銅墊片沖壓成形工藝與模具設計【落料-沖孔復合?！?/h1>

銅墊片沖壓成形工藝與模具設計【落料-沖孔復合?！?落料-沖孔復合模,銅墊片沖壓成形工藝與模具設計【落料-沖孔復合?！?墊片,沖壓,成形,工藝,模具設計,落料,沖孔,復合 中期檢查表 學生姓名 學 號 指導教師 選題情況 課題名稱 銅墊片沖壓成形工藝與模具設計 難易程度 偏難 適中 偏易 工作量 較大 合理 較小 符合規(guī)范化的要求 任務書 有 無 開題報告 有 無 外文翻譯質(zhì)量 優(yōu) 良 中 差 學習態(tài)度、出勤情況 好 一般 差 工作進度 快 按計劃進行 慢 中期工作匯報及解答問題情況 優(yōu) 良 中 差 中期成績評定： 所在專業(yè)意見： 負責人： 2014 年 2 月 22日 設計任務書 系 部： 專 業(yè)： 學 生： 學 號： 設計題目： 銅墊片沖壓成形工藝與模具設計 起迄日期: 指導教師： 2013 年 11 月2日  畢 業(yè) 設 計 任 務 書 1．本畢業(yè)設計課題來源及應達到的目的： 在完成該課題之后，應對沖壓工藝生產(chǎn)較為熟悉，能熟練掌握相關(guān)設計手冊的使用，能獨立完成一套模具的設計及模具工作零件加工工藝的編制，能夠運用軟件完成模具裝配圖及零件圖的繪制。 2．本畢業(yè)設計課題任務的內(nèi)容和要求（包括原始數(shù)據(jù)、技術(shù)要求、工作要求等）： （1）了解目前國內(nèi)外沖壓模具的發(fā)展現(xiàn)狀； （2）工件的結(jié)構(gòu)工藝分析； （3）折彎墊片沖壓成形與模具設計，并編寫設計說明書一份； （4）繪制模具總裝圖一張，并畫出非標準零件的零件圖； （5）編制主要零件加工工藝過程卡。 原始資料：工件圖 材料：Q215 生產(chǎn)量：大批量 所在專業(yè)審查意見： 負責人： 年 月 日 系部意見： 系領(lǐng)導： 年 月 日 II 機 械 加 工 工 藝 過 程 卡 零件號 零 件 名 稱 凸模 工序號 工 序 名 稱 設 備 夾 具 刀 具 量 具 工 時 名 稱 型 號 名 稱 規(guī) 格 名 稱 規(guī) 格 名 稱 規(guī) 格 01 02 03 04 05 06 07 08 09 10 下料 鍛造 熱處理 粗車外形 精車外形 熱處理 磨外圓 拋光 鉗修 鋸床 鍛床 退火爐 車床 車床 淬火爐 磨床 油石 卡盤 卡盤 帶鋸 鍛錘 車刀 車刀 砂輪 油石 直尺 直尺 游標卡尺 千分尺 千分尺 編制 校對 審核 批準 機 械 加 工 工 序 卡 工序名稱 粗銑六面 工序號 03 零件名稱 凹模 零件號 02-11 零件重量 同時加工零件數(shù) 1 材 料 毛 坯 牌 號 硬 度 種 類 重 量 Cr12 48---52HRC 鍛 件 設 備 夾 具 名 稱 輔 助 工 具 名 稱 型 號 銑床 虎鉗 墊塊 安 裝 工 步 安裝及工步說明 刀 具 量 具 走 刀 長 度 走 刀 次 數(shù) 切 削 深 度 進給量 主 軸 轉(zhuǎn) 速 切 削 速 度 基 本 工 時 二次 2 銑上、下平面 30面銑刀 游標卡尺 5 0.2mm 200㎜/ min 2000r/min 二次 1 銑四周面 10立銑刀 游標卡尺 2 0.5mm 60㎜/ min 2000r/mi 設 計 者 指 導 教 師 共 頁 第 頁 設計說明書 畢業(yè)設計題目：銅墊片沖壓成形工藝與模具設計 系 部 專 業(yè) 班 級 學生姓名 學 號 指導教師 2014年4月16日 銅墊片沖壓成形工藝與模具設計 摘要：本設計題目為墊片沖裁模，體現(xiàn)了典型沖裁模的設計要求、內(nèi)容及方向，有一定的設計意義。通過對該模具的設計，加強了設計者對沖裁模設計基礎(chǔ)知識的理解和運用，為設計更復雜的沖裁模具做好了鋪墊。 本設計運用沖裁工藝及模具設計的基礎(chǔ)知識，首先分析了板材的性能要求，為選取模具的類型做好了準備；然后計算了沖裁件的沖裁力，便于選取壓力機噸位及確定壓力機型號；最后分析了沖裁件的特征，便于確定模具的設計參數(shù)、設計要點及卸件裝置。 本設計采用了沖孔—落料復合模成形墊片。