| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent local decrease in the thickness of a tube stock which is rolled with a mandrel mill. <P>SOLUTION: In the mandrel mill provided with a plurality of roll stands having a pair of grooved rolls opposing each other, the thickness of the tube stock in the direction of the final screw-down in the position of the outlet side of the final roll stand and/or the 90°direction to the direction of the final screw-down are measured with thickness measuring instruments and, when the measured value is smaller than a calculated value by comparing the measured value with the calculated thickness value with a comparing means, rolling reduction of a roll stand at which the reduction is performed in the same direction of screw-down as the measuring direction in the upstream before at least two stages of the final roll stand is decreased through a control section. By this invention, the local decrease in the thickness of the tube stock which is rolled with the mandrel mill is surely prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
