Analysis and Evaluation of the Experimental Effect of Double-Disc Knife-Cutting Device for Carrot Combine Harvester

At present, the problems of the low cutting reliability and poor cutting quality of carrot harvesters in China are particularly prominent, directly leading to the problems of high root and stem damage rates, low stem and leaf cutting rates, and low cutting surface flatness rates. In order to solve these problems, we developed a disc-type double-disc cutting device. Based on the structural analysis and the central combination design theory of Box–Behnken, using three factors as influencing factors, namely, clamping and conveying speed, the rotary speed of the disc cutter, and the thickness of the disc cutter. A response surface experiment was carried out to analyze the influence of each factor on the high damage rates of the rhizome, the clean rates of stems and leaves, and the flatness rate of cutting surfaces to optimize the influencing factors. According to the test results, a regression mathematical model between test parameters and performance indexes was established, and optimization verification was carried out according to the regression model between test factors and indexes. Finally, the optimal parameter combination is as follows: a clamping and conveying speed of 1.0 m/s, a rotary speed of the disc cutter of 193.5 r/min, and a thickness of the disc cutter of 3.6 mm. The results of the field experiment showed that the root and stem damage rate was 2.61%, the stem and leaf-cutting rate was 87.32%, and the cutting surface flatness rate was 89.87%. Compared with a set of parameters commonly used in double-disc cutters to harvest carrots under the same conditions, the corresponding root and stem damage rates, stem and leaf-cutting rates, and productivity decreased by 2.16%, 1.97%, and 1.87%, respectively, and the comprehensive performance was obviously improved. The proposed research method can well simulate the cutting process in carrot harvesting and provide support for the development of carrot harvesting equipment.