Methodology of Experimental Measurement of Loads, Acting on Rock Cutting Elements of Drilling Bit

摘要

To assess the reliability and durability of the cutting elements of roller cutter drill bits and bearing assemblies of rolling cutters, it is necessary to know the values of the forces acting on the rock cutting elements of a rolling cutter. A fundamentally new measuring device is known that allows measuring the value of force acting on each tooth of each rolling cutter when interacting with an indestructible bore-hole bottom, consisting of concentric steel rings divided into two sectors. To implement this method, a stand was designed for rolling the drilling bit under load on the bore-hole bottom of the measuring device. A methodology for measuring the forces acting on the cutting elements of a roller cutter drill bit is developed. The substantiation of the choice of the object of research is given and based on the results of the conducted methodical experiments and their statistical processing the minimum required duration of one test and the number of repetitions of each test are determined to obtain reliable results at a given level of confidence probability and permissible measurement error. The analysis of the scheme of interaction of cutting elements of one rolling cutter with the bore-hole bottom is made, on the basis of which it was concluded that the axial components of the forces have a greater influence on the useful life of the cutting elements than the tangential ones. Therefore, when selecting the test regimes, only axial components were evaluated. Optimal intervals of axial loads on the drill bit and bit rotation frequencies are determined, which allow to obtain an actual model of the distribution of forces on the cutting elements the drill bit. The developed methodology with the use of a computer makes it possible to obtain very quickly a large amount of reliable information about the loading of all cutting elements of roller cutter drill bits of various standard sizes for the purpose of optimizing the design of their cutting elements and bearings.