Method and results of an experiment to measure the mechanical drilling speed and durability of the 6L-145-Ok bit in relation to drilling conditions and rock hardness

Abstract

1. The lack of a device for measuring the “drillability” at any point in a borehole, together with frequent variations in the hardness (drillability) of the rocks, causes a great deal of difficulty in experiments to find the mechanical drilling speed and bit durability in terms of the drilling conditions and the rock hardness. 2. In drilling by milling-type bits, the drillability of the rock at any point in the borehole can be determined from the mechanical drilling speed in standard conditions. 3. The mechanical drilling speed can be plotted versus the rock hardness and drilling conditions by regular periodic drilling of the variable rock in standard and test conditions, all the drilling parameters being recorded automatically. 4. The bit durability can be determined as the product of the mechanical drilling speed in rock of given hardness in given conditions, multiplied by the bit lifetime in the same contions.