Design And Experiment Of Picking And Crushing Device In Straw Feed Harvester

China’s straw resources feature large output,wide distribution,and rich nutrients.Reasonable use of straw resources can effectively avoid environmental pollution and resource waste caused by straw incineration.Straw forage harvesters can pick,cut,throw,and load straw.Currently,the picking and crushing devices of straw forage harvesters have such problems as substandard picking and crushing performance and high energy consumption.In response to the above problems,research on the performance of straw picking and crushing devices is carried out to optimize the key components of the devices.By analyzing the straw picking and crushing process with the discrete element method,the working parameters of the picking and crushing devices are optimized and verification tests are carried out.The research content and results are specified as follows:(1)The key structure of the picking and crushing device was optimized.Airfoil-shaped moving cutter blades were designed,which can efficiently crush straw with fixed cutter blades.The crushed feed can be directly fed to cattle and sheep,which improves the overall operating performance.Besides,the structure of the fixed cutter blades was optimized,and serrated edges of the fixed knife were introduced to crush the cortex of straw more effectively and improve the crushing performance.(2)The discrete element analysis method of the picking and crushing device was carried out and a straw model was established.By changing the structural parameters and working parameters of the machine,the influence of different rotational speeds and the number of fixed cutter blade holders on the operating performance of the machine was analyzed.A single-factor test was carried out on the rotational speed of the cutter shaft;after comprehensively considering the requirements of per ton power consumption and the dynamic balance requirements of the machine based on industry standards,it was concluded that a rotational speed between 1,600 r/min and 2,000 r/min can ensure satisfactory picking and crushing performance.Based on the single-factor test results,two-factor tests were carried out for different types of moving cutter blades,with the number of fixed cutter blade holders and the rotational speed of the cutter shaft as the test factors,the per ton power consumption and the rate of bond breakage as evaluation indicators,to obtain the optimal working parameters for the picking and crushing device when it was equipped with hammer claws and airfoil moving cutter blades respectively.The results showed that when the rotational speed of the moving cutter blade was 1,600r/min and two sets of fixed cutter holders were installed,the performance was relatively fine.The effect of each factor on the c performance was obtained by ANOVA and verified that there is some advantage of the wing-shaped dynamic blade in the working process.(3)Based on the simulation results,a bench test of crushing performance was conducted,and the test data were compared with the simulation data,and the average error of the per ton power consumption was 4.68%,which verified the accuracy of the simulation.The straw filamentation rate and bond breakage rate were fitted to analyze the correlation between them,and the optimal operating parameters of the picking and crushing device were derived with reference to the simulation results,and the machine worked better when the speed reached 1600 r/min and two sets of fixed knives were installed.Meanwhile,comparing the two types of movable knives,it can be seen that under the optimal working parameters,the tonnage power consumption of the hammer claw is8.41 k W·h/t and the straw shredding rate is 92.23%,while the per ton power consumption of the wing-type movable blade is 5.03 k W·h/t and the straw shredding rate is 91.17%,and the wing-type movable blade effectively reduces the energy consumption while ensuring the shredding rate.The results of this research can provide reference for the design of key components and setting of working parameters of straw forage harvesters and have positive significance for the utilization of straw resources.