| Worm gear and worm transmission has the characteristic of high transmission ratio, good stationarity, low noise, compact construction and self-locking for requirement, which has wildly applied to machinery processing and manufacturing industries, especially in precision mechanic and precision instrument manufacture. Measured worm gear transmission errors can describe accuracy parameters synthetically.Research team designed a"full microcomputerized test system of gear machine accuracy"(FMT) in 1991, which combines circle magnetic encoders of bearing spring to realize transmission chain errors measurement. This measuring system has been successfully applied to fault diagnosis of machine tools for many years. With the development of microelectronic technology, traditional computers in the 90s are replaced by advanced ones with novel hardware. In addition, DOS operating system is update to Windows operating system. In sensor field, magnetic encoders are gradually withdrawn from the market for some reasons. Currently the most common used displacement sensor is optical grating, but advanced optical gratings are rely on import, So the price is much high, and some optical gratings with certain accuracy are under import restriction, which is the key to restrict the manufacturing industry of detecting instruments and numerical control system. Time grating displacement sensors are original inventions with proprietary intellectual property rights, which have the characteristic of high accuracy, low cost, strong anti-interference and so on. They are mainly applied to measurement field in industrial production.On the one hand, research work adopt new technology to realize a novel FMT system based on original FMT system; On the other hand, in order to remain past several decades of transmission error measurement experience with incremental sensors, original absolute angular signal outputted by time grating sensors should be transformed to incremental pulses of spatial equal division. In this way, a novel FMT system based on absolute time grating sensor is designed. So this measurement system can be applied to transmission error measurement with high accuracy and low cost, as well as the transmission accuracy measurement of machine tool.Main research content and innovations are as follow:1. A forecasting method is employed to dynamic measurement with time grating displacement sensor. According to analysis on series of measured data for certain space with time grating displacement sensor, the future measurement data can be forecasted. In this way, absolute time grating sensors can be transformed to incremental ones. 2. The principles of identification, checkout, optimization, adaptive ordering and parameter estimation of forecasting model are discussed in this paper. Series of discrete measured angles sampled in equal time interval by time grating can be regarded as time series. So according to time series model and methods, forecasting model can be established to generate continuous spatial angle displacement. In this way, time discretization can be transformed into spatial discretization for measured data of time grating.3. The principles and technology of dynamic measurement errors correction are discussed. Measured data of time grating can be regarded as discrete normalized value which is employed to correct forecast errors in real time. And stationary time series can be obtained with difference for measured angles of time grating sensors. Established AR model can be applied to high accuracy forecast for time grating. Experiment results prove that dynamic forecast errors can be restrict within±2″.4. The synchronous comparison principles of transmission error and corresponding displacement are discussed, as well as sampling principle of FMT system. Multi-level clock interpolation principle and adaptive algorithms are presented based on original subdivision principle of FMT system to improve the accuracy of transmission errors to greatest extent under various measurement environments.5. Based on analyzing the characteristics of the fixtures of measurement sensors for traditional transmission error measurement system, shift level mode structure is adopted for the fixtures of upper sensors. In order to eliminate installation eccentric, soft algorithms are adopted to process measurement curves for different position of shift level.6. A novel FMT system based on time grating sensors:①The design of large worm gear measuring system. This measuring system offers measurement methods to the integrated accuracy of large worm gear. In addition, measurement results can feedback to processing chain and guide industrial production.②The improvement of small worm gear measuring system. Original gear integrated errors measuring systems are improved with time grating sensors. Then realize integrated errors measurement for small worm gear.③The design of online measuring system for worm gear process. This measuring system can be applied to machining and on-line testing, which avoid errors caused by multiple installation during machining and testing process. In addition, transmission accuracy testing during machining can ensure that machining parameters can be adjusted in real time to achieve high precision machining fast. ④Combining measuring systems with Carla Henrique KeFu error transfer rule, the transmission accuracy of hobbing machine can be analyzed systematically. And error correction methods are analyzed and obtained with known artificial errors. Finally, according to the characteristic of error, a general hobbing machine can be improved into a high precision worm gear tool.⑤Accuracy improvement of worm grinder. According to analyzing transmitted chains of worm grinder, transmission accuracy can be improved with eccentric gears. The researches above in thesis have been summarized as fig.1-fig.2 showed on page 11. |
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