成形原理可劃分為三個階段：首先沖孔凸模與凹模共同作用先沖出四個5mm，而后利用第一步?jīng)_出的四個5mm孔做精確定位使外形凸模與凹模共同作用使工件落料成形，最后一步是進行折彎。 關(guān)鍵詞：沖孔—落料復合模 沖孔凸模 凹模 壓力機噸位 Abstract：The topic for the design is pad blanking die design,It has manifested the typical blanking dies design request, the content and the direction, has certain design significance.Through the design of the component mold, strengthens the designer’s understand and utilize to the blanking die design basical knowledge,has prepareed for designing more complex blanking die. The design has utilize blanking craft and the basical knowledge of the mold design, has first analyzed the property requirement of the plate , has prepared for selecting the mold type；then has calculated the blanking strength,has advantaged to select the press tonnage and determine press model; Finally has analyzed the characteristic of the products, has advantaged to finite the mold design variable,the design main point and shedder. This design used piercing and blanking progressive die to form the products.The forming principle can be divided to two stages: First, piercing punch and die affect together and pierce four holes of3.2mm and one hole of8.5mm,then use the four holes and the one hole as pinpoint to make the product formed. Key word: Piercing and blanking progressive die Piercing punch Press Tonnage II 設計評語 學生姓名： 班級: 學號: 題 目： 銅墊片沖壓成形工藝與模具設計 綜合成績： 指導者評語： 1）該同學工作態(tài)度不夠認真，能基本完成畢業(yè)設計任務； 2）該同學制訂出了較合理的沖壓模具結(jié)構(gòu)； 3）該同學設計說明書內(nèi)容比較完整，計算較正確，格式一般； 4）該同學裝配圖、零件圖設計比較合理，視圖表達正確； 5）可以提交答辯。 指導者(簽字)： 年 月 日 畢業(yè)設計評語 評閱者評語： 該同學畢業(yè)設計任務來自生產(chǎn)實際，工作量大小適中，能夠按照要求完成設計說明書的撰寫，零件圖上存在較多問題，建議成績評定為及格，可以提交答辯。 評閱者(簽字)： 年 月 日 答辯委員會（小組）評語： 答辯委員會（小組）負責人(簽字)： 年 月 日 1 緒論 1.1國內(nèi)模具的現(xiàn)狀 我國模具近年來發(fā)展很快，據(jù)不完全統(tǒng)計，2003年我國模具生產(chǎn)廠點約有2萬多家，從業(yè)人員約50多萬人，2004年模具行業(yè)的發(fā)展保持良好勢頭，模具企業(yè)總體上訂單充足，任務飽滿，2004年模具產(chǎn)值530億元。