彎曲角小于90°的U形彎曲模具運動仿真【說明書+CAD+PROE+仿真】
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河南機電高等??茖W(xué)校
學(xué)生畢業(yè)設(shè)計中期檢查表
學(xué)生姓名
王亞飛
學(xué) 號
061304327
指導(dǎo)教師
原紅玲
選題情況
課題名稱
彎曲角小于90°的U形彎曲模運動仿真
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(wù)書
有
無
開題報告
有
無
外文翻譯質(zhì)量
優(yōu)
良
中
差
學(xué)習(xí)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(zé)人:
年 月 日
河南機電高等專科學(xué)校
畢業(yè)設(shè)計任務(wù)書
系 部: 材料工程系
專 業(yè): 模具設(shè)計與制造
學(xué)生姓名: 王亞飛 學(xué) 號: 061304327
設(shè)計題目: 彎曲角小于90°的U形彎曲模具運動仿真
起 迄 日 期: 2009 年3 月 11 日~ 5 月 20 日
指 導(dǎo) 教 師: 原紅玲
2009年3月11日
畢 業(yè) 設(shè) 計 任 務(wù) 書
1.本畢業(yè)設(shè)計課題來源及應(yīng)達到的目的:
該題目來自原紅玲主編的《沖壓工藝與模具設(shè)計》第110頁圖3.49。
在完成該課題之后,能夠把所學(xué)知識和軟件更好的結(jié)合起來,應(yīng)對彎曲模具設(shè)計熟悉,能熟練掌握相關(guān)設(shè)計手冊的使用,能獨立完成一套模具的設(shè)計并靈活運用模具設(shè)計軟件完成模具動畫的制作過程。
2.本畢業(yè)設(shè)計課題任務(wù)的內(nèi)容和要求
(1)了解目前國內(nèi)外彎曲模具的發(fā)展現(xiàn)狀;
(2)了解模具設(shè)計軟件的功能特點;
(3)彎曲工藝簡介與分析;
(4)模具動作過程準(zhǔn)確、連貫,動畫速度適中;
(5)凹型精密彎曲模具的運動仿真動畫設(shè)計,并編寫設(shè)計說明書一份;
所在專業(yè)審查意見:
負責(zé)人:
年 月 日
系部意見:
系領(lǐng)導(dǎo):
年 月 日
河南機電高等??茖W(xué)校
畢業(yè)論文
畢業(yè)論文題目:彎曲角小于90°的U形彎曲模運動仿真
系 部 材料工程系
專 業(yè) 模具設(shè)計與制造
班 級 模具063班
學(xué)生姓名 王 亞 飛
學(xué) 號 061304327
指導(dǎo)教師 原紅玲
2009年5月 15日
河南機電高等??茖W(xué)校畢業(yè)論文
1 緒 論
目前,我國沖壓技術(shù)與工業(yè)發(fā)達國家相比還相當(dāng)?shù)穆浜?,主要原因是我國在沖壓基礎(chǔ)理論及成形工藝、模具標(biāo)準(zhǔn)化、模具設(shè)計、模具制造工藝及設(shè)備等方面與發(fā)達國家尚有相當(dāng)大的差距,導(dǎo)致我國模具在壽命、效率、加工精度、生產(chǎn)周期等方面與工業(yè)發(fā)達國家的模具相比差距相當(dāng)大。
1.1 沖壓工藝簡介
沖壓加工技術(shù)應(yīng)用十分廣泛,在國民經(jīng)濟各工業(yè)部門中,幾乎都有沖壓加工或沖壓產(chǎn)品的生產(chǎn)。如汽車、飛機、拖拉機。電機、電器、儀表、鐵道、電信、化工以及輕工日用產(chǎn)品中均占有相當(dāng)大的比重。
沖壓生產(chǎn)主要是利用沖壓設(shè)備和模具實現(xiàn)對金屬材料(板材)的加工,使其產(chǎn)生分離或塑性變形,從而獲得零件的過程。所以沖壓加工具有以下特點:(1)生產(chǎn)率搞、操作方便、容易實現(xiàn)機械化和自動化,特別適合于大批量生產(chǎn);(2)沖壓零件表面光潔,尺寸精度穩(wěn)定,互換性好,成本低廉;(3)在材料消耗不多的情況下,可以獲得輕度高、剛度大、而重量小的零件;(4)可得到其他加工方法難以加工或無法加工的復(fù)雜形狀零件。
由于沖壓加工具有節(jié)材、節(jié)能和生產(chǎn)效率高等突出特點,決定了沖壓產(chǎn)品成本低廉,效益較好,因而沖壓生產(chǎn)在制造行業(yè)中占有重要的地位。隨著科學(xué)技術(shù)的進步和工業(yè)生產(chǎn)的迅速發(fā)展,許多新技術(shù)、新工藝、新材料、新設(shè)備不斷涌現(xiàn),因而,促成了沖壓技術(shù)的不斷革新和發(fā)展。模具已成為當(dāng)代工業(yè)生產(chǎn)的重要手段,沖壓生產(chǎn)和模具工業(yè)得到了世界各國的高度重視。
彎曲是利用金屬的塑性變形,將板材、棒料、型材或管料等完成一定形狀和角度的零件的一種沖壓成型工序。采用彎曲成形的零件種類繁多,常見的如汽車大梁、自行車把、門窗鉸鏈、各種電器零件的支架等。由于金屬的流動發(fā)生在金屬的塑性變形范圍內(nèi),因此當(dāng)所施加的外力取出后將會保留一個永久性的彎曲變形。
V形壓彎模和U形壓彎模是彎曲模中兩種最基本的彎曲模。U形彎曲中(如下圖所示),在凹模的圓角半徑支撐點B處產(chǎn)生反力P,這樣就形成彎曲力矩M=PL,該彎曲力矩使板料產(chǎn)生彎曲。在彎曲過程中,隨著凸模進入凹模的深度不同,凹模圓角半徑支撐點的位置及彎曲件毛坯彎曲半徑r發(fā)生變化,即支撐點距離L和彎曲半徑r逐漸減小,而彎曲力P逐漸增大,彎矩M也增加。當(dāng)毛坯的彎曲半徑達到一定值時,毛坯在彎曲凸模圓角半徑處開始塑性變形,最后將板料彎曲成與凸模形狀一致的工件。
1 凸模 2凹模
1.2 Pro/ENGINEER簡介
Pro/ENGINEER是由美國參數(shù)技術(shù)公司推出的一套博大精深的三維CAD/CAM參數(shù)化軟件系統(tǒng),它的內(nèi)容涵蓋了產(chǎn)品從概念設(shè)計、工業(yè)造型設(shè)計、分析計算;動態(tài)模擬和仿真、工程圖的輸出、生產(chǎn)加工成產(chǎn)品的全過程,其中還包括了大量的電纜和管道布線。模具設(shè)計與分析等使用模塊。應(yīng)用領(lǐng)域包括航空航天、汽車、機械、數(shù)控(NC)加工、電子等諸多行業(yè)。
由于其強大而完美的功能,Pro/ENGINEER幾乎成為三維CAD/CAM領(lǐng)域的一面旗幟和標(biāo)準(zhǔn)。它在國外大學(xué)校園里已成為學(xué)生工程必修的專業(yè)課程,也成為工程技術(shù)人員必備的技術(shù)。
1.2.1 Pro/ENGINEER的動畫模塊概述
(1)將產(chǎn)品的運行用動畫來表示,使其具有可視性。只要將主體拖動到不同的位置,并拍下快照來創(chuàng)建動畫。
(2)可以用動畫的方式形象的表示產(chǎn)品的裝配和拆卸序列。
(3)可以創(chuàng)建維護產(chǎn)品步驟的簡短動畫,用來指導(dǎo)用戶如何維修或建立產(chǎn)品。
1.2.2 動畫創(chuàng)建的一般步驟
(1)進入動畫模塊
(2)新建并命名動畫
(3)定義主體
(4)拖移主體并生成一連串的快照
(5)用所生成的快照建立關(guān)鍵幀
(6)執(zhí)行動畫,播放動畫
(7)保存動畫文件
1.2.3 Pro/ENGINEER動畫模塊里的常用圖標(biāo)命令
定義動畫名稱;
動畫中的主體定義;
創(chuàng)建新關(guān)鍵幀序列;
從動畫時間線中移除選定的圖元;
啟動動畫;
回放,可以回放動畫,輸出視頻文件。
2本次論文論述所要解決的問題
運用Pro ENGINEER野火4.0對《沖壓工藝與模具設(shè)計》3.7節(jié)彎曲模具的典型結(jié)構(gòu)的彎曲角小于90°U形件彎曲模進行模具結(jié)構(gòu)分析,將各個彎曲模具的零部件裝配在一起,用Pro ENGINEER野火4.0里的動畫模塊進行動畫設(shè)計,通過動畫用三維的動態(tài)效果來表現(xiàn)模具工作原理,形象,容易理解。
本次畢業(yè)論文的要求就是進一步解釋動畫制作的基本步驟和方法,根據(jù)我的學(xué)習(xí)下面將本動畫的詳細步驟敘述于下,希望老師給以檢閱審查,提出寶貴的意見。
3 彎曲角小于90°的U形件彎曲模動畫制作
3.1 彎曲角小于90°的U形件彎曲模動畫的制作進度
(1)了解國內(nèi)外沖壓模具的發(fā)展現(xiàn)狀,所用時間2天;
(2)弄懂本模具的工作原理所用時間2天;
(3)彎曲模具各個零部件設(shè)計所用時間3天;
(4)彎曲模具的裝配,所用時間2天;
(5)動畫的制作所用時間7天;
(6)修改動畫,寫畢業(yè)論文5天。
3.2 彎曲角小于90°的U形彎曲模的工作原理
