AU2007203018A1

AU2007203018A1 - Method of sealing hollow bolts

Info

Publication number: AU2007203018A1
Application number: AU2007203018A
Authority: AU
Inventors: John Horsch; Steven Lee Weaver; Darren Leslie Webb
Original assignee: Sandvik Intellectual Property AB
Current assignee: Sandvik Intellectual Property AB
Priority date: 2006-06-29
Filing date: 2007-06-28
Publication date: 2008-01-17

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): Sandvik Intellectual Property AB Invention Title: METHOD OF SEALING HOLLOW BOLTS The following statement is a full description of this invention, including the best method of performing it known to me/us: -2- HOLLOW ROD ;Technical Field The present invention relates generally to hollow rods. The invention has particular 0 application for steel hollow rods used in rock bolting applications and the invention is herein described in that context. However, it is to be appreciated that the invention has 00 broader application and is not limited to that particular use.

Background of the Invention Roof and wall support is vital in mining and tunnelling operations. Mine and tunnel walls and roofs consist of rock strata, which must be reinforced to prevent the possibility of collapse. Rock bolts are widely used for consolidating rock strata. In this context the term "rock" as used in the specification is to be given a broad meaning to cover both hard rock applications as well as softer strata, such as that found in coal mines.

In conventional strata support systems, a hole is drilled into the rock by a drill rod, which is then removed and a rock bolt is then installed in the drilled hole and secured in place typically using a resin and/or cement-based grout. To improve this process, selfdrilling rock bolts have been proposed whereby the bolt is also used as the drill rod. As such, with a self-drilling rock bolt, the hole can be drilled and the bolt installed in a single pass.

In both these strata support systems, fluid needs to be conveyed into the drilled hole.

This fluid may be for the purposes of drilling to flush particulates from the cutting tip and/or to introduce a resin or cement grout so as to secure the rock bolt in place.

To introduce fluids into the drilled hole, hollow rods have been proposed for use either as a drill rod, or a rock bolt or a self-drilling rock bolt. In these applications, the central cavity of the rod is used as part of a circulation passage to either introduce or remove fluid from the drilled hole.

Summary of the Invention In accordance with a first aspect, the present invention provides a hollow rod having opposite ends, a longitudinal cavity extending between the ends, and at least one longitudinally extending seam, the rod further comprising a sealing arrangement to inhibit fluid leakage through the seam whilst fluid is passed along the cavity.

-3- SIn one embodiment the sealing arrangement is in the form of a settable material ;disposed in the seam.

00 C 5 In a particular form the settable material is polymeric. In a particular form, the settable material is an anaerobic adhesive. In one form, the anaerobic adhesive is a methacrylate 00 adhesive. In one form, the anaerobic adhesive comprises 2 hydroxyethylmacrylate C and methacrylate.

In another form, the sealing arrangement comprises a sleeve disposed in and extending Salong the cavity. In a particular embodiment, the sleeve is made from a plastic or similar material.

In a particular embodiment of the hollow rod according to any form described above, the rod includes a body portion made from an elongate metal section that is folded over so that opposite longitudinal edges of the metal section are brought into contact to form the seam. One such hollow rod of this form is manufactured and supplied by OneSteel Pty Ltd and uses a steel section. Such construction of hollow rod has the advantage that it can be made relatively inexpensively and therefore is ideally suited for applications such as in self-drilling rock bolts where the bolt is for single use. Whilst such constructions of rod has the above advantage, they are prone to leak along the seal which can be substantially ameliorated by the construction of the rod with the sealing arrangement as described above.

According to a further aspect of the invention, there is provided a hollow rod comprising an elongate metal body portion having opposite ends and a longitudinal cavity extending between the ends, and a liner sleeve disposed in and extending along the cavity.

In a further aspect, the invention relates to a drill rod incorporating a hollow metal rod according to any form described above.

