Patent GB-825721-A (GB)
Title: Method and apparatus for forming tubular articles
IPC: B21D24/00
Filed: 1957-06-13
Abstract: 825,721. Cupping; embossing; curling; trimming. KAISER ALUMINUM & CHEMICAL CORPORATION. June 13, 1957 [July 30, 1956], No. 18714/57. Class 83 (4). An apparatus for forming tubular articles from flat metal blanks comprises first and second sets of die rings 33, the second set of the rings being disposed opposite to and spaced from the first sets of the rings, a fluid operable piston 5 interposed between the first and second sets of die rings, a first forming ram 25 secured to one side of the piston and a second forming ram 25 secured to the opposite side of the piston, the forming rams being arranged so that during one full stroke of the piston the first forming ram is inserted into the first set of die rings and the second forming ram is then inserted into the second set of die rings, alignment means including the piston for maintaining the forming rams on true linear paths of travel and means including a pressure pad 20 for maintaining a blank 40 between each of the forming rams and the innermost die ring of the associated die set prior to the insertion of the ram. Located at each end of the cylinder 3 for the piston 5 is a guide ring 19 housing the pressure pad 20 which encircles the forming ram 25 adjustably attached to the piston rod 6. Constant pressure air chambers 30 are provided at each end of the housing 1 between the end of the cylinder 3 and the guide ring 19. The die rings are floatingly carried in holders 70 mounted on rods 39 and spaced apart by washers 33<SP>1</SP> the die rings being of progressively reduced diameter and of progressively increased distance from each other. The blank 40 which is coated with a lubricant may be heated by an induction heater (not shown) and a plurality of small rods 50 secured in the innermost die ring support the blank in the opening 80. When the ram carrying a formed blank contacts a switch 58 at the end of its stroke jaws 60 are closed about the blank to strip it from the ram and after a predetermined time a timer 59 de-energizes solenoids 64 to allow the formed blank to drop into a hopper from whence it is conveyed to a trimming apparatus (not shown). The bottom of the formed blank is ribbed by a member 81 cooperating with rib recesses 83 in the end of the ram. Openings 27 and 28 in the ram allow air to enter the ram and break any vacuum to facilitate stripping of the formed blank from the ram. In a modification the outermost die ring is replaced by a ring 90 and an air ring 90<SP>1</SP> (Fig. 9). The ring 90 is provided with a segmented stripper and lip forming member 100 held together by an annular helical spring 102. Mounted in spaced relation to the die ring 90 is a bearing block assembly 108 comprising a recessed bearing block 109 secured to the piston of a pneumatic cylinder 126. In operation, as the ram, which is provided with stepped surfaces 140 and 141, passes through the die ring 90 the final portion of the formed blank is pinched off as the stepped surface 140 enters the die ring. As the ram and the formed blank move forward to engage the pressure block 109 the segments 101 of the stripper and lip forming member 100 drop on to the ram behind the blank. When the ram engages the block 109 the ribs are embossed at the bottom of the blank and switches in the block recess are actuated to remove detents 115 and 116 to enable fluid pressure cylinder 126 to move the block 109 so that the formed blank is forced back against the stripper and lip forming member 100. As the lip is formed air pressure is supplied from the air ring 90<SP>1</SP> to the end of the ram to release the blank from the ram which returns to its initial position. A switch on the block 109 arrests backward movement of the blank by stopping the piston 125 and another switch reverses the piston 125 to retract the block to its initial position within the bearing block assembly and the formed blank falls into a hopper. The severed end B of the blank is stripped from the ram by an air blast.