GB611036A - A core recovering device for use in diamond and rotary drilling - Google Patents

Abstract

611,036. Boring earth and rock. DUFFIELD, C. F. March 2, 1945, No. 5207. Convention date, Aug. 16, 1943. [Class 85] Means for obtaining cores in diamond or rotary drilling comprises a bit 1 with a tapered bore 11 adapted to co-operate with an outwardly tapered split ring 8 initially encircling the lower apertured end of a core tube 4 and slidably guided by lugs 5. At the upper end of the core tube is a non-return valve 45 allowing passage of water &c. and an adjustable threaded stem 6 which bears against a slidable valve member 7 pressed by a spring 30 and adapted to co-operate with a valve member 25. When short cores are required, a stop comprising a split tube 36 is locked at the desired height in the core tube by a screw 37 and a wedge member 38. Above the parts shown, a strainer is arranged in the drill tubing. In use, when the core sticks or contacts the stop or the end of the core tube, downward movement of the core tube stops. Drilling continues until the valve members 7, 25, contact to cut-off the supply of flushing water and so give an indication above ground; just before this, lugs 5 push the split ring 8 off the core tube, and on raising the drill string, the spring 30 acts through parts 7, 4, to press the split ring into the tapered bore 11 to cause the core to break.