墊片落料翻邊復合模具設計【套蓋沖壓模具設計】
墊片落料翻邊復合模具設計【套蓋沖壓模具設計】,套蓋沖壓模具設計,墊片落料翻邊復合模具設計【套蓋沖壓模具設計】,墊片,落料翻邊,復合,模具設計,沖壓
學校中期檢查表學生姓名學 號指導教師選題情況課題名稱墊片落料翻邊復合模難易程度偏難適中偏易工作量較大合理較小符合規(guī)范化的要求任務書有無開題報告有無外文翻譯質(zhì)量優(yōu)良中差學習態(tài)度、出勤情況好一般差工作進度快按計劃進行慢中期工作匯報及解答問題情況優(yōu)良中差中期成績評定:所在專業(yè)意見: 負責人: 2014年 4月 16日 學校任務書系 部: 專 業(yè): 學生姓名: 學 號: 設計題目: 墊片落料翻邊復合模 起 迄 日 期: 指 導 教 師: 2013 年 11 月 8 日任 務 書1本設計課題來源及應達到的目的:本設計題目為墊片落料翻邊復合模設計,通過對本塑件的模具設計,對沖壓模結(jié)構(gòu)有一定的掌握,能熟悉沖壓模設計的一般流程,能熟練使用相關(guān)設計手冊,撰寫相應的設計說明書。同時能熟練應用有關(guān)軟件繪制零件圖和總裝圖,編制典型零件的加工工藝規(guī)程。2本設計課題任務的內(nèi)容和要求(包括原始數(shù)據(jù)、技術(shù)要求、工作要求等):原始數(shù)據(jù):產(chǎn)品名稱:墊片材料:Q245生產(chǎn)批量:大批量生產(chǎn)設計任務:(1)了解目前國內(nèi)外沖壓模具的發(fā)展現(xiàn)狀;(2)分析墊片的沖壓成形工藝并確定其工藝方案;(3)沖壓設備的選用及校核;(4)模具的整體設計,繪制模具總裝圖與拆畫非標準件零件圖;(5)編寫設計說明書一份;(6)編制主要零件加工工藝過程卡。所在專業(yè)審查意見:負責人: 年 月 日系部意見:系領(lǐng)導: 年 月 日墊片翻邊落料復合模第一章 概論日常生產(chǎn)、生活中所使用到的各種工具和產(chǎn)品,大到機床的底座、機身外殼,小到一個胚頭螺絲、紐扣以及各種家用電器的外殼,無不與模具有著密切的關(guān)系。模具的形狀決定著這些產(chǎn)品的外形,模具的加工質(zhì)量與精度也就決定著這些產(chǎn)品的質(zhì)量。因為各種產(chǎn)品的材質(zhì)、外觀、規(guī)格及用途的不同,模具分為了鑄造模、鍛造模、壓鑄模、沖壓模等非塑膠模具,以及塑膠模具。 隨著科學技術(shù)的進步和工業(yè)生產(chǎn)的迅速發(fā)展,沖壓加工技術(shù)的應用愈來愈廣泛,模具成形已成為當代工業(yè)生產(chǎn)的重要手段。1.2沖壓模地位及我國沖壓技術(shù) 1.2.1沖壓模相關(guān)介紹 冷沖壓:是在常溫下利用沖模在壓力機上對材料施加壓力,使其產(chǎn)生分離或變形,從而獲得一定形狀、尺寸和性能的零件的加工方法。 沖壓可分為五個基本工序:沖裁、彎曲、拉深、成形和立體壓制。 沖壓模具:在冷沖壓加工中,將材料(金屬或非金屬)加工成零件(或半成品)的一種特殊工藝裝備,稱為冷沖壓模具(俗稱冷沖模)。 沖壓模按照工序組合分為三類:單工序模、復合模和級進模。 復合模與單工序模相比減少了沖壓工藝,其結(jié)構(gòu)緊湊,面積較小;沖出的制件精度高,工件表面較平直,特別是孔與制件的外形同步精度容易保證;適于沖薄料,可充分利用短料和邊角余料;適合大批量生產(chǎn),生產(chǎn)率高,所以得到廣泛應用,但模具結(jié)構(gòu)復雜,制造困難。 沖壓模具是沖壓生產(chǎn)必不可少的工藝裝備,是技術(shù)密集型產(chǎn)品。沖壓件的質(zhì)量、生產(chǎn)效率以及生產(chǎn)成本等,與模具設計和制造有直接關(guān)系。模具設計與制造技術(shù)水平的高低,是衡量一個國家產(chǎn)品制造水平高低的重要標志之一,在很大程度上決定著產(chǎn)品的質(zhì)量、效益和新產(chǎn)品的開發(fā)能力。 1.2.2沖模在現(xiàn)代工業(yè)生產(chǎn)中的地位 在現(xiàn)代工業(yè)生產(chǎn)中,沖模約占模具工業(yè)的50%,在國民經(jīng)濟各個部門,特別是汽車、航空航天、儀器儀表、機械制造、家用電器、石油化工、輕工日用品等工業(yè)部門得到極其廣泛的應用。據(jù)統(tǒng)計,利用沖模制造的零件,在飛機、汽車、電機電器、儀器儀表等機電產(chǎn)品中占60%70%,在電視機、錄音機、計算機等電子產(chǎn)品中占80%以上,在自行車、手表、洗衣機、電冰箱、電風扇等輕工產(chǎn)品中占85%以上。在各種類型的汽車中,平均一個車型需要沖壓模具2000套,其中大中型覆蓋件模具300套。1.2.3我國沖壓模具市場情況 我國沖壓模具無論在數(shù)量上,還是在質(zhì)量、技術(shù)和能力等方面都已有了很大發(fā)展,但與國發(fā)經(jīng)濟需求和世界先進水平相比,差距仍很大,一些大型、精度、復雜、長壽命的高檔模具每年仍大量進口,特別是中高檔轎車的覆蓋件模具,目前仍主要依靠進口。一些低檔次的簡單沖模,已趨供過于求,市場竟爭激烈。 據(jù)中國模具工業(yè)協(xié)會發(fā)布的統(tǒng)計材料,2004年我國沖壓模具總產(chǎn)出約為220億元,其中出口0.75億美元,約合6.2億元. 根據(jù)我國海關(guān)統(tǒng)計資料,2004年我國共進口沖壓模具5.61億美聯(lián)社元,約合46.6億元.從上述數(shù)字可以得出2004年我國沖壓模具市場總規(guī)模約為266.6億元.其中國內(nèi)市場需求為260.4億元,總供應約為213.8億元,市場滿足率為82%.在上述供求總體情況中,有幾個具體情況必須說明:一是進口模具大部分是技術(shù)含量高的大型精密模具,而出口模具大部分是技術(shù)含量較低中的中低檔模具,因此技術(shù)含量高的中高檔模具市場滿足率低于沖壓模具總體滿足率,這些模具的發(fā)展已滯后于沖壓件生產(chǎn),而技術(shù)含量低的中低檔模具市場滿足率要高于沖壓模具市場總體滿足率;二是由于我國的模具價格要比國際市場低格低許多,具有一定的竟爭力,因此其在國際市場前景看好,2005年沖壓模具出口達到1.46億美元,比2004年增長94.7%就可說明這一點;三是近年來港資、臺資、外資企業(yè)在我國發(fā)展迅速,這些企業(yè)中大量的自產(chǎn)自用的沖壓模具無確切的統(tǒng)計資料,因此未能計入上述數(shù)字之中。 我國沖模工業(yè)不能滿足國內(nèi)經(jīng)濟需要的原因主要有:1.專業(yè)化和標準化程度低。2.模具品種少,效率低,經(jīng)濟效益也差。3.制造周期長,模具精度不高,制造技術(shù)較落后。4.模具壽命短,新材料使用量不到10%。力量分散,管理落后。但改革開放以來,在國家產(chǎn)業(yè)政策和與之配套的一系列國家經(jīng)濟政策的支持和引導下,尤其是國民經(jīng)濟的高速發(fā)展,大大地提高了模具的商品化程度,推動了模具技術(shù)和模具工業(yè)的迅速發(fā)展,在CAD/CAM/CAE的運用、加工工藝手段、沖壓件質(zhì)量及模具性能方面,均已達到或接近國際水平。1.2.4 沖壓模具水平狀況 近年來,我國沖壓模具水平已有很大提高。大型沖壓模具已能生產(chǎn)單套重量達50多噸的模具。為中檔轎車配套的覆蓋件模具內(nèi)也能生產(chǎn)了。精度達到12m,壽命2億次左右的多工位級進模國內(nèi)已有多家企業(yè)能夠生產(chǎn)。表面粗糙度達到Ra1.5m的精沖模,大尺寸(300mm)精沖模及中厚板精沖模國內(nèi)也已達到相當高的水平。 1. 模具CAD/CAM技術(shù)狀況 我國模具CAD/CAM技術(shù)的發(fā)展已有20多年歷史。由原華中工學院和武漢733廠于1984年共同完成的精神模CAD/CAM系統(tǒng)是我國第一個自行開發(fā)的模具CAD/CAM系統(tǒng)。由華中工學院和北京模具廠等于1986年共同完成的冷沖模CAD/CAM系統(tǒng)是我國自行開發(fā)的第一個沖裁模CAD/CAM系統(tǒng)。上海交通大學開發(fā)的冷沖模CAD/CAM系統(tǒng)也于同年完成。20世紀90年代以來,國內(nèi)汽車行業(yè)的模具設計制造中開始采用CAD/CAM技術(shù)。國家科委863計劃將東風汽車公司作為CIMS應用示范工廠,由華中理工大學作為技術(shù)依托單位,開發(fā)的汽車車身與覆蓋模具CAD/CAPP/CAM集成系統(tǒng)于1996年初通過鑒定。在此期間,一汽和成飛汽車模具中心引進了工作站和CAD/CAM軟件系統(tǒng),并在模具設計制造中實際應用,取得了顯著效益。1997年一汽引進了板料成型過程計算機模擬CAE軟件并開始用于生產(chǎn)。 21世紀開始CAD/CAM技術(shù)逐漸普及,現(xiàn)在具有一定生產(chǎn)能力的沖壓模具企業(yè)基本都有了CAD/CAM技術(shù)。其中部分骨干重點企業(yè)還具備各CAE能力。 模具CAD/CAM技術(shù)能顯著縮短模具設計與制造周期,降低生產(chǎn)成本,提高產(chǎn)品質(zhì)量,已成為人們的共識。在“八五”、九五“期間,已有一大批模具企業(yè)推廣普及了計算機繪圖技術(shù),數(shù)控加工的使用率也越來越高,并陸續(xù)引進了相當數(shù)量CAD/CAM系統(tǒng)。如美國EDS的UG,美國Parametric Technology公司 Pro/Engineer,美國CV公司的CADSS,英國DELCAM公司的DOCT5,日本HZS公司的CRADE及space-E, 以色列公司的Cimatron 還引進了AutoCAD CATIA 等軟件及法國Marta-Daravision公司用于汽車及覆蓋件模具的Euclid-IS等專用軟件。