| 摘要 |
<p>The apparatus comprises a heating device (2) for the tubular thermoplastic elements (1a, 1b) to be welded together and a supporting device (3) arranged in the tubular elements (1a, 1b). The supporting device (3) has an expandable bubble (4), which is provided in its interior (8) with an electric heating element (9) and a fluid (10) which expands when heated. …<??>During heating by means of electric power, the bubble (4) comes to bear against the inner contour of the ends to be welded of the tubular elements (1a, 1b), the bearing of the bubble (4) during the welding operation avoiding the formation of a welding bead and producing a welding pressure. …<??>Once welding has been carried out, the shrunken bubble (4) is withdrawn by means of the drawrod (11). …<IMAGE>… </p> |
