| The plastic film mulching planting technology has achieved quality and efficiency improvement in agricultural production due to its functions of increasing temperature,preserving soil moisture,and inhibiting weed growth.However,the residual plastic film in the soil has caused white pollution in farmland,seriously affecting crop yield and sustainable development of agriculture.It has become a prominent problem restricting the sustainable development of green agriculture in China.At present,the cleaning rate of residual film recycling operations is around 80%,and 20% of the current year’s plastic film residue is still in the arable layer of farmland.In addition,the accumulation of a large amount of plastic film residue in the tillage layer in previous years has made the recovery of plastic film residue in the tillage layer a crucial factor in effectively controlling agricultural film pollution.The common problems of severe fragmentation and poor mechanical properties of the residual film in the tillage layer,as well as the difficulty in separating the residual film from the soil and root residue,is the critical factor that causes the low collection rate,high soil content,and root residue content in the tillage layer residual film recycling operation,which seriously restricts the level of mechanized plow layer residual film recycling.It is urgent to study the methods and mechanisms for the effective recovery of tillage layer residual film and explore the mechanism of plow layer residual film recycling to provide a theoretical basis and technical support for developing efficient machinery for recovering arable film residue.Therefore,based on the analysis of the current research status and existing problems of residual film recycling machines,the factors affecting the performance of residual film recycling operations in the tillage layer were studied.The critical technology of roll-type residual film recycling was identified,and a rotary tillage membrane lifting device was proposed to rotate and throw up the membrane soil mixture.During the falling process of the membrane picking area,the elastic teeth rotated and actively hooked the residual film to pick up and separate it.The research on the film characteristics of the rotary tillage film lifting device,the theoretical analysis and parameters of the roll-type tillage layer residual film recovery mechanism,and the roll-type tillage layer residual film recovery experiment to verify the mechanism of the roll-type plow layer residual film recovery,The main research conclusions are as follows:(1)The factors that affect the recovery of residue film were analyzed,and experimental research on the distribution of residue film at different soil depths,measured the geometric characteristics and mechanical properties of residue film,and revealed the distribution and mechanical properties of residue film at different soil depths.The impact of the residual film recycling operation period and film removal method on the performance of residual film recycling operation were analyzed.The critical technologies of roll-type tillage residual film recovery were clarified,and the technical solutions of roll-type tillage residual film recovery were proposed.Using the coupling method of FEM and SPH to establish a numerical model of the roll teeth-picking process,studied the roll forward and reverse picking process and the effect of the teeth on soil and residual film during the roll-picking process.The process of breaking the soil and picking up the film by roll spring teeth and its influence on soil shear breaking and residual film stress change were analyzed microscopically.Through analysis,it is found that the forward picking process has a smaller disturbance effect on the soil by the spring tooth compared to the reverse picking process,which can effectively reduce the influence of the soil on the spring teeth during the picking process.The working resistance of reverse film picking is higher than that of forward film picking.According to the changes in force on the teeth in the X and Y directions,to ensure that the teeth can effectively hook and roll residual film,the bending angle design of the tooth tip can effectively improve the performance of the teeth in picking up film.When the roller speed is 3.22 m/s,the force exerted by the tine on the residual film is greater than its puncture resistance strength.The tooth tip can effectively pick up the residual film and separate it from the soil mixture,achieving the pickup and separation of the residual film in the tillage layer.The structural design and analysis of the key components of the roll-type topsoil residual film recycling machine were carried out.(2)By studying the film-lifting characteristics of the rotary tillage film-lifting device and establishing the model of the film-lifting knife movement,the critical conditions for the film-lifting knife to throw the tillage layer film-soil mixture backward were obtained,and the rotation speed ω of the film-lifting knife was calculated to be 22.37 rad/s.The relationships between soil cutting width,soil cutting pitch,and the overlapping amount were studied,and their influence on the effective breaking of broken soil by the mixture of residual film in the tillage layer was explored.By analyzing the throwing process of the rotary tillage film lifting device on the residual film mixture in the tillage layer and constructing the power model of the film lifting knife throw the residual film mixture,the throwing characteristics of the rotary tillage film lifting device on the residual film mixture of the tillage layer were obtained.The effects of rotary tillage film lifting device on the throwing rate,fragmentation,and film lifting rate of the residual film were studied through experiments.Through film lifting operation experiments,the film lifting rate of tillage residual film in 0-150 mm soil layer was 92.3 %.The experiment of the throwing rate of residual film in the tillage layer revealed the throwing law of the rotary tillage film lifting device on residual film in different soil depths.The average fragmentation before and after the film lifting operation decreased by 6.5mg/piece.These tests indicated that the rotary tillage film lifting device can effectively break the soil and throw the residual film of the 0-150 mm soil layer depth.The through law of the tillage film lifting device on the residual film of different soil depths was clarified,which provided a theoretical basis for the design of the picking drum.(3)By Studying the theoretical analysis and parameters of the roll-type tillage film recycling mechanism,the motion model of the operation process of the roll-type tillage film recycling mechanism was established.The rotation speed of the picking drum was 4.58 rad/s,and the roll forward rotation picking film speed was 13.74 rad/s.The force process of the roller spring teeth film-picking and the tooth tip hook film was studied,and the critical condition for the spring teeth to effectively hook and pick the residual film in the mixture was that the rotation speed of the teeth was not less than 8.89 rad/s.The designed rotation speed meets the film-picking conditions.By analyzing the factors that affect the film-picking performance of the roll,such as the thickness,width,and picking area,the law of the effective film-picking film of the roll spring teeth is obtained.The unloading process of the roll was studied,and it was found that the reverse unloading speed of the roll was 17.57 rad/s,while the unloading speed of the roll was 4.5 rad/s.Using ADAMS simulation technology,study the film picking and unloading process of the roll-type tillage layer residual film recovery mechanism and accurately analyze the displacement,velocity,and other motion changes of the roll spring teeth.The simulation results show that the motion of the roll-type plow layer residual film recovery mechanism meets the expected requirements of the design and can complete the operation process of the roll turning forward to pick up film and reverse to unload film in the picking area.(4)We have trial-produced the roll-type tillage film recycling machine and conducted single-factor experimental research to obtain the influence of factors such as forward speed,roll speed,picking drum speed,and the tooth tip bending angle on the performance of tillage film recycling operations.The response surface test was conducted using forward speed,teeth speed,and tooth tip bending angle as experimental factors,and the cleaning rate and residual film content of the recovered mixture as experimental indicators.A regression equation was established for the cleaning rate of residual film in the cultivation layer and the residual film content in the recovered mixture.Through analysis of the regression equation,the optimal working parameters were obtained as forward speed of 4km/h,tine speed of 3.3 m/s,and tooth tip bending angle of 46.5°.The cleaning rate under the optimal parameter combination operation was 73.07 %,and the residual film content of the recovered mixture was 73.27 %;The validation experiment was conducted under the optimal parameters combination,and the recovery rate was 73.5 %,which was higher than the corresponding fitting optimization value of 0.47 %.The residual film content of the recovered mixture was74.36 % which was higher than the corresponding fitting optimization value of 1.09 %.The experimental results were consistent with the results obtained from the optimization model,indicating the correctness of the analysis model. |
PDF Full Text Request