Design and Experiment of Wheat Pneumatic Centralized Seeding Distributing System

Abstract

Aimed at the problem of low breadth and uneven wheat sowing machine, a kind of wheat pneumatic centralized sowing system was designed. The sowing mechanism and distribution mechanism were studied from the aspects of concentrated quantitative seeding system and airflow first-order distribution system. The stability of the centralized quantitative seeding system and the uniformity of the seed distribution system were analyzed. Concentrated quantitative seeding system discharged a certain amount of seeds, and the seeds fell into the conveying tube in gravity. Airflow first-order distribution system converted the seeds into a uniform seed stream and transported to the seeding tube, which achieved uniform seeding requirements. According to the principle of distributor, the diameter of the conveying tube was 50mm. By the computational fluid dynamics (CFD) software Solidworks Flow, the influence of structural parameters of seed distribution system on vacuum chamber fluid were simulated and analyzed. The structural parameters included the conveying pipe and outer cover. The analysis of speed flow field showed that corrugated length of the fold tube was 16mm, corrugated angle of the fold tube was 90°, and cone angle of outer cover was 120°. The experiments of the uniformity and steadiness was designed and conducted for seeding distribution system. The performance tests were performed with four indices adopted, including variation coefficient of total displacement stability, variation coefficient of each row displacement consistency, seeding rate coefficient of variation of distributor intra-row, and the percentage of damaged seeds in laboratory. The results showed that when rotate speed of sowing device was in the range of 20~40r/min, variation coefficient of total displacement stability was 1.01%~1.19%, variation coefficient of each row displacement consistency was 3.20%, seeding rate coefficient of variation of distributor intra-row was 3.96%, and the percentage of damaged seeds was 0.23%. The test results were consistent with CFD simulation. The field experiment of sowing was also carried out with four indices, including the percentage of damaged seeds, variation coefficient of total displacement stability, variation coefficient of each row displacement consistency, and variation coefficient of seeding uniformity for this device. The results showed that variation coefficient of total displacement stability was 1.06%, variation coefficient of each row displacement consistency was 3.34%, variation coefficient of seeding uniformity was 27.35%, the percentage of damaged seeds was 0.28%, and the seeding emergence rate was 89.63%. These testing results fully coincided with the standard GB/T 9478—2005 Test methods of grain drills. The design and experimentation improved the seeding stability and distribution uniformity of the planter, and the results provided a theoretical reference for the design and analysis of wheat wide precision sowing.

Keywords: wheat, quantitative seed, distributor, pneumatic centralized type