Design And Experimental Study Of The Shrub Stumping Machine

Shrub stumping operation plays an important role in the forestry production. To solve the probloms of low production efficiency, high harvesting cost and harvesting inconvenience in planting and using process of desert shrub, shrub stumping machine with caterpillar chassis was designed and the stumping key technologies suitable for our national conditions were studied.Through researching on basic principle of shrub cutting, circular saw blades rotary cutting movement and stress distribution were analyzed. The cutting conditions of the stumping machine and the power consumption factors were determined, which the main factors influenced shrub sawing force were the shrub species, shrub diameter, shrub moisture content, the type of saw blade, sawing linear velocity and feed speed.The shrub sawing test-bed was designed, including sawing device, feeding clamping mechanism, frequency conversion motor, gear box, cooling and lubrication system, controlling system and testing equipments, etc. Then sawing device of the test-bed, feed clamping mechanism and other key parts were calculated and analyzed. Finally, according to the technical requirements and applications of the test-bed, appropriate motor, gear box, cooling and lubrication systems and test equipment were selected.Shrub sawing performances was studied indoor, it was shown that the shrub moisture content and shrub diameter had significant effect on the sawing force and sawing power. It was listed depending on the influence: sawing linear velocity > feed speed> saw blade specifications. Reasonable optimal parameters: season when shrub moisture content was about 20%, shrub diameter was around 15 mm, linear velocity of the cutter head of shrub stumping machine was 40 ~ 60 m/s, the pitch of saw blade was 9.81 mm, thickness was 2 mm.Main components of the shrub stumping machine were designed and analyzed. Cutting head with combined structure was designed, thickness of the saw blade was 2 mm, number of teeth were 200; cutting speed of the machine was 1500 r/min, cutting power of the single cutting head was 1.68 kW; conveying device with the pitch of conveyor roller chains as 15.875 mm was designed, conveying linear velocity was 1.8 m/s, conveying power was 1.77 kW and the cutting motor power was 7.5 kW. In order to suit for the terrain, the method of combining hydraulic cylinder lifting with machinery adaptive system, hook and copying device with hanging structure were designed.The prototype of shrub stumping machine was used in korshinskii shrub stumping experiment.It was shown that the machine speed had significant effect on both shrub damage rate and cutting rate. Damage rate increased and cutting rate decreased continuously when the machine speed increased, however the production efficiency was higher. In order to ensure productivity, the machine speed of 3 ~ 4 km/h was recommended in which damage rate was below 3% and average cutting rate was 98% ~ 98.7%.