AU2010250921A1

AU2010250921A1 - Rock bolt with separate mixing-and discharge head

Info

Publication number: AU2010250921A1
Application number: AU2010250921A
Authority: AU
Inventors: Hans-Georg Beyer; Markus Swoboda
Original assignee: Minova International Ltd
Current assignee: Minova International Ltd
Priority date: 2009-05-20
Filing date: 2010-05-20
Publication date: 2011-12-22
Anticipated expiration: 2030-05-20
Also published as: AU2010250921B2; CL2011002921A1; DE102010004926A1; WO2010133883A2; EP2432970A2; CN102482942B; CN102482942A; WO2010133883A3

Abstract

Rock bolts (1) exist in various forms, wherein it is particularly advantageous if the discharge end (4) is provided with a mixing head (15), into which the required exit hole (8) is integrated. This exit hole (8) is protected by the shape of the head (16) of the mixing head (15) in such a way that a reliable discharge of the anchoring mixture is always guaranteed even if there are drillings still situated in the borehole. Furthermore, the anchoring cartridge (7) upon the application of pressure is reliably torn open so that the two components pass into the region of the static mixer (9) and are then discharged in the mixed state so that the cavity (12) around the bolt tube (2) is reliably filled.

Description

WO 2010/133883 PCT/GB2010/050823 1 ROCK BOLT WITH SEPARATE MIXING- AND DISCHARGE HEAD The invention relates to a rock bolt in the form of an anchoring bolt, with the externally profiled bolt tube of which there is associated an anchoring 5 compound charge, which is accommodated for example in an anchoring cartridge and is ejectable from the bolt tube through a static mixer by means of an ejection plunger, wherein the discharge end of the bolt tube that is to be disposed in the end of the borehole has one or more exit holes. 10 Rock bolts are known in various forms and are used above all to stabilize the rock in the area surrounding galleries and roads as well as tunnels. In the case of a rock bolt known from DE 100 17 750 Al and WO 03/044324 Al, in a first working step a drilling tube is used to drill a 15 borehole in the rock before then, after reaching the final length, being exchanged for a bolt tube having a continuous internal opening. Into this internal opening of the bolt tube an anchoring cartridge is inserted and, in front of this, a static mixer, so that by suitably loading the anchoring cartridge the anchoring compound charge contained therein is pressed 20 through the static mixer into the borehole. Whereas in DE 100 17 750 Al the borehole and the bolt tube are identical and so, at the tip of the bolt tube, a bit closes the internal opening, in WO 03/044324 Al a bolt tube that is approximately open at the front is used. In principle, therefore, in WO 03/044324 Al the anchoring compound charge pressed through the 25 static mixer may simply penetrate into the borehole and above all into the gap between borehole wall and bolt tube and hence result in an anchoring joint. What makes a trouble-free exit difficult or even impossible is the fact that the bolt tube in the end of the borehole rests against the rock, with the result that the internal opening of the bolt tube is completely or 30 at least substantially closed. It is then difficult or totally impossible to press the anchoring compound charge into the intended cavity. In the WO 2010/133883 PCT/GB2010/050823 2 solution known from DE 100 17 750 Al and/or B4, the so-called through bores are admittedly provided laterally, but they too may easily become clogged with any bore dust still present in the borehole, wherein as a further drawback here the so-called static mixer is to be mentioned, 5 because it has inadequate parts for tearing open the anchoring cartridge, has only a narrow cross section of passage and operates with a hardener that is not simultaneously accommodated in the anchoring compound cartridge, with the result that a mixing of both components is unsatisfactory or not possible at all. Furthermore, special auxiliary 10 measures are needed to ensure that the static mixer and/or the so-called sealing piston is not displaced to such an extent that the through-bores are closed. The underlying object of the invention is therefore to provide a rock bolt 15 serving as an anchoring bolt, which is economical to manufacture and given the use of which the anchoring compound charge, practically independently of its nature, is always pressed uniformly and reliably into the cavity around the bolt tube. 20 The object is achieved according to the invention in that the bolt tube at the discharge end is entirely or partially covered by a mixing head with clearance, so that the exit hole or the exit holes are protected against clogging, and that the mixing head at the opposite end, which receives the static mixer and the anchoring cartridge, is designed so as reliably to 25 open the anchoring cartridge upon the application of pressure. A rock bolt of such a design, which is introduced into the pre-drilled borehole, has a bolt tube with a correspondingly large inside diameter, wherein the bolt tube is protected by a mounted mixing head against 30 closure and/or against any drillings still present in the end of the borehole. The anchoring compound charge, which is released during WO 2010/133883 PCT/GB2010/050823 3 expression of the anchoring cartridge, may therefore be pressed fully protected into the end of the borehole and in particular into the cavity around the bolt tube in order thereby to achieve a complete anchoring bonding of the bolt tube to the borehole wall and hence ensure the desired 5 stabilization of the rock. Neither the inserted static mixer, which is supported at the end by the mixing head, nor sludge or drillings located in the end of the borehole can lead to non-uniform or even incomplete pointing because the exit hole or exit holes are protected by the mixing head in such a way that the desired uniform discharge of the anchoring 10 compound charge is always achievable. Tearing-open of the anchoring cartridge is guaranteed because the end of the bolt tube is designed so as reliably to open the anchoring cartridge upon the application of pressure. According to an advantageous form of construction it is provided that the 15 mixing head is designed to be supported on the wall edge of the bolt tube. This guarantees, on the one hand, that the mixing head is not inadvertently pressed into the bolt tube but instead acts as a buffer between the end of the borehole and the actual bolt tube and, on the other hand, that the exit hole remains protected by the actual mixing head since 20 the exit hole cannot be adversely affected either by the static mixer or by dirt. How the protection of the exit hole may look is described further below. The most advantageous way of realizing the supporting of the mixing 25 head on the bolt tube is for the mixing head to have a head that is equipped with a support plate, the outer edge of which is designed to be approximately flush with the tube outer wall. This support plate is therefore optimally supported on the tube outer wall and/or on the bolt tube, thereby reliably preventing a complete insertion of this mixing head 30 into the rod inner bore. On the other hand, it is thereby ensured that the exit hole, which is integrated into the mixing head, is kept open.

