Biomechanical properties of ready-to-harvest rapeseed plants:Measurement and analysis

A large loss occurs in the combine harvesting of rapeseeds due to the fragility of rapeseed pods,and all the more so with the vibration of the combine header and the collision between the header and plants.Seed loss is greatly affected by the biomechanical properties of ready-to-harvest rapeseed plants.To understand the mechanism of pod cracking and seed loss and to propose measures for alleviating them,it is needed to study the biomechanical properties of ready-to-harvest rapeseed plants.To this end,“Huayouza 62”,a widely planted rapeseed variety in central China,was selected to study the biomechanical properties,including pod-cracking resistance,main stem-shearing resistance and resonant frequencies,of whole plants.The results showed that the distribution of pod-cracking resistance forces was 1.333–6.100 N in the mature stage,and the pod width and thickness had a significant influence on the cracking resistance.The main influencing factor of the main stem-shearing resistance was the stem diameter.A thicker main stem resulted in a larger shearing resistance force but a smaller shear stress.The moisture contents of the main stems varied from 47.71%to 76.13%.However,the varying moisture contents did not show a significant impact on the shearing resistance.The resonant frequencies of whole rapeseed plants ready for harvest ranged from 6.5 Hz to 7.5 Hz,which was close to the excitation frequency of the cutter bar on the 4LL-1.5Y harvester.This study lays a foundation for improving the design and construction of harvesting devices for rapeseed plants to reduce seed loss.

Parameter matching and experiment of the combined cyclone separation and cylinder sieve cleaning system for rape combine harvester

Existing rape combine harvester with a cyclone separation cleaning device has the challenge that the loss rate and the cleaning rate increase and decrease simultaneously.A cleaning process route was proposed,which involves the cyclone separation cleaning device removing light and tiny impurities,and the cylinder sieve device removing coarse and long impurities such as pod shells and short stems.A novel cleaning system combining the cyclone separation cleaning device and cylinder sieve cleaning devices was designed.The ranges of the structure and operation parameters for each component were analyzed based on kinematics and dynamic analysis.A four-factor five-level quadratic orthogonal test was carried out,in which the loss rate and cleaning rate were taken as the evaluation indexes.The velocity at the suction port,the rotation speed of the cylinder sieve,the screw pitch of the spiral blade and the diameter of the sieve hole were taken as the influencing factors.The orthogonal test results showed that the cleaning system performed best at a rotation speed of the winnower is 600 r/min,an airflow velocity at the suction port is 18.25 m/s,a rotation speed of the cylinder sieve is 87 r/min,a screw pitch of the spiral blade is 440 mm and a diameter of the sieve hole is 4.48 mm.At this time,the loss rate of the cleaning system is 3.22%,and the cleaning rate is 95.67%.Compared to the conventional cyclone separation cleaning device,the loss rate is reduced by 2.17%and the cleaning rate is increased by 1.05%.This study can provide a reference for the optimal cleaning system design for rape combine harvesters.