Patent GB-733245-A (GB)
Title: Improvements in or relating to apparatus and method for conforming sheet material topredetermined shapes
IPC: B21D22/12
Filed: 1953-03-09
Abstract: 733,245. Stamping. DOUGLAS AIRCRAFT CO., Inc. March 9, 1953 [March 11, 1952], No. 6427/53. Class 83 (4). A press for stamping sheet metal comprises a hollow container with two oppositely disposed surfaces, adjacent one of which is an inflatable bag by which an elastic pad is pressed on to the work resting on formers, the work and the formers being- inserted into the container through lateral openings and means being provided to prevent dislodgement during working. In one form, Figs. 1-3, a rigid bed 21 supports a container built up of upper and lower sections 52 held together by vertical bolts 54 and horizontal tie rods 56. At each end the container has an opening 24 through which platens 25 carrying formers 27 and sheet metal 26 may be moved into an out of operative position by means of rods 32, 35 secured to pistons within double-acting pressure-fluid cylinders 31, 34. Mounted within the upper part of the container is an elastic bag 22 adapted to have pressure fluid forced in or sucked out. through a.pipe 41 which may be connected through valve gear to pressure pump 37 or scavenging pump 38, both driven from a motor 39. Beneath the bag 22 is a relatively thick elastic pad 23 which is deformed by the bag so as to press the work to the external shape of the formers as shown in Fig. 2. The pad also bears on the bevelled edges of the platens, setting up equal and opposite outwardly directed forces which hold the platens in position. The bag conforms substantially to the interior shape of the container, a rigid fairing 63 of for example, glasscloth and plastic being interposed between the bag and the container at each end. Disposed within the bag. is a rigid plate 67 having a bossed aperture 68 into which is secured the. end of the pipe 41. This pipe also serves to suspend the plate and bag within the container. The pressure pad 23 has along each side a double bead 77 by which it is clamped between the upper and lower members 52 and at each end has a double head 79 by which it is gripped between upper and lower clamping members 81, 82, the latter being screwed to the upper members 52. Between the edge regions of the bag and pad may be inserted an elastic filler 30, Fig. 16. Each platen 25 comprises a concave tray formed by a base 102, Fig. 7, having bevelled side and end members 104, a centring groove 100 and a removable filler member 50. The end members serve to close the openings 24 when in operative position. In a modification, Fig. 18, the body of the press is formed from a number of one-piece sections 132 held together by the rods 137. The sides of the pad 23 are held between the upper interior surfaces of the sections and separate inserts 96 or alternatively lower sealing members 124 pressed upwardly by springs 123 in the members 96 may be used as shown in Fig. 9. In another modification, Fig. 19, the body of the press comprises a tubular shell 141 housing upper and lower members 142, 143 shaped to receive the pressureapplying means and the platens. In the form shown in Fig. 21, the press body comprises upper and lower cast members 151, 152 held together by bolts 158, each member being of less general thickness than in the preceding forms but having integral spaced reinforcing ribs. Fig. 22 shows another modification in which the bag and pressure pad are circular in plan and are mounted within an upper member 161 secured by bolts 163 to a lower member 162. These members are spaced apart by blocks 186 to provide room for four intermediate members 166 each having a concave work-receiving part 167 and a tailpart 168 by which it is pivoted to a block 186 so that it can be moved between an external loading and unloading position and a working position beneath the pressure pad. In operation the work is placed on the formers carried by the platens, the platens are moved into position beneath the pressure pad and pressure fluid is admitted to the bag.