國內(nèi)汽車覆蓋件模具生產(chǎn)企業(yè)普遍采用了CAD/CAM技術(shù)/DL圖的設計和模具結(jié)構(gòu)圖的設計均已實現(xiàn)二維CAD,多數(shù)企業(yè)已經(jīng)向三維過渡,總圖生產(chǎn)逐步代替零件圖生產(chǎn)。且模具的參數(shù)化設計也開始走向少數(shù)模具廠家技術(shù)開發(fā)的領(lǐng)域。 在沖壓成型CAE軟件方面,除了引進的軟件外,華中科技術(shù)大學、吉林大學、湖南大學等都已研發(fā)了較高水平的具有自主知識產(chǎn)權(quán)的軟件,并已在生實踐中得到成功應用,產(chǎn)生了良好的效益。 快速原型(RP)傳統(tǒng)的快速經(jīng)濟模具相結(jié)合,快速制造大型汽車覆蓋件模具,解決了原來低熔點合金模具靠樣件澆鑄模具,模具精度低、制件精度低,樣樣制作難等問題,實現(xiàn)了以三維CAD模型作為制模依據(jù)的快速模具制造,它標志著RPM應用于汽車身大型覆蓋件試制模具已取得了成功。 圍繞著汽車車身試制、大型覆蓋件模具的快速制造,近年來也涌現(xiàn)出一些新的快速成型方法,例如目前已開始在生產(chǎn)中應用的無模多點成型及激光沖擊和電磁成型等技術(shù)。它們都表現(xiàn)出了降低成本、提高效率等優(yōu)點。 2. 模具設計與制造能力狀況 在國家產(chǎn)業(yè)政策的正確引導下,經(jīng)過幾十年努力,現(xiàn)在我國沖壓模具的設計與制造能力已達到較高水平,包括信息工程和虛擬技術(shù)等許多現(xiàn)代設計制造技術(shù)已在很多模具企業(yè)得到應用。 雖然如此,我國的沖壓模具設計制造能力與市場需要和國際先進水平相比仍有較大差距。這一些主要表現(xiàn)在高檔轎車和大中型汽車覆蓋件模具及高精度沖模方面,無論在設計還是加工工藝和能力方面,都有較大差距。轎車覆蓋件模具,具有設計和制造難度大,質(zhì)量和精度要求高的特點,可代表覆蓋件模具的水平。雖然在設計制造方法和手段方面基本達到了國際水平,模具結(jié)構(gòu)周期等方面,與國外相比還存在一定的差距。 標志沖模技術(shù)先進水平的多工位級進模和多功能模具,是我國重點發(fā)展的精密模具品種。有代表性的是集機電一體化的鐵芯精密自動閥片多功能模具,已基本達到國際水平。 但總體上和國外多工位級進模相比,在制造精度、使用壽命、模具結(jié)構(gòu)和功能上,仍存在一定差距。 汽車覆蓋件模具制造技術(shù)正在不斷地提高和完美,高精度、高效益加工設備的使用越來越廣泛。高性能的五軸高速銑床和三軸的高速銑床的應用已越來越多。NC、DNC技術(shù)的應用越來越成熟,可以進行傾角加工超精加工。這些都提高了模具面加工精度,提高了模具的質(zhì)量,縮短了模具的制造周期。 模具表面強化技術(shù)也得到廣泛應用。工藝成熟、無污染、成本適中的離子滲氮技術(shù)越來越被認可,碳化物被覆處理(TD處理)及許多鍍(涂)層技術(shù)在沖壓模具上的應用日益增多。真空處理技術(shù)、實型鑄造技術(shù)、刃口堆焊技術(shù)等日趨成熟。激光切割和激光焊技術(shù)也得到了應用。1.2.5我國沖模今后發(fā)展趨勢根據(jù)我國沖模技術(shù)的發(fā)展現(xiàn)狀及存在的問題,今后應朝著如下幾個方面發(fā)展:1.開發(fā)、發(fā)展精密、復雜、大型、長壽命模具。2.加速模具標準化和商品化,以提高模具質(zhì)量,縮短模具制造周期。3.大力開發(fā)和推廣應用模具CAD/CAM技術(shù),提高模具制造過程的自動化程度。4.積極開發(fā)模具新品種、新工藝、新技術(shù)和新材料。5.發(fā)展模具加工成套設備,以滿足高速發(fā)展的模具工業(yè)需要。 1.3總結(jié) 沖壓加工作為一個行業(yè),在國民經(jīng)濟的加工工業(yè)中占有重要的地位。近年來,沖壓成型工藝有了很多新的進展,特別是精密沖裁、精密成形、精密剪切、復合材料成形、超塑性成形、軟模成形以及電磁成形等新工藝日新月異,沖壓件的成形精度日趨精確,生產(chǎn)率有了極大的提高,正把沖壓加工提高到高品質(zhì)、新的發(fā)展水平。由于引入了計算機輔助工程(CAE)沖壓成形已從原來對應力應變進行有限元分析而逐步發(fā)展到采用計算機進行工藝過程的模擬與分析,以實現(xiàn)沖壓過程的優(yōu)化分析設計。計算機在模具領(lǐng)域,包括設計、制造、管理等領(lǐng)域發(fā)揮著越來越重要的作用。 3墊片落料翻邊復合模第二章 工件工藝性分析及方案確定2.1工件工藝性分析2.1.1沖裁工藝性圖2-1 零件圖由零件簡圖2-1可見,該工件的加工涉及到落料、沖孔、翻邊等工序成形。該零件的外徑為80mm,屬于小制件,形狀簡單且對稱,適于沖裁加工。查冷沖壓模具設計與制造表2.3沖壓件內(nèi)、外形所能達到的經(jīng)濟精度,因制件形狀簡單、對稱,沖裁件內(nèi)外形所能達到的經(jīng)濟精度為IT12-IT13。查表2.5孔中心與邊緣距離尺寸公差為0.5mm。查表2.7一般剪切斷面表面粗糙度為3.2m.查冷沖模設計表23,得材料Q235號鋼的力學性能如下表:表2-1 10號鋼的性能抗剪強度310380MPa抗拉強度b375460MPa屈服點s235MPa伸長率25%材料Q235鋼,其沖壓性能較好,孔與外緣的壁厚較大,復合模中的凸凹模壁厚部分具有足夠的強度。2.1.2翻邊工藝性1. 翻邊工件邊緣與平面的圓角半徑r=(13)t2. 翻邊的高度h=61.5r=1.53. 翻邊的相對厚度d/t=31.3(1.72),所以翻邊后有良好的圓筒壁4. 沖孔毛刺面與翻邊方向相反,翻邊后工件質(zhì)量沒大影響。 總體看來:該制件均滿足沖裁工藝性和翻邊工藝性,適于沖裁加工。2.1.3判斷能否一次性翻邊成形由預沖孔公式可以得到翻邊高度H的表達式:H=+0.43r+0.72t (2-1)或H=(1-)+0.43r+0.72t = +0.43r+0.72t若將Kmin帶入上式,則可得到許可的最大翻邊高度HmaxHmax=(1-Kmin)+0.43r+0.72t 其中 D翻邊后的中經(jīng)(mm) Kmin極限翻邊系數(shù) r翻邊圓角半徑(mm) t材料厚度(mm)查冷沖模設計,表7-1低碳鋼圓孔極限翻邊系數(shù) 這里凸模采用圓柱形平底型式 孔的加工方式為沖孔 因 相對厚度d/t=31.3 得Kmin= 0.6 于是Hmax=41/2(1-0.6)+0.431+0.721 =9.35(mm)因工件高度H Zmax Zmin因此在這里采用單配方法加工。對于落料,先做凹模,并以它作為基準配做凸模查互換性與測量技術(shù)基礎表2-4查出其極限偏差為: mm查冷沖模設計表3-5磨損系數(shù) 取X=0.5則 D凹= (5-1)=mm =mm落料凸模的尺寸按凹模尺寸配制,其雙面間隙為0.100.14mm 5.2沖孔刃口尺寸沖孔部分:凹=+0.025mm 凸=-0.02mm |凹|+|凸|=0.025+0.02mm =0.045mm|凹|+|凸|= Zmax Zmin對于采用分別加工時,應保證下述關(guān)系:|凹|+|凸|Zmax Zmin (5-2)但對于形狀復雜或料薄的工件,為了保證凸、凹模間一定的隙值,必須采用配合加工。因此在這里采用還是采用單配方法加工對于沖孔,先做凸模,并以它作為基準配做凹模查互換性與測量技術(shù)基礎表2-4查出其極限偏差為:mm 查冷沖模設計表3-5磨損系數(shù) 取X=0.5則 d凸= (5-3) = = mm沖孔凹模的尺寸按凸模尺寸配制,其雙面間隙為0.100.14mm5.3翻邊工作刃口尺寸5.3.1翻邊間隙 如圖5-1,由于在翻邊過程中,材料沿切向伸長,因此其端面的材料變薄非常嚴重,根據(jù)材料的統(tǒng)一變形情況,翻邊凹模與翻邊凸模之間的間隙應小于原來的材料厚度。 圖5-1 翻邊間隙查冷沖壓模具設計與制造,表5-5平板毛坯翻邊時凸凹模之間的間隙得Z/2=0.85mm5.3.2翻邊刃口尺寸1. 翻邊凸模的刃口尺寸計算查互換性與測量技術(shù)基礎表2-4查出其極限偏差為:mm查冷沖模設計表3-5磨損系數(shù) 取X=0.5則 d凸= (5-4)=2.翻邊凹模的刃口尺寸計算根據(jù)翻邊間隙和翻邊凸模的刃口尺寸來確定翻邊凹模的刃口尺寸D凹= (5-5) = =mm 19墊片落料翻邊復合模第六章 凸模、凹模及凸凹模的結(jié)構(gòu)設計及校核6.1落料凹模結(jié)構(gòu)設計6.1.1最小壁厚沖孔落料復合模的凸凹模其刃口平面與工件尺寸相同,這就產(chǎn)生了復合模的“最小壁厚”問題。沖孔落料復合模許用最小壁厚可按表6-1選取,形式如圖6-1表示,表值為經(jīng)驗數(shù)據(jù)。表6-1 凸凹模最小壁厚a數(shù)值 (單位:mm)部分如下材料厚度0.80.91.01.2最小壁厚2.32.52.73.2最小直徑1518圖61 最小壁厚為了增加凸凹模的強度和減少孔內(nèi)廢料的漲力,可以采用對凸凹模有效刃口以下增加壁厚或?qū)U料反向頂出的辦法如圖61所示。 6.1.2模具材料的選擇從眾多模具材料中選出Cr12Mov鋼,該模具鋼是一種綜合力學性能比碳素工具鋼好的低合金工具鋼,它具有較高的硬度和耐磨性,淬火時變形較小,淬透性很好。由于鋼中含有一定量的釩,細化了晶粒,減小了鋼的過熱敏感性,同時碳化物較細小和分布較均勻。9Mn2V鋼的化學成分和物理性能分別如表6-2和表6-3所示表6-2 Cr12Mov鋼化學成分(GB/T 12992000)W%CSiMnVPS0.850.950.401.702.000.100.250.0300.030表6-3 臨界溫度臨界點Ac1AcmAr1Ar3溫度(近似值)730760655690 表6-4 綜合性能耐磨性耐沖擊性淬火不變形性淬硬深度中等中等好淺紅硬性脫碳敏感性切削加工性差較大較好所以這里不管是凸模、凹模還是凸凹模,材料都選用Cr12Mov鋼這里的落料凹模的熱處理硬度為5860HRC6.1.3確定凹模外形尺寸確定凹模外形尺寸的方法有多種,通常都是根據(jù)零件的材料厚度和排樣圖所確定的凹模型孔壁間最大距離為依據(jù),來求凹模的外形尺寸。