Tkach M. Increasing of Efficiency of Locking Threaded Connections of a Drill String by Pulse Vacuum And Gasterosteus Ion-Plasma Nitriding

The thesis is devoted to the urgent scientific task on development of a set of scientific reasonable technological solutions aimed at the effectiveness increasing of the process of drilling holes through the efficiency increasing of locking threaded connections of a drill string by a pulse vacuum and gasterosteus ion-plasma nitriding method. To achieve the goal, a method of the pulse vacuum and gasterosteus ion-plasma nitriding was improved. With the help of the results of conducted experiments, the mathematical models were obtained, that show the criteria dependence of wear resistance optimization, endurance limits and corrosion resistance of locking threaded connections of a drill string from technological, functional and maintenance factors as well as the optimization of locking threaded connections of a drill string by pulse vacuum and gasterosteus ion-plasma nitriding method has been carried out. The following things were determined: parameters of the technological process and certain composition and structure of the strengthened surface layer. The defined parameters increase substantiality, maintenance and corrosion resistance. Based on theoretical and experimental studies the technological process of locking threaded connections of a drill string by pulse vacuum and gasterosteus ion-plasma nitriding was improved with a purpose to increase the efficiency of locking threaded connections of a drill string. The core of this process is a pulse mode of processing of the surface layer and it ensures the increasing substantiality limit by 20…40%, the wear resistance by 1.8-2.2 times and the corrosion resistance by 1.7-3.1 times, depending on the technological process parameters.