WO2015081365A1

WO2015081365A1 - Reinforcing couplings and their manufacture

Info

Publication number: WO2015081365A1
Application number: PCT/AU2013/001406
Authority: WO
Inventors: Tony MANDILE; Timothy COWDERY; Norbert Schauer
Original assignee: Monkey Bar Couplers Pty Ltd
Priority date: 2013-12-03
Filing date: 2013-12-03
Publication date: 2015-06-11

Abstract

A termination for a reinforcing bar shaft is disclosed having a body including an engagement face, the engagement face adapted to incorporate profiled formations arranged to interfit with a complementary shaped termination to resist movement in the longitudinal direction. In one form, at least one datum is located in a surface of the body. In one form, the termination includes a rear face opposite the engagement face having a recess therein. A chuck assembly for supporting a termination for a reinforcing bar shaft is also disclosed. The chuck assembly is configured to support the termination so as to facilitate a correct angle of connection between the termination and the reinforcing bar shaft during manufacture and comprises one or more removable insert sections configured to be mounted on a static jaw of the chuck and, in use, to contact a surface of the termination to support the termination.

Description

REINFORCING COUPLINGS AND THEIR MANUFACTURE

Technical Field The present disclosure relates generally to reinforcing for concrete or other

cementitious construction. In particular, the disclosure is directed to the coupling of reinforcing bars for reinforcing concrete and the manufacture of such couplings and the disclosure is herein described in that context. However, it is to be appreciated that the disclosure has broader application and may be utilised in the coupling of a reinforcing bar to other rigid objects such as metal plates or the like or for the coupling of other rigid bars.

Background In the construction industry, structures (such as walls, floors, slabs and columns) of concrete are produced by positioning reinforcing such as steel reinforcing bars in a region where concrete is then poured to produce the structure. The bars are supported in desired positions and often there is a need to join length of bars to each other to ensure that the reinforcing not only is correctly positioned, but is able to transmit load across the coupling so that the bars can accommodate a large part or even their full axial capacity in either tension or compression.

In the past, wire ties or wraps have been secured around overlapping ends of adjacent bars to hold them relative to one another prior to the concrete pour.

Axial loads are transferred from one bar to the other overlapped bar through the concrete encasing the two joined bars. This method uses more bar than necessary as the overlapped length of bar is only useful to effect the transfer of axial loads and these overlapping lengths can form a significant mass of reinforcing bar in a structure. In another arrangement, bars are formed with short externally threaded end portions and a sleeve with left handed and right handed internal thread portions is used to allow adjacent end of the bars to be connected to one another.

The formation of the external threaded portions on ends of the bars results in those ends being of less diameter than the remainder of the bar and thus is undesirable since engineering requirements may dictate that a bar having a predetermined diameter is used. One way to overcome this difficulty is to employ oversized bars. This ensures that the threaded end of the bar is still of a diameter equal to or greater than the diameter dictated by the engineering requirements. However, with this arrangement, most of the bars are of a gauge greater than is necessary.

Ideally the properties of the coupling, such as its axial capacity and its ductility, are at least the same as the major portion of the bars and that only limited longitudinal slip will occur when the coupling is loaded. If these properties are not within certain tolerances, then the coupling can significantly compromise the resulting structure. For example, if there is excessive longitudinal slip then this can cause excessive localised cracking thereby heightening the risk of corrosion, and may also cause excessive deflection.

The use of a threaded arrangement requires for there to be some play between the components to enable easy installation, which in turn may result in unacceptable longitudinal slip under load. Also there is an ongoing risk that the couplings are not adequately tightened on site which will compromise the coupling.

In International application WO 2006/094320, a reinforcing bar is disclosed which includes an enlarged termination integrally formed on the reinforcing bar shaft. The termination is profiled to include locking formations that enable the termination to form part of an interlock and is disclosed as been made by deforming an end of the reinforcing bar. A process of forming the reinforcing with the profiled termination is disclosed in International application WO 2006/084321, where the reinforcing bar end is subjected to various forging and milling stages.

