傳動(dòng)箱體工藝與夾具設(shè)計(jì)銑床夾具設(shè)計(jì)

傳動(dòng)箱體工藝與夾具設(shè)計(jì)銑床夾具設(shè)計(jì),傳動(dòng),箱體,工藝,夾具,設(shè)計(jì),銑床 畢 業(yè) 設(shè) 計(jì) 設(shè)計(jì)題目： 傳動(dòng)箱體工藝與夾具設(shè)計(jì) 系 別: 專 業(yè): 班 級(jí): 姓 名: 學(xué) 號(hào): 設(shè)計(jì)小組: 指導(dǎo)教師: 完成時(shí)間: 機(jī) 械 加 工 工 序 卡 產(chǎn)品型號(hào) 零件名稱 零件號(hào) 傳動(dòng)箱體 工序名稱 粗,精銑上平面 工序號(hào) 01 技檢要求 按照?qǐng)D示要求保證粗糙度要求并保證尺寸57,要求已加工平面無(wú)明顯刀痕 基準(zhǔn)面 下平面與側(cè)面 材料 同時(shí)加工零件數(shù) 設(shè)備 牌號(hào) 硬度 名稱 型號(hào) HT200 200HBS 1 立式銑床 X52K 夾具 定 額 代號(hào) 名稱 單件時(shí)間（分） 每班次數(shù) 每臺(tái)件數(shù) 工人等級(jí) 工步號(hào) 工步內(nèi)容 走刀長(zhǎng)度(毫米） 走刀次數(shù) 切削深度(毫米） 切削速度（米/秒） 主軸轉(zhuǎn)速（轉(zhuǎn)/分） 進(jìn)給量（毫米/轉(zhuǎn)） 機(jī)動(dòng)時(shí)間（分） 輔助時(shí)間（分） 刀具 輔具 量具 名稱規(guī)格 數(shù)量 名稱規(guī)格 數(shù)量 名稱規(guī)格 1 粗銑平面,控制尺寸到104mm 55 1 2 1.57 300 4.8 1.13 1.04 高速鋼三面刃圓盤銑刀 1 1 專用量具 2 精銑平面,控制尺寸到103mm 55 1 2 0.4 75 0.8 1.09 1.04 高速鋼三面刃圓盤銑刀 1 1 專用量具 擬制 日期 審核 日期 批準(zhǔn) 日期 共 頁(yè) 第 頁(yè) 機(jī) 械 加 工 工 序 卡 產(chǎn)品型號(hào) 零件名稱 零件號(hào) 傳動(dòng)箱體 02 工序名稱 粗,精銑下平面 工序號(hào) 技檢要求 按照?qǐng)D示要求保證粗糙度要求并保證尺寸100±0.1工平面無(wú)明顯刀痕 基準(zhǔn)面 上平面與側(cè)面 材料 同時(shí)加工零件數(shù) 設(shè)備 牌號(hào) 硬度 名稱 型號(hào) HT200 200HBS 1 立式銑床 X52K 夾具 定 額 代號(hào) 名稱 單件時(shí)間（分） 每班次數(shù) 每臺(tái)件數(shù) 工人等級(jí) 工步號(hào) 工步內(nèi)容 走刀長(zhǎng)度(毫米） 走刀次數(shù) 切削深度(毫米） 切削速度（米/秒） 主軸轉(zhuǎn)速（轉(zhuǎn)/分） 進(jìn)給量（毫米/轉(zhuǎn)） 機(jī)動(dòng)時(shí)間（分） 輔助時(shí)間（分） 刀具 輔具 量具 名稱規(guī)格 數(shù)量 名稱規(guī)格 數(shù)量 名稱規(guī)格 1 粗銑平面,控制尺寸到101mm 70 1 2 1.57 300 4.8 1.13 1.04 高速鋼三面刃圓盤銑刀 1 專用量具 2 精銑平面,控制尺寸到100mm 70 1 1 0.4 75 0.8 1.09 1.04 高速鋼三面刃圓盤銑刀 1 專用量具 擬制 日期 審核 日期 批準(zhǔn) 日期 共 頁(yè) 第 頁(yè) 機(jī) 械 加 工 工 序 卡 產(chǎn)品型號(hào) 零件名稱 零件號(hào) 傳動(dòng)箱體 工序名稱 粗精銑寬度為20mm的側(cè)面 工序號(hào) 03 技檢要求 按照?qǐng)D示要求保證粗糙度要求并保證尺寸20及62尺寸無(wú)明顯刀痕,并且保證各面沒有可以刀痕 基準(zhǔn)面 下平面與側(cè)面 材料 同時(shí)加工零件數(shù) 設(shè)備 牌號(hào) 硬度 名稱 型號(hào) HT200 200HBS 1 立式銑床 X52K 夾具 定 額 代號(hào) 名稱 單件時(shí)間（分） 每班次數(shù) 每臺(tái)件數(shù) 工人等級(jí) 工步號(hào) 工步內(nèi)容 走刀長(zhǎng)度(毫米） 走刀次數(shù) 切削深度(毫米） 切削速度（米/秒） 主軸轉(zhuǎn)速（轉(zhuǎn)/分） 進(jìn)給量（毫米/轉(zhuǎn)） 機(jī)動(dòng)時(shí)間（分） 輔助時(shí)間（分） 刀具 輔具 量具 名稱規(guī)格 數(shù)量 名稱規(guī)格 數(shù)量 名稱規(guī)格 粗銑平面,控制尺寸到21與61 40 1 2 1.57 300 0.12 2.21 0.41 高速鋼三面刃圓盤銑刀 1 1 專用量具 精銑平面,控制尺寸到20與60mm 40 1 1 0.4 75 0.08 2.21 0.41 高速鋼三面刃圓盤銑刀 1 1 專用量具 擬制 日期 審核 日期 批準(zhǔn) 日期 共 頁(yè) 第 頁(yè) 機(jī) 械 加 工 工 序 卡 產(chǎn)品型號(hào) 零件名稱 零件號(hào) 傳動(dòng)箱體 工序名稱 鏜上平面孔 工序號(hào) 04 技檢要求 按照?qǐng)D示要求保證粗糙度并保證各孔尺寸,各孔表面沒有明顯可見的刀痕跡,控制各孔的軸之間的同軸度要求 基準(zhǔn)面 下平面與側(cè)面 材料 同時(shí)加工零件數(shù) 設(shè)備 牌號(hào) 硬度 名稱 型號(hào) HT200 200HBS 1 臥式鏜床 夾具 定 額 代號(hào) 名稱 單件時(shí)間（分） 每班次數(shù) 每臺(tái)件數(shù) 工人等級(jí) 工步號(hào) 工步內(nèi)容 走刀長(zhǎng)度(毫米） 走刀次數(shù) 切削深度(毫米） 切削速度（米/秒） 主軸轉(zhuǎn)速（轉(zhuǎn)/分） 進(jìn)給量（毫米/轉(zhuǎn)） 機(jī)動(dòng)時(shí)間（分） 輔助時(shí)間（分） 刀具 輔具 量具 名稱規(guī)格 數(shù)量 名稱規(guī)格 數(shù)量 名稱規(guī)格 1 粗鏜上面各孔,鏜削余量單邊為2mm 8 1 2 2.98 1000 0.2 0.227 2.61 硬質(zhì)合金鏜刀 1 塞規(guī) 2 精鏜上面各孔,鏜削余量單邊為0.5mm 8 1 0.5 3.09 1000 0.15 0.279 1.86 硬質(zhì)合金鏜刀 1 塞規(guī) 擬制 日期 審核 日期 