Abstract:

[Objective] According to the environment conditions and the growing characteristics of the bush, the function of ground surface following was required for cutting mechanism of bush stumper with flexible connecting and lifting. A crawler self-propelled desert shrub stumper was developed to provide technical support for the effective utilization of shrub resource. [Method] The optimized design scheme of crawler self-propelled shrub stumper was confirmed based on field trip of Kerqin Sandy of Inner Mongolia, and the design of the suspension cutting machine overall structure and key parts was accomplished with design methods of 3D solid modeling technology and virtual prototype technology etc. The sampling survey method was applied when doing statistical calculation of shrub distribution density and biomass in the forest experiments. [Result] Considering the characteristics of shrub and the overall environment of sand, the working head was designed into an inverted V-shape based on the characteristics of shrub root. The application of hoisting chain, support rollers and flexible connection makes the cutting device floating on the ground while going up and down. The design and manufacture of the suspension type shrub stumper were completed, including the selection of traction and drive mode, the design of cutting device and profiling mechanism, etc. The cutting device was suspended at the front of the hydraulic crawler tractor. Operating speed of this prototype, of which shape size is 1 200 mm long, 900 mm wide, 1 150 mm high, is 3.5 km·h^-1, moving speed of it is 5 km·h^-1. The rotating speed of circular saw blade cutting tool is 3 600 r·min^-1. The maximum clearance from cutting device to the ground is 900mm, with a common cutting stubble height of 50mm. After finishing the design and manufacture, the test run of the prototype was launched in a forest farm named Xing Longzhao, landed on Kerqin sandy land in Tongliao City of Inner Mongolia. There are 266 700 hm² of lobular caragana shrub. Moreover there are 2 000 hm² of this shrub on this forest farm. The test area is 10 m wide and 90 m long, with a total area of 900 m². At the same time, a statistical survey was conducted, the number of cut shrub and the amount of branches were measured. The statistical data shows that the actual distribution density of the bushes of the region is 811 bundle ·hm^-2, the biomass wet weight and dry weight are 6 012.44 kg·hm^-2 and 3 763.22 kg·hm^-2, the average sediment deposition of each shrub is 0.5 m³, of which the crown diameter is 3.1m and the average height is 1.9m. The moisture content of shrubs before sprouting is 34.71% by the way of kiln dried. All the surveys above provided basic data for the resource and energy utilization of shrub tending slashes.[Conclusion] A prototype of shrub stumper powered by hydraulic driven rub crawler tractor was designed and manufactured. A shrub stumping trial using the machine was carried out in Kerqin sand area of Inner Mongolia. The test showed that efficiency of the machine shrub stumping was 243 shrubs·h^-1 with 50 mm cutting height and less than 3% split of reserved stumps. The new sprouts of shrub stumps were five to ten times of reserved stumps and the new stumps glow more than 1.2 m in the summer and autumn investigation. The machine are suited the requirement of shrub stump reproduction in desert sand area.

Key words: shrub stump reproduction, shrub forest, shrub stumper, machine design and manufacture