Abstract
For the purpose of reducing the number of conventional seed-metering devices and high demand for vacuums, this study designed a vacuum central drum seed-metering device, that is intended to replace multiple seed-metering devices with one, which is comprised of the inner and outer drum. This can be replaced with different diameters of suction holes, ventilation housing, seeding tube, agitating devices, seed box, and seed-cleaning devices, etc. A hybrid rice seed Jingliangyou 1212 was applied as an experimental material, and a JPS-12 computer vision metering device test bench was used to test singular-factor and multi-factor seeding performance of the seed-metering device. The singular-factor performance test of the metering device was conducted under negative pressure of seed suction in the range of 1∼1.5 kPa, at the metering device rotation speed of 10∼60 rpm, with diameters of inlet holes being 2 mm (chamfer: 45°), 2, and 1.5 mm, respectively. The number of seeds was counted by a sucking hole under different factor combinations. The multi-factor test was carried out by rotation rate, negative pressure, and types of sucking holes. A rate of 2 ± 1 rice seed per sucking hole is regarded as the qualified standard. It shows that the qualification rate (2 ± 1 rice seed per sucking hole) of seed suction can reach 97.4% under a combination of metering device rotation speed of 30 r/min, negative pressure of 1.0 kPa, and suction hole diameters of 1.5 mm. High-speed photography was used to study the trajectory of seed-metering at different rotation rates, a locomotive axis was applied to fit the motion curve, and 3D-printing was used to make the seed-metering tube so that the seed collisions could be reduced. This study provides evidence for further optimizing the performance of the vacuum central drum direct-seeding machine for hybrid rice.
Highlights
Rice-planting mechanization is an important part for realizing the complete mechanization of rice production
To improve the level of lightened and simplified mechanization of hybrid rice seeding in China, this paper adopted a combination of theoretical calculation, parametric design, and a bench test to design a vacuum central drum seed-metering device
The test results show that the developed metering device can meet the design objectives, reducing the number of conventional seed-metering devices, and high demanding for vacuums
Summary
Rice-planting mechanization is an important part for realizing the complete mechanization of rice production. Rice-planting mechanization mainly includes three patterns: mechanized transplanting, throwing, and direct seeding. Chinese mechanized direct sowing technology of rice has achieved significant development in recent years, of which the precision rice hill–drop drilling technology has been promoted over a wide area due to its advantages of saving time and work, well ventilated fields, fewer pests, low tillering node in rice, and even uniform growth [1,2,3,4]. Hybrid rice, owing to its features of strong tillering ability and high production, has obtained a wide popularization in China. Current mechanical seed-metering devices are mainly designed for medium or large seeding amount requirements, which makes it hard to meet the technical requirements of precise seeding of hybrid rice. Vacuum seed-metering devices are suitable for precise seeding due to its characteristics of less bud damage and strong adaptability to the dimensions of rice seeds
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