WO2013104021A1

WO2013104021A1 - Improved torque tensioning system for cable bolts

Info

Publication number: WO2013104021A1
Application number: PCT/AU2013/000016
Authority: WO
Inventors: Warwick Hutchins
Original assignee: Quantax Pty Ltd
Priority date: 2012-01-10
Filing date: 2013-01-10
Publication date: 2013-07-18
Also published as: AU2013209274A1; AU2017219084A1

Abstract

An improved torque tensioning system for applying high load tension to a cable bolt of the type including a threaded sleeve, an anchor plate, a domed washer, and a tensioning nut, the system comprising a drive assembly including a housing and internal gearing; a socket assembly removably mounted to the drive assembly, the socket assembly having an outer socket having a substantially hollow body, and an inner socket rotatably received within the hollow body of the outer socket, wherein the inner socket is substantially co-axially mounted within the outer socket, whereby the inner socket includes a drive receptacle for receiving the tensioning nut of the cable bolt in an operating condition, and wherein the outer socket includes a first open end for receiving the inner socket and a mounting portion about the opening, and a second opposite end having a cut-out shaped opening adjacent thereto for engaging at least a portion of the domed ball of the cable bolt in an operating condition; a drive shaft having a first mounting end adapted for rotatable mounting of an output drive of the drive assembly; and a second mounting end for drivably engaging the inner socket of the socket assembly; a reaction structure fixedly mounted at one end thereof on a portion of the housing of the drive assembly and extending substantially co-axially with the drive shaft between a portion of the drive assembly and removably fixed to the mounting portion of the outer socket; and wherein the cut-out shaped opening of the outer socket is adapted to engage at least a portion of the domed washer of the cable assembly so that the reaction structure is substantially prevented from rotation when the drive assembly is in an operating condition, and whereby the drive receptacle of the inner socket engages the tensioning nut of the cable bolt such that when the drive shaft is caused to rotate by the drive assembly the tensioning nut is tightened on threaded portions of the sleeve against the domed washer, which in turn bears against an anchor plate and tensions the cable.

Description

Title: Improved Torque tensioning system for cable bolts Field of the invention The present invention relates to an improved cable bolt tensioning assembly for use in supporting and stabilizing roof structures in underground mining and excavations for civil engineering and the like operations. In particular the present invention relates to an improved cable bolt tensioning tool for use in applying high torque and thereby high tension to the cable bolt, which enhances working safety in underground excavation during formation of tunnels.

Background of the invention

Roof and wall support is critical in underground excavation and tunnel formation to prevent the possibility of collapse. Rock bolts such as rigid shaft rock bolts and flexible cable bolts are widely used to reinforce and stabilise rock strata.

Many different types of cable bolts have been produced in the past. Generally, a cable bolt includes a number of closely spaced wires which have a first end adapted for fitting into a bore hole, and a second end including a drive portion and a cylindrical sleeve, whereby the drive portion is adapted for engagement with an industry standai^'d drill rig chuck or the like for installing the cable by inserting and spinning the cable bolt into a drilled hole. The cylindrical sleeve includes a threaded external surface to receive a tensioning nut for tightening against an anchor plate so as to tension the cable bolt. The cable bolt assembly can also include a universal domed ball with a central opening through which the cable bolt extends, the domed ball being located intermediate the tensioning nut and anchor plate, and whereby the domed washer has a domed head portion for angular- alignment relative to the anchor plate, and a planar bottom edge about the central opening for contact with the tensioning nut. When the tensioning nut is rotated about the threaded portion of the sleeve, the tensioning nut tightens against the bottom edge portion of the domed washer thereby urging the domed head portion against the anchor plate to hold the anchor plate in positive engagement against the roof to maintain tension on the cable. The procedure for installing a cable bolt involves drilling a hole into the rock with a rotary drill, and resin anchoring of a cable bolt inserted within the bore hole. When received, a distal portion of the cable bolt is located adjacent the blind end of the hole, and a proximal portion of the cable bolt extends outwardly from the drilled hole. A resin filled cartridge is inserted into the distal end of the drilled hole before inserting the cable bolt, the cartridge usually containing a chemical resin and a catalyst to cure the resin. Insertion of the cable bolt into the drilled hole punctures the cartridge, and spinning of the bolt by rotating the drive end of the cable mixes the resin and catalyst. This anchors the distal portion of the bolt within the drilled hole.

Once the resin is set, cable bolts are then tensioned by rotating the tensioning nut by use of a rotary drill rig. While the torque provided by a rotary drill rig may in most instances result in an effective tension on the cable for rock reinforcement, in some circumstances tensions higher dian that capable of being provided by a rotary drill rig may be required to provide greater compressive forces to rock surfaces for supporting and stabilization of walls and roofs of excavation works.

