GB2603924A - Apparatus and method for tensioning a mechanical member - Google Patents

Abstract

The apparatus 10 includes a fluid-powered tensioner arrangement comprising a housing 14 and a chamber 18 for receiving a pressurised fluid 28. The fluid comprises or takes the form of a curable material. A piston member 16 is axially movable relative to the housing. The piston member forms part of, is configured for coupling to, or is configured to engage the mechanical member 12 to be tensioned. Movement of the piston member relative to the housing transmits a tensile load force L to the mechanical member, to induce strain in the member. A fluid delivery arrangement 30 delivers the curable material to the chamber. When the curable material cures, the strain induced in the mechanical member is locked-in. The tensioner arrangement may be hydraulic. The curable material may be a resin, a resin and a hardener, or a grout material. The apparatus may include more than one piston. A piston rod may be at least partially formed by the mechanical member. A method for tensioning a mechanical member includes applying a tensile load force using a fluid-powered tensioner to induce strain in the mechanical member, delivering a pressurised fluid of curable material, and curing the material to lock-in the strain.

Description

APPARATUS AND METHOD FOR TENSIONING A MECHANICAL MEMBER

FIELD

This relates to an apparatus and method for tensioning a mechanical member, in particular but not exclusively an apparatus and method for tensioning a mechanical fastener such as a bolt, stud, tie-rod or the like.

BACKGROUND

Mechanical members are utilised in a vast array of applications and in a wide variety of industries. Typical examples of such mechanical members include mechanical fasteners, with bolts, studs, and tie-bars being particularly common examples. Other examples of mechanical members include cables used to secure and/or stabilise structures.

In many applications, particularly those of a safety critical nature, the mechanical members are tensioned to a prescribed load or to prescribed strain. In the case of mechanical fasteners, for example, tensioning ensures that the coupling between the mating faces of the components to be coupled is maintained. The tension applied to the fasteners is typically selected to be in excess of the expected separation force acting on the mating faces in use, and provides a greater degree of confidence that the coupling will function as expected.

There are a number of different methods for applying tension to mechanical members. One method of applying tension to mechanical fasteners such as bolts or studs involves the use of a tensioner device (also known as a bolt or stud tensioner), whereby a hydraulic cylinder is used to apply tension to the mechanical fastener to induce stretching of the fastener. A mechanical retainer, typically in the form of a nut, is then located on the stretched fastener, the nut maintaining the strain when the hydraulic load is removed. The tensioner device is then removed. In an alternative tensioner device, often known as a hydraulic nut, the hydraulic cylinder and the nut form a single assembly. Whereas bolt or stud tensioners are removed after use, the hydraulic nut remains in place, forming a permanent installation.

Despite their widespread use, conventional tensioner devices and techniques nevertheless involve a number of drawbacks For example, conventional tensioner devices and techniques require that personnel work in the vicinity of the strained mechanical members. In the case of mechanical fasteners, it is common for the fastener to be tensioned to 90% of its yield.

As a result, the stored energy contained within the fastener represents a significant, potentially fatal, risk to personnel handling and/or operating in the immediate environment should the fastener fail.

Moreover, spinning up the retainer, e.g. nut, used to maintain the strain after the hydraulic load is removed requires operator skill and dexterity. In remote and/or hazardous environments such as those that arise in industries that operate in nuclear, subsea, mining and space settings and the like, where manual access is restricted or prohibited, the nut needs to be driven and thus requires additional equipment such as a power source and a motor. Furthermore, in order for the operator to know that the nut has been positioned correctly, sensing equipment such as load transducers, position transducers, contact switches and the like are required. Each of the above factors represents increased cost and complexity, and increases the likelihood of error.

Another drawback with conventional tools and methodologies is that some of the applied tension, and thereby strain, in the mechanical member is inevitably lost as the load is transferred from the hydraulic fluid onto the mechanical retainer, e.g. nut. Thus, an allowance must be made which accounts for expected load losses when the hydraulic oil is bled off and the spun-up nut takes on the load, this being known as the Load Transfer Factor. Although based on calculations, the Load Transfer Factor is in effect an estimate of the expected losses and thus does not result in an accurate representation of the actual tension remaining in the mechanical member.

Once the mechanical member is fully loaded and the mechanical retainer, typically a nut, is in place then some risk remains where cyclic loading or vibration is present. Cyclic loading and vibration can, over time, cause such a mechanical retainer to move in such a way as to diminish the original load or strain established in the mechanical member.

SUMMARY

Aspects of the present disclosure relate to an apparatus and method for tensioning a mechanical member, in particular but not exclusively a fastener such as a bolt, stud, tie-rod or the like.

According to a first aspect, there is provided an apparatus for tensioning a mechanical member, the apparatus comprising: a fluid-powered tensioner arrangement comprising: a housing; a chamber for receiving a pressurised fluid comprising or taking the form of a curable material; and a piston member axially movable relative to the housing, wherein the piston member forms part of, is configured for coupling to, or is configured to engage the mechanical member to be tensioned, and wherein movement of the piston member relative to the housing transmits a tensile load force to the mechanical member so as to induce strain in the mechanical member; a fluid delivery arrangement for delivering the curable material to the chamber, such that when the curable material cures the strain induced in the mechanical member is locked-in.

