Patent ID: 7604070
Filing Date: 2009-10-20
Classification: E21B

Abstract:
1. A method for controlling percussive rock drilling under the control of a control unit, the method comprising steps defined in a control strategy of the control unit and carried out by the control unit: controlling a percussion device in a rock drilling machine that gives impact pulses to a tool connected to the rock drilling machine during the drilling, controlling a rotating device in the rock drilling machine, the tool being rotated round its longitudinal axis during the drilling, controlling a feed device feeding the rock drilling machine during the drilling towards the rock to be drilled and correspondingly backwards, determining, during the drilling, at least rotation resistance, and registering a first moment of time when the rotation resistance exceeds a predetermined reference limit for the rotation resistance, decreasing the feed to control the rotation resistance towards the predetermined reference limit for the rotation resistance, determining at least a first limit and a second limit for the control, at least one of the limits being a time limit, carrying out at least one control action for adjusting the rotation resistance at the moment of time corresponding to each limit, setting the time difference between the starting moments of successive control actions according to the time limit, and further, decreasing the percussion power if the rotation resistance is greater than the reference limit for the rotation resistance at the second moment of time corresponding to the first limit, and stopping the feed if the rotation resistance is greater than the reference limit for the rotation resistance at the third moment of time corresponding to the second limit.