One means commonly used for arriving at relatively high tensions requires use of assemblies involving hydraulic jacking means, which apply a pulling force against the drive end of the cable and tliereafter the tensioning nut tightened about the threaded sleeve of the cable bolt. While use of hydraulic assemblies can achieve high tensioning, hydraulic assemblies for tensioning often require the operator to lift the assembly above head height to be placed on the drive end of the cable. To enable this, various additional infrastructure is required to allow safe operation in close proximity to the roof. In order to avoid costs associated with assembling additional infrastructure in confined spaces such as in underground mines and civil excavation sites, operators have adopted no n -regulatory and unsafe work practices which expose workers to potential injury and workplace accidents. Hydraulic assemblies also require specialised operators, are heavy, expensive to maintain, and are usually working at high hydraulic pressures.

In an alternative method, a hollow threaded sleeve is fitted onto the distal end of the cable using an external clamp type fitting. The threaded sleeve is disposed partly within the bore and with a part thereof arranged to project from the bore . A plate is then disposed on the sleeve and a nut threadingly engaged with the sleeve to capture the plate. The nut is rotated on the sleeve such that the plate is forced onto the substrate about the bore hole. This method requires that a portion of the bore hole adjacent the opening be widened to accommodate the cylindrical sleeve. This generally requires two drilling steps, which is both time consuming and labor intensive. Attempts to apply high relative tensions to cable bolts has included use of a torque multiplier. In a conventional torque multiplier, the outside casing of the multiplier is usually engaged with internal gear teeth hence the casing would normally rotate in the opposite direction to the gear with an output shaft remaining stationary. In this condition the output shaft will not apply torque. In order to apply torque using a multiplier, a reaction arm is provided on the casing of a multiplier which is adapted to bear against a fixed, stable structure, so that rotation of the housing is prevented and the output shaft drive turns..

One attempt to achieve high tension of cable bolts using a torque multiplier underground is known to apply the reaction arm to the anchor plate, or the steel mesh layer, the roof surface about the drilled opening of the bore or even the drill rig. Attachment to the drill rig is undesirable because a drill rig is not engineered to withstand the type of reaction torque required. It has therefore been common practice to attach the reaction arm to a portion of the roof to prevent rotation of the torque multiplier housing. This practice however places heavy reliance on what roof structure is available, the stability of the roof structure, and does not take into account the possibility of alignment for uneven roof or wall surfaces.

Under high output torque such as provided by a torque multiplier, it is therefore a real probability for the reaction arm to disengage from the point of fixation on a roof structure, and rotate wildly out of control at high speeds. This is clearly undesirable because it- places the safety of a working crew at risk, and indeed such situation has been known to cause serious injuries and in some instances fatalities have occurred. It is therefore desirable to provide improved means for applying high tension to cable bolts in conditions where high tension is desirable.

A further limitation known as cable 'wind up' is faced when using a torque multiplier to apply high tension to cable bolts. For instance, for a given cable bolt type and length it is known that a cable will start to wind up or twist at a certain torque output rather than the tensioning nut being advanced up the threaded portion of the cylindrical sleeve .

It is an object of the present invention to address one or more of the foregoing problems of the prior art or at least provides a useful alternative.

A further object of the present invention is to provide a practical high tensioning assembly to help improve work safety.

The above discussion o background art is included to explain the context of the present invention. It is not to be taken as an admission that any material referred to was published, known or part of the common general knowledge in Australia or elsewhere at the priority date of any one of the claims of this specification.

Summary of the invention

In accordance with the invention there is provided an improved torque tensioning system for applying high load tension to a cable bolt of the type including a threaded sleeve, an anchor plate, a domed washer, and a tensioning nut, the system comprising:

a drive assembly including a housing and internal gearing;

a socket assembly removably mounted to the drive assembly, the socket assembly having:

an outer socket having a substantially hollow body, and

an inner socket rotatably received within the hollow body of the outer socket,

wherein the inner socket is substantially co-axially mounted within the outer socket, whereby the inner socket includes a drive receptacle for receiving the tensioning nut of the cable bolt in an operating condition, and

wherein the outer socket includes a first end having an opening for receiving the inner socket and a mounting portion about the opening, and a second opposite end having a cut-out shaped opening adjacent thereto for engaging at least a portion of the domed washer of the cable bolt in an operating condition; a drive shaft having a first mounting end adapted for rotatable mounting of an output drive of the drive assembly; and a second mounting end for drivably engaging the inner socket of the socket assembly;

a reaction structure fixedly mounted at one end thereof on a portion of the housing of the drive assembly and extending substantially co-axially with the drive shaft between a portion of the drive assembly and removably fixed to the mounting portion of the outer socket; and

wherein the cut-out shaped opening of the outer socket is adapted to engage at least a portion of the domed washer of the cable assembly so that the reaction structure is substantially prevented from rotation when the drive assembly is in an operating condition, and whereby the drive receptacle of the inner socket engages the tensioning nut of the cable bolt such that when the drive shaft is caused to rotate by the drive assembly the tensioning nut is tightened on threaded portions of the sleeve against the domed washer, which in turn bears against an anchor plate and tensions the cable.

