CA10B解放汽車中間軸軸承支架機械加工工藝規(guī)程及夾具設(shè)計【銑銷支架兩側(cè)平面】【說明書+CAD】,銑銷支架兩側(cè)平面,說明書+CAD,CA10B解放汽車中間軸軸承支架機械加工工藝規(guī)程及夾具設(shè)計【銑銷支架兩側(cè)平面】【說明書+CAD】,ca10b,解放,汽車,中間,軸承,支架,機械,加工,工藝,規(guī)程,夾具 工廠工藝加工工藝過程卡產(chǎn)品型號CA10B零件圖號831013KG-000產(chǎn)品名稱解放牌汽車零件名稱中間軸軸承支架共 1 頁第 1 頁材料牌號HT200毛坯種類鑄件毛坯外形尺寸26726183每毛坯可制件數(shù)1每臺件數(shù)1備注工序號工序名稱工序內(nèi)容車間工段設(shè)備工藝裝備工時/min準終單件010車削 粗車155兩端面金工C630A專用夾具JJ-C016.40020鏜削 粗鏜并半精鏜140內(nèi)孔，倒角C2金工T611A專用夾具JJ-T011.08030銑削 粗銑中間凸平面金工X5030A專用夾具JJ-X010.35040鉆削 鉆中間平面12小孔金工Z5125專用夾具JJ-Z010.10050銑削 銑支架兩側(cè)面金工X5030A專用夾具JJ-X021.30060鉆削 鉆側(cè)支架12兩小孔金工X61專用夾具JJ-X020.20070鉆削 鉆7.2兩孔金工X61專用夾具JJ-Z020.22100去毛刺 鉗工去毛刺金工110檢驗 終檢質(zhì)檢室描 圖描 校底圖號裝訂號設(shè)計（日期）審核（日期）標準化（日期）會簽 （日期）標記處數(shù)更改文件號簽字日期標記處數(shù)更改文件號簽字日期工廠工藝加工工序卡產(chǎn)品型號CA10B零件圖號831013KX-010產(chǎn)品名稱解放牌汽車零件名稱中間軸軸承支架共 7 頁第 1 頁車間工序號工序名稱材料牌號金工010車削HT200毛坯種類毛坯外形尺寸每毛坯可制件數(shù)每臺件數(shù)鑄件2672618311設(shè)備名稱設(shè)備型號設(shè)備編號同時加工件數(shù)臥式車床C630ACM-011夾具編號夾具名稱切削液JJ-C01車床夾具工位器編號工位器具名稱工序工時準件單件6.4工步號工步名稱工藝裝備主軸轉(zhuǎn)速(rmin-1)切削速度(mmin-1)進給量/mm背吃刀量/mm進給次數(shù)工時機動單件011粗車155mm一端面至52.5mmC630A；硬質(zhì)合金車刀；卡尺188920.32.513.2012粗車155mm另一端面，保證尺寸50mm188920.32.513.2描 圖描 校底圖號裝訂號設(shè)計（日期）審核 （日期）標準化（日期）會簽 （日期）標記處數(shù)更改文件號簽字日期標記處數(shù)更改文件號簽字日期工廠工藝加工工序卡產(chǎn)品型號CA10B零件圖號831013KX-020產(chǎn)品名稱解放牌汽車零件名稱中間軸軸承支架共 7 頁第 2 頁車間工序號工序名稱材料牌號金工020鏜削HT200毛坯種類毛坯外形尺寸每毛坯可制件數(shù)每臺件數(shù)鑄件2672618311設(shè)備名稱設(shè)備型號設(shè)備編號同時加工件數(shù)臥式鏜床T611ATK-011夾具編號夾具名稱切削液JJ-T01鏜床夾具工位器編號工位器具名稱工序工時準件單件1.08工步號工步名稱工藝裝備主軸轉(zhuǎn)速(rmin-1)切削速度(mmin-1)進給量/mm背吃刀量/mm進給次數(shù)工時機動單件021粗鏜140內(nèi)孔至139T611A；單刃鏜刀；卡規(guī)15065.471210.4022半精鏜140內(nèi)孔20087.920.50.510.6023倒角245T611A；單刃鏜刀200902210.04024倒另一面倒角245200902210.04描 圖描 校底圖號裝訂號設(shè)計（日期）審核 （日期）標準化（日期）會簽（日期）標記處數(shù)更改文件號簽字日期標記處數(shù)更改文件號簽字日期工廠工藝加工工序卡產(chǎn)品型號CA10B零件圖號831013KX-030產(chǎn)品名稱解放牌汽車零件名稱中間軸軸承支架共 7 頁第 3 頁車間工序號工序名稱材料牌號金工030銑削HT200毛坯種類毛坯外形尺寸每毛坯可制件數(shù)每臺件數(shù)鑄件2672618311設(shè)備名稱設(shè)備型號設(shè)備編號同時加工件數(shù)立式升降臺銑床X5030AXM-011夾具編號夾具名稱切削液JJ-X01銑床夾具工位器編號工位器具名稱工序工時準件單件0.35工步號工步名稱工藝裝備主軸轉(zhuǎn)速(rmin-1)切削速度(mmin-1)進給量/mm背吃刀量/mm進給次數(shù)工時機動單件031銑中間平面，保證尺寸12mmX5030A；鑲齒套式面銑刀；卡尺10025.121.92.510.35描 圖描 校底圖號裝訂號設(shè)計（日期）審核（日期）標準化 （日期）會簽（日期）標記處數(shù)更改文件號簽字日期標記處數(shù)更改文件號簽字日期工廠工藝加工工序卡產(chǎn)品型號CA10B零件圖號831013KX-040產(chǎn)品名稱 解放牌汽車零件名稱中間軸軸承支架共 7 頁第 4 頁車間工序號工序名稱材料牌號金工040鉆削HT200毛坯種類毛坯外形尺寸每毛坯可制件數(shù)每臺件數(shù)鑄件2672618311設(shè)備名稱設(shè)備型號設(shè)備編號同時加工件數(shù)立式升降臺銑床Z5125ZK-011夾具編號夾具名稱切削液JJ-Z01鉆床夾具工位器編號工位器具名稱工序工時準件單件0.1工步號工步名稱工藝裝備主軸轉(zhuǎn)速(rmin-1)切削速度(mmin-1)進給量/mm背吃刀量/mm進給次數(shù)工時機動單件041鉆12孔Z5125；直柄小麻花鉆；卡尺39214.80.5510.1描 圖描 校底圖號裝訂號設(shè)計（日期）審核（日期）標準化（日期）會簽 （日期）標記處數(shù)更改文件號簽字日期標記處數(shù)更改文件號簽字日期工廠工藝加工工序卡產(chǎn)品型號CA10B零件圖號831013KX-050產(chǎn)品名稱 解放牌汽車零件名稱中間軸軸承支架共 7 頁第 5 頁車間工序號工序名稱材料牌號金工050銑削HT200毛坯種類毛坯外形尺寸每毛坯可制件數(shù)每臺件數(shù)鑄件2672618311設(shè)備名稱設(shè)備型號設(shè)備編號同時加工件數(shù)立式升降臺銑床X5030AXM-021夾具編號夾具名稱切削液JJ-X02銑床夾具工位器編號工位器具名稱工序工時準件單件1.3工步號工步名稱工藝裝備主軸轉(zhuǎn)速(rmin-1)切削速度(mmin-1)進給量/mm背吃刀量/mm進給次數(shù)工時機動單件051銑一側(cè)支架，保證尺寸12mmX6030；鑲齒套式面銑刀；卡尺10025.121.92.510.65052銑另一側(cè)支架，保證尺寸12mm10025.121.92.510.65描 圖描 校底圖號裝訂號設(shè)計（日期）審核 （日期）標準化（日期）會簽 （日期）標記處數(shù)更改文件號簽字日期標記處數(shù)更改文件號簽字日期工廠工藝加工工序卡產(chǎn)品型號CA10B零件圖號831013KX-060產(chǎn)品名稱解放牌汽車零件名稱中間軸軸承支架共 7 頁第 6 頁車間工序號工序名稱材料牌號金工060鉆削HT200毛坯種類毛坯外形尺寸每毛坯可制件數(shù)每臺件數(shù)鑄件2672618311設(shè)備名稱設(shè)備型號設(shè)備編號同時加工件數(shù)臥式銑床X61ZK-021夾具編號夾具名稱切削液JJ-X02銑床夾具工位器編號工位器具名稱工序工時準件單件0.2工步號工步名稱工藝裝備主軸轉(zhuǎn)速(rmin-1)切削速度(mmin-1)進給量/mm背吃刀量/mm進給次數(shù)工時機動單件061鉆12兩孔X61；直柄小麻花鉆；卡尺38014.320.5520.2描 圖描 校底圖號裝訂號設(shè)計（日期）審核（日期）標準化（日期）會簽（日期）標記處數(shù) 更改文件號簽字日期標記處數(shù)更改文件號簽字日期工廠工藝加工工序卡產(chǎn)品型號CA10B零件圖號831013KX-070產(chǎn)品名稱 解放牌汽車零件名稱中間軸軸承支架共 7 頁第 7 頁車間工序號工序名稱材料牌號金工070鉆削HT200毛坯種類毛坯外形尺寸每毛坯可制件數(shù)每臺件數(shù)鑄件2672618311設(shè)備名稱設(shè)備型號設(shè)備編號同時加工件數(shù)臥式銑床X61ZK-031夾具編號夾具名稱切削液JJ-Z02鉆床夾具工位器編號工位器具名稱工序工時準件單件0.22工步號工步名稱工藝裝備主軸轉(zhuǎn)速(rmin-1)切削速度(mmin-1)進給量/mm背吃刀量/mm進給次數(shù)工時機動單件071鉆7.2兩孔X61；直柄小麻花鉆；卡尺59022.230.420.22描 圖描 校底圖號裝訂號設(shè)計（日期）審核 （日期）標準化（日期）會簽 （日期）標記處數(shù)更改文件號簽字日期標記處數(shù)更改文件號簽字日期機械制造技術(shù)基礎(chǔ)課程設(shè)計說明書 目錄 序 言 1 一、零件的分析 2 〈一〉零件的作用 2 〈二〉零件的工藝分析 2 二、工藝規(guī)程的設(shè)計 3 <一> 確定毛坯的制造形式 3 <二> 基準的選擇 3 <三> 制定工藝路線 4 <四> 機械加工余量,工序尺寸及毛坯尺寸的確定 6 <五> 切削用量以及機床的確定 7 三、 零件專用夾具的設(shè)計 10 <一> 設(shè)計方案的確定 10 <二> 夾緊力的分析 11 <三> 精度的分析 11 四．