沖壓模具設(shè)計(jì)畢業(yè)外文翻譯@中英文翻譯@外文文獻(xiàn)翻譯

1、完美WORD格式編輯畢業(yè)設(shè)計(jì)（論文）外文資料翻譯系部：專(zhuān)業(yè)：姓名：學(xué)號(hào)：外文由處： The Pofessional English of DesignManufacture for Dies & Moulds附 件：1.外文資料翻譯譯文：2.外文原文。指導(dǎo)教師評(píng)語(yǔ):簽名:學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯附件1：外文資料翻譯譯文沖壓模具設(shè)計(jì)對(duì)于汽車(chē)行業(yè)與電子行業(yè)，各種各樣的板料零件都是有各種不同的成型工藝所 生產(chǎn)出來(lái)的，這些均可以列入一般種類(lèi)“板料成形”的范疇。板料成形（也稱(chēng)為沖 壓或壓力成形）經(jīng)常在廠區(qū)面積非常大的公司中進(jìn)行。如果自己沒(méi)有去這些大公司訪問(wèn)，沒(méi)有站在巨大的機(jī)器旁，沒(méi)有感受到地

2、面的 震顫，沒(méi)有看巨大型的機(jī)器人的手臂吧零件從一個(gè)機(jī)器移動(dòng)到另一個(gè)機(jī)器，那么廠 區(qū)的范圍與價(jià)值真是難以想象的。當(dāng)然，一盤(pán)錄像帶或一部電視專(zhuān)題片不能反映出 汽車(chē)沖壓流水線的宏大規(guī)模。站在這樣的流水線旁觀看的另一個(gè)因素是觀看大量的 汽車(chē)板類(lèi)零件被進(jìn)行不同類(lèi)型的板料成形加工。落料是簡(jiǎn)單的剪切完成的，然后進(jìn) 行不同類(lèi)型的加工，諸如：彎曲、拉深、拉延、切斷、剪切等，每一種情況均要求 特殊的、專(zhuān)門(mén)的模具。而且還有大量后續(xù)的加工工藝，在每一種情況下，均可以通過(guò)諸如拉深、拉延 與彎曲等工藝不同的成形方法得到所希望的得到的形狀。根據(jù)板料平面的各種各樣 的受應(yīng)力狀態(tài)的小板單元體所可以考慮到的變形情形描述三種成形，

3、原理圖1描述的是一個(gè)簡(jiǎn)單的從圓坯料拉深成一個(gè)圓柱水杯的成形過(guò)程。學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯圖1板料成形一個(gè)簡(jiǎn)單的水杯拉深是從凸緣型坯料考慮的，即通過(guò)模具上沖頭的向下作用使材料被水平拉 深。一個(gè)凸緣板料上的單元體在半徑方向上被限定，而板厚保持幾乎不變。板料成形的原理如圖2所示。拉延通常是用來(lái)描述在板料平面上的兩個(gè)互相垂直的方向被拉長(zhǎng)的板料的單 元體的變形原理的術(shù)語(yǔ)。拉延的一種特殊形式，可以在大多數(shù)成形加工中遇到，即 平面張力拉延。在這種情況下，一個(gè)板料的單元體僅在一個(gè)方向上進(jìn)行拉延，在拉 長(zhǎng)的方向上寬度沒(méi)有發(fā)生變化，但是在厚度上有明確的變化，即變薄。機(jī)M張力弘延學(xué)習(xí)指導(dǎo)參考資料完美WO

