| 摘要 |
A holder (20) presents the stud (22) to the workpiece (24) approaching it (24) axially (26). Protective gas (40) is supplied along the stud and removed in a second, axially opposite direction. In new design, a resilient, folding annular bellows (52) completes a welding chamber sealing it off from the exterior during welding. The arrangement confines the protective gas so that it can only escape in the second, axial direction. The mouthpiece (12) is used as a supportive base. Its body (32) defines an interior with a first opening facing the workpiece and a second opening facing away at the rear. The holder is arranged inside to present the stud at the front of the mouthpiece. The sealing bellows is fitted to the mouthpiece, such that in a neutral position it is relaxed and projects beyond it. In the welding position, it rests against the workpiece. The bellows is attached at the front (54) of the mouthpiece, or onto its outer casing. The bellows surrounds an area of the workpiece which exceeds the area of the mouthpiece opening. Further information concerning use of a mask and bush are provided, together with details of seal construction. The bellows includes an edge making an assured planar contact with the workpiece. |
