Design And Experimental Study Of Plastic Film Force Measuring Device

Film mulching is widely used in the cultivation of grain,cotton,oil,vegetable,melon and fruit for its remarkable characteristics of increasing temperature and keeping moisture,inhibiting weed growth,promoting early maturing and increasing yield of crops.The use of plastic film increased crop yield and caused persistent damage to cultivated land and its surrounding environment.A large number of results show that the soil fertility is weakened due to the incomplete recovery of plastic film,so plastic film recovery has been paid more attention.In this paper,the change of mechanical properties of plastic film with time,thickness and tensile mode is studied by means of experimental analysis.A mathematical model of the change of film mechanical properties with thickness and time was established.A mechanical testing device for plastic film was designed and the recovery test was carried out.By comparing the field experiment with the plastic film mechanical characteristic model,the film thickness during the recovery period was predicted,and the suitable film thickness was obtained.The research content of this thesis is as follows:(1)Experimental study on mechanical properties of plastic film.the mechanical properties of the film with different thicknesses of 0.010 mm,0.012 mm,0.014 mm,0.018 mm and 0.020 mm were measured,and the mechanical properties of the film were changed with time,thickness and position.The film thickness,filming time and light conditions have a significant effect on the average maximum tensile strength and average elongation at break of the film.The stretching method has a certain influence,and the tensile speed has no significant effect.According to the experimental data,the mathematical model of the mechanical properties of the film with thickness and time is obtained.(2)Development of test equipment.a test device for measuring the filming force was designed,analyzing its structural composition,determining that the filming angle of the filming shovel is 11°,the inclination angle of the film is 36°,and the arrangement of the filming fork row is triangular arrangement.The tooth spacing is 210 mm,and the structure of the film shovel is determined by Abaqus static analysis.and made a prototype(3)Making a force measuring device and conducting a field test After the test:when the working speed is 2.5-5km/h,the load force of the film is 38.5～91.20N,and the average value ranges from 45.93～77.92.N,the maximum value is 77.92N.At the same time,the tensile strength ranges from 2.2965 to 3.389Mpa,and the maximum tensile strength is 3.389Mpa.The minimum thickness of the film is calculated by the model to be 0.0186mm.The recovery rate of the film is determined.(4)Film recycling test,the cost and the recovery curve intersect at 0.018～0.020mm,which indicates that the film has a good recovery rate and suitable cost at the same time when the film thickness is between 0.018 and 0.020 mm.Considering that the mulch film with a thickness of about 0.0186 mm can be pulled up in the field without breaking,and considering the conditions of the mulch film manufacturer to prepare the mulch film,it is recommended to use a mulch film with a thickness of 0.019 mm,which can meet the economic benefits and can be recovered under the device.Appropriate recovery rate.