DETERMINATION OF FORCES FROM 10 N UP TO 250 kN USING TWO FULL AUTOMATICAL DEAD WEIGHT MACHINES DEVELOPED BY THE BEV

摘要

The Austrian national metrology institute, the Federal Office of Metrology and Surveying (BEV) developed and realised in 2008 an automatic dead weight machine to determine small forces in the range of 1 μN -10N with a special construction that allows to measure continuously from 10 N tensions to 10 N compressions. It makes possible to cover the complete range without changing the mounting of the force transducer under calibration. After the successful establishment of this equipment, the BEV started in 2010 together with the Institute of Production Engineering (IFT) of the Vienna University of Technology to realise another dead weight force machine in the range of 5 N - 2 kN based on the same technique. This machine also allows to measure continuously in 10N steps over the whole range from tension to compression without changing the mounting of the force transducer. To cover the higher range of force in addition to the previously described ones, a dead weight standard machine based on the conventional technique (separated measurements for tension and for compression) in the range of 50 N - 250 kN was built. This machine is also capable using a hydraulic amplification to cover the range of 1MN and 5MN. All dead weight machines allow controlling each and every weight separately. They have special designed beam balance constructions to compensate the weight of the suspension system. Due to the precise determination of the position of the balance beams using laser, the systems are able to compensate the deformation of the force transducer under stress. The usage of this compensation is drastically improving the reproducibility of the systems. A further advantage of these machines is that their constructions enable the periodic recalibration of the weights without changing the adjustment of the dead weight machine. All the systems were finished at the end of the year 2011. According the schedule first internal and then bilateral international comparisons will be carried out from summer of 2012 to validate the performance of the machines.