The Structure Optimization And Test Of The Key Components Of The Tobacco Stalk Puller Crusher

Tobacco stalks are directly discarded in the field or burned,which will give rise to soil,environment and water pollution and impact growth and output of tobacco stalks in the next year.Thus,comprehensive utilization of tobacco stalks is urgent,in which tobacco stalk collection is a key link.Due to the restriction of tobacco stalk collection cost,it is difficult to achieve efficient comprehensive utilization of tobacco stalks.The collection link involves stalk pulling,transportation and crushing links,etc.The existing agricultural machines can mostly handle a single link,and such problems as low efficiency of stalk pulling and transportation exist.Therefore,a mobile tobacco stalk pulling and crushing machine(the first generation of prototype)was researched and developed by the research group in the early stage,which can accomplish tobacco stalk pulling,transportation,crushing and collection at one time,and effectively resolve the major problems of original tobacco stalk collection equipment in tobacco stalk collection process.However,the machine still has some problems in the field operation,including overweight,large vibration,high power consumption and stalk blockage at a high speed.In order to solve the above problems,theoretical analysis,simulation and experiment were combined to study vibration characteristics and vibration mitigation measures for the first generation of tobacco stalk pulling and crushing machine during the field operation.Meanwhile,an experimental platform was set up to investigate and improve the critical component.On this basis,the overall design scheme of the second generation of tobacco stalk pulling and crushing machine was proposed.Finally,lightweight design,prototype trial-manufacture,analysis of dynamic and static characteristics,vibration verification test and field operation performance test were carried out for the second generation of tobacco stalk pulling and crushing machine.The main research work is as below:(1)For the first generation of tobacco stalk pulling and crushing machine,the eccentric structure design of crushing mechanism and transmission mechanism,and the rigid connection between each working part with the frame cause the vibration problem.To solve this problem,DH5925 dynamic signal test system was used for vibration test and analysis of 8measurement points under 5 working conditions,including no load of tractor engine under idling and full accelerator conditions,no load of the whole machine and stalk pulsing operation in the field.The distribution rules of time-domain characteristics and spectrum characteristics of corresponding vibration were obtained.Through analysis ofroot-mean-square value of vibration acceleration and vibration frequency,the reason why the first generation of prototype vibrated at each direction was gained,and the corresponding vibration attenuation design scheme was proposed.(2)For the problems of stalk blockage and high power consumption of transmission mechanism of the first generation of tobacco stalk pulling and crushing machine at a high speed,a new rubber transmission double-roll with adjustable space which is easy to dissemble was designed on the basis of analyzing the reason for stalk blockage.Through kinetic analysis,the mathematical model of stress deformation and transmission power consumption under extrusion and transmission stage of stalks was gained.And,the test platform for the transmission mechanism of tobacco stalk pulling and crushing machine was set up for orthogonal rotation combination test to study the influencing rule of transmission double-roll design on stalk blockage and power consumption.Finally,the optimized design scheme and design parameters of transmission mechanism were acquired.(3)Based on the improved design scheme of the first generation of prototype,the entire design of the second generation of tobacco stalk pulling and crushing machine was completed.The complete machine mainly comprises the knife roll for stalk pulling,clamping fed double-roll,transmission mechanism composed of chain net conveyor and double-roll at the feeding opening,drum crusher and machine driven system,and vibration dampers are added at each connecting piece.On this basis,structure parameter analysis and kinetic analysis were performed for the knife roll for stalk pulling,transmission mechanism,crusher and other critical components to investigate rationality and feasibility of the structure design scheme.(4)In a bid to gain a lighter second generation of tobacco stalk pulling and crushing machine with more stable working performance,to lower the mass,maximum deformation and maximum stress was taken as the optimization objective under the preconditions of no resonance and meeting lightweight design.Topological optimization and multi-objective optimization based on genetic algorithm were applied to carry out lightweight design for the frame and support structure of transmission part of the second generation of tobacco stalk pulling and crushing machine.Moreover,the second generation of prototype was produced according to the design results.On this basis,the vibration verification test was implemented for the second generation of prototype to study the vibration conditions and resonance problem,etc.(5)To test structure design rationality and prototype working performance of the second generation of tobacco stalk pulling and crushing machine,the field performance test and working parameter optimization study were conducted for the second generation of prototype.In the test,the unit speed,output shaft speed of the tractor,stalk pulling depth and revolving speed of the crusher were chosen as the experimental factors,and stalk omission rate and pass rate of crushing particle size were used as the evaluation indexes for single factor experiment to confirm the better operation level of each factor.Based on the single factor experiment,the combined test of quadratic regression and orthogonal rotation center involving four factors and five levels was carried out for the second generation of prototype,and the regression mathematical model of test indexes was established to explore the influencing rule of each experimental factor on the experimental indexes and the optimal operation parameter combination for the second generation of prototype.