In this research we discuss behaviors of a high speed mass measurement system with conveyor belt (a checkweigher). The objective of this paper is a proposal of a simple dynamic model of the system. The dynamics of the checkweigher with Electro-Magnetic Force Compensation (simply called EMFC) can be approximated by a mass-springdamper system as a physical model, and an equation of motion is derived. Model parameters can be estimated from the experimental data. Then, comparisons of the simulation results with the realistic responses are carried out. Finally, effects of floor vibration on the...
Over the last period, increasing attention has been paid to measurement of small forces which play a more important role in nanotechnology and other significant areas such as MEMS (Micro-Electro-Mechanical Systems). In this respect, the development of mass standards and measurement techniques below the current limit of 1 milligram is vital to provide traceability to the SI for such measurements. The lowest traceable force realized by a deadweight standard machine is typically around the level of 1 N. The national measurement institutes (NMIs), motivated by the need for small force standards,...
A new technology demonstrated by an innovative measuring instrument is presented. This instrument is conceived to measure the dynamic torque in shafts and rotating mechanical elements. The present paper describes the instrument layout, a laboratory prototype recently developed and the results of the first tests performed on the prototype in order to study its capabilities.
For the dynamic calibration of torque transducers, a model of the transducer and an extended model of the mounted transducer with the measuring device have been developed. The dynamic behaviour of a torque transducer is described by model parameters. This paper describes the model with the known and unknown parameters and how the calibration measurements are going to be carried out. The principle for the identification of the transducer’s model parameters from measurement data is described using a least squares approach.
For different types of click-torque wrenches, measurement uncertainty contributions of typical calibration conditions were investigated. Procedures which differ from those given in ISO 6789 were suggested for transfer measurements at calibration facilities for click-torque wrenches in order to improve their reproducibility. Examinations were carried out for influences like lever length, rise time, temperature and humidity.
There are many computer software packages available for the calculation of measurement uncertainties. Some are free and open source, but many are not free to use or are restricted to non-commercial use. Not in all cases, however, is it necessary or advisable to purchase and learn to use a more or less fully featured software package. Some simple calculations can be done using free spreadsheet software contained in LibreOffice or OpenOffice. Also, MS Excel is often already available on the PC. In some other cases the calculations are not simple, especially when the partial derivatives of the...
In October 2009, the members of the German DKD Torque Committee (FA 10) agreed to carry out a comparison of torque calibrations according to the German torque calibration standard DIN 51309:2005-12 in the range from 20 N · m to 200 N · m using very stable torque transducers as travelling standards. The pilot laboratory was the torque working group at PTB. Thirteen accredited laboratories from Germany, together with another German laboratory without accreditation and an Austrian laboratory, participated in this comparison. All measurements were carried out in 2010 and 2011, and the first...
This paper describes one of the uncertainty contributions which can be derived from sinusoidal force measurements. These measurements are based on the application of a scanning vibrometer and the use of triaxial accelerometers. The measuring of many acceleration points on the top mass of the transducer makes it possible to obtain acceleration distributions from which a standard deviation can be derived; the triaxial accelerometer allow the observance of certain effects, like rocking modes, or other problems related to specific excitation frequencies of the force transducer. Both measurements...
In this contribution, a compression-torsion sensor with a low and reproducible crosstalk behaviour will be presented. This sensor type was especially developed to investigate the characteristics of a measuring machine designed for the calibration of friction coefficient sensors. The measurement range for this build-up compressiontorsion sensor lies at a maximum torque of 500 N·m and a nominal force of 500 kN. The results with regard to the calibration on individual components ( F z and M z ) and the signal crosstalk have been investigated and shall now be presented.
Centro Español de Metrología (CEM) is developing a completely new torque 10 kN·m deadweight standard machine. This new torque standard machine operates in a working range up to 10 kN·m, clockwise and anti-clockwise. The designed machine, actually under construction, consists of a torque arm, an air bearing, two concentric sets of weight stacks, a main body and a control system that will be able to operate it almost fully automatically.