Design and experiment of hob-type joint operation machine for silage corn root stubble plucking and residual plastic film collecting

Abstract: Agricultural film has many advantages, such as raising ground temperature, saving water and improving yield per hectare. For some northwestern Chinese regions like Xinjiang, Inner Mongolia and Gansu, the climate is dry and cold, and temperature difference between day and night is large, and thus the traditional agricultural production has wasted a mass of resources. With the use of agricultural film, and the planting structure in these areas has been improved, which has accelerated the development of agriculture in northwest China. However, it is difficult to degrade the films because most of the used films are PE (polyethylene) and PVC (polyvinyl chloride), and thus they accumulate in the field and cause the "white pollution", which can do great harm to the agriculture production. Especially in the corn filed, the corn fibrous roots are stuck in the film during growing up, and the stubble is entwined with the plastic film, which has great impacts on the recovery of residual film. Corn was one of the major grain crops in China, and the issue that needs to be resolved is directly related to fundamental interests of the millions of farmers. Nowadays, a variety of plastic film recycling equipment have been developed in China, and most of residual film recovery machines in Xinjiang are designed for wide, large cotton field, while residual film recovery machine for corn field is relatively less. In order to improve the mechanization recovery level of Xinjiang silage corn residue membrane, To study the effect of large root stubble on mechanized recovery of remnant membrane, and solve the problems of machine work such as low recovery of residual membrane and easy blockage of membrane stubble, we designed a hob-type joint operation machine for silage corn root stubble plucking and residual film collecting, which can be used to recycle silage corn root stubble and residual film. The key components of the machine are hob cutting device, drum collecting device, and film-stripping roller device. In this job, the hob cutting device can pull up silage corn root stubble from field, which can reduce their impacts on the residual film recovery. Then drum collecting device can pick up the residual film, and film stripping roller will send the film to box. Stubble extracting rate and residual film recovery rate are the main indicators of evaluating the machine and its operating characteristics. The Design Expert was used to design a three-factor three-level two-time regression center combination test, and the three-dimensional model of response surface with the depth of hob buried, the forward velocity of machine and the velocity of knife shaft as influence factors was established. The result shows that the depth of hob buried and the forward velocity of machine have evident influences on film recovery, while the depth of hob buried and the velocity of knife shaft have evident influences on stubbles recovery. According to the equations, we found out the optimal working parameters of the machine: The depth of hob buried is 18.5 mm, the forward velocity of machine is 4.57 km/h, and the velocity of hob shaft is 906.43 r/min. During the actual field test, when the forward velocity is 4.5 km/h, the depth of hob buried is 20 mm and the velocity of cutter shaft is 900 r/min, the residual film recovery rate can reach 84.62% and the root stubble cut rate is up to 88.25%. The test results show that the theoretical results are coincident with the measuring results, and the error between them is less than 4%. The hob-type film recovery machine can solve the impacts of silage corn root stubbles on residual film recovery. The results can provide some useful information for the further study on film recovery machines which are used in corn field and other large-stubble plants.