| 摘要 |
Welding apparatus for plastic lining (5) in concrete tubing (4) comprises a centering carriage (6) movable inside the tubing along its length and fixable in position at a location adjacent a butt joint (51) having a seam to be welded. A carrier arm (10) is mounted for rotation about an axis (9) coincident with the axis of the tubing (4) for supporting a welding unit (14) at its outer end remote from the axis of the tubing. A drive source (15, 16) adjacent the welding unit engages the interior of the tubing and self propells the welding unit (14) and carrier arm (10) around the interior of the tubing (4). The welding unit (14) is biased outwardly towards the wall of the tubing and is guided along the welding seam by either a guide ring (21) or a roller (20) engaging a gap (48) between adjacent tubing sections. Several degrees of freedom are provided for accommodating lack of concentricity and translation of the welding unit along the length of the tubing without moving the centering carriage. |
