錐形油杯沖壓模具設(shè)計【含13張CAD圖紙和文檔全套】
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第 22 頁 共 23 頁設(shè)計用紙在沖壓過程模擬 - 產(chǎn)品和工藝設(shè)計最新應(yīng)用摘 要 工藝產(chǎn)品和工藝設(shè)計仿真都是目前正在實行產(chǎn)業(yè)。然而,一個變量數(shù)目會對輸入的準確性和計算機預(yù)測的可靠性產(chǎn)生重大的影響。 曾經(jīng)進行一項有關(guān)沖壓模擬能力評估預(yù)測的特點和其工藝條件部分的復(fù)雜形面形成了復(fù)合、工業(yè)零件的研究。在工業(yè)應(yīng)用中,下面是沖壓過程的進行模擬測試達到的兩個目標(biāo):(1)通過分析在產(chǎn)品設(shè)計階段、成形性及預(yù)測來優(yōu)化產(chǎn)品的設(shè)計;(2)在模具設(shè)計的前期階段減少試模時間和在沖壓加工過程中降低生產(chǎn)成本。為了達到這兩個目標(biāo),有兩種方法可以選擇:一種是Pam-Stamp應(yīng)用法,一種是Intl工程系統(tǒng)有限元增量的動態(tài)程序法。很明顯第二個目標(biāo)方法比較好,因為它可以處理的實際沖壓中的大多數(shù)參數(shù)。FAST_FORM3D,一個單步有限元程序的成型技術(shù),匹配第一個目標(biāo),因為它只需零件幾何形狀復(fù)雜的過程,而不是信息。在以往的研究表明,這些兩個沖壓守則也適用于制造汽車和工程機械所使用的復(fù)雜形狀部件。對在沖壓成形性預(yù)測問題的能力進行了評價。本文回顧了這一研究結(jié)果,并總結(jié)了有限元模擬程序所取得結(jié)果的準確性、可靠性。 在另一項研究中,對控制壓邊力(BHF)在半球狀圓頂平底杯拉深中的影響進行了研究。高性能的標(biāo)準汽車材料鋁鎮(zhèn)靜高質(zhì)量鋼(AKDQ),以及如高強度鋼板、烘烤硬鋼、鋁6111等。已經(jīng)確認不同的壓邊力可以改善圓頂杯的應(yīng)變分布。關(guān)鍵詞:沖壓;過程刺激;工藝設(shè)計1.簡介對于形狀復(fù)雜的板材(如汽車覆蓋件金屬沖壓件的設(shè)計過程,包括決策的許多階段)的設(shè)計過程是一個非常昂貴和耗時的過程。在目前的工業(yè)上,許多工程決策是基于工作人員的經(jīng)驗和他們的知識,這些決策通常是經(jīng)過軟工裝模具成型階段和硬模選拔賽驗證階段后才做出的。很多時候軟、硬工具必須重新編制,甚至重新設(shè)計和提供的零件到達可接受的質(zhì)量水平。 現(xiàn)在將最好的設(shè)計過程列在圖1中。在這個設(shè)計過程中,經(jīng)驗豐富的產(chǎn)品設(shè)計人員會使用一個稱為一步有限元法的專門設(shè)計的軟件來估計其設(shè)計成形性。這將使產(chǎn)品的設(shè)計者在確定設(shè)計路線之前,以及昂貴的模具已經(jīng)制造出來之前做必要的修改。一步法有限元法特別適合用于產(chǎn)品分析,因為它不需要粘結(jié)劑、附錄、甚至絕大多數(shù)工藝條件。通常方法不可用在產(chǎn)品設(shè)計階段。一步法有限元法也很容易掌握,計算速度快,這使得設(shè)計人員能夠發(fā)揮“如果”沒有太多的時間投資。 圖- 1 金屬薄板沖壓件的參考設(shè)計過程。 一旦產(chǎn)品已經(jīng)設(shè)計和經(jīng)過驗證,開發(fā)項目將進入“零時間”階段,并傳遞到模具設(shè)計階段。模具設(shè)計人員會確認他們自己的增量有限元程序的有關(guān)設(shè)計并進行必要的設(shè)計變更,甚至優(yōu)化工藝參數(shù),確保不只是最低的可接受的零件質(zhì)量,而是最高達到的質(zhì)量。這增加了產(chǎn)品的質(zhì)量,而且增加過程的成品率。增量有限元法特別適合于模具設(shè)計分析,因為它確實需要粘合劑,附錄,以及已知的模具設(shè)計或渴望被人知道的過程。驗證制造模具的設(shè)計后就會直接進入了艱苦的生產(chǎn)加工和被驗證階段,在此期間,將與物理原型零件對比著進行,試用時間應(yīng)該減少由于先前的數(shù)值驗證。重新設(shè)計和成型,由于不可預(yù)見的問題,再制造模具應(yīng)該是過去的事情。試用時間減少和消除重新設(shè)計/再制造所用的時間應(yīng)該超過彌補進行數(shù)值驗證、試模、加工過程所用的時間。對于薄板沖壓件生產(chǎn)商而言,沖壓工藝的優(yōu)化也是非常重要的。通過適度增加壓力機設(shè)備的投資、并使用模具成型、一個人可以控制多個沖壓過程。據(jù)記載,壓邊力是板料成形過程中最敏感的工藝參數(shù)之一,因此可用于精確控制變形過程。通過控制壓邊力在功能和壓應(yīng)力的位置等有效措施,提高粘結(jié)劑的外圍的應(yīng)變分布的小組提供了新增的強度和剛度,降低了面板和殘余應(yīng)力的回彈程度,提高產(chǎn)品品質(zhì)和穩(wěn)定性。通過控制作為壓應(yīng)力和周圍的粘結(jié)劑邊緣位置的函數(shù)壓邊力,可以提高面板強度和剛度,減少面板回彈和殘余應(yīng)力應(yīng)變分布,提高產(chǎn)品質(zhì)量和過程的穩(wěn)定性。一種廉價的工業(yè)質(zhì)量體系,目前正在制定在緊急救濟協(xié)調(diào)員/ NSM采用了液壓和氮的結(jié)合,如圖2所示。使用壓邊力控制也可以允許工程師設(shè)計更具有侵略性的板窗利用所提供的增加壓邊力控制成形性。 圖2. 壓邊力控制系統(tǒng)和模具正在開發(fā)的ERC / NSM實驗室1.對設(shè)計過程的三個獨立階段研究進行了研究將會在下一節(jié)描述產(chǎn)品的設(shè)計階段,其中一個步驟是有限元程序FAST_FORM3D(成型技術(shù))的驗證,作為實驗室和工業(yè)的一部分,用來預(yù)測毛坯最佳形狀的研究。第4節(jié)總結(jié)了模具的設(shè)計階段,其中一個實際的工業(yè)平板是用來驗證的增量有限元程序的PAM Stamp系統(tǒng)(國際工程系統(tǒng))的研究。第5節(jié)覆蓋了在實驗室研究壓邊力控制應(yīng)變分布在深沖、半球形、圓頂平底杯的影響。2 產(chǎn)品仿真 - 應(yīng)用這項調(diào)查的目的是為了驗證FAST_FORM3D系統(tǒng),確定FAST_FORM3D對毛坯形狀預(yù)測的能力,并確定一步有限元法在產(chǎn)品設(shè)計過程中是怎么實施的。成型技術(shù)提供了他們的一步法有限元代碼和培訓(xùn)中心的FAST_FORM3D / NSM為目的的基準和研究。FAST_FORM3D并不等同于變形歷史。相反,它將項目上一個平面或可展曲面零件幾何形狀和重新定位的最后節(jié)點和元素,直至達到最低能量狀態(tài)。這個過程是計算速度比就像是PAM Stemp的增量模擬,也使得假設(shè)增多。FAST_FORM3D能評價和估計最優(yōu)毛坯矩形件的結(jié)構(gòu),也是一個強有力的工具,產(chǎn)品設(shè)計師由于其速度和使用的安逸性,但是在這時期的幾何是不可用的。為了驗證FAST_FORM3D,我們比較分析其與毛坯形狀預(yù)測預(yù)報方法的毛坯形狀。該零件的幾何形狀如圖3所示是一個長15英寸、寬5英寸、深12英寸有一個1英寸直角法蘭盤英寸。表1列出了工藝條件下使用,圖4顯示了使用Romanovski零件毛坯形狀的實證法和滑移線場的方法來預(yù)測毛坯形狀的原理。 圖. 3 矩形幾何用于FAST_FORM3D驗證表1 為FAST_FORM3D矩形驗證過程中使用參數(shù)圖4。使用手工計算毛坯長方形盤的外形設(shè)計。 (一)Romanovski的經(jīng)驗方法;(二)滑移線場分析方法。圖5(a)給出了預(yù)測從Romanovski法,滑移線場方法,幾何形狀和FAST_FORM3D空白。空白形狀同意在角落里地區(qū),但不同的側(cè)面區(qū)域很大。圖5(二)- (c)顯示抽簽中模式后的矩形繪制過程。平移由Pam-Stemp模擬預(yù)測空白的每個形狀。抽簽中地區(qū)在彎道很好匹配所有三個長方形盤模式。滑移線場方法,雖然沒有達到目標(biāo)區(qū)域在身邊1英寸法蘭,而Romanovski和FAST_FORM3D方法實現(xiàn)了1英寸法蘭在身邊地區(qū)相對較好。此外,只有FAST_FORM3D毛坯同意在角落里/側(cè)過渡區(qū)。此外,F(xiàn)AST_FORM3D毛坯比Romanovski具有較好的應(yīng)變分布和更低的峰值應(yīng)變比,由圖6中可以看到。圖5 各種毛坯形狀預(yù)測和帕姆印花仿真結(jié)果為長方形鍋。 (一)三預(yù)測空白形狀;(二)變形滑移線領(lǐng)域的毛坯;(三)畸形Romanovski毛坯;(四)畸形FAST_FORM3D毛坯圖6 比較應(yīng)變泛用長方形的PAM Stemp形狀分布的各種毛坯。 (一)變形Romanovski毛坯;(二)畸形FAST_FORM3D毛坯。若要繼續(xù)此驗證研究,從小松制作工業(yè)部分被選中,并在圖7(a)所示。我們預(yù)計的一個最優(yōu)幾何FAST_FORM3D空白的實驗裝置,正如所見,毛坯很相似,但有一些差異,最終的零件毛坯形狀,如圖7(b)。圖7 儀器FAST_FORM3D模擬結(jié)果包括最終驗證。 (一)FAST_FORM3D成形性能的比較;(二)預(yù)測與實驗的毛坯形狀比較。接下來,我們模擬了沖壓的毛坯和FAST_FORM3D使用Pam-Stamp實驗毛坯。我們通過比較兩者的計算機輔助設(shè)計(CAD)預(yù)測的零件幾何形狀 (圖8),發(fā)現(xiàn)FAST_FORM3D是更精確的。一個不錯的特征是,FAST_FORM3D能顯示“失敗”的部分情節(jié)的輪廓曲線,對失敗限制示于圖7(A)??傊? FAST_FORM3D在預(yù)測的實驗室和工業(yè)部件的最佳形狀成功的毛坯。這表明,F(xiàn)AST_FORM3D可以成功地用于評估產(chǎn)品設(shè)計成形性的問題。在儀器的覆蓋情況下,審判和錯誤實驗多小時可能被淘汰使用FAST_FORM3D和更好的毛坯形狀可能已經(jīng)開發(fā)出來。圖 8。比較FAST_FORM3D和實驗儀器的零件形狀。 (一)實驗開發(fā)毛坯形狀和CAD幾何;(二)優(yōu)化毛坯形狀和FAST_FORM3D的CAD幾何。3 模具和工藝模擬- 應(yīng)用為了在研究模具設(shè)計過程中緊密合作,一個由日本小松制作所和ERC/ NSM組成的小組。與形成問題的一個生產(chǎn)小組選擇了小松。該面板是挖掘機的駕駛室左側(cè)內(nèi)板,如圖9所示。是的幾何簡化為一個實驗實驗室死亡,同時保持該小組的主要特征。在實驗進行過程中小松使用表2所示的條件。一個成形極限圖(FLD)研制了用于繪圖品質(zhì)采用穹頂鋼和視覺測試應(yīng)變測量系統(tǒng),并在圖10所示。在實驗中使用三壓邊力分別是(10,30,50噸)以確定其效果。每個模擬實驗條件進行了增量在ERC/ NSM使用PAM-Stemp。圖9 挖掘機的駕駛室,左側(cè)內(nèi)板表2機艙內(nèi) 的工藝條件調(diào)查圖10 在機艙內(nèi)調(diào)查所使用的繪圖優(yōu)質(zhì)鋼成形極限圖。