INVESTIGATION OF A NEW 1 MN FORCE CALIBRATION MACHINE OF TWIN CYLINDER DESIGN

Abstract: Three new force calibration machines covering the range from 1 kN to 1 MN has been designed and constructed at DM-SIC in Bogotá, Columbia. The 1 MN force calibration machine (fcm) is a reference force calibration machine of new design. A special flexible sealed twin piston cylinder system with rotating cylinders has been used for the generation of hydraulic forces to reduce the friction, oil losses and pressure drops in the hydraulic system. Time optimization and a high accuracy of force control could be achieved by a three-step combination of rapid preliminary positioning, a PI controller algorithm and, finally, a change-over to PID controller characteristics. The relative deviations between the measurements carried out at PTB and the final measurements performed in the 1 MN reference force calibration machine show that the fcm fulfils the predetermined overall specifications limits of relative uncertainty < 2⋅10-4 in the whole working range from 40 kN to 1 MN