GB610406A - Improved lattice forming and welding machine - Google Patents

Abstract

610,406. Making lattice girders. BRITISH FEDERAL WELDER & MACHINE CO., Ltd., and TRIBE, T. F. April 3, 1946, No. 10252. [Classes 83 (ii) and 83 (iv)] Straightening; corrugating ; welding.-A machine for making lattice girders by bending and welding comprises a feed table for feeding bar stock continuously in predetermined lengths, a bending apparatus for bending the stock to zig-zag form, a feed table for feeding bar stock to form the flanges and a number of welding machines initially adjustable by manual means and thereafter operable automatically in synchronism to weld the flanges to a number of opposed crests of the lattice element. The general arrangement of the parts is as described in Specification 610,404, which describes also the construction of the spinner, straightener and the bending apparatus is particularly described in Specification 610,405. The stock is fed by a feed table and passes through bending apparatus and after a length is bent the feed table operates to feed another length and also the bent length to four welding machines W<SP>1</SP>, W<SP>2</SP>, W<SP>3</SP>, W 4 , arranged in staggered relation along the line of feed, and the feed table at the same time feeding the flange stock to the welding machines to weld two or four crests simultaneously to the flanges. In the second alternative, welding occurs to alternate cycles of operation. The lattice element and flange bars are passed over guides 47, mounted in a framework 62 to the welding machines. In making a box girder, a frame 64 supported by the frame 62 has a pair of guide rollers 65 which are laterally adjustable, and two complete lattices are arranged vertically and a lattice element 50 positioned horizontally and passed through the welding electrodes. The figure is then inverted and the final element then welded. The machines are each adjustable laterally on rails by screws 48 and longitudinally by hand wheels 49 to accommodate girders of different pitch and depth. Each welding machine has a fixed head 52 provided with an arm 74 carrying a fixed electrode engaging the outside of the flange 4 and connected to one terminal of a transformer, and a movable electrode 79 grooved and tapered to engage the inside of the crest of the lattice element and carried by a movable head 51 connected to the other terminal of the transformer. The head 51 is formed with an arm 84 having short axles 86 guided in projecting arms 88 secured to the head 52, and the arm 84 terminating in a forked pivot 85 pinned at 95 to the screwed extension of a piston-rod 81 moved rearwardly by air pressure to effect the weld. The forked pivot 85 has depending extensions 89 slotted at 90 to embrace slidable pins 91 and pressed forwards by a spring 92. When air is released from the cylinder, the head is moved to the right by the spring 92, the axles 86 moving in the guides 87 until they reach the chamfered end 93, whereupon they fall clear and the head swings on pivot 85 out of the path of the lattice element during the next feed motion. The welding current is switched on automatically.