GB1295217A - - Google Patents

Abstract

1295217 Rock drills; screwing up tools ATLAS COPCO AB 28 May 1971 [15 June 1970] 17935/71 Headings B3C and B3N [Also in Division E1] A drill string joint breaking means comprises a drill string holder 21, an hydraulic pressure operated chuck 27, an hydraulic motor 32 for rotating the chuck, a conduit 37 (Fig. 6) for supplying hydraulic fluid to the motor and including a control valve 57, a branch conduit 63 supplying hydraulic fluid from the conduit 37 to the chuck, and a delaying valve 75 in the branch conduit delaying chuck closure until the motor and chuck are rotating so that the K.E. of motor and chuck provides torque for joint breaking. The chuck is in accordance with Specification 1,237,859 and is closed by fluid pressure, and the holder is opened by fluid pressure. Except that the non-return valve 75 has a delaying action the drilling apparatus is generally in accordance with Specification 1,238,109. The valve 57 controls the direction of rotation of motor and chuck and during drilling and making and breaking of a joint controls the opening and closing of holder and clutch. A valve 58 controls a linear motor 17 for feeding the drill head 14 comprising motor 32 and chuck, and during introduction and withdrawal of the string controls the opening and closing of the holder and chuck. With valves 57, 58, 61 set at positions b, the drill string 23 is supported by the holder. For drilling, valves 57, 58 are set at positions a and valve 61 is set at position b, the holder being open. -The valve 57 is moved to position b so that a pipe section and swivel may be added to the string which is supported by the closed holder. Valve 58 is moved to position c to raise the head so that drilling may recommence. During withdrawal of the string the valves 57, 58 are set at positions b, c respectively, the holder releasing the string and the chuck gripping and raising the string. The chuck is moved into position for breaking a joint by moving the valve 58 to position a, the string being supported by the holder. The joint is broken by moving the valves 58, 57 to positions b, c respectively, fluid flowing through the branch and valve 75 preventing closure of the chuck before rotation of the motor 32 and chuck. The string is inserted into the hole by setting valves 61, 57 to positions a, b respectively, the insertion being controlled by the valve 58. Both holder and chuck are opened for insertion of the bit, which may be a diamond or core drill, by closing valve 66, moving valve 57 to position b, and moving valves 58, 61 to positions a. In a modification, the holder may be rotated and axially displaced.