凹模的刃口形式,考慮到本例生產(chǎn)批量較大,所以采用刃口強度較高的凹模,故采用階梯形直壁式。凹模的外形一般有矩形與圓形兩種,凹模的外形尺寸應保證凹模有足夠的強度與剛度,凹模的厚度還應考慮修模量。凹模的外形尺寸一般根據(jù)沖材料的厚度和沖裁件的最大外形尺寸來確定。查冷沖模設計,第101頁,凹模厚度和壁厚公式為凹模厚度 H=Kb(15mm) (6-1)式中 K系數(shù),考慮板料厚度的影響b沖裁件的最大外形尺寸凹模壁厚 C=(1.52)H(3040mm) (6-2) 查冷沖模設計,表4-3 系數(shù)K值 因 b=80 mm 取K=0.22故 H=0.2280 =17.6mm C=1.535 =52.5mm 考慮到翻邊高度6mm 和保證H17.6mm,最后取H=35mm凹模形狀簡圖如圖6-2圖6-2 落料凹模6.1.4凹模的強度校核查中國模具設計大典,第三卷,表20.1-18 凹模強度計算公式Hmin= (6-3)式中 Hmin凹模的最小厚度(mm)F沖壓力(N) wp許用彎曲應力(MPa) d、do凹模刃口與支承口直徑(mm)這里F= F落=114296(N) wp= 500MPa d=79.77mm do=80mmHmin= =10.72mm而真實的凹模厚度為35mm,所以凹模的強度滿足要求。6.2凸凹模外形尺寸1.凸凹模的高度落料、翻邊凸凹模的高度滿足翻邊高度和凸、凹模之間安全距離外,還考慮翻邊間隙,保證強度要求,即凸凹模壁厚大于最小壁厚。這里落料、翻邊凸凹模的高度為55mm。2.凸凹模的強度校核Lmax (6-4)式中 Lmax沖孔凸模許用的最大自由長度(mm) E沖孔凸模材料的彈性模量(MPa) d凸?;驔_孔直徑(mm) 沖件材料的抗剪強度(MPa) t沖件材料的厚度(mm)這里E=2.2 MPa d=40mm t=1mm =350 MPa于是Lmax = =6342.6mm而實際的沖孔、翻邊凸凹模厚度為55mm,所以強度完全滿足要求。材料同樣選用Cr12Mov鋼,其熱處理硬度為5860HRC落料、翻邊凸凹模簡圖如圖6-3圖6-3 落料、翻邊凸凹模6.3沖孔凸模外形尺寸1.沖孔凸模的形式采用類似直通式的形式,少了階梯形式的復雜,主要受上頂桿孔和凸模孔的影響,避免出現(xiàn)最小壁厚。2.沖孔凸模的長度沖孔凸模的長度=沖孔凸模固定板的厚度+落料、翻邊凸凹模的高度+超出落料、翻邊凸凹模的2mm則沖孔凸模的長度=18mm +35mm +27mm =80mm 沖孔凸模簡圖如圖6-5圖6-4 沖孔凸模3.強度校核1)凸模穩(wěn)定能力的校核查中國模具設計大典,第三卷,表20.1-10 凸模穩(wěn)定能力校核計算公式Lmax (6-7)式中 Lmax沖孔凸模許用的最大自由長度(mm) E沖孔凸模材料的彈性模量(MPa) d凸?;驔_孔直徑(mm) 沖件材料的抗剪強度(MPa) t沖件材料的厚度(mm)這里E=2.2 MPa d=31.3mm t=1mm =350 MPa于是Lmax = =4390.3mm2)承壓能力的校核k=p (6-8)式中 沖件材料的抗剪強度(MPa) t沖件材料的厚度(mm)d凸?;驔_孔直徑(mm)k凸模刃口的接觸應力(MPa)p凸模材料的許用壓應力(MPa)這里=350 MPa t=1mm d=31.3mm p=1500 MPa則k= = =711.36MPap=1500 MPa即凸模穩(wěn)定能力和承壓能力均滿足要求。第七章 主要零部件設計7.1模柄的設計查中國模具設計大典第3卷,表22.5-24壓入式模柄(JB/T7646.1-1994)選擇B型材料:Q235熱處理硬度:4348HRC模柄簡圖如圖7-1圖7-1 模柄7.2固定板和墊板的設計7.2.1沖孔、翻邊凸凹模固定板的設計查中國模具設計大典第3卷,表22.5-19固定板長寬LXB=160X160mm,厚度H=18mm材料:45 熱處理硬度4348HRC沖孔、翻邊凸凹模固定板的簡圖如圖7-2圖7-2 沖孔、翻邊凸凹模固定板7.2.2沖孔凸模固定板的設計沖孔凸模的固定方式有直接固定在模座、用固定板固定和快換式固定三種固定方式,這里選用固定板固定,且采用臺肩固定。將沖孔凸模壓入固定板內(nèi),裝配采用N7/h6 查中國模具設計大典第3卷,表22.5-19圓形固定板長寬LXB=160X160mm,厚度H=18mm材料:45 熱處理硬度4348HRC沖孔固定板的簡圖如圖7-3圖7-3 沖孔固定板7.2.3墊板的設計查中國模具設計大典第3卷,表22.5-20圓形墊板長寬LXB=160X160mm,厚度H=8mm材料:45 熱處理硬度4348HRC墊板的結(jié)構(gòu)簡圖如圖7-4圖7-4 墊板31第八章 沖壓設備的校核與選定第八章 沖壓設備的校核與選定8.1 沖壓設備的校核該模具的閉合高度由以下零件高度相加之和求的。該模具閉合高度: H閉=H上+H下+H墊+L+H-h (8-1) 式中:L-沖孔凸模長度; H-凸凹模厚度; h-沖孔凸模沖裁后進入凸凹模的深度h=2mm。根據(jù)公式(8-1)得模具的閉合高度為:H閉=H上+H下+H墊+L+H-h =40+50+30+8+53+55-5 =231(mm)可見該模具的閉合高度在所選模具閉合高度之間,則該模架可以使用,該模具的閉合高度小于所選壓力機型號為J23-40的最大閉合高度為330mm,最大裝模高度為265,高度調(diào)節(jié)量為65,可以使用。8.2 沖壓設備的選用根據(jù)模具閉合高度、沖裁力等,壓力機型號為J23-40,能滿足各項要求,因此選取J23-40號壓力機。35第九章 繪制模具總裝圖及零件圖運用Auto CAD軟件,按照上述幾章設計的尺寸,繪制模具裝配總圖及各零件圖??傃b配圖按照0#圖紙繪制,零件圖則按照其它型號的圖紙繪制。圖樣幅面應符合國家(GB4457.1-84)。 先繪制裝配草圖,經(jīng)指導老師認可,才進行正式圖的繪制。繪圖過程中嚴格按照國標制圖標準繪制。9.1裝配圖繪制裝配圖應用足夠說明模具構(gòu)造的投影圖及必要的剖面圖、剖視圖,一般主視圖和俯視圖應對應繪制。還要注明必要尺寸,如模具高度、輪廓尺寸以及裝配保證的有關(guān)尺寸和精度。畫出排樣圖,填寫詳細的零件明細表和技術(shù)要求。裝配結(jié)構(gòu)圖如圖9-1: 圖9-1 模具總裝圖墊片落料翻邊復合模致 謝在近一個學期的努力之后,我的畢業(yè)設計終于完成了。在這幾個月的設計過程中,我遇到了許多的問題,得到了老師和同學的大力幫助,尤其是文秀海輔導老師,他的耐心教導及指點給予了我極大的幫助。在此,對輔導老師的教誨表示衷心的感謝。在這次模具設計課題中,有一定的繪圖工作量。因此,我有不少的圖紙需要老師來指導和檢查。每次答疑時,老師更是仔細、耐心。認真的檢查我的圖紙的每個細節(jié),指出其中的錯誤和不足之處,給我提出很好的改進方案。由于我們不能每時每刻找老師答疑,經(jīng)常與同學進行討論,他們的指點也給我很大的幫助。最后,由衷的感謝老師的悉心指導和熱忱鼓勵,還要感謝幫助過我的同學們。37參考文獻1 任海東、蘇君. 冷沖壓工藝與模具設計.鄭州:河南科學技術(shù)出版社20072 王麗霞、愈佳芝.計算機繪圖.鄭州:河南科學技術(shù)出版社20063 劉家平.機械制圖.鄭州:河南科學技術(shù)出版社20064 Yoshida K, Classification and Systematization of Sheet Metal Press Forming Process Sci. Pap.IPCR.Vol42,No. 1514,1959,1421595 Keeler S.P. Determination of Forming Limit in Automotive Stamping. Sheet Metal Industries,1965 Vol. 42. 6 康寶來、于興芝.機械設計基礎.鄭州:河南科學技術(shù)出版社2006 7 黃云清.公差配合與測量技術(shù).北京:機械工業(yè)出版社2007.1 8 李云程 模具制造工藝學.北京:機械工業(yè)出版社 2007.19 孫鳳勤.沖壓與塑壓設備.北京:機械工業(yè)出版社 2007.810 吳兆祥.模具材料及表面處理.北京:機械工業(yè)出版社 2008.211 許發(fā)越.模具標準應用手冊.北京:機械工業(yè)出版社 199412 王芳.冷沖壓模具設計指導.北京:機械工業(yè)出版社 1998.10 13 李奇.江瑩模具構(gòu)造與制造.北京:青華大學出版社.2004.814 王秀鳳.冷沖壓模具設計與制造.北京:航空航天大學出版社 2005.415 成虹.沖壓工藝與模具設計.北京:高等教育出版社 2006.716 楊玉英,崔令江.實用沖壓工藝及模具設計手冊.機械工業(yè)出版社2005.117 彭建生.模具設計與加工速查手冊. 北京:機械工業(yè)出版社2005.718 徐政坤.沖壓模具及設備. 北京:機械工業(yè)出版社2005.1學校說明書題目: 墊片落料翻邊復合模 系 部 專 業(yè) 班 級 學生姓名 學 號 指導教師 2014年04月20日 插圖清單圖1 零件圖 6圖2 排樣示意圖11圖3 落料凹模21圖4 沖孔凸模23圖5凸凹模固定板26圖6沖孔固定板27圖7墊板28圖8模具總裝圖30表格清單表1 10號鋼的性能6表2 模具性能比較7表3 正裝復合模和倒裝復合模的比較9表4 凸凹模最小壁厚a數(shù)值19表5 臨界溫度20摘 要本次設計了一套沖孔落料、翻邊的復合模模具。經(jīng)過查閱資料,首先要對零件進行工藝分析,經(jīng)過工藝分析和對比,采用沖孔落料翻邊工序,通過沖裁力、頂件力、卸料力等計算,確定模具的類型。得出將設計的模具類型后將模具的各工作零部件設計過程表達出來。