WO 2010/133883 PCT/GB2010/050823 4 The integrating of the exit hole into the mixing head is advantageously effected in that the head is provided with a crosspiece that extends across the exit hole. Thus, the anchoring compound charge after leaving the 5 static mixer is introduced into the head, in which the actual exit hole is disposed in the same axis as the rod inner bore. A blocking or impairment as a result of sludge or drillings at the end of the borehole is prevented by means of the crosspiece because this is supported on or against the end of the borehole and so the exit hole always remains spaced 10 apart from the end of the borehole. The anchoring compound or, in simple terms, the anchoring, which may be a mortar or even a one component or two-component plastics compound, passes out of the exit hole and is then even more advantageously deflected along the crosspiece before then flowing into the cavity between bolt tube and borehole wall. 15 The head and/or the entire mixing head are supported via the support plate on the actual bolt tube, so that during the outflow too an open exit hole is permanently guaranteed. A "breaking-off" of the crosspiece is reliably prevented in that the head 20 with the crosspiece comprises supports resulting in the shape of a perforated truncated cone and is moreover connected to the support plate. These supports are sufficiently stable and because of their special construction simultaneously contribute towards the crosspiece having only an extent corresponding approximately to the exit hole. The crosspiece is 25 integrally connected to these supports, wherein these supports defining a truncated cone advantageously facilitate the introduction of the bolt tube with the mixing head into the borehole. The introduction of the bolt tube with the mixing head is further 30 facilitated in that there are associated with the supports triangular ribs, which project beyond the oblique outer wall of the supports. As the bolt WO 2010/133883 PCT/GB2010/050823 5 tube is rotating as it is introduced, "the path is cleared for the mixing head", with the result that an easy positioning of the bolt tube in the borehole may be guaranteed. 5 The outward flow of the anchoring or the anchoring compound in the mixed state is further improved in that two or more supports are provided, which are stable and designed so as to define with the crosspiece outwardly widening channels for the exit hole. After leaving the exit hole the "deflection" of the anchoring occurs only after leaving 10 the exit hole, thereby simultaneously also ensuring that the end of the borehole also is effectively filled with this anchoring compound and/or the anchoring. The deflection of the anchoring flow is further promoted in that a 15 distribution head is positioned in the centre of the free part of the crosspiece on the underside thereof. This distribution head may have the shape of a cone or alternatively any other shape that promotes the deflection of the anchoring flow. 20 It has already been pointed out further above that the mixing head comprises the head projecting beyond the bolt tube as well as an attachment that may be inserted into the bolt tube. The seating of the attachment tightly in the bolt tube and hence the exact positioning is guaranteed in that the mixing head has, spaced apart from the outer edge, 25 a plurality of fastening rings, which project from the wall, or a thread. The fastening rings are made preferably from the same material as the attachment itself and/or the entire mixing head but may alternatively be manufactured from a softer material that promotes sealing. 30 The insertion of the mixing head and its attachment into the bolt tube is promoted in that the fastening rings are designed so as to extend obliquely WO 2010/133883 PCT/GB2010/050823 6 in the direction of the outer edge or to have such chamfers at the end. Six or eight of such fastening rings may be attached, although it is also possible to work with fewer of such fastening rings because in principle pushing of the mixing head out of the bolt tube is prevented by the fact 5 that the mixing head during injection of the anchoring is supported against the end of the borehole. During initiation and implementation of the injection process, i.e. the expressing of the anchoring into the borehole, the anchoring cartridge is 10 to be slit open or torn at the edge to ensure that the anchoring can escape. This may be achieved in that the end of the mixing head that is to be inserted into the bolt tube is designed with internal cutting edges, which widen in a funnel-shaped manner from the outer edge to the end and hence result in a lead-in funnel. The anchoring cartridge is therefore 15 introduced into the attachment of the mixing head, where it is reliably slit open by the internal cutting edges. This reliably prevents the anchoring cartridge during initiation of the injection process from being able to slip or skew, such that the anchoring cartridge is not torn open at all or is not torn fully open. 20 This introduction of the anchoring cartridge into the lead-in funnel may be promoted in that the cutting edges are disposed on the inner wall of the mixing head and/or the attachments thereof so as to leave a lead-in clearance relative to the funnel edge. The undamaged and hence taut 25 anchoring cartridge is therefore inserted into the lead-in funnel, before only then being slit open and hence destroyed. The shape of the lead-in funnel may advantageously be additionally exploited by designing the cutting edges such that they follow the shape 30 of the lead-in funnel and retain their height. It is thereby ensured that the inserted or, to put it better, press-fitted anchoring cartridge is at any rate WO 2010/133883 PCT/GB2010/050823 7 slit open and destroyed in such a way that the anchoring contained therein also passes reliably into the region of the static mixer in order to be mixed intensively there. 