| Hybrid rice is a high-yield rice variety with good quality,which has been widely used and popularized in China.Its cultivation requires less planting and fewer seedlings,and tiller capacity is used to increase yields.The existing mechanized rice sowing technology is difficult to meet the requirements of precision sowing with low sowing number of hybrid rice.The improvedvarieties are not matched with high-yield cultivation technology,and the high-yield advantage of hybrid rice cannot be fullyexploited,which restricts the development of rice planting mechanization in China.Pot seedling transplanting possesses the advantages of light root injury,rapid rejuvenation,early tillering and large elasticity of seedling age,which solves the shortage of traditional machine transplanting and increases production significantly.In order to cultivate pot seedling of hybrid rice suitable for mechanized transplanting,and to meet the agronomic requirements of low sowing number precision seeding and the technical requirements of light and simplified cultivation,it is necessary to carry out the key technology research on light-economical pot seedling nursery machine,to realize the low sowing number precision seeding operation of hybrid rice,to improve the automation and intelligence of the production line,and to reduce the labor intensity of seedling raising degree.In this paper,the research background of precision seeding production line of rice seedling tray at home and abroad was analyzed,combining with the agronomic requirements of precision seeding of hybrid rice with low sowing number.The material characteristics of typical hybrid rice bud seeds were studied and evaluated based on the principal component analysis method,which provided data basis for the design and optimization of precision seeder;The design and performance optimization of the precision seeder for rice seedling raising with the intelligent double-filled hole drum were carried out by the means of theoretical analysis,EDEM simulation of discrete element and practical performance test.In order to solve the problem that the plate of soft plastic pot can not be directly placed or automatically stacked after covering the surface soil,and necessary for manually terminating the hard tray and waiting for the plate of soft plastic pot to be embedded before carrying out subsequent operations,existing technical problems of high labor intensity and low productivity,a kind of automatic inserting device of soft pot was developed And a precision seeding production line of light and simple hybrid rice was developed on the basis of the key technology research,and the performance test was carried out to provide a new device for mechanized planting of hybrid rice.The main research contents and conclusions are as follows:(1)Based on the principal component analysis,this paper studied the physical characteristics of typical hybrid rice bud seeds,constructing a scientific quantitative evaluation system,provideinng a new idea for the scientific evaluation of the physical characteristics of typical hybrid rice bud seeds,and layed a foundation for the parameter design and discrete element simulation of the intelligent double-filledg hole roller hybrid rice seedling precision seeder.Nine kinds of hybrid rice buds commonly used in South China rice areas were as test samples,eight physical property index parameters were measured,and the principal component analysis method was used to simplify the physical property indexes.A scientific quantitative evaluation system was constructed to obtain a comprehensive score for each sample.The results show that the mass of thousand seeds had a significant positive correlation with the angle of repose α and angle of repose β;the triaxial arithmetic mean particle size had a significant positive correlation with the angle of repose α and angle of repose β;Thousand～grain mass had a positive correlation with water content,triaxial arithmetic mean particle size,and sliding friction angle;water content had a positive correlation with bud length;hardness had a positive correlation with angle of repose α;bud length shows a positive correlation with angle of repose α,angle of repose β,and triaxial arithmetic mean particle size.Using the principal component analysis method to extract the first three principal component factors,the cumulative contribution rate reached more than 80%,which could represent most of the original eight physical characteristics indexes.Based on the test results,the evaluation criteria for the physical characteristics of nine kinds of hybrid rice bud seed samples were preliminarily determined,and appropriate evaluations were conducted.Cluster comprehensive analysis was utilized to analyze the comprehensive scores of the physical characteristics of the samples.Nine hybrid rice buds were aggregated into five categories,and the physical properties of the hybrid rice buds were different among the samples.The physical characteristics of hybrid rice buds were evaluated based on principal component analysis to provide data basis for the design and optimization of precision seeder operation parameters.