Mechanical Analysis And Performance Evaluation Of Mast Oil Workover Rig

The workover rig is one of the main key equipments for underground work,and is the key components of oil drilling and workover machines.It is mainly composed of the stell frame structure.The working environment and the load is bigger,and serious accidents often occur because of its strength failure and insufficient stability.Therefore,it is necessary to study the well frame structure of workover rig.This paper analyzed JJ80-29 W mast of oil workover rig frame structure characteristics by using ANSYS software.Firstly,The finite element software ANSYS is used to establish the finite element geometric model.Based on the theory of material mechanics and finite element,the mechanical analysis and research of the mast type oil workover rig are carried out.For the maximum hook load 800 k N conditions for strength analysis,according to the API standard safety factor is 1.67,and stress value exceed allowable stress,mainly happens on the top of the derrick and the both sides of the bottom of the mast,until the derrick safety factor increase to1.69,structure improved strength increased by 42%,The stress and displacement distribution of the derrick under different loading conditions were obtained.Secondly,the software ANSYS is used for modal analysis of the derrick,and the first 8order natural frequencies and vibration shapes of the derrick expansion are obtained.The analysis results show that the common derrick belongs to a large low frequency vibration structure,and will not have resonance with the outside world.Suggestions on the speed and gear design of the rotary system such as the turntable and the winch of the parallel trimming machine are put forward.The results show that the stiffness of the derrick in the left and right derrick is greater than the stiffness in the front and back directions and the relationship between the maximum displacement of the derrick in each direction and the modes of the derrick.Finally,the single member and the overall stability of the derrick are analyzed with the help of ANSYS,and the analysis shows that the local stability of the derrick is sufficient.When the dead weight of the derrick is not considered,the critical load value of the derrick is7849.50 k N,which is much larger than the maximum hook load,which indicates that the derrick will not be unstable.The critical load value of the derrick is 7949.10 k N when the critical load value of the derrick is considered.The comparative analysis of the two cases shows that the critical load value of the derrick considering the dead weight is greater than that without considering the critical load value.The derrick has a dead weight of 88.32 k N,which indicates that the dead weight of the derrick has little influence on its overall stability.The research results of this paper provide some theoretical guidance for other derrick design.