| In the oil drilling industry,the split-type caliper logging tool plays an important role in the measurement of caliper data,and the high-precision and high-reliability operation of the push-back system is the key to ensure the accurate measurement of the caliper data by the split-type caliper logging tool.Therefore,it is of great significance to use the reliability analysis method to analyze the reliability of the push system of the split caliper logging tool from the perspectives of wear between components,mechanical structure and motion accuracy.The main contents of this paper are as follows:(1)The ADAMS software is used to establish the virtual prototype model of the push-by system of the separated caliper logging tool,and the dynamic analysis is carried out for different motion states.The force and motion curves of each key point in the push-by system are obtained,which lays a data foundation for the reliability and sensitivity analysis of the cam wear of the push-by arm,the reliability analysis of the structure of the push-by arm and the reliability analysis of the motion accuracy of the push-by system.(2)Taking the contact point between the cam and the piston rod as the breakthrough point,the mathematical model of the wear depth is constructed,and the curve of the wear reliability of the cam with the logging length is obtained.On this basis,through sensitivity analysis,the effect of different random variables on the wear failure probability is studied.The results show that the reliability of the push arm cam begins to decrease significantly when the logging work is about 1.5×10~7meters.The influence degree of each random variable on the wear failure of cam from large to small is sliding distance,allowable wear amount,material hardness,contact stress and wear coefficient.(3)After the static simulation analysis of the push arm by ANSYS Workbench software,the maximum equivalent stress and the maximum total deformation are taken as the output variables,and the load and size parameters of the push arm are taken as the input variables.By generating the response surface and carrying out the parameter sensitivity analysis,the structural reliability analysis of the push arm is carried out.The response curve,probability distribution table and probability distribution histogram of input parameters to output parameters are obtained.The results show that the x axial force at the pin slot of the push arm is positively correlated with the maximum equivalent stress and the maximum total deformation of the push arm,and the other input parameters are negatively correlated.The structural strength reliability of the arm is 0.99976 when the maximum allowable stress is 180MPa,and the structural stiffness reliability of the arm is 0.99961 when the maximum allowable deformation is 1.2mm.(4)In the case of considering the original size error and the clearance error of the kinematic pair,the reliability mathematical model of the motion accuracy of the push-back system is established by analyzing the motion state of the push-back system under the two states of opening and measuring.The reliability of the motion accuracy of the output end of the push-back system is analyzed and the reliability under different error conditions is compared.The results show that the displacement reliability of the output end of the push system is higher than0.9955,and the clearance error of the kinematic pair has little effect on the motion accuracy of the push system.Through the research of this paper,a relatively complete reliability analysis system of the push-up system of the separated caliper logging tool is established,which provides a theoretical basis for the prediction of the maintenance cycle of the push-up arm cam,the improvement of the wear reliability and the improvement of the reliability of the push-up arm structure.At the same time,the error factors affecting the reliability of the motion accuracy of the push-up system are analyzed,which has certain practical significance and guiding value. |
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