Study On Key Parts Of No-till Planter And Parameterization Design Method

The wind is strong; the drought and wind erosion is serious in spring in northeast China where maizeridge culture is the primary planting mode. The more excellent performance of no-tillage seeder is requiredbecause of the thick stubble and rough field surface. The present research on maize ridge conservationtillage technology is still weak; the no-tillage seeder suited for maize ridge is few; the study on key partsshould be enhanced. The theoretical analysis, experiments and parameterization design of the keycomponents have significance on improving the machine performance and design efficiency, shorteningdevelopment cycle and developing no-tillage seeder with high quality and reliability.Based on the analysis on conservation tillage technology and no-till seeders in China and abroad, theworking process of coulter was studied, the performance experiments of three disc coulters were carried out,the movement stability of working parts was analyzed. The critical technologies of parameterization designand automatic assembling of stubble-cutting components were researched and the corresponding systemwas developed, the parameters of seeder profiling mechanism was optimized by use of virtual prototypetechnology. The main conclusions are as following:(1)The condition that maize stalk on ground was cut off and not pushed forward was derived by forceanalysis and the minimum diameter of disc coulter used in no-tillage was determined. The change ofworking arc length and sliding cutting angle of coulter edge in the stubble cutting process was analyzed; theinfluence of coulter slipping on the sliding cutting angle and velocity of random point on edge was studied;the force models of coulter were built. This can provide theoretical foundations for designing and applyingdisc coulter.(2)The factors affecting the lateral displacement and velocity of working parts of no-tillage seederwere investigated. The results show that the increase of the unit velocity and the distance from workingparts to the axis of tractor driving wheel will increase them which make the machine tend to move offridge.(3)The force model and furrow depth stability model of no-tillage seeder equipped with four-barprofiling mechanism with tension spring were established. The influence of main factors on furrow depthstability was put forward which can be reference for the design of the machine.(4)The field experiments of smooth coulter, wave coulter and turbo coulter were conducted and theinfluence of additional weight and unit working velocity on cutting depth and furrow width was studied.The three-factor three-level orthogonal test of draft resistance was carried out which concluded the changeregularity of draft resistance to additional weight and unit working velocity and the order of all affectingfactors.(5)The parameterization design system of no-tillage stubble-cutting components was developed by thecombination of VC integrated development circumstance and underlying functions provided by Pro/Toolkit.The configuration of developing circumstance, menu and MFC dialog design, and the access of Pro/Toolkitapplication program to external database were studied. The case-based reasoning was applied in theparameterization design system; case representations, calculation of resemblance level and determination method for weight of characteristics properties were studied. The verification process shows that themethod can realize the reuse of design experience and results and improve design efficiency ofstubble-cutting parts.(6)The idea of virtual automatic assembling based on constraint coordinate system was put forward,the method of building constraint coordinate system and the steps of realizing automatic assembling wereanalyzed, and the program was completed. A method of virtual batch automatic assembling was proposedaccording to the situation that many stand parts such as bolts, nuts, and so on need to be assembledrepeatedly. The assembly constraint coordinate systems on a part and on many same parts were studiedseparately. The developed platform can finish automatic assembling of parts by interface operation, reducerepeated assembling work, improve design efficiency, and provide convenient means for the design ofstubble-cutting parts.(7)The virtual prototype of profiling mechanism was established with ADAMS software and themovement simulation was carried out. The influence of spring stiffness, preload and mass of seeder unit onprofiling wheel pressure was investigated. The parameters of profiling mechanism were optimized in thegiven working conditions with the objective function of minimizing the maximum profiling wheel pressure.The virtual prototype presents an effective method for the design and parameter optimization of profilingmechanism.