Design And Research On Mechanical System Of Positioning Manipulator In Pressurized Crude Oil Environment

The crude oil heat exchanger is an important process equipment in the oilfield exploitation process,which is responsible for heat treatment of the crude oil and improve transportation efficiency.However,due to the complex composition and high viscosity of the crude oil,the heat exchanger is prone to blockage.In order to achieve effective cleaning without affecting the oilfield mining process,a new online automatic cleaning scheme for crude oil heat exchangers is proposed by combining traditional cleaning technology with robot technology.The positioning manipulator designed in this paper is an important part of it,which is responsible for driving the cleaning head movement and achieving precise positioning;The feasibility and performance of the device are of great significance to the realization of the entire online automatic cleaning solution.Therefore,a general scheme of the positioning manipulator is proposed for a pressurized crude oil environment,its mechanical structure and seal are detail designed.The structure of the manipulator is checked and the structure is improved by using computer software simulation to ensure the rationality of the design;Finally,considering the environmental factors,the joint force and driving characteristics of the positioning manipulator are studied to ensure the design and selection of the drive system is reasonable.The main contents of the paper are as follows:Firstly,according to the online cleaning task of the heat exchanger,the general scheme of the online cleaning device is clarified,the function and structural design requirements of the positioning robot is determined through analysis.The general scheme of the mechanical system for positioning manipulator is proposed,and the structure design,drive system design,sealing and mechanical system design of the mechanical system are carried out,finally the establishment of the initial three-dimensional model of the positioning manipulator is completed.Secondly,in order to prevent the crude oil from leaking into the inside of the manipulator housing,causing short circuit,electric leakage or damage to the charging device,the sealing structure of the positioning manipulator is designed.In order to ensure the reliability of the seal,the performance of the seal structure is verified by ANSYS software.The influence of sealing pressure and compression ratio of the sealing element on sealing performance is analyzed,which verifys the feasibility of the designed sealing structure and provides a theoretical basis for the parameter selection of the sealing structure.Thirdly,considering the special working conditions of the positioning manipulator,in order to obtain the static characteristics under the action of pressure environment,load and self-weight,ensure that the structural strength and rigidity of the manipulator meet the design requirements.The stresses and strains of the positioning manipulator initial model in the air environment and crude oil environment are analyzed separately.According to the analysis results,the structural improvement of parts with large stress and strain are carried out,and the rationality of the improved structure is analyzed.In order to find the optimal structure with high safety and economy,combined with the structural optimization design theory,the structural optimization model of the positioning robot is established.The structural parameters of the manipulator are optimized by ANSYS software.Finally,an optimized three-dimensional model of the positioning manipulator is established.Finally,in order to obtain the driving characteristics of the positioning manipulator in the pressurized crude oil environment and perform the drive system selection check,by analyzing the liquid force of the single moving body in the crude oil environment,the action moment equation of each liquid force on the rotating joint of the positioning manipulator is established.Because the viscosity of crude oil is large,the drag coefficient can’t be obtained based on experience.Based on Fluent fluid simulation software,the drag coefficient of the manipulator shell in the crude oil environment is solved.At the same time,the numerical simulation analysis of the positioning manipulator dynamics model established by Lagrange method is carried out in combination with Matlab software,the driving force and torque curve of the manipulator joint are obtained.The factors affecting the driving torque of the positioning robot are discussed and the selection of the drive system is checked.