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模具工業(yè)是國民經(jīng)濟的基礎工業(yè),是國際上公認的關鍵工業(yè),工業(yè)發(fā)達國家稱之為“工業(yè)之母”。模具成型具有效率高,質(zhì)量好,節(jié)省原材料,降低產(chǎn)品成本等優(yōu)點。采用模具制造產(chǎn)品零件已成為當今工業(yè)的重要工藝手段。模具在機械,電子,輕工,紡織,航空,航天等工業(yè)領域里,已成為使用最廣泛的工業(yè)化生產(chǎn)的主要工藝裝備,它承擔了這些工業(yè)領域中60%--80%產(chǎn)品零件,組件和部件的加工生產(chǎn)。“模具就是產(chǎn)品質(zhì)量”,“模具就是經(jīng)濟效益”的觀念已被越來越多的人所認識和接受。在中國,人們已經(jīng)認識到模具在制造業(yè)中的重要基礎地位,認識更新?lián)Q代的速度,新產(chǎn)品的開發(fā)能力,進而決定企業(yè)的應變能力和市場競爭能力。在目前用薄鋼板制造發(fā)動機罩蓋的傳統(tǒng)還是會持續(xù)相當一段時間,所以有必要在鋼板的基礎上通過利用計算機軟件的功能分析零件的工藝性能(結(jié)構(gòu)合理,受力,是否容易沖出破面、、、),發(fā)現(xiàn)現(xiàn)有零件的不足之處,討論并確定改進這些不足之處,進而改善模具的設計,改良沖裁方式;最終實現(xiàn)產(chǎn)品的改良,改善產(chǎn)品的力學性能,外觀,使用效果,和造價等等。沖壓加工是通過模具來實現(xiàn)的,從模具角度來看,模具生產(chǎn)技術水平的高低,已成為衡量一個國家產(chǎn)品制造水平高低的重要標志,因為模具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。“模具是工業(yè)生產(chǎn)的基礎工藝裝備”也已經(jīng)取得了共識。據(jù)統(tǒng)計,在電子、汽車、電機、電器、儀器、儀表、家電和通信等產(chǎn)品中,60%~80%的零部件都要依靠模具成形。用模具生產(chǎn)制件所具備的高精度、高復雜程度、高一致性、高生產(chǎn)率和低消耗,是其他加工制造方法所不能比擬的。同時,沖壓加工也創(chuàng)造了巨大的價值增值,模具是“效益放大器”,用模具生產(chǎn)的最終產(chǎn)品的價值,往往是模具自身價值的幾十倍、上百倍。目前全世界模具年產(chǎn)值約為600億美元,日、美等工業(yè)發(fā)達國家的模具工業(yè)產(chǎn)值已超過機床工業(yè),從1997年開始,我國模具工業(yè)產(chǎn)值也超過了機床工業(yè)產(chǎn)值。其中沖壓模具在所有模具(鍛造模、壓鑄模、注塑模等)中,無論從數(shù)量、重量或者是從價值上都位居榜首。
由此可見,板料沖壓加工及其模具制造技術對國民經(jīng)濟的發(fā)展已經(jīng)并將繼續(xù)作出重大的貢獻。隨著我國經(jīng)濟的發(fā)展,對這種生產(chǎn)技術的發(fā)展及專業(yè)技術人才的需求將與日俱增。因此,加強對板料沖壓加工及其模具制造技術的研究,具有重要的意義。
現(xiàn)狀和發(fā)展趨勢:經(jīng)過了100多年的發(fā)展,目前小型汽車發(fā)動機的罩殼的設計技術已經(jīng)相當成熟的了,但是隨著各式各樣的小型發(fā)動機的開發(fā),發(fā)動機的前后罩也做了很大的改進。現(xiàn)在,對小型汽車發(fā)動機的罩殼的改進主要表現(xiàn)在對其構(gòu)造材料的改進;例如用樹脂基復合材料替代傳統(tǒng)的薄鋼板,用 RTM制造 發(fā)動機水箱、隔熱罩、發(fā)動機罩等等,由于用復合材料來取代原有金屬的發(fā)動機殼體類零件,重量會有所減輕,且成本也將大大降低,對制造商而言,這個改進創(chuàng)造了很大了利潤空間,所以這方面的技術進步還會持續(xù)相當長一段時間。就目前而言,我國沖壓模具還存在許多問題,其中模具生產(chǎn)周期、質(zhì)量和數(shù)量仍舊是關鍵。與國際水平相比,一般來說,我國沖壓模具生產(chǎn)周期要比國外先進水平長、壽命約相差一倍、精度差距也較大。數(shù)量的不足主要反映在大型、精密、復雜、長壽命模具上。存在這些問題的主要原因是:1)行業(yè)結(jié)構(gòu)(如企業(yè)組織結(jié)構(gòu)、產(chǎn)品結(jié)構(gòu)、技術結(jié)構(gòu)和進出口結(jié)構(gòu)等)不合理: 2)企業(yè)綜合素質(zhì)欠佳、設計制造水平較低、開發(fā)能力弱、管理較落后;3 )模具人才嚴重不足 ;4)資金投入不夠;5)專業(yè)化、標準化、商品化程度低,協(xié)作差:6)模具材料及相關技術落后;7)模具生產(chǎn)企業(yè)的效率和效益較低,等等。
柳州天隆機械有限公司所用的沖壓模具還比較落后,利用沖壓模具沖出的零件質(zhì)量也不是很高,經(jīng)常有起皺,尺寸和形狀精度不高,壽命短等缺陷。同時,在排樣時的不合理更造成原材料的浪費。這些因素無不影響著公司產(chǎn)品質(zhì)量和效益的提高。歸及以上原因主要是由于模具設計得不夠合理,考慮得不夠周全等所造成的。其次不合理的工藝設計也是造成零件質(zhì)量不高的原因。工藝設計是聯(lián)接產(chǎn)品設計與制造的橋梁和紐帶,合理的成形工藝設計是模具設計與制造的基礎,也是決定零件能否順利成形的關鍵,它將直接關系到產(chǎn)品的質(zhì)量、成本、生產(chǎn)效率以及模具的使用壽命等方面。在現(xiàn)在這個科技突飛猛進的時代里,模具設計技術同樣也是在快速的發(fā)展著。模具技術未來發(fā)展趨勢主要是朝信息化、高速化生產(chǎn)與高精度化發(fā)展。
而如今的市場經(jīng)濟,競爭又十分激烈,要想在市場中站得住腳,那么就必須不斷的提高自己設計模具的水平,使自己設計出來的沖壓模具更合理,沖出來的零件質(zhì)量,尺寸和形狀精度,壽命以及資源利用率都能得到大幅度的提高,進而才能提高公司的效益和競爭力。
