Simulation and optimization of the spoon-wheel type maize precision seed- metering device based on vibration

Abstract

Due to the sticky soil and uneven terrain in southwest China, the planters will vibrate in the field, and the seed-metering device will also be vibrated up and down with them, hence increasing the leakage rate and deteriorating the plant distribution uniformity in maize. The spoon-wheel disc is the essential part of the spoon-wheel seed-metering device, and the spoon shape contributes to the device’s capacity for seed-filling, seed-cleaning, and seed-delivery. DEM simulation and optimization of the shapes and quantity of spoons under vibrational conditions are investigated in this paper. EDEM was adopted to establish DEM models of ‘Zhongyu No.3’ coated maize seeds and the spoon-wheel seed-metering device first, and four additional spoons of various shapes (labeled as K1 ~ K5, respectively) were designed based on the original spoon structure. Based on the in-field vibrational properties of the spoon-wheel planter at diverse operating speeds, a single-factor simulation test of the spoon structures under vibrational conditions was implemented with the variation of the seed acceleration inside the spoon in the Y-direction as an evaluation index. The results indicated that the acceleration of seeds in the Y-direction in spoons (K2 ~ 5) were all less fluctuating than those in the original spoon (K1), and the multiple rate was the largest in spoon (K5), implying that the seeding performance of spoons (K2 ~ 4) was relatively more favorable. According to the results of the single-factor simulation test, a 3-factor and 4-level simulation orthogonal test was conducted with the working speed, the number and shapes of spoons as testing factors, and the qualified rate, multiple rate, leakage rate, and variation coefficient as evaluation indicators. The ultimate optimal working speed of the spoon-wheel maize precision planter in southwest China was identified as 3 km/h, with 22 spoons on the spoon-wheel disc, and the ideal spoon shape being K3. The bench validation test was executed under vibrational conditions based on the optimal spoon structure and operation settings of the seed-metering device. The qualified rate of the seed-metering device exceeded 94.5% at an operating speed of 3 ~ 4 km/h, while the multiple rate was less than 4%, the leakage rate was lower than 1.5%, and the variation coefficient was smaller than 25.5%. The variety adaptability test was launched when the working speed was 3 km/h. The qualified rate of various maize varieties were all more than 96.5%, the multiple and leakage rates were both less than 2%, which satisfies the technical requirements of the maize precision sowing in southwest China.