外文翻譯新型四分區(qū)錐形壓邊力摩擦輔助拉深的工藝

1、畢業(yè)設計(論文)外文資料翻譯系部： 機械工程系 專 業(yè)： 機械制造及自動化 姓 名： 學 號： 外文出處: journal of materials processing technology，159(2005),418425. 附 件： 1.外文資料翻譯譯文；2.外文原文。 指導教師評語：該英文翻譯經(jīng)過幾次修改后語句較通順，較能正確表達原文的內容。這反映了該生通過本英文翻譯基本掌握了科技文獻的閱讀方法和常用專業(yè)詞匯的翻譯方法，基本達到了外文資料翻譯的目的。 簽名： 2009 年 3 月 18 日附件1：外文資料翻譯譯文新型四分區(qū)錐形壓邊力摩擦輔助拉深的工藝摘要：本文提出了一種摩擦輔助拉深的新

2、技術。金屬壓邊圈設計可分為兩層：一層為不動層，或稱基層，由四個5°錐角的平面組成；另一層為移動層，分為四個錐形部分。在適當?shù)膲哼吜ο?，這四個部分能通過一種專門設計的壓緊工具勻速徑向移動到模腔，這種壓邊裝置的主要功能是利用板料和壓邊圈之間的在有效拉深方向上的摩擦力，就如在maslennikov過程中利用的橡膠圈的功能。使用一個輔助的金屬沖壓器在拉深過程中在液壓缸的幫助下提供一個恒定的拉深力來實現(xiàn)有效的拉深變形。所提出工藝的優(yōu)缺特點主要研究拉深的機構和拉深條件的影響。雖然成功制造拉深比率為3.76的深杯狀體已驗證了當前技術的可行性，然而，提高拉深效率還需要進一步研究。關鍵詞 金屬板料成型

3、 摩擦輔助拉深 拉深 分塊壓邊圈1. 介紹在傳統(tǒng)的拉深法中，第一階段的拉深很難超過單位杯高度與直徑比率為2.2的拉深比率極限。提出的提高變形極限的解決方案一般分為三類：改變需成型金屬板的材料特性；改變應力狀態(tài)；改變摩擦狀態(tài)?；谶@些基本解決方案，已提出了很多特殊工藝來提高拉深比率極限1-10。使用這些工藝，在材料流動應力可控制在材料極限強度以下時來獲得巨大的塑性張力。在這些拉深工藝中，所謂的maslennikov工藝11是一種特殊的方式，其巧妙的利用置于杯形件中的橡膠圈作為壓力介質產(chǎn)生毛坯拉深變形。該過程屬于上述的第三類方案，即改變摩擦的狀態(tài)。不同于傳統(tǒng)方法，該工藝利用毛坯板材和橡膠圈之間的摩

4、擦力實現(xiàn)深拉深。由于該拉深方式是通過徑向的壓力實現(xiàn)的，就能避免凸模圓角部分的破裂。但是，對于薄板，凸緣部分仍然存在圓周破裂。這種破裂曾被認為是由于壓力沿橡膠圈和毛坯12，13 的半徑方向分布不均勻而產(chǎn)生的防滑點。maslennikov工藝的另一個缺陷是，因為誘導摩擦力不足而導致高變形阻力毛坯不能拉深。此外，橡膠的使用壽命短，而拉深又要求有較高的壓力。為了克服這些缺陷， hassan et al 14 。提出了新的建議：用一個分為四部分的壓邊圈取代在maslennikov工藝中使用的橡膠圈。該技術進行深拉深的可行性已被驗證，但是，有一個關鍵點約束著該裝置的應用。那就是由于凸模材料流入壓邊分區(qū)之間