5 Further above it has been extensively described how the mixing head is to act and how it acts on account of its shaping. This special shape is achievable in a particularly advantageous manner if the mixing head is manufactured from plastic, wherein it is, as explained further below, an integral part and is completed only by the static mixer or even together 10 with the latter forms one component. In the two-part form of construction the static mixer is inserted into the mixing head and/or the attachment thereof and fastened there, so that the anchoring released when the anchoring cartridge is torn open is reliably 15 pressed through the static mixer before leaving the exit hole of the mixing head. To ensure that the cross section of the exit hole is not impaired from the inside either, it is provided that in the region of the head a support web for the static mixer is provided or that the distribution head on the crosspiece serves as an end stop for the static mixer that is to be 20 inserted. In both forms of construction, the static mixer is prevented from being, as it were, pushed in front of or into the exit hole in a way that adversely affects the escape of the anchoring. It is also conceivable to work with mortar or some other material. For 25 this purpose, it is provided that the anchoring compound charge is provided in the form of a direct filling of the bolt tube and that there is associated with the discharge end of the bolt tube a mixing head, which is supported there and comprises and protects the exit hole, with or without an introducible static mixer and a rupture disk disposed in flow direction 30 upstream of the static mixer. Here, depending on the composition of the direct filling a static mixer that is introducible into the mixing head is or WO 2010/133883 PCT/GB2010/050823 8 is not used. The rupture disk and/or membrane ensures that a suitably high pressure is first built up before this anchoring material then passes out through the static mixer or alternatively directly into the cavity around the bolt tube. 5 It has already been pointed out further above that the described solution is notable for that fact that the mixing head used is characterized by a plurality of properties and may moreover be manufactured advantageously and economically as a plastic part. The invention further provides that 10 the mixing head with attachment is designed as an integral part that receives and integrates the static mixer as a second component, or that mixing head, attachment and static mixer are designed so as to form one component. The latter is achievable for example in that two halves are injection-moulded in one operation and then glued together in such a way 15 as to form one component, i.e. the static mixer is fully integrated into the exit nozzle. The two-part form of construction however has the advantage that if need be, as described further above, it is possible to work without the static mixer, for example in the case of a directly filled hollow bolt, which does not necessarily require a static mixer. 20 Depending on the anchoring cartridge used, it may be difficult to slit open the wall of the anchoring cartridge by means of the described cutting edges and hence ensure that the anchoring or the anchoring components can escape. The stated object may accordingly also be achieved in that 25 the bolt tube is open at the discharge end and equipped with a mounted mixing head, in which the exit hole or exit holes are positioned so as to be protected from clogging, and that on the discharge end in front of the static mixer there are disposed a collecting basket for the clip closing the anchoring cartridge as well as a fastening ring that prevents the anchoring 30 cartridge from slipping. With this solution, first of all the mixing head already described in detail further above offers the possibility of WO 2010/133883 PCT/GB2010/050823 9 permanently ensuring that the exit holes are also effectively clear, so that the anchoring and/or the anchoring compound charge may also pass reliably into the cavity around the bolt rod and/or the bolt tube in order then to bond the bolt tube effectively to the rock. Furthermore, here, 5 instead of working with cutting edges or the like, the end of the anchoring cartridge that is associated with the static mixer and is closed by means of a clip is influenced to such an extent that this clip is pressed or slides off the wall, with the result that the anchoring cartridge is then open fully, i.e. practically over its entire cross section. The anchoring compound 10 charge may then pass without difficulty into the static mixer and from there into the exit holes, wherein the pushed-off clip is reliably caught in the collecting basket, i.e. cannot impair or even destroy the static mixer. The pressure needed to push off the clip is achieved in that the anchoring cartridge is prevented from slipping by means of the fastening ring, so 15 that it accordingly inflates and then presses off the clip mounted on the wall of the cartridge in order to release the entire cross section of the anchoring cartridge. The fastening ring in this case encircles the end of the anchoring cartridge in a way that inevitably results in the bulging of the wall of the anchoring cartridge and hence in the pressure needed to 20 push the clip off the wall. In order to ensure that the clip is also reliably pressed and/or pushed off the wall of the anchoring cartridge, it is provided that at the clip, which closes the anchoring cartridge and is disposed on the end facing the static 25 mixer, the wall projecting length is designed to terminate closely adjacent to the clip. As a rule, this wall projecting length is correspondingly trimmed prior to the introduction of the anchoring cartridge into the bolt tube or it is already correspondingly worked during manufacture of the anchoring cartridge. Thus, the distance that the clip has to slide to be 30 pushed off is delimited to such an extent that with the previously WO 2010/133883 PCT/GB2010/050823 10 described inflation of the anchoring cartridge the necessary pressure is also able to build up and take effect. In order to optimize the support of the collecting basket and precisely 5 define its position, it is provided that the collecting basket comprises a base, which has a central recess adapted to the dimensions of the static mixer, and the webs forming the side wall. The collecting basket is mounted by its recess quasi onto the static mixer and is then no longer able to vary the clearance relative to the static mixer, wherein the webs 10 have corresponding projections, on which the edge of the static mixer is supported. The webs are then used simultaneously to support the fastening ring too, with the result that, after these components have been integrated into the rod inner bore, all of the parts are disposed in a way that allows them to function optimally with one another. 