Principle and Mechanical Structure of Accuracy Checking Device for CMMsXu Gang, Fei Yetai ,Li GuangkeXu Gang, Fei Yetai ,Li GuangkeAbstract:A portable accuracy calibrating instrument for CMMs are developed based on the combination calibration method with symmetric connection of one dimensional ball row. The system consists of a flat with global holes, a sliding track, a bracket, a foundation, a servo-drive system and electric control, as well as data - processing software. Based on the knowing of any interval＇s deviation of the ball row, the row intervals are contrasted with the coordinate intervals using symmetrically connected method. Then the error of the point in the space of CMM can be calculated by processing the measuring values with the least square principle. By using this method called combination calibration with symmetric connection of one dimensional ball row, the checking accuracy of one dimensional ball row can reach a high level and the checking range can be largely increased. Based on the calibration of one interval of ball row which is regarded as the standard value, the accuracy of one dimensional ball row and the accuracy of CMM which is unknown before checking can be obtained after a whole measuring process. What＇ s more, the checking device needn＇ t be calibrated periodically according to the national standard value transmission, but it needs to be calibrated by using units with simple device and the standard value that they have. So this method doesn＇ t require tbe stability of the checking device, and it will also be easier to design and manufacture the checking device.[著者文摘]