Design of an active seed throwing and cleaning unit for pneumatic rice seed metering device

To address the clogging of the rice seed metering device after a long period of operation without affecting the precision of normal seeding,an active seed throwing and cleaning unit was designed based on the fact that magnets of the same pole were mutually exclusive.The working principle of the two devices was analysed theoretically,and a mechanical model was created according to the relationship between the repulsion forces of magnets and the spring forces of springs.The super hybrid rice Y-2 You 900 with 22.5%moisture content(wet basis)was used as the test object.The whole factor experiments were carried out under different negative pressures,rotational speeds of the suction plates,and lengths of probes.The results indicated that under any test conditions,the active seed throwing and cleaning unit worked normally.The results of high-speed photography showed that the rate of seed cleaning was 100%.The results also showed that the optimal negative pressure was 0.8 kPa.The probability of 1-3 seeds per hill for the seed metering device was approximately 95%under the optimal negative pressure.The optimal length of the probe was found to be 2 mm.The average qualified rate of hill space was 96.04%under the optimal length of probe,the longer the length of the probe,the lower the qualified rate of hill space.It also showed that an active seed throwing and cleaning unit could effectively avoid the hole clogging caused by the long-term operation and had no influence on the normal operation of the pneumatic rice seed metering device.The active seed throwing and cleaning unit improved the stability of the seed metering device,and the research provided a reference for the optimal design of seed throwing and cleaning structures of the pneumatic rice seed metering device.

Design and experiment of seed furrow cleaning device based on throwing and sliding for no-till maize seeding

In order to solve the serious problems of seeds are covered by residual film and overhead by straw during no-till seeding,a seed furrow cleaning device for no-till maize seeding was developed,which adopted a collaborative cleaning method of rotating spring teeth and curved sliding shovel.The movement process and motion trajectory of throwing residual film and straw were constructed.The maximum distance of throwing to one side in horizontal and maximum height in vertical were obtained.The motion trajectory of adjacent spring teeth was analyzed by Matlab,the motion trajectories of adjacent spring teeth at different speeds of 120 r/min,150 r/min and 180 r/min were achieved,the theoretical analysis results showed that the area of omitted area decreased with the increase of rotation speed.Based on theoretical and simulation analysis of critical parameters,the forward speed of machine,rotation speed of spring teeth,and dip angle between spring teeth and rotary disc were selected as the influencing factor.Straw cleaning rate(SCR)and residual film cleaning rate(RFCR)were selected as the response values for three factors and three levels of orthogonal experiment design.The optimal combination of the selected parameters was obtained,and the field test verification was also conducted.The results showed that the rotation speed of spring teeth,forward speed and dip angle of spring teeth significantly affect SCR and RFCR were in decreasing order.The field test results indicated that when forward speed was 6 km/h,rotation speed of spring teeth was 180 r/min and dip angle of spring teeth was 40°,SCR and RFCR were 88.27%and 84.31%,respectively.This study provides a reference for the development of no-till seeder in Xinjiang and the northwestern regions of China.