15 This supporting of the fastening ring on the webs is possible in a particularly reliable and uniform manner if the fastening ring is designed as a disk with inner opening and so as to be supported on the web ends and/or the inner wall of the bolt tube. Thus, this fastening ring and/or 20 the disk may act in the manner described further above, i.e. the end of the anchoring cartridge is held precisely and influenced in such a way that the necessary pressure must build up. A uniform influencing of the anchoring cartridge is achieved in that the 25 ejection plunger takes the form of a hat-shaped piston and is introduced, with the piston head facing the anchoring cartridge, into the bolt tube and is formed so that its sealing rim lies sealingly against the inner wall of the bolt tube. The ejection plunger is therefore displaced from the direction of its open side by the hydraulic liquid or some other pressure medium 30 inside the bolt tube, wherein the sealing rim ensures that the ejection plunger in the form of the piston cannot become skewed but acts WO 2010/133883 PCT/GB2010/050823 11 uniformly upon the anchoring cartridge, and does so independently of the state of the inner wall of the bolt tube. As this inner wall is not smooth but undulates, for example as a result of formation of the outer ribs on the other wall of the bolt tube, it is important that the piston via this 5 sealing rim always lies against the inner wall of the bolt tube. This stabilization of the piston is even more optimal if the piston takes the form of a single- or multi-part double piston or multiple piston, because then there are quasi two or more annular seating surfaces, for the double 10 piston or multiple piston has at least two sealing rims that slide along the inner wall of the bolt tube. In this case, these guiding- and sealing rims are flexible to a limited extent, so that they may also undertake effective guiding and sealing functions. 15 The uniform guidance of the piston and hence the uniform loading of the anchoring cartridge is additionally improved if there is associated with the piston or double piston or the multiple piston a guide element, which is formed on the side of the piston head, detachably connected thereto or provided as a separate part. The piston, as it is displaced in the direction 20 of the anchoring cartridge, therefore on the one hand has an additional support edge relative to the inner wall of the bolt tube and at the same time encloses the corresponding end of the anchoring cartridge, so that the anchoring cartridge purposefully guides and/or conversely also guides the piston. 25 To allow optimum adaptation to the diameter of the end of the anchoring cartridge and also improve sliding on the inner wall of the bolt tube, it is provided that the guide element is designed to comprise resilient lateral elements, which are fastened to the base and have at the end an outwardly 30 oriented reverse-drawn edge. This reverse-drawn edge prevents the individual lateral elements from possibly becoming stuck or caught on the WO 2010/133883 PCT/GB2010/050823 12 inner wall of the bolt tube. The uniform guidance of the piston is therefore further optimized, wherein the number of lateral elements may be varied. It is advantageously between 6 and 10. 5 The invention is notable for the fact that a rock bolt is provided, which may be used as an anchoring bolt and which ensures that the required anchoring material is always completely and reliably expressed from its position in the bolt tube and then reliably fills the cavity around the anchoring bolt. The mixing head that is used is of a simple construction 10 and is stable enough during the anchoring process to maintain a position that at any rate ensures a reliable escape of the anchoring compound from the bolt tube. The exit hole is accommodated in a protected manner in the mixing head and disposed in such a way that there is no need for a substantial deflection inside the bolt tube and/or the mixing head. Rather, 15 the anchoring compound flows first towards the end of the borehole, filling it completely, and is then or alternatively simultaneously fed into the cavity around the bolt tube, where it ensures the stabilization of the rock and the bonding of bolt tube and rock. It is further advantageous that the present invention is extremely versatile, i.e. independently of 20 which type of anchoring cartridge and/or anchoring material is used. Installation is moreover so straightforward that this work may be carried out even by semi-skilled workers. Opening of the anchoring cartridge is moreover optimally ensured if in front of the static mixer there are associated a collecting basket for the clip closing the anchoring cartridge 25 and a fastening ring that prevents the anchoring cartridge from slipping. The collecting basket ensures that the clip, which as a result of inflating of the jacket of the anchoring cartridge slips or, to put it better, is pushed off the end of the anchoring cartridge, is caught and cannot impair the static mixer, while the fastening ring ensures that the necessary pressure 30 builds up in the anchoring cartridge and then ensures that the clip is pushed off the anchoring cartridge.