5、的空隙而產(chǎn)生起皺，如圖1(a)所示。這個問題可以通過在這四個分區(qū)15之間的間隙中插入四小楔子得以解決。新的壓邊圈分為八個部分(四小楔子和四個拉深分區(qū))取得了良好的效果。但是不幸的是，在使用薄板材的情況下，拉深部分和四個楔子的邊緣部分由于局部過強的剪切力而出現(xiàn)裂痕，如圖1(b)中所示。在目前的研究論文中最新提出，用一個分為四部分的雙層錐形壓邊圈來消除局部褶皺和嚴重剪切變形區(qū)域這些不足。該論文細致探討了變形機制和拉深條件的影響，并證實了現(xiàn)今深拉深技術的可行性。（a四分塊壓邊圈下的局部起皺、b八分塊壓邊圈下的局部剪切區(qū)）圖1 原摩擦輔助拉深觀察到的缺陷2. 四分區(qū)錐形壓邊圈的構造和拉深機制圖2(a)

6、 所示為上述錐形壓邊圈示意圖。它由一個固定的底座和四個成5°微斜錐形角的位面組成。拉深部分能勻速的在底座的錐形面上沿半徑方向的滑動。四個滑配合的楔片被用來引導這些拉深部分在固定底座上的運動。理解拉深機制和壓邊圈的復合運動至關重要。拉深過程的第一步中，當兩個端面分區(qū)在a方向上呈沿半徑方向位移時，變形便開始了，如圖2(b)所示。另外兩個部分在b方向上反向進行復合運動，即與圖2(b)中所示的拉深方向相反，向下和沿半徑方向向外運動。因此，毛坯板材和模具在a方向上上升，而在b方向上，如圖2(d)所示，毛坯板材和兩個拉深部分并沒有接觸。此時，邊緣有50%并不受制于壓邊圈。另一方面，a方向上的兩個

7、拉深部分不斷上升至模具的開口處，兩者與毛坯板材有輕微的接觸，如圖2(c)所示。a方向上產(chǎn)生的摩擦力迫使毛坯變形并移向模具的開口處，同時，b方向上的兩個拉深部分產(chǎn)生一個反向的摩擦力使毛坯變形。所以，這種技術成功地消除了八個部分組成的壓邊圈帶來的局部強烈剪切變形。然而，b方向上的毛坯邊緣由于受到圓周壓力作用而出現(xiàn)了褶皺。在第二步拉深中，b方向上的壓邊圈做沿半徑方向換位轉移，與此同時，在a方向上的兩個拉深部分以于第一步中相似的方式做復合運動。因此，第一步中b方向上產(chǎn)生的褶皺被同時校正了。重復上述兩個步驟，就能成功制造出深杯形件。圖2 四分區(qū)錐形壓邊圈的組成和運動示意圖3. 實驗準備3.1. 測試設備

8、圖3是試驗設備的主要組成部分的示意圖。毛坯變形需要足夠的壓邊力f1， 而沖壓力f2主要起到提高杯形件尺寸準確性和幫助變形拉深的作用。合適的壓邊力f1由壓力閥17控制，合適的沖力f2由壓力閥16控制。拉深部件沿半徑方向在0-2毫米范圍內的位移運動由測微儀13和四個調整銷11控制。壓緊工具 5 應該在每次拉深操作后旋轉90度來改變強制性半徑方向替代運動的方向和毛坯與壓邊圈之間的壓力。實驗裝置裝配在一臺水壓機上。該水壓機能軸向進行多范圍速度的運動，并能產(chǎn)生最大為100kn的壓力，而一臺單獨的泵所能產(chǎn)生的最大沖壓力也只有10 kn。試驗裝置尺寸和最佳力度見表1。1拉深滑塊,2液壓缸,3,液壓,4擠壓墊

9、,5壓緊工具,6模具,7 毛坯,8錐形邊壓邊圈,9壓邊基座,10沖頭， 11調整銷, 12彈簧, 13測微儀, 14模具, 15工作臺,16壓力閥,17減壓閥。圖3 拉深試驗設備示意圖;表1 工具尺寸和實驗工況模具外徑(mm)120內徑(mm)32剖面半徑(mm)3錐形壓邊圈外徑(mm)116內徑(mm)35側偏量(mm)1徑向速度(mm/s)0.2壓邊力(kn)40-100輔助拉深器直徑(mm)30剖面半徑(mm)2速度(mm/s)0.8沖壓力(kn)1-53.2.實驗材料和實驗條件使用0.5毫米厚度的柔軟的鋁(al-co)制毛坯作為試驗材料。表2中所列數(shù)據(jù)為單軸張力測試中得到的材料的屬性常

