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============================================喜歡這套資料就充值下載吧。。。資源目錄里展示的都可在線預(yù)覽哦。。。下載后都有，，請(qǐng)放心下載，，文件全都包含在內(nèi)，，【有疑問咨詢QQ:1064457796 或 1304139763】
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麗水學(xué)院畢業(yè)設(shè)計(jì)（論文）
開 題 報(bào) 告
（200 屆）
題 目
指導(dǎo)教師
院 系
班 級(jí)
學(xué) 號(hào)
姓 名
二〇〇 年 月 日
一、選題的意義
此工件為簡(jiǎn)單的沖壓件，設(shè)計(jì)此課題為了了解
模具沖壓的工序及設(shè)計(jì)要求，讓我全面認(rèn)識(shí)沖
壓模具的結(jié)構(gòu)。
二、研究的主要內(nèi)容，擬解決的主要問題（闡述的主要觀點(diǎn)）
模具沖壓如何實(shí)現(xiàn)落料，拉深,沖孔等工序的。
每個(gè)工序之間有合聯(lián)系，他們要怎么相互完成
的及其先后順序。
本篇設(shè)計(jì)只設(shè)計(jì)了落料拉深復(fù)合模,由于時(shí)間關(guān)系
沖孔模沒有設(shè)計(jì),在以后的工作中會(huì)進(jìn)一步熟悉所有
工序的完成.
三、研究（工作）步驟、方法及措施（思路）
工藝方案
1） 落料
2） 拉深
3） 沖φ11的孔1個(gè)
4） 翻邊
5） 沖φ6的孔φ2個(gè)及不規(guī)則形狀的孔1個(gè)
6） 鉆孔直徑2
7） 鉆矩形孔7.5x2.5
8） 锪孔φ6成φ6 .4
四、畢業(yè)論文（設(shè)計(jì)）提綱
畢業(yè)設(shè)計(jì)是每位大學(xué)生畢業(yè)之前必經(jīng)之路， 經(jīng)過了此次畢業(yè)設(shè)計(jì)，我初步了解了設(shè)計(jì)模具的各道工序，清楚了模具的各個(gè)結(jié)構(gòu)，了解了各個(gè)設(shè)計(jì)過程中的重要環(huán)節(jié)，具備了一定的設(shè)計(jì)能力，學(xué)到了真正的實(shí)踐知識(shí)，但這還不夠，在以后的工作中，還要繼續(xù)努力的為中國(guó)的模具設(shè)計(jì)與制造水平上升而努力。
五、主要參考文獻(xiàn)
1肖景容 姜奎華編的《沖壓工藝學(xué)》北京：機(jī)械加工出版社會(huì)性 1999。
2王孝培主編《沖壓手冊(cè)》第二版 北京 機(jī)械工業(yè)出版社。
3王芳主編《冷沖壓模具設(shè)計(jì)手冊(cè)》 北京 機(jī)械工業(yè)出版社。
指導(dǎo)教師意見：
簽名：
年 月 日
系畢業(yè)設(shè)計(jì)（論文）工作指導(dǎo)小組意見：
簽名：
年 月 日
二級(jí)學(xué)院(直屬系)畢業(yè)設(shè)計(jì)（論文）工作領(lǐng)導(dǎo)小組意見：
簽名：
年 月 日
5
畢業(yè)設(shè)計(jì)（論文）任務(wù)書
題 目 箱殼落料拉深模設(shè)計(jì)
起 止 時(shí) 間 2006年3月—2006年6月
學(xué) 生 姓 名
專 業(yè) 班 級(jí)
學(xué) 號(hào)
指 導(dǎo) 老 師
教研室主任
2006年5月25日
計(jì) 算 內(nèi) 容
說 明
目 錄
一、 設(shè)計(jì)任務(wù)書…………………………………………………
二、 工藝分析……………………………………………………
三、 工藝方案的確定……………………………………………
四、 工作原理……………………………………………………
五、 工藝設(shè)計(jì)……………………………………………………
六、 模具結(jié)構(gòu)設(shè)計(jì)………………………………………………
七、 總結(jié)…………………………………………………………
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設(shè)計(jì)任務(wù)書
1箱殼零件圖
2落料拉伸復(fù)合模裝配圖
3全體模具零件圖
4設(shè)計(jì)說明書
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工藝分析
1該產(chǎn)品的基本工序?yàn)槁淞?、沖孔。
2它對(duì)零件尺寸公差特殊要求，遷用IT12級(jí)，利用普通話加工方式可達(dá)到圖樣要求。
3重視模具材料和結(jié)構(gòu)的選擇，保證有一定的模具壽命。
工件的極限偏差
尺寸 凸模偏差 凹模偏差
58 -0.020 +0.030
88 -0.025 +0.025
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工藝方案的確定
根據(jù)制件工藝分析，其基本工序有落料、沖孔。完成箱殼的設(shè)計(jì)，需要的工序有：
1） 落料
2） 沖φ11的孔1個(gè)