In use, the apparatus may be configured for location on a given mechanical member to be tensioned. Pressurised fluid in the form of a curable material, for example but not exclusively a liquid plastic compound may be supplied to the chamber, the pressurised fluid generating the pressure force in the chamber which is transmitted to the mechanical member so as to apply the tensile load force to the fastener, and thereby induce strain in the mechanical member. The pressure in the chamber and thus the tensile load force on the mechanical member is maintained until the curable material cures, i.e., changes from a liquid phase to a solid phase. The curable material, when cured, locks-in the strain in the mechanical member.

The apparatus provides a number of significant benefits over conventional tools and equipment. For example, the apparatus eliminates the requirement for a secondary, mechanical, device to retain the strain. Accordingly, the apparatus can be operated remotely or otherwise from distance, thereby reducing or eliminating the risk to personnel due to release of the stored energy in the mechanical member in the event of failure.

Moreover, the ability of the apparatus to be operated remotely or otherwise from distance facilitates operations in remote and/or hazardous environments such as those that arise in industries that operate in nuclear, subsea, mining and space settings, and the like, where manual access is restricted or prohibited.

Furthermore, the ability of the apparatus to maintain and lock-in the strain in the mechanical member, without the losses which may otherwise occur with conventional tensioner devices and methodologies when the hydraulic oil is bled off and the spun-up retainer, e.g. nut, takes on the load, obviates the requirement for a Load Transfer Factor.

Furthermore, the elimination of the secondary, mechanical, device (typically a nut) to retain the strain consequently eliminates the risk that that device will diminish the load or strain in the mechanical member over time due to exposure to cyclic loading or vibration. The adhesion and keying properties of the cured fluid additionally secures against any movement between the mechanical member and the apparatus.

The mechanical member may take a variety of different forms. For example, the mechanical member may comprise or take the form of a mechanical fastener. The mechanical fastener may comprise or take the form of a threaded mechanical fastener. The mechanical fastener may comprise a bolt, stud, screw, tie-rod or the like. Alternatively, the mechanical member may comprise a cable or the like, such as may be used to secure a structure As described above, the apparatus comprises a fluid-powered tensioner arrangement. In particular, the tensioner arrangement may comprise or take the form of a hydraulic tensioner arrangement.

The housing may comprise or take the form of a piston housing. The housing may be configured for location on the mechanical member. The housing may be disposed on the mechanical member. The housing may be configured for location on and/or around a portion of the mechanical member. The housing may comprise or define a throughbore through which the mechanical member may be disposed.

The piston member may be at least partially disposed within the housing. The apparatus may comprise a single piston member. Alternatively, the apparatus may comprise a plurality of piston members.

The apparatus may comprise a piston rod. The piston rod may form part of the tensioner arrangement of the apparatus. The piston rod may be at least partially formed by the mechanical member to be tensioned. The piston rod may be coupled to the mechanical member to be tensioned. The piston rod may be integrally formed with the piston member. Alternatively, the piston rod may be coupled to the piston member.

The apparatus may comprise a coupling arrangement for coupling the apparatus to the mechanical member.

The coupling arrangement may comprise or take the form of a threaded coupling arrangement.

The piston member may be configured for coupling to the mechanical member. The piston member may comprise a coupling profile for coupling to the mechanical member. The coupling profile may be formed or otherwise provided on an inner circumferential surface of the piston member.

Where the mechanical member comprises a threaded portion, the coupling profile of the piston member may comprise a threaded portion. The piston member may thus be considered or define a nut.

The threaded portion of the piston member and the threaded portion of the mechanical member may together form or form part of the coupling arrangement of the apparatus.

The piston rod may be configured for coupling to the mechanical member. The piston rod may comprise a coupling profile for coupling to the mechanical member. The coupling profile may be formed or otherwise provided on an inner circumferential surface of the piston rod.

Where the mechanical member comprises a threaded portion, the coupling profile of the piston rod may comprise a threaded portion. The piston rod may thus be considered or define a nut.

As described above, the tensioner arrangement comprises a chamber. The chamber may comprise or take the form of a piston chamber. The piston chamber may be interposed between the housing and the piston member.

The apparatus may comprise, or may be coupled to, a source of the curable material ("curable material source").

The chamber may be coupled to the curable material source by one or more fluid conduits. At least one of the fluid conduits may comprise or take the form of tubing or a hydraulic hose. The one or more fluid conduits for coupling the curable material source to the chamber may form part of the delivery arrangement.

The chamber may define a first chamber portion configured for coupling to and/or to fluidly communicate with the curable material source.

The first chamber portion may be coupled to the curable material source by one or more fluid conduits. At least one of the fluid conduits may comprise or take the form of tubing or a hydraulic hose.

The chamber may define a second chamber portion. The second chamber portion may be configured to receive a second pressurised fluid, e.g. a hydraulic fluid such as hydraulic oil.