Whilst the reinforcing disclosed in these earlier applications performs well, the specialised equipment required to manufacture the reinforcing provides a constraint to distributed manufacture of the product in view of the necessary capital outlay for that equipment. Accordingly, alternative modes of manufacturing the reinforcing are desirable.

An alternative mode of manufacturing the reinforcing with coupling terminations is disclosed in International application WO2010/051594 where rather than make the termination from a deformed end of the reinforcing bar, the termination is made as a separate casting and is bonded to the end of a reinforcing bar by a friction welding process. Whilst this later approach has the advantage of reducing the use of specialised equipment and allowing more distributed manufacture, the ability to make a product of consistent quality and in a cost effective manner, particularly where at least part of the product assembly may be done on-site, remains problematic. A reference herein to prior art is not an admission that the prior art forms part of the common general knowledge of a person of ordinary skill in the art in Australia or elsewhere.

Summary

In a first aspect, a termination for a reinforcing bar shaft is disclosed. The termination includes a body incorporating an engagement face that is adapted to incorporate profiled formations arranged to interfit with a complementary shaped termination to resist movement in the longitudinal direction. The termination further includes at least one datum located in a surface of the body.

In a second aspect, a termination for a reinforcing bar shaft is disclosed, the termination having a body, at least one surface of the body incorporating an engagement face, the engagement face adapted to incorporate profiled formations arranged to interfit with a complementary shaped termination to resist movement in the longitudinal direction, the termination further comprising a rear face opposite the engagement face including a recess therein.

In a third aspect, a chuck for supporting a termination for reinforcing is disclosed, the chuck being configured to support the termination so as to facilitate a correct angle of connection between the termination and a reinforcing bar shaft during manufacture. The chuck includes a static jaw; and an insert section configured to be mounted on the static jaw and to contact at least one reference surface of the termination to support and align the termination in use. The chuck further includes one or more moveable jaws configured to retain the termination in position with respect to the insert.

The incorporation of the at least one datum in the termination can significantly improve the ease of manufacture and quality of the resultant reinforcing coupling. The at least one datum may be included in an early stage of manufacture of the termination (for example on casting or otherwise forming a termination blank) and can then be used in subsequent steps of manufacture where the product needs to be made to a tight tolerance (for example in forming the engagement face and/or connecting the termination to a reinforcing shaft).

The chuck of the third aspect utilises one or more reference surfaces (which may be the at least one datum of the first aspect or another part of the termination manufactured utilising the datum) and an insert section to allow for accurate alignment during connection which in turn can facilitate on-site accurate connection of the termination to reinforcing bar shaft. In one form, a reference axis of the termination that extends between first and second ends of the termination is aligned with an axis of the reinforcing bar. The alignment of these axes reduces eccentric loading on the termination so as to maintain axial loading at the interlock on tensioning of the reinforcing bar. In another form, the termination may be arranged to be offset to the bar axis if required.

In the context of the specification, "axial loading" means loading that is applied in the direction that the termination extends so that the interlock is in tension or compression. Further, the term "interlock" means an arrangement where components are connected together in a manner that prevents separation under load in at least one direction, even if the components are free to separate under load in another direction.

In one form, the termination is fused to the shaft to form the permanent connection. In one form, a forging operation is used to bond the termination to the reinforcing bar. In one form, the bond is formed by welding.

In a particular form, the termination is friction welded to the shaft. Friction welding involves a process where two components are forced together (under a friction or forge force) and are heated by mechanical friction of one component rubbing against the other (typically by rotating one component whilst holding the other component stationary). The heating by mechanical friction continues for sufficient time until the material softens and some shortening (upset) of the components occur under the friction force. The rotation driving force is then discontinued but the friction force is maintained or increased to fuse the materials together. Technically, because no melt occurs, friction welding is not actually a welding process in the traditional sense, but a forging technique. An advantage of friction welding is that because of the direct heat input at the weld surface, it gives rise to relatively small heat affected zones. Also as there is no melting, no solidification defects occur. The resulting joints are of forge quality, with a complete butt joint weld through the contact area.

