外文翻译-- 一项对提高成形性椭圆拉深过程的研究.docx

附录引用的外文文献及其译文A study on the improvement of formability for elliptical deep drawing processesD.H. Parka,*, S.S. Kanga, S.B. ParkbAbstractThe punch and die corner radii, the lubricant condition, the working speed, the blank-holding force, the friction force and the clearance change the formability of the deep drawing process. In general, sheet metal forming may involve stretching, drawing or various combinations of these basic modes of deformation. The influence of the punch and die corner radii is of great importance in the design of sheet metal working processes. Recently, most of the research for the sheet metal deep drawing process has been performed on the formability of an axisymmetric shape, but there are not any concrete reports on the formability of a non-axisymmetric shape. In addition,the conventional corner radii of the punch and die have been determined by trial-and-error using industrial experience and post-processing tests, and only approximate corner radii of the punch and die have been presented. In order to obtain the optimal products in the deep drawing process, elliptical deep drawing tests were carried out with several corner radii of the punch and die. In this study, the optimal corner radii of the punch and die in the deep drawing process with a non-axisymmetric blank shape are proposed.Research has been carried out using diverse technologies including experimentation and the finite element method. C 2001 Elsevier Science B.V. All rights reservedKeywords: Non-axisymmetric deep drawing; Punch corner radius; Die corner radius; Finite element method; Blank shape1. IntroductionMany research investigations for cylindrical products have been carried out into the fundamentals of the deep drawing process 14. Thus, this has produced many applied shapes such as rectangular, elliptical and non-axi-symmetrical. In general, most of the research for the deep drawing process has been performed on the formability of an axisymmetrical shape, but there are no any concrete reports on the formability of an elliptical shape 57. For the improvement of the formability of deep drawing process,the punch and die corner radii, the lubricant condition, the working speed, the blank-holding force, the friction force and the clearance are influential. In general, sheet metal forming may involve stretching, drawing or various combi-nations of these basic modes of deformation. It is important to determine the influence of the process variables in the design of sheet metal working processes. Especially, the punch and die corner radii for deep drawing will affect the formability. Research works for a better understanding of sheet metal forming processes have been carried out using diverse technologies including experimentation and the finite element method (FEM).The formability of non-axisymmetrical shapes has been explored under the process conditions that the blank size is different between the major and minor axes and that the material flow is non-uniform 8. It is important to change the blank shape, because a blank comes into contact with thedie 9,10. In this study, the corner radii of the punch and die for the elliptical deep drawing process were studied to investigate their influence on formability.2. Experimental work2.1. Experimental materialThe material used in this study is an electro-galvanized sheet steel SECE with a thickness of 1.6 mm. Tensile tests were carried out in the directions of 0, 45 and 90 to the rolling direction. The gauge length and width of the tensile specimens were 25 and 50 mm, respectively. The mechan-ical properties in the tensile direction are indicated in Table 1.D.H. Park et al. / Journal of Materials Processing Technology 113 (2001) 662665Table 1 Mechanical property in the tensile directionDirection Yield strength(MPa) Tensile strength(MPa) Elongation(%)0 210 311 4645 226 323 4390 222 307 452.2. Experimental equipmentDeep drawing tests were carried out using a punch with a diameter of 56 mm and a die with a diameter of 60 mm.Fig. 