WO2020230082A1

WO2020230082A1 - A mechanical tensioning device and method

Info

Publication number: WO2020230082A1
Application number: PCT/IB2020/054582
Authority: WO
Inventors: Christian Ivan BASSON; Lorenzo Andrea MISSIO
Original assignee: Advmet (Pty) Ltd
Priority date: 2019-05-16
Filing date: 2020-05-14
Publication date: 2020-11-19
Also published as: ZA202108913B

Abstract

The invention relates to a removable mechanical tensioning device, and a method of stretching a bolt or stud axially, the bolt being located in and attachable to an object via a nut. The device is operatively attachable to the bolt and comprises or is operatively coupled to a nut engaging assembly configured to automatically engage and tighten the nut, at a lower torque than the applied tool torque during loading conditions. In particular, displacement of a part of the tensioner device during loading conditions, causes axial stretch of the elongate member and actuation of the nut engaging assembly in the manner mentioned.

Description

A MECHANICAL TENSIONING DEVICE AND METHOD

FIELD OF INVENTION

The invention relates to a mechanical tensioning device, particularly a removable mechanical tensioning device such as a load socked, and a method of stretching a bolt or stud axially.

BACKGROUND OF THE INVENTION

In many conventional fastening applications employing bolts/studs, for example, fastening of objects such as flanges together, at least one bolt/stud is located in the objects via suitably aligned apertures and a nut is tightened around the bolt/stud with torque applied to the nut via a suitable tool such as a wrench with a socket. This technique, colloquially referred to as“torqueing the bolt/stud and/or nut”, relies on torque applied to the nut to axially stretch, or in other words tension, the bolt/stud in a well-known and desirable fashion but results in undesirable torsional twisting of the bolt/stud which is affected by varying friction coefficients of engaging surfaces between the nut and/or bolt/stud and/or object. Torsional twist becomes a major concern as the length of the bolt/stud increases. Moreover, frictional forces can account for up to 80% of energy required to achieve correct bolt load when torqueing a nut in a conventional manner. In addition, it is noted that in conventional torqueing techniques as described herein, the majority of friction (approximately 50%, or more) occurs under the nut face. The friction under the nut face, typically at an intersection of the nut and a surface of the object, is referred to as nut face friction and relatively small changes this nut face friction can have a significant effect on bolt preload.

Though nut face friction may be reduced by lubrication, the accuracy of repeated tests is relatively low with high scatter. In addition, lubrication use has certain drawbacks in that certain industries such as food and/beverage industries are not keen on the use of lubricants in certain fastening applications. Moreover, lubrication may add to slippage between the bolt/stud and nut increasing risk of loosening of nuts.

It is well known to those skilled in the art, that when torqueing of Stainless Steel, Aluminium, and Titanium fasteners, the risk of galling (micro welding between nut and stud) is high. Typically galling happens during the tightening process where friction between the nut and thread surface can cause micro-welding. In order to mitigate the risks, the conventional torqueing operations need be highly controlled by reducing the torque speed and the use of copious amounts of suitable and expensive lubricants.

The present invention seeks to address the drawbacks evident in conventional techniques employed to tension bolts/studs by way of torqueing.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a removable mechanical tensioning device for stretching an elongate member in an axial direction, the elongate member being located in and attachable to an object via a nut, wherein the tensioning device defines an interior within which the elongate member and nut are locatable, in use, wherein the tensioning device comprises or is operatively coupled to a nut engaging assembly configured to engage the nut, in use, such that displacement of at least a transversely displaceable part of the tensioning device in a transverse direction, transverse to the axial direction, causes stretch of the elongate member in the axial direction; and actuation of the nut engaging assembly to bring about displacement of the nut in the transverse direction relative to the stretched elongate member with a torque and/or force which is lower than torque and/or force applied to the bring about operative displacement of the transversely displaceable part of the tensioning device to cause axial stretch of the elongate member.

The terms “tensioning device” and “tensioner device” may be used interchangeably herein.

The displacement of the nut may be automatic and/or simultaneous. The nut engaging assembly may be configured to displace the nut in the transverse direction automatically and/or simultaneously with stretching of the elongate member.

It will be appreciated that the nut engaging assembly may be configured to displace the nut in the transverse direction upon displacement of at least part of the tensioning device with a torque value and/or force which is lower than torque and/or force applied to the bring about operative displacement of at least part of the tensioning device to axially stretch the bolt. In other words, the nut may be automatically and/or simultaneously tightened around the stretched elongate member with a lower torque than that applied to the tensioning device.

It will be understood that“automatic and/or simultaneous” displacement of the nut may be understood to mean displacement and/or tightening of the nut about the stretched elongate member without the need for additional tools and/or action outside of the device described herein and/or force or torque applied to displace the transversely displaceable part of the tensioner device in the transverse direction. In other words, no other means need be used outside of the device disclosed herein, with the single action of the transverse displacement of the transversely displaceable part of the tensioning device, to automatically and/or simultaneously axially stretch the elongate member and turn or tighten the nut around the elongate member so as to preserve said axial stretch of the elongate member.

The lower torque applied by the nut engaging assembly to bring about automatic and/or simultaneous displacement of the nut may be derived from and may be lower than the torque applied to displace the transversely displaceable part of the tensioning device in the transverse direction.

The tensioning device may comprise: a base portion; a friction element; and a tensioning body attached to the base portion while abutting the friction element, wherein the tensioning body is freely displaceable in the transverse direction relative to the base portion and the friction element.

The tensioning body may comprise a tool end portion.

Under load conditions, with the tensioning device operatively attached to the elongate member and the base portion abutting a surface adjacent the nut, the nut engaging assembly operatively engages the nut, wherein displacement of the tensioning body in the transverse direction causes stretch of the elongate member in the axial direction; and actuation of the nut engaging assembly.

The tensioning body may be freely displaceable relative to the friction element in a frictional fashion. This may be due to the co-efficient of friction between the tensioning body and the friction element.

It will be understood that, in use, the base portion operatively abuts a surface adjacent to the nut. The axial stretch of the elongate member may be along its longitudinal axis.

The tensioning body may be the transversely displaceable part of the tensioning device which may be transversely displaceable, in use, in response to an applied force or torque. It follows that the nut engaging assembly may be configured to automatically and/or simultaneously displace the nut in the transverse direction upon displacement of at least part of the tensioning body with a torque value which is lower than the torque applied to the bring about displacement of at least the transversely displaceable part of the tensioning device.

The tensioning body may define a bore having an axis aligned with a central axis of the tensioning device, and a chamber in communication with the bore. The central axis of the tensioning device may be an axis along which the interior of the tensioning device extends. The chamber may be shaped and/or dimensioned to house all or a part of the nut engaging assembly. The chamber may be located at an end opposite to the tool end portion. The tool end portion may thus be located at a first end portion of the tensioning body and the chamber may be located at a second end portion of the tensioning body. The tool end portion may be attached or engageable with a suitable tool. The tool end portion of the tensioning body may comprise a nut integral therewith. Instead, or in addition, the tool end portion may comprise a suitable coupling for attachment to the suitable tool. The tool end portion may comprise or define engaging formations within the bore for engaging the elongate member, in use. The engaging formations may be complementary screw-threading for engaging screw-threading provided on an outer surface of the elongate member.

In some example embodiments, the tool end portion is in the form of a coupling for operative engagement with a suitable tool. The actuation of the nut engaging assembly may be automatic and/or simultaneous as a result of operative cooperation between the nut engaging assembly and the tensioning body during displacement of the tensioning body.

The nut engaging assembly may be operatively arranged with the base portion and/or the tensioning body such that, in use, with the elongate member with the nut attached located in the bore of the tensioning device such that the nut engaging assembly operatively engages the nut, and the elongate member operatively is operatively attached to the tensioning body via the engaging formations, displacement of the tensioning body in the transverse direction causes displacement of the elongate member in the axial direction; and actuation of the nut engaging assembly to bring about automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member.

