Research On Key Technology Of Lifting Transmission Design For Jack-up Offshore Drilling Platform

Currently, with the depletion of oil exploration on land, it has been mainstream to get into the ocean for drilling, mainly within 150 meters water depth. Jack-up offshore drilling platform with its unique advantage occupies an important position in the offshore oil and gas exploration and exploitation. Lifting transmission occupies a key position which cannot be substituted in the jack-up offshore drilling platform, and its performance not only affects directly the quality of jack-up platform in the process of using, but has a great influence on the operation of the platform and variable load. At present, lifting transmission of Jack-up offshore drilling platform is mainly produced by foreign manufacturers, therefore it is is very import to research on key technology of lifting transmission design for Jack-up offshore drilling platform.Taking the lifting transmission of one 300ft jack-up drilling platform for the research object, the deficiency of gear transmission design is analyzed, then improving its structure design. Dynamic response of hybrid gear transmission system is studied by using kinetic theory, and the strength and carrying capacity factors of large modulus rack and pinion are analyzed and calculated based on the analytical method and numerical method in jack-up drilling platform. Finally, in order to verify the correctness of above calculation method, a 300ft jack-up drilling experimental platform of pinion and rack is constructed in this paper. Here are the main contents:(1) By analyzing traditional structure design for hybrid gear transmission system of jack-up platform, pointing out its shortcomings, the structure is improved a differential planetary gear transmission to achieve the single-input and dual-output. According to design requirements, the main parameters of parallel shaft gear and differential gear are designed, and building the three-dimensional model of hybrid gear transmission system.(2) The lumped parameter method is employed to establish the dynamics model of the gear transmission system in Jack-up platform. The model is established after comprehensive considering the factors associated with time-varying mesh stiffness, dynamic transmission error, supporting stiffness and damping. Using Newton’s second law to establish dynamical differential equation of the model, and when solving dynamical differential equation, the calculation methods of relevant parameters are given, which contains mainly meshing stiffness calculation method. Solving the dynamic differential equations under constant load excitation by MATLAB, to get the dynamic response of gear transmission system.(3) Firstly, giving different calculation methods of root stress at dangerous cross-section of large modulus gear based on the theory of materials mechanics. Then, in order to get change law of stress in the rack and pinion meshing process, the dynamic and static characteristics of super-modulus pinion and rack are analyzed by finite element method, and the calculation results by using numerical method are compared as the results by using analytical method to verify its accuracy. Finally, Compared with the results of considering gear shaft to study the impact on bending stress of gear shaft.(4) Gear transmission experimental platform of lifting system in Jack-up platform is constructed, getting change law of the tensile-side and compression-side stress by collecting strain and stress in the root dangerous cross-section of large modulus pinion and rack. And the test results are compared as the results by using numerical method to verify the reliability of calculating bending strength of large modulus gear by finite element method.