| 摘要 |
<p>A powder-filled welded steel tube has a tube wall (1) with a welded longitudinal seam (6) and is wound into a coil for despatch. To reduce the risk that the seam opens when the tube is twisted, e.g. on uncoiling, the tube wall is provided with a continuous longitudinal groove (5). Preferably the groove (5) is symmetrical and directed radially inwards. In the continuous manufacture of such tube, a metal strip is formed into an open channel, powder is introduced into the channel, the channel is closed and the edges welded to form a closed tube. The diameter is then reduced and the finished product is coiled. The longitudinal groove (5) is rolled in continuously during the diameter reduction of the powder-filled welded tube.</p> |
