Patent GB-565582-A (GB)
Title: Improvements in and relating to machines for bending metal
IPC: B21D7/04
Filed: 1943-05-11
Abstract: 565,582. Angular bending. BRIGGS MANUFACTURING CO. May 11, 1943, No. 7463. Convention date, June 25, 1942. [Class 83 (iv)] Metal strip, such as of flat, angle,. channel, T- or Z-section, is bent in the plane of the strip by gripping the strip at longitudinally spaced points, moving it bodily in a given direction and bending it over a curved former while clamping it against the former progressively along the length of the strip and moving the leading end at a greater lineal rate of speed than that of the trailing end. The strip is thus stretched progressively, to a variable extent from the outer to the inner edge during bending so as to avoid the formation of wrinkles and eliminate compressive strains in the fibres. The front end of a T-shaped strip C is secured to one end of curved former B traversed in a curved path and the tail end is secured to the rear of a slide 22 mounted on a slide 23 traversed in a rectilinear path tangential to the curved path of the former. The slide 22 carries a hydraulic pump 60 communicating by pipes with a series of cylinders 65 on the slide 23 so as to operate pistons 66 to move the slide 22 laterally towards or from the work so as to apply pressure thereto at its point of engagement with the former B. To the front wall of the slide 22 is bolted a pressure plate 26 having a face which is gradually tapered from its rear to its front end to engage a similarly shaped face on the former so that flange of the strip has an inclined shape progressively imparted thereto as it is fed forwards and progressively wrapped on the former. The clamp at the rear end of the slide 22 comprises a block 27 with a tapered cavity 31 containing a pair of serrated wedge-shaped clamping blocks 30 operated by a clamping member 32 through bolts 33. The former 35 is provided at the position beyond the end of the member 26 in the initial position of the parts with a clamp consisting of a block 39 with an inclined wall co-operating with a pair of serrated wedge blocks 44 engaging respectively a recess 43 in the former and a recess 42 in the block 40 mounted in a notched portion thereof. The clamp block 39 is secured to the parts 35, 40 by bolts 41. An end plate 45 is used to hold the blocks 44 in position. The rest of the operative face of the former is cut away to receive a strip 36 which is bolted thereto and has a recess 38 to receive the web of the strip. To the back of the former is secured by pins 49 a pair of chains 47, 48 which engage a pair of sprockets 50, 50a mounted on a driven shaft 54 and engaging a thrust bearing ring 53. The slide 23 is driven by a rack 56 and pinion 57 on a driven shaft 58. The shafts 54, 58 are driven through reducing gearing 72, 73 and chains 74, 75 from a variable speed mechanism 76 so as to rotate the shaft 54 at a greater speed than the shaft 58. The differential speeds of these shafts may be changed at will. To facilitate determination of the proper relative positions of the slide and former at the starting point, the member 26 may be provided with a gauge having a tooth fitting in a notch in the member 36.