Patent ID: 7114576
Filing Date: 2006-10-03
Classification: E21B

Abstract:
1. A method in connection with a rock drill apparatus, which rock drill apparatus comprises a rock drill machine provided with a percussion device, a feed device and a tool, the tool end comprising a bit for breaking rock, and the tool being arranged to transmit impact energy generated by the percussion device as a compression stress wave to the bit and the feed device being arranged to thrust the tool and the bit against the rock to be drilled, whereby on drilling at least part of the compression stress wave generated by the percussion device to the tool reflects from the rock to be drilled back to the tool as tensile stress, the method comprising determining the penetration rate, determining the level of tensile stress reflecting from the rock to be drilled to the tool on the basis of interdependence of drilling penetration rate and the level of the tensile stress and adjusting impact energy of the percussion device on the basis of the level of tensile stress reflecting from the rock to be drilled to the tool.