Design And Experimental Study Of The Floating Suspended Laser Grader

The application of laser grader can improve the flatness of field surface,save irrigation water,improve irrigation efficiency,inhibit the growth of weeds,improve the uniformity of crop maturity,increase crop yield and reduce production cost.Key laboratory of key technology of agricultural machinery and equipment of the ministry of education of south China agricultural university has developed a set of mature laser grader system.The1pj-3.0 paddy field laser grader has a leveling accuracy of up to 3cm.Due to its simple operation and ideal effect,it has been applied in many rice planting areas.However,as the machine needs to be used with head of high speed transplanter whose head power is small,it is difficult to improve leveling efficiency.In order to improve the laser leveler efficiency of paddy field(PF),basing on the floating function of three-point rear suspension mechanism of wheeled tractor,the working principle of floating suspended laser grader(FSLG)was analyzed,the feasibility of FSLG was demonstrated.In order to solve the problems of large turning radius,compaction in wet field and large settlement in horizontal PF,a suspended multi-wheel supported dryland laser grader(SMSDLG)was designed.Aiming at the fact that wheel rutting of wheeled tractor in PF has an influence on leveling and seeding,and elevation adjustment is prone to delay,a suspended roller supported laser grader for paddy field(SRSLGPF)was designed.The main research contents and achievements of this paper include:(1)A floating suspended grader hanging on tractor was put forward.Through the combination of the floating function of three-point rear suspension(TPRS)and supported device,the working principle of FSLG was studied,and the feasibility of developing SMSDLG and SRSLGPF was demonstrated.The impact of the change of tractor pitch attitude on the shovel and supported wheel under the floating condition was analyzed,which provided theoretical basis for SMSDLG.The impact of the change of tractor pitch attitude on the roller and the shovel under joint control of force and position and floating was analyzed,which provided the theoretical basis for SMSDLG.(2)Based on EDEM,the soil model in dry land(DL)and PF were established respectively.The working process of shovel on DL and roller in PF was simulated.The order of factors which affected the resistance of shovel on DL was: the shovel height,the radius of the arc,and the angle of soil cutting.The optimal parameter combination is shovel height of550 mm,arc radius of 250 mm and soil cutting Angle of 30°.The order of factors which affected the rutting elimination of the roller was: the blade height,the cylinder diameter,the number of blade rows,and the cylinder burial depth.The optimal parameters are the blade height of 120 mm,the cylinder diameter of 140 mm,the number of blade rows,and the cylinder burial depth of 10 mm.(3)FSLG was designed,including SMSDLG and SRSLGPF.By the analysis of TPRS combined with multi-support wheel to achieve laser leveler for SMSDLG,a floating mathematical model was established,and the structural and operating parameters of SMSDLG were confirmed,the compaction of the soil by the support wheel was analyzed,a multi-supported wheel device composed of two sets of rigid wheels was designed,which could effectively reduce the compaction to soft soil.On the other hand,a new leveling way was put forward,in which the traditional roller with blade was used to eliminate the wheel ruts in front of grader.In order to ensure elevation adjustment speed,the mathematical model of shovel elevation movement was established,and the level of elevation oil cylinder variation to shovel elevation variation was improved to 1:3,an elevation adjusting frame composed of parallelogram connecting rod was designed,the structural and operating parameters of SRSLGPF were confirmed.(4)The hydraulic and laser control system of FSLG was integrated and experiment in field was carried out.The test of SMSDLG results revealed that the machine could work stably,which can significantly improve the smoothing of the field and meet the flatness of land in the small field.The maximum elevation difference and standard deviation of the field were reduced from 20.8cm and 4.48 cm to 7.3cm and 1.72 cm respectively.The cumulative percentage of the sampling points with the absolute difference between the sampling point and the mean is less than 3cm is 91.94%.The soil compaction degree of the grid points before and after levelling was compared and analyzed,which indicated that the compaction effect of the multi-wheel support on the test field appeared at 0-17.5cm.However,when the depth was more than 17.5cm,the soil compaction was basically stable,and the surface soil of the whole field was compacted evenly.Moreover,the soft soil was moderately compacted after leveling,which reduced the sedimentation in the later stage of the soil and ensures the smoothness of the field.The PF test revealed that SRSLGPF could work stable and the roller could eliminate the ruts well.The standard deviation changed from 11.27 cm to 6.02 cm after the work of SRSLGPF,the absolute difference changed from 24.51% to 61.12%,which means that SRSLGPF can significantly improve the flatness of PF.