Research On Steel Ball Surface Defect Detection System Based On Eddy Current Sensor

The service life and performance of bearing,ball screw and linear guide are closely related to the quality of bearing steel ball.In order to ensure the quality of bearing steel ball,in addition to strictly controlling all aspects of manufacturing,it is also necessary to strictly inspect the steel ball before delivery.How to realize high efficiency,fast and full surface on-line detection of precision steel ball is a difficult problem to be solved in steel ball industry.As an important method of nondestructive testing,eddy current testing has the advantages of high detection accuracy,sensitive response and easy to realize automation.In this paper,eddy current nondestructive testing method is used to analyze and discuss the key technology of on-line detection of steel ball surface defects,and on this basis,a complete non-destructive testing system for steel balls is developed.The main contents of this paper are as follows:Firstly,combined with Maxwell's electromagnetic theory,the principle of eddy current testing of steel ball and the distribution of eddy current in steel ball are analyzed,and the main factors affecting the detection accuracy and sensitivity of steel ball eddy current sensor are analyzed,which provides theoretical basis for the design of steel ball detection coilSecondly,according to eddy current electromagnetic theory analysis,using SOLIDWORKS to establish the simulation model,and lead into COMSOL for the simulation analysis of eddy current testing of steel ball.The parameters of the detecting coil are set as different values,and the optimal value of the parameters of the detecting coil is determined through the simulation analysis of the different parameters of the detecting system;the detection frequency is determined by analyzing the detection depth of the steel ball and the sensitivity requirement of the system at different detection frequencies,and then the capacitance value of the detection circuit is determined,the influence of lifting height on the test result is analyzed,and then the optimal value of lifting height is obtained,the influence of the size of defect,the location of defect and detection coil on eddy current testing is analyzedThirdly,on the basis of analyzing the traditional expanding method of the steel ball,the surface of the steel ball can be fully unfolded by using the orthogonal sucker expanding mechanism,and the automatic detection of the steel ball can be realized by combining the vibrating plate loading mechanismFinally,data processing and experimental results analysis.The parameters of wavelet function are determined by the control variable method,and the determined wavelet function is embedded in the upper computer program to denoise the detection signal.The steel balls with spot,strip and crack defects are detected and the test results are obtained.The automatic detection of batch steel balls with a certain number of defective steel balls is carried out,and the error detection rate and missing detection rate of the detection system are obtained.It is concluded that the system can better detect the spot,strip and crack defects on the surface of steel balls.