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Wan-Sup Cheung, Sang-Myong Park
Progress in development of primary angular vibration calibration systems

The angular vibration calibration system is not well established even in most of NMI’s. Moreover, it is not certain that suppliers of angular vibration pickups have well maintained the traceability of their calibration systems, unlike the linear vibration calibration systems well established in the industrial sector. This paper points out several technical issues encountered in setting up the angular vibration calibration system in KRISS. The first was to develop a new angular vibration exciter that is not commercialized yet. The angular vibration calibration system can not do without the angular vibration generation apparatus. The multi-layered PCB manufacturing technology is exploited to make the rotating coil designed to generate the Lorenz force. The first prototype model of the angular vibration exciter built up in KRISS is illustrated in this paper. It is shown to meet the requirements of the amplitude stability, the total harmonic distortion, and the hum and noise components, recommended in Clause ISO16063-15. Furthermore, it is shown the measured frequency responses that it can generate angular vibration over the frequency range of 5 Hz to 1 kHz (or more). Main features of the angle prism based interferometer set up in KRISS are addressed. Three uncertainty components are introduced and their evaluated uncertainty contribution is demonstrated. Those results are very useful to judge the measurement capability of the angle prism based interferometer.

Akihiro Oota, Takashi Usuda, Hideaki Nozato, Tamio Ishigami, Hisayuki Aoyama, Katsuhisa Kudo
Development of primary calibration system for high frequency range up to 10 kHz

In this paper, a new primary calibration system for the frequency range from 5 kHz to 10 kHz at the National Metrology Institute of Japan (NMIJ) is reported. In the high frequency range, the displacement amplitude becomes small and the effects of parasitic motion, such as drift motion and external noise, become greater with increasing frequency. Therefore, the realization of the primary calibration system becomes difficult. The new primary calibration system for the high frequency range is implemented with a newly designed laser interferometer and a new signal processing algorithm, which is named the multiple sinusoidal approximation method. The new designed laser interferometer has a twofold optical path to detect a small displacement with high accuracy, as well as a flexible alignment mechanism for the measurement position. The multiple sinusoidal approximation method can correct the effect of parasitic motion, which leads to high accuracy acceleration measurement. As a result, the new primary calibration system has realized a calibration capability within an expanded uncertainty of 0.5%.

Park Yon-Kyu, K. Min-Seok, K. Jong-Ho, C. Jae-Hyuk, K. Dae-Im
Establishment of torque standards in KRISS of Korea

Korea Research Institute of Standards and Science(KRISS) has developed a 100 N·m and a 2 kN·m deadweight torque standard machines. The 100 N·m torque machine can generate torque from 0.1 N·m to 110 N·m. The length of its torque arm is 0.25 m for both sides. It uses continuous deadweight stack. At each side, it has three different deadweight stacks. By rotating the base plate on which the deadweight stacks are located, the machine can adjust a suitable deadweight stack of appropriate torque range. Its relative uncertainty is 5 × 10-4 from 0.1 N·m to 1 N·m and 5 × 10-5 from 1 N·m to 110 N·m. The 2 kN·m deadweight torque machine uses a continuous deadweight stack at the left side and a binary type combination deadweight stack at the right side. By combining both deadweight stacks, the machine can generate torque from 10 N·m to 2200 N·m for both clockwise and counter-clockwise directions. The machine fixes its torque arm when changing the torque to maintain previous torque level. Its relative expanded uncertainty is 5 × 10-5.

D. Röske
The New version of the German torque calibration standard DIN 51309:2005-12 a comparative overview

In December 2005, the new version of the DIN 51309 was issued by DIN, the German Institute for Standardization. This standard takes into account some fundamental ideas about the target application of a torque transducer, for example high-level inter-comparison measurements or measurements in industrial environments. Two cases are considered and two different calibration results are calculated on the basis of a standard calibration procedure. For some intercomparisons, the hysteresis of the transducer does not have any influence on the result and is therefore excluded. This paper shows, on the one hand, the new version in comparison with other standards (e. g. EA-10/14) and some guidelines of the DKD, the German Calibration Service, and describes, on the other hand, its application to torque reference machines.