3） 沖φ6的孔2個(gè)及不規(guī)則形狀的孔1個(gè)
4） 锪孔φ6成φ6 .4
5） 鉆孔φ2
6） 鉆矩形孔7.5x2.5
7） 拉深
8） 翻邊
根據(jù)這些工序，可得到如下幾種方案
方案一
1） 落料
2） 沖φ11的孔1個(gè)
3） 翻邊
4） 拉深
5） 沖φ6的孔φ2個(gè)及不規(guī)則形狀的孔1個(gè)
6） 鉆孔φ2
7） 鉆矩形孔7.5x2.5
8） 锪孔φ6成φ6 .4
方案二
1） 落料
2） 沖φ6的孔φ2個(gè)及不規(guī)則形狀的孔1個(gè)
3） 拉深
4） 沖φ11的孔1個(gè)
5） 翻邊
6） 鉆孔φ2
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方案三
1） 落料
2） 拉深
3） 沖φ11的孔1個(gè)
4） 翻邊
5） 沖φ6的孔φ2個(gè)及不規(guī)則形狀的孔1個(gè)
6） 鉆孔直徑2
7） 鉆矩形孔7.5x2.5
8） 锪孔φ6成φ6 .4
綜合以上三種方案，方案三最合理。采用三種模具即可解決一些問題，第一種是落料拉深模，第二種沖孔翻邊模，第三種是沖裁模，故選擇的是落料拉伸模。
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工作原理
首先由壓力機(jī)帶動(dòng)模柄，模柄再帶動(dòng)上模座下行，上模座帶著凸凹模下行，凸凹模與落料凹模完成落料的動(dòng)作，凸凹模繼續(xù)下行，拉深凹將條料拉入凸凹模，完成拉深動(dòng)作過程，再由頂桿帶動(dòng)壓邊圈拉制件頂出。
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工藝設(shè)計(jì)
1、尺寸的確定
已知b1=88 b=58 t=1.2 r底=6 r1=3.8 r2=7.3 h0=28
r1/b=3.8/58=0.066
h0/b=28/58=0.483
由圖4—72查得該件屬 區(qū)的低矩形件，又根據(jù)t/bx100=1.2/58x100=2.172 ，可按表4—33所得的第一種方法計(jì)算。
1） 選取修邊余量h，確定矩形件的計(jì)算高度。
當(dāng)h0/r1=28/3.8=7.368
Δh=0.5h0/r1=0.5x7.368=3.684(mm)
h=h0+Δh=28+3.684=31.684(mm)
2） 假想毛坯尺寸直徑。
D=1.13
=112.418mm
3） 毛坯長(zhǎng)度
r=D+(b1-b)=112.418+(88-58)=142.418(mm)
4） 毛坯寬度
K=D-(b-2r1)+【b-2x（h-0.43xr底）】（b1-b）/（b1-2r）
=112.418x(58-2x3.8)+【58+2x（31.684-0.43X6）】（88-58）/（88-2x3.8）
=113.832mm
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5） 毛坯直徑
R=0.5K=0.5x113.832=56.916(mm)
圓整毛坯直徑為11.25mm。毛坯長(zhǎng)度為142.5mm,毛坯寬度為114mm。毛坯半徑為57mm。
6） 毛坯尺寸如下圖示：
由h0/b=28/58=0.483<0.7~0.8
這屬于低盒件拉深。
M=r/R=3.8/57=0.067
毛坯相對(duì)厚度t/bx100=1.2/58x100=2.1
查表相4-27得
m1=0.050
m>m1
所以屬于一次拉深成形。
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2、確定排樣方式和計(jì)算材料利用率。
上圖的毛坯形狀和尺寸較大，為便于手工送料，選用單排沖壓，有兩種排樣方式如圖示。
經(jīng)過分析計(jì)算：（a）的排樣方式，材料利用率最高。
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3、搭邊值的確定
由于工藝所采用的送料方式為手工送料，且為非圖形，查表2-17得
a=2.5mm a1=2mm
4、沖壓設(shè)備的選擇，
由于本套模具為落料拉伸模，計(jì)算參數(shù)如下：
1） 落料力
F落=1.3Lτz
將t=1.2mm及08鋼材料的搞剪強(qiáng)度τ=260Mpa代入上式，得
F落=1?.3x(2xπx57+30x2)x260
=122849.99N
2） 推件力
F推=nF落k1
n=1,k1查表2-10得k1=0.035代入得：
F推=1x122849.99x0.035
=4299.750N
F總=F落+F推=127149.74N
根據(jù)壓力，可選用160的開式雙柱可傾壓力機(jī)。
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根據(jù)資料得其主要參數(shù)及大小如下：
最大沖壓力 160KN
滑塊行程 70mm
滑塊行程次數(shù) 120次/min
最大封閉高度 220mm
封閉高度調(diào)節(jié)量 45mm
工作臺(tái)尺寸 300mmx450mm
模柄尺寸 直徑40x60
5、落料拉深先后的確定
F0=127149.7 4
拉深力
