U.S. patent application number 11/890800 was filed with the patent office on 2009-02-12 for expansion bail anchor and method.
This patent application is currently assigned to JENNMAR CORPORATION. Invention is credited to Demrey G. Brandon, Mark F. Novakowski, John G. Oldsen, Michael S. Reilley, John C. Stankus.
Application Number | 20090041550 11/890800 |
Document ID | / |
Family ID | 40339649 |
Filed Date | 2009-02-12 |
United States Patent
Application |
20090041550 |
Kind Code |
A1 |
Oldsen; John G. ; et
al. |
February 12, 2009 |
Expansion bail anchor and method
Abstract
An expansion anchor assembly for a mine roof bolt having a
tapered plug, expansion leaves, a bail and a removable holding ring
configured to hold the expansion anchor assembly in an assembled
position is disclosed. The tapered plug is configured to be
threaded onto the mine roof bolt and defines plug channels to
encourage symmetrical resin flow past the tapered plug. The bail
defines a medial opening through which the mine roof bolt
extends.
Inventors: |
Oldsen; John G.; (Butler,
PA) ; Stankus; John C.; (Canonsburg, PA) ;
Brandon; Demrey G.; (Pittsburgh, PA) ; Novakowski;
Mark F.; (Jamesville, NY) ; Reilley; Michael S.;
(Baldwinsville, NY) |
Correspondence
Address: |
THE WEBB LAW FIRM, P.C.
700 KOPPERS BUILDING, 436 SEVENTH AVENUE
PITTSBURGH
PA
15219
US
|
Assignee: |
JENNMAR CORPORATION
Pittsburgh
PA
|
Family ID: |
40339649 |
Appl. No.: |
11/890800 |
Filed: |
August 7, 2007 |
Current U.S.
Class: |
405/259.3 ;
405/259.6 |
Current CPC
Class: |
E21D 21/008 20130101;
E21D 20/025 20130101 |
Class at
Publication: |
405/259.3 ;
405/259.6 |
International
Class: |
E21D 20/00 20060101
E21D020/00 |
Claims
1. An expansion shell assembly for a mine roof bolt, comprising: an
expansion shell comprising a pair of leaves, said leaves each
having an outer surface for engaging a wall of a mine roof bore
hole and an inner surface; an internally threaded plug received
between said inner surfaces of said leaves for threading onto a
mine roof bolt, an outer surface of said plug defining a resin
groove; and a bail comprising a pair of legs and a medial member
therebetween, each said leg being attached to one said leaf, said
medial member defining an aperture through which a mine roof bolt
is extendable.
2. The expansion shell assembly of claim 1, wherein said medial
member defines a recess aligned with said resin groove of said
plug.
3. The expansion shell assembly of claim 2, wherein said medial
member is ring-shaped and two opposing portions of said medial
member have a reduced radial dimension.
4. The expansion shell assembly of claim 2, wherein said recess
comprises a notch in said medial portion.
5. The expansion shell assembly of claim 1, wherein an upper
surface of said plug receives said bail medial portion and said
plug defines a pair of bail grooves receiving a leg of said
bail.
6. The expansion assembly of claim 5, wherein said plug has a
sloped upper surface.
7. A mine roof bolt comprising: an elongated rod, said rod having a
drive end and a threaded portion; and an expansion shell assembly
as claimed in claim 1 threaded onto said rod threaded portion.
8. A mine roof bolt comprising: an elongated cable, said cable
having a drive end and a distal end; a threaded member fixed to
said cable; and an expansion shell assembly as claimed in claim 1
threaded onto said threaded member.
9. The mine roof bolt of claim 8, wherein said threaded member is
fixed to said cable at said cable distal end.
10. The mine roof bolt of claim 8, wherein said threaded member is
fixed to said cable at a position intermediate said cable drive end
and said cable distal end.
