Patent GB-982694-A (GB)
Title: Method and apparatus for producing automotive vehicle bumpers
Inventor: O'BRIEN PAUL ROWEN
IPC: B60R19/02
Filed: 1961-05-19
Abstract: 982,694. Making vehicle bumpers; bending. REYNOLDS METAL CO. May 19, 1961, No. 18383/61. Headings B3A, B3E and B3Q. A method of making a bumper for a motor vehicle comprises extruding an aluminium alloy strip of an irregular grooved cross-section, cutting to length, bending and otherwise shaping the blank in a press-forming operation, trimming, to final shape and chemically brightening. An aluminium alloy strip is extruded and cut to length to form a blank 26, Fig. 3, and then heated for five to fifteen minutes to a temperature of 935-980‹ F. in an atmosphere of air and ammonium fluoborate to form a surface coating capable of taking a bright finish after subsequent treatment. Within ten to forty-five seconds the blank is subjected to forming operations. In the first, while still at 900-950‹ F., it is pressed to form a recess 38 for a rear light, in a second at from 850-900‹ F. the walls 48 are made perpendicular to the general axis of the bumper and the ridges 50 are formed, Fig. 13, and in a third forming operation at 800-850‹ F. the end flanges 62 are formed, Fig. 20. After quenching, the blank is trimmed and pierced at 70, 72, 74 and 76, and tempered and then buffed, chemically brightened and anodized. The end flanges 62 may be formed in the press shown in Figs. 63 and 64. The blank is supported on a fixed die 556 with its ends slightly overhanging the die and may be held down by a member 552. Plates 60a attached to an upper press head then descend, bend the overhanging ends and draw them down into contact with the ends of the fixed die to form the flanges 62. The dies may be heated to 350-400‹ F. In another example, instead of having separate ends for attachment to the flanges 62, a bumper may be formed with integral ends. A heat treated blank of section as in Fig. 41 is placed in an apparatus comprising a central grooved die member 222, Fig. 32, and two end dies 226 of similar cross-section rockable about pins 248. As an upper die 236 descends it enters into the blank and presses the centre member 222 down against a pneumatic cushion 274 while the end dies pivot about the pins 248 to bend the ends of the blank around the sides of the die 236. As the die 222 descends further to its lowest position, the bent ends move along grooves 252 in re-strike dies 254 which smooth out any corrugations formed by the bending. During the bending, portions 270 and 262 of the upper and lower central dies co-operate to form an indented portion later to become a light window and number plate location. The ends of the blank may be held in the dies 226 by flanges 284, Fig. 43, which are moved over the upper edges 280, 282 of the bumper by means of air cylinders 286. A plunger 299 pushes the blank into contact with the flanges. Alternatively, the blank may be held between stationary bars 324 and plungers 322, Fig. 37. The bending dies may be electrically heated. After removal from the bending press and quenching, the indented portion 204 is trimmed and the ends 216 are trimmed and shaped as required and fixing brackets 422 and 428, Fig. 45, are brazed or welded in position. Fig. 49 shows a modified form of bumper in which the fixing brackets 444 are snapped into position in the bar. They may also be brazed or welded. In order to prevent wrinkling of the edge at the inside of the bend, the ends of the blank within the rocker members 226 may be stretched. The ends 472 of the bumper are gripped by a member 460, Fig. 56, and as the die 236 descends, a cam 452 thereon engages the fulcrum pins 248 of the members 226 and moves them outwardly along slots 450 in their supporting members 258a. As the rockers 226 move back to their horizontal positions, cams 476 thereon engage a fixed member 478 to push the pins 248 back along the slots 450. Alternatively, the end gripping devices previously described could be used in addition to, or instead of, the grippers 460. In a modified form of apparatus, the middle part of the blank is gripped between upper and lower dies 330, 340. At the ends of the upper die and originally positioned as indicated by the dotted lines 336a in Fig. 51 are rocker die members 336 and at the ends of the lower die 340 are dies or punch members 342. After the blank has been gripped between dies 330 and 340, the rocker members are moved by cylinders 356 from horizontal to vertical positions along paths determined by guide grooves 388 and 390 so that the ends of the blank are bent round the curved members 342. The dies 330 and 340 are then moved together by their cylinders 350, 352 to the positions shown in Fig. 53 so that the stationary members 342 produce bulges 344 in the bumper. The bumper may be formed with a dovetailed recess 608, Fig. 70, to receive a rubber or similar impact absorbing insert 620.