In yet a further aspect, the invention relates to a self-drilling rock bolt that comprises first and second ends, a shaft extending between the ends, the first end being adapted to penetrate rock and the second end being adapted to be connected to a drilling apparatus to allow rotation of and thrust to the bolt, the shaft being formed from a hollow metal rod according to any form above wherein the longitudinal cavity forms an inner passage 0 to allow fluid to be passed between the ends.

;In one form, the self-drilling rock bolt includes an anchoring device operative to retain the bolt when located in a drilled hole.

In accordance with this aspect, a self-drilling rock bolt is provided that incorporates an 00 inner passage within the shaft. This passage typically provides part of a circulation Spassage to allow drilling fluid to be introduced, or withdrawn, at the first end of the bolt Sand to enable grout to be pumped into the drilled hole to set the rock bolt in place.

S 10 Typically, the circulation passage further includes a second passage that is formed between the bolt shaft and the wall of the drilled hole.

In a particular form, the anchoring device uses a mechanical system to retain the bolt in a drilled hole. In one form, the anchoring device comprises at least one expansion element that is displaced radially outwardly to retain the bolt in a drilled hole. In one form, the expansion element includes an element that deforms so as to displace radially outwardly. In another form, the expansion element is arranged to move, such as through a pivoting action, so as to be displaced radially outwardly.

In a particular form, the anchoring device further comprises a mandrel that has a inclined external surface and wherein the expansion element has an inner surface that bears against this inclined surface. In a particular form, the mandrel is able to move relative to the expansion element. When that movement is in a predetermined direction, the expansion element is caused to be displaced radially outwardly.

In a particular form, the bolt is rotated in a first direction in a drilling operation and is rotated in a second direction which is opposite to the first direction, to cause the anchoring device to become operative to retain the bolt in a drilled hole.

In one form, the expansion element projects downwardly from the restrained end towards the second end of the rock bolt. In another form, the expansion element projects upwardly towards the first end of the rock bolt. In this latter arrangement, the at least one expansion element may be located in a groove, or bear against a retaining collar disposed on the shaft at a location spaced from the first end.

In one form, where the anchoring device comprises the at least one expansion element and the mandrel, these elements are connected to the bolt shaft so as to enable relative rotation. Furthermore, in at least one form, the inner surface of the expansion element Nand the external inclined surface are shaped so that relative rotation between the ;expansion element and the mandrel is prevented. As such, the expansion element and n the mandrel rotate together about the bolt shaft.

CK1 In a particular form of the above mentioned arrangement, on rotating the shaft in a 0_ second direction relative to the anchoring device, the expansion element is restrained Sfrom axial movement along the bolt shaft, whereas the mandrel is movable axially along the shaft in a direction that causes outward displacement of the expansion elements.

Accordingly, with this configuration, rotation of the shaft relative to the anchoring device induces relative movement between the expansion element and the mandrel to cause activation of the expansion element.

In a particular form, the mandrel is connected to the shaft via a threaded coupling comprising an external thread on the shaft and a complementary inner thread disposed on an inner surface of the mandrel. In this way, the threaded coupling induces axial movement of the mandrel on the shaft under relative rotation between the shaft and the mandrel. In a particular form, movement of the mandrel down the shaft towards the second end) causes the expansion element to be displaced radially outwardly.

In one form, the first end is adapted to penetrate rock by incorporating at least one drill tip that extends radially from the bolt axis, a distance greater than the shaft. In one form, the drill tip is located directly on the shaft of the bolt, which may be modified to accept the drill tip such as through a milling or forging operation.

In an alternative form, the rock bolt further comprises a drill bit which is connected to an end of the shaft and which incorporates the drill tip thereon. In this arrangement, the drill bit is connected to the end of the shaft by a coupling that is arranged to impart rotation to the drill bit from the shaft when the shaft is rotated in at least one direction.

In this regard, the coupling may be permanent i.e. the drill bit may be welded on to the shaft, or alternatively the drill bit may be removable. In this latter arrangement, the coupling may be in the form ofinterfitting projections and recesses that allow rotation to be imparted or alternatively a threaded coupling may be used wherein the drill bit incorporates a shank having an extemrnal thread and a complementary inner thread is disposed on an inner surface of the shaft that defines the inner passage.

