GB929997A - Centering device for welding ends of pipe - Google Patents

Abstract

929,997. Welding by fusion. KRAFTANLAGEN A.G. Sept. 24, 1959 [Sept. 24, 1958; Aug. 5, 1959], No. 32498/59. Class 83 (4). A centring device for use in the buttwelding of pipes consists of two expandable clamps arranged to engage the inner surfaces of the pipes, one of the clamps being pivotally secured to the other. Each clamp has sectors 1, 5, Fig. 1, guided in channels 14, 15 and connected by links 2, 6 to pistons sliding in hydraulic cylinders 3, 7 respectively. A frame 25 carrying the channel 14 and secured to the cylinder 3 is universally pivoted to a frame 21 secured to the cylinder 7. The channel 15 which is slidably mounted on the cylinder 7 carries bolts 10 surrounded by springs 8 and engaging in the channel 14 to initially maintain the channels 14, 15 parallel. In operation, the right-hand clamp is inserted in the pipe 4 and pressure liquid is supplied to the cylinder 3 to force the sectors 1 against the pipe. Spacers consisting of steel strips radially movable relative to and mounted on the sectors 1 abut the end of the pipe 4. The pipe 11 is superposed over the left-hand clamp which is expanded. Further supply of pressure liquid to the cylinder 7 causes the clamps to move together until the pipe 11 abuts the spacers. After a root weld has been formed the cylinders 3, 7 are exhausted and the clamps are released by a compression spring 26. If desired the sectors may form an elliptical configuration for use in the process described in Specification 760,504. In a modification, the sectors 43, 44, Fig. 5, connected by links 51, 52 to the frames 53, 54 of the clamps are linked to nuts 50, 49 on oppositely threaded rods 46, 45, ball-jointed together and journalled in the frames 53, 54. Upon rotation of the rods 46, 45 manually or by an adjacent or remote electric motor, the sectors 43, 44 are extended until the latter engage the pipe 41. At the same time spacers 60 on arms 61 held by springs 62 against the sectors 41 are extended by links 63. The clamps are held parallel initially by springs 65 on bolts 64 passing through the frames 53, 54. After the pipe 42 is placed in position the sectors 44 are further extended by rotation of the rods 45, 46 which as the nut 50 is now fixed move axially against the action of a spring 66 to pull the pipes 41, 42 together. After the root weld has been made, reverse rotation of the rods 45, 46 releases the sectors 44. When a thrust bearing on the end of the rod 46 engages the frame 53 the spacers 60 and the sectors 43 are withdrawn. Alternatively, the spacers 60 may be hydraulically actuated and the aligning bolts 64 and springs 65 may be replaced by spring- loaded rods mounted in the sectors 44 and engaging the spacers 60. The spacers and sectors may also be actuated pneumatically or electromagnetically.