Optimization Design And Its Numerical Simulation Of Cutting Process For The Cutters Of Chain-Ditcher

The annual planting area for orchard is about 150 million mu in China, accounting for 17% of the global annual production. Ditching is a necessary link in the process of orchard planting. At present, orchard ditching is almost accomplished by manpower with heavy labor intensity and unstable ditching quality. The various ditchers in existence disagree with orchard ditching for the special working environment. On the premise of satisfying agricultural planting requirement on ditching, how to match the parameters of structure and operation to for the purpose of low power-consumption and fine working performance is the key for ditcher design.This thesis regards a self-developed chain-ditcher as the research object, aiming at the minimum power consumption for operation. By using the methods of kinematics analysis, numerical simulation and optimal design, the following research has been carried out:1. The kinematics and dynamics analysis of the chain ditcher has been accomplished systematically. On the base of the radical principle of the kinematics and dynamics, combining the vector graph and force analysis graph, the ditching mechanism has been studied, and mathematical model on the total cutting resistance and the total power-consumption of the ditcher has been established. Research result demonstrated that the main parameters affecting the power-consumption include: the ditcher horizontal moving speed v_e, the chain hobs absolute motion speed v_a and the chain hobs relative motion speed to the ditcher v_γ.2. Utilizing the software ANSYS/LS-DYNA, the dynamical model about the interaction between cuplike blades and soil has been developed. Through analyzing the blades cutting process with dynamics, the real-time dynamic change in stress, strain and resistance of single blade in the whole cutting process have been obtained. Through simulating with various cutting speed, the change rule of the cutting resistance and power-consumption has been studied.3. On the base of statics analysis, according the blade' structure forms, choosing the radius of circular arc r, the blade height H and thickness d as design variables, the maximal node equivalent stress in board as state variable, distilling the volume of cutting tools as target function, a optimization design has been achieved by applying the Design Opt module in ANSYS, on the premise that the performance should not been affected, the results showed: the optimal combination among circular arc r , the blade height H and thickness d is: r=75.116, H=127.826, d=6.5. 4. By means of the kinematics analysis and the numerical simulation, using the lowest power-consumption as target function, the mathematical model for optimization design for the main structure and motion parameters of the chain ditcher was set up. Then the optimization of ditcher's power-consumption was carried out by using the constrained nonlinear functions in MATLAB. At last, the optimal combination among the three main stand-alone variable parameters affecting the power-consumption as the horizontal moving speed v_e, the chain moving speed v_r and the chain horizontal inclination. a was obtained. Trials demonstrated that optimal designed power -consumption decreased 11.71% than the initial theoretical design value.5. Orthogonal tests with three factors and two levels have been carried out on the cutting speed of the cuplike cutters, involving cutting speed, cutting angle and cutting deepness by soil-bin experiment. Through regression analyzing on the soil-bin experiment, the interaction relationships for cutting resistance and cutting speed, cutting depth and cutting angle of per unit cutting area have been obtained. The test showed that cutting depth, cutting angle and the chain blades moving speed have significant impact on the soil cutting resistance.