4、RD格式編輯圖2板料成形原理彎曲時(shí)當(dāng)板料經(jīng)過(guò)沖模，即沖頭半徑加工成形時(shí)所觀察到的變形原理，因此在 定向的方向上受到改變，這種變形式一個(gè)平面張力拉長(zhǎng)與收縮的典型實(shí)例。在一個(gè)壓力機(jī)沖程中用于在一塊板料上沖出一個(gè)或多個(gè)孔的一個(gè)完整的沖壓模具可以歸類(lèi)即制造商標(biāo)準(zhǔn)化為一個(gè)單工序沖孔模具，如圖3所示。圖3典型的單工序沖孔模具1一下模座2、5導(dǎo)套3凹模4導(dǎo)桿6彈壓卸料板7凸模8托板9凸模護(hù)套10 扇形塊11 固定板12凸模固定板13一墊塊15一階梯螺釘16一上模座17一模柄任何一個(gè)完整的沖壓模具都是有一副（或多副的組合）用于沖制工作的（沖壓）零件組成，包括：所有的支撐件部分與模具的工作部分零件，即構(gòu)成一副沖

5、模。沖壓（術(shù)語(yǔ)）通常將完整壓制工具的凹模（母模）部分定義為模具。導(dǎo)桿，或?qū)е前惭b在下模座上的。上模座則安裝有用于導(dǎo)桿滑動(dòng)的導(dǎo)套，分別裝有導(dǎo)套與導(dǎo)桿的上模座與下模座組合成為木架。模架有許多規(guī)格與結(jié)構(gòu)設(shè)計(jì) 用于商業(yè)銷(xiāo)售。安裝在上模座上的凸模固定裝置固定兩個(gè)凸模（模具中的突出部分），這兩個(gè)學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯圓形凸模則通過(guò)插入在卸料板上的導(dǎo)套進(jìn)行導(dǎo)向。套筒，或凸模護(hù)套，是用來(lái)保護(hù) 沖頭，以免在沖壓過(guò)程中被卡住。在沖穿工件材料后，兩個(gè)沖頭便進(jìn)入到凹模一定 距離。凹模（母模）部分，即凹模，通常是由插入模具體內(nèi)的兩個(gè)模具導(dǎo)套組成的。因?yàn)闆_頭的直徑是被沖孔的直徑所要求的，所以有一定間隙的

6、凹模直徑是大于沖頭 直徑的。由于工件材料坯料或工件在沖制回程時(shí)與沖頭附連在一起，所以把材料從沖頭上剝離是必需的。彈壓卸料板則保持沖頭在沖制工件回程時(shí)縮回，使工件與工件剝 離。一個(gè)沖制的工件通常是留在漏料槽內(nèi)的，漏料槽是由包含整個(gè)零件外輪廓的平板組成。模座是由銷(xiāo)釘支撐板以及其他的滑塊下行程時(shí)定位的擋料塊等定位的。彎曲時(shí)一種最常見(jiàn)的成形工序。當(dāng)我們僅將目光移至汽車(chē)或電器上的部件，或 一個(gè)剪紙機(jī)或檔案柜上時(shí)，就會(huì)發(fā)現(xiàn)許多零件都是由彎曲成形的。彎曲不僅可以用 來(lái)成形法蘭、接頭、波紋，也可以提高零件的強(qiáng)度（通過(guò)增加零件的慣性矩）圖4彎曲術(shù)語(yǔ)-r T彎曲中所用的術(shù)語(yǔ)，如圖4所示，應(yīng)該注意的是，在彎曲中材料

7、的外纖維是處 于拉應(yīng)力狀態(tài)，而材料的內(nèi)纖維則處于壓應(yīng)力狀態(tài)。由于泊松比原因，在外部區(qū)域 的零件（彎曲長(zhǎng)度L）是小于原始寬度，處于內(nèi)部區(qū)域的則比原始寬度大。這種現(xiàn)學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯象可在彎曲一個(gè)矩形的橡膠板擦?xí)r容易觀察到的。最小彎曲半徑對(duì)于不同的金屬是變化的。一般而言，各種退火的金屬板在沒(méi)有斷裂或變?nèi)醯那疤嵯?，可以彎曲成一個(gè)等同金屬板厚的半徑。隨著 R/T比值的減少（彎曲半徑對(duì)厚度的比值變?。?，外纖維的拉應(yīng)力增加，材料最終斷裂（參見(jiàn)圖 5）0圖5泊松效應(yīng)不同材料的最小彎曲半徑參考表 1,他通常是按照不同板厚來(lái)表示的，諸如:2T, 3T, 4T 等。表1在室溫狀態(tài)下各種材料的最小