1.2 選題背景
1.2.1 近年來沖壓成形工藝與理論的研究成果
近年來,沖壓成形工藝有很多新的進展,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,沖壓件的精度日趨精確,生產(chǎn)率也有極大提高,正在把沖壓加工提高到高品質(zhì)的、新的發(fā)展水平。
由于引入了CAE,沖壓成形已從原來的對應力應變進行有限元等分析而逐步發(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)化設計。在沖壓毛坯設計方面也開展了計算機輔助設計,可以對排樣或拉深毛坯進行優(yōu)化設計。
此外,對沖壓成形性能和成形極限的研究,沖壓件成形難度的判定以及成形預報等技術的發(fā)展,均標志著沖壓成形以從原來的經(jīng)驗、實驗分析階段開始走上由沖壓理論指導的科學階段,使沖壓成形走向計算機輔助工程化和智能化的發(fā)展道路。
方案:作為沖壓件要大略了解它的沖壓性能的好或者差,用個人的經(jīng)驗或者視覺的判斷就可以了,但是在要求量化的條件下,最好莫過于用機械相關的板料分析軟件;我使用DYNAFORM來對沖壓件分析。從分析的圖象的顏色可以判斷沖壓條件是否惡劣,給出的列表數(shù)據(jù)可以清楚得知道,拉伸的情況。依據(jù)它給出的信息,我們可以對沖壓件作出相應的改進。最后重點放在模具的設計上來。
大體步驟:
1.用CAE軟件(DYNAFORM)分析,并討論現(xiàn)有零件的工藝性(沖壓性能)
?2.改進零件的部分外形,和加強筋分布。
?3.用FASTBLANK展料,并排樣,選出最佳排樣方案。
?4.進行相關運算,得出相關數(shù)據(jù)。描繪出大體輪廓。
?5.利用上面所得數(shù)據(jù),使用UG畫出模具3維圖(數(shù)模)。
6.利用上述數(shù)模 討論具體零件工藝和相關方案。
?7.利用 AUTOCAD或CAXA繪制模具相關部件2維圖。
?8.寫課題說明書。
沖壓工藝過程的優(yōu)劣,決定了沖壓件制造技術的合理性、沖壓件的質(zhì)量和產(chǎn)品成本。因此必須對沖壓件進行詳盡的工藝分析,分析沖壓件的結(jié)構(gòu)、性能及加工難易程度,確定科學的、合理的工序方案。并在保證產(chǎn)品的設計要求、滿足使用條件的情況下盡量減少工序,采用適宜的材料,盡量節(jié)約用料,選擇先進且合理的加工技術,力求生產(chǎn)工藝過程簡單易行,以降低生產(chǎn)成本,提高經(jīng)濟效益。
模具CAE技術就是在設計制造模具之前,在計算機上模擬出沖壓件在模具中成形的真實過程,向用戶告知模具結(jié)構(gòu)設計、工藝條件狀況是否合理,并最終為用戶提供出最佳的模具設計工藝方案,可靠性達到80%以上。從而縮短模具設計與制造周期2/5(對于復雜模具而言),并提高模具質(zhì)量和產(chǎn)品合格率,進而可大幅度降低制造成本,增強產(chǎn)品的市場競爭力。
國內(nèi)模具與國外模具的差距
當前,我國工業(yè)生產(chǎn)的特點是產(chǎn)品品種多、更新快和市場競爭激烈。在這種情況下,用戶對模具制造的要求是“交貨期短”、“精度高”、“質(zhì)量好”、“價格低”。
而供需兩旺是近幾年來我國模具市場的總體表現(xiàn),2004年仍舊是這個格局。由于汽車、機電等工業(yè)的發(fā)展增幅回落,再加上原材料漲價,能源緊張,電力供應不足,資金周轉(zhuǎn)不暢和運費增加,所以2004年模具市場在供需兩旺的情況下,發(fā)展增幅也有所回落。2005年相比,預計要回落5個百分點以上。
在歐美,CAD/CAE/CAM已成為模具企業(yè)普遍采用的技術。在CAD方面,目前3D設計也達到了70%~89%。澳大利亞3D設計已達到60%,而我國只是剛剛起步。CAE技術在歐美應用逐漸成熟。在沖模設計中應用CAE軟件,模擬金屬變形過程,分析應力應變的分布,預測破裂、起皺和回彈等缺陷,我國只有少部分企業(yè)開始CAE技術的應用。
DL圖(沖壓工藝過程圖)設計的過程中,在沖壓工藝分析、沖壓方向的確定和工序劃分方面我國與國外水平接近。但在工藝補充面的設計和產(chǎn)品數(shù)模的工藝處理方面還存在著較大的差距,如過拉延部分的設計,回彈值的處理等方面國外具有豐富的經(jīng)驗,特別是在高精度轎車零件的工藝設計方面與國外相比仍存在著很大的差距。
高速切削是以高切削速度、高進給速度和高加工質(zhì)量為主要特征的加工技術。在國外已是比較成熟的技術,型面加工精度≤0.05mm,不需要研合間隙。修邊模刃口間隙由機加工保證;鉗裝不需要研配間隙,加工后可直接裝配合模。而國內(nèi)的模具鉗工工作量仍較大。
國內(nèi)的加工機床性能基本與國外設備相當,但在NC技術參數(shù)方面,走刀路徑、方式及技術的設計方面仍存在著差距。
另外在模具制造周期、質(zhì)量方面和標準化程度方面也存在著較大的差距。
第二章 沖壓工藝過程設計
沖壓工藝過程的優(yōu)劣,決定了沖壓件制造技術的合理性、沖壓件的質(zhì)量和產(chǎn)品成本。因此必須對沖壓件進行詳盡的工藝分析,分析沖壓件的結(jié)構(gòu)、性能及加工難易程度,確定科學的、合理的工序方案。并在保證產(chǎn)品的設計要求、滿足使用條件的情況下盡量減少工序,采用適宜的材料,盡量節(jié)約用料,選擇先進且合理的加工技術,力求生產(chǎn)工藝過程簡單易行,以降低生產(chǎn)成本,提高經(jīng)濟效益。
模具CAE技術就是在設計制造模具之前,在計算機上模擬出沖壓件在模具中成形的真實過程,向用戶告知模具結(jié)構(gòu)設計、工藝條件狀況是否合理,并最終為用戶提供出最佳的模具設計工藝方案,可靠性達到80%以上。從而縮短模具設計與制造周期2/5(對于復雜模具而言),并提高模具質(zhì)量和產(chǎn)品合格率,進而可大幅度降低制造成本,增強產(chǎn)品的市場競爭力。
