GB577110A - Improvements in or relating to drills for drilling wells - Google Patents

Abstract

577,110. Well-drilling. ZUBLIN, J. A. Dec. 8, 1943, No. 20508. [Class 85] Well-drilling apparatus having a hydraulicallydriven gyratory bit comprises a casing with a generally cylindrical interior and a watercourse at its upper end adapted to communicate with the interior of a drilling string, a hydraulic motor in said casing driven by fluid flowing in said watercourse and driving a shank, radial and thrust bearings between said shank and the casing, a bit mounted on said shank for rotation about an axis inclined at an acute angle to the axis of rotation of said shank, and a passage in said shank for flow of exhaust fluid from the motor to the bit. In Fig. 1, the casing A, with watercourse 112, has the motor stator 114 removably held by welds 117, and the shank B is secured to the rotor 122 and has an exhaust passage 129, bearings 132, 134 preventing axial and radial movement ; the shank has an inclined pin 137 on which the cutter bit C is rotatable, bearings 141 preventing axial and radial movement. In Fig. 4, the casing is secured to a slotted resilient drill guide 208 as in Specification 575,685, and the bearings 231, 234 supporting the shank allow limited axial movement of the latter. In another form, the motor stator has limited axial play and moves with the shank. The cutter bit may have teeth 242 extending from the periphery to the centre, and shorter teeth 243 in the same surface of revolution, while further teeth 244 lie in a higher surface of revolution, whereby in operation, vibratory movements are imparted to the shank.