The apparatus may comprise, or may be coupled to, a source of the second pressurised fluid ("second pressurised fluid source"). The second chamber portion may be coupled to and/or fluidly communicate with the second pressurised fluid source. The second pressurised fluid source may comprise or take the form of a reservoir suitable for storing the second pressurised fluid. The source may comprise an accumulator or other fluid reservoir suitable for storing the second pressurised fluid.

The second chamber portion may be coupled to the second pressurised fluid source by one or more fluid conduits. At least one of the fluid conduits may comprise or take the form of tubing or a hydraulic hose.

However, it will be understood that the apparatus may be configured so that the first chamber portion receives the second pressurised fluid and/or the apparatus may be configured so that the second chamber portion receives the curable material.

The apparatus may comprise a shuttle. The shuttle may be disposed within the chamber. The shuttle may divide the chamber into the first chamber portion and the second chamber portion.

As described above, the apparatus comprises a fluid delivery arrangement for delivering the curable material to the chamber, such that when the curable material cures the strain induced in the mechanical member is locked-in.

The fluid delivery arrangement may comprise or may be coupled to the source of curable material. The source of curable material or its components may comprise or take the form of a reservoir. The source of curable material or its components may comprise or take the form of an accumulator.

The curable material may comprise a resin. The curable material may comprise a setting agent, e.g. a hardener. The curable material may comprise liquid plastic resin. The curable material may comprise polyurethane resin. The curable material may comprise polyester resin.

In some instances, the resin may be present in the chamber and the setting agent, e.g. hardener, directed to the chamber so as to cure the resin. In other instances, the setting agent may be present in the chamber and the resin directed to the chamber, the resin curing in the chamber. In some instances, the resin and setting agent will be combined external to the chamber and subsequently directed to the chamber.

The curable material may comprise or take the form of a grout material, or other fluid which is capable of curing through chemical reaction within the fluid and/or through the action of a curing means, such as the application of heat and/or radiation.

The apparatus may comprise or may be coupled to a second fluid delivery arrangement for delivering the second pressurised fluid to the chamber. The second fluid delivery arrangement may comprise or take the form of a hydraulic power pack.

However, it will be understood that any suitable means for delivering the second pressurised fluid may be utilised.

The pressurised fluid may comprise or take the form of a power fluid. The pressurised fluid may comprise or take the form of hydraulic fluid, such as hydraulic oil or the like Where the chamber is divided into a first chamber portion and a second chamber portion then one chamber portion will be coupled to the curable material source by one or more fluid conduits and the remaining chamber will be coupled to the second pressurised fluid source by one or more fluid conduits.

The fluid delivery arrangement may comprise a pump. The pump may comprise or take the form of a positive displacement pump.

The fluid delivery arrangement may comprise a positive displacement from pressurised reservoirs or accumulators. That positive displacement driving pressure or accumulator charging may be under the action of a pump.

The apparatus may comprise an arrangement for regulating the pressure in the chamber. The apparatus may comprise or may be coupled to a pressure relief valve, a reducing valve or any such arrangement that serves a pressure-control function.

According to a second aspect, there is provided a method for tensioning a mechanical member, the method comprising: applying a tensile load force to a mechanical member using a fluid-powered tensioner arrangement so as to induce strain in the mechanical member to be tensioned; delivering a pressurised fluid comprising or taking the form of a curable material to a chamber of the fluid-powered tensioner arrangement; and curing the curable material to lock-in the strain in the mechanical member.

The fluid-powered tensioner may comprise: a housing; the chamber for receiving the pressurised fluid in the form of the curable material; and a piston member axially movable relative to the housing, wherein the piston member forms part of, is configured for coupling to, or is configured to engage the mechanical member to be tensioned, and wherein movement of the piston member relative to the housing transmits a tensile load force to the mechanical member so as to induce strain in the mechanical member.

The method provides a number of significant benefits over conventional techniques. For example, the method eliminates the requirement for a secondary, mechanical, device to retain the strain. Accordingly, the method can be operated remotely or otherwise from distance, thereby reducing or eliminating the risk to personnel due to release of the stored energy in the mechanical member in the event of failure.

Moreover, the ability of the method to be operated remotely or otherwise from distance facilitates operations in remote and/or hazardous environments such as those that arise in industries that operate in nuclear, subsea, mining and space settings, and the like, where manual access is restricted or prohibited.

Furthermore, the ability of the method to maintain and lock-in the strain in the mechanical member, without the losses which may otherwise occur with conventional tensioner devices and methodologies when the hydraulic oil is bled off and the secondary mechanical retainer device, e.g. nut, takes on the load, obviates the requirement for a Load Transfer Factor.

Furthermore, the elimination of the secondary, mechanical retainer device (typically a nut) consequently eliminates the risk that that device will diminish the load or strain in the mechanical member over time due to exposure to cyclic loading or vibration. The adhesion and keying properties of the cured fluid additionally secures against any movement between the mechanical member and the apparatus.