It will be appreciated that under load conditions, a predetermined amount of force needs to be applied to the device and/or tensioning body to load the elongate member. Moreover, under load conditions, it will be appreciated that the elongate member is located through the bore and the base portion abuts a surface adjacent the nut. In this way, torque applied to the tensioning body may effectively stretch the elongate member but the nut face friction is eliminated as the friction is taken up by the tensioning body frictionally engaging the friction element.

In one example embodiment, the nut engaging assembly may comprise a resilient nut engaging member adapted to engage the nut, in use, wherein the resilient nut engaging member co-operates with the displaceable part of the tensioning device during displacement thereof in the transverse direction to cause loading of the resilient nut engaging member which causes automatic and/or simultaneous displacement of the nut with a lower torque than the torque applied to the transversely displaceable part of the tensioning device, in the transverse direction relative to the stretched elongate member upon release of said loading. The resilient nut engaging member may be operatively arranged with the base portion and/or the tensioning body such that, in use, the displacement of the tensioning body in the transverse direction causes loading of the resilient nut engaging member and automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member. For example, upon release of said loading.

The device may comprise a load arrangement to cause operative engagement of the tensioning body and the resilient nut engaging member, in use, under load conditions to facilitate the loading of the resilient nut engaging member. It will be appreciated that the resilient nut engaging member may be freely displaceable in the transverse direction under non-load conditions but under load conditions, the load arrangement operates to allow operative engagement between the tensioning body and the resilient nut engaging member to facilitate loading of the latter.

In one example embodiment, the load arrangement may comprise one or more plungers which are displaced to operatively facilitate engagement of the tensioning body and the resilient nut engaging member.

The tensioning body may be attached to the base portion adjacent the second end portion thereof.

Displacement in the transverse direction may be rotation about the central axis. From the description which follows the transverse direction may be clockwise or anti clockwise about the central axis.

The base portion may define an aperture. The aperture of the base portion may have an axis aligned with the central axis. The base portion may comprise of one or more bearing elements which are operatively engageable with the tensioning body so as at least to facilitate free displacement of the tensioning body in the transverse direction. In one example, embodiment, the tensioning body may define a circumferentially extending groove on an outer surface thereof adjacent an end of the second end portion, within which the bearing elements are locatable. In this way, at least one of the bearing elements may effectively attach the tensioning body to the base portion in a displaceable fashion as described herein.

It will be understood that, in use, the base portion rests on the object and is moveable relative to the same.

The friction element may define an aperture. The aperture of the friction element may have an axis aligned or at least parallel with the central axis. The friction element may be, at least in part, sandwiched between the tensioning body and the base portion. The friction element may not be moveable relative to the tensioning body and/or the base portion. In one example embodiment, the friction element is attached to the base portion in a fixed/immovable fashion. The second end portion of the tensioning body may define a surface which abuts the friction element when the tensioning body is attached to the base portion.

In one example embodiment, the resilient nut engaging member may be in the form of a resilient spring-like member extending between a first end portion and a second end portion, wherein a bore is provided there through. The bore may have an axis aligned with the central axis. The first end portion may define engaging formations to merely attach the resilient nut engaging member to the tensioning body so as to allow free displacement thereof in the transverse direction under non-load conditions. In one example embodiment, the resilient nut engaging member may comprise one or more radially extending flanges adjacent the first end portion thereof for location in a suitable circumferentially extending notch provided with the chamber. In this way, axial removal of the resilient nut engaging member from attachment to the tensioning body is limited and operative engagement between the resilient nut engaging member and the tensioning body is by way of the load arrangement under load conditions.

The second end portion of the resilient nut engaging member may define nut engaging formations for engaging the nut in a gripping or holding fashion, in use. The nut may be a conventional nut having a polygonal profile but any profile nut may be used within the context of the present disclosure. The elongate member may be a bolt or a stud. The resilient nut engaging member may comprise a load release mechanism to release the loaded resilient nut engaging member causing displacement thereof thereby to displace the nut in the transverse direction, in use.

The resilient nut engaging member may be locatable within the chamber of the tensioning body such that the axes of the bores of both parts are aligned.

In another example embodiment, the nut engaging assembly may comprise a clutch arrangement configured to engage the nut and displace the nut in the transverse direction with a lower torque than the torque applied to the transversely displaceable part of the tensioning device. In other words, the clutch arrangement may be configured to engage the nut and displace the nut in the transverse direction automatically and/or simultaneously and with a lower torque than the torque applied to the tensioning body to bring about displacement thereof in the transverse direction.

The clutch arrangement may engage with a friction body located in the tensioning body and/or the base portion, and the nut, in use, such that interaction of the clutch arrangement and the friction body during the displacement of the transversely displaceable part of the tensioning device in the transverse direction which causes displacement of the nut with a lower torque than that applied to the transversely displaceable part. It will be appreciated that displacement of the nut with a lower torque may be due to frictional engagement of the clutch arrangement and the friction body. In other words, the slippage between the clutch arrangement and the friction body.

In one example embodiment, at least one part of the clutch arrangement is freely displaceable relative to the tensioning body and/or the base portion in the transverse direction. The transverse direction may be a tightening direction or a clockwise direction to the central axis when viewed from above. The direction opposite to the transverse direction or in other words the opposite direction may be a loosening direction or an anti-clockwise/counter-clockwise direction to the central axis when viewed from above.

The clutch arrangement may be located in the chamber of the tensioning body. In this regard, the chamber may be shaped and/or dimensioned to house the clutch arrangement. The friction body may be in the form of a friction bush located in a seat provided within the chamber of the tensioning body. The clutch arrangement may comprise: a nut rotating socket; and a one way clutch assembly which interfaces with the friction body and co-operates with the nut rotating socket such that, in use, application of torque to bring about displacement of the displaceable part of the tensioning device in the transverse direction causes the one way clutch assembly to be operated to a locked condition in which it is frictionally displaceable relative to the friction body only so as to limit the torque applied to the nut located operatively in nut rotating socket to a lower value than that of the torque applied to the displaceable part of the tensioning device.

It will be appreciated that displacement of the displaceable part of the tensioning device in a direction opposite to the transverse direction, in use, may cause the one way clutch assembly to be operated to an activated condition which permits free displacement of the nut rotating socket and/or the tensioning body relative to the clutch assembly. The friction body may be constructed out of a similar material as the friction member.

The one way clutch assembly may comprise a clutch disk locatable in and displaceable within a sleeve, wherein the clutch disk comprises one or more peripheral apertures within which clutch elements may be locatable. The clutch elements facilitate operation of the one way clutch assembly between the locked and activated conditions, wherein in the locked condition the clutch disk is locked against displacement within the sleeve. In the activated condition the clutch disk is freely displaceable within the sleeve. The clutch elements may interferingly be displaceable within zones defined by the sleeve and the clutch disk to facilitate operation of the one way clutch. It will be noted that due to the interaction with the clutch elements, the clutch disk is the at last one part of the clutch arrangement freely displaceable in the transverse direction in the activated condition.

Differently defined, in use, the tensioning body may be configured to actuate the clutch assembly between the locked and activated conditions. In this regard, displacement of the tensioning body, in use, in the transverse direction causes operation of the clutch assembly to the locked condition. In the locked condition, the clutch disk is locked against displacement within the sleeve, wherein further displacement of the tensioning body in the transverse direction causes displacement of the sleeve of the clutch assembly relative to the friction bush which it abuts in a frictionally engaging manner. It will be noted that the coefficient of friction between the sleeve and friction bush may be selected such that displacement of the friction bush relative to the sleeve occurs during displacement of the tensioning body in the transverse direction.

