Load sensing washer and method of use thereof

Abstract

The present invention relates to a load sensing washer. The present invention alleviates provides further ability to monitor the tensioning on a fastening member and / or apparatus.

Description

Load sensing washer and method of use thereof FIELD OF THE INVENTION

[0001] The present invention relates to the field of fastening. Particularly, the present invention relates to the field of fastening components. More particularly, the invention relates to a load sensing washer. BACKGROUND TO THE INVENTION

[0002] Any reference to background art herein is not to be construed as an admission that such art constitutes common general knowledge in Australia or elsewhere.

[0003] Fastening workpieces is important to many different industries. Typically, fastening two or more workpieces require force to apply axial pressure thereto. However, over-application of force can result in buckling of the fastener and thus lead to the workpieces disengaging. Alternatively, under-application of force can similarly lead to an ineffective or failed connection.

[0004] It would be advantageous to provide a method and / or a device for determining the axial pressure applied by a fastening member so that the amount of applied force can be monitored to alleviate the problem of over tensioning or under-tensioning. Furthermore, it would be advantageous to monitor the amount of force being applied over time as this would provide an indication as to whether tension is being lost.

[0005] One problem associated with many of the presently available solutions is that they are only compatible with certain types of fastening methodologies.

[0006] It would be advantageous address one or more of the above issues and / or to provide the consumer with a commercial alternative to the presently available solutions. SUMMARY OF THE INVENTION

[0007] In a first aspect, although it need not be the only or indeed the broadest aspect, the invention resides in a load sensing washer comprising: a body having a first surface and a second surface, wherein the body comprises an aperture extending from the first surface and the second surface; and one or more deformation measurement device(s) being received or formed with the body.

[0008] In one embodiment, the body comprises an outer surface connecting an outer peripheral of the first surface to the outer peripheral of the second surface. In an embodiment, the body comprises an inner surface connecting an inner peripheral of the first surface to the inner peripheral of the second surface. In one embodiment, the body is an annulus.

[0009] In some embodiments, the body comprises a chamfer. In an embodiment, the top of the body is chamfered. In an embodiment, one or both of the junction between the outer surface and the first surface and / or the junction between the inner surface and the first surface is / are chamfered.

[0010] In certain embodiments, the bottom of the body is chamfered. In an embodiment, one or both of the junction between the outer surface and the second surface and / or the junction between the inner surface and the second surface is / are chamfered.

[0011] In embodiments, the outer surface comprises an indent. In some embodiments, the indent is adapted to receive the one or more deformation measurement device(s) and / or a protecting ring. In an embodiment, the outer surface comprises the deformation measurement device. In a preferredembodiment, the indent extends around the outer surface. In one embodiment, the deformation measurement device is formed with the body.

[0012] In an embodiment, the deformation device comprises or is a strain gauge.

[0013] In one embodiment, the one or more deformation devices are equidistant or substantially equidistant to an adjacent deformation device. In one embodiment, the load sensing washer comprises two, three or four deformation devices.

[0014] In one embodiment, the load sensing washer further comprises a protective ring. In a preferred embodiment, the protective ring covers the one or more deformation measurement device(s). In one embodiment, the protective ring is received in the indent. In an embodiment, the protective ring comprises a connection portion adapted to facilitate wired and / or wireless data communication.

[0015] In another aspect, although it need not be the only or indeed the broadest aspect, the invention resides in a fastening assembly for determining an applied load comprising: a fastener comprising an elongate fastening member having a male threaded distal end, optionally a nut device having a female threaded aperture; and a load sensing washer comprising a body having a first surface and a second surface, wherein the body comprises an aperture extending from the first surface and the second surface, and one or more deformation measurement device(s) being received or formed with the body.

[0016] The load sensing washer and components thereof may be as substantially described herein for the first aspect.

