| As a special type of reciprocating pump,diaphragm pump has become one of the key equipment in long-distance pipeline transportation because of the special structure of its hydraulic end,especially in the field of long-distance pipeline transportation of high-abrasion,high-concentration solid-liquid two-phase media.However,with the development of the pipeline transportation industry,higher demand has been put forward for the performance indicators of diaphragm pumps.Diaphragm pumps are required not only to work more efficiently,but also to consume less energy,to be more reliable and to be lighter.Therefore,the power end of a certain type of large diaphragm pump in the 3D series of Chongqing water Pump Factory is taken as the research object in this paper.Under the condition that the rigidity and strength of each component of the power end are not reduced,the structure of each component is optimized in order to reduce the quality of the power end and lay the foundation for the lightweight design of the base and hydraulic end of the diaphragm pump.The main research contents of this paper are as follows:Firstly,through the working principle of diaphragm pump,the motion law of the main components in the power end is analyzed,and the interaction force between the crankshaft,crosshead and connecting rod is obtained based on the D’Alembert principle considering gravity,friction and inertial force,and MATLAB is used to obtain the curve of the force between the components with the crank angle.Subsequently,the kinematics and dynamics simulation of the power end was analyzed by the virtual prototyping technology,and the contact collision force was added to the dynamic simulation to simulate a more realistic motion situation.The simulation results show that the simulation value is consistent with the trend of the theoretical value,which proves the correctness of the theoretical calculation results.However,in dynamic analysis,the simulation value is always less than the theoretical value,so it is more conservative to use the theoretical value as a loading condition for finite element analysis.the crankshaft,connecting rod and crosshead are analyzed by WORKBENCH to determine whether their strength and stiffness meet the requirements,and the most dangerous working conditions of each component and the load conditions under the corresponding working conditions are found,which lay the foundation for subsequent optimization work.In addition,the modal analysis of each component is carried out separately,and the natural frequency and mode shape of the first ten orders of each component under the constraint condition are obtained,which provides a certain dynamic characteristic basis for the optimization work,and the displacement amplitude response spectrum of each component under the excitation force is obtained through harmonic response analysis,which provides suggestions for the frequency of external excitation at the power end.Taking the finite element analysis results as the basis for selecting optimization variables,combining the main length,width and height parameters of each component to determine the design variables,taking the maximum stress value,maximum deformation and mass of each component as the optimization goal,the central composite design method is used to design the experimental sample points,the RBF neural network is used as the proxy model to fit the mapping relationship between the design variables and the optimization target,and the NSGA-II algorithm is used to find the optimal size combination scheme.Finally,without significant changes in the strength and stiffness of the crankshaft,connecting rod and crosshead,the mass of the three decreases by 12.35%,26.46% and 24.42%,respectively,and the natural frequencies of the optimized crankshaft,connecting rod and crosshead increase in the low-order frequency range. |
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