Design and test of double-shaft type sweet potato haulm cutting return machine

In this study, a double-shaft type sweet potato rice-planting and rice-returning machine was designed. The structure of the whole machine as well as the key components were analyzed, and the influence of each factor on the operation quality was studied. The results of the study showed that the order of the influence of each factor on the length of broken stems and leaves and the rate of checking was as follows: roller speed > toggle clearance > toggle spacing; the order of the influence on the stubble height was as follows: toggle clearance > roller speed > toggle spacing; and the order of the influence on the rate of injury to potatoes was as follows: roller speed = toggle clearance = toggle spacing. The optimal combination of working parameters in the field test was 1944 r/min for roll speed, 132 mm for toggle spacing, and 20 mm for toggle clearance, at which the qualification rate of stem and leaf breaking length was 94.32%, stubble height was 33.61 mm, and potato injury rate was 0.26%. The relative error with the theoretical optimization value is between 0.13% and 7.14%, which meets the operational requirements of sweet potato rice transplanter.