[0017] In a further aspect, although it need not be the only or indeed the broadest aspect, the invention resides in a method of determining a load applied to a fastening assembly comprising a fastener, the method including:providing a fastener an elongate fastening member having a male threaded distal end; locating a load sensing washer about the elongate fastening member, the load sensing washer comprising a body having a first surface and a second surface, wherein the body comprises an aperture extending from the first surface and the second surface, and one or more deformation measurement device(s) being received or formed with the body, optionally securing a nut device to the male threaded distal end, tensioning the fastener and / or nut device; determining the load applied to the elongate fastening member by: measuring deformation of the load sensing washer transversely to an axial direction of the elongate fastening member, and determining the load applied to the elongate fastening member from the deformation of the body; to thereby determine the load applied to the fastening assembly.

[0018] The load sensing washer and components thereof may be as substantially described herein for the first aspect.

[0019] The various features and embodiments of the present invention referred to in the individual sections above and in the description which follows apply, as appropriate, to other sections, mutatis mutandis. Consequently, features specified in one section may be combined with features specified in other sections as appropriate.

[0020] Further features and advantages of the present invention will become apparent from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, embodiments of the invention will be described by way of example only with reference to theaccompanying drawings, in which: Figure 1 shows an embodiment of the load sensing washer; Figure 2 shows an exploded view of the load sensing washer; Figure 3 shows a load sensing washer placed on the frontside of a load cell; Figure 4 shows a load sensing washer placed on the backside of a load cell; Figure 5 shows a calibration set up; Figure 6 shows an embodiment of a multi jackbolt tensioner and the calculations of the distance between the load sensing washer and the body of the multi jackbolt tensioner; and Figure 7 shows an enlarged view of the deformation measurement device / strain gauge. DETAILED DESCRIPTION OF THE INVENTION

[0022] Embodiments of the present invention reside primarily in a load sensing washer. Accordingly, the assembly, device, apparatus or method steps have been illustrated in the drawings, showing only those specific details that are necessary for understanding the embodiments of the present invention, but so as not to obscure the disclosure with excessive detail that will be readily apparent to those of ordinary skill in the art having the benefit of the present description.

[0023] In this specification, adjectives such as first and second, upper and lower, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order.

[0024] Words such as “comprises” or “includes” are intended to define a non- exclusive inclusion, such that an assembly, method, article, or apparatus that comprises a list of elements does not include only those elements but mayinclude other elements not expressly including elements that are inherent to such an assembly, method, article, or apparatus.

[0025] As used herein, the term ‘about’ means the amount is nominally the number following the term ‘about’ but the actual amount may vary from this precise number to an unimportant degree.

[0026] The present invention is predicated on, at least, the finding that a load sensing washer can be utilized to determine the axial pressure applied thereto. In this regard, the amount of force applied can be actively monitored to alleviate the problem of over-tensioning or under-tensioning. Additionally, the present invention is also predicated on being able to monitor the amount of axial force being applied over time to provide an indication as to whether tension is being lost. Furthermore, the present invention is predicated on the finding that a load sensing washer can be utilized on either or both of the reacting side and the acting side of the fastener. This advantageously allows for either side of the fastener (the acting side, the reacting side or both) to be accessed for sensing the load on the fastener. In addition to the above, multiple load sensing washers can be utilized with a fastening assembly to provide multiple readings.

[0027] Shown in Figure 1 is an embodiment of a load sensing washer. The load sensing washer 100 comprises a body 110 having a first surface 111 and a second surface 112. In one embodiment, the first surface 111 is in a substantially parallel plane to the second surface 112. In one embodiment, the first surface 111 is in a parallel plane to the second surface 112. That is, the first surface 111 is parallel to the second surface 112. The body 110 further comprises an aperture 116 that extends from the first surface 111 to the second surface 112. In one embodiment, the aperture 116 is centrally located. The body 110 further comprises an outer surface 113 and an inner surface 114. The outer surface 113 connects an outer peripheral of the first surface 111 to the outer peripheral of the second surface 112. The inner surface 114 connects an inner peripheral of the first surface 111 to the inner peripheral of the second surface 112. In one embodiment, the body is an annular body. In an embodiment, the body is an annulus.

