Patent ID: 7617887

Claim:
A method for casing drilling, the method comprising: drilling rock by rotating an inner rod ( 10 ) by a rotation device ( 9 ) included in a rock drilling machine ( 7 ), and breaking rock by at least one drill bit ( 11 , 14 ) and pulling an outer tube ( 13 ) into a borehole ( 12 ) during drilling; forming extension drill equipment by joining two or more inner rods ( 10 ) one after another in the longitudinal direction and by correspondingly joining two or more outer tubes ( 13 ) one after another in the longitudinal direction; turning the inner rod ( 10 ) about its longitudinal axis when the inner rods ( 10 ) are joined together or when the extension drill equipment is disassembled; turning the outer tube ( 13 ) about its longitudinal axis when the outer tubes ( 13 ) are joined together or when the extension drill equipment is disassembled; performing the turning needed to join the inner rods ( 10 ) and the outer tubes ( 13 ) non-simultaneously; turning the inner rod ( 10 ) and the outer tube ( 13 ) by means of the rotation device ( 9 ) of the rock drilling machine ( 7 ) and an adapter device ( 20 ) connected thereto when the extension drill equipment is being assembled or disassembled, characterized by using the adapter device ( 20 ) comprising an inner piece ( 21 ) to be connected to the inner rod ( 10 ) and an outer piece ( 22 ) to be connected to the outer casing ( 13 ) in the joining and disassembly of the extension drill equipment; supplying rotation force to the inner piece ( 21 ) of the adapter device ( 20 ) and transmitting it from the inner piece ( 21 ) to the outer piece ( 22 ); and moving the outer piece ( 22 ) in the axial direction with respect to the inner piece ( 21 ) to select whether the rotation force generated by the rotation device affects the inner rod ( 10 ) or the outer tube ( 13 ).