Design And Experimental Research Of Combined Tillage Machine By Hydraulic Driving

The soil of the Yangtze River area was heavy texture and harden,rice stubble was generally high,making it difficult to subsequent soil tillage and seeding.Due to the long-term use of rotary tiller farming soil,paddy field tillage layer gradually become shallow and the plow bottom becomes thicker,soil bulk density was increasing,the permeability of the soil was deteriorated.Combined tillage techniques could reduce the number of tools using and the destruction of the soil structure,improve the structure of the soil;The combined tillage technique was beneficial to reduce the evaporation of water,improve the water retention capacity of the soil,and thus reduce the cost of soil tillage.A combined tillage machine was designed based on disk plow,in order to meet the agronomic requirement of rape seeding.The main contents are as follows:1)The relevant tests of soil physical properties were carried out.The sieve analysis method was used to soil texture testing,The soil types suitable for rapeseed sowing were analyzed.Strain-controlled direct shear apparatus was used,fast shear method was used to test,When the soil moisture content was 25.79%,angle of internal friction of soil was 18.78?,friction coefficient was 0.34,cohesion was 52 kpa.Field survey and measurement method was adopted to measure soil tillage,the soil bulk density of sandy loam was 1.24,the average tillage layer was 17 cm,the bottom layer of plow was 8.7cm,the tillage layer of paddy field was 16.5cm and the thickness of bottom plow was 9.5cm,The soil porosity was 25.27% and the soil bulk density was 1.39 when soil water content was 29.37%.2)A hydraulic driven passive combined tiller was designed.The structural characteristics and working characteristics of the passive and active combined tiller are compared and analyzed,the two equipments was designed according to the process of ripping soil,turning soil,flat soil and crushing soil.The working parts of the combined tiller include corrugated disc harrow,ripper,notched disc harrow,and field experiments were carried out;The study shows that the field size of the middle and lower area in the Yangtze River was small,the quantity of Straw was large,and the operating speed for equipment was limited,the loosening of the machine and the ability to turn the soil was difficult to guarantee.In this paper,a hydraulic-driven notched disc machine which could broke the soil,cut and cover the rice residues was designed.The structure and operation parameters of disc harrow were analyzed and hydraulic-driven system was selected,The speed range of hydraulic motor was among 60~168r/min according to different working situation.The motion trajectory of the notched disc was analyzed and the critical angle of disc harrow was 23?,The stability of tillage depth was ensured by installing the wheel.3)The process that disc broke the soil was analyzed in finite element method using ANSYS/LS-DYNA.A finite element model of soil cutting disc harrow was built,the constitutive model of soil material MAT147 was analyzed and the relevant values were determined.The simulation results showed,the resistant force of disc cutting the soil changed periodically at the beginning and then increased gradually.The positive side of the disc squeezed and rotated the soil.Compared with the negative disc simulation results,hydraulic-driven notched disc could rotate more soil and its work depth was more stable.4)The hydraulic drive system was designed and tested,Through the throttle opening and disk rake group test,the rotational speed of disc rake group meet the design requirements;The simulation results were verified by the soil tank test,the passive disc harrow in the forward direction of average tillage resistance was 303.4N,the simulation results show that the disc raking resistance was 266 N,the simulation model of soil trough validation was basically accurate;The tillage resistance obtained by the soil test increased with the increase of tillage depth.the power consumption of the disc rake group was 13.6kw;Field experiments were conducted,the field experiment showed that,hydraulic driven tillage machine compared to the passive tillage machine had a better turning mattress and dumping performance,the passing performance of the machine was better,and the soil water content was appropriate,the crushed soil quality was better,the operating effect was in line with the agronomic requirements of rape seeding.