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前 言
隨著模具技術(shù)的發(fā)展,模具已經(jīng)成為現(xiàn)代工業(yè)中不可缺少的工藝裝備，模具設(shè)計(jì)是工科類學(xué)校機(jī)械專業(yè)最重要的教學(xué)環(huán)節(jié)，它是我們對(duì)所學(xué)知識(shí)的綜合運(yùn)用,通過對(duì)專業(yè)知識(shí)的綜合運(yùn)用,使我們對(duì)模具從設(shè)計(jì)到制造的過程有個(gè)基本的了解,為以后的工作打下堅(jiān)定的基礎(chǔ)
畢業(yè)設(shè)計(jì)的主要目的有兩個(gè):一,讓我們掌握查閱資料與手冊的能力,能夠熟練運(yùn)用CAD進(jìn)行繪畫.二,掌握模具設(shè)計(jì)方法和步驟,了解模具的工藝過程.
本人設(shè)計(jì)的是一付復(fù)合模,對(duì)復(fù)合模的結(jié)構(gòu)與工作原理我有了一個(gè)比較清楚的了解,在這次設(shè)計(jì)過程中,我得到莫老師和室友的大力支持與幫助,在此我表示衷心的感謝.
由于我的經(jīng)驗(yàn)不足,水平有限,在本次設(shè)計(jì)中有很多錯(cuò)誤,肴望老師批評(píng)指正,以便在以后的工作中吸取教訓(xùn),本人十分感謝.
目 錄
第1章 零件的工藝分析……………………………………………2
第1.1節(jié) 制件公差要求………………………………………2
第1.2節(jié) 制件的形狀分析……………………………………2
第2章 零件工藝方案的及計(jì)算的確定……………………………2
第3章 選取模具結(jié)構(gòu)形式…………………………………………3
第4章 必要的零件結(jié)構(gòu)及計(jì)算……………………………………4
第4.1節(jié) 排樣設(shè)計(jì)與計(jì)算………………………………………4
第4.2節(jié) 各種力的計(jì)算…………………………………………5
第4.3節(jié) 壓力中心的計(jì)算及確定………………………………6
第4.4節(jié) 計(jì)算凸凹模的刃口尺寸………………………………7
第4.5節(jié) 主要零件的結(jié)構(gòu)，外形尺寸的確定及選材…………8
第5章 典型零件加工工藝分析……………………………………13
第5.1節(jié) 落料凹模的工藝分析及制造過程…………………13
第5.2節(jié) 落料反拉深凸凹的加工工藝分析…………………15
第5.3節(jié) 反拉深-正拉深凸凹模的工藝分析制………………16
第5.4節(jié) 正拉深凸模工藝分析、制定方案…………………17
第5..5節(jié) 各類板料的選材，熱處理及加工工藝過程………18
第5.6節(jié) 各類固定板的選材，熱處理及加工工藝方案……19
第6章 模具的裝配…………………………………………………26
第6.1節(jié) 組件的裝配……………………………………………26
第6.2節(jié) 模具的總裝配…………………………………………26
第1章 零件的工藝分析
1.1制件公差要求
該制件無公差要求，取自由公差，為IT14。
1.2制件的形狀分析
該零件左右對(duì)稱，轉(zhuǎn)角處呈圓角過渡，易于模具加工，減少了熱處理和沖壓時(shí)在尖角了處開裂現(xiàn)象，同時(shí)也能防止尖角處部位刃口的過快磨損。
第2章 零件工藝方案的及計(jì)算的確定
2.1 工藝方案的確定
該制件形狀簡單，對(duì)稱，尺寸精度低，適合于落料、拉深復(fù)合模。若用帶凸緣的落料拉深復(fù)合模，則轉(zhuǎn)角處會(huì)產(chǎn)生劇烈變形，極度不平整，影響制件精度和質(zhì)量要求，應(yīng)有后續(xù)工序，即需有整形工序，故采用正反二次拉深模，不僅可達(dá)制件要求，質(zhì)量好，而且經(jīng)濟(jì)性好。
2.2 拉深工藝計(jì)算
2.2.1 確定修邊余量
查表2-34（《實(shí)用模具技術(shù)手冊》）得：
?h=0, ?d=0?。
2.2.2 計(jì)算毛坯直徑
料厚t=0.8,故可以按中線計(jì)算其尺寸 ：
D=(d12+2πr2d1+8r22+4d2h+2πr1d2+4.56r12+d42-d32)1/2
其中d4=32mm,d1= d2=d3=22mm, h=16, r1=1.5,r2=1,
代入可得：D=52.9mm
2.2.3確定拉深系數(shù)
正拉深時(shí)，拉深系數(shù)越大，拉深越容易，反拉深時(shí),由于硬化程度小，可適當(dāng)考慮減速小反拉深系數(shù)，但反拉深系數(shù)又直接影響拉深-反拉深凸凹中的凸凹壁厚，反拉深系數(shù)越大，凸凹模壁厚越小，因此反拉深系數(shù)又不能太大，因此可視情況選用d=33mm,由此確定正拉深系數(shù)m1=33/52.9=0.623,m2=22/33=0.667
2.2.4中間尺寸的確定
由6-16（冷沖模設(shè)計(jì)）得h=0.25(D2/d-d)+0.43r/d(d+0.32r)
這里，D=52.9,d=22,r=1.5, 代入得h=16.1mm
由此可得制件的尺寸確定如下
第3章 選取模具結(jié)構(gòu)形式
本模具，采用上模的剛性卸料，下面采用彈簧的彈性卸料裝置，
導(dǎo)柱、導(dǎo)套保證其正確間隙。初步確定其閉模高度為130mm。
裝配草圖
第4章 必要的零件結(jié)構(gòu)及計(jì)算
4.1排樣設(shè)計(jì)與計(jì)算（所有公式，出處均選自《冷沖模設(shè)計(jì)》）：
4.1.1搭邊值的確定
由制件為圓形件確定為有廢料直排，工件間的a值及側(cè)面a1值
查表3-10，a在1.3與1.4之間，a1在1.56與1.68之間，取a=1.3,
a1=1.6。
4.1.2料步距A的確定
A=D+a=52.8+1.3=54.2mm
4.1.3確定條料寬度B
B=(D+2a1+2?a+b0)-?0=57.4-0.50
4.1.4 確定排樣圖
4.2各種力的計(jì)算：
4.2.1落料時(shí)，力的計(jì)算如下：
Fb=Ltób=πDtób(3-16)
這里，Ｄ＝52.9mm,ób=100Mp(表２-３)，t=0.8mm
代入得Ｆ=3.14*52.9*0.8*100=13288N
4.2.2拉深時(shí)，即拉深拉時(shí)力的計(jì)算
F1=Kπóbt
其中Ｋ＝０.７６（表６－１１），d=33mm,ób=100MP
F=0.76*3.14*33*0.8*100=6299N
拉深時(shí)，(t/D)*100=0.8*100/52.9=1.5
查表２－５６３（《實(shí)用模具技術(shù)手冊》）可知，此拉深不用壓邊圈套
Ｆ總＝Ｆ１=６２９９
4.2.3由力確定壓力機(jī)的選取：
模具工作過程中，沖裁力最大，壓力機(jī)也由此確定，落料階段的總沖壓力不要超過壓力機(jī)額定壓力的30%-40% ，因此壓力機(jī)的額定壓力F0大于F/（30%-40%），其中F=11354N，經(jīng)計(jì)算取F0=32440N。
又由裝配圖可以知道，選用開式壓力機(jī)，其主要參數(shù)如下次（表7-1-6〈實(shí)用模具技術(shù)手冊〉）
滑塊行程工作臺(tái) 86mm
裝模高度調(diào)節(jié)量： 35mm
壓力機(jī)的最大裝模高度： 160mm
工作臺(tái)面的最大尺寸： 220*220mm2
工作臺(tái)墊板厚度： 35mm
模柄孔尺寸： （直徑*厚度）?30*50mm2
4.3壓力中心的計(jì)算及確定
本次復(fù)合模沖模中，制件及半成品均對(duì)稱，故其壓力中心即為制件的幾何中心。
4.4計(jì)算凸凹模的刃口尺寸
4.4.1落料時(shí)：由表3-5（《沖模設(shè)計(jì)手冊》）得Zmin=0.045,Zmax=0.075,
由表3-6（《冷沖模設(shè)計(jì)》）得，凸凹模的制造偏差為
δ凹=+0.03, δ凸=-0.02
|δ凹|+|δ凸|=0.05>0.075-0.045=0.03
不滿足分別加工法對(duì)間隙和公差的要求，故用配合加工法生產(chǎn)凸凹模
D凹=（Dmax-x?）01/4Δ （3-8） （《冷沖模設(shè)計(jì)》）
這里，?=0.74, Dmax=52.9
查表3-5（《冷沖模設(shè)計(jì)》）得 x=0.5 ,代入有
D凹=52.530+0.185
至于凸模，按凹模的基本尺寸配做，保持雙面間隙為0.045-0.075
4.4.2拉深時(shí)，即反拉深時(shí)，凸凹模的刃口尺寸計(jì)算
這次拉深時(shí)，凸凹模圓角半徑的確定如下：
R凹=0.8×（D-d）1/2×t1/2=3
R凸=（0.7～1）R凹=（0.7～1）×3=2.1～3
取R凸 =2.5
D凹=（D-0.75?）0＋§凹 (6-23) 《冷沖模設(shè)計(jì)》
Ｄ凸＝（ D-0.75?-2z）-§０凸 (6-24)
這里， D=33， ?=0.62,
Z=(1-1.1)t, t=0.8,取Z=0.84
查表 3-6 得， §凹=+0.03 §凸=-0.02
代入有： D凹=32.540+0.03
Ｄ凸=30.86-0.020
4.4.3沖孔凸凹模尺寸的計(jì)算
1） 凹模厚度 按式H=Kb=38mm
根據(jù)工件尺寸即可估算凹模的外形尺寸：
長度X寬度為此45X40
2） 凸模固定板的厚度
H=0.7XH=21.1取整數(shù)為21
3） 墊板的采用與厚度：
是否采用墊板ó=F/A=450Mpa
查表得鑄鐵模板的[ó]=90-140Mpa
因此須采用墊板，墊板厚度取8
4） 計(jì)算凸模工作部分尺寸
由表查得：尺寸為20時(shí) δP=0.02
查表X=0.75
B=（20-0.75X0.02）-00.02=19.9850-0.02
凹模工作部分尺寸均按模研配，間隙極小。
4.5主要零件的結(jié)構(gòu)，外形尺寸的確定及選材
4.5.1落料凹模的選材、外邊形式確定
材料要求有耐磨性，零件材料選為T10A，熱處理硬度達(dá)60-64HRC
直接用螺釘裝在下模座上。因而凹模座有螺釘孔、銷孔。凹模洞口形狀選用圖表4-47的B圖，查表4-2，其中H取16.1mm,h取6mm,C取值使得凹模周邊達(dá)120mm，具體情況見落料凹模零件圖。
4.5.2正拉深凸模的選材，熱處理和結(jié)構(gòu)：
選取材料為T10A，熱處理達(dá)58-62HRC，凸模采用臺(tái)階式，將凸模裝入固定板內(nèi)，采用H7/m6配合。凸模長度，留有修模余量4-10，模具閉全狀態(tài)下，卸料板到凸模固定板間留有避免壓手的安全距離，另外，凸模的最小相對(duì)直徑0.75-1.20之間。具體見零件圖。
4.4.6落料反拉深凸凹模，反拉深-正拉深凸凹的選材、熱處和結(jié)構(gòu)確定
這兩種凸凹拉都選用T10A，經(jīng)熱處理達(dá)60-64HRC，具體情況見零件表。
4.5 導(dǎo)料、卸料等其它裝置的確定
4.5.1 凸模固定板與墊板的確定：
凸模固定板經(jīng)落料凸模用鏍釘圓柱銷固定在上模座上，其外形尺寸如落料凸模外形尺寸一樣，并將反拉深凸模固定在落料正拉深凸凹模上，由于本模具中的沖裁力較小，但考慮其結(jié)構(gòu)，選取墊板，選取厚度為9mm。凸模固定板的厚度取凹模厚度的0.6-0.8倍，本模具中可取12mm。具體結(jié)構(gòu)見零件圖。
4.5.2推件裝置的選用和確定
4.5.2.1下出件裝置的設(shè)計(jì)
上模裝有剛性推裝置，推件力通過打桿——推板——推桿——推件塊傳到工件。
本模具中，選用四個(gè)分布均勻、長短一致的推桿，推板裝在上模板的孔內(nèi)，為保證凸模支承剛度和強(qiáng)度，放推板的孔挖空，下面放有墊板。推板的形狀設(shè)置為圓形。
4.5.2.2 上出件裝置的設(shè)計(jì)
根據(jù)本模具的結(jié)構(gòu)，力小，選用彈簧，又凹模內(nèi)空，可容納彈簧，用卸料螺釘裝上推板，進(jìn)行預(yù)壓和導(dǎo)向固定?，F(xiàn)確定彈簧的型號(hào)及主要參數(shù)如下：
根據(jù)本模具的結(jié)構(gòu)及尺寸，確定用一根彈簧；
計(jì)算每個(gè)彈簧的頂件載荷F，Q=FQ=21N；
其中F‘Q為彈簧的預(yù)壓力
計(jì)算頂件時(shí)所需的最大壓縮行程L0
L0=h1+t+h2+h3
式中，h1—卸料板高出凸模端面的高度，為零
t—料厚，為0.8mm
h2—凸模進(jìn)入凹模的深度，為16mm
h3—凸?？傂弈Ａ?，為4mm
計(jì)算彈簧工作時(shí)的總行程L總：
L總=L，+ L0
L，—產(chǎn)生F，Q所需的彈簧預(yù)壓縮量，L總必須不大于彈簧的最大壓縮量Lmax。
計(jì)算所需彈簧的最大壓力F max與最大壓縮行程Lmax
由虎克定律得
F，Q/ FQ=F max/Lmax
L0+ L，≤Lmax
令L，=KLmax,模具為拉深模，K取小些，為0.4
于是，F(xiàn)max=F，Q/K=21/0.4=52.5N
Lmax=L0/（1-K）=20/0.6=34mm
查表5-23 《簡明模具工實(shí)用技術(shù)手冊》 選用彈簧的參數(shù)如下：
D=20mm, d=2.5mm t=6 H=60mm
記為 彈簧Ф20×2.6×60 （JB425-62）
彈簧材料為：65Mn 熱處理達(dá)HRC40-45
4.5.3導(dǎo)向零件的設(shè)計(jì)與選用:
由于本模具中，材料厚度比較小，因而間隙小，選用導(dǎo)柱導(dǎo)套保證上模和下模之間的精確位置頭系。因?yàn)楸灸＞咧械牧慵紴閳A形，為避免出錯(cuò)，選用的中間模架上的兩導(dǎo)柱，做成直徑不等的型式。
查表2-44（冷沖壓模具設(shè)計(jì)指導(dǎo)），根據(jù)凹模周界，選用凹模周界為125的，其中參數(shù)如下：
最小閉合高度： 125
最大閉合高度： 150
上模座： 125*30 (GB/T 2855.11)
下模座： 125*35 (GB/T2855.12)
導(dǎo)柱： 25*110 (GB/T2861.1)
導(dǎo)套： 22*80*28 (GB/t2861.6)
4.6 連接、固定用零件即鏍釘、銷釘?shù)倪x用
4.6.1 鏍釘?shù)倪x用
查表2-10（《機(jī)械制圖》）選用螺釘?shù)囊?guī)格如下：
4.6.1.1下模座與凹模、導(dǎo)料卸料板、墊板之間的固定。選用M10的螺釘4個(gè)，長為60，記為M10×60。（GB68-85）鏍釘材料為45號(hào)鋼，頭部淬火達(dá)硬度HRC43-48。
選用A型圓柱銷2個(gè)，d為10，長為50，材料為45號(hào)鋼，熱處理達(dá)HRC43-48。記為Ф10×50。（GB119-86）
4.6.1.2 凸模固定板、墊板、上模座及凸模之間的固用螺釘、銷釘，其材料為45號(hào)鋼，熱處理達(dá)HRC43-48，其記號(hào)如下：
鏍釘————M12×66（GB68-85）
圓柱銷———Ф10×55。（GB119-86）
4.6.1.3 模柄與上模座之間的固定用螺釘四個(gè)，其記號(hào)如下：
鏍釘————M9×30 （GB68-85）
4.6.1.4 凸凹模和下模座之間的固定用螺釘，選用2個(gè)M6的螺釘，長為18。記為M6×18 （GB68-85） 2個(gè)圓柱銷,記為Ф10×55
（GB119-86）
4.6.1.5 卸料螺釘?shù)倪x用，M3的卸料螺釘2個(gè)，長為88mm,記為
M3×88 （GB68-85）
另有一個(gè)卸料螺釘，用于彈簧的固定,型號(hào)為M6，長為50，記為
M6×50 （GB68-85）
4.7 固定擋料銷的選定
查表10-60 （《沖壓手冊》）
選Ι型,得 d=3mm h=2mm L=8mm
D的極限偏差為-0.0750 d的極限偏差為+0.008+0.002
材料為45號(hào)鋼,熱處理達(dá)硬度HRC43-48
查自GB2866.11-81
4.8頂板的確定
查《沖壓手冊》選 A型,其中 D=20mm, h=6mm
材料為45號(hào)鋼,熱處理達(dá)HRC43-48.
查自GB2867.4-81
第5章 典型零件加工工藝分析
5.1落料凹模的工藝分析及制造過程。
5.1.1工藝分析
該零件是復(fù)合沖裁模的凹模，采用整體式結(jié)構(gòu)，容易制造，強(qiáng)度高。由于該模具為中小型沖模，因而其弱點(diǎn)，如制造成本高，維修不方便，對(duì)其并沒有太大的影響。零件的外形尺寸為?125×22，零件的成型表面尺寸是落料凹模型孔，結(jié)構(gòu)表面包括螺紋連接孔，和銷釘定位孔。
該零件是本付模具裝配和加工的基準(zhǔn)件，模具的卸料板、固定板、模板上的各孔都和該零件有關(guān)，以該零件的實(shí)際尺寸為基準(zhǔn)來加工相關(guān)各孔。
零件的材料為T10A，熱處理硬度達(dá)60～64HRC，零件毛坯形式為鍛件。
5.1.2工藝過程的制定
序號(hào)
工序名稱
工序主要內(nèi)容
1
下料
鋸床下料，?68×104+4
2
鍛造
將坯料鍛壓成形?130×30
3
熱處理
退火至HBS〈119
4
粗車
留有0。05的磨削余量
5
劃線
畫出各螺孔、銷孔的位置
6
鉆孔、攻絲
在鉆床上鉆出所有銷孔及螺絲底孔，并
進(jìn)行攻絲鉸銷釘孔。
7
熱處理
淬火、回火至60～64HRC
8
磨
平面磨床上平磨上下兩底面，內(nèi)圓磨床上
磨形孔至尺寸，磨孔的精度達(dá)1～2級(jí)，表面粗糙度達(dá)R a為1.60～0.2
9
鉗
鉗工研磨修整工作型面至尺寸精度，刃
口要鋒利。
5.1.3 漏料孔的加工
沖裁漏料孔是在保證型孔工作長度基礎(chǔ)上，減小落料件與型孔的磨擦力。本模具中，漏料孔的加工放在零件淬火之前，在工具銑床上將漏料孔銑削完畢即可。
5.1.4 鍛件毛坯下料尺寸與鍛壓設(shè)備的確定
由圖沖裁凹模外形尺寸為125×125×22，凹模零件材料為T10A，設(shè)鍛件的毛坯的外形尺寸為125+4×125+4×27+4
5.1.4.1 鍛件體積和重量的計(jì)算
鍛件的體積： V鍛=130×130×27mm3=456.3cm3
鍛件的重量： G鍛=7.85×456.3=3.58㎏
當(dāng)鍛件質(zhì)量在5㎏之內(nèi)，一般需要加熱1～2次，鍛件總的損耗系數(shù)取5%
鍛件毛坯的體保積： V坯=V鍛×1.05=1.05×456.3=497.1cm3
鍛件毛坯的重量： G坯=G鍛×1.05=3.58×1.05=3.76㎏
5.1.4確定鍛件毛坯尺寸
理論圓棒直徑 D理=（0.63×V坯）1/3=6.62cm=66.2mm
選取圓棒直徑為68，則可算出圓棒長度
L坯=G坯×4/D2л×r=3.76×4/3.14×68×68=104mm
驗(yàn)證鍛壓比： Y=L坯/D坯=104/68=1.53
符合Y=（1.25～2.5）的要求。
故鍛件下料尺寸為?65×104+4
5.1.3 鍛壓設(shè)備的確定
該鍛件坯料重量為3.57㎏，材料為T10A，應(yīng)選400㎏的空氣錘。
5.2 落料拉深凸凹的加工工藝分析
5.2.1 工藝分析
該落料拉深凸凹模是完成制件外形尺寸和拉深成形的工作零件，中間為四個(gè)M10的螺紋孔，四個(gè)M10的銷孔，工作外表面為直角，有鋒利刃口，內(nèi)表面刃口為3的圓角，在車床上粗車后用球形銑出圓角，再經(jīng)磨床或鉗工修整。
由凸凹模的材料為T10A，熱處理硬度達(dá)58～62HRC
5.2.2 工藝方案的確定
于該零件外形尺寸為圓形，因而用普通機(jī)床的車、銑、磨即可達(dá)到要求，無需先進(jìn)的制造技術(shù)，如線切割、電火花等到，即增大技術(shù)含量，又增大加工成本?，F(xiàn)決定工藝方案如下：
備料—鍛造—退火—精車—磨上下兩圓面—鉗工劃線作孔—熱處理—研磨內(nèi)孔和外圓，即工作表面。
5.2.3 工藝過程制定如下：
序號(hào)
工序名稱
工序主要內(nèi)容
1
下料
鋸床下料，?106×133+4
2
鍛造
鍛造成?130×82
3
熱處理
退火至HBS≤119
4
粗車
車內(nèi)圓、內(nèi)孔，留雙邊間隙為0.05mm
5
磨
磨上下兩面至Ra為0.8
6
鉗
劃線，作孔，攻絲
7
熱處理
淬火到HRC58～62
8
磨
磨內(nèi)、外工作表面至圖紙要求
9
鉗
修整內(nèi)圓角半徑3
5.3拉深凸凹模的工藝分析制定
5.3.1 工藝分析
該零件和落料-反拉深凸凹模制作相仿，材料奕為T10A，熱處理硬度達(dá)HRC58～62。
5.3.2 工藝方案的確定
于該零件外形尺寸為圓形，因而用普通機(jī)床的車、銑、磨即可達(dá)到要求，無需先進(jìn)的制造技術(shù)，如線切割、電火花等到，即增大技術(shù)含量，又增大加工成本?，F(xiàn)決定工藝方案如下：
備料—鍛造—退火—精車—磨上下兩圓面—鉗工劃線作孔—熱處理—研磨內(nèi)孔和外圓，即工作表面。
5.3.3工藝過程制作如下表：
序號(hào)
工序名稱
工序主要內(nèi)容
1
下料
鋸床下料，?33×60+4
2
鍛造
鍛造成?36×57
3
熱處理
退火至HBS<119
4
粗車
車內(nèi)圓、內(nèi)孔，留雙邊間隙為0.05mm
5
磨
磨上下兩面至Ra為0.8
6
鉗
劃線，作孔，攻絲
7
熱處理
淬火到HRC58～62
8
磨
磨內(nèi)、外工作表面至圖紙要求
9
鉗
修整內(nèi)圓角半徑1
5.4 正拉深凸模工藝分析、制定方案
5.5.1工藝性分析
該零件形狀和精度要求看，以及零件要求進(jìn)行淬火處理，加工方式主要是車削和外圓磨削。加工精度要求在外圓磨削的經(jīng)濟(jì)加工范圍之內(nèi)。
該零件的材料為T10A，熱處理硬度為HRC58-62零件毛坯材料為圓形，經(jīng)下料鍛造之后進(jìn)行機(jī)械加工。
5.5.2 工藝方案
凸模的加工方案如下：
備料——鍛造——粗車——鉗——熱處理——磨——鉗
5.5.3 工藝過程的制定
序號(hào)
工序名稱
工序主要內(nèi)容
1
下料
鋸床下料Ф33×142+4
2
鍛造
鍛造成Ф47×77
3
粗車
車外圓至圖紙要求，工作尺寸留余量0.5mm
4
鉗
劃線，作過孔
5
熱處理
硬度達(dá)HRC58-62
6
磨
磨削精度達(dá)1-2級(jí)，粗糙度為0.4
7
鉗
磨刃口圓角達(dá)1mm
5.5 導(dǎo)料, 卸料板的選材，熱處理及加工工藝過程
根據(jù)表8-8， （冷沖壓模具設(shè)計(jì)指導(dǎo)） 普通卸料板的材料選Q235號(hào)鋼,但導(dǎo)料板的材料為45號(hào)鋼,故選取好的即使45號(hào)鋼。 它是一種普通碳素結(jié)構(gòu)鋼， 這種鋼冶煉容易， 塑性好， 焊接性好， 強(qiáng)度較低， 價(jià)廉， 而且在力學(xué)性能上也能滿足普通卸料板的要求， 但鋼中含有S， P和非金屬夾雜物，其塑性， 韌性較低。 故加工成形后一般不進(jìn)行熱處理。 而是直接使用。
根據(jù)普通卸料板的要求， 確定卸料板的加工工藝為：
備料— 鍛造— 熱處理退火— 刨削粗加工— 平磨上下工作平面。 其內(nèi)孔的加工可采用以下的方法： 先加工出毛坯孔。 孔邊留單邊的壓印余量0.5mm, 然后用壓印法加工出型孔。
工藝方案的制定如下：
序號(hào)
工序名稱
工序的主要內(nèi)容
1
下料
鋸床下料 φ125+5×21+4
2
粗車
粗車外形
3
刨削粗加工
去掉大部分的加余量留分的磨削余量小部,并刨出方的導(dǎo)料部分
4
平磨上下表面
去掉磨削余量使尺寸要求
5
鏜孔
孔邊留單邊壓印余量0.5mm.
6
壓印
壓印加工出型孔
5.6 固定板的選材，熱處理及加工工藝方案
根據(jù)表8-8， （冷沖壓模具設(shè)計(jì)指導(dǎo)） 普通固定板的材料選
用Q235就能滿足其工藝性要求。 它是一種普通碳素結(jié)構(gòu)鋼
這類鋼不但冶煉容易， 而且塑性好， 焊接性能好。 價(jià)格低廉
只不過強(qiáng)度較低。 但是還能滿足所需要的要求。 此類鋼中含有S
P和非金屬夾雜物， 影響了此類鋼的塑性和韌性。 故加工后
般不進(jìn)行熱處理，而是直接使用即可。
根據(jù)普通固定板的要求。 固定板的毛坯的預(yù)加工工藝與凹
基本相同， 外形為圓形的固定板可用車， 磨來加工， 其工藝
方案如下：
備料— 退火— 車削粗加工— 平磨上下面
固定板上的固定孔加工可直接劃線用車床及鉆床。 也可用銑床
鏜床加工。
工藝方案的制定如下：
序號(hào)
工序名稱
工序主要內(nèi)容
1
下料
鋸床下料φ125+5×12+4
2
車削
在車床上去掉大部分的工余量，僅留加0.2~0.3mm的余量
3
劃線
劃出固定孔的位置及大小
4
車孔
按線車孔
5
鉆孔
加工出固定孔
5.7 推桿的選取材，熱處理及加工工藝過程]
根據(jù)表14-63， （冷沖壓設(shè)計(jì)手冊） 一般用途的推桿的材料選用為45鋼。 它是一種優(yōu)質(zhì)碳素結(jié)構(gòu)鋼。 這類結(jié)構(gòu)鋼的硫。 磷含量較低。 非金屬的夾雜物也較少。 鋼的品質(zhì)較高。 45鋼屬于中碳鋼， 須經(jīng)調(diào)質(zhì)處理后使用。 這種鋼經(jīng)調(diào)質(zhì)后具有良好的綜合力學(xué)性能， 即具有較高的強(qiáng)度。 又具有較高的韌性和塑性， 焊接性能也好。 而推桿承受較大的力的作用， 故采用此種鋼比較好。
工藝方案如下
備料 — 銑— 平磨
工藝過程的制定如下
序號(hào)
工序名稱
工序的主要內(nèi)容
1
下料
鋸床下料φ22*78mm
2
銑
銑側(cè)面及上下表面
3
平磨
平磨上下面
5.8 推板的選材，熱處理及加工工藝方案
根據(jù)表率14-53。 （沖壓設(shè)計(jì)手冊） 本副模具所選用推板的材料為Q235 。推板在工作過程中報(bào)承受的力沒有多大。 材料Q235即可滿足要求。 Q235在各種普通零件中是應(yīng)用廣泛的。 它雖然強(qiáng)度不是很好。 但還是能達(dá)到其要求。 而且價(jià)格也低。 使用這種材料能夠降低模具的成本。 故采用這種材料既經(jīng)濟(jì)又實(shí)惠。
其工藝方案如下：
備較— 鍛造— 粗銑外形— 平磨上下面
工藝過程的制定如下
序號(hào)
序號(hào)
工序的主要內(nèi)容
1
下料
鋸床下料
2
鍛造
鍛造為需要的尺寸
3
銑
粗銑外形（梅花形
4
平磨
平磨上下面
5.9 墊板的選材， 熱處理及加工工藝過程
根據(jù)表8-9， （冷沖壓模具設(shè)計(jì)指導(dǎo)） 本副模具墊板所承受
的單位壓力比較大。 為了安全起見， 墊板所選用的材料為T8 。 該誤材料為一種優(yōu)質(zhì)碳素工具鋼。 碳素工具鋼的化學(xué)成份的特點(diǎn)是含高碳和硫， 磷雜質(zhì)低。保證淬火后有足夠的硬度和耐磨性。 并提高了工具鋼的可鍛性。 減少了淬裂傾向。 T8鋼，塑性好， 但耐磨性較差。 淬透性差。 回火抗力差。 須鍛造， 使碳化物細(xì)化并分布均勻。 然后退火， 降低硬度。 改善切削加工性。 同時(shí)為淬火作好組織準(zhǔn)備。 退火后的組織為球狀珠光體。 硬度不高于197HBS。 由于這類鋼對(duì)過熱敏感。 應(yīng)選較低的淬火溫度。 淬火后應(yīng)立即低溫回火。回火后的組織為細(xì)針狀馬氏體和分布均勻細(xì)小粒狀滲碳體。有少量殘余奧氏體。
工藝方案如下：
備料— 鍛造— 回火— 車削— 平磨
工藝方案的制定如下
序號(hào)
工序名稱
工序主要內(nèi)容
1
下料
鋸床下料
2
鍛造
鍛造所要的形狀
3
退火
退火硬度≤197HBS
4
車削
去掉加工余量 留0.5左右的磨削余量即可
5
平磨
平磨上下面
5.10 模架的選材，熱處理及加工工藝方案
導(dǎo)套，導(dǎo)柱與上下模座孔采用壓配合的模架， 要求上，下模座的導(dǎo)套，導(dǎo)柱孔的孔距一致， 孔與模座平面保證垂直， 并達(dá)到孔徑尺寸要求。
上下模座所選用的材料為HT200即可， 該材料是一種普通灰鑄鐵。由于石墨基層間較弱的結(jié)合力。 使兩基面間容易產(chǎn)生滑移。 因而使鑄鐵的力學(xué)性能不如鋼， 但也正由于石墨的存在賦予了鑄鐵許多鋼所不及的性能， 如優(yōu)良的鑄造性， 較好的切削加工性和耐磨性及減振性。 同時(shí)鑄鐵的生產(chǎn)設(shè)備簡單和工藝簡單， 使模具的生產(chǎn)成本降低。 灰鑄鐵的抗壓強(qiáng)度比抗拉強(qiáng)度要好。 所以比較適合上下模座的材料。
加工工藝方案如下：
備料— 鍛造— 退火— 鉆孔— 鉸孔— 鉆孔— 鉸孔— 鏜孔
工藝方案的制定如下：
序號(hào) 工序名稱 工序的主要內(nèi)容
1
下料
鋸床下料
2
鍛造
3
鉆孔
鉆螺紋孔
4
鉸孔
鉸銷釘孔
5
鉆孔
鉆模柄孔
6
鉸孔
鉸模柄孔
7
鏜孔
鉸模柄孔]
8
平磨
平磨端面
5.11 模柄的選材，熱處理及加工工藝方案
根據(jù)表14-53 （沖壓設(shè)計(jì)手冊）模柄的材料選用Q275。 它是一種普通碳素結(jié)構(gòu)鋼。 這類鋼冶煉容易。 工藝性好。 價(jià)廉。 而且在力學(xué)性能上也能滿足模柄的要求， 塑性好。 焊接性好， 強(qiáng)度較高，可用于制作受力比較大的普通零件。 加工成形后一般不進(jìn)行熱處理， 直接使用。
模柄的加工工藝方案如下：
備料— 鍛造— 退火— 銑— 鉸孔— 鉆孔— 平磨
工藝方案的制定如下：
序號(hào)
工序名稱
工序的主要內(nèi)容
1
下料
鋸床下料
2
鍛造
3
退火
退火硬度≤197HBS
4
銑
粗銑外形
5
鉸孔
鉸銷釘孔
6
鉆孔
鉆螺釘孔
7
平磨
磨端面
5.12 打料桿的選材， 熱處理有加工工藝方案
根據(jù)表8-9 （冷沖壓模具設(shè)計(jì)指導(dǎo)） 打料桿的材料選用45鋼。 它是一種優(yōu)質(zhì)碳素結(jié)構(gòu)鋼。 這類鋼的硫， 磷含量較低。 非金屬雜物也較少。 鋼的品質(zhì)較高。 45鋼屬于中碳鋼， 須調(diào)質(zhì)后使用。 這種鋼調(diào)質(zhì)后具有良好的綜合力學(xué)性能， 即具有較高強(qiáng)度，又具有良好的塑性韌性。 這部分鋼是碳鋼中應(yīng)用最廣泛的。
加工工藝過程如下：
備料— 鍛造— 退火— 銑— 車— 平磨
工藝的制定如下：
序號(hào)
工序名稱
工序的主要內(nèi)容
1
下料
鋸床下料
2
鍛造
3
退火
退火硬度<197HBS
4
銑
5
車
粗銑外形
6
平磨
在車床上鉆孔
磨端面]
第6章 模具的裝配
模具的裝配包括組件裝配和總的裝配
6.1組件的裝配
6.1.1 模柄的裝配
裝配前要檢查模柄和上模座的尺寸精度和表面粗糙度。 并檢驗(yàn)?zāi)Ｗ惭b面與平面垂直度精度。 裝配時(shí)將上模座放平， 并將模柄放在安裝面，對(duì)準(zhǔn)孔的位置， 用銷釘固定， 然后用螺釘固定， 檢查模柄相對(duì)上模座平面的垂直度精度， 合格即可。
6.1.2 凸模，凸凹模與固定板的裝配
壓入式凸模與固定板的裝配。 裝配前要檢查凸模與固定板配合部位的尺寸精度和表面粗糙度，并檢驗(yàn)固定板的安裝面與平面的垂直度，裝配時(shí)將固定板放平， 用銅棒將凸模慢慢打入固定板， 要邊打邊檢查凸模的垂直度，直止凸模臺(tái)階面與固定板接觸為止，檢查凸模相對(duì)固定板平面的垂直度精度，合格后將平面磨平。
6.2 模具的總裝配
6.2.1 確定裝配基準(zhǔn)件
落料，拉深，沖孔復(fù)合模應(yīng)以沖裁凸凹模為裝配基準(zhǔn)件。 首先要確定凸凹模在模架中的位置， 安裝凸凹模組件， 加工出下厝座的漏料孔，確定凸凹模組件在下模座的位置， 然后用平行板將凸凹模和下模座夾緊，在下模座上劃出漏料孔線，加工漏料孔，再安裝凸凹模組件。
6.2.2 安裝上模部分。
檢查上模部分各個(gè)零件尺寸是不是滿足裝配技術(shù)條件要求。 安裝上模，調(diào)整沖裁間隙， 將上模系統(tǒng)各零件分別裝于上模座和模柄內(nèi)。
6.2.3 安裝下模座內(nèi)的各個(gè)零件。
6.2.4 按沖模技術(shù)條件進(jìn)行總裝配檢查。
6.2.5 檢驗(yàn)。
6.2.6 試模。
后 語
通過這次冷沖模的畢業(yè)設(shè)計(jì)，我在各個(gè)方面都有所提高。 懂得了對(duì)零件工藝性的分析，怎樣去確定工藝方案，了解了模具的基本結(jié)構(gòu)，提高了設(shè)計(jì)能力，繪圖能力，查找資料和手冊的能力，熟悉了規(guī)范和標(biāo)準(zhǔn)，同時(shí)各科相關(guān)的課程有了全面的復(fù)習(xí)，獨(dú)立思考的能力也有一定的提高。
同時(shí)由于本人的設(shè)計(jì)水平和經(jīng)驗(yàn)的不足，在設(shè)計(jì)過程中還存在許多的錯(cuò)誤，請(qǐng)各位老師和同學(xué)批評(píng)和指正，本人將萬分感謝
參考文獻(xiàn)
1. 王芳主編· 冷沖壓模具設(shè)計(jì)指導(dǎo)· 北京：機(jī)械工業(yè)出版社，1998 10
2. 孫鳳勤主編· 模具制造工藝與設(shè)備·北京：機(jī)械工業(yè)出版社，1999
3. 溫松明主編· 互換性與測量技術(shù)基礎(chǔ)· 長沙：湖南大學(xué)出版社，1998
4. 丁仁亮主編· 金屬材料及熱處理· 北京：機(jī)械工業(yè)出版社。1999
5. 冷沖模設(shè)計(jì)組主編· 冷沖模設(shè)計(jì)手冊· 北京：機(jī)械工業(yè)出版社 1999
6. 吳天生主編·機(jī)械制圖·高等教育出版社·1999
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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 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