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Page 849 of 936 Results 8481 - 8490 of 9356

Cristiana Zanatta Viana, André Roberto de Sousa, Anésio Mariano Junior
STANDARDIZATION OF MEASUREMENT STRATEGIES IN COORDINATE METROLOGY IN THE AUTOMOTIVE SUPPLY CHAIN

The outsourcing in the automotive industry transferred the responsibility to produce products with quality to its supplier and, consequently, the definition and execution of the measurements in the supplied products. However, it is still frequent the occurrence of the conflicts between companies related to divergences in the dimensional tests. This problem is more critical in coordinate metrology, due to the many parameters in the measurement process. This paper describes a methodology developed for the standardization of measurement strategies to be used during the product development and its application in the supply chain of the Brazilian automotive industry.

Rigoberto Nava-Sandoval, Rufino Díaz-Uribe
OPTICAL POLYGON CALIBRATION USING ONLY ONE AUTOCOLLIMATOR

In this paper we present a new measuring method to obtain the angular variations of the faces of an optical polygon using only one autocollimator. The method requires additionally an external beam splitter to divide the light from autocollimator and a flat mirror for second autocollimator emulation. The method can be used for polygons of any number of faces. In this case we present calibration results of a twelve faces polygon.

P. Fernández, B.J. Álvarez, J.C. Rico, D. Blanco, G. Valiño
SCANNING OF FREE-FORM SURFACES BY USING A LASER-STRIPE SENSOR ON A CMM

This research presents a working methodology for developing an automatic planning system of the scanning process of free-form surfaces. The surface has been modelled using a STL format, that permits the automatic recognizing of any type of surface. This work does only consider collision-free orientations that guarantee the visibility of the zone to scan and that are compatible with the constraints imposed by the process parameters. To speed up the calculation of these orientations, different methods like back-face culling and space partitioning techniques, such as kd-trees, are applied. Once the space occupied by the part is partitioned in regions, recursive ray traversal algorithms are used in order to check for intersection exclusively the part triangles (STL) that can potentially be traversed by each laser beam direction.

Tomáš Radil, Jan Fischer
TWO-DIMENSIONAL POSITION MEASUREMENT OF OBJECTS WITH CIRCULAR CROSS-SECTION USING SINGLE LINEAR CCD SENSOR

This paper describes a novel method of twodimensional position measurement of objects with circular cross-section. The proposed method employs a single linear CCD sensor and two point light sources. Using this simple measuring set-up the described method achieves typical linearity deviations below 4.5 µm in the direction along the senor and 22 µm in the direction perpendicular to the sensor.

Yuri Chugui, Nikolai Yakovenko, Michael Yaluplin
FRESNEL MEASURING METHOD FOR DIMENSIONAL INSPECTION

Accuracy characterization of a Fresnel method for objects dimensions measurement in coherent and partially coherent light is investigated. The major sources of a systematic measurement error are estimated analytically including non-uniform illumination of the object, the interference effect of the diffraction object edge images, the integration properties of the linear multi-element photodetector, influence of extended size of partially coherent light source. Effective algorithms for account of basic error components and for increase accuracy in low measuring range are proposed. The obtained results are confirmed by experiments.

Andrea Magalini, David Vetturi
LASER INTERFEROMETRY FOR STRAIGHTNESS MEASUREMENTS IN A WEAKLY CONTROLLED ENVIRONMENT

Straightness measurements for the geometrical inspection of machining tools have been operated in a weakly controlled environment (concerning temperature, pressure, humidity and induced mechanical vibrations) with reference to industrial manufacturing departments.
Measurements have been performed by means of a Wollaston prism laser interferometer.
A first experimental characterization of this instrumentation has been operated by repeatability tests conducted in controlled and not controlled environments, considering different relative positions for the interferometer and the laser head. Then a calibration diagram has been constructed, assessing the accuracy and the instrumental uncertainty in the case of displacement measurements in a plane perpendicular to the laser beam direction.
In a second stage a suitable method has been developed to estimate the uncertainty level associated to straightness measures operated by the laser interferometric technique and also by traditional instrumentation, such as taut-wire and microscope and precision level. Measurement uncertainty is estimated by means of the Monte Carlo Method and according to standards.
Measures obtained by the laser interferometric method prove to be affected by higher levels of uncertainty than those coming from traditional approaches.

Alexandre Titov, Igor Malinovsky
ADVANCES AND NEW TECHNIQUES IN LENGTH MEASUREMENTS BY OPTICAL INTERFEROMETRY

Studies of a long gauge block Kösters interferometer, performed at INMETRO, and the results of the CIPM Key Comparison CCL-2 show that the uncertainty in realization of the SI length unit achieved with this type of instrument in the range of 500 mm is ~1 part in 108. Basic advances in philosophy and techniques of high-precision temperature measurements, realized in Brazil in the last few ears, permit to reduce crucially the uncertainty of length measurements by optical interferometry and to reach the Nanometrolgy regime in artifacts with nominal lengths above 100 mm. New measurement and calibration techniques give an opportunity to realize the temperature measurement of a particular point on the GB surface inside the interferometer with a total uncertainty below 0.1 mK, realizing the measurement without the contributions of the temperature gradient in the GB and velocity error. The demonstrated reproducibility in length measurements of 100-mm steel gauge block is at the level of 58 pm.

Olga B. Basun, Valery A. Granovsky, Mikhail D. Kudryavtsev
PRECISION SCALES OF PLANE ANGLE: PRINCIPLES AND METHODS OF CALIBRATION

Precision angular scales are considered from common point of view, and principles of their construction are formulated. Methods of mutual calibration of circular scales are developed to meet these principles taking into account the redundancy factor. Multidimensional classification of the methods is proposed. The family of designs is constructed, and relations of procedure parameters of a scale carrier calibration with required accuracy of the procedure results is established.

J. Sładek, R.Sitnik, M. Kupiec, P.Błaszczyk
THE NEW HYBRID METHOD FOR FAST AND PRECISION MEASUREMENT

In this article a new concept of a hybrid measurement method will be presented. The hybrid method is developed for fast and precise measurement especially for the automotive industry. It combines the high-speed of optical methods with the high-accuracy of CMMs measurement. A laboratory prototype of the system is described. Furthermore we present preliminary work on assessment of measurement uncertainty of the hybrid system based on the comparison of the results with CMM measurements.

José Sánchez, Sergio Padilla, J.M. Dorador
NEW FACILITIES OF VIRTUAL MACHINES: OPERATING MACHINES FROM CAD BROWSERS, FOR ANALYSIS

The main purpose of this paper is to show advances on the concept of virtual coordinate machines, already developed for aiding calibrating and teaching tasks. It is now possible to operate these machines directly from CAD browsers. No matter how distorted are the machines, it is possible to perform the analysis.

Page 849 of 936 Results 8481 - 8490 of 9356