F拉=(2b1+2b-1.72r)tδbk4
查表4-23得k4=0.7
δb=420Mpa代入公式得
F拉=(2x88+2x58-1.72x6)x1.2x420x0.7
=104376.704
所以F總>F拉
所以本復(fù)合模為先沖裁后拉深
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模具結(jié)構(gòu)設(shè)計(jì)
1凹模的設(shè)計(jì)
1） 模的材料選Cr12，凹模是在強(qiáng)壓連續(xù)使用和有很大沖壓力的條件下工作臺(tái)的，且伴有溫度的升高，工作條件惡劣，要求凹模材料有好的耐磨性，耐沖擊性，淬透性和切耐性。
2） 凹模的硬度要求較高，一般應(yīng)進(jìn)行淬為熱處理，使其硬度達(dá)到期HRC58-62。
3） 凹模設(shè)計(jì)的結(jié)構(gòu)如下圖所示：
4）刃口尺寸的確定
由表尺寸2-23表得
Zmax=0.180
Zmin=0.126
Zmax-Zmin=0.180-0.126=0.054
根據(jù)表2-32表得
A凹=（A-xΔ）+0δ凹
根據(jù)表2-30得
x=0.75 Δ=0.4
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則： A凹1=（58-0.75x0.4） 0+0.030=57.70+0.030
A凹2=（88-0.75x0.4）+00.035=87.70+0.035
5）、強(qiáng)度的校核
凹模強(qiáng)度校核主要是栓查高度h，因?yàn)榘寄Ｏ旅娴哪Ｗ驂|板一的洞口較凹模洞口大，合凹模工作時(shí)彎曲，若凹高度不夠便會(huì)產(chǎn)生彎曲變形，以致?lián)p壞。
查表2-45得
δ彎=1.5F/h2【δ彎】
h最小=
凹模厚度 H=K6
查表2-24得K=0 .2
H=142.5x0.2=28.5mm
考慮到工件及凸凹模的影響取取H=0.32mm
【δ彎】=490Mpa
δ彎=1.5X122849.99/322=179.956Mpa<【δ彎】
經(jīng)校核，凹模強(qiáng)度足夠。
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2、凸模的設(shè)計(jì)
1） 凸模的材料為Cr12MOV
2） 凸模硬度要求低于凹模硬度，但其硬度還是較高的，要經(jīng)過回火的熱處理方法，使其硬度達(dá)到HRC56-60。
該凸模為拉深模具，且凸模的長(zhǎng)度，寬度應(yīng)根據(jù)拉深件具體結(jié)構(gòu)確定。
3） 圓角半徑 rp
rd=8t
rp=（0.6~1）rd
4） 所以該凸模圓角半徑rp為
rp=0.6x8t
=0.6x8x1.2
=6mm
5） 凸模刃口的尺寸
B凸=（B-XΔ-Z）0-δP
查表2-30得
x=0.75 Δ=0.4 Z=（1.0~1.1）t
B凸1=（58-0.75x0.4-1.2x2）0-0.020
B凸2=（88-0.75x0.4-1.2x2）0-0.025
=85.30-0.025
6） 拉深凸模出氣口的尺寸
查表4-35得：
通孔直徑d
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d=6.5mm
7） 凸模強(qiáng)度校核
δp=F/A≤【δp】
沖裁時(shí)，凸模承受的壓力，必須小于凸模材料強(qiáng)度允許的壓應(yīng)力【δp】
δp=F/A122849.99/55.3x85.3=260Mpa
δp≤【δp】=980~1569
所以凸模強(qiáng)度足夠。
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3凸凹模具的設(shè)計(jì)
1） 材料選用Cr12。
2） 熱處理硬度達(dá)到HRC58-62。
3） 凸凹模的尺寸如圖所示：
凸凹模的最小壁厚一般由經(jīng)驗(yàn)數(shù)據(jù)確定，倒裝復(fù)合凸凹模最小壁厚：對(duì)于黑色金屬和硬材料約為工件的料厚的1.5倍，但不小于0.7mm；對(duì)于有色金屬用軟材料約等于工件壁厚，但不小于0.5mm正裝復(fù)合模凸凹模的最小可參考表2-27
t=1.2
最小壁厚 3.2
最小直徑 18
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4、卸料板的設(shè)計(jì)
1） 材料為45號(hào)鋼。
2） 裝置形式如下圖所示。
5、打桿的長(zhǎng)度
考慮到墊板的高度是10mm，推板的高度是12mm，模柄的尺寸是40 x100。螺母的寬度為8mm。且需2個(gè)螺母，還需留一定的余量。所以打桿的長(zhǎng)度
L=10+12+100+2x8+10
=148mm
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6、壓邊裝置的設(shè)計(jì)
在拉深過程中，壓邊圈的作用是用來防止工件邊壁或凸緣起皺的。隨著拉深增加還需要減少的壓邊力應(yīng)減少。
t/D=1.2/112.418=1.1% m1=0.050
查表4-11 t/D<1.5% m1≤0.60