批準(zhǔn) 日期 共 頁(yè) 第 頁(yè) 機(jī) 械 加 工 工 序 卡 產(chǎn)品型號(hào) 零件名稱 零件號(hào) 傳動(dòng)箱體 工序名稱 鏜下平面孔 工序號(hào) 05 技檢要求 按照?qǐng)D示要求保證粗糙度并保證各孔尺寸,各孔表面沒有明顯可見的刀痕跡,控制各孔的軸之間的同軸度要求 基準(zhǔn)面 上平面與側(cè)面 材料 同時(shí)加工零件數(shù) 設(shè)備 牌號(hào) 硬度 名稱 型號(hào) HT200 200HBS 1 臥式鏜床 夾具 定 額 代號(hào) 名稱 單件時(shí)間（分） 每班次數(shù) 每臺(tái)件數(shù) 工人等級(jí) 工步號(hào) 工步內(nèi)容 走刀長(zhǎng)度(毫米） 走刀次數(shù) 切削深度(毫米） 切削速度（米/秒） 主軸轉(zhuǎn)速（轉(zhuǎn)/分） 進(jìn)給量（毫米/轉(zhuǎn)） 機(jī)動(dòng)時(shí)間（分） 輔助時(shí)間（分） 刀具 輔具 量具 名稱規(guī)格 數(shù)量 名稱規(guī)格 數(shù)量 名稱規(guī)格 粗鏜下面各孔,鏜削余量單邊為2mm 18 1 2 1.75 600 0.2 0.96 2.61 硬質(zhì)合金鏜刀 1 專用塞規(guī) 精鏜下面各孔,鏜削余量單邊為0.5mm 18 1 0.5 3.09 800 0.15 0.224 1.56 硬質(zhì)合金鏜刀 1 專用塞規(guī) 擬制 日期 審核 日期 批準(zhǔn) 日期 共 頁(yè) 第 頁(yè) 機(jī) 械 加 工 工 序 卡 產(chǎn)品型號(hào) 零件名稱 零件號(hào) 傳動(dòng)箱體 工序名稱 鉆上平面M6螺紋底孔 工序號(hào) 06 技檢要求 采用塞規(guī)檢查各孔的尺寸大小,不合格的產(chǎn)品杜決流入下道工序 基準(zhǔn)面 下平面與側(cè)面 材料 同時(shí)加工零件數(shù) 設(shè)備 牌號(hào) 硬度 名稱 型號(hào) 200 200HBS 1 立式鉆床 Z535 夾具 定 額 代號(hào) 名稱 單件時(shí)間（分） 每班次數(shù) 每臺(tái)件數(shù) 工人等級(jí) 工步號(hào) 工步內(nèi)容 走刀長(zhǎng)度(毫米） 走刀次數(shù) 切削深度(毫米） 切削速度（米/秒） 主軸轉(zhuǎn)速（轉(zhuǎn)/分） 進(jìn)給量（毫米/轉(zhuǎn)） 機(jī)動(dòng)時(shí)間（分） 輔助時(shí)間（分） 刀具 輔具 量具 名稱規(guī)格 數(shù)量 名稱規(guī)格 數(shù)量 名稱規(guī)格 1 鉆上面各孔至Φ5 8 1 0.24 900 0.25 0.118 1.77 Φ5的麻花鉆頭 1 專用塞規(guī) 2 攻絲至M6 8 1 0.15 480 0.15 0.05 1.77 M6細(xì)柄機(jī)用絲錐攻螺紋 1 專用塞規(guī) 擬制 日期 審核 日期 批準(zhǔn) 日期 共 頁(yè) 第 頁(yè) 機(jī) 械 加 工 工 序 卡 產(chǎn)品型號(hào) 零件名稱 零件號(hào) 傳動(dòng)箱體 工序名稱 鉆兩側(cè)平面M4螺紋底孔 工序號(hào) 07 技檢要求 采用塞規(guī)檢查各孔的尺寸大小,不合格的產(chǎn)品杜決流入下道工序 基準(zhǔn)面 上平面與側(cè)面 材料 同時(shí)加工零件數(shù) 設(shè)備 牌號(hào) 硬度 名稱 型號(hào) HT200 200HBS 1 Z535 立式鉆床 夾具 定 額 代號(hào) 名稱 單件時(shí)間（分） 每班次數(shù) 每臺(tái)件數(shù) 工人等級(jí) 工步號(hào) 工步內(nèi)容 走刀長(zhǎng)度(毫米） 走刀次數(shù) 切削深度(毫米） 切削速度（米/秒） 主軸轉(zhuǎn)速（轉(zhuǎn)/分） 進(jìn)給量（毫米/轉(zhuǎn)） 機(jī)動(dòng)時(shí)間（分） 輔助時(shí)間（分） 刀具 輔具 量具 名稱規(guī)格 數(shù)量 名稱規(guī)格 數(shù)量 名稱規(guī)格 1 鉆上面各孔至Φ7 18 1 0.33 900 0.25 0.128 0.177 Φ3.5的麻花鉆頭 1 專用塞規(guī) 2 攻絲至M8 18 1 0.15 360 0.15 0.09 0.177 M4細(xì)柄機(jī)用絲錐攻螺紋 1 專用塞規(guī) 擬制 日期 審核 日期 批準(zhǔn) 日期 共 頁(yè) 第 頁(yè) 機(jī) 械 加 工 工 序 卡 產(chǎn)品型號(hào) 零件名稱 零件號(hào) 傳動(dòng)箱體 08 工序名稱 鉆臺(tái)階小孔 工序號(hào) 08 技檢要求 采用塞規(guī)檢查各孔的尺寸大小,不合格的產(chǎn)品杜決流入下道工序 基準(zhǔn)面 上平面與側(cè)面 材料 同時(shí)加工零件數(shù) 設(shè)備 牌號(hào) 硬度 名稱 型號(hào) HT200 200HBS 1 立式鉆床 Z535 夾具 定 額 代號(hào) 名稱 單件時(shí)間（分） 每班次數(shù) 每臺(tái)件數(shù) 工人等級(jí) 工步號(hào) 工步內(nèi)容 走刀長(zhǎng)度(毫米） 走刀次數(shù) 切削深度(毫米） 切削速度（米/秒） 主軸轉(zhuǎn)速（轉(zhuǎn)/分） 進(jìn)給量（毫米/轉(zhuǎn)） 機(jī)動(dòng)時(shí)間（分） 輔助時(shí)間（分） 刀具 輔具 量具 名稱規(guī)格 數(shù)量 名稱規(guī)格 數(shù)量 名稱規(guī)格 1 鉆臺(tái)階面的各個(gè)小孔并用塞規(guī)控制其大小 8 1 0.33 900 0.25 0.128 0.177 Φ7的麻花鉆頭 1 專用塞規(guī) 8 1 0.15 360 0.15 0.09 0.177 Φ9.5的麻花鉆頭 1 專用塞規(guī) 擬制 日期 審核 日期 批準(zhǔn) 日期 共 頁(yè) 第 頁(yè) 機(jī) 械 加 工 工 序 卡 產(chǎn)品型號(hào) 零件名稱 零件號(hào) 傳動(dòng)箱體 工序名稱 鉆箱體側(cè)面兩孔 工序號(hào) 09 技檢要求 采用塞規(guī)檢查各螺紋孔的尺寸大小,不合格的產(chǎn)品杜決流入下道工序 基準(zhǔn)面 下平面 材料 同時(shí)加工零件數(shù) 設(shè)備 牌號(hào) 硬度 名稱 型號(hào) HT200 200HBS 1 立式鉆床 Z535 