GB1051095A - - Google Patents

Abstract

1,051,095. Bearings. HUGHES TOOL CO. April 2, 1964 [April 22, 1963], No. 13671/64. Heading F2A. [Also in Division E1] In an earth-boring drill (Fig. 1, not shown), each of a plurality of rotary cutters 10 is supported on a pin 9 by a thrust bearing 14, a ball bearing 17, a roller bearing 18 and a plain bearing comprising a bushing 5 which engages with a cylindrical surface 16 on said pin and is made of a hard wear-resistant material having the hardness and wear-resistance of a carburized heat-hardened alloy-steel, e.g. high carbon steel, or mixtures of compounds such as carbides of tungsten and other metals adjacent thereto in the Periodic Table. The inner surface 1 (Fig. 3, not shown) of the bushing 5 comprises slots filled with a soft anti-galling metal 2, e.g. silver or a silver alloy, the slots being either straight and parallel to the axis of rotation of the cutter or helical (Fig. 3A, not shown). Alternatively, the surface 16 on the pin 9 is made of hardened steel in which axiallyorientated grooves are cut and filled with a soft anti-galling metal 39 (Figs. 4 and 4A, not shown). Lands 40 between the grooves may include bands 40<SP>1</SP>made of a hard alloy having a base of, e.g. iron or cobalt. The ball bearing 18 may be replaced by a plain bearing (Figs. 5A to 5E, not shown) wherein grooves or indentations in the bearing surface on the cutter are filled with soft anti-galling metal 23 . . . 23<SP>IV</SP>. Alternatively, the corresponding surface on the pin 9 includes a plurality of grooves 69 or 69<SP>1</SP> (Figs. 6A and 6B, not shown) filled with soft anti-galling metal. The thrust bearing 14 may comprise a button 14<SP>1</SP>(Fig. 10, not shown) lodged in the cutter and engaging with a surface 15 on the end of the pin 9 which has a coating 41 (Fig. 9, not shown) which is made of a cobalt-based alloy and includes recesses (not shown in the drawings) filled with soft anti-galling metal. Alternatively, the button 14<SP>1</SP>includes an eccentrically situated annular groove 27 filled with soft anti-galling metal which engages with the surface 15. A further thrust-bearing surface 41<SP>1</SP>on the pin 9 may include recesses 42 filled with soft anti-galling metal. Other examples of a soft anti-galling metal are lead, tin, copper, antimony, rhodium, platinum, palladium, gold, indium, bismuth, beryllium, zinc and aluminium. Lubrication of the ball bearing 17 is effected through passages 30, 31, 32 by a proportion of gaseous cooling medium which is supplied to the cutters 10. 'If the cutters are supplied with a liquid cooling medium, the bearing 17 is lubricated by grease which is lodged in passages 34, 35, 32 (Fig. 2, not shown) and driven into the bearing by a capsule 33 expanding when the pressure of said medium surrounding the cutters increases in accordance with the downward progress of the drill in the bore-hole. The lubricant supplied to the bearing 17 also serves to lubricate the other bearings.