Study On Soybean Harvesting Crushing Mechanism And Low Damage Harvesting Technology

Soybeans are important grains and oil crops in China.In 2022,the sown area of soybeans in China reached 154 million acres,with a total yield exceeding 20 million tons.Harvesting is an important factor in determining the actual yield of soybeans,and it is also a weak link in China’s soybean mechanization production.Currently,the overall level of soybean harvesting in China is relatively backward,and the mechanized harvesting rate of soybeans is about 82%.There are quality problems such as large machine harvesting losses and serious grain damage.This article focuses on the main operational quality issues faced by soybean machine harvesting,starting from the study of soybean crushing mechanism and the development of low loss harvesting technology and equipment.It combines experimental analysis,theoretical analysis,simulation calculation,and experimental verification to carry out research on the causes and influencing laws of soybean machine harvesting crushing,as well as the process of soybean seed transportation and threshing movement.Based on this,a low loss soybean conveying system and a low loss threshing system have been developed.At the same time,key technology research and component development were carried out to address the issues of soybean loss and fragmentation during the header,cleaning,and unloading processes.Low loss soybean harvesting equipment was integrated and developed,and field performance experiments were conducted.The main research content is as follows:（1）A study on the mechanical properties of soybean seed tissue was conducted,and the elastic modulus,crushing force,crushing deformation displacement,and crushing energy of Qihuang 34 and Wansu 01-15 were experimentally measured.The results showed that there were significant differences in the elastic modulus,crushing force,and crushing energy of different soybean varieties.The elastic modulus,crushing force,crushing deformation displacement,and crushing energy values of the navel and embryo of the same soybean variety were smaller than those of the seed coat and cotyledons,The navel of soybeans is more prone to breakage under stress.The experiment measured the elastic modulus,crushing force,crushing deformation displacement,and crushing energy of Qihuang 34 at moisture content of 12.10%,18.90%,22.40%,and 26.70%.The results showed that the mechanical properties of soybean grain tissue were significantly correlated with moisture content.As the moisture content increased,the resistance to deformation and crushing ability of soybean seeds decreased.（2）Aiming at the problem of serious damage in the process of soybean harvesting and production,this paper analyzed the soybean harvesting process,and determined the main crushing forms of soybeans:epidermal breakage,splitting into two flaps,and overall crushing.The influence of different operation links on soybean crushing during the harvesting process,such as cutting table feeding churn,horizontal seed spiral conveyor,horizontal miscellaneous residue spiral conveyor,and threshing roller was studied.The influence of the operating parameters such as the forward speed of the harvester,threshing roller speed,and deflector angle on the soybean crushing form was studied experimentally.The results showed that,the degree of influence on the proportion of sepidermal breakage from high to low was the forward speed of the harvester,deflector angle and threshing roller speed.The degree of influence on the proportion of splitting into two flaps from high to low was the deflector angle,threshing roller speed and the forward speed of the harvester.The degree of influence on the proportion of the overall crushing from high to low was the forward speed of the harvester,threshing roller speed and deflector angle.The research results can provide a reference for the subsequent structural improvement of soybean harvester and optimization of operating parameters.（3）Study the mechanism of soybean seed crushing during the transportation process,establish a digital characterization model for the movement and force of soybean seeds during the transportation process,determine the structural parameters of the transportation mechanism and the influence of motion parameters on soybean seed movement,and provide theoretical basis for the optimization and innovation of the transportation mechanism.We conducted research on the motion process of soybean spiral conveying,used the single particle method to analyze the dynamics of soybean spiral conveying,studied the force state of soybean seeds during the horizontal spiral conveying process,and established a force model for soybean seeds during the horizontal conveying process;The single particle method was used to analyze the force on soybean during vertical transportation,and the force models of soybean seeds under low speed and high speed operation of spiral transportation were established respectively.Established models for the axial and radial velocities of soybean seeds during horizontal and vertical spiral conveying processes,and analyzed the relationship between soybean seed motion velocity and spiral blade radius,spiral conveying shaft speed,and spiral blade pitch.In response to the serious problem of soybean seed damage during the spiral conveying process,a research on the soybean seed pneumatic conveying system was carried out.A soybean seed pneumatic conveying device was developed and parameter optimization experiments were conducted.The experimental results showed that the influence of experimental factors on the conveying crushing rate was in descending order:the speed of the threshing drum,the forward speed of the harvester,the threshing gap,and the angle of the guide plate,The influence of experimental factors on the threshing and crushing rate is in descending order:fan speed,conveying duct sidewall angleα_S3.Feed rate and conveying duct sidewall angleα_S4.The optimal parameter combination for the pneumatic conveying system was determined through experiments as follows:feeding rate 2kg/s,fan speed 2500r/min,and conveying duct sidewall angleα_S3is 35°,and the angle of the side wall of the conveying air ductα_S4is 40°.