Rotation of the tensioning body in the direction opposite to the transverse direction causes operation of the clutch assembly to the activated condition, in which the clutch disk is free to rotate within the sleeve in the transverse direction. When the clutch disk is in the activated condition, it will be appreciated that the tensioning body is free to rotate in the direction opposite to the transverse direction.

The clutch disk and the nut rotating socket may engage with each other via suitable castellations which allow for a degree of play before actuation of the clutch to a locked and/or activated conditions. In one example embodiment, the clutch disk may comprise grooves within which castellations of the nut rotating socket may be locatable in, wherein the nut rotating socket is configured to engage the clutch disk to actuate the same only after a degree of displacement of the nut rotating socket. In this way, when torque is applied to displace the displaceable part of the tensioner body, the nut rotating socket only operatively engages the clutch to operate the same to the locked condition after a predetermined amount of displacement or rotation of the nut rotating socket.

In one example embodiment, the tensioning body may comprise a retaining member to retain the nut engaging assembly in the chamber of the tensioning body. The retaining member may define the surface of the tensioning body which abuts the friction element when the tensioning body is attached to the base portion. The retaining member may be removably attachable to the tensioning body. For example, in a screw-threaded fashion. The nut rotating socket may be operatively located in a nested fashion within the retaining member.

It will be appreciated that all the components of the clutch arrangement may comprise apertures which are aligned with the central axis. It will be appreciated that a portion of the elongate member must protrude from the nut. The protruding length of the elongate member must be approximately 1.5 times the diameter of the elongate member.

Moreover, the portion of the elongate member protruding from the nut may operatively be engageable by engaging formations of the tool end portion of the tensioning body, in use.

The device may be a removable device from the elongate member and nut after axially stretching the elongate member and automatically and/or simultaneously displacing the nut around the axially stretched member.

It will be noted that the bores and chambers of the components of the tensioning device and/or the nut engaging assembly may all be aligned and may all extend through the tensioning device and/or assembly.

According to another aspect of the invention, there is provided a removable mechanical tensioning device for stretching an elongate member in an axial direction, the elongate member being located in and attachable to an object via a nut, wherein the device defines an interior extending along a central axis, and comprises: a base portion; a friction element; a tensioning body attachable to the elongate member, wherein the tensioning body is attached to the base portion while abutting the friction element such that the tensioning body is freely displaceable relative to the base portion and the friction element in a transverse direction, transverse to the axial direction, wherein the tensioning body comprises an tool end portion; and a resilient nut engaging member being adapted to engage the nut, in use, wherein the resilient nut engaging member is operatively engageable with at least the tensioning body such that, in use, under load conditions with the tensioning body operatively attached to the elongate member and the base portion abutting a surface adjacent the nut, the resilient nut engaging member operatively engages the nut, wherein displacement of the tensioning body in the transverse direction causes stretch of the elongate member in the axial direction; and loading of the resilient nut engaging member to cause automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member.

According to another aspect of the invention, there is provided a removable mechanical tensioning device for stretching an elongate member in an axial direction, the elongate member being located in and attachable to an object via a nut, wherein the device defines an interior extending along a central axis, and comprises: a base portion; a friction element; a tensioning body attachable to the elongate member, wherein the tensioning body is attached to the base portion while abutting the friction element such that the tensioning body is freely displaceable relative to the base portion and the friction element in a transverse direction, transverse to the axial direction, wherein the tensioning body comprises an tool end portion; and a clutch arrangement being adapted to engage the nut, in use, wherein the clutch arrangement is operatively engageable with the base portion and/or the tensioning body such that, in use, under load conditions with the tensioning body operatively attached to the elongate member and the base portion abutting a surface adjacent the nut, the clutch arrangement operatively engages the nut, wherein displacement of the tensioning body in the transverse direction causes stretch of the elongate member in the axial direction; and actuation of the clutch arrangement to cause automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member.

According to another aspect of the invention, there is provided a removable mechanical tensioning device for stretching an elongate member in an axial direction, the elongate member being located in and attachable to an object via a nut, wherein the device defines an interior therethrough extending along a central axis, and comprises: a base portion; a friction element; a tensioning body attachable to the elongate member, wherein the tensioning body is attached to the base portion while abutting the friction element such that the tensioning body is freely displaceable relative to the base portion and the friction element in a transverse direction, transverse to the axial direction, wherein the tensioning body comprises an tool end portion for engagement with a suitable tool, in use; and a resilient nut engaging member being adapted to engage the nut, in use, wherein the resilient nut engaging member is operatively engageable with at least the tensioning body such that, in use, under load conditions with the tensioning body operatively attached to the elongate member and the base portion abutting a surface adjacent the nut, the resilient nut engaging member operatively engages the nut, wherein displacement of the tensioning body in the transverse direction causes stretch of the elongate member in the axial direction; and loading of the resilient nut engaging member to cause automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member; or a clutch arrangement being adapted to engage the nut, in use, wherein the clutch arrangement is operatively engageable with the base portion and/or the tensioning body such that, in use, under load conditions with the tensioning body operatively attached to the elongate member and the base portion abutting a surface adjacent the nut, the clutch arrangement operatively engages the nut, wherein displacement of the tensioning body in the transverse direction causes stretch of the elongate member in the axial direction; and actuation of the clutch arrangement to cause automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member.

According to yet another aspect of the invention, there is provided a method for stretching an elongate member in an axial direction mechanically, the elongate member being located in and attachable to an object via a nut, wherein the method comprises: attaching a tensioner device over the elongate member and the nut such that a base of the tensioner device rests on the object and a nut engaging assembly of or coupled to the tensioner device engages the nut; displacing the tensioner device in a transverse direction, transverse to the axial direction, such that the tensioner device is wound down on the elongate member and a base portion thereof abuts the object, and a nut engaging assembly of or coupled to the tensioning device is operatively engaged with the tensioning body and/or the nut; and displacing a transversely displaceable part of the tensioning body in the transverse direction under load conditions to cause stretch of the elongate member in the axial direction; and automatic actuation of the nut engaging assembly to bring about displacement of the nut in the transverse direction relative to the stretched elongate member with a torque and/or force which is lower than torque and/or force applied to the bring about operative displacement of the transversely displaceable part of the tensioning device to cause axial stretch of the elongate member.

In one example embodiment, the nut engaging assembly may actuated by co- operation with the tensioning body under load conditions with the nut operative engaged thereby.

It will be appreciated that the method may comprise turning the nut about the elongate member prior to the use of the tensioning device as described herein. In this way, the nut is loosely but snugly attached at the intersection of the elongate member and the object.

Once a desired loading of the elongate member has been achieved, the method may comprise removing the device from engagement with the elongate member and nut respectively.

According to another aspect of the invention, there is provided a method for stretching an elongate member in an axial direction mechanically, the elongate member being located in and attachable to an object via a nut, wherein the method comprises: attaching a device as described herein to a free end of the elongate member; displacing the device in a transverse direction, transverse to the axial direction, such that the base portion abuts the object, particularly the surface of the object adjacent the nut and the resilient nut engaging member is operatively engaged with the tensioning body and the nut; and displacing the tensioning body in the transverse direction under load conditions to cause stretch of the elongate member in the axial direction; and loading of the resilient nut engaging member to cause automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member.