[0028] In an embodiment, the sensing washer further comprises one or more deformation measurement device(s) 130 (shown in Figure 7). In a preferred embodiment, the load sensing washer comprises a plurality of deformation measurement devices. In one embodiment, the outer surface comprises an indent which receives the one or more deformation measurement device(s). In another embodiment, the outer surface comprises the one or more deformation measurement device(s). That is, the outer surface is formed with the one or more deformation measurement device(s). In an embodiment, the one or more deformation measurement device(s) is / are formed with the body. Alternatively, or additionally, the indent is suitably adapted to receive a protecting ring (mentioned in more detail hereinafter).

[0029] In one embodiment, the deformation measurement device comprises a strain gauge. A strain gauge is a device utilized to measure the amount of strain on an object by responding to deformation of the object. The measured strain can then be utilized to determine the amount of load (such as axial load) being applied. Non-limiting examples of the strain gauge include electro- resistance strain gauges and optical strain gauges. In the embodiment shown, the outer surface 113 comprises an indent 113’ which receives the one or more deformation measurement device(s) (such as strain gauge). In one embodiment, the indent 113’ extends entirely around the outer surface 113. As mentioned above, the indent 113’ is also suitably adapted to receive a protecting ring.

[0030] In one embodiment, a deformation measurement device may be mounted about, or formed with, the outer surface 113. In this regard, the deformation measurement device may be formed within or on the indent. In this regard, each deformation measurement device can be used to more accurately measure the amount of deformation and thus force applied to the elongate fastening member. In an embodiment, the load sensing washer may comprise one or more indents which each receive or are adapted to receive the one or more deformation measurement device(s) and / or a protecting ring. Alternatively, or additionally, the load sensing washer may comprise one or more deformation measurement devices affixed or secured to the body.

[0031] The load sensing washer comprises a protective ring 120. The protective ring suitably covers the one or more deformation measurement device(s) and alleviates the issue of the one or more deformation measurement device(s) being damaged. The protective ring 120 may also suitably comprise a connection portion adapted to facilitate wired and / or wireless communication with a display or control unit. The connection portion may also be adapted to facilitate wired and / or wireless data communication. In the embodiment shown, the protective ring 120 is provided with a cable connector for facilitate wired communication with a display or control unit. The protective ring allows for the readings of the one or more deformation measurement device(s) to be transmitted to the control unit.

[0032] It will be appreciated that the control unit is adapted to determine the amount of strain / deformation on the load sensing washer and thus assembly based on the information or readings of the one or more deformation measuring device(s). In this regard, the connection portion is adapted to transmit data / information to the display / control unit either in a wired or wireless method.

[0033] In use, the load sensing washer may be utilized with an elongate fastening member or assembly. In one embodiment, the load sensing washer is provided in combination with an elongate fastening member. In this regard, an elongate fastening member may be inserted through aligned apertures in one or more workpiece(s). The elongate fastening member may be formed with a head or body portion that can be tensioned (e.g., a multi jackbolt tensioner or fastener). Either or both end(s) of the elongate fastening member may be provided with the load sensing washer of the present invention. By torquing the multi jackbolt tensioner or fastener, a strong axial force is generated and directed against the workpiece(s). The thrust force of the jackbolts or head and the opposite reaction force of the load sensing washer impose a strong clamping force on the workpiece(s).

[0034] As tension is applied to the elongate fastening member, the load sensing washer 100 is pulled against a workpiece(s) under an axial force. The force applied to the load sensing washer 100 causes the body 110 to elastically deform or deflect. Deflection (circumferential expansion) can be determined bythe deformation measurement gauge and the force being applied can be determined therefrom.