The system of the present invention represents a substantial improvement over the prior art high tensioning devices because it does not require a reaction arm that needs to be fixed against the roof or other object. Compared to the prior art devices, the present invention provides a stable fixed or stationary point on the cable bolt assembly to which a reaction structure can be fixed while a drive assembly rotates the lock nut to urge the domed head against an anchor plate and thereby apply high tension to the cable anchored within a drilled bore hole. The present invention therefore improves safety within an underground excavation environment, and also provides a practical means of improving high tension efficiencies.

In an operating condition, the engagement between the shaped cut-out portion of the outer socket and the domed washer of the cable bolt stabilizes the drive assembly by

substantially preventing rotational movement of the housing of the drive assembly, which would otherwise render the output of the drive assembly inoperative.

The present invention significantly improves safety in underground excavation because the reaction structure of the system is stabilized by engagement with the cable bolt while the torque multiplier rotates the drive shaft hence the reaction structure reduces the potential of prior art torque multipliers to release from contact with a fixed object and cause damage. In addition, the reaction structure substantially prevents rotation of the torque multiplier housing while the output shaft of the torque multiplier rotates the drive shaft of the tensioning system, and thereby the inner socket on the lock nut, to apply high toque output resulting in high cable tensioning.

The drive assembly of the present invention can be a torque multiplier having:

a housing including torque gear means for multiplying an input torque; an input drive shaft connected to the gear means, whereby the input drive shaft is adapted for mounting a drill rig chuck for rotation;

an output drive shaft substantially in line with the input drive shaft, the output shaft being connected to the gear means for receiving output torque therefrom, and adapted for receiving the socket assembly.

The system can further includes a holding means for holding the cable in a substantially non-wind up condition so that higher relative tension can be achieved, the holding means having cooperating components on the sleeve and within the domed washer of the cable bolt for assisting in substantially preventing rotation of the cable when the drive assembly applies high torque to the drive shaft. The holding means helps to maintain the cable in a stationary (non-rotating) condition relative to the tensioning nut during winding of the tensioning nut about the threaded sleeve at high torque output. As a result, greater relative torque output can be applied to a cable and therefore substantially high cable tensioning loads can be achieved, well before the cable starts to twist. This represents an

improvement over prior art systems using a torque multiplier to apply high torque in an attempt to obtain high cable tensions.

The holding means can include:

a domed washer having a domed head portion for substantially universal angular fitment with the anchor plate, and a hex skirt extending from and about the domed head portion for receiving a corresponding shaped cut-out portion of the outer socket receptacle in an engaged condition, wherein the domed washer further includes a shaped internal void; and

a portion of the sleeve of the cable bolt assembly further including a non- threaded head section which has a shape complementary to the internal void; wherein in an assembled condition the non-threaded head section is received in non-rotalional engagement within the shaped internal void so as to

substantially minimize effect of torque on the cable and assist optimizing conversion of torque into cable tensioning.

In a further aspect of the present invention the system can include an adaptor for mounting on the housing of the torque multiplier, the adaptor having a cylindrical body and central opening therethrough for receiving the output drive shaft at one end, wherein the opposite end of the adaptor has a cut-out opening configured to receive a complimentary end of the reaction structure in an engaged condition therewith.

The system of, the invention can further include a coupler for connecting the drive shaft to the output drive shaft of the torque multiplier, the coupler having a body sized to fit within the adaptor, and wherein the body is of generally cylindrical geometry with a central opening therethrough allowing receipt of or engagement with the output drive shaft of the torque multiplier so that torque can be transferred. The coupler can further include a bore which is adapted to coincide with a corresponding bore in a connecting end of the drive shaft, wherein the connecting end of the drive shaft and coupler can be connected by a pin extending through the coincidental bores.

The system can further include a fixing plate having a central opening wherein the opening is adapted for receiving a connecting end of the drive shaft therethrough, and whereby upper and lower circumferential surface portions of the plate about the opening are fixed by attachment means to the reaction structure and a portion of the outer socket of the socket assembly respectively.

The inner socket of the socket assembly can include an open end and contiguous internal cavity for receiving therein a connecting end structure of the drive shaft. The connecting end structure of the drive shaft can include an opening and internally threaded section for receiving a complimentary fastening nut so as to transfer torque from the drive shaft to the inner socket. The inner socket further includes an -opposite open end having a shaped cutout portion forming a shaped drive receptacle for engaging and driving a correspondingly shaped tensioning nut on the cable assembly. The outer socket can include open ends and an internal cavity to receive the inner socket in an assembled condition. The outer socket further includes a shaped cut-out opening on its upper end wherein the shaped cut-out opening forms a receptacle adapted to engage a complementary portion of the domed washer so as to substantially prevent rotation of the outer socket and thereby the reaction structure. In one embodiment, the cut-out opening of the outer socket receptacle is a hex-shape for mating with the hex skirt of the domed washer.

