| 摘要 |
<p>PURPOSE:To securely detect the momentary plate breakage of the belt-like metal plate without any malfunction by detecting the variation quantity of the armature current of a driving electric motor and rolling speed exceeding permissible maximum values and no belt-like metal plate being present by a preximity switch. CONSTITUTION:If the belt-like metal plate 2a breaks on the side of a payoff reel 1 about a mill work roll 3, the rotating speed of the reel 1 decreases and when the metal plate breaks on the side of a tension reel 5, the rotating speed increases to output signals corresponding to momentary variations of armature currents of driving electric motors 6A and 6B to outputs 11A and 11B. When those signals exceed the set permissible maximum current variation value, logic values showing tension variation are outputted 12A and 12B. Further, a rolling speed which causes momentary abnormality is detected 7A and 7B from the rotating speed of a deflector roll 4 and when their difference exceeds the permissible maximum rolling speed value, a logic value showing the abnormality is outputted 15. Further, plural proximity switches 9A and 9B detect the absence of the metal plate 2a and output logic values indicating the occurrence of the plate breakage. A logic circuit 17 ORs those values and outputs a signal indicating the plate breakage.</p> |
