WO2008141138A2

WO2008141138A2 - Cutting head bearing arrangement for blast hole drilling machine

Info

Publication number: WO2008141138A2
Application number: PCT/US2008/063185
Authority: WO
Inventors: Timothy Murphy
Original assignee: The Timken Company
Priority date: 2007-05-10
Filing date: 2008-05-09
Publication date: 2008-11-20
Also published as: WO2008141138A3

Abstract

A drill head (10) bearing which incorporates a pair of tapered roller bearings (12A, 14A) separated by a row of ball-type rolling elements (18) to support a rotating drill head component (16) relative to a stationary component (24) disposed within an axial bore (30). Raceways (32, 34) machined into an inner surface rotating drill head component (16) and are configured to force loading of an outboard bearing (14A) having a larger diameter by offsetting the outer ring race (26) of an inboard tapered roller bearing (14A) having a smaller diameter. The smaller diameter tapered roller bearings (14A) is configured to support loads responsive to deflections of the rotating drill head component (16) exceed the offset designed into the outer ring race (26).

Description

CUTTING HEAD BEARING ARRANGEMENT FOR BLAST HOLE DRILLING MACHINE

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is related to, and claims priority from, U.S.

Provisional Patent Application No. 60/917,215 filed on May 10, 2007, herein incorporated by reference. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable. BACKGROUND OF THE INVENTION

The present invention is related generally to blast-hole drills, and in particular, to a drill head bearing arrangement for use with a blast hole drilling machine.

Drilling machines designed for boring blast holes into rock, such as during mining or construction, typically employ a rotating cutting head which is supported by bearings against a static drill head component. These bearings traditionally comprise a triple-row, full complement bearing arrangement which supports heavy radial and thrust loading. Generally, there are two rows of different diameter cylindrical rollers, separated by a row of ball-type rolling elements. The raceways of all three rows of bearings are machined into the static (or inner ring) and the dynamic (or out ring) components of the drill head. No bearing lubrication is used, and compressed air is circulated through the drill head to dissipate heat generated by the bearing. A typical service life for these bearings is merely 30 hours. Examination of failed traditional drill head bearing components often identifies edge loading and raceway surface damage, which is characteristic of insufficient lubrication. Accordingly, it would be advantageous to provide a drill head bearing which has an increased service life, which is capable of withstanding significant radial and thrust loads, and which incorporates a means of lubricating the various internal components. BRIEF SUMMARY OF THE INVENTION

Briefly stated, the present disclosure provides an improved drill head bearing which has an increased service life, which is capable of withstanding significant radial and thrust loads, and which incorporates a means of lubricating the various internal components.

In one embodiment, the present disclosure provides a drill head bearing which incorporates a pair of tandem-mounted single-row tapered roller bearings separated by a row of ball-type rolling elements. A lubrication- impregnated polymer (or solid lube) is molded into the cones to provide bearing lubrication during operation of the drill head. The rotating raceways are machined into the drill head bore and are configured to force loading of the larger, outboard bearing by offsetting the outer ring race of the smaller tapered roller bearing. The smaller tapered roller bearings support load only when deflections of the outer ring bore exceed the offset designed into the outer ring race, i.e. the bore of the blast-hold drill head.

The foregoing features, and advantages set forth in the present disclosure as well as presently preferred embodiments will become more apparent from the reading of the following description in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the accompanying drawings which form part of the specification:

Figure 1 is a sectional view of a prior art drill head bearing arrangement; and

Figure 2 is a sectional view of a drill head bearing arrangement of the present disclosure.

Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. It is to be understood that the drawings are for illustrating the concepts set forth in the present disclosure and are not to scale. DESCRIPTION OF THE PREFERRED EMBODIMENT

The following detailed description illustrates the invention by way of example and not by way of limitation. The description enables one skilled in the art to make and use the present disclosure, and describes several embodiments, adaptations, variations, alternatives, and uses of the present disclosure, including what is presently believed to be the best mode of carrying out the present disclosure.

Turning to the figures and to Figure 2 in particular, a drill head 10 having a bearing arrangement of the present disclosure is shown generally in sectional view. Preferably, the drill head bearing arrangement employs two tandem-mounted single-row tapered roller bearings 12A, 14A of different diameters (sizes). The smaller diameter tapered roller bearing 12A, adjacent to the tip 16 of the drill head 10 is separated from the larger tapered roller bearing 14A by a row of ball-type rolling elements 18. For optimal performance, the smaller tapered roller bearing 12A is configured with a suitable diameter, and each rolling element 12 has a suitable taper, selected to minimize geometric stress concentrations that result from asymmetric application loading.