在10噸的條件下發(fā)生起皺的實驗部分,如圖11所示。在30噸條件下發(fā)生皺紋被淘汰,如圖12所示。對這些實驗結(jié)果進行了PAM Stemp模擬預(yù)測,如圖13所示。 30噸壓力的測量小組以確定材料畫中的模式。這些測量結(jié)果進行了比較與預(yù)測材料繪制在圖14研究。效果是非常良好,只有10毫米,最大的錯誤。一個輕微的頸部,觀察小組的30噸,如圖13所示。在50噸時,面板上會出現(xiàn)明顯的骨折起皺。圖11 皺褶實驗室機艙內(nèi)板,壓邊力= 10噸圖12 壓邊力=30噸機艙內(nèi)的實驗室和頸縮變形階段。 (一)實驗毛坯;(二)實驗小組,形成了60;(三)實驗小組,完全形成;(四)實驗小組,縮頸細節(jié)。圖13 預(yù)測和在實驗室客艙內(nèi)消除皺紋。 (a)預(yù)期的幾何形狀,壓邊力= 10噸;(二)預(yù)測的幾何形狀,壓邊力= 30噸圖14 在實驗室內(nèi)艙預(yù)測與實測比較所得出的結(jié)果,壓邊力= 30噸。應(yīng)變測量系統(tǒng)測量了每個小組的結(jié)果,其結(jié)果如圖15所示。從每個小組有限元模擬的預(yù)測在圖16所示。這些預(yù)測和測量吻合有關(guān)的應(yīng)變分布,不同的壓邊力對結(jié)果的影響不大。雖然趨勢是代表,壓邊力的影響往往在模擬的壓力更多的本地化的方式相比,測量。然而,這些預(yù)測表明, PAM Stemp正確預(yù)測了頸縮和斷裂在30和50噸時發(fā)生。關(guān)于摩擦應(yīng)變分布的影響進行了研究,如圖17模擬圖所示。圖 15 機艙內(nèi)的實驗室試驗應(yīng)變測量。 (一)測量應(yīng)變,壓邊力= 10噸(面板皺)(二)測量應(yīng)變,壓邊力= 30噸(面板頸);(三)測量應(yīng)變,壓邊力=50噸(面板裂縫)。圖。16。機艙內(nèi)的實驗室應(yīng)變有限元預(yù)測。 (a)預(yù)期的壓力,壓邊力= 10噸;(二)預(yù)測的壓力,壓邊力= 30噸;(三)預(yù)測的壓力,壓邊力= 50噸。圖17 實驗室內(nèi)預(yù)測效應(yīng)摩擦機艙內(nèi),壓邊力= 30噸。 (a)預(yù)期的壓力,=0.06;(二)預(yù)測應(yīng)變,=0.10。它們的比較結(jié)果摘要列于表3中,此表顯示,模擬預(yù)測了在實驗條件下每一株測量系統(tǒng)實驗觀測結(jié)果。這表明,PAM-Stemp可以用來評估成形模具設(shè)計相關(guān)的問題。表3客艙內(nèi)的研究結(jié)果摘要4. 壓邊力控制- 應(yīng)用這次調(diào)查的目的是確定各種高性能材料在半球狀,圓頂平底,深拉杯深沖性能(見圖18),并探討不同時間的變壓邊力上進行了拉伸試驗,以確定這些材料進行分析和模擬輸入到流動應(yīng)力和各向異性特征(見圖 19和表5)。在被調(diào)查的材料包括AKDQ鋼、高強度鋼、烘烤硬鋼、鋁6111(見表4)。圖18 巨形杯模具的幾何形狀表4用于材料研究的圓頂杯圖19 鋁6111,AKDQ,強度高,烤硬鋼的拉伸試驗結(jié)果。 (一)拉伸試樣裂隙;(二)應(yīng)力/應(yīng)變曲線。表5 鋁6111、AKDQ、烤硬鋼的高強度拉伸試驗數(shù)據(jù)值得注意的是流動應(yīng)力和AKDQ烤硬鋼曲線非常類似,但是在5的時候伸長率減少類似烤硬。雖然高強度鋼和鋁6111的伸長率很相似,但是其N值比鋁6111的值大兩倍。此外, AKDQ的R值遠遠大于1,而烤硬接近1,鋁6111遠小于1。在這次調(diào)查中的壓邊力用型材時間變量中包含常數(shù),線性減少,脈動(見圖20)。為AKDQ鋼的實驗條件進行了模擬使用的PAM -Stemp增量代碼。斷裂、皺紋的例子,和良好的實驗室杯圖21所示以及對模擬圖像皺杯。圖20.用于研究剖面圓頂杯的壓邊力時間。 (一)固定壓邊力;(二)斜壓邊力;(三)脈動壓邊力。圖 21。模擬實驗和圓頂杯。 (一)實驗好杯;(b)實驗裂隙杯;(三)實驗皺杯;(四)模擬皺杯對深沖性能進行了實驗研究限制使用固定壓邊力。這項研究的結(jié)果顯示在表6 此表顯示,AKDQ的沖壓性能最大,而鋁的最小而烤硬、高強度鋼的性能中等。對AKDQ的連續(xù)應(yīng)變分布、脈動壓邊力進行了比較實驗圖22,模擬圖23。這兩個模擬和實驗的結(jié)果發(fā)現(xiàn),斜坡的壓邊力軌跡對于提高應(yīng)變分布情況是最好的。不僅減少了骨折的可能性降低峰值高達5,而且還降低應(yīng)變地區(qū)的增加。這種應(yīng)變分布的改善,提高產(chǎn)品的剛度和強度,減少回彈和殘余應(yīng)力,提高產(chǎn)品質(zhì)量和工藝的魯棒性。表6。恒定壓邊力限制的頂燈杯的沖壓性能圖22。時間變量對AKDQ鋼圓頂杯壓邊力變化的實驗圖23。時間變量對AKDQ鋼圓頂杯壓邊力變化的模擬實驗脈動壓邊力在調(diào)查的頻率范圍內(nèi),未發(fā)現(xiàn)有對應(yīng)變分布的影響。這可能是由于這一事實的脈動頻率進行了測試只有1赫茲。從其他研究人員以前的實驗可知,適當(dāng)?shù)念l率范圍是從5到25赫茲。AKDQ從模擬和實驗載荷行程曲線比較圖24所示。良好的協(xié)議被發(fā)現(xiàn)的情況下=0.08。這表明,有限元模擬可以用來評估成形性,可以通過使用壓邊力控制技術(shù)獲得改善。圖24.KDQ穹頂鋼杯的比較實驗與模擬負載沖程曲線5 結(jié)論和未來工作在本文中,我們評價一個復(fù)雜的沖壓件的改進設(shè)計過程中,涉及消除了軟模具相結(jié)合的產(chǎn)品和工藝驗證使用單步和增量有限元模擬。此外,改進工藝,提出了壓邊力控制實施以提高產(chǎn)品質(zhì)量和工藝的魯棒性組成三個獨立的調(diào)查分析,總結(jié)其在設(shè)計過程的各個階段。首先,產(chǎn)品設(shè)計階段進行了調(diào)查與實驗室和一個步驟有限元程序FAST_FORM3D和評估的能力,在產(chǎn)品設(shè)計成形性問題所涉及的工業(yè)驗證。 FAST_FORM3D在預(yù)測中矩形工業(yè)儀表盤和蓋形狀最佳空白成功。在儀器的覆蓋情況下,審判和錯誤實驗多小時可能被淘汰使用FAST_FORM3D和更好的毛坯形狀可能已經(jīng)開發(fā)出來。 其次,模具設(shè)計階段進行了調(diào)查實驗室和增量代碼的PAM Stemp系統(tǒng)的工業(yè)驗證和評估的能力,形成與模具設(shè)計有關(guān)的問題。這項調(diào)查表明,PAM的郵票可以預(yù)測應(yīng)變分布,起皺,頸縮和斷裂,至少一個遠景以及應(yīng)變各種條件下的實驗測量系統(tǒng)。 最后,工藝設(shè)計階段的調(diào)查,對質(zhì)量可與壓邊力控制技術(shù)的實現(xiàn)實現(xiàn)改善的實驗研究。在此調(diào)查,半球狀,圓頂平底高峰株,杯子的拉伸值都被減少了5,從而減少了皺折的可能性,并降低了應(yīng)變區(qū)強度。這種應(yīng)變分布的改善,提高產(chǎn)品的剛度和強度,減少回彈和殘余應(yīng)力,提高產(chǎn)品質(zhì)量和工藝的穩(wěn)定性??梢灶A(yù)計,深沖性能將會在不斷優(yōu)化的壓邊力中逐漸增強。此外,在實驗測量和數(shù)值模擬預(yù)測中發(fā)現(xiàn)負載行程曲線,表明有限元模擬可以用來評估成形性,可控制壓邊力技術(shù),使用得到改善。 1模具在工業(yè)生產(chǎn)中的地位模具是大批量生產(chǎn)同形產(chǎn)品的工具,是工業(yè)生產(chǎn)的主要工藝裝備。采用模具生產(chǎn)零部件,具有生產(chǎn)效率高、質(zhì)量好、成本低、節(jié)約能源和原材料等一系列優(yōu)點,用模具生產(chǎn)制件所具備的高精度、高復(fù)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。已成為當(dāng)代工業(yè)生產(chǎn)的重要手段和工藝發(fā)展方向?,F(xiàn)代經(jīng)濟的基礎(chǔ)工業(yè)?,F(xiàn)代工業(yè)品的發(fā)展和技術(shù)水平的提高,很大程度上取決于模具工業(yè)的發(fā)展水平,因此模具工業(yè)對國民經(jīng)濟和社會發(fā)展將起越來越大的作用。1989年3月國務(wù)院頒布的關(guān)于當(dāng)前產(chǎn)業(yè)政策要點的決定中,把模具列為機械工業(yè)技術(shù)改造序列的第一位、生產(chǎn)和基本建設(shè)序列的第二位(僅次于大型發(fā)電設(shè)備及相應(yīng)的輸變電設(shè)備),確立模具工業(yè)在國民經(jīng)濟中的重要地位。1997年以來,又相繼把模具及其加工技術(shù)和設(shè)備列入了當(dāng)前國家重點鼓勵發(fā)展的產(chǎn)業(yè)、產(chǎn)品和技術(shù)目錄和鼓勵外商投資產(chǎn)業(yè)目錄。經(jīng)國務(wù)院批準,從1997年到2000年,對80多家國有專業(yè)模具廠實行增值稅返還70%的優(yōu)惠政策,以扶植模具工業(yè)的發(fā)展。所有這些,都充分體現(xiàn)了國務(wù)院和國家有關(guān)部門對發(fā)展模具工業(yè)的重視和支持。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。據(jù)統(tǒng)計,在家電、玩具等輕工行業(yè),近90的零件是綜筷具生產(chǎn)的;在飛機、汽車、農(nóng)機和無線電行業(yè),這個比例也超過60。例如飛機制造業(yè),某型戰(zhàn)斗機模具使用量超過三萬套,其中主機八千套、發(fā)動機二千套、輔機二萬套。從產(chǎn)值看,80年代以來,美、日等工業(yè)發(fā)達國家模具行業(yè)的產(chǎn)值已超過機床行業(yè),并又有繼續(xù)增長的趨勢。據(jù)國際生產(chǎn)技術(shù)協(xié)會預(yù)測,到2000年,產(chǎn)品盡件粗加工的75%、精加工的50將由模具完成;金屬、塑料、陶瓷、橡膠、建材等工業(yè)制品大部分將由模具完成,50以上的金屬板材、80以上的塑料都特通過模具轉(zhuǎn)化成制品。 2模具的歷史發(fā)展模具的出現(xiàn)可以追溯到幾千年前的陶器和青銅器鑄造,但其大規(guī)模使用卻是隨著現(xiàn)代工業(yè)的掘起而發(fā)展起來的。19世紀,隨著軍火工業(yè)(槍炮的彈殼)、鐘表工業(yè)、無線電工業(yè)的發(fā)展,沖模得到廣泛使用。二次大戰(zhàn)后,隨著世界經(jīng)濟的飛速發(fā)展,它又成了大量生產(chǎn)家用電器、汽車、電子儀器、照相機、鐘表等零件的最佳方式。從世界范圍看,當(dāng)時美國的沖壓技術(shù)走在前列許多模具先進技術(shù),如簡易模具、高效率模具、高壽命模具和沖壓自動化技術(shù),大多起源于美國;而瑞士的精沖、德國的冷擠壓技術(shù),蘇聯(lián)對塑性加工的研究也處于世界先進行列。50年代,模具行業(yè)工作重點是根據(jù)訂戶的要求,制作能滿足產(chǎn)品要求的模具。模具設(shè)計多憑經(jīng)驗,參考已有圖紙和感性認識,對所設(shè)計模具零件的機能缺乏真切了解。