The mechanical member may take a variety of different forms. For example, the mechanical member may comprise or take the form of a mechanical fastener. The mechanical fastener may comprise or take the form of a threaded mechanical fastener. The mechanical fastener may comprise a bolt, stud, screw, tie-rod or the like.

Alternatively, the mechanical member may comprise a cable or the like, such as may be used to secure and/or stabilise a structure.

The invention is defined by the appended claims. However, for the purposes of the present disclosure it will be understood that any of the features defined above or described below may be utilised in isolation or in combination. For example, features described above in relation to one of the above aspects or below in relation to the detailed description may be utilised in any other aspect, or together form a new aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects will now be described, by way of example only, with reference to the accompanying drawings, in which: Figures 1A and 1B show diagrammatic views of an apparatus for tensioning a mechanical member; Figures 2A and 2B show diagrammatic views of an alternative apparatus for tensioning a mechanical member; Figures 3A and 3B show diagrammatic views of an alternative apparatus for tensioning a mechanical member; Figures 4A, 4B and 4C show diagrammatic views of an alternative apparatus for tensioning a mechanical member; Figures 5A and 5B show diagrammatic views of an alternative apparatus for tensioning a mechanical member; Figures 6A and 6B show diagrammatic views of an alternative apparatus for tensioning a mechanical member; Figure 7 shows a fluid delivery arrangement for use in one or more of the apparatus shown in Figures 1 to 6; and Figure 8 shows another fluid delivery arrangement for use in one or more of the apparatus shown in Figures 1 to 6.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring first to Figure 1 of the accompanying drawings, there is shown a diagrammatic view of an apparatus 10 for tensioning a mechanical member 12.

In use, the apparatus 10 is configured to apply a tensile force L to the mechanical member 12, the tensile load force L inducing a strain in the mechanical member 12. The strain in the mechanical member 12 is then locked-in as will be described further below.

As shown in Figure 1, the apparatus 10 comprises a housing 14 and a piston member 16 disposed within the housing 14. A chamber 18 is disposed between the housing 14 and the piston member 16.

An annular seal element 20 is disposed in an annular groove 22 in the piston member 16. The seal element 20 prevents leakage of fluid between the piston member 16 and the housing 14.

In the apparatus 10 illustrated in Figure 1, the mechanical member 12 is integrally formed with the apparatus 10, the mechanical member 12 forming a piston rod of the apparatus 10.

An annular seal element 24 is disposed in an annular groove 26 in the housing 14. The seal element 24 prevents leakage of fluid between the mechanical member 12 and the housing 14.

It will be recognised that the annular seal elements 20, 24 and the annular grooves 22,26 can be sited otherwise than as illustrated in Figure 1 and still serve the function described above.

The chamber 18 communicates with a source 28 of curable material, which in the illustrated apparatus 10 takes the form of a mixture of liquid plastic resin and a hardener in a liquid state. The source 28 of curable material communicates with the chamber 18 via a fluid conduit 30, which in the illustrated apparatus 10 takes the form of a hydraulic hose.

The housing 14, piston member 16 and chamber 18 form a fluid-powered tensioner arrangement of the apparatus 10, wherein the curable material directed from the source 28 to the chamber 18 via the fluid conduit 30 generates a pressure force on the piston member 16 which is transmitted to the mechanical member 12 so as to apply the tensile force L to the mechanical member 12, and thereby induce strain in the mechanical member 12. The strain in the mechanical member 12 is then locked-in by curing the curable material, i.e. the curable material transitioning from its liquid state to its solid state.

As shown in Figure 1, the chamber 18 has an inlet A and an outlet B, and in use some of the curable material is flushed through the chamber 18. The apparatus 10 is configured so that piston member 16 cannot stroke while the chamber 18 is flushed. Once flushing has been effected, the outlet B is closed such that the pressure can build until the piston member 16 starts to stroke and the tensile load force L comes onto the mechanical member 12. The chamber 18 is filled with the curable material at a preselected pressure required to generate the desired load force L and strain in the mechanical member 12.

The apparatus 10 can be configured without the outlet B. Any fluid resident in the apparatus 10 before the curable material is delivered from source 28 will amalgamate with the curable material within the piston chamber 18.

The apparatus 10 provides a number of significant benefits over conventional tools and equipment. For example, the apparatus 10 eliminates the requirement for a secondary, mechanical, device to retain the strain in the mechanical member 12.

Accordingly, the apparatus 10 can be operated remotely or otherwise from distance, thereby reducing or eliminating the risk to personnel due to release of the stored energy in the mechanical member 12 in the event of failure.

Moreover, the ability of the apparatus 10 to be operated remotely or otherwise from distance facilitates operations in remote and/or hazardous environments such as those that arise in industries that operate in nuclear, subsea, mining and space settings, and the like, where manual access is restricted or prohibited.

Furthermore, the ability of the apparatus 10 to maintain and lock-in the strain in the mechanical member 12, without the losses which may otherwise occur with conventional tensioner devices and methodologies when the hydraulic oil is bled off and the secondary mechanical retainer device, e.g. nut, takes on the load, obviates the requirement for a Load Transfer Factor.