Description of the Drawings

Embodiments will now be described by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a perspective view of one embodiment of a termination of the present disclosure;

Fig. 2 is a side view of the termination of Fig. 1 ;

Fig. 3 is a top plan view of the termination of Fig. 1;

Fig. 4 is a bottom view of the termination of Fig. 1;

Fig. 5 is an end view of the termination of Fig. 1;

Fig. 6 is a front view of a coupling tool for holding the termination in a broaching machine;

Fig. 7 is a section view along section line A-A of the tool of Fig. 6;

Fig. 8 is an insert for the tool of Fig. 6;

Fig. 9 is a perspective view of a second embodiment of a termination of the present disclosure;

Fig. 10 is a side view of the termination of Fig. 9;

Fig. 11 is a bottom plan view of the termination of Fig. 9;

Fig. 12 is a perspective view of a third embodiment of a termination of the present disclosure;

Fig. 13 is a bottom plan of the termination of Fig. 12;

Fig. 14 is a side view view of the termination of Fig. 12;

Fig. 15 is a section view along section line B-B of the termination of Fig. 12;

Fig. 16 is a perspective view of reinforcing showing a termination of the reinforcing on a reinforcing bar end;

Fig. 17 is a front view of one embodiment of a chuck of the present disclosure with a termination of Fig 1 mounted thereon;

Fig. 18 is a cross section along section line C-C of the chuck of Fig. 17;

Fig. 19 is the cross sectional view of Fig. 17 with a different inserts and size of termination incorporated therein; Fig. 20 is an exploded perspective view of a coupling using the termination of Fig. 1; and,

Fig. 21 is a perspective view of the coupling of Fig. 20. Detailed Description

In the following detailed description, reference is made to accompanying drawings which form a part of the detailed description. The illustrative embodiments described in the detailed description, depicted in the drawings and defined in the claims, are not intended to be limiting. Other embodiments may be utilised and other changes may be made without departing from the spirit or scope of the subject matter presented. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the drawings can be arranged, substituted, combined, separated and designed in a wide variety of different configurations, all of which are

contemplated in this disclosure.

The reinforcing and coupling system disclosed is based on the system disclosed in in International application WO2010/051594 (the rights in which were assigned to the Applicant) where the termination is made as a separate casting and is connected to the end of a reinforcing bar by a friction welding process. The contents of

WO2010/051594 are herein incorporated by cross reference.

Ideally the properties of a reinforcing coupling in steel reinforcing of concrete structures, such as its axial capacity and its ductility, are at least the same as the major portion of the bars and that only limited longitudinal slip will occur when the coupling is loaded. If these properties are not within certain tolerances, then the coupling can significantly compromise the resulting structure. For example, if there is excessive longitudinal slip then this can cause excessive localised cracking thereby heightening the risk of corrosion, and may also cause excessive deflection. If the coupling is not as ductile as the main part of the bar, then this can cause localised stress concentration which potentially could result in catastrophic failure of the coupling.

To achieve the required properties, the terminations used in the reinforcing coupling and the properties of the connection of the termination to the reinforcing bar (such as its strength and alignment) need to be within tight tolerances. This therefore requires precision manufacture. However, the construction industry is competitive and, as a result, the cost of manufacture is an important consideration. Also transportation of product is a major issue due to the cost, and the importance of timely supply. The need for onsite variations to products is another major consideration. Therefore on-site or near-site assembly is preferred. Both the cost pressure and the desire for a distributed assembly are problematic for precision manufacture.

Disclosed is a termination for a reinforcing bar shaft, the termination having a body, at least one surface of the body incorporating an engagement face, the engagement face adapted to incorporate profiled formations arranged to interfit with a complementary shaped termination to resist movement in the longitudinal direction, and at least one datum located in a surface of the body.

In some forms, the at least one datum facilitates correct positioning of the profiled formations on the engagement face during manufacture.

In some forms, the at least one datum is positioned in a face other than the engagement face. In some forms, the at least one datum is positioned in a rear face located opposite the engagement face. In some forms, the at least one datum extends into the surface of the body. In at least some forms a datum surface of the at least one datum is positioned internal to the body.