課程設(shè)計總結(jié) 12 參考書目 13 序 言 機械制造技術(shù)基礎(chǔ)課程設(shè)計是我們學完了大學全部基礎(chǔ)知識，技術(shù)基礎(chǔ)課以及大部分專業(yè)課以后進行的。這是我們在進行畢業(yè)設(shè)計之前對所學課程一次深入的，綜合性的總復(fù)習，也是一次理論聯(lián)系實際的訓練，因此它在我四年的大學生活中占有重要地位。 就我個人而言，這次課程設(shè)計是對自己未來從事的工作進行的一次適應(yīng)性的訓練，從中鍛煉自己分析問題，解決問題的能力，為今后的工作打下良好的基礎(chǔ)。 一、零件的分析 〈一〉零件的作用 題目給出的是CA10B解放牌汽車中間軸軸承支架，它的主要作用是（1)起到穩(wěn)固滾子的作用 (2)在安裝時起到固定滾珠的作用,利于安裝。要求零件的配合符合要求。 〈二〉零件的工藝分析 零件的加工過程中，要保證零件上部的折彎部分在豎直方向與?140孔成5.5°的夾角，同時要保證支架兩側(cè)板的平面與水平面成30°的夾角，孔中心到頂小孔所在平面的距離為40mm，且每孔中心線與豎直方向零件的夾角成60°夾角。要保證以上尺寸要求，最好先將?1400+0.26的內(nèi)孔和端面加工完成，再以內(nèi)孔和端面為定位基準對上凸臺表面進行加工，最后以?1400+0.26內(nèi)孔，端面，和上?13的小孔（一面兩銷）為定位基準，加工支架兩側(cè)板，其中主要加工面粗糙度為6.3μm，其余表面粗糙度為50μm. 二、工藝規(guī)程的設(shè)計 <一> 確定毛坯的制造形式 零件的材料為HT200,零件承受的沖擊載荷不是很大，且零件的輪廓尺寸較大，又是大批量生產(chǎn)，而且表面粗糙度質(zhì)量要求也不是很高，故可采用鑄件，以提高生產(chǎn)效率和效益。 <二> 基準的選擇 基準的選擇是工藝規(guī)程設(shè)計中的重要工作之一，他對零件的生產(chǎn)是非常重要的。 1． 粗基準的選擇 先選取?155外圓為定位基準，利用三爪卡盤為定位元件，銑?155兩端面，再以?155外圓為定位基準，利用三爪卡盤為定位元件，鏜?1400+0.26內(nèi)孔。 2． 精基準的選擇 以?1400+0.26內(nèi)孔，?155端面，?13孔（兩面一銷）為定位精基準，加工其它表面及孔。主要考慮精基準重合的問題，當設(shè)計基準與工序基準不重合的時候，應(yīng)該進行尺寸換算，這在以后還要進行專門的計算，在此不再重復(fù)。 <三> 制定工藝路線 制定工藝路線的出發(fā)點，應(yīng)當是使零件的幾何形狀，尺寸精度及位置精度的技術(shù)要求能得到合理的保證，在生產(chǎn)綱領(lǐng)已確定為大批量生產(chǎn)的條件下，可以考慮采用萬能機床以及專用夾具，并盡量使工序集中來提高生產(chǎn)率。除此之外還應(yīng)當考慮經(jīng)濟效果，以便生產(chǎn)成本盡量降低。 1).工藝路線方案一 工序1 以?155外圓為定位基準，車?155兩端面掉轉(zhuǎn)； 工序2 以?155外圓為定位基準，粗鏜、半精鏜?1400+0.26內(nèi)孔，； 工序3 以?1400+0.26內(nèi)孔為定位基準，銑頂小凸臺面； 工序4 以?1400+0.26內(nèi)孔為定位基準，鉆中間?13的孔； 工序5 以?1400+0.26內(nèi)孔，中間?13小孔，?155端面為定位基準，銑支架兩側(cè)臺平面； 工序6 以?1400+0.26內(nèi)孔，中間?13小孔，?155端面為定位基準，鉆支架兩側(cè)臺平面的?13小孔， 工序7 以?155外圓為定位基準，鉆2X?7.20+0.2小孔； 工序8 檢查。 2). 工藝路線方案二 工序1 銑削 以?155外圓和一端面為基準,銑一端面,粗糙度為50μm,翻轉(zhuǎn)銑另一端面,粗糙度為50μm; 工序2 鏜削 以?155外圓和一端面為基準,粗鏜內(nèi)孔到?139.8mm,半精鏜內(nèi)孔到?1400+0.26,倒2X45°倒角,粗糙度為50μm; 工序3 銑削 以?1400+0.26內(nèi)孔和一端面為基準,銑上中間凸平面,使其厚度為12mm,表面粗糙度為50μm; 工序4 鉆孔 以?1400+0.26內(nèi)孔和一端面為基準,鉆中間?13的孔,粗糙度為50μm; 工序5 銑削 銑支架兩側(cè)平面.表面粗糙度為50μm; 工序6 鉆孔 以?1400+0.26內(nèi)孔, ?155端面以及中間?13的小孔為定位基準(一面兩銷),鉆支架兩側(cè)平面?13的孔,表面粗糙度為50μm; 工序7 鉆孔 一?1400+0.26和?155一端面為基準,鉆圓柱面上兩小孔,2X?7.20+0.2,保證兩孔間距離為32±0.1mm; 工序8 檢查. 比較以上兩種方案,兩種方案的定位基準基本一樣,加工工序的 步驟也一樣,但方案一中?155端面用車銷加工也可以,但由于工件上 面的突出部分使得車銷時轉(zhuǎn)動起來工件的離心力太大,這樣會影響加 工的精度,同時也給夾具的設(shè)計帶來一定的難度,況且其工件裝夾的次數(shù)要比第二種方案多,故影響加工效率,.而第二種方案中, ?155兩端面采用銑銷加工,這樣工件上面的突出部分就不會對加工產(chǎn)生大的影響.所以第二種方案更為經(jīng)濟合理,選第二種方案. <四> 機械加工余量,工序尺寸及毛坯尺寸的確定 CA10B中間軸軸承支架零件材料為HT200,生產(chǎn)類型為大批量 產(chǎn).根據(jù)上訴資料及加工工藝,分別確定各加工表面的機加工余量,工序尺寸以及毛坯尺寸如下: 1. ?155兩端面 參照<<機械加工工藝手冊>>,因其表面質(zhì)量要求比較低(粗糙度為50μm),故可直接對其表面進行銑銷;銑銷厚度為2mm,故毛坯兩表面之間的厚度為50mm+2mm=52mm厚; 2. ?140內(nèi)孔的加工 參照<<機械加工工藝手冊>>,其加工余量為0.5mm,粗鏜0.4mm,精鏜0.1mm,故毛坯的尺寸為?140mm-0.5mm=139.50+0.26mm; 3. 銑中凸臺面 參照<<機械加工工藝手冊>>,因其表面質(zhì)量要求比較低(粗糙度為50μm),故可直接對其表面進行銑銷;銑銷厚度為2mm,故毛坯凸臺平面的厚度為12mm+2mm=14mm; 4. 鉆中間?13的孔 參照<<機械加工工藝手冊>>,因其表面質(zhì)量要求比較低(粗糙度為50μm),故可直接對其進行鉆孔; 5. 銑側(cè)兩平面 參照<<機械加工工藝手冊>>,因其表面質(zhì)量要求比較低(粗糙度為50μm),故可直接對其表面進行銑銷;銑銷厚度為2mm,故毛坯兩側(cè)平面的厚度為12mm+2mm=14mm; 6. 鉆兩側(cè)平面孔 參照<<機械加工工藝手冊>>,因其表面質(zhì)量要求比較低(粗糙度為50μm),故可直接對其進行鉆孔; 7. 鉆圓柱面上兩小孔 參照<<機械加工工藝手冊>>,因其公差等級要求比較低(兩孔軸線之間的距離為32±0.1mm,兩孔的直徑為?7.20+0.2,故可直接對其進行鉆孔; <五> 切削用量以及機床的確定 工序1. 銑兩端面,選用X50A式銑床,采用w18Cr4V立銑刀,dw=16mm,z=3,切削速度:參考有關(guān)手冊,V=37m/min.進給量為0.25mm/r; 工序2. 