Dynamics Simulation And Crank Phase Optimization Of Quintuple Pump Transmission System

The transmission system of fracturing pump is the most critical component of the fracturing pump power end.At present,the common transmission method of the power end of the five-cylinder single-acting fracturing pump is to adopt a symmetrical first-stage double helical gear transmission system.The key parts of the transmission system mainly include drive shaft,crankshaft,connecting rod,crosshead and plunger assembly.The wear of the crosshead,at the power end,will lead to generate the clearance between the crosshead and the slideway,resulting in the change of the force on the crosshead and the deviation of the center of the plunger,it can even cause damage to the crankshaft.In the working process,the crankshaft will produce torsional vibration because of the action of external periodic excitation force.Not only will this lead to reduce the power performance of fracturing pump,arise noise,but also accelerate the damage of other accessories.Therefore,it is of great engineering significance and economic value to deeply study the dynamics of fracturing pump transmission system and optimize the related structure.This paper mainly studies the following aspects:The crank,connecting rod and crosshead is simplified to the plane slider-crank mechanism.According to discriminant conditions of contact collison,mechanical and mathematical models of crosshead considered sliding pair clearance are established basing on the contact collision model between sliding and guide.Meanwhile,the impact force on the crosshead is solved,and the effects of crankshaft speed,offset distance of crosshead,offset style of crosshead and clearance size on the impact force of crosshead are analyzed.It is proved that the influence of clearance of sliding pair on the force of crosshead can not be ignored.Mechanical and mathematical models,using the lumped parameter method,are established of torsional vibration of transmisson system in fracturing pump with considering the influence of external excitation load,meshing stiffness,meshing damping,external damping and structural damping,think bearing as rigid,and without considering the bending deformation and longitudinal deformation of the crankshaft.Taking the software of matlab 2014 a as simulation platform,the natural frequency and the main modeof the transmission system are obtained,and the forced torsional vibration of transmission system is simulated by using Runge-Kutta method.The influence of helical gear meshing stiffness and helical Angle on the natural frequency of five-cylinder fracturing pump transmission shaft system is analyzed and compared.The dynamic input torque and the static input torque of the transmission shaft are simulated and analyzed.Based on the analysis of the force and strength of the crankshaft,taking the initial phase angle of the crankshaft as the design variable and the minimum value of the maximum bending moment of the dangerous section of the crankshaft as the objective function,the simulated annealing optimization algorithm is adopted to optimize the layout scheme of the crankshaft phase with five crutches and six supports.