According to another aspect of the invention, there is provided a method for stretching an elongate member in an axial direction mechanically, the elongate member being located in and attachable to an object via a nut, wherein the method comprises: attaching a device as described herein to a free end of the elongate member; displacing the device in a transverse direction, transverse to the axial direction, such that the base portion abuts the object, particularly the surface of the object adjacent the nut, and the clutch arrangement is operatively engaged with the nut; and displacing the tensioning body in the transverse direction under load conditions to cause stretch of the elongate member in the axial direction; and actuation of the clutch arrangement to cause automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member. According to another aspect of the invention, there is provided a method for stretching an elongate member in an axial direction mechanically, the elongate member being located in and attachable to an object via a nut, wherein the method comprises: attaching a device as described herein to a free end of the elongate member; displacing the device in a transverse direction, transverse to the axial direction, such that the base portion abuts the object, particularly the surface of the object adjacent the nut, and the resilient nut engaging member is operatively engaged with the tensioning body and/or the nut or the clutch arrangement is operatively engaged with the nut; and displacing the tensioning body in the transverse direction under load conditions to cause stretch of the elongate member in the axial direction; and actuation of the clutch arrangement to cause automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member; or loading of the resilient nut engaging member to cause automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member.

According to yet another aspect of the invention, there is provided a method for stretching an elongate member in an axial direction mechanically, the elongate member being located in and attachable to an object via a nut, wherein the method comprises: attaching a device as described herein to a free end of the elongate member; displacing the transversely displaceable part of the device in a transverse direction, transverse to the axial direction, such that the base portion abuts the object, particularly the surface of the object adjacent the nut, and the nut engaging assembly of or coupled to the tensioning device is operatively engaged with the tensioning body and/or the nut; and displacing the transversely displaceable part of the tensioning body in the transverse direction under load conditions to cause stretch of the elongate member in the axial direction; and actuation of the nut engaging assembly to bring about automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member.

It will be appreciated by those skilled in the art that the comments above regarding the previously described aspects of the invention applies to all other aspects of the invention, mutatis mutandis.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a three-dimensional perspective view of a device in accordance with an example embodiment of the invention in an assembled state, in use on an object shown in dotted lines;

Figure 2 shows a three-dimensional perspective view of a device in accordance with an example embodiment of the invention in an exploded state;

Figure 3 shows another three-dimensional perspective view of a device in accordance with an example embodiment of the invention in an exploded state; and

Figure 4 shows a sectional side view of the device of Figure 1 at Q-Q with an elongate member and nut included in dotted lines for illustrative purposes;

Figure 5 shows a three-dimensional perspective view of another device in accordance with an example embodiment of the invention in an assembled state, in use on an object shown in dotted lines;

Figure 6 shows a three-dimensional perspective view of the device of

Figure 5 in an exploded state;

Figure 7 shows another three-dimensional perspective view of the device of Figure 5 in an exploded state; and Figure 8 shows a sectional side view of the device of Figure 5 at G-G with an elongate member and nut included in dotted lines for illustrative purposes.

DETAILED DESCRIPTION OF THE DRAWINGS

The following description of the invention is provided as an enabling teaching of the invention. Those skilled in the relevant art will recognise that many changes can be made to the embodiment described, while still attaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be attained by selecting some of the features of the present invention without utilising other features. Accordingly, those skilled in the art will recognise that modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not a limitation thereof.

It will be appreciated that the phrase“for example,”“such as”, and variants thereof describe non-limiting embodiments of the presently disclosed subject matter. Reference in the specification to “one example embodiment”, “another example embodiment”, “some example embodiment/s”, or variants thereof means that a particular feature, structure or characteristic described in connection with the embodiment(s) is included in at least one embodiment of the presently disclosed subject matter. Thus, the use of the phrase“one example embodiment”,“another example embodiment”,“some example embodiment/s”, or variants thereof does not necessarily refer to the same embodiment(s).

Unless otherwise stated, some features of the subject matter described herein, which are, described in the context of separate embodiments for purposes of clarity, may also be provided in combination in a single embodiment. Similarly, various features of the subject matter disclosed herein which are described in the context of a single embodiment may also be provided separately or in any suitable sub combination. Referring to Figures 1 to 4 of the drawings, a removable mechanical tensioning device for stretching an elongate member 2 in an axial direction A (Figure 1 ) in accordance with an example embodiment of the invention is generally indicated by reference numeral 10. The axial direction may be in an upward and/or a downward axial stretching direction. The member 2 is located in and attachable to an object 4 via a nut 6. For ease of explanation and by way of a non-limiting example, the elongate member 2 is in the form of a conventional cylindrical bolt or stud having screw threading 2.1 provided on an exterior surface thereof and the nut 6 is in the form of a conventional nut having internal threading matched for complementary engagement with the bolt/stud and a polygonal profile, for example, a hexagonal profile.

The device 10 has dimensions matched to the dimensions of the bolt/stud 2 and the nut 6. In this regard, it follows that the dimensions of the device 10 may be selected depending on the application and the device 10 typically caters for bolt/stud diameters between M8 (5/16” or 7.94mm) and M18 (3/4” or 19.05mm). Bolt/ stud diameters outside of these typical diameters may also be catered for.

The object 4 may be in the form of a flange but it will be appreciated that the object may be any object to which the bolt/stud 2 is located in.

As will become evident from the descriptions which follow, the device 10 is typically configured to axially stretch a bolt/stud 2 and automatically and/or simultaneously turn/tighten the nut around the bolt/stud with a lower torque than that applied to stretch the bolt/stud 2 thereby preserving said axial stretch of the bolt/stud 2. Moreover, the device 10 requires no additional non-conventional tools to be used to operate in the manner as described herein.

The tensioning device 10 defines an interior in the form of a central bore 12 extending therethrough along a central axis X. It will be understood by those skilled in the art that the interior or central bore 12 of the device 10 is typically defined by the various bores and/or chambers and/or apertures making up the tensioner device 10 and/or the component/s located within the device 10 in substantially a co-axial fashion.

The device 10 is removably attachable to the bolt/stud 2 and comprises a plurality of co-operating parts. In particular, the device 10 comprises a base portion 20, a friction element 22, a tensioning body 24, and a nut engaging assembly 23 which comprises a resilient nut engaging member 26 arranged in a generally nested fashion. The friction element 22 is attached to the base in an immovable fashion, for example, via suitable one or more grub screws/pins 28, or the like. The tensioning body 24 is attached to the base portion 20, while abutting the friction element 22, by way of suitable bearing elements 30 in the form of ball plungers. The member 26 is arranged with the body 24 and is effectively sandwiched between the body 24 and base portion 20 as can be seen in Figure 4 and as will be described below.

The tensioning body 24 is conveniently arranged to be freely displaceable relative to the base portion 20 and the friction element 22 in a transverse direction B (Figure 1 ), transverse to the axial direction A. In particular, the tensioning body 24 may be freely displaceable in a frictional fashion, in use as will be described below.

The tensioning body 24 being displaceable in the transverse direction B may understood to mean that the body 24 is effectively rotatably displaceable about the central axis X. In this regard, the tensioning body 24 is freely rotatable relative to the base portion 20 while abutting the friction element 22, in a clockwise and anti- clockwise fashion about the central axis X.

The tensioning body 24 is comprises a tool engaging portion 24.1 and a generally cylindrical second end portion 24.2. The body 24 defines a bore 32 therethrough having an axis aligned with the central axis X, and a chamber 34 (as can be seen in Figure 3) in communication with the bore 32. The chamber 34 is shaped and/or dimensioned to house the nut engaging member 26.

The tool engaging portion 24.1 may comprise a suitable nut integral 25 with the body 24 for engagement with a suitable tool such as a ring or open-ended type wrench. To this end, the device 10 may be a load socket. The tensioning body 24 may define engaging formations 38 within the bore 32, for example, adjacent the tool engaging end portion 24.1 , for engaging the screw-threading 2.1 of the bolt/stud in a complementary fashion. In this regard, the device 10, particularly the bore 12 thereof is shaped and/or dimensioned to be matched with the shape and/or dimensions of a conventional bolt/stud 2.