S. Kuhn
Advantage of carrier frecquency in contactles high precision torque measurement systems

This paper describes the advantage of carrier frequency amplifiers in rotating torque flanges. It gives an overview of the systematic effects and random errors which disturb the torque measurement and shows how the measurement errors can be suppressed by means of carrier frequency technology. The resulting high reproducibility and linearity of the new torque flange with digital signal processing and transmission is shown in torque and temperature plots.

K. Ohgushi, A. Nishino, T. OTA, K. Ueda
Expansion of the calibration range and improvement of the uncertainty in the 1 kN·m deadweight torque standard machine

Expansion of the calibration range and improvement of the uncertainty of realized torque in the 1 kN·m deadweight torque standard machine were investigated. The lower limit of the calibration range was lowered from 5 N·m to 0.5 N·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 = 2) of 7.3 × 10-5 and 2.9 × 10-5 could be obtained in the range from 0.5 N·m to 20 N·m and from 5 N·m to 1 kN·m, respectively.

A. Brüge
Mathematical representation of reference torque transducers in partial-range regimes

Investigations with regard to the mathematical description of reference torque transducers used in comparison calibration facilities are described. A method is presented which uses only the direct loading calibration data of a torque transducer in the full range in order to calculate its behaviour in any reasonable partial range. Examinations of typical reference torque transducers demonstrate how to find transducers which are qualified for this calculation method and provide estimations of the possible effects on the measurement uncertainty caused by the calculation of the partial-range behaviour.

P. Averlant, A. Gosset
Development of the new LNE 50 N·m deadweight torque standard machine

This paper describes the new LNE 50 N·m deadweight torque standard machine. Informations on the design, development, and commissioning of this standard are given. Its design is described focusing on mechanical and metrological characteristics in particular of the structure, the deadweight, the air bearing and the lever arm.

L. C. Cabral-de Freitas, S. R. Reis-da Costa, R. Soares-de Oliveira, C. A. Koch
The torque metrology management in Brazil

In 2001, in order to improve the confidence level and the accuracy of the torque calibration systems in Brazil, the Force, Torque and Hardness Laboratory (Lafor/Inmetro) acquired a Torque Primary Standard Machine from 20 N·m up to 3000 N·m of nominal range, in clockwise and in anti-clockwise, where it was qualified by PTB/Germany in 2004. Since them, some steps have been done to disseminate the improved torque results to the users. The present work has the objective to demonstrate how Inmetro/Lafor is preparing to manage the torque metrology in Brazil due to the best measurement capabilities obtained and the increasing of the demand by the accredited laboratories and industries which are upgrading their torque equipment in order to get better uncertainties together with decreasing measurement costs.

T. Licht, S. E. Salboel
Primary vibration calibration by laser interferometry and mechanical shortcomings

Primary vibration calibration by laser interferometry using quadrature outputs has been used for the last 10-15 years. The ISO 16063-11 was published in 1999 and this has increased the interest further.
With new compact laser interferometers the difficulties of optical alignment and adjustment has been practically eliminated and dedicated software has made the process automatic, permitting to gather much more data.
Furthermore the advancement in electronic measurement capabilities, especially in high precision A/D converters, has made the electrical parts of the error budget very small.
Therefore today the dominating error sources are of mechanical nature. The problem that the laser beam not always can be directed towards the point or surface to which it ideally should be directed, introduces errors that can be quite significant and often will dominate the final error budget.
At low frequencies this is often due to non-ideal exciter motion, at high frequencies due to relative motion between points on apparently rigid mechanical structures. The ISO standards and other published material do not treat these problems in detail; only very general comments are given.
To help the calibration laboratories to a better understanding and agreement of uncertainties some practical examples, finite element modelling and corresponding measurements will be given. Examples of solutions to these problems including uncertainty calculations will be presented.

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