從1955年到1965年,是壓力加工的探索和開發(fā)時代對模具主要零部件的機能和受力狀態(tài)進行了數(shù)學(xué)分橋,并把這些知識不斷應(yīng)用于現(xiàn)場實際,使得沖壓技術(shù)在各方面有飛躍的發(fā)展。其結(jié)果是歸納出模具設(shè)計原則,并使得壓力機械、沖壓材料、加工方法、梅具結(jié)構(gòu)、模具材料、模具制造方法、自動化裝置等領(lǐng)域面貌一新,并向?qū)嵱没姆较蛲七M,從而使沖壓加工從儀能生產(chǎn)優(yōu)良產(chǎn)品的第一階段。進入70年代向高速化、啟動化、精密化、安全化發(fā)展的第二階段。在這個過程中不斷涌現(xiàn)各種高效率、商壽命、高精度助多功能自動校具。其代表是多達別多個工位的級進模和十幾個工位的多工位傳遞模。在此基礎(chǔ)上又發(fā)展出既有連續(xù)沖壓工位又有多滑塊成形工位的壓力機彎曲機。在此期間,日本站到了世界最前列其模具加工精度進入了微米級,模具壽命,合金工具鋼制造的模具達到了幾千萬次,硬質(zhì)合金鋼制造的模具達到了幾億次p每分鐘沖壓次數(shù),小型壓力機通常為200至300次,最高為1200次至1500次。在此期間,為了適應(yīng)產(chǎn)品更新快、用期短(如汽車改型、玩具翻新等)的需要,各種經(jīng)濟型模具,如鋅落合金模具、聚氨酯橡膠模具、鋼皮沖模等也得到了很大發(fā)展。從70年代中期至今可以說是計算機輔助設(shè)計、輔助制造技術(shù)不斷發(fā)展的時代。隨著模具加工精度與復(fù)雜性不斷提高,生產(chǎn)周期不斷加快,模具業(yè)對設(shè)備和人員素質(zhì)的要求也不斷提高。依靠普通加工設(shè)備,憑經(jīng)驗和手藝越來越不能滿足模具生產(chǎn)的需要。90年代以來,機械技術(shù)和電子技術(shù)緊密結(jié)合,發(fā)展了NC機床,如數(shù)控線切割機床、數(shù)控電火花機床、數(shù)控銑床、數(shù)控坐標(biāo)磨床等。而采用電子計算機自動編程、控制的CNC機床提高了數(shù)控機床的使用效率和范圍。近年來又發(fā)展出由一臺計算機以分時的方式直接管理和控制一群數(shù)控機床的NNC系統(tǒng)。隨著計算機技術(shù)的發(fā)展,計算機也逐步進入模具生產(chǎn)的各個領(lǐng)域,包括設(shè)計、制造、管理等。國際生產(chǎn)研究協(xié)會預(yù)測,到2000年,作為設(shè)計和制造之間聯(lián)系手段的圖紙將失去其主要作用。模具自動設(shè)計的最根本點是必須確立模具零件標(biāo)準及設(shè)計標(biāo)準。要擺脫過去以人的思考判斷和實際經(jīng)驗為中心所組成的設(shè)計方法,就必須把過去的經(jīng)驗和思考方法,進行系列化、數(shù)值化、數(shù)式化,作為設(shè)計準則儲存到計算機中。因為模具構(gòu)成元件也干差萬別,要搞出一個能適應(yīng)各種零件的設(shè)計軟件幾乎不可能。但是有些產(chǎn)品的零件形狀變化不大,模具結(jié)構(gòu)有一定的規(guī)律,放可總結(jié)歸納,為自動設(shè)計提供軟件。如日本某公司的CDM系統(tǒng)用于級進模設(shè)計與制造,其中包括零件圖形輸入、毛坯展開、條料排樣、確定模板尺寸和標(biāo)準、繪制裝配圖和零件圖、輸出NC程序(為數(shù)控加工中心和線切割編程)等,所用時間由手工的20%、工時減少到35小時;從80年代初日本就將三維的CADCAM系統(tǒng)用于汽車覆蓋件模具。目前,在實體件的掃描輸入,圖線和數(shù)據(jù)輸入,幾何造形、顯示、繪圖、標(biāo)注以及對數(shù)據(jù)的自動編程,產(chǎn)生效控機床控制系統(tǒng)的后置處理文件等方面已達到較高水平;計算機仿真(CAE)技術(shù)也取得了一定成果。在高層次上,CADCAMCAE集成的,即數(shù)據(jù)是統(tǒng)一的,可以互相直接傳輸信息實現(xiàn)網(wǎng)絡(luò)化。目前國外僅有少數(shù)廠家能夠做到。3我國模具工業(yè)現(xiàn)狀及發(fā)展趨勢由于歷史原因形成的封閉式、“大而全”的企業(yè)特征,我國大部分企業(yè)均設(shè)有模具車間,處于本廠的配套地位,自70年代末才有了模具工業(yè)化和生產(chǎn)專業(yè)化這個概念。生產(chǎn)效率不高,經(jīng)濟效益較差。模具行業(yè)的生產(chǎn)小而散亂,跨行業(yè)、投資密集,專業(yè)化、商品化和技術(shù)管理水平都比較低。據(jù)不完全統(tǒng)計,全國現(xiàn)有模具專業(yè)生產(chǎn)廠、產(chǎn)品廠配套的模具車間(分廠)近17000家,約60萬從業(yè)人員,年模具總產(chǎn)值達200億元人民幣。但是,我國模具工業(yè)現(xiàn)有能力只能滿足需求量的60左右,還不能適應(yīng)國民經(jīng)濟發(fā)展的需要。目前,國內(nèi)需要的大型、精密、復(fù)雜和長壽命的模具還主要依靠進口。據(jù)海關(guān)統(tǒng)計,1997年進口模具價值6.3億美元,這還不包括隨設(shè)備一起進口的模具;1997年出口模具僅為7800萬美元。目前我國模具工業(yè)的技術(shù)水平和制造能力,是我國國民經(jīng)濟建設(shè)中的薄弱環(huán)節(jié)和制約經(jīng)濟持續(xù)發(fā)展的瓶頸。3.1 模具工業(yè)產(chǎn)品結(jié)構(gòu)的現(xiàn)狀按照中國模具工業(yè)協(xié)會的劃分,我國模具基本分為10大類,其中,沖壓模和塑料成型模兩大類占主要部分。按產(chǎn)值計算,目前我國沖壓模占50左右,塑料成形模約占20,拉絲模(工具)約占10,而世界上發(fā)達工業(yè)國家和地區(qū)的塑料成形模比例一般占全部模具產(chǎn)值的40以上。我國沖壓模大多為簡單模、單工序模和符合模等,精沖模,精密多工位級進模還為數(shù)不多,模具平均壽命不足100萬次,模具最高壽命達到1億次以上,精度達到35um,有50個以上的級進工位,與國際上最高模具壽命6億次,平均模具壽命5000萬次相比,處于80年代中期國際先進水平。我國的塑料成形模具設(shè)計,制作技術(shù)起步較晚,整體水平還較低。目前單型腔,簡單型腔的模具達70以上,仍占主導(dǎo)地位。一模多腔精密復(fù)雜的塑料注射模,多色塑料注射模已經(jīng)能初步設(shè)計和制造。模具平均壽命約為80萬次左右,主要差距是模具零件變形大、溢邊毛刺大、表面質(zhì)量差、模具型腔沖蝕和腐蝕嚴重、模具排氣不暢和型腔易損等,注射模精度已達到5um以下,最高壽命已突破2000萬次,型腔數(shù)量已超過100腔,達到了80年代中期至90年代初期的國際先進水平。3.2 模具工業(yè)技術(shù)結(jié)構(gòu)現(xiàn)狀我國模具工業(yè)目前技術(shù)水平參差不齊,懸殊較大。從總體上來講,與發(fā)達工業(yè)國家及港臺地區(qū)先進水平相比,還有較大的差距。 在采用CAD/CAM/CAE/CAPP等技術(shù)設(shè)計與制造模具方面,無論是應(yīng)用的廣泛性,還是技術(shù)水平上都存在很大的差距。在應(yīng)用CAD技術(shù)設(shè)計模具方面,僅有約10%的模具在設(shè)計中采用了CAD,距拋開繪圖板還有漫長的一段路要走;在應(yīng)用CAE進行模具方案設(shè)計和分析計算方面,也才剛剛起步,大多還處于試用和動畫游戲階段;在應(yīng)用CAM技術(shù)制造模具方面,一是缺乏先進適用的制造裝備,二是現(xiàn)有的工藝設(shè)備(包括近10多年來引進的先進設(shè)備)或因計算機制式(IBM微機及其兼容機、HP工作站等)不同,或因字節(jié)差異、運算速度差異、抗電磁干擾能力差異等,聯(lián)網(wǎng)率較低,只有5%左右的模具制造設(shè)備近年來才開展這項工作;在應(yīng)用CAPP技術(shù)進行工藝規(guī)劃方面,基本上處于空白狀態(tài),需要進行大量的標(biāo)準化基礎(chǔ)工作;在模具共性工藝技術(shù),如模具快速成型技術(shù)、拋光技術(shù)、電鑄成型技術(shù)、表面處理技術(shù)等方面的CAD/CAM技術(shù)應(yīng)用在我國才剛起步。計算機輔助技術(shù)的軟件開發(fā),尚處于較低水平,需要知識和經(jīng)驗的積累。我國大部分模具廠、車間的模具加工設(shè)備陳舊,在役期長、精度差、效率低,至今仍在使用普通的鍛、車、銑、刨、鉆、磨設(shè)備加工模具,熱處理加工仍在使用鹽浴、箱式爐,操作憑工人的經(jīng)驗,設(shè)備簡陋,能耗高。設(shè)備更新速度緩慢,技術(shù)改造,技術(shù)進步力度不大。雖然近年來也引進了不少先進的模具加工設(shè)備,但過于分散,或不配套,利用率一般僅有25%左右,設(shè)備的一些先進功能也未能得到充分發(fā)揮。缺乏技術(shù)素質(zhì)較高的模具設(shè)計、制造工藝技術(shù)人員和技術(shù)工人,尤其缺乏知識面寬、知識結(jié)構(gòu)層次高的復(fù)合型人才。中國模具行業(yè)中的技術(shù)人員,只占從業(yè)人員的8%12%左右,且技術(shù)人員和技術(shù)工人的總體技術(shù)水平也較低。1980年以前從業(yè)的技術(shù)人員和技術(shù)工人知識老化,知識結(jié)構(gòu)不能適應(yīng)現(xiàn)在的需要;而80年代以后從業(yè)的人員,專業(yè)知識、經(jīng)驗匱乏,動手能力差,不安心,不愿學(xué)技術(shù)。近年來人才外流不僅造成人才數(shù)量與素質(zhì)水平下降,而且人才結(jié)構(gòu)也出現(xiàn)了新的斷層,青黃不接,使得模具設(shè)計、制造的技術(shù)水平難以提高。3.3 模具工業(yè)配套材料,標(biāo)準件結(jié)構(gòu)現(xiàn)狀近10多年來,特別是“八五”以來,國家有關(guān)部委已多次組織有關(guān)材料研究所、大專院校和鋼鐵企業(yè),研究和開發(fā)模具專用系列鋼種、模具專用硬質(zhì)合金及其他模具加工的專用工具、輔助材料等,并有所推廣。但因材料的質(zhì)量不夠穩(wěn)定,缺乏必要的試驗條件和試驗數(shù)據(jù),規(guī)格品種較少,大型模具和特種模具所需的鋼材及規(guī)格還有缺口。在鋼材供應(yīng)上,解決用戶的零星用量與鋼廠的批量生產(chǎn)的供需矛盾,尚未得到有效的解決。另外,國外模具鋼材近年來相繼在國內(nèi)建立了銷售網(wǎng)點,但因渠道不暢、技術(shù)服務(wù)支撐薄弱及價格偏高、外匯結(jié)算制度等因素的影響,目前推廣應(yīng)用不多。模具加工的輔助材料和專用技術(shù)近年來雖有所推廣應(yīng)用,但未形成成熟的生產(chǎn)技術(shù),大多仍還處于試驗摸索階段,如模具表面涂層技術(shù)、模具表面熱處理技術(shù)、模具導(dǎo)向副潤滑技術(shù)、模具型腔傳感技術(shù)及潤滑技術(shù)、模具去應(yīng)力技術(shù)、模具抗疲勞及防腐技術(shù)等尚未完全形成生產(chǎn)力,走向商品化。