The second end portion 24.2 of the body 24 typically defines the chamber 34. Moreover, the second end portion 24.2 has an operative surface 24.3 (Figure 3) which abuts the friction element 22. It will be evident from the drawings that the tensioning body 24 is attached to the base portion 20 adjacent the second end portion 24.2 thereof. In particular, the second end portion 24.2 of the body 24 may define a circumferentially extending groove 24.4, within which the ball plungers 30 are located so as to retain the body 24 in attachment with the base portion 20 in a manner which prevents axial separation of the base portion 20 and the body 24 but allows for free rotational movement between the base portion 20 and the body 24, as well as between the body 24 and the friction element 22 which abuts the body 24.

It will be appreciated that the base portion 20 may define an aperture 41 (Figure 2) having an axis aligned with the central axis X. The base portion 20 is also substantially cylindrical and has a generally U-shaped sectional profile. However, it will be understood that the outer appearance and/or shape of the base portion 20, or the tensioning body 24 may take on a variety of forms as will be understood by those skilled in the art.

The ball plungers 30 may be attached to the base portion 20 in a conventional fashion, for example, through machined apertures 31 and operatively project into a locating zone where the body 24 is locatable to engage the grove 24.4 in a manner described herein to effectively provide a bearing surface to assist in free rotation of the body 24.

The friction element 22 may be constructed of a different material than the base portion 20 and/or the body 24 and/or the member 26. In one example embodiment, the element 22 is in the form of a thrust washer with known and/or predetermined coefficient of friction. The thrust washer 22 may be constructed of a composite material whilst the device 10 is constructed of a suitable metal such as high strength tensile steel. The thrust washer 22 is generally disk-shaped with a central aperture having an axis aligned or at least parallel with the central axis. As evident from the foregoing and the drawings, the thrust washer 22 is typically sandwiched between the tensioning body 24 and the base portion 20. The friction element 22 is immovable relative to the tensioning body 24 and/or the base portion 20. It will be understood that the friction element defines an operative surface 22.1 (Figure 2) which abuts the surface 24.3 of the body 24. In one example embodiment, the resilient nut engaging member 26 may in the form of a spring-like member, for example, a machined spring body 40 extending between a first end portion 26.1 and a second end portion 26.2. It will be understood that a bore 26.3 is provided through the resilient nut engaging member 26, the bore 26.3 having an axis aligned with the central axis X.

The first end portion 26.1 typically defines radially extending flanges 26.5 which are locatable in a suitable circumferentially extending notch 34.1 defined by the body 24 in the chamber 34. Once the member 26 is located in the chamber 34, the flanges

26.5 effectively attach the member 26 to the body 24 in a manner which allows rotation of the member 26 freely relative to the body 24 but restricts removal of the member from the body 24.

The second end portion 26.2 of the member 26 generally define nut engaging formations for engaging the nut 6 in a gripping fashion, particularly an outer surface thereof, in use. To this end, in one example embodiment, the nut engaging formations are teeth which project into the bore 26.3 of the member 26. It will be appreciated that the end portion 26.2 may be shaped and/or dimensioned to engage operative outer surfaces of a nut 6 of predetermined typically conventional shape and/or dimensions. It will be noted that the end portion 26.1 of the member 26 is axially spaced from the thrust washer 22, in use, so that there is no abutment between these two components.

The device 10 also comprises a load arrangement 50 comprising a plurality of suitable plunger elements 52 which are axially displaceable under load conditions. The load arrangement 50 effectively permits the member 26 to operatively engage with the body 24 to permit the latter to load the former in use as will be described below under load conditions.

In construction, referring to Figures 1 to 4, the thrust washer 22 is attached to the base portion 20 in an immovable fashion via one or more pins 28 through aligned apertures provided on said components.

The member 26 is located in the chamber 34 and the flanges thereof are located in the notch 34.1 so as to limit axial removal thereof but allow free rotation thereof under no-load conditions. The load arrangement is attached to the body 24. In particular, the plunger elements 52 (which may be or may comprise components which are axially displaceable, for example, in a resilient fashion), are located in suitable slots 24.8 (Figure 4) in the body 24. The body 24 is then attached to the base portion 20 such that the surface 24.3 of the body 24 rests on and effectively abuts the thrust washer 22, and the ball plungers 30 are operatively located in the groove 24.4. In this way, the body 24, as well as the member 26 located in the chamber 34, are restrained from displacement, and thus disengagement from the base portion 20, in the axial direction A with at least the body 24 being free to rotate in the transverse direction B. It will be appreciated that the mating surfaces between the body 24 and the thrust washer 22 may be lubricated via a suitable lubricant prior to assembly as described herein.

It will be noted that in some example embodiments, the portion 26.2 of the member 26 is axially spaced from the thrust washer 22 under both load and no-load conditions. However, in other example embodiments, the member 26 may be located in the chamber 34 such that it is restrained from removal from the chamber 34 by way of the thrust washer 22 but engagement with the nut 6 causes spacing of the portion 26.2 off the thrust washer 22. In this way the member 26 is not permitted to frictionally engage the thrust washer 22, in use, and particularly under load conditions.

In use, referring again to Figures 1 to 4 of the drawings, a bolt/stud 2 is located in the object 4 in a conventional fashion and a nut 6 is wound down on a free end of the bolt/stud and is tightened to a predetermined extent, typically by hand. In order to use the device 10 described herein, there must be a protrusion of threaded portions of the bolt/stud 2 of approximately 1.5 times the diameter of the bolt/stud 2.

The dimensions of the device 10 is selected based on the nut 6 and/or bolt/stud 2 dimensions as mentioned above. In particular, the bore 12 and/or screw-threading 38 is matched with the bolt/stud 2 and the end portion 26.2 of the member 26 is matched to the nut 6. The tensioning device 10 is located over the free end of the bolt/stud 2 such that the bolt/stud 2 is located through the central bore 12 of the device 10. The device 10 is then wound down on the bolt//stud 2 in a conventional fashion until the base portion 20 is adjacent the object 4, particularly the surface of the object 4 adjacent the nut 6. It will be noted that the member 26 freely rotates during this process under no- load conditions to engage with the nut 6 to grip the same.

Once the device 10 has been rotated down such that the base portion 20 abuts the object 4, a suitable tool such as a ring or open-ended wrench is engaged with the condition in the transverse direction B, typically clockwise (to the axis X when viewed from above). It will be understood that the transverse direction B may be clockwise (to the axis X when viewed from above) in the case of tensioning a bolt/stud 2 as described herein or counter-clockwise when loosening.

With a predetermined amount of torque being applied to the body 24, the plunger elements 52 are urged by abutment with the thrust washer 22 to be axially displaced to interact with the flanges 26.5 thereby permit operative engagement between the member 26 and the body 24, wherein displacement of the body 24 also causes displacement and/or loading of the member 26.

The body 24 is rotated under load conditions about axis X in a clockwise direction relative to the base portion 20 and the thrust washer 22 with the greatest friction encountered between abutting surface 22.1 of the thrust washer 22 and the surface 24.3 of the body 24. Rotation of the body 24 in this fashion causes the bolt/stud 2 to axially stretch in a desirable manner.