隨著現(xiàn)代生產(chǎn)制造的需要,新產(chǎn)品開發(fā)設計、制造的質(zhì)量和周期已成為企業(yè)在市場經(jīng)濟中能夠生存發(fā)展的重要決定性因素之一。計算機輔助設計(CAD)及制造(CAM)技術的推廣應用,不僅將產(chǎn)品開發(fā)的設計者們從繁重的手工制圖方式中解脫出來,同時,對加工制造業(yè)而言應該是一次巨大的革命性飛躍。然而,在并行工程CE (ConcurrentEngineering)的概念提出和應用前,產(chǎn)品的CAD /CAM/CAE/CAPP由于分屬不同部門的工作內(nèi)容,產(chǎn)品的設計、制造、分析是在自上而下的串行設計中完成的,很顯然,針對并行設計,前者在整個設計過程中受到不能及時更新的約束,很難做到產(chǎn)品開發(fā)制造集成同步實現(xiàn),增加了開發(fā)周期和生產(chǎn)成本。公司完成的“國家863/CIMS主題”重大應用項目并行工程, 通過在新產(chǎn)品開發(fā)CAD/CAM/CAE過程中的實施,體現(xiàn)了良好的應用前景。其中,PRO/E三維設計系統(tǒng)在產(chǎn)品開發(fā)過程中沖壓模具的并行全相關參數(shù)化設計已得到很好的應用。
近年來,隨著計算機綜合應用技術的迅速發(fā)展,計算機集成制造系統(tǒng)(CIMS)、并行工程(CE)、虛擬生產(chǎn)(VM)等一系列新技術將機械工程制造業(yè)帶進了一個嶄新的生產(chǎn)過程模式。有關資料統(tǒng)計表明,我國在863/CIMS應用推廣過程中,相關企業(yè)均獲得了明顯的經(jīng)濟和社會效益,在提高生產(chǎn)效率,降低成本、縮短產(chǎn)品周期、提高質(zhì)量方面的成
績尤為突出。
“并行工程”就其意義而言是一個復雜的系統(tǒng)過程,它解決如何有效的將產(chǎn)品開發(fā)設計、工藝準備過程、制造、過程管理、經(jīng)營銷售等過程合理的組織,實現(xiàn)獲得最佳的產(chǎn)品周期和成本。幾年來,公司并行工程項目的啟動和實施,在不同部門的協(xié)同應用實施仍處于不斷探索驗證的階段,其中,沖壓模具并行設計已經(jīng)基本形成了較為完善的過程框架,對于模具設計制造過程,并行設計的根本實現(xiàn)必須由核心CAD/CAM/CAE軟件的支持,作為并行工程的設計系統(tǒng)平臺,公司引進了美國PTC公司的PRO/ENGINEER作為CAD/CAM 軟件平臺,而沖壓成形數(shù)值模擬分析則引進了專業(yè)CAE分析系統(tǒng)DYNAFORM,在模具展開設計前和過程中,對于模具結(jié)構(gòu)設計意圖的關鍵要素利用PRO/E建模并通過標準數(shù)據(jù)格式提交給DYNAFORM 進行計算分析,預測可行性干預改進模具結(jié)構(gòu)相關參數(shù)。另外,在模具的制造上可以實現(xiàn)在PR0/E內(nèi)部的CAD/CAM無縫轉(zhuǎn)接,從而不僅可以完全體現(xiàn)模具設計意圖、避免工程圖紙的信息損失,還能夠大大縮短制造周期。PRO/ENGINEER在設計過程中可以利用參數(shù)設置、關系(Relations)、參考(Reference)管理實現(xiàn)全相關(Dependency)參數(shù)化設計,換言之,在模具設計的過程中,設計產(chǎn)品的任何變化都將傳遞到模具所有相關的結(jié)構(gòu)件上并按照結(jié)構(gòu)設計意圖自動更新。這大大提高了模具設計的效率,支持設計的反復性,高效率的進行設計更新。PRo/ENGINEER提供了一套方法和各種工具構(gòu)成了一個相對完善的Top-Down Design的環(huán)境,Top—Down Design是指在結(jié)構(gòu)設計中的一種組織方式,其實,不單純在PRo/E環(huán)境下,以往在手工及二維設計過程中也體現(xiàn)了它的宗旨。Top—Down Design的主題思想是以圍繞核心設計意圖進行關聯(lián)式展開設計。模具并行設計的實現(xiàn)一般按以下6個步驟來完成:
(1)模具設計者參與提取產(chǎn)品設計過程中確定產(chǎn)品或原型產(chǎn)品的模型要素,接受或自行完成已經(jīng)具備最終產(chǎn)品全部特點的建模。
(2)對產(chǎn)品進行工藝分析,以Top-Down De—sign方式規(guī)劃確定模具重要結(jié)構(gòu)件的層級骨架(Skeletions)組織設計過程。
(3)在Pro/E系統(tǒng)中圍繞產(chǎn)品沖壓加工建立核心組件模型,并根據(jù)工藝需要確定結(jié)構(gòu)參數(shù),轉(zhuǎn)換數(shù)據(jù)格式提交沖壓CAE分析軟件DYN 刪進行可靠性分析計算。
(4)在Pro/E系統(tǒng)中進行模具設計。由于準備隨時接受來自設計部門的變更及分析結(jié)果的干預進行設計更新,需要利用建模結(jié)構(gòu)、順序、參照控制、特征間關系、元件間關系、組件間關系有效的保證整個模型的可靠性,如當產(chǎn)品局部變更時,相應凸凹模、定位元件、固定板、上下模板結(jié)構(gòu)特征等必須保證成功的再生(Regenerate)。
(5)模具結(jié)構(gòu)設計完成后,輸出二維工程圖?;诠こ虉D與三維建模的全相關性,無論在設計過程中還是在今后都可確保模具局部結(jié)構(gòu)變化后工程圖自動及時準確的更新。
(6)同時提交模具的CAM 部門進行工藝分析及編程。Pro/E系統(tǒng)CAD/CAM 的無縫連接,使得NC程序同樣可以得到更新.
沖模在裝配前應根據(jù)沖模的結(jié)構(gòu)特點和技術要求,確定合理的裝配順序和裝配方法。沖模裝配之后,必須在生產(chǎn)條件下進行試沖,沖出的工件按沖壓零件產(chǎn)品圖或試樣進行檢查驗收。如果發(fā)現(xiàn)不合格者,必須對沖模進行適當?shù)恼{(diào)整和修理,然后再試沖,直到生產(chǎn)合格的沖件為止。在沖模工作一段時間后,可采用超前維修。沖模的受力只局限于刃口的附近在使用一段時間以后,刃口處會不可避免地出現(xiàn)不均勻磨損和磨損溝痕,如果提前維修,可避免因凸、凹模間隙不均勻而產(chǎn)生附加彎矩和防止磨損溝痕產(chǎn)生裂紋,以提高模具壽命。