一些關(guān)鍵、重要的技術(shù)也還缺少知識產(chǎn)權(quán)的保護。 我國的模具標(biāo)準件生產(chǎn),80年代初才形成小規(guī)模生產(chǎn),模具標(biāo)準化程度及標(biāo)準件的使用覆蓋面約占20%,從市場上能配到的也只有約30個品種,且僅限于中小規(guī)格。標(biāo)準凸凹模、熱流道元件等剛剛開始供應(yīng),模架及零件生產(chǎn)供應(yīng)渠道不暢,精度和質(zhì)量也較差。3.4 模具工業(yè)產(chǎn)業(yè)組織結(jié)構(gòu)現(xiàn)狀我國的模具工業(yè)相對較落后,至今仍不能稱其為一個獨立的行業(yè)。我國目前的模具生產(chǎn)企業(yè)可劃分為四大類:專業(yè)模具廠,專業(yè)生產(chǎn)外供模具;產(chǎn)品廠的模具分廠或車間,以供給本產(chǎn)品廠所需的模具為主要任務(wù);三資企業(yè)的模具分廠,其組織模式與專業(yè)模具廠相類似,以小而專為主;鄉(xiāng)鎮(zhèn)模具企業(yè),與專業(yè)模具廠相類似。其中以第一類數(shù)量最多,模具產(chǎn)量約占總產(chǎn)量的70%以上。我國的模具行業(yè)管理體制分散。目前有19個大行業(yè)部門制造和使用模具,沒有統(tǒng)一管理的部門。僅靠中國模具工業(yè)協(xié)會統(tǒng)籌規(guī)劃,集中攻關(guān),跨行業(yè),跨部門管理困難很多。 模具適宜于中小型企業(yè)組織生產(chǎn),而我國技術(shù)改造投資向大中型企業(yè)傾斜時,中小型模具企業(yè)的投資得不到保證。包括產(chǎn)品廠的模具車間、分廠在內(nèi),技術(shù)改造后不能很快收回其投資,甚至負債累累,影響發(fā)展。 雖然大多數(shù)產(chǎn)品廠的模具車間、分廠技術(shù)力量強,設(shè)備條件較好,生產(chǎn)的模具水平也較高,但設(shè)備利用率低。 我國模具價格長期以來同其價值不協(xié)調(diào),造成模具行業(yè)“自身經(jīng)濟效益小,社會效益大”的現(xiàn)象?!案赡>叩牟蝗绺赡>邩?biāo)準件的,干標(biāo)準件的不如干模具帶件生產(chǎn)的。干帶件生產(chǎn)的不如用模具加工產(chǎn)品的”之類不正?,F(xiàn)象存在。4模具的發(fā)展趨勢4.1 模具CAD/CAE/CAM正向集成化、三維化、智能化和網(wǎng)絡(luò)化方向發(fā)展(1)模具軟件功能集成化 模具軟件功能的集成化要求軟件的功能模塊比較齊全,同時各功能模塊采用同一數(shù)據(jù)模型,以實現(xiàn)信息的綜合管理與共享,從而支持模具設(shè)計、制造、裝配、檢驗、測試及生產(chǎn)管理的全過程,達到實現(xiàn)最佳效益的目的。如英國Delcam公司的系列化軟件就包括了曲面/實體幾何造型、復(fù)雜形體工程制圖、工業(yè)設(shè)計高級渲染、塑料模設(shè)計專家系統(tǒng)、復(fù)雜形體CAM、藝術(shù)造型及雕刻自動編程系統(tǒng)、逆向工程系統(tǒng)及復(fù)雜形體在線測量系統(tǒng)等。集成化程度較高的軟件還包括:Pro/ENGINEER、UG和CATIA等。國內(nèi)有上海交通大學(xué)金屬塑性成型有限元分析系統(tǒng)和沖裁模CAD/CAM系統(tǒng);北京北航海爾軟件有限公司的CAXA系列軟件;吉林金網(wǎng)格模具工程研究中心的沖壓模CAD/CAE/CAM系統(tǒng)等。(2)模具設(shè)計、分析及制造的三維化傳統(tǒng)的二維模具結(jié)構(gòu)設(shè)計已越來越不適應(yīng)現(xiàn)代化生產(chǎn)和集成化技術(shù)要求。模具設(shè)計、分析、制造的三維化、無紙化要求新一代模具軟件以立體的、直觀的感覺來設(shè)計模具,所采用的三維數(shù)字化模型能方便地用于產(chǎn)品結(jié)構(gòu)的CAE分析、模具可制造性評價和數(shù)控加工、成形過程模擬及信息的管理與共享。如Pro/ENGINEER、UG和CATIA等軟件具備參數(shù)化、基于特征、全相關(guān)等特點,從而使模具并行工程成為可能。另外,Cimatran公司的Moldexpert,Delcam公司的Ps-mold及日立造船的Space-E/mold均是3D專業(yè)注塑模設(shè)計軟件,可進行交互式3D型腔、型芯設(shè)計、模架配置及典型結(jié)構(gòu)設(shè)計。澳大利亞Moldflow公司的三維真實感流動模擬軟件MoldflowAdvisers已經(jīng)受到用戶廣泛的好評和應(yīng)用。國內(nèi)有華中理工大學(xué)研制的同類軟件HSC3D4.5F及鄭州工業(yè)大學(xué)的Z-mold軟件。面向制造、基于知識的智能化功能是衡量模具軟件先進性和實用性的重要標(biāo)志之一。如Cimatron公司的注塑模專家軟件能根據(jù)脫模方向自動產(chǎn)生分型線和分型面,生成與制品相對應(yīng)的型芯和型腔,實現(xiàn)模架零件的全相關(guān),自動產(chǎn)生材料明細表和供NC加工的鉆孔表格,并能進行智能化加工參數(shù)設(shè)定、加工結(jié)果校驗等。(3)模具軟件應(yīng)用的網(wǎng)絡(luò)化趨勢 隨著模具在企業(yè)競爭、合作、生產(chǎn)和管理等方面的全球化、國際化,以及計算機軟硬件技術(shù)的迅速發(fā)展,網(wǎng)絡(luò)使得在模具行業(yè)應(yīng)用虛擬設(shè)計、敏捷制造技術(shù)既有必要,也有可能。美國在其21世紀制造企業(yè)戰(zhàn)略中指出,到2006年要實現(xiàn)汽車工業(yè)敏捷生產(chǎn)/虛擬工程方案,使汽車開發(fā)周期從40個月縮短到4個月。4.2 模具檢測、加工設(shè)備向精密、高效和多功能方向發(fā)展(1)模具檢測設(shè)備的日益精密、高效 精密、復(fù)雜、大型模具的發(fā)展,對檢測設(shè)備的要求越來越高。現(xiàn)在精密模具的精度已達23m,目前國內(nèi)廠家使用較多的有意大利、美國、日本等國的高精度三坐標(biāo)測量機,并具有數(shù)字化掃描功能。如東風(fēng)汽車模具廠不僅擁有意大利產(chǎn)3250mm3250mm三坐標(biāo)測量機,還擁有數(shù)碼攝影光學(xué)掃描儀,率先在國內(nèi)采用數(shù)碼攝影、光學(xué)掃描作為空間三維信息的獲得手段,從而實現(xiàn)了從測量實物建立數(shù)學(xué)模型輸出工程圖紙模具制造全過程,成功實現(xiàn)了逆向工程技術(shù)的開發(fā)和應(yīng)用。這方面的設(shè)備還包括:英國雷尼紹公司第二代高速掃描儀(CYCLON SERIES2)可實現(xiàn)激光測頭和接觸式測頭優(yōu)勢互補,激光掃描精度為0.05mm,接觸式測頭掃描精度達0.02mm。另外德國GOM公司的ATOS便攜式掃描儀,日本羅蘭公司的PIX-30、PIX-4臺式掃描儀和英國泰勒霍普森公司TALYSCAN150多傳感三維掃描儀分別具有高速化、廉價化和功能復(fù)合化等特點。(2)數(shù)控電火花加工機床 日本沙迪克公司采用直線電機伺服驅(qū)動的AQ325L、AQ550LLS-WEDM具有驅(qū)動反應(yīng)快、傳動及定位精度高、熱變形小等優(yōu)點。瑞士夏米爾公司的NCEDM具有P-E3自適應(yīng)控制、PCE能量控制及自動編程專家系統(tǒng)。另外有些EDM還采用了混粉加工工藝、微精加工脈沖電源及模糊控制(FC)等技術(shù)。(3) 高速銑削機床(HSM)銑削加工是型腔模具加工的重要手段。而高速銑削具有工件溫升低、切削力小、加工平穩(wěn)、加工質(zhì)量好、加工效率高(為普通銑削加工的510倍)及可加工硬材料(60HRC)等諸多優(yōu)點。因而在模具加工中日益受到重視。瑞士克朗公司UCP710型五軸聯(lián)動加工中心,其機床定位精度可達8m,自制的具有矢量閉環(huán)控制電主軸,最大轉(zhuǎn)速為42000r/min。意大利RAMBAUDI公司的高速銑床,其加工范圍達2500mm5000mm1800mm,轉(zhuǎn)速達20500r/min,切削進給速度達20m/min。HSM一般主要用于大、中型模具加工,如汽車覆蓋件模具、壓鑄模、大型塑料等曲面加工,其曲面加工精度可達0.01mm。4.3 快速經(jīng)濟制模技術(shù)縮短產(chǎn)品開發(fā)周期是贏得市場競爭的有效手段之一。與傳統(tǒng)模具加工技術(shù)相比,快速經(jīng)濟制模技術(shù)具有制模周期短、成本較低的特點,精度和壽命又能滿足生產(chǎn)需求,是綜合經(jīng)濟效益比較顯著的模具制造技術(shù),具體主要有以下一些技術(shù)。 (1)快速原型制造技術(shù)(RPM)。它包括激光立體光刻技術(shù)(SLA) ;疊層輪廓制造技術(shù)(LOM) ;激光粉末選區(qū)燒結(jié)成形技術(shù)(SLS) ;熔融沉積成形技術(shù)(FDM) 和三維印刷成形技術(shù)(3D-P)等。 (2)表面成形制模技術(shù)。它是指利用噴涂、電鑄和化學(xué)腐蝕等新的工藝方法形成型腔表面及精細花紋的一種工藝技術(shù)。 (3)澆鑄成形制模技術(shù)。主要有鉍錫合金制模技術(shù)、鋅基合金制模技術(shù)、樹脂復(fù)合成形模具技術(shù)及硅橡膠制模技術(shù)等。 (4)冷擠壓及超塑成形制模技術(shù)。 (5)無模多點成形技術(shù)。 (6)KEVRON鋼帶沖裁落料制模技術(shù)。(7)模具毛坯快速制造技術(shù)。主要有干砂實型鑄造、負壓實型鑄造、樹脂砂實型鑄造及失蠟精鑄等技術(shù)。 (8)其他方面技術(shù)。如采用氮氣彈簧壓邊、卸料、快速換模技術(shù)、沖壓單元組合技術(shù)、刃口堆焊技術(shù)及實型鑄造沖模刃口鑲塊技術(shù)等。4.4 模具材料及表面處理技術(shù)發(fā)展迅速模具工業(yè)要上水平,材料應(yīng)用是關(guān)鍵。因選材和用材不當(dāng),致使模具過早失效,大約占失效模具的45%以上。在模具材料方面,常用冷作模具鋼有CrWMn、Cr12、Cr12MoV和W6Mo5Cr4V2,火焰淬火鋼(如日本的AUX2、SX105V(7CrSiMnMoV)等;常用新型熱作模具鋼有美國H13、瑞典QRO80M、QRO90SUPREME等;常用塑料模具用鋼有預(yù)硬鋼(如美國P20)、時效硬化型鋼(如美國P21、日本NAK55等)、熱處理硬化型鋼(如美國D2,日本PD613、PD555、瑞典一勝白136等)、粉末模具鋼(如日本KAD18和KAS440)等;覆蓋件拉延模常用HT300、QT60-2、Mo-Cr、Mo-V鑄鐵等,大型模架用HT250。多工位精密沖模常采用鋼結(jié)硬質(zhì)合金及硬質(zhì)合金YG20等。在模具表面處理方面,其主要趨勢是:由滲入單一元素向多元素共滲、復(fù)合滲(如TD法)發(fā)展;由一般擴散向CVD、PVD、PCVD、離子滲入、離子注入等方向發(fā)展;可采用的鍍膜有:TiC、TiN、TiCN、TiAlN、CrN、Cr7C3、W2C等,同時熱處理手段由大氣熱處理向真空熱處理發(fā)展。另外,目前對激光強化、輝光離子氮化技術(shù)及電鍍(刷鍍)防腐強化等技術(shù)也日益受到重視。