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Page 491 of 977 Results 4901 - 4910 of 9762

S. Nattapon, S. Tassanai
A COMPARISON OF PURELY STATIC AND CONTINUOUS TORQUE CALIBRATION PROCEDURE

This paper presents the results of calibration procedure comparison in pure torque measurement with a synchronous system between the purely static (step-by-step) and continuous (quasi-static) facilities in order to prove the influence of the procedural conditions on the uncertainty of calibration. The filter setting (Low pass Bessel: 0.2 Hz, 1.25 Hz, 5 Hz and 10 Hz) and speed of applying torque (≈ 0.7 % of full scale/sec to ≈ 2.8% of full scale/sec) were varied to examine the effects of both parameters on the measurement results and to optimize the continuous procedure. The measurement was made by a torque calibration machine (TCM) with a reference torque transducer and the HBM MGCplus amplifier system using a comparison method.
The results of this experiment show the deviation between the purely static and continuous procedure within ± 0.01% of reading that was enough for class 0.2 torque measuring devices (DIN 51309) and torque transfer wrench (DAkkS-DKD-R 3-7) calibration. For the step-by-step measurement, the duration time in each torque step (form applying torque to data record) must be adequate for steady state of filter setting. For the continuous measurement, the speed of applying torque and filter setting should be optimized for best measurement capability.

M. Kühnel, M. Rivero, C. Diethold, F. Hilbrunner, T. Fröhlich
PRECISE TILTMETER AND INCLINOMETER BASED ON COMMERCIAL FORCE COMPENSATION WEIGH CELLS

High precision measurements and monitoring of tilt or inclination are essential in the field of ultraprecise force and mass measurements. We present a new concept for high resolving tilt / inclination measurements. Therefore a commercial electromagnetic force compensation (EMC) weigh cell is mounted in a hanging position and loaded with a defined weight. Thus the system conforms to a pendulum. By measuring the tilt depended deflection of the pendulum with the position sensor of the weigh cell we achieved a standard deviation of 7.1 nrad (3.4 nrad filtered) within a sampling time of 15 min. In future investigations we will compensate the deflection and take the compensation force as a measure for the tilt.

C. Diethold, S. Vasilijan, T. Fröhlich
LORENTZ FORCE VELOCIMETRY USING ELECTROMAGNETIC FORCE COMPENSATED LOAD CELLS

This paper discusses the flow rate measurement of poorly conducting fluids (such as electrolytes) using Lorentz force velocimetry (short: LFV). The Lorentz force caused by the moving electrolytes is in the range of micronewton. This tiny Lorentz force is determined using a high resolution force measurement systems based on electromagnetic force compensated (short: EMC) load cells.
In this paper the force measurement system, the principle of LFV and the environmental influences on this kind of force measurement system are described.

David Kimetto
REALISATION OF THE UNIT OF FORCE AND DISSEMINATION IN KENYA

This paper highlights how the S.I unit of force (newton) is realized in the Kenya Bureau of Standards Force Laboratory. The use of the 1 MN Multi-Lever Force Standard Machine. The dissemination of the unit (N) in the organization (KEBS) and in the Kenyan industry. Calculation of uncertainty of measurement.

K. Ogushi, A. Nishino, K. Maeda, K. Ueda
CALIBRATION CHAIN FOR HAND TORQUE SCREWDRIVERS

Hand torque screwdrivers are used for the fastening control of screws in almost all precise mechanical and electrical parts. This paper describes the realization of a calibration chain for hand torque screwdrivers traceable to the national standard for torque. The calibration methods for a reference torque screwdriver using a primary torque standard machine, a torque screwdriver tester using the reference torque screwdriver, and hand torque screwdrivers using the torque screwdriver tester are also described.

Tassanai Sanponpute, Nittaya Arksonnarong
TEMPERATURE AND HUMIDITY DEPENDENCE ON STABILITY OF TORQUE MEASURING DEVICES

Effect of temperature and humidity on torque measuring devices were studied.With the aim to estimate measurement uncertainties due to environmental varying conditions, torque transfer wrenches and transducers were carried out by the measurement in an environmental controlled chamber under conditions of range 16°C to 31°C and 35%RH to 65%RH. The measurement responses from two kind of amplifiers, alternating current and direct current excitation amplifier were taken into account as well. The temperature sensitivity was significantly minimized causing by temperature compensation circuit. Moreover, the humidity sensitivities from several kinds of torque device structure consisted of directly contact to ambient, covering protection, waterproof protection and hermetically sealed seem to be similar and cannot be distinguished. On the other hand, amount of humidity sensitivity obtained by using direct current excitation amplifier are smaller than using alternating current excitation amplifier.

