Drill Pipe Thread Failure Analysis And Research Measures To Improve

Drill pipe which is used in the sapping drill marine of coal mine receive several kinds of load which include bend, torsion, vibration, pull and press. The rupture of drill pipe often occurs in working. The rupture of drill pipe not only is effect on the producing, but also is difficult to salvage. So it will worsen accident and result the loss of manpower and money. Therefore, it is necessary to study drill pipe joint and analyze reasons of ruptures. And some available measures should be implemented to improve the quality of drill pipe and decrease accidents rate of drill pipe. So it has important value to guarantee well working states of drill pipe.Papers from the drill pipe joint connecting thread failure type analysis commence and adopt a flexible finite element method to establish a drill pipe connecting thread analysis model, aim at the current domestic coal mine tunnel drilling rig commonly usedΦ42 drilled a pole to carry on strength analysis, and carry on the morphology of the fracture, measuring chemical composition, hardness measurement, metallographic analysis to Drill pipe material, discuss the specific reasons for failure of the drill pipe rupture, the main causations are the high stress of the first joint drill pipe screw thread, joint drill pipe material strength insufficient reserves and heat treatment of instability etc.Put forward that model number design project of drill pipe on the structure, that is, cutting the bulky end of the outside drill pipe joint and change the taper of outside drill pipe joint tie-in two kinds of projects for the cause of the rupture of drill pipe. Analysis showed that: (1)Slice to the bulky end of the outside drill pipe joint, can effectively reduce greatly the loading comparison to attain 30 percent, for small-end bearing condition without influence. (2)Change the taper can significantly decreased the stress level of engagement bulky end, bulky end load ratio can be reduced to 23 percent. Material in the drill pipe joint and fracture analysis of the reasons for strict control by the heat treatment process and heat treatment to increase the hardness and strength to ensure that the drill pipe joint and properties of uniformity and consistency and made a specific heat treatment method.The drill pipe manufactured according to the upper improvement measures, through the major coal mine in the practical application, the drill pipe fault accident rate decreased significantly, and achieved good results, save for a large number of enterprises to improve the cost and shorten the time to improve and create a greater economic benefits and social benefits.