Parameters optimization and experiment of garlic picking mechanism

Abstract: In the present, the mechanized harvest technology of garlic in China is still in infancy. Most of the current domestic garlic harvesters only can accomplish the processes of digging and laying. However, the garlic combine harvester, which can synchronously finish the processes of digging, cleaning soil, cutting stem, cutting beard, gathering garlic bulb, etc., is still under test and demonstration. Furthermore, picking is the most important and difficult process of combine harvest, because the bad separation will result in another manual cutting. Different with the harvest mode of the developed countries, the farmers in China pull out the young garlic shoot in its early stage, which causes the garlic to collapse and affects its locating in the application of half feeding combine harvest. Besides, the residual stem is long, the damage rate is high and the cut pass rate is low. In view of the above problems, a picking device of garlic combine harvester was designed, realizing the garlic plant flexibly clamped, the garlic being sorted one by one and aligned automatically. In order to further study the garlic picking device, the garlic picking testbed was designed. The garlic picking testbed consists of a garlic picking device, shelf and transmission system. The main goal of testbed is the garlic picking device which consists of a clamping device, a rank-alignment device, a cutting device. In order to enhance operational performance of garlic picking device, reduce the residual stem length, the damage rate and increase cutting surface pass rate, the Box-Benhnken central composite experimental design principle was conducted in this paper. A four factors and three levels response surface experiment was completed on the garlic picking testbed, with four factors which affect picking quality. This paper established the response surface model and studied the factors affecting picking quality. At the same time, it synthetically optimized the factors affecting picking quality. The results showed that trial factors had great effects on picking quality. The significant effects of clamp number, main chain speed, clamp height, and clamp angle on residual stem length were in a decreasing order; The significant effects of main chain speed, clamp number, clamp height, and clamp angle on damage rate were in a decreasing order; The significant effects of main chain speed, clamp number, clamp height, and clamp angle on cut pass rate were in a decreasing order. The higher main chain speed, higher clamp height, more numbers of plants, then the residual stem length was longer, in contrast, the residual stem length was shorter. The higher main chain speed, shorter clamp height, more numbers of plants, then the damage rate was higher, in contrast, the damage rate was lower. The lower main chain speed, higher clamp height, less numbers of plants, then the cut pass rate was higher, in contrast, the cut pass rate was lower. The interaction of various factors affecting residual stem length, damage rate and cut pass rate were not significant changed. The optimum parameters were that the speed of main clamping chain was 1.05 m/s, the clamping angle was 77°, the clamping height was 220 mm, and the clamping number was two. The results have provided a base for the garlic picking mechanism.