Moreover, as the body 24 rotates about the central axis X, the spring body 40 of the member 26 is loaded in a resilient manner as it is operatively engaged with the body 24 by way of the plunger elements 52 engaging the flanges 26.5 of the member 26. The loading of the member 26 in this fashion whilst engaged with the nut 6 causes the member 26 to also rotate in a resilient fashion in the transverse direction B thereby causing the nut 6 to rotate in the transverse direction B automatically and/or simultaneously and turn around the stretched bolt/stud 2 adjacent the intersection of the axially stretched bolt/stud 2 and the object 4 without inducing any nut face friction of the magnitudes associated with conventional torqueing techniques. It will be noted that here the nut 6 merely preserves the axial stretch achieved by the device 10 by being turned at a low torque around the bolt/stud 2 as opposed to torqueing the bolt/stud 2 in a conventional fashion as described herein. In particular, it will be noted that the nut 6 is turned with a force or torque which is lower than the force or torque applied to bring about rotation of the body 24. In any event, once desired bolt stretching has been achieved, the device 10 is removed from the bolt/stud and the device 10 by rotating the same in an anti -clockwise direction. In doing so, the elements 52 disengage from operative engagement with the member 26 thereby allowing free rotation of the member 26 relative to the body 24 and thus the nut 6 is not loosened as the device 10 is removed.

It will be noted that loosening of the nut/undoing the bolt/stud 2 stretch may be achieved with conventional tools such as hand wrenches. The present invention make the use of washers optional, since one of the functions of washers is to provide a hard surface for the nut face to turn on, washers being located between the nut and the surface of the object 4.

Referring now to Figures 5 to 8 of the drawings, where another, preferred example embodiment, mechanical tensioning device for stretching an elongate member 2 in an axial direction A (Figure 5) and automatically and/or simultaneously turning a nut 6 about the member 2 is generally indicated by reference numeral 100.

The device 100 is substantially similar to the device 10 described herein with reference to Figures 1 to 4 and thus similar parts will be labelled with similar reference numerals. Moreover, it will be understood by those skilled in the art that the description of components of the device 10 above apply mutatis mutandis to the device 100.

The device 100 is also configured to axially stretch a bolt/stud 2 and automatically and/or simultaneously turn/tighten the nut around the bolt/stud with a lower torque than that applied to stretch the bolt/stud 2 thereby preserving said axial stretch of the bolt/stud 2. The device 100 defines an interior in the form of a central bore 112 extending therethrough along a central axis X. The central bore 1 1 1 also has a chamber 134 and bore 132 in communication with each other.

One difference between the device 100 and the device 10 described herein is that the nut engaging assembly 23 in the device 100 is different to the assembly 23 of the device 10. In particular, instead of the resilient nut engaging member 26, the nut engaging assembly 23 of the device 100 comprises a clutch arrangement 126 configured to engage the nut 6 and displace the nut 6 in the transverse direction automatically and/or simultaneously and with a lower torque than the torque applied to the tensioning body 124. It will be understood by those skilled in the art that though the actual mechanism of operation of the clutch arrangement 126 may be different to the member 26, the end effect is the same in that the nut is automatically and/or simultaneously turned with lower torque than that applied to the tensioning body 124 so as to preserve the axial stretch of the bolt 2. It follows that other variations and mechanisms not described herein may be employed to achieve the same end described herein.

In some example embodiments, the clutch arrangement 126 may be engageable with a friction body in the form of a friction bush 127. The bush 127 may be located in a seat provided in the chamber 134 of the tensioning body 124. Interaction of the clutch arrangement 126 and the friction bush 127 during the displacement of the tensioning body 124, particularly in the direction of arrow D, causes turning/tightening of the nut 6 with a lower torque than that applied to tensioning body 124 due to the frictional engagement of the clutch arrangement 126 and the friction bush 127. To this end, the bush 127 may be constructed of a similar material as the thrust washer 22 and may thus have a predetermined coefficient of friction.

The bush 127 may be a ring-like bush which is provided at a periphery of the arrangement 126, essentially surrounding it.

In one example embodiment, the clutch arrangement 126 may comprise a nut rotating socket 130; and a one way clutch assembly 132. The one way clutch assembly 132 comprises a clutch disk 135 locatable in and displaceable within a sleeve 136, wherein the clutch disk 135 comprises peripheral apertures or cut-away portions 135.1 within which clutch elements 138 are locatable. The assembly 132 fits in a nested fashion within the friction bush 127 and thus it will be noted that the assembly 132 defines a bore therethrough aligned with the central axis X.

The clutch elements 138 may be cylindrical rollers with tapered waists and effectively facilitates operation of the one way clutch assembly 132 between locked and activated conditions, wherein in the locked condition, in use, the clutch disk 135 is locked against displacement within the sleeve 136 during displacement of the tensioning body 124 in the direction of arrow D (clockwise). In the activated condition, the clutch disk 135 is freely displaceable within the sleeve 136 during displacement of the tensioning body 124 in the direction of arrow E (anti-clockwise). In use, the operation of the clutch assembly 132 to the locked condition typically occurs when the body 124 is displaced in the direction of arrow D to axially stretch and tighten the nut 6 as will be discussed below. Conversely, in the activated condition, in use, the disk 135 is free to rotate about its axis, or is freely displaceable, in the direction of arrow E. In use, the operation of the clutch assembly 132 to the activated condition typically occurs when the body 124 is displaced in the direction of arrow E.

The clutch elements 138 may interferingly be displaceable within zones defined by the sleeve 136 and the clutch disk portions 135.1 to facilitate operation of the one way clutch between the locked and activated conditions. To this end, the cutaway portions 135.1 are tapered or have smaller cross-sectional areas in locations away from the direction of arrow E (when viewed from above) such that the elements effectively interferingly engage with the sleeve 136 and the disk 135 thereby locking the rotation of the disk 135 in the direction of arrow D.

It will be understood that, in use, displacement of the tensioning body 124 in the direction of arrow D under load conditions operates the clutch assembly 132 to the locked condition and displacement of the body 1 24 in the direction of arrow E operates the clutch assembly 132 to the activated condition. It is in the locked condition that displacement of the body 124 causes the clutch assembly 132 to be displaced relative to the friction bush 127. In particular, the sleeve 136 is frictionally displaced relative to the bush 127 when the clutch assembly 132 is in the locked condition and the body 124 is displaced in the direction of arrow D.

The clutch disk 135 and the nut rotating socket 130 may engage with each other via suitable grooves 135.2 and castellations 130.1 which allow for a degree of play before actuation of the clutch assembly 132 to a locked and/or activated conditions. Male castellations 130.1 are smaller in dimension than the grooves 135.2 to allow for a slight degree of play before the socket 130 operatively engages the disk 135.

In the present example embodiment of the device 100, the tensioning body 124 comprises a retaining member 125 which removably attaches to the body 124 thereby locking the arrangement 126 in the chamber of the body 124. The member 125 may comprise screw-threading on an outer surface for operative engagement with complementary screw-threading provided in the chamber of the body 124. It will be noted that in the example embodiment illustrated, the member 125 is attachable to the base 20 via the ball plungers 30. To this end, the member 125 defines the circumferentially extending groove 124.4 for location of the ball plungers 30. Moreover, the member 125 defines the operative surface or face 124.3 which interfaces with the thrust washer 22. The body 124 may also advantageously comprise a tool attachment portion 150 which may be used for attachment to a suitable tool such as a torque wrench and or spanner

In assembly, referring to Figures 5 to 8 of the drawings, the thrust washer 22 is attached to the base portion 20 in an immovable fashion via one or more pins 28 through aligned apertures provided on said components.

The friction bush 127 is press fitted into the seat provided in the chamber 134. The elements 138 are located in the portions 135.1 of the disk 135 and is located in the sleeve 136. To this end, the sleeve may be in a two-piece construction to facilitate ease of construction. The assembly 132 is then located within the bush 127 such that they are co-axially arranged.

The nut engaging socket 130 is located in a cradle defined by the retaining member 125 and the member 125 is screwed into place in the body 124 such that the male castellations 130.1 are brought into location with the grooves 135.2. the nut engaging socket 130 has an end opposite the castellations 130.1 which is shaped and/or dimensioned for operative engagement with the nut 6.

