Distribution of an Axial Load along the Teeth Rows of Rolling Cutters of Drill Bits (Test Results)

摘要

The durability of cutting elements and bearings of roller cutter drill bits depend on load level of their components. A considerable number of analytical and experimental studies are devoted to the study of regularities of distribution of efforts along the teeth of the cutting elements and roller bearing supports of drill bits. For experimental measurement of value of efforts, acting on separate teeth of each rolling cutter of the drill bit in the process of overrolling of drill bit under the load on metal bore-hole bottom, there was constructed the measuring device and special stand. This stand provides the possibility of testing of the drill bits of various standard types and sizes with a minimum expenditure of time and materials. The choice of the standard types of the drill bits is justified to conduct the research and of the testing methodology. The results of the research are suggested of distribution of axial load amoung the teeth rows of rolling cutters of drill bits with hardalloy and milled inserts. The results obtained made it possible to establish that the load on the teeth rows of rolling cutters distributes quite unevenly, and the intermediate teeth rows of rolling cutters are most loaded. At this, this unevenness remains unchanged at different constructive design of cutting elements. The distribution of axial load along the rolling cutters of drill bits is also uneven, the maximum axial load is taken by the first roller cutter, the minimum - by the third. However, the degree of unevenness of distribution of an axial load along the rolling cutters depend largely on constructive design and mainly on the location of teeth rows on rolling cutters alond the radius of the drill bit, which is especially significant for drill bits with hard-alloy inserts. It is established that the nature of the distribution of the axial loads along the teeth rows is related to the design of the rolling cutter support assembly. To reduce the unevenness of the distribution of an axial load between the teeth rows and the rolling cutters, it is necessary to change the scheme of interaction with the bore-hole bottom.