夾具 定 額 代號(hào) 名稱 單件時(shí)間（分） 每班次數(shù) 每臺(tái)件數(shù) 工人等級(jí) 工步號(hào) 工步內(nèi)容 走刀長(zhǎng)度(毫米） 走刀次數(shù) 切削深度(毫米） 切削速度（米/秒） 主軸轉(zhuǎn)速（轉(zhuǎn)/分） 進(jìn)給量（毫米/轉(zhuǎn)） 機(jī)動(dòng)時(shí)間（分） 輔助時(shí)間（分） 刀具 輔具 量具 名稱規(guī)格 數(shù)量 名稱規(guī)格 數(shù)量 名稱規(guī)格 1 鉆箱體側(cè)面各小孔并用螺紋塞規(guī)控制其大小 8 1 0.25 900 0.25 0.118 1.77 Φ10的麻花鉆頭 專用塞規(guī) 2 攻絲至M6 8 1 0.15 480 0.15 0.05 1.77 Φ16麻花鉆頭 專用塞規(guī) 擬制 日期 審核 日期 批準(zhǔn) 日期 共 頁(yè) 第 頁(yè) 機(jī)械加工工藝過(guò)程卡 產(chǎn)品型號(hào) 零（部）圖號(hào) 共 頁(yè) 產(chǎn)品名稱 零（部）名稱 傳動(dòng)箱體 第 頁(yè) 材料牌號(hào) HT200 毛坯種類 鑄件 毛坯外形尺寸 380×270×106 每毛坯件數(shù) 4000 每臺(tái)件數(shù) 備 注 工序號(hào) 工序名稱 工 序 內(nèi) 容 車 間 工 段 設(shè) 備 工 藝 裝 備 工 時(shí) 準(zhǔn)終 單件 1 鑄造 鑄造 2 時(shí)效 時(shí)效 3 涂底漆 涂底漆 4 銑 粗,精銑上平面至尺寸 X52K立式銑床 專用 5 銑 粗,精銑下平面，保證尺寸與粗糙度達(dá)到1.6 X52K立式銑床 專用 6 銑 粗,精銑側(cè)面及保證尺寸，保證粗糙度達(dá)到1.6 X52K立式銑床 專用 7 鏜 鏜上平面孔圓柱度達(dá)到0.02,粗糙度達(dá)到1.6,并保證孔尺寸 臥式鏜床 專用 8 鏜 鏜下平面孔圓柱度達(dá)到0.02,粗糙度達(dá)到1.6,并保證孔尺寸 臥式鏜床 專用 9 鉆 鉆上平面M6螺紋底孔 Z535立式鉆床 專用 10 鉆 鉆側(cè)面φ16與φ10兩孔 Z535立式鉆床 11 鉆 鉆兩側(cè)平面M4螺紋底孔 Z535立式鉆床 專用 12 鉆 鉆兩側(cè)平面臺(tái)階面各小孔 Z535立式鉆床 專用 13 鉗 鉗工，攻絲各螺紋孔 Z535立式鉆床 專用 14 檢驗(yàn) 檢驗(yàn) 15 入庫(kù) 入庫(kù) 設(shè)計(jì)（日期） 審核（日期） 標(biāo)準(zhǔn)化（日期） 會(huì)簽（日期） 標(biāo)記 處記 更改文件號(hào) 簽字 日期 1ApplicationApplicationApplicationApplication andandandand developmentdevelopmentdevelopmentdevelopmentOfOfOfOf casecasecasecase basedbasedbasedbasedreasoningreasoningreasoningreasoning ininininfixturefixturefixturefixturedesigndesigndesigndesignAbstract:Abstract:Abstract:Abstract: Based on the case baseddesigning(CBD)methodology,thefixture similarity is in two respects: thefunction and the structure information.Then, the computer aided fixture designsystemiscreatedoncasebasedreasoning (CBR),in which the attributesof the main features of workpiece andstructure of fixture as case index codeare designed for the retrieve of thesimilar cases, and the structure andhierarchical relation of case library aresetupforstore.Meanwhile,thealgorithmbasedontheknowledgeguided in the retrieve of the similarcases, the strategy of case adapt at ionand case storage in which the case identif cat ion number is used to distinguishfrom similar cases are presented. Theapplicationofthesysteminsomeprojects improves the design efficiencyand gets a good result .Keywords:Keywords:Keywords:Keywords:casebasedreasoning;fixturedesign;computeraided design(CAD)Fixtures are devices that serveas the purpose of holding the workpiecesecurelyandaccurately,andmaintaining a consistent relationshipwithrespecttothetoolswhilemachining.Becausethefixturestructure depends on the feature of theproduct and the status of the processplanning in the enterprise, its design isthe bottleneck during manufacturing,whichrestrainstoimprovetheefficiency and leadtime. And fixture2design is a complicated process, basedonexperiencethatneedscomprehensive qualitative knowledgeaboutanumberofdesignissuesincludingworkpiececonfiguration,manufacturing processes involved, andmachining