Design Optimization And Experimental Study Of Vertical Blades Based On SPH Algorithm For A Small Deep Ploughing Machine

Currently rotary tiller is the main plowing machine in hilly regions,which actual tillage depth is only 10-15 cm.Hallow plowing for a long time has brought some serious problems such as plough pan thickening,soil hardening,soil fertility keeping ability reducing,the capacity of water retention gradually weakening and the pests increasing.So farmers urgently need small deep-tillage-machine which is suitable for hilly regions.Vertical milling operation mode is one of the effective ways to use small deep plowing machine to plough.Structural parameters and motion parameters of the vertical rotary blade will directly affect the operation quality and the power consumption of the vertical small deep plowing machine.According to the cutting theory and soil dynamics theory,linetype of vertical rotary blade is designed and simulated.For the purpose of minimizing the total power consumption,vertical rotary blade motion and structure parameters are optimized and tested.(1)According to soil dynamics theory,soil cutting theory and empirical formula,we design linetype of vertical rotary blade,deduce the linetype equation of spiral cutter,select structural parameters of vertical rotary blade.(2)The trajectory of blades is analyzed,which is a cycloid.By the soil dynamics theory and cutting theory,this paper analyzes the motion and stress state of the soil particles,and get the critical angular velocity equation of vertical rotary blade.This paper,from the perspective of macro and micro,analyzes the power consumption of rotary blade cutting soil.The results show that the main factors affecting the power consumption are moving speed,structure parameters and rotational speed.(3)This paper constructs realistic soil constitutive model with SPH algorithm to simulate the single rotary blade.It analyzes the change rule of the cutting resistance and the power consumption of the rotary blade,and describes the movement state of soil particles.In this paper,the feasibility of the installation of the cantilever beam tool is verified.The dynamic simulation is carried out to verify the correctness of the blade arrangement,the number of cutters and the design of cutter.The feasibility of the simulation model is verified by the experimental platform torque power test.Simulation analysis and experimental results show that:1)The rotary blade designed in this paper,its advance speed is 0.3m/s and its rotation speed is 240r/min,Through the analysis of the rotary blade cutting resistance,soil equivalent stress evolution is deformation — hardening — failure.And the cutting resistance of single blade is stable at about 1000 N.2)Three different depth soil particles are selected to make the trajectory.Furthermore displacement curve,velocity curve and acceleration curve of soil particles are analyzed to verify that blade has the effect on enhancing the transport of soil,which basically achieves the purpose of cultivating the upper soil and loosening the subsoil.3)By simulation of blades,the cutting power is about 3.3 kilowatts,its size is 3 times that of a single rotary blade.In addition,power value changes stably,which explains equal pressure of each blade and the feasibility of the blade arrangement.Moreover,Good tillage effect is achieved.4)The single blade of the simulation model is verified by the test platform,and the error between the measured power value and the simulation result is 8.68%.(4)The virtual orthogonal test is made.The test factors include the rotary blade forward speed,rotating speed and structure parameters,and the result of the test is power consumption.The paper establishes the regression equation of power consumption and various factors with SPSS software,meanwhile sets the target function and constraints with MATLAB software to optimize the linear regression equation.The minimum power consumption value and optimal structure parameters and motion parameters of rotary blade: the minimum power consumption is 2.43 kW,when the speed is 0.28m/s,the rotating speed is 20.78rad/s,the number of spiral is 1.35.(5)Experimental verification is carried out.After testing,the average power consumption of the rotary blade is 2.64 kW.The error between the experimental results and the simulation results is 8.64%.The correctness of theoretical analysis and simulation model is verified.At the same time,through platform experiment,the qualified rate of tillage depth of small deep ploughing machine platform is 91.17%,the rate of broken soil is 72.54%,and the land surface roughness is 2cm.All tillage indexes are up to standard.