4.5 模具工業(yè)新工藝、新理念和新模式逐步得到了認同在成形工藝方面,主要有沖壓模具功能復(fù)合化、超塑性成形、塑性精密成形技術(shù)、塑料模氣體輔助注射技術(shù)及熱流道技術(shù)、高壓注射成形技術(shù)等。另一方面,隨著先進制造技術(shù)的不斷發(fā)展和模具行業(yè)整體水平的提高,在模具行業(yè)出現(xiàn)了一些新的設(shè)計、生產(chǎn)、管理理念與模式。具體主要有:適應(yīng)模具單件生產(chǎn)特點的柔性制造技術(shù);創(chuàng)造最佳管理和效益的團隊精神,精益生產(chǎn);提高快速應(yīng)變能力的并行工程、虛擬制造及全球敏捷制造、網(wǎng)絡(luò)制造等新的生產(chǎn)哲理;廣泛采用標(biāo)準件通用件的分工協(xié)作生產(chǎn)模式;適應(yīng)可持續(xù)發(fā)展和環(huán)保要求的綠色設(shè)計與制造等。第 26 頁 共 27 頁e pos 模具工業(yè)現(xiàn)狀Process simulation in stamping recent applications for product and process designAbstractProcess simulation for product and process design is currently being practiced in industry. However, a number of input variables have a significant effect on the accuracy and reliability of computer predictions. A study was conducted to evaluate the capability of FE-simulations for predicting part characteristics and process conditions in forming complex-shaped, industrial parts.In industrial applications, there are two objectives for conducting FE-simulations of the stamping process; (1) to optimize the product design by analyzing formability at the product design stage and (2) to reduce the tryout time and cost in process design by predicting the deformation process in advance during the die design stage. For each of these objectives, two kinds of FE-simulations are applied. Pam-Stamp, an incremental dynamic-explicit FEM code released by Engineering Systems Intl, matches the second objective well because it can deal with most of the practical stamping parameters. FAST_FORM3D, a one-step FEM code released by Forming Technologies, matches the first objective because it only requires the part geometry and not the complex process information.In a previous study, these two FE codes were applied to complex-shaped parts used in manufacturing automobiles and construction machinery. Their capabilities in predicting formability issues in stamping were evaluated. This paper reviews the results of this study and summarizes the recommended procedures for obtaining accurate and reliable results from FE simulations.In another study, the effect of controlling the blank holder force (BHF) during the deep drawing of hemispherical, dome-bottomed cups was investigated. The standard automotive aluminum-killed, drawing-quality (AKDQ) steel was used as well as high performance materials such as high strength steel, bake hard steel, and aluminum 6111. It was determined that varying the BHF as a function of stroke improved the strain distributions in the domed cups.Keywords: Stamping; Process ;stimulation; Process design1. IntroductionThe design process of complex shaped sheet metal stampings such as automotive panels, consists of many stages of decision making and is a very expensive and time consuming process. Currently in industry, many engineering decisions are made based on the knowledge of experienced personnel and these decisions are typically validated during the soft tooling and prototyping stage and during hard die tryouts. Very often the soft and hard tools must be reworked or even redesigned and remanufactured to provide parts with acceptable levels of quality.The best case scenario would consist of the process outlined in Fig. 1. In this design process, the experienced product designer would have immediate feedback using a specially design software called one-step FEM to estimate the formability of their design. This would allow the product designer to make necessary changes up front as opposed to down the line after expensive tooling has been manufactured. One-step FEM is particularly suited for product analysis since it does not require binder, addendum, or even most process conditions. Typically this information is not available during the product design phase. One-step FEM is also easy to use and computationally fast, which allows the designer to play “what if” without much time investment.Fig. 1. Proposed design process for sheet metal stampings. Once the product has been designed and validated, the development project would enter the “time zero” phase and be passed onto the die designer. The die designer would validate his/her design with an incremental FEM code and make necessary design changes and perhaps even optimize the process parameters to ensure not just minimum acceptability of part quality, but maximum achievable quality. This increases product quality but also increase process robustness. Incremental FEM is particularly suited for die design analysis since it does require binder, addendum, and process conditions which are either known during die design or desired to be known.The validated die design would then be manufactured directly into the hard production tooling and be validated with physical tryouts during which the prototype parts would be made. Tryout time should be decreased due to the earlier numerical validations. Redesign and remanufacturing of the tooling due to unforeseen forming problems should be a thing of the past. The decrease