粗鏜?1400+0.26mm內(nèi)孔, 選用T611臥式鏜床,采用通空鏜刀,d=25mm,鏜銷速度:參考有關(guān)手冊V=25m/min,進給量為0.2mm/r; 精鏜?1400+0.26mm內(nèi)孔,選用T611臥式鏜床,采用通空鏜刀,d=20mm,鏜銷速度:參考有關(guān)手冊V=20m/min,進給量為0.15mm/r 工序3. 銑中間凸平面,選用X50A立式銑床, 采用w18Cr4V立銑刀,dw=16mm,z=3,切削速度:參考有關(guān)手冊,V=37m/min.進給量為0.25mm/r; 工序4. 鉆中間?13的孔,選用Z518立式鉆床,采用直柄小麻花鉆,d=13mm, 鉆削速度:參考有關(guān)手冊,V=23m/min.進給量為0.3mm/r; 工序5. 銑支架兩側(cè)平面,選用X6030臥式銑床采用w18Cr4V臥銑刀,dw=16mm,z=3,切削速度:參考有關(guān)手冊,V=37m/min.進給量為0.25mm/r; 工序6. 鉆支架兩側(cè)平面小孔, 選用Z518立式鉆床,采用直柄小麻花鉆,d=13mm, 鉆削速度:參考有關(guān)手冊,V=23m/min.進給量為0.3mm/r; 工序7. 鉆圓柱面上兩小孔, 選用Z518立式鉆床,采用直柄小麻花鉆,d=7.2mm, 切削速度:參考有關(guān)手冊,V=18m/min.進給量為0.2mm/r. 三、 零件專用夾具的設(shè)計 本次課程設(shè)計所設(shè)計的是銑銷CA10B解放牌汽車中間軸軸承支架兩側(cè)平面的專用夾具.其具體設(shè)計思路及方案如下: <一> 設(shè)計方案的確定 本夾具是銑銷支架兩側(cè)平面用,該零件表面不規(guī)則,故不能用通用的機床夾具來裝夾,又因其是大批量生產(chǎn),所以要設(shè)計專用夾具以提高加工精度和加工效率.分析零件,加工支架兩側(cè)平面是在中間的?1400+0.26內(nèi)孔和?13的小孔加工以后加工的,故定位的時候可以考慮用這幾個已加工的面或孔來作定位基準加工支架兩側(cè)平面,這樣可以提高加工的精度. 再者,因為支架兩側(cè)平面與支架?1400+0.26內(nèi)孔軸線有一定的夾角,故銑銷的時候要產(chǎn)生相對工件幾個方向的力,所以要把六個自由度全部限制了.因為在加工這兩個平面之前,除了上面提到的兩孔外,還有?155兩個端面也已加工完成.所以可以考慮一面兩銷定位,即兩個短銷分別固定?1400+0.26和?155兩個空,再利用一平面即可實現(xiàn)完全定位,這樣就可以對零件進行精確的定位,可以保證加工精度. 又因零件加工的兩個面不在同一平面上,而是有一定的角度,故夾具的設(shè)計中還應(yīng)考慮的分度的問題,以提高加工效率.可采用一分度盤,將零件固定在分度盤上,通過分度盤的轉(zhuǎn)動帶動零件的轉(zhuǎn)動,分度盤可通過其上的一個當塊和固定在夾具座上的兩個當塊限位. 綜上所述,本夾具可采用兩個定位銷,一個分度盤,一個壓板和夾具座等主要元件組成. <二> 夾緊力的分析 本到工序為銑片面,因此對工作臺將產(chǎn)生一個扭矩,但因切銷量很小(2mm),故其扭矩也不會太大,根據(jù)夾緊的基本原則,確定工件的夾緊方式,分度盤上的兩個定位削可將銑銷時產(chǎn)生的扭矩平衡掉.分度盤再通過兩個鉤頭壓板壓緊在夾具體座上,這樣夾緊機構(gòu)即可以保證工件夾緊的可靠,安全,又不會破壞工件的定位及夾壓表面的精度和粗糙度. <三> 精度的分析 本夾具設(shè)計的是銑支架兩側(cè)平面，用圓柱銷模擬?1400+0.26內(nèi)孔軸線，所以工序基準和設(shè)計基準重合，又由于該加工面的精度要求不是很高，那么零件的加工精度可以完全由圓柱銷的制造精度和安裝精度來保證，為此本夾具在裝配好后應(yīng)對圓柱銷的安裝精度進行檢測，如果不符合要求可以進行修配。 四．課程設(shè)計總結(jié) 就我個人而言，我希望能通過這次課程設(shè)計對自己的四年的大學生活做出總結(jié),同時為將來工作進行一次適應(yīng)性訓練，從中鍛煉自己分析問題、解決問題的能力，為今后自己的研究生生活打下一個良好的基礎(chǔ)。但是這次課程設(shè)計的確顯得有點心有余而力不足: 首先是自己的心態(tài)問題,輕視這次課程設(shè)計,以為可以像以前一樣輕輕松松地通過,其次就是基本知識問題,以前對基礎(chǔ)知識沒有很好的掌握，以后需要多加鞏固。 總的說來,在這次設(shè)計中自己學到了很多的東西,取得一定的成績,但同時也存在一定的不足和缺陷,我想這都是這次設(shè)計的價值所在,以后的日子以后自己應(yīng)該更加努力認真,以冷靜沉著的心態(tài)去辦好每一件事情! 參考書目 1.《機械制造技術(shù)基礎(chǔ)課程設(shè)計指導書》，馮濤等主編。 2．《機械加工工藝手冊》，孟少農(nóng)主編，機械工業(yè)出版社 3．《機械加工工藝設(shè)計手冊》，張耀宸，航空工業(yè)出版社 4．《機械制造技術(shù)基礎(chǔ)》，曾志新主編，武漢理工大學出版社 5．《機械設(shè)計課程設(shè)計手冊》，吳宗澤主編，高等教育出版社 12 Proceedings ofthe2006 IEEE/RSJ International Conference on Intelligent Robots and Systems October9- 15, 2006, Beijing, China ANovelModularFixtureDesignandAssemblySystem BasedonVR PengGaoliang, LiuWenjian SchoolofMechatronicsEngineering HarbinInstituteofTechnology Harbin, 150001, China pgl7782a Abstract - Modular fixtures are one oftheimportant aspects ofmanufacturing. This paper presents a desktop VR system for modular fixture design. The virtual environmentis designed and the design procedure is proposed. It assists the designer to make the feasible design decisions effectively and efficiently. A hierarchical data model is proposed to represent the modular fixture assembly. Based on this structure, the user can manipulate the virtual models precisely in VE during the design and assembly processes. Moreover, the machining simulation for manufacturing interaction checking is discussed and implemented. Finally, the case study has demonstrated the functionality of the proposed system. Compared with the immersive VR system, the proposed system has offered an affordable andportable solutionformodularfixtures design. Index Terms - Modularfixture, desktop VR, assembly design, machiningsimlulation. I. INTRODUCTION Modular fixtures are one of the important aspects of manufacturing. Proper fixture design is crucial to product quality in terms of precision, accuracy, and finish of the machined part. Modular fixture is a system of interchange- eable and highly standardized