| Plastic film planting has the advantages of increasing surface temperature,inhibiting weed growth,reducing crop growth cycle and increasing crop yield.However,due to the diversity of cultivated crops,complex surface conditions and plastic film strength,there are some problems in mechanical recovery of residual film,such as low recovery rate,high impurity content,and easy entanglement and blockage.In this paper,based on the investigation of potato planting mode and the present situation of residual film recovery in Qinghai Province,the bottleneck factors affecting the recovery of residual film were analyzed,and new residual film recovery technology was put forward and the supporting equipment was developed.The main work and conclusions of this paper were as follows:(1)The mechanization technology of potato residual film recovery and the design scheme of supporting equipment were put forward.In the typical potato planting areas of Qinghai Province,the planting agronomy of potatoes and the surface condition before the recovery of residual film were investigated,the matching machines and operation quality in mechanical harvesting and residual film recovery were analyzed,and the factors restricting the recovery quality of residual film were summarized.Finally,the mechanized recovery technology of potato mulching film before potato harvest was determined,which included loosening the mulch with soil crushing roller,bunching the residual mulch with bunching ring and raising a certain height,cleaning the sundries on the mulch with beating mechanism,and collecting the mulch film with double rollers.The overall design scheme of supporting machines and tools was also determined.(2)A new way of film formation is designed,in which the single wing scoops up the film and the middle wing scoops up the film.According to the principle of reducing the resistance of machines and tools,the parameters of the film lifting shovel are finally determined as follows: the rake angle is 28,the length is 280 mm,the cross-section width is 210 mm,and the wing shovel opening angle is 62;The finite element analysis of the film-forming shovel was carried out by ANSYS.The results show that the maximum stress occurs at the bolt,which is 137.65 MPa,and the maximum strain occurs at the bolt hole.The maximum stress is less than the yield limit of its material,which does not affect the working performance of the shovel.(3)A membrane-soil separation device was designed,which combines soil crushing roller and beating mechanism.The shear mechanical performance test of hardened soil was carried out,the effect of shear force on hardened soil was analyzed,and the optimum shear force was determined to be 1556 Pa.EDEM and Adams are used to analyze the membrane-soil separation mechanism.The results show that the membrane-soil separation effect is best when the number of crushing teeth of the crushing roller is 20,the width of crushing teeth is 15 mm,the height of crushing teeth is 20 mm,the travel of travel limit slider is 30 mm,and the rotating speed of eccentric wheel is 60 r/min.(4)A film collecting device with bunching ring bunching and double-roller conveying was designed.According to the technical scheme,the mechanical properties of bunched plastic film are studied.The results show that the maximum tensile force is 2.1 times that of single-layer plastic film,the elongation is 54.762 mm higher than that of single-layer plastic film,and the breaking nominal strain is 55%higher than that of single-layer plastic film.The transport force of the film collecting device is analyzed.When the diameter of the transport roller of the transport mechanism is 110 mm and the working gap is 2 mm,the transport force is far less than the overall tensile force of the bunched mulch film 183.7 N.The experimental platform was set up for the designed film collecting device,and the bench test was carried out.The results showed that when the distance between the conveying rollers was adjusted to 2 mm,and the speed of the ground wheel was maintained at 2-3 km/h,the residual film had good passability and no fracture occurred.(5)Design the transmission system and frame.The transmission ratio between beating mechanism and ground wheel is 3:1,and that between film collecting device and ground wheel is 6:1.The teeth number of left wheel,beating mechanism,right wheel,outer wheel,inner wheel and lower roller of film collecting roller are 30,12,36,12 respectively.The whole dimensions of the machine are determined to be 1680 mm in length,1400 mm in width and 800 mm in height through the previous investigation of potato planting agronomy.The modal analysis of the machine frame shows that the natural frequency of the machine frame is between 17.589 Hz and70.299 Hz,and the main vibration of the machine frame occurs on both sides of the machine frame,mainly at the end of the machine frame,where the film collecting roller is located.It can be seen from the sixth-order vibration mode nephogram that the machine frame does not resonate.(6)Complete prototype manufacture and simulated field test.The experimental results show that when the distance between the upper and lower rollers of the conveying roller is 2 mm,and the speed of the machine is 2 km/h,the mulching film does not break,and its passability is good,and the impurity content of the residual film is 6.83%. |
