Indirect prediction of drill bit wear in andesite drilling

Rotary rock drilling of rocks deploys a combined action of normal and tangential forces induced by thrust force pressing against the drill bit along with rotation of the bit, delivering the loosening of rock chips from the solid rock mass after crossing its strength limits. Different mechanisms of rock breaking occur during the rock drilling, which depends on the applied thrust force. The highest probability of energy-convenient chipping occurs near the inflection point of the penetration-thrust curve. Energy theories of rock drilling consider the area surrounding the inflection point as the point where the energy necessary to break the unit volume of rock (i.e. specific energy) reaches its minimum. The inflection points of the designed model of penetration depth were fitted with exponential trend lines for two tested drill bits. The area of chipping moves to higher thrust forces due to bit's progressing wear. Indirect assessment and prediction of drill bit wear based on model of penetration depth used in process control enables to reduce the energy consumption and decrease the drill bit wear in underground construction and mining of mineral resources.