| The parallel operation mode of corn harvest and straw returning combines with no-till seeding is of great significance to the protection of soil.According to the regional characteristics of Heilongjiang,threshed mixtures cutting and throwing device which is connected with 4YZ-8 corn harvester,which is independently developed by Heilongjiang Machinery Engineering Scientific Research Institute,is designed.The method of combining theory analysis with virtual prototyping technology was used to study the device and the technology of straw crushing and returning to field,the working parameters of the device are optimized by the bench test,the better working parameters were selected to test the working performance of the device.The main contents and results are as follows:(1)According to the parallel operation mode of corn harvest and straw returning and the structural characteristics of 4YZ-8 corn harvester,proposing the design requirements of threshed mixtures cutting and throwing device,the integral structure of corn stalk with leftover cutting and throwing device is determined.(2)According to design requirements,designed the structure of smashing workshop.Detecting bug through the performance test of the first generation prototype,and reasonably planning and designing the structure of smashing workshop to overcome blockage.In order to improve the quality of smashing,the stability of operation and the uniformity of throwing,designing knife roller and determining the symmetry staggered arrangement by the theory of dynamic balance test.Designing cutting knife,fixed knife group,throwing plate group and the connecting mechanism structure through the theoretical analysis,the utility model has the advantages of simple structure and strong practicability,which satisfies the use function requirements of the device.(3)The finite element static analysis of the blade is carried out,and the equivalent stress nephogram and equivalent displacement nephogram are calculated.The structure of fixed knife can satisfy the requirement of strength.The modal analysis of the shell of the device is carried out,and the first 6 order modal shapes and natural frequencies are obtained,so as to avoid resonance phenomenon.(4)The 3D model of threshed mixtures cutting and throwing device was established.Under the condition of no interference,the full set of detailed engineering drawings of the device is completed.Producting three prototypes under supervising and prepared for test and performance test.(5)Regarding passing rate of cut corn stalk and power consumption as responsefunctions,regarding rotating knife velocity,thickness of knife,overlap of rotating and fixed knife as influence factors.Determining the effect of the experimental factors on the performance index through single factor analysis.The range of values of each experimental factor is obtained.The multi-factor interaction test was conducted on the corn stalk with leftover cutting and throwing device by central composite face-centered design method.Implementing variance analysis of test data by using design-expert software platform to obtain the regression mathematical model.The effect of the interaction between factors on the working performance of the device was analyzed by response surface methodology.(6)Optimizing multiple objective for regression model by the genetic algorithm NSGA-II,obtained the better working parameters combination that rotating knife velocity is 47.61m/s,thickness of knife is 4.8 mm,overlap of rotating and fixed knife is 30 mm,passing rate of cut corn stalk is 87.72%,power consumption is 6.21 kW.Verificating the optimal working parameters of threshed mixtures cutting and throwing device,passing rate of cut corn stalk is 86.55%,power consumption is 6.4 kW,relative error is 1.4% and 3.0% by comparing with the optimization results.According to the field working performance test,the passing rate of cut corn stalk is85.39%,the relative error of the optimized result is 2.73%,and throwing unevenness is 16.30%. |
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