In a particular form, the drill bit incorporates a passage that is in fluid communication with the inner passage of the shaft so as to enable fluid to be passed from the passage through to the drill tip. In a particular arrangement, where the sealing arrangement ;incorporates a sealing sleeve, one end of the sleeve is arranged to be sealing engaged with the drill bit.

N1 Typically, the anchoring device is disposed adjacent the first end. In the arrangement 00 described above, where the at least one expansion element is restrained from axial Omovement along the shaft, this expansion element may be seated in a groove or recess Odisposed along the shaft length. In an alternative form, the expansion element may be designed to be captured between the drill bit and the shaft end so as to restrain the expansion element from axial movement.

In a particular form, a plurality of expansion elements are provided which in use are angularly spaced about the shaft axis. In a particular form, a connector is provided which interconnects the expansion elements and which is arranged to engage with the bolt shaft so as to prevent the axial movement of the expansion elements along the shaft. In one form, this connector may be formed in multiple pieces, or able to be deformed, so as to extend about and locate in a recess in the shaft.

In an alternative arrangement to the above, the expansion element is formed as a single piece which incorporates a central aperture which is designed to locate between the drill bit and the shaft end with a shank of the drill bit being arranged to extend within the aperture formed in the connector.

In one form, the internal passage is arranged to be open at the second end of the shaft so as to allow suitable equipment such as pumps or the like to be fitted to that end to introduce or withdraw fluids from bored hole. In a particular form where the sealing arrangement is a sleeve, an end cap is provided that locates at the second end and is fitted to the sleeve.

In a particular form, the rock bolt further comprises a drive coupler disposed adjacent to the second end and which is designed to interengage with the drilling apparatus. The drive coupler is also connected to the shaft so as to allow rotation of and thrust to be imparted to the bolt shaft.

In a particular form, the drive coupler is in the form of a drive nut which is connected to the bolt shaft through a threaded coupling comprising an external thread disposed on the shaft and a complementary inner thread disposed on an inner surface of the drive nut.

;In a particular form, a stop is provided which is operative to inhibit axial movement of 00 the drive nut beyond a predetermined location on the shaft. In a particular form, this stop is in the form of a lock nut which is secured to the shaft and which is coupled to the shaft through a threaded coupling which preferably has a handed thread which is 00 opposite to that used on the drive nut.

OIn one form, a torque means is arranged to restrict axial movement of the drive nut along the shaft until a predetermined torque is supplied to the nut. In a particular form, this torque means is in the form of a torque pin which extends radially through the nut and into the shaft, and wherein the torque pin is operative to shear on the application of a predetermined torque to the nut. In one form, the torque means also acts as the stop for the drive nut.

In operation of a particular embodiment of the self drilling rock bolt, the bolt is secured to a drilling apparatus, via the drive nut, which rotates the rock bolt in the first direction.

Drilling fluid is pumped into the inner passage of the shaft to flush the cutting surface of the rock bolt. On completion of the drilling phase, the drilling apparatus then rotates the bolt in the opposite direction which causes activation of the anchoring device and in particular causes the mandrel to move axially down the bolt shaft causing the expansion element(s) to expand.

In a particular form, the threaded coupling for both the mandrel and the drive nut has the same handed thread. With this arrangement, on rotation in the second direction, the drive nut rotates with the shaft as relative movement is prevented by the torque pin.

Accordingly the shaft rotates in the second direction. This causes the expansion element(s) and mandrel to start to slip relative to the bolt shaft. This relative movement induced between the anchoring device and the shaft causes the mandrel to wind down the thread of the shaft thereby causing the expansion elements to displace radially outwardly to engage the rock surface of the drilled hole.

When the expansion elements are engaged with the wall surface, the bolt becomes firmly held in place. Accordingly if need be the drilling apparatus can be detached and at some later time grout can be injected into the hole to set the bolt in place.