In some forms, at least three datums are provided on the body. In some forms, the body is shaped so as to facilitate engagement of the at least one datum on a reference surface in a subsequent manufacturing process of the termination or reinforcing.

In some forms, the subsequent manufacturing process is the forming of the profiled formations on the engagement face. In some forms this manufacturing process is a broaching process.

In some forms, the body comprises the engagement face, a rear face located opposite the engagement face, and side faces that extend between said engagement face and the rear face and wherein the side faces taper outwardly towards the rear face to facilitate engagement of the at least one datum on the reference surface. In some forms the side faces taper between 5 degrees and 8 degrees.

Also disclosed is a termination for a reinforcing bar shaft, the termination having a body, at least one surface of the body incorporating an engagement face, the engagement face adapted to incorporate profiled formations arranged to interfit with a complementary shaped termination to resist movement in the longitudinal direction, the termination further comprising a rear face opposite the engagement face including a recess therein.

In some forms, the recess extends longitudinally along the rear face and is deeper towards a first end than its oppostite second end.

Also disclosed is a method of manufacture of a termination comprising:

locating a termination blank for processing using at least one datum located on the termination; and forming profiled formations on an engagement face of the termination blank when located in position with reference to the at least one datum. In some forms the forming comprises broaching a surface of the termination to form the profiled engagement face.

Also disclosed is reinforcing comprising: a reinforcing bar extending along a portion of the length of the reinforcing; and a termination according to a form as described above extending along an end portion of the reinforcing, the termination being permanently bonded to the reinforcing bar by a friction welding process.

Also disclosed is a chuck assembly for supporting a termination for reinforcing, the chuck assembly being configured to support the termination so as to facilitate a correct angle of connection between the termination and a reinforcing bar shaft during manufacture, the chuck comprising: a static jaw; an insert section configured to be mounted on the static jaw and to contact at least one reference surface of the termination to support and align the termination in use; and at least one moveable jaw configured to retain the termination in position with respect to the insert.

In some forms, the termination is of a form as previously described having at least one datum and the reference surface is formed using the at least one datum. In some forms, the termination has a profiled surface and the reference surface on which the insert section is configured to contact is disposed on the profiled surface.

In some forms, the insert is configured to contact the termination in at least two reference surfaces on the body.

In at least some forms, the insert section is removable. In at least some forms, the insert section is mounted on the static jaw through a single releasable connector. In some forms, the releasable connector includes a threaded shaft

In some forms, the chuck includes a plurality of insert sections, each configured to be mounted on the static jaw and to contact at least one reference surface of the termination to support and align the termination in use. Also disclosed is a chuck assembly for supporting a termination for a reinforcing bar shaft, the chuck assembly being configured to support the termination so as to facilitate a correct angle of connection between the termination and the reinforcing bar shaft during manufacture, the chuck assembly comprising a plurality of removable insert sections configured to be mounted on a static jaw of the chuck and, in use, to contact one or more surfaces of the termination to support the termination.

In some forms, the insert sections are variably sized and/or shaped to allow for the chuck assembly to support a variety of terminations. In some forms, the chuck is as otherwise described with respect to the chuck of the earlier aspect.

In some forms, the chuck is for use in a friction welding machine. Also disclosed is a method of manufacturing a reinforcing bar having a shaft and a termination, the method comprising providing a chuck having a static jaw and a plurality of moveable jaws; mounting an insert section on the static jaw; locating the termination such that the insert section contacts a surface of the termination to support the termination during manufacture; moving the moveable jaws to retain the termination in position with respect to the chuck; and j oining the shaft to the termination. In some forms, the step of joining comprises friction welding.

In some forms, the method further comprises the step of selecting the insert section to correspond with the size or shape of the termination.

