| 摘要 |
PURPOSE:To eliminate a slip between a pipe stock and a roller by comparing current values of a driving motor before and after an end of the pipe stock passed a forming stand bites to the next forming stand, and thereby setting up a rotational speed of the driving motor. CONSTITUTION:Until an end of a material 3 to be worked is bitten by the second forming stand 11, current values of a driving motor 4 detected by a current detector 8 of the first forming stand 10 is memorized by a speed control unit 6. As soon as a detector 9 detects the biting of the stand 11 the control unit 6 compares current values before and after the biting and by changing the speed of the driving motor 4 of the stand 11, controls current values of the motor 4 of the stand 10 so that they return to the previous value before the biting. The similar control operation is repeated on the third forming stand 12 so as to make a condition not sustaining effects of biting for each stand. In consequence, the speed control unit for the pipe forming mill capable of eliminating the slip between the material to be worked and the roller is obtained.
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