components designed to securely and accurately position, hold, and support the workpiece throughout the machining process 1. Tradition- ally, fixture designers rely on experience or use trial-and- error methods to determine an appropriate fixturing scheme. With the advent of computer technology, computer aided design has been prevalent in the area of modular fixture design. In general, the associated fixture design activities, namely setup planning, fixture element design, and fixture layout design are often dealt with at the downstream end of the machine tool development life-cycle. These practices do not lend themselves well to the bridging of design and manufacturing activities. Forexample, very few systems have incorporated the functionality of detecting machining interference. This leads to a gap between the fixture design andmanufacturing operationswheretheaspectofcutterpaths is not considered during the design stage 2. As a result, re- designcannotbeavoidedwhenthecutterisfoundtointerfere with the fixture components in the manufactu- ring set-up. Therefore, in orderto bring machining fixture design into the arenaofflexiblemanufacturing, amoresystematicandnatural designenvironmentisrequired. As a synthetic, 3D, interactive environment typically generated by a computer, VR has been recognized as a very powerful human-computer interface for decades 4. VR holds great potential in manufacturing applications to solve problems before being employed in practical manufacturing thereby preventing costly mistakes. The advances in VR technology in the last decade have provided the impetus for applying VR to different engineering applications such as product design 5, assembly 6, machining simulation 7, andtraining 8. The goal ofthis paper is to develop a VR- basedmodular fixtures design system (VMJFDS). This is the firststepto develop anintegratedandimmersiveenvironment for modular fixture design. This application has the advantages of making the fixture design in a natural and instructive manner, providing better match to the working conditions, reducing lead-time, and generally providing a significantenhancementoffixtureproductivityandeconomy. II. OVERVIEWOFTHEPROPOSEDSYSTEM The system architecture of the proposed desktop VR systemismodularisedbasedonthefunctionalrequirements of thesystem,whichisshowninFig.1. Atthesystemlevel,three modules of proposed system, namely, Graphic interface (GUI), Virtual environment (VE) and Database modules are designed. For each ofthe modules, a set ofobjects has been identified to realize its functional requirements. The detailed objectdesignandimplementation are omittedfromthispaper. Instead, the briefdescription ofthese three modules is given below. 1) Graphic Interface (GUI): The GUI is basically a friendly graphic interface that is used to integrate the virtual environmentandmodularfixturedesignactions. 2) Virtual environment (VE): TheVEprovidestheusers with a 3D display for navigating and manipulating the models of modular fixture system and its components in the virtual environment. As shown in Fig. 1, the virtual environment module comprises two parts, namely assembly design environment andmachiningsimulationenvironment. Theuser selects appropriate elements andputs downthese elements on the desk in the assembly design area. Then he assembles the selected elements one by one to build up the final fixture systemwiththeguidanceofthesystem. 1-4244-0259-X/06/$20.00 C)2006IEEE 2650 Authorized licensed use limited to: Nanchang University. Downloaded on December 20, 2009 at 22:44 from IEEE Xplore. Restrictions apply. Fig.1.OverviewofthedesktopVRbasedmodularfixturedesignsystem. 