| Rhizome medicinal materials are the main medicinal materials in China,and Chuanxiong is an important rhizome medicinal material.Sichuan Province accounts for more than 90%of the planting area of Ligusticum chuanxiong in China,and its market demand has increased significantly,while the corresponding harvesting machinery has developed slowly.At present,it is mainly harvested by manual excavation.The main reason is that there are many roots of Ligusticum chuanxiong,with fibrous roots and soil,It leads to the problems of difficult soil crushing and separation,easy soil blocking and difficult transportation during mechanized harvest.Therefore,the current rhizome medicine harvester cannot operate normally during the harvest of Ligusticum chuanxiong.At the same time,the root structure and harvest method of Ligusticum chuanxiong are representative,which can solve the problems of difficult soil crushing and separation,easy soil blocking and Provide basis for problems such as difficult transportation.Based on the analysis of the soil crushing and separation mechanism and transportation principle of rhizome crops at home and abroad,this paper puts forward a throwing and breaking soil separation technology.This technology is based on the crank rocker mechanism,combined with the growth soil characteristics and harvest mode of Ligusticum chuanxiong,establishes the test platform of throwing and breaking soil separation mechanism to test the physical characteristics of soil crushing,The working mechanism of the throwing broken soil separation mechanism is studied by means of theoretical analysis and experiment.The kinematics of the throwing broken soil separation mechanism,the breaking and separation of soil collision,the motion characteristics of the mixture relative to the vibrating screen,and the performance test of the throwing broken soil separation mechanism are studied.The main research contents are as follows:(1)Using the crank double rocker mechanism,a device for the separation of the throwing and breaking soil separation was developed,and an acceleration test platform for the throwing and breaking soil separation mechanism was built.The acceleration of the throwing and breaking soil separation mechanism at different speeds is measured,and the acceleration variation laws in different directions are obtained.The soil compaction and moisture content of the growth base of Chuanxiong were measured,and soil crushing tests were carried out with different depths and different moisture content as test factors.The crushing strength of soil is 1.33N/cm~2.The basic condition for deriving soil crushing and throwing is that the spindle speed of the throwing and crushing soil separation mechanism is greater than180r/min.Then it is concluded that the factors that affect the soil crushing and separation and the mixture throwing off the vibrating screen are the crank speed and the structure parameters of the throwing and breaking soil separation mechanism.For the crank speed and the structure parameters of the throwing and crushing soil separation mechanism,analyze the throwing and breaking soil separation mechanism,design the throwing and breaking soil separation mechanism,and finally determine the basic structural parameters of the throwing and breaking soil separation mechanism.(2)The kinematic model of the separation of the throwing and breaking soil separation mechanism is deduced by the closed vector method.Taking crank speed,crank radius and length of driving connecting rod as factors,displacement,velocity and acceleration are used as evaluation indicators,and Matlab software is used to draw displacement,velocity and acceleration curves.,using the orthogonal test to obtain the primary and secondary order of the influence of each factor on the evaluation index is crank speed,crank radius,drive connecting rod;using the Lagrangr method,to carry out the dynamic modeling of the throwing and breaking soil separation mechanism,Using D’Alembert’s principle,the equilibrium equations of inertial force and inertial moment of each connecting rod are obtained,the kinetic energy and potential energy of each connecting rod are deduced,and the dynamic model of the throwing and breaking soil separation mechanism is obtained.(3)The parametric modeling of the throwing and breaking soil separation mechanism is carried out by ADAMS software,and the optimization is carried out with the maximum acceleration value of the vibrating screen in the throwing and breaking soil separation mechanism as the objective,and the existence of the turnover pair of the crank-rocker mechanism is used as the constraint condition for optimization.After optimization,the acceleration amplitudes in the horizontal and vertical directions are increased by 89.7%and56.8%,respectively,and the relevant parameters of the throwing and breaking soil separation mechanism are finally determined.(4)Establish the movement model of the soil entering the vibrating screen,deduce the soil kinematics formula,establish the mechanical model of the soil collision vibrating screen,deduce the soil collision displacement response formula,use the Matlab software to draw the collision displacement response formula,and obtain that the displacement of the soil collision is 2.5～3mm,The collision time is 23.5ms,and the law of soil breaking and separation in the crank rotation period is obtained;the motion model of the vibrating screen is established,the kinematics formula of the vibrating screen is deduced,and the sliding condition of the mixture relative to the vibrating screen is derived,using Matlab to draw the movement speed curve of the mixture relative to the vibrating screen,obtain the movement law of the mixture relative to the vibrating screen,deduce the conditions for the mixture to be thrown away from the vibrating screen,the time of falling back to the vibrating screen,and the sliding time relative to the vibrating screen,and obtain:The mixture is positive relative to the vibrating screen.The sliding movement distance is greater than the reverse sliding movement distance,which meets the forward(backward)conveying requirements of the mixture and avoids blocking phenomenon.The movement process of the mixture relative to the screen surface of the vibrating screen is forward sliding,throwing away from the vibrating screen,hitting the vibrating screen,forward sliding,and reverse sliding.Forward sliding,reverse sliding;the mixture moves backward relative to the ground(the reverse direction of the forward direction of the Chuanxiong harvester)in the cycle is 0.286m,and the forward speed of the Chuanxiong harvester should be less than 1.644m/s.(5)Using ADAMS software to simulate the displacement,velocity and acceleration curves of the vibrating screen in the throwing and breaking soil separation mechanism,it is obtained:when the vibrating screen is located at two extreme positions,the theoretically calculated crank angle and the simulated crank angle error are respectively:0.7°,0.6°;EDEM software is used to simulate the separation mechanism of the throwing and breaking soil,and it is concluded that the required crushing force when the soil is broken is 5N,and the maximum speed after the soil is thrown away from the vibrating screen is 3.5m/s.The results of the theoretical analysis of the motion of the vibrating screen;the field test was carried out on the prototype,and it was found that the open stem rate of the Chuanxiong harvester relying on this mechanism was 95%,the loss rate was 4.5%,and the damage rate was 0.4%.The crank angles are 23.5°and 201.5°,respectively,which are 0.95°and 0.68°respectively from the theoretically calculated 24.45°and 202.18°.There is no stagnant soil phenomenon during the harvesting process.Throw the mixture backwards to verify the theoretical derivation and simulation analysis results. |
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