Design And Parameter Optimization Of Double Axis Rotary Tillage Stubble Extinguisher Based On Discrete Element Method

China encourages the development of land preparation machinery that accords with the needs of local soil characteristics.The soil characteristics of rice and wheat rotation in Jiangsu province make the soil stuck to the soil after general tillage machinery is more serious.The soil block is large.In addition,the amount of straw on the surface of the farmland is large.The stubble coverage of ordinary rotary stubble extinguisher is low,and there are still a lot of straw remaining above the surface after rotary tillage,which was not conducive to the emergence of wheat.In order to improve the tillage quality and adapt to the soil environment with large water content in Jiangsu rice and wheat rotation,double axis rotary tillage stubble extinguisher has been gradually studied and applied.In order to solve the problem of large power consumption caused by double axis rotary tillage and improve the effect of soil breaking and stubble burying,the design and optimization of key parameters of double axis configuration of rotary stubble extinguisher were carried out according to the soil condition of rice stubble field in rice and wheat rotation in Jiangsu combined with discrete element method.1.The structure of the double axis rotary tillage stubble extinguisher is designed.Combined with the analysis of the existing models.Based on the analysis of the existing model,it had been determined that the direction of double axis rotary tillage was forward rotation of the front cutter shaft and backward rotation of the cutter shaft,and the theoretical analysis of the double axis rotary tillage was carried out.According to the rotary tillage theory,the rotating speeds of the front and rear cutter shafts are 245r/min and 310r/min respectively.The arrangement mode of the rotary tillage knife is double helix,so as to ensure the uniform stress of the knife shaft.2.Through soil texture test,density test,moisture content test,direct shear test and compaction test,the soil physical and mechanical parameters of the plough layer,plow bottom layer and subsoil layer were obtained.The parameters of straw were obtained through three-dimensional size study and stacking characteristics study of straw.The Hertz-Mindlin with bonding bonded contact model was used to describe the bond relationship between soil particles in different soil layers.The contact parameters between soil particles were determined by comparing the actual and simulated accumulation angle tests,and the soil adhesion parameters were determined by physical and mechanical parameters of soil.A discrete element model of double axis rotary tillage for paddy soil in rice and wheat rotation in Jiangsu was established,which provides a simulation basis for simulation and optimization of parameters.3.According to the study of double axis rotary tillage,the influence of four key parameters on the quality of rotary tilling,namely,the rotation radius of front rotary blade axis(R_f),the rotation radius of rear rotary blade axis(R_b),the vertical distance between the rear axle relative to the front axis(L_n)and the horizontal distance of the front and rear axes(L_l)were analyzed.The simulation test was designed by using Box-Behnken method.The response surface method was used to analyze the simulation results.When the R_f=225mm,R_b=195mm,L_n=35.4mm,L_l=137.8mm,it could make the tillage performance reach the best.The total power consumption of double cutter shaft was 26.3kw,the broken soil rate was 93.1%,and the stubble coverage was 94.1%.The optimal parameter combination obtained by simulation analysis provides a reference for the design and manufacture of the prototype.4.The prototype of the double axis rotary tillage stubble extinguisher was developed.Strain gauges on two side drive shaft of the prototype and test the torque of the tested shaft with DH5905 wireless torque testing system.The hall speed sensor was used to test the measured shaft speed.The field test showed that the total power consumption of the double cutter shaft was 29.3kw,the broken soil rate was 92.8%,and the stubble coverage was 93.3%,which was consistent with the simulation results of the whole machine.It was proved that the discrete element simulation model established in this paper was correct.The optimized parameters were effective,and the discrete element simulation test method could effectively predict the quality of the double axis rotary tillage.