Drilling bit has shaft with drill crown, magnetic core movable in shaft, capacitor discharged via discharge contacts and electrodes in water to produce electrohydraulic pulse for breaking rock

摘要

The drill bit shaft contains a magnetic core in a discharge chamber and permanently facing north. Two discharge contacts cause a spark when touching the armature each turn. Electrodes in shaft apertures have positive poles connected to the discharge contacts and negative poles supplied by a current feed and carry water so a capacitor can discharge via the discharge contacts with the electrodes in water to give an electrohydraulic pulse. The drill bit has a shaft (1) with a drill crown (2) that uses hydraulic pulses to break rock. A movable magnetic core (6) mounted in an electrical discharge chamber (4) within the rotating shaft is permanently aligned with north. Two discharge contacts (5) rotating with the chamber cause a spark when contacting the armature once per revolution. Electrodes (7) in shaft apertures and pointing downwards have positive poles (10) connected to the discharge contacts and negative poles supplied by a current feed (9) and carry water flow so that a capacitor can be discharged via the discharge contacts with the electrodes in water to produce an electrohydraulic pulse.