在論文中第一部分,主要敘述了沖壓模具的發(fā)展狀況,說明了沖壓模具的重要性,接著是對沖壓件的工藝分析,完成了工藝方案的確定。第二部分,對零件排樣圖的設計,完成了材料利用率的計算。再進行沖裁工藝力的計算和沖裁模工作部分的設計計算,對選擇沖壓設備提供依據(jù)。最后對主要零部件的設計和標準件的選擇,為本次設計模具的繪制和模具的成形提供依據(jù)。通過前面的設計方案畫出模具各零件圖和裝配圖。本模具性能可靠,運行平穩(wěn),能夠適應大批量生產(chǎn)要求,提高了產(chǎn)品質(zhì)量和生產(chǎn)效率,降低勞動強度和生產(chǎn)成本。關(guān)鍵詞:沖壓;復合模;模具結(jié)構(gòu)AbstractThe design of the compound die punching, blanking, a flanging. Through access to information, the first part to process analysis, through process analysis and comparison, the punching flanging die, punching through, the top pieces, such as the discharge of calculation, determine the type of die. The design of the mold type after the working parts mold design process of expression.In the first part, mainly describes the development of stamping dies, illustrates the importance of stamping dies, then stamping process is analyzed to determine the completion of the process plan. The second part, the part layout diagram design, complete the calculation of material utilization. Then the blanking force calculation and design calculation of blanking die working parts, provide the basis for the selection of stamping equipment. Finally the design and standards on the main parts selection, provide the basis for drawing and the mould forming the mold design. The design drawing mold parts drawing and assembly drawing.The die is reliable performance, stable running, able to adapt to the requirement of mass production, improve product quality and production efficiency, reduce labor intensity and production cost.Keywords: punching compound die; die structure機 械 加 工 工 序 卡 工序名稱車工序號02零件名稱落料凹模零件號00-07零件重量同時加工零件數(shù)1材 料毛 坯牌 號硬 度型 號重 量Cr12MoV設 備夾 具名 稱輔 助工 具名 稱型 號車床虎鉗游標卡尺安 裝工 步安裝及工步說明刀 具量 具走 刀長 度走 刀次 數(shù)切 削 深 度進給量主 軸轉(zhuǎn) 速切 削速 度基 本工 時一次1車端面斷面車刀游標卡尺21100/ min800r/min一次1車外圓外圓車刀游標卡尺21100/ min800r/min一次2精車外圓車刀游標卡尺2150/ min11200r/mi一次2切斷切斷刀游標卡尺1150/ min1500r/mi設 計 者指 導 教 師共 1 頁第 1 頁 機 械 加 工 工 藝 過 程 卡 零件號零 件 名 稱00-06落料凹模工序號工 序 名 稱設 備夾 具刀 具量 具工 時名 稱型 號名 稱規(guī) 格名 稱規(guī) 格名 稱規(guī) 格01下料(3075mm)鋸床直尺02車端面車床三角卡盤標準端面車刀游標卡尺03車外圓車床三角卡盤外圓車刀游標卡尺04切槽車床三角卡盤切斷刀游標卡尺05精車車床三角卡盤外圓車刀千分尺06熱處理(滲碳、淬火、低回)電熱爐07磨削磨床砂輪千分尺 編制 鄭勝男 校對 審核 批準 目 錄摘 要I第一章概論11.2沖壓模地位及我國沖壓技術(shù)11.2.1沖壓模相關(guān)介紹11.2.2沖模在現(xiàn)代工業(yè)生產(chǎn)中的地位11.2.3我國沖壓模具市場情況21.2.4 沖壓模具水平狀況31.2.5我國沖模今后發(fā)展趨勢51.3總結(jié)5第二章工件工藝性分析及方案確定62.1工件工藝性分析62.1.1沖裁工藝性62.1.2翻邊工藝性62.1.3判斷能否一次性翻邊成形72.2 工藝方案確定7第三章排樣及計算材料利用率103.1計算預沖孔大小103.2確定排樣方式103.3計算材料利用率11第四章沖裁力及壓力中心計算144.1.落料力F落144.2卸料力F 卸144.3沖孔力F沖144.4頂件力F頂154.5翻邊力F翻154.6總沖壓力F總154.7計算壓力中心15第五章主要工作部分尺寸計算165.1落料刃口尺寸165.2沖孔刃口尺寸165.3翻邊工作刃口尺寸175.3.1翻邊間隙175.3.2翻邊刃口尺寸18第六章凸模、凹模及凸凹模的結(jié)構(gòu)設計及校核196.1落料凹模結(jié)構(gòu)設計196.1.1最小壁厚196.1.2模具材料的選擇196.1.3確定凹模外形尺寸206.1.4凹模的強度校核216.2凸凹模外形尺寸216.3沖孔凸模外形尺寸23第七章主要零部件設計267.1模柄的設計267.2固定板和墊板的設計267.2.1沖孔、翻邊凸凹模固定板的設計267.2.2沖孔凸模固定板的設計277.2.3墊板的設計28第八章沖壓設備的校核與選定298.1 沖壓設備的校核298.2 沖壓設備的選用29第九章繪制模具總裝圖及零件圖309.1裝配圖繪制30致 謝31參考文獻32編號無錫太湖學院畢業(yè)設計(論文)相關(guān)資料題目: 軸承保持架沖壓模具設計 機電 系 機械工程及自動化專業(yè)學 號: 0923181學生姓名: 呂金勇 指導教師: 黃敏(職稱:副教授) 2013年5月25日無錫太湖學院畢業(yè)設計(論文)開題報告 題目: 軸承保持架沖壓模具設計 機電 系 機械工程及自動化 專業(yè)學 號: 0923181 學生姓名: 呂金勇 指導教師: 黃敏 (職稱:副教授) 2012年11月25日 課題來源自擬??茖W依據(jù)(包括課題的科學意義;國內(nèi)外研究概況、水平和發(fā)展趨勢;應用前景等)(1)課題科學意義 隨著與國際接軌的腳步日益放慢,市場競爭的日益加劇,人們對模具的各種要求也不斷的加大.可以說模具制造技術(shù)是用來衡量一個國家工業(yè)發(fā)展水平的重要標志。則現(xiàn)階段的工業(yè)生產(chǎn)中,模具是一種非常重要的工藝裝備。其在各個行業(yè)中也演繹著非常重要的角色,其運用于汽車、機械、航天、航空、輕工、電子、電器、儀表等行業(yè)。在我國的模具行業(yè)中有50%的是沖壓模具,足以看出沖壓模具之重要。所以現(xiàn)階段對于沖壓模具的研究也是非常有必要的。軸承保持架沖壓模具的研究狀況及其發(fā)展前景 隨著計算機技術(shù)的發(fā)展和普及,沖壓模具也基本實現(xiàn)了計算機化,其中使用最多的是cad軟件。抽高壓模具的計算機化也是日益發(fā)展趨勢下不可避免的。近些年來各種多軸數(shù)控機床,激光切割機床數(shù)控雕刻機床等等紛紛面世,這些設備在提高模具的數(shù)量,規(guī)模和制造能力上的作用是不可估量的。還有其中快速成形技術(shù)和快速模具技術(shù)這兩種先進的制造技術(shù)也越來越廣泛的應用于模具行業(yè)。中國的模具行業(yè)每年都保持著25%的增長率,其行業(yè)的生產(chǎn)能力也僅次于美國日本,位列世界第三。其行業(yè)生產(chǎn)能力約占世界總量的10%。然而, 與國際先進水平相比, 中國的模具行業(yè)的差距不僅表現(xiàn)在精度差距大、 交貨周期長等方面, 模具壽命也只有國際先進水平的 50% 左右。大型、精密、技術(shù)含量高的轎車覆蓋件沖壓模具和精密沖裁模具是現(xiàn)階段最需要解決的問題。綜上由于市場需求模具的現(xiàn)階段發(fā)展快速,應用廣其前景也是也是非??春玫摹Q芯績?nèi)容了解沖壓加工的工作原理,國內(nèi)外的研究發(fā)展現(xiàn)狀;完成軸承保持架沖壓模具的總體方案設計;完成有關(guān)零部件的選型計算、結(jié)構(gòu)強度校核及液壓系統(tǒng)設計;熟練掌握有關(guān)計算機繪圖軟件,并繪制裝配圖和零件圖紙,折合A0紙不少于3張;完成設計說明書的撰寫,并翻譯外文資料1篇。擬采取的研究方法、技術(shù)路線、實驗方案及可行性分析沖壓是一種利用壓力加工的方法,就是壓力機上裝上模具對材料施加壓力。使材料分離或者變形形成合格的所需產(chǎn)品。沖壓模具材料的確定是一開始必須要確認的,其次是沖壓模具的結(jié)構(gòu)設計分沖壓工藝的確定和模具結(jié)構(gòu)的設計兩個方面,則需從這兩個方面入手。最后是對模具的壓力計算還有軟件模擬。