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河南機(jī)電高等?？茖W(xué)校材料工程系畢業(yè)設(shè)計(jì)說明書/論文 前 言 利用模具生產(chǎn)零件的方法已成為工業(yè)上進(jìn)行成批或大批生產(chǎn)的主要技術(shù)手段，它對(duì)于保證制品質(zhì)量，縮短試制周期，進(jìn)而爭(zhēng)先占領(lǐng)市場(chǎng)，以及產(chǎn)品更新?lián)Q代和新產(chǎn)品開發(fā)都有決定性的意義。在現(xiàn)代工業(yè)的主要部門，如機(jī)械、電子、輕工、交通和國(guó)防工業(yè)中得到了極其廣泛的應(yīng)用。如70%以上的汽車、拖拉機(jī)、電機(jī)、電器、儀表零件，80%以上的塑料制品，70%以上的日用五金及耐用消費(fèi)零件，都采用模具成型的方法來(lái)生產(chǎn)[10]。 利用模具將平板毛坯變成開口空心零件的加工方法稱為拉深（或拉延）。 拉深是主要的沖壓工序之一，應(yīng)用廣泛。用這種工藝方法可以制成筒形、階梯形、球形、錐形、拋物線形、盒形和其它不規(guī)則的薄壁零件，如果與其它沖壓工藝相配合，還可以制造形狀更為復(fù)雜的零件。因此在汽車、拖拉機(jī)、電器、儀表電子、輕工等行業(yè)中有相當(dāng)重要的地位。 該模具適應(yīng)于高矩形和高筒形件的拉深，在毛坯排樣無(wú)中間搭邊，沖裁后廢料中間自動(dòng)斷開，方便送料，不用設(shè)置卸料板送料。該成型方法已經(jīng)熟練應(yīng)用于工業(yè)生產(chǎn)中。但是在以前模具設(shè)計(jì)的毛坯計(jì)算中都是采用有關(guān)手冊(cè)上所給的公式進(jìn)行計(jì)算，計(jì)算量不僅很大，而且當(dāng)遇到形狀復(fù)雜的零件（該零件就是屬于這種情況）會(huì)比較麻煩，且容易出錯(cuò)。所以在本設(shè)計(jì)中擬采用模具CAD技術(shù)對(duì)零件的毛坯進(jìn)行計(jì)算，以解決以前模具設(shè)計(jì)中毛坯計(jì)算較為復(fù)雜的問題，從而縮短模具設(shè)計(jì)的周期。 從模具設(shè)計(jì)和制造技術(shù)角度來(lái)看，模具的發(fā)展趨勢(shì)可歸納為以下幾個(gè)方面： （1）加深理論研究。 加強(qiáng)沖壓理論的研究，以提供更加準(zhǔn)確、實(shí)用、方便的計(jì)算方法，正確地制定沖壓工藝參數(shù)和模具工作部分的幾何形狀與尺寸，解決沖壓變形中出現(xiàn)的各種實(shí)際問題，進(jìn)一步提高工件的質(zhì)量。 （2）高效率、自動(dòng)化。為適應(yīng)市場(chǎng)的發(fā)化發(fā)展，沖壓模具正向高效率、自動(dòng)化、長(zhǎng)壽命、大型化方向發(fā)展。 （3）大型、超小型及高精度。隨著工業(yè)產(chǎn)品質(zhì)量的不斷提高，沖壓產(chǎn)品生產(chǎn)正呈現(xiàn)多品種、少批量、復(fù)雜、大型、精密，更新?lián)Q代速度快等變化特點(diǎn)。 （4）革新模具制造工藝。 模具制造技術(shù)現(xiàn)代化是模具工業(yè)發(fā)展的基礎(chǔ)。隨著科學(xué)技術(shù)的發(fā)展，計(jì)算機(jī)技術(shù)、信息技術(shù)、自動(dòng)化技術(shù)等先進(jìn)技術(shù)正不斷向傳統(tǒng)制造技術(shù)滲透、交叉、融合，對(duì)其實(shí)施改造，以形成先進(jìn)的模具制造技術(shù)。 （5）標(biāo)準(zhǔn)化。 開展模具標(biāo)準(zhǔn)化工作，使模板導(dǎo)柱等通用零件標(biāo)準(zhǔn)化、商品化，以適應(yīng)大規(guī)模地成批的生產(chǎn)塑料成型模具。 我國(guó)的模具工業(yè)發(fā)展到今天經(jīng)歷了一個(gè)艱辛的歷程。 我國(guó)模具工業(yè)是19世紀(jì)末20世紀(jì)初隨軍火和鐘表業(yè)引進(jìn)的壓力機(jī)發(fā)展起來(lái)的。從那時(shí)到20世紀(jì)50年代初，模具多采用作坊式生產(chǎn)，憑工人經(jīng)驗(yàn)，用簡(jiǎn)單的加工手段制造。在以后的幾十年中，隨著國(guó)民經(jīng)濟(jì)的大規(guī)模發(fā)展，模具工業(yè)進(jìn)步很快。當(dāng)時(shí)我國(guó)大量引進(jìn)蘇聯(lián)的圖紙、設(shè)備和先進(jìn)經(jīng)驗(yàn)，其水平不低于當(dāng)時(shí)工業(yè)發(fā)達(dá)的國(guó)家。此后直到20世紀(jì)70年代末，由于錯(cuò)過了世界經(jīng)濟(jì)發(fā)展的大浪潮，我國(guó)模具業(yè)沒有跟上世界發(fā)展的步伐。20世紀(jì)80年代末，伴隨家電、輕工、汽車生產(chǎn)線模具的大量進(jìn)口和模具國(guó)產(chǎn)化的呼聲日益高漲，我國(guó)先后引進(jìn)了一批現(xiàn)代化模具加工機(jī)床。在此基礎(chǔ)上，參照以后的進(jìn)口模具，我國(guó)成功地復(fù)制了一批替代品。如汽車覆蓋件模具等。模具的國(guó)產(chǎn)化雖然使我國(guó)模具制造水平逐漸趕上了國(guó)際先進(jìn)水平，但計(jì)算機(jī)應(yīng)用方面仍然存在很大的差距。 我國(guó)模具工業(yè)起步晚，基礎(chǔ)差，就總量來(lái)看，大型、精密、復(fù)雜、長(zhǎng)壽命模具產(chǎn)需矛盾仍然十分突出。為了進(jìn)一步振興模具工業(yè)，國(guó)家有關(guān)部門進(jìn)一步部署。相信在政府的大力支持下，通過本行業(yè)和相關(guān)行業(yè)以及廣大模具工作者的共同努力，我國(guó)模具工業(yè)水平必將大大提高，為國(guó)家經(jīng)濟(jì)建設(shè)作出更大的貢獻(xiàn)。 第1章 沖壓件工藝性分析 1.1零件材料的力學(xué)性能 圖1. 零件圖 此零件為軸承座，是典型的沖壓件。工件尺寸步太大，表面質(zhì)量要求不太高。材料厚度為2.5mm，為中批量生產(chǎn)，每月2000～4000件。所用材料為08鋼，由于含碳量≤0.25％，屬于極軟低碳鋼。強(qiáng)度、硬度很低，塑性、韌性極好，冷加工性好，淬透性、淬硬性差。其理學(xué)性能見表1。 表1 08鋼力學(xué)性能 名稱 牌號(hào) 力學(xué)性能 抗剪強(qiáng)度τ（MPa） 抗拉強(qiáng)度（MPa） 屈服強(qiáng)度（MPa） 延伸率（%） 08鋼 08 260～360 380～470 200 32 由表知，材料力學(xué)性能較好，料薄，孔徑mm，為IT11級(jí)，屬于一般沖裁精度，拉深件外形直徑?62mm未注公差，按IT4級(jí)精度計(jì)算，公差要求大于它的極限偏差，精度要求不高。 該零件結(jié)構(gòu)對(duì)稱，受力均勻；凸臺(tái)較高，在拉深過程中，材料補(bǔ)充有困難，靠變薄拉深滿足不了要求，4個(gè)孔的位置容易移動(dòng)。如果先沖孔后拉深，則沖好的孔會(huì)產(chǎn)生變形。因此，應(yīng)先拉深后沖孔。 1.2 零件成型工藝分析 （1）拉深件形狀應(yīng)盡量簡(jiǎn)單，對(duì)稱。從零件圖上可以看出：該零件的外形為類似矩形，而且用圓弧過渡連接，結(jié)構(gòu)對(duì)稱。即工件在圓周方向上的變形是均勻的，模具容易加工，其工藝性較好，避免了急劇的輪廓變化。 （2）拉深件各部分尺寸比例要適當(dāng)。從零件圖上可以看出：該零件的設(shè)計(jì)避免了寬凸緣和深度較大的尺寸（即d凸>3d,h≥2d）。這樣在成型中可以減少拉深次數(shù)甚至一次拉成。 （3）拉深件的圓角半徑要適當(dāng)。拉深件的圓角半徑，應(yīng)盡量大些，以便利于成型和減少拉深次數(shù)。拉深件底與壁、矩形件的四壁圓角半徑應(yīng)滿足r1≥t、r2≥3t.從零件圖可以得出：該零件底與壁、矩形件的四壁圓角半徑應(yīng)滿足上述值得要求。這樣就可以不用再另外增加整形工序。 （4）拉深件厚度不均勻現(xiàn)象的考慮。由于各處變形不均勻，上下壁厚的變化達(dá)1.2t至0.75t。但是只有工件有特殊的要求，才會(huì)考慮這些問題，否則可以認(rèn)為零件壁厚是均勻的。由畢業(yè)設(shè)計(jì)原始資料可以不用考慮壁厚不均勻的現(xiàn)象。 此外，拉深件的尺寸精度不宜要求過高。 第2章 沖壓工藝方案的確定 該工件包括落料、拉深、沖孔三個(gè)基本工序，可以有三種工藝方案： 方案一：先落料，后拉深，再?zèng)_孔。采用單工序模生產(chǎn)。 方案二：落料-拉深-沖孔復(fù)合沖壓。采用復(fù)合模生產(chǎn)。 方案三：拉深級(jí)進(jìn)沖壓。采用級(jí)進(jìn)模生產(chǎn)。 方案一模具結(jié)構(gòu)簡(jiǎn)單，制造周期短，工件質(zhì)量容易控制并且以后工序都可以采用預(yù)沖孔定位，且定位基準(zhǔn)一致，操作方便。但需三副模具，工序分散，但需成本高而生產(chǎn)效率低，難以滿足顧客的要求。 方案二只需一幅模具，工件的形位精度和尺寸精度易保證且生產(chǎn)效率高。盡管模具結(jié)構(gòu)較方案一復(fù)雜，但由于零件的幾何形狀簡(jiǎn)單對(duì)稱，模具制造難度不大。 方案三也只需要一幅模具，生產(chǎn)效率也高，但零件的沖壓精度稍差欲保證沖壓件的形位精度，需要在模具上設(shè)置導(dǎo)正銷導(dǎo)正。因此模具制造、安裝較復(fù)合模復(fù)雜，安裝調(diào)試，維修較困難，制造周期長(zhǎng)。 通過對(duì)上述三種工藝方案的分析比較，綜合考慮，該工件的沖壓生產(chǎn)采用方案二為佳。 第3章 排樣及裁板方式的經(jīng)濟(jì)性分析 2.1毛坯直徑的計(jì)算 由《沖壓設(shè)計(jì)資料》可查得以下計(jì)算公式： = 式中 —毛坯直徑； —制件直徑； —零件筒形部分的直徑； —拉深高度； R—凸緣轉(zhuǎn)角半徑。 將數(shù)值代入公式計(jì)算得 = = =138.89mm 2.2確定搭邊值 由《沖壓設(shè)計(jì)資料》表2-5-2知工件間距=1.5mm，側(cè)邊距=1.8mm。其排樣圖如圖2： 2.3條料寬度及送料步距的計(jì)算 條料寬度：B= + 式中—條料寬度方向沖裁件的最大尺寸； —側(cè)搭邊值。 將數(shù)值代入公式計(jì)算得 B= +=138.89+2×1.5=141.89mm 導(dǎo)料板間距：A=B+C=++C 圖2.排樣圖 式中C—導(dǎo)料板與寬度條料之間的間隙，其最小值查《沖壓設(shè)計(jì)資料》表2-5得C=1mm; 將數(shù)值代入公式計(jì)算得 A=B+C=++C=141.89+1=142.89mm 送料步距S=+ 式中—工件間搭邊值； 將數(shù)值代入公式得 S=+=138.89+1.5=140.89mm 由《沖壓設(shè)計(jì)資料》表2.1知△=0.5mm，則B=mm。 2.4條料的剪裁 條料是從板料剪裁得來(lái)的，條料寬度一經(jīng)決定就可以裁板，板料一般都是長(zhǎng)方形的，所以就有縱裁和橫裁兩種方法。 因?yàn)榭v裁的裁板次數(shù)少，沖壓時(shí)調(diào)換條料次數(shù)少，工作操作方便，生產(chǎn)率高，因此，該毛坯采用總裁。 2.5沖壓材料板料規(guī)格的選擇 選用板料時(shí)應(yīng)盡量使裁后所剩廢料少，同時(shí)考慮占地面積及裁板機(jī)的情況。根據(jù)條料寬度B=151.89mm，步距S=140.39mm。查《模具設(shè)計(jì)與制造簡(jiǎn)明手冊(cè)》表1-2選用1600×2800mm的板料。 2.6材料的利用率 每塊板料可裁的制件數(shù)：n==19，則材料的利用率為 式中 A—一個(gè)步距內(nèi)沖裁件的實(shí)際面積； B—條料寬度； L—板料長(zhǎng)度； n—每塊板料所裁得的制件數(shù)。 第4章 工藝力的計(jì)算 4.1壓力中心的確定 為了保證壓力機(jī)和模具正常地工作，必須使模具的壓力中心通過模柄軸線且和壓力機(jī)滑塊的中心線重合。否則滑塊就會(huì)受到偏心載荷而導(dǎo)致滑塊導(dǎo)軌和模具的不正常磨損，降低模具壽命，甚至損壞模具。 4.2沖裁力的計(jì)算 查《冷沖模設(shè)計(jì)》表3-15得 F=KLtτ 式中 —沖裁力； —沖裁件周長(zhǎng)； t—板料厚度； K—系數(shù)（常取K=1.3）； τ—材料的抗剪強(qiáng)度。 由《冷沖模設(shè)計(jì)》表2-3知τ=260～360MPa，這取τ=260 MPa。 沖孔時(shí)的沖裁力 =Ktτ =1.3×（2×3.14×）×2.5×260 =140624.9N =tτ =0.055×140624.9 =7734.36N 式中 —推件力系數(shù)。 由《沖壓設(shè)計(jì)資料》表2-38得=0.055。 =4Ktτ =1.3×2.5×（2×3.14×）×260×2 =93396N =4 =2×0.055×93396=10272.14N 落料時(shí)的沖裁力 = KLtτ =1.3×2×3.14××260×2.5 =344929N 拉深力 =πtK =3.14×62×2.5×880×0.6 =110967.6N =+++++ =694.84KN 初選750噸的壓力機(jī)，型號(hào)為J23-80。 4.3壓力機(jī)的主要技術(shù)參數(shù) 公稱壓力/KN 800 滑塊行程/mm 130 滑塊行程次數(shù)/（次·mm-1） 45 最大封閉高度/mm 380 封閉高度調(diào)節(jié)量/mm 90 工作臺(tái)尺寸/mm 前后 540 左右 800 模柄孔尺寸/mm 直徑 60 深度 80 滑塊底面尺寸/mm 前后 350 左右 370 第5章 分析選定模具結(jié)構(gòu)形式 確定了沖壓工藝方案后，根據(jù)零件的形狀特點(diǎn)，精度要求，所選設(shè)備的主要技術(shù)參數(shù)，模具制造條件以及安全生產(chǎn)等選定沖模的類型及結(jié)構(gòu)形式，使其盡可能滿足以下要求。 （1）能符合工件的技術(shù)要求； （2）又合乎需要的生產(chǎn)率； （3）模具制造和修模方便； （4）模具有足夠的強(qiáng)度； （5）模具易于安裝、調(diào)試且操作方便、安全。 5.1模具結(jié)構(gòu)形式 由于倒裝式?jīng)_孔模的沖孔廢料可以通過凹模從壓力機(jī)工作臺(tái)孔漏出，工件由推件裝置推出，操作方便、安全，能保證較高的生產(chǎn)率。故沖孔選倒裝式，拉深與落料也采用倒裝式模具，廢料由卸料板卸下，落料件由頂出裝置頂出。 5.2壓邊裝置 此工件相對(duì)厚度較小，須采用壓邊裝置，此副模具采用的是剛性壓邊裝置，且其又可以起到卸料的作用。 5.3推件裝置 在此模具中，沖壓后，工件易套在沖孔凸模上，需由剛性或彈性裝置推出，考慮到剛性推件裝置可靠，結(jié)構(gòu)緊湊，維護(hù)方便，故此模具采用剛性推件裝置。 5.4卸料裝置 沖裁時(shí)，廢料將卡在拉深凹模里面和沖孔凸模外面。因此，在上模需裝卸料裝置。 5.5定位方式的選擇 該模具使用的是條料，為保證毛坯的準(zhǔn)確定位，應(yīng)用導(dǎo)料板控制送料方向， 送料步距控制采用擋料銷。 5.6上下模座的導(dǎo)向及模架形式的選擇 導(dǎo)向零件可保證模具沖壓時(shí)上下模有準(zhǔn)確的位置關(guān)系，在中小型模具中最廣泛采用的導(dǎo)向零件是導(dǎo)柱導(dǎo)套。 模架主要由上下模座、模柄及導(dǎo)向裝置組成。上模座通過模柄與壓力機(jī)相連，下模座則用壓板固定在壓力機(jī)上，上下模之間靠模架的導(dǎo)向裝置（導(dǎo)柱、導(dǎo)套）連接，保持準(zhǔn)確位置，以引導(dǎo)凸模運(yùn)動(dòng)，保證在沖裁過程中，間隙均勻，沖出合格的制件。 模架要求有足夠的強(qiáng)度、剛度和精度，上下模之間的導(dǎo)向要精確。 模架形式對(duì)沖裁精度、模具壽命都有較大的影響，下面對(duì)各種模架形式作以比較。 （1）后側(cè)導(dǎo)柱模架。送料方便，但沖壓時(shí)偏心距易使導(dǎo)柱導(dǎo)套單邊磨損，不能用于模柄與上模浮動(dòng)連接的模具。 （2）對(duì)角導(dǎo)柱模架。上下模座工作平面的橫向尺寸一般大于縱向尺寸，常用于橫向送進(jìn)的級(jí)進(jìn)模，縱向送料的單工序模和復(fù)合模。 （3）四導(dǎo)柱模架。導(dǎo)向精度高，剛度好，主要用于大型沖壓模。 （4）中間導(dǎo)柱模架。導(dǎo)向裝置安裝在模具的對(duì)稱線上，滑動(dòng)平穩(wěn)，導(dǎo)向準(zhǔn)確可靠，一般用于單工序模和復(fù)合模。 該工件的孔對(duì)稱分布，在沖裁時(shí)要求準(zhǔn)確的導(dǎo)向，經(jīng)分析對(duì)比，應(yīng)選用中間導(dǎo)柱模架。 第6章 凸凹模工作部分尺寸的計(jì)算 6.1工作零件刃口尺寸計(jì)算 沖裁模初始雙面間隙值的取值如下： mm；mm。 6.1.1對(duì)于沖?8.8mm的孔的沖孔凸模 凸凹模的制造公差按表2-4-1查得mm，mm，滿足+≤+。 =（） =（8.8+0.75×0.4） =9.1mm =（+） =（9.1+0.360） =9.46mm 6.1.2對(duì)于沖?53mm的孔的沖孔凸模 查表2-4-1得mm，mm,滿足+≤-。 =（） =（53+0.75×0.6） =53.45mm =（+） =（53.45+0.360） =9.46mm 6.1.3對(duì)于落料凸模 落料凸模取IT14級(jí)精度，χ=0.5,Δ=1.0,查表2-4-1得mm，mm,滿足+≤-。 =（）=（130+0.5×1）=130.5mm =（+） =（130.5+0.360） =130.86mm 6.1.4對(duì)于拉深凸凹模 拉深凸凹模也取IT14級(jí)精度，公差取0.74。查表4-8-3得拉深凸凹模的制造公差=0.05，=0.08，查表4-8-2表單邊間隙2.5mm。 =（） =（52+0.74×0.4） =62.3mm =（++） =（62+0.4×0.74+5） =130.86mm 6.2卸料橡膠的設(shè)計(jì) 該模具選用橡膠作為彈壓卸料的彈性元件，選用4塊筒形橡膠，厚度一致，不然會(huì)造成受力不均勻，運(yùn)動(dòng)產(chǎn)生歪斜，影響模具的正常工作。 卸料板工作行程 =13.5mm 式中 —凸模凹進(jìn)卸料板的高度1mm； —拉深凸模沖裁后進(jìn)入凹模的深度12.5mm。 橡膠工作行程=18.5mm 式中 為凸模修磨量，取5mm。 橡膠自由高度=4×18.5=74mm。 第7章 模具的主要零件的設(shè)計(jì) 7.1落料凹模的設(shè)計(jì) 7.1.1材料的選擇 由于零件外形尺寸精度要求不高，而沖孔精度要求較高，而模具壽命與沖裁的精度、模具材料有關(guān)。 模具材料的選用應(yīng)遵守如下原則。 （1）根據(jù)零件生產(chǎn)批量的大小來(lái)選擇模具材料。對(duì)大量生產(chǎn)的應(yīng)選用質(zhì)量較高，能耐用度高的材料。 （2）根據(jù)沖壓材料的性質(zhì)、工序種類及沖模零件的工作條件和作用來(lái)選擇模具材料。 由于零件的外形尺寸精度要求較低，考慮到生產(chǎn)的經(jīng)濟(jì)性及零件形狀尺寸等各方面因素的影響，落料凹模選用鋼，淬火HRC60～62。 7.1.2尺寸計(jì)算 （1）落料凹模厚度 H=Kb =0.15×138=20.7mm 式中 K—系數(shù)，取0.15； b—最大孔口尺寸。 取H=30mm。 （2）落料凹模壁厚 C=（1.5～2）H =2×30=60mm （3）落料凹模周界尺寸 L=b+2C =138+2×60=258mm 查《模具設(shè)計(jì)與制造簡(jiǎn)明手冊(cè)》表1-29可選用L×B=250×250mm的模架。 7.1.3.方法 由于工件的形狀較簡(jiǎn)單，圓角半徑較小，并且?guī)в型古_(tái)，不能用電火花線切割，用普通機(jī)床即可。 7.1.4強(qiáng)度的校核 由《沖壓設(shè)計(jì)資料》表2-48得 式中 =324～441MPa，取=400MPa。 7.2落料凸模與拉深凹模的設(shè)計(jì) 7.2.1材料的選擇 落料凸模與拉深凹模是一體的凸凹模，形狀復(fù)雜，容易變形，截面較大，承受載荷較重，選用高耐磨模具鋼制造，熱處理硬度HRC58～62。 7.2.2形式及固定 采用機(jī)械固定，用螺釘與銷釘直接固定在凸模固定板上。尺寸、公差與粗糙度要求見零件圖3。 7.2.3凸凹模壁厚 凸凹模壁厚a=65-33.5=31.5mm,大于最小模具壁厚2.7mm,故模具強(qiáng)度足夠。 圖3. 凸凹模 7.3落料凹模與拉深凸模的設(shè)計(jì) 7.3.1材料的選擇 落料凹模與拉深凸模是一體的凸凹模，形狀復(fù)雜，容易變形，截面較大，承受載荷較重，選用高耐磨模具鋼制造，熱處理硬度HRC58～62。 7.3.2形式及固定 采用凸臺(tái)固定，用螺釘與銷釘直接固定在凹模固定板上。尺寸、公差與粗糙度要求見零件圖4。 圖4.凸凹模 7.3.3凸凹模壁厚 凸凹模壁厚a==4.5mm,大于最小模具壁厚2.7mm,故模具強(qiáng)度足夠。 7.4沖孔凸模的設(shè)計(jì) 7.4.1沖大孔凸模的設(shè)計(jì) （1）材料的選擇。模具刃口要有高的耐磨性，要承受沖裁時(shí)的沖擊力，應(yīng)由高的硬度與適當(dāng)韌性，采用T10A制造，淬火硬度HRC58～62。 （2）形式及固定。采用臺(tái)階式凸模，將凸模壓入落料凸模，拉深凹模內(nèi)，采用H7/m6的過盈配合，定位精度較高。 （3）凸模長(zhǎng)度。凸模長(zhǎng)度根據(jù)以后公式計(jì)算得 L=20+40+2.5+10.5=73mm 凸模較粗且不長(zhǎng)，板料又較薄不必對(duì)凸模進(jìn)行強(qiáng)度校核。 其具體結(jié)構(gòu)見圖5 7.4.2沖小孔凸模的設(shè)計(jì) （1）材料的選擇。模具刃口要有高的耐磨性，要承受沖裁時(shí)的沖擊力，應(yīng)由 圖5.大孔凸模 高的硬度與適當(dāng)韌性，采用T10A制造，淬火硬度HRC58～62。 （2）形式及固定。采用臺(tái)階式凸模，將凸模壓入凸模固定板內(nèi)，采用H7/m6的過渡配合，定位精度較高。 （3）凸模長(zhǎng)度。凸模長(zhǎng)度根據(jù)以后公式計(jì)算得 L=20+358+2.5=57.5mm 凸模較粗且不長(zhǎng)，板料又較薄不必對(duì)凸模進(jìn)行強(qiáng)度校核。 其具體結(jié)構(gòu)見圖6 7.5定位零件 工件采用的是141×2800mm的板料，為保證工件的精度，采用擋料銷定位。因?yàn)閔≥t+1=2mm，查《模具標(biāo)準(zhǔn)匯編》選用A型固定擋料銷A6×2×10，GB2868.11-81。材料為45鋼，熱處理硬度為HRC45～48。 7.6固定零件 7.6.1凸模固定板 凸模直徑?9.1mm，固定部分為?13mm，查《標(biāo)準(zhǔn)件手冊(cè)》固定板的厚度選為 圖6.小孔凸模 20mm，其與沖孔凸模的配合為H7/m6的過渡配合。材料為45鋼，淬火熱處理硬度為HRC43～48。 7.6.2墊板 墊板厚度為10mm，材料45鋼，其上的孔均為過孔，間隙較大，與銷釘間隙配合。具體尺寸與技術(shù)要求見零件圖7。 7.7漏料孔 查《沖壓設(shè)計(jì)資料》可得 =+（0.5～2）=53+2=55mm =+（0.5～2）=8.8+2=10.8mm 圖7.墊板 7.8模座的選用 由于選用標(biāo)準(zhǔn)模架，模座的尺寸也隨之確定了。由所選的模架的凹模周界尺寸查《沖壓手冊(cè)》表10-38選用下模座：250×250×55； 上模座與下模座配套使用，由《沖壓手冊(cè)》表10-38選用上模座：250×250×45。 7.9導(dǎo)柱、導(dǎo)套的選用 導(dǎo)柱、導(dǎo)套根據(jù)與之相配合的模架選用標(biāo)準(zhǔn)件，由前面所選模架知，該模架采用 導(dǎo)柱、導(dǎo)套的長(zhǎng)度應(yīng)能保證在閉合狀態(tài)下應(yīng)有一定的配合長(zhǎng)度，同時(shí)應(yīng)保證在閉合后，導(dǎo)柱不能伸出導(dǎo)套，以免損壞導(dǎo)柱。根據(jù)模具的閉合高度，以及模架的配合導(dǎo)柱、導(dǎo)套的要求初選 導(dǎo)柱：Φ35×190；Φ40×190 材料：T8，淬火硬度HRC58～62 導(dǎo)套：Φ35×115×50；Φ40×115×55。 材料：T8，淬火硬度HRC58～62 7.10其它標(biāo)準(zhǔn)件的選用 7.10.1緊固連接上模座與固定板的螺釘、銷釘 查《沖壓設(shè)計(jì)資料》選用 圓柱頭內(nèi)六角螺釘M12×70 GB70-76 圓頭銷釘?8×70 GB119-76 7.10.2連接上下模與固定板的螺釘、銷釘 查《沖壓設(shè)計(jì)資料》選用 螺釘M8×30 GB70-76 銷釘?8×40 GB119-76 7.10.3緊固連接落料凹模與下模座的螺釘、銷釘 查《沖壓設(shè)計(jì)資料》選用 螺釘M12×60 GB70-76 銷釘?8×70 GB119-76 第8章 模具的裝配與調(diào)整 沖模裝配時(shí)沖模制造中的關(guān)鍵工序，其裝配質(zhì)量的好壞將直接影響之間質(zhì)量，沖模的技術(shù)狀態(tài)和使用壽命。裝配前，我們應(yīng)全面了解此沖模的工作性能、結(jié)構(gòu)以及制件要求，并按技術(shù)要求，模具零件的精度要求的裝配工藝，提出實(shí)現(xiàn)設(shè)計(jì)要求的具體措施。裝配完畢應(yīng)滿足模架各工作面的平行度和垂直度，壓料板的工作準(zhǔn)確性，工件間的間隙大小和均勻性，導(dǎo)柱、導(dǎo)套間的間隙配合。 此模具裝配的模柄為凸臺(tái)式 ，下面有螺釘緊固，應(yīng)先裝好模柄，模柄裝入，再加工螺釘孔。沖孔凸模與固定板采用H7/m6的配合，再在固定板上套入頂件塊，用螺釘與銷釘固定好落料拉深凸凹模，磨平?jīng)_孔凸模與固定板配合面及凸模端面，然后順序往上模座上裝入打桿，墊板、頂桿組合體。 整體裝配：先裝上模，找正下模的位置。按照沖孔凹模型孔加工出漏料子，裝入沖孔拉深凸凹模，調(diào)整間隙，加工銷釘孔，裝入銷釘，裝入落料凹模，調(diào)整間隙，加工銷釘孔，裝入銷釘，裝入上落料凹模最后進(jìn)行試沖及調(diào)整當(dāng)調(diào)整中發(fā)現(xiàn)頂件力不足時(shí)旋緊緊固螺釘以增大頂件力。 第9章 工件主要成型工藝問題及解決措施 9.1拉深成型工藝質(zhì)量問題及解決措施 拉深過程中主要成型工藝質(zhì)量問題為凸緣變形區(qū)的起皺和筒壁傳力區(qū)的拉裂。前者是因?yàn)榍邢驂簯?yīng)力引起板料失去穩(wěn)定產(chǎn)生彎曲；傳力區(qū)的拉裂是由于拉應(yīng)力超過抗拉強(qiáng)度引起板料斷裂。同時(shí)變形區(qū)板料有所增厚，而傳力區(qū)板料有所變薄。 起皺主要取決于兩個(gè)方面:一方面是切向壓應(yīng)力的大小，其值越大，越容易起皺；另一方面是凸緣變形區(qū)材料本身的抵抗失穩(wěn)的能力，凸緣寬度越大，厚度越薄，材料的E值越小，則材料的抵抗失穩(wěn)的能力越小，容易起皺。 9.2拉裂分析及解決措施 筒壁的拉裂主要取決于兩個(gè)方面：一方面是筒壁傳力區(qū)中的拉應(yīng)力；另一方面是筒壁傳力區(qū)的抗拉強(qiáng)度。當(dāng)筒壁拉應(yīng)力超過該區(qū)材料允許的抗拉強(qiáng)度時(shí)，拉深件就會(huì)在底部圓角與筒壁相切處—“危險(xiǎn)斷面”產(chǎn)生破裂。 為防止拉深過程中，工件的邊壁或凸緣起皺，應(yīng)使毛坯（或半成品）被拉入凹模圓角以前保持穩(wěn)定狀態(tài)。其取決于毛坯的相對(duì)厚度。以上述值查相關(guān)手冊(cè)來(lái)決定是否采取壓邊圈來(lái)防止工件起皺的工藝質(zhì)量問題。由排樣圖可以計(jì)算毛坯的相對(duì)厚度，查表4-80[1]可以得出以下結(jié)論：該工件不用采用壓邊圈來(lái)防止工件的起皺。 為防止工件在拉深過程中出現(xiàn)筒壁拉裂的工藝質(zhì)量問題，一方面要通過改善材料的力學(xué)性能，提高筒壁的抗拉強(qiáng)度；另一方面是通過制定正確的拉深工藝和設(shè)計(jì)模具，合理確定拉深變形程度、凹模圓角半徑、合理改善潤(rùn)滑條件，以降低筒壁傳力區(qū)的拉應(yīng)力。這里要特別注意的是：模具潤(rùn)滑的部位。因?yàn)樵诶畛尚沃?，需要摩擦力小的部位（如凹模?cè)壁和圓角與板料之間的摩擦力），除模具表面粗糙度應(yīng)該小外，還必須潤(rùn)滑，以減小摩擦系數(shù)，減小拉應(yīng)力，提高極限變形程度。而摩擦力對(duì)拉深成形有益的部位，（如凸模側(cè)壁和圓角與板料之間的摩擦力）可以不用潤(rùn)滑。并且此處的表面粗糙度也不宜過小。 致 謝 為期兩個(gè)月的畢業(yè)設(shè)計(jì)以近尾聲,伴隨著它的將是我在校學(xué)習(xí)生涯的結(jié)束.為了給我的學(xué)業(yè)畫一個(gè)圓滿的句號(hào),設(shè)計(jì)中,我仔細(xì)制訂思索,認(rèn)真細(xì)致,不敢有絲毫馬虎,努力做到詳盡、細(xì)致地設(shè)計(jì)每一個(gè)環(huán)節(jié)，每一個(gè)步驟。仔細(xì)地查閱各種資料，使公式、數(shù)據(jù)準(zhǔn)確無(wú)誤。 此工件材料變形很復(fù)雜，尤其是在凸臺(tái)內(nèi)側(cè)及兩凸臺(tái)之間的凸臺(tái)圓弧部分。在過程中，材料補(bǔ)充有困難靠變薄拉深不能滿足要求，很易實(shí)拉破。為了避免此情況，我采取的是預(yù)沖φ20㎜的孔改善了四個(gè)凸臺(tái)內(nèi)側(cè)及凸臺(tái)之間的金屬流動(dòng)；凸臺(tái)外側(cè)采取先拉深到一定嘗試再進(jìn)行落料的辦法，使材料易得到補(bǔ)充。 通過這次畢業(yè)設(shè)計(jì)我基本掌握了如何使用工具手冊(cè)，仔細(xì)了解了模具的結(jié)構(gòu)和裝配過程，熟悉了材料的性能與模具壽命的關(guān)系，完善了設(shè)計(jì)思路。 我的指導(dǎo)老師是于老師，設(shè)計(jì)中，于老師運(yùn)載我悉心報(bào)紙雜志，細(xì)心幫助，在這里表示對(duì)于老師深深的謝意！ 我們最后一年的學(xué)習(xí)任務(wù)較重，多謝各位老師的辛勤教導(dǎo)，在此，對(duì)您們表示衷心的感謝！ 參考文獻(xiàn) 1.王孝培主編.沖壓設(shè)計(jì)資料.北京：機(jī)械工業(yè)出版社.1983 2.丁松聚主編.冷沖模設(shè)計(jì).北京:機(jī)械工業(yè)出版社.1994 3.馮炳堯,韓泰榮,張文森主編.模具設(shè)計(jì)與制造簡(jiǎn)明手冊(cè).上海:科學(xué)技術(shù)出版社.1985 4.許發(fā)樾主編.模具標(biāo)準(zhǔn)應(yīng)用手冊(cè).北京:機(jī)械工業(yè)出版社1884 5.王芳主編.冷沖壓模具設(shè)計(jì)指導(dǎo).北京:工業(yè)出版社1998 6.王運(yùn)炎主編.機(jī)械工程材料.北京:機(jī)械工業(yè)出版社1991 7.李澄,吳天生,周百橋主編.機(jī)械制圖.北京:等教育出版社.1996 8.鄭修本,馮冠大主編.機(jī)械制造工藝學(xué).北京:械工業(yè)出版社1991 9.徐茂功主編.公差與技術(shù)測(cè)量.北京:機(jī)械工業(yè)出版社.1995 10.王衛(wèi)衛(wèi)主編.金屬與塑料成型設(shè)備.北京:機(jī)械工業(yè)出版社.1996 11.程培源,趙仲治主編.模具壽命與材料.武漢:武漢工學(xué)院教材出版中心.1994 12.黃毅宏主編.模具制造工藝（第二版）.北京:械工業(yè)出版社1996 13.李天佑主編,沖模圖冊(cè).北京:機(jī)械工業(yè)出版社.1988 14.模具標(biāo)準(zhǔn)協(xié)會(huì)編. 具標(biāo)準(zhǔn)協(xié)會(huì)匯編.北京:機(jī)械工業(yè)出版社.1994 第 27 頁(yè) 共 27 頁(yè) 編號(hào) 無(wú)錫太湖學(xué)院 畢業(yè)設(shè)計(jì)（論文） 相關(guān)資料 題目： 軸承保持架沖壓模具設(shè)計(jì) 機(jī)電 系 機(jī)械工程及自動(dòng)化專業(yè) 學(xué) 號(hào)： 　　　 0923181　　　 學(xué)生姓名： 呂金勇 指導(dǎo)教師： 　 黃敏（職稱：副教授） 2013年5月25日 無(wú)錫太湖學(xué)院 畢業(yè)設(shè)計(jì)（論文） 開題報(bào)告 題目： 軸承保持架沖壓模具設(shè)計(jì) 機(jī)電 系 機(jī)械工程及自動(dòng)化 專業(yè) 學(xué) 號(hào)： 0923181 學(xué)生姓名： 呂金勇 指導(dǎo)教師： 黃敏 （職稱：副教授） 2012年11月25日 課題來(lái)源 自擬。 科學(xué)依據(jù)（包括課題的科學(xué)意義；國(guó)內(nèi)外研究概況、水平和發(fā)展趨勢(shì)；應(yīng)用前景等） （1）課題科學(xué)意義 隨著與國(guó)際接軌的腳步日益放慢,市場(chǎng)競(jìng)爭(zhēng)的日益加劇,人們對(duì)模具的各種要求也不斷的加大.可以說模具制造技術(shù)是用來(lái)衡量一個(gè)國(guó)家工業(yè)發(fā)展水平的重要標(biāo)志。則現(xiàn)階段的工業(yè)生產(chǎn)中，模具是一種非常重要的工藝裝備。其在各個(gè)行業(yè)中也演繹著非常重要的角色，其運(yùn)用于汽車、機(jī)械、航天、航空、輕工、電子、電器、儀表等行業(yè)。在我國(guó)的模具行業(yè)中有50%的是沖壓模具，足以看出沖壓模具之重要。所以現(xiàn)階段對(duì)于沖壓模具的研究也是非常有必要的。 軸承保持架沖壓模具的研究狀況及其發(fā)展前景 隨著計(jì)算機(jī)技術(shù)的發(fā)展和普及，沖壓模具也基本實(shí)現(xiàn)了計(jì)算機(jī)化，其中使用最多的是cad軟件。抽高壓模具的計(jì)算機(jī)化也是日益發(fā)展趨勢(shì)下不可避免的。近些年來(lái)各種多軸數(shù)控機(jī)床，激光切割機(jī)床數(shù)控雕刻機(jī)床等等紛紛面世，這些設(shè)備在提高模具的數(shù)量，規(guī)模和制造能力上的作用是不可估量的。還有其中快速成形技術(shù)和快速模具技術(shù)這兩種先進(jìn)的制造技術(shù)也越來(lái)越廣泛的應(yīng)用于模具行業(yè)。 中國(guó)的模具行業(yè)每年都保持著25%的增長(zhǎng)率，其行業(yè)的生產(chǎn)能力也僅次于美國(guó)日本，位列世界第三。其行業(yè)生產(chǎn)能力約占世界總量的10%。 然而, 與國(guó)際先進(jìn)水平相比, 中國(guó)的模具行業(yè)的差距不僅表現(xiàn)在精度差距大、 交貨周期長(zhǎng)等方面, 模具壽命也只有國(guó)際先進(jìn)水平的 50% 左右。大型、精密、技術(shù)含量高的轎車覆蓋件沖壓模具和精密沖裁模具是現(xiàn)階段最需要解決的問題。綜上由于市場(chǎng)需求模具的現(xiàn)階段發(fā)展快速，應(yīng)用廣其前景也是也是非?？春玫?。 研究?jī)?nèi)容 ①了解沖壓加工的工作原理，國(guó)內(nèi)外的研究發(fā)展現(xiàn)狀； ②完成軸承保持架沖壓模具的總體方案設(shè)計(jì)； ③完成有關(guān)零部件的選型計(jì)算、結(jié)構(gòu)強(qiáng)度校核及液壓系統(tǒng)設(shè)計(jì)； ④熟練掌握有關(guān)計(jì)算機(jī)繪圖軟件，并繪制裝配圖和零件圖紙，折合A0紙不少于3張； ⑤完成設(shè)計(jì)說明書的撰寫，并翻譯外文資料1篇。 擬采取的研究方法、技術(shù)路線、實(shí)驗(yàn)方案及可行性分析 沖壓是一種利用壓力加工的方法，就是壓力機(jī)上裝上模具對(duì)材料施加壓力。使材料分離或者變形形成合格的所需產(chǎn)品。 沖壓模具材料的確定是一開始必須要確認(rèn)的，其次是沖壓模具的結(jié)構(gòu)設(shè)計(jì)分沖壓工藝的確定和模具結(jié)構(gòu)的設(shè)計(jì)兩個(gè)方面，則需從這兩個(gè)方面入手。最后是對(duì)模具的壓力計(jì)算還有軟件模擬。 研究計(jì)劃及預(yù)期成果 研究計(jì)劃： 2012年11月17日-2013年1月13日：按照任務(wù)書要求查閱論文相關(guān)參考資料，填寫畢業(yè)設(shè)計(jì)開題報(bào)告書,學(xué)習(xí)并翻譯一篇與畢業(yè)設(shè)計(jì)相關(guān)的英文材料。 2013年1月11日-2013年3月5日：指導(dǎo)員實(shí)訓(xùn)。 2013年3月8日-2013年3月14日：查閱與設(shè)計(jì)有關(guān)的參考資料不少于10篇，其中外文不少于5篇,翻譯機(jī)械方面的外文資料。 2013年3月15日-2013年3月21日：軸承保持架工藝分析。 2013年3月22日-2013年4月11日：初步繪制裝配圖和修改完成。 2013年4月12日-2013年4月25日：對(duì)凹凸模尺寸計(jì)算，繪制凹凸模及各零件。 2013年4月26日-2013年5月21日：繪制上下模及其各零件，完成設(shè)計(jì)說明書（論文）、摘要和小結(jié)，修改設(shè)計(jì)說明書開題報(bào)告格式，整理所有資料，打印后上交，準(zhǔn)備答辯。 預(yù)期成果。 特色或創(chuàng)新之處 ① 沖模的使用便于生產(chǎn)自動(dòng)化，操作簡(jiǎn)單，生產(chǎn)率提高。 ② 減少制作軸承保持架的材料。 已具備的條件和尚需解決的問題 ① 已找到大量相關(guān)資料文獻(xiàn)，對(duì)軸承保持架零件有相關(guān)認(rèn)識(shí)。 ② 沖壓工藝的加工工序 指導(dǎo)教師意見 指導(dǎo)教師簽名： 年 月 日 教研室（學(xué)科組、研究所）意見 教研室主任簽名： 年 月 日 系意見 主管領(lǐng)導(dǎo)簽名： 年 月 日 英文原文 Stress Analysis of Stamping Dies J. Mater. Shaping Technoi. (1990) 8:17-22 9 1990 Springer-Verlag New York Inc. R . S . R a o Abstract: Experimental and computational procedures for studying deflections, flit, andalignment characteristics of a sequence of stamping dies, housed in a transfer press, are pre-sented. Die loads are actually measured at all the 12 die stations using new load monitors and used as input to the computational procedure. A typical stamping die is analyzed using a computational code, MSC/NASTRAN, based on finite element method. The analysis is then extended to the other dies, especially the ones where the loads are high. Stresses and deflections are evaluated in the dies for the symmetric and asymmetric loading conditions. Based on our independent die analysis, stresses and deflections are found to be reasonably well within the tolerable limits. However, this situation could change when the stamping dies are eventually integrated with the press as a total system which is the ultimate goal of this broad research program. INTRODUCTION Sheet metal parts require a series of operations such as shearing , drawing , stretching , bending , and squeezing. All these operations are carried out at once while the double slide mechanism descends to work on the parts in the die stations, housed in a transfer press [1]. Material is fed to the press as blanks from a stock feeder. In operation the stock is moved from one station to the next by a mechanism synchronized with the motion of the slide. Each die is a separate unit which may be independently adjusted from the main slide. An automotive part stamped from a hot rolled steel blank in 12 steps without any intermediate anneals is shown in Figure 1. Transfer presses are mainly used to produce different types of automotive and aircraft parts and home appliances. The economic use of transfer presses depends upon quantity production as their usual production rate is 500 to 1500 parts per hour [2]. Although production is rapid in this way, close tolerances are often difficult to achieve. Moreover, the presses produce a set of conditions for off-center loads owing to the different operations being performed simultaneously in several dies during each stroke. Thus, the forming load applied at one station can affect the alignment and general accuracy of the operation being performed at adjacent stations. Another practical problem is the significant amount of set-up time involved to bring all the dies into proper operation. Hence, the broad goal of this research is to study the structural characteristics of press and dies combination as a total system. In this paper, experimental and computational procedures for investigating die problems are presented. The analysis of structural characteristics of the transfer press was pursued separately [3]. A transfer press consisting of 12 die stations was chosen for analysis. Typical die problems are excessive deflections, tilt, and misalignment of the upperand lower die halves. Inadequate cushioning and offcenter loading may cause tilt and misalignment of the dies. Tilt and excessive deflections may also be caused by the lack of stiffness of the die bolster and the die itself. Part quality can be greatly affected by these die problems. There are a lot of other parameters such as the die design, friction and lubrication along the die work interface, speed, etc. that play a great role in producing consistently good parts. Realistically, the analysis should be carded out by incorporating the die design and the deforming characteristics of the work material such as the elastic-plastic work hardening properties. In this preliminary study, the large plastic deformation of the workpiece was not considered for the reasons mentioned below. Large deformation modeling of a sheet stretching process was carded out using the computational code based on an elastic-plastic work hardening model of the deformation process [4]. Laboratory experiments were conducted on various commercial materials using a hemispherical punch. The coefficient of friction along the punch-sheet interface was actually measured in the experiment and used as a prescribed boundary to the numerical model. Although a good solution was obtained, it was realized that the numerical analysis was very sensitive to the frictional conditions along the interface. In the most recent work, a new friction model based on the micromechanics of the asperity contact was developed [5]. In the present problem, there are several operations such as deep drawing, several reduction drawing operations, and coining, which are performed using complex die geometries. The resources and the duration of time were not adequate to study these nonlinear problems. Hence,the preliminary study was limited to die problems basedon linear stress analysis. A detailed die analysis was carried out by using MSC /NASTRAN code based on finite ele mentmethod. Die loads were.measured at all the stations using new load monitors. Such measured data were used in the numerical model to evaluate stresses and deflections in the dies for normal operating conditions and for asymmetric loading conditions. Asymmetric loading conditions were created in the analysis by tilting the dies. In real practice, it is customary to pursue trial-and-error procedures such as placing shims under the die or by adjusting the cushion pressure to correct the die alignment problems. Such time consuming tasks can be reduced or even eliminated using the computational and experimental procedures presented here. DIE GEOMETRY AND MATERIALS The design of metal stamping dies is an inexact process. There are considerable trial-and-error adjustments during die tryout that are often required to finish the fabrication of a die that will produce acceptable parts. It involves not only the proper selection of die materials, but also dimensions. In order to withstand the pressure, a die must have proper cross-sectional area and clearances. Sharp comers, radii, fillets, and sudden changes in the cross section can have deleterious effects on the die life. In this work, the analysis was done on the existing set of dies. The dies were made of high carbon, high chromium tool steel. The hardness of this tool steel material is in the range of Rockwell C 57 to 60. Resistance to wear and galling was greatly improved by coating the dies with titanium nitride and titanium carbide. The dies were supported by several other steel holders made of alloy steels such as SAE 4140. The geometry of a typical stamping die is axisymmetric but it varies slightly from die to die depending on the operation. Detailed information about geometry andmaterials of a reduction drawing die (station number 4) was gathered from blueprints. It was reproducedin three-dimensional geometry using a preprocessor, PATRAN. One quadrant of the die is shown in Figure2. The data including geometry and elastic properties of the die material were fed to the numerical model. The work material used was hot rolled aluminumkilled steel, SAE 1008 A-K Steel and the blank thickness was about 4.5 ram. Stampings used in unexposed places or as parts of some deisgn where fine finish is not essential are usually made from hot rolled steel. The automotive part produced in this die set is a cover for a torque converter. A principal advantage of aluminum-killed steel is its minimum strain aging. EXPERIMENTAL PROCEDURES As mentioned earlier, this research involved monitoting of die loads which were to be used in the numerical model to staldy the structural characteristicsof dies. The other advantage is to avoid overloadingthe dies in practice. Off-center loading can be detected and also set-up time can be reduced. Thus, any changes in the thickness of stock, dulling of the die,unbalanced loads, or overloadings can be detected using die load monitors. Strain gage based fiat load cells made of high grade tool steel material were fabricated and supplied by IDC Corporation. Four identical load cells were embedded in a thick rectangular plate as shown in Figure 3. They were calibrated both in the laboratory and in the plant.The plate was placed on the top of the die. The knockout pin slips through the hole in the plate. Six such plates were placed on each of six dies. In this way,24 readings can be obtained at a given time. Then they were shifted to the other six dies for complete data. All the 12 die loads are presented in Table 1. COMPUTATIONAL PROCEDURES Linear static analysis using finite element method wasused to study the effect of symmetric and asymmetric loading for this problem. A finite element model of die station 4 was created using the graphical preprocessor, PATRAN, and the analysis was carried outusing the code MSC/NASTRA N . The code has a wide T a b l e I. Die Loads Die Station Load Number (kN) 1 356 2 641 3 214 4 356 5 854 6 712 7 285 8 32O 9 2349 10 1139 11 214 12 2100 spectrum of capabilities, of which linear static analysis is discussed here. The NASTRAN code initially generates a structural matrix and then the stiffness and the mass matrices from the data in the input file. The theoretical formulations of a static structural problem by the displacement method can be obtained from the references [6]. The unknowns are displacements and are solved for the appropriate boundary conditions. Strains are obtained from displacements. Then they are converted into stresses by using elastic stress-strain relationships of the die material. The solution procedure began with the creation of die geometry using the graphical preprocessor, PATRAN. The solution domain was divided into appropriate hyper-patches. This was followed by the generation of nodes, which were then connected by elements. Solid HEXA elements with eight nodes were used for this problem. The nodes and elements were distributed in such a way that a finer mesh was created at the critical region of the die-sheet metal interface and a coarser mesh elsewhere. The model was then optimized by deleting the unwanted nodes. The element connectivities were checked. By taking advantage of the symmetry, only one quarter of the die was analyzed. In the asymmetric case, half of the die was considered for analysis. Although, in practice, the load is applied at the top of the die, for the purpose of proper representation of the boundary conditions to the computational code, reaction forces were considered for analysis. The displacement and force boundary conditions are shown for the two cases inFigure 4. As mentioned earlier, sheet metal was not modeled in this preliminary research. As shown in Figure 4(a),the nodes on the top surface of the die were constrained (stationary surface) and the measured load of 356 kN was equally distributed on the contact nodes at the workpiece die interface. Similar boundary conditions for the punch are shown in Figure 4(b). It is noticeable that fewer nodes are in contact with the sheet metal due to the die tilt for the asymmetric loading case as shown in Figure 4(c). In real practice, the pressure actually varies along the die contact surface. Since the actual distribution was not known, uniform distribution was considered in the present analysis. DISCUSSION OF RESULTS As described in the earlier section, the numerical analysis of die Station 4 (both the die and punch) was performed using the code MSC/NASTRAN . Two cases were considered, namely: (a) symmetric loading and (b) asymmetric loading Fig. 4. Boundary conditions. (A) Symmetric case (onequadrant of the die). (B) Symmetric case (one quadrant ofnthe punch). (C) Asymmetric case (half of the die). Symmetric Loading Numerical analysis of the die was carried out for a measured load o f 356 kN as distributed equally in Figure 4(a). The major displacements in the loading direction are shown in Figure 5(a). These displacement contours can be shown in various colors to represent different magnitudes. The m aximum displacement value is 0.01 m m for a uniformly distributed load of 356 kN. The corresponding critical stress is very small, 8.4 MPa in the y direction and 30 MPa in the x direction. The calculated displacements and stresses at the surrounding elements and nodes were of the same order, but they decreased in magnitude at the nodes away from this critical region. Thus, the die was considered very rigid under this loading condition. Symmetric loading was applied to the punch and the numerical analysis was carried out separately. The displacement values in the protruding region of the punch were high compared to the die. The maximum displacement was 0.08 m m . It should be noted that the displacement values in this critical range of the punch were of the same order ranging from 0.05 mm to 0.08 ram. Although the load acting on the punch (bottom half) was the same as the die (upper half), that is, 356 kN, the values of displacements and stresses were higher in the punch because of the differences in the geometry. This is especially true for the protruding part of the punch. The corresponding maxim u m stress was 232 MPa. This part of the punch is still in the elastic range as the yield strength of tool steel is approximately 1034 MPa. The critical stress value might be varied for different load distributions. Since the actual distribution of the load was not known,the load was distributed equally on all nodes. As the die (upper half) is operating in a region which is extremely safe, a change in the load distribution may not produce any high critical stresses in the die. Although higher loads are applied at other die stations(see Table 1), it is concluded that the critical stresses are not going to be significantly higher due to the appropriate changes in the die geometries. Asymmetric Loading For the purpose of analysis, an asymmetric loading situation was created by tilting the die. Thus, only 15 nodes were in contact with the workpiece compared to 40 nodes for the symmetric loading case. As shown in Figure 4(c), a 356 kN load was uniformly distributed over the 15 nodes that were in contact with the workpiece. Although the pressure was high, because of the geometry at the location where the load was acting, the critical values of displacement and stress were found to be similar to the symmetric case. The predicted displacement and stress values were not significantly higher than the values predicted for the symmetric case. Fig. 5. Displacement contours in the loading direction. (A) Symmetric case (one quadrant of the die). (B) Symmetric case (one quadrant of the punch). (C)Asymmetric case (half of the die). CONCLUSIONS In this preliminary study, we have demonstrated the capabilities of the computational procedure, based on finite element method, to evaluate the stresses and deflections within the stamping dies for the measured loads. The dies were found to be within the tolerable elastic limits for both symmetric and asymmetric loading conditions. Thus the computational procedure can be used to study the tilt and alignment characteristics of stamping dies. In general, the die load monitors are very useful not only for analysis but also for on-line tonnage control. Future research involves the integration of the structural analysis of stamping dies with that of the transfer press as a total system. ACKNOWLEDGMENTS Professor J.G. Eisley, W.J. Anderson, and Mr. D.Londhe are thanked for their comments on this paper. REFERENCES 1. R.S. Rao and A. Bhattacharya, "Transfer Process De-flection, Parallelism, and Alignment Characteristics,"Technical Report, January 1988, Department of Mechanical Engineering and Applied Mechanics, the University of Michigan, Ann Arbor. 2. Editors of American Machinist, "Metalforming: Modem Machines, Methods, and Tooling for Engineers and Operating Personnel," McGraw-Hill, Inc., 1982, pp. 47-50. 3. W.J. Anderson, J.G. Eisley, and M.A. Tessmer,"Transfer Press Deflection, Parallelism, and Alignment Characteristics," Technical Report, January 1988, Department of Aerospace Engineering, the University of Michigan, Ann Arbor. 4. B.B. Yoon, R.S. Rao, and N. Kikuchi, "Sheet Stretching: A Theoretical Experimental Comparison," International Journal of Mechanical Sciences, Vol. 31, No.8, pp. 579-590, 1989. 5. B.B. Yoon, R.S. Rao, and N. Kikuchi, "Experimental and Numerical Comparisons of Sheet Stretching Using a New Friction Model," ASME Journal of Engineering Materials and Technology, in press. 6. MSX/NASTRAN, McNeal Schwendler Corporation.22 9 J. Materials Shaping Technology, Vol. 8, No. 1, 1990 中文譯文 沖壓模具的受力分析 R.S.Rao J.Mater.Shaping Tec