Functional Bearing With Position Detection Based On Time-grating Sensing Technology

At present,many domestic industrial production,national defense science and technology fields,productivity improvement,technological breakthroughs,equipment manufacturing and other factors are limited,among which large-scale machinery processing to achieve high accuracy and efficiency is particularly prominent.The reason is that there is a lack of key technology to develop large precision machine tools,and it often solves the problem of position detection of large precision indexing table.These large and super-large precision turntables are often unable to achieve high precision because of the large,hollow and strong impact of the coaxial angular encoder for full closed-loop control.Compared with the traditional grating sensor,the time grating sensor eliminates the link of high-precision grooving.The requirement of manufacturing accuracy is only equivalent to the ordinary machining accuracy,which can achieve the measurement accuracy of measuring grating.Therefore,this paper proposes and develops a kind of bearing with position detection function based on time grating sensing technology to solve the problem of precision displacement detection and precise positioning of large NC turntable at the end of machine tool transmission chain.In this paper,the theory of time grating sensing is introduced.By constructing uniform coordinate system,the transformation between position difference and time difference is realized,and uniform motion coordinate system is constructed by constructing uniform motion traveling wave.According to the principle of field time grating traveling wave formation,the bearing structure is analyzed,and two signal pickup modules of time grating bearing based on time-varying magnetic field are proposed.The sensor model is established,and the electromagnetic field of the two schemes is simulated with Ansoft Maxwell electromagnetic simulation software.After analyzing the simulation results,the structure of the stator and rotor is optimized.The signal processing circuit of time grating bearing is designed to provide the required excitation signal for the sensor,and the output signal of the sensor is converted into angular displacement information.In this paper,YRT180 rolling bearing is used to carry out the experiment.The inner ring of the bearing is mechanically divided into two parts as the sensor rotor,and the stator probe is processed according to the design scheme.Two kinds of experimental prototype of the grating bearing with multi-probe and the time grating bearing with discrete probe are developed.The experimental platform is set up,and the principle experiment and performance test experiment of the sensor prototype are carried out.The experimental results show that the stability fluctuation of the bearing is within ±2?and the original error is within ±25? in the whole week(0o~360o);the stability of the bearing with discrete probe is about ±3? in the whole week(0o~360o)and the original error is within ±30? in the whole week(0o~360o).The experimental results verify the feasibility of the two signal pickup module schemes.From the point of view of measurement stability and accuracy,the grating bearing with multi-probe has better performance than the grating bearing with discrete probe.