APPARATUS AND METHOD FOR SEALING COLLARS OF DOUBLE-WALL BELLOWS AND DOUBLE-WALL BELLOWS SO OBTAINED THAT CAN BE FITTED WITH CRACK MONITORING

摘要

Method in which a continuous butt-sealed rim of a collar defined by corresponding concentric ends, without undulations, of a first wall, radially innermost, and a second wall, radially outermost, of a double-wall bellows is obtained as a continuous butt-weld bead on the corresponding rims, arranged radially adjacent to each other, of the ends of the first and second walls, which have been prepared such that, before welding, they are radially spaced apart from each other by not more than 0.3 mm and with the rim of the second wall that projects in an axial direction with respect to that of the first wall for a length of 0.2-0.4 mm; butt welding is performed with a laser beam directed parallel to an axis of symmetry of the collar, making the latter rotate around the axis to progressively expose the entire perimeter of the rims of the ends of the first and second walls, simultaneously pressing the rims against each other with a force between 1 and 3 kg via spring clamping rollers.