WO 2010/133883 PCT/GB2010/050823 13 Further details and advantages of the invention emerge from the following description of the accompanying drawings, in which a preferred embodiment with the requisite details and individual parts is represented. 5 The drawings show in: Figure 1 shows a rock bolt that has been at least partially introduced into a borehole; 10 Figure 2 shows the rock bolt of Figure 1 in longitudinal section; Figure 3 shows a mixing head that has been inserted into a bolt tube shown here in section; 15 Figure 4 shows the mixing head in a perspective view; Figure 5 shows the mixing head in longitudinal section with inserted static mixer; 20 Figure 6 shows a bolt tube with mixing head and direct charge with static mixer; Figure 7 shows a bolt tube with single-chamber cartridge and mixing head without static mixer; 25 Figure 8 shows the construction shown in Figure 6, here without static mixer; Figure 9 shows a cross section through a bolt tube shortly before 30 expression of the anchoring cartridge; WO 2010/133883 PCT/GB2010/050823 14 Figure 10 shows an enlarged representation of the part of the bolt tube disposed in the end of the borehole; Figure 11 shows the collecting basket according to Figure 10 with 5 disk in a perspective view; Figure 12 shows an ejection plunger in the form of a piston with guide element; 10 Figure 13 shows a guide element in side view with a plurality of lateral elements; and Figure 14 shows an ejection plunger in the form of a double piston in side view. 15 Figure 1 shows a rock bolt I in the form of an anchoring bolt partially placed in a drilled hole 10 (or borehole 10). Rock bolt 1 has a bolt tube 2, an anchoring cartridge 7,21 (not shown in Figure 1), an ejection plunger 54 (not shown in Figure 1) and a mixing head 15. 20 Bolt tube 2 is hollow, having an internal channel 5, and has an inlet (not shown) and an outlet in the form of discharge end 4. The bolt tube 2 is equipped on the outside with external ribs 3. Ejection plunger 54 is placed in the internal channel 5 of bolt tube 2 near its inlet such that the 25 anchoring cartridge 7 (or a multi-chambered anchoring cartridge 21) is arranged in the internal channel 5 between the ejection plunger 54 and the mixing head 15. Ejection plunger 54 is moveable along the internal channel 5. In use, ejection plunger 54 may be used to load the anchoring cartridge 7,21 in the bolt tube 2. 30 WO 2010/133883 PCT/GB2010/050823 15 Mixing head 15 has an attachment 17 for opening the anchoring cartridge, a static mixer 9, a support plate 24, a head 16 which forms an exit hole 8. Disposed on the discharge end 4 of the bolt tube 2 is the mixing head 15 5 with the integrated exit hole 8. This exit hole 8 is practically an extension of the inner channel 5 of bolt tube 2 through mixing head 15 when it is mounted on the bolt tube 2. Here, of the entire mixing head 15 only the head 16 is visible in Figure 1. Head 16 engages the end 11 of the drilled hole 10 by its upper edge without thereby risking blocking the 10 exit hole 8, which is in a lower position. Between the bolt tube 2 and the sides of the drilled hole 10 is a cavity 12 that is to be filled by means of an injection operation with anchoring composition, anchoring or an anchoring compound, which is not shown in Figure 1. 15 Figure 2 shows a section through the bolt tube 2 shown in Figure 1. It may be seen that an anchoring compound charge 6, namely in the form of an anchoring cartridge 7 is placed in the inner channel 5 of bolt tube 2,. This anchoring cartridge 7 may be pressed by the ejection plunger 54 in the direction of the mixing head 15 and/or discharge end 4 and in the 20 process the contents of the anchoring cartridge 7 are emptied in the manner described in detail further below. In this case, this anchoring compound charge 6, mixture and/or anchoring compound previously has to be pressed through a static mixer 9, which is accommodated at or near the outlet end 4 of the inner channel 5 of the bolt tube 2 or, more 25 precisely, in the mixing head 15. This mixing head 15 comprises not only the head 16 but also an attachment 17, which extends into the inner channel 5 of bolt tube 2. In this form of construction, attachment 17 or mixing head 15 has a 30 proximal end 18 which has on the inside cutting edges 19, 20, which ensure that when the ejection plunger 54 is activated to pressurise the WO 2010/133883 PCT/GB2010/050823 16 anchoring cartridge 7,21 against proximal end 18 of attachment 17. the cartridge 7,21 is slit open so that the anchoring material contained therein moves through the attachment 17 into the static mixer 9, where it is mixed intensively because of the pressure applied by the ejection plunger 5 54 which may be high pressure. The shape of the cutting edges 19, 20 is illustrated in Figure 5, where it may be seen that these cutting edges 19, 20 are sharp and pointed enough to guarantee an effective slitting-open of the anchoring cartridge 7,21. 10 Ejection of the mixing head 15 having head 16 and attachment 17 out of the inner channel 5 of bolt tube 2 is prevented because fastening rings 37, 38 are disposed on the inner wall 36 of mixing head 15. Fastening rings 37,38 rub against the inner wall of the tube inner channel 5 and thereby provide a friction fit to hamper such an ejection, but also the pushing-in, 15 this being necessary, if the rock bolt is correspondingly equipped. Also, ejection of the mixing head is prevented in use because pressure is applied by the ejection plunger 54 when the head 16 and/or the mixing head 15 is placed against drilled hole 10 and provided with a support plate 24, the bolt edge 26 of which projects as far as the tube outer wall 20 25. This support plate 24 is therefore fully supported on the wall edge 23 of the bolt tube 2 and, as the mixing head 15 during insertion is supported against the end 11 of the borehole, ejection out of the borehole 10 is prevented when at the other end the ejection plunger 54 is actuated. 25 Figure 3 shows a mixing head 15 that has been fully inserted into the inner channel 5 of the bolt tube 2. Here it may be seen that the fastening rings 37, 38 at the end have a chamfer 39, which is to facilitate introduction into the inner channel 5. At the same time the chamfers 39 make it difficult for the mixing head 15 to be retracted and hence pushed 30 out of the tube inner channel 5.

