Simulation and experiment on a root cutting device for a chinese chard harvester

In view of the problem of the poor quality of root cutting during the harvesting of Chinese chard, the aim of this study was to improve the cutting quality of a device for harvesting Chinese chard, and to provide a reference for dynamic simulations of a Chinese chard root cutting device. In this study, key parameters such as the root diameter (mean value 24.05 mm) and maximum shear force (mean value 241.62 N) were measured for the predominant variety of Chinese chard (cv. Yihe) in the Shandong region. Based on these values, a root cutting device was designed with a vertical shaft double disc knife, using a 65 Mn disc knife (Φ300 mm) with a maximum speed of 400 rpm. A model of root cutting for Chinese chard with this double disc knife was established based on Livermore Software Technology Corporation’s Dynamic Analyzer (ANSYS/LS-DYNA), and a dynamic simulation of the root cutting process showed that the cutting stress first increased and then decreased. Simulation optimization experiments were then conducted with the maximum cutting force as the experimental indicator, and the optimal parameter combination for cutting was obtained as a traveling speed of 0.3 m s-1, a cutting speed of 300 rpm, and a root diameter of 20 mm. Performance experiments for the root cutting device were conducted in the field based on the results of simulation experiments, with an average maximum root cutting force of 36.10 N and an average root cutting accuracy rate of 93.90%, thus verifying the effectiveness of the proposed root cutting device.