Smith International, Inc.

Robert L Dixon

Malcolm D Maxsted

Robert E Allison

Jackson M Kellner

William J Neilson

A drill bit is disclosed for drilling large diameter shafts. The drill bit comprises a main bit body having a plurality of cutter assemblies rotatively mounted on the lower side thereof. The cutters contact and disintegrate the earth formations at the bottom of the shaft, thereby creating rock chips. The cutters are strategically located along arcuate paths and extending generally from the bit gage or periphery to the center of the bit. An arcuate channel is formed by the bit body to house the cutters and to provide a high velocity flow path for drilling fluid which engulfs all the cutters and flushes the rock chips away during operation of the bit. Drilling fluid containing rock chips enters the drillstring at the center of the bit body and is then pumped up and out of the shaft being drilled.

Large diameter drill bit

A removable shirttail of an earth boring tool, such as a hole opener, protects the seals and bearings of an associated cutter. In one embodiment, the shirttail attaches to a journal or mounting shaft of the cutter by threaded fasteners. In an alternate embodiment, different threaded fasteners that attach the journal to an associated leg of the tool cooperate with the cutter and the leg to clamp the shirttail between the journal and the leg. A wedge-shaped boss of the shirttail faces the wall of the bore being opened. A V-shaped saddle in the boss receives a complementary lug of the journal. The lug of the journal also mates with a complementary notch of the leg to prevent journal rotation. The removal of the theaded fasteners that attach the journal to the leg allows spacers or shims to be withdrawn, which in turn permits the cutter, journal, and shirttail to be moved along the journal axis to clear a nose of the journal from a bore in a central body of the tool. The cutter, journal, and shirttail can then be lifted from the tool. Removed, the shirttail can be replaced, and seals and bearing of the cutter assembly inspected without the renewal of other parts of the cutter assembly or yoke.

Replaceable shirttail

A raise drill is disclosed for enlarging a pilot hole into a large diameter hole by disintegrating the earth formations surrounding the pilot hole. The raise drill includes a bit body having a plurality of roller cutters mounted thereon. The bit body is detachable secured to a drive stem to permit removal and replacement of the stem. A shock absorbing element is interconnected between the drive stem and the bit body to enable the bit body to be flexibly mounted on the drive stem. A central yoke is provided to extend around the drive stem and interconnect the saddles of the two innermost cutters. The central yoke functions to distribute the loading of the inboard cutters. The central yoke can also function as a housing for a packing element.

Raise drill inner yoke bridge

A cutter assembly for a rotary head of a drilling machine comprises a yoke having a base for attachment to the rotary head, a pair of legs depending from the base, and an asymmetrical mounting hole through each leg, the hole being aligned with each other. A load pin extends between the legs of the yoke with the load pin being disposed within the holes. To prevent wear of the yoke during drilling, a replaceable wear pad is provided for each end of the load pin. Each pad is disposed between the load pin and the portion of the periphery of a mounting hole closest to the base. Thus, each wear pad is positioned at the loaded portion of the periphery of a mounting hole. Each wear pad extends around from about 1/3 to about 1/2 the circumference of the load pin.

Replaceable wear pad for a rock bit cutter yoke

A raise drill for enlarging a pilot hole into a larger diameter hole by disintegrating the earth formations surrounding the pilot hole is disclosed. The raise drill includes a main bit body having a plurality of cutters mounted thereon. The bit body is detachably secured to the drive stem to permit removal and replacement of the stem. The removable drive stem allows the raise bit to be transported through small drifts and helps extend the useful life of the raise bit. The drive stem extends through a central opening in the raise bit body and includes an upwardly facing shoulder for engaging the margin of the bit body about the opening. The drive stem further includes a plurality of tapered flat surfaces located about the periphery of the bottom end thereof. A plurality of bolted wedge blocks, attachable to the main bit body are provided to engage the tapered flat surfaces of the drive stem in order to urge the shoulder of the drive stem into locking engagement with the main bit body.

Raise drill with removable stem

This earth boring drill apparatus has a cutter mounting leg extending from one side of a drive stem and a removable cutter assembly, including a fixed shaft and cutter journaled for rotation on the shaft supported between the drive stem and the mounting leg. The stem has a bore for slidably receiving the inner end of the shaft. The cutter mounting leg terminates in an end surface extending parallel to the axis of rotation of the bore and shaft. A shaft supporting lug projecting from the outer end of the shaft has a surface which is parallel to the end surface on the leg. The opposed surfaces respectively have a V-shaped projection and mating groove which provide lateral alignment and prevent shaft rotation while permitting the shaft to be movable in an axial direction by an amount sufficient to permit the shaft to be withdrawn from the bore. Bolts extending between the mounting leg and the shaft at an angle clamp the mating surfaces of the groove and projection together and also clamp a pair of flat spacers between the mounting leg and the outer end of the shaft to lock the shaft in the bore.

Hole opener with improved rotary cutter mounting

A raise drill having a central drive stem to which a surrounding cutter mounting frame is attached, the cutter mounting frame supporting a plurality of rotary cutter units. One or more inboard cutter units each include a shaft and a rotary cutter journaled for rotation on the shaft. One end of the shaft is inserted in a bore extending into the side of the stem. A yoke member receives the outer end of the shaft. The yoke member is supported by a mounting block secured to the frame. The mounting block has first and second intersecting planar surfaces, the first surface extending substantially parallel to the axis of the bore and the second surface extending in an obtuse angle to the first surface facing the stem. The yoke member has a first surface which slidably engages the first surface of the mounting member, and a second surface spaced from the second surface of the mounting member, allowing axial movement of the cutter shaft into and out of the bore. A spacer or shim is inserted between the second surfaces after the shaft is inserted in the bore and bolts extending between the yoke and the mounting block pull the yoke against the mounting block and at the same time clamp the spacer in place.

Mounting for inboard cutters on a raise drill

A raise type of earth boring drill in which the cutter assembly is detachably secured to the drive stem to permit replacement of the stem. The stem slidably engages a central opening in the cutter assembly, the cutter assembly engaging a shoulder on the stem which carries axial loads in the drill. The cutter assembly is detachably anchored by a plurality of bolts to a torque plate attached to the end of the stem for transmitting torque load to the cutter assembly, the bolts clamping the cutter assembly against the shoulder.

Raise drill with replaceable stem

A drill bit construction of the rotary cutter type in which cutter journals extend downwardly from the bit body and toward each other at an angle, the provision of bearing sleeves removably mounted on the journals and rotary cutters removably and rotatably mounted on the bearing sleeves, permitting the replacement of the bearing sleeves or the customary roller or ballbearings and also permitting replacement of the rotary cutter itself if the latter has become worn or damaged.

Growing community of inventors

Brea, CA, United States of America

Robert L Dixon