[0035] One advantage of the present load sensing washer is that the deformation thereof can be utilized to more accurately determine the load on the elongate fastening member and workpiece(s). Another advantage of the present invention is that the load sensing washer is not tightened directly, which provides more possibilities of use. In this regard, a consumer can access more joint configurations regardless of tightening method. Typically, the load sensing washer device can be used on any end of an elongate fastening member, and the generation of load can be completed on either the opposing or same end to the load sensing washer by torquing a bolt head or jackbolts. As such, the present load sensing washer allows monitoring and determining the load with tightening methods which include, but not limited to, conventional torque / turn tightening, stud stretching by heat, mechanical tensioning and hydraulic tensioning. This is a significant advantage as it allows for monitoring and determination of load with numerous tightening methodologies. Furthermore, the monitoring of the load on a distal end is generally much more accessible than monitoring the load at the location of torquing. In this regard, it will be appreciated that space will be required to apply force thereto. Furthermore, it will also be appreciated that a number of load sensing washers can be utilized in a fastening assembly to provide sensitivity, multiple readings and information regarding possible failures.

[0036] In an embodiment, the body 110 comprises a chamfer. In one embodiment, the top of the body is chamfered. That is, one or both of the junctions between the outer surface and the first surface and / or the junction between the inner surface and the first surface is / are chamfered.

[0037] In an embodiment, the bottom of the body is chamfered. That is, one or both of the junctions between the outer surface and the second surface and / or the junction between the inner surface and the second surface is / are chamfered.

[0038] It will be appreciated that the chamfered face relative to an adjoining face may be at any angle. In one embodiment, the chamfer angle is between 0º and about 2º. In an embodiment, the body does not comprise a chamfer. In apreferred embodiment, the chamfer may be 2º. It is postulated that the chamfered junction(s) allow for a more pronounced deflection which results in a better monitoring of the deformation and thus strain.

[0039] In one embodiment, the strain gauge is externally located on the body. In an embodiment, the strain gauge is located on the outer surface. In an embodiment, the strain gauge is located on an outer surface of the indent. In one embodiment, the strain gauge is located on the inner surface. In another embodiment, the strain gauge is internally located in the body.

[0040] As mentioned above, the load sensing washer may comprise one or more deformation measurement devices. In one embodiment, the load sensing washer comprises 2, 3, 4, 5, 6, 7, 8…n deformation measurement device(s), where n is an integer above 1. In one embodiment, the load sensing washer comprises two or four deformation measurement devices. In an embodiment, the load sensing washer comprises two or four strain gauges.

[0041] In an embodiment, the one or more deformation measurement device(s) are equidistant or substantially equidistant to one another. For exemplary purposes, in the embodiment where the load sensing washer comprises two deformation measurement devices, the two deformation measurement devices are located at about 180º. In the embodiment where the loading sensing washer comprises four deformation measurement devices, the four deformation measurement devices are located at about 90º apart. In the embodiment where the load sensing washer comprises x (where x is an integer) deformation devices, the x deformation measurement devices are located at about 360º / x apart.

[0042] The present invention may be utilized with a multi jackbolt tensioner (MJT). In an embodiment, the load sensing washer for use with a multi jackbolt tensioner. In one embodiment, the load sensing washer when used with a multi jackbolt tensioner.

[0043] In a preferred embodiment, the load sensing washer is spaced apart from the body of a multi jackbolt tensioner. In an embodiment, the load sensing washer abuts another washer that abuts the body of the multi jackbolt tensioner.Alternatively, or additionally, the sensing washer can be utilized on the reacting side of a stud.

[0044] The inventors have found that if the present load sensing washer is to be utilized with a multi jackbolt tensioner then a spacing may be required between the body of the multi jackbolt tensioner and the load sensing washer. It is believed that a spacing may be required to ensure that an equal load application is placed on the load sensing washer, and it is postulated that the required spacing can be determined from the distance between jackbolt (see Figure 6). For instance, where the angle a is 30º and the distance between jackbolts is 19.5mm, the required spacing between the load sensing washer and the body of the multi jackbolt tensioner is at least 33.8mm to ensure equal load application. As such, a further washer can be utilized between the load sensing washer and the body of the multi jackbolt tensioner.

