Measurement point prediction of flatness geometric tolerance by using greytheory

The objective of this study is to improve the efficiency in achieving accur ate and speedy inspection when coordinate measuring machine (CMM) is used t o measure geometric tolerance. The grey prediction in grey theory was appli ed in developing the algorithm for predicting the number of measuring point s required for measuring geometric tolerance in this article. The said algo rithm was used to plan the number of measuring points of the next workpiece and to predict the geometric tolerance dimension of the next workpiece. Th is step provided better foundation for on line inspection to determine the number of measuring points required for measurement inspection of the next workpiece. Besides, it can predict whether the geometric tolerance of the n ext workpiece conform with the geometric tolerance dimension marked on the design drawing. This algorithm is used to determine whether the manufacturi ng process requires modification. in an attempt to save human and material resources and improve failure rate. In this paper, the said algorithm refers to the flatness measurement point algorithm in a plane of the workpiece. in planning for the increase of meas uring points, this algorithm is bound by the principle of keeping the measu rement scope a rectangular shape by adding a row of measuring points. When the prediction value exceeds the designation dimensions range, immediate in spection of the manufacturing process is needed. The concept of on line ins pection of the addition of measuring points is also incorporated together w ith the grey prediction model and concept of standard deviation model in an effort to develop the said algorithm. Experimental data were also introduced to verify the flatness geometric tol erance measuring points algorithm for the flatness geometric tolerance in a workpiece plane. The objective is to reach a balance between the smallest number of measuring points possible required for inspection and inspection accuracy. Consequently, one can avoid using too many measuring points, whic h increases the inspection time, while achieving the required measurement a ccuracy. (C) 2001 Elsevier Science Inc. All rights reserved.