Integrating clamping finger-chain residual film recycling and straw crushing return to cotton field

Mulch cultivation has been widely used to regulate the growth cycle of crops for the high yields, due to the high ground temperature and moisture conservation for suppressing weeds. However, the main components of mulch film are polyethylene compounds extremely difficult to degrade. Once the mulch film failed to be recycled in a timely manner, the soil structure and fertility would be threatened, even by the serious pollution in sustainable cultivation. Among them, Xinjiang is the largest area of film cultivation in China. A great challenge is to recycle the ultra-thin film after a cotton operating season, due to the low film strength. However there are still some problems in the residual film recovery, such as the low adaptability to the unevenness of the ground, low recovery rate of residual film, and a large number of impurities in the recovered residual film. This study aims to develop an integrated machine with the clamping finger-chain type residual film recycling and straw crushing return to the cotton field. The machine was to concurrently realize the straw crushing and returning to the field, residual film recycling, as well as the clearing and baling operation. The structure and parameters of the existing clamping finger-chain type film collecting device were improved to design the disc film removing device and inclined belt impurity cleaning and feeding device. Mechanical analysis was conducted to determine the structural dimensions and arrangement of the film-removing device, as well as the impurity cleaning and feeding device. Three field tests were also carried out at an operating speed of 7 km/h. The test showed that the average lifting rate of residual film increased by 2.52 percentage pionts than before. The film-removing rate test showed that the highest film-removing rate of 99.79% was achieved when the speed of the film-removing disc was 189.47 r/min. The influencing factors on the residual film recovery rate were determined as the clamping finger-chain line speed ratio, the working length of the impurity cleaning belt, and the inclination of the impurity cleaning belt. The impurity rate of the residual film was dominated by the inclination of the impurity cleaning belt, the working length of the impurity cleaning belt, and the speed ratio of the impurity cleaning belt line. The working parameters were then optimized after the test. An optimal combination was obtained as follows: clamping finger-chain line speed ratio 0.8, clamping finger-chain belt inclination 50°, working length of impurity cleaning belt 608 mm. A better performance was achieved, where the evaluation indexes were 91.50% of residual film recovery rate, and 24.53% of impurity rate of residual film, respectively. The field test showed that the residual film recovery rate was 92.85%, and the residual film crushing and returning to the field rate was 26.05%, indicating a less difference from the predicted values. The integrated machine can be expected to fully meet the design requirements in the cotton field.