[0045] Furthermore, the present load sensing washer can be utilized with other force determining means to provide a more accurate measurement of force application. Experimental Section

[0046] The inventors designed and tested six (6):Preload target values (from CY-M36 tensioner): Pretensioning: 2x up to 670kN Calibration: 5 points from 0 – 610kN, Nominal load at 455kN

[0047] The load sensing washers were tested on a 1MN loadcell by loading them on a bolted connection. The load sensing washer was either placed belowa CY-M36 tensioner (front side of see Figure 3) or on the backside of the load cell (see Figure 4).

[0048] The preload target values (from the CY-M36) were pretensioning (2x up to 670kN) and calibration (5 points from 0 – 610kN, nominal load at 455 kN).

[0049] The load sensing washer was then pretensioned and calibrated, and compared the resulting preload with the value displayed on the load cell (Figure 5).

[0050] For consistency, the load sensing washer was utilized on the backside of the load cell, as this is postulated to provide an even load application on the load sensing washer.

[0051] Shown below are the Calibration and Test Results: Test Load Sensing Washer No.1 (external ring)Test Load Sensing Washer No.2 (external ring)Test LoadTest Load

[0052] The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment.

[0053] As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. Accordingly, this invention is intended to embrace all alternatives, modifications and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.

Claims

CLAIMS 1. A load sensing washer comprising a body having a first surface and a second surface, wherein the body comprises an aperture extending from the first surface and the second surface; and one or more deformation measurement device(s) being received or formed with the body.

2. A fastening assembly for determining an applied load comprises: a fastener comprising an elongate fastening member having a male threaded distal end, optionally a nut device having a female threaded aperture; and a load sensing washer comprising a body having a first surface and a second surface, wherein the body comprises an aperture extending from the first surface and the second surface, and one or more deformation measurement device(s) being received or formed with the body.

3. A method of determining a load applied to a fastening assembly comprising a fastener and a nut device, the method including: locating a load sensing washer about the elongate fastening member, the load sensing washer comprising a body having a first surface and a second surface, wherein the body comprises an aperture extending from the first surface and the second surface, and one or more deformation measurement device(s) being received or formed with the body, optionally securing a nut device to the male threaded distal end, tensioning the fastener and / or nut device; and determining the load applied to the elongate fastening member by:measuring deformation the load sensing washer transversely to an axial direction of the elongate fastening member, and determining the load applied to the elongate fastening member from the deformation of the body; ereby determine the load applied to the fastening assembly.

4. The load sensing washer of claim 1, the fastening assembly of claim 2, or the method of claim 3, wherein the body comprises an outer surface connecting an outer peripheral of the first surface to an outer peripheral of the second surface, and wherein the body comprises an inner surface connecting an inner peripheral of the first surface to an inner peripheral of the second surface.

5. The load sensing washer, the fastening assembly, or the method of claim 4, wherein the body comprises one or more chamfer(s).

6. The load sensing washer, the fastening assembly, or the method of claim 4, wherein a top of the body comprises a chamfer.

7. The load sensing washer, the fastening assembly, or the method of any one of claims 4 to 6, wherein one or both of the junction between the outer surface and the first surface and / or the junction between the inner surface and the first surface is / are chamfered.

8. The load sensing washer, the fastening assembly, or the method of any one claims 4 to 7, wherein a bottom of the body comprises a chamfer.

9. The load sensing washer, the fastening assembly, or the method of any one of claims 4 to 8, wherein one or both of the junction between the outer surface and the second surface and / or the junction between the inner surface and the second surface is / are chamfered.

10. The load sensing washer, fastening assembly, or the method of any one of claims 4 to 9, wherein the outer surface comprises an indent.

11. The load sensing washer, the fastening assembly, or the method of claim 10, wherein the indent is adapted to receive the one or more deformation measurement device(s) and / or a protecting ring.

12. The load sensing washer, the fastening assembly, or the method of claim 10 or 11, wherein the indent extends entirely around the outer surface 13. The load sensing washer, the fastening assembly, or the method of claim 11, wherein the protective ring covers the one or more deformation measurement device(s).

14. The load sensing washer, the fastening assembly, or the method of claim 13, the protective ring comprises a connection portion adapted to facilitate wired and / or wireless data communication.

Images