Patent GB-1435500-A (GB)
Title: Machine for use in the welding of a pipe to a pipe-end fitting
IPC: B23K9/028
Filed: 1972-07-20
Abstract: 1435500 Welding by fusion; grinding ROLLSROYCE (1971) Ltd 26 July 1973 [20 July 1972] 33901/72 Headings B3R and B3D [Also in Division F2] A machine for circumferentially welding together a pipe 68 and a pipe end fitting 55 comprises relatively movable carriages respectively for supporting the pipe, the end fitting and a rotary welding head. The machine comprises a frame 12, a lower carriage 25 slidably mounted on the frame for horizontal movement parallel to the frame front, a welding head carriage 31 and a grinding wheel carriage 71 each slidably mounted on the carriage 25 for horizontal movement normal to the frame front, a lower workpiece table 51 vertically slidably mounted on the carriage 31, and an upper workpiece table 61 vertically slidably mounted on the frame 12. A TIG rotary welding head 36 is mounted on the top of the carriage 31 via mutually perpendicular dovetail slides along which it is manually screw adjustable, for horizontal head movements parallel and normal to the frame front. The head comprises an electrode 44 mounted on a split ring 45 in turn mounted in a split housing (48, 49) held together by pivotable screw assemblies (82). The ring 45 has gear teeth by which it is rotated by an infinitely variable speed motor 91 via a transmission 92, and has holes 93 through which shielding gas is fed from a conduit (not shown). Pivoted gas shrouds 87-90 are provided to enclose the weld zone. Welding current is fed to the head by brush means (not shown). The lower workpiece table 51 is vertically air-movable to a position manually adjustable by a screw stop 60 and has fixed thereto a collet, clamp or, as shown, selfcentering chuck 54 for the pipe end fitting 55. Shielding gas is fed to the workpiece interior via a flexible pipe 57. The upper workpiece table 61 is vertically movable, via counterbalancing linkage, by a lever 66, and supports one or more pipe clamps 64 which are secured to the table at alternative poisitions, by dowels and screws 67, 70. The grinding wheel carriage 71 supports a grinding wheel 73 which is driven by an air motor 76 and is manually vertically adjustable at 75. Air-engaged, spring-released brake means (Fig. 5, not shown) (see Division F2) are provided to station the carriages 25, 31, 71 and the table 61. Air power for these brakes, for raising the table 51, and for the grinding wheel motor is controlled by six on/off valves on a front panel 123. The shielding gas may be inert, e.g. argon, or, for stainless steel, an inert/hydrogen mixture. Rotary speed and number of revolutions of the electrode, welding current, and shielding gas flow is programmed. In operation, (i) the pipe 68 is secured in the clamp 64 approximately coaxially with the head 36, (ii) the fitting 55 is secured in the chuck 54 which is then air raised until the stop 60 abuts a portion (83) of the carriage 31, (iii) the stop 60 is then adjusted to bring the fitting end face coplanar with the rotational plane of the electrode 44, (iv) the head 36 is screw adjusted into coaxial alignment with the fitting, such alignment being checked visually or by a graticulefitted microscope, (v) the carriage 25 is leftwardly moved to bring the grinding wheel 74 below the end face of the pipe 68, (vi) the table 61 is lowered, by the lever 66, to bring the pipe end face slightly above the grinding wheel, (vii) the motor 76 is started and the carriage 71 is manually reciprocated whilst the grinding wheel is raised in small increments to grind the end face of the pipe, (viii) the table 61 is raised, (ix) the carriage 25 is rightwardly moved to bring the head 36 below the pipe 68, (x) the pipe 68 and fitting 55 are coaxially aligned by interposition of a steel ball therebetween by relative adjustment of the carriage 25 and the carriage 31 and table 61 until the ball seats within the ends of the pipe and the fitting, (xi) the table 61 is raised, the ball removed and the table 61 lowered again to abut the pipe and fitting, (xii) the shrouds 87-90 are engaged, and (xiii) the welding is carried out. The split construction of the welding head also enables it to weld a ring (such as a gas turbine fuel manifold ring) to a pipe.