Abstract: In order to solve the agglomeration problem and the contradiction between speed and precision in the quantitative weighing of floccule powder products, a micro-high precision weighing system based on industrial PLC was designed. The methods of improving the mechanical structure and controlling the weighing by stages were adopted by this system. In terms of mechanical structure, the agglomeration problem occurred during the rubber powder weighing could be overcome by the spiral feeding mode combining with heart-shaped agitator and feeding screw to a certain extent. FX3U-32MT-E PLC was adopted as the core of the whole circuit, the feedback weight information was dealt with in time, and instructions were sent to the actuator. According to the weight information, the layingoff motor speed was controlled by the software to realize the laying powder products in stages and improve the weighing precision. Finally, the weighing test of rubber powder with different moisture content was carried out,in order to verify the effectiveness of the micro highprecision weighing system for flocculent powder products. The research results show that when weighing rubber powder with more than 6% moisture content, the weighing error can be stabilized within 250mg, the standard deviation of weighing value can be controlled within 0.21g, the maximum relative error can be controlled within 2.5%, and the weighing speed can reach 12~14seconds per time. The measured weighing speed and accuracy can meet the requirements of automatic weighing rubber powder.

Key words:  automatic weighing system;weighing of powder products; the weighing sensor; weighing accuracy