Rotary Drilling Rig, The Stability Of The Telescopic Drill Pipe Strength Finite Element Method Analysis

Piling rig , the optimum equipment for the foundation project , is usually used inthe large diameter hole drilling for its good function , high efficiency and littlepollution . As a key component of piling rig , the Kelly pipe is adapted to theformation and other drilling tools , such as rotary drive and different drilling bits .Because of the complex and variable condition of formations and the variablecross-section of the Kelly bar , the stress status of the Kelly bar is complicated duringthe process of deep hole drilling , it requires the strength of the Kelly bar to beadapted to the formation condition . Furthermore , different types of drilling toolsconnected to the Kelly bar are needed . All above show that the devise of strength,stability and structure of Kelly bar is considerably important to the whole set of pilingrig.In this article , it introduces the developing status of the piling rigs at present , thedifferent types of Kelly bar and the process that transfer the WOB (weight on bit) andthe torque step by step . Then , on base of the FEA method and FEA softwareANSYS , the results on strength , rigidity and stability of Kelly bar are got , whichindicate the stress distributing status and the location of the highest stress that lead thematerial failure under pressure and torque . Appling different constrains on both sidesof Kelly bar , we also get the curve of critical load on different constraints anddifferent depths in stability calculation . The results above can be provided to themanufacturer to further improve and optimize the Kelly bar and it also can beprovided to the engineering services to operate the piling rig with correct WOBdecreasing regulations.