GB832271A - Improvements in or relating to electric resistance welding machines - Google Patents

Abstract

832,271. Welding by pressure. RESISTANCE WELDERS Ltd. June 11, 1958 [June 21, 1957], No. 19678/57. Class 83 (4). In an electric resistance welding machine for welding lengths of rail, the clamping means 32, 33 for gripping the rail lengths include lower clamping members and upper clamping members movable vertically relatively to the lower members, the machine frame being movable bodily such that the lower clamping members move upwardly and downwardly without movement relative to the frame. In an embodiment a frame 10, Figs. 1, 3, is supported by pairs of rollers 11, 12 at its ends on rails 13 and is movable along the rails by a piston and cylinder device 16, 14. The rollers 12 are mounted eccentrically on a shaft 21 so that rocking of the frame about the rollers 11 is caused by rotation of the shaft effected by a piston and cylinder device 23, 24 coupled to an arm 22 fixed to the shaft. An electric motor-driven pump 28 draws liquid from a tank 31 and supplies it to the cylinders 14, 24. Clamp unit 32 is fixed to the frame and clamp unit 33 is carried on a movable head on the frame, the jaws of the units being movable by fluid pressure. With the shaft 21 rotated to lower the frame, Fig. 1, and the jaws open, the rail 37 last welded is moved to the left and a new rail 38 is fed from the right to meet the length 37. The frame is then moved to bring the meeting ends between the clamp, the shaft is rotated to raise the frame, the jaws are closed, Fig. 3, and welding is effected. The arm 22 may be connected to the piston-rod of a substantially vertical compressed air cylinder, the arrangement being such that as the piston is raised to cause lowering of the frame it engages a stem in the cylinder which moves to compress a spring to assist in taking the weight of the frame. The frame alternatively has at one end a shaft 51, Fig. 6, rotatable in blocks 52 on the floor and is supported at the other end by leaf springs 53. A toggle link 54 is connected to a block 55 on the floor and another link 56 is connected to the frame, the common point 58 of the links being connected to a piston-rod 59 of a liquid or air pressure cylinder 61 on the frame. Movement of the piston effects rocking of the frame.