外文翻译新型四分区锥形压边力摩擦辅助拉深的工艺

1、毕业设计(论文)外文资料翻译系部： 机械工程系 专 业： 机械制造及自动化 姓 名： 学 号： 外文出处: journal of materials processing technology，159(2005),418425. 附 件： 1.外文资料翻译译文；2.外文原文。 指导教师评语：该英文翻译经过几次修改后语句较通顺，较能正确表达原文的内容。这反映了该生通过本英文翻译基本掌握了科技文献的阅读方法和常用专业词汇的翻译方法，基本达到了外文资料翻译的目的。 签名： 2009 年 3 月 18 日附件1：外文资料翻译译文新型四分区锥形压边力摩擦辅助拉深的工艺摘要：本文提出了一种摩擦辅助拉深的新

2、技术。金属压边圈设计可分为两层：一层为不动层，或称基层，由四个5°锥角的平面组成；另一层为移动层，分为四个锥形部分。在适当的压边力下，这四个部分能通过一种专门设计的压紧工具匀速径向移动到模腔，这种压边装置的主要功能是利用板料和压边圈之间的在有效拉深方向上的摩擦力，就如在maslennikov过程中利用的橡胶圈的功能。使用一个辅助的金属冲压器在拉深过程中在液压缸的帮助下提供一个恒定的拉深力来实现有效的拉深变形。所提出工艺的优缺特点主要研究拉深的机构和拉深条件的影响。虽然成功制造拉深比率为3.76的深杯状体已验证了当前技术的可行性，然而，提高拉深效率还需要进一步研究。关键词 金属板料成型

3、 摩擦辅助拉深 拉深 分块压边圈1. 介绍在传统的拉深法中，第一阶段的拉深很难超过单位杯高度与直径比率为2.2的拉深比率极限。提出的提高变形极限的解决方案一般分为三类：改变需成型金属板的材料特性；改变应力状态；改变摩擦状态。基于这些基本解决方案，已提出了很多特殊工艺来提高拉深比率极限1-10。使用这些工艺，在材料流动应力可控制在材料极限强度以下时来获得巨大的塑性张力。在这些拉深工艺中，所谓的maslennikov工艺11是一种特殊的方式，其巧妙的利用置于杯形件中的橡胶圈作为压力介质产生毛坯拉深变形。该过程属于上述的第三类方案，即改变摩擦的状态。不同于传统方法，该工艺利用毛坯板材和橡胶圈之间的摩

4、擦力实现深拉深。由于该拉深方式是通过径向的压力实现的，就能避免凸模圆角部分的破裂。但是，对于薄板，凸缘部分仍然存在圆周破裂。这种破裂曾被认为是由于压力沿橡胶圈和毛坯12，13 的半径方向分布不均匀而产生的防滑点。maslennikov工艺的另一个缺陷是，因为诱导摩擦力不足而导致高变形阻力毛坯不能拉深。此外，橡胶的使用寿命短，而拉深又要求有较高的压力。为了克服这些缺陷， hassan et al 14 。提出了新的建议：用一个分为四部分的压边圈取代在maslennikov工艺中使用的橡胶圈。该技术进行深拉深的可行性已被验证，但是，有一个关键点约束着该装置的应用。那就是由于凸模材料流入压边分区之间

5、的空隙而产生起皱，如图1(a)所示。这个问题可以通过在这四个分区15之间的间隙中插入四小楔子得以解决。新的压边圈分为八个部分(四小楔子和四个拉深分区)取得了良好的效果。但是不幸的是，在使用薄板材的情况下，拉深部分和四个楔子的边缘部分由于局部过强的剪切力而出现裂痕，如图1(b)中所示。在目前的研究论文中最新提出，用一个分为四部分的双层锥形压边圈来消除局部褶皱和严重剪切变形区域这些不足。该论文细致探讨了变形机制和拉深条件的影响，并证实了现今深拉深技术的可行性。（a四分块压边圈下的局部起皱、b八分块压边圈下的局部剪切区）图1 原摩擦辅助拉深观察到的缺陷2. 四分区锥形压边圈的构造和拉深机制图2(a)

6、 所示为上述锥形压边圈示意图。它由一个固定的底座和四个成5°微斜锥形角的位面组成。拉深部分能匀速的在底座的锥形面上沿半径方向的滑动。四个滑配合的楔片被用来引导这些拉深部分在固定底座上的运动。理解拉深机制和压边圈的复合运动至关重要。拉深过程的第一步中，当两个端面分区在a方向上呈沿半径方向位移时，变形便开始了，如图2(b)所示。另外两个部分在b方向上反向进行复合运动，即与图2(b)中所示的拉深方向相反，向下和沿半径方向向外运动。因此，毛坯板材和模具在a方向上上升，而在b方向上，如图2(d)所示，毛坯板材和两个拉深部分并没有接触。此时，边缘有50%并不受制于压边圈。另一方面，a方向上的两个