Furthermore, the elimination of the secondary, mechanical retainer device (typically a nut) consequently eliminates the risk that that device will diminish the load or strain in the mechanical member over time due to exposure to cyclic loading or vibration. The adhesion and keying properties of the cured fluid additionally secures against any movement between the mechanical member and the apparatus.

The mechanical member 12 may take a variety of different forms. For example, in the illustrated apparatus 10 the mechanical member 12 takes the form of a mechanical fastener, more specifically a tie-rod. However, it will be understood that the mechanical member may alternatively comprise or take the form of a different mechanical fastener such as a bolt, stud or the like, or may comprise a cable or the like, such as may be used to secure and/or stabilise a structure.

Referring now to Figure 2 of the accompanying drawings, there is shown an alternative apparatus 110 for tensioning a mechanical member 112.

As in the apparatus 10 described above, the apparatus 110 is configured to apply a tensile load force L to a mechanical member 112, the tensile load force L inducing a strain in the mechanical member 112. The strain in the mechanical member 112 is then locked-in.

As shown in Figure 2, the apparatus 110 comprises a housing 114 and a piston member 116 disposed within the housing 114. A chamber 118 is disposed between the housing 114 and the piston member 116.

An annular seal element 120 is disposed in an annular groove 122 in the piston member 116. The seal element 120 prevents leakage of fluid between the piston member 116 and the housing 114.

In contrast to the apparatus 10 in which the mechanical member 12 forms a piston rod of the apparatus 10, in the apparatus 110 illustrated in Figure 2 the apparatus 110 comprises piston rod 123 which is integrally formed with the piston member 116.

An annular seal element 124 is disposed in an annular groove 126 in the piston rod 123. The seal element 124 prevents leakage of fluid between the piston rod 123 and the housing 114.

It will be recognised that the annular seal elements 120 & 124 and the annular grooves 122 & 126 can be sited otherwise than as illustrated in Figure 2 and still serve the function described above.

The chamber 118 communicates with a source 128 of curable material, which in the illustrated apparatus 110 takes the form of a mixture of liquid plastic resin and hardener in a liquid state. The source 128 of curable material communicates with the chamber 118 via a fluid conduit 130, which in the illustrated apparatus 110 takes the form of a hydraulic hose.

The housing 114, piston member 116 and chamber 118 form a fluid-powered tensioner arrangement of the apparatus 110, wherein the curable material directed from the source 128 to the chamber 118 via the fluid conduit 130 generates a pressure force on the piston member 116 which is transmitted to the mechanical member 112 so as to apply the tensile load force L to the mechanical member 112, and thereby induce strain in the mechanical member 112. The strain in the mechanical member 112 is then locked-in by curing the curable material, i.e. the curable material transifioning from its liquid state to its solid state.

As shown in Figure 2, the chamber 118 has an inlet A and an outlet B, and in use some of the curable material is flushed through the chamber 118. The apparatus 110 is configured so that piston member 116 cannot stroke while the chamber 118 is flushed.

Once flushing has been effected, the outlet B is closed such that the pressure can build until the piston member 116 starts to stroke and the tensile load force L comes onto the mechanical member 112. The chamber 118 is filled with the curable material at a preselected pressure required to generate the desired load force L and strain in the mechanical member 112.

The apparatus 110 can be configured without the outlet B. Any fluid resident in the apparatus 110 before the curable material is delivered from source 128 will amalgamate with the curable material within the piston chamber 118.

The apparatus 110 comprises a coupling arrangement, generally denoted 132, for coupling the apparatus 110 to the mechanical member 112. In the illustrated apparatus 110, the coupling arrangement 132 takes the form of a thread connection between a thread profile 136 on the mechanical member 112 and a thread profile 134 on the piston rod 123.

It will be recognised, however, that the coupling arrangement 132 may take any suitable form. For example, the thread profiles 134, 136 may alternatively or additionally be formed between the piston member 116 and the mechanical member 112. The coupling arrangement 132 may alternatively or additionally comprise or take the form of means for attachment other than a threaded coupling.

Referring now to Figure 3 of the accompanying drawings, there is shown an alternative apparatus 210 for tensioning a mechanical member 212.

As in the apparatus 10,110 described above, the apparatus 210 is configured to apply a tensile load force L to a mechanical member 212, the tensile load force L inducing a strain in the mechanical member 212. The strain in the mechanical member 212 is then locked-in.

As shown in Figure 3, the apparatus 210 comprises a housing 214 and a piston member 216 disposed within the housing 214. A chamber 218 is disposed between the housing 214 and the piston member 216.

In the apparatus 210 shown in Figure 3, the housing 214 is annular, having a throughbore 238 that facilitates location of the apparatus 210 around the mechanical member 212. The apparatus 210 comprises a single annular piston member 216. However, it will be recognised that in some instances the apparatus 210 may alternatively comprise a plurality of cylindrical piston members 216 arrayed around the annular housing in a plurality of chambers.

Annular seal elements 220 are disposed in annular grooves 222 in the outer face of piston members 216. The seal elements 220 prevent leakage of fluid between the piston members 216 and the housing 214.

