Optimization design and experiment of profiling and slide board mechanism of precision rice hill-drop drilling machine

Abstract: In order to better realize the combination of agricultural machinery and agronomy, the design of precision rice hill-drop drilling machine was further optimized and tested. The precision rice hill-drop drilling machine that was powered with high speed transplanter chassis was composed of frame, furrowing and ridging device, height and horizontal profiling mechanism system, power transmission system, seeding device and hydraulic lifting frame. It could meet the rice direct seeding agronomic requirements which are furrowing and ridging synchronously, adjustable sowing rate and hill space, optional row space, profiling seeding mode and stubble burying before seeding. The combined hole-type metering device included small and big type holes was used for the precision rice hill-drop drilling machine, so that it could meet the sowing rate requirement of conventional rice and hybrid rice simultaneously and adjust the seeding rate quickly. On the basis of the combination of agricultural machinery and agronomy as well as the experimental verification, the frame, reduction gearbox, horizontal profiling mechanism, height profiling system and installation angle of slide plate were optimized. The new frame could protect the main bar from being bended. The new reduction gearbox made the hill space to match the speed of the chassis more accurately and also could change the rotation direction to fit different kinds of chassis. The height and horizontal profiling mechanism made the seeding machine more floatable, so it could adapt more complicate ground. Furthermore, the related experiments proved that profiling system is conducive to the seedling emergence of rice. The seedling emergence rates of the rice varieties XS134 and PZTF, which were seeded by the precision rice hill-drop machine with horizontal profiling mechanism, were 7.9% and 8.7% higher than that without horizontal profiling mechanism, respectively. In order to protect the atmosphere environment, the government introduced the relevant policies and laws to prohibit the burning of straw, and promoted the comprehensive utilization of crop straw. Many farmers returned straw residue to field to improve soil fertility and reduce environmental pollution, but it could be more difficult for the direct seeding machine and rice transplanter working in the field as well. To overcome this difficulty, the stubble-burying seeding was studied. The angle of the slide board was confirmed as 4° by the experiment result, while the efficiency of stubble burying was 91.6% and the furrowing and ridging effect under 4° was relatively better than that under other degrees. In this paper, some verification tests involved the main technical indices of the seeding machine and its reliability. Results showed that, the pure work efficiency was 0.67 hm2/h, the qualified rate of hill space was up to 100%, the variable coefficient was as low as 2.5%, the qualified rate of the seeds number per hill reached 95% and the cavity rate was 0; furthermore, the variable coefficient of the consistency of seeding quantity per row and the stability of total seeding quantity were 3.8% and 1.5% respectively; after seeding with horizontal profiling mechanism, the height difference between the left and the right field surface was about 2.0 cm; more important, the average of assignment before first-time fault (MTTFF) was 30.4 hm2/h, and the validity reached up to 98.2%. Therefore, on the basis of these results which all meet the national standard and the requirements of the combination of agricultural machinery and agronomy, and the reduction gearbox makes the machine more universal. The performance of the optimized precision rice hill-drop drilling machine is reliable and has exciting application foreground.