10、數(shù)f， n和r。當毛坯的直徑分別為86和110時，拉深比率由2.87變?yōu)?.67。為了研究毛坯變形的情況，在毛坯表面預先標注出2毫米的同心圈，如圖4(a)所示。其中，最小的圓直徑為28毫米，最大的為80毫米。此外，還在毛坯表面標注出a， b， c三個沿半徑的方向。在奇數(shù)/偶數(shù)次拉深時，部件分別在a/b方向上進行替換移動，而部件c和壓邊圈各部分的銜接邊界重合。為了研究在杯側壁的格柵的變形，在直徑為110毫米的毛坯上標示出間隔為5毫米的同心圓和五條間隔為22.5 °圓周角的半徑，如圖4(b)所示。45 °和-45°的半徑方向與指示邊界c重合，而零度方向為b方向，該方向

11、上在偶數(shù)次拉深時受力變形。毛坯板材和壓邊圈之間干燥的摩擦有利于增加產(chǎn)生的摩擦力。不過，特氟隆影片(ptfe)被用作在毛坯板材和模具之間的固體潤滑劑，來減小摩擦力。 （a） 拉深率2.87，板徑86mm （b） 拉深率3.67，板徑110 mm圖4 板材上標明的圓形柵格和方向 表2 柔軟的鋁制毛坯的機械特性和尺寸f值(mpa)220n值0.27r值0.76厚度(mm)0.5毛坯直徑(mm)86、1104. 結果討論（略）5. 目前的深沖壓技術的可行性圖5、圖6為已拉深杯形件；前者在50次拉深之后側壁c方向（±45°方向）出現(xiàn)弧坑狀缺陷。在制作過程中，c方向上板材的運動比b、a

12、方向上的程度大，因此板材撞擊到模具開口處的帶扣而在沖壓和模具相分離時產(chǎn)生凹陷。然而，這個凹陷是可以被消除的：每隔一次拉深，把毛坯板材就銜接邊緣方向旋轉45°。這個簡單的技術幫助制造出了64毫米高3.67比率的杯形件，如圖14所示。這樣的杯形件需要經(jīng)過100次的拉深，但是也證實了目前的依靠摩擦力的深拉深技術具有可行性。圖5 c向上的弧坑狀缺陷圖6 成功的杯形件例子(=3.67，杯形件高度=64 mm，n=100)6. 結論在借助摩擦力實現(xiàn)深拉深的技術方面，提出了一種新的方法來實現(xiàn)深杯形件的制造，即借助一個由四個錐形部分組成的壓邊圈。這種新設備克服了傳統(tǒng)的四部分或八部分構成的壓邊圈會產(chǎn)生

13、局部褶皺和劇烈的剪切變形等問題。拉深機制和拉深條件的影響也被細致的觀察了。當壓邊力大于80kn，輔助沖壓力大于4kn時，拉深效率有顯著提高。這種技術能成功制造出比率為3.67的深杯形件，這也證實了目前改良技術的可行性。由于每次拉深壓邊圈沿半徑方向的位移被限制在1毫米，制造過程需要100次拉深。但是，在該工藝中，自始至終只使用了一套剛性工具，加工時間也可由增加每分鐘的沖壓次數(shù)來縮短。因此，該工藝便于小批量深杯形件的生產(chǎn)。附件2：外文原文（復印件）a novel process on friction aided deep drawing usingtapered blank holder div

14、ided into four segmentsabstracta new technique on friction aided deep drawing has been proposed. a metal blank holder was designed to be of two layers: stationary layer or base with four planes of 5 taper angle and moving layer divided into four tapered segments. under appropriate blank holding forc

15、e, these four segments can move radically to the die opening with a constant speed by using a specially designed compression tool. the main function of this developed blank holding device is adopting the frictional force between the blank and the blank holder to work in the useful drawing direction

16、likewise the function of the rubber ring used in maslennikovs process. drawing deformation is efficiently performed by using an assistant metal punch, which is supplemented with a hydraulic cylinder to provide a constant punch force during the drawing process. the drawing mechanism and the effects o

