9762 papers found
MPA NRW realized a new concept for the calibration of the velocity of the impact body of Leeb hardness testers according to the standards DIN 50156, ISO/DIS 16859 and ASTM A 956. A laser vibrometer is used for the continuous measurement of velocity andtime. The measuring device enables the calibration of theimpact velocity of all types of Leeb hardness testers available on the market.
To quantitatively determine the tip radius of spherical and conical indenters, a practical non-contact radius measurement system is presented. Realizationof the optical system has been detailed, including its theoretical and actual resolution and error sources. For the purpose of experimental investigation of the performance of the nonimaging radius measurement system, a sapphire sphere with a nominal radius of 200 µm has been employed. Detai led data analysis indicates that high-order form error of the object under test might be one of the key error sources within the calibration setup.
Rebound hardness is a popular onsite testing method to evaluate the hardness of heavy and massive metal parts and products. However, such rebound testers are sometimes wrongly applied to small specimens that do not have enough mass. In such a case, impact energy is partly “leaked” through the vibration of the specimen and this leads to a lowered and wrong value of the coefficient of restitution. This phenomenon is called a “mass effect” and it is mainly caused by a heavy impact body mounted with a diamond or cemented carbide tip indenter. In 1987, Nakamura and Maki et al. developed a new...
The main purpose of the paper is to outline the essential properties, principal classes and most widely used principles / methods / approaches typical for the modern instrumentation in the area of electrical measurement of force and related quantities (such as torque, pressure, strain, vibration). For beginning, the concepts of sensor and transducer are clarified, emphasizing that the sensor is the element being influenced by the measurand, while the transducer is usually a more complex device performing the input-output conversion. A general classification of the electrical methods for...
In this paper, a calibration device for silk screen tension meter is designed. The device has a measurement range from 5 to 100 N/cm. It can achieve simultaneous loading in x and y directions by servo motors. For loading accuracy, two high precisionforce sensors are utilized in the closed-loop control system for each direction. To verify the device, it is utilized to calibrate a commercial available silk screen tension meter. The results from the device are compared with that from the Swiss Federal Office of Metrology. It demonstrates that the max error is 0.5 %.
The calibration of heavy mass standards is a difficult, demanding, and time consuming process. Loading and unloading of heavy mass standards is strenuous work as well as placing of the weights in the center of the weighing position by human. A high capacity automatic comparator with readability of 0.1 mg has become available in National Institute of Metrology (NIM). Performance analysis of this mass comparator is shown in the paper.
This paper outlines a design of 20 kN·m deadweight torque standard machine to be commissioned by 2015 at KRISS. The torque machine incorporates newest technologies for user-friendliness and lower calibration uncertainties, such as an aerostatic bearing of double-cone type, a counter-drive with low backlash, and an individually controlled weighing system.
The necessity of making a new transfer standard was proposed to disseminate of mass scale during or after establishing new definition of kilogram unit. It is worthy to find new material or perfect surface characterization of mass transfer standard. It should be confirmed whether a material is suitable to use as a standard after much chemical or mechanical analysis of its surface. In this presentation, we would like to present the first plan for development project of new transfer standard materials.
To realize volume measurement of weights from 2 kg to 20 kg, three hydrostatic methods from annex B.7.4 of OIML R111-1 are described in this paper. Equipment with regard to volume measurement of weights from 2 kg to 20 kg having three operation procedures is designed and developed on the basis of three hydrostatic methods at National Institute of Metrology (NIM) in China. The equipment consists of robot arm for transferring weights, liquid bath, mass comparator, glass housing, two weight exchangers, two weight holders and controller . The equipment will enable to finish automatically...
The unit of mass, the kilogram, is the last of the seven base units of the International System of Units (SI) to be defined in terms of a material artefact rather than by relation to an invariant of nature. Progress is being made towards a redefinition in terms of the Planck constant ( h ), realised via the watt balance and Avogadro experiments. This paper describes the results of investigations to develop mass standards compatible with use in vacuum, and methods for the transfer, storage and cleaning of these standards in order to satisfactorily implement and disseminate the kilogram...