Research on coaxiality measurement system of large-span small-hole system based on laser collimation

Aiming at the problems of large-span small-hole system, such as long spatial span, small measured aperture, short hole depth, large distance between adjacent holes, limited measurement space, and lack of measurement benchmark, a non-contact coaxiality measurement system based on laser collimation with the laser displacement sensor as the core is proposed. According to the mathematical model, a position sensitive detector(PSD) and a motion platform with multiple degrees of freedom are utilized to establish a reference axis for parts at any position. Also, the relevant cross-section circle fitting and coaxiality evaluation algorithms are designed to solve the measurement problem. It is proved that this system has high coaxiality detection accuracy for the parts with large axial dimensions (total length is more than 1500 mm), small aperture (diameter is less than φ 10 mm) and large hole spacing (space between two holes is more than 750 mm), and the measurement error does not exceed 0.03 mm.