Alternatively the bolt can be placed in tension by continuing to apply torque in the second direction to the drive nut. At a particular point, the expansion elements are -8-

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forced so hard against the rock wall surface that the mandrel cannot move down the shaft any further. This then effectively binds the bolt and inhibits it from rotating any ;further. This builds up the torque at the drive nut until it reaches a point where it will shear the torque pin thereby letting the drive nut to move relative to the shaft. This relative movement then causes the nut to wind up the shaft.

00 Once the drive nut is able to move along the bolt shaft, it will then move into Oengagement with the outer face of the rock strata (either directly or through a bearer Splate) which will then enable the bolt to be placed in tension as the effective length of 10 the bolt between the drive nut and the anchoring device is shortened. This places the rock strata in compression. Once the bolt is under sufficient tension, the drilling Sapparatus can then be removed and the final stage of setting the bolt in place by the introduction of the grout through the inner passage of the bolt can then be performed.

Brief Description of the Drawings Embodiments of the present invention are hereafter described with reference to the accompanying drawings. The particularity of the drawings and the related description is to be understood as not superseding the generality of the preceding broad description of the invention.

In the drawings: Fig. 1 is a schematic perspective view of a hollow rod according to a first aspect of the invention; Fig. 2 is an end view of Fig. 1; Fig. 3 is a detailed view of the seam of the rock bolt of Fig. 1; Fig. 4 is a schematic perspective view of a second embodiment of a hollow rod; Fig. 5 is an end view of the rod of Fig. 4; Fig. 6 is a schematic perspective view of a self-drilling rock bolt; Fig. 7 is a side elevation of the self-drilling rock bolt of Fig. 6; and Fig. 8 is a cross-sectional view of the rock bolt of Fig. 6 installed in a bored hole.

Detailed Description of the Drawings Turning firstly to Figs. 1 to 3 a hollow metal rod 10 is disclosed. The rod 10 is elongated having a body portion 12 which extends between opposite ends (one of which is shown at 11). The body portion 12 is formed by the folding of a metal strip so that opposite longitudinal edges 14 and 15 of the body 12 are joined to produce a ;Zlongitudinal seam 16 which extends between the ends. Further, the folding operation is such that a longitudinal cavity 13 is formed within the body portion 12. Typically the S 5 rod 10 is formed in a continuous manner and is cut into discrete lengths. As part of the manufacturing operation, the outer surface of the rod 10 is profiled to incorporate ridges 0_ 17 which assist in bonding of the rod in a settable matrix such as a cement grout.

A hollow rod formed using this construction has the advantage that it can be manufactured relatively inexpensively relative to other hollow steel rods. However, this construction is such that there is a tendency for the longitudinal seam to leak when the Scavity 13 is used to convey fluid. To ameliorate this problem, the rod 10 incorporates a sealing arrangement in the longitudinal seam 16. In the first embodiment, this sealing arrangement is in the form of an adhesive 18 applied in the seam 16.

In the embodiment of Figs. 1 to 3, the adhesive is an anaerobic adhesive which can be applied in a post forming operation. The advantage of using an anaerobic adhesive is that the adhesive 18 bonds in the absence of air. As such it can be applied liberally to the longitudinal seam to ensure penetration into the seam with the excess adhesive being able to be easily removed after setting of the adhesive in the seam as it will not set in view of its exposure to the ambient air. Whilst the anaerobic adhesive may be applied as part of a post forming operation, it is to be appreciated that the adhesive may also be applied during forming of the bar In one form, the anaerobic adhesive is a methacrylate adhesive. In a particular form, the anaerobic adhesive comprises its 2-hydroxyethylmacrylate and methacrylate. One suitable anaerobic adhesive is supplied under the brand name 3 Bond 1373B by 3 Bond Singapore Pte Ltd. Such an anaerobic setting adhesive sets when not exposed to air and when in contact with metal and therefore is ideally suited to the present application.

