Design and experiment of DX1B bamboo root excavator

Abstract: There are more than 40 genera and 500 species of bamboo plants in China. Bamboo forest total area is up to 4.2 million hm2, and annual production is 18 million tons. Bamboo processing industry in China has been expanding and growing quickly because of good social and economic benefits as well as better environment protection significance, and this will drive the exploitation and use of bamboo resource. However, the bamboo roots hewn occupy a round range with a diameter of about 0.5-0.7 m and rot in several years in the land, which thus will block the growth of underground bamboo roots system if not be cleaned out in short time. Then the rapid comeback and progress of bamboo resource will be influenced, and meanwhile the land resource will also be wasted. In order to solve the low level of mechanization in the process of bamboo root grabbing, in view of the key factors affecting the bamboo root grabbing in the complex areas of bamboo forest and the different agronomy requirements, we researched and designed the automatic bamboo root excavator to solve the related problems. The main working principle of the bamboo root excavator was described. The design of the main structure and key parts was proposed. And the critical parameters were calculated. In addition, the cylindrical cutter and the pressure spring were analyzed by the finite element method. Theory analysis and simulation were presented to testify that the strength of the machine could satisfy the requirements of bamboo root grabbing. The analysis results showed that the von Mises stress of cylindrical cutter was about 195.6 MPa and its safety coefficient was 3.2. Besides, the maximum stress of pressure string was 4.6×109 Pa. Meanwhile, the modal analysis was carried out on the holder of machine to obtain the first four-order natural frequencies and mode shapes; the first four-order nature frequencies were 33.227, 36.23, 91.297 and 106.98 Hz, respectively. The first order and the second order frequency were close, so they could be seen as the multiple roots of the vibration equation. The analysis of the dynamic stability was proposed in order to avoid the resonance frequency during the structural design. Finally, the experiments with small prototype were carried out in bamboo forest to verify the performance of the machine. In the experiments, the diameters of cylindrical cutters were from 40 to 120 mm, and the diameters of the corresponding grabbed bamboo roots were from 30 to 70 mm. The maximum grabbing depth was 250 mm. The experiments showed that the majority of the bamboo roots could be grabbed by digging down about 150 to 200mm rather than digging to their bottom. And the shapes of bamboo roots were kept well. When the grabbing speed was about 2 mm/s, the stability and efficiency of the prototype were optimal. The entire grabbing process needed 2-5 min. The efficiency was improved by more than 60% compared with the manual grabbing. The results show that the designed bamboo root excavator realizes the automatic feeding and picking, and has the functions of automatically discharging soil and grabbing roots. During the grabbing, the worker does not need to contact with bamboo roots and soil. The research can offer a solution for the bamboo root grabbing in the complicated hilly and mountainous area. It can provide a reference for the development of full automation of bamboo root grabbing.