7、拉深部分不断上升至模具的开口处，两者与毛坯板材有轻微的接触，如图2(c)所示。a方向上产生的摩擦力迫使毛坯变形并移向模具的开口处，同时，b方向上的两个拉深部分产生一个反向的摩擦力使毛坯变形。所以，这种技术成功地消除了八个部分组成的压边圈带来的局部强烈剪切变形。然而，b方向上的毛坯边缘由于受到圆周压力作用而出现了褶皱。在第二步拉深中，b方向上的压边圈做沿半径方向换位转移，与此同时，在a方向上的两个拉深部分以于第一步中相似的方式做复合运动。因此，第一步中b方向上产生的褶皱被同时校正了。重复上述两个步骤，就能成功制造出深杯形件。图2 四分区锥形压边圈的组成和运动示意图3. 实验准备3.1. 测试设备

8、图3是试验设备的主要组成部分的示意图。毛坯变形需要足够的压边力f1， 而冲压力f2主要起到提高杯形件尺寸准确性和帮助变形拉深的作用。合适的压边力f1由压力阀17控制，合适的冲力f2由压力阀16控制。拉深部件沿半径方向在0-2毫米范围内的位移运动由测微仪13和四个调整销11控制。压紧工具 5 应该在每次拉深操作后旋转90度来改变强制性半径方向替代运动的方向和毛坯与压边圈之间的压力。实验装置装配在一台水压机上。该水压机能轴向进行多范围速度的运动，并能产生最大为100kn的压力，而一台单独的泵所能产生的最大冲压力也只有10 kn。试验装置尺寸和最佳力度见表1。1拉深滑块,2液压缸,3,液压,4挤压垫

9、,5压紧工具,6模具,7 毛坯,8锥形边压边圈,9压边基座,10冲头， 11调整销, 12弹簧, 13测微仪, 14模具, 15工作台,16压力阀,17减压阀。图3 拉深试验设备示意图;表1 工具尺寸和实验工况模具外径(mm)120内径(mm)32剖面半径(mm)3锥形压边圈外径(mm)116内径(mm)35侧偏量(mm)1径向速度(mm/s)0.2压边力(kn)40-100辅助拉深器直径(mm)30剖面半径(mm)2速度(mm/s)0.8冲压力(kn)1-53.2.实验材料和实验条件使用0.5毫米厚度的柔软的铝(al-co)制毛坯作为试验材料。表2中所列数据为单轴张力测试中得到的材料的属性常

10、数f， n和r。当毛坯的直径分别为86和110时，拉深比率由2.87变为3.67。为了研究毛坯变形的情况，在毛坯表面预先标注出2毫米的同心圈，如图4(a)所示。其中，最小的圆直径为28毫米，最大的为80毫米。此外，还在毛坯表面标注出a， b， c三个沿半径的方向。在奇数/偶数次拉深时，部件分别在a/b方向上进行替换移动，而部件c和压边圈各部分的衔接边界重合。为了研究在杯侧壁的格栅的变形，在直径为110毫米的毛坯上标示出间隔为5毫米的同心圆和五条间隔为22.5 °圆周角的半径，如图4(b)所示。45 °和-45°的半径方向与指示边界c重合，而零度方向为b方向，该方向

11、上在偶数次拉深时受力变形。毛坯板材和压边圈之间干燥的摩擦有利于增加产生的摩擦力。不过，特氟隆影片(ptfe)被用作在毛坯板材和模具之间的固体润滑剂，来减小摩擦力。 （a） 拉深率2.87，板径86mm （b） 拉深率3.67，板径110 mm图4 板材上标明的圆形栅格和方向 表2 柔软的铝制毛坯的机械特性和尺寸f值(mpa)220n值0.27r值0.76厚度(mm)0.5毛坯直径(mm)86、1104. 结果讨论（略）5. 目前的深冲压技术的可行性图5、图6为已拉深杯形件；前者在50次拉深之后侧壁c方向（±45°方向）出现弧坑状缺陷。在制作过程中，c方向上板材的运动比b、a

12、方向上的程度大，因此板材撞击到模具开口处的带扣而在冲压和模具相分离时产生凹陷。然而，这个凹陷是可以被消除的：每隔一次拉深，把毛坯板材就衔接边缘方向旋转45°。这个简单的技术帮助制造出了64毫米高3.67比率的杯形件，如图14所示。这样的杯形件需要经过100次的拉深，但是也证实了目前的依靠摩擦力的深拉深技术具有可行性。图5 c向上的弧坑状缺陷图6 成功的杯形件例子(=3.67，杯形件高度=64 mm，n=100)6. 结论在借助摩擦力实现深拉深的技术方面，提出了一种新的方法来实现深杯形件的制造，即借助一个由四个锥形部分组成的压边圈。这种新设备克服了传统的四部分或八部分构成的压边圈会产生

13、局部褶皱和剧烈的剪切变形等问题。拉深机制和拉深条件的影响也被细致的观察了。当压边力大于80kn，辅助冲压力大于4kn时，拉深效率有显著提高。这种技术能成功制造出比率为3.67的深杯形件，这也证实了目前改良技术的可行性。由于每次拉深压边圈沿半径方向的位移被限制在1毫米，制造过程需要100次拉深。但是，在该工艺中，自始至终只使用了一套刚性工具，加工时间也可由增加每分钟的冲压次数来缩短。因此，该工艺便于小批量深杯形件的生产。附件2：外文原文（复印件）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