Figs. 4 and 5 illustrate a second embodiment of a hollow rod. In this embodiment the rod 20 has the same basic construction as the rod 10. As such like features have been given corresponding reference numbers (commencing with rather than as in the first embodiment) to allow distinction between the two embodiments.

The second embodiment of bolt 20 is distinguished from the first embodiment 10 by the arrangement of the sealing arrangement 28 for the longitudinal seam 26. In the second embodiment, this sealing arrangement is provided by the incorporation of an elongated tube that locates within the cavity 23. Typically the tube is made from a polymer ;material and again may either be incorporated in a post forming step to the bar 20 or as 00 part of the forming operation wherein the body 22 of the rod is rolled around the tube C" 5 28. Typically the tube is sized so as to form an interference fit with the body 22 so that the tube 28 is firmly held in position.

00 SWith the arrangement of the rod 20 fluids can be passed along the cavity within the tube thereby avoiding the need to provide a separate seal along the longitudinal seam 26.

Furthermore, the body portion 22 protects the tube 28 thereby obviating the need for the tube to be made with any particular strength characteristics.

Figs. 6 to 8 illustrate a self drilling rock bolt 100 which uses the rod 20 of the second embodiment described above having the lining sleeve 28 that seals the rod seam 26 to inhibit the passage of water through the seam 26.

The rock bolt 100 incorporates a first (drilling) end 101 and a second (nut) end 102 and the rod 20 forms the rock bolt shaft 103 which extends between the opposite ends 101, 102. The shaft 103 is hollow and incorporates a central passage 104 (see Fig. 8) which allows fluid to be passed from the nut end 102 to the drilling end 101. In use, the self drilling rock bolt 100 is connected to a drilling apparatus (not shown) and acts as a drill rod to drill a hole 200 (see Fig. 8) into rock strata 500. Thereafter, the rock bolt 100 is secured in place as will be explained in more detail below to provide support for the rock strata 500.

The drilling end 101 incorporates a drill bit 105 incorporating a drill tip 106 at a distal end thereof and an anchoring device 123 which in use is arranged to retain the bolt in a drilled hole. The anchoring device 123 may be used to retain the bolt 100 in the drilled hole so as to temporarily secure the rock bolt in place prior to the introduction of grout into the hole 200 to permanently fix the bolt in place and/or to tension the bolt so as to place the rock strata 500 in compression.

The drill bit 105 includes a bit body 107 which includes the drill tip 106 at its outer end and a drill bit shank 108 which incorporates an external thread 122 on its outer surface.

A passage 109 extends from the distal tip of the shank 108 through to the distal end of the bit body 107. This passage 109 is arranged to be in fluid communication with the passage 104 of the shaft when the drill bit 105 is secured to the end 120 of the shaft 103

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r- 11 I (as best seen in Fig. The shaft end 120 includes an inner thread 121 which is complementary to the external thread 122 on the drill bit shank 108. As such, the drill ;Zbit 105 can be simply screwed on to shaft end 120 of the shaft 103. Furthermore a 0 distal end 27 of the sleeve 26 lining the passage 104 projects from the shaft end 120 and 5 is received within the bit passage 109 in a close fitting arrangement to provide an effective seal therebetween.

00 SDuring a drilling operation, the drilling apparatus typically induces right hand rotation to the drill shaft. To ensure that the drill bit 105 does not separate from the shaft during 10 the drilling operation, the threaded coupling between the drill bit 105 and the shaft 103 is a right handed thread so as to tend to cause the threaded coupling between the drill bit Sand shaft to tighten during a drilling operation.

The anchoring device 123 is disposed below the drill bit 105 and in the illustrated form is a mechanical type including a pair of expansion elements 124 which are designed to be caused to move outwardly from a retracted position as illustrated in the drawings to an expanded condition (not shown) wherein the expansion elements 124 engage the wall 201 of the drilled hole 200.

The expansion elements 124 are interconnected by a connector 125. This connector is typically made from spring steel and is welded (or otherwise fixed) to a proximal end 128 of the expansion elements 124. By making the connector 125 from spring steel, it can flex thereby providing a live hinge that allows pivoting of the expansion elements so as to enable it to easily move between its retracted and its extended position.