Wirun Laopornpichayanuwat, Rungsiya Sukhon, Tosapon Pangviwate, Monchai Mitaree
ROUGHNESS EFFECT ON STABILITIES OF STANDARD WEIGHTS CLASS E

The stability of the mass of a weight is highly dependent on the surface structures of the weight. In this research, the data have been collected more than 10 years in order to study the trend in changing values of the conventional mass of the standard weight of 1 g to 1 kg class E1 and E2 by controlling the environment of the storage room for these standard weights. The resulting values are assessed to determine the relationship between the conventional mass when it is changing by time. The mean height of roughness profile (Ra) and maximum height of roughness profile (Rz) are determined at the begin and the end of this experiment. Which at the beginning of the experiment, the two values are within specification of OIML R 111-1. These two values are measured by applying a Mirau interferometer (MI) is composed of interference microscope with mirau objectives and light emitting diodes (LEDs) that provide white light over several µm and a vertical scanning interferometry (VSI). At the same time, the uncertainty values are reported. The drifting trend of the conventional mass value over time is quite constant when the values of Ra and Rz are within the specification of OIML R 111-1. Whereas, the drifting trend of conventional mass value is moving up or moving down when the roughness of the surface is out of specification.

R. Högström, K. Riski, M. Ojanen, M. Heinonen
ATOMIC FORCE MICROSCOPY STUDY ON THE EFFECT OF LOW-PRESSURE HYDROGEN PLASMA CLEANING ON STAINLESS STEEL WEIGHTS

Despite the new definition of the Kilogram, physical weights prone to contamination will still be used in the dissemination of the unit. Cleaning is applied to bring the weight surface to a well-defined state to allow predictable adsorption behaviour. Currently used mechanical cleaning methods show poor reproducibility. Therefore, non-contact cleaning techniques such as plasma cleaning have been introduced. In this study, the applicability of low-pressure hydrogen plasma for cleaning stainless steel weights was studied using atomic force microscopy (AFM) and gravimetric weighing. Results show that hydrogen plasma effectively removes surface contamination without damaging the surface. Successive ultrasonic cleaning in ethanol did not considerably reduce surface contamination.

Tang Chunqian, A Germak, Li Qingzhong, F Mazzoleni, Tang Yun, Xu Yinjie
FORCE INTER-COMPARISON BETWEEN CHINA AND ITALY

The paper descriptes the inter-comparison of two force primary standards of 1 MN DWMs established by National Institute of Measurement and Testing Technology (NIMTT), Chengdu, China, and Istituto Nazionale di Ricerca Metrologica(INRIM), Torino, Italy. It was tested that the temperature coefficients of the two cells as transfer standard, and their long-term stability. There were results on the deviation of force generated by the two DWMs as well as their normalized error.

Yao Jinhui , Li Qingzhong/Presenter, Xu Hang, Chi Hui, Lin jianhui, Li Haigen
DESIGN OF 60 MN BUILD-UP FORCE STANDARD MACHINE

The paper describes a design of the 60 MN build-up force standard machine(60 MNBM), which would be established by Fujian Province Institute of Metrology, Fuzhou, China, at the end of 2014. The design has covered 1) mainspecifications; 2) main construction; 3) Finite Element Analysis (FEA) of key units; 4) uncertainty evaluation of the force generated, etc.
The 60 MNBM will generate vertical load of (4 ... 60) MN, as well as lateral load of (120 ... 2000) kN. The machine is employed to calibrate and test force transducers, load-boxes, hydraulic jacks, plastic supports, etc. The machine isdivided into two parts, of which one part is used to generate reference load as a calibration machine, the other one is used as a normal testing machine to test the force apparatus as mentioned above.

Page 491 of 977 Results 4901 - 4910 of 9762