Patent GB-600260-A (GB)
Title: Improvements in apparatus and method for working sheet metal and other sheet material
IPC: B21D5/04
Filed: 1945-01-18
Abstract: 600,260. Stretching; drawing; stamping. ANDERSON, F. Jan. 18, 1945, No. 1547. [Classes 83 (ii) and 83 (iv)] A machine for differentially stret hing and thus curving a in tal &c. sheet in two directions comprises a guide and a number of die slots through which the sheet is successively pulled, the guide imposing a drag and the dies having different contours and being arranged in stepped relation to bend the sheet abruptly first in one direction and then in the reverse direction. The dies are adjustably mounted to vary their relative position and the form of the slots, except the first, can be varied during or between operations. The sheet 13, Figs. 5 and 8, is pulled by grippers 10, flexibly connected to a motor-driven carriage 2, through two dies D<SP>1</SP>, D<SP>2</SP>. The first is mounted, for angular adjustment, by circular ribs and pins 62, Fig. 10, engaging corresponding grooves and slots 54, 55 in supports 51 carried by a slide 32 movable longitudinally on the base 1, which is formed as a drip tray. The die D <SP>1</SP> has, near its centre of adjustment, insets 80, 81, Figs. 5 and 8, either of which may act as a working surface according to the relative position of the dies. The slide 32 is moved to or from the die D<SP>2</SP> by toggles 34 and a handle 37, Fig. 11, or a hydraulic cylinder 184, or rollers 44 engaging an adjustable cam tract 45 on a bar 25 connected to the carriage 2. The angular position of the die D' .may also be varied during the process by an adjustable link 79, Fig. 10, lever 76, roller 74 and an adjustable cam track 24, Fig. 5, connected to the carriage 2. The die D<SP>1</SP> may be opened by turning back the upper part as at 57a, Fig. 8, may contain oil chambers 85 and passages 65, Fig. 9, and may carry an adjustable deflector 90 with adjustable or spring-pressed side guides for the sheet 13. The slot of the die D<SP>2</SP> is bounded by two flexible strips 137, 138, Figs. 5 and 8, dovetailed to upper and lower flexible strips 136 which are adjustably connected, by a number of screw sockets 125 and ball joints, to rods 117 ... 120 and 139 ... 142. The lower rods 117 &c. may be each fixed to a C- shaped frame 113 ... 116, in the upper parts of which slide the rods 139 &c. These are each connected to its frame by a toggle 147 which can be straightened, to close the slot to its correct width after insertion of the sheet 13, by bars 151 and a hydraulic piston. Each frame 113 &c. is moved vertically on a crossslide 30 by a roller 154 mounted on its rod 117  &c. running on an adjustable cam-track 16 ... 19 connected to and moved by the carriage 2, thus altering the shape of the die-slot D<SP>2</SP> as the sheet is pulled through it. In a modification, the frames 113 &c. are omitted, the lower rods 117 &c., Fig. 20, are actuated by the tracks 16 &c. and the upper rods 139 &c. are mounted in a beam 185 movable vertically on the slide 30 by toggles 173 &c., and are each pressed down by a spring 187 against the upper surface of the sheet 13. In a simpler construction, the rods 117 &c. are adjustably fixed in the frame 30 and the rods 139 &c. are adjustably fixed in the beam 185. The slide 30 may be moved laterally during the operation by an adjustable cam track 182, Fig. 11, engaging rollers 181 mounted on the slide. The drag on the sheet 13 may be increased by a gripper applying a backward pull thereto, by making the slot in the die D<SP>1</SP> sinuous, or by deflecting the sheet by an adjustable bar 90, Fig. 9. This may carry adjustable guide blocks 91 to engage the edges of the sheet or, if the sheet varies in width, the blocks 193, Fig. 14, may be connected by a cable 194 passing over pulleys 197 biassed by springs to press the blocks towards the centre. The die D<SP>2</SP> may have a slot which bends the sheet first in one direction at 211, Fig. 22, and then in the other at 212. The parts which perform these bends may be integral or separate and in this case may be adjustably fixed or movable relatively, either by separate cam tracks or each track 158, Fig. 33, may move a part of the die a directly through a roller 154 and a rod 192 and a part of the die b through the roller 154, lever 202 and a rod 192a. The dies shown in this Figure have five working edges. Making boats.-Examples, including a boat hull, of forms which can be thus produced are shown.