Annular seal elements 224 are disposed in annular grooves 226 in the inner face of piston member 216. The seal elements 224 prevent leakage of fluid between the piston members 216 and the housing 214.

It will be recognised that the annular seal elements 220 & 224 and the annular grooves 222 & 226 can be sited otherwise than as illustrated in Figure 3 and still serve the function described above.

In contrast to the apparatus 110, the apparatus 210 illustrated in Figure 3 comprises a member 239 which engages the piston members 216 in order to facilitate the transmission of the tensile load force L from the apparatus 210 to the mechanical member 212. In the illustrated apparatus 210, the member 239 is separate from and is coupled to the mechanical member 212 by a coupling arrangement, generally denoted 240. In the illustrated apparatus 210, the coupling arrangement 240 takes the form of a thread connection between a thread profile 242 on the mechanical member 212 and a thread profile 244 on the member 239.

It will be recognised, however, that the coupling arrangement 240 may take any suitable form. For example, the coupling arrangement 240 may alternatively or additionally comprise or take the form of means for attachment other than a threaded coupling.

Alternatively, the member 239 may be integrally formed with the mechanical member 212.

The chamber 218 communicates with a source 228 of curable material, which in the illustrated apparatus 210 takes the form of a mixture of liquid plastic resin and a hardener in a liquid state. The source 228 of curable material communicates with the chamber 218 via a fluid conduit 230, which in the illustrated apparatus 210 takes the form of a hydraulic hose.

The housing 214, piston members 216 and chamber 218 form a fluid-powered tensioner arrangement of the apparatus 210, wherein the curable material directed from the source 228 to the chamber 218 via the fluid conduit 230 generates a pressure force on the piston members 216 which is transmitted to the mechanical member 212 so as to apply the tensile load force L to the mechanical member 212, and thereby induce strain in the mechanical member 212. The strain in the mechanical member 212 is then locked-in by curing the curable material, i.e. the curable material transitioning from its liquid state to its solid state.

As shown in Figure 3, the chamber 218 has an inlet A and an outlet B, and in use some of the curable material is flushed through the chamber 218. The apparatus 210 is configured so that piston member 216 cannot stroke while the chamber 218 is flushed.

Once flushing has been effected, the outlet B is closed such that the pressure can build until the piston member 216 starts to stroke and the tensile load force [comes onto the mechanical member 212. The chamber 218 is filled with the curable material at a preselected pressure required to generate the desired load force L and strain in the mechanical member 212.

The apparatus 210 can be configured without the outlet B. Any fluid resident in the apparatus 210 before the curable material is delivered from source 228 will amalgamate with the curable material within the piston chamber 218.

It will be understood that various modifications may be made without departing from the scope of the claimed invention.

Figure 4 of the accompanying drawings show diagrammatic views of an apparatus 310 for tensioning a mechanical member 312.

As in the apparatus 10, described above, the apparatus 310 is configured to apply a tensile load force L to a mechanical member 312, the tensile load force [inducing a strain in the mechanical member 312. The strain in the mechanical member 312 is then locked-in.

As shown in Figure 4, the apparatus 310 comprises a housing 314 and a piston member 316 disposed within the housing 314. A piston chamber 318 is disposed between the housing 314 and the piston member 316.

A shuttle 346 is disposed in the piston chamber 318. The shuttle 346 divides the piston chamber 318 into a first chamber portion 348 and a second chamber portion 350.

The first chamber portion 348 communicates with a source 328 of curable material, which in the illustrated apparatus 310 takes the form of a mixture of liquid plastic resin and a hardener in a liquid state. The source 328 of curable material communicates with the first chamber portion 348 via a fluid conduit 330, which in the illustrated apparatus 310 takes the form of a hydraulic hose.

The second chamber portion 350 communicates with a source 352 of a second pressurised fluid via fluid conduit 354. In the illustrated apparatus 310, the second pressurised fluid is hydraulic fluid, more specifically hydraulic oil, and the fluid conduit 354 takes the form of a hydraulic hose.

In the apparatus 310 illustrated in Figure 4, the mechanical member 312 is integrally formed with the apparatus 310, the mechanical member 312 forming a piston rod of the apparatus 310.

As shown in Figure 4, the apparatus 310 further comprises a pressure relief valve 356, which will be described further below.

In use, the second pressurised fluid, i.e., hydraulic fluid, is directed from the source 352 to the second chamber portion 350. The piston member 316 is axially moveable relative to the housing 314 in response to the fluid pressure in the second chamber portion 350 acting on the area of the piston member 316 exposed to the pressurised fluid.

Translation of the piston member 316 relative to the housing 314 applies a tensile force L on the mechanical member 312, inducing a strain in the mechanical member 312.

The magnitude of the tensile force L and the resultant strain is governed by the supply pressure of the second pressurised fluid, and thus can be accurately controlled.

Once the desired tensile load force L has been applied to the mechanical member the curable material is directed from the source 328 of the curable material to the first chamber portion 348 via the conduit 330.

