| Based on the systematically researching the development of rape combined harvesting technology and equipment at home and abroad,a combined cutting and throwing longitudinal axial flow threshing and separating device was designed to solve the problems like long transport distance and high probability of blockage in threshing device due to the low adaptability of the chain conveyor to rape with high and thick stalks in traditional rape combine harvester.The functions of forced feeding,cutting,throwing,threshing and separating were combined,and it could meet the operation demand of the rape combine harvester and shorten the material migration route.This study provides a reference for the optimization of the structure and working parameters of the rape combine harvester.The main research contents of the thesis are as follows:(1)The overall analysis design of the rape combine harvester and the design of its key components'structure were developed.The 4LYZ-2.0 type rape combine harvester consists of the header,the combined cutting and throwing longitudinal axis flow threshing and separating device,the cyclone separation and cleaning system,the hydraulic drive system,etc.,which realized the functions of cutting and conveying,forced feeding,cutting and throwing,threshing and separating,cleaning and separating,and power support respectively.The working process and route of the rape combine harvester are described.The basic technical parameters of the rape combine harvester are determined:2000 mm for the cutting width,the average field operation speed is greater than 0.9 m/s,the feed rate is greater than 2 kg/s,the productivity is greater than 0.65hm~2/h.At the same time,the layout design of the whole machine was carried out.(2)The design and analysis of the combined cutting and throwing longitudinal axial flow threshing and separating device for rape combine harvester and its key components were carried out.The overall structure of the combined cutting and throwing longitudinal axial flow threshing and separating device was described and it could be divided into three stages:grasping and feeding,cutting and throwing,threshing and separating,according to the material working process.The diameter and rotational speed of feeding roller were determined to be 150 mm and 500 r/min respectively according to the kinetic analysis of the rape stalks.According to design of the cutting cylinder with the function of cutting off the stalk and throwing material,the relevant structural parameters and working parameters were determined by analysis.It's concluded that the cutting cylinder's diameter is 400 mm,the blade angle is 21°,the installation anteversion angle is50°,the installation clearance angle is 19°,and the rotation speed range is 414~552 r/min.Through the force analysis of the material,the rise angle of the helical blade on the threshing drum is 18°,the outer diameter of the helical blade is 460 mm,and the pitch is300 mm.According to the requirements of rape feed rate and threshing and separating,the total length of the threshing cylinder is 2220 mm,the diameter is 450 mm,and the number of nails is 102,the speed range is 424~679 r/min and the threshing clearance can be adjusted by 20~30 mm.In order to increase the separation rate,a woven sieve concave boult is used with it's concave angle is 180°,and the mesh size is 5 mm×5 mm.According to the size of the threshing cylinder,the height of the baffle is 35 mm and the radius of the top cover is 260 mm.(3)The design of the throwing cover and the simulation of the airflow field were carried out.SolidWorks is used to build the three-dimensional model of the throwing cover and the cutting cylinder which is imported into Flow Simulation to build the air flow field simulation project.Through the analysis and comparison of the air velocity contour,air flow rate and air flow trajectory of different outlet height of the throwing cover,it is concluded that when the outlet height of the throwing cover is 200 mm,the air flow conveying performance is optimal.At the same time,the comparison of the air flow field in the curved cover and the linear cover shows that the internal pressure of the linear cover is slightly lower than the inlet port pressure,which is beneficial to grasping the crops and reducing the return loss.The airflow field in the outlet of curved cover is smoother and more stable.It's air volume is larger,and the eddy current zone is less,which has better airflow performance than the linear cover.(4)The single factor test research and analysis of the combined cutting and throwing longitudinal axial flow threshing and separating device were carried out.The threshing entrainment loss,the content of rapeseed and short stalks in the rape extractives,the total power consumption of the cutting cylinder and the threshing cylinder,and the average length of the stalks discharged from the straw outlet were used as test indexes for single factor tests of the threshing cylinder speed and the cutting cylinder speed.The conclusion indicated that the rate of detachment,the content of grain and short stalks in the rape extractives were parabolic with the change of the rotation speed of the threshing cylinder and the cutting cylinder,the total power consumption and the average length of the stalks discharged from the straw outlet were linear with the change of speed of the threshing cylinder and the cutting cylinder.The rotational speed of threshing cylinder and the cutting cylinder was 450~550 r/min in the subsequent orthogonal test.(5)The orthogonal test of the combined cutting and throwing longitudinal axial flow threshing and separating device was carried out.The orthogonal test of three factors and three levels was carried out by choosing the speed of the threshing cylinder?the cutting cylinder and the threshing clearance as the influencing factors.It can be concluded from the range analysis that the orders of main factors affecting the total power consumption and the average length of the stalks were the speed of the threshing cylinder,the speed of the cutting cylinder and the threshing clearance.The orders of main factors affecting the entrainment loss rate were the speed of the threshing cylinder,the threshing clearance and the speed of the cutting cylinder.The orders of main factors affecting the proportion of the short stalks in the exudate were the speed of the cutting cylinder,the threshing cylinder and the threshing clearance.The analysis of comprehensive scoring method shows that the optimal parameters were 450 r/min for the cutting cylinder speed,450r/min for the threshing cylinder speed and 30 mm for the threshing clearance.Under this combination of parameters,the entrainment loss rate was 0.415%,the mass percentages of short stalks in the threshing outlets was 10.43%,the total power consumption for cutting cylinder and threshing cylinder was 4.16 kW and the average length of the stalks discharged from the outlet of stems was 134.8 mm.The total loss rate and cleaning rate of the corresponding cyclone separation and cleaning system were 6.13%and 91.97%respectively.(6)The field experiment of rape combine harvester.The field experiment was carried out on the self-developed 4LYZ-2.0 type rape combine harvester showed that rape combine harvester has the expected functions and it runs smoothly.The combined cutting and throwing longitudinal axial flow threshing and separating device could realize the functions of grasping and feeding,cutting and throwing,and threshing and separating of the rape to be harvested in the field.Stalks blocked didn't appear in short-distance transportation.The average entrainment loss rate of the threshing cylinder is 2.41%,the average loss rate of the cleaning system was 7.83%,and the average cleaning rate of rapeseed is 87.65%,which can meet the field working requirements of the rape combine harvester.This study was innovative in the design of the combined cutting and throwing vertical axial flow detachment device for rape combine harvester,which provides a reference for the optimization of the structure and working parameters of the rape combine harvester. |
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