in tryout time and elimination of redesign/remanufacturing should more than make up for the time used to numerically validate the part, die, and process. Optimization of the stamping process is also of great importance to producers of sheet stampings. By modestly increasing ones investment in presses, equipment, and tooling used in sheet forming, one may increase ones control over the stamping process tremendously. It has been well documented that blank holder force is one of the most sensitive process parameters in sheet forming and therefore can be used to precisely control the deformation process.By controlling the blank holder force as a function of press stroke AND position around the binder periphery, one can improve the strain distribution of the panel providing increased panel strength and stiffness, reduced springback and residual stresses, increased product quality and process robustness. An inexpensive, but industrial quality system is currently being developed at the ERC/NSM using a combination of hydraulics and nitrogen and is shown in Fig. 2. Using BHF control can also allow engineers to design more aggressive panels to take advantage the increased formability window provided by BHF control.Fig. 2. Blank holder force control system and tooling being developed at the ERC/NSM labs.Three separate studies were undertaken to study the various stages of the design process. The next section describes a study of the product design phase in which the one-step FEM code FAST_FORM3D (Forming Technologies) was validated with a laboratory and industrial part and used to predict optimal blank shapes. Section 4 summarizes a study of the die design stage in which an actual industrial panel was used to validate the incremental FEM code Pam-Stamp (Engineering Systems Intl). Section 5 covers a laboratory study of the effect of blank holder force control on the strain distributions in deep drawn, hemispherical, dome-bottomed cups.2. Product simulation applicationsThe objective of this investigation was to validate FAST_FORM3D, to determine FAST_FORM3Ds blank shape prediction capability, and to determine how one-step FEM can be implemented into the product design process. Forming Technologies has provided their one-step FEM code FAST_FORM3D and training to the ERC/NSM for the purpose of benchmarking and research. FAST_FORM3D does not simulate the deformation history. Instead it projects the final part geometry onto a flat plane or developable surface and repositions the nodes and elements until a minimum energy state is reached. This process is computationally faster than incremental simulations like Pam-Stamp, but also makes more assumptions. FAST_FORM3D can evaluate formability and estimate optimal blank geometries and is a strong tool for product designers due to its speed and ease of use particularly during the stage when the die geometry is not available.In order to validate FAST_FORM3D, we compared its blank shape prediction with analytical blank shape prediction methods. The part geometry used was a 5in. deep 12in. by 15in. rectangular pan with a 1in. flange as shown in Fig. 3. Table 1 lists the process conditions used. Romanovskis empirical blank shape method and the slip line field method was used to predict blank shapes for this part which are shown in Fig. 4. Fig. 3. Rectangular pan geometry used for FAST_FORM3D validation.Table 1. Process parameters used for FAST_FORM3D rectangular pan validation Fig. 4. Blank shape design for rectangular pans using hand calculations. (a) Romanovskis empirical method; (b) slip line field analytical method.Fig. 5(a) shows the predicted blank geometries from the Romanovski method, slip line field method, and FAST_FORM3D. The blank shapes agree in the corner area, but differ greatly in the side regions. Fig. 5(b)(c) show the draw-in pattern after the drawing process of the rectangular pan as simulated by Pam-Stamp for each of the predicted blank shapes. The draw-in patterns for all three rectangular pans matched in the corners regions quite well. The slip line field method, though, did not achieve the objective 1in. flange in the side region, while the Romanovski and FAST_FORM3D methods achieved the 1in. flange in the side regions relatively well. Further, only the FAST_FORM3D blank agrees in the corner/side transition regions. Moreover, the FAST_FORM3D blank has a better strain distribution and lower peak strain than Romanovski as can be seen in Fig. 6.Fig. 5. Various blank shape predictions and Pam-Stamp simulation results for the rectangular pan. (a) Three predicted blank shapes; (b) deformed slip line field blank; (c) deformed Romanovski blank; (d) deformed FAST_FORM3D blank.Fig. 6. Comparison of strain distribution of various blank shapes using Pam-Stamp for the rectangular pan. (a) Deformed Romanovski blank; (b) deformed FAST_FORM3D blank.To continue this validation study, an industrial part from the Komatsu Ltd. was chosen and is shown in Fig. 7(a). We predicted an