3) Database: The database deposit all of the models of environment and modular fixture elements, as well as the domain knowledge and useful cases. There are 5 databases shown in Fig.1. Among them, knowledge & rule base governing all fixture planning principles forms the brains of thesystem. III. PROCEDUREOFMODULARFIXTUREDESIGN In this section, an instructive modular fixture design procedure within VE is presented. Besides the 3D depth that the users feel and the real-world like operation process, this procedure features intelligence and introduction. During the design process, some useful cases and suggestion will be presented to the user for reference based on intelligent inference method such as Case based reasoning (CBR) and Rule based reasoning (RBR). Further more, relative knowledge andrules arepresented ashelppages thattheuser caneasilybrowsedduringthedesignprocess. Overview of modular fixture design process is summarized in Fig. 2. After the VE environment is initialed andthe workpiece is loaded, the first step is fixtureplanning. Inthis step, theuserfirstdecides thefixturing scheme, thatis specifies the fixturing faces of the workpiece interactively. Forhelptheusersdecision-making, someusefulcasesaswell as their fixturing scheme will be presented via the automatic CBR retrieval method. Once the fixturing faces are selected, theusermaybepromptto specifythefixturingpoints. Inthis task, somesuggestions andrulesaregiven. After the fixturing planning, the next step is fixture FUs design stage. In this stage, the user may be to select suitable fixture elements andassembletheseindividualparts into FUs. According to the spatial information ofthe fixturingpoints in relation to the fixture base and the workpiece, some typical FUs and suggestions may be presented automatically. These willbehelpfulfortheuser. AftertheplanningandFUs design stage, the next stage is interactively assembling the designed fixtureFUstoconnecttheworkpiecetothebaseplate. When the fixture configuration is completed, the result will be checked and evaluated within the machining environment. The tasks executed in this environment including assembly planning, machining simulation, and fixture evaluation. Assemblyplanning isusedto gain optimal assembly sequence and assembly path of each component. Machining simulation is responsible for manufacturing interaction detection. Fixture evaluation will check and evaluate the design result. In conclusion, the whole design process isinanaturemannerforthebenefitofVE. Moreover, the presented information of suggestion and knowledge can advise the user on how to make decisions ofthe best design selection. IV. ASSEMBLYMODELINGOFMODULARFIXTURE A. Modularfixturestructureanalysis A functionalunit(FU) is acombination offixture elements to provide connectionbetweenthebaseplate and aworkpiece 11. Generally, modularfixture structuremaybe dividedinto three functional units according to its basic structure characteristics, namely locating unit, clamping unit, and supporting unit. The number offixture elements in aFU may consist ofone or more elements, in which only one element serves as a locator, support or clamp. The major task ofthe modularfixture assembly is to selectthe supporting, locating, clamping and accessory elements to generate the fixture FUs toconnecttheworkpiecetothebaseplate. By analyzing the practical application ofmodular fixtures, it is found that the assembly ofmodular fixtures begins by selecting the suitable fixture elements to construct FUs, then subsequentlymountingtheseFUs onthebaseplate. Therefore, the FUs can be regarded as subassemblies ofmodular fixture system.Further,thestructureofmodularfixturesystemcanbe representedasahierarchalstructureasshowninFig.3. 