Apparatus for forming a circumferential weld

Claim 1

Apparatus for forming a circumferential weld in a circumferential groove on a cylindrical member disposed at a predetermined position within said apparatus, said apparatus comprising: a plurality of A-frame structures; a bridge disposed between said A-frame structures; a welding head for laying a weld bead in said circumferential groove; means for rotating said cylindrical member about its longitudinal axis; means for moving said welding head horizontally in a plane generally parallel to a plane passing through said circumferential groove, said means for moving the welding head horizontally in a plane generally parallel to a plane passing through said circumferential groove comprises a first bar rigidly mounted on the bridge and a second bar rigidly mounted on said bridge and generally parallel to said first bar, said bars being disposed in a plane forming an acute angle with said plane passing through the circumferential groove, means for sliding said welding head longitudinally along said bars and means for locking said weld head in any longitudinal position with respect to said bars; means for moving said welding head vertically in a plane generally parallel to a plane passing through said circumferential groove; means for moving said welding head horizontally in a plane generally perpendicular to a plane passing through said circumferential groove; and, a probe which is disposed to run in said circumferential groove and respond to vertical and horizontal variations in the circumferential groove to signal the means for moving said welding head vertically and to move said welding head horizontally in a plane perpendicular to a plane passing through said circumferential groove to compensate for variations in said groove and said cylindrical member to automatically provide a high circumferential weld.