17、f drawing conditions are mainly investigated to characterize the merits and defects of the proposed process. since successful deep cups of drawing ratio 3.76 have been produced the possibility of the present technique is already cornered, however, further investigations are needed to enhance the dra

18、wing efficiency.1. introductionthe limiting drawing ratio achieved by the rst stage drawing in conventional deep drawing method seldom exceeds 2.2 which corresponds to the cup height to diameter ratio of about unity. solutions proposed for increasing the forming limit generally fall into three categ

19、ories; changein the material properties of the sheet metal being formed, change in the stress state and change in the frictional state. based on these fundamental solutions, many special processes have been proposed to increase the limiting drawing ratio 110. in these processes, large plastic strain

20、s could be achieved when the low stress of material can be controlled in the range below the ultimate strength of material. among these deep drawing processes the so-called maslennikov process 11 is a unique method in which a rubber ring put in a container is skillfully utilized as a pressuremedium

21、to generate drawing deformation of a blank. this process belongs to the third category, i.e. change in the frictional state; the frictional force between the blank sheet and the rubber ring is used to achieve deep drawing unlike the conventional method. because the drawing of the blankis carried out

22、 by the radial compressive force, the fracture at the punch prole portion can be avoided. however, for thin sheets, circumferential fracture has been observed at the ange portion. the reason behind such fracture was attributed to the existence of a non-slip point at the angedue to the difference in

23、the radial velocity distributions of the rubber ring and blank 12,13. as another defect of the maslennikov process, blanks of high deformation resistance cannot be drawn because the induced frictional force is not sufficient. moreover, the lifetime of the rubber is short and very high pressure is re

24、quired for drawing.to overcome these decencies, hassan et al. 14 have proposed to use a blank holder divided into four segments instead of the rubber ring used in the maslennikov process.the possibility of the deep drawing with such technique has been conrmed, however, there was one criticism limiti

25、ng the application of such proposed device. that is occurrence of wrinkles due to owing of ange material into the gaps between the blank holder segments as shown in fig. 1(a).such a problem was overcome by tting four small wedges in these gaps between the four drawing segments 15. using this new bla

26、nk holder divided into eight segments (four small wedges and four drawing segments) give good results. but unfortunately in case of using thin sheets a crack as shownfig. 1. defects observed in the previous friction aided deep drawing methods.in fig. 1(b) was observed due to the localized intensive

27、shear deformation at the boundaries between the drawing segments and the four small wedges.in the present paper, a two-layered tapered blank holder divided into four segments was newly proposed to eliminate the defects of localized wrinkling and intensive shear deformation regions. the deformation m

28、echanism and the effects of drawing conditions are mainly investigated in detail and the possibility of the present deep drawing method is conrmed.fig. 2. schematic of construction and movement of tapered blank holder divided into four segments.drawing segments that have similar planes of slightly t

29、aper angle of 5, the drawing segments can slide radially under a constant speed over the tapered surfaces of the stationary base. four keys with sliding t are used for guiding the motion of these segments on the stationary base.it is important to understand the drawing mechanism and the compound mot

30、ion of the blank holder segments. in the rst drawing step, deformation starts when two facing segments receive radial displacement in the a-direction as shown in fig. 2(b). the other two segments in the b-direction move in the reverse direction with compound motion; downward and radially outward opp

31、osite to the drawing direction as shown in fig. 2(d). due to this action, the blank sheet and the die in the a-direction are lifted up as shown in fig. 2(c),while in the b-direction, there is no contact between the blank sheet and the two segments as shown in fig. 2(d). at that time about 50% of the

32、 ange is not subjected to blank holding force. on the other hand, the two segments in the a-direction are climbing up and advancing to the die opening, so that they tightly contact with the blank sheet as shown in fig. 2(c). as a result, the frictional force generated in the a-direction yields the b

33、lank to deform and move toward the die opening. while, the two segments in the b-direction do not generate outward frictional force opposing the blank deformation. therefore, this technique successfully eliminates the localized intensive shear deformation observed when using the blank holder divided