2651 Authorized licensed use limited to: Nanchang University. Downloaded on December 20, 2009 at 22:44 from IEEE Xplore. Restrictions apply. UsefTa6 *T- siikg&Sugge lr,l Fixtui e Elemenets rUetrieval i0 Tools rKetrieval 4 Fig.2Modularfixturedesignprocedureinproposedsystem B. Hierarchically structured data modelfor modularfixture representation in VE It is common that the corresponding virtual environment may contain millions ofgeometric polygon primitives. Over thepastyears, anumberofmodel sub-division schemes, such asBSP-tree 10 andOctrees,havebeenproposedto organize largepolygonalmodels.However, formodular Ba 1I_ 1 Hsreplalte Bansepla1nte Elements *Locatng ElementsL,cating Units AccessoryEllements ClamnpingElemnents !ClampingUnits SupportingElemntsSupporting Ufnits Accessory Elements Fig. 3Hierarchical structureofmodularfixture system design applications, the scene is also dynamically changing, due to interactions. For example, in design process, the part object may change its spatial position, orientation and assembly relations. This indicates that a static representation, such as BSP-tree, is not sufficient. Further more, the above models can only represent the topology structure of fixture system in the component level. However, to the assembly relationship among fixture components, which refers to the mating relationship between assembly features that is not concerned. In this section, we present a hierarchically structuredandconstraint-baseddatamodelformodularfixture system representation, real-time visualization and precise 3D manipulationinVE. As shown in Fig.4, the high-level component based model is used for interactive operations involving assemblies or disassembles. It provides both topological structure and link relationsbetweencomponents. Theinformationrepresent- ed in the high-level model can be divided into two types, i.e. component objects and assembly relationships. Component objects can be a subassembly or a part. A subassembly consists of individual parts and assembly relationships betweentheparts. Component Level (Pt Part S Subassembly Assembly relationship Feature Level Ft3 Feature Feature mating relationship t- -t Polygon Level FZ-ll. Polygon Fig.4ThehierarchicalstructuredatamodelinVE Themiddle-levelfeaturebasedmodelisbuiltuponfeatures and feature constraints. In general, the assembly relationship often treated as the mating relationships between assembly features. Thus the featurebasedmodel isusedto describethe assembly relationship andprovides necessary information for spatial relationship calculating during assembly operation. In this model, only the feature relationships between two different components are considered. The relationship between features ofone element will be discussed in feature basedmodularfixtureelementmodelingbelow. The low-level polygon based model corresponds to the above two level models for real-time visualization and interaction. It describes the entire surface as an inter- connected triangular surface mesh. More about how the polygons organized of a single element will be discussed is thenextsection. C. Modularfixtureelementsmodeling As we know, in VE, the part is only represented as a number ofpolygon primitives. This result in the topological 2652 Authorized licensed use limited to: Nanchang University. Downloaded on December 20, 2009 at 22:44 from IEEE Xplore. Restrictions apply. relations- hips and parametric information are lost during the translation process of models from CAD systems to VR systems. However, this important information is necessary in design and assembly process. In order to fulfill the requirements, we present a modeling scheme for fixture