CONTROL DEVICE FOR NUMBER OF HOISTED STEEL PLATE BY HOISTING ELECTROMAGNET

摘要

PURPOSE:To surely adsorb and hoist the specified number of steel plates without being affected by the presence of regularities on the steel plate surface and the scale stuck on the surface by adjusting the value of the current fed to an exciting coil in response to the detected magnetic flux. CONSTITUTION:When the magnetic resistance is changed by irregularities on the steel plate surface and the scale stuck on the surface, the detected magnetic flux outputted by a magnetic flux detecting means 13 is changed, thus the current fed to an exciting coil 12 is automatically adjusted to compensate the change quantity. Multiple current detecting means 180 and 190 with different detection characteristics from each other are provided, and a hoist control means 110 switches the selection of the voltage outputted by a voltage converting means 120 and switches multiple current detecting means 180 and 190 in response to the quantity of the load indicated by a hoist supporting means 100 and the magnitude of the reference exciting current or the detected current. The detection range of the current detecting means 180 or 190 used is switched in response to the switching of the variable range of the current corresponding to the switching of the voltage, thus the detected error is reduced.