研究計劃及預期成果研究計劃:2012年11月17日-2013年1月13日:按照任務書要求查閱論文相關(guān)參考資料,填寫畢業(yè)設計開題報告書,學習并翻譯一篇與畢業(yè)設計相關(guān)的英文材料。2013年1月11日-2013年3月5日:指導員實訓。2013年3月8日-2013年3月14日:查閱與設計有關(guān)的參考資料不少于10篇,其中外文不少于5篇,翻譯機械方面的外文資料。2013年3月15日-2013年3月21日:軸承保持架工藝分析。2013年3月22日-2013年4月11日:初步繪制裝配圖和修改完成。2013年4月12日-2013年4月25日:對凹凸模尺寸計算,繪制凹凸模及各零件。2013年4月26日-2013年5月21日:繪制上下模及其各零件,完成設計說明書(論文)、摘要和小結(jié),修改設計說明書開題報告格式,整理所有資料,打印后上交,準備答辯。預期成果。特色或創(chuàng)新之處 沖模的使用便于生產(chǎn)自動化,操作簡單,生產(chǎn)率提高。 減少制作軸承保持架的材料。已具備的條件和尚需解決的問題 已找到大量相關(guān)資料文獻,對軸承保持架零件有相關(guān)認識。 沖壓工藝的加工工序指導教師意見 指導教師簽名:年 月 日教研室(學科組、研究所)意見 教研室主任簽名: 年 月 日系意見 主管領(lǐng)導簽名: 年 月 日英文原文 Stress Analysis of Stamping Dies J. Mater. Shaping Technoi. (1990) 8:17-22 9 1990 Springer-Verlag New York Inc. R . S . R a oAbstract: Experimental and computational procedures for studying deflections, flit, andalignment characteristics of a sequence of stamping dies, housed in a transfer press, are pre-sented. Die loads are actually measured at all the 12 die stations using new load monitors and used as input to the computational procedure. A typical stamping die is analyzed using a computational code, MSC/NASTRAN, based on finite element method. The analysis is then extended to the other dies, especially the ones where the loads are high. Stresses and deflections are evaluated in the dies for the symmetric and asymmetric loading conditions. Based on our independent die analysis, stresses and deflections are found to be reasonably well within the tolerable limits. However, this situation could change when the stamping dies are eventually integrated with the press as a total system which is the ultimate goal of this broad research program. INTRODUCTION Sheet metal parts require a series of operations such as shearing , drawing , stretching , bending , and squeezing. All these operations are carried out at once while the double slide mechanism descends to work on the parts in the die stations, housed in a transfer press 1. Material is fed to the press as blanks from a stock feeder. In operation the stock is moved from one station to the next by a mechanism synchronized with the motion of the slide. Each die is a separate unit which may be independently adjusted from the main slide. An automotive part stamped from a hot rolled steel blank in 12 steps without any intermediate anneals is shown in Figure 1. Transfer presses are mainly used to produce different types of automotive and aircraft parts and home appliances. The economic use of transfer presses depends upon quantity production as their usual production rate is 500 to 1500 parts per hour 2. Although production is rapid in this way, close tolerances are often difficult to achieve. Moreover, the presses produce a set of conditions for off-center loads owing to the different operations being performed simultaneously in several dies during each stroke. Thus, the forming load applied at one station can affect the alignment and general accuracy of the operation being performed at adjacent stations. Another practical problem is the significant amount of set-up time involved to bring all the dies into proper operation. Hence, the broad goal of this research is to study the structural characteristics of press and dies combination as a total system. In this paper, experimental and computational procedures for investigating die problems are presented. The analysis of structural characteristics of the transfer press was pursued separately 3. A transfer press consisting of 12 die stations was chosen for analysis. Typical die problems are excessive deflections, tilt, and misalignment of the upperand lower die halves. Inadequate cushioning and offcenter loading may cause tilt and misalignment of the dies. Tilt and excessive deflections may also be caused by the lack of stiffness of the die bolster and the die itself. Part quality can be greatly affected by these die problems. There are a lot of other parameters such as the die design, friction and lubrication along the die work interface, speed, etc. that play a great role in producing consistently good parts. Realistically, the analysis should be carded out by incorporating the die design and the deforming characteristics of the work material such as the elastic-plastic work hardening properties. In this preliminary study, the large