In some forms the step of locating the termination comprises locating the termination such that it contacts the insert section in at least two locations. Turning firstly to Figs. 1 to 5, a reinforcing bar termination is shown. The termination 1, which is typically made from steel, comprises a body 10 and a shaft engagement end 1 1 which extends outwardly from a connection end 14 of the body 10. In the illustrated form, the termination is designed for use with a 32 mm reinforcing bar. It is to be appreciated that the termination of the disclosure is not limited to a particular size, rather different sized terminations may be provided to suit different sized reinforcing bars or installation requirements (for example in forming a connection between different sized reinforcing bars would require using the same size termination on both bars such that the smaller reinforcing bar would include an oversized termination) and in some instances the manufacturing process described below cater for interchanging between termination sizes.

The body 10 extends between longitudinally spaced ends, a connection end 1 1 and a terminal end 13. The shaft connection end 1 1 is configured to allow for engagement with a reinforcing bar shaft 101 (Fig.12) at one end of the shaft. In some embodiments engagement between the shaft and the termination 1 is permanent and comprises welding such as, for example, friction welding. It is to be appreciated that the shaft may extend for many metres. The reinforcing bar shafts may be made in continuous lengths and cut to size depending upon the requirements of the job. The shaft may be plain or may be deformed such as, for example ribbed.

The termination 1 is enlarged as compared to the shaft (i.e. it extends radially outwardly from a central axis of the reinforcing bar a greater distance than does the shaft). A transition zone, or step, is provided in of the form of a tapered wall 14 between the end 11 and the main part of the termination body 10. The termination 1 includes a lateral engagement face 15 which is located on a surface 16 of the termination 1. In the illustrated form the engagement face 15 is located on a surface which faces substantially perpendicularly to the longitudinal axis CL of the termination 1 (which extends through the centre of the engagement end 11). This engagement face 15 is profiled to include profiled formations 18 which enable the termination 1 to be coupled with another termination or other object with a

complementary surface to form an interlock (not illustrated in these Figs). The profiled formations 18 in the illustrated form comprise a plurality of spaced apart upstanding projections 19 and a plurality of recesses 20. Primarily the recesses 20 are positioned intermediate the projections 19 such that each recess is positioned between adjacent projections 19. In the illustrated form, the projections 19 of the body 10 step progressively from the terminal end 13 to the connection end 11.

As best illustrated in Fig. 1, each of the projections 19 include opposite side walls 25 which are interconnected by bridging portions 26. With this arrangement, the walls 25 also act as the side walls for recesses 20. Base portions 28 interconnect these adjacent side walls to for the base of respective recesses 20.

The side walls 25 in the illustrated form extend laterally across the entire engagement face 15. Further, the bridging portions 26 and bases 28 are also formed from flat surfaces. As best illustrated in Figs. 2 and 3, each of the side walls 25 which face towards the connection end 14 (and which in use are in contact with another termination in an interlock under tensile loading) is formed from three components. The first component is a bearing surface 29 which is disposed in a mid region of the side wall and which is substantially normal to the termination axis CL. A first transition region 30 is formed at the intersection between that bearing surface 29 and the bridging surface 26. A second transition region 31 extends from the bearing surface 29 to the base portion 28. In general, the termination is designed so that axial loading at the interlock is accommodated through the bearing surfaces which form the primary region of contact between the interengaged terminations. To enable this to occur, clearances are provided in the regions of the first and second transition regions. In the illustrated form, both the first and the second transition regions (30 and 31) incorporate a radius. In the illustrated form the radius of the first transition region 30 is larger than the radius of the second transition region 31 so that when an interlock is formed the clearances are provided in the regions of the radii so that the contact between the interlocked terminations is at the bearing regions.

In the illustrated form the end projection 19 adjacent the terminal end 13 of the bar 10 is wider than the other proj ections. Further, the innermost recess 20 is also wider so as to be able to receive the wider end proj ection 19. This arrangement is provided so as to facilitate proper mating of the terminations in forming the interlock.

