AU2011254017A1

AU2011254017A1 - Rock bolt

Info

Publication number: AU2011254017A1
Application number: AU2011254017A
Authority: AU
Inventors: Frank Schmidt
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2010-12-15
Filing date: 2011-12-14
Publication date: 2012-07-05
Also published as: CA2760164A1; EP2466066A2; ZA201109216B; US20120155971A1; DE102010063098A1

Abstract

Abstract In a rock bolt (1), particularly for use in mining, comprising an anchor tube (3), which encloses an interior space (4), a fixing means (5) arranged inside the interior space (4) for the substance to-substance fixation of the anchor tube (3) to the stone (28), a mobile piston (11) arranged inside the interior space (4) for transporting the fixing means (5) out of the anchor tube (3) in an arrangement of the anchor tube (3) in a bore hole (29) in the stone (28), at least one means (12) for moving the piston (11), an anchor nut (14), an anchor plate (15) supported by the anchor nut (14) for the support on the stone (28), the fixing means (5) shall be able to be moved with little technical expense into the space (29) between the stone (28) and the anchor tube (3) and/or the rock bolt (1) as gliding anchor (2) requires only little operating space in an underground tunnel and/or operating gallery. This objective is attained such that at least one means (12) is provided to move the piston (11) in the form of a spindle drive (13) and/or the anchor nut (14) and the anchor plate (15) are fastened at a rod (16) arranged inside the anchor tube (3), the rod (16) is fastened with a fastening direction (19) at the anchor tube (3) such that the fastening of the rod (16) at the anchor tube (3) is only loosened beginning at a predetermined tensile force in the rod (16) and thus the rod (16) is partially mobile towards the outside such that the rock bolt (1) represents a gliding anchor (2). (Fig. 1) 28 0 26,27 16,17 0 28 019,20,21 18 16,17 3 1,2 Is //A1 Fig.1I

Description

- 1 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant: Hilti Aktiengesellschaft Actual Inventor: Frank Schmidt Address for Service is: SHELSTON IP 60 Margaret Street Telephone No: (02) 9777 1111 SYDNEY NSW 2000 Facsimile No. (02) 9241 4666 CCN: 3710000352 Attorney Code: SW Invention Title: Rock bolt The following statement is a full description of this invention, including the best method of performing it known to me/us: File: 72942AUP00 -2 Rock bolt Description [0001] The present invention relates to a rock bolt according to the preamble of claim 1 and a method for fixing a rock bolt in stone according to the preamble of claim 12. [0002] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. [0003] In mining and tunnel construction rock bolts are used in order to prevent any rock movements of adjacent stone, to slow them, or to secure larger split-offs of adjacent rock and thus allow a risk-free operation. Here, two functional principles are known, which sometimes are combined. In mechanical systems the fastening of the anchor occurs by friction fitting, with mechanical stone and/or rock anchors generally also showing an expanding sleeve. In chemical rock bolts the anchor tubes are connected to a curing cement or resin as a fixation means in a substance-to-substance manner to the base and/or the adjacent stone. The rock bolts are installed here with or without any prestressing in the adjacent stone. Contrary to tunnel construction rock bolts in mining, e.g., underground coal mining, serve only for a temporary securing of the stone, because generally the temporarily secured stone will be mined in a later processing step and thus the rock bolts are removed again from the stone. [0004] US 4 601 614 shows a rock bolt for tunnel construction and mining. A two-component fixing means in two cartridges is arranged inside an interior space enclosed by an anchor tube. The extemal end of the anchor tube comprises an opening to introduce water under high pressure into the interior space enclosed by the anchor tube. A piston is arranged articulate inside the interior space and by moving the piston the two-component fixing means is transported and/or pressed through holes in the anchor tube into a space between the anchor tube and the stone. For this purpose, an opening is provided at the external end of the anchor tube, through which water can be introduced under high pressure into the interior space enclosed by the anchor tube and by this water the piston is pressurized, so that the piston is moved inwardly and thus the fixation means is expressed. Disadvantageously it is therefore necessary for a substance-to-substance fastening of the anchor tube with the fixing means that -3 in tunnel construction or mining, a high pressure pump is required to create highly pressurized water to move the piston. [0005] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. [0006] The objective of at least a preferred embodiment of the present invention comprises providing a rock bolt and a method for fixing a rock bolt in stone, in which with little technical expense the fixing means can be inserted into the space between the stone and the anchor tube and/or the rock bolt embodied as a gliding anchor requires only little space in the tunnel and/or work gallery produced underground. [0007] According to the invention there is provided a rock bolt, particularly for application in mining, comprising - an anchor tube, which encloses an interior space, - a fixing means arranged inside the interior space for a substance-to-substance fixation of the anchor tube to the stone, - a mobile piston arranged inside the interior space for the transportation of the fixing means out of the anchor tube with an arrangement of the anchor tube in a bore hole in the stone, - at least one means for moving the piston, - an anchor nut, - an anchor plate supported by the anchor nut for supporting on the stone, wherein at least one means as a spindle drive is provided for moving the piston, and/or the anchor nut and the anchor plate are fastened at a rod arranged inside the anchor tube, the rod being fastened via a fastening device at an anchor tube such that the fastening of the rod at the anchor rod is only released beginning at a predetermined tensile force in the rod and thus the rod can be partially moved outwardly so that the rock bolt represents a gliding anchor. [0008] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