首先先畫出此模具的二維主視圖,觀察模具結(jié)構(gòu),如圖3-1所示。圖3-1 所示為彎曲角小于90°的U形件彎曲模。坯料首先在凸模8的作用下被彎成U形;隨著上模座4繼續(xù)向下移動,彈簧3被壓縮,裝于上模座4上的兩塊斜楔2壓向滾柱1,使裝有滾柱1的活動凹模快5、6分別向中間移動,將U形件的兩側(cè)邊向里完成小于90°的角度,當(dāng)上?;爻虝r,彈簧7 使凹模塊復(fù)位,工件被凸模帶著上行,前后方向取出工件。
圖3-1
4 彎曲角小于90°U形件彎曲模模具動畫制作詳細過程
因為Pro ENGINEER 軟件動畫模塊功能里對動畫制作完全是瞬間拍照,然后經(jīng)過圖片的連接完成一連續(xù)的動畫;此模具的運動過程是彎曲,而在軟件中,坯料不能隨著凸模的下行而自動彎曲變形,根據(jù)凸模下行的不同位置在Pro ENGINEER 中不同位置的工件彎曲形狀,把各個彎曲階段不同形狀的彎曲件裝配在凸模下行過程中的不同位置。本動畫制作過程中,根據(jù)10種不同彎曲狀態(tài)連接而成的動畫。
4.1 彎曲模具動畫制作準(zhǔn)備工作
(1)用Pro ENGINEER 4.0零件模塊建立各個零件的三維模型,建立如圖3-1所示的每一個零部件。
(2)在組建模塊把各零部件進行裝配,裝配完成后,需要刪除裝配約束,為方便以后做動畫
4.2 彎曲工件凸模下行到工件表面動畫的制作
運行Pro ENGINEER 4.0,選擇下拉菜單【文件】下【設(shè)置工作目錄】命令,將工作目錄設(shè)置在D:\wangyafei-donghua\wanqumuju。
然后選擇下拉菜單【文件】點擊【打開】,打開裝配好的模具裝配圖文件asm0003.asm,如圖4-1。
圖4-1
注意:進入動畫模塊,必須在裝配模塊中進行。
選擇下拉菜單【應(yīng)用程序】--【動畫】命令。系統(tǒng)進入動畫模塊,如圖4-2。
圖4-2
單擊,在在彈出的對話框中的建立一個【重定向視圖】,命名為donghua保存,如圖4-3。
圖4-3
單擊圖標(biāo),新建動畫,在彈出對話框中可重命名動畫名稱,如圖4-4所示,定義動畫名稱后,關(guān)閉窗口。
圖4-4
單擊 圖標(biāo),彈出如對話框,在操作之前,每一個零件都是一個 boyd檢查裝配模具圖的整個剛體情況,根據(jù)本模具工作把上模部分整體連接組成一個剛體,先單擊每一個主體一個零件,再單擊body19上模座,點編輯按住Ctrl鍵添加上模部分的所有零件,如圖圖4-5。
圖 4-5
單擊 圖標(biāo) ,彈出如圖4-6對話框,在圖4-6對話框中單擊擊圖標(biāo),彈出如圖4-7拖動對話框,先點拍下第一張圖snapshot1,然后在圖4-6對話框中點擊點拖動圖標(biāo),選擇拖動的方向Z軸方向,如圖4-8。 然后鼠標(biāo)拖動上模部分向下移動至凸模與坯料接觸,再單擊擊圖標(biāo)拍下模具下行的第二張圖snapshot2,如圖4-9所示,點關(guān)閉。
圖4-6
圖4-7
圖4-8
圖4-9
在如圖4-10 所示的對話框中設(shè)置時間,更改時間為5s,回車,再單擊確定
圖4-10
單擊圖標(biāo),查看動畫第一階段的動作是否正確。無誤后,再單擊圖標(biāo),彈出如圖4-11對話框中單擊捕獲,在彈出如圖 對話框,更改名稱為001.mpg,單擊確定輸出此階段的動畫視頻。最后刪除關(guān)鍵幀操作,如圖4-12。
圖4-11 圖4-12
單擊【文件】——【保存】,保存文件。
最后刪除關(guān)鍵幀操作,如圖4-13。
圖4-13
4.3 彎曲角大于90°彎曲部分的動畫制作
在模型樹中右鍵單擊gongjian-01.prt隱藏,在右鍵單擊gongjian-02.prt取消隱藏,如圖4-14所示。gongjian-02.prt就會顯示在凸模上了,接著做動畫,如圖4-15。
圖4-14
圖4-15
單擊圖標(biāo),進行第二階段的拍照,彈出對話框后,和第一階段的操作相同,上模部分被拖動到的位置(如圖圖4-16 )得到snapshot3和snapshot4兩張快照,時間為2s。查看模具的動作無誤后,輸出動畫視頻002。再保存文件。
圖 4-16
隱藏藏上次操作的工件,在左邊模型樹中對下一次需要操作的零件取消隱藏。如同第二階段的動畫操作,做出動畫,一直到gongjian-07.prt,每個階段的位置,如圖4-17所示。
gongjian-04.prt gongjian-05.prt
gngjian-06.prt gongjian-07.prt
圖4-17
4.4彎曲角小于90°的彎曲部分動畫制作
隱藏gongjian-07.prt,取消隱藏gongjian-09.prt得到模具這個的階段的視圖,如圖4-18。
圖4-18
單擊擊圖標(biāo),彈出自定義主體對話框,如圖4-19所示,單擊每一個主體一個零件。選擇整上模座、導(dǎo)套、斜楔、模柄和四個長螺釘為一個連接剛體,如圖4-20。
圖4-19
圖4-20
再編輯左右凹?;瑝K(包括滾柱、滾輪和凹?;顒訅K)分別為一個連接剛體,如圖4-21
圖4-21
圖4-22
點擊圖標(biāo),對此階段拍照,彈出對話框后,單擊圖標(biāo),在彈出對話框中單擊拍下一張圖,再單擊高級拖動選項中的X向平移,如圖4-22 。分別拖動左右凹?;瑝K到如圖4-23所示的位置,單擊Z向平移,拖動上模座和斜楔部分,是斜楔的斜面和滾輪面接觸,如圖4-24單擊拍下快照,設(shè)置時間2s。檢查模具動畫動作是否正確,輸出動畫008.mpg,并保存文件。最后再移除關(guān)鍵幀。
圖4-23
圖4-24
在下兩個階段gongjian-10.prt和gongjian.prt上一個階段的操作相同,拖動位置如圖4-25
gongjian-10.prt
gongjian.prt
圖4-25
4.5彎曲模具上模部分回程制作
點擊圖標(biāo),對此階段拍照,彈出對話框后,單擊圖標(biāo),在彈出對話框中單擊拍下一張圖,再單擊高級拖動選項中的X向平移,如圖圖4-25所示的位置 。分別拖動左右凹?;瑝K到如圖圖4-26所示的位置,單擊Z向平移,拖動上模座和斜楔部分,是斜楔的斜面和滾輪面接觸,如圖4-27所示的位置,單擊拍下快照,設(shè)置時間2s。檢查和輸出動畫11.mpg。
圖4-26
圖4-27
單擊點擊圖標(biāo),利用上一張的快照,點擊圖標(biāo),在彈出的對話框中選擇Z向平移,使工件和整個上模部分上行到合適的位置,如圖4-28對此進行拍照生成照片后點關(guān)閉,完成拍照,會自動退入下一個對話框,設(shè)置時間為5s,單擊確定。檢查和輸出動畫12.mpg。
圖4-28
4.6 彎曲模具取出工件部分的動畫制作
擊圖標(biāo),在彈出的對話框中單節(jié)每個主體一個零件,單擊關(guān)閉。
點擊圖標(biāo),利用上一張的拍照,點擊圖標(biāo),在彈出的對話框中選擇Y向平移(如圖4-29),拖動gongjian.prt至合適的位置,如圖4-30設(shè)置時間為5s,單擊確定。檢查和輸出動畫13.mpg。保存文件。
圖4-29
圖4-30
最后需在制作視頻的軟件上對輸出的動畫視屏進行合理的修剪和合并,完成動畫制作。
5 總 結(jié)
通過這次畢業(yè)論文,使我學(xué)到了很多東西,Pro/ENGINEER的功能齊全而又強大,先是在建模模塊設(shè)計三維零件,再裝配成模具。在動畫模塊完成三維動態(tài)設(shè)計,做成形象的視頻來理解彎曲角小于90°的U形彎曲模的工作原理。在此過程中要利用桌面捕捉工具,詳細記錄各個步驟的操作圖片,在編輯成word格式的文件,最后檢查和修改模具動畫,編輯畢業(yè)論文。整個過程都是在計算機上完成的。鍛煉自己計算機操作能力,會使用軟件結(jié)局問題,總之受益匪淺。
致 謝
首先感謝本人的導(dǎo)師原紅玲老師,她對我的仔細審閱了本文的全部內(nèi)容并對我的畢業(yè)設(shè)計內(nèi)容提出了許多建設(shè)性建議。原紅玲老師淵博的知識,誠懇的為人,使我受益匪淺,在畢業(yè)設(shè)計的過程中,特別是遇到困難時,她給了我鼓勵和幫助,在這里我向他表示真誠的感謝!
感謝母?!幽蠙C電高等??茖W(xué)校的辛勤培育之恩!感謝材料工程系給我提供的良好學(xué)習(xí)及實踐環(huán)境,使我學(xué)到了許多新的知識,掌握了一定的操作技能。
感謝和我在一起進行課題研究的同窗沈偉飛同學(xué),和他在一起討論、研究使我受益非淺。
最后,我非常慶幸在三年的的學(xué)習(xí)、生活中認識了很多可敬的老師和可親的同學(xué),并感激師友的教誨和幫助!
參考文獻
[1]原紅玲主編.沖壓工藝與模具設(shè)計.北京:機械工業(yè)出版社,2008.8
[2]詹友剛編著. Pro/ENGINEER英文野火版教程-專用模塊.北京:清華大學(xué)出版社,2004.8
[3]葛正浩,楊芙蓮編著. Pro/E 機構(gòu)設(shè)計與運動仿真勢力教程.北京:化學(xué)工業(yè)出版社,2007.8
[4錫棟、周小玉主編.實用模具技術(shù)手冊[M].北京:機械工業(yè)出版社,2001
[5楊占堯主編.沖壓模具圖冊.北京:高等教育出版社,2008.3
- 23 -
插 圖 清 單
