| The cultivation technology of plastic film mulching has obvious effect of increasing production,the area of plastic film mulching has increased rapidly since it was popularized in China.At present,the production and usage of plastic film in China ranks first in the world,and plastic film has become the fourth largest agricultural means of production in China.The mechanization of cotton planting with plastic film,drip irrigation under mulch film and precision seeding technology have greatly improved cotton production in Xinjiang.At present,the cotton planting area and the use of plastic mulch film in Xinjiang rank first in China.However,while the plastic film brings great economic benefits to people,because of the recovery of the residual film in the farmland is not thorough,the accumulation of the residual film in the soil year after year,seriously endangering the sustainable development of agriculture.It is a feasible way to solve the pollution problem of residual film in farmland that thorough recovery of the mulch film in the year and gradually recover the residual film in former years.However,the film with too small thickness is fragile when it is recycled,which makes it difficult to recycle the small residual film mixed with soil.At present,there are some problems of low recovery rate and poor reliability in the existing residual film recycling machines in China.Therefore,in view of the above problems,on the basis of the implementation of the new national standard of weather resistant mulch film,combining agricultural machinery,agronomy and agricultural mulch,the design ideas of recycling residual film integrated,cleaning impurities by overturn the film surface,and automatic rolling are adopted.Therefore,this paper takes Xinjiang cotton field mulch film as the research object to carry out the research on the key technology of cotton field mulch film recovery and the passive residual plastic film recycling machine.Through theoretical analysis,experimental research and other methods and means,to explore the performance of key components.The research provides an effective technical and equipment support for promoting the application of residual plastic film recovery technology,and has important practical significance for improving the level of mechanized residual plastic film recovery.The research content of this paper mainly includes the following aspects:(1)Study on the key factors of the experiment and passive recovery mode of residual plastic film.The field topography of residual film was studied,the basic data of cotton planting density,soil physical properties,distribution of impurities on the surface of the residual plastic film,surface flatness of cotton field and mechanical properties of weather resistant residual film were obtained,which provides theoretical support for the design of key components;At the same time,the paper discusses the mode of the passive residual film recovery,and determines the main structure,working principle and transmission scheme of the passive residual film recycling machine.(2)Mechanism analysis and experimental study on film-soil separating.According to the experience and the actual demand of film-soil separating,a film-soil separating device and three different shape of spades are designed,and the arrangement and matching size of spades in the film-soil separating device are determined.The mechanism of film-soil separating is explored and the mechanical model of film-soil separating device is established;This paper analyzes the force condition of the film-soil separating device in the stable operation state,and determines the size of the parallel four-bar profiling mechanism;According to the test results of the stability of the ditching depth,the ditching depth stability was more than 80%,which proved that the structure design of the profiling mechanism was reasonable and met the requirements of the industry standard.In order to select the best type of spade,a single factor test was carried out with the spades type as the test factor,and the recovery rate of residual film,the draft force,soil disturbance and stubble uprooting as the indicators.The test results showed that the type of the spades had a significant influence on the recovery rate of residual film,the draft force and soil disturbance at a travel speed of 4.5 km/h and a working depth of40 mm of the combined implement.Spade A had the largest recovery rate of residual film,while spade C had the smallest one;Spade B had a higher draft force than the other spades.This trend was also observed for the soil disturbance area;There was no significant difference between the stubble uprooting rate of different spades.Analyzed the test results,and comprehensively considered the operation conditions and technical requirements of the passive residual film recovery machine,among the three spades spade A was the most aggressive tool in residual film recovery,for maximum residual plastic film recovery,reduced tractor power requirement,spade A should be recommended as the first choice.(3)Design of collecting and detaching residual film apparatus.By studying the operation principle of picking up and detaching,an apparatus integrating picking up,detaching and cleaning was designed.The main working part of the combined machine,including the structure design of nails,chains and cylinder for picking up residual film,and roller for detaching film,etc.,and through theoretical analysis of key components,the size parameters of pick up nails,chains arrangement are determined.The kinematic model of pick up nails was established,and the motion process of pick up nails was analyzed,the result showed that the pick up trajectory was cycloid.Through the analysis of the conditions under which the residual film was picked up successfully,the parameter range of pick up speed ratio of the residual film was 1?1.3,which provided the basis for the field test of the residual film recovery machine;Through the analysis of the movement process of the residual film detached from the device,the working conditions of the residual film removal were obtained.Combining with the mechanical properties of the weathering residual film,the rationality of the structural design of the detaching film apparatus was verified theoretically.(4)Design and experimental study of residual film rolling device.A belt-type curling-up film device was designed to realize automatic residual film roll unloading and resetting,including the structure design of main components such as frame,curl-up film roller,mandrel,gas spring,hydraulic system etc..The friction coefficient between the residual film and curling-up film belt was measured;The mechanical model of the curling-up film belt was established,and the structure and spatial layout were considered,then the driving form of the residual film rolling device was double drum driving;The parameters and models of the air spring were determined by analyzing the force on the residual film rolling device;According to the analysis of the residual film stress in the rolling process and the mechanical characteristics of the residual film,it was necessary to limit the maximum diameter of the film roll to 0.5m in order to ensure that the residual film will not be broken during the rolling process.In order to obtain the best structure and motion parameters,a multi factor field experiment was carried out to investigate the influence of various factors on the quality of film roll,the test results showed that the optimal parameter combination of the film rolling device was that the forward speed of the unit was 5.38 km/h,the film rolling speed ratio is1.19,and the film rolling angle is 80°.At this time,the average density of the film roll was122.7 kg/m~3,and the film roll met the requirements of resource utilization of the residual film.(5)Field test of the combined machine.A residual plastic film recycling machine suitable for the cotton field in Xinjiang was developed by integrating the research results of key technologies of residual plastic film recovery in the early stage,and the trial production of the prototype was completed.Take the picking up speed ratio of residual film,working speed of the machine,and the ditching depth of spades as the test factors,and taking the recovery rate and twining rate of residual film as the optimization objective.The experimental research on the residual film recycling machine was carried out and the relevant model was established,the multi-objective optimization of the regression model was carried out and verified by experiments.The test results showed that:When the picking up speed ratio of residual film was 1.08,the forward speed of the combined machine is 5.6 km/h,and the ditching depth of spades was 45 mm,the recovery rate and twining rate of residual film were 91.7%and 1.6%respectively. |
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