Rock drill with increased bearing life

Claim 2

In a rock drill wherein a rolling cutter is rotatably mounted on a cantilever bearing pin with the interposition of a set of balls disposed in a pair of registering circumferential races to lock the cutter on the bearing pin, and there is at least one pair of transversely extending and adjoining surfaces on the cutter and bearing pin, one each of the races and one each of the transverse surfaces on the exterior surface of the bearing pin while the other member of each pair is disposed on the interior surface of the rolling cutter, the improvement wherein said races and pair of surfaces are formed and disposed: (1) with said pair of transverse surfaces in frictional contact with one another, and (2) with a portion of at least one of the races spaced from the balls to prevent said balls from carrying outward thrust(.) and the remaining portion substantially tangent said balls in order to resist substantial inward movement from inward thrust.

Claim 3

The improved rock drill of claim 1 in which said races are formed and disposed so that the outboard portion of the bearing pinball race is spaced from the balls by a gap which extends from the outboard extremity of the race to its radially innermost portion, thereby preventing the balls from bearing radial loads as well as outward thrust.

Claim 4

The improved rock drill of claim 1 in which said races are formed and disposed so that the inboard portion of the rolling cutter ball race is spaced from the balls by a gap which extends from the inboard extremity of the race to its radially outermost portion, thereby preventing the balls from bearing radial loads as well as outward thrust.

Claim 5

The improved rock drill of claim 1 in which said races are formed and disposed so that both the outboard portion of the bearing pinball race and the inboard portion of the rolling cutter ball race are spaced from the balls by gaps.

Claim 6

The improved rock drill of claim 1 in which said races are formed and disposed so that both the outboard portion of the bearing pinball race and the inboard portion of the rolling cutter ball race are spaced from the balls by gaps extending from said portion to the deepest part of the race, thereby preventing the balls from bearing radial loads as well as outward thrust.

Claim 7

The improved rock drill of claim 1 in which the balls are gripped between the inboard portion of the bearing pin race and the outboard portion of the rolling cutter race to lock the cutter on the pin when said pair of transverse surfaces are in frictional contact with one another.

Claim 8

In a rock bit which includes at least one bearing piN member and a rolling cutter member mounted on such bearing pin to rotate with respect thereto, the bearing structure between said bearing pin and cutter including at least one thrust friction bearing defined by opposed transverse faces on the two members and a ball bearing consisting of a set of balls rolling in a toroidal raceway jointly defined by the two members, the improvement comprising selectively deepened portions in the toroidal raceway proportioned relative to the thrust bearing so that when the opposed faces of the thrust bearing come into thrust-transmitting contact with each other there is no load-transmitting contact through said balls other than the inward thrust transmitting contact which also locks the cutter to the bearing pin.

Claim 9

In a rock bit which includes at least one bearing piN member and a rolling cutter member mounted on such bearing pin to rotate with respect thereto, the bearing structure between said bearing pin and cutter including at least one thrust friction bearing defined by opposed transverse faces on the two members and a ball bearing consisting of a set of balls rolling in a toroidal raceway jointly defined by the two members, the improvement comprising selectively deepened portions in the toroidal raceway proportioned relative to the thrust bearing so that when the opposed faces of the thrust bearing come into thrust-transmitting contact with each other there is no load-transmitting contact through said balls other than the inward thrust transmitting contact which also locks the cutter to the bearing pin.

