Patent ID: 7143846

Claim:
A drilling apparatus, comprising: a casing part; a first drilling element operative to drill a center hole and at least partially arranged within the casing part; a second drilling head element operative to ream the center hole; a removable power transmitting arrangement operative to couple the first drilling head element and the second drilling head element at least during drilling; a first frame part in which the first drilling head element is arranged; a second frame part in which the second drilling head element is arranged; and a flushing flow arrangement operative to flush waste, being generated by drilling, inside the case part, the flushing flow arrangement comprising a first transferring arrangement operative to transfer flushing medium centrally through the first drilling head element and then toward an outer periphery of the first drilling head element, the flushing flow arrangement further comprising a second transferring arrangement operative to carry out a reverse circulation of flushing medium from an outer periphery of the first drilling head element toward a central portion of a drilling surface of the first drilling head element and then internally through the first drilling head element toward a periphery of the first drilling head element into a space between the first frame part and the casing part.