8、彎曲半徑材料狀態(tài)軟硬鋁合金06T鐵青銅合金，欽合金04T黃銅，低鉛02T鎂5T13T鋼奧氏體不銹鋼0.5T6T低碳鋼，低合金鋼，高強(qiáng)度鉛合金0.5T4T鈦0.7T3T鈦合金2.6T4T學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯注：T材料厚度。彎曲容許范圍，是指彎曲中的中性線（層）的長(zhǎng)度，用來(lái)確定彎曲零件的坯料 長(zhǎng)度。然而，中性線（層）的位置是喲彎曲角度（正如在材料力學(xué)課本中所描述） 來(lái)決定的。彎曲容許范圍（Lb）的近似的公式為：Lb= a （R+kT）式中：Lb彎曲容許范圍，毫米；a彎曲角度（弧度），度；T金屬板厚，毫米；R彎曲內(nèi)層半徑，毫米；k當(dāng)半徑R2T時(shí)為0.50。彎曲方式通常用于沖壓模具。金

9、屬鋼板或帶料，由 V形支撐，參見(jiàn)圖6 （a）在 楔形沖頭的沖壓力作用下進(jìn)入V形模具內(nèi)彈簧加載壓花銷(xiāo)和零件之間的摩擦將會(huì)防 止或減少零件在彎曲期間的邊緣滑移。棱邊彎曲，參見(jiàn)圖6 （b）是懸臂橫梁式加載方式，彎曲沖頭對(duì)相對(duì)支撐的凹模 上的金屬施加彎曲力。彎曲軸線是與彎曲模具的棱邊相平行的。在沖頭接觸工件之 前，為了防止沖頭向下行程的位移，工件則被一個(gè)彈性加載墊片加緊模具體上。圖6彎曲方式彎曲力的大小是可以通過(guò)對(duì)一根矩形橫梁的簡(jiǎn)單彎曲的工藝過(guò)程的確定來(lái)估學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯算。在此情況下的彎曲力是材料強(qiáng)度的函數(shù)，此彎曲力的計(jì)算式為：p=klsT/w式中：P彎曲力，噸（對(duì)于米制使用單位

10、，噸乘以 8.896數(shù)值以得到千牛 頓單位）；K模具開(kāi)啟系數(shù)：16倍材料厚度（16T）時(shí)的開(kāi)啟系數(shù)為1.20, 8倍 材料厚度（8T）時(shí)的開(kāi)啟系數(shù)為1.33;L零件長(zhǎng)度，英寸；S 極限張力弓S度，噸/平方英寸；W V或U形模具的寬度，英寸；T材料厚度，英寸。對(duì)于U形彎曲（槽形彎曲），彎曲力大約是V形彎曲所需要的彎曲壓力的兩倍， 棱邊彎曲則大約是V形彎曲所需要的彎曲壓力的1/2。回彈。所有金屬材料均有一個(gè)固定的彈性模量，隨之而來(lái)的是塑性變形，當(dāng)施 加在材料上的彎曲力消除時(shí)就會(huì)有一些彈性恢復(fù)（見(jiàn)圖7）。在彎曲過(guò)程中這種恢復(fù)稱(chēng)為回彈。一般而言，這樣的回彈在 0.5 -5之間變化，取決于固定的彈性模量

