Development of a Cutting–Extrusion Soil-Crushing Model for Peanut Harvesting and Optimization of Key Components

This study aims to address the major challenges encountered during peanut harvesting and digging in saline–alkali soils, including high digging resistance, poor soil fragmentation, and difficulty separating pods from the soil. A combined cutting–extrusion excavation device was optimized based on soil dynamics. A mechanical model for soil fragmentation via cutting and extrusion was constructed, alongside a mechanical model for separating soil–nut aggregates. Key factors influencing the device’s operational performance were identified, and parameter ranges were determined. Through theoretical analysis and discrete element simulation, the force distribution on the device during operation and the soil fragmentation mechanism were elucidated. Single-factor experiments determined the influence of each factor on evaluation metrics. Through orthogonal experimental analysis, the optimal parameter combination was determined as a blade angle of 21°, a rake angle of 50°, and a forward speed of 4 km/h. At this setting, the number of bonds broken was 172,652, and the working resistance was 14,673.5 N. Field test results indicate that the cutting–extrusion combined excavation device achieved 75.29% soil fragmentation and 16,965.4 N of working resistance. Compared to the original excavation device, soil fragmentation increased by 20.68% and working resistance decreased by 8.06%. The cutting–extrusion combined excavation device outperforms the original excavation device.