Patent GB-282806-A (GB)
Title: Improvements in and relating to welding of rails
IPC: B23K31/00
Filed: 1927-12-28
Abstract: 282,806. Stedefeld, G. Dec. 27, 1926, [Convention date]. Welding railway rails.-In repairing or renewing rails in welded rail tracks without expansion joints, the longitudinal movement of the rail required during welding which corresponds with the shortening of the rail by welding, is obtained by lateral deflection of the rail in the plane of least bending resistance, the length of rail set frea for bending and the amount of deflection being such that the highest stress in the rail is below the elastic limit. One rail 2 is fixed and the other rail 1 overlaps its end by an amount 3 equal to the shortening due to welding. and is fixed at 5, the intermediate portion being freed from its clamps. The length of the rail 1 which is to be freed and the amount of lateral deflection at P, the centre of the freed length, required to take up the overlap, are determined by calculation. The rail 1, which passes through guide rails 4, is then laterally deflected at P to take up the overlap and welding is then performed by connecting the rails to the jaws of an electric-welding apparatus and applying pressure P in the reverse direction together with a longitudinal pressure R applied near the joint. The joint faces after short contact are moved apart about 2 m.ms. then again brought into contact and then moved apart again and so forth until welding heat is obtained whereupon the joint is completed by end pressure. The overlap may occur normally or may be produced by pushing the ends of the rails towards one another, or, when, as in winter, the temperature is below that at which the rail is free from tension, by heating the rails on one or both sides of the joint by flames or electrically.. The pressure members may be actuated mechanically, electrically or hydraulically. With small cross-sections they may be operated by hand, a second member being in some cases used to obtain end pressure. In Fig. 7, one rail 8 is. secured in a frame 7 by jaws 13, Fig. 11, operated by hand through screws 12 and worm gear 10, 11. Guides 15, Fig. 9, screwed to the rail 14 have projections to engage rollers on a lever 20 operated by an hydraulic cylinder 6 through a link 21 to. produce the end pressure. The guides slide over rollers 16 bearing against removable bars 22 in the frame, one of the bars being tapered to facilitate insertion. The deflecting is effected by an hydraulic cylinder 25, Fig. 14, secured to sleepers and coupled to the cylinder 6, the piston operating through a link 27 and forked member 28. reaction being taken by the second rail through the sleepers. The welding jaws are secured to the rails, insulation being inserted between the rail 8 and the jaws 13. The end pressure cylinder 39, Fig. 15, and the deflecting cylinder 41, may be controlled by a piston 35 operated by a handlever 34 and sliding in a movable control sleeve 31 connected by a lever 47 to the piston rod 46. Each position of the hand lever corresponds to a definite position of the rail. When the piston 35 is pushed forward fluid from the inlet passes into, the chamber 33 and through ports 36 and pipe 38 into the cylinder 39 to produce the end pressure. Fluid also passes out through the pipe 40 into the cylinder 41. The pipe 40 has an excess pressure throttle valve 48 so as to delay admission of pressure to the cylinder 41 in order to avoid intermediate bends. This valve is held down by an adjustable spring 52, Fig. 16, and raised by pressure supplied to the chambers 49, 50. Towards the end of the movement of the piston 44, the control sleeve 31 moves over the piston 35 to close the ports 36. When the piston 35 is moved to its other position the fluid passes through pipe 53 into the cylinder 41 to effect the deflection of the rail, and also through pipe 54 with excess pressure throttle valve 48 into the cylinder 39. Exhaust from rear end of cylinder 39 and lover end of cylinder 41 passes through pipes 55, 42 having check valves 43. The cylinders may be single-acting, Fig. 17, the exhaust from both cylinders taking place either direct or through adjustable excess pressure valves 59 to act as brakes and avoid intermediate bends. The valves are gradually relieved by their load and finally lifted by pistons 61 through springs 60. In both cases a proportional indication of the abutment pressure may be felt at the operating end of the hand lever 34 or 6 by arranging a cylinder 62 on the control sleeve connected by pipes 63 or 64 to the cylinder ends 65 or 66. In a further form the end pressure may be effected hydraulically and the deflection by spring or weight. Loaded springs 80, Fig. 20, are arranged between crossheads 83 and covers 82 in a slotted cylinder 81 which is enclosed in a casing 87 secured to the sleepers. To the cross-heads are pivoted links 86, which are also jointed together and to a link 85 provided with the deflecting member 89, so that the bending force continually increases with increase of deflection. To the ends of rods 90 secured to the cross-heads are attached tubes 91 provided with forked members 97. To these members are pivoted links 94 which are provided with blocks slidable in slots in U-shaped members 92 secured to carriers 101 screwed to the sleepers. Links 93 are pivoted to the members 92 and are jointed at 98 to the links 94 and also to links 99 carrying the deflecting members 100. One of these side deflecting members is arranged on each side of the central member at “ span from the ends of the rail, the links being half the length of the centre links. Intermediate bends are thus avoided.