1 presents the dimensions of the tools used in the first drawing process. The clearance and the corner radii of the punch and die are listed in Table 2. The forming sequence for the product consists of three processes which are: (a) first drawing; (b) redrawing; (c) elliptical drawing. The corner radii of the punch (Rp) and die (Rd) were different for each process. The initial blank-holder force was determined as the minimum force that could prevent the wrinkling of the blanks and was kept constant during the test for each blank.Elliptical deep drawing tests were performed at various corner radii in a 300 t mechanical press. The corner radii of the punch and die in first drawing were the three types mentioned in Table 3.Fig. 1. Dimensions of the tools (mm) used in the first drawing process.Table 2 Corner radius and clearance （t= 1.6 mm）Process Corner radius (mm) Clearance (mm)First drawing Rp =15, Rd = 10 2 (1.25 t)Redrawing Rp =12, Rd = 8 2 (1.25 t)Elliptical drawing Rp =8, Rd = 5 Long side: 1.50,short side: 1.39Table 3 Test conditions in first drawingType Rp (mm) Rd (mm)A3 6.4 16B3 9.6 16C3 12.8 16D.H. Park et al. / Journal of Materials Processing Technology 113 (2001) 6626652.3. Blank shape and measurementThe final product is of an elliptical shape that consists of a circular arc at the long side and a straight line at the short side. The blank shape designed by trial-and-error was simply fabricated with an equivalent surface area to the final product, and then a size of final blank was determined through many experiments 1113. Fig. 2 presents the blank shape designed by trial-and-error. Figs. 3 and 4 present experimental results for each process of elliptical deep drawing. Measurement of the thickness distribution of the product has been made a point micrometer measuring fromthe center of the product to the edge of flange at the interval of 3 mm, and the thickness of the product is measured in two parts of both the long and short sides.Fig. 2. Blank shape designed by trial-and-error.Fig. 3. Experimental result for each process.Fig. 4. An elliptical deep drawingD.H. Park et al. / Journal of Materials Processing Technology 113 (2001) 6626653. Results and discussionThe material used in computation is electro-galvanized steel for which the stress-strain characteristic is expressed as MPa: (1)The process variables used in simulation are as follows: (1)sheet thickness, t =1.6 mm; (2) diameter of die, 60 mm; (3)diameter of punch, 56 mm; (4) blank-holder force, 9800 N;5) Youngs modulus, MPa; (6) Poissons ratio,0.3; (7) Coulomb coefficient of friction, 0.04The coefficient of friction among the sheet, punch, die and blank holder was taken as 0.04 due to the wet friction of using drawing oil. It was assumed that the friction coeffi-cient would remain constant during the operation. The finite element mesh system is constructed with 445 nodal points and 404 elements. By the geometric symmetry, a quarter of a sheet blank is considered. Fig. 5 shows the deformed mesh configurations at a stroke of 46 mm. The formability and productivity of sheet metal forming process can improve the proposed corner radii of the punch and die.In order to show the change of the deformed shape, the corresponding boundary contours of the deformed mesh with respect to punch height are shown in Fig. 6. In case of Rp =6.4 mm and Rd = 16 mm, the computed results are in better agreement with the experimental results at a stroke of 46 mm. Fig. 7 shows the comparison of the boundary shape contour between the computed and experimental results in the case of Rp =9.6 mm and Rd = 16 mm, whilst Fig. 8 shows the comparison of the boundary shape contour between the computed and experimental results in the case of Rp =12.8 mm and Rd = 16 mm.In the case of Rp = 6.4 mm and Rd = 16 mm, the thick-ness distribution along the rolling direction (the long side) and transverse direction (the short side) at a stroke of 46 mm is shown in Fig. 9. The thickness from the long side is smaller than that from the short side near the punch