US3866698A

US3866698A - Raise drilling bit

Info

Publication number: US3866698A
Application number: US416362A
Authority: US
Inventors: John M Stanley
Original assignee: Reed Tool Co Ltd
Current assignee: Camco Drilling Group Ltd; Reed Tool Co
Priority date: 1973-11-16
Filing date: 1973-11-16
Publication date: 1975-02-18
Anticipated expiration: 1992-02-18

Abstract

A rotary drill bit for producing a raise bore about a pilot hole including a drill head having an upper surface for mounting cutter assemblies. A lower surface spaced from said upper surface and having a drive stem attached thereto. The drive stem being adapted for limited or floating movement with respect to said upper mounting surface.

Description

United States Patent 1 Stanley 1 1 Feb. 18,1975

1 1 RAISE DRILLING BIT [75] Inventor: John M. Stanley, Houston, Tex.

[73] Assignee: Reed Tool Company, Houston, Tex. [22] Filed: Nov. 16, 1973 i [21] Appl. No.: 416,362

Henderson 175/73 Pessier 175/53 Primary Examiner-Frank L. Abbott Assistant ExaminerRichard E. Favreau Attorney, Agent, or FirmC. Kucera 57 ABSTRACT 10 Claims, 5 Drawing Figures [52] US. Cl. 175/53, 175/61 [51] Int. Cl. E2lc 23/00 [58] Field of Search 175/53, 61, 74, 263

[56] References Cited UNITED STATES PATENTS 2,938,710 4/1960 Tannehill 175/263 3,231,029 l/l966 Winberg 175/53 3,299,970 l/l967 Anderson 175/53 X PATENTED FEB 1 8 1 5 SHEET 10F 2 1 RAISE DRILLING BIT BACKGROUND The present invention relates to earth boring rotary drill bits, and particularly to drill bits for the drilling of raises extending from mine galleries or shafts at one level to galleries or shafts at other levels. Raise drilling comprises the drilling of a relatively small diameter pilot hole followed by enlargement of the hole to a predetermined raise diameter by rotating and raising the drill along the pilot hole to form a raise bore between a lower level and an upper level, the drill being rotated from above by a drill stem and guided by the pilot hole. The cuttings produced during such drilling operation are allowed to fall to the lower level.

Raise bores are usually 36 inches in diameter or more and the pilot hole may have a diameter of 9 to l5 inches. Such drill may weigh 5,000 pounds or more. As the raise drilling operation is commenced by rotation of the drill stern by a drilling rig, the bit may be rotated approximately l to 40 R.P.M. while the rig exerts an upward pull on the bit of approximately 150,000 to 950,000 pounds. As drilling progresses, sections of the drill stem, which may comprise cylindrical or tubular members approximately feet long, are progressively uncoupled at the upper level and the raise is completed by rotating and lifting the drill stem and the raise drill.

It will be appreciated that such drill bits, drill stems and the drive connections to the drill bits are subjected to severe wear and stresses whereby the cutters may have to be replaced, and at times the drive connection to the drill bit may fail, usually in fatigue. Thus it is desirable that the components may be readily replaceable for relative ease in handling in close places where otherwise the entire bit may be difficult to maneuver or transport.

SUMMARY The present invention provides a new and improved raise drill bit wherein the components may be readily replaced.

An object of the invention is to provide a new and improved drive stem arrangement for a raise drill.

Another object is to provide a drive stem attachment for a raise drill which is adapted to minimize stress ris ers to alleviate fatigue failures of the drive stem.

Another object is to provide a new and improved raise drill which is economical to manufacture and efficient in operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the raise drill.

FIG. 2 is a view taken along line 2 2 in FIG. 1.

FIG. 3 is a view similar to FIG. 2 but with the drive stem removed.

FIG. 4 is a plan view of the drive stem driving means.

FIG. 5 is a view taken along line 5 5 in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in the drawings, the raise drill includes an upper mounting member 11 and a lower attachment member 12.

Circular plates

13 and 14 and outer plate 15 may be secured as by welding to members 11 and 12 to form a drill head 16. Roller cutter assemblies 17 and 18 may be secured to mounting member 11 by welding or in any other suitable manner. The roller cutter assemblies may be of a type which is well known in the industry and may comprise a style of roller cutter assembly similar to that shown in US Pat. No. 3,385,385, issued May 28, 1968 to C. M. Kucera, et al.

Referring to FIGS. 2 and 5, a drive stem 20 is shown having a threaded connection 21 adapted to be attached to the lower end of a drill stem (not shown). The drive stem 20 may have upper and

lower flanges

22 and 23 secured thereto by welding or otherwise. Support 24 may be secured to the flange 22 and driver stem 20 and gussets 25 may be secured between support 24 and driver stem 20 to reinforce the connection between the driver stem 20 and the flange 22. The flange 22 may have driving pins 26 adapted to fit into openings 27 in the lower attachment member 12 to provide means for rotatably driving the drill head 16 with the driver stem 20. Cap screws 28 secure the flange 22 to member 12 of the drill head 16.

