PUNCHER TOOL

A device and a method are for perforating downhole casings. The method includes arranging a device on a drill string, running the device into a bore hole, dropping a ball down through the drill string down to the device for causing a first sequence of pressure rise and relief, causing a firing system to trigger a charge for punching one or more holes through a surrounding casing wall in response to the first sequence of pressure rise and relief, driving the pressure inside of the drill string up to a second level, and causing a rupture disc at the second level to burst so as to establish a fluid communication between the inside and outside of the drill string through the opening in the pipe wall of the pipe section.