Patent ID: 7717190

Claim:
A method for controlling a percussion device, the method comprising: providing impact pulses with the percussion device during drilling to a tool connectable to a rock-drilling machine; and generating a compression stress wave to the tool to propagate at a wave propagation velocity dependent on the tool material from a first end to a second end of the tool, with at least some of the compression stress reflecting back from the second end of the tool as a reflected wave that propagates toward the first end of the tool; and controlling the percussion device in the rock-drilling machine and its impact frequency, selling the impact frequency of the percussion device proportional to the propagation time of the stress waves that depends on the length of the used tool and the propagation velocity of the wave in the tool material; generating with the percussion device a new compression stress wave to the tool when the reflected wave from one of the previous compression stress waves reaches the first end of the tool; and summing the new compression stress wave and the reflected wave to produce a sum wave that propagates in the tool at the propagation velocity of the wave toward the second end of the tool.