environment. This is also avery time consuming work when usingtraditionalCADtools(suchasUnigraphics, CATIA or Pro/E), whichare good at performing detailed designtasks, but provide few benefits fortaking advantage of the previous designexperience and resources, which areprecisely the key factors in improvingthe efficiency. The methodology of casebasedreasoning(CBR)adaptsthesolution of a previously solved case tobuild a solution for a new problem withthe following four steps: retrieve, reuse,revise, and retain 1. This is a moreuseful method than the use of an expertsystemtosimulatehumanthoughtbecause proposing a similar case andapplying a few modifications seems tobe self explanatory and more intuitivetohumans.Sovariouscasebaseddesignsupporttoolshavebeendevelopedfornumerousareas2-4,such as in injection molding and design,architectural design, die castingdiedesign, process planning, and also infixture design. Sun used six digitals tocompose the index code that includedworkpieceshape,machineportion,bushing, the 1stlocating device, the 2ndlocating device and clamping device5.But the system cannot be used for otherfixture types except for drill fixtures,and cannot solve the problem of storageof the same index code that needs to beretained, which is very important inCBR6.1 Construction of a Case Index and3Case Library1.1 Case indexThecaseindexshouldbecomposedofallfeaturesoftheworkpiece,whicharedistinguishedfrom different fixtures. Using all ofthem wouldmake the operation inconvenient. Because the forms of theparts are diverse, and the technologyrequirementsofmanufacture intheenterprise also develop continuously,lots of features used as the case indexwill make the search rate slow, and themainfeatureunimportant,forthereason that the relative weight which isallotted to every feature must diminish.And on the other hand, it is hard toinclude all the features in the caseindex.Therefore,consideringthepracticality and the demand of rapiddesign, the case index includes both themajor feature of the workpiece and thestructure of fixture. The case index codeis made up of 16 digits: 13 digits forcase features and 3 digits for caseidentification number.The first 13 digits represent 13features. Each digit is corresponding toan attribute of the feature, which maybe one of“*”, “？”, “1”, “2”,“A” , “B” , “Z” , etc. In which,“*” means anyone, “?” uncertain,“0” nothing.The system rules: fixture type,workpiece shape, locating model cannotbe “*”or“?”. When the system isdesigned, the attribute information ofthe three items does not have theseoptions,whichmeansthecertainattribute must be selected.The last three digits are the caseidentification number, which means the13 digits of the case feature are the4same, and the number of these threedigits is used for distinguishing them.The system also rules: “000”is aprototypecase,whichisusedforretrieval, and other cases are “001”,“ 002 ” ,which are used forreferencecasestobesearchedbydesigners. If