shoulder, which is in better agreement with experiment. The thickness distribution of the flange region presents a difference between the experimental and computed results. Fig. 10 shows the comparison of the experimental results and thefinite element method in the case of Rp = 9.6 mm and Rd =16 mm, whilst Fig. 11 shows the comparison of the experimental results and the finite element method in case of Rp =12.8 mm and Rd = 16 mm.The thickness distribution of the entire region has a good agreement between the experimental and computed results.An optimum design procedure of process parameters has been carried out for the optimum process of sheet metal forming. Optimum design conditions of the corner radii are sought in deep drawing processes for a better quality of product.Fig. 5. Thickness distribution of the first drawing product.D.H. Park et al. / Journal of Materials Processing Technology 113 (2001) 662665Fig. 6. Comparison of the boundary shape contour between the computed and experimental results (type A3).Fig. 7. Comparison of the boundary shape contour between the computed and experimental results (type B3).Fig. 8. Comparison of the boundary shape contour between the computed and experimental results (type C3D.H. Park et al. / Journal of Materials Processing Technology 113 (2001) 662665Fig. 9. Comparison of the experimental results and the finite element method (type A3).Fig. 10. Comparison of the experimental results and the finite element method (type B3).Fig. 11. Comparison of the experimental results and the finite element method (type C3).D.H. Park et al. / Journal of Materials Processing Technology 113 (2001) 6626654. ConclusionsThe cross-section of the product body, punch corner radius (Rp) and die corner radius (Rd) were considered as the main design parameters. This study focused on acquiring and quantifying process design variables such as the corner radii of the punch and die for elliptically shaped deepdrawing products. The results are summarized as follow.The optimal corner radii of the punch and die for the improvement of formability are proposed in the elliptical deep drawing process. The present analysis has been carried out for deep drawing process of an elliptical cup. The computed results along the corner radii of the punch and die were in better agreement with the experimental results.AcknowledgementsThis work was supported by the Engineering Research Center for Net Shape and Die Manufacturing (ERC/NSDM) at Pusan National University. 一项对提高成形性椭圆拉深过程的研究D.H. Parka,*, S.S. Kanga, S.B. Parkb摘要冲床和模具圆角的半径、润滑剂条件、工作速度、压边力、摩擦力和间隙改变了拉深过程的可成形性。一般来说,可能包括拉伸板料成形、制图、多方面的这些因素同时作用的基本模式的变形。影响冲床和模具角落钣金加工过程中非常重要的设计。最近,大部分研究对板料拉深成形过程已经进行了成形性的轴对称的研究,但没有任何具体的报告,引入非完全轴对称单元成形性能的形状。此外,传统的角落半径冲床和模具的试误取决于使用的行业经验和后处理测试,但只有半径的近似角落的冲床和模具已被提交。为了获得最优产品在深拉拔工艺、椭圆拉深试验得出的半径与几个角落的冲床和模具。在这项研究中,最优角落的半径冲床和模具的拉深过程中引入非完全轴对称零件毛坯形状与工作提出了建议。研究和利用不同实践技术包括实验和有限元方法。农业科学B.V. 2001年保留所有权利关键词:引入非完全轴对称拉深冲压角落，角半径，有限元方法，空白的形状1.介绍许多研究圆柱的产品的基本原理已经被运用到拉拔工艺1-4。因此,这产生了许多应用形状如长方形、椭圆和非轴对称的。一般来说,大多数的研究在深度拉拔工艺的回转体的形状中被应用了,但没有任何具体的报告在椭圆形状的成形中应用5-7。为提高拉深的成形过程,冲床和模具角落的半径、润滑剂条件,工作速度、压边力、摩擦力,间隙很有影响。一般来说,板料可能包括拉伸成形、制图、各种这些基本模式的综合的变形。在设计钣金加工过程中确定过程变量的影响是很重要的。尤其,冲床和模具角半径将直接影响到拉深成形性。科研工作使更好的理解板料成形过程已经进行了一定的应用包括实验和不同技术的有限元法(FEM)。非轴对称形状的成形探讨了工艺条件下的毛坯尺寸在主轴和次要轴条件下的差异,以及物料流的不均匀性8。改变毛坯的形状是很重要的,因为毛坯最终影响到模具9、10。在这项研究中,对椭圆的拉深过程冲床和模具角半径进行了研究，研究它们对成形性的影响。相关作者0924-0136/01/$-前面内容2001科学B.V.出版社版权所有。PII: S 0 9 2 4 - 0 1 3 6 ( 0 1 ) 0 0 6 6 4 - 1材料加工技术杂志113 (2001) 6626652.实验工作2.1. 实验资料材料应用于该研究是一种电镀薄钢板SECE薄钢板的厚度为1.6毫米。拉伸试验进行了进一步的研究，研究方向在0度45度和90度方向。拉力长度和宽度的标本分别为25毫米和50毫米。拉伸过程中的力学性能显示于表1。表1 力学性能拉伸方向方向 屈服强度 抗拉强度 伸长 （Mpa） （Mpa） （%）0 210 311 4645 226 323 4390 222 307 45表2 圆角半径及间隙（t=1.6mm）圆角半径（mm） 间隙（mm）第一次拉伸 Rp=15，Rd=10 2（1.25t）第二次拉伸 Rp=12，Rd=8 2（1.25t）椭圆拉伸 Rp=8，Rd=5 长边：1.50，短边：1.39表3 第一次拉伸下的测试类型 Rp （mm） Rd（mm）A3 6.4 16B3 9.6 16C3 12.8 162.2.实验设备拉深试验得出采用冲压机用56个毫米直径和一个冲模直径为60毫米。图1给出了第一绘画的过程中使用的工装夹具的大小。冲床和模具间隙以及圆角半径都列在表2中。产品的形成过程包括三个过程:(一)第一次拉伸;(b)二次拉伸;(三)椭圆形拉伸。冲压半径(Rp)及模具半径(Rd)在每个制造过程中都不同。确定了最初的最小压边力能防止起皱和保持测试过程中每个坯料的参数不变。椭圆形的拉深试验的圆弧半径在300吨机械压力机下显得更复杂。冲