PREVENTING DEVICE OF OVERLOAD OF MATERIAL TESTER

摘要

PURPOSE:To prevent the application of an overload on a material tester by a method wherein a second physical amount is compared with a prescribed threshold value and, based on a comparison output, it is prevented from varying beyond said threshold value in a mechanism for feedback control of a first physical amount of a testing body. CONSTITUTION:The displacement of the main body 4 of a tester is controlled by an oil hydraulic valve 13 operated by a servo amplifier 3, and a load is applied to a testing body 14 to conduct a material test. A deviation unit 11 subtracts an output E2 of a displacement sensor 5 from a set value E1 set by a displacement setter 1 and delivers an output thus obtained to the servo amplifier 3 for feedback control through the intermediary of a control amplifier 2 and an addition point 12. A load acting on the testing body 14 is measured by a load cell 7, compared with the upper and lower limits of a threshold level by comparators 9 and 10, and delivered to the addition point 12 when it exceeds prescribed limits. By this constitution, the load is prevented from exceeding the prescribed limits, and thus an overload is prevented.