The system of the present invention can further include a torque load indicator.

In a related aspect of the present invention there is provided an improved torque tensioning system for applying high load tension to a cable bolt of the type including a threaded sleeve, an anchor plate, a domed washer, and a tensioning nut, the system comprising: a torque multiplier having:

an output drive shaft substantially in line with the input drive shaft, the output shaft being connected_. to the gear means for receiving output torque; a drive shaft having a first mounting end adapted for rotatable mounting by the output drive shaft of the torque multiplier; and a second mounting end distal to the first mounting end a reaction structure having a first mounting end adapted for fixable attachment to the torque multiplier housing, and a second remote mounting end, the reaction structure extending substantially coaxialiy and externally of the drive shaft; a socket assembly including an outer socket having a substantially hollow body, and an inner socket rotatably received within the hollow body of the outer socket, the inner socket being substantially co-axially mounted within the outer socket, whereby the inner socket includes a drive receptacle for receiving the tensioning nut of the cable bolt in an operating condition, and wherein the outer socket includes a first open end and a mounting portion, the open end allowing receipt of the inner socket, and a second opposite end having a cut-out shaped opening for engaging at least a portion of the domed washer of the cable bolt in an operating condition, wherein the second remote end of the reaction structure is adapted for fixable mounting on the mounting portion of the outer socket; a holding means on the sleeve and the domed ball of the cable bolt for substantially preventing rotation of the cable when the torque multiplier is in operation, wherein in an operating condition the reaction structure substantially prevents rotation of the housing while the output shaft of the torque multiplier rotates the drive shaft and thereby the inner socket on the tensioning nut to apply high torque output resulting in high cable tensioning. In a further related aspect of the present invention there is provided a system for applying high load tension to a cable bolt of the type including a threaded sleeve, an anchor plate, a domed washer, and a tensioning nut, the system comprising: a housing;

a longitudinally-extending hollow member mounted on the housing in a way which substantially prevents rotation of the hollow member about its longitudinal axis relative to the housing; and

a rotatable output shaft within the hollow member and extending substantially parallel to the longitudinal axis of the hollow member.

It is preferred that the hollow member and at least a portion of the rotatable output shaft are in the form of a module which is readily detachably connectable to the housing. it is preferred that the hollow member and the rotatable output shaft are substantially coaxial.

It is preferred that the hollow member is substantially cylindrical. It is preferred that the end of the hollow member which is remote from the housing carries a coupling which is adapted to engage a stationary object.

It is preferred that the end of the drive shaft which is remote from the housing carries a coupling which is adapted to engage a rotatable object.

It is preferred that the housing comprises a socket which is adapted to receive the module which is readily detachably connectable to the housing. It is preferred that the torque multiplying ratio is in the range of 5: 1 to 2: 1 and it is particularly preferred that the torque multiplying ratio is 3: 1.

In yet a further related aspect of the present invention there is provided an improved cable bolt assembly for substantially increasing cable tension loads for a pre-determined torque input, the cable bolt including:

a cable having a plurality of closely spaced wires which have a first end adapted for fitting into a drilled hole, a second end including a drive portion adapted for engagement with an industry standard drill rig chuck or the like for installing the cable, and a cylindrical sleeve affixed thereto, wherein the sleeve includes a threaded portion and an upper head portion;

a tensioning nut adapted for threading engagement with the threaded portion of the sleeve, wherein the tensioning nut winds about the threaded portion under application of torque thereto to tension the cable;

an anchor plate adapted to bear against the roof or wall of a exposed rock surface, the plate having an opening therein for receiving the cable therethrough;

a domed washer having:

a domed head portion for angular alignment with the anchor plate about the central opening,

a skirt portion extending from the domed head portion; and

an internal void for receiving cable therethrough, the void having a shape adapted to matingly receive the upper head portion of the sleeve whereby in an assembled condition, the upper head portion of the sleeve is received within the internal void of the domed washer, and wherein torque can be applied to the tensioning nut to apply a load tension to the cable substantially without twisting the cable.

For a better understanding of the invention, and to show how it may be carried into effect, embodiments of it are shown, by way of non-limiting example only, in the accompanying drawings.