11、、 彎曲方式、模具間隙等。磷青銅的回彈則在 10 75之間。學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯圖7彎曲中的回彈減少或消除在彎曲工序中回彈方法可以根據(jù)下列工藝方法進(jìn)行，如圖8所示,在彎曲模具中產(chǎn)生的零件也可以通過(guò)等同回彈角度彎曲模上挖凹模或彈性緩沖式 彎曲模而被過(guò)度彎曲來(lái)減少或消除回彈。圖8減少或消除回彈的方法從應(yīng)用角度來(lái)說(shuō)，有許多類(lèi)型的壓力機(jī)，諸如：閉式雙點(diǎn)偏心軸單動(dòng)機(jī)械壓力 機(jī)，沖壓成形機(jī)，液壓成形壓力機(jī)，液壓機(jī)，彎板機(jī)，三動(dòng)式壓力機(jī)，沖?；剞D(zhuǎn)壓 力機(jī)，雙點(diǎn)壓力機(jī)，雙邊齒輪驅(qū)動(dòng)壓力機(jī)，雙點(diǎn)單動(dòng)壓力機(jī)，臺(tái)式壓力機(jī)，切邊壓 力機(jī)，閉式單動(dòng)（曲柄）壓力機(jī)，肘桿式壓力機(jī)，單點(diǎn)單動(dòng)壓力機(jī)，開(kāi)式雙柱可

12、傾 壓力機(jī)，開(kāi)式壓力機(jī)，四點(diǎn)式壓力機(jī)，四曲柄壓力機(jī)，飛輪式螺旋壓力機(jī)，摩擦傳 動(dòng)螺旋壓力機(jī)，閉式雙點(diǎn)單動(dòng)雙曲柄壓力機(jī)，搖臂式壓力機(jī)螺旋式壓力機(jī)和上傳動(dòng) 板料沖壓自動(dòng)壓力機(jī)等。雙動(dòng)式壓力機(jī)是用于鉞金零件的拉深加工。此種類(lèi)型的壓力機(jī)有一個(gè)外滑塊 （壓邊圈），并且有一個(gè)切斷的內(nèi)滑塊（沖頭夾緊器）。在加工工作循環(huán)期間，壓邊 圈首先與零件接觸，然后施加壓力使沖頭夾緊器進(jìn)行適當(dāng)零件拉深（見(jiàn)圖9）。學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯圖9典型通用壓力機(jī)三動(dòng)式壓力機(jī)具有和雙動(dòng)式壓力機(jī)相同的內(nèi)、外滑塊。另外，三動(dòng)式壓力機(jī)床 身還有另一個(gè)滑塊，它可向上運(yùn)動(dòng)，從而在一個(gè)沖壓循環(huán)中實(shí)現(xiàn)反向拉伸。三動(dòng)式 壓力機(jī)應(yīng)用不是

13、很廣泛。肘桿式壓力機(jī)是用于壓印加工。這裝置的設(shè)計(jì)是在沖壓行程的末端以很高壓 力。此種壓力機(jī)利用一個(gè)曲柄（曲柄帶動(dòng)違節(jié)運(yùn)動(dòng)，連節(jié)是由兩個(gè)在上死點(diǎn)到下死 點(diǎn)之間進(jìn)行擺動(dòng)的連桿組成，連桿擺動(dòng)時(shí)間很短）.在臨近沖程底部時(shí)慢速移動(dòng)的 滑塊具有功率很大的短距離位移。液壓機(jī)主要是用于成形加工工序中，相比大多散 機(jī)械式壓力機(jī)，它有一個(gè)比較長(zhǎng)的工作周期。液壓機(jī)的優(yōu)點(diǎn)足工作壓力、沖程和滑 塊的速度均是可調(diào)的（見(jiàn)圖10）。學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯圖10典型液壓機(jī)液壓機(jī)屬于壓力限定型的成形機(jī)械，液壓機(jī)的主要用途體現(xiàn)在沿滑塊路徑外力 是必須保持恒定或處于精確攤制株成形技術(shù)領(lǐng)域中?；钊c液壓缸的驅(qū)動(dòng)機(jī)構(gòu)是用