elementsrepresentationinthissection. The modular fixture elements are pre-manufactured parts withstandarddimensions. Afterthefixturingschemedesigned, the left job is to select suitable standard elements and assemblethese elements to formafixture systeminafeasible andeffectivemanner. Therefore, intheproposed system, only the assembly features of the fixture elements need to be considered. Inthispaperanassemblyfeature isdefinedas apropertyof afixture element, whichprovidesrelatedinformationrelevant to modular fixture design and assembly/disassembly. The following eight function faces are defined as assembly featuresoffixtureelements: supportingfaces, supportedfaces, locating holes, counterbore holes, screw holes, fixing slots, andscrewbolts. Besidestheinformation aboutthefeaturelike typeanddimension, otherparameters, i.e. therelativeposition andorientationofthe featureintheelements localcoordinate system are recorded with the geometric model in the fixture element database. When one element assembles with another, the information aboutthematedfeatures isretrieved andused to decide the spatial relationship ofthe two elements. More information about the assembly features and their mating relationship arediscusseddetailedinRef 1. D. Constraintbasedfixtureassemblyin VE 1)Assemblyrelationshipbetweenfixtureelements Mating relationships have been used to define assembly relationships between part components in the field of assembly. According to the assembly features summarized in the above section, there are fivetypes ofmating relationships between fixture elements. Namely against, fit, screw fit, across, andT-slotfit,which are illustrated inFig. 5. Based on these mating relationships, we can reason the possible assemblyrelationshipofanytwoassembledfixtureelements. 2)Assemblyrelationshipreasoning Ingeneral, the assemblyrelationship oftwo assembledpart isrepresented as thematedassembly featurepairs ofthem. In the above section, we defined five basic mating relationships between fixture elements. Therefore, it is enabled to decide the possible assembly relationships through finding the possible mating assembly feature pairs. These possible assembly relationships are saved in assembly relationships database(ARDB)forfixtureassemblyinnextstage. However, when the fixture is complicated and the numbers ofcomposite fixture elements is large, the possible assembly relationships are too much to take much time for reasoning andtreating. To avoidthis situation, wefirstdecide the possible assembled elements pairs. That is to avoid reasoning the assembly relationship between a clamp andthe baseplate, for they never were assembled together. In this stage, some rules are utilized to find the possible assembled elementspairs. The algorithm of assembly relationships reasoning is similar to what discussed in Ref 12. Thus the detailed descriptionofthealgorithmisomittedfromthispaper. (a) AIlai.ns .2 l.I.F LIi I7 F d) Asicmie 1f-isxkt Elmn Fig. 5Fivebasicmatingrelationshipsbetweenfixtureelements 3)Constraint-basedfixtureassembly Aftercarrying outthe assemblyrelationships reasoning, all possible assembly relationships ofthe selected elements are establishedandsavedinARDB. Basedontheserelationships, the trainee can assemble these individual parts to a fixture system. This section is about the discussion of interactive assembly operation in VE. The process ofa single assembly operation is presented in Fig.5 and illustrated by two simple partsassemblyasshowninFig.6. In general, the assembly operation process is divided into three steps, namely assembly relationship recognizing, constraint analysis and applying, constraint-based motion. Firstly, the trainee selects an element