58 00847 53 * ** ** Journal of Japan Institute of Light Metals, Vol. 58, No. 008, pp. 47 53 Production of aluminum tall container with flange by hydraulic bulging with compression of surrounding material Nobuo HATANAKA*, Takashi IIZUKA** and Norio TAKAKURA** Bulging process is suitable to produce cups with wide flange because of keeping the contour shape of blank sheet unchanged. On the other hand, it is difficult to form tall cups by conventional bulging because, at punch shoulder, thickness of metal sheet becomes much smaller than other portions and it results in a quick breakage there. When the way to decrease the thickness of a sheet metal during the process approaches more to the uniform one, it becomes possible to form cups with both of wide flange and large height. In this study, a new bulging process combined with ironing was proposed in order to form tall cups with wide flange. In this new method, as in the conventional hydraulic bulging method, hydraulic pressure was used to deform metal sheet uniformly. In this hydraulic bulging, compression around die hole by a metal ring assisted the hydraulic pressure to put material into the die-hole. In addition to that, a counter metal punch was used to prevent the material on the head of bulged portion from locally thinning. Furthermore, following ironing makes it possible to decrease thickness of sidewall. In order to clarify the effectiveness of this method, differences of the configuration and the thickness strain distribution between products formed by conventional and new methods were investigated. Finally, it was confirmed that this method make it possible to produce a cup four times as tall as conventional one. Received August 0, 007 Accepted October 3, 007 Keywords: hydraulic bulging, ironing, deep container, flange, aluminum sheet 1 3 3 4,5 * 774 0017 65 Anan National College of Technology 65 Minobayashi, Anan-shi, Tokushima 774 0017. E-mail: hatanaka@anan-nct.ac.jp ** Kyoto Institute of Technology Kyoto-shi, Kyoto.
58 008 Fig. 1 Hydraulic bulging process with counter punch. Fig. 1 a Fig. 1 b Fig. d h t 0 D t 3 t 1 t V 1 V π V1 d t π ( ) t0 { D ( d t ) }( t0 t3) 1 4 4 Fig. Improvement of bulging process by compression of the material around die hole. Fig. 3 Relationship between outer diameter of compressing region and increase of bulged height in case of different compression rate of metal sheet. π V ( d t) t π dht 4 V 1 V h 1 h { D ( t0 t3) ( d t) ( t3 t1)} 4dt 3 1 h0 ( d t ) ( t0 t1) 4dt 1 4 3 4 t 1 t 1/ t 0 D Fig. 3 Fig. 4 Fig. 4 b Fig. 4 c
J. JILM 58 008 Table 1 Dimensions of tools used for hydraulic bulging and ironing Punch Die Radius Radius Diameter, of punch Diameter, of die D (mm) shoulder, D (mm) shoulder, R (mm) R (mm) Rigid bulging 36.0 4.0 40.0 4.0 Hydraulic bulging 40.0 4.0 Ironing process 38.5 4.0 40.0 4.0 Table Mechanical properties of material Fig. 4 Bulging process with compression of die hole around. Fig. 4 d Table 1 40 mm 4mm 36 mm 4mm 38.5 mm 4mm 70 kn 1mm A1050P O d 60 mm Table F n s Fe n 1mm t 0 t ε t t ln t 0 5 Fig. 5 ab cde f g h Material A1050P-O Yield stress Y MPa 7 Tensile strength s B MPa 8.7 Total elongation d % 36 Plastic modulus F MPa 175 Work-hardening exponent n 0.30 Vickers hardness HV 7 Fig. 5 Schematic diagram of equipment and tool arrangement for this new hydraulic bulging process. a Blank, b Die, c Compression ring, d Blank holder, e Oil pot, f Oil, g Counter punch, h Press ram, i Load cell, j Release valve, k Moving shaft, l Oil pump, m Pressure gauge P 1 P i P 1 jk d P 1
58 008 Table 3 Dimensions of tools used for hydraulic bulging with compression of the material around die hole and ironing Punch Die Compression ring Diameter, D (mm) Radius of punch Radius of die Outer Inside Diameter, shoulder, shoulder, diameter, diameter, D (mm) R (mm) R (mm) D (mm) d (mm) Hydraulic bulging 31.5 4.0 50.0 30.0 Ironing process 30.0 4.0 31.5 4.0 c PP l P 3 m n Table 3 31.5 mm 4mm 30 mm 4mm 30 mm 50 mm 150 kn 30 MPa 450 kn t.0 mm 10 mm A1050P O Table 1mm 1mm Fig. 6 1mm Fig. 6 a 7.5 mm 7.3 mm p 5MPa h 1.4 mm p 6MPah 17. mm p 6MPa h 1 mm 15 mm 16.5 mm Fig. 6 Differences of product states obtained in various bulging conditions. h 1 mm p 10 MPa h 15 mm p 7MPa p h 16.5 mm Fig. 6 b r 16 mm 0.39 0.083 p 5MPa 6MPa
J. JILM 58 008 h 1 mm 0.668 h 15 mm 0.856 r 5mm r 13 mm h 1 mm h 1 mm p 10 MPa h 15 mm p 6MPa Fig. 7 Fig. 7 a h 1 mm 15 mm 15.1 mm 16.4 mm Fig. 7 b h 1 mm r 14 mm h 15 mm r 7mm Fig. 8 Fig. 8 a Fig. 8 b Fig. 8 c h 1 mm Fig. 8 d Fig. 7 Variations of product state by following ironing. Fig. 8 Comparison between cross sections of products obtained in various bulging processes.
58 008 Fig. 11 Breakage occurrence by hydraulic bulging after compressing the material around die hole. Fig. 9 Deformation behavior of sheet metal in compressing the material around die hole. Fig. 1 Thickness strain distributions of products in hydraulic bulging after compressing the material around die hole. Fig. 10 Thickness strain distributions of products in compressing the material around die hole. mm D 50.0 mm Fig. 9 Fig. 10 10 mm 15 mm e t 00.0.40.6 Fig. 11 Fig. 1 e t 0. e t 0 0.4 0.6 0 18 MPa 19 MPa 16 MPa 19 MPa 17 MPa 16 MPa e t 1.1 Fig. 13 Fig. 14 19 MPa Fig. 15 a 19 MPa Fig. 15 b 16 MPa Fig. 15 c Fig. 16
J. JILM 58 008 Fig. 13 Deformation behavior of sheet metal in hydraulic bulging with compression of the material around die hole e t 1.1, t 0.0 mm. Fig. 14 Thickness strain distributions of products obtained by hydraulic bulging with compression of the material around die hole e t 1.1, t 0.0 mm. Fig. 15 Variation of product appearance in each process step of this new bulging method. e t 0.81.0 31.5 mm 33.1 mm Fig. 16 Variation of thickness strain distribution in each process step of this new bulging method. 1 3 4 5 e t 0.81.0 31.5 mm 33.1 mm 1 56 006, 39 334. 56 006, 483 488. 3 53 00, 11 1. 4 15 003, 309 310. 5 54 003, 41 4.