FEEDBACK CONTROL SWITCHING DEVICE IN ELECTRIC HYDRAULIC SERVO-MATERIAL TESTING MACHINE

摘要

PURPOSE:To switch automatically a feedback control by correcting a ratio of two detecting signals and a target value by an adding means, so as to hold a detecting signal of pressure piece, when a detecting signal of a load becomes a prescribed value. CONSTITUTION:A displacement of a pressure piece in an electric hydraulic servo-material testing machine is detected by a detecting means 1, a load is detected by a detecting means 2, and by adding both of them, a feedback signal for controlling a servo-valve is obtained. In this case, it is detected by a detecting means 5 that a signal of the detecting means 2 becomes a prescribed value, and in accordance with it, a value of a signal the detecting means 1 of that time is stored in a storage means 6. In this state, at every prescribed time, the stored value is compared with the signal from the detecting means 1, a ratio of two detecting signals and a target value 4 are corrected, and a feedback signal is outputted. Accordingly, a shock applied to the material is minimized and switching of an electric hydraulic servo-mechanism to a load state from pressure can be executed.