Design and test of clamping finger-chain type device for recycling agricultural plastic film

Abstract: The domestic equipment for recycling agricultural plastic film has the problems of low recovery rate of plastic film, wrapping the film collecting parts by plastics, or difficulty of separating the straw and soil from the film. In addition, film removing for the current methods is poor and high impurity content of recovered plastic film can't be recycled. In order to solve these problems, the clamping finger-chain type device for recycling agricultural plastic film was designed. The designed device mainly consisted of film collecting device, film removing device, transmission system, side film shoveling, tie rod, transverse beam, residual film box, etc. The film collecting device mainly included film collecting frame, upper film collecting sprocket, under film collecting sprocket, film collecting chain, clamping finger, film cutting saw disk, supporting chain roller, tightening devices, etc. The film removing device mainly included film removing rotation shaft, film removing blade, driving sprocket, film removing bracket, bearing chock, etc. The film collecting device was driven by the ground wheel through the film collecting transmission system and the film removing device was driven by the tractor power output shaft through the film removing transmission. Through the design and mechanical analysis of the clamping finger-chain, the structure size parameters of it were determined, which contained the spacing between two clamping finger-chains was 220 mm, and its working angle was 40°, the effective length of clamping finger L was 135 mm, and the angle between clamping finger and outer link was 20°. The tension mechanism could make the clamping finger-chain be always in a state of tension in the process of operation. The specification parameters of the selected spring were determined by analysis of the tensioning mechanism. Through the structure size design and motion analysis of film removing device, the film removing blade size was determined, and the length was 220 mm and the width was 80 mm. The working speed of film removing rotation shaft was 220 r/min. Based on the motion analysis of the clamping finger end from entering the soil to coming out the soil, the motion equations of finger end were obtained, and then the maximum buried depth of the clamping finger and the sliding length on the ground of the clamping finger were deduced. According to the above formula, the sliding length on the ground of the clamping finger was positively correlated with the ratio of operating speed of machine and line speed of clamping finger-chain. When the ratio of operating speed of machine and line speed of clamping finger-chain was 2, there was less stuff blocked in the lower sprocket and the residual plastic film which was cut into strip could be successfully picked up by clamping finger-chain. At last, the field experiment and statistic data analysis of the device were carried out. The experimental results showed that when the traction speed of tractor was 5.5 km/h, the conveyor inclined angle of the under clamping finger-chain was 40°, and the operating speed was two times of the speed of the film collecting chain. The field test showed that the recovery rate of agricultural plastic film was 90.5%, the effect of collecting film was better and there was no plastic film and other debris, such as straw and mud, blocking the under sprocket or the plastic film being torn up. The effect of film removal was also better and there was no plastic film winding on the upper film collecting sprocket, and there was less straw and soil in the recovered residual membrane which would be convenient to subsequent process and reuse. These indexes met the technical requirements of the plastic film recovery and this device could be used for the development of a new type of residual film recycling machine.