Pod-picking Mechanism And Screening Characteristic Research For Bottom-feeding Four Rows Peanut Combine Harvester

Peanut is an important and high-quality oil-bearing crop with the greatest international competitiveness in China.In recent years,research institutions and companies developed several high-efficiency peanut combines such as the bottom-feeding four-row peanut combine(hereinafter referred to as the four-row combine),the pick-up multi-row peanut combine due to the planting area increasing and the large-scale production thriving.Peanut-pod picking and screening are the key technologies for the four-row combine,however,currently the working mechanism of the pick-up is ambiguous,and the optimization design method and basis for the screening structure are insufficient,which restrict the improvement for innovation and operation quality of the machine.Therefore,this paper was mainly to solve the above problems by means of taking the peanut-pod picking and screening mechanisms of the four-row combine developed by our research team as the research objects primarily.Then the important parameters such as basic information,geometric characteristics,water content,mechanical and biomechanical properties,and pods characteristics of peanut strains were obtained by researching on peanut strains characteristics closely related to mechanical harvest,and 11 typical peanut varieties in the main peanut producing areas in China were selected as research objects.Meanwhile an ACCESS database that had the functions of classification query and statistical analysis was built.Finally,a series of researches based on the above test data were carried out.A,the finite element model of peanut pod,flexible body model of peanut strains and dynamic simulation model of rigid-flexible coupling multibody were built.B,the finite element analysis of pod impact were carried out.C,the mechanical characteristics of pods at different impact speeds were studied.D,the dynamic simulation analysis of peanut pod picking operations under different parameters were carried out,in which the stress and movement behavior of peanut pods,the connection characteristics of the "seedling-stalkpod" were emphatically analyzed.E,the bottom-feeding test-bed for peanut pod picking integrated the high-speed photographic test system to study the separation process of pod-seedling under the above simulation conditions;to aquire the movement track and stress characteristics of pod;and to ascertain the production and influence mechanism of working quality.F,the single-factor experiment and the response surface tests of factors were carried out by combining with the above simulation and high-speed photography test to analyze the influence of each factor on the value of breakage and un-picked rate of pods and decrease them.The optimal parameters of factors as follow: the roller length was 850 mm;the included angle was 18o;the center distance of the double rolls was 200mm;the linear velocity of the blade outer edge was 4.8m/s;the clamp-transportation velocity was 1m/s.G,the peanut pods picked by the optimized pod picking device were analyzed by conducting the orthogonal and single factor test of restitution coefficient and friction coefficient of pod,in view of the phenomenon of pod impact,bouncing and friction occurred during the operation of vibrating screen.The influence law of different factors on the restitution coefficient of pod was studied and the friction coefficient between pod and different materials was determined.Moreover,on this basis,a new oscillating screen with lap-joint elastic steel pole without retardance was designed.The new screen was compared with traditional screens.the response surface tests of the related factors were conducted on the basis of theoretical analysis and single factor test to analyze the influence of each factor on the value of impurities and loss rate of pods.The optimal parameters as follow: the vibration frequency of elastic pole screen was 6Hz;the diameter of elastic pole was 3mm;the altitude of elastic pole screen was 7mm and the mounting angle was2.8o.The research achievements mentioned above provided a theoretical basis and a new method for the research and development of the bottom-feeding peanut picking and screening technology.After applying these research achievements to the four-row combine,the operation performance was effectively improved.