圖3-1 彎曲角小于90°的U形彎曲模具裝配圖……………………………………5
圖4-1彎曲模具三維裝配圖………………………………………………………………7
圖4-2 應(yīng)用程序工具欄……………………………………………………………………7
圖4-3 重定向視圖對話框…………………………………………………………………8
圖4-4 動畫命名 ……………………………………………………………………………8
圖4-5 定義主體 ……………………………………………………………………………9
圖4-6創(chuàng)建關(guān)鍵幀序列 …………………………………………………………………10
圖4-7快照對話框………… ………………………………………………………………10
圖4-8高級拖動選項…………… …………………………………………………………11
圖4-9模具下行拖移位置…………… ……………………………………………………11
圖4-10創(chuàng)建關(guān)鍵幀序列……………………………………………………………………12
圖4-11 動畫 …………………………………………………………………………………12
圖4-12捕獲輸出動畫對話框 ……………………………………………………………12
圖4-13移除關(guān)鍵幀時間線…………………………………………………………………13
圖4-14隱藏和取消隱藏……………………………………………………………………13
圖4-15第一次彎曲工件……………………………………………………………………14
圖4-16第一次彎曲工件位置 ……………………………………………………………14
圖4-17彎曲工件位置………………………………………………………………………15
圖4-18活動凹模塊移動前的位置 ………………………………………………………15
圖4-19再次定義主體對話框 ……………………………………………………………16
圖4-20上模部分定義主體…………………………………………………………………16
圖4-21凹?;瑝K定義主體…………………………………………………………………16
圖4-22凹模高級拖動選向…………………………………………………………………17
圖4-23凹模滑塊拖動位置…………………………………………………………………17
圖4-24快照創(chuàng)建關(guān)鍵幀……………………………………………………………………18
圖4-25凸模下行凹模的位置………………………………………………………………18
圖4-26凸?;爻虝r凹模的位置 …………………………………………………………19
圖4-27模具斜楔與滾輪接觸 ……………………………………………………………19
圖4-28模具回程完成………………………………………………………………………20
圖4-29取件是高級拖動選向 ……………………………………………………………20
圖4-30取件完成 ……………………………………………………………………………21
彎曲角小于90°的U形彎曲模運動仿真
摘 要
彎曲是利用金屬的塑性變形,將板料,棒料,型材或管材等按設(shè)計要求彎曲成一定曲率和一定角度的零件的一種沖壓工序。由于金屬的流動發(fā)生在金屬的塑性變形范圍內(nèi),因此當(dāng)所施加的外力取出后將會保留一個永久性的彎曲變形。
本設(shè)計是通過Pro/ENGINEER4.0的PRT模塊和ASM模塊里的動畫功能表現(xiàn)彎曲角小于90°的U形彎曲模模具的工作過程和工作原理。
關(guān)鍵詞:沖壓工序 彎曲模 塑性變形 動畫
Bending angle is acute U-bending modulus of precision motion simulation
Abstract
Bending is the use of metal plastic deformation, the sheet metal, bar, profile or pipe bending according to design requirements, such as a certain curvature and to a certain point of view of the parts of a stamping process.Metal flow takes place within the plastic range of the metal,so that the bend retains a permanent set after removal of the applied stress.
The graduated design through the shape Pro/ENGINEER4.0 of PRT and ASM module assembly module in the demo animation feature curved Bending angle is acute U-bending modulus of precision motion simulation process mode, and works.
Keywords: stamping process,Bengding dies, the plastic range, Animation
目 錄
1 緒論………………………………………………………………………………....1
1.1沖壓工藝簡介…………………………………………………………………...1
1.2 Pro/ENGINEER簡介…………………………………………………………….2
1.2.2 Pro/ENGINEER的動畫模塊概述 ………………………………………….2
1.2.2 動畫創(chuàng)建的一般步驟 ………………………………………………………3
1.2.3 Pro/ENGINEER動畫模塊里的常用圖標(biāo)命令 ……………………………3
2 本次論文論述所要解決的問題.. ……….………………………………………4
3 彎曲角小于90°的U形件彎曲模動畫…………………………………………5
3.1彎曲角小于90°的U形件彎曲模動畫的制作進度………………………..5
3.2彎曲角小于90°的U形彎曲模的工作原理……..... ………………………5
4 彎曲角小于90°U形件彎曲模模具動畫制作詳細過程 ……………………6
4.1彎曲模具動畫制作準(zhǔn)備工作…………………………………………………..6
4.2彎曲工件凸模下行到工件表面動畫的制作 ………………………………..6
4.3彎曲角大于90°彎曲部分的動畫制作 ……… ……………………………13
4.4彎曲角小于90°的彎曲部分動畫制作 …………………………………….15
4.5彎曲模具上模部分回程制作………………… ………………………………19
4.6彎曲模具取出工件部分的動畫制作…………………………………………20
5總結(jié)… ……………………………………………………………………………..22
致 謝 …… ……………………………………………………………………….....23
參考文獻… ………………………………………………………………………….24
河南機電高等??茖W(xué)校
畢業(yè)設(shè)計評語
學(xué)生姓名:王亞飛班級: 模具063 學(xué)號:061304327
題 目:彎曲角小于90°的U形彎曲模具運動仿真
綜合成績:
指導(dǎo)者評語:
王亞飛同學(xué)能按照任務(wù)書要求完成彎曲角小于90°的彎曲模具運動仿真,完成畢業(yè)設(shè)計任務(wù)過程中能正確查找設(shè)計資料,并能把所學(xué)的知識靈活運用,工作量達到要求,建議成績評定為良,可以提交答辯。
指導(dǎo)者(簽字):
2009年 5 月 10 日
畢業(yè)設(shè)計評語
評閱者評語:
王亞飛同學(xué)的畢業(yè)設(shè)計工作量達到要求,模具動作正確,能按照規(guī)范性要求書寫設(shè)計說明書。建議成績評定為良,可以提交答辯。
評閱者(簽字):
2009 年 5 月 15 日
答辯委員會(小組)評語:
答辯委員會(小組)負責(zé)人(簽字):
2009 年 月 日
