Expansion of the calibration range and improvement of the uncertainty in the 1 kN(centre dot)m deadweight torque standard machine

摘要

Expansion of the calibration range and improvement of the uncertainty of realized torque in the 1 kN(centre dot)m deadweight torque standard machine were investigated. The lower limit of the calibration range was lowered from 5 N(centre dot)m to 0.5 N(centre dot)m by developing new small linkage weight series. In addition, the sensitivity limit at the fulcrum was reevaluated. The moment-arm length was also re-measured after changing the thin metal bands at the ends of the moment-arm. As a result of these evaluations, relative expanded uncertainties (k velence 2) of 7.3 X 10~(-5) and 2.9 X 10~(-5) could be obtained in the range from 0.5 N(centre dot)m to 20 N(centre dot)m and from 5 N(centre dot)m to 1 kN(centre dot)m, respectively.