11. In an expansion shell assembly for a mine roof bolt comprising:
(i) an expansion shell comprising a pair of leaves, each said leaf
having an outer surface for engaging a wall of a mine roof bore
hole and an inner surface; (ii) an internally threaded plug
received between said leaves for threading onto a mine roof bolt;
and (iii) a bail comprising a medial member and a pair of legs
extending from opposing sides thereof, the improvement comprising:
said bail medial member defining a recess and said plug defining a
resin groove extending from an upper surface of said plug and being
aligned with said bail recess, such that resin is flowable through
said bail recess and into said plug groove.
12. The expansion shell assembly of claim 11, wherein said medial
member is ring-shaped and two opposing portions of said medial
member have a reduced radial dimension.
13. The expansion shell assembly of claim 11, wherein said plug
defines a plurality of resin grooves, said resin grooves being
aligned with said recess.
14. The expansion shell assembly of claim 11, wherein said bail
recess comprises a notch defined in said medial member.
15. A method of supporting a mine roof comprising: (a) inserting a
mine roof bolt into a bore hole containing a frangible curable
resin cartridge, the mine roof bolt comprising an elongated member
having a threaded portion and an expansion shell assembly received
on the threaded portion, the expansion shell assembly comprising:
(i) an expansion shell comprising a pair of leaves, the leaves
having an outer surface and an inner surface; (ii) an internally
threaded plug received between the leaves inner surface and
threaded on the threaded portion, an outer surface of the plug
defining a resin groove; and (iii) a bail comprising a pair of legs
extending from a medial member defining an aperture, each leg
attached to one of the leaves, wherein the elongated member extends
through the aperture; (b) rupturing the resin cartridge; and (c)
rotating the mine roof bolt such that resin is mixed and flows
through the resin groove, and the expansion shell expands and
engages the bore hole wall.
16. The method of claim 15, wherein the elongated member comprises
a rod.
17. The method of claim 15, wherein the elongated member comprises
a multi-strand cable.
18. The method of claim 17, wherein the threaded portion comprises
a tube fixed to the cable.
19. The method of claim 18, wherein the tube is fixed to the cable
at a position between the drivehead and the end of the cable.
20. The method of claim 15, wherein the bail medial member defines
a recess aligned with the plug resin groove so that resin flows
through the recess and resin groove.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to expansion bail-type mine
anchors and methods of their use.
[0003] 2. Description of the Prior Art
[0004] In underground mining operations generally, unsupported rock
formations may be reinforced by bolts inserted into bore holes that
have been drilled into the rock formations. These bolts may then be
secured within the bore hole to the rock formations by utilizing an
expansion anchor positioned on the distal end of the bolt. The free
end of the bolt extending into the mine passageway receives a
bearing plate. Rotation of the bolt within the bore hole expands
the expansion anchor to engage the rock surrounding the bore hole.
The expansion of the expansion anchor brings the bolt under tension
and further compresses the rock strata between the bearing plate
and expansion anchor to form a beam of rock strata that resists
forces that could stress the rock formations. Accordingly,
expansion anchors are widely used for supporting and reinforcing
rock formations in underground mining operations.
[0005] One type of expansion anchor includes a bail-type anchor
having a bail connecting two leaves of a hollow shell surrounding a
tapered wedge or plug. The tapered plug is generally internally
threaded and is threaded onto the distal end of a bolt. Upon
application of a rotation of the bolt, the plug threads downwardly
on the bolt, thereby forcing the shell to expand into gripping
contact with the bore hole wall.
[0006] Other expansion anchors include an expansion shell anchor
having three or four upwardly extending expansion leaves of a
hollow shell commonly joined at one end opposite a tapered plug
that is threaded onto a bolt. Upon rotation of the bolt, the leaves
of the shell expand into gripping contact with the bore hole formed
in the rock formation through the axial movement of the tapered
plug engaging the shell.
[0007] Typically, there are several methods employed for securing a
mine roof bolt within a bore hole. The bolt may be dry anchored in
the rock formation by engagement of an expansion anchor, either the
bail-type or the expansion-shell type, positioned on the end of the
bolt within the rock formation. Other methods include chemically
anchoring the bolt by bonding the bolt with resin to the rock
formation surrounding the bore hole, or using both an expansion
anchor and resin together to retain the bolt within the bore hole.