(2)It is the first time to put forward the conception of photoelectric detection and prediction of holes in the first seed filling chamber and intelligent vibration refilling of the second seed filling chamber.By using the method of dynamic analysis,discrete element edem simulation and practical test,an intelligent double seed filling type precision seeder for hybrid rice seedling raising is developed.The test shows that the scheme of "intelligent double seed filling" can significantly improve the operation of the precision seeder When the productivity is 400 ～ 600 trays / h,the vibration frequency is 27 Hz,the qualified index of sowing is 90.2% ～ 91.9%,and the missed index is 1.8%～ 2.9%.According to the concept of "intelligent double seed filling",the whole structure and working principle of the seeder are described,and a hole seed filling performance detection and control system with PLC as the control core is built.Dynamic analysis and edem software were used to simulate the hole shape,the position angle and the productivity of the first seed filling chamber,and the best working parameters of the seeder were obtained.The experimental prototype was developed and tested.Three factors and three levels of orthogonal test were used to study the influence rule of the hole depth,productivity and the first seed chamber filling position angle on the experimental indexes.The results showed that the primary and secondary order of the factors affecting the seeding qualification index and the replaying index was:the depth of the hole > the productivity > the first seed chamber filling position angle;the primary and secondary order of the factors affecting the missed seeding index was:Productivity > hole depth > position angle of the first seed filling chamber;then the influence of different vibration frequencies on the test indexes was studied.Under the same production rate,with the increase of vibration frequency,the sowing qualified index decreased,the missed sowing index decreased,and the replaying index increased.When the productivity was 400～600trays / h,the vibration frequency was 27 Hz,the sowing qualified index was 90.2%～91.9%,and the missed sowing index was 1.8% ～2.9%,The test indexes meet the technical requirements of precision sowing with low sowing rate of hybrid rice.(3)Through the dynamic analysis of the laminated tray,the condition of ensuring the stability of the laminated tray was obtained,and the embedded hard tray suitable for the automatic operation of the light and simple cultivation tray was designed.The embedding process of the drive belt conveying the tray was analyzed by the functional principle,and the minimum linear speed and the minimum transmission speed of the drive belt required to ensure that the tray is embedded in the hard tray under different productivity conditions were obtained The length of the moving belt is 1.2m,which realizes the automatic inlay process integrating the inspection from the soft tray to the tray,the orderly supply of the hard tray and the effective inlay of the soft tray into the hard tray.The test results show that when the productivity is 400～600 trays / h,the success rate of inlay is 98.5% ～100%,and the seed exposure rate is 0.92%～1.33%.The dynamic analysis of the whole inlay and automatic conveying of the soft pot tray is carried out,and the structure and working parameters of the inlay hard tray,the automatic dropping mechanism of the hard tray,the inlay mechanism of the drive belt and the conveying mechanism are determined.Based on the Arduino programming environment,the design of the control system for the automatic feeding of the hard tray and the automatic inlaying of the soft tray is completed,which realizes the automatic inlaying process of the inspection from the soft tray to the tray,the orderly feeding of the hard tray and the effective inlaying of the soft tray into the hard tray.The test results show that when the production rate is 400 ～ 600 trays / h,the success rate of the inlay disc is 98.5%～100%,and the seed exposure rate is 0.92 %～1.33%,which meets the technical requirements of the actual operation of the device.The results laid a foundation for the automatic operation of the precision seeding production line of light and simple hybrid rice.(4)Based on the research of the key technologies of the production line such as intelligent double seed seeder and the automatic imbedding device of the soft pot,combined with the design requirements of the factory seedling raising technology,the light and simple precision seeder production line of hybrid rice with the combination of the subsoil laying,subsoil compaction,precision seeding,overburden and the automatic imbedding of the soft pot is developed.The test shows that the production line can be stable when the production rate is 500 trays /h.The qualified index of sowing was 91.1%,the replaying index was 6.2%,the missed index was 2.7%,and the success rate of inlay was99.3%,which met the requirements of precision sowing of hybrid rice with low sowing rate and pot seedling,and the automation level was improved.According to the requirements of Agronomy and mechanical design of hybrid rice seedling raising and sowing,the light and simple precision seeding production line of hybrid rice seedling raising by hole plate was determined,and the solid modeling of key components was carried out by using the virtual prototype technology Solid Works modeling software.In the virtual assembly environment,the whole machine model is checked by collision dry inspection,assembly position constraint processing,assembly path sequence simulation and system analysis.The trial production principle prototype was tested,taking the sowing qualified index,replaying index and the success rate of inlaying plate as the evaluation index,and the productivity as the test factor.When the productivity is 500 trays / h,the sowing qualified index is 91.1%,replaying index is 6.2%,missed seeding index is 2.7%,inlaying plate success rate is 99.3%,which meets the requirements of precision sowing agronomy of hybrid rice seedling in pot and low seeding rate and automation level With the improvement,the filling mode of "intelligent double filling seed" in the production line significantly improved the filling performance of each hole,and the seeding performance was improved.The adoption of the automatic inlay device of the soft pot plate facilitated the subsequent direct operation of the soft pot plate and reduced the labor intensity of seedling raising.The research results provided a new device for the mechanized planting of hybrid rice. |
PDF Full Text Request