Int J Adv Manuf Technol (2002) 19:253259 2002 Springer-Verlag London Limited An Analysis of Draw-Wall Wrinkling in a Stamping Die Design F.-K. Chen and Y.-C. Liao Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan Wrinkling that occurs in the stamping of tapered square cups and stepped rectangular cups is investigated. A common characteristic of these two types of wrinkling is that the wrinkles are found at the draw wall that is relatively unsup- ported. In the stamping of a tapered square cup, the effect of process parameters, such as the die gap and blank-holder force, on the occurrence of wrinkling is examined using finite- element simulations. The simulation results show that the larger the die gap, the more severe is the wrinkling, and such wrinkling cannot be suppressed by increasing the blank-holder force. In the analysis of wrinkling that occurred in the stamping of a stepped rectangular cup, an actual production part that has a similar type of geometry was examined. The wrinkles found at the draw wall are attributed to the unbalanced stretching of the sheet metal between the punch head and the step edge. An optimum die design for the purpose of eliminating the wrinkles is determined using finite-element analysis. The good agreement between the simulation results and those observed in the wrinkle-free production part validates the accuracy of the finite-element analysis, and demonstrates the advantage of using finite-element analysis for stamping die design. Keywords: Draw-wall wrinkle; Stamping die; Stepped rec- tangular cup; Tapered square cups 1. Introduction Wrinkling is one of the major defects that occur in the sheet metal forming process. For both functional and visual reasons, wrinkles are usually not acceptable in a finished part. There are three types of wrinkle which frequently occur in the sheet metal forming process: flange wrinkling, wall wrinkling, and elastic buckling of the undeformed area owing to residual elastic compressive stresses. In the forming operation of stamp- ing a complex shape, draw-wall wrinkling means the occurrence Correspondence and offprint requests to: Professor F.-K. Chen, Depart- ment of Mechanical Engineering, National Taiwan University, No. 1 Roosevelt Road, Sec. 4, Taipei, Taiwan 10617. E-mail: fkchenL50560 w3.me.ntu.edu.tw of wrinkles in the die cavity. Since the sheet metal in the wall area is relatively unsupported by the tool, the elimination of wall wrinkles is more difficult than the suppression of flange wrinkles. It is well known that additional stretching of the material in the unsupported wall area may prevent wrinkling, and this can be achieved in practice by increasing the blank- holder force; but the application of excessive tensile stresses leads to failure by tearing. Hence, the blank-holder force must lie within a narrow range, above that necessary to suppress wrinkles on the one hand, and below that which produces fracture on the other. This narrow range of blank-holder force is difficult to determine. For wrinkles occurring in the central area of a stamped part with a complex shape, a workable range of blank-holder force does not even exist. In order to examine the mechanics of the formation of wrinkles, Yoshida et al. 1 developed a test in which a thin plate was non-uniformly stretched along one of its diagonals. They also proposed an approximate theoretical model in which the onset of wrinkling is due to elastic buckling resulting from the compressive lateral stresses developed in the non-uniform stress field. Yu et al. 2,3 investigated the wrinkling problem both experimentally and analytically. They found that wrinkling could occur having two circumferential waves according to their theoretical analysis, whereas the experimental results indi- cated four to six wrinkles. Narayanasamy and Sowerby 4 examined the wrinkling of sheet metal when drawing it through a conical die using flat-bottomed and hemispherical-ended punches. They also attempted to rank the properties that appeared to suppress wrinkling. These efforts are focused on the wrinkling problems associa- ted with the forming operations of simple shapes only, such as a circular cup. In the early 1990s, the successful application of the 3D dynamic/explicit finite-element method to