤主編.機(jī)械零件設(shè)計(jì)手冊(cè)[M].機(jī)械工業(yè)出版社.2003 [9] 徐圣群主編. 簡明機(jī)械加工工藝手冊(cè)[M]. 上?？茖W(xué)技術(shù)出版社.1991 [10] 于就泗，齊發(fā)主編.機(jī)械工程材料[M].大連理工大學(xué)出版社,2003 [11] 譚建榮主編.圖學(xué)基礎(chǔ)教程[M].高等教育出版社，1999 [12] 余桂英，郭紀(jì)林主編.Auto CAD 2006中文版實(shí)用教程[M].大連理工出版社.2006 [13] 戴曙主編.金屬切削機(jī)床[M].機(jī)械工業(yè)出版社.1993 [14] 上海柴油機(jī)廠工藝設(shè)備研究所編.金屬切削機(jī)床夾具設(shè)計(jì)手冊(cè)[M].機(jī)械工業(yè)出版社.1984 [15] 上海市金屬切削技術(shù)協(xié)會(huì)編. 金屬切削手冊(cè)[M]. 上海科學(xué)技術(shù)出版社，1984 [16] 中國機(jī)械社區(qū)：http://bbs.cmiw.cn/index.php. [17] 野火論壇：http://www.proewildfire.cn/index.php. [18] 燕春南.浮動(dòng)夾緊銑削夾具的設(shè)計(jì). 機(jī)床與液壓[J]，2008年 01期. [19] 李兆東.一種萬能銑夾具設(shè)計(jì).山東建筑工程學(xué)院學(xué)報(bào)[J]，2006年 03期. [20] 竇廣勇，胡延鳳.單向閥專用銑夾具的設(shè)計(jì).通用機(jī)械[J]，2004年 08期. 致 謝 此次畢業(yè)設(shè)計(jì)可以圓滿地完成，要感謝我的指導(dǎo)老師樊十全,感謝他在整個(gè)設(shè)計(jì)過程中給予我的指導(dǎo)和幫助,也要謝謝吳彥紅老師中途對(duì)我CAD圖的指正，以及我周圍的同學(xué)朋友，感謝他們提出寶貴的意見和建議。另外，我要感謝在大學(xué)期間所有傳授我知識(shí)的老師，是你們的悉心教導(dǎo)使我有了良好的專業(yè)基礎(chǔ)知識(shí)，這也是畢業(yè)設(shè)計(jì)得以完成的基礎(chǔ)。 ??雖然大學(xué)即將結(jié)束,但學(xué)習(xí)是人一生的事,在以后的工作中,我一定努力學(xué)習(xí),不辜負(fù)老師同學(xué)對(duì)我的期待,做出自己的一份事業(yè)，也為社會(huì)做出自己的一份貢獻(xiàn)。 - 17 - , J.M. Superior 2, Cranfield accepted 26 relies requirements, taking this as a general concept, is to make should be always linked to a requirement, and its purpose is International Journal of Machine Tools Fixture knowledge modelling, Fixture functional requirements 1. Introduction The main objective of any design theory is to provide a suitable framework and methodology for the definition of a sequence of activities that conform the design process of a product or system 1. In general, all of them identify requirements as the starting point in the design process. In fact, the engineering discipline dealing with product design can be defined as the one that considers scientific and engineering knowledge to create product definitions and design solutions based on ideas and concepts derived from requirements and constraints 24. For this research, a relevant issue when considering explicit the meaning of two main terms: Functional Requirement (FR) and Constraint (C). A functional requirement, as it stated by different authors, represents what the product has to or must do independently of any possible solution, 2,4. A FR is a kind of requirement, and considering some basic principles widely recognized in the field of Requirements Engineering, we could add it is a unique and unambiguous statement in natural language of a single functionality, written in a way that it can be ranked, traced, measured, verified, and validated. A constraint can be defined as a restriction that in general affects some kind of requirement, and it limits the range of possible solutions while satisfying the requirements. So, a constraint A functional approach for the formalization R. Hunter a , J. Rios b, * a Department of Mechanical and Manufacturing Engineering, Escuela Tecnica Jose Gutierrez Abascal, b Currently in Enterprise Integration (Bldg 53), Received 14 January 2005; Available online Abstract The design of machining fixtures is a highly complex process that of the fixture design process Perez a , A. Vizan a de Ingenieros Industriales, Universidad Politecnica de Madrid, 28006 Madrid, Spain University, Cranfield, MK43 0AL, UK 14 April 2005 August 2005 on designer experience and his/her implicit knowledge to achieve Manufacture 46 (2006) 683697 functional requirements should be defined in the functional domain, which brings on the scene the issue of how to define and represent the functionality of a product. The way used to represent it will affect the reasoning process of the designer, and in that sense, the mapping between the functional 0890-6955/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijmachtools.2005.04.018 * Corresponding author. Tel.: C44 1234 754936; fax.: C44 1234 750852. to narrow the design outcome to acceptable solutions. Considering the Theory of Axiomatic Design 4, ably, the first aspect to think about is how the requirements are represented or declared. As it has been previously and the physical domains, being the later the one where the design solutions are developed. Several authors have investigated the concept of functionality and functional representation 2,58. Their design approach provides a view based on the Function-Behaviour-Structure frame- work, where function is defined using structure and behaviour 6. The objective is to fill the gap that allows a designer to progress from FRs to physical design solutions. The approach is that product functions are achieved by means of its structure, which seems to lead to an iterative causal approach, where solutions are sought until the selected structure causes the intended functionality. The approach adopted in the research presented in this paper is based on the definition of Fixture Functional Components (FFC), which can satisfy the fixture functionality, and on the mapping between such FFC and fixture commercial elements. An advanced approach to the definition of requirements and functions comes from the creation of ontologies. The ontological approach pursues the definition of the meaning of terms making use of some kind of logic, and the definition of axioms to enable automatic deduction and