occasionally one of themneeds to be changed as the prototypecase, first it must be required to applyto change the one to “000”, and theformer is changed to referential caseautomatically.The construction of the case indexcode is shown in Fig.1.1.2 Case libraryThe case library consists of lots ofpredefined cases. Case representation isone of the most important issues in casebased reasoning. So compounding withthe index code,.1.3 Hierarchical form of CaseThestructuresimilarityofthefixture is representedas the wholefixture similarity, components similarityand component similarity. So the wholefixture case library, components caselibrary,componentcaselibraryoffixtureareformedcorrespondingly.Usuallydesigninformationofthewhole fixture is composed of workpieceinformation and workpiece procedureinformation, which represent the fixturesatisfyingthespecificallydesigningfunction demand. The whole fixturecase is made up of function components,which are described by the functioncomponentsnames and numbers. Thecomponentscaserepresentsthemembers.(functioncomponentand5other structure components ，maindriven parameter, the number, and theirconstrain relations.)The componentcase (the lowest layer of the fixture) isthe structure of function component andothercomponents.Inthemodernfixturedesigntherearelotsofparametric standard parts and commonnon standard parts. So the componentcaselibraryshouldrecordthespecification parameter and the way inwhich it keeps them.2 Strategy of Case RetrievalInthecasebaseddesignoffixtures ,the most important thing is theretrieval of the similarity, which canhelp to obtain the most similar case, andto cut down the time of adaptation.According to the requirement of fixturedesign, the strategy of case retrievalcombinesthewayofthenearestneighbor and knowledge guided. That is,first search on depth, then on breadth;the knowledge guided strategy means tosearch on the knowledge rule from rootto the object, which is firstly searchedby the fixture type, then by the shape ofthe workpiece, thirdly by the locatingmethod. For example, if the case indexcode includes the milling fixture offixture type, the search is just for allmillingfixtures,thenforboxofworkpiece shape, the third for 1plane+2pine of locating method. If there is nomatch of it, then the search stops ondepth, and returns to the upper layer,and retrieves all the relative cases onbreadth.Retrieval algorithms:1)Accordingtothecaseindexinformationoffixturecaselibrary,search the relevant case library;2)Match the case index code withthe code of each case of the case library,6and calculate the value of the similaritymeasure;3)Sorttheorderofsimilaritymeasure, the biggest value, which is themost analogical case.Similarity between two cases isbased on the similarity between the twocases.features.Thecalculationofsimilarity measure depends on the typeof the feature. The value of similaritycan be calculated for numerical values,for