plastic deformation of the workpiece was not considered for the reasons mentioned below. Large deformation modeling of a sheet stretching process was carded out using the computational code based on an elastic-plastic work hardening model of the deformation process 4. Laboratory experiments were conducted on various commercial materials using a hemispherical punch. The coefficient of friction along the punch-sheet interface was actually measured in the experiment and used as a prescribed boundary to the numerical model. Although a good solution was obtained, it was realized that the numerical analysis was very sensitive to the frictional conditions along the interface. In the most recent work, a new friction model based on the micromechanics of the asperity contact was developed 5. In the present problem, there are several operations such as deep drawing, several reduction drawing operations, and coining, which are performed using complex die geometries. The resources and the duration of time were not adequate to study these nonlinear problems. Hence,the preliminary study was limited to die problems basedon linear stress analysis. A detailed die analysis was carried out by using MSC /NASTRAN code based on finite ele mentmethod. Die loads were.measured at all the stations using new load monitors. Such measured data were used in the numerical model to evaluate stresses and deflections in the dies for normal operating conditions and for asymmetric loading conditions. Asymmetric loading conditions were created in the analysis by tilting the dies. In real practice, it is customary to pursue trial-and-error procedures such as placing shims under the die or by adjusting the cushion pressure to correct the die alignment problems. Such time consuming tasks can be reduced or even eliminated using the computational and experimental procedures presented here. DIE GEOMETRY AND MATERIALS The design of metal stamping dies is an inexact process. There are considerable trial-and-error adjustments during die tryout that are often required to finish the fabrication of a die that will produce acceptable parts. It involves not only the proper selection of die materials, but also dimensions. In order to withstand the pressure, a die must have proper cross-sectional area and clearances. Sharp comers, radii, fillets, and sudden changes in the cross section can have deleterious effects on the die life. In this work, the analysis was done on the existing set of dies. The dies were made of high carbon, high chromium tool steel. The hardness of this tool steel material is in the range of Rockwell C 57 to 60. Resistance to wear and galling was greatly improved by coating the dies with titanium nitride and titanium carbide. The dies were supported by several other steel holders made of alloy steels such as SAE 4140. The geometry of a typical stamping die is axisymmetric but it varies slightly from die to die depending on the operation. Detailed information about geometry andmaterials of a reduction drawing die (station number 4) was gathered from blueprints. It was reproducedin three-dimensional geometry using a preprocessor, PATRAN. One quadrant of the die is shown in Figure2. The data including geometry and elastic properties of the die material were fed to the numerical model. The work material used was hot rolled aluminumkilled steel, SAE 1008 A-K Steel and the blank thickness was about 4.5 ram. Stampings used in unexposed places or as parts of some deisgn where fine finish is not essential are usually made from hot rolled steel. The automotive part produced in this die set is a cover for a torque converter. A principal advantage of aluminum-killed steel is its minimum strain aging.EXPERIMENTAL PROCEDURES As mentioned earlier, this research involved monitoting of die loads which were to be used in the numerical model to staldy the structural characteristicsof dies. The other advantage is to avoid overloadingthe dies in practice. Off-center loading can be detected and also set-up time can be reduced. Thus, any changes in the thickness of stock, dulling of the die,unbalanced loads, or overloadings can be detected using die load monitors. Strain gage based fiat load cells made of high grade tool steel material were fabricated and supplied by IDC