Brief description of the drawings

In the drawings:

Figure 1 is an isometric view of an embodiment of the present invention;

Figure 2 is a cross sectional view of the embodiment shown in figure 1 ;

Figure 3 is an isometric view of the embodiment shown in figure 1 with part exploded view of the system;

Figure 4 is an exploded elevation view of a portion of a cable bolt, together with some accessories which are used in the course of tensioning that bolt;

Figure 5 is an exploded cross-sectional view of a portion of figure 1;

Figure 6 is an exploded cross-sectional view of another portion of figure 1 ;

Figure 7 is a cross-sectional view illustrating the operation of an embodiment of the present invention with the cable bolt of figure 4; and

Figure 8 is a plan view from above of a dome head and outer socket assembly.

Description of preferred embodiments of the invention

Referring to figures 1 , 2 and 3 there is shown a system 1 in accordance with the present invention for applying high load tension to a cable bolt assembly 2 of the type shown in figure 4. The system 1 comprises a drive assembly, which in this embodiment is a torque multiplier 3, attached to a socket assembly 7 by a drive shaftj and a co-axially mounted reaction structure 9. As seen in figure 3, the socket assembly 7 comprises an outer hollow socket 10 and an inner socket 1 1 sized to locate within the hollow interior of the outer socket. The inner socket 1 1 is shown with its lower end received on one end of the drive shaft 8. The inner socket includes a drive receptacle end 12 comprising a shaped cut-out portion configured to engage a correspondingly shaped tensioning nut 13 (see figure 4). The outer socket is interconnected to the housing 4 of the torque multiplier 3 via a reaction structure 9, and includes a static receptacle end 17 having a shaped cut out portion configured to engage a complementary shaped skirt portion 18 of a domed washer 19 of the cable bolt assembly 16.

When the system is in an operating condition, the drive shaft 8 rotates the inner socket of the socket assembly, which in turn drives the tensioning nut 13 over a threaded portion 14 of a sleeve element 15 of the cable bolt assembly 16, thereby to urge domed head 49 of the domed washer 19 against anchor plate 20 until anchor plate 20 bites into rock ceiling 21. Further application, of torque to the tensioning nut 13 tensions the anchored cable 22 within a bore hole (not shown).

Engagement between the static receptacle 17 of the outer socket 10 and skirt portion 18 of the domed washer 19 of the cable bolt assembly provides a stable point of connection for the reaction structure 8, whereby rotation of the housing of the torque multiplier is substantially prevented without the use of an arm connecting from the housing to the roof ceiling or anchor plate. Such as static point significantly improves underground work safety because there is no support arm attachment to substrates that can potentially move. Referring to figures 5 and 6, there is shown for convenience exploded views of lower and upper assembly parts respectively of the instant system. Turning to figure 5, the lower assembly of the system 1 includes a torque multiplier 3 comprising a housing 4 which has torque-multiplying gearing (which is not illustrated in the drawings) mounted within that housing. Two axially-aligned shafts, an input drive shaft 5 and an output drive shaft 23, protrude from opposite sides of the housing 4. The input dive shaft 5 is adapted for receiving a rotary drill rig chuck (not shown).

There is shown an adaptor socket 24 which has a generally hollow, cylindrical body 25 which has a radially-projecting flange 26 protruding from its lower end. The adaptor socket 24 is mounted to the housing 4 by means of capscrews 27 which extend through longitudinally-extending bores 28 in the flange 1 1 into screw-threaded bores (which arc not illustrated in the drawings) and which are circtimferentially spaced around a side of the housing 4. The upper end of the adaptor socket 24 carries an internal cut out shaped in the form of a hex socket 29. Figure 5 shows a cylindrical reaction structure 9 and a cylindrical drive shaft 8 mounted co-axially therewithin, extending between the torque multiplier 3 and the socket assembly 7. The reaction tube 9 includes an upper flange mounting portion 30 (see figure 6) about a central opening through which the drive shaft 8 is received, and a lower end 31 having a shape which complements the hex socket 29 of the adaptor 24, so that the reaction tube 9 is constrained against rotating relative to the adaptor socket 24.

