1、PDF外文：http:/ 引用的外文文献及其译文 A study on the improvement of formability for elliptical deep drawing processes D.H. Parka,*, S.S. Kanga, S.B. Parkb Abstract The punch and die corner radii, the lubricant condition, the working speed, the blank-holding force, the friction force and
2、the clearancechange the formability of the deep drawing process. In general, sheet metal forming may involve stretching, drawing or variouscombinations of these basic modes of deformation. The influence of the punch and die corner radii is of great importance in the design ofsheet metal working proc
3、esses. Recently, most of the research for the sheet metal deep drawing process has been performed on theformability 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 bee
4、n determined by trial-and-error using industrial experience and post-processingtests, 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 ra
5、dii of the punch and die. In this study, the optimalcorner radii of the punch and die in the deep drawing process with a non-axisymmetric blank shape are proposed.Research has been carriedout using diverse technologies including experimentation and the finite element method. C 2001 Elsevier Science
6、B.V. All rights reserved Keywords: Non-axisymmetric deep drawing； Punch corner radius； Die corner radius； Finite element method； Blank shape 1. Introduction Many research investigations for cylindrical products have been carried out into the fundamentals of the deep drawing process 1 4. Thus, this h
7、as produced manyapplied shapes such as rectangular, elliptical and non-axi-symmetrical. In general, most of the research for the deepdrawing process has been performed on the formability of anaxisymmetrical shape, but there are no any concrete reports on the formability of an elliptical shape 5 7. F
8、or 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 forceand the clearance are influential. In general, sheet metalforming may involve stretching, drawing or various combi-nat
9、ions of these basic modes of deformation. It is important to determine the influence of the process variables in thedesign of sheet metal working processes. Especially, thepunch and die corner radii for deep drawing will affect theformability. Research works for a better understanding ofsheet metal
10、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
11、 material flow is non-uniform 8. It is important to changethe blank shape, because a blank comes into contact with the die 9,10. In this study, the corner radii of the punch and die for the elliptical deep drawing process were studied toinvestigate their influence on formability. 2. Experiment
12、al work 2.1. Experimental material The 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
13、 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) 662 665 Table 1Mechanical property in the tensile direction Direction Yield strength(MPa) Tensil
14、e strength(MPa) Elongation(%) 0 210 311 46 45 226 &n
15、bsp; 323 43 90 222 307
16、 45 2.2. Experimental equipment Deep 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 firstdrawing process. The clearance and the corner radii of thepunch and die are lis
17、ted in Table 2. The forming sequence forthe product consists of three processes which are: (a) firstdrawing； (b) redrawing； (c) elliptical drawing. The cornerradii of the punch (Rp) and die (Rd) were different for eachprocess. The initial blank-holder force was determined as theminimum force that co
18、uld prevent the wrinkling of theblanks 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 radiiof the punch and die in first drawing were the three typesmentioned in Table 3.
19、 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) Cle
20、arance (mm) First drawing Rp =15, Rd = 10 2 (1.25 t) Redrawing Rp =12, Rd = 8 2 (1.25 t) Elliptical drawing &nbs
21、p; Rp =8, Rd = 5 Long side: 1.50,short side: 1.39 Table 3Test conditions in first drawing Type Rp (mm) Rd (mm)