Corporation. Four identical load cells were embedded in a thick rectangular plate as shown in Figure 3. They were calibrated both in the laboratory and in the plant.The plate was placed on the top of the die. The knockout pin slips through the hole in the plate. Six such plates were placed on each of six dies. In this way,24 readings can be obtained at a given time. Then they were shifted to the other six dies for complete data. All the 12 die loads are presented in Table 1.COMPUTATIONAL PROCEDURES Linear static analysis using finite element method wasused to study the effect of symmetric and asymmetric loading for this problem. A finite element model of die station 4 was created using the graphical preprocessor, PATRAN, and the analysis was carried outusing the code MSC/NASTRA N . The code has a wide T a b l e I. Die LoadsDie Station LoadNumber (kN)1 3562 6413 2144 3565 8546 7127 2858 32O9 234910 113911 21412 2100spectrum of capabilities, of which linear static analysis is discussed here. The NASTRAN code initially generates a structural matrix and then the stiffness and the mass matrices from the data in the input file. The theoretical formulations of a static structural problem by the displacement method can be obtained from the references 6. The unknowns are displacements and are solved for the appropriate boundary conditions. Strains are obtained from displacements. Then they are converted into stresses by using elastic stress-strain relationships of the die material. The solution procedure began with the creation of die geometry using the graphical preprocessor, PATRAN. The solution domain was divided into appropriate hyper-patches. This was followed by the generation of nodes, which were then connected by elements. Solid HEXA elements with eight nodes were used for this problem. The nodes and elements were distributed in such a way that a finer mesh was created at the critical region of the die-sheet metal interface and a coarser mesh elsewhere. The model was then optimized by deleting the unwanted nodes. The element connectivities were checked. By taking advantage of the symmetry, only one quarter of the die was analyzed. In the asymmetric case, half of the die was considered for analysis. Although, in practice, the load is applied at the top of the die, for the purpose of proper representation of the boundary conditions to the computational code, reaction forces were considered for analysis. The displacement and force boundary conditions are shown for the two cases inFigure 4.As mentioned earlier, sheet metal was not modeled in this preliminary research. As shown in Figure 4(a),the nodes on the top surface of the die were constrained (stationary surface) and the measured load of 356 kN was equally distributed on the contact nodes at the workpiece die interface. Similar boundary conditions for the punch are shown in Figure 4(b). It is noticeable that fewer nodes are in contact with the sheet metal due to the die tilt for the asymmetric loading case as shown in Figure 4(c). In real practice, the pressure actually varies along the die contact surface. Since the actual distribution was not known, uniform distribution was considered in the present analysis.DISCUSSION OF RESULTS As described in the earlier section, the numerical analysis of die Station 4 (both the die and punch) was performed using the code MSC/NASTRAN . Two cases were considered, namely: (a) symmetric loading and (b) asymmetric loading Fig. 4. Boundary conditions. (A) Symmetric case (onequadrant of the die). (B) Symmetric case (one quadrant ofnthe punch). (C) Asymmetric case (half of the die).Symmetric Loading Numerical analysis of the die was carried out for a measured load o f 356 kN as distributed equally in Figure 4(a). The major displacements in the loading direction are shown in Figure 5(a). These displacement contours can be shown in various colors to represent different magnitudes. The m aximum displacement value is 0.01 m m for a uniformly distributed load of 356 kN. The corresponding critical stress is very small, 8.4 MPa in the y direction and 30 MPa in the x direction. The calculated displacements and stresses at the surrounding elements and nodes wereof the same order, but they decreased in magnitude at the nodes away from this critical