AIR VENT APPARATUS OF ROLL BENDER CYLINDER WHICH JUDGES PENETRATION OF OIL OR AIR

摘要

PURPOSE: To provide an air vent apparatus of roll bender cylinder which is capable of automatically judging penetration of oil or air although its amount is small and completely discharging air or water penetrated without stopping of rolling operation. CONSTITUTION: The air vent apparatus comprises a valve (19) for pullback for supplying oil to one side of the roll bender cylinder (24) according to operation signal of air vent; a valve (14) for air vent for discharging oil from the other side of the roll bender cylinder to tank according to the operation signal of the air vent; the air vent starting judgement part (12) for instructing starting of automatic air vent if the deviation between pressure detection values and the set pressure value is a critical value or more by checking deviation between a set pressure (1) of the roll bender cylinder and actual pressure values; deviation maximum value detection parts (7,8) for detecting when the deviation reaches +/- maximum values by receiving deviation between a set pressure value of the roll bender cylinder and pressure measured values according to instructions of the air vent starting judgement part; a hunting detection part (9) for judging whether hunting is generated or not in the roll bender cylinder from the +/- maximum deviation values detected in the deviation maximum value detection parts; a hunting counting part (10) for outputting air vent operation signal if a set hunting detection number or more is counted by counting the number of hunting detection in the hunting detection part; a valve output part (11) for operating the valves by impressing a preset valve output value to the valve for pullback and the valve for air vent if an air vent operation signal is inputted from the hunting counting part; and a holding part (16) for maintaining servo valve (17) of the roll bender cylinder to the present state until air venting is completed if the air vent operation signal is outputted from the hunting counting part.