1 INVESTIGATIONS ON TRANSDUCERS FOR TRANSFER OR REFERENCE IN CONTINUOUS TORQUE CALIBRATION

The highest level of torque calibration is achieved by direct loading and, due to the use of mass stacks, is associated with the step-by-step method. In order to fit the demand of applications especially in industry, calibration devices with the ability of performing continuous loading were developed which are working as reference machines. A benefit of continuous methods is that the time for a loading-unloading cycle can be ten times or more shorter than using the step method. This fast change in torque leads to conditions of use that cannot be represented in the national torque standards. Therefore the appointed reference- and transfer-transducers should have negligible sensitivity to fast loading effects. With such transducers the results of slow absolute calibrations in the national torque standards are valid also in the fast continuous-working machines. In Germany a guideline treating this problems of continuous calibration is in preparation at a working group of the German Calibration Service (DKD). In this guideline special qualification-tests are proposed which can be performed in existing direct loading machines and which can deliver information about the suitability of transducers as reference or transfer for continuous working machines. In this paper we describe these qualification-tests, discuss the results of the tests in comparison to the behaviour of the tested transducers in continuous measurements and recommendations for the selection of transducers for continuous use are given