In use, the connector 125 is captured between the drill bit 105 and shaft end 120 in a manner that allowed the expansion elements to rotate about the shaft axis 120 but prevent them from moving axially along the bolt shaft.

The anchoring device 123 further includes a mandrel 129 which includes opposite inclined surfaces 130 and 131. The inclined surfaces 130 and 131 are designed to abut with inner surfaces 135 of the expansion elements 124 in a manner such that relative movement of the mandrel towards the nut end 112 of the shaft causes the expansion elements to move from their retracted position to their extended position.

To enable this relative movement, the mandrel is coupled to the bolt shaft which in the illustrated arrangement is through a threaded coupling 136 with an internal thread -12formed in an inner side of the mandrel 129 and an external thread formed on the bolt shaft 103.

;Z

The threaded coupling 136 between the mandrel 129 and the bolt shaft 103 is a left 00 5 handed thread so that when the rock bolt is undergoing a drilling operation (under right hand rotation of the shaft), any relative motion between the mandrel and the shaft would 00 cause the mandrel to move towards the drill end thereby ensuring that the expansion elements are not moved to their expanded condition.

S 10 The anchoring device 123 further comprises a pair of outwardly extending tangs 139 Sdisposed at a distal end 140 of the expansion elements 124. As best illustrated in Fig. 6, ,1 the tangs 139 project outwardly from the expansion elements 124. This enables the tangs 139 to engage wall surface of the drilled hole. When the rock bolt 100 is rotated under left hand rotation, the engagement of the tangs 139 enables the anchoring device to begin to slip relative to the shaft thereby inducing some relative movement. This movement, in turn causes the mandrel to start winding down the shaft thereby causing the expansion elements to be displaced outwardly.

Turning to the nut end 102 of the rock bolt 100, a drive coupler 143 is disposed adjacent to the end 102 and arranged to inter-engage with the drilling apparatus and the shaft so as to allow rotation of and thrust to be imparted to the bolt shaft. The drive coupler 143 is in the form of a drive nut which is connected to the bolt shaft 103 through a threaded coupling 144 comprising external thread disposed on the shaft 103 and a complementary inner thread disposed on an inner surface of the drive nut.

The threaded coupling in the illustrated form is a left handed thread so that during a drilling operation, the torque applied to the drive nut tends to cause it to wind off the second end of the shaft 103. To prevent this, a stop assembly 146 is provided which is operative to inhibit axial movement of the drive nut on the shaft. In the illustrated form, this stop is in the form of a torque pin 151 which is arranged to restrict relative movement of the drive nut until a predetermined torque is supplied to the nut. The torque pin 151 extends radially through the nut 143 and into the shaft 103 (as best illustrated in Fig. and is operative to shear on the application of a predetermined torque to the nut.

The second end 102 is open to the passage 104 and an end collar 152 is fitted to the end 102 and engages with a lower end 28 of the sleeve lining 26. The drive coupler 143 is -13-

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0 disposed inwardly of second end 102 to allow a short stub 153 to project from the nut to the end. This stub is arranged to be connected to pumping apparatus (not shown) to ;allow fluid to be introduced into the open second end 102.

00 Finally, a bearer plate 154 and ball washer 155 may be disposed on the shaft 103 and captured by the drive nut 143. The bearer plate 154 is arranged to bear against the outer 00 face 501 of the rock strata 500.

OIn operation, the bolt 100 is secured to a drilling apparatus, via the drive nut 143, which rotates the rock bolt in the first direction. Drilling fluid is pumped into the inner passage 104 of the shaft to flush the cutting surface of the rock bolt.

