FIXATION BAIL

Abstract

A bail (20) for an expansion shell assembly which is formed from a continuous elongate metallic member shaped to have a yoke (24), at least two U-shaped legs (26,28,30) which extend from the yoke, and a biasing element (76) which projects from the yoke.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to a rock or anchor bolt and, more particularly, is concerned with a bolt of this type which makes use of a mechanically activated expansion shell assembly.

An expansion shell assembly typically includes a wedge member and a number of leaves which are held together, at spaced locations around the wedge member, by means of a bail. Each leaf is directly attached to a leg of the bail by means of spot welding or the like.

FIG. 1 of the accompanying drawings illustrates a sheet metal blank 10 from which bails of the aforementioned kind are made. An opening 12 in the blank outlines material which is removed to form a bail. Each bail has a central, circular yoke 14 and (in this case) three legs 16 which are integrally formed with the yoke and which are spaced apart at 120 degrees from each other. The plate 10 typically is about 1 millimetre thick.

The bails are precisely positioned on the strip 10 to minimize the production of waste material when the bails are stamped or otherwise formed from the strip 10. Nonetheless a substantial amount of waste material is produced—this is evident from an inspection of FIG. 1 in which a hatched area 18 represents material within the strip which is wasted or which otherwise must be recovered for recycling or similar purposes.

It is an object of the invention to provide a bail in which the generation of waste material is substantially eliminated. This helps to contain costs.

SUMMARY OF THE INVENTION

The invention provides a bail for an expansion shell assembly which includes a body which has a yoke and a number of legs extending from the yoke and which is formed from an elongate member.

The elongate member is preferably a continuous elongate length of metal e.g. wire or a thin rod.

The yoke may be formed at least partly by one or more sections of the elongate member which bound, at least partly, a central region of the body.

The central region may be substantially circular in outline.

A portion of the elongate member may extend across the yoke.

The portion of the elongate member may be secured to the yoke e.g. by spot welding the portion to the yoke at a location at which the portion overlies, and is in contact with, the yoke, or by crimping the portion, e.g. at an extremity, to the yoke.

Each leg may be of any suitable shape and preferably is in the form of an elongate U. Extremities of the U are conveniently shaped to facilitate attachment of each leg to a respective leaf in an expansion shell assembly.

The bail may include a biasing element. Preferably the biasing element is formed from part of the elongate member. The biasing element may be of any suitable shape or form.

The biasing element may extend from the yoke. Preferably the biasing element is in the form of a coil spring which projects from one side of the yoke.

The invention also extends to an expansion shell assembly which includes a wedge member, a plurality of leaves which are positioned at spaced locations around the wedge member, and a bail of the aforementioned kind, and wherein each leg of the bail is attached to a respective leaf.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described by way of examples with reference to the accompanying drawings in which:

FIG. 1, which has already been referred to hereinbefore, relates to prior art bails;

FIG. 2 is a plan view of a bail according to a first form of the invention;

FIG. 3 is a side-view of an expansion shell assembly which makes use of a bail of the kind shown in FIG. 2; and

FIG. 4 is a perspective view of a bail according to a second form of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 2 of the accompanying drawings illustrates a bail 20 according to a first form of the invention which is manufactured on a CNC wire bending machine using an elongate metallic member, e.g. a length of wire 21 of a suitable diameter.

The wire bending machine is programmed using techniques which are known in the art to bend the wire 21 into a desired shape. During production the wire is shaped at great speed and with substantial economy in material. No scrap wire is generated and material handling processes and the costs associated therewith are greatly reduced.

In this example the bail 20 has a body 22 with a central yoke 24 and three legs 26, 28 and 30 which extend from the yoke. The yoke is formed at least partly by a number of sections 32, each of arcuate shape, which bound a central region 34 of the body which is substantially circular in outline.

Adjacent legs are spaced apart from each other, in an angular sense, by about 120°. Each leg is in the form of a elongate U and includes opposed, spaced parallel limbs 36 and 38 respectively and a bridging, curved portion 40 at an outer extremity of the limbs.

An end section 42 of the wire 21 extends centrally into the circular region bounded by the yoke. At a location 44 where a part of the section 42 overlies, and is in contact with, a part of the yoke, the section 42 is secured to the yoke, e.g. by using an automated spot welding technique. The two wire parts could alternatively be fixed together by mechanically deforming e.g. crimping one or both parts, or by wrapping or twisting the end section 42 around the yoke.