-4 [0009] The anchor nut and the anchor plate can be embodied as a single piece or as two separate components. [0010] In order to move the piston, i.e. to express the fixing means out of the interior space into a space between the anchor tube and the stone, it is therefore no longer required to expensively provide a high-pressure pump in the tunnel or gallery in order to move the piston with high-pressurized water. The rock bolt comprises a spindle drive so that the piston can be moved by a mere application of a torque at the rock bolt, particularly at the outside. [0011] The rock bolt is further embodied as a gliding anchor. The gliding anchor shows a gliding function such that beginning at a predetermined tensile force compensated by the rock bolt, i.e. at the pressure acting upon the anchor plate which is caused by the stone, the rock bolt is extended in its length and thus a motion is permitted at the stone which reduces the tensile forces compensated at the rod (below the predetermined tensile force as a threshold, so that no more gliding occurs) and thus a better securing of the stone is ensured. Here, after the expression of the fixing means from the interior space the rod is essentially arranged underneath the interior space, i.e. the rod projects only slightly beyond the exterior end of the anchor tube, so that the gliding anchor requires only little structural space outside the stone. In the gliding anchors known from prior art the gliding function at the anchor nut is implemented such that the anchor nut glides outwardly at a larger projection of the rod and/or the anchor tube. Thus, in the gliding anchors known from prior art a large amount of space is required prior to the gliding of the gliding anchor for the projection at the anchor tube and/or the rod for the nut. [0012] If the tensile force to be compensated by the rod and/or the force at the rock bolt according to the invention to be compensated by the rod at the fastening device falls below a predetermined tensile force the motion of the rod towards the outside is hindered again, relative to the anchor tube with the fastening device, so that greater forces can be compensated by the rock bolt. [0013] In an additional embodiment the rod represents a threaded rod with an external thread and the fastening device is an annular part with an internal thread, e.g., a nut, and the annular part is fastened at the anchor tube and the internal thread of the annular part engages the external thread of the threaded rod.

