Development On Seperating-combined Header And Directional Conveying Device Of Rape Combine Harvester

Rape is one of the most important oil crop in the world and its planting area is biggest in China,accounting for 35% of the world.Mechanical harvesting is an appropriate way to improve harvesting efficiency and save labo.Therefore,rapeseed combined harvesting becomes one of research focuses in the agriculture machinery field.However,there are some problems for the adaptability of the rape combine harvester.4LYZ-1.8 harvester was developed to improve the adaptability of rape combine harvester.The harvester composes of separating-combined header,directional conveying device,longitudinal axial flow threshing and separating device,cyclone separating and cleaning system,hydraulic drive system,control system,travelling system and other components.The conceptual design,working principle and technical parameters of the machine were determined.The separating-combined header was designed to perform cutting,conveying and re-cutting,so it could cut the whole rape stalks into several short stalks to avoid winding and blocking in subsequent conveying and separating.An adjustable clearance mechanism was innovated on re-cutting conveyor to eliminate the problems of winding and blocking.Furthermore,a directional conveying device was designed to convey stalks from the head to threshing device,and then it was integrated with the longitudinal axial threshing and separating device,which could solve the problem of complicated and long conveying distance of chain harrow type conveyer on the traditional combine harvester.Finally,field tests were conducted to evaluate the machine performance.The main contents of this research were as follows:(1)Measurement and analysis of rape plant characteristics were conducted.Some measurements were carried out at plant harvest time,includeing: plant population,row spacing,plant spacing of rapeseed,plant height,plant mass,first branch height,bottom pod height,plant location of center of gravity,stem diameter at 350 mm height,maximum diameter of the pod layer,friction coefficient between stalk and mechanical parts.In order to improve adaptability of rape combine harvester,the 4LYZ-1.8 harvester was developed to suit planting density and different individual plant growth characteristics of rapeseed.The conceptual design,working principle and technical parameters of the machine were determined.Then,overall layout and power allocation of the harvester were determined.(2)A separating-combined header with the function of cutting,conveying,and re-cutting was developed.The structure and working parameters of re-cutting conveyor were determined,and mechanical modeling of re-cutting operation was established.The angle of conveyor knife was determined to be an inclined with 12.8? according to the maximum shearing stress theory.The length of linear cuter edge with 118-200 mm and base circle radius with less than 133.6 mm of involute cutter were determined,respectively.The relationship between conveying and re-cutting capability and the number of knives,geometric parameters and inclination angle was established,and then the distance between two adjacent knives was found to be 100 mm,whereas four knives were fitted in one pitch of the conveyor according to this relationship.An automatic clearance adjusting mechanism was designed for further adaptability improvement of feeding quantity.The mechanism could change the clearance between re-cutting conveyor and floor automatically when the feeding quantity was different.The maximum torque and displacement were 366 N and 50 mm by kinematics and dynamics analysis of the re-cutting conveyor,respectively.In addition,other parts and parameters including guiding cover,lifting hydraulic cylinder,length of header,reel were designed and their performance were also analyzed.(3)Performance experiments and simulation analysis of separating-combined header were conducted.Results of orthogonal experiments with re-cutting conveyor speed,feeding quantity and knife type as factors showed that when re-cutting conveyor speed was 200r/min,feeding quantity was 2 kg/s,and knife shape was involute,the re-cutting performance was optimal.During orthogonal experiments,a high-speed camera system was used to observe re-cutting process and moving path of the stems simultaneously.Then mathematical model between 4 experimental indexes and involute cutter base circle radius,installation angle were established.Parameters experiments on clearance adaptive adjusting mechanism were conducted using torque sensor and high-speed camera technique to measure torque on conveyor shaft and displacement,respectively.Its results indicated that when pretension was 293 N and stiffness coefficient was 12.65 N/mm,the maximum torque was 8.267N·m,decreasing by 40.7% and maximum displacement of the slider was 10.2 mm.When the adjustable mechanism on conveyor compared with non-mechanism,it reduced torque and increased maximum feeding quantity.Moreover,the maximum torque of the experimental group was smaller than that of the comparative group when feeding quantity was inconsistent.Flexible simulation on contact process between the reel and stalk was conducted based on ANSYS-ADAMS.Simulation results revealed that the optimized parameters of the reel;forward speed,reel speed and installation height were 1.2 m/s,30 r/min and 1200 mm,respectively.(4)A directional conveying device was designed and its optimal experiments were conducted.In order to achieve locating stalks in same direction and conveying them from header to threshing and separating device,the device was built to transport stems for short distance.The structure,working principle and parameters of the device were determined according to kinematics and dynamics theory,and its performance experiment was carried out with the passing rate of material as index.Then,an optimization and improvement of the device was conducted as to obtain smooth,efficient and i stalks-directed conveying.It was integrated with the longitudinal axial threshing and separating device.The axis of threshing cylinder and wheel was located vertically as T-shape.They could independently rotate without interference which simplified the structure.Experiment results declared that the improved directional conveying device and threshing device could successfully completed conveying,threshing,separating and other harvesting operation.(5)Bench performance experiments and field adaptability test were conducted.Re-cutting performance,test with no-load machine of hydraulic system and field functional test were carried out.Re-cutting performance showed that when rotational speed and feeding quantity were 200-400r/min and 0.5-1.5 kg/s,respectively,stems were cut into short stalks.No-load test of the hydraulic drive system showed that power consumption varied with the range of 6.8-8.7 k W,and the performance of hydraulic system was relatively stable.Field experiment results showed that stalks were firstly cut at 350 mm height from the ground and stubble height was stable.Re-cutting process was performed to cut the stems into shorts parts by re-cutting conveyor.Adjustable clearance mechanism could adjust the clearance between re-cutting conveyor and bottom plate in time according to the amount of feeding quantity during harvesting operation.The directional conveying device was capable of conveying,threshing and separating material.The structure and working elements of the harvester were fit well to match subsequent stages of harvesting which resulted in easy maneuvering and good adaptability.Results declared that the harvester could successfully satisfy the combined harvesting of rape.