Resin is generally provided in a two-compartment cartridge, one
compartment for each of a curable resin composition and a catalyst
or curing agent. The resin cartridge is inserted into the blind end
of the bore hole in advance of the mine roof bolt. Upon insertion
of the mine roof bolt and rotation thereof, the cartridge is
shredded and its contents are mixed. Proper mixing of the curable
resin composition and curing agent without interference from the
cartridge housing are important to achieve good chemical
anchoring.
[0008] Bail-type anchors are traditionally difficult to use with
chemical anchoring. As the resin mixes and cures, the bail of
traditional bail-type expansion anchors has a tendency to bias and
become cocked, compromising the ability of the anchor assembly to
properly expand and engage the rock formation.
SUMMARY OF THE INVENTION
[0009] The present invention includes an expansion shell assembly
for a mine roof bolt comprising: (i) an expansion shell comprising
a pair of leaves, the leaves each having an outer surface for
engaging a wall of a mine roof bore hole and an inner surface; (ii)
an internally threaded plug received between the inner surfaces of
the leaves for threading onto a mine roof bolt, an outer surface of
the plug defining a resin groove; and (iii) a bail comprising a
pair of legs and a medial member therebetween, each leg being
attached to one leaf, the medial member defining an aperture
through which a mine roof bolt extends. The present invention also
includes a mine roof bolt comprising an elongated member having a
threaded portion and the afore-described expansion shell assembly
threaded thereon.
[0010] The present invention further includes a method of
supporting a mine roof comprising: (i) inserting a mine roof bolt
into a bore hole containing a frangible curable resin cartridge,
the mine roof bolt comprising an elongated member having a threaded
portion and an expansion shell assembly received on the threaded
portion of the expansion shell comprising: (a) an expansion shell
comprising a pair of leaves, the leaves having an outer surface and
an inner surface; (b) an internally threaded plug received between
the leaves inner surface and threaded on the threaded portion, an
outer surface of the plug defining a resin groove; and (c) a bail
comprising a pair of legs extending from a medial member defining
an aperture, each leg attached to one of the leaves, wherein the
elongated member extends through the aperture; (ii) rupturing the
resin cartridge; and (iii) rotating the mine roof bolt such that
resin is mixed and flows through the resin groove and the expansion
shell expands and engages the bore hole wall.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is an exploded side view of an expansion bail anchor
assembly in accordance with the present invention;
[0012] FIG. 2 is a side view of the expansion bail anchor assembly
of FIG. 1 showing the expansion bail anchor installed on a threaded
end of a bolt and positioned in a bore hole in an unengaged
state;
[0013] FIG. 3 is a side view of the bolt with expansion assembly of
FIG. 2 showing the expansion assembly during installation;
[0014] FIG. 4 is a perspective view of the bolt with expansion
assembly of FIG. 3 after installation;
[0015] FIG. 5 is a side view of the partially assembled expansion
assembly shown in FIG. 1;
[0016] FIG. 6 is a side view of the expansion assembly of FIG. 5,
with a retaining ring;
[0017] FIG. 7 is a side view of the expansion assembly of FIG. 1
installed on a threaded sleeve positioned at a proximal end of a
cable bolt;
[0018] FIG. 8 is a side view of the expansion assembly of FIG. 1
installed on a threaded sleeve positioned at a distal end of a
cable bolt;
[0019] FIG. 9 is a side view of the expansion assembly of FIG. 1
installed on a threaded sleeve positioned between the distal and
proximal ends of a cable bolt;
[0020] FIG. 10 is a perspective view of another embodiment of the
expansion assembly of the present invention;
[0021] FIG. 11 is a plan view of the bail used in the expansion
assembly of FIG. 5;
[0022] FIG. 12 is a plan view of the bail used in the expansion
assembly of FIG. 10; and
[0023] FIG. 13 is a plan view of another embodiment of a bail.
DETAILED DESCRIPTION OF THE INVENTION
[0024] For purposes of the disclosure, the terms "upper", "lower",
"right", "left", "vertical", "horizontal", "top", "bottom" and
derivatives thereof shall relate to the invention as it is oriented
in the drawing figures generally. However, it is to be understood
that the invention may assume various alternative variations and
step sequences, except where expressly specified to the contrary.