Finally, as best illustrated in Fig. 2, the projections are arranged to step downwardly towards the terminal end 13. With this arrangement, the bearing surfaces 29 of the various projections are not axially aligned but rather are at different radial spacings from the axis CL. This is advantageous as it enables a more even distribution of stress through the termination when it is coupled to another termination. As best shown in Figs. 4 and 5, the termination 1 includes a plurality of datums, being in the illustrated form, five datums (40, 42, 44, 46, 48) located on the body 10. Four of the datums (40, 42, 44, 46) are disposed on a rear face 50 of the termination, whereas the fifth datum 48 is disclosed on the face 52 of the terminal end 13. The five datums 40 are positioned and configured to allow for accurate positioning of the termination 1 during manufacture. In particular these datums allow for correct position in three dimensions when disposed in tooling to form the profiled formations 18 on the engagement face 15. The correct location of the termination 1 in the tooling can be referenced relative to the longitudinal axis CL. Specifically, the four datums (40, 42, 44, 46) which are disposed in the region of the four corners of the rear face 50 allow for orientation of the termination both in regard to angular displacement along the longitudinal axis CL and its angular orientation relative to an axis perpendicular to the longitudinal axis CL. The fifth datum 48 allows for accurate positioning along the longitudinal axis CL In use the termination is made initially as a blank which incorporates the datums at precise locations (i.e. within required tolerances) whereas the profiled formations are manufactured only in general form and require further machining (typically by a broaching process) to shape them within tolerance (which is typically ±0.01 mm. The datums 40 allow for accurate positioning of the termination blank produced for this broaching process (as discussed in more detail below). Accuracy of the positioning of the proj ections 19 and recesses 20 is critical to the interlock of the termination 1 within small tolerances.

In the illustrated form of Figs. 1 to 4, the surface of the datums (40, 42, 44, 46, 48) are recessed into the termination body 10 to provide additional protection of the datum surfaces so as to assist in maintaining their integrity throughout the manufacturing process. In the illustrated form a total of five datums are positioned on the body 10 however it will be understood that differing numbers and positioning of datums may be desirable for manufacturing and fall within the scope of the disclosure. The termination l is further configured to be wedge shaped (as best illustrated in Fig. 5). The sides 54, 56 of the body 10 taper outwardly from the engagement face 15 to the rear face 50. In the illustrated form the taper of the body 10 is between 5 and 8 degrees, and preferably at 6 degrees. The taper of the body 10 is designed to work with the datums (40, 42, 44, 46, 48) on the rear face to facilitate positioning and clamping of the termination for manufacturing. In particular the taper assist in drawing the body of the termination blank back onto a reference surface 501of a tool 500 (as shown in Figs. 9 to 1 1) which registers with the four rear facing datums. This drawing action is typically done by a biasing clamp which grips the side faces. As the clamp grips the tapered walls, the taper of the walls causes the terminations to slide back into engagement with the reference surface thereby ensuring that the blank is correctly positioned.

The termination 1 also includes, in the illustrated form, grooves 58 running along the side edges between the rear 50 and side 52, 54 faces. These grooves are arranged to cooperate with a clipping structure (700) to hold the termination in an interlocked condition with another like termination as shown in Fig. 20. Further details on the clipping structure is disclosed in the applicants copending international application entitled "Retaining Clip for Reinforcing" the contents of which are herein incorporated by cross reference. In the arrangement as shown in Figs. 6 to 8, the tool 500 forms part of a broaching assembly to shape the engagement face 15. As best shown in Figs. 6 and 7, the tool 500 is arranged to hold a termination 1 in place and includes a body 502 on which a lower fixed member 503 is mounted. An upper member 504 is mounted to a carriage 505 so as to be slidable relative to the body 502. The upper member is movable under a drive arrangement (which in the illustrated form is a hydraulic piston cylinder assembly 506. The termination is arranged to be installed between the members 503, 504 and is clamped therebetween under operation of the drive arrangement 506. The inner walls 507 and 508 of the members 503 and 504, include tapered surfaces which are complementary to the tapered walls 54, 56 of the termination 1, such that under the clamping action the termination is caused to move back onto the reference surface 501. In the illustrated form, the reference surface forms part of an insert 520 (Fig.8) that is mounted to the body 506. The isert includes raised tabs 521, 522, 523, 524, 525, which register with the five datums (40, 42, 44, 46, 48) on the termination 1 to correctly locate the termination in position in the tool 500. A modified termination is disclosed in Figs. 9 to 1 1, where the termination 60 has a rear face 61 that incorporates at least one datum flush with the surface of that face 61 rather than recessed as disclosed in the termination 1. In the illustrated form, the termination 60 is arranged to utilise specific areas (62, 63, 64, and 65) of the rear face as datum points and these correspond to the positioning of the datumns 40,42, 44, 46 of the termination 1. In this way the termination 60 can use five datum references as provided in the termination 1. An advantage of the termination 60 is that the rear face 61 can be made so as provide a datum at any point on the surface of the rear face 61 thereby increasing the versatility of the termination to be operable with different coupling arrangements for subsequent manufacturing steps of the termination. In other respects the termination 60 is the same as termination 1 described above with reference to Figs. 1 to 5.