On completion of the drilling phase, the drilling apparatus then rotates the bolt in the opposite direction. The drive nut 143 rotates with the shaft 103 as relative movement is prevented by the torque pin. The tangsl39 grip the wall surface 201 causing the expansion elements 124 and mandrel 129 to start to slip relative to the bolt shaft. This relative movement induced between the anchoring device and the shaft causes the mandrel to wind down the thread of the shaft thereby causing the expansion elements to displace radially outwardly to engage the rock surface of the drilled hole.

When the expansion elements are engaged with the wall surface, the bolt becomes firmly held in place. Accordingly if need be, the drilling apparatus can be detached and at some later time grout can be injected into the hole to set the bolt in place.

Alternatively the bolt can be placed in tension by continuing to apply torque in the second direction to the drive nut 143. At a particular point, the expansion elements 124 are forced so hard against the rock wall surface that the mandrel cannot move down the shaft any further. This then effectively binds the bolt and inhibits it from rotating any further. This builds up the torque at the drive nut 143 until it reaches a point where it will shear the torque pin 151 thereby letting the drive nut to move relative to the shaft.

This relative movement then causes the nut to wind up the shaft.

Once the drive nut is able to move along the bolt shaft, it will then move the bearer plate 154 into engagement the outer face 202 of the rock strata 500 which will then enable the bolt to be placed in tension as the effective length of the bolt between the drive nut and the anchoring device is shortened. This places the rock strata in compression. Once the bolt is under sufficient tension, the drilling apparatus can then be removed and the final stage of setting the bolt in place by the introduction of the grout -14through the inner passage of the bolt can then be performed.

(N

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, N 5 the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the 00 -presence or addition of further features in various embodiments of the invention.

SVariations and/or modifications may be made to the parts previously described without (N departing from the spirit or ambit of the invention.