region. Thus, the die was considered very rigid under this loading condition. Symmetric loading was applied to the punch and the numerical analysis was carried out separately. The displacement values in the protruding region of the punch were high compared to the die. The maximum displacement was 0.08 m m . It should be noted that the displacement values in this critical range of the punch were of the same order ranging from 0.05 mm to 0.08 ram. Although the load acting on the punch (bottom half) was the same as the die (upper half), that is, 356 kN, the values of displacements and stresses were higher in the punch because of the differences in the geometry. This is especially true for the protruding part of the punch. The corresponding maxim u m stress was 232 MPa. This part of the punch is still in the elastic range as the yield strength of tool steel is approximately 1034 MPa. The critical stress value might be varied for different load distributions. Since the actual distribution of the load was not known,the load was distributed equally on all nodes. As the die (upper half) is operating in a region which is extremely safe, a change in the load distribution may not produce any high critical stresses in the die. Although higher loads are applied at other die stations(see Table 1), it is concluded that the critical stresses are not going to be significantly higher due to the appropriate changes in the die geometries.Asymmetric Loading For the purpose of analysis, an asymmetric loading situation was created by tilting the die. Thus, only 15 nodes were in contact with the workpiece compared to 40 nodes for the symmetric loading case. As shown in Figure 4(c), a 356 kN load was uniformly distributed over the 15 nodes that were in contact with the workpiece. Although the pressure was high, because of the geometry at the location where the load was acting, the critical values of displacement and stress were found to be similar to the symmetric case. The predicted displacement and stress values were not significantly higher than the values predicted for the symmetric case.Fig. 5. Displacement contours in the loading direction. (A) Symmetric case (one quadrant of thedie). (B) Symmetric case (one quadrant of the punch). (C)Asymmetric case (half of the die).CONCLUSIONS In this preliminary study, we have demonstrated the capabilities of the computational procedure, based on finite element method, to evaluate the stresses and deflections within the stamping dies for the measured loads. The dies were found to be within the tolerable elastic limits for both symmetric and asymmetric loading conditions. Thus the computational procedure can be used to study the tilt and alignment characteristics of stamping dies. In general, the die load monitors are very useful not only for analysis but also for on-line tonnage control. Future research involves theintegration of the structural analysis of stamping dies with that of the transfer press as a total system.ACKNOWLEDGMENTSProfessor J.G. Eisley, W.J. Anderson, and Mr. D.Londhe are thanked for their comments on this paper.REFERENCES1. R.S. Rao and A. Bhattacharya, Transfer Process De-flection, Parallelism, and Alignment Characteristics,Technical Report, January 1988, Department of Mechanical Engineering and Applied Mechanics, the University of Michigan, Ann Arbor.2. Editors of American Machinist, Metalforming: Modem Machines, Methods, and Tooling for Engineers and Operating Personnel, McGraw-Hill, Inc., 1982, pp. 47-50.3. W.J. Anderson, J.G. Eisley, and M.A. Tessmer,Transfer Press Deflection, Parallelism, and Alignment Characteristics, Technical Report, January 1988, Department of Aerospace Engineering, the University of Michigan, Ann Arbor.4. B.B. Yoon, R.S. Rao, and N. Kikuchi, Sheet Stretching: A Theoretical Experimental Comparison, International Journal of Mechanical Sciences, Vol. 31, No.8, pp. 579-590, 1989.5. B.B. Yoon, R.S. Rao, and N. Kikuchi, Experimental and Numerical Comparisons of Sheet Stretching Using a New Friction Model, ASME Journal of Engineering Materials and Technology, in press.6. MSX/NASTRAN, McNeal Schwendler Corporation.22 9 J. Materials Shaping Technology, Vol. 8, No. 1, 1990中文譯文 沖壓模具的受力分析 R.S.Rao J.Mater.Shaping Tec
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