WO 2010/133883 PCT/GB2010/050823 17 It may moreover be seen that the head 16 has a special shape, which is characterized in that a crosspiece 27 is connected by supports 28, 29 to the support plate 24. This crosspiece 27 extends across the exit hole 8, thereby preventing dirt from being able to pass into the exit hole 8 from 5 borehole 10, but in particular thereby preventing the exit hole 8 from being able to lie directly against the end 11 of the borehole 10. The supports 28, 29 have a special shape and, viewed over the entire head 16, result in a truncated cone that ensures and facilitates the insertion of the entire bolt tube 2 with the mixing head 15 into the borehole 10. This is 10 additionally assisted by the provision of ribs 31 on the oblique outer wall 30 of the supports 28, 29. The ribs 31 facilitate the screwing-in of this rock bolt 1 and/or anchoring bolt when it is inserted into the borehole 10. The supports 28. 29 together with the crosspiece 27 moreover form a kind 15 of channel 32, so that the anchoring material leaving the exit hole 8 may penetrate reliably and without influence into the cavity 12. On the underside of the crosspiece 27, a distribution head 34 is provided, which promotes the flow-off of the anchoring material but above all serves to prevent the static mixer 9 from moving out too far, for which purpose the 20 support webs 46 evident from Figure 5 may also be used. The shape of the supports 28, 29 moreover ensures that the free part 33 of the crosspiece 27 is always so dimensioned that it reliably withstands the pressure that arises. 25 The bottom end of the attachment 17 forms a lead-in funnel 40, thereby facilitating the insertion of the anchoring cartridge 7. Figure 4 shows a perspective view of the mixing head 15 as a component drawing, wherein it is apparent that below the crosspiece 27 there 30 remains a relatively large exit hole 8, out of which the mixed anchoring compound may flow, wherein the channel 32 formed by the supports 28, WO 2010/133883 PCT/GB2010/050823 18 29 has a promoting effect. The stable construction of the transverse web 27 allows it to be pressed against the end 11 of the borehole (not shown here), thereby simultaneously achieving the effect that the mixing head 15 is mounted by its support plate 24 onto the wall edge 23 and hence 5 simultaneously secures the position of the mixing head 15. Here too, at the bottom end of the attachment 17 the lead-in funnel 40 may be seen, which facilitates the insertion of the anchoring cartridge 7 (not visible here). The previously mentioned channel 32 terminates in a chamfer 52 in order to facilitate and/or define the flow-off of the mixed anchoring 10 material. As an alternative to chamfer 52, channel 32 may terminate in a curvature 51, seen in Figure 5. However, the normal situation may be that a rectangular and/or angular formation of the bolt edge 26 is sufficient. The cross-section shown in Figure 5 represents the support webs 6 or the support web, against which the inserted static mixer 9 15 strikes, so that the actual exit of the exit hole 8 remains totally unaffected. As an additional safeguard or merely as a safeguard it is also possible simultaneously to use the distributor head 34, which may be seen particularly clearly here. The static mixer 9 may have a different shape, wherein it to some extent adjoins the cutting edges 19, 20 that may be 20 seen at the bottom end, i.e. in the lead-in funnel 40. The static mixer 9 may be inserted past these internal cutting edges 19, 20 into the then smooth-walled part of the attachment 17 and, as mentioned, be placed against the support web 46. 25 In the funnel-shaped part, i.e. in the lead-in funnel 40 the previously mentioned cutting edges 19, 20 are formed, wherein these terminate in a downward direction in a point, this applying both to the cutting edges 19, 20 and to the cutting edges 19', 20'. Between these ends and the funnel edge 42, a smooth lead-in clearance area 41 is provided in order thereby 30 to promote the introduction of the anchoring cartridge 7, i.e. along the smooth inner wall 43, until the anchoring cartridge 7 then strikes the WO 2010/133883 PCT/GB2010/050823 19 points of the cutting edges 19, 19', 20, 20' and is slit open by these cutting edges. The cutting edges 19, 20 have a height that remains constant, so that with narrowing of the lead-in funnel 40 they automatically cut deeper into the inner wall of the anchoring cartridge 7. 5 Figures 6, 7 and 8 show special forms of construction of the anchoring material. In Figures 6 and 8, instead of an anchoring cartridge 7, here the inner channel 5 is directly filled with an anchoring compound 49. This direct filling of anchoring compound 49 requires the use of a rupture 10 disk 48, which is supported on the funnel edge 47 or alternatively on the bottom end of the cutting edges 19, 20 and ensures that this direct filling anchoring compound 49 may be placed under pressure as long as is necessary either to discharge a mixed output through a static mixer 9 (as shown in Figure 6) or in the absence of such a static mixer 9 (as shown in 15 Figure 8) the mixed material. Figure 7 on the other hand shows a form of construction, in which a single-chamber cartridge 50 is used. Here it is not shown that the single chamber cartridge 50 as a rule likewise contains two components, the 20 second component however in the form of globules or the like, the inner wall of which is burst when the pressure is applied to the single-chamber cartridge 50, so that the two components then mix with one another. Occasionally, in this case too it is possible to dispense with a static mixer 9, as is shown in Figure 7. In Figure 6, Figure 7 and Figure 8 the 25 injection process or expression process is generated likewise by means of an ejection plunger 54, wherein the necessary pressure upon the ejection plunger 54 may be effected hydraulically or by means of compressed air. The invention is notable in particular for the fact that it uses a relatively 30 simple, generally integral component in the form of the