（4）Study the mechanism of soybean seed breakage during the threshing process,establish a digital characterization model of soybean seed motion and force during the threshing process,determine the structural parameters of the threshing system,and the influence of motion parameters on soybean seed motion,providing a theoretical basis for optimizing the soybean threshing system.Studied the stress state of soybean threshing,established a maximum stress model for collision compression between soybean seeds and threshing components,and constructed a critical motion velocity model for soybean seeds under low crushing conditions.Analyzed the motion state of soybean seeds in the spiral feeding space,concave threshing separation space,cover plate threshing separation space,and arch tooth threshing space,established the axial and radial motion velocity models and motion differential equations of soybean seeds.The process of soybean threshing was analyzed through high-speed photography,and its motion trajectory,velocity,and acceleration were quantitatively analyzed.Taking the soybean separated from the concave sieve after threshing as an example,the changes in x-axis and y-axis displacement,motion velocity,and acceleration were studied.The effects of different feed rates and different threshing drum speeds on the motion status of soybean seeds were studied.The motion trajectory,absolute motion velocity,and absolute motion acceleration of soybean seeds were analyzed under the feed rates of 1.0kg/s and 1.5kg/s,as well as the drum speeds of 350r/min and 450r/min.We conducted research on a soybean low loss threshing system,developed a bow toothed threshing drum,a guide plate angle adjustment mechanism,and a circular hole concave screen.We integrated and developed a soybean low loss threshing system and conducted parameter optimization experiments.The results showed that the influence of experimental factors on the entrainment loss rate was in descending order:threshing drum speed,harvester forward speed,threshing gap,and guide plate angle,The influence of experimental factors on the threshing and crushing rate is in descending order:the speed of the threshing drum,the forward speed of the harvester,the threshing gap,and the angle of the guide plate.The optimal parameter combination for the threshing system is:the forward speed of the harvester is 1.2m/s;The speed of the threshing drum is 300r/min,the angle of the guide plate is 38°,and the threshing gap is 30mm.（5）Research on soybean low loss harvesting technology,carry out research on soybean machinery interaction mechanism in header,cleaning,grain unloading and other links,innovate key operation components,optimize motion parameters,and provide component support for the creation of soybean low loss harvesting equipment.According to the characteristics of soybean pod explosion at maturity stage,the soybean reel operation process was analyzed,the reel structure and motion parameter solving model was established,and the reel radius,reel speed ratio,reel speed and other parameters were optimized;According to the characteristics of low pod setting and easy to shovel soil during harvesting,the statistical law of soybean grain size parameters was analyzed,and the soil filtering mechanism of header and intermediate conveyor was optimized.The cleaning device and pneumatic grain unloading device were optimized according to the characteristics of soybean easy to be broken;According to the harvest requirements of breeding plot,the digital design model of crank rocker mechanism of seed cleaning device was established,and the structural parameters of seed cleaning device were determined;According to the demand of low cutting profile of soybean,the interaction process between the profile mechanism of soybean harvester and soil was studied,the force and movement of the profile mechanism during the operation process were analyzed,the relationship model between the detection angle of angle sensor and the rotation angle of the profile mechanism was constructed,the mathematical model of soil compactness and compaction depth was established,the calculation model of header profile height was determined,and the header height control system of soybean harvester was developed.（6）The soybean combine harvester was created and the operation parameters were optimized to provide equipment support for the low loss and high efficiency soybean harvesting operation in the main production areas of China.The 4lz-1.5 soybean combine harvester was developed by integrating the key low loss harvesting technologies and components such as soybean mechanical harvesting and crushing mechanism,soybean low damage conveyor,low loss threshing system,low loss harvesting header,header height control system,cleaning system,pneumatic grain unloading device,seed cleaning device and so on.The performance tests were carried out in field and plot breeding scenarios.The results showed that the loss rate was less than 3.5%,the crushing rate was less than 1.5%,and the impurity content was less than 1%,The results showed that the 4lz-1.5 soybean combine harvester had good field harvest effect and could meet the requirements of low loss soybean harvest.The harvest test of 14 different soybean varieties was carried out in 3m×6m plot,and the test results were all achieved:loss rate<3%,crushing rate<1.5%,impurity content<1%,mixed seed rate<0.2%,seed clearing time range 200～270s,which met the requirements of harvest operation indicators in breeding plot.