進口模具18.13億?美元，出口模具4.91億美元，分別比2003年增長18%、32.4%和45.9%。進出口之比2004年為3.69:1，進出口相抵后的進凈口達13.2億美元，為凈進口量較大的國家。 在2萬多家生產(chǎn)廠點中，有一半以上是自產(chǎn)自用的。在模具企業(yè)中，產(chǎn)值過億元的模具企業(yè)只有20多家，中型企業(yè)幾十家，其余都是小型企業(yè)。?近年來，?模具行業(yè)結(jié)構(gòu)調(diào)整和體制改革步伐加快，主要表現(xiàn)為：大型、精密、復雜、長壽命中高檔模具及模具標準件發(fā)展速度快于一般模具產(chǎn)品；專業(yè)模具廠數(shù)量增加，能力提高較快；"三資"及私營企業(yè)發(fā)展迅速；國企股份制改造步伐加快等。 1.2　國內(nèi)模具的發(fā)展趨勢 巨大的市場需求將推動中國模具的工業(yè)調(diào)整發(fā)展。雖然我國的模具工業(yè)和技術(shù)在過去的十多年得到了快速發(fā)展，但與國外工業(yè)發(fā)達國家相比仍存在較大差距，尚不能完全滿足國民經(jīng)濟高速發(fā)展的需求。未來的十年，中國模具工業(yè)和技術(shù)的主要發(fā)展方向包括以下幾方面:???? 1） 模具日趨大型化；??? ? 2）在模具設計制造中廣泛應用CAD/CAE/CAM技術(shù)；?? ? 3）模具掃描及數(shù)字化系統(tǒng)；??? ? 4）在塑料模具中推廣應用熱流道技術(shù)、氣輔注射成型和高壓注射成型技術(shù)；? ??5）提高模具標準化水平和模具標準件的使用率；??? 6）發(fā)展優(yōu)質(zhì)模具材料和先進的表面處理技術(shù)；??? 7）模具的精度將越來越高；? ? 8）模具研磨拋光將自動化、智能化；?? ??9）研究和應用模具的高速測量技術(shù)與逆向工程；?? ?10）開發(fā)新的成形工藝和模具。 1.3國外模具的現(xiàn)狀和發(fā)展趨勢 模具是工業(yè)生產(chǎn)關(guān)鍵的工藝裝備，在電子、建材、汽車、電機、電器、儀器儀表、家電和通訊器材等產(chǎn)品中，60％－80％的零部件都要依靠模具成型。用模具生產(chǎn)制作表現(xiàn)出的高效率、低成本、高精度、高一致性和清潔環(huán)保的特性，是其他加工制造方法所無法替代的。模具生產(chǎn)技術(shù)水平的高低，已成為衡量一個國家制造業(yè)水平高低的重要標志，并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。近幾年，全球模具市場呈現(xiàn)供不應求的局面，世界模具市場年交易總額為600～650億美元左右。美國、日本、法國、瑞士等國家年出口模具量約占本國模具年總產(chǎn)值的三分之一。? 國外模具總量中,大型、精密、復雜、長壽命模具的比例占到50%以上；國外模具企業(yè)的組織形式是"大而專"、"大而精"。2004年中國模協(xié)在德國訪問時，從德國工、模具行業(yè)組織--德國機械制造商聯(lián)合會（VDMA）工模具協(xié)會了解到，德國有模具企業(yè)約5000家。2003年德國模具產(chǎn)值達48億歐元。其中（VDMA）會員模具企業(yè)有90家，這90家骨干模具企業(yè)的產(chǎn)值就占德國模具產(chǎn)值的90%，可見其規(guī)模效益。 隨著時代的進步和技術(shù)的發(fā)展，國外的一些掌握和能運用新技術(shù)的人才如模具結(jié)構(gòu)設計、模具工藝設計、高級鉗工及企業(yè)管理人才，他們的技術(shù)水平比較高．故人均產(chǎn)值也較高．我國每個職工平均每年創(chuàng)造模具產(chǎn)值約合1萬美元左右，而國外模具工業(yè)發(fā)達國家大多15～20萬美元，有的達到 25～30萬美元。 2 沖孔落料的模具設計 2.1工件圖及技術(shù)要求 1.零件名稱：銅墊片 2.