mixing head 15, which ensures uniform mixing and discharging of the anchoring WO 2010/133883 PCT/GB2010/050823 20 compound without any risk of early clogging of the exit hole 8 with drillings, waste from the drilling of borehole 10 or the like. The anchoring compound passes without changing direction into this mixing head 15 and/or the head 16 thereof, wherein in particular Figures 7 and 8 5 show clearly that this exit hole 8 has the same diameter as the longitudinal bore behind the lead-in funnel 40 up to reaching the support plate 24 of the mixing head 15 that has the exit hole 8. It is therefore ensured that, after for example the anchoring cartridge 7 or the single chamber cartridge 50 has been slit open, the already pre-mixed anchoring 10 compound material is discharged rapidly and reliably. Figure 9 shows a further section of a bolt tube 2 with the discharge end 4, on which the head 16 is disposed. The static mixer 9 is disposed in front of the discharge end 4, in the tube inner channel 5. Adjoining the static 15 mixer 9 in this construction is a collecting basket 58, on which a fastening ring 60 is supported. The collecting basket 58 has a side wall 66 that comprises a plurality of webs 67, 68. This sub-portion of the bolt tube 2 is represented in an enlarged view in Figure 10 and described in detail in this connection. 20 At the opposite end of the bolt tube 2 the tube inner channel 5 is closed by means of a connection stopper 55, which is used for example to connect the pressure generator. This connection stopper 55 here has the shape of a setting adapter, wherein for example through the polygonal 25 socket 56 compressed air is applied to the ejection plunger 54. The ejection plunger 54 takes the form of a piston 74, which is guided along the inner wall 72 of the tube inner channel 5. To ensure a uniform movement, it is designed so as to lie at least at two annular points against the inner wall 72 and moreover comprises a guide element 78, which, as 30 Figure 9 reveals, securely encloses the end of the anchoring cartridge 7 adjacent thereto. By said means a uniform action of pressure upon the WO 2010/133883 PCT/GB2010/050823 21 entire anchoring cartridge 7 as well as an aligning of the ejection plunger 54 are guaranteed. By means of the ejection plunger 54 in the form of piston 74 and the 5 guide element 78 disposed in front, which are detachably connected to one another by piston head 75 and base 79, the anchoring cartridge 7 is placed under pressure, wherein at the opposite end it is not slit open in the manner described further above, rather it is ensured that the clip 59 fitted on the end is pushed off the end 61 of the anchoring cartridge 7. 10 The anchoring compound charge 6 of the anchoring cartridge 7 may then move purposefully through the static mixer 9 and out of the discharge end 4. For guaranteed opening of the end 61 of the anchoring cartridge 7 a 15 fastening ring 60 in the form of a disk 70 is provided, an enlarged perspective view of which is provided in Figure 11. Here it may be seen that this disk 70 has a large central inner opening 73 so that the loaded anchoring cartridge 7 is unable to move completely in the direction of collecting basket 58. The anchoring cartridge deforms, there is 20 backpressure and hence an increased pressure, which then ensures that the clip 59 is pressed off the end 61 of the anchoring cartridge 7. To promote this, there is only a very slight wall projecting length 62, i.e. prior to introduction of the anchoring cartridge 7 into the tube inner channel 5 such a slight wall projecting length 62 is produced by trimming 25 or alternatively the clip 59 was pressed from the start in a suitably tight manner onto the anchoring cartridge 7. It may be seen in Figure 10 and Figure 11 that the disk 70 is supported on the web ends 71 of the webs 67, 68, thereby additionally assisting and guaranteeing the inflation of the anchoring cartridge 7. The side wall 66 of the collecting basket 58 is 30 formed by these webs, as Figure 11 in particular shows clearly. The base 64 of the collecting basket 58 has a recess 65, the dimensions of which WO 2010/133883 PCT/GB2010/050823 22 correspond to those of the static mixer 9. The static mixer 9 is therefore practically inserted into this recess 65 in the base 64 and is then blocked because corresponding cutouts 69 are provided in the webs 67, 68 5 As described further above, the piston 74 has a kind of hat shape and at the end remote from the piston head 75 is equipped with a sealing rim 76. This ensures that the piston 74 at least at this end scrapes along the tube inner channel 5 and/or the inner wall 72 and ensures smooth guidance. This guidance is additionally promoted in that the piston 74 takes the 10 form of double piston 77, as Figure 14 reveals. This double piston 77 has two sealing rims 76, 76', thereby promoting the uniform movement of the double piston 77. In Figure 14 it is further indicated that the bottom part 84 of the double piston 77 has a recess 85, into which the connection stopper 55 is inserted when both components are in the initial position. 15 The piston 74 and/or double piston 77 is combined with a guide element 78, wherein Figure 12 represents such a guide element 78 with six and/or eight lateral elements 80, 81, while according to Figure 13 such a guide element 78' has far more of such lateral elements 80, 81. All of these 20 then resiliently disposed lateral elements 80, 81 have on the free end a reverse-drawn edge 82, which ensures that the guide element 78 cannot be pressed into the inner wall of the anchoring cartridge 7 but is instead pressed only against the inner wall of the tube inner channel 5 and then simultaneously ensures that both components, which are connected by 25 piston head and base to one another, act in a uniformly guided manner upon the anchoring cartridge 7. Returning to Figure 11, it is additionally pointed out that the disk 70 has an edge 83 that is formed into a kind of cutting edge in order thereby to 30 promote sliding along the tube inner channel 5.