-5 (0014] In an amended embodiment the annular part is embodied in one piece at the anchor tube, particularly by an internal thread being embodied inside the anchor tube. The annular part can here represent a separate part fastened to the anchor tube or an annular part with an internal thread can be embodied in one piece with the anchor tube, for example such that an internal thread is provided at the external end section inside the anchor tube. [0015] In another variant the internal thread of the annular part is embodied as a specialty thread, which destroys the external thread of the threaded rod only beginning at a predetermined tensile force or vice versa. [0016] Beneficially the spindle drive to move the piston is formed from the threaded rod and the annular part with the internal thread. [0017] In an amended embodiment the piston is fastened directly or indirectly at the threaded rod. [0018] In an additional embodiment the rear end of the anchor tube is closed by a cap and the anchor tube and/or the cap comprise at least one opening to guide the fixing means out of the interior space enclosed by the anchor tube. On the one hand, the cap can be a separate part or also be embodied in one piece together with the anchor tube. [0019] In a supplementary embodiment the fixing means, particularly resin or cement, comprises two components, e.g., an adhesive component and a curing component. [0020] Preferably the two components are each arranged separated in a bag. Here, any device for storing the two separate components is considered a bag, for example a cartridge or any other container. (0021] In an amended embodiment a mixer is arranged between the fixing means and at least one opening to mix the fixing means, particularly the two components, before the fixing means is ejected through at least one opening. [0022] Beneficially the rod is provided with a stop, preferably an annular stop, so that the mobility of the rod towards the outside is limited by said stop. Here, the stop may be a separate -6 component or be embodied in one piece with the rod, particularly a threaded rod. Furthermore, the stop may also be formed by the piston. [0023] The method according to the invention for fixing a rock bolt in stone, particularly a rock bolt as described in this application, having the steps implementing a bore hole in the stone, inserting the rock bolt into the bore hole, transporting a fixing means from the interior space enclosed by an anchor tube through at least one hole into a space, particularly an annular space between the anchor tube and the stone by way of moving a piston in the interior space towards the fixing means, a substance-to-substance fastening of the anchor tube by the fixing means to the stone, curing the fixing means, with the piston being moved by a spindle drive at a rock bolt, particularly inside an interior chamber enclosed by the anchor tube. [0024] In an additional embodiment the spindle drive comprises a threaded rod, a torque is applied from the outside to the threaded rod such that the threaded rod is set into a rotary motion about the longitudinal axis of the threaded rod, and the threaded rod is screwed with an external thread to an internal thread at the anchor tube such that the threaded rod performs an axial motion towards the inside, i.e. the threaded rod is screwed into the interior space enclosed by the anchor tube. [0025] In an amended variant the piston fastened at the threaded rod performs the inwardly directed axial motion together with the threaded rod. [0026] In an additional variant, prior to the threaded rod being screwed into the interior space enclosed by the anchor tube the threaded rod is only partially arranged in the interior space enclosed by the anchor tube and during the expression of the fixing means from the interior space enclosed by the anchor tube the threaded rod is essentially entirely screwed into the interior space enclosed by the anchor tube. Here, "essentially entirely screwed into the interior space enclosed by the anchor tube" means that the threaded rod is screwed into the interior space by at least 70%, 80%, 90% or 95%. This way, only a small part of the threaded rod, i.e. for example less than 30%, 20%, 10%, or 5% is arranged outside the interior space so that after the screwing in and the compression of the space between the anchor tube and the stone with the fixing means the rock bolt requires only little operating space in the tunnel or gallery.