The retaining member 125 is attached to the base portion 20 such that the surface 124.3 of the member 125 rests on and effectively abuts the thrust washer 22, and the ball plungers 30 are operatively located in the groove 124.4. In this way, the body 124, as well as the arrangement 126 located in the chamber 134, are restrained from displacement, and thus disengagement from the base portion 20, in the axial direction A with at least the body 24 being free to rotate in the transverse directions D & E. It will be appreciated that the mating surfaces between the member 125 and the thrust washer 22 may be lubricated via a suitable lubricant prior to assembly as described herein. In use, referring again to Figures 5 to 8 of the drawings, the operation of the device 100 is very similar to the operation of the device 10 in that the device 100 is turned down over the bolt/stud 2 located in the object 4 until the arrangement 126 operatively engages the nut 6 and the base portion 20 rests on a surface of the object 4 shouldering the nut 6.

Turning of the body 124 under load with a predetermined torque causes axial stretch of the bolt/stud 2 and automatic and/or simultaneous tightening of the nut 6 with a torque value which is less than the torque applied to the body 124.

It will be noted that with a nut 6 operatively engaged by the socket 125, the bolt/stud 2 by the member 1 12, and the member 1 12 operatively located in the body 124, rotation of the tensioning body 124 in the direction of arrow D by way of a torque wrench and or suitable spanner attachable to the nut 150 causes the body 124 to rotate under load relative to the base portion 20 and the thrust washer 22. The greatest friction is encountered between abutting surfaces 22.1 and 124.3 in axially stretching the bolt/stud 2 as compared to nut 6 and bolt/stud 2 friction encountered between the nut 6 and bolt/stud 2. The force or toque applied to bring about rotation of the body 124 may be selected so that it is sufficient to overcome the friction between the bush 127 and the sleeve 136 as well as cause desired axial stretch of the bolt/stud 2. Overcoming friction between the bush 127 and the sleeve 136 may be frictional slippage between these parts. Differently defined, the co-friction of friction and/or the material selected for the bush 127 may be based on the amount of torque and/or force required to axially stretch the bolt/stud 2.

Moreover, as the body 124 rotates about the central axis X in the direction of arrow D with the free end of the bolt/stud attached to the screw-threading provided in the bore 132 of the body 124, the socket 130, with the nut located therein, engages the clutch assembly 132. In particular, the castellations 130.1 or other suitable engaging formations of the socket 130 engage the clutch disk 135 or the grooves 135.2 with a slight degree of play before operating the clutch assembly 132 to the locked condition whilst force/torque is applied in the direction of arrow D on the body 124. In the locked condition, the clutch disk 135 is locked against rotation within the sleeve 136 about its axis and thus assembly 132 rotates frictionally about its axis as a singular unit relative to the friction bush 127. The sleeve 136 moves relative to the friction bush whilst abutting said friction bush 127 during rotation of the tensioning body 124 in the direction of arrow D which causes the socket 130 to turn the nut with a reduced torque than the torque applied to the turn the body 124.

In this way, the bolt/stud 2 is axially stretched and the nut 6 is simultaneously and/or automatically turned about the axially stretched nut with a lower torque than the torque applied to the body 124. It will be noted that arrangement 126 turns the nut 6 with a lower torque which is derived from the torque applied to the tensioning body 124 to tension the bolt/stud 2.

Similarly as herein, once desired bolt stretching has been achieved, the member 1 12 is removed from the bolt/stud 2 and the body 124 with its components are removed. In particular, rotation of the body 124 in the direction of arrow E causes the socket 130 to operate the clutch assembly 132 to the activated condition in which the clutch disk 135 is freely rotatable relative to the sleeve 136 thus enabling the device 100 to be unscrewed from the bolt/stud 2 in the direction of arrow E without undoing the tightened nut 6. The device 100 is also thus a removable device for tightening a nut that completely eliminates risk of galling occurring between the elongate member and nut.

It will be noted that loosening of the nut/undoing the bolt/stud 2 stretch may be achieved with conventional tools such as hand wrenches. The present invention provides a means to achieve bolt/stud stretching mechanically by using torqueing techniques which reduce nut face friction thereby at least addressing the problems highlighted above. Moreover, the present invention improves torque accuracy and improves joint integrity by reducing the likelihood of slipping between threads (self loosening). Most importantly, the present invention also prevents and/or reduces galling between the nut and bolt on Stainless Steels, Aluminium and Titanium fastening applications. The device disclosed herein may essentially be a toque device that is a tool that eliminates any risk of galling, as well as eliminating the requirement to lubricate the said elongate member & nut as compared to conventional approaches.

Claims

1 . A removable mechanical tensioning device for stretching an elongate member in an axial direction, the elongate member being located in and attachable to an object via a nut, wherein the tensioning device is attachable to the elongate member in a removable fashion and defines an interior within which the elongate member and nut are locatable, in use, wherein the tensioning device comprises or is operatively coupled to a nut engaging assembly configured to engage the nut in the interior of the tensioning device, in use, such that displacement of at least a transversely displaceable part of the tensioning device in a transverse direction, transverse to the axial direction, causes stretch of the elongate member in the axial direction, and automatic actuation of the nut engaging assembly to bring about displacement of the nut in the transverse direction relative to the stretched elongate member with a torque and/or force which is lower than torque and/or force applied to the bring about operative displacement of the transversely displaceable part of the tensioning device to cause axial stretch of the elongate member.

2. A device as claimed in claim 1 , wherein the nut engaging assembly is configured to displace the nut in the transverse direction automatically and/or simultaneously with stretching of the elongate member.

3. A device as claimed in either claim 1 or 2, wherein the lower torque applied by the nut engaging assembly to bring about displacement of the nut is derived from the torque applied to displace the transversely displaceable part of the tensioner device in the transverse direction.

4. A device as claimed in any one of the preceding claims, wherein the device has a central axis and comprises: a base portion; a friction element; and a tensioning body attached to the base portion while abutting the friction element, wherein the tensioning body is freely displaceable in the transverse direction relative to the base portion and the friction element in a frictional fashion, at least in use.

5. A device as claimed in claim 4, wherein the tensioning body is the transversely displaceable part of the tensioner device which is transversely displaceable, in use, in response to an applied torque, wherein the nut engaging assembly is automatically and/or simultaneously actuated as a result of operative cooperation between the nut engaging assembly and the tensioning body during displacement of the tensioning body, in use.

6. A device as claimed in either claim 4 or claim 5, wherein under load conditions, with the tensioning device operatively attached to the elongate member and the base portion abutting a surface adjacent the nut, the nut engaging assembly operatively engages the nut, wherein displacement of the tensioning body in the transverse direction causes stretch of the elongate member in the axial direction; and actuation of the nut engaging assembly.

7. A device as claimed in any one of claims 4 to 6, wherein the tensioning body extends between first and second end portions and defines a bore having an axis aligned with the central axis of the tensioning device, and a chamber in communication with the bore, wherein chamber is shaped and/or dimensioned to house all or a part of the nut engaging assembly.

8. A device as claimed in claim 7, wherein the chamber is located at the second end portion and the first end portion is a tool end portion attached or engageable with a suitable tool.

9. A device as claimed in either claim 7 or 8, wherein the first end portion of the tensioning body comprises or defines engaging formations within the bore thereof for engaging complementary engaging formations on an outer surface of the elongate member, in use, thereby to engage and attach the tensioning device to the elongate member, in use.

10. A device as claimed in any one of claims 7 to 9, wherein the tensioning body is attached to the base portion adjacent the second end portion thereof.

1 1. A device as claimed in any one of claims 7 to 10, wherein the base portion defines an aperture aligned with the central axis for receiving the elongate member and nut, and locating the same operatively in the bore and chamber of the tensioning body, respectively.

