Seeding Performance Test And Structural Optimization Of A Rapeseed Hill-seeding Centralized Metering Device Under Vibration-tilting Conditions

Rape centralized sowing is a light and simplified precision sowing method,and hill-seeding centralized metering device is the core component of precision sowing.This article aims at problems such as uneven seed supply,seed breakage,and low consistency of seeding in various rows when existing mechanical centralized sowing devices operate under vibration,tilt,and other conditions.Based on methods such as high-speed photography,DEM simulation,and bench testing,the impact of vibration and tilt conditions on the performance of the rape hole sowing centralized metering device is clarified,and the vibration and tilt conditions are adapted by optimizing the structural parameters of the centralized metering device.The main research conclusions are as follows:(1)Analysis of field vibration characteristics of rape seeder.By analyzing and processing the frequency domain signals collected by the seeder during field operation,the results showed that the frequency range sensed by the seeder was mainly concentrated in low frequency(0-60 Hz),medium frequency(70-110 Hz),and high frequency(120-180Hz),which was related to the rotational speed of the engine and rotary tillage device;At the same time,combined with the root mean square value distribution of vibration acceleration,the maximum vibration acceleration at low frequencies of 0 to 60 Hz is determined to be 14 m/s~2;The maximum vibration acceleration at the intermediate frequency of 70-110 Hz is 23 m/s~2;The maximum vibration acceleration at high frequencies of 120-180 Hz is 33 m/s~2.(2)Simulation experiments were conducted to investigate the effects of vibration and tilt on seed filling and metering performance.The simulation results showed that a vibration frequency of 10-40 Hz would lead to an increase in seed filling angle,significantly reducing the qualified rate of seed filling,and significantly exacerbating the change in seed speed;As the lateral inclination angle increases,the missing rate of seed filling and the height deviation of the seed layers on both sides increase;With the increase of the forward inclination angle,the seed filling angle and the amount of seed filling decrease,and the missing rate of seed filling increases significantly;With the increase of the rearward tilt angle,the seed filling angle,the number of seeds filling,and the height of the seed layer increase,and the multiple rate of seed filling significantly increases.The seed filling performance and seeding performance are inversely proportional to the tilt angle.Applying vibration when tilting backward and sideways can exacerbate the impact of the tilt on seed filling,adding adverse effects and significantly reducing the seed filling performance.However,when tilting forward,vibration can exacerbate seed layer disturbances and thereby improve the seed filling effect.(3)Conduct bench tests on the impact of vibration,tilt,and other working conditions on seed filling and metering performance,the bench test results show that when the rotation speed of the metering wheel is 24 r/min,the vibration has a significant impact on the qualified rate of seed filling,the rate of missing seed filling,the rate of multiple seed filling,and the seed filling angle.At the frequency of 10-40 Hz,the influence of the longitudinal distance of the seed layer adjusting plate on the seed filling performance is significantly greater than the lateral distance.At 10 Hz,the increase of longitudinal distance can improve the qualified rate of seed filling.However,at 20-40 Hz,the higher longitudinal distance increases the rate of multiple seed filling,and then reduces the qualified rate of seed filling.By adjusting the longitudinal distance,the qualified rate of seed filling can be maintained above 91%.By installing a seed cleaning brush and adjusting the longitudinal distance of the seed layer adjustment plate under the vibration tilt coupling condition,the qualified rate of seed filling of the rape hole sowing centralized metering device is above 98.33%at other frequencies and tilt angles,except for 30 Hz vibration.(4)According to the size characteristics of rape seeds,a circular coated hole was designed,and the lateral seed filling method was optimized,the seed cleaning device was strengthened,the seed protection effect was improved,and the seeding effect of the distribution head was optimized.The main structural parameters of the seed-metering device are determined and the test is carried out.The results show that the distributor has a good seeding effect,and the average hole distance fluctuates slightly between 99.7-133.87mm.Determine the optimal rotation speed of the metering device as 24 r/min.The qualified rate of hole spacing at each frequency is higher than 80.01%,and the empty hole rate is lower than 8.88%.At the same time,the vibration will not affect the seeding performance under the inclined condition,but will be beneficial to the filling and seeding at this time,and can ensure the qualified rate of hole spacing≥83.89%.At the same time,there is no over seed filling and seed breaking phenomenon in the test.