Finite Element Analysis And Research On Optimum Design Of Drilling Tower Joints Of JYD-1000 All-hydraulic Core Drill

Drilling towers are the important constitution of drilling equipment. The main application of drilling towers is lifting and lowering drilling tools during drilling, hanging drilling tools during hydraulic drilling and lifting and lowering spigots in some conditions to settle well emergency. The materials of drilling towers generally are steels (structural sections or tubes) except woods used in portable triangular drilling towers. The design of drilling towers usually accepts analogy method in recent stage. There are a lot of weaknesses of analogy method such as wasting materials, increasing weights and low-usage performance of steel. The design of joints is easily ignored. There aren't references in nation. So it is necessary to research the joints of drilling towers.The major content of this paper are: Firstly, the static analysis of different type joints of drilling towers. Secondly, the analysis of the limited bearing capacity of T-joint in bending and tension. Third, the analysis of parameters of limited bearing capacity of T-joints, TT-joints and K-joints. Forth, optimize parameters of joints. The research of the paper has realistic significance as well as theoretical significance.1. The static analysis of different type joints of drill towersIn this paper finite element software ANSYS are used to create model and analysis the stress, strain and limit bearing capacity of joints. The steps of analyses are:1) Using the APDL parameter language of ANSYS to create finite element model of T-joint, TT-joint and K-joint.2) Applying restrain loading on the model and solving.3) Post-processing of finite element results. The general post-processing of ANSYS can get the von Mises stress and displacement.Using above methods and steps getting the stresses and displacements of every type joints in the normal using condition. The maximum value of stress can be seen from the distribution and stresses. The results show that the joints are safety.2. The analysis of limited bearing capacity of T-joint in bending and tension.T-joints in bending beared most of loading and deadweights of drill tower. The limit bearing capacity of T1-joints is related to the capacity of drill tower which is the most important parameters. So the research on T1-joints is the important aspect of this paper. By researching, the limit bearing capacity of T1-joints is 1050NM.The T-joints of variable cross-section on up tower bear the maximum loads. Both chief and branch are in tension. The finite element model is created according to solid model. Finally the limit tension is 239.96kN.3. The parameters research of T-joints, TT-joints and K-joints 1) For T-joints in bending the thickness ratioαof chief is larger and the displacements of joints is smaller on limit load. Forαlager value of joints the displacements is smaller. This phenomenon is agreement with side walls flexion failure mode. Forαsmaller value of joints the displacements is larger. Then chief web plate failure occurred, rather than chief side wall failure.2) The major factor of K-joints failure is vertical force of branch axial force. The rake angleθis smaller the vertical force is smaller and the limit bearing capacity is higher. The impact of the horizon force is relative smaller. The limit bearing capacity will be smaller as the increase of flakiness ratio of chief when the other parameters are same. The most important way to increase the limit bearing capacity is to enlarge the chief thickness when the width of chief is given.3) The ratio of branch and chief widthβis an important factor to impact the limit bearing capacity to TT-joint. It is useful to improve the limit bearing capacity of joints that keeping the width of the branch closed to the width of chief. The impact of ratio of branch and chief thicknessτis rather small. The limit bearing capacity will enlarge as the value ofτincreasing. But the amplitude is not great.4. optimized parameter of jointsThe parameters of T-joints, TT-joints and K-joints were optimized by ANSYS. The parameters of K-joints and the cross-section are changed. The nature of materials is sufficiently displayed and reducing deadweight, fabrication costs.