WO 2010/133883 PCT/GB2010/050823 23 All of the described features, including those inferable exclusively from the drawings, are regarded individually and in combination as central to the invention.

Claims

1. Rock bolt (1) having: an anchoring compound (7) for anchoring the rock bolt in a 5 borehole; an ejection plunger (54) for ejecting the anchoring compound from the rock bolt; a bolt tube (2) for receiving the ejection plunger and the anchoring cartridge wherein the bolt tube has a discharge end (4) which forms one 10 or more exit holes (8); and a mixing head (15) which wholly or partially covers the discharge end of the bolt tube to protect the one or more exit holes from clogging.

2. A rock bolt of Claim 1 having a static mixer (9) for mixing the 15 anchoring compound wherein the bolt tube receives the static mixer.

3. A rock bolt of Claim I or Claim 2 wherein the anchoring compound is provided in an anchoring cartridge. 20

4. A rock bolt of any one of the preceding claims wherein the mixing head has a proximal end (18) which is inserted into the bolt tube wherein the proximal end receives the static mixer and the anchoring cartridge (7), is designed so as reliably to open the anchoring cartridge (7) upon the application of pressure. 25

5. A rock bolt of any one of the preceding claims wherein the mixing head is supported on the distal end of the bolt tube.

6. A rock bolt according to claim 5 wherein the mixing head 30 comprises a head (16) that is equipped with a support plate (24), the outer WO 2010/133883 PCT/GB2010/050823 25 edge (26) of which is designed to be approximately flush with an outer wall (25) of the bolt tube.

7. A rock bolt according to any one of the preceding claims wherein 5 the mixing head is provided with a crosspiece to reduce the ingress of dirt, preferably the crosspiece extends across the one or more exit holes, more preferably the mixing head comprises supports (28, 29) to form a perforated truncated cone, preferably the perforated truncated cone is connected to the support plate. 10

8. A rock bolt according to claim 7 wherein the head is provided with ribs to assist with the insertion of the rock bolt into a borehole, preferably the ribs are associated with the supports, more preferably the ribs are triangular and project beyond the oblique outer wall (30) of the 15 supports.

9. A rock bolt according to claim 7 or claim 8 wherein the head has two or more stable supports to define with the cross piece channels for the one or more exit holes. 20

10. A rock bolt according to any one of the preceding claims wherein the mixing head has a distribution head to promote the outflow of the anchoring compound, preferably the distribution head is arranged below the cross-piece. 25

11. A rock bolt according to any one of the preceding claims wherein the mixing head has one or more fastening rings (37, 38) to provide a friction fit with the bolt tube. WO 2010/133883 PCT/GB2010/050823 26

12. A rock bolt according to claim 11 wherein the one or more fastening rings have a chamfer (39) to facilitate insertion of the mixing head into the bolt tube. 5

13. A rock bolt according to any one of the preceding claims wherein the mixing head is formed from a plastics material.

14. A rock bolt according to any one of the preceding claims wherein the head has a support web (46) for the static mixer. 10

15. A rock bolt according to claim 1 wherein the anchoring compound is directly filled in the bolt tube and wherein a rupture disk is inserted between the anchoring compound and the static mixer. 15

16. A rock bolt according to claim 1 or claim 13 wherein the mixing head has an attachment which is designed as an integral part that receives and integrates the static mixer as a second component, or that the mixing head, attachment and static mixer form one component. 20

17. A rock bolt according to any one of the preceding claims wherein the anchoring compound is provided in an anchoring cartridge closed by a clip (59) and wherein the mixing head has a collecting basket (58) for receiving the clip. 25

18. A rock bolt according to claim 17 wherein the anchoring cartridge is arranged in the bolt tube such that the clip is at the distal end of the cartridge such that the static mixer terminates closely adjacent to the clip. 30

19. A rock bolt according to claim 17 or claim 18 wherein the collecting basket comprises a base which has a central recess adapted to WO 2010/133883 PCT/GB2010/050823 27 the dimensions of the static mixer and the webs (67, 68) forming the side wall.

20. A rock bolt according to any one of claims 17 to 19 wherein the 5 anchoring cartridge has a fastening ring for preventing the cartridge from slipping, preferably the fastening ring is designed as a disk (70) with inner opening (73) and so as to be supported on the web ends (71) and/or the inner wall (72) of the bolt tube (2). 10

21. A rock bolt according to any one of the preceding claims wherein the ejection plunger is in the form of a hat-shaped piston (74) and is preferably arranged with the piston head (75) facing the anchoring cartridge in the bolt tube such that it lies with its sealing rim sealingly against an inner wall of the bolt tube. 15

22. A rock bolt according to claim 21 wherein the piston is in the form of a single- or multi-part double piston (77) or a multiple piston, preferably the double piston or multiple piston comprises one, two or more mutually spaced guiding- and sealing rims (76) that are flexible to a 20 limited extent.

23. A rock bolt according to claim 21 or claim 22 wherein a guide element (78) is associated with the piston and is formed on the side of the piston head, optionally detachably connected thereto or provided as an 25 individual part.

24. A rock bolt according to claim 23 wherein the guide element is designed so as to comprise resilient lateral elements (80, 81), which are fastened to the base (79) and have at the end an outwardly oriented 30 reverse-drawn edge (82).