Claim 10

In a rock bit having at least one bearing pin depending cantilever fashion below the body of the bit and extending toward the axis of rotation of the bit, a rolling cutter or cone in the general form of a conical shell rotatably mounted on such bearing pin and locked thereon against inadvertent removal in a direction parallel to the axis of the bearing pin by a set of balls disposed in a pair of registering circumferential raceways, one on the outer surface of the bearing pin and the other on the inner surface of the rolling cone, there being a bearing structure between the rolling cone and the bearing pin which includes said balls and raceways and at least one friction bearing comprising a pair of transversely extending, confronting surfaces, one on each of the cone and pin, the improvement comprising portions of said ball raceways being undercut so that said rolling cone has a first or new position relative to the bearing pin in which said confronting surfaces are in outward thrust-transmitting contact and there are clearances in the undercut portions between said balls and the ball raceways, and contact between said balls and the ball raceways in the remaining portions, thus relieving the ball bearing of at least outward thrust loading, but transmitting inward thrust loading through said ball bearing, and a second or partially worn position in which there is a clearance between the confronting surfaces of the friction bearing and inward thrust-transmitting contact between cone, balls and bearing pin.

Claim 11

In a rock bit having at least one bearing pin depending cantilever fashion below the body of the bit and extending toward the axis of rotation of the bit, a rolling cutter or cone in the general form of a conical shell rotatably mounted on such bearing pin and locked thereon against inadvertent removal in a direction parallel to the axis of the bearing pin by a set of balls disposed in a pair of registering circumferential raceways, one on the outer surface of the bearing pin and the other on the inner surface of the rolling cone, there being a bearing structure between the rolling cone and the bearing pin which includes said balls and raceways and at least one friction bearing comprising a pair of transversely extending, confronting surfaces, one on each of the cone and pin, the improvement comprising portions of said ball raceways being undercut so that said rolling cone has a first or new position relative to the bearing pin in which said confronting surfaces are in outward thrust-transmitting contact and there are clearances in the undercut portions between said balls and the ball raceways, and contact between said balls and the ball raceways in the remaining portions, thus relieving the ball bearing of at least outward thrust loading, but transmitting inward thrust loading through said ball bearing, and a second or partially worn position in which there is a clearance between the confronting surfaces of the friction bearing and inward thrust-transmitting contact between cone, balls and bearing pin.

Claim 12

A journal bearing type rolling cutter assembly of a rock disintegrating drilling tool including a downwardly extending leg, a stub shaft projecting generally perpendicular to a surface of said leg, a rolling cutter secured on the stub shaft to rotate about the axis thereof, and an antifriction bearing between said cutter and stub shaft in the form of a circumferential row of balls disposed in a pair of registering toroidal raceways on the exterior of the shaft and the interior of the cutter, the radial and axial thrust bearings of said assembly otherwise comprising registering pairs of confronting surfaces on the two members, at least a portion of one of said ball raceways being selectively undercut so that axial thrust in the direction from the stub shaft to the leg is transmitted through one or more of said pairs of confronting surfaces and not through said balls and ball raceways(.) with the remaining portion of said undercut raceway contacting said balls to transmit axial thrust in the direction from the leg to the stub shaft.

Claim 13

A journal bearing type rolling cutter assembly of a rock disintegrating drilling tool including a downwardly extending leg, a stub shaft projecting generally perpendicular to a surface of said leg, a rolling cutter secured on the stub shaft to rotate about the axis thereof, and an antifriction bearing between said cutter and stub shaft in the form of a circumferential row of balls disposed in a pair of registering toroidal raceways on the exterior of the shaft and the interior of the cutter, the radial and axial thrust bearings of said assembly otherwise comprising registering pairs of confronting surfaces on the two members, at least a portion of one of said ball raceways being selectively undercut so that axial thrust in the direction from the stub shaft to the leg is transmitted through one or more of said pairs of confronting surfaces and not through said balls and ball raceways(.) with the remaining portion of said undercut raceway contacting said balls to transmit axial thrust in the direction from the leg to the stub shaft.

Claim 14

In the bearing of a rolling cone assembly which includes at least one pair of frictionally engaged axial thrust-transmitting surfaces on a bearing pin and a rolling cone and a circumferential row of balls disposed in a pair of mating raceways on said bearing pin and cone, said balls serving to lock the members together during operation, the improvement comprising a portion of said ball raceways being selectively deepened so that outward thrust is transmitted only through said thrust surfaces, and the remaining portion of each raceway mating with the balls to transmit inward thrust, wherEby said ball raceway on the bearing pin is relieved of loading and spalling of the raceway is reduced to prolong the life of the bearing.