It is also to be understood that the specific devices and methods
illustrated in the attached drawings and described in the written
description are simply exemplary embodiments of the invention.
Hence, specific dimensions and other physical and spatial
characteristics related to the embodiments disclosed herein are not
to be considered as unduly limiting the present invention.
[0025] Referring to the drawings, and particularly to FIGS. 1-4,
there is shown a mine roof bolt 10 bearing a bail-type expansion
assembly 12. The mine roof bolt 10 is shown inserted into a bore
hole 14 surrounded by rock strata 16 in FIGS. 2-4 and including a
rod 18 having a drive end 20 that includes drive head 22 fixed to
the rod 18. A bearing plate 24 is generally positioned between
drive head 22 and the mine roof surface 26. Threaded distal end 28
of rod 18 receives the expansion assembly 12. The expansion
assembly 12 generally includes a bail 30, a tapered plug 32, a
plurality of expansion leaves 34 connected by the bail 30 and may
further include a removable retaining ring 36. The bail 30 is shown
in more detail in a flattened state in FIG. 11 and includes a
medial portion 38 and a pair of legs 40 that may be integrally
formed therewith. An opening 42 is defined in medial portion 38 for
receiving bolt threaded end 28 therethrough. Legs 40 are fixed to
leaves 34 in a conventional manner, such as via an attachment
member 44, such as a pin extending through both as shown in FIGS. 5
and 6. Attachment member 44 prevents bail 30 from moving in
directions parallel to the medial axis. Alternatively, attachment
member 44 may be formed integrally with the expansion leaf 34 or
bail legs 40.
[0026] As shown in FIG. 5, the tapered plug 32 defines a threaded
internal bore 46 for threading onto and traveling along a threaded
end 28 of mine roof bolt 10. Plug 32 includes an upper plug surface
48 that may be planar or frustoconical as shown. A pair of channels
50 for receiving bail legs 40 are defined in opposing sides of plug
32 and upper plug surface 48.
[0027] A pair of legs 52 extend from main portion 54 of plug 32,
thereby forming tapered surfaces 55. Main portion 54 further
defines a plurality of longitudinal plug grooves 56. The
longitudinal plug grooves 56 may be provided to encourage passage
of resin as described below.
[0028] Expansion leaves 34 may have a serrated outer surface 58
that generally extends circumferentially about the longitudinal
axis and tapering edge surfaces 60 along the serrated outer
surfaces 58. In an assembled position, as shown in FIGS. 5 and 6,
the leaf tapering edge surfaces 60 taper toward each other and abut
corresponding plug tapered surfaces 55. The distal end of leaves 34
may define rows of channels 62 formed therein.
[0029] When assembled (FIG. 6), bail medial portion 38 seats on
upper plug surface 48. In one embodiment, bail medial portion 38 is
generally ring-shaped with opposing sides of the ring having a
reduced dimensional portion 66 as shown in FIGS. 5 and 11. Other
configurations for a bail medial portion may be used. As shown in
FIG. 12, bail 130 includes bail medial portion 138 that is
generally ring-shaped. Alternatively, as shown in FIG. 13, a bail
230 having a bail medial portion 238 with reduced dimensional
portions or notches 266 may be used. Notches 266 are sized and
positioned to align with plug grooves 56 as shown in FIG. 10.
Reduced dimensional portion 66, 266 is sized and configured to
prevent interference of bail medial portion 38 (and/or 238) from
interfering with use of plug grooves 56.
[0030] Additionally, the reduced dimension portion 66, 266 may
encourage the even flow of resin on either side of expansion anchor
12 and help prevent cocking of the expansion anchor assembly 12.
Accordingly, the reduced dimension portion 66, 266 may be formed
symmetrically in any given embodiment. Further, the reduced
dimensional portion 66, 266 may encourage resin to flow through the
plug grooves 56 to further encourage the proper alignment of the
expansion anchor assembly 12 into the bore hole 14. In addition,
reduced dimensional portion 66, 266 may further encourage shredding
and mixing of a resin capsule and/or resin.
