Patent GB-910664-A (GB)
Title: Forming apparatus for forming metal plate and sheet
IPC: B21D5/02
Filed: 1961-02-06
Abstract: 910,664. Making tubes; angular bending. LAKE ERIE MACHINERY CORPORATION. Feb. 6, 1961 [Feb. 15, 1960], No. 4356/61. Classes 83 (2) and 83 (4). Forming apparatus for forming metal plate and sheet workpieces comprises a frame in which a pair of forming aprons is mounted each having parts arranged in face to face relation on opposite sides of a plane which includes a single forming axis about which the workpiece is to be deformed, and also including parts having working surfaces parallel with and adjacent to said axis, a clamping ram movable on said frame along said plane toward and from said working surfaces in opposed relation thereto, a mandrel carried by said clamping ram and having an exterior forming portion arranged to be brought into concentric relation with said forming axis by the movement of said clamping ram, supporting pivot means on said frame concentric with said forming axis at opposite ends of said aprons, and an adjustable connection supporting each apron on said supporting pivot means for independent adjustment of each of said working surfaces relative to said forming axis and relative to each other to form a workpiece having surfaces contacted by said working surfaces at different distances from said forming axis. The frame of the apparatus comprises a pair of end columns 30 connected by upper and lower beams 32 and 31 respectively. Bosses 46, 48 on each column 30 carry the main pivot pins 49 of the brake, said pins supporting front and rear aprons 51a and 51 which co-operate with the clamping ram 53 to bend a metal plate 55 to the desired form. The clamping ram 53 is moved into and out of engagement with the workpiece on the aprons 51, 51a by means of hydraulic or pneumatic cylinders 66 actuating toggle mechanism 70 and 84. The pivot 76 of the bell-crank lever 70 is adjustable vertically to set the clamping ram in its working position by a screw 80 rotated by bevel gears and sprocket mechanism actuated by a handle 90. The workpiece is engaged by a mandrel 120 removably secured to the bottom of the ram 53. Each apron 51, 51a is independently pivoted on the main pivot pins 49 and also independently adjustable toward and from the forming axis by screws 138, Fig. 9, rotatably mounted on pins 139. The screws are adjusted by a handle 164 through sprocket mechanism and gearing on a shaft 156, and the angular position of each screw is determined by graduations 149 on a flange 148. A scale 151 on a bar 150 attached to each nut 130 indicates the position of the aprons which are swung independently of each other by hydraulic cylinders 169a, Fig. 1. The front apron 51a carries a pair of spaced forwardly-projecting bars 176 on which is slidably mounted an adjustable spring-loaded stop 183 which accurately positions the plate or sheet in the brake. For repeated operation of the brake in the production of indentical forms, each apron has to be individually stopped at the required angular position so that the operator has only to place the workpiece against the stops 183, clamp the workpiece against the aprons 51, 51a and by the mandrel 120 and start the operation of the aprons which stop automatically when the workpiece is bent to the required form. The apron stop mechanism comprises a wire 191 fixed to each apron, Figs. 10 and 11, and to a vertically reciprocating rod 194 carrying a weight 196. A sleeve 198 is adjustably clamped on the rod 194 according to a scale 206 and each sleeve carries a cam 209 which operates an electric switch controlling the hydraulic cylinders which actuate the apron. Hydraulic and electric systems for operating the brake are fully described in the Specification. The brake is used for forming a closed tube, as shown in Fig. 21. In this embodiment the brake is used for completing the bend 293, Fig. 20, to bring the flanges 290 and 294 into contact to close the tube. In another embodiment a flange of single-ply thickness is formed on a body of two-ply material, Fig. 23. A double radius bend can be formed in a metal sheet by using a mandrel 281, Fig. 25. A metal plate having different thicknesses 306, 308 can be bent, as shown in Fig. 27, using a mandrel 284.