As shown in figures, a coupler 32 of cylindrical configuration and having a central opening is assembled within the adaptor socket 24, and a bushing member 33 is received within the adaptor 24 between the coupler32 and the reaction structure 9. The drive shaft 8 is a clearance fit within the reaction tube 9 in either direction. The lower end 34 of the drive shaft 8 has a bore 35 through it and adapted to fit within a portion of the central opening of the coupler 32. The bushing member 33 has inner and outer stepped diameters, forming a bearing face 36. In an assembled condition the bore 35 aligns with a bore 37 extending through the coupler 32. The drive coupler 32 is retained in place on the drive shaft 8 by a pin 38 (shown in figure 2) which passes through the bores 35 and 38. An end of the square drive coupler 32 bears against the bearing face 36 of the bushing 33 to prevent longitudinal upwards movement of the drive shaft 8 within the reaction tube 9. Turning now to figure 6, the outer socket 10 of the socket assembly 7 is mounted to the reaction tube 9 by means of capscrews 38 which extend through longitudinally-extending bores 39 in the upper flange mounting portion 30 of the reaction tube structure 9 into internal bores 40 of the outer socket 7. The lower end of the inner socket 11 has a square drive coupling 41 for receipt of an upper square end 42 of the drive shaft 8. The inner socket 1 1 is constrained in the radial direction by a radial bearing 43 and a thrust bearing 44 (in the form of a needle bearing) is located between the radial bearing 43 and lower planar surface of the inner socket 1 1. Multiple drive shafts 21 (and their component parts reaction tube 22 and drive shaft 23) can be produced, each of a different length, to suit the space constraints of the mine in which the system is to be used. Figure 4 illustrates a cable bolt assembly 16 which comprises a stranded cable 22 with a sleeve 14 which is fixedly attached to the cable anchor cable 22 by means within the sleeve (which are not illustrated in the drawing). The sleeve 15 is externally screw- threaded over a portion 14 which extends from the lower end of the sleeve 14, leaving a relatively small head portion 45 which is unthreaded and which is hex shaped in section. The sleeve 14 is also internally screw-threaded adjacent its lower end to receive a drive nut 46.

Before installation of a cable anchor into a bore hole, the cable is extended through an opening in anchor plate 20, domed washer 19, a needle bearing 47 and a thrust washer 48. The domed washer 19 includes a semi-spherical or domed head portion 49, which allows universal angular fitment to a concave portion (not shown) of the anchor plate 20, and a dependent skirt 18 of hex configuration. Referring to figure 7, the skirt portion 18 of the domed washer is shaped to be received in a static condition by the receptacle end 17 of the outer socket 10.

The system of the present invention further includes a holding means combining the domed washer and sleeve. As best seen in figure 8, the domed washer includes a shaped internal void or opening 60 therethrough adapted to receive the hex -section portion 45 of the sleeve 15, and which has a shape that is complementary to the portion 45 of that sleeve. The holding function of the dome head and hex section 45 is to assist to maintain resistance to rotation of the cable while torque is being applied to the tensioning nut 13. Hence higher torque output can be applied to the tensioning of the cable before the cable begins to wind -up.

The thrust washer 48 is in the form of a needle bearing. The shroud 47 is formed from plastics material. The shroud 47 has a radially extending portion with a portion which extends longitudinally from the periphery of the radially extending portion. The longitudinally extending portion of the shroud 47 has projections which project axially inwardly to keep the thrust washer within the shroud 47 and in contact with the radially extending portion of the shroud. The longitudinally extending portion is received within the lock nut' 13. The shroud 47 functions to keep the thrust washer 48 clean and in place. It also functions to retain any fracture products which result from damage to the thrust washer 48.

Referring to figure 7, there is shown a close up view of a top part of the system of the invention in an operating condition tensioning a cable bolt. Figure 7 shows the tensioning nut 13 is threaded onto the external screw thread section 14 of the sleeve 15. The tensioning nut 13 has a spigot 50 which projects upwards into the aperture through the thrust washer 48, to keep components of the thrust washer 48 axially aligned. The tensioning nut 13 also has a short internal screw thread (not shown), which does not extend the full length of the bore through the nut. The drive nut 46 is threaded into the internal screw thread (not shown) of the sleeve 14, retaining a washer 54 between the drive nut 46 and the lock nut 13. In installations where resin is used to adhere the far end of the stranded cable to the surrounding geology, a hex-shaped drive socket on the drilling rig is placed over the hex shaped drive nut 46 and is used to spin the cable bolt in the resin while driving the bolt forward through the resin.

To further tension the cable bolt, the upper socket assembly 10 is placed so that the hex receptacle socket 17 of the upper outer socket 10 engages the hex nut skirt 18 of the domed washer 19 and the hex drive socket 12 of the upper inner socket 1 1 engages the tensioning nut 13. The internal shaped void 60 of the domed washer 19 receives the complementary section portion 45 of the sleeve 15. The domed head 49 of the domed washer 19 engages the anchor plate 20. That is:

the outer socket 10 of the reaction tube 9 engages the hex skirt 18 extending from the domed head 49;

the internal void 60 of the domed head 49 receives the hex-section 45 of the sleeve

14.

