Movement law of maize population in seed room of seed metering device based on discrete element method

Abstract: Development of conservation tillage can improve the ecological environment in alpine arid area of northern China and farming and animal husbandry interlaced zone, conducive to the sustainable development of China agriculture. Due to the regional difference of conservation tillage, developing a precise no-tillage planter suitable for alpine arid area has an important significance for farming and animal husbandry interlaced zone in increasing surface coverage and reducing water loss and soil erosion. As the surface under conservation tillage has a certain amount of straw and stubble, vibration characteristic of planter is different from common cultivation during the operation, and the vibration has great influence on the movement state of seed population. Population movement state affects seed suction performance of air-suction seed metering device, thus influencing the quality of whole operation of no-tillage planter. When the vibration is small, population movement speed is low, liquidity is poor, and suction hole re-suction rate is relatively high; when the vibration is large, population movement speed is high, and it is difficult to suck seeds for suction hole and the leakage rate is relatively high; proper vibration can reduce the leakage rate and the re-suction rate of suction hole. Therefore, for no-tillage surface planting in alpine arid area, metering device vibration and population movement state have great influence on seed suction performance of air-suction seed metering device. The paper aims to study the influence law of vibration parameters of seed metering device on corn population movement in seed metering device during no-tillage surface operation with air-suction no-tillage planter. This paper adopts the BK acceleration sensor and Pulse LAN-XI vibration test system for testing vibration characteristics of seed metering device during no-tillage surface operation with 2BM-5 air-suction no-tillage planter, and the analysis on time domain and frequency domain of vibration signal is conducted with the MATLAB software. Then the time domain and frequency domain results are taken as input parameters of seed metering device model in discrete element software, and the movement law of maize populations under the condition of vibration is simulated in the field work of no-till planter. Seed suction performance bench test verification is performed with the JPS-12 computer vision test bench and LKD-P type suction electromagnetic vibration table, and the analysis on seed metering performance of air-suction seed metering device is conducted under different operation speed and vibration amplitude. Field vibration signal analysis results show that when the field operation speed of planter increases from 2 to 7 km/h, the frequency of the main vibration power of seed metering device is basically kept at 5, 6 and 7 Hz; the vibration amplitude of the seed metering device shows a linear increase from 2.4 to 7.9 mm. Discrete element method simulation results show that the fitting curve between the maximum speed of corn population in seed room and the forward speed of planter has a fitting determination coefficient (R2) of 0.9671. The fitting straight line between the average speed of corn population and the speed of planter has a fitting determination coefficient (R2) of 0.9325. Bench test results show that the operation speed for good seed metering performance of the air-suction seed metering device is 3-5 km/h, and the good vibration amplitude is 6 mm; the maximum speed range of the population is 0.1203-0.2243 m/s, the population average speed range is 0.0807-0.1413 m/s, the maximum speed range of the population in seed suction area is 0.127-0.26 m/s, and the air-suction seed metering device has a good performance. The results can provide theoretical basis for improving the seed suction performance of air-suction seed metering device of no-tillage planter.