Abstract:

Objective: In this study, a roller-type leaf-stripping and bark-peeling machine was designed and developed to achieve continuous leaf-stripping and bark-peeling operations for annual Eucommia ulmoides twigs during harvest, in order to address the low mechanization level in the large-scale harvesting process of E. ulmoides leaf-used forests. Method: Based on the determined characteristic parameters of the material and the performance criteria of the machine, EDEM software was employed for simulation analyses and bench tests to determine the optimal configuration of parameters, including the pitch, spacing, and speed ratio of the dual-roller cutting mechanism. Besides, the most appropriate number of rollers and a reasonable transmission mode were determined to ensure that the machine’s design meeting both performance specifications and operational efficiency standards. The force situation of the hammer blade used for defoliation was analyzed to determine the structural dimensions and arrangement of the hammer blade mechanism, and the design of key components of the equipment was completed. The feed roller speed and hammer blade roller speed for defoliation and peeling were selected as experimental factors, and the defoliation rate, peeling rate, and production efficiency were used as experimental indicators, to evaluate the overall performance of the machine. Result: 1) The cutting efficiency of the dual-roller mechanism on E. ulmoides bark decreased as the roller spacing increased, but was not significantly correlated with either the pitch or the speed ratio. The optimal parameter set comprised the cutting roller diameter of 150 mm, length of 1250 mm, pitch of 2.5 mm, the dual-roller spacing of 10 mm, the speed ratio of 1, two pairs of dual-rollers, and the rotational speed of 400 r·min^–1. 2) The hammer blade mechanism was configured in a fixed-distance, even number, and uniformly spaced arrangement. When hammer blades were 130 mm in length, 50 mm in width, and 4 mm in thickness, with a spacing of 15 mm between each hammer blade, a total of 40 hammers, two pairs of dual-rollers, rotating at a speed of 1 200 r·min^–1, the optimal defoliation effect could be achieved. 3) Field trial results indicated that the machine based on the design parameters exhibited the highest stripping efficiency for E. ulmoides twigs harvested in the first day of the annual growth cycle, with a moisture content ranging from 58%?70%. The defoliation rate achieved 100%, peeling rate achieved 78%, and the production efficiency reached 64%. Conclusion: The roller-type leaf-stripping and bark-peeling machine has achieved all the main design objectives, and this design may provide a reference solution for the development of mechanized harvesting equipment for E. ulmoides leaf-used forests.

Key words: leaf-used forest of Eucommia ulmoides, roller-pair type, hammer flake, defoliating mechanism, peeling mechanism