Research On Calculation Method Of Strength And Stiffness Of Crank Pin And Bracket Of Beam Pumping Unit

The beam pumping unit is one of the main oil extraction equipment in the oil field.It has long-term work in the field,harsh working environment,long operating time,and long-term under alternating load,the pumping unit structure often suffer fatigue damage.There are many structure prone to fatigue damage in the structure of pumping units,such as brackets,beams,samson post bearing,pitmans,cranks,etc.It is obviously unrealistic to analyze strength of each structure,so this article takes structures bracket and crank for example for analyzing strength of structure.Through the analysis of the structural strength of the parts,the damage of the parts during the operation of the pumping unit is avoided,thereby reducing the occurrence of the shutdown of the pumping unit,the waste of resources caused by the remanufacturing process of the parts,and the economic loss caused by the shutdown.This paper focuses on the two parts of the crank pin and the bracket of the pumping unit,and studies the structural strength of these two parts.The main research is as follows:First,based on the longitudinal vibration of the rod and the law of suspension point motion,the reaction forces of the rods are solved to obtain the excitation force at the upper end of the bracket and the excitation force at the journal end of the crank pin,which lays the foundation for subsequent research.Secondly,this chapter analyzes the strength of the crank pin through statics and dynamics.Two methods of static analysis and ANSYS Workbench are used to analyze the stress distribution of the crank pin,and the results calculated by the two methods are compared.The dynamic analysis study considers the lateral vibration response of the crank pin when the crank body is deformed along the radius of the crank.Compared with the simulation results of ANSYS Workbench,based on the study of the lateral vibration displacement response of the crank pin,a method for solving the dynamic stress of the crank pin cross section is given,and the fatigue strength design of the dangerous cross section of the crank pin is designed based on the calculated dynamic stress results.Finally,the lateral vibration and dynamic stability of the bracket were studied by simplifying the bracket into a beam model.The specific contents include: establishing the mechanical model and mathematical model of the lateral vibration of the stent,applying the difference method to find the natural frequency and mode function of the stent,and applying the mode superposition method to solve the lateral forced vibration response of the stent;applying the Mathieu equation The dynamic unstable region and critical frequency of the stent are solved.In the end,the conclusion of this article is that the dynamics of the structural strength of pumping unit components under dynamic load conditions is more consistent with the forces of the components in the actual work of the pumping unit,and the structural strength of the pumping unit components is more accurate.