UME force standard machines, 11 kN and 110 kN dead-weight and 1.1 MN lever amplification, were installed into UME Force Laboratory in 1995. During commissioning of these machines in 1995 and 1997, two intecomparison measurements were realized between UME and PTB. Uncertainty level was 2 x 10 -5 for dead-weight machines and is 1 x 10 -4 for lever amplification machine. Marmara Earthquake influenced the force standard machines in August 1999. The epicentre of earthquake is 30 km to UME. Some connection points, welded parts and position of mass stacks were affected from this earthquake. After...
In traditional calibration, we must use a torque standard machine which measuring range is larger than that of the calibrated torque transducer. With the rapidly development of power machinery, its torque has been larger than 100 kN·m now, but it is difficult to establish corresponding torque standard machine in so large range. We developed a similarity method in calibrating those super-large range clamping ring type torque transducer in 30 kN·m torque standard machine. Testing a series of specimens with same method, similarity in geometry, time and kinetic, but in different similarity...
Due to their extremely compact and short design and extremely high torsional stiffness, the so-called torque flanges based on strain gage technology are the most up-to-date devices used for in-line torque measurement in power test stands. The optimum transfer of the measurand torque into the shaft line is an important factor for a correct measurement of torque. Due to the compact and stiff design of the torque flanges some basic points must be taken into account. This paper describes specific factors affecting the measurement uncertainty and their reasons. It includes recommendations on how...
In the metrology of the mechanical quantities of force and torque, standard machines are used that allow these components to be generated in a given direction. For force in most cases this is the vertical, for torque both the horizontal or the vertical directions are in use. In contrast to this realization, for some applications it is necessary to generate forces or moments in arbitrary directions. Moreover, the standard machines generate only one main component and in addition small disturbing components. But it is often desired to have a superposition of forces and moments without a main...
A new design of strain-gauge torque transducer has been developed which is hermetically sealed and especially suitable for low nominal torque capacities. Apart from high basic repeatability, the major design aim was a high degree of insensitivity to parasitic forces and moments. In order to fulfil both requirements, a sensing element shaped as an elastic hinge was chosen. Theoretical considerations and measuring results confirm the characteristics which were aimed to be achieved. The particular design and the metrological performance make the new sensor ideally suited for applications as...
The uncertainty of each component in the developed deadweight torque standard machine of rated capacity 1 kN·m has been evaluated at the National Metrological Institute of Japan (NMIJ). For estimating Best Measurement Capability, the following evaluations had remained: actual moment-arm length during torque calibration, influence of measurement axis misalignment due to the coupling condition. Therefore, the actual moment-arm length was estimated by measuring the temperature distribution of the moment-arm in the environment of the torque calibration room. In addition, the length variation of...
Comparison measurements between a standard and a test object may be performed and evaluated by various sequences of measurement cycles in repetition. It is understood that from each cycle a single measurement result and from the total number of them a mean and an uncertainty are evaluated. Consecutive cycles may have independent data or a certain number of common data. When evaluating of the measurement uncertainty of the mean, cycles with common data have to be considered as correlated and corresponding procedures have to be observed, which differ from the statistical procedure for a number...
Calibrating weight sets creates some unique challenges to the metrologist. Performance and reliability of the calibration oppose its productivity. A calibration of a weight set, also called a dissemination, requires manual interventions by the operator, even if it is performed on a mass comparator with a turntable. Sometimes, a comparator does not offer enough room to accommodate an entire group of weights; then the use of custom auxiliary weights may be required. Besides, the threat of confounding weights is omnipresent. Recently, a new generation of computer controlled comparators,...
On weight calibrations one by one there is not a way to check about the validity of the founded values on calibration due to systematic errors (p.e. a possible mass deviation of the mass standard used). The present work proposes a way to check the mass values of the calibration that would support calibration decisions, especially for the secondary labs.
As measurement instrument the weighing instrument has a very good measurement accuracy compared to some other measurements in processes. To know the characters of the weighing instrument the user must be able to evaluate it. The calibration is one method to show this working capacity of weighing instruments. The user must be able to define the values for permissible error of indication as well as the needed uncertainty of the calibration. The practice has shown that in the most cases it is adequate to indicate these values as scale intervals and it is as well a very pragmatic way to estimate...