12. A device as claimed in any one of claims 7 to 1 1 , wherein the friction element is, at least in part, sandwiched between the tensioning body and the base portion such that the second end portion of the tensioning body defines a surface which abuts the friction element when the tensioning body is attached to the base portion.

13. A device as claimed in any one of claims 4 to 12, wherein the friction element is attachable to the base portion and defines an aperture aligned with the central axis.

14. A device as claimed in any one of the preceding claims, wherein the nut engaging assembly comprises a resilient nut engaging member adapted to engage the nut, in use, wherein the resilient nut engaging member co-operates with the displaceable part of the tensioner device during displacement thereof in the transverse direction to cause loading of the resilient nut engaging member which causes displacement of the nut with a lower torque than the torque applied to the transversely displaceable part of the tensioner device, in the transverse direction relative to the stretched elongate member upon release of said loading.

15. A device as claimed in claim 14 when dependent on any one of claims 4 to 13, wherein the resilient nut engaging member is operatively arranged with the base portion and/or the tensioning body such that, in use, the displacement of the tensioning body in the transverse direction causes loading of the resilient nut engaging member and automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member.

16. A device as claimed in either claim 14 or 15, wherein the device comprises a load arrangement to cause operative engagement of the tensioning body and the resilient nut engaging member, in use, under load conditions to facilitate the loading of the resilient nut engaging member, wherein the resilient nut engaging member is freely displaceable in the transverse direction under non-load conditions but under load conditions, the load arrangement operates to allow operative engagement between the tensioning body and the resilient nut engaging member to facilitate loading of the latter.

17. A device as claimed in any one of claims 14 to 16, wherein the resilient nut engaging member comprises a load release mechanism to release the loaded resilient nut engaging member causing displacement thereof thereby to displace the nut in the transverse direction, in use.

18. A device as claimed in claim 14 when dependent on any one of claims 4 to 12, wherein the resilient nut engaging member is operatively arranged with the base portion and/or the tensioning body such that, in use, the displacement of the tensioning body in the transverse direction causes loading of the resilient nut engaging member and automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member.

19. A device as claimed in any one of claims 14 to 18, wherein the resilient nut engaging member is in the form of a resilient spring-like member extending between a first end portion and a second end portion, wherein a bore having an axis aligned with the central axis is provided therethrough.

20. A device as claimed in claim 19, wherein the first end portion of the resilient member defines engaging formations to attach the resilient nut engaging member to the tensioning body so as to allow free displacement thereof in the transverse direction under non-load conditions.

21. A device as claimed in either claim 19 or 20 when dependent on any one of claims 7 to 12, wherein the resilient nut engaging member comprises one or more radially extending flanges adjacent the first end portion thereof for location in a suitable circumferentially extending notch provided in the chamber of the tensioning body.

22. A device as claimed in any one of claims 1 to 13 wherein the nut engaging assembly comprises a clutch arrangement configured to engage the nut and displace the nut in the transverse direction with a lower torque than the torque applied to the transversely displaceable part of the tensioner device.

23. A device as claimed in claim 22 when dependent on any one of claims 4 to 13, wherein the clutch arrangement is configured to engage with a friction body located in the tensioning body and/or the base portion, and the nut, in use, such that interaction of the clutch arrangement and the friction body during the displacement of tensioning body in the transverse direction causes displacement of the nut with a lower torque than that applied to the tensioning body.

24. A device as claimed in claim 23, wherein at least one part of the clutch arrangement is freely displaceable relative to the tensioning body and/or the base portion in the transverse direction.

25. A device as claimed in any one of claims 22 to 24 when dependent on any one of claims 7 to 12, wherein the clutch arrangement is located in the chamber of the tensioning body.

26. A device as claimed in claim 25 when dependent on claim 23, wherein the friction body is the form of a friction bush located in a seat provided within the chamber of the tensioning body.

27. A device as claimed in claim 23, wherein the clutch arrangement comprises: a nut rotating socket; and a one way clutch assembly which interfaces with the friction body and co-operates with the nut rotating socket such that, in use, application of torque to bring about displacement of the displaceable part of the tensioner device in the transverse direction causes the one way clutch assembly to be operated to a locked condition in which it is frictionally displaceable relative to the friction body only so as to limit the torque applied to the nut located operatively in nut rotating socket to a lower value than that of the torque applied to the displaceable part of the tensioner device.

28. A device as claimed in claim 27, wherein displacement of the tensioning body in a direction opposite to the transverse direction, in use, causes the one way clutch assembly to be operated to an activated condition which permits free displacement of the nut rotating socket and/or the tensioning body relative to the clutch assembly.

29. A device as claimed in claim 28, wherein the one way clutch assembly comprises a clutch disk locatable in and displaceable within a sleeve, wherein the clutch disk comprises one or more peripheral apertures within which clutch elements are locatable, wherein the clutch elements facilitate operation of the one way clutch assembly between the locked and activated conditions, wherein in the locked condition the clutch disk is locked against displacement within the sleeve, and wherein in the activated condition the clutch disk is freely displaceable within the sleeve.

30. A device as claimed in claim 29, wherein the clutch elements are interferingly displaceable within zones defined by the sleeve and the clutch disk to facilitate operation of the one way clutch.

31. A device as claimed in any one of claims 7 to 12, wherein the tensioning body comprises a retaining member to retain the nut engaging assembly in the chamber of the tensioning body, wherein the retaining member defines the surface of the tensioning body which abuts the friction element when the tensioning body is attached to the base portion.

32. A device as claimed in claim 8, wherein the tool end portion comprises a nut engageable with a suitable tool.

33. A method for stretching an elongate member in an axial direction mechanically, the elongate member being located in and attachable to an object via a nut, wherein the method comprises: attaching a tensioner device over the elongate member and the nut such that a base of the tensioner device rests on the object and a nut engaging assembly of or coupled to the tensioner device engages the nut; displacing the tensioner device in a transverse direction, transverse to the axial direction, such that the tensioner device is wound down on the elongate member and a base portion thereof abuts the object, and a nut engaging assembly of or coupled to the tensioning device is operatively engaged with the tensioning body and/or the nut; and displacing a transversely displaceable part of the tensioning body in the transverse direction under load conditions to cause stretch of the elongate member in the axial direction; and automatic actuation of the nut engaging assembly to bring about displacement of the nut in the transverse direction relative to the stretched elongate member with a torque and/or force which is lower than torque and/or force applied to the bring about operative displacement of the transversely displaceable part of the tensioning device to cause axial stretch of the elongate member.

34. A method as claimed in claim 33, wherein the nut engaging assembly is actuated by co-operation with the tensioning body under load conditions with the nut operative engaged thereby.

35. A method as claimed in either claim 33 or claim 34, wherein the method comprises turning the nut about the elongate member prior to the use of the tensioning device.

36. A method as claimed in any one of claims 33 to 35, wherein once a desired loading of the elongate member has been achieved, the method comprises removing the device from engagement with the elongate member and nut.

37. A method as claimed in any one of claims 33 to 36, wherein the method comprises: displacing the device in a transverse direction, transverse to the axial direction, such that the base portion abuts the object, particularly the surface of the object adjacent the nut and the resilient nut engaging member is operatively engaged with the tensioning body and the nut; and displacing the tensioning body in the transverse direction under load conditions to cause stretch of the elongate member in the axial direction; and loading of a resilient nut engaging member to cause automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member.

38. A method as claimed in any one of claims 33 to 36, wherein the method comprises: displacing the device in a transverse direction, transverse to the axial direction, such that the base portion abuts the object, particularly the surface of the object adjacent the nut, and the clutch arrangement is operatively engaged with the nut; and displacing the tensioning body in the transverse direction under load conditions to cause stretch of the elongate member in the axial direction; and actuation of the clutch arrangement to cause automatic and/or simultaneous displacement of the nut in the transverse direction relative to the stretched elongate member.