the sheet- metal forming process made it possible to analyse the wrinkling problem involved in stamping complex shapes. In the present study, the 3D finite-element method was employed to analyse the effects of the process parameters on the metal flow causing wrinkles at the draw wall in the stamping of a tapered square cup, and of a stepped rectangular part. A tapered square cup, as shown in Fig. 1(a), has an inclined draw wall on each side of the cup, similar to that existing in a conical cup. During the stamping process, the sheet metal on the draw wall is relatively unsupported, and is therefore 254 F.-K. Chen and Y.-C. Liao Fig. 1. Sketches of (a) a tapered square cup and (b) a stepped rectangular cup. prone to wrinkling. In the present study, the effect of various process parameters on the wrinkling was investigated. In the case of a stepped rectangular part, as shown in Fig. 1(b), another type of wrinkling is observed. In order to estimate the effectiveness of the analysis, an actual production part with stepped geometry was examined in the present study. The cause of the wrinkling was determined using finite-element analysis, and an optimum die design was proposed to eliminate the wrinkles. The die design obtained from finite-element analy- sis was validated by observations on an actual production part. 2. Finite-Element Model The tooling geometry, including the punch, die and blank- holder, were designed using the CAD program PRO/ ENGINEER. Both the 3-node and 4-node shell elements were adopted to generate the mesh systems for the above tooling using the same CAD program. For the finite-element simul- ation, the tooling is considered to be rigid, and the correspond- ing meshes are used only to define the tooling geometry and Fig. 2. Finite-element mesh. are not for stress analysis. The same CAD program using 4- node shell elements was employed to construct the mesh system for the sheet blank. Figure 2 shows the mesh system for the complete set of tooling and the sheet-blank used in the stamping of a tapered square cup. Owing to the symmetric conditions, only a quarter of the square cup is analysed. In the simulation, the sheet blank is put on the blank-holder and the die is moved down to clamp the sheet blank against the blank-holder. The punch is then moved up to draw the sheet metal into the die cavity. In order to perform an accurate finite-element analysis, the actual stressstrain relationship of the sheet metal is required as part of the input data. In the present study, sheet metal with deep-drawing quality is used in the simulations. A tensile test has been conducted for the specimens cut along planes coinciding with the rolling direction (0) and at angles of 45 and 90 to the rolling direction. The average flow stress H9268, calculated from the equation H9268H11005(H9268 0 H11001 2H9268 45 H11001H9268 90 )/4, for each measured true strain, as shown in Fig. 3, is used for the simulations for the stampings of the tapered square cup and also for the stepped rectangular cup. All the simulations performed in the present study were run on an SGI Indigo 2 workstation using the finite-element pro- gram PAMFSTAMP. To complete the set of input data required Fig. 3. The stressstrain relationship for the sheet metal. Draw-Wall Wrinkling in a Stamping Die Design 255 for the simulations, the punch speed is set to 10 m s H110021 and a coefficient of Coulomb friction equal to 0.1 is assumed. 3. Wrinkling in a Tapered Square Cup A sketch indicating some relevant dimensions of the tapered square cup is shown in Fig. 1(a). As seen in Fig. 1(a), the length of each side of the square punch head (2W p ), the die cavity opening (2W d ), and the drawing height (H) are con- sidered as the crucial dimensions that affect the wrinkling. Half of the difference between the dimensions of the die cavity opening and the punch head is termed the die gap (G) in the present study, i.e. G H11005 W d H11002 W p . The extent of the relatively unsupported sheet metal at the draw wall is presumably due to the die gap, and the wrinkles are supposed to be suppressed by increasing the blank-holder force. The effects of both the die gap and the blank-holder force in relation to the occurrence of wrinkling in the stamping of a tapered square cup are investigated in the following sections. 