<p>Determining the energy consumption of rock breaking using cone bits (CBs) during open-pit mining is crucial for evaluating drilling efficiency. This study investigates the energy consumption characteristics and drilling efficiency of rock breaking through numerical simulations and field drilling tests. A novel image processing-based method is presented for acquiring drilling pressure and rotational speed data from field cone bits. The concept of energy–time density is introduced to quantify the energy consumption. The results indicate that increasing rotational speed and axial pressure improves drilling speed in hard rock (hematite). Conversely, for relatively soft rock (green mudstone), optimal drilling speed is achieved with low axial pressure and high rotational speed. In medium-hard rock (phyllite), high rotation speed and medium axial pressure are recommended for improved drilling speed. At rock strata junctions, drilling force increases with increasing rock strength, while torque does not necessarily exhibit a corresponding relationship with rock strength. A drilling efficiency evaluation criterion is established based on drilling speed and energy–time density. For hematite, high drilling efficiency is observed when the drilling speed exceeds 3 mm/s, and the energy–time density falls within the range of 0.018 to 0.02 J/mm³&#xa0;s⁻¹.</p>