Uma interface eletrônica e computacional para medições a três coordenadas
Data
2017-11-15
Autores
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Biblioteca Digital de Teses e Dissertações da USP
Universidade de São Paulo
Escola de Engenharia de São Carlos
Universidade de São Paulo
Escola de Engenharia de São Carlos
Resumo
Descrição
As Máquinas de Medir a Três Coordenadas (MM3Cs) desde sua criação evoluíram sensivelmente, entretanto poucas foram as modificações estruturais observadas. Hoje, para fabricantes de máquinas destacarem-se no mercado, são necessários grandes investimentos na busca de novos materiais estruturais e no desenvolvimento de programas computacionais cada vez mais versáteis. O sistema eletrônico e os programas computacionais utilizados durante as medições são inacessíveis e rígidos. Estes aplicativos normalmente não podem ser analisados nem modificados pelo usuário. São exemplos clássicos desta rigidez as características préestabelecidas pelo programa, ou métodos de ajustes utilizados na definição das grandezas. Este trabalho tem por objetivo exibir a interface eletrônica e computacional que quebra essa rigidez e permite a aquisição dos sinais das escalas da MM3C, possibilitando o desenvolvimento de novos aplicativos computacionais. O sistema foi aplicado em uma MM3C do tipo Ponte Móvel. Foi desenvolvido um programa computacional, MaqMed 2000, que utiliza os valores dos pontos coordenadas capturados no volume de trabalho da MM3C, e faz a compensação das coordenadas dos pontos utilizados, através das equações do Modelo Reduzido de Sintetização de Erros (MRSE). A avaliação da compatibilidade do dispositivo construído foi feita através do MaqMed 2000 em situações práticas. Foram tomados pontos no perfil de artefatos-padrão e os pontos ajustados através de duas rotinas, uma com e outra sem compensação dos erros. Os artefatos foram medidos em várias posições no volume da MM3C e averiguada a proximidade entre os resultados compensados e os não compensados, ao valor calibrado do artefato. O sistema desenvolvido permitiu compensar os erros em até 98% para compensação bidimensional e 87% para tridimensional.
Since the advent Coordinate Measuring Machines (CMMs) have improved substantially. However, only a small number of structural modifications were observed. Nowadays, considerable capital expenditure is needed to keep CMM builders competitive. Most important research fields concern structural material and production of more flexible and versatile software. The electronic system and the software used during measurement with CMM are rigid and inaccessible and no user modification is permitted. Typical examples are the predetermined software features and curve fitting methods used on the magnitudes definition process. This research aims to exhibit an interface that copes with the system stiffness and enables signal acquisition from the scales of the CMM, allowing the development of new types softwares. The proposed system was implemented on a moving bridge type CMM. A program that uses the values of the coordinate points obtained from the CMM work volume was created. The software MaqMed 2000 performs the compensation of the coordinates of the used points by means of synthesized errors equations. Evaluation of the performance of the built device was carried out using MaqMed 2000 in practical situations. Data sets were collected along the profile of artefacts and fitted by means of two routines, one with error compensation and the other not compensated. Artefacts were measured in several locations in the whole volume of the CMM. The proximity between the compensated and noncompensated results with respect to the calibrated artefact value was examined. The developed system allowed for error compensation of 98% for bi-dimensional compensation and 87% for tri-dimensional compensation.
Since the advent Coordinate Measuring Machines (CMMs) have improved substantially. However, only a small number of structural modifications were observed. Nowadays, considerable capital expenditure is needed to keep CMM builders competitive. Most important research fields concern structural material and production of more flexible and versatile software. The electronic system and the software used during measurement with CMM are rigid and inaccessible and no user modification is permitted. Typical examples are the predetermined software features and curve fitting methods used on the magnitudes definition process. This research aims to exhibit an interface that copes with the system stiffness and enables signal acquisition from the scales of the CMM, allowing the development of new types softwares. The proposed system was implemented on a moving bridge type CMM. A program that uses the values of the coordinate points obtained from the CMM work volume was created. The software MaqMed 2000 performs the compensation of the coordinates of the used points by means of synthesized errors equations. Evaluation of the performance of the built device was carried out using MaqMed 2000 in practical situations. Data sets were collected along the profile of artefacts and fitted by means of two routines, one with error compensation and the other not compensated. Artefacts were measured in several locations in the whole volume of the CMM. The proximity between the compensated and noncompensated results with respect to the calibrated artefact value was examined. The developed system allowed for error compensation of 98% for bi-dimensional compensation and 87% for tri-dimensional compensation.
Palavras-chave
Erro volumétrico e compensação, Máquina de Medir a Três Coordenadas (MM3C), Three Coordinate Measuring Machines (CMM), Volumetric error and compensation