| Qinghai province,as the dominant area of spring rape planting in the north,still basically follows the traditional manual labor mode and the semi-mechanical segmented harvesting method such as cutting first and then removing,with a relatively low level of machine harvest.There are few rapeseed combine harvesters,and most of them are modified models of rice and wheat combine harvesters.Due to the different biological characteristics of plants,there is no in-depth and detailed research on the characteristics of rapeseed.Therefore,the performance is not perfect enough.Therefore,the development of high efficiency,low loss rate,strong adaptability of rapeseed combine harvester is imminent.This topic in view of the rape planting mode of Qinghai province,the working environment,and the characteristics of rape plant and harvest rapeseed agronomic requirements,using theoretical analysis,computer aided design and computer simulation methods,such as paddy,wheat combine and draw lessons from the existing rape modified model,designed a loss rate and impurity rate double low rape combine of 4LZY-7.The main contents and results of this study are as follows:(1)Literature review and status recommend.On the basis of full investigation and literature review,the research status of rapeseed combine at home and abroad was introduced,and the existing problems of rapeseed combine were found out.For the problem that the loss rate is too high in the harvest process,a new design improvement scheme is put forward,the structure optimization and motion parameter optimization are carried out through field experiments,and the corresponding research method and technical route are given.(2)Analysis on the structure and characteristics of rapeseed combine harvester.Structural design and parameter calculation are carried out for the key parts of rapeseed combine harvester,such as the conveyance of the cutting platform,the cutting wheel,the longitudinal cutter,the connecting bridge,the double drum of threshing part,the screen of concave plate,the combination of the air screen ofcleaning part and its driving mechanism.On this basis,the working principle and power transmission route of the rapeseed combine harvester are described.(3)Dynamic analysis of the cutting process of longitudinal cutter.The dynamic analysis of the cutting mechanism using ADAMS software shows that the cutting displacement of the longitudinal cutting blade satisfies the condition that the cutting stroke is greater than the distance between the moving blades.The cutting speed of longitudinal cutting blade can meet the requirement of cutting characteristics of rapeseed stalk,and can finish cutting and dividing grain.(4)The static analysis of the cutting table frame is carried out.Based on the Solidworks-Simulation module,the static analysis and modal analysis of the cutting table frame are carried out to determine the installation position of the longitudinal cutter.Solidworks-Edition module was used to model the rapeseed cutting table,and then the Simulation module was selected for static analysis.Finally,the model was simulated and solved.The maximum stress of the cutting platform frame was concentrated on the support of the hydraulic device of the puller,which was about27.7Mpa,far less than the yield limit of the material,and the maximum displacement and deformation was 5.430 mm,located at the front end of the bottom plate.The frame of the cutting table meets the strength requirement as a whole,and the mounting position of the longitudinal cutter of the cutting table avoids the support of the hydraulic device of the puller.(5)The modal analysis of the frame is carried out.By analyzing the non-zero modes of the first ten orders of the cutting table frame,the natural frequency range of the first ten orders of the cutting table frame is within 30~113Hz,and both of them will cause bending deformation to the plates on both sides of the cutting table frame.In order to avoid mechanical interference and collision with the transmission mechanism installed on the left side of the frame of the cutting table,the position of the right side board with the smallest deformation was selected as the installation position of the five-bar longitudinal cutting mechanism on the plane of the cuttingtable.It is found that the excitation frequency of the power input crank of the longitudinal cutter is 8.74 hz,which is not within the natural frequency range of the first ten orders of the cutting platform frame,and no mechanical resonance will occur.(6)Field experiments were carried out to verify and analyze the prototype.The experimental data were recorded and range analysis and variance analysis were performed on the data.It is concluded that the biggest factors affecting the loss rate of the cutting table are,in turn,the advance speed of the machine,the rotation speed of the eccentric puller and the height of the eccentric puller shaft.To optimize a set of best parameter combination for the field test,the test results show that the harvester of overall performance is good,all the indexes can reach rape harvest machinery operation regulations,among them,cutting loss rate up to 2.35%,the grain total loss rate < 3.95%,the grain crushing rate < 0.5%,grain impurity rate < 2.8%,has realized the generation of prototype to achieve the goal... |
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