Study of the Cutting Mechanism of Oil Tree Peony Stem

Tree peony is a deciduous shrub endemic to China, and peony seed oil (PSO) is an important plant oil resource. However, at present, pruning and fruits harvesting of oil tree peony are mainly completed by manual work, which has seriously affected production efficiency. By the need to develop efficient pruning and harvesting equipment for oil tree peony, this study investigated the effect of cutting tool geometric parameters and cutting speed on cutting force and energy. A cutting device was set up, and six cutting tools with different blade angle and sliding-cutting angle were prepared for this research. Stems in different growth stages (anthesis and fructescence) were collected for cutting experiments. In this paper, four blade angles (25 degrees, 30 degrees, 35 degrees, and 40 degrees), three sliding-cutting angles (0 degrees, 10 degrees, and 20 degrees), and four cutting speeds (25 mm/min, 50 mm/min, 100 mm/min, and 200 mm/min) were considered in the experiments. The results showed that cutting force and energy are positively related to blade angle, and the minimum cutting force and energy are required in cutting with 25 degrees blade angle. Compared to straight cutting (sliding-cutting angle is 0 degrees), sliding cutting can obviously reduce the cutting force and energy. Furthermore, the best sliding-cutting angles of cutting tools have discrepancies dependent on the stems in different growth stages. In fructescence, 10 degrees sliding cutting required the lowest cutting force and energy. In contrast, the best sliding-cutting angle of stems in anthesis was 20 degrees. On the other hand, the cutting force and energy were obviously proportional to the cutting speed, which increased by the cutting speed increasing. Therefore, under the condition of ensuring the cutting efficiency, reducing the cutting speed can effectively reduce the power consumption. These results are an important basis for pruning and harvesting machine development for oil tree peony.