reasoning 9. The ontological approach has got a higher relevance since the representation of knowledge is considered the key factor in whatever engineering process, and it has been recognized as a way to facilitate the integration of engineering applications 10, to describe functional design knowledge 7, and to define requirements 11. Considering a purist approach, if an ontology does not include axioms to enable reasoning then it could be considered more like an information model, and in this sense, this is the approach developed in the work presented in this paper. When considering the methodologies developed for the design of fixtures, it can be stated that in general they are rational and propose a series of steps to follow. For example, the methodologies proposed by Scallan and Henriksen 12, 13, make use of this approach to describe in general terms the information needed in each stage of the fixture design process. Basically, the importance of modelling in detail such information, which mainly is related to fixture requirements, fixture functionality, fixture components, manufacturing resources, manufacturing processes, and design rules; resides on the possibility to automate the design process through the development of a knowledge- based application or system. It is relevant to mention that several authors have already aimed to develop knowledge- based applications for fixture design, none of them based on a functional approach, some of the most recently published works can be found in the Refs. 1419. In the following sections, this paper presents a methodology to formalize the design process of machin- ing fixtures based on the engineering concepts of functional requirements and fixture functions 20. The formalization of the functional requirements is achieved through the application of a structured way of specifica- R. Hunter et al. / International Journal of Machine684 tion via natural language. Additionally, IDEF0, MOKA mentioned, the way of expressing requirements definitively affects their interpretation and the creation of a design solution. In this sense, it is widely accepted, that the use of natural language is the most common way of expressing requirements and in consequence, their writing becomes an important issue. The anatomy proposed by Alexander et al. 24 to write requirements in a semi-structured way is used as basis to declare the functional requirements and constraints of fixtures 20. In machining, work holding is a key aspect, and fixtures are the elements responsible to satisfy this general goal. In their design process, the starting point is the definition of the machining fixtures functional requirements and constraints. Usually, a fixture solution is made of one or several physical elements, as a whole the designed fixture solution must methodology, and UML diagrams are used to capture, represent and formalize knowledge, being the ultimate goal to facilitate the automation of the fixture design process. The IDEF0 method is used to create an activity model of the fixture design process, allowing the identification of the information used in each one of the different tasks it comprises. UML has been used to complement the IDEF0 model by representing the interaction between the activities of the process. The MOKA methodology together with UML, are used to capture and represent knowledge involved in the fixture design process. Finally, to validate the proposed methodology, partial results obtained from the development of a prototype knowledge-based application are presented. 2. Analysis of machining fixtures requirements In Section 1, two terms have been defined: functional requirement and constraint. Requirements have always existed, the way in which they are expressed, and how they are integrated in the product design process, are aspects that are addressed from different disciplines, for example: product design engineering and requirements engineering among others. In general, Requirements Engineering refers to the discipline dealing with the capture, formalization, representation, analysis, management and verification of requirements fulfilment. However, all these aspects need to be integrated in the product design process, and require- ments should lead to the definition of the possible product design solutions, which in general demands an integrated view of the requirements issue. It is important to keep in mind that the development of such discipline is strongly related to Software Engineering and Systems Engineering, and in fact much of the research related to requirements come from authors from these engineering areas 2123. When considering the analysis of requirements, prob- Tools in this case a KBE application for the design of machining fixtures; and the second one is the functional requirements of the components subject of the application; in this case machining fixtures. An example of the former ones for an application developed in collabor- ation with an industrial partner is presented by Rios et al. 28. For this kind of FRs specification, UML seems to be for fixture FRs. MOKA ICARE: ENTITY Name Reference Entity Type Function Constraints Functional Requirements for the Fixture Constraints Functional Requirements (CFR) Structure Define constrains