-7 [0027] In an amended embodiment the components of the rock bolt, for example the anchor tube, the piston, the spindle drive, the anchor nut, the anchor plate, the rod, the fastening device, the annular part, the cap, and/or the stop are made at least partially, preferably entirely, from metal, for example steel or a steel alloy, or fiberglass-reinforced plastic. [0028] In the following an exemplary embodiment of the invention is described in greater detail with reference to the attached drawings. Shown are: [0029] Fig. 1 a longitudinal cross section of a rock bolt, which is inserted into a bore hole in stone and the fixing means is not yet inserted into the space between the stone and the anchor tube, and [0030] Fig. 2 a longitudinal cross section of the rock bolt according to Fig. 1, in which the fixing means is inserted into the space between the stone and the anchor tube. [0031] A rock bolt 1 embodied as a gliding anchor 2 is used in mining for the temporary securing of stone in galleries. The rock bolt 1 comprises an anchor tube 3, which encloses an interior space 4. The rock bolt 1 represents a chemical rock bolt 1, i.e. using a fixing means 5 arranged in the interior space 4 to the anchor tube 3 to be fastened in a substance-to-substance fashion to the stone 28. For this purpose, a bore hole 29 must be implemented in the stone 28 and then the rock bolt 1 must be inserted into the bore hole 29. This status is shown in Fig. 1, prior to the expression of the fixing means 5 into a space between the anchor tube 3 and the stone 28. Fig. 2 shows the rock bolt 1 connected to the stone 28 in a substance-to-substance manner. The fixing means 5 represents a resin 6 here, which shows an adhesive component 7 and a curing component 8. The adhering component 7 is stored in a first bag 9 and the curing component 8 is stored in a second bag 10. The two bags 9, 10 are stored in the interior space 9. [0032] Prior to the expression of the fixing means from the interior space 4 a rod 16 embodied as a threaded rod 17 is arranged with an external thread 18 only up to approximately half in the interior space 4 and the other half is outside the interior space 4, i.e. in an operating space 30 of a hollow space or gallery for mining. A fastening device 19 is fixed inside at the anchor tube 3 in the exterior end section as an annular part 20 at the anchor tube 3. The annular part 20, for example a nut 21 with an internal thread 22, is here for example welded to the anchor tube 3. Here the external thread 18 of the threaded rod 17 engages the internal -8 thread 22 of the annular part 20 so that this way the threaded rod 17 is indirectly fastened to the anchor tube 3. A piston 11 is fastened at the interior end of the threaded rod 17. The interior end of the anchor tube 3 is closed by a cap 23 with an opening 24. Through the opening 24 the fixing means 5 can flow from the interior space 4 of the anchor tube 3 towards the outside into the space, particularly annular space, between the anchor tube 3 and the stone 28. Here, a mixer 25 is arranged at the opening 24, through which due to the geometric arrangement of the mixer 25 in the interior space 4, the fixing means 5 must mandatorily flow from the two bags 9, 10 first through the mixer 25 and then through the opening 24 to the outside. Here, the mixer 25 comprises devices, for example an appropriate geometry, such that the fixing means 5 flows meandering or tube-like through the mixer 25 and thus a mixing of the adhesive component 7 with the curing component 8 of the resin 6 occurs prior to flowing out of the opening 24. [0033] At the exterior outer end of the threaded bolt 17 an anchor nut 14 is screwed onto the external thread 18 of the threaded rod 17 with an internal thread and an anchor plate 15 is placed on the anchor nut 14. Here, the anchor nut 15 comprises a bore hole without an internal thread, with the threaded rod 17 being arranged therein. Thus, according to the illustration in Fig. 2 a pressure can be applied by the stone 28 upon the anchor plate 15. This pressure is transferred from the anchor plate 15 to the anchor nut 14 and from the anchor nut 14 to the threaded rod 17 so that a tensile force is applied to the threaded rod 17. This tensile force is transferred via the annular part 20 to the anchor tube 3 and from the anchor tube 3 at the outside in a substance-to-substance manner by the fixing means 5 to the stone 28. [0034] The piston 11 is moved inwardly in order to insert the fixing means 5 into the space between the anchor tube 3 and the stone 28, i.e. according to the illustration of Fig. 1 upwardly. This way, the piston 11 destroys the first and second bag 9, 10 so that the adhesive component 7 and the curing component 8 move and due to the reducing volume