| Rice is one of the important food crops in China. The planting patterns of rice mainly are two crops a year and a year one ripe. Compared with double cropping rice, the middle-season rice has higher efficiency on the whole, so farmers generally tend to plant middle-season rice. Owing to the planting time of middle-season rice is relatively broad, so used more direct seeding. And because the direct seeding with saving time, saving the cost, increasing the efficiency and other advantages, its planting area has the trend of expansion year by year.In order to meet the demand of rice precision seeding, this article has carried out the experimental research on the material properties of rice, and based on the test result of material properties, designing a kind of double cavity side-filled precision seed metering device which adapted to seed hybrid rice and conventional rice, analyzing the theoretical for the process of filling seed, retaining seed and throwing seed of seed metering device, and carrying out the bench test. The main research content is as follows:(1).Carrying out the experimental research on the material properties of rice, analyzing general rules of the material properties of rice under the different content condition, the general rules, getting three dimensional size, 1000-grain weight and natural angle of repose under the different moisture conditions, sliding friction angle under different materials and different moisture content of "Peizataifeng" and "Huanghuazhan", which provided the basis for the design of structure parameters of type holes of seed metering device.(2) Based on the principle of side-filled, the double cavity side-filled precision hole seed metering device for rice was developed, the seeding theory was analyzed, and the structure parameters and working parameters were determined.(3) The movement condition and stress were analyzed in the process of filling seed, clearing seed, throwing seed, retaining seed and clearing blockage of seed metering device, and the mechanics model of filling seed, clearing seed, throwing seed were established.(4) With the rotational speed of seeding axle as the experimental factor, indoor bench test about seed metering device was carried out, the experimental result showed: the number of rice seeds discharged by seed metering device obeyed normal distribution, while the rotational speed of seeding axle ranged from 10r/min to 25 r/min, with the increase of rotational speed of seed metering axle, the qualification ratio((2-4)seeds per hill) of seeding “Huanghuazhan” ranged from 84.13% to 88.85%,and the qualification ratio((5-8)seeds per hill) of seeding “Peizataifeng” ranged from 67.03% to 72.40%. When the rotational speed of seeding axle was more than 25 r/min, the qualification decreased along with increasing of rotational speed of seeding axle, the resowing ratio fluctuated within a narrow range, and the leakage ratio was rising; the single cavity of seed metering device was used to seed the “Peizataifeng”(Hybrid rice) while the double cavity of seed metering device was used to seed “Huanghuazhan”(Conventional rice),the optimal combination parameters were rotational speed of seeding axle with 25 r/min, forward speed of conveyor belt with 1.0 m/s, hill distance with 150 mm, throwing-seed height with 150 mm,the angle between type hole central line and the end face of seeding plate was 20°, the angle between the radial direction of the long axis of the section of the type hole and the radial direction along the end face of the seeding plate was 90°, under the optimal combination parameters, the qualification ratio((2-4) seeds per hill) of seeding “Peizataifeng”(Hybrid rice) with single cavity was 87.04%, the resowing ratio((0-1) seeds per hill) was 2.96%, cavity ratio(0 seeds per hill) was 3.33%,and the breaking ratio was 0.40%; Meanwhile, the qualification ratio((5-8)seeds per hill) of seeding “Huanghuazhan”(Conventional rice)with double cavity was 70.26%,cavity ratio(0 seeds per hill) was 0, and the breaking ratio was 0.06%. |
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