It will be recognised that the curable material is in a liquid state and thus exerts a fluid pressure on the shuttle 346. The shuttle 346 is axially moveable relative to the piston chamber 316 in response to the force acting on the shuttle 346 as a result of the fluid pressure of the curable material in the first chamber portion 348 acting on the area of the shuttle 346 exposed to the curable material. As shown, translation of the shuttle 346 sweeps the pressurised fluid, i.e., the hydraulic fluid, from the second chamber portion 350.

The second pressured fluid is discharged at a pressure regulated by the pressure relief valve 356 and that pressure will determine the load in the mechanical member 312 while the shuttle transits and the piston chamber is cleared of the second pressurised fluid and replaced by the curable material. That load may be any load up to the intended final tension load force L. Once shuttle 346 contacts the piston member 346 then the load in the mechanical member is determined by the supply pressure of the curable material. That supply pressure is regulated to set and maintain the tensile load L in mechanical member 312 until the curable material has cured, thereby locking in the strain in mechanical member 312.

As shown in Figure 4, the chamber 318 has a curable material side 348 that has an inlet A and an outlet B, and in use some of the curable material is flushed through the chamber 348. The apparatus 310 is configured so that shuttle member 346 cannot stroke while the chamber 248 is flushed. Once flushing has been effected, the outlet B is closed such that the pressure can build until the shuttle member 346 starts to travel through the chamber 318. The chamber 318 is filled with the curable material at a preselected pressure required to generate the desired load force L and strain in the mechanical member 312.

The apparatus 310 can be configured without the outlet B. Any fluid resident in the apparatus from source 328 to chamber 348 when the curable material is delivered from source 328 will amalgamate with the curable material within the chamber 318.

As noted above, it will be understood that various modifications may be made without departing from the scope of the claimed invention.

For example, Figures 5A and 5B shows an alternative apparatus 410. The apparatus 410 is similar to the apparatus 110 described above and shown in Figures 2A, 2B, but adapted to include a shuttle member 446 similar to that described above with reference to Figures 4A, 4B, and 40.

For example, Figures 6A and 6B shows an alternative apparatus 510. The apparatus 510 is similar to the apparatus 210 described above and shown in Figures 3A and 3B, but adapted to include a shuttle member 546 similar to that described above with reference to Figures 4A,4B, and 40.

Referring now to Figures 7 and 8 of the accompanying drawings, there are shown fluid delivery arrangements of the apparatus 10,110,210,310,410,510 described above.

Figure 7 illustrates a fluid delivery arrangement 600 to deliver the curable material. As shown in Figure 7, the fluid delivery arrangement 600 is configured to maintain the pressure in the curable material at a prescribed pressure to impart a prescribed tensile load force L and thus strain into the mechanical member 12;112;212;312;412;512 until the curable material transitions from its liquid state to its solid state. It will be understood that the term liquid state means flowable state. The prescribed strain is thereby retained in the mechanical member 12;112;212;312;412;512. It will be recognised that the components wetted by the curable material are single-use; sacrificed to the solidified curable material.

As shown in Figure 7, the delivery arrangement 600 includes a reservoir 602 for receiving and mixing the components of the curable material. In the illustrated arrangement 600 the components of the curable material take the form of liquid plastic resin and a hardener in liquid form. The reservoir 602 is in fluid communication with a pump 604. The pump 604 is single-use since it will have cured material inside it at the end of the operation.

The delivery pressure (and thereby the tensile load force L and strain induced in the mechanical member 12;112;212;312,412,512) is governed by the relief valve 606 on the pump discharge.

The pressure may be maintained more local to the apparatus 10;110;210;310,410,510 by a pressure accumulator or functionally similar device 610.

The supply to the pump 604 may be from a single source of mixed curable material, such as reservoir 602 or from a plurality of individual metered supplies 608 delivering the fluid components of the curable material in the appropriate proportions to formulate the curable material.

The delivery system 600 interfaces with the rest of the apparatus 10;110;210;310;410,510 at the battery limit 612, defining the source 28;128;228; 328;428;528.

Figure 8 illustrates an alternative fluid delivery arrangement 700 that forms part of one or more of the apparatus 10,110,210,310;410;510.

As shown in Figure 8, the delivery arrangement 700 comprises cylinders 702, 704, 706 that are coupled together by a common mounting 713. The piston rods 708, 710, 712 are coupled together by coupler 714. Cylinder 702 is functioned by a hydraulic oil power pack (not shown) at the battery limit 716.

The prescribed strain in the mechanical member 12;112;212;312;412;512 is established by the prescribed pressure delivered and maintained in volume 718. That pressure translates to a different pressure in volumes 720 and 722 and it is that pressure that is delivered to the rest of the apparatus 10;110;210;310;410;510 beyond the battery limit 724.

The pressure may be maintained more locally to the rest of the apparatus 10;110;210;310;410;510 by a pressure accumulator or functionally similar device 726.

This accumulator or functionally similar device 726 may be incorporated in the build of the apparatus 10;110;210;310;410;510.

