| 摘要 |
PURPOSE:To improve the accuracy of a welded pipe of titanium, etc. and to prevent the wear of a roll by distributing an outer-diametral drawing rate to each roll while limiting the total drawing rate, from squeezing rolls to the final rolls of sizing, to the range of specified percentage. CONSTITUTION:A hoop 1 of titanium, etc. is formed into an open pipe after passing through forming rolls F1-F7, and a preparation work for welding is controlled by squeezing rolls SQ. A welded pipe welded in its longitudinal direction by a torch 2 of TIG welding, is passed through four stages of rolls F8-F11 having a cahiber with true roundness and is finished into the desired outer- diametral tolerance and out of roundness. At that time, when the total outer- diametral drawing rate, ranging from the squeezing rolls SQ to the final rolls F11 of sizing, is limited to 1-2%, and is distributed to each roll; the required accuracy of the out of roundness, etc. is obtained, and also the wear of roll due to excessive drawing rate is prevented. |
