Metodologia de calibração de blocos padrões usando uma máquina de medição por coordenada

Abstract

The standard blocks assumed the role of standardizing the concept of length and materialization in dimensional analysis, efforts in the pursuit of quality and minimization of errors has been a challenge in the search for qualification of measurement. First with Eli Whitney enthusiast who implanted in the idea of interchangeability in the manufacturing industry and subsequently Johansson taking the initial step even facing obstacles in construction innovated and until today has this invention as a world standard and Quality reference. Parallel to this we have the scientific technical development that, in order to give greater credibility through the quality in the manufacture saw the need to standardize the industrial production, with this the creation of regulatory units, so we have the emergence of numerous organs that regiments and standardizes the technical activity in order to adapt to international standards, In Brazil we have the ABNT organ founded in 1940, an important institution at the national level in the elaboration of technical norms, being very often as a model for other collegiate organs. The most diverse technical Norms exemplify practically the same points, even with some changes that vary from applications and targeting, other points as specified tolerances, conceptualization of the object as well as the techniques of calibrations That can be adopted and what the implications in the use of each are somewhat equal, Similarly the mechanical properties inherent to the manufacturing material of the blocks, hardness, expansion characteristics and the behavior of the material facing the environment such as temperature and exposure are also specified and in a certain way standardized. There are two calibration techniques specified and each with particularities, which depending on the application can be chosen one or the other. The calibration by comparison consists of the intercomparison between dimensions of a block to be calibrated with the other one previously gauged at a higher level called the reference block, through an equipment called a mechanical comparator, which is usually Used when you want to get a faster analysis and a low cost. On the other hand, the interferometric system most intended for the calibration of reference blocks, this method is summarized in the optical analysis through the previously known wavelength, determining the differences between the fringes of reflected interferences On a lower surface that after calculations it is verified the dimensional deviation and the length of the block, this method is more sophisticated and indicated when you want greater accuracy in the results. As a proposal for this work an alternative method using a coordinate measuring machine (MMC), proved to be a viable and highly qualified form in the calibration and analysis of the geometric deviations of the standard blocks, the technology aggregated to the Device and the versatility in the traceability of the result demonstrated that the coordinated measurement the development of a block fixation device to MMCs and the analysis of the results in the face of deviations and uncertainties further qualified as a Optimum alternative to standard block calibration.