Research On Key Technology Of Large-scale Length Comparison Measuring Device

With the continuous development of science and technology,the content and methods of industrial measurement continue to change,and various length measurement devices continue to appear.The measurement accuracy indicators of these instruments are obtained by the instrument manufacturer according to the processing characteristics of the instrument and after testing in the standary laboratory environment,which is the reference index of the measurement performance of the instruments provided for users.In practical application,the measurement accuracy of the instrument will be affected by transportation,measurement environment and measurement personnel.Therefore,A large-length comparison measuring device to meet the traceability requirements of large-size measuring instruments.According to the calibration specifications of photoelectric rangefinder and laser tracker,the overall scheme and layout of large length comparison measuring device are designed after summarizing the technical requirements of large length comparison measuring device.The comparison measurement device mainly includes a 55-meter power measurement motion system,a laser interferometer measurement system and an automatic control system.The laser interferometer,which is the core component of the comparison measurement device,mostly relies on imports and lacks the domestically developed laser interferometer independently developed.The imported laser interferometer adopts the USB transmission method,and the data refresh and delay are relatively large.Therefore,in response to the requirement of high dynamic response data acquisition for laser interference signals,a four-division acquisition card based on complex programmable logic devices(CPLD)was designed,and repeated experimental verification was carried out.As a high-precision basic component of large length ratio measuring device,linear guide will deflect the measuring prism and produce additional optical path difference when it has large straightness error,which directly affects the overall accuracy of the device.Therefore,A laser tracker was used to measure and adjust the straightness error of the 55-meter linear guide.Through repeated measurement and constant adjustment,the final straightness of the linear guide in the horizontal direction is 0.572mm and the straightness in the vertical direction is 0.705mm,which guarantees the technical requirements of the high straightness of the guide rail.The collected card ratio was carried out,and the standard difference between the acquisition card measurement was ± 0.83 μm in the 55 m measurement range.The measurement experiment of the ranging instrument is performed.The experimental results show that the measurement standard difference is ± 2.97μm,the comparison measurement error is compared,and the measurement error is measured.The tracking instrument showed error ratio measurement experiments,and the experimental results confirm that the system meets the specifications requirements.The Large-scale length comparison measuring device is a universal measurement calibration equipment,which can realize high-precision linear displacement measurement in large length,and has a wide application prospects.