Referring to FIG. 3, the members 11 and 12 have

openings

30 and 31 therethrough to accommodate the driver stem 20, support 24 and gussets 25. The opening 30 is such that there is a clearance between the driver stem 20 and the upper mounting member 11 to provide limited or floating movement of the driver stem 20 with respect to the upper mounting member 11. This arrangement provides some flexibility of the stem 20 with respect to the drill head 16 and reduces stress concentrations in the driver stem 20 in the vicinity of the upper member 11 on which the cutter assemblies 17 and 18 are mounted.

The design of the present invention does not require mating tapered surfaces or exacting tolerances between the drive stem 20 and the drill head 16, yet provides a rugged drill bit which is easily assembled or disassembled by means of the cap screws 28, when replacement parts are required.

The provision of a raise drill bit having an upper surface for the mounting of roller cutter assemblies thereon, and having a lower surface, spaced from said upper surface, to accommodate a driving connection to the driver stem whereby the driver stem may float relative to the upper mounting surface, which has severe and irregular stresses imposed upon such surface by the cutter assemblies, results in a drilling bit which is less susceptible to fatigue failures, especially of the driver stern, during drilling operations.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. A rotary drill bit for producing a raise bore by disintegrating the earth formation surrounding a pilot hole comprising:

a drillhead having an upper mounting member and an attachment portion,

a plurality of cutters secured to said upper mounting member,

a drive stem,

said drive stern being fastened to said attachment portion and extending through said upper mounting member without force transmitting contact therewith thereby to be floating with respect to said upper mounting member.

2. A drill bit according to claim 1 wherein the upper mounting member is spaced from said attachment portion.

3. A drill bit according to claim 1 wherein the cutters are arranged to drill the raise bore in a single stage about the pilot hole.

4. A drill bit according to claim 1 wherein the cutters include rolling cutters.

5. In a rotary drill bit for producing raise bores by enlarging a pilot hole,

a drill head having an upper portion adapted to have secured thereon a plurality of cutters, and an attachment means,

a drive stem,

said drive stem being fastened to said attachment portion and extending through said upper mounting member without force transmitting contact therewith, thereby to be floating with respect to said upper portion.

6. A drill head according to claim 5 wherein said drive stem attachment means is spaced from said upper portion.

7. A drill head according to claim 5 wherein the cutters include rolling cutters.

8. A drill head according to claim 5 wherein the drive stem is removably-fast'ened to said attachment means.

9. A rotary drill bit for producing a raise bore by disintegrating the earth formation surrounding a pilot hole comprising:

a drill head having an upper mounting member and an attachment portion, a plurality of cutters secured to said upper mounting member, a drive stem, said drive stern being fastened to said attachment portion and extending with clearance through said upper mounting member for limited floating move ment with respect to said upper mounting member. 10. In a rotary drill bit for producing raise bores by enlarging a pilot hole,

a drill head having an upper portion adapted to have secured thereon a plurality of cutters, and an attachment means, a drive stem, said drive stem being fastened to said attachment means and extending with clearance through said upper portion for limited floating movement with respect to said upper portion.

Claims

1. A rotary drill bit for producing a raise bore by disintegrating the earth formation surrounding a pilot hole comprising: a drill head having an upper mounting member and an attachment portion, a plurality of cutters secured to said upper mounting member, a drive stem, said drive stem being fastened to said attachment portion and extending through said upper mounting member without force transmitting contact therewith thereby to be floating with respect to said upper mounting member.

5. In a rotary drill bit for producing raise bores by enlarging a pilot hole, a drill head having an upper portion adapted to have secured thereon a plurality of cutters, and an attachment means, a drive stem, said drive stem being fastened to said attachment portion and extending through said upper mounting member without force transmitting contact therewith, thereby to be floating with respect to said upper portion.

8. A drill head according to claim 5 wherein the drive stem is removably fastened to said attachment means.

9. A rotary drill bit for producing a raise bore by disintegrating the earth formation surrounding a pilot hole comprising: a drill head having an upper mounting member and an attachment portion, a plurality of cutters secured to said upper mounting member, a drive stem, said drive stem being fastened to said attachment portion and extending with clearance through said upper mounting member for limited floating movement with respect to said upper mounting member.

10. In a rotary drill bit for producing raise bores by enlarging a pilot hole, a drill head having an upper portion adapted to have secured thereon a plurality of cutters, and an attachment means, a drive stem, said drive stem being fastened to said attachment means and extending with clearance through said upper portion for limited floating movement with respect to said upper portion.