Study On Seeding Performance Of Hole-wheel Seedmeter For Rape Under Vibration

Rapeseed is one of the four major oil crops in China with a wide planting area.It can be divided into winter rapeseed and spring rapeseed.Winter rapeseed is mainly planted in the south of the Yangtze River in China.Generally speaking,rapeseed is cultivated in the form of rice-rice-oil or rice-oil.Mechanical integration,including direct seeding,fertilization,shallow ploughing and stubble cleaning,is applied to rapeseed planting,which can simplify the rapeseed planting process and reduce the labor cost.However,during direct seeding,the seedmeter need finish shallow ploughing and stubble cleaning as well,which will bring great vibration to the seedmeter and affect its seeding quality.Considering this problem,this paper is based on a large number of relative literatures and take the double hole-wheel seedmeter for rape(2BYG-220 type)as the research object.Firstly,by testing and analyzing the vibration effect of the seedmeter in the field operation,the range of main vibration frequency and distribution of vibration amplitude were found,and taking this as a parameter to design a vibration test bench for seedmeter.The discrete element simulation method and bench test method were used for static testing on the seeding performance of seedmeter to verify the accuracy of the discrete element model parameters of the double hole-wheel seedmeter.The seeding principles and rational range of rotating speed of the hole-wheel seedmeter were determined.Secondly,based on conclusions of static testing on the seedmeter,the discrete element simulation method was applied to test and analyze the seeding performance of the seedmeter,and the relationship among the vibration frequency,amplitude and seeding performance was obtained.Finally,the parameters of the double hole-wheel seedmeter are optimized to improve the seeding performance of the seedmeter under vibration.The main conclusions can be drawn as follows:(1)Vibration test on the seedmeter in the field operation shows that the vibration power is mainly concentrated at 0～25Hz and the amplitude is mainly concentrated at 0～3mm.Based on the results of field vibration tests,the vibration seeding test bench of eccentric wheel-reset spring was designed and manufactured.The vibration seeding test bench can adjust the amplitude of 0～3mm by replacing the eccentric wheel with different eccentricity,and the vibration speed can be adjusted within 0～25Hz by using the frequency converter to adjust the motor speed,which lays the foundation for the bench test.(2)The discrete element simulation model of double hole-wheel seedmeter for rapeseed was established.The materials and impact parameters of the discrete element simulation model were calibrated by the repose angle experiment to ensure the accuracy of the simulation test.From the perspective of collision theory,the normal force generated by the particle collision determines the internal friction among the particles.(3)Based on the simulation and bench test for seedmeter,the rational rotating speed of the seedmeter is 30～60r/min.And the seeding quality per unit time has a tendency to decrease when the rotating speed is over 60r/min.When the seedmeter works with double rows of holes,the seeding performance is the better than the work with a single row of holes.The side plates will cause a tangential traction effect on the population of flow layers.The first row is so close to the side plates that the seeding quality per unit time will decrease and the seeding performance will get worse.(4)The amplitude has a little effect on the seeding performance of the double hole-wheel seedmeter for rapeseed,while the vibration frequency has a great influence on the seeding performance of the seedmeter.When the vibration frequency is over 10 Hz,the seeding performance of double hole-wheel seedmeter for rapeseed will get worse dramatically.To be specific,the seeding quality is decreased and the seeding uniformity variation coefficient is increased,and the two are linearly negatively correlated.The reason for this phenomenon is that the particle population is thrown away from the surface of the hole-wheel under vibration,and the seeds cannot be filled into the holes of seedmeter.(5)There is a linear negative correlation between seeding quality and seeding uniformity variation coefficient.The relational expression is y=-5.025x+83.468,and the fitting degree R^~2=0.72022.To meet the seeding quality requirements in the field operation,the seeding quality per unit time should be greater than or equal to 7.66g/min.(6)Under vibration,the throwing direction of the inner particle population in the seedmeter is vertical upward.To effectively block the throwing movement of the particle population,the ballast plate can be installed in the seedmeter,which can improve the seeding performance of the seedmeter under vibration.It can also make the article population close to the hole wheel,and the seeds can be filled smoothly into the holes of seedmeter.The seeding quality and seeding uniformity variation coefficient can be kept stable at the vibration frequency of 0～16Hz.