Rotation of the drive shaft 8 by the torque multiplier 3 screws the tensioning nut 13 upwards along the thread 14 of the sleeve, and the tensioning nut 13 bears against an underside of the domed washer 19 through the bearing 47 and thrust washer 48, operating to further tension the cable bolt. The bearing and thrust washer reduces friction between the tensioning nut 13 and the domed washer 19. It is particularly preferred that the thrust washer 48 be in the form of a needle bearing. The use of a short internal thread in the tensioning nut 13 results in a lower friction between the tensioning nut and the thread 14 than there would be if the internal thread extended the full length of the tensioning nut. The engagement of the reaction tube 9 with the outer socket 10, and so with the skirl portion of the domed washer 19, and so with the sleeve 15, has the result that the reaction tube 9 and the sleeve 9 cannot rotate relative to each other. The initial tensioning of the anchor (as previously described) results in the application of compressive force by the sleeve on the domed head and on the anchor plate 20, in turn resulting in the development of frictional forces at the interface between the domed washer 19 and the anchor plate 20, and at the interface between the anchor plate 20 and the adjacent rock structure. During the process of tensioning as described above, forward thrust is applied from the drilling machine through the torque multiplier to the bolt. That thrust is transferred from the drilling machine to the housing 6, then to the flange 30 of the adaptor socket 24, then to the reaction tube 9, then to the outer socket 10, then to the domed washer 19, and through the anchor plate 20. That is, the construction is such that no forward thrus.t is transferred through the torque-multiplying gearing which is within the housing 4, so that there is no axial loading on that gearing.

While the present invention has been described with reference to a few specific embodiments, the description is illustrative of the invention and is not to be construed as limiting the invention. Various modifications may occur to those slcilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.

A reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that the referenced prior art forms part of the common general knowledge, whether in Australia or elsewhere.

Throughout this specification, the words "comprise", "comprised", "comprising" and "comprises" are to be taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. In the claims, each dependent claim is to be read as being within the scope of its parent claim or claims, in the sense that a dependent claim is not to be interpreted as infringed unless its parent claims are also infringed.

Claims

The claims defining the invention are as follows:

1. An improved torque tensioning system for applying high load tension to a cable bolt of the type including a threaded sleeve, an anchor plate, a domed washer, and a tensioning nut, the system comprising:

, a drive assembly including a housing and internal gearing;

an outer socket having a substantially hollow body, and

an inner socket rotatably received within the hollow body of the outer socket,

wherein the outer socket includes a first end having an opening for receiving the inner socket and a mounting portion about the opening, and a second opposite end having a cut-out shaped opening adjacent thereto for engaging at least a portion of the domed washer of the cable bolt in an operating condition;

a drive shaft having a first mounting end adapted for rotatable mounting of an output drive of the drive assembly; and a second mounting end for drivably engaging the inner socket of the socket assembly;

2. An improved torque tensioning system for applying high load tension to a cable bolt according to claim 1 wherein the drive assembly of the present invention is a torque multiplier having:

3. An improved torque tensioning system for applying high load tension to a cable bolt according to claim 1 further including a holding means comprising complementary mating components on the sleeve and the domed washer of the cable bolt assembly for assisting in substantially preventing rotation of the cable when the drive assembly rotates the drive shaft and tensions the cable.

4. An improved torque tensioning system for applying high load tension to a cable bolt according to claim 3 wherein the holding means includes:

a domed washer having a domed head portion for substantially universal angular fitment with the anchor plate, and a dependent skirt extending from and about the domed head portion for receiving a corresponding shaped cut-out portion of the outer socket receptacle in an engaged condition, wherein the domed washer further includes a shaped internal void; and

a portion of the sleeve of the cable bolt assembly further including a non- threaded head section which has a shape complementary to the internal void;

wherein in an assembled condition the non-threaded head section is received in non-rotational engagement within the shaped internal void so as to

substantially prevent wind up of the cable under application of high torque.

5. An improved torque tensioning system for applying high load tension to a cable bolt according to claim 1 further including an adaptor for mounting on the housing of the torque multiplier, the adaptor having a cylindrical body and central opening therethrough for receiving the output drive shaft at one end, wherein the opposite end of the adaptor has a cut-out opening configured to receive a complimentary end of the reaction structure in an engaged condition therewith.

6. An improved torque tensioning system for applying high load tension to a cable bolt according to claim 5 further including a coupler for connecting the drive shaft to the output drive shaft of the torque multiplier, the coupler having a body sized to fit within the adaptor, and wherein the body is of generally cylindrical geometry with a central opening therethrough allowing receipt of or engagement with the output drive shaft of the torque multiplier so that torque can be transferred.

7. An improved torque tensioning system for applying high load tension to a cable bolt according to claim 6 wherein the coupler further includes a bore which is adapted to coincide with a corresponding bore in a connecting end of the drive shaft, wherein the connecting end of the drive shaft and coupler can be connected by a pin extending through the coincidental bores.

8. An improved torque tensioning system for applying high load tension to a cable bolt according to claim 1 wherein the reaction structure include a mounting plate extending circumferentially about its upper open end, whereby fastening means secures the mounting plate to a lower end portion of the outer socket of the socket assembly.

