Research On Base Flatness On-line Measurement Technique

The flatness of hall bases is one of the key factors that affect the construction quality. Hull bases are composed of many flats with different sizes, whose geometry sizes are large, some will amount to 10 meters. Requests to the machining accuracy of hull base are generally high, there usually should use special machine to accomplish the precision machining. High accuracy flatness measurement will take place not only before and after the machining process, but dynamic flatness on-line measurement around the machined points is also necessary during the course, this can be convenient to adjust some related parameters and notarize whether the machining results meet the requirements. The technology of flatness on-line measurement integrates the machining and detecting processes, realize the integration of them, reduces measuring time and greatly increases production efficiency.At present there is not any forthcoming flatness on-line measurement system that can be available, in this paper according to practical needs, take the error separation technique as theoretical basis, and design a flatness on-line measurement system based on several eddy current displacement sensors, and carry on evaluation to the measured dates basing on least condition principle to figure out flatness error value.This paper proposes the whole design scheme of base flatness on-line measurement, using the two-dimension frequency domain four-point method to realize the flatness error separation, which can help decrease harmonic suppression. Use several sensors to convert displacement to analog voltage signal, and design a data sampling and processing circuit taking the high speed DSP chip TMS320VC5416 as the core processor, which include A/D conversion circuit, warless transmitting module, data display module and extend a Flash memory to ensure bootloader. Finish signals' A/D conversion that from sensors and realize errors separation. Rely on timer interrupt period to control the sample frequency of A/D conversion to realize synchronization with machine. Error separation results are transmitted to computer in a wireless way in order to smooth away the line connecting difficulty. On the computer, design base flatness evaluation software, and figure out the flatness error value using the order discriminate method basing on the least condition principle, realizing human-computer interaction.Preliminary lab experiments indicate that the technique approach of the system is feasible and measuring accuracy and efficiency achieves the expectation effect, which will lay a solid foundation for the subsequent field debugging and application.