實踐證明,并行參數(shù)化設計技術在工藝準備過程中的應用,大幅度降低了產(chǎn)品周期,增強了設計的可靠性,同時為企業(yè)取得了巨大的經(jīng)濟效益和社會效益??梢灶A見,計算機立用技術將在生產(chǎn)過程中發(fā)揮更力Ⅱ重要的作用,并已漸漸成為現(xiàn)代制造業(yè)的—個重要特征。
Mold industry is the foundation of the national economy; it is recognized as the key industry in the world; and it is also regarded as "the mother of the industry" in the developed countries. Molding has many advantages, such as high efficiency, good quality, economizing on raw materials, reducing the cost of the production. Manufacturing the components of the productions by molding now has become an important technological method in the industry. In the machinery, electronics, light industry, textile, aviation, aerospace and other industrial areas, molding has become the most widely used main technical equipment of the industrialized production, which undertakes the processing and production task of 60% - 80% of the product components, elements and parts in these industrial fields. The concepts that "Mold is the product quality" and "Mold is the economic-effect" have been realized and received by more and more people. In China, people have recognized the important foundation of the molding in the manufacturing industry and they have realized that the management of the crisis and the market competiveness of the enterprises depend on the speed of replacement, new product development capabilities. Currently the tradition of manufacturing the engine hood by the thin steel plates will still be last quite some time, so it is necessary to analysis the technological properties, such as the reasonable structure, the force, whether it is easy to break out the surface, on the basis of the steel plate by computer software, to find the shortcomings of the ready components, discuss and determine the improvement of these deficiencies and thus improve the mold design and the stamping method, and to realize eventually the product improvement on the mechanical properties, appearance, the results of the usage and the cost and so on. Stamping processing is achieved by the mold. From the point of mold, the level of mold production technology has become the important symbol of measuring that of the country's manufacturing, because on a large extent the mold determines the capability of product quality, effectiveness and new product development. People have known that "mold industry is the basis processes and equipment of the industrial production". According to the statistics, in the