Claim 15

In the bearing of a rolling cone assembly which includes at least one pair of frictionally engaged axial thrust-transmitting surfaces on a bearing pin and a rolling cone and a circumferential row of balls disposed in a pair of mating raceways on said bearing pin and cone, said balls serving to lock the members together during operation, the improvement comprising a portion of said ball raceways being selectively deepened so that outward thrust is transmitted only through said thrust surfaces, and the remaining portion of each raceway mating with the balls to transmit inward thrust, wherEby said ball raceway on the bearing pin is relieved of loading and spalling of the raceway is reduced to prolong the life of the bearing.

Claim 16

In the bearing of a rolling cutter rotatably mounted on a bearing pin, a pair of friction bearing surfaces one on the cutter and the other on the bearing pin and extending transversely of the axis of rotation of the cutter, said surfaces being in contact with each other to transmit outward thrust loading from the cutter to the bearing pin, and a ball bearing comprising a multiplicity of balls disposed in a registering pair of circumferential raceways on said bearing pin and cutter, one or both raceways being undercut so that the distance between the outward portion of the bearing pin raceway and the inward portion of the cutter raceway is larger than the ball diameter whereby the outward thrust loading is taken only by the friction bearing surfaces.

Claim 17

In the bearing of a rolling cutter rotatably mounted on a bearing pin, a pair of friction bearing surfaces one on the cutter and the other on the bearing pin and extending transversely of the axis of rotation of the cutter, said surfaces being in contact with each other to transmit outward thrust loading from the cutter to the bearing pin, and a ball bearing comprising a multiplicity of balls disposed in a registering pair of circumferential raceways on said bearing pin and cutter, one or both raceways being undercut so that the distance between the outward portion of the bearing pin raceway and the inward portion of the cutter raceway is larger than the ball diameter whereby the outward thrust loading is taken only by the friction bearing surfaces.

Claim 18

A lubricated and sealed rock bit cutter assembly comprising a stub shaft extending integrally from a leg of the bit and a rolling cone cutter surrounding and rotatably mounted on said stub shaft, the mounting of said cutter on the stub shaft being a composite bearing consisting of a circumferential ball bearing and friction bearings, said friction bearings including at least one journal bearing for radial loading and at least one pair of transversely extending thrust faces, such thrust faces being disposed one on each member and in registering and contacting relationship, said ball bearing comprising a multiplicity of balls disposed in a pair of generally registering and generally semicylindrical races on the two members, said races having dimensions and dispositions to lock the cutter on the shaft in the contacting position of said thrust faces by squeezing the balls between the outboard portion of the cutter race and the inboard portion of the shaft race, the other portions of at least one of said races being spaced from said balls so that outward thrust on the cutter is transmitted to the shaft only through said thrust faces.

Claim 19

A lubricated and sealed rock bit cutter assembly comprising a stub shaft extending integrally from a leg of the bit and a rolling cone cutter surrounding and rotatably mounted on said stub shaft, the mounting of said cutter on the stub shaft being a composite bearing consisting of a circumferential ball bearing and friction bearings, said friction bearings including at least one journal bearing for radial loading and at least one pair of transversely extending thrust faces, such thrust faces being disposed one on each member and in registering and contacting relationship, said ball bearing comprising a multiplicity of balls disposed in a pair of generally registering and generally semicylindrical races on the two members, said races having dimensions and dispositions to lock the cutter on the shaft in the contacting position of said thrust faces by squeezing the balls between the outboard portion of the cutter race and the inboard portion of the shaft race, the other portions of at least one of said races being spaced from said balls so that outward thrust on the cutter is transmitted to the shaft only through said thrust faces.