9. An improved torque tensioning system for applying high load tension to a cable bolt according to claim 1 wherein the inner socket of the socket assembly includes an open end and contiguous internal cavity for receiving therein a connecting end structure of the drive shaft, whereby the connecting end structure of the drive shaft includes an opening and internally threaded section for receiving a complimentary fastening nut so as to transfer torque from the drive shaft to the inner socket.

10. An improved torque tensioning system for applying high load tension to a cable bolt according to claim 9 wherein the inner socket further includes an opposite open end having a shaped cut-out portion forming a shaped drive receptacle for engaging and driving a correspondingly shaped tensioning nut on the cable assembly.

1 1.An improved torque tensioning system for applying high load tension to a cable bolt according to claim 1 wherein the outer socket includes open ends and an internal cavity to receive the inner socket in an assembled condition, and whereby the outer socket further includes a shaped cut-out opening on its upper end wherein the shaped cut-out opening forms a receptacle adapted to engage a complementary portion of the domed washer so as to substantially prevent rotation of the outer socket and thereby the reaction structure.

12. An improved torque tensioning system for applying high load tension to a cable bolt according to claim 1 wherein the system of the present invention further includes a torque load indicator.

13. An improved torque tensioning system for applying high load tension to a cable bolt of the type including a threaded sleeve, an anchor plate, a domed washer, and a tensioning nut, the system comprising: a torque multiplier having:

an output drive shaft substantially in line with the input drive shaft, the output shaft being connected to the gear means for receiving output torque; a drive shaft having a first mounting end adapted for rotatable mounting by the output drive shaft of the torque multiplier; and a second mounting end distal to the first mounting end a reaction structure having a first mounting end adapted for fixable attachment to the torque multiplier housing, and a second remote mounting end, the reaction structure extending substantially coaxially and externally of the drive shaft; a socket assembly including an outer socket having a substantially hollow body, and an inner socket rotatably received within the hollow body of the outer socket, the inner socket being substantially co-axially mounted within the outer socket, whereby the inner socket includes a drive receptacle for receiving the tensioning nut of the cable bolt in an operating condition, and wherein the outer socket includes a first open end and a mounting portion, the open end allowing receipt of the inner socket, and a second opposite end having a cut-out shaped opening for engaging at least a portion of the domed washer of the cable bolt in an operating condition, wherein the second remote end of the reaction structure is adapted for fixable mounting on the mounting portion of the outer socket; a holding means on the sleeve and the domed ball of the cable bolt for substantially preventing rotation of the cable when the torque multiplier is in operation, wherein in an operating condition the reaction structure substantially prevents rotation of the housing while the output shaft of the torque multiplier rotates the drive shaft and thereby the inner socket on the tensioning nut to apply high torque output resulting in high cable tensioning.

14. A system for applying high load tension to a cable bolt of the type including a threaded sleeve, an anchor plate, a domed washer, and a tensioning nut, the system comprising: a torque multiplier comprising:

an output drive shaft substantially in line with the input drive shaft, the output shaft being connected to the gear means for receiving output torque; a longitudinally-extending hollow member mounted on the housing in a way which substantially prevents rotation of the hollow member about its longitudinal axis relative to the housing; and a rotatable output shaft within the hollow member and extending substantially parallel to the longitudinal axis of the hollow member.

15. A system as claimed in claim 14, in which the hollow member and at least a portion of the rotatable output shaft are in the form of a module which is readily detachably connectable to the housing.

16. A system as claimed in any one of claims 14 or 15, in which the hollow member and the rotatable output shaft are substantially coaxial.

17. A system as claimed in any one of claims 14 to 16, in which the hollow member is substantially cylindrical.

18. A system as claimed in any one of claims 14 to 17, in which the end of the hollow member which is remote from the housing carries a coupling which is adapted to engage a stationary object.

19. A system as claimed in any one of claims 14 to 18, in which the end of the drive shaft which is remote from the housing carries a coupling which is adapted to engage a rotatable object.

20. A system as claimed in any one of claims 15 to 19 in which the housing comprises a socket which is adapted to receive the module which is readily detachably connectable to the housing.

21. A system as claimed in any one of the preceding claims, in which the torque

multiplying ratio is in the range of 5: 1 to 2: 1.

22. A system as claimed in claim 21, in which the torque multiplying ratio is 3: 1.

23. An improved cable bolt assembly for substantially increasing cable tension loads for a pre-determined torque input, the cable bolt including:

a cable having a plurality of closely spaced wires which have a first end adapted for fitting into a drilled hole, a second end 'including a drive portion adapted for engagement with an industry standard drill rig chuck or the like for installing the cable, and a cylindrical sleeve affixed thereto, wherein the sleeve includes a threaded portion and an upper head portion; a tensioning nut adapted for threading engagement with the threaded portion of the sleeve, wherein the tensioning nut winds about the threaded portion under application of torque thereto to tension the cable;

a domed washer having:

a skirt portion extending from the domed head portion; and