The pressure delivered is a function of the prescribed pressure delivered to volume 718 in the ration of the total pressure-active areas of cylinders 704,706 to the pressure-active area of cylinder 702. Cylinders 704,706 are sized differently according to the ratio of the component fluids required to formulate the curable material to be delivered.

Cylinders 704,706 may comprise one, two or more cylinders as determined by the composition of the curable material. Cylinder 704 and cylinder 706 and any further cylinders will each discharge through a non-return valve 728,730 or functionally similar device to a mixer unit 732. Only components wetted by the curable material discharged from the mixer unit 732 and the mixer unit 732 itself are single-use. The mixer unit 732 may be incorporated into the apparatus 10;110;210;310;410;510. The other components of the delivery arrangement 700 are multi-use components.

The delivery arrangement 700 need not have volumes 720,722 charged with the fluids to deliver the full volume of curable material necessary to function the apparatus 10;110;210;310;410;510. The curable material may be supplied to more than one apparatus simultaneously. The provision of check valves or similar devices 734,736 at cylinders 720,722 and of supply reservoirs 738,740 of the component fluids to formulate the curable material allows the delivery arrangement 700 to take multiple charges from the reservoirs 738,740 and to deliver multiple volumes of the curable material from the mixer unit 732.

The delivery arrangement 700 may have one, two or more such check valve and reservoir arrangements consistent with the number of cylinders such as cylinders 720,722 making up the delivery arrangement 700.

The delivery arrangement 700 can be configured to deliver the prescribed pressure to volume 742 and the corresponding functions associated with cylinders 720,722 revert to volumes 744,746.

This delivery system 700 interfaces with the rest of apparatus 10;110;210;310;410;510 at the battery limit 724, defining the source 28;128;228;328;428;528.

Claims (19)

1. CLAIMS1. An apparatus for tensioning a mechanical member, the apparatus comprising: a fluid-powered tensioner arrangement comprising: a housing; a chamber for receiving a pressurised fluid comprising or taking the form of a curable material; and a piston member axially movable relative to the housing, wherein the piston member forms part of, is configured for coupling to, or is configured to engage the mechanical member to be tensioned, and wherein movement of the piston member relative to the housing transmits a tensile load force to the mechanical member so as to induce strain in the mechanical member; a fluid delivery arrangement for delivering the curable material to the chamber, such that when the curable material cures the strain induced in the mechanical member is locked-in.
2. 2. The apparatus of claim 1, wherein the tensioner arrangement comprises or takes the form of a hydraulic tensioner arrangement.
3. 3. The apparatus of claim 1 or 2, wherein the curable material comprises or takes the form of: a resin; a resin and a hardener; or a grout material.
4. 4. The apparatus of claim 1, 2 or 3, wherein the housing is configured for location on and/or around a portion of the mechanical member.
5. 5. The apparatus of any preceding claim, wherein the apparatus comprises a plurality of the piston members.
6. 6. The apparatus of any preceding claim, comprising a piston rod.
7. 7. The apparatus of claim 6, wherein the piston rod is at least partially formed by the mechanical member to be tensioned.
8. 8. The apparatus of claim 6, wherein the piston rod is coupled to the mechanical member to be tensioned.
9. 9. The apparatus of claim 6, 7 or 8, wherein the piston rod is integrally formed with the piston member.
10. 10. The apparatus of claim 6, 7 or 8, wherein the piston rod is coupled to the piston member.
11. 11. The apparatus of any preceding claim, comprising a curable material source, wherein the fluid delivery arrangement is configured to deliver the curable material from the curable material source to the chamber.
12. 12. The apparatus of any preceding claim, wherein the chamber defines a first chamber portion and a second chamber portion.
13. 13. The apparatus of claim 12, when dependent on claim 11, wherein the first fluid chamber is configured for coupling to and/or fluidly communicate with the curable material source.
14. 14. The apparatus of claim 12 or 13, wherein the second chamber portion is configured to receive a second pressurised fluid.
15. 15. The apparatus of claim 14, wherein the second pressurised fluid comprises or takes the form of hydraulic oil.
16. 16. The apparatus of any one of claims 12 to 15, wherein the second chamber portion is coupled to and/or fluidly communicate with a second pressurised fluid source.
17. 17. The apparatus of any one of claims 12 to 16, comprising a shuttle disposed within the chamber, the shuttle dividing the chamber into the first chamber portion and the second chamber portion.
18. 18. A method for tensioning a mechanical member, the method comprising: applying a tensile load force to a mechanical member using a fluid-powered tensioner arrangement so as to induce strain in the mechanical member to be tensioned; delivering a pressurised fluid comprising or taking the form of a curable material to a chamber of the fluid-powered tensioner arrangement; and curing the curable material to lock-in the strain in the mechanical member.
19. 19. The method of claim 18, wherein the fluid-powered tensioner may comprise: a housing; the chamber for receiving the pressurised fluid in the form of the curable material; and a piston member axially movable relative to the housing, wherein the piston member forms part of, is configured for coupling to, or is configured to engage the mechanical member to be tensioned, and wherein movement of the piston member relative to the housing transmits a tensile load force to the mechanical member so as to induce strain in the mechanical member.