| Castor is an oil crop with regional characteristics in Inner Mongolia and is an important strategic resource for national defense under the special international situation.However,due to significant differences in botanical characteristics among its varieties,mechanized harvesting of its fruits proves to be challenging,resulting in a high loss rate.This issue has a detrimental effect on the development of the castor industry.To investigate the mechanism behind the loss of castor beans during mechanical harvesting and address the challenge of difficult harvesting caused by morphological differences among castor bean varieties,a comprehensive study was conducted on the morphological characteristics of castor bean plants.Experiments were carried out to analyze the impact and shear characteristics.Subsequently,a vibrating castor bean harvesting device was developed,and the main device parameters were designed and optimized.Additionally,relevant research on the working mechanism,indoor bench experiments,and field experiments were conducted,yielding the following research findings:Statistical analysis was conducted on the morphological characteristics of castor plants,including plant height,ear position,number of nodes,and stem diameter.Additionally,shear strength,impact strength,and maximum fruit yield of the castor stem were measured.The results of the statistical and analytical studies indicate that short stem varieties have an average height of 140 cm,whereas high stem varieties have an average plant height of 265 cm.The number of primary branches ranges from 3-4,with the thickest main stem measuring 4.24 cm.Shear and impact tests reveal that the blade shear angle significantly affects the shear load,while the impact blade angle and impact location have a significant impact on the test indicators(P<0.01).The maximum fruiting force was found to be 0.67 N,with an average maximum fruiting force of 0.51 N.Based on the morphological characteristics and agronomic requirements of castor,a comprehensive design and analysis of the castor harvesting device were conducted.Moreover,the design scheme of the castor bean harvesting device was improved,taking into consideration the harvesting of high stem castor beans and the trafficability requirements of multi-branch castor plants.An innovative combined harvesting method involving a belt shaking harvesting device and a clamping conveying bullet impact harvesting device was implemented,achieving excellent results in harvesting castor fruits of various varieties,including short,medium,and high.A vibration system model was established for the excitation device and castor plant,leading to the derivation of the system’s vibration equation.The study identified the excitation frequency and amplitude as the key factors influencing the inertia force of castor branches during the vibration process.A three-dimensional model of the castor plant was developed,enabling modal analysis and harmonic response analysis.The modal analysis revealed significant vibration amplitudes and deformation effects at frequencies of 3.1967 Hz,4.5779 Hz,13.5050 Hz,and 21.2700 Hz.The results from harmonic response analysis demonstrated that,when a single excitation force is applied,the overall vibration deformation and transmission effect are most favorable when applied at a ground height of650 mm.Similarly,when two excitation forces of equal magnitude are applied simultaneously,the most preferable effect is achieved when the forces are applied at ground heights of 650 mm and 2000 mm.Through the analysis of acceleration response,it was determined that the optimal excitation frequency ranges between 13-15 Hz.Indoor tests were conducted to validate the simulation results regarding vibration shedding characteristics.The cutting and conveying device underwent structural design,and the cutting mechanism of the castor stem was analyzed.Through dynamic analysis and simulation methods,the parameters of the disc cutting device,the upper and lower clamping and conveying device,as well as the spring and fruit stripping device were optimized.The research findings indicate that cutting resistance is directly affected by factors such as cutterhead thickness,rotational speed,feed speed,and diameter.Specifically,the thickness of the cutterhead is inversely proportional to the collision force and torque experienced by the castor stem during contact.The diameter and speed of the cutterhead,along with the forward speed of the unit,are directly proportional to the collision force and torque when in contact.A paddle-type elastic fruit stripping element with a paddle length of 480 mm has been determined to meet the strength requirements of harvesting operations.For the upper and lower clamping conveyor,the center-to-center distance(LX)should be ≥435mm,the chain inclination(ab)should be 25°,and the center distance(b)of the drive chain should range between 164-184 mm.Additionally,the lower limit value for the diameter of the castor stem has been defined.An experimental platform for castor vibration harvesting was constructed,and indoor experiments were conducted.To evaluate the shaking recovery rate,an orthogonal experiment was designed,considering the factors of trolley forward speed,motor speed,and counterweight quality.The results revealed that both the trolley forward speed and motor speed had a significant impact on the shaking recovery rate(P<0.01).Similarly,orthogonal experiments were designed with recovery rate as the evaluation index and cutter head diameter,cutter head speed,and forward speed as factors.The results indicated that cutter head diameter and cutter head speed significantly influenced the recovery rate,while forward speed also had a significant impact(P<0.01).Subsequently,a vibrating castor harvesting device was developed,and field experiments were conducted.The findings demonstrated that for mature castor plants with a moisture content of 15%-20%,the harvester’s loss rate ranged from 5.1% to 6.1%,with an average value of 5.62%.The impurity content ranged from 4.9% to 5.5%,with an average value of 5.22%.Additionally,the damage rate was found to be between 2.1% and 3.1%,with an average value of 2.58%.These results were in compliance with the standard for "Operation Quality of Castor Harvester."... |
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