example, compareWorkpiece withthe weight of 50kg and 20kg. The valuecan also be calculated between nonnumerical values, for example, now thefirst 13 digits index code is all nonnumericalvalues.Thesimilaritymeasure of a fixture is calculated asfollows:where S is the similarity measureof current fixture, n is the number of theindex feature,is the weight of eachfeature,is the similaritymeasure of the attributeof the i2thfeature with the attributeof relativefeature of the j-th case in the caselibrary.Atthesametime, the value countsas follows:.Whereis the value of the indexattribute of the i-th feature, andis7the value of attribute of the relative i-thfeature of the j-th case in case library.So there are two methods to selectthe analogical fixture. One is to set thevalue.Ifthevaluesofsimilaritymeasure of current cases were less thana given value, those cases would not beselected as analogical cases. When thecase library is initially set up, and thereare only a few cases, the value can besetsmaller.Iftherearelotsofanalogical cases, the value should getlarger. The other is just to set thenumber of the analogical cases (suchas10), which is the largest value ofsimilaritymeasurefromthesortedorder.3CaseadaptationandCaseStorage3.1 Case adaptationThemodificationoftheanalogical case in the fixture designincludes the following three cases:1) The substitution of componentsand the component;2) Adjustingthedimensionofcomponents and the component whilethe form remains;3) The redesign of the model.If the components and componentof the fixture are common objects, theycan be edited, substituted and deletedwith tools, which have been designed.3.2 Case storageBefore saving a new fixture case inthecase library, the designermustconsider whether the saving is valuable.Ifthecasedoesnotincreasetheknowledge of the system, it is notnecessary to store it in the case library.If it is valuable, then the designer mustanalyzeitbefore savingittoseewhetherthecaseisstoredasaprototype case or as reference case. A8prototype case is a representation thatcan describe the main features of a casefamily. A case family consists of thosecases whose index codes have the samefirst 13 digits and different last threedigits in the case library. The last threedigits of a prototype case are always“000” . A reference case belongs to thesame family as the prototype case andis distinguished by the different lastthree digits.From the concept that has beenexplained, the following strategies areadopted:1) If a new case matches anyexisting case family, it has the samefirst 13 digits as an existing prototypecase, so the case is not saved because itis represented well by the prototypecase. Or is just saved as a referencecase (the last 3 digits are not “000”,and not the same with others) in thecase library.2) If a new case matches anyexisting case family and is thought tobebetteratrepresentingthiscasefamily than the previous prototype case,then the prototype case