應(yīng)采用壓邊圈裝置。
壓邊力Fy=AP
查表4-27得
P=2.5-3MPa
根據(jù)設(shè)計(jì)時(shí)壓邊圈的面積為：
A=πR2+30x114=πx572+3420=13627(mm2)
Fy=22.5x13627=34067.5N
一般情況下采用彈簧墊或橡皮墊，本設(shè)計(jì)選擇橡皮墊。采用平面壓邊圈，一般拉深模中采用平面壓邊圈。
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7、頂桿的長(zhǎng)度
頂桿的長(zhǎng)度取決于工件的高度，在保證制件頂出的情況下，頂桿的長(zhǎng)度為：
L=32+45+10=87mm
取L=90mm
8、橡皮墊的設(shè)計(jì)
1）、選用的原則
為保證橡皮不致于過早失去彈性損壞，其允許最大壓縮量應(yīng)不超過其自由高度的45%
一般取h總=（0.35-0.45）h自由
故工作行程
h工作= h總- h預(yù)=（0.25-0.30）h自由
2)橡皮高度
h自由=h工作/0.25-0.30
3)橡皮的結(jié)構(gòu)形式如下圖：
D=
=132mm
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根據(jù)工件的厚度1.2mm，拉深時(shí)凸模進(jìn)入凸凹模深度為35mm，考慮模具維修時(shí)刃磨留量2mm，則總的工作行程。
H工作=1.2+35+2=38.2mm
H自由=38.2/0.25-0.30=127.3~152.8mm
取自由高度為150
h預(yù)期=(10%~15%)h自由
=15~22.5mm
取h預(yù)=22mm
模具中橡皮高度為128mm
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9、模具的選擇
根據(jù)制件的毛坯尺寸可選凹模周界為250mm，B為125mm，H為160~220mm，的后側(cè)導(dǎo)柱模深
根據(jù)模架可知
上模座 250X125X40 GB2855.5-81
下模座 250X125X45 GB2855.6-81
導(dǎo)柱 28X150 GB2861.1-81
導(dǎo)套 28X100X38 GB2861.6-81
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參考資料
1、 肖景容 姜奎華編的《沖壓工藝學(xué)》北京：機(jī)械加工出版社會(huì)性 1999。
2王孝培主編《沖壓手冊(cè)》第二版 北京 機(jī)械工業(yè)出版社。
3王芳主編《冷沖壓模具設(shè)計(jì)手冊(cè)》 北京 機(jī)械工業(yè)出版社。
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總結(jié)
畢業(yè)設(shè)計(jì)是每位大學(xué)生畢業(yè)之前必經(jīng)之路， 經(jīng)過了此次畢業(yè)設(shè)計(jì)，我初步了解了設(shè)計(jì)模具的各道工序，清楚了模具的各個(gè)結(jié)構(gòu)，了解了各個(gè)設(shè)計(jì)過程中的重要環(huán)節(jié)，具備了一定的設(shè)計(jì)能力，學(xué)到了真正的實(shí)踐知識(shí)，但這還不夠，在以后的工作中，還要繼續(xù)努力的為中國(guó)的模具設(shè)計(jì)與制造水平上升而努力。
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e pos 模具工業(yè)現(xiàn)狀Process simulation in stamping – recent
applications for product and process design
Abstract
Process 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 Int'l, 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 design
1. Introduction
The 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 one's investment in presses, equipment, and tooling used in sheet forming, one may increase one's 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 Int'l). 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 – applications