A further embodiment of the termination is disclosed in Figs. 12 to 15. The termination 80, includes many of the features of the terminations 1, 60 and like features have been given like reference numerals. In the illustrated form, the termination also has the lateral engagement face 15 which is profiled to include the profiled formations 18 which enable the termination 1 to be coupled with another termination or other structure. A feature of the termination 80, which distinguishes it from the earlier embodiments, is the design of the rear face 82, Whilst the rear face 82 includes the datum regions 48, 62, 63, 64, and 65 (as disclosed in termination 60), it also

incorporates a recess 84 that extends along the majority of the face 82. In the illustrated form, the recess 84 is shaped to progressively deepen from a first end 85 located adj acent the terminal end 13 towards a second end 86 disposed towards the connection end 1 1. The incorporation of the recess may provide a number of benefits including:

· reducing the overall weight of the termination by allowing material to be

removed; • improving the material properties when the termination is cast. By

incorporating the recess the wall thickness of the casting sections become more uniform (the terminations 1, 60 become progressively thicker from the terminal end 13 to the connection end 1 1). When the thickness of a casting is more uniform it is easier to control the material properties;

• the strength of the casting can be more accurately controlled by changing the depth of the recess 84, thereby allowing more control of the strength properties of the termination and resultant coupling including interlocked terminations 80; and

· allowing for more intimate connection of the termination within a concrete

structure as concrete is able to fill the recess 84 when concrete is cast about a reinforcing bar including the termination 80. This enables the termination to become keyed to the hardened concrete structure. Fig. 16 illustrates reinforcing 100 which includes a reinforcing bar 101 having a termination 102 connected to an end of the bar. The termination 102 shown is substantially the same as the termination 60 described above with the exception that it is sized for use on a smaller 24mm diameter bar (rather than a 32 mm bar as is the case for terminations 1, 10). The termination 102 is bonded to the reinforcing bar 101 by a friction welding process.

In the illustrated form, the diameter of the connection end 103 of the termination 101 is generally the same size as the diameter of the bar 101 so that when joined there is a consistent connection bond 104 between those components in the reinforcing 100. This connection bond 104 in the illustrated form is substantially perpendicular to the axis of the reinforcing bar CL. As such the bond is perpendicular to the principal loading condition (axial) of the reinforcing.

In forming the reinforcing 100, the j oin 104 between the termination and the reinforcing bar is made permanent. This has the advantage of making the reinforcing a fully integral unit that obviates the need for any manual assembly of components on site. This both provides for ease of installation and obviates the problem of incorrect fitting of separate couplings. Furthermore, bonding of the components, rather than using a mechanical connection such as a collar swaged onto both components, minimise the components used in the connection, and allows for better control of the join to ensure that the requirements of strength under axial load and ductility are met. In a particular form, the termination and bar are connected by a friction welding process where the two components are forced together (under a friction or forge force) and are heated by mechanical friction of one component rubbing against the other by rotating one component whilst holding the other component stationary. In particular, the bar 101 is held in a non-rotating vice of a friction welding machine, whilst the termination 103 is attached to a rotating chuck. The components 101, 103 are aligned so that the axis of the bar 103 aligns with a reference axis of the termination 103. The components are brought together by relative movement of the vice and the rotating chuck is rotated to cause the termination end 103 to rub against the bar end causing the components to heat. The heating by mechanical friction continues for sufficient time until the metal softens and some shortening (upset) of the components occur under the friction force. The rotation driving force on the chuck is then discontinued but the friction force is maintained or increased to fuse the termination to the bar end. Technically, because no melt occurs, friction welding is not actually a welding process in the traditional sense, but a forging technique. The resulting join is of forge quality and is a complete butt joint weld through the contact area. The friction welding machine requires no special installation requirements, there are no gases generated that need to be exhausted, and the process is easily automated for high production rates. A further advantage is that the ends to be joined do not need to be specially prepared thereby minimising pre- treatment of the components.