材 料：H62 3.材料厚度：0.5mm 4.未注公差按14級 5.批量生產(chǎn) 2.2 任務要求 1． 完成制件工藝性分析，確定制件成形工藝方案。 2． 完成模具裝配圖設計，繪制模具總裝圖。 3． 完成模具零件圖設計，繪制模具零件圖。 4． 撰寫畢業(yè)設計說明書。 2.3沖壓件工藝性分析： 2.3.1結(jié)構(gòu)工藝性分析 1.）該工件形狀簡單，規(guī)則，使用單次沖裁 2.)該沖件處有尖角，但圖紙上無特殊要求，用圓角過渡 3.)沖件無懸臂和狹槽 4.)最小孔邊距為（4-1.5）/2=1.25>1.5t，孔與孔之間的距離3.3-0.75-0.5=2.05>t,合理 5.)沖裁件端部帶圓弧，因為該材料比較軟，所以不會出現(xiàn)臺階 6.)受凸模強度和剛度限制，沖裁件上的孔不能太小。因為最小孔d=1>0.9t,所以合理 2.3.2公差和表面粗糙分析 1.) 該工件最小公差尺寸為φ1，上公差為+0.12,下公差為0，查的精度等級為IT12級，復合模沖孔能達到9級，落料能達到10級。 2.) 表面粗糙度，圖紙未作特殊要求 3.) 沖裁材料H62，沖裁性能比較好，適合沖裁 2.4工藝方案制定 1. 采用單沖模，分別做兩副模具，沖孔模與落料模，但這樣操作制件兩次定位精度低，兩副模具經(jīng)濟成本不高但模具壽命相對也較低，但需要勞動力多，管理成本多，分攤在單件上的成本較高，生產(chǎn)操作不安全。 2. 采用級進模即將沖孔和落料分成兩個不同工位但裝在同一副模具上同時完成不同工序沖裁，這種方法能使沖件精度較高，但是不適合批量生產(chǎn)，而且制造成本比較高。 3.采用復合模即沖孔和落料同時進行，一次定位能提高沖件精度且模具結(jié)構(gòu)相對簡單，制作費用較低，勞動力需求少，適合批量生產(chǎn)，制造成本一般。 結(jié)論：綜合以上的比較，選擇復合模工藝方案比較可行，符合各方面要求 3 沖壓零件主要參數(shù)的計算 3.1搭邊值的確定和條料寬度的確定 查課本表格2-6得普通沖裁的塔邊值，材料厚0.5mm，彈壓卸料，工件寬度L小于50毫米，即a=1.0,a1=1.2 由表2-7得剪料公差為0.4，條料寬度為27.9mm,材料利用率87% 3.2 壓力中心及沖壓力計算 a.)沖裁力：Fp=1.3*68.01*0.5*225=9946.5N b.)卸料力：FQ=0.04*9946.5=397.86N c.)推件力：查表2-10得凹模刃口高h=4 FQ1=0.05*9946.5*4/0.5=3978.6N 采用彈壓卸料和下出件裝置： FΣ=9946.5+397.86+3978.6=14322.96N d.)壓力中心計算： 沖孔 O 0 (0, 0) L0=4.71 O 2 (3.3,0) L2=3.14 落料 O 1 (2.3,0) L1=6.28 O3 (7.4 ,2 ) L3=15.5 O4 (7.4 ,-2) L4=15.5 O5 (19.2,2.7) L5=5 O6 (19.2,-2.7) L6=5 O7 (22.5,2.4) L7=1.6 O8 (22.5, 1.8) L8=1.6 O9 (22.5,-1.8) L9=1.6 O10 (22.5,-2.4) L10=1.6 X0=4.71*0+3.14*3.3+6.28*2.3+15.5*7.4+15.5*7.4+5*19.2+5*19.2+1.6*22.5+1.6*22.5+1.6*22.5+1.6*22.5/61.53≈13 Y0=0 即壓力中心為（13，0） 3.3壓力機標準公稱壓力確定 P大于等于（1.1~1.3）F總=（1.1~1.3）*14KN=(15.4~18.2)KN 根據(jù)表2-2得選擇壓力機為開式壓力機，公稱壓力為100KN，壓力機型號為J-23-10 主要技術(shù)參數(shù)為： 3.4凹模周界尺寸計算和模具典型結(jié)構(gòu)選擇 1.）