14、線性方式實(shí)現(xiàn)的，并且直接.連接到滑塊。液壓機(jī)框架結(jié)構(gòu)的形式是非常類(lèi)似于機(jī) 械式力機(jī)。液壓驅(qū)動(dòng)裝置易于安裝在機(jī)械框架結(jié)構(gòu)中。因此幾種液壓機(jī)驅(qū)動(dòng)很容易 就被制成復(fù)雜成形與切斷加工（拉深、擠壓、切斷、模鍛等）的單一機(jī)械，并且所 要求的運(yùn)動(dòng)可以容易地定位，彎扳機(jī)除了它的長(zhǎng)床身之外基本是與開(kāi)式壓力機(jī)棚同 的，床身長(zhǎng)度可為620英尺（1.86米）或更長(zhǎng)，它基本上是用在尺寸大的鉞金零 件上的各種類(lèi)型的彎曲加工成形，它也可以使用不同整套的刀具分別進(jìn)行淺沖孔、 切口與成形（見(jiàn)圖11）。這就可以使零件僅通過(guò)把復(fù)雜的零件分成幾個(gè)簡(jiǎn)單的加工 工序?qū)崿F(xiàn)由復(fù)雜設(shè)計(jì)到精確制造的過(guò)程，且沒(méi)有使用昂貴的沖制刀具。此種類(lèi)型加 工

15、工序用于小批量生產(chǎn)或試樣零件。學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯I：傳動(dòng)機(jī)構(gòu)潦塊Kill 保持置 床。一向面的護(hù)板圖11 典型彎板機(jī)電動(dòng)機(jī)離合，制動(dòng)衣動(dòng)KK使用帶有簡(jiǎn)單央具的彎扳機(jī)可以容易地對(duì)鉞金進(jìn)行彎曲。彎板機(jī)使用一個(gè)用在 機(jī)械或液壓饑上的長(zhǎng)模具，適用于小批量生產(chǎn)。模具簡(jiǎn)單，適于各種類(lèi)型的成形加 工，而且，加工工序很容易實(shí)現(xiàn)自動(dòng)化。彎板機(jī)的模具材料可以是硬木（用于低強(qiáng) 度材料與小批量生產(chǎn)），也可以是硬質(zhì)合金材料。大多數(shù)應(yīng)用中，一般是使用碳鋼 或灰鑄鐵材料模具。學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯附件2:外文原文Stamping Die DesignThe wide variety of s

16、heet metal parts for both the automobile and electronic industries is produced by numerous forming processes that fall into the generic category of sheet-metal forming. Sheet-metal forming (also called stamping or pressing )is often carried out in large facilities hundreds of yards long.It is hard t

17、o imagine the scope and cost of these facilities without visiting an automobile factory, standing next to the gigantic machines, feeling the floor vibrate, and watching heavy duty robotic manipulators move the parts from one machine to another. Certainly, a videotape or television special cannot con

18、vey the scale of todays automobile stamping lines. Another factor that one sees standing next to such lines is the number of different sheet-forming operations that automobile panels go through. Blanks are created by simple shearing, but from then on a wide variety of bending, drawing, stretching, c

19、ropping , and trimming takes place, each學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯requiring a special, custom-made die.Despite this wide variety of sub-processes, in each case the desiredshapes are achieved by the modesof deformation known as drawing, stretching, and bending. The three modes can be 川ustratedby considering

20、thedeformation of small sheet elements subjected to various states of stressin the plane of the sheet. Figure 1 considers a simple forming process inwhich a cylindrical cup is produced from a circular blank.Figure 1 Sheet forming a simple cupDrawing is observed in the blank flange as it is being dra

21、wn horizontally through the die by the downward action of the punch. A sheet element in the flange is made to elongate in the radial direction and contract in the circumferential direction, the sheet thickness remaining approximately constant Modes of sheet forming are shown in Figure 2.學(xué)習(xí)指導(dǎo)參考資料完美WO

22、RD格式編輯StretchingFigure2 Modes of sheet formingis the term usually used to describethe deformation in whichan element of sheet material is made to elongate in two perpendiculardirectionsin the sheet plane. A special form of stretching,which isencountered in most forming operations, is plane strain st

23、retching. In this case, a sheet element is madeto stretch in one direction only, with no change in dimension in the direction normal to the direction of elongation but a definite change in thickness, that is, thinning.Bending is the mode of deformation observed when the sheet material is madeto go o