The objective of this investigation was to validate FAST_FORM3D, to determine FAST_FORM3D's 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 5?in. deep 12?in. by 15?in. rectangular pan with a 1?in. flange as shown in Fig. 3. Table 1 lists the process conditions used. Romanovski's 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) Romanovski's 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 1?in. flange in the side region, while the Romanovski and FAST_FORM3D methods achieved the 1?in. 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_FORM3D's 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 – applications
In 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 excavator's 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 50?ton) 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 10?ton, wrinkling occurred in the experimental parts as shown in Fig. 11. At 30?ton, the wrinkling was eliminated as shown in Fig. 12. These experimental observations were predicted with Pam-stamp simulations as shown in Fig. 13. The 30?ton 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 10?mm. A slight neck was observed in the 30?ton panel as shown in Fig. 13. At 50?ton, an obvious fracture occurred in the panel.
Fig. 11. Wrinkling in laboratory cabin inner panel, BHF=10?ton.
Fig. 12. Deformation stages of the laboratory cabin inner and necking, BHF=30?ton.
(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=10?ton; (b) predicted geometry, BHF=30?ton.
Fig. 14. Comparison of predicted and measured material draw-in for lab cabin inner, BHF=30?ton.
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 50?ton. 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=10?ton (panel wrinkled); (b) measured strain, BHF=30?ton (panel necked); (c) measured strain, BHF =50?ton (panel fractured).
Fig. 16. FEM strain predictions for the laboratory cabin inner.
(a) Predicted strain, BHF=10?ton; (b) predicted strain, BHF=30?ton; (c) predicted strain, BHF=50?ton.
Fig. 17. Predicted effect of friction for the laboratory cabin inner, BHF=30?ton.
(a) Predicted strain, μ=0.06; (b) predicted strain, μ=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 – applications
The 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 1?Hz. It is known from previous experiments of other researchers that proper frequencies range from 5 to 25?Hz [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 μ=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