Abstract: Rotary drilling rigs possess characteristics such as fast construction speed, high borehole quality, and minimal environmental pollution. However, these rigs face numerous challenges in terms of construction efficiency and fuel consumption due to the diverse construction processes, variable geological conditions, and complex quality control requirements. In order to improve the construction efficiency and reduce fuel consumption of rotary drilling rigs, experimental research on the construction process of rotary drilling rigs was conducted. Firstly, based on the operational characteristics of rotary drilling rigs, the working process was divided into five stages: drilling down, raising the drill pipe, rotating while on the carriage, discharging the excavated material, and rotating for hole alignment. Then, the variations in performance parameters of the rotary drilling rig and the engine during each stage were analyzed. Finally, in order to maintain the optimal operating condition of the engine at each stage of the rotary drilling rig, a control strategy based on the maximum feed rate of the drill pipe was proposed. A control program was developed to achieve precise control of the engine speed during the working process of the rotary drilling rig. The research was validated onsite at the production facility using an actual drilling rig, and the data were compared with that obtained from the onboard monitoring system installed on the drilling rig. The research results indicate that the adoption of the new control strategy enables the engine to operate in its optimal state, resulting in a 15% improvement in overall operational efficiency and a 5.74% reduction in overall fuel consumption. When this method is applied in the actual working process of rotary drilling rigs, it has the characteristics of low operating difficulty and strong stability, which can effectively improve the efficiency of rotary drilling rig operation process and reduce fuel consumption.
Key words:  construction machinery; rotary drilling rig; construction efficiency; engine; process control; speed control strategy