34、 into eight segments 15.how-ever, small wrinkles arise in the b-direction of the ange portions due to the circumferential compressive force.in the second drawing step, the blank holder segments in the b-direction receive radial displacement, while the other two segments in the a-direction move in a

35、compound motion in a similar manner to the rst drawing step. as a resultwrinkles generated in the b-direction in the rst drawing step will be simultaneously corrected. therefore, complete and successful deep cups can be obtained by repeating these two steps to a certain number of drawings.3. experim

36、ental setup3.1. test equipmentfig. 3 is a schematic diagram which shows the essential elements of the test equipment. a sufficient blank holding force f1 is mainly required for the deformation of blank, while the punch force f2 is mainly added to enhance the dimensional accuracy of the drawn cup and

37、 to help partially the drawing deformation. the blank holding force f1 is controlled by the pressure valve 17 to obtain appropriate force, while the punch force f2 is controlled by the valve 16 for the proper use. the radial displacement of the blank holder segments is controlled within the range 02

38、mm using the dial gauge 13 and four adjusting pins 11. the compression tool 5 should be rotated 90 after each drawing operation to change the direction of the imposed radial displacement and the holding pressure over blank and blank holder seg-fig. 3. schematic diagram showing equipment used for dee

39、p drawing test; 1-press ram, 2-hydraulic cylinder, 3-oil pressure, 4-dummy block, 5-compression tool, 6-die, 7-blank, 8-tapered blank holder, 9-blank holder stationary base, 10-punch, 11-adjusting pin, 12-spring, 13-dial gauge, 14-container, 15-die set, 16-control valve, 17-relief valve.table 1tool

40、dimensions and experimental conditionsdieouter diameter (mm)120inner diameter (mm)32prole adius (mm)3tapered blank holderouter diameter (mm)116inner diameter (mm)35radial displacement (mm)1radial velocity (mm/s)0.2blank holding force (kn)40100assistant punchdiameter (mm)30prole radius (mm)2velocity

41、(mm/s)0.8punch force (kn)15ments. the test rig is assembled on a hydraulic press, which has multi-ranges of axial speeds and maximum compression force of 1000 n, while the maximum punch force given by a separate pump is 10 kn. the test rig dimensions and the optimum force conditions are listed in ta

42、ble 1.3.2. test material and experimental conditionssoft aluminum (alo) blanks of 0.5mm thickness was used as a testing material. the material constants f, n and r.table 2mechanical properties and dimensions of soft aluminum blanks (alo)f-value (mpa)220n-value0.27r-value0.76thickness (mm)0.5blank di

43、ameter (mm)86, 110determined from uneasily tension test are listed in table 2.the blank diameter was changed as 86 and 110 which give drawing ratios of 2.87 and 3.67.in order to investigate the deformation behavior of blank,concentric circles of 2mm apart were initially marked on the blank surface a

44、s shown in fig. 4(a). the smallest circle diameter is 28mm and the biggest one is 80mm. in addition to that, three radial directions a, b and c are marked on the blank surface. directions a and b receive imposed radial displacement during the odd and the even numbers of drawing respectively, while t

45、he direction c corresponds to the boundary between blank holder segments.to study the distortion of grids at cup side wall, concentric circles of 5mm apart and ve radial lines of 22.5 angular distances were marked on the blank of 110mm in diameter as shown in fig. 4(b). the radial directions 45 and

46、45 correspond to the boundary directions c, while zero direction is located to be in consistent with b-direction which receives imposed deformation at the even number of drawing.dry friction condition between blank sheet and blank holder segments is necessary to increase the induced frictional force

47、. however, te on lm (ptfe) is used as a solid lubri-cant between die and blank to reduce the frictional force.fig. 4. circular grids and prescribed directions marked on blanks.4. results and discussion5. possibility of the present deep drawing processexamples of drawn cups are shown in figs. 5 and 6

48、;the former shows defects like a crater observed at the cup sidewall at the direction c (±45 directions) after 50 times drawing operations. at this stage of drawing, the radial in ow of material in the c-directions is greater than those in the directions b and a. therefore, the material coming to the die opening buckles and makes craters in the clearance between punch and die. however, the craters could be eliminated by rotating the blank sheet through 45 with respect to the boundary directions after eve