A coupling arrangement using the reinforcing bars and couplings as described above has substantial practical benefit.

Typically by incorporating an enlarged end with the profiled engagement face and having the material of the termination the same as the shaft, the strength at the coupling is greater than the bar being joined. In one form, the coupling has a strength of approximately 110% of the strength of the bar although as will be appreciated this could be varied by varying the dimensions of the various components and changing the heat treatment parameters of the castings in the termination.

Also, the normal bearing faces limit the longitudinal slip of the coupling under load. Again tests conducted by the inventor have indicated that there is slip of less than 0.1mm under prescribed loading test conditions (typically under 300Mpa of axial loading). Further, the coupling has a relatively thin profile which is advantageous as it may allow thinner concrete sections to be used in some circumstances whilst still allowing adequate concrete cover to provide over the reinforcing.

The option of preforming the terminations and then subsequently joining those terminations to reinforcing bars, enables the resultant reinforcing to be made without the need for highly specialised equipment, thereby providing flexibility in the manufacture of the product and in particular allows for distributed manufacturing which can reduce transporting and handling costs, and if desired on site manufacture.

However, to ensure correct performance it is necessary that the termination and the reinforcing bar are friction welded in correct alignment. This requires accurate positioning of the components in the friction welding machine. To assist in this alignment a chuck 200 as disclosed in Figs 7 to 9 has been designed to accept the termination 10, 102.

As shown in Figs. 17 and 18 disclosed is a chuck 200 for supporting a termination 10 in position during friction welding.

In the illustrated form, the chuck 200 comprises a static jaw 202 and two moveable jaws 203 which are configured to support the termination 10 in use. The static jaw 202 is configured such that, in the illustrated form, two insert sections 205 and 206 are mounted to the static jaw in use.

The insert sections of the illustrated form comprise a lower insert section 205 and a rear insert section 206. The lower insert section 205 is configured to be mounted on the static jaw 202 and secured there by means of an engagement member 208 in the form of a bolt 209 extending to abut the lower insert section 205. The single engagement member 208 allows for easy removal of the insert section 205 by removal of the bolt 209.

The lower insert section 205 includes a contact surface 212 which is positioned in the illustrated form along the upper edge of that insert section 205. The contact surface 212 is profiled such that in use the termination 10 which is supported by the lower insert section is in contact with the contact surface 212 at two locations. Specifically in the illustrated form, the contact surface 212 is stepped and arranged to contact the two of the bridging faces (designated 26¹ and 26¹¹ for convenience) of the innermost and outermost profiled formations. The multiple contact surfaces enables the angular orientation of the termination 10 to be correctly set such that the termination is not "tipping" forwards or backwards which is the critical orientation . Furthermore the bridging faces 26¹ and 26¹¹ provide accurate reference surfaces as they are formed in the embodiment disclosed as part of the subsequent forming (broaching process) in manufacture of the termination 10. This broaching process utilises the datums (48) thereby enabling the bridging faces 26¹ and 26¹¹ to be formed to a tight tolerance.

The rear insert section 206 is inserted behind the lower insert section 205 and is retained in position in the chuck 200 by the lower insert section 205. The rear insert section 206 abuts a terminal end 13 of the termination 10 to provide support and retention of the termination within the chuck 200 for manufacturing.

The chuck 200 further includes moveable jaws 203 which are adapted to be moved to support and retain the termination 201 in the chuck in use.

The chuck 200 is designed to allow for support of terminations of varying sizes, shapes and configurations. The lