煙灰缸蓋的沖壓工藝及模具設(shè)計【10張CAD圖紙+PDF圖】
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煙灰缸蓋的沖壓工藝及模具設(shè)計 學(xué) 生:周茂賢指導(dǎo)老師:董亮(湖南農(nóng)業(yè)大學(xué)工學(xué)院,長沙410128)摘 要:本設(shè)計應(yīng)用本專業(yè)所學(xué)的模具理論和生產(chǎn)實際知識進(jìn)行一次冷沖壓模具設(shè)計,其中包括了落料拉深復(fù)合模和沖孔翻邊復(fù)合模的設(shè)計,并詳細(xì)地描述復(fù)合模具的結(jié)構(gòu)如凸、凹模,定位零件,導(dǎo)向零件,卸料與推件裝置,連接與固定零件等的設(shè)計過程,重要零件的工藝參數(shù)的選擇與計算以及各個參數(shù)的校核。這次模具設(shè)計的目的在于提高學(xué)生獨立工作能力,鞏固與擴充了冷沖壓模具設(shè)計等課程所學(xué)內(nèi)容。關(guān)鍵詞:落料拉深;沖孔翻邊;工藝分析The Stamping and Mold Design of Ashtray CoverStudent:Zhou MaoxianTutor:Dong Liang(College of Engineering , Hunan Agriculturial University,Changsha 410128,China)Abstract: This paper applied the professional mould theory and production to learn a practical knowledge of cold stamping mould design, including the blanking deep drawing composite membrane and punching flanging composite membrane design.The paper describes in detail the structure of a ramming mold,for example bulge and concave mold,locating elements,guide element,ex-denning and liftout attachment and so on, choice and compute technological parameter of important components and examinute each parameter. The mould design purpose was to improve students ability to work independently, consolidate and expand cold stamping mould design lessons content. Key word:blanking drawing; punching flanging; process analysis1 前言隨著科學(xué)技術(shù)的發(fā)展需要,模具已成為現(xiàn)代化不可缺少的工藝設(shè)備,模具設(shè)計是機械專業(yè)一個最重要的教學(xué)環(huán)節(jié),而且模具是工業(yè)生產(chǎn)中的基礎(chǔ)工藝裝備,是一種高附加值的高技術(shù)密集型產(chǎn)品,也是高新技術(shù)產(chǎn)業(yè)的重要領(lǐng)域,其技術(shù)水平的高低已成為衡量一個國家制造水平的重要標(biāo)志。沖壓成型作為現(xiàn)在工業(yè)中一種十分重要的加工方法,用以生產(chǎn)各種板料零件,具有很多獨特的優(yōu)勢,其成型件具有自重輕、剛度大、強度高、互換性好、成本低、生產(chǎn)過程便于實現(xiàn)機械自動化及生產(chǎn)效率高等優(yōu)點,是一種其他加工方法所不能相比和不可替代的先進(jìn)制造技術(shù),在制造業(yè)中具有很強的競爭力,被廣泛應(yīng)用于汽車、能源、機械、信息、航空航天、國防工業(yè)和日常生活的生產(chǎn)之中。在吸收了力學(xué)、數(shù)學(xué)、金屬材料學(xué)、機械科學(xué)以及控制、計算機技術(shù)等方面的知識后,已經(jīng)形成了沖壓學(xué)科的成形基本理論1。以沖壓產(chǎn)品為龍頭,以模具為中心,結(jié)合現(xiàn)代先進(jìn)技術(shù)的應(yīng)用,在產(chǎn)品的巨大市場需求刺激和推動下,沖壓成形技術(shù)在國民經(jīng)濟發(fā)展、實現(xiàn)現(xiàn)代化和提高人民生活水平方面發(fā)揮著越來越重要的作用。據(jù)中國模具工業(yè)協(xié)會發(fā)布的統(tǒng)計材料,2006年我國模具總產(chǎn)值約為710億元,出口10.41億元,進(jìn)口10.49億元。我國模具行業(yè)經(jīng)濟活動總還有以下幾個特點:(1)總產(chǎn)值中2/3為自用,1/3為商品銷售;(2)制造模具的比重為沖壓模占50%,塑料模占33%,壓鑄模占6%,其他占11%;(3)進(jìn)口模具的比重為塑料模大于沖壓模;(4)模具進(jìn)口依次為日本,臺灣地區(qū),韓國,香港地區(qū),歐美各國2。本設(shè)計應(yīng)用本專業(yè)所學(xué)課程的理論和生產(chǎn)實際知識進(jìn)行一次冷沖壓模具設(shè)計工作的實際訓(xùn)練從而培養(yǎng)和提高學(xué)生獨立工作能力,鞏固與擴充了冷沖壓模具設(shè)計等課程所學(xué)的內(nèi)容,掌握冷沖壓模具設(shè)計的方法和步棸,掌握冷沖壓模具設(shè)計的基本的模具技能,并懂得了怎么樣分析零件的工藝性,怎么樣確定工藝方案,了解了模具的基本結(jié)構(gòu),提高了計算能力,繪圖能力,熟悉了規(guī)范和標(biāo)準(zhǔn),同時各科相關(guān)的課程都有了全面的復(fù)習(xí),獨立思考的能力也有了提高。采用落料拉深復(fù)合模,能較好地實現(xiàn)落料及落料件的修邊,模具設(shè)計制造也簡便易行。落料拉深效果好,能極大地提高生產(chǎn)效率,但落料拉深凹模的設(shè)計較為重要,設(shè)計中應(yīng)充分考慮其落料拉深??谛螤?,否則易影響落料拉深件的形狀。主要工序包括:a落料拉深復(fù)合模加工,b沖孔翻邊復(fù)合模加工,c成型。本設(shè)計分別論述了產(chǎn)品工藝分析,沖壓方案的確定,工藝計算,模板及零件設(shè)計,模具組立等問題。本設(shè)計的內(nèi)容是確定復(fù)合模內(nèi)型和結(jié)構(gòu)形式以及工藝性,繪制模具總圖和非標(biāo)準(zhǔn)件零件圖。這次畢業(yè)設(shè)計的目的有兩個:一是讓學(xué)生掌握了查詢資料和手冊的能力,并能夠很好的理解課程上所學(xué)習(xí)的知識。二是掌握了模具設(shè)計的方法和步棸,了解了模具加工的工藝過程。2 煙灰缸蓋的工藝性分析圖1 零件外形圖Fig1 Appearance picture of the part如圖所示,該工件為軸對稱拉深件,在圓周方向上的變形也是均勻的,模具的加工也比較容易,但是中間有個內(nèi)凹孔,這就不得不用翻邊來完成工件的加工。(1)從工件形狀上看,屬于圓筒形拉深件,其主要問題是考慮圓筒形件是否可以一次拉成。 (2)由于中間有內(nèi)凹孔,所以也要判斷是否可以一次翻邊成功。 (3)由于該工件精度要求不高,不需要擴孔跟出毛坯等提高加工精度的步棸3。2.1 沖壓工藝方案的分析和比較(1)方案1先落料拉深采用連續(xù)模,再沖孔,最后翻邊(2)方案2先落料拉深復(fù)合,再沖孔,最后翻邊(3)方案3先落料拉深復(fù)合,再沖孔翻邊復(fù)合方案的比較就是沖壓件的工藝路線的比較,主要包括沖壓工序數(shù),工序的組合和順序的比較等。確定合理的沖裁工藝方案應(yīng)在不同的工藝方面進(jìn)行全面的分析與研究,比較其綜合的經(jīng)濟技術(shù)效果,選擇一個合理的沖壓工藝方案。方案1雖然考慮到零件拉深工藝的復(fù)雜性,減少了產(chǎn)品的沖壓成型時間,但是模具結(jié)構(gòu)復(fù)雜且精度要求高,制造周期長,制模成本高,加工也不方便。而方案二雖然用落料拉深復(fù)合模相應(yīng)地提高了成型的速度,但是后面2個工序卻增加了制造的周期。相比之下方案三由于采用落料拉深復(fù)合模和沖孔翻邊復(fù)合模就大大地提高了成型的速度,使得模具制造周期短,制造低廉,工人操作安全,方便可靠。2.2 確定排版、裁板方案在沖壓生產(chǎn)中,節(jié)約金屬和減少廢料具有非常重要的意義,特別是在大批量生產(chǎn)中,合理的排樣和選擇適當(dāng)?shù)拇钸呏凳墙档统杀?、保證工件質(zhì)量及延長模具壽命的有效措施。此沖裁件為圓形,采用無廢料排樣不可能,而采用少廢料排樣影響了工件的質(zhì)量和精度,同時還會縮短模具的壽命,所以采用直排的方式來確定排樣方案4。排樣方式如圖所示:圖2 排樣圖Fig2 Layout drawing按表1查得最小搭邊值:a = 1.5mm,a1 = 1.5mm 條料寬度:b = 138+2a =141mm 進(jìn)距:h = 138+a1 = 139.5mm 一個進(jìn)距的材料利用率=nA/bh100%=76% (1)式中:A-沖裁件面積, n-一個進(jìn)距沖裁件數(shù)目; b-條料寬度,mm; h-進(jìn)距,mm。表1 沖裁金屬材料的搭邊值Table1 Punching metal structures on the value side 料厚 圓形 非圓形 往復(fù)送料 自動送料 a a1 a a1 a a1 a a11 1.5 1.5 2 1.5 3 2 - - 12 2 1.5 2.5 2 3.5 2.5 3 223 2.5 2 3 2.5 4 3.5 - -34 3 2.5 3.5 3 5 4 4 345 4 3 5 4 6 5 5 456 5 4 6 5 7 6 6 568 6 5 7 6 8 7 7 6 8 7 6 8 7 9 8 8 7 3 落料拉深復(fù)合模工序設(shè)計計算3.1 沖壓件的工藝分析此工件為無凸緣圓筒形件,要求內(nèi)形尺寸,沒有厚度不變的要求。工件底部圓角半徑rt=8mm,大于拉深凸模圓角半徑rp =46mm(查表4.31的首次拉深凹模圓角半徑rd,而rp=(061)rd=46mm),滿足要求。最后按公差表查得工件為IT14級,滿足拉深工序?qū)ぜ畹燃壍囊蟆?.1.1 計算毛坯直徑D根據(jù)毛坯尺寸的確定原則可知有兩種方法來計算毛坯的計算原則:1.面積相等原則:由于拉深前和拉深后材料的體積不變,對于不變薄拉深,假設(shè)材料厚度拉深前后不變,拉深毛坯的尺寸按“拉深前后的表面積相等”來確定。2.形狀相似原則:拉深毛坯的形狀一般與拉深件橫截面的形狀相似,即當(dāng)零件的形狀是圓形或橢圓形時,其拉深前毛坯的展開形狀也基本上是圓形或橢圓形5。如圖1所示,h =(25.5-0.5)= 25mm,d =(100-1)= 99。工件的相對高度h/d = 25mm/99mm =0.253。根據(jù)相對高度從表2中查得修邊余量h = 2mm。由表2序號1,查得無凸緣圓筒形拉深工件的毛坯尺寸計算公式為D (2)將d =99mm,H =h+h = 27mm,r =8+0.5 = 8.5mm代入上式得D =138mm表2 常用旋轉(zhuǎn)體拉深件毛坯直徑的計算公式Table2 Common rotation drawing parts formula for calculating the blank diameter序 號 工作形狀 毛坯直徑D1 (d+4d(H+)-1.72rd-0.56r)3.1.2 判斷拉深次數(shù)工件總的拉深系數(shù):m總 = d/D = 99/138 = 0.7 (3)毛坯相對厚度:t/D = 1/138 = 0.0072 (4) 采用壓邊圈的條件:用式來判斷是否需要壓邊。因,故需加壓邊圈。由相對厚度可以從表3中查得首次拉深的極限拉深系數(shù)m=0.54因m總m1,故工件只需一次拉深。表3 無凸緣圓筒形工件的多次拉深Table3 No lugs cylindrical workpieces repeatedly deep drawing拉深因數(shù) 毛坯的相對厚度t/D*100 21.5 1.51.0 1.00.5 0.60.3 0.30.15 m1 0.480.50 0.500.53 0.530.55 0.550.58 0.580.60 m2 0.730.75 0.750.76 0.760.78 0.780.79 0.790.80 m3 0.760.78 0.780.79 0.790.80 0.800.81 0.810.82 m4 0.780.80 0.800.81 0.810.82 0.820.83 0.830.85 m5 0.800.82 0.820.83 0.830.85 0.850.86 0.860.873.2 落料拉深的相關(guān)計算3.2.1 確定工藝方案本工件首先需要落料制成D = 138mm的圓片,然后以D = 138mm的圓板料為毛坯進(jìn)行拉深,拉深成外徑為1000-0.87mm、內(nèi)圓角R為8mm的無凸緣圓筒,最后按h = 25.5mm進(jìn)行修邊。3.2.2 進(jìn)行必要的計算(1)計算落料力、壓邊力、拉深力落料力是選擇壓力機的主要依據(jù),也是設(shè)計模具所必需的數(shù)據(jù)。一般包括彈性變形階段,塑性變形階段,分離階段三部分。彈性變形階段當(dāng)凸模對板料施壓,是材料產(chǎn)生彈性變形。板料稍微擠入凹???。板料與凸凹模接觸處成很小的圓角。由于凸凹模之間存在間隙,板料同時受到彎曲和拉伸的作用,凸模下的板料產(chǎn)生彎曲,凹模上的板料開始上翹。塑性變形階段當(dāng)凹模繼續(xù)壓到一定深度時,材料內(nèi)部應(yīng)力達(dá)到屈服點,板料開始在與凸模、凹模的刃口接觸處產(chǎn)生塑性變形。隨著沖壓過程的繼續(xù),應(yīng)力不斷增加,材料的變形程度便不斷增加,變形區(qū)向板材的深度方向擴展,直至凸、凹模刃口處達(dá)到極限應(yīng)力和應(yīng)變值,材料即產(chǎn)生微小變形。分離階段裂紋產(chǎn)生后,隨凸模繼續(xù)壓入,凸凹模刃口附近產(chǎn)生的微裂紋沿最大剪應(yīng)變速度方向不斷向板材內(nèi)部擴展。若間隙合適,上、下裂紋則相遇重合,板料上下部分離。落料力F=KLt6式中:F-沖裁力; L-沖裁件的周長; t-材料的厚度; -材料的抗剪強度; K-安全系數(shù),取K=1.3。在一般情況下材料的強度極限1.3,為方便計算,則沖裁力F可由下式計算: F=Lt 取10鋼的強度極限=430MPa, t = 1mm,L = 433mm 代入數(shù)值計算: F=Lt=186327N (4)卸料力 F卸=K卸F 查表2.10得K卸=0.05,則 F卸=9316.35N (5)頂出力 F頂=K頂F 查表2.10得K頂=0.06,則 F頂=11179.62N (6)推件力 F推=nK推F 查表2.10得K推=0.055,則 F推=10247.985N (7) 選擇沖床時的總沖壓力:F總= F+F卸+F頂+F推=217070.96N (8) 拉伸所用的模具主要由凸模、凹模和壓邊圈組成。與沖裁不同的是,凸模、凹模工作部分沒有鋒利的刃口,而是有一定的圓角半徑,并且其間隙較稍大于板料的厚度。在凸模的壓力下、直徑為D、厚度而為t的圓形板料逐漸被拉入凹模洞口,得到外徑為d、高度為H的開口圓形工件。由表4確定壓邊力的計算公式為 (9)式中,單邊壓邊力; 平板毛坯直徑; 第1n次拉深直徑;r凹-拉深凹模圓角半徑;式中rd = rp = 8mm,D = 116mm,d1 = 74,由相關(guān)資料查得p=2.7MPa代入上式,得壓力為FQ=13225N表4 壓邊力的計算公式Table4 Put pressure on our side of the formula 拉深情況 公式 拉深任何形狀的工件 FQ = Ap 圓筒形件的第一次拉深(用平板毛坯) FQ = /4D-(d1+2rd)p圓筒形件以后各次拉深(用筒形毛坯) FQ = /4(dn-1-dn)p查表5計算拉深力為 (10)式中,拉深件的直徑; 材料厚度;材料的強度極限; 拉深力;系數(shù);已知m = 0.7,由表5查得K1=0.52,10鋼的強度極限=430MPa式中d = 99mm,t = 1mm,得出F = 69544N表5 計算拉深力的使用公式Table5 Using formula calculation of drawing force拉深件型式 拉深工序 公式 查系數(shù)k的表格編號無凸緣圓筒形件 第1次 FL = k1d1tb 查表8 第2次及以后 FL = k2d2tb 查表9查相關(guān)資料,壓力機的公稱壓力為F壓 1.4(FQ+F)= 114627N 故選用的壓力機公稱壓力要大于125KN??紤]到壓力機的使用安全,選擇壓力機的噸位時,總工藝力F一般不應(yīng)超過壓力機額定噸位的80%。壓力機選用J23-35開式可傾壓力機公稱壓力為350KN(2)模具工作部分尺寸的計算拉深模的間隙 拉深間隙是指凸凹模橫向尺寸的差值,雙邊間隙用Z表示。間隙過小,工件質(zhì)量較好,但拉深力大工件容易拉斷,模具磨損嚴(yán)重,壽命低。間隙過大,拉深力小,模具壽命提高了,但工件易起皺變厚,側(cè)壁不直,口部邊線不齊,有回彈,質(zhì)量不能保證。因此,確定間隙的原則是:既要考慮到板料公差的影響,又要考慮毛坯口部增厚現(xiàn)象,故間隙值一般應(yīng)比毛坯厚度略大一些,其值按下式計算;單面間隙: 式中,板料的最大厚度,; 板料的厚度;板料的正偏差;間隙系數(shù),考慮到板料增厚現(xiàn)象;由表6可知有壓邊圈拉深時,拉深模的單邊間隙為:Z/2 = 1.1mm: 表6 有壓邊圈拉深時的單邊間隙值Table6 Unilateral clearance of the blank holder drawing value總拉深次數(shù) 拉深工序 單邊間隙Z/2 1 一次拉深 (11.1)t 2 第一次拉深 1.1t 第二次拉深 (11.05)t拉深模圓角半徑圓角半徑對拉深過程的影響拉深力是通過凸模圓角傳遞到被拉深工件上的,位于凸模圓角處的工件材料是最容易破裂的,“危險斷面”凸模圓角半徑r增大,則該處拉深件材料因厚度變薄量減小而強度增大,所傳遞的極限拉深力F也增大,因而可以減小拉深系數(shù)m。拉深模的凹模圓角半徑要取得適當(dāng),如果增大凹模圓角半徑ra則材料拉入凹模時的阻力減小,拉深系數(shù)m也減小,但當(dāng)如果當(dāng)ra取得過大,則有更多的材料未被壓料圈壓住,而容易起皺。在拉深工件時,對于變形量較大處,就需要用較大的ra,由于在矩形件拉深時,角部的變形量最大,為了使金屬的流動性較為均勻,角部的凹模圓角半徑應(yīng)比直邊處的凹模圓角半徑大。圓角半徑數(shù)值凹模的圓角半徑rd按表7選取,rd = 8t = 8mm。凸模的圓角半徑r等于工件的內(nèi)圓角半徑,即rp = r = 8mm。 表7 首次拉深凹模的圓角半徑Table7 Deep drawing die for the first time the fillet radius拉深件形式 毛坯的相對厚度t/D*100 2.01.0 1.00.3 0.30.1 有凸緣 (46)t (68)t (812)t 無凸緣 (812)t (1215)t (1520)t拉深凸、凹模工作部分的尺寸和公差。由于工件要求外形尺寸,則以凹模為設(shè)計基準(zhǔn)。已知 = 0.87,將模具公差按IT11級選取,則p = 0.22凸模的尺寸按表8計算,即Dp =(Dmax-0.75-Z)+P0 = 97.15+0.220 (11) 凹模尺寸的計算見表8得Dd=(Dmax -0.75)+d0 =99.350-0.22 (12) 式中,Dmax -為工件外形的最大尺寸;-工件的公差;凸凹模的制造公差;表8 拉深模徑向尺寸計算公式Table8 Radial size drawing die formula尺寸標(biāo)準(zhǔn)方式 凹模尺寸 凸模尺寸 標(biāo)注內(nèi)形尺寸 中間拉深dd = (dmin+Z)+d0 中間拉深dp = dmin0-p 末次拉深 末次拉深 dd = (dmin+0.4+Z)+d0 dp = (dmin+0.4)0-p 標(biāo)注外形尺寸 中間拉深Dd = Dmax+d0 中間拉深Dp = (Dmax-Z)0-p 末次拉深 末次拉深 Dd = (Dmax-0.75)+d0 Dp = (Dmax-Z-0.75)0-p3.2.3 確定凸模的通氣孔由表9查得,凸模的通氣孔直徑為8mm。表9 拉深凸模出氣孔尺寸Table9 Drawing a pore size of the punch凸模直徑dp/mm 50100 100200 200 出氣孔直徑d/mm 5 6.5 8 9.5 數(shù)量 按圓周直徑5060均步47個成一組3.2.4 落料凸、凹模工作部分的尺寸和公差查表10的間隙值Zmin = 0.13mm,Zmax = 0.16mm。 表10 落料、沖孔模刃口始用間隙Table10 Blanking, piercing begins with cutting edge gap材 45 10、15、20 Q215、Q235鋼板 H62、H68(軟)、 酚醛環(huán)氧層壓 鋼紙板、料 T7、T8(退火)30鋼板 0.8、10.15鋼板 防銹剛 玻璃布板 云母板名 稱力學(xué)性能 600MPa 400600 300400MPa 300MPa厚度t 初始間隙Z Zmin Zmax Zmin Zmax Zmin Zmax Zmin Zmax Zmin Zmax Zmin Zmax 0.1 0.015 0.035 0.01 0.03 - - - - - - - - 0.2 0.025 0.045 0.015 0.035 0.01 0.03 - - - - - - 0.3 0.04 0.06 0.03 0.05 0.02 0.04 0.01 0.03 - - - - 0.5 0.08 0.10 0.06 0.08 0.04 0.06 0.025 0.045 0.01 0.02 - - 0.8 0.13 0.16 0.10 0.13 0.07 0.10 0.045 0.075 0.015 0.03 - - 1.0 0.17 0.20 0.13 0.16 0.10 0.13 0.065 0.095 0.025 0.04 - -1.2 0.21 0.24 0.16 0.19 0.13 0.16 0.075 0.105 0.035 0.05 - -1.5 0.27 0.31 0.21 0.25 0.15 0.19 0.10 0.14 0.004 0.05 - -查表11的磨損系數(shù)x = 0.5,=1,取合理最小間隙為0.15mm 表11 磨損系數(shù)xTable11 Wearing and tearing coefficient of form x材料厚度t/mm 非圓形 圓形 1 0.75 0.5 0.75 0.5 工件公查/mm 1 0.16 0.170.35 0.36 12 0.20 0.210.41 0.42 24 0.24 0.250.49 0.50 4 0.30 0.310.59 0.60 3080 0.020 0.02080120 0.025 0.035120180 0.030 0.0403.2.5 落料拉深模具總體設(shè)計(1)確定導(dǎo)向方式 方案一采用對角導(dǎo)柱模架。由于導(dǎo)柱安裝在模具壓力中心對稱的對角線上,所以上模座在導(dǎo)柱上滑動平穩(wěn)。常用于橫向送料級進(jìn)模或縱向送料的落料模、復(fù)合模。 方案二采用后側(cè)導(dǎo)柱模架。由于前面和左、右不受限制,送料和操作比較方便。方案三四導(dǎo)柱模架。具有導(dǎo)向平穩(wěn)、導(dǎo)向準(zhǔn)確可靠、剛性好等優(yōu)點。常用于沖壓件尺寸較大或精度要求較高的沖壓零件,以及大量生產(chǎn)用的自動沖壓模架。 方案四中間導(dǎo)柱模架。導(dǎo)柱安裝在模具的對稱線上,導(dǎo)向平穩(wěn)、準(zhǔn)確。 根據(jù)以上方案比較并結(jié)合模具結(jié)構(gòu)形式和送料方式,為提高模具壽命和工件質(zhì)量,該落料拉伸模采用后側(cè)導(dǎo)柱模架的導(dǎo)向方式。(2)定位方式的選擇 定位零件是用來保證條料的正確送進(jìn)及在模具中的正確位置,以保證沖制出合格的零件。條料在模具送料平面中必須有兩個方向的限位:一是在與條料方向垂直方上的限位,保證條料沿正確的方向送進(jìn)成為送進(jìn)導(dǎo)向;二是在送料方向的限位,控制條料一次送進(jìn)的距離。 導(dǎo)料銷的選擇 屬于送料導(dǎo)向的定位零件有導(dǎo)料銷,導(dǎo)料板、側(cè)壓板等。導(dǎo)料板及側(cè)壓板多用于級進(jìn)模和單工序模中。導(dǎo)料銷則多用于復(fù)合模和單工序模中。因此選導(dǎo)料銷做為導(dǎo)向且位于條料的同側(cè),一般設(shè)2個,從前向后送料時導(dǎo)料銷裝在左側(cè),為標(biāo)準(zhǔn)件。 擋料銷的選擇屬于送料定距的定位零件有擋料銷、導(dǎo)正銷、側(cè)刃等,導(dǎo)正銷及側(cè)刃多用于級進(jìn)模和單工序模中。擋料銷則多用于復(fù)合模和單工序模中。選取擋料銷做定距定位零件。在模具閉合后不許擋料銷的頂端高出材料因選取固定擋料銷。(3)卸料裝置和推件裝置的選擇 卸料裝置的選擇 為了沖壓后卡在凸模上、凸凹模上的制件或廢料卸掉,將機械設(shè)備制件從凹模中推出來(凹模在上模),或頂出來(凹模在下模),以保證下次沖壓正常進(jìn)行,設(shè)計模具時,必須正確選擇卸料方式和設(shè)計卸料裝置。 在選用壓料、卸料裝置的形式時,應(yīng)考慮操作方式,即板料送進(jìn)和定位是手動操作還是自動化操作,出料方式是上出料,還是下出料。 壓料、卸料裝置根據(jù)沖壓件平整度要求或料的厚薄來決定。一般情況對于沖裁較硬、較厚且精度要求不高的工件,可選擇剛性卸料方式,對于沖裁料厚在1.5mm 以下,且要求沖裁件比較平整的制件,可選擇彈性卸料方式,對于彎曲、拉深等成形零件的卸料方式選擇及卸料裝置的設(shè)計,應(yīng)考慮既不損壞成形部位,又能滿足機械卸料要求的機械卸料裝置。卸料裝置設(shè)計的正確與否,直接影響工件的質(zhì)量、生產(chǎn)效率和操作安全程度。 其卸料力的大小決定與所選用的彈性元件。結(jié)合本次工序的要求選取彈性卸料板。 推件裝置的選擇推件裝置主要有剛性推件裝置和彈性推件裝置兩種,一般剛性用的較多,它由打桿、推板、連接桿和推件塊組成。其工作原理是在沖壓結(jié)束后上?;爻虝r,利用壓力機滑塊上的打料桿,撞擊上模內(nèi)的打桿與推件板,將凹模內(nèi)的工件推出,其推件力大。(4)凸凹模的設(shè)計圖3 落料拉伸凸凹模Fig3 Blanking strench intensive 圖4 拉伸凸模Fig4 Strenching the punch圖5 落料凹模Fig5 Blanking die(5)模架尺寸上模座:L/mmB/mmH/mm=24018045 GB2855.5-81 HT200下模座:L/mmB/mmH/mm=24018045 GB2855.6-81 HT200導(dǎo)柱:d/mmL/mm=32160 A32h5160 GB2861.1-81導(dǎo)套:d/mmL/mmD/mm=326545 A25h56545 GB2861.7-81模具的閉合高度:200mm凸模固定板的厚度:16mm凹模固定板的厚度:35mm卸料板的厚度:14mm壓邊圈的厚度:10mm如圖所示圖6 落料拉深復(fù)合模具總裝配圖Fig6 Drawing compound die for blanking General Assembly drawing4 沖孔翻邊復(fù)合模工序設(shè)計計算4.1 翻邊件的工藝分析60mm處由內(nèi)孔翻邊成形,翻邊前應(yīng)預(yù)沖孔;100mm是圓筒形拉深件,可一次拉深成形。工序安排為落料、拉深、預(yù)沖孔、翻邊等。翻邊前為100mm、高25mm的無凸緣圓筒形件,如圖14.2 工藝計算4.2.1 計算預(yù)沖孔D = 68mm,H = 10mm,h = H-r-t = 10-8-1 = 1mm 由相關(guān)資料查得計算翻邊前預(yù)沖孔直徑d0的公式d0 = D-2(H-0.43r-0.72t)=68-2(10-0.438.5-0.72)=57.75mm (15)4.2.2 計算翻邊系數(shù)由表13計算翻邊系數(shù)為m=d0/D=0.85 (16)由d/t = 57.75查相關(guān)資料得知10鋼極限翻邊系數(shù)為0.75 m,所以該零件能一次翻邊成形,預(yù)沖孔直徑d = 57.75mm。 表13 各種材料的翻邊系數(shù)Table13 Flanging coefficient of various materials材料名稱 翻邊系數(shù) K Kmin 白鐵皮 0.70 0.65 軟剛 t = 0.252mm 0.72 0.68 軟剛 t = 36mm 0.78 0.75 黃銅H62 t = 0.56mm 0.68 0.62 鋁 t = 0.55mm 0.70 0.64 硬鋁合金 0.89 0.804.2.3 計算翻邊力、沖裁力P = 1.1(D-d)中查表14得 = 206MPa,得出p = 2549.25N沖裁力F = Lt = Lt (17)式中查表14得 = 430MPa,t = 1mm,L = 149mm 得出F = 64472N而我采用的是彈壓頂件裝置的倒裝式復(fù)合模,F(xiàn) = F+F卸+F推+F頂查相關(guān)資料可以得出F卸、F推、F頂?shù)闹怠W詈蟮贸鰤毫 = 182577N 表14 黑色金屬材料的力學(xué)性能Table14 Mechanical properties of ferrous materials材料名稱 牌號 材料的狀態(tài) 力 學(xué) 性 能 抗剪強度 抗拉強度 屈服點 伸長率 彈性模量 /MPa b/MPa s/MPa 10/% 10-3E/MPa電工用的工業(yè)純鐵 已退火 177 225 - 26 -電工硅鋼普通碳素鋼 Q235 未經(jīng)退火304373 432461 235 1923碳素結(jié)構(gòu)鋼 8 已退火 255353 324441 177 32 186碳素結(jié)構(gòu)鋼 10 已退火 255333 294432 206 29 194碳素結(jié)構(gòu)鋼 15 已退火 265373 333471 225 26 1984.2.4 沖孔翻邊復(fù)合工序壓力機的選擇考慮到壓力機的使用安全,選擇壓力機的噸位時,總工藝力F一般不應(yīng)超過壓力機額定噸位的80%。壓力機選用J23-25開式可傾壓力機公稱壓力為250KN4.2.5 沖孔翻邊模具工作部分尺寸(1)翻邊模的間隙 由表14查得拉深模的單邊間隙為Z/2 = 0.85mm。 表15 平板毛坯翻邊時凸、凹模之間的間隙Table15 The gap between the die with flat blank flange convex 工件形狀 t/mm Z/2/mm0.3 0.250.5 0.450.7 0.600.8 0.701.0 0.851.2 1.001.5 1.30(2)凸、凹模工作部分的尺寸和公差。由于工件要求內(nèi)孔尺寸,則以凸模為設(shè)計基準(zhǔn)。已知 = 0.74,凸模尺寸的計算見相關(guān)資料dp =(d0min+)0-p將模具公差按IT11級選取,則=0.19代入數(shù)據(jù)得dp =68.740-0.19 (18)間隙取在凹模上,則凹模的尺寸按表15計算,即dd =(d0min+Z)+d0,則得出dd=70.44+0.190 (19)表16 圓形拉深模凸、凹模的制造公查Table16 Round convex drawing die and die manufacturing tolerances材料厚度 工件直徑的基本尺寸 1050 50200 200500 d p d p d p d p0.25 0.015 0.010 0.02 0.010 0.03 0.015 0.03 0.0150.35 0.020 0.010 0.03 0.020 0.04 0.020 0.04 0.0250.5 0.030 0.015 0.04 0.030 0.05 0.030 0.05 0.0350.80 0.040 0.025 0.06 0.035 0.06 0.040 0.06 0.0401.0 0.045 0.030 0.07 0.040 0.08 0.050 0.08 0.0604.2.6 預(yù)沖孔模具工作部分尺寸查表10的間隙值Zmin =0.13mm,Zmax =0.16mm。 查表11的磨損系數(shù)x=0.5,=0.74,取合理最小間隙為0.13mm 查表12得出dd =(dmin+x+ Zmin)+d0=58.25+0.190 (20) dp =(dmin+x)0-p = 58.120-0.19 (21) 4.2.7 沖孔翻邊模具總體設(shè)計圖7 沖孔翻邊凸凹模Fig7 Punching in flanging intensive圖8 沖孔凸模Fig8 Piercing punch圖9 翻邊凹模Fig9 Flanging die(2)模架尺寸上模座:L/mmB/mmH/mm=17016045 GB2855.5-81 HT200下模座:L/mmB/mmH/mm=17016045 GB2855.6-81 HT200導(dǎo)柱:d/mmL/mm=28160 A28h5160 GB2861.1-81導(dǎo)套:d/mmL/mmD/mm=286042 A28h56042 GB2861.7-81模具的閉合高度:200mm凸模固定板的厚度:20mm凹模固定板的厚度:16mm凹模固定板的厚度:30mm卸料板的厚度:14mm墊板的厚度:10mm如下圖所示:圖10 沖孔翻邊復(fù)合??傃b配圖Fig10 Total Assembly of piercing-flanging compound film5 各凸模與凸凹模校核5.1 落料凸模的校核5.1.1 凸??箟簭姸刃:送鼓U9ぷ鳁l件是其刃口斷面承受的軸向壓力不應(yīng)超過模具材料的許用壓應(yīng)力,即c = F /S c (22)式中:c凸模刃口端面承受的壓應(yīng)力,MPa;F作用在凸模刃口端面上的總壓力,N;S凸模刃口端面面積,mm;c 模具鋼的許用壓應(yīng)力,MPa。圓形凸模如圖,即d d = 4tk(1+nK推)/c (23)式中:Smin凸模端面面積的臨界值,mm;dmin凸模的最小許用直徑,mm;d凸模的設(shè)計直徑,mm;n積聚在凹模型孔內(nèi)的零件數(shù);K推推件力系數(shù)。5.1.2 凸??箟菏Х€(wěn)校核 細(xì)長凸模抗壓失穩(wěn)條件,可用壓桿失穩(wěn)的歐拉公式確定。求壓桿失穩(wěn)臨界載荷F的歐拉公式為Fcr = EJ/(lmax) (24) 式中:Fcr壓桿(凸模)失穩(wěn)時的臨界載荷,N Lmax臨界載荷作用下,壓桿(凸模伸出固定板)的“許用”長度,mm; E彈性模數(shù),MPa,對于模具鋼E = (2.12.2)1010MPa; J凸模最小斷面的慣性矩,mm,圓形凸模,J = d/64; 與支撐情況有關(guān)的長度系數(shù)。 載荷條件:凸模刃口端面承受的總沖壓力F應(yīng)小于臨界載荷Fcr,即FFcr。為此,引入安全系數(shù)K,通常取K = 23,則可令Fcr=KF 如圖所示是無導(dǎo)向裝置的模具結(jié)構(gòu),則lmax=0.5(EJ/(KF) (25) 凸模的長度llmax則符合要求。而凸模長度為54mm60mm,故符合要求5.2 拉深凸凹模的校核5.2.1 凸凹??箟簭姸刃:藥肴缟系墓降贸龇弦?.2.2 凸凹??箟菏Х€(wěn)校核帶入如上的公式得出凸凹模長度l=74mm85mm,故符合要求。5.3 翻邊凸凹模的校核5.3.1 凸凹??箟簭姸刃:藥肴缟系墓降贸龇弦?.3.2 凸凹模抗壓失穩(wěn)校核帶入如上的公式得出凸凹模長度l=84mm85mm故符合要求。5.4 卸料彈簧設(shè)計彈簧預(yù)壓力公式: (26)式中 彈簧預(yù)壓力,N; 湖南農(nóng)業(yè)大學(xué)全日制普通本科生畢業(yè)論文(設(shè)計)中 期 檢 查 表學(xué) 院: 工學(xué)院 學(xué)生姓名周茂賢學(xué) 號200941738312年級專業(yè)及班級2009 級 機制 專業(yè)(2)班指導(dǎo)教師姓名董亮指導(dǎo)教師職稱副教授論文(設(shè)計)題目煙灰缸蓋的沖壓工藝及模具設(shè)計畢業(yè)論文(設(shè)計)工作進(jìn)度已完成的主要內(nèi)容尚需解決的主要問題1.零件的沖壓工藝性分析2.零件的工藝計算3.模具設(shè)計4.各模具的計算1.模具零件圖2.模具總裝配圖指導(dǎo)教師意見 簽名: 年 月 日 檢查小組意見 組長簽名: 年 月 日 注:1.此表可用黑色簽字筆填寫,也可打印,但意見欄必須相應(yīng)責(zé)任人親筆填寫。2.此表可從教務(wù)處網(wǎng)站下載中心下載。沖壓成形與板材沖壓 1 概述通過模具使板材產(chǎn)生塑性變形而獲得成品零件的一次成形工藝方法叫做沖壓。由于沖壓通常在冷態(tài)下進(jìn)行,因此也稱為冷沖壓。只有當(dāng)板材厚度超過8100mm時,才采用熱沖壓。沖壓加工的原材料一般為板材或帶材,故也稱板材沖壓。某些非金屬板材(如膠木板、云母片、石棉、皮革等)亦可采用沖壓成形工藝進(jìn)行加工。沖壓廣泛應(yīng)用于金屬制品各行業(yè)中,尤其在汽車、儀表、軍工、家用電器等工業(yè)中占有極其重要的地位。沖壓成形需研究工藝設(shè)備和模具三類基本問題。 板材沖壓具有下列特點: (1)高的材料利用率。(2)可加工薄壁、形狀復(fù)雜的零件。(3)沖壓件在形狀和尺寸方面的互換性好。(4)能獲得質(zhì)量輕而強度高、剛性好的零件。(5)生產(chǎn)率高,操作簡單,容易實現(xiàn)機械化和自動化。沖壓模具制作成本高,因此適合大批量生產(chǎn)。對于小批量、多品種生產(chǎn),常采用簡易沖模,同時引進(jìn)沖壓加工中心等新型設(shè)備,以滿足市場求新求變的需求。板材沖壓常用的金屬材料有低碳鋼、銅、鋁、鎂合金及高塑性的合金剛等。如前所述,材料形狀有板材和帶材。沖壓生產(chǎn)設(shè)備有剪床和沖床。剪床是用來將板材剪切成具有一定寬度的條料,以供后續(xù)沖壓工序使用,沖床可用于剪切及成形。 2 沖壓成形的特點生產(chǎn)時間中所采用的沖壓成形工藝方法有很多,具有多種形式餓名稱,但塑性變形本質(zhì)是相同的。沖壓成形具有如下幾個非常突出的特點。 (1)垂直于板面方向的單位面積上的壓力,其數(shù)值不大便足以在板面方向上使板材產(chǎn)生塑性變形。由于垂直于板面方向上的單位面積上壓力的素質(zhì)遠(yuǎn)小于板面方向上的內(nèi)應(yīng)力,所以大多數(shù)的沖壓變形都可以近似地當(dāng)作平面應(yīng)力狀態(tài)來處理,使其變形力學(xué)的分析和工藝參數(shù)的計算大呢感工作都得到很大的簡化。 (2)由于沖壓成形用的板材毛胚的相對厚度很小,在壓應(yīng)力作用下的抗失穩(wěn)能力也很差,所以在沒有抗失穩(wěn)裝置(如壓邊圈等)的條件下,很難在自由狀態(tài)下順利地完成沖壓成形過程。因此,以拉應(yīng)力作用為主的伸長類沖壓成形過程多于以壓應(yīng)力作用為主的壓縮類成形過程。 (3)沖壓成形時,板材毛胚內(nèi)應(yīng)力的數(shù)值等于或小于材料的屈服應(yīng)力。在這一點上,沖壓成形與體積成形的差別很大。因此,在沖壓成形時變形區(qū)應(yīng)力狀態(tài)中的靜水壓力成分對成形極限與變形抗力的影響,已失去其在體積成形時的重要程度,有些情況下,甚至可以完全不予考慮,即使有必要考慮時,其處理方法也不相同。 (4)在沖壓成形時,模具對板材毛胚作用力所形成的約束作用較輕,不像體積成形(如模鍛)是靠與制件形狀完全相同的型腔對毛胚進(jìn)行全面接觸而實現(xiàn)的強制成形。在沖壓成形中,大多數(shù)情況下,板材毛胚都有某種程度的自由度,常常是只有一個表面與模具接觸,甚至有時存在板材兩側(cè)表面都有于模具接觸的變形部分。在這種情況下,這部分毛胚的變形是靠模具對其相鄰部分施加的外力實現(xiàn)其控制作用的。例如,球面和錐面零件成形時的懸空部分和管胚端部的卷邊成形都屬這種情況。 由于沖壓成形具有上述一些在變形與力學(xué)方面的特點,致使沖壓技術(shù)也形成了一些與體積成形不同的特點。由于不需要在板材毛的表面施加很大的單位壓力即可使其成形,所以在沖壓技術(shù)中關(guān)于模具強度與剛度的研究并不十分重要,相反卻發(fā)展了學(xué)多簡易模具技術(shù)。由于相同原因,也促使靠氣體或液體壓力成形的工藝方法得以發(fā)展。因沖壓成形時的平面應(yīng)力狀態(tài)或更為單純的應(yīng)變狀態(tài)(與體積成形相比),當(dāng)前對沖壓成形匯中毛胚的變形與 力能參數(shù)方面的研究較為深入,有條件運用合理的科學(xué)方法進(jìn)行沖壓加工。借助于電子計算機與先進(jìn)的測試手段,在對板材性能與沖壓變形參數(shù)進(jìn)行實時測量與分析基礎(chǔ)上,實現(xiàn)沖壓過程智能化控制的研究工作也在開展。人們在對沖壓成形過程有離開較為深入的了解后,已經(jīng)認(rèn)識到?jīng)_壓成型與原材料有十分密切的關(guān)系。所以,對板材沖壓性能即成形性與形狀穩(wěn)定性的研究,目前已成為沖壓技術(shù)的一個重要內(nèi)容。對板材沖壓性能的研究工作不僅是沖壓技術(shù)發(fā)展的需要,而且也促進(jìn)了鋼鐵工業(yè)生產(chǎn)技術(shù)的發(fā)展,為其提高板材的質(zhì)量提供了一個可靠的基礎(chǔ)與依據(jù)。 3沖壓變形的分類 沖壓變形工藝可完成多種工序,其基本工序可分為分離工序和變形工序兩大類。分離工序是使胚料的一部分與另一部分相互分離的工藝方法,主要有落料、沖孔、切邊、剖切、修整等。其中又以沖孔、落料應(yīng)用最廣。變形工序是使胚料的一部分相對于另一部分產(chǎn)生位移而不破裂的工藝方法,主要有拉深、彎曲、局部成形、脹形、翻邊、縮徑、校形、旋壓等。從本質(zhì)上看,沖壓成形就是毛胚的變形區(qū)在外力的作用下產(chǎn)生相應(yīng)的塑性變形,所以變形區(qū)內(nèi)的應(yīng)力狀態(tài)和變形特點景象的沖壓成形分類,可以把成形性質(zhì)相同的成形方法概括成同一個類型并進(jìn)行體系化的研究。絕大多數(shù)沖壓成形時毛胚變形區(qū)均處于平面應(yīng)力狀態(tài)。通常認(rèn)為在板材表面上不受外力的作用,即使有外力作用,其數(shù)值也是較小的,所以可以認(rèn)為垂直于板面方向上的應(yīng)力為零,使板材毛胚產(chǎn)生塑性變形的是作用于板面方向上相互的兩個主應(yīng)力。由于板厚較小,通常都近似地認(rèn)為這兩個主應(yīng)力在厚度方向上是均勻分布的?;谶@樣的分析,可以把各種形式?jīng)_壓成型中的毛陪變形區(qū)的受力狀態(tài)與變形特點,在平面應(yīng)力的應(yīng)力坐標(biāo)系中與相應(yīng)的兩向應(yīng)變坐標(biāo)系中以應(yīng)力與應(yīng)變坐標(biāo)決定的位置來表示。4.沖壓用原材料 沖壓加工用原材料有很多種,它們的性能也有很大的差別,所以必須根據(jù)原材料的性能與特點,采用不同的沖壓成形方法、工藝參數(shù)和模具結(jié)構(gòu),才能達(dá)到?jīng)_壓加工的目的。由于人們對沖壓成形過程板材毛胚的變形行為有了較為深入的認(rèn)識,已經(jīng)相當(dāng)清楚的建立了由原材料的化學(xué)成分、組織等因素所決定的材料性能與沖壓成形之間的關(guān)系,這就使原材料生產(chǎn)部門不但按照沖壓件的工作條件與使用要求進(jìn)行原材料的設(shè)計工作,而且也根據(jù)沖壓件加工過程對板材性能的要求進(jìn)行新型材料的開發(fā)工作,這是沖壓技術(shù)在原材料研究方面的一個重要方向。對沖壓用原材料沖壓性能方面的研究工作有(1)原材料沖壓性能的含義。(2)判斷原材料沖壓性能的科學(xué)方法,確定可以確切反映材料沖壓性能的參數(shù),建立沖壓性能的參數(shù)與實際沖壓成形間的關(guān)系,以及沖壓性能參數(shù)的測試方法等。 (3)建立原材料的化學(xué)成分、組織和制造過程與沖壓性能之間的關(guān)系。沖壓用原材料主要是各種金屬與非金屬板材。金屬板材包括各種黑色技術(shù)和有色金屬板材。雖然在沖壓生產(chǎn)中所用金屬板材的種類很多,但最多的原材料蛀牙是鋼板、不銹鋼板、鋁合金板及各種復(fù)合金屬板。5板材沖壓性能及其鑒定方法 板材是指對沖壓加工的適應(yīng)能力。對板材沖壓性能的研究具有飛行重要的意義。為了能夠運用最科學(xué)與最經(jīng)濟合理的沖壓工藝過程與工藝參數(shù)制造出沖壓零件,必須對作為加工對象的板材的性能具有十分清楚的了解,這樣才有可能充分地利用板材在加工方面的潛在能力。另一方面,為了能夠依據(jù)沖壓件的形狀與尺寸特點及其所需的成形工藝等基本因素,正確、合理地選用板材,也必須對板材的沖壓性能有一個科學(xué)的認(rèn)識與正確的判斷。評定板材沖壓性能的方法有直接試驗法與間接試驗法。 實物沖壓試驗是最直接的板材沖壓性能的評定方法。利用實際生產(chǎn)設(shè)備與模具,在與生產(chǎn)完全相同的條件下進(jìn)行實際沖壓零件的性能評定,當(dāng)然能夠的最可靠的結(jié)果。但是,這種評定方法不具有普遍意義,不能作為行業(yè)之間的通用標(biāo)準(zhǔn)進(jìn)行信息的交流。 模擬試驗是把生產(chǎn)中實際存在的沖壓成形方法進(jìn)行歸納與簡單化處理,消除許多過于復(fù)雜的因素,利用軸對稱的簡化了的成形方法,在保證試驗中板材的變形性質(zhì)與應(yīng)力狀態(tài)都與實際沖壓成形相同的條件下進(jìn)行的沖壓性能的評定工作。為了保證模擬試驗結(jié)果的可靠性與通用性,規(guī)定了私分具體的關(guān)于試驗用工具的幾何形狀與尺寸、毛胚的尺寸、試驗條件(沖壓速度、潤滑方法、壓邊力等)。 間接試驗法也叫做基礎(chǔ)試驗法。間接試驗法的特點是:在對板材在塑性變形過程中所表現(xiàn)出的基本性質(zhì)與規(guī)律進(jìn)行分析與研究的基礎(chǔ)上,進(jìn)一步把它和具體的沖壓成形中板材的塑性變形參數(shù)聯(lián)系起來,建立間接試驗結(jié)果(間接試驗值)與具體的沖壓成形性能(工藝參數(shù))之間的相關(guān)性。由于間接試驗時所用試件的形狀與尺寸以及加載的方式等都不同于具體的沖壓成形過程,所以它的變形性質(zhì)和應(yīng)力狀態(tài)也不同于沖壓變形。因此間接試驗所得的結(jié)果(試驗值)并不是沖壓成形的工藝參數(shù),而是可以用來表示板材沖壓性能的基礎(chǔ)性參數(shù)。Characteristics and Sheet Metal Forming1 The article overview Stamping is a kind of plastic forming process in which a part is produced by means of the plastic forming the material under the action of a die. Stamping is usually carried out under cold state, so it is also called stamping. Heat stamping is used only when the blank thickness is greater than 8100mm. The blank material for stamping is usually in the form of sheet or strip, and therefore it is also called sheet metal forming. Some non-metal sheets (such as plywood, mica sheet, asbestos, leather)can also be formed by stamping. Stamping is widely used in various fields of the metalworking industry, and it plays a crucial role in the industries for manufacturing automobiles, instruments, military parts and household electrical appliances, etc. The process, equipment and die are the three foundational problems that needed to be studied in stamping. The characteristics of the sheet metal forming are as follows: (1) High material utilization (2) Capacity to produce thin-walled parts of complex shape. (3) Good interchangeability between stamping parts due to precision in shapeand dimension. (4) Parts with lightweight, high-strength and fine rigidity can be obtained. (5) High productivity, easy to operate and to realize mechanization and automatization. The manufacture of the stamping die is costly, and therefore it only fits to mass production. For the manufacture of products in small batch and rich variety, the simple stamping die and the new equipment such as a stamping machining center, are usually adopted to meet the market demands. The materials for sheet metal stamping include mild steel, copper, aluminum, magnesium alloy and high-plasticity alloy-steel, etc.Stamping equipment includes plate shear punching press. The former shears plate into strips with a definite width, which would be pressed later. The later can be used both in shearing and forming. 2Characteristics of stamping forming There are various processes of stamping forming with different working patterns and names. But these processes are similar to each other in plastic deformation. There are following conspicuous characteristics in stamping: (1)The force per unit area perpendicular to the blank surface is not large but is enough to cause the material plastic deformation. It is much less than the inner stresses on the plate plane directions. In most cases stamping forming can be treated approximately as that of the plane stress state to simplify vastly the theoretical analysis and the calculation of the process parameters. (2)Due to the small relative thickness, the anti-instability capability of the blank is weak under compressive stress. As a result, the stamping process is difficult to proceed successfully without using the anti-instability device (such as blank holder). Therefore the varieties of the stamping processes dominated by tensile stress are more than dominated by compressive stress. (3)During stamping forming, the inner stress of the blank is equal to or sometimes less than the yield stress of the material. In this point, the stamping is different from the bulk forming. During stamping forming, the influence of the hydrostatic pressure of the stress state in the deformation zone to the forming limit and the deformation resistance is not so important as to the bulk forming. In some circumstances, such influence may be neglected. Even in the case when this influence should be considered, the treating method is also different from that of bulk forming. (4)In stamping forming, the restrain action of the die to the blank is not severs as in the case of the bulk forming (such as die forging). In bulk forming, the constraint forming is proceeded by the die with exactly the same shape of the part. Whereas in stamping, in most cases, the blank has a certain degree of freedom, only one surface of the blank contacts with the die. In some extra cases, such as the forming of the blank on the deforming zone contact with the die. The deformation in these regions are caused and controlled by the die applying an external force to its adjacent area. Due to the characteristics of stamping deformation and mechanics mentioned above, the stamping technique is different form the bulk metal forming: The importance or the strength and rigidity of the die in stamping forming is less than that in bulk forming because the blank can be formed without applying large pressure per unit area on its surface. Instead, the techniques of the simple die and the pneumatic and hydraulic forming are developed. Due to the plane stress or simple strain state in comparison with bulk forming, more research on deformation or force and power parameters has been done. Stamping forming can be performed by more reasonable scientific methods. Based on the real time measurement and analysis on the sheet metal properties and stamping parameters, by means of computer and some modern testing apparatus, research on the intellectualized control of stamping process is also in proceeding. It is shown that there is a close relationship between stamping forming and raw material. The research on the properties of the stamping forming, that is, forming ability and shape stability, has become a key point in stamping technology development, but also enhances the manufacturing technique of iron and steel industry, and provides a reliable foundation for increasing sheet metal quality. 3Categories of stamping forming Many deformation processes can be done by stamping, the basic processes of the stamping can be divided into two kinds: cutting and forming.Cutting is a shearing process that one part of the blank is cut from the other. It mainly includes blanking, punching, trimming, parting and shaving, where punching and blanking are the most widely used. Forming is a process that one part of the blank has some displacement from the other. It mainly includes deep drawing, bending, local forming, bulging, flanging, necking, sizing and spinning. In substance, stamping forming is such that the plastic deformation occurs in the deformation zone of the stamping blank caused by the external force. The stress state and deformation characteristic of the deformation zone are the basic factors to decide the properties of the stamping forming. Based on the stress state and deformation characteristics of the deformation zone, the forming methods can be divided into several categories with the same forming properties and be studied systematically.The deformation zone in almost all types of stamping forming is in the plane stress state. Usually there is no force or only small force applied on the blank surface. When is assumed that the stress perpendicular to the blank surface equals to zero, two principal stresses perpendicular to each other and act on the blank surface produce the plastic deformation of the material. Due to the small thickness of the blank, it is assumed approximately the two principal stresses distribute uniformly along the thickness direction. Based on this analysis, the stress state and the deformation characteristics of the deformation zone in all kinds of stamping forming can be denoted by the points in the coordinates of the plane principal stresses and the coordinates of the corresponding plane principal strains. 4Raw materials for stamping formingThere are a lot of raw materials used in stamping forming, and the properties of these materials may have large difference. The stamping forming can be succeeded only by determining the stamping method, the forming parameters and the die structures according to the properties and characteristics of the raw materials. The deformation of the blank during stamping forming has been investigated quite thoroughly. The relationships between the material properties decided by the chemistry component and structure of the material and the stamping forming has been established clearly. Not only the proper material can be selected based on the working condition and usage demand, but also the new material can be developed according to the demands of the blank properties during processing the stamping part. This is an important domain in stamping forming research. The research on the material properties for stamping forming is as follows: (1)Definition of the stamping property of the material. (2)Method to judge the stamping property of the material, find parameters to express the definitely material property of the stamping forming, establish the relationship between the property parameters and the practical stamping forming, and investigate the testing methods of the property parameters. (3)Establish the relationship among the chemical component, structure, manufacturing process and stamping property. The raw materials for stamping forming mainly include various metals and nonmetal plate. Sheet metal includes both ferrous and nonferrous metals. Although a lot of sheet metals are used in stamping forming, the most widely used materials are steel, stainless steel, aluminum alloy and various composite metal plates. 5Stamping forming property of sheet metal and its assessing methodThe stamping forming property of the sheet metal is the adaptation capability of the sheet metal to stamping forming. It has crucial meaning to the investigation of the stamping forming property of the sheet metal. In order to produce stamping forming parts with most scientific, economic and rational stamping forming process and forming parameters, it is necessary to understand clearly the properties of the sheet metal, so as to utilize the potential of the sheet metal fully in the production. On the other hand, to select plate material accurately and rationally in accordance with the characteristics of the shape and dimension of the stamping forming part and its forming technique is also necessary so that a scientific understanding and accurate judgment to the stamping forming properties of the sheet metal may be achieved. There are direct and indirect testing methods to assess the stamping property of the sheet metal.Practicality stamping test is the most direct method to assess stamping forming property of the sheet metal. This test is done exactly in the same condition as actual production by using the practical equipment and dies. Surely, this test result is most reliable. But this kind of assessing method is not comprehensively applicable, and cannot be shared as a commonly used standard between factories. The simulation test is a kind of assessing method that after simplifying and summing up actual stamping forming methods, as well as eliminating many trivial factors, the stamping properties of the sheet metal are assessed, based on simplified axial-symmetric forming method under the same deformation and stress states between the testing plate and the actual forming states. In order to guarantee the reliability and generality of simulation results, a lot of factors are regulated in detail, such as the shape and dimension of tools for test, blank dimension and testing conditions(stamping velocity, lubrication method and blank holding force, etc).Indirect testing method is also called basic testing method its characteristic is to connect analysis and research on fundamental property and principle of the sheet metal during plastic deformation, and with the plastic deformation parameters of the sheet metal in actual stamping forming, and then to establish the relationship between the indirect testing results(indirect testing value) and the actual stamping forming property (forming parameters). Because the shape and dimension of the specimen and the loading pattern of the indirect testing are different from the actual stamping forming, the deformation characteristics and stress states of the indirect test are different from those of the actual one. So, the results obtained form the indirect test are not the stamping forming parameters, but are the fundamental parameters that can be used to represent the stamping forming property of the sheet metal.
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