Design And Experiment Of Rice Seed Metering Apparatus With Gradient Hole Depth And Low Loss

Aiming at the problem of bud seed damage in rice seed metering apparatus,a rice seed metering apparatus with gradual hole depth and low damage was proposed.Theory study,gas-solid coupling simulation and bench test,analysis of CAM plunger variable structure type and hole depth,using the structure features of the piston radial sliding slightly in seed filling and cleaning were,with a kind of kind of adaptive phase type hole depth and shots,research-based hole depth,the working process of the low creep damage of rice seed metering device,implements rice shoots,reduce the damage of purpose.The main research contents are as follows:(1)The rice varieties huanghuazhan,Xiangliangyou 600 and Yliangyou 203 commonly used in the rice growing areas of the middle and lower Reaches of the Yangtze River were selected as the research objects.The physical and mechanical characteristics of bud were determined,such as 1000-seed weight,density,moisture content,friction coefficient and recovery coefficient.The effects of seed attitude and variety on the deformation and ultimate load of rice bud were obtained by compression test.The experiment of rice germination rate of Xiangliangyou 600 was carried out,and the limit load of sprout seed satisfying the requirement of minimum agronomic germination rate was obtained.(2)Double-layer filling structure of rice seed metering device with gradual hole depth and low loss;By analyzing the key parameters such as drum diameter,suitable speed and pitch,the chamfering Angle of the shaped hole is 37°,and the diameter of the suction hole is 4.4mm.For the purpose of smooth running of end cover groove line and avoiding interference of parts,the function expression of end cover track groove and radial running rule of piston are clarified.The movement law of seed filling,seed cleaning,seed carrying and seed dropping was analyzed.Based on the basic theory of circular section jet flow,the limit distance between seed cleaning nozzle and mold hole was 46.2mm.(3)EDEM and Fluent software were used to simulate the flow field of the parallel assembly mode and the staggered assembly mode of the seed metering piston.The results show that the parallel assembly mode is better,and the flow tends to be stable when the center of the white steel rod is 5mm from the end face.The analysis of the seed cleaning flow field of the seed metering device shows that the action form of the seed cleaning air flow and the shorter the action time of the seed cleaning air flow are.The adsorption law of buds in the roller seed metering device was obtained by gas-solid coupling simulation.(4)The bench test of rice seed metering apparatus with gradient hole depth and low loss was carried out.The single factor test and multi-factor optimization test were carried out with the roller speed,inner negative pressure and seed cleaning air flow as the test factors,and the seeding index of bud seed as the test index.The single factor test showed that when the rotation speed was 10r/min～15r/min,the negative pressure in the cavity was 4k Pa～4.5kpa,and the positive pressure of clear seed was 3.5kpa～4k Pa,the seeding index was above 85%.Multi-factor optimization test of seed metering device shows that:The primary and secondary factors affecting the qualified index were speed,negative pressure and positive pressure of seed cleaning.The best working parameters obtained by fitting the equation were speed of 10r/min,negative pressure of 4.37 kpa and positive pressure of seed cleaning of 3.89 kpa.At this time,the qualified rate of seed metering device was 85.39%,replay rate was 7.7% and missed rate was 6.91%.On this basis,the experimental results showed that the germination rate of the rice seed metering device with gradual hole depth and low loss was 97.3%,and that of the pneumatic roller seed metering device with gradual hole depth and low loss was 94.7%.