Design And Test Of Combined Straw And Stubble Crushing And Returning Machine

China is a large agricultural country with the highest grain output in the world.As one of the main by-products of grain production,straw is a kind of biomass resource with huge output and very valuable value.It is a low cost way to crush straw and return it to the field,at the same time,it can improve the quality of cultivated land and realize the sustainable development of agriculture.At present,there are still some problems in the mechanized straw pulverization and returning technology in China.1.the straw was not buried in time,after the sun exposure of water evaporation,nutrient loss,reduce the efficiency of the straw itself;2.the crushed straw is scattered to the ground,easy to ignite,easy wind,cannot fundamentally prevent the occurrence of fire;3.straw surface coverage is too large,and straw grinding degree is low,so that straw is difficult to carry out natural decomposition,and affect the late no-tillage sowing;4.The failure to effectively crush the underground crop stubble will not only affect the sowing but also affect the later crop growth.The straw pulverizing and returning machine generally adopts the position adjustment mode,and the machine and tools shake in the process of operation,which leads to the instability of operation.The roller part of the machine is relatively fixed,and the height cannot be adjusted.In view of the above problems,a combined straw and stubble crushing and returning machine is designed,which mainly includes:1.Combined with agricultural machinery agronomy,on the basis of existing models,determine the structure of the whole machine as a combination,to achieve a multi-purpose machine;As for the optimized design of the roller part,the working depth of the machine can be adjusted stepless through the roller.The transmission mode of the tractor adopts the method of combining belt and gear.By placing the belt pulley and gear box on both sides,the left and right weight of the tractor is balanced,and the torsion force generated by the tractor during suspension is reduced.Determine the parameters of the whole machine.2.Transmission gear,power input and output shaft design,calculation,check.The principle of straw pulverizer was analyzed and the combined blade was selected.On the blade arrangement,a single spiral line is used to meet the design requirements.The working principle of stubble mixer is analyzed and the type of blade is determined.Stubble cutters are arranged in a symmetrical double screw pattern to improve the stability of the machine.Finally,the movement of stubble cutter is analyzed.3.Through the analysis of variance,it can be concluded that the slower the driving speed and the faster the power output shaft speed,the better the crushing effect.The field test results of the machine showed that the average length of straw crushing was 62 mm,the mixed crushing rate of straw stubble was 86.9%,the average depth of stubble killing was 86 mm,the stability of stubble killing depth was 97.15%,and the soil breaking rate was 81.1%.The test results were all better than the national standards or testing standards of machines and tools,reaching the expected design goals.