| 摘要 |
PURPOSE:To remove fins by nonuse of crop cutting and to prevent a yield drop of tubes by installing plural grooved rolls on one plane in the final rolling stand and collapsing fins at the tube end generated during rolling. CONSTITUTION:Grooved rolls 12 are symmetrically arranged to the sectional center of a tube 2 and on one plane in the final rolling stand or at the outlet side of the stand of a mandrel mill. The grooved rolls 12 are composed of our rolls such as upper and lower main rolls 10 and upper and lower side rolls 11. The hole dia. of the rolls 12 is set to an outer finishing dia. of the tube 2. When the rear end fin is bitten, the projection of the fin is restricted by the main rolls 10 and is pushed toward the inside of the tube 2,which is rolled between the rolls 12 and a mandrel. By this mechanism, the manufacturing efficiency of the tube 2 is improved and generation of troubles caused by crop cutting is prevented.
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