products of electronics, automobile, electrical machinery, electrical appliances, instruments, meters, home appliances and communications, 60% ~ 80% of the parts are shaped by the molds. The characteristics of high-precision, high-complexity, high-consistency, high-productivity and low-consumption, which are acquired by the mold production, are incomparable with the other manufacturing methods. In addiction, the stamping process can create great added value. The mold is "the amplifier of the value"; the value of the final production made by the mold is often higher than that of the own mold dozens, or even hundreds. Nowadays, the value of the global mold annual outputting is about 60 billion U.S. dollars, and the output value of the mold industry has surpassed that of the machine tool industry in Japan, the United States and the other industrialized countries. Since 1997, China's output value of the mold industry has also exceeded that of the machine tool industry. Among all the molds (forging mold, die casting mold, injection mold, etc.), no matter the quantity, weight or the value of the stamping die is on the top one.
Thus, sheet metal stamping and processing and the mold production technology have made and will continue make a great contribution to the development of the national economy. With the development of China’s economy, the needs to the technology development and the technical professionals will be rising. Therefore, it is significantly important to strength the research of sheet metal stamping and processing and the mold production technology.
Current Situation and Development Trends: After the 100 years’ development, it has already been mature that the design technology of the engine of the hood of the small-size vehicle. However, with the exploitation of the all kinds of small sized engine, a lot of improvements have been done on the front and the rear hood of the engines. In the current period, the improvements of the hood of the small-size automobile’s engine are mainly manifested in the improvement of the construction materials, for example, replace the traditional thin steel plate with the resin-based composite materials and make with the engine water tank, the heat shield and the engine cover, etc. by RTM. As with composite materials replace the original metal shell type of engine parts, the weight will be reduced, and the cost will be greatly reduced; for manufacturers, this creates a great deal of profit, so the technical progress is also will continue for a long period of time. As far as it goes, there are still many problems in the China’s stamping