Abstract:  For fullface vertical shaft boring machine with superlarge diameter, a type of graded excavation cutterhead driven by conventional power system is developed to match the localization and generalization of the driving system of boring machines, reduce the manufacturing difficulty, and shorten the processing time. Based on a vertical shaft project in China and the graded excavation design method, a graded excavation cutterhead with a diameter of 21.85 m embedded in the sliding cutter box and driven by a 5.3 m main bearing is developed. To minimize the torque and power required by the cutterhead, the cutterhead regulates the change in position and height of the disc cutter by stretching the sliding cutter box up and down, so that only a part of the disc cutters engage in each rockbreaking operation. In practical engineering applications, the cutterhead torque is less than 17 000 kN·m, the maximum daily advancing length is 1.8 m, and the average daily advancing length is approximately 1 m, indicating a favorable application effect. Finally, several recommendations for improving graded excavation cutterheads are provided.

Key words: superlarge diameter vertical shaft boring machine, fullface excavation, graded excavation cutterhead, structural design