Study on geometric features of conical threads

Abstract

The article studies the problem of oil/gas pipe conical thread reinforcement; in particular, the geometrical fundamentals for tool design for reinforcement. The article considers the main types of conical threads for pipes used in oil/gas industry. It was determined, that to obtain initial data for tools, used to reinforce thread crest and flank, it is necessary to consider conical threads not only as helical lines, but also as helicoid surfaces, to determine what helicoid parameters make the thread conical and obtain relations for the calculation of these geometric parameters. The authors determined geometrical parameters of conical threads and design parameters to develop rollers with deformed protrusions for simultaneous reinforcement of aforementioned thread crests and flank to improve tools for their frictional reinforcement. It was stated, that contrary to cylindrical threads, helicoid’s angles of inclination, which form conical threads, differ not only by the angle of inclination to the plane normal to their axes, but also by the values. The study of conical thread geometrical features refers to a cylindrical one allows to use these features in the design or improvement of tools for its manufacture and/or reinforcement. This approach allows improving the tools for frictional reinforcement of conical locking threads by modifying the lateral deforming elements. It makes possible to simplify tool manufacture, increase tool durability, reinforce the conical thread surface, and improve the quality, performance and economy of the conical thread frictional reinforcement.