24、ver a die or punch radius, thus suffering a change in orientation. The deformation is an example of plane strain elongation and contractionA complete press tool for cutting a hole or multi-holes in sheet material at one stroke of the press as classified and standardized by a large manufacturer as a

25、single-station piercing die is shown in Figure3.學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯Any complete press tool, consisting of a pair( or a combination of pars ) of mating member for producing pressworked (stmped ) parts, including all supporting and actuating elements of the tool, is a die. Pressworking terminology comm

26、only defines the female part of any complete press tool as a die.The guide pins, or posts, are mounted in the lower shoe. The upper shoe contains bushings which slide on the guide pins. The assembly of the lower and upper shoes with guide pins and bushings is a die set. Die sets in many sizes and de

27、signs are commercially available. The guide pins are shown in Figure 3.Figure3 Typical single-station die for piercing hole1 Lower shoe 2,5 Guide bushings 3 Cavity plate 4Guid pin學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯6Spring-loaded stripper 7Punch 8Support plate 9 Punch bushing10Fan-shaped block 11 Fixed plate 12 Punch

28、-holder plate 13Backingplate 14 Spring 15 Stepping bolts 16Upper shoe 17 ShankA punch holder mounted to the upper shoe holds two round punches (male membersof the die) which are guided by bushings inserted in the stripper. A sleeve, or quill, encloses one punch to prevent its buckling under pressure

29、 from the ram of the press. After penetration of the work material, the two punches enter the die bushings for a slight distance.The female member, or die, consists of two die bushings inserted in the die block. Since this press tool punches holes to the diameters required, the diameters of the die

30、bushings are larger than those of the punches by the amount of clearance.Since the work material stock or workpiece can cling to a punch on the upstroke, it may be necessary to strip the material from the punch. Spring-loaded strippers hold the work material against the die block until the punches a

31、re withdrawn from the punched holes. A workpiece to be pierced is commonly held and located in a nest (Figure 2-3) composed of flat plates shaped to encircle the outside part contours. Stock is positioned in dies by pins, blocks, or other types of stops for locating before the downstroke of the ram.

32、Bending is one of the most common forming operations. We merely have to look at the components in an automobile or an appliance-or at a paper學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯clip or a file cabinet-to appreciate how many parts are shaped by bending. Bending is used not only to form flanges, seams, and corrugations

33、but also to impart stiffness to the part ( by increasing its moment of inertia ).The terminology used in bending is shown in Figure 4. Note that, in bending, the outer fibers of the material are in tension, while the inner fibers are in compression. Because of the Poissons ratio, the width of the pa

34、rt (bend length, L) in the outer region is smaller, and in the inner region is larger than the original width. This phenomenon may easily be observed by bending a rectangular rubber eraser.Minimum bend radii vary for different metals, generally, differentannealed metals can be bent to a radius equal

35、 to the thickness of the metal without cracking or weakening. As R/T decreases (the ratio of the bend radiusto the thickness becomes smaller), the tensile strain at the outer fiberincreases, and the material eventually cracks (Figure 5).Figure 4 Bending terminology學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯Rolling direction

36、Rolling directionElongated inclusions(stringers)No cracks(a) Parallel with bending direction (b) Vertical with bending directionoisson effectThe minimum bend radius for various materials is given in Table 1 andit is usually expressed in terms of the thickness. such as 2 T, 3 T, 4T.Table 1 Minimum be

37、nd radius for various materials at room temperatureMaterialConditionSoftHardAluminum alloys06TBeryllium copper04TBrass,low-leaded02TMagnesium5T13TSteelsAustenitic stanless0.5T6TLow-carbon,lowalloy,HSLA0.5T4TTitanium0.7T3T學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯Titanium alloys2.6T4TNote :Tthickness of materialBend allowan

38、ce as shown in Figure 4 is the length of the neutral axis in the bend and is used to determine the blank length for a bent part. However, the position of the neutral axis depends on the radius and angle of bend (as described in texts on mechanics of materials).An approximate formula for the bend all

