The Performance Analysis And Structure Optimization Of Gearbox Of Full Casing Rotary Drilling Rig

Full Casing Rotary Drilling Rig is a new type and efficient construction equipment infoundation pile construction, which is widely used in a variety foundation work such asfilling piles, diaphragm walls, foundation reinforcement, etc. Based on the structurearrangement of gearbox on full casing rotary drilling rig, the gearbox bears large additionaldynamic loads during the process of operation, and its safety a very important guaranteefor the normal operation of drilling rig. Meanwhile since the rig has large size and highweight, the issues of production costs during the production process, the transport costsduring transitions process and also the site adaptability are the main concerned problemsfor enterprises and users. Therefore, it is necessary to make structure optimization underthe premise of ensuring the safety of gearbox. This paper has made a deep research on theperformance analysis and optimization of the gearbox of the full casing rotary drilling rig,regarded the gearbox as the research object, combined with the typical working situation ofthe full casing rotary drilling rig, the finite element method, the rigid flexible couplingmethod, and size optimization method are used for its analysis and optimization, to get thewhole performance characteristics of gearbox and then make optimization for gearbox. Themain contents of this article are as follows:1. This paper has summarized the development status and structural characteristics ofthe full casing rotary drilling rig at home and abroad, introduced the main content andmethod on the structure optimization design, analyzed the research significance and statedthe analysis of the ideas and research methods.2. This section mainly has introduced the basic theory of finite element method (fem)using in enclosure structure statics analysis, including its developing course, basic idea andthe basic analysis process. Based on the theory of elastic mechanics, this paper has explicitthe method to solve the problem of elastic mechanics unit space, and provides thetheoretical foundation for the finite element simulation analysis on gearbox in the thirdchapter. According to the actual stress state of gearbox for force analysis, this paper hasdetermined the boundary of the constraint condition of mechanics analysis. This paper alsohas analyzed and determined the box stress conditions, including the loads from geartransmission through the bearing acting on the enclosure in the box, the loads from thehydraulic motor in the upper box acting on the enclosure, and central platform loads on thecasing and so on, and provided the basis for the following static simulation analysis. 3. Through the simulation research on reducer gearbox under static and dynamicconditions to analyze its characteristics of static and dynamic stress. In static analysis,finite element analysis by ANSYS was carried out, which was under the working conditionthat the load of the full rotary drilling rig is the maximum. Based on this, the stress andstrain distributions of gearbox was obtained, then comparing the stress extreme value withmaterial allowable stress to check for the strength of gearbox and the safety of the structureused. In dynamics analysis, by rigid-flexible coupling method through ADAMS andANSYS co-simulation analysis to accomplish the dynamics simulation of gearbox to getthe stress and strain distributions in the whole working cycle of the full rotary drilling rig.Through comparative analysis of the result of static and dynamics simulation, it wasconcluded that the security coefficient of gearbox is2.38in static analysis, and the stressextreme value of dynamics simulation is206MPa, which is far from material stress limit of345MPa, as a result, the gearbox studied have further structural optimization space.4. Based on the optimization module of software ANSYS to make the structureoptimization of the gearbox. The thicknesses of plates are taken as the design variables, theextreme stress of gearbox which is set for smaller than the material stress limit is taken asthe constraints, and the total mass of gearbox which is looking for the smallest one is takenas the objective function, then the size optimization of gearbox is made and the optimumthickness combinations are obtained. After optimization, the total mass of gearbox isreduced from724.4kg (the previous optimization) to527.1kg, decreased by27.2%, and theweight of gearbox has been effectively reduced. Then analyze the overall performance ofthe gearbox before and after optimization. The security coefficient of after-optimizationgearbox in static analysis is reduced from2.38to1.55, and the security coefficient is morereasonable; also the extreme stress in dynamic analysis is changed from206MPa to310MPa, and the material of gearbox has been fully utilized. Meanwhile the stress andstrain distribution of gearbox is more reasonable, and the optimization results are effective.