Claims

2. A hollow rod according to claim 1, wherein the sealing arrangement is in the Sform ofa settable material disposed in the seam.
3. A hollow rod according to claims 1 or 2, wherein the settable material is polymeric.
4. A hollow rod according to claims 2 or 3, wherein the settable material is an anaerobic adhesive. A hollow rod according to any one of claims 2 to 4, wherein the anaerobic adhesive is a methacrylate adhesive.
6. A hollow rod according to claim 5 wherein the methacrylate adhesive comprises 2-hydroxyethylmacrylate and methacrylate.
7. A hollow rod according to claim 1, wherein the sealing arrangement comprises a liner sleeve disposed in and extending along the cavity.
8. A hollow rod according to claim 7, wherein the sleeve is polymeric.
9. A hollow rod according to any preceding claim, wherein the rod comprises a body portion formed from an elongate metal section having opposite longitudinal edges that are brought into contact to form the seam. A hollow rod comprising an elongate metal body portion having opposite ends and a longitudinal cavity extending between the ends, and a liner sleeve disposed in and extending along the cavity.
11. A hollow rod according to claim 9 or 10, wherein the body portion is formed of steel. -16-
12. A drill rod comprising first and second ends, a shaft extending between the ends, the first end being adapted to penetrate rock and the second end being adapted to ;be connected to a drilling apparatus to allow rotation of, and thrust to the rod, the shaft 00 being formed from a hollow rod according to any one of claims 9 to 11 wherein the longitudinal cavity forms an inner passage to allow fluid to be passed between the ends. 00
13. A self drilling rock bolt comprising first and second ends, a shaft extending Cc between the ends, the first end being adapted to penetrate rock and the second end being I adapted to be connected to a drilling apparatus to allow rotation of, and thrust to, the bolt, the shaft being formed from a hollow metal rod according to any one of claims 9 to S 10 11 wherein the longitudinal cavity forms an inner passage to allow fluid to be passed between the ends.
14. A self drilling rock bolt according to claim 13, further comprising an anchoring device operative to retain the bolt when located in a drilled hole. A self drilling rock bolt according to claim 14, wherein the anchoring device uses a mechanical system to retain the bolt in a drilled hole.
16. A self drilling rock bolt according to claim 15, wherein the anchoring device comprises at least one expansion element that is displaced radially outwardly to retain the bolt in a drilled hole.
17. A self drilling rock bolt according to claim 16, wherein the anchoring device further comprises a mandrel having one or more external surface inclined to the shaft and wherein the expansion element is displaced radially outwardly on a predetermined relative movement of the inclined surface of the mandrel across an inner surface of the at least one expansion element.
18. A self drilling rock bolt according to claim 17, wherein the predetermined relative movement is axially along the shaft towards the second end.
19. A self drilling rock bolt according to claim 18, wherein the at least one expansion element and the mandrel are restrained from relative rotation about the shaft axis by engagement of the inclined surface of the mandrel with the inner surface of the at least one expansion element. -17- A self drilling rock bolt according to claim 18 or 19, wherein the at least one expansion element is restrained from axial movement along the bolt shaft. c' 21. A self drilling rock bolt according to claim 20, wherein the mandrel is 00 C connected to the shaft via a threaded coupling comprising an external thread on the shaft and a complementary inner thread disposed on an inner surface of the mandrel. 00
22. A self drilling rock bolt according to any one of claims 14 to 21, wherein the bolt is rotated in a first direction in a drilling operation and is rotated in a second direction which is opposite to the first direction to cause the anchoring device to Sbecome operative to retain the bolt in a drilled hole.
23. A self drilling rock bolt according to any one of claims 13 to 21, wherein the first end incorporates at least one drill tip that has an outer edge that extends radially a distance greater than the radius of the shaft.
24. A self drilling rock bolt according to claim 23, further comprising a drill bit which is connected to an end of the shaft and incorporates the at least one drill tip thereon, the drill bit being connected to the end of the shaft by a coupling that is arranged to impart rotation to the drill bit from the shaft when the shaft is rotated in at least one direction. A self drilling rock bolt according to claim 24, wherein the drill bit incorporates a passage that is in fluid communication with the inner passage of the shaft so as to enable fluid to be passed between the passage and the drill tip.
26. A self drilling rock bolt according to claim 25, wherein the sealing arrangement incorporates the liner sleeve and one end of the sleeve is arranged to be sealing engaged with the drill bit.
27. A self drilling rock bolt according to any one of claims 24 to 26, wherein the coupling between the drill bit and the shaft comprises a threaded coupling having an external thread on a shank of the drill bit and a complementary inner thread disposed on an inner surface of the shaft that defines said inner passage.
28. A self drilling rock bolt according to any one of claims 24 to 27, wherein the at -18- least one expansion element is captured between the drill bit and the shaft end.
29. A self drilling rock bolt according to claim 28, wherein the anchoring device -n further comprises a connector and the at least one expansion shell depends from the 00 N connector, and wherein the connector is captured between the drill bit and the shaft. 00 5 30. A self drilling rock bolt according to claim 29, wherein a hinge is formed between the connector the at least one expansion element and wherein the at least one expansion element is arranged to be displaced radially outwardly by pivoting about the hinge.
31. A self drilling rock bolt according to any one of claims 13 to 30, further comprising a drive coupler disposed adjacent the second end, and connected to the shaft so as to allow rotation and thrust to be imparted to the bolt shaft.
32. A self drilling rock bolt according to claim 31, wherein the drive coupler is in the form of a drive nut which is connected to the bolt shaft through a threaded coupling comprising an external thread disposed on the shaft and a complementary inner thread disposed on an inner surface of the drive nut.
33. A self drilling rock bolt according claims 31 or 32, further comprising a stop secured to the shaft and operative to inhibit axial movement of the drive nut.
34. A self drilling rock bolt according to claim 33, wherein the stop comprises torque means operative to restrict axial movement of the drive nut along the shaft until a predetermined torque is applied to the nut. A self drilling rock bolt according to claim 34, wherein the torque means is in the form of a torque pin which extends radially through the nut and into the shaft, the torque pin being operative to shear on the application of a predetermined torque to the nut. -19- o 36. A self drilling rock bolt according to claim 35, when dependent on claim 21, wherein the threaded couplings of the mandrel and the drive nut to the shaft have the Ssame handing. 00 00