Finding velocity of roller-bit and rotary-percussive drilling using the energy conservation law

Abstract

Velocity of roller-bit and rotary-percussive drilling depends on many factors distributed in 4 groups in technical literature: rock properties, bit parameters, bit-rock interaction conditions and drilling modes. Literature sources present some very complex formulas which need finding empirical coefficients before determining drilling velocity, i.e. the formulas are difficult to use. Moreover, the formulas neglect jointing of rock masses. At the same time, mathematical relations connecting drilling velocity, drilling mode and drillability of jointed rocks will make it possible to rate drilling processes and adjust blasting parameters. These studies aim to determine velocity of roller-bit and rotary-percussive drilling using the energy conservation law. The used method of mathematical modeling allowed obtaining formulas for rock drilling velocity with regard to drilling modes, bit parameters, factor of rock hardness (strength) and rock mass jointing. The validity of the relations of the roller-bit and rotary-percussive drilling velocity is proved. The reliability of the drilling velocity formulas can be determined by means of investigations performed in open pit mines, with recording of all parameters and with mathematical processing of the data. The mathematical relations connecting drilling velocity, drilling modes, drill bit parameters and drillability of jointed rocks will enable rating of drilling and adjustment of blasting patterns.