[0031] In use, a two-component (catalyst and curable resin) capsule
80 is inserted into the blind end of a bore hole 14. The mine roof
bolt 10 bearing expansion anchor assembly 12 is inserted into bore
hole 14 with bearing plate 24 positioned thereon.
[0032] Retaining ring 36, which may be formed of a breakable and/or
flexible thermoplastic material, is positioned around the expansion
leaves 34 and holds the expansion anchor assembly 12 together,
while the bolt 10 is being inserted into the bore hole 14. As the
bolt 10 is inserted into bore hole 14, the retaining ring 36
remains outside the bore hole 14 (FIG. 2) and is removed. Bolt 10
contacts and ruptures the capsule 80. Rotation of the bolt 10 about
its longitudinal axis mixes the curable component and catalyst
component, generating resin 82. Rotation of the bolt 10 also causes
plug 32 to travel toward the mine roof surface 26 on the threaded
portion end 28, thereby forcing expansion leaves 34 to spread apart
and engage the rock strata 16. The resin 82 flows downwardly around
and past the reduced dimensional portion 66, 266 and into plug
grooves 56 and the leaf channels 62, each facilitating the flow of
resin 82 over the expansion anchor assembly 12.
[0033] It should be appreciated that the improved expansion anchor
assembly 12 of the present invention may be implemented in chemical
anchoring or mechanical anchoring applications, although the
invention has been illustrated showing resin bonding to provide
chemical anchorage of the expansion anchor assembly 12.
[0034] As can be seen in FIGS. 7-9, a cable bolt as described in
U.S. Pat. No. 6,270,290, incorporated herein by reference, may
include the expansion anchor assembly 12 of the present invention.
Cable bolt 310 includes a multistrand cable 311 adapted to be
received within a bore hole. The cable 311 is preferably formed of
steel strands conforming to appropriate ASTM standards for a given
application. The cable 311 may generally have multiple strands with
a medial strand helically enclosed by outer strands. Cap 312 may be
included to provide integrity to the end of the cable bolt 310.
[0035] The cable bolt 310 may include "birdcages" 313 positioned
where the strands of the cable 311 are separated and partially
unwound from each other. A nut or washer 318 may optionally be
positioned on the medial strand of the cable 311 in the birdcage
313 to assist in maintaining spacing between the medial strand and
the surrounding strands. The provision of spaced birdcages may also
enhance the mixing and/or shredding of resin capsule 80 during
installation, as well as increase the bond strength of the
resulting chemical anchorage.
[0036] Cable bolt 310 includes a conventional drive head 322 (for
rotating the bolt 310) and barrel and wedge assembly 324 (for
tensioning the bolt). A sleeve or shaft 326 having a central bore
for receiving the cable 311 is fixed to the cable 311, such as by
crimping or swaging. The shaft 326 defines exterior threads 328
onto which expansion assembly 12 is threaded.
[0037] In use, cable bolt 310 is inserted into a bore hole
following insertion of a resin cartridge as with bolt 10 and
ruptures the cartridge. The cable bolt 310 is rotated using drive
head 322 to mix the contents of the resin cartridge and cause
expansion assembly 12 to grip the bore hole wall as described above
in reference to bolt 10.
[0038] When used with a cable bolt, expansion assembly 12 may be
positioned proximal to the drive end (as in FIG. 7), or may be
positioned at the end of the cable 311 (per bolt 310A of FIG. 8) or
intermediate the length of the cable 311 (per bolt 310B of FIG. 9).
Bolts 310A and 310B include the shaft 326 at a desired location for
mechanical anchoring. Stiffener sleeve 330 may be included to
assist insertion of bolts 310A and 310B into a bore hole.
[0039] The invention has been described with reference to the
preferred embodiments. Obvious modifications and alterations will
occur to others upon reading and understanding the preceding
detailed description. It is intended that the invention be
construed as including all such modifications and alterations
insofar as they come within the scope of the appended claims or the
equivalents thereof.
* * * * *