die, and among these problems, the mold production cycle, quality and quantity are still the keys. Compared to the international standards, in general, the productive cycle of China’s stamping die is longer, the lifespan is shorter twice and there is a wide gap of the accuracy. The lack of quantity is mainly reflected on the large-scale, sophisticated, complex, long-life mold. The main reasons of these problems are the following: 1) the irrational industry structure (such as enterprise organizational structure, product structure, technical structure and import and export structure, etc.) 2) the weakness of the comprehensive character of the enterprise, the level of design and production, the ability of development and the management; 3) the serious shortage of the qualified personnel; 4) the shortage of the capital; 5) the low level of the specialization, standardization and commercialization and the bad collaboration: 6) the outmoded mold materials and related skill; 7) the low efficiency and benefits of the mold manufacturing enterprises, etc..
The stamping dies used by Tian Long Machinery Company Ltd., Liuzhou still relatively fall behind, so the components made by the stamping dies are with the shortcomings that they are of low quality, low accuracy of the size and shape and short lifespan, and they often wrinkle. Additionally, the irrational nesting may lead to the waste of raw materials. The reasons above are mainly due to the unreasonable mold design and the incomplete consideration. What’s more, the unreasonable process design is the reason of the low quality of the components. Process design is the bridge and link between the production design and manufacture. Reasonable forming process design is the basis of mold design and manufacture, and it is also the key that whether the component can form smoothly; it is related directly to the quality, cost, efficiency of the production, and the mold’s lifespan and so on. In the present era, the technology developing rapidly, the technology of mold design is also in the fast developing. The tendency of the mold technology in the future is the development towards the information technology, high-speed production and precision of the development.
Nowadays, competition is very intense in the market economy. In order to prevail in the market, the level of the design must be continually improved so that the stamping dies are more reasonable and the quality, size, shape accuracy, lifespan and resource utilization of the components are can be greatly enhanced, which can improve the company's efficiency and competitiveness.
