Improvement of straw transport device for straw-smashing back-throwing type multi-function no-tillage planter

Abstract: No-tillage planter can sow seeds in the condition of straw mulching field, which receives great attention and support from conservation society. But this kind of machine has some problems when it is used under full straw mulching field, such as grass winding and seed uncovering. Clean planter area under full straw mulching can help to achieve the processes of straw chopping, straw transport, sowing, fertilization, and straw mulching once and for all, which is widely used in many areas of China. Straw transport device is one of the important components of the clean planting area which is used to convey, elevate and throw straw. However, the problems of high power consumption and congestion affect the promotion of the machine. In order to deal with these problems, the structure of throwing pipeline was redesigned and analyzed. The analysis result showed that the improved throwing pipeline had a better throwing performance than the original throwing pipeline. On the basis of structural development of throwing pipeline, the central composite test method was used to optimize the key parameters for straw transport device. The main experimental apparatuses included straw cleaning device, rotational speed and torque sensor and high-speed camera acquisition system. The rotate speed of throwing impeller, feed quantity and sectional area of throwing pipeline were taken as the influencing factors. The specific power consumption and throwing speed were taken as response values in the experimental study. Orthogonal rotational quadratic combination test with three factors and three levels was made to evaluate the combined influence of the factors on the test index value. Besides, regression equations to describe the relationships between the factors and each assessment index were established by using the regression analysis and response surface analysis with the software Design-Expert 8.0.6. The optimum combination of the selected parameters was obtained and verified, and the experimental verification of the mathematical model was also conducted. The results showed that trial factors had great effects to the performance of straw transport device. The significant effects of rotate speed of throwing impeller, sectional area of throwing pipeline and feed quantity on reducing the specific power consumption were in a decreasing order. The significant effects of rotate speed of throwing impeller, sectional area of throwing pipeline and feed quantity on increasing but the throwing speed were in a decreasing order. The best model of the integrated straw transport parameters were as follows: When the rotate speed of throwing impeller was 2 272.26 r/min, the feed quantity was 1.33 kg/s and sectional area of throwing pipeline was 507 cm2, the specific power consumption and throwing speed by the models were 8 009.58 m2/s2 and 12.02 m/s, respectively. The model validation tests had been repeated for three times on the simulation field by using the optimization results, the rotate speed of throwing impeller was 2 270 r/min, the feed quantity was 1.3 kg/s and sectional area of throwing pipeline was 507 cm2, the values of practical specific power consumption and throwing speed were 7 980 m2/s2 and 11.7 m/s, respectively. Either of the relative errors between the experimental and predicted values of specific power consumption and throwing speed were less than 5%, which indicated a reasonable choice of optimization conditions. The research results can provide the references for the structural improvement and working parameters optimization of straw transport device of straw-smashing back-throwing type multi-function no-tillage planter.