Research status and prospect of drill pipe thread used in coal mine

Drill pipe is one of the main device for drilling construction of gas drainage, water detection and drainage and geological exploration. Due to complicated force conditions and using environment of drill pipe, accidents in boreholes caused by the failure of drill pipe threads are common. According to different structural classification, the characteristics of drill pipe thread structure in coal mines are introduced in detail; the current research status of thread stress distribution and failure analysis of thread are summarized. The research methods of thread stress distribution mainly include analytical method, finite element method and test method. The main causes of thread failure are fatigue failure, brittle fracture and thread gluing. At the same time, the problems in the design and production of drill pipe threads are analyzed, including the inadequate basic research, the lagging manufacturing technology and the higher demand of new drilling technology for thread structure. Combined with the technical status of API thread and premium connection of petroleum drill pipe, the development direction of drill pipe thread used coal mine is discussed, including research on large diameter drill pipe thread, development of special thread used in coal mine, optimizing the force distribution of screw thread and the study of the dynamic cyclic composite load test method to evaluate the performance of drill pipe thread, etc.