39、owance, Lb is given byLb= a (R 十 kT)Where Lbbend allowance, in (mm).abend angle, (radians) (deg).Tsheet thickness, in (mm).Rinside radius of bend, in (mm).k0.33 when R is less than 2T and 0.50 when JR is more than 2T.Bend methods arc commonly used in press tool. Metal sheet or strip, supported by-V

40、bockFigure 6(a),is forced by a wedge-shaped punch into the block. This method, termed V bending, produces a bend having an included angle which may be acute, obtuse, or 900 .Friction between a spring -loadedknurled pin in the vee die and the part will prevent or reduce side creep of the part during

41、its bending.Edge bending Figure 6(b) is cantilever loading of a beam. The bending punch forces the metal against the supporting die. The bend axis is parallel to the edge of the die. The workpiece is clamped to the die block by a學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯spring-loaded pad before the punch contacts the workp

42、iece to prevent itsmovement during downward travel of the punch.Hl)V die(b) Wiping dieBending methodsBending Force can be estimated by assuming the process of simplebending of a rectangular beam. The bending force in that case is a function of the strength of the material. The calculation of bending

43、 force is as follows:p=klsTwWhere P-bending force, tons (for metric usage, multiply number of tons by 8.896 to obtain kilonewtons).Kdie opening factor: 1.20 for a die opening of 16 times metalthickness, 1.33 for an opening of 8 times metal thickness.Llength of part, in.Sultimate tensile strength, to

44、ns per square in.W-width of V or U die, in.Tmetal thickness, in.For U bending (channel bending) pressures will be approximately twice學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯those required for V bending, edge bending requires about one-half those needed for V bending.Springback in that all materials have a finite modulus

45、of elasticity, plastic deformation is followed, when bending pressure on metal is removed, by someelastic recovery (see Figure 7). In bending, this recovery is called springback. Generally speaking, such a springback varies in sheet from 0.5 to 5 , depending upon finite modulus of elasticity, modes

46、of bending, clearance of die and so on, but phosphor bronze mayspring back from 10 to15 0Figure 7 Springback during bendingMethods of reducing or eliminating springback in bending operations can be madeaccording to the following operations, shownin Figure 8, and parts produced in bending die are als

47、o overbent through an angle equal to the springback angle with an undercut or relieved punch.學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯Figure8 Methods of reducing or eliminating springbackFor the applications, there are many types of the presses, such as the single-action straight-slide eccentric mechanical press, punch pr

48、ess, hydro-former press, hydraulic press, press brake, triple-action press, turret press, two-point press, twin-drive press, two point single-action press, watch press, trimming press, closed-type single-action crank press, knuckle-lever press, one-point single-action press, open-back inclinable pre

49、ss, open-side press, four-point press, four-crank press, flywheel-type screw press, friction screw press, straight-side single-action double-crank press, rocker-arm press, screw press and top-drive sheet-metal stamping automatic press and so on.A double-action press is used for large, or deep drawin

50、g operations on sheet metal parts. This type of press has an outer ram ( blank holder ) and a section inner ram ( punch holder ) . During the operating cycle, the blank holder contacts the material first and applies pressure to allow the punch holder to properly draw the part (Figure 9).學(xué)習(xí)指導(dǎo)參考資料完美WO

51、RD格式編輯Figure9 Typical versatile pressA triple-action press has the same inner and outer ram as the double-action press, but a third ram in the press bed moves up allowing a reverse draw to be made in one press cycle. The triple-action press is not widely used.A knuckle press is used for coining oper

52、ation. The design of the drive allows for very high pressures at the bottom of the ram stroke. This type uses a crank, which moves a joint consisting of two levers that oscillate to and from dead center and results in a short, powerful movement of the slide with slow travel near the bottom of the st

53、roke.A hydraulic press is used basically for forming operations and has a slower operating cycle time than most mechanical presses. The advantages of hydraulic presses are that the working pressure stroke, and speed of the學(xué)習(xí)指導(dǎo)參考資料完美WORD格式編輯ram are adjustable (Figure 10).Hydraulic presses belong to the force-constrained type of forming machines . Their main use