3.1 Effect of Die Gap In order to examine the effect of die gap on the wrinkling, the stamping of a tapered square cup with three different die gaps of 20 mm, 30 mm, and 50 mm was simulated. In each simulation, the die cavity opening is fixed at 200 mm, and the cup is drawn to the same height of 100 mm. The sheet metal used in all three simulations is a 380 mm H11003 380 mm square sheet with thickness of 0.7 mm, the stressstrain curve for the material is shown in Fig. 3. The simulation results show that wrinkling occurred in all three tapered square cups, and the simulated shape of the drawn cup for a die gap of 50 mm is shown in Fig. 4. It is seen in Fig. 4 that the wrinkling is distributed on the draw wall and is particularly obvious at the corner between adjacent walls. It is suggested that the wrinkling is due to the large unsupported area at the draw wall during the stamping process, also, the side length of the punch head and the die cavity Fig. 4. Wrinkling in a tapered square cup (G H11005 50 mm). opening are different owing to the die gap. The sheet metal stretched between the punch head and the die cavity shoulder becomes unstable owing to the presence of compressive trans- verse stresses. The unconstrained stretching of the sheet metal under compression seems to be the main cause for the wrink- ling at the draw wall. In order to compare the results for the three different die gaps, the ratio H9252 of the two principal strains is introduced, H9252 being H9280 min /H9280 max , where H9280 max and H9280 min are the major and the minor principal strains, respectively. Hosford and Caddell 5 have shown that if the absolute value of H9252 is greater than a critical value, wrinkling is supposed to occur, and the larger the absolute value of H9252, the greater is the possibility of wrinkling. The H9252 values along the cross-section MN at the same drawing height for the three simulated shapes with different die gaps, as marked in Fig. 4, are plotted in Fig. 5. It is noted from Fig. 5 that severe wrinkles are located close to the corner and fewer wrinkles occur in the middle of the draw wall for all three different die gaps. It is also noted that the bigger the die gap, the larger is the absolute value of H9252. Consequently, increasing the die gap will increase the possibility of wrinkling occurring at the draw wall of the tapered square cup. 3.2 Effect of the Blank-Holder Force It is well known that increasing the blank-holder force can help to eliminate wrinkling in the stamping process. In order to study the effectiveness of increased blank-holder force, the stamping of a tapered square cup with die gap of 50 mm, which is associated with severe wrinkling as stated above, was simulated with different values of blank-holder force. The blank-holder force was increased from 100 kN to 600 kN, which yielded a blank-holder pressure of 0.33 MPa and 1.98 MPa, respectively. The remaining simulation conditions are maintained the same as those specified in the previous section. An intermediate blank-holder force of 300 kN was also used in the simulation. The simulation results show that an increase in the blank- holder force does not help to eliminate the wrinkling that occurs at the draw wall. The H9252 values along the cross-section Fig. 5. H9252-value along the cross-section MN for different die gaps. 256 F.-K. Chen and Y.