During assembly, the tapered roller bearing inner rings (or cones) 20, 22 for each row of tapered roller bearings 12, 14, respectively, are installed on a stepped drill shaft component 24 of the drill head 10, which remains static during use. A lubrication member, such as a lubrication impregnated polymer (or solid lube) is incorporated into the cones 20, 22 to provide lubrication during use. The tapered roller bearing outer ring (or cups) 26, 28, providing raceways 32, 34 for each row of tapered roller bearings 12A, 14A, respectively, and are machined directly into an inner surface of a bore 33 of the rotating or dynamic component 30 of the drill head 10. Incorporation of the cup components 26, 28 into the drill head bore maximizes the size of the tapered rollers 12, 14 within the bearings. -A-

Preferably, the raceways 32, 34 for each row of tapered roller bearings 12, 14, respectively, which are machined into the drill head bore 30 are designed to force loading of the larger outboard bearing components 14A before loading the smaller inboard bearing components 12A. If the rolling elements 14 of the larger diameter outboard bearing component 14A and rolling elements 12 of the smaller diameter inboard bearing components 12A contact the raceways uniformly, the service life of the assembly is determined by the smaller of the two rows of tapered roller bearings. Hence, the inboard bearing cup race 20 and outer ring range 26 are shifted axially to facilitate the loading of the larger outboard bearing component 14A. The smaller inboard bearing components 12A support load only when deflections of the outer ring bore 28 exceed a threshold associated with the axial offset designed into the outer ring race 28, i.e., the bore of the blast-hole drill head 10. As sufficient wear occurs during use of the drill head 10 of the present disclosure, the smaller inboard bearing 12A gradually accommodate a greater portion of the loads.

In an embodiment of the present disclosure, a suitable annular drill head bore seal 36, such as a machined nylon washer, is provided in proximity to the outboard tapered roller bearing to minimize debris ingress and prevent purging of lubricants from within the drill head bore during operation.

As various changes could be made in the above constructions without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

CLAIMS:

1 . A drill head (10) bearing supporting a rotating outer component (16) against a stationary inner component (24) disposed within a bore (33) of the rotating outer component (16), comprising: a pair of tapered roller bearings (12A, 14A); and a row of ball-type rolling elements (18) separating said pair of tapered roller bearings (12A, 14A).

2. The drill head of Claim 1 wherein said pair of tandem-mounted single-row tapered roller bearings (12A, 14A) includes an inboard tapered roller bearing (12A) of a first diameter having tapered rollers (12) of a first taper, and an outboard tapered roller bearing (14A) of a second diameter having tapered rollers (14) of a second taper, said second diameter greater than said first diameter.

3. The drill head of Claim 2 wherein each of said single-row tapered roller bearings (12A, 14A) include cups (26, 28) machined within a bore of the rotating outer component (16).

4. The drill head of Claim 3 wherein said cup (26) of the inboard tapered roller bearing (12A) is axially offset, said axial offset selected to alter a loading between said inboard and outboard tapered roller bearings (12A, 14A).

5. The drill head of Claim 4 wherein said axial offset is selected such that initial loads on the rotating outer component (16) of said drill head (10) are carried by said outboard tapered roller bearing (14A) to said stationary inner component (24).

6. The drill head of Claim 1 wherein each of said single-row tapered roller bearings (12A, 14A) include cones (20, 22) mounted to said stationary inner component (24).

7. The drill head of Claim 6 wherein each of said cones (20, 22) incorporates a lubrication means adapted to provide bearing lubrication during operation of the drill head.

8. The drill head of Claim 7 wherein said lubrication means comprises a lubrication-impregnated polymer.

9. The drill head of Claim 7 wherein said lubrication means comprises solid lubrication member.

10. The drill head of Claim 1 further including a seal member (36) disposed outboard of the pair of tapered roller bearings (12A, 14A), said seal member (36) configured to minimize debris ingress and purge of lubricant from within the bore.

1 1 . The drill head of Claim 1 wherein said tapered roller bearings (12A, 14A) are tandem-mounted single-row tapered roller bearings.

12. A method for supporting a rotating drill head outer component (16) against a stationary inner component (24) disposed within a bore (33) of the rotating outer drill head component (16), comprising: providing at least a pair of tapered roller bearings (12A, 14A) within the bore (33), said pair of tapered roller bearings (12A, 14A) including an inboard tapered roller bearing (12A) having a first diameter and including tapered rollers (12) of a first taper, and a outboard tapered roller bearing (14A) having a second diameter and including tapered rollers (14) of a second taper, said second diameter greater than said first diameter; supporting an initial loading of said rotating outer drill head component

(16) with said outboard tapered roller bearing (14A); and responsive to deflection of the rotating outer drill head component (16) exceeding a threshold, supporting at least a portion of a loading of said rotating outer drill head component (16) with said inboard tapered roller bearing (12A).

13. The method of Claim 12 wherein said threshold corresponds to an axial offset of at least an outer ring race (26) of said inboard tapered roller bearing (12A).