optimal blank geometry with FAST_FORM3D and compared it with the experimentally developed blank shape as shown in Fig. 7(b). As seen, the blanks are similar but have some differences.Fig. 7. FAST_FORM3D simulation results for instrument cover validation. (a) FAST_FORM3Ds formability evaluation; (b) comparison of predicted and experimental blank geometries.Next we simulated the stamping of the FAST_FORM3D blank and the experimental blank using Pam-Stamp. We compared both predicted geometries to the nominal CAD geometry (Fig. 8) and found that the FAST_FORM3D geometry was much more accurate. A nice feature of FAST_FORM3D is that it can show a “failure” contour plot of the part with respect to a failure limit curve which is shown in Fig. 7(a). In conclusion, FAST_FORM3D was successful at predicting optimal blank shapes for a laboratory and industrial parts. This indicates that FAST_FORM3D can be successfully used to assess formability issues of product designs. In the case of the instrument cover, many hours of trial and error experimentation could have been eliminated by using FAST_FORM3D and a better blank shape could have been developed.Fig. 8. Comparison of FAST_FORM3D and experimental blank shapes for the instrument cover. (a) Experimentally developed blank shape and the nominal CAD geometry; (b) FAST_FORM3D optimal blank shape and the nominal CAD geometry.3. Die and process simulation applicationsIn order to study the die design process closely, a cooperative study was conducted by Komatsu Ltd. of Japan and the ERC/NSM. A production panel with forming problems was chosen by Komatsu. This panel was the excavators cabin, left-hand inner panel shown in Fig. 9. The geometry was simplified into an experimental laboratory die, while maintaining the main features of the panel. Experiments were conducted at Komatsu using the process conditions shown in Table 2. A forming limit diagram (FLD) was developed for the drawing-quality steel using dome tests and a vision strain measurement system and is shown in Fig. 10. Three blank holder forces (10, 30, and 50ton) were used in the experiments to determine its effect. Incremental simulations of each experimental condition was conducted at the ERC/NSM using Pam-Stamp.Fig. 9. Actual product cabin inner panel.Table 2. Process conditions for the cabin inner investigation Fig. 10. Forming limit diagram for the drawing-quality steel used in the cabin inner investigation.At 10ton, wrinkling occurred in the experimental parts as shown in Fig. 11. At 30ton, the wrinkling was eliminated as shown in Fig. 12. These experimental observations were predicted with Pam-stamp simulations as shown in Fig. 13. The 30ton panel was measured to determine the material draw-in pattern. These measurements are compared with the predicted material draw-in in Fig. 14. Agreement was very good, with a maximum error of only 10mm. A slight neck was observed in the 30ton panel as shown in Fig. 13. At 50ton, an obvious fracture occurred in the panel.Fig. 11. Wrinkling in laboratory cabin inner panel, BHF=10ton.Fig. 12. Deformation stages of the laboratory cabin inner and necking, BHF=30ton. (a) Experimental blank; (b) experimental panel, 60% formed; (c) experimental panel, fully formed; (d) experimental panel, necking detail.Fig. 13. Predication and elimination of wrinkling in the laboratory cabin inner. (a) Predicted geometry, BHF=10ton; (b) predicted geometry, BHF=30ton.Fig. 14. Comparison of predicted and measured material draw-in for lab cabin inner, BHF=30ton.Strains were measured with the vision strain measurement system for each panel, and the results are shown in Fig. 15. The predicted strains from FEM simulations for each panel are shown in Fig. 16. The predictions and measurements agree well regarding the strain distributions, but differ slightly on the effect of BHF. Although the trends are represented, the BHF tends to effect the strains in a more localized manner in the simulations when compared to the measurements. Nevertheless, these strain prediction show that Pam-Stamp correctly predicted the necking and fracture which occurs at 30 and 50ton. The effect of friction on strain distribution was also investigated with simulations and is shown in Fig. 17.Fig. 15. Experimental strain measurements for the laboratory cabin inner. (a) measured strain, BHF=10ton (panel wrinkled); (b) measured strain, BHF=30ton (panel necked); (c) measured strain, BHF =50ton (panel fractured).Fig. 16. FEM strain predictions for the laboratory cabin inner. (a) Predicted strain, BHF=10ton; (b) predicted strain, BHF=30ton; (c) predicted strain, BHF=50ton.Fig. 17. Predicted effect of friction for the laboratory cabin inner, BHF=30ton. (a) Predicted strain, =0.06; (b) predicted strain, =0.10.A summary of the results of the comparisons is included in Table 3. This table shows that the simulations predicted the experimental observations at least as well as the strain measurement system at each of the experimental