-C. Liao MN, as marked in Fig. 4, are compared with one another for the stamping processes with blank-holder force of 100 kN and 600 kN. The simulation results indicate that the H9252 values along the cross-section MN are almost identical in both cases. In order to examine the difference of the wrinkle shape for the two different blank-holder forces, five cross-sections of the draw wall at different heights from the bottom to the line M N, as marked in Fig. 4, are plotted in Fig. 6 for both cases. It is noted from Fig. 6 that the waviness of the cross-sections for both cases is similar. This indicates that the blank-holder force does not affect the occurrence of wrinkling in the stamp- ing of a tapered square cup, because the formation of wrinkles is mainly due to the large unsupported area at the draw wall where large compressive transverse stresses exist. The blank- holder force has no influence on the instability mode of the material between the punch head and the die cavity shoulder. 4. Stepped Rectangular Cup In the stamping of a stepped rectangular cup, wrinkling occurs at the draw wall even though the die gaps are not so significant. Figure 1(b) shows a sketch of a punch shape used for stamping a stepped rectangular cup in which the draw wall C is followed by a step DE. An actual production part that has this type of geometry was examined in the present study. The material used for this production part was 0.7 mm thick, and the stress strain relation obtained from tensile tests is shown in Fig. 3. The procedure in the press shop for the production of this stamping part consists of deep drawing followed by trimming. In the deep drawing process, no draw bead is employed on the die surface to facilitate the metal flow. However, owing to the small punch corner radius and complex geometry, a split occurred at the top edge of the punch and wrinkles were found to occur at the draw wall of the actual production part, as shown in Fig. 7. It is seen from Fig. 7 that wrinkles are distributed on the draw wall, but are more severe at the corner edges of the step, as marked by AD and BE in Fig. 1(b). The metal is torn apart along the whole top edge of the punch, as shown in Fig. 7, to form a split. In order to provide a further understanding of the defor- mation of the sheet-blank during the stamping process, a finite- element analysis was conducted. The finite-element simulation was first performed for the original design. The simulated shape of the part is shown from Fig. 8. It is noted from Fig. 8 that the mesh at the top edge of the part is stretched Fig. 6. Cross-section lines at different heights of the draw wall for different blank-holder forces. (a) 100 kN. (b) 600 kN. Fig. 7. Split and wrinkles in the production part. Fig. 8. Simulated shape for the production part with split and wrinkles. significantly, and that wrinkles are distributed at the draw wall, similar to those observed in the actual part. The small punch radius, such as the radius along the edge AB, and the radius of the punch corner A, as marked in Fig. 1(b), are considered to be the major reasons for the wall breakage. However, according to the results of the finite- element analysis, splitting can be avoided by increasing the above-mentioned radii. This concept was validated by the actual production part manufactured with larger corner radii. Several attempts were also made to eliminate the wrinkling. First, the blank-holder force was increased to twice the original value. However, just as for the results obtained in the previous section for the drawing of tapered square cup, the effect of blank-holder force on the elimination of wrinkling was not found to be significant. The same results are also obtained by increasing the friction or increasing the blank size. We conclude that this kind of wrinkling cannot be suppressed by increasing the stretching force. Since wrinkles are formed because of excessive metal flow in certain regions, where the sheet is subjected to large com- pressive stresses, a straightforward method of eliminating the wrinkles is to add drawbars in the wrinkled area to absorb the redundant material. The drawbars should be added parallel to the direction of the wrinkles so that the redundant metal can be absorbed effectively. Based on this concept, two drawbars are added to the adjacent walls, as shown in Fig. 9, to absorb the excessive material. The simulation results show that the Draw-Wall Wrinkling in a Stamping Die Design 257 Fig. 9. Drawbars added to the draw walls. wrinkles at the corner of the step are absorbed by the drawbars as expected, however some wrinkles still appear at the remain- ing wall. This indicates the need to put more drawbars at the draw wall to absorb all the excess material. This is, however, not permissible from considerations of the part design. One of the advantages of using finite-element analysis for the stamping process is that the deformed shape of the sheet blank can be monitored throughout the stamping process, which is not possible in the actual production process. A close look at the metal flow during the stamping process reveals that the sheet blank is first drawn into the die cavity by the punch head and the wrinkles are not formed until the sheet blank touches the step edge DE marked in Fig. 1(b). The wrinkled shape is shown in Fig. 10. This provides valuable information for a possible modification of die design. An initial surmise for the cause of the occurrence of wrink- ling is the uneven stretch of the sheet metal between the punch corner radius A and the step corner radius D, as indicated in Fig. 1(b). Therefore a modification of die design was carried out in which the step corner was cut off, as shown in Fig. 11, so that the stretch condition is changed favourably, which allows more stretch to be applied by increasing the step edges. However, wrinkles were still found at the draw wall of the cup. This result implies that wrinkles are introduced because of the uneven stretch between the whole punch head edge and the whole step edge, not merely between the punch corner and Fig. 10. Wrinkle formed when the sheet blank touches the stepped edge. Fig. 11. Cut-off of the stepped corner. the step corner. In order to verify this idea, two modifications of the die design were suggested: one is to cut the whole step off, and the other is to add one more drawing operation, that is, to draw the desired shape using two drawing operations. The simulated shape for the former method is shown in Fig. 12. Since the lower step is cut off, the drawing process is quite similar to that of a rectangular cup drawing, as shown in Fig. 12. It is seen in Fig. 12 that the wrinkles were eliminated. In the two-operation drawing process, the sheet blank was first drawn to the deeper step, as shown in Fig. 13(a). Sub- sequently, the lower step was formed in the second drawing operation, and the desired shape was then obtained, as shown in Fig. 13(b). It is seen clearly in Fig. 13(b) that the stepped rectangular cup can be manufactured without wrinkling, by a two-operation drawing process. It should also be noted that in the two-operation drawing process, if an opposite sequence is applied, that is, the lower step is formed first and is followed by the drawing of the deeper step, the edge of the deeper step, as shown by AB in Fig. 1(b), is prone to tearing because the metal cannot easily flow over the lower step into the die cavity. The finite-element simulations have indicated that the die design for stamping the desired stepped rectangular cup using one single draw operation is barely achieved. However, the manufacturing cost is expected to be much higher for the two- operation drawing process owing to the additional die cost and operation cost. In order to maintain a lower manufacturing cost, the part design engineer made suitable shape changes, and modified the die design according to the finite-element Fig. 12.
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