1.2 Background of the topic
1.2.1 The Research Results of the of Metal Forming Technology and Research Results in Recent Years
In recent years, stamping forming process there are many new advances, especially in precision stamping, precision molding, precision cutting, composite materials, forming, super plastic forming, soft-casting and the electromagnetic forming of new technology with each passing day, increasing the accuracy of precision stamping parts productivity is also greatly improved, is to improve the stamping process to high-quality, new level of development.
Since CAE is introduced, the stamping process has developed to computer simulation and analysis process from making finite element analysis by the pairs of stress and strain in order to achieve optimal design. What’s more, the computer-aided design has also been launched in the stamping blank design to draw on the blank layout to optimize the design.
The research on the performance of the metal stamping and forming and the limits of forming, as well as the determination on the difficulty of the stampings forming and the developing on the techniques of forming forecasting, shows that the stamping and forming begins to enter the scientific stage guided by the stamping theory from the stage of analyzing the original experience and experiments; these all help the technology of stamping and forming go to the development of stamping and intelligent computer-aided engineering.
Program: As a stamping press, its rough performance, good or bad, can be the judged by personal experience or vision, but under the conditions of requiring the quantization, people would better use the sheet metal analysis software associated with the mechanism; and I use DYNAFORM to analysis the stamping parts. The color of the images in the analysis can determine that the conditions of the pressing, and we can know clearly the stretching situation by the list of data. Based on information given, we can improve correspondingly the stampings. Finally we should focus on the mold design up.
General steps:
1. Analyzing by using CAE software (DYNAFORM), and discussing the manufacturability of the existing parts (stamping performance)
2. Improving some parts shape, and strengthening the tendons distribution
3. Exhibition of materials by FASTBLANK, stock layout, and selecting the best layout program
4. Making calculations, getting the associated data and depicting the general outline
5. Draw the three-dimensional mold chart (DAC) by the use of the data above and UG
6. Discussing the specific parts technology and related programs according to the model
7. Drawing the two-dimensional map of the die of the related components by AUTOCAD or CAXA.
8. Writing the topic statement.
The pros and cons of the process of stamping process determine the rationality of the stamping parts manufacturing technology, the stamping parts quality and the cost of the production. Therefore the stamping parts must be made a thorough process analysis and by analyzing the structure, performance and the difficulty level of the stamping parts to choose the scientific and rational processes program. And to ensure the product design requirements, minimize the process, we could adopt the appropriate materials, save the materials, select the advanced and reasonable processing technology, and strive to the simple production process to reduce the production costs and improve the economic efficiency.
Mold CAE technology is the one which simulates the real process of the stamping die forming on the computer before the design and manufacture of molds, informs the user that whether the die structure design and the process conditions are reasonable and ultimately provides users with the best mold design process program. The reliability of this technology is more than 80%. By using the technology the design and manufacturing cycle can be reduced by 2 / 5 (for complex mold case) and improve the mold quality and product qualification rate which can significantly reduce the manufacturing cost and enhance the product market competition.
Gap between the Domestic and Foreign Mold
At present, the characteristics of China's industrial production are production variety, quick updates, and the fierce market competition. In this case, the requirements of the users for mold manufacturing are "the short delivery time", "high precision", "good quality", and "low prices".
That the supply and demand are both booming is the general display of China’s mold market in recent years, and in 2004 this pattern remains. As the growth rate of the automotive, mechanical and electrical industries drops, the price of the raw material rises, the energy and the electricity is in the shortage, the capital is not enough to go round and the transportation expense is on the rise, in 2004 the growth rate of the mold market falls back, although the supply and demand condition is flourishing. The condition in 2005 is expected to be down 5 percentage points compared to 2004.
In Europe and the United States, CAD / CAE / CAM have become a widely used technology in the mold enterprise. Presently the mature level of the 3D design of CAD has reached 70% ~ 89%, and Australian 3D design 60%, while China is only just on the beginning. The Application of CAE technology in Europe and the United States has been mature. In China, only few enterprises put CAE technology which can simulate of metal deformation process, analyze the distribution of stress and strain to predict rupture, forecast the defects such as cracking, wrinkling and springback in the use during the stamping die design.
In the DL Chart (stamping process diagram) design process, the stamping process analysis, the choosing of the direction of stamping and the division of the processes are close to those of foreign countries. However, there is a wide gap on the design of the additional surface in process and product processing, for example,