Structure optimization and performance simulation of screw discontinuous feeding device

Abstract: Discontinuous, quantitative materials feeding is an important process in industrial and agricultural production. Adapting a spiral feeding device to operate in a discontinuous mode has many advantages, such as good sealing properties, high energy efficiency, simple structure, more effective and better control. Compared with the traditional discrete- quantitative design, converting a spiral feeding device to achieve discontinuous quantitative feeding can shift the quantitative method from passive measuring feeding to active quantitative feeding. It also omits the weight measuring procedure, so as to improve the process-monitoring efficiency with a broad prospect of application. To deal with the instability of materials feed rates and the high-energy consumption of discontinuous spiral feeding device, structure optimization and performance simulation were studied in this paper.The performance index of spiral feeding and the different structural parameters' effects on discontinuous feeding performance were analyzed firstly. Moreover, with the spiral discontinuous feeding device of 100 mm outer diameter as the research subject, minimizing the energy consumption per unit of feeding amount as the optimization goal，the inner diameter，the pitch, and the operating speed were chosen as optimization variables. On the basis of certain constraints, a stochastic direction method was used to acquire the optimization results: speed of 65 r/min, inner diameter of 40 mm, and thread pitch of 85 mm. Furthermore, the discrete element method was used to simulate the effect of changing the inner diameter and pitch on feeding performance, such as particle filling rate, feeding rate variation, and energy consumption.The simulation results showed that: (1) with an outside diameter was 100 mm, the thread pitch 100 mm, and the speed 65 r/min, as the inner diameter increased the feed rate of the spiral feeding device decreased, and the change of average particle filling rate was not obvious; but when the inner diameter was too small or too great, the energy consumption and the fluctuation in particle-filling rate both increased. When the inner diameter was the commonly used size of 50 mm, the performance of feed stability and energy consumption was better; (2) when the outside diameter was 100 mm, the inner diameter 50 mm, and the speed 65 r/min, as thread pitch increased, the feed rate of spiral feeding device increased gradually, and the average particle filling rate decreased slowly, but when the thread pitch was too small or too great, the energy consumption and the fluctuations in particle-filling rate both increased. When the thread pitch of 100 mm was the standard size, the performance of feed stability and energy consumption was better; (3) with an outside diameter of 100 mm and the speed of 65 r/min were unchanged, the inner diameter of 40 mm and the thread pitch of 85 mm were optimal, and the feed-rate stability, energy consumption, and overall performance of the spiral feeding device were superior to other conditions.