| Steel ball is an important component of ball bearings, as a rolling body bear load and the dynamic performance of the bearing directly related to the bear. Its quality will have a direct impact on bearing service life and reliability. With the high performance and high-speed machine-oriented development,there is a more stringent quality requirements on the surface of steel ball bearings.The defects of steel ball near the surface or near the sub-surface generally refers to the cracks,pockmark,crow ball.These defects are key factors which restrict the improving quality of steel ball.Now,most of the steel ball factory adopt the artificial-appearance method to find these defects.With the time growing,people eyes become fatigue leading to high false detecting rate,and the method can't find the defects near the sub-surface;A small number of factory buy the imported testing equipment,it can't satisfy the needs to testing as the high price.This paper analyzes and compares on the principle of non-destructive testing methods for characteristics of quality defects of the ball, discusssing the eddy current testing in steel ball has a surface crack detection test reliability, high efficiency, non-contact, easy to automate the detection superiority. It proves the eddy current method of testing the crack of steel ball surface feasibility, using of eddy current to detect ball surface and subsurface cracks, scratches and other defects in the quality of feature information.Under the analysis of steel ball surface eddy current inspection system objectives, functions, we do the work of the functional module analysis and design for the eddy current testing system. We select the appropriate eddy current sensors, and designed the signal source, amplifier, sensor voltage compensation circuit, orthogonal reference source, phase-sensitive detector, filtering and isolation peripheral circuits. Anti-interference measures on the system hardware and its improvement methods are analyzed and discussed.The host computer display interface is designed to use HMI configuration software for steel ball quality inspection and sorting,and prepared a transport protocol with the next crew F020 microcontroller for high-speed data communication,after debugging. The next crew can get the data collect and can be transmitted quickly and accurately to the upper plane, the upper can also send commands to the next crew with the correct response.Experimental data analyzed by lift-off effect on the impact of defect signals to determine the sensor to the ball the right distance, according to the defects characteristic information extraction, design of eddy current acquisition board to the correct characterization of the crack and the equivalent impedance Ball relations plan . |