計算凹模周界L*B： 外形尺寸按下式計算：L=2(L1+L2) 式中，L1為壓力中心到最遠型孔的壁距離，按照孔型的布置，凹模的外形尺寸L1分別為L1（平行）=12.75 垂直與送料方向的凹模外形最遠壁間距 L2（垂直）=2.7 由表2-9查得L2=20 垂直送料方向的凹模外形尺寸 L垂直=2*（12.75+20）=65.5 平行送料方向的凹模外形尺寸 L平行=2* (2.7+20)=58 L（垂直）=65.5大于L（平行）=58 所以該模具送料方向為縱向送料 由從向送料，彈壓卸料而選擇典型組合，查手冊的L*B=80*80 g.沖裁凸凹模刃口尺寸計算 凸凹?？紤]用配作法 查表2-13 : =0.09t=0.09*0.5=0.045mm =0.12t=0.12*0.5=0.06mm △ Z=-=0.06-0.045=0.015mm =△/4 尺寸Ⅰ：φ1.5沖孔磨后變小 IT14 △=0.25 x=0.5 =0.25/4=0.0625 b凸=(1.5+0.5*0.25)0-0.06=1.63 0-0.06 沖孔凹模按照凸模在最小間隙與最大間隙制件配做 尺寸Ⅱ：φ1 0+0.12 沖孔磨后變小 IT12 △=0.12 x=0.75 =0.12/4=0.03 b凸=(1+0.75*0.12)0-0.03 =1.09 0-0.03 沖孔凹模按照凸模在最小間隙與最大間隙制件配做 尺寸Ⅲ：R2 落料后變大 IT14 △=0.25 x=0.5 =0.25/4=0.06 B凹=(2-0.5*0.25) 0+0.06 =1.88 0+0.06 落料凸模按照凹模在最小間隙與最大間隙之間配做 尺寸Ⅳ：4 0-0.16 落料后變大 IT12 △=0.16 x=0.75 =0.16/4=0.04 B凹=（4-0.75*0.16）0+0.04 =3.88 0+0.04 落料凸模按照凹模在最小間隙與最大間隙之間配做 尺寸Ⅴ：19 0-0.24 落料磨后變大 IT12 △=0.24 x=0.75 =0.24/4=0.06 B凹=(19-0.75*0.24) 0+0.06 =18.82 0+0.06 落料凸模按照凹模在最小間隙與最大間隙之間配做 尺寸Ⅵ： 6.5 0-0.2 落料后變大 IT12 △=0.2 x=0.75 =0.2/4=0.05 B凹=(6.5-0.75*0.2) 0+0.05 =6.35 0+0.05 落料凸模按照凹模在最小間隙與最大間隙之間配做 尺寸Ⅶ：5 0-0.16 落料后變大 IT12 △=0.16 x=0.75 =0.16/4=0.04 B凹=(5-0.75*0.16) 0+0.04 =4.88 0+0.04 落料凸模按照凹模在最小間隙與最大間隙之間配做 尺寸Ⅷ：5.4 0-0.1 落料后變大 IT12 △=0.1 x=0.75 =0.1/4=0.03 B凹=(5.4-0.75*0.1) 0+0.03 =5.33 0+0.03 落料凸模按照凹模在最小間隙與最大間隙之間配做 尺寸Ⅸ：2.3 落料后變大 IT14 △=0.25 x=0.5 =0.25/4=0.06 B凹=(2.3-0.5*0.25) 0+0.06 =2.18 0+0.06 落料凸模按照凹模在最小間隙與最大間隙之間配做 尺寸Ⅹ：30+0.12 落料后變小 IT12 △=0.12 x=0.75 =0.12/4=0.03 B凹=(3+0.75*0.12)0-0.03 =3.09 0-0.03 落料凸模按照凹模在最小間隙與最大間隙之間配做 尺寸Ⅺ: 4.2±0.1 磨后尺寸不變 IT13 △=0.2 x=0.75 =0.2/4=0.05 C凸=C凹=(4.1+0.1) ±0.2/8=4.2±0.03 尺寸Ⅻ：3.3 磨后尺寸不變 IT14 △=0.3 x=0.5 =0.3/4=0.08 C凸=C凹=(3.3+0.15)±0.3/8=3.45±0.04 3.5選擇標準模架 由于沖件精度要求不高，選擇對角到導柱的模架，該模架適合橫，縱送料方向 h.彈簧選擇 F卸/4=P’ *Fx 398/4=p *Fx 根據(jù)手冊查表1的取矩形界面符合彈簧 即，選擇25*90的規(guī)格 1導柱 2下模座 3下固定板 4凸凹模 5彈壓卸料板 6擋料銷 7上模座 8上墊板 9 浮動模柄 10 調(diào)節(jié)螺釘 11 壓板 12 橡膠 13 螺釘 14 上固定板 15 中墊板 16 落料凹模17 導套 18頂桿 19 推板 20 沖孔凸模 結(jié)構(gòu)特點： 模具導向：制件精度不高，采用對角導柱，用導柱12滑動導套8導向定位 卸料：卸料板5不僅起卸料作用，同時可導向凸模的作用。