conditions. This indicates that Pam-Stamp can be used to assess formability issues associated with the die design.Table 3. Summary results of cabin inner study 4. Blank holder force control applicationsThe objective of this investigation was to determine the drawability of various, high performance materials using a hemispherical, dome-bottomed, deep drawn cup (see Fig. 18) and to investigate various time variable blank holder force profiles. The materials that were investigated included AKDQ steel, high strength steel, bake hard steel, and aluminum 6111 (see Table 4). Tensile tests were performed on these materials to determine flow stress and anisotropy characteristics for analysis and for input into the simulations (see Fig. 19 and Table 5).Fig. 18. Dome cup tooling geometry.Table 4. Material used for the dome cup study Fig. 19. Results of tensile tests of aluminum 6111, AKDQ, high strength, and bake hard steels. (a) Fractured tensile specimens; (b) Stress/strain curves.Table 5. Tensile test data for aluminum 6111, AKDQ, high strength, and bake hard steels It is interesting to note that the flow stress curves for bake hard steel and AKDQ steel were very similar except for a 5% reduction in elongation for bake hard. Although, the elongations for high strength steel and aluminum 6111 were similar, the n-value for aluminum 6111 was twice as large. Also, the r-value for AKDQ was much bigger than 1, while bake hard was nearly 1, and aluminum 6111 was much less than 1.The time variable BHF profiles used in this investigation included constant, linearly decreasing, and pulsating (see Fig. 20). The experimental conditions for AKDQ steel were simulated using the incremental code Pam-Stamp. Examples of wrinkled, fractured, and good laboratory cups are shown in Fig. 21 as well as an image of a simulated wrinkled cup.Fig. 20. BHF time-profiles used for the dome cup study. (a) Constant BHF; (b) ramp BHF; (c) pulsating BHF.Fig. 21. Experimental and simulated dome cups. (a) Experimental good cup; (b) experimental fractured cup; (c) experimental wrinkled cup; (d) simulated wrinkled cup.Limits of drawability were experimentally investigated using constant BHF. The results of this study are shown in Table 6. This table indicates that AKDQ had the largest drawability window while aluminum had the smallest and bake hard and high strength steels were in the middle. The strain distributions for constant, ramp, and pulsating BHF are compared experimentally in Fig. 22 and are compared with simulations in Fig. 23 for AKDQ. In both simulations and experiments, it was found that the ramp BHF trajectory improved the strain distribution the best. Not only were peak strains reduced by up to 5% thereby reducing the possibility of fracture, but low strain regions were increased. This improvement in strain distribution can increase product stiffness and strength, decrease springback and residual stresses, increase product quality and process robustness.Table 6. Limits of drawability for dome cup with constant BHF Fig. 22. Experimental effect of time variable BHF on engineering strain in an AKDQ steel dome cup.Fig. 23. Simulated effect of time variable BHF on true strain in an AKDQ steel dome cup.Pulsating BHF, at the frequency range investigated, was not found to have an effect on strain distribution. This was likely due to the fact the frequency of pulsation that was tested was only 1Hz. It is known from previous experiments of other researchers that proper frequencies range from 5 to 25Hz 3. A comparison of load-stroke curves from simulation and experiments are shown in Fig. 24 for AKDQ. Good agreement was found for the case where =0.08. This indicates that FEM simulations can be used to assess the formability improvements that can be obtained by using BHF control techniques.Fig. 24. Comparison of experimental and simulated load-stroke curves for an AKDQ steel dome cup.5 Conclusions and future work In this paper, we evaluated an improved design process for complex stampings which involved eliminating the soft tooling phase and incorporated the validation of product and process using one-step and incremental FEM simulations. Also, process improvements were proposed consisting of the implementation of blank holder force control to increase product quality and process robustness.Three separate investigations were summarized which analyzed various stages in the design process. First, the product design phase was investigated with a laboratory and industrial validation of the one-step FEM code FAST_FORM3D and its ability to assess formability issues involved in product design. FAST_FORM3D was successful at predicting optimal blank shapes for a rectangular pan and an industrial instrument cover. In the case of the instrument cover, many hours of trial and error experimentation could have been eliminated by using FAST_FORM3D and a better blank shape could have been developed.Second, the die design
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