导向链耙式地表残膜回收机设计与试验

针对耙齿式残膜回收机工作过程中存在漏捡、脱膜不彻底、耙齿回带残膜等问题，该研究设计了导向链耙式地表残膜回收机。设计了导向链耙式拾膜机构以及耙齿总成与输送链的连接结构，以解决现有链齿式拾膜装置需要输送链弯折实现脱膜的问题；确定了耙齿结构和耙齿的排布；采用旋转式脱膜装置配合导向耙齿提升脱膜效果；在膜箱后部设计了推膜机构以提高装载量；应用机械加液压的组合方式实现拾膜、脱膜与推膜的传动需求；通过运动分析确定了各主要运动部件的结构参数。为了验证机具关键部件的可靠性与作业效果，以机具前进速度、耙齿入土深度、链耙输入转速为试验因素，以拾膜率与缠膜率为指标，进行了拟水平正交试验。试验结果表明：影响拾膜率的主次因素为链耙输入转速、机具行进速度、耙齿入土深度；影响缠膜率的主次因素为链耙输入转速、耙齿入土深度、机具行进速度。以拾膜率为主要指标，利用综合平衡法确定较优的作业参数组合为机具行进速度8 km/h、耙齿入土深度30 mm、链耙输入转速143 r/min。利用较优参数组合进行田间验证试验，拾膜率为88.73%，缠膜率为1.91%，研究结果可为残膜回收机的优化提供参考。

Design and experiments of rake type surface residual film recycling machine with guide chain

Abstract: The usage of film mulch cultivation technology is ever increasing in China, particularly ranging from fruits and vegetables to a variety of food crops in a large area. Ultra-thin plastic film is commonly used as a soil surface mulch. The long-term laying of plastic film has brought serious mulch residues, due to its polyethylene film is difficult to be degraded in the natural environment. The accumulation of plastic film residues has caused serious negative effects on the crop growth, such as microorganisms in the soil difficult to survive, damage of soil agglomeration structure, obstruction of moisture circulation, soil salinization and compaction. As such, various machines were developed for residual film recovery, with strong adaptability, high recovery rate, and high work efficiency, particularly on the residual film pickup device in tooth-chain type for gathering and tying the film. However, the complicated structure of mechanism limited the application of residual film pickup device. At present, a bent conveyor chain is often used, in order to improve the efficiency of removed film. If the length beyond the critical after the conveyor chain bending, the film pickup teeth are easy to be deformed after impact, resulting in leakage pickup phenomenon, and the incompletely removed film, easy to wind, and low loading. This study aims at the problems of missing inspection, incomplete stripping, and winding of rake type residual plastic film collector during the working process, thereby to design a guiding chain harrow type residual plastic film collector on the surface soil. The main content included the design of guide chain harrow type picking-up film mechanism, and the connection structure between the rake assembly and the transport chain, with emphasis on the transport chain for the removal of film. Specifically, the structure of rake teeth and the arrangement of rake teeth were determined, the rotary film removal device with guide rake to improve the effect of removing film, and a pushing film mechanism was designed at the rear of film collecting box for increasing the loading capacity. A combined method of mechanical and hydraulic pressure was applied to realize the transmission requirements of picking up, removing, and pushing film. A motion analysis and pretests were conducted to optimize the structural parameters of main moving parts. A quasi-horizontal orthogonal test was carried out to verify the reliability of key parts in the machine and the operation performance. The test factors were selected, including the machine advancing velocity, the depth of rake into soil, and the chain rake input speed, and the indexes were the film pickup rate and film winding rate. The results show that the primary and secondary factors that affected the film pickup rate were the chain harrow input speed, the machine advancing velocity, and the depth of rake into soil, whereas, the primary and secondary factors that affected the film winding rate were the chain rake input speed, the depth of rake into soil, and the machine advancing velocity. Taking the film pickup rate as the main index, the integrated balance method was used to determine the optimal operating parameters, where the machine advancing velocity was 8 km/h, depth of rake into soil was 30 mm, and the chain rake input speed was 143 r/min. A field validation test was performed on the better parameter combination, where the film pickup rate was 88.73%, and the film wrapping rate was 1.91%. The findings can provide a sound reference to optimize the design of residual plastic film collector, and further to improve the operation performance.