Claim 20

An improved bearing structure in a rolling cone rock bit, said bearing structure comprising an outboard journal bearing, an inboard thrust friction bearing defined by a pair of transversely extending surfaces, one on the rolling cutter and one on the bearing pin on which the cutter is rotatably mounted, and a circumferentially disposed ball bearing between said journal bearing and said thrust bearing, said ball bearing comprising a multiplicity of balls disposed in a toroidal raceway jointly defined by a race in the interior surface of the rolling cone and a similar race on the exterior surface of the bearing pin, such races being disposed so that in a newly manufactured assembly (1) the balls are squeezed between the outboard portion of the cone ball race and the inboard portion of the bearing pin ball race, (2) said pair of transversely extending surfaces are in frictional contact, and (3) other portions of at least one of said races define gaps with said balls to prevent said ball bearing from transmitting outward thrust and radial loads.

Claim 21

An improved bearing structure in a rolling cone rock bit, said bearing structure comprising an outboard journal bearing, an inboard thrust friction bearing defined by a pair of transversely extending surfaces, one on the rolling cutter and one on the bearing pin on which the cutter is rotatably mounted, and a circumferentially disposed ball bearing between said journal bearing and said thrust bearing, said ball bearing comprising a multiplicity of balls disposed in a toroidal raceway jointly defined by a race in the interior surface of the rolling cone and a similar race on the exterior surface of the bearing pin, such races being disposed so that in a newly manufactured assembly (1) the balls are squeezed between the outboard portion of the cone ball race and the inboard portion of the bearing pin ball race, (2) said pair of transversely extending surfaces are in frictional contact, and (3) other portions of at least one of said races define gaps with said balls to prevent said ball bearing from transmitting outward thrust and radial loads.

Claim 22

In a rolling cutter assembly consisting of a conical shell cutter rotatably mounted on a fixed bearing pin having a base portion and a pilot pin portion terminating with a free end, there being an annular shoulder on the end of said base portion surrounding its juncture with said pilot pin, the cutter having a bearing cavity conforming generally to the shape of the bearing pin which includes a transverse surface adjoining the annular surface of the bearing pin, said cutter being locked on the bearing pin against movement in the inboard direction, toward the free end of the bearing pin, by a set of balls disposed in a toroidal raceway jointly defined by a pair of generally registering circumferential races on the two members, the balls contacting both the inboard portion of the bearing pin ball race and the outboard portion of the cutter ball race to accomplish such locking, the improvemeNt comprising disposing said races and undercutting nonlocking portions of at least one of them so that said transverse surface of the cutter bears against the annular shoulder of the bearing pin to transmit outward thrust therethrough and at the same time the raceway space accommodating the set of balls has cross-sectional dimensions in at least the outward thrust direction greater than the diameter of the balls, thereby relieving the balls of at least outward thrust.

Claim 23

In a rolling cutter assembly consisting of a conical shell cutter rotatably mounted on a fixed bearing pin having a base portion and a pilot pin portion terminating with a free end, there being an annular shoulder on the end of said base portion surrounding its juncture with said pilot pin, the cutter having a bearing cavity conforming generally to the shape of the bearing pin which includes a transverse surface adjoining the annular surface of the bearing pin, said cutter being locked on the bearing pin against movement in the inboard direction, toward the free end of the bearing pin, by a set of balls disposed in a toroidal raceway jointly defined by a pair of generally registering circumferential races on the two members, the balls contacting both the inboard portion of the bearing pin ball race and the outboard portion of the cutter ball race to accomplish such locking, the improvemeNt comprising disposing said races and undercutting nonlocking portions of at least one of them so that said transverse surface of the cutter bears against the annular shoulder of the bearing pin to transmit outward thrust therethrough and at the same time the raceway space accommodating the set of balls has cross-sectional dimensions in at least the outward thrust direction greater than the diameter of the balls, thereby relieving the balls of at least outward thrust.

Claim 24

The improved rolling cutter assembly of claim 14 in which said undercutting provides a raceway space having a cross section larger than the diameter of the balls in both the radial direction and the outward thrust direction, thus relieving the ball bearing of radial loads as well as outward thrust.