COBEM99

SR20 Metrologia

Title:

UM MODELO HÍBRIDO PARA O CÁLCULO DAS COMPONENTES DO ERRO VOLUMÉTRICO EM MÁQUINAS DE MEDIR A TRÊS COORDENADAS

Summary :

HIBRID MODEL FOR CALCULATION OF VOLUMETRIC ERRORS COMPONENTS OF CMM ABSTRACT. THE ACCURACY AND THE REPEATABILITY OF MEASUREMENTS OF THREE COORDINATES MEASURING MACHINES (CMM) ARE AFFECTED BY SEVERAL ERRORS. AMONG THEM, GEOMETRICAL ERRORS ARE THE MOST INFLUENTS IN THE MOST EXPERIMENTAL CASES. THE RESULT OF GEOMETRIC ERRORS COMBINATION IN EACH OF THE PREFERENTIALS DIRECTIONS IS DENOMINATED OF VOLUMETRIC ERROR COMPONENTS. THUS, ITS POSSIBLE TO KNOW THE EXISTENT RELATIONSHIP BETWEEN COORDINATES OF MEASURED POINTS AND VOLUMETRIC ERROR COMPONENTS. SEVERAL METHODS HAVE BEEN PROPOSED TO MODEL THE BEHAVIOR OF THE VOLUMETRIC ERROR IN CMM AS A FUNCTION OF THE X, Y AND Z COORDINATES. HOWEVER, SOFAR FROM EXPERIMENTAL MEASUREMENTS OF THE VOLUMETRIC ERROR NO MATHEMATICAL MODEL FOR THE DESCRIPTIONS AND CHARACTERIZATIONS OF ERRORS HAS BEM PROPOSED. IN THIS WORK IS PRESENTED A GENERAL METHODOLOGY TO OBTAIN A MATHEMATICAL EQUATION AND PREDICTION OF THE COMPONENTS OF THE VOLUMETRIC ERRORS, USING MULTIPLE REGRESSION. THE METHODOLOGY WAS APPLIED AT A OF "MOVING BRIDGE" CMM TYPE. WERE OBTAINED THREE REGRESSION EQUATIONS, ONE FOR EACH COMPONENT OF THE ERROR, STARTING FROM DATA COLLECTED BY DIRECT CALIBRATION, SPECIFICALLY BY THE DIVIDED VOLUME METHOD. THE MODEL WAS EVALUATED STATISTICALLY. THE SIMULATED RESULTS WERE EVALUATED, DISCUSSED AND COMPARED WITH THE RESULTS OBTAINED THROUGH THE BALL BAR CALIBRATION, SHOWING AN EXCELLENT CAPACITY OF THE MODEL IN THE PREDICTION OF THE VOLUMETRIC ERROR OF THE MACHINE. PALAVRAS CHAVES: BALL BAR, QUADRATIC MODEL, CALIBRATION

Author :

Arencibia, Rosenda Valdes
Giacomo, Benedito Di
Souza, Vagner Augusto

Paper View :