Objective In order to increase the impact-cutting efficiency and improve the pruning quality of P. tomentosa branches, the adaptability of impact-cutting performance of P. tomentosa branches was analyzed by studying the influence of internal factors of the branches on the cutting performance.
Method In this research, the branches of the fast-growing forest species P. tomentosa, which is widely planted in forest farms in north China, were taken as the research object, and a self-developed branch cutting platform was used to carry out branch cutting tests. On the basis of a one-factor test, based on the Box-Benhnken central combination test method, experimental and theoretical studies were conducted to investigate the influence patterns of three internal factors, namely branch diameter, moisture content and branching angle, on the peak cutting force and fracture effect.
Result (1) Cutting mechanism model of impact-cutting performance of P. tomentosa branches was established. (2) Through the optimization analysis of the model, the optimal parameter combination was obtained as branch diameter of 14.7 mm, moisture content of 14.0%, and branching angle of 90°. The peak cutting force under this combination was 370.48 N, and the fracture quality score was 4.6, and the relative deviation between predicted and measured values of peak cutting force and fracture quality score was both less than 5%. (3) Peak cutting force increased linearly with branch diameter, tended to increase and then decrease with increasing branch moisture content, and increased slightly with increasing branching angle.
Conclusion Selecting the tree age of 7 years for pruning operation, and choosing the season of operation in autumn and winter, can obtain better pruning quality. This study can provide data support for the research and development of pruning equipment for fast-growing forests in combination with the optimization of forest nursery methods.
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