682,222. Making well-centring devices. BAKER OIL TOOLS, Inc. Dec. 27, 1950, No. 31428/50. Classes 83 (ii) and 83 (iv). Welding. - A method of making a well casing centring device comprises mounting a number of circumferentially-spaced centring elements with their end portions adjacent a collar member and forming a continuous weld around said member and along the end portions of said centring elements while jointly rotating said member and centring elements to weld the end of said elements to said member. The centring device A (Fig. 11) is mounted on a well casing string B disposed in a well bore and comprises upper and lower spaced collars 10, 11 to which are welded outwardly-bowed leaf springs 12. A stop collar 15 or 16 is disposed longitudinally outwardly of each collar member to which it is attached by circumferentially-spaced tiemembers 17. The stop collars co-operate with lugs 18 welded to the casing B for facilitating the entry and removal of the centring device from the well bore. According to the invention the components of the centring device are mounted on a member C (Fig. 1) of a welding-machine, the member being rotated to enable a continuous weld 14 to be run around each collar 10, 11 to weld the springs 12 to the collars. The member 3 is secured to a horizontal driveshaft 21 carried in bearings 22 supported on the base 24 of the machine and is rotated by a motor and gear reducer 25. The welding apparatus D is mounted on a carriage 31 supported by rollers 32 on a track 29 and a welding rod 20 from a reel 33 is fed to the work-piece by a feeding device 34. A hopper 37 delivers flux to the weld through a tube 38 regulated by a valve 39. The member C comprises a head 40 secured to the drive-shaft 21, the head being attached to a hollow .drive-shaft 42 which is supported at its end remote from the head 40 by rollers on a support 45 pivoted to the machine base 24. The support 45 may be swung to the dotted line position in Fig. 1 to enable the centralizer components to be assembled on the member C. The shaft 42 carries a pair of opposed expander members 52, 53 having outer disc portions 55, 65 for locating the stop collars 15, 16. The inner portion 57, 66 of each expander member is frusto-conical and co-operates with a number of circumferentially arranged wedges 59, engaging the inner surface of the collars 10, 11. The large ends of the wedges engage a thrust-plate 63, 70 secured to sleeves 64 and 83, respectively, mounted on the shaft 42. Movement of the wedges is effected by a shaft 72 extending within the shaft 42 and rotatable in a head 73 secured within the end of the shaft 42. The shaft 72 has a threaded portion 75 at its inner end which engages a nut 76. A number of cap screws 77 are threaded into the nut and extend through slots 78 in the shaft 42 and through holes 79 in the sleeve 64. The shaft 72 is also rotatable within a sleeve 80 disposed within the shaft 42 to which a number of cap screws 81 are secured, such screws extending through slots 82 in the shaft 42 and holes in the sleeve 71. Collars 84 fixed to the shaft 42 on each side of the sleeve 80 prevent relative longitudinal movement between the sleeve and the shaft 42. An abutment plate 86, having a transverse slot 87 to enable it to be moved endwise over the shaft 42, is held against the stop collar 16 by a clamp nut 88. In operation, the spring collars 10, 11 to which have been spot-welded the tie members 17 attached to the stop collars 15, 16 are arranged in the machine so that recesses 13 in the collars 10, 11 are aligned to receive the ends of the outwardly-bowed leaf-springs 12, any longitudinal adjustment being made by rotating the clamp nut 88, and the shaft 72 is then rotated to wedge the segments 59, 69 within the collars. The leaf-springs are retained in position by coilsprings 95 held in position by a hook 96. The assembly is then rotated and a welding bead 14 formed around each collar to weld the ends of the springs to the collars. Excess flux is collected in a bin 97 below the member C. In a modified form of the member C (Fig. 7) the wedges for clamping the spring collars are operated by transversely moving a number of wedges 100, 101 between head members 102, 103 mounted on the abutment sleeves 64a, 71a, respectively. One wedge 101 is threaded to receive a bolt 105 extending through slots 106 in the shaft 42. Rotation of the bolt forces the sleeves apart to operate the wedges for clamping the collars. In a further modification (Fig. 8), the wedges are operated by fluid pressure. The thrust-plates 63a, 70a are mounted on the shaft 42a and have sealing-rings 110 and 113, respectively. A sleeve 114 is welded to the thrustplate 63a and is slidable over a piston-ring 115 on the thrust-plate 70a. Air pressure is introduced into the space 117 through a valve 118 to urge the thrust-plates away from each other to operate the wedges. The air pressure may also be released through the valve 118.