It is apparent from a comparison of FIG. 1 and FIG. 2 that the bail 20 conforms in outline substantially to the bail opening 12 shown in FIG. 1.

The yoke 14, of a bail made using the technique shown in FIG. 1, consists of a solid piece of the sheet material. In the bail 20 the yoke 24 is not continuous and the section 42 is formed to enable the wire bail to act, effectively, in the same way as the sheet metal bail.

FIG. 3 is a side view of an expansion shell assembly 50 which includes a centrally positioned wedge member 52, only a small portion of which is visible, three leaves 54 which are positioned at locations which are spaced apart by 120° from each other around the wedge member, and a bail 20 of the kind shown in FIG. 2. The yoke 24 overlies a central portion of the wedge member and the legs 26, 28 and 30 are folded, from the planar arrangement, shown in FIG. 2, through 90° so that each leg partly overlies a respective leaf 54. An extremity of each leg is tack-welded to a respective leaf 54. Alternatively, as shown in FIG. 3, a small rivet or similar upset member 56 is deformed to secure the leg to the leaf. The latter process can be facilitated, if required, by bending the wire at the curved portion 40 of each leg, into a closed loop e.g. a circle 60 as is shown for the leg 30 in FIG. 2.

An advantage of using a CNC wire bending machine is that the wire which forms the bail can be shaped, within reason, in any appropriate way to facilitate attachment of the bail to the leaves of the expansion shell assembly. Although the bail is preferably formed from a continuous length of wire it could be formed from two or more wire lengths but, in this event, there would normally be attendant costs and technical implications.

The section 42 overlies the mouth of a passage which extends centrally through the wedge member and functions, in use of the expansion assembly, in a manner which is similar to the way in which the solid yoke 14 shown in FIG. 1 functions.

FIG. 4 shows, in perspective, a bail 64 according to a second form of the invention which is also made on a CNC wire bending machine using an elongate length of wire 66. The bail 64 has a central yoke 68 of generally circular outline and legs 70, 72 and 74 which are generally the same as the legs shown in FIG. 2 and which are positioned at locations spaced apart by 120° around the yoke 68. The bail includes an integrally formed biasing element 76 in the form of a helical coil spring which is centred on the yoke 68 and which, in use, is oriented to face onto the centrally positioned passage, referred to in connection with FIG. 3, in the wedge member 52. At a location 44A, on the yoke, overlapping parts of the wire 66 which contact each other are spot welded together. This stiffens the bail and helps the bail to retain its shape during installation of the expansion shell assembly. For reasons which are known in the art and which are not further described herein the inclusion of the biasing element, integrally provided with the remainder of the bail, substantially facilitates use of the expansion shell assembly when a rock bolt is installed.

Claims

1-13. (canceled)

14. A bail for an expansion shell assembly including:

a body having a yoke and a number of legs extending from the yoke and formed from an elongate member, the bail comprising:

a biasing element formed from part of the elongate member.

15. The bail according to claim 14 wherein the elongate member comprises a continuous elongate length of metal.

16. The bail according to claim 14 wherein the yoke is formed at least partly by one or more sections of the elongate member which bound, at least partly, a central region of the body.

17. The bail according to claim 16 wherein a portion of the elongate member extends across the yoke.

18. The bail according to claim 14 wherein each leg is in the form of an elongate U and includes opposed, spaced, parallel limbs and a bridging portion at an outer extremity of the limbs.

19. The bail according to claim 18 wherein the bridging portion of each leg is formed into a closed loop.

20. The bail according to claim 14, wherein at the yoke, a first part of the elongate member is secured to a second part of the elongate member by welding, or by mechanical deformation of at least one part.

21. The bail according to claim 14 wherein the biasing element comprises a coil spring on one side of the yoke.

22. A bail for an expansion shell assembly formed from a continuous elongate metallic member shaped to have a yoke, and at least two U-shaped legs which extend from the yoke, the bail comprising a biasing element projecting from the yoke, and configured as a helical coil.

23. A bail for an expansion shell assembly formed from a continuous elongate metallic member shaped to have a yoke, and at least two U-shaped legs extending from the yoke, the bail comprising:

a biasing element projecting from the yoke, and wherein at the yoke, a first part of the elongate member overlies, and is in contact with, a second part of the elongate member, and the first part is secured to the second part by welding or by mechanically deforming at least one of the parts.

24. An expansion shell assembly having a wedge member, and a plurality of leaves positioned at spaced locations around the wedge member, the expansion shell comprising the bail according to claim 14, and wherein each leg of the bail is attached to a respective leaf.