and moves it to the assembled component. Once an inference between the assembling and assembled component is detected during the moving,the inferredfeatures is checked. Ifthetwo features is one of the assembly relationships in ARDB, they will be highlighted and will await the users confirmation. Once it is confirmed, the recognized assembly relationship will be appliedby constraint analyzing and solving, that is adjustthe translationandorientationoftheassemblingelementtosatisfy the position relationship ofthese two components, as well as applythenew constrainttotheassemblingelement.Whenthe new constraint is applied, the motion of the assembling element will be mapped into a constraint space. This is done bytransferring 3Dmotiondatafromtheinputdevicesintothe allowable motions ofthe object. The constraint-based motion notonlyensuresthattheprecisepositionsofacomponentcan be obtained, but also guarantee that the existing constraints will not be violated during the future operations. The assembling element will reach to the final position through succession assembly relationship recognizing and constraint applying. 2653 Ii 1-11 4- (b) F.t Authorized licensed use limited to: Nanchang University. Downloaded on December 20, 2009 at 22:44 from IEEE Xplore. Restrictions apply. NO Assembly relationship Iis possible checking elatioohship? Fig. 6Processofassemblyconstraintestablishment No V. MACHINING SIMULATION A. Manufacturinginteractions During the machining process, there are many types of manufacturing interactions associated with the fixture may occur. These interactions can be divided into two broad categories illustrated below, namely static interactions and dynamicinteractions. 1) Static interactions refer to the interference between fixture components, the interference between fixture components and machine tool, and the interference between fixture components andmaching feature ofworkpiece during theworkpiecesetup. 2)Dynamicinteractionsrefertothetool-fixtureinteractions, which occur within a single operation when the tool and the fixtureusedinthatoperationmaycollideduringcutting. Generally, the aspects of machining process and cutter paths are not considered duringthe fixture design stage. As a result, these interactions may often occur during the practical manufacturing. Thus the human machinists have to spend muchoftheirtimeidentifyingtheseinteractions andresolving them. Itis oftenresults inmodification orre-designoffixture system. Thatistediousandtimecostly. B.Interferencedetection Although the currently commercial software, like VERICUT, can simulates NC machining to detect tool path errors and inefficient motion prior to machining an actual workpiece. It is available to eliminate errors that could ruin the part, damage the fixture, break the cutting tool, or crash the machine during the part programming stage. However, these software are expensive and oriented to NC program- mertherebynotsuitableforfixturedesigners. During the fixture design stage, it should be ensured that the associated fixture interactions can be avoided. In this system, after the fixture configuration is complete, the machining simulation module is presented to the user to identifytheinteractionsandresolvethem. Within the machining simulation environment, the 3D digitalmodelofmachinetoolispresented. The canassemble the fixture components on the work bench and setup the workpiece, just as what the machining engineers do in the actual site. During the setup, the fixture components and the workpiece are move to their assembly position under manipulation. Theinterferencecheckingmoduleiscarriedout. Ifinterference occurs, the inferred objectwill be highlight. It is p