| 摘要 |
<p>In the manufacture of welded pipes, edge buckling or waving of the strip (1) is prevented by heating. In one method, during the process for bending the strip (1) into a tubular form (10), the edges (7) of the strip (1) are heated so that tensile stress exerted thereon is reduced to a minimum and, thereafter, before the edges (7) are abutted against each other, the strip is wholly heated so that the compressive stress exerted on the edges is reduced to a minimum. According to another mode, during the process for bending the strip (1) gradually into a tubular form (10) or during the process in which the edges (7) of the strip are held in abutment against each other, the strip except its portions of the edges (7) is substantially or partially heated so that the strip except its portions of the edges is subjected to compressive stress while the portions of the edges are subjected to tensile stress, and under these conditions the edges are welded together.</p> |