of the internal space 4 between the piston 11 and the cap 23 the fixing means 5 is pressed through the mixer 25 and the opening 24 into the space between the anchor tube 4 and the stone 28 and subsequently cures. For this purpose, the rock bolt 1 comprises a spindle drive 13 as a means 12 for moving the piston 11. Here, the threaded rod 17 and the annular part 20 with the internal thread 22 serve as the spindle drive 13. The external end of the threaded rod 17 shows a respective geometry, for example the shape of a hexagon in the cross section, so that here a torque can be applied upon the threaded rod 17, for example via a pneumatic screw, and thus the threaded rod 17 is set into a rotary motion about its longitudinal axis. This way, the threaded rod 17 is moved inwardly, i.e. according to the illustration in Fig. 1 towards the top, due to the engagement of the external thread 18 of the threaded rod 17 with the internal thread 22 of the annular part 20. [0035] With the motion of the threaded rod 17 the piston 11 also performs the motion according to the illustration of Fig. 1 upwards, because the piston 11 is fastened to the threaded rod 17. In Fig. 2 the fixing means 5 is already completely pressed into the space between the anchor tube 3 and the stone 28, i.e. the anchor tube 3 is fastened to the stone 28 in a substance-to-substance fashion, particularly by way of gluing. Here, in the installed state shown in Fig. 2 the threaded rod 17 is essentially completely arranged inside the interior space 4, thus only a small portion of the threaded rod 17, for example less than 10% or 5% is located outside the interior space 4. This way, in the installed state of the rock bolt 1 only very little operating space is required in the operating area 30 in the mining gallery. In the installed state according to Fig. 2 the anchor plate 15 contacts the stone 28 and thus can compensate pressures. Further, shear forces perpendicular in reference to a longitudinal axis of the threaded rod 17 and/or the anchor tube 3 can also be compensated by the rock bolt 1 and thus the stone 28 can additionally be secured. [0036] The rock bolt 1 is embodied as a gliding anchor 2. For this purpose, the intemal thread 22 of the annular part 20 is embodied as a specialty thread, which beginning at a predetermined tensile force in the threaded rod 17 destroys the extemal thread 18 of the threaded rod 17, for example by way of shearing so that this way the threaded rod 17 is moved outwardly, i.e. according to the illustration in Fig. 2 downwards in reference to the anchor tube 3. Here, the anchor nut 14 as well as the anchor plate 15 move together with the threaded rod 17 outwardly. This way, movements of the stone 28 can be compensated by the rock bolt 1 being a gliding anchor 2 without this leading to the rock bolt 1 breaking. When the tensile force and/or the pressure to be compensated by the threaded rod 17 upon the anchor plate 15 falls back below the predetermined threshold for the tensile force the external thread 18 of the threaded rod 17 is no longer destroyed by the specialty thread of the internal thread 22 of the annular part 20 and the threaded rod 17 no longer moves towards the outside. [0037] A stop 26 embodied as an annular stop 27 in the upper end section of the threaded rod 17 prevents that during gliding, i.e. during a motion of the threaded rod 17 towards the outside, said rod cannot completely move out and by the annular stop 27 contacting the annular -10 stop 20 a gliding of the gliding anchor 2 and/or a motion of the threaded rod 17 towards the outside is prevented. After the annular stop 27 has contacted the annular part 20 this way the gliding anchor 2 is no longer able to glide and compensates the tensile forces at the threaded rod 17 until the tensile forces applied cause the rock bolt 18 to fail, for example the threaded bolt 17 breaking or the adhesive bonding failing between the fixing means 5 and the stone 28. [0038] Overall, the rock bolt 1 according to the invention provides essential advantages. In order to move the piston 11, i.e. the expression of the fixing means 5 from the interior space 4, provision of expensive high-pressure pumps is no longer required in mining operations. The piston 11 can be moved by only applying a torque upon the threaded rod 17 at the outside, for example via a pneumatic screw. In the installed state according to Fig. 2 the rock bolt 1 only requires little operating space 30, because the threaded rod 17 is arranged only slightly outside the anchor tube 3 to accept the anchor nut 4 and the anchor plate 15, and shows no greater length outside the interior space 4 in the installed state according to Fig. 2 to compensate gliding motions of the anchor nut 14 on the threaded rod 17.