is substituted bythisnewcase,andthepreviousprototype case is saved as a referencecase.3) If a new case does not matchany existing case family, a new casefamily will be generated automaticallyand the case is stored as the prototypecase in the case library.4ProcessofCBRinFixtureDesignAccording to the characteristics offixture design, the basic information ofthe fixture design such as the name offixture, part, product and the designer,etc. must be input first. Then the fixturefile is set up automatically, in which all9componentsofthefixtureareputtogether.Thenthemodeloftheworkpiece is input or designed. Thedetailedinformationabouttheworkpiece is input, the case index codeis set up, and then the CBR begins tosearch the analogical cases, relying onthe similarity measure, and the mostanalogicalcaseisselectedout.Ifneeded, the case is adapted to satisfythe current design, and restored into thecaselibrary.Theflowchartoftheprocess is shown in Fig.3.5 Illustrating for Fixture Design byCBRThis is a workpiece (seeFig.4). Itsmaterial is 45# steel. Its name is seat.Its shape is block, and the product batchsize is middle, etc.Afixture is turningfixture that serves to turn the hole,which needs to be designed.The value of feature, attribute,case index code and weight of theworkpiece is show n in Tab.2.10Through searching, and calculatingthe similarity, the case index code of themostsimilarcaseis19325513321402000, and the detailedinformation is show n in Tab. 3.The similarity is calculated asfollows:So the value of similarity measureofthefixturewhichneedstobedesigned with the most analogical caseincaselibraryis0.806,andthestructure of the most analogical case isshown in Fig.5.After having been substituted thecomponent,modifiedthelocatingmodel and clamp model, and adjustedthe relative dimension, the new fixtureis designed, and the figure is show n in11Fig.6.As there is not the analogicalfixture in the case library, the newfixture is restored in to the case library.Thecaseindexcodeis19325513311402000.6 ConclusionCBR,asaproblemsolvingmethodology,isamoreefficientmethodthananexpertsystemtosimulate human thought, and has beendevelopedinmanydomainswhereknowledge is difficult to acquire. Theadvantages of the CBR are as follows:itresembleshumanthoughtmoreclosely; the building of a case librarywhichhasselflearningabilitybysaving new cases is easier and fasterthan the building of a rule library; and itsupportsabettertransferandexplanation of new knowledge that ismore different than the rule library.Aproposed fixture design framework onthe CBR has been implemented byusing Visual C +, UG/Open API in Un graphics with Oracle as databasesupport, which also has been integratedwiththe32Dparametriccommoncomponentlibrary,commoncomponents library and typical fixturelibrary.Theprototypesystem,developed here, is used for the aviationproject, and aids the fixture designers toimprove the design efficiency and reuseprevious design resources.