Vibratory Conveying and Distributor Experiment of Rehydrated Pellet Feed for Silkworms Based on the Discrete Element Method

To solve the problems of low efficiency, poor uniformity and high labor intensity in the manual distribution of rehydrated pellet feed for young silkworms, a distributing machine for silkworm rehydrated pellet feed was developed. According to the feeding requirements of 1st- and 2nd-instar silkworms, the required feed mass per rearing tray was determined to be 1350 g and 3640 g, respectively, with distribution widths of 375 mm and 750 mm, and a continuous distributing device composed of a rehydrated pellet feed conveyor, a vibrating feeder and a silkworm tray conveyor was designed. A discrete element model of the rehydrated pellet feed was established using the Hertz–Mindlin with JKR contact model, and the particle surface energy was calibrated using the angle of repose as the target; the resulting surface energies of the 1st- and 2nd-instar silkworm feeds were 0.095 J/m2 and 0.05 J/m2, respectively. The effect of the vibration direction angle on the particle conveying characteristics was analyzed, and among the tested angles of 30°, 35° and 40°, the average tangential velocity of the particles was the highest at 30°, indicating better conveying performance. The model was validated by high-speed photography for both feeds: the measured distance between the particle and the trough surface was 19.27 ± 5.98 mm and 18.97 ± 4.69 mm for the 1st- and 2nd-instar feeds, compared with 20.23 ± 2.60 mm and 20.01 ± 2.65 mm in the simulation, giving relative differences of 4.75% and 5.20%. Prototype tests showed that the measured feed mass per tray was 1320.91 g for the 1st-instar feed and 3659.44 g for the 2nd-instar feed, deviating by −2.15% and +0.53% from the required values, that the distribution width was 387 mm and 750 mm, and that the distributing time per tray was 15 s and 20 s, respectively. The machine met the feeding requirements of young silkworms reared on pellet artificial feed.