Claims

1. A rock bolt, particularly for application in mining, comprising - an anchor tube, which encloses an interior space, - a fixing means arranged inside the interior space for a substance-to-substance fixation of the anchor tube to the stone, - a mobile piston arranged inside the interior space for the transportation of the fixing means out of the anchor tube with an arrangement of the anchor tube in a bore hole in the stone, - at least one means for moving the piston, - an anchor nut, - an anchor plate supported by the anchor nut for supporting on the stone, wherein at least one means as a spindle drive is provided for moving the piston, and/or the anchor nut and the anchor plate are fastened at a rod arranged inside the anchor tube, the rod being fastened via a fastening device at an anchor tube such that the fastening of the rod at the anchor rod is only released beginning at a predetermined tensile force in the rod and thus the rod can be partially moved outwardly so that the rock bolt represents a gliding anchor.

2. A rock bolt according to claim 1, wherein the rod is a threaded rod with an external thread and the fastening device is an annular part with an internal thread, e.g., a nut and the annular part is fastened at the anchor tube and the internal thread of the annular part engages the external thread of the threaded rod.

3. A rock bolt according to claim 2, wherein the annular part is embodied at the anchor tube, particularly by the internal thread being embodied at the inside of the anchor tube.

4. A rock bolt according to claim 2 or 3, wherein the internal thread of the annular part is embodied as a specialty thread, which only destroys the external thread of the threaded rod beginning at a predetermined tensile force.

5. A rock bolt according to one or more of the previous claims, wherein the spindle drive for moving the piston is formed by the threaded rod and the annular part with the internal thread.

6. A rock bolt according to claim 5, wherein the piston is fastened directly or indirectly at the threaded rod. -12

7. A rock bolt according to one or more of the previous claims, wherein a rear end of the anchor tube is closed by a cap and the anchor tube and/or the cap comprises at least one opening to guide the fixing means from the interior space enclosed by the anchor tube.

8. A rock bolt according to one or more of the previous claims, wherein the fixing means, particularly the resin or cement, comprises two components, e.g., an adhesive component and a curing component.

9. A rock bolt according to claim 8, wherein the two components are each arranged separated in a bag.

10. A rock bolt according to one or more of the previous claims, wherein a mixer is arranged between the fixing means and at least one opening to mix the fixing means, particularly the two components prior to the emission of the fixing means from at least one opening.

11. A rock bolt according to one or more of the previous claims, wherein the rod comprises a stop, preferably an annular stop, so that the ability of the rod to move outwardly is limited by said stop.

12. A method for fixing a rock bolt, particularly a rock anchor according to one or more of the previous claims, in stone comprising the steps, - implementing a bore hole in the stone, - inserting the rock bolt into the bore, - transporting a fixing means from an interior space enclosed by an anchor tube through at least one opening into a space, particularly an annular space between the anchor tube and the stone by moving a piston in the interior space towards the fixing means, - substance-to-substance fastening of the anchor tube with the fixing means at the stone, - curing the fixing means, wherein the piston is moved in a spindle drive at the rock bolt, particularly inside an interior space enclosed by the anchor tube. -13

13. A method according to claim 12, wherein the spindle drive comprises a threaded rod, with a torque being applied upon the threaded rod from the outside such that the threaded rod is set into a rotary motion about a longitudinal axis of the threaded rod and the threaded rod is screwed with an extemal thread to the internal thread at the anchor tube so that by the threaded rod an axial motion is performed inwardly, i.e. the threaded rod is screwed into the interior space enclosed by the anchor tube.

14. A method according to claim 13, wherein the piston fastened at the threaded rod performs an axial motion directed inwardly together with the threaded rod.

15. A method according to claim 13 or 14, wherein prior to screwing the threaded rod into the anchor tube enclosed in the interior space the threaded rod is only partially arranged in the interior space enclosed by the anchor tube and during the expression of the fixing means out of the interior space enclosed by the anchor tube the threaded rod is essentially screwed entirely into the interior space enclosed by the anchor space.

16. A rock bolt substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.

17. A method for fixing a rock substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.