Vibratory Feeding Performance Improvement Through Discrete Element Analysis for High-Speed Optical Detection of LED Chips

A high-speed vibratory bowl feeder is a key equipment of the optical detection of light emitting diode (LED) chips. Addressing the stationarity-losing problem induced by transporting small-size and light-weight LED chips, this study designs a vibratory bowl feeder for the high-speed detection of small LED chips based on theoretical and numerical analyses. To understand the influence of the structural parameters of the feeder on its performance, we create a mathematical model of the part's behavior base on the Hertz-Mindlin contact theory. The numerical model indicates that the property of the part, the track angle and the friction coefficient of the track are the main factors that affect the behavior of the part in the feeding process. Through the discrete element method (DEM) simulation, we observe the part behavior under different track angles and friction coefficients of the feeder. The motion stationary of the LED chip is evaluated by its standard deviation (STD) of velocity and hopping height. Thus, we can appropriately determine these parameters of the vibratory feeder in order to get the optimal feeding performance. Finally, an experimental platform of the LED chip detection device is built to verify the performance of the vibratory bowl feeder. The experimental results show that the performance of the feeder was in good agreement with the simulation results. With the theoretical analysis and experimental verification, the vibratory bowl feeder was successfully implemented for LED transportation and reached a high feeding velocity of 1516.5 pieces/min at the working frequency of 223 Hz.