to Functional Requirements for the fixture t support the fun e structur de of the fixtur Re 03-07-04 1.0 In progres form R. Hunter et al. / International Journal of Machine Tools it is independent of the knowledge representation to be used in the implementation, and it does not require from the fixture designer a deep knowledge of any software modelling technique. The definition of these fixture functions is a first step in the modelling needed for a KBE application development. For example, considering stability as one of the main constraints affecting the fixture FRs, any fixture functional solution should satisfy this constraint. To achieve that, it would be necessary to define a fixture function (FF) for stability methodology. Part machining: operations strategies cutting parameters cutting tool parameters volume to remove Optimization method Analysis model Constraints: Deformation Stability Interference Part orientation Part support: support points support vectors support surfaces Determine cut Determ Determine cl Determine cl Determ Determ R. Hunter et al. / International Journal of Machine Tools & Manufacture 46 (2006) 683697 689 Part location: locating points locating vectors locating surfaces Part information: mechanical properties friction coefficient raw material shape and dimensions part shape and dimensions tolerances evaluation, and this function could be called from the fixture function clamp (clamp_FF) presented as example in the Fig. 6. From a high level perspective, the stability_FF would need as input: part information (i.e.: material mechanical properties, shape, dimensions and tolerances), machining process information (i.e.: machining operations, machining strategies, volumes to remove, cutting parameters, cutting tool parameters), and fixture functional element information (i.e.: function, constraints, rules, containing volume, point and vector of application). Part of this information will have to be used to determine some derived parameters like cutting and allowed clamping forces. Making use of such infor- mation together with an analysis model, for example the one proposed by Liao et al. 32, and optimization methods, for example the one proposed by Pelinescu et al. 33, such stability_FF could be developed and implemented. The complexity in the detailed specification of such stability_FF is extremely high, and demands its own research by itself Fig. 6. High-level function template Fig. 7. Structure of the AFNOR fixture Fixture functional elements: function constraints rules containing volume Function Clamp (clamp_FF) F4 ting forces ine clamping surface amping points amping orientation ine clamping forces ine clamping elements 32,34,35, but the definition of a high level function where all the information needed for its development could be represented, is one of the objectives of the research presented in this paper. Phase 3: The third phase, functional design (FD), is aimed to create a set of functional solutions for the fixture design. A functional solution is independent of any particular commercial fixture component, and it is rep- resented by means of a set of fixture functional elements. A fixture functional element satisfies at least one of the functions identified as inherent to a fixture, i.e.: centre, position, orientate, clamp, and support. These elements are represented by means of graphical symbols, also called functional symbols, which apart from the functionality also represent some qualifiers that affect them. Such fixture functional symbols are based on the technological elements defined in the AFNOR standard NF E 04-013 - 1985 36. Fig. 7 presents their structure, which comprises: kind of representation. technological elements. Type Function *Surface class: Machined *Type contact surface: Punctual technology, state of the part surface, function of the technological element, and the kind of contact between the part surface and the fixture element. In order to progress from the functional design to the detailed one, which is the next phase, it has been defined a mapping table between functional symbols and commercial fixture elements 20, Table 2 represents an example. For the creation of the possible functional solutions a set of input information, analysis models, optimization func- tions, and rules has to be included in the software functions previously defined in the second phase. Basically, the inputs defined are: Part information: material mechanical properties, shape and dimensions of the part to be machined, and the associated tolerances. Functional element information: functions, associated restrictions, orientation, containing volume, contact parameters, and location point. Part manufacturing process: sequence of operations, and for each operation: machining strategy, cutting para- meters, cutting tool, and volume to remove. Production estimation of: number of set-ups, set-up times, batch size, production rate, and target cost. Resource information: machine morphology, and machine capacity. Functional design brings benefits to design environments Table 2 Relation between AFNOR elements and fixture commercial components Fixture function Functional representation Clamp function (Attribute) Type technology Surface Class *Type technology *Surface class *Type contact surface *Type function R. Hunter et al. / International Journal of Machine690 where the solution is mainly driven by the satisfaction of quantitative functions, as opposite to environments where subjective aspects like aesthetics has a major relevance. In particular, in the fixture design environment, the advantage of creating a functional solution derives from not using a full library of commercial fixture elements but a reduced number of basic functional elements, which can be transformed into the former ones in a second design phase. And this is particularly relevant when some kind of artificial intelligence technique is going to be applied in the implementation phase, since many of these techniques are based on the initial generation of a complete design space where the possible solutions are contained, if the design space can be reduced then the determination of the solutions can be done more efficiently. And with the functional design approach the design space is divided in two subsets, one subset dealing with the functional solution and other dealing with the physical one. Phase 4: The fourth phase, detailed design (DD) comprises the creation of detailed solutions from a functional one. To undertake this phase the mapping tables previously mentioned and the corresponding interpretation rules have to be used. To mention as well, that the fixture software functions apply in a similar way, but with a different input, which basically is the geometry (containing volume) associated with the fixture element, this is particularly relevant for the interference checking. How- ever, in this case the space of possible solutions is reduced by the fact that only those commercial elements that can be mapped to the functional ones can be used, and that a point of application and an orientation vector for the elements to be used are data as well. A detailed solution contains the finalfixturecommercialelementstobeusedinthe machining of the part and their set-up. Finally, the fifth phase, validation of the design (FV), is aimed to make a final evaluation and validation of the functional requirements and their associated constraints defined in the first phase. However, it is important to mention that in addition to a final validation, the functional approach, with the separation of the design spaces in two parts, allows implementing the validation in two prior stages. First in the functional design phase, so the possible functional design Type contact surface *Type function: Machining Fixture Commercial elements selected type *Type technology: Clamp Tools & Manufacture 46 (2006) 683697 solutions fulfil the imposed requirements, and second in the detailed design phase. This can be made by means of the optimization method that can be included in the Fixture Function (FF), as it was previously mentioned in the Phase 3. Based on this methodology, a detailed definition of the fixture functional design process is presented in the next section. 4. Fixture functional design process model As it was mentioned in the introduction, the functional approach to design has drawn the attention of several researchers 2,5,6,7,8. However, as it is pointed out by Kitamura 7, in general, the functional knowledge is left implicit, there are not clear definitions of the functional concepts, and the generic functions proposed in the literature are too generic to be used by designers. In this sense, the ontological approach is an interesting contri- bution to formalize the functional design knowledge. The approach adopted in this research deals with the definition of what would be the first step in a fixture ontology development, which is the modelling of the fixture information. The functional approach to fixture design, based on an information model definition, has some characteristics that can be deduced from the facts presented in the previous sections, that is: a reduced number of functions that a fixture has to perform, the possibility of formalizing the FRs specification with quantitative qualifiers, and the reduction of the design space by using functional elements. However, prior to the definition of any fixture information model, it is necessary to define the fixture design process and the information flow along it. Following is the activity model developed in this research to represent the fixture design process. The model is represented using the IDEF0 technique and UML, and it allows identifying the knowledge units needed during such process, and the interaction among used modelling techniques to represent the process and part of the information related to the fixture design process 37,38, but without taking a functional approach to it. Starting with the input knowledge units related to part geometry, manufacturing process plan, machining resources, and following the IDEF0 methodology, the first step is to create a context diagram or highest-level diagram, of the fixture design process. The knowledge units that constitute the final output to the process are the fixture detailed design, and the fixture assembly plan. The resource knowledge units are the machine-tool unit and the modular fixture elements one. The IDEF0 methodology is based on the definition of a hierarchical b