| 摘要 |
This invention concerns a method and an apparatus for making a spirally-wound tube from a hollow thermoplastic profile ( 1 ) having a substantially rectangular cross-section, which method comprises the steps of: winding the thermoplastic profile ( 1 ) around a drum ( 2 ) and joining adjacent loops together by welding, and smoothing the outer weld joint ( 13 ) by means of extra heat and a smoothing body resting against the weld joint ( 13 ). The invention is characterized in that the thermoplastic profile ( 1 ), when fed to the drum ( 2 ), comes onto a stationary first section ( 3 ) comprising spaced sliding means ( 5 ) arranged along the periphery, on which section welding is performed, after which an inner weld joint ( 11 ) thus formed is arranged to run along a spiral groove ( 14 ) running around the stationary first section ( 3 ), whereby the inner weld joint ( 11 ), as well as the outer weld joint ( 13 ), are treated by using extra heat and a stationary smoothing body ( 10 ) resting against it, and that the tube, once both of the welded surfaces ( 11, 13 ) have been smoothed, is transferred to a rotary driven drum section ( 4 ) causing the tube to rotate and generating the winding motion of the thermoplastic profile ( 1 ).
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