卸料板材料為45鋼，不熱處理仍符合各項要求 模具結(jié)構(gòu)小，凹模采用整體結(jié)構(gòu)；凸模用鉚接式固定 凸模選用Cr12MoV制作，熱處理58~62HRC，耐磨損 制件精度不高，對模具定位精度也不高，擋料銷定位擋料，正確，方便 凸模固定板采用Q235，凹模采用Cr12Mov熱處理60~64HRC，上、下模用HT250制作，經(jīng)調(diào)質(zhì) 導柱、導套，采用20鋼熱處理58~64（滲碳） 凸模，固定板型腔，凹模，卸料板，采用快絲切割 沖模工作過程 將條料校平送入工作范圍，擋料銷定位，壓力機滑塊下行上模座向下運動卸料板將條料壓平至凹模上，然后模具向上運動條料被卸料板卸下，推板推料，順利完成沖壓工序 設計小結(jié) 此課題來的比較晚，本來想放棄做畢業(yè)設計，因為我是委培生，原因很多，畢業(yè)證書不能拿到，工作的忙碌，路途的遙遠，但后來想想，以上的原因也不能成為什么，大學三年，也應該有所成就，最后決定還是給自己一個交代，認認真真完成這樣一生只有一次的畢業(yè)設計。 拿到課題，分析之后發(fā)現(xiàn)，將要設計的是一副復合沖裁模，這樣一來，在公司實習的東西，就只能用到一點點，我是學級進模的，相對來說，復合模應該是在這之前所需要經(jīng)過的一個階段，而在公司我沒去學過單沖模，所以所需的一切我必須從以前的課本和記憶中尋找。 參看典型畢業(yè)設計，讓我對設計的步驟有了一定的了解，翻閱參考書，利用一段時間進行了各類工藝分析和各個尺寸的計算，由于有一定的基礎(chǔ)，這些方面做起來也比較輕松，接下來才進入正題——模具圖的繪制 我們公司主要用的軟件是AutoCAD，所以一個設計員對CAD的操作熟練度是不可忽視的，由于經(jīng)過一個月的強化練習，我對CAD的熟練度達到了一個很高的程度，所以繪制這樣的模具的是難不到我的，我參閱課本的典型倒裝復合模，對自己的工件進行總裝圖的設計。手冊中查閱出了典型的模座布置，然后配上了各個板的大小，并且對各板的連接配上了銷釘和螺釘，我選擇的是彈簧彈壓卸料，因為我認為用彈簧卸料要比其他方式都要好，用圓擋料銷定位，推板通過頂桿推件，凸模凹模均采用Cr12Mov材料，有利于磨損。整個模具結(jié)構(gòu)簡單，模具壽命好，適合批量生產(chǎn)。 此次畢業(yè)設計，我運用了公司與學校所學知識結(jié)合，利用工作空出時間，參考各類書籍獨立完成的，由于對復合模的知識有所欠缺，難免出現(xiàn)錯誤，今后也會一一改正。然而在學習過程中，首先我明白了做學問要一絲不茍，對于出現(xiàn)的任何問題和偏差都不要輕視，要通過正確的途徑去解決，在做事情的過程中要有耐心和毅力，不要一遇到困難就打退堂鼓，只要堅持下去就可以找到思路去解決問題的。在工作中要學會與人合作的態(tài)度，認真聽取別人的意見，這樣做起事情來就可以事倍功半。 畢業(yè)設計的完成既為大學三年劃上了一個完美的句號，也為將來的人生之路做好了一個很好的鋪墊。 致謝 三年一晃而過，校園生活已成回憶。在學校里，同學老師都很照顧我。我深表感謝。這次畢業(yè)設計做的很沖忙，有太多的紕漏，請老師多多包容。 雖然我不是學校真正的學生，也不敢說為學校爭光，但我也不會替學校摸黑。 這三年，在學校學到很多專業(yè)知識，這可能就是我以后的衣食父母，我很感激。 這是在學校交的最后一份作業(yè)了，主觀上還是希望能完美結(jié)束，做到善始善終。但走出社會后，好多事情超出了自己能掌握的范圍，與本意相違背了。考慮的不夠好的希望給予指正。 參考文獻 [1]韓森和主編.冷沖壓工藝及模具設計制造.[M] 高等教育出版社.2006.2 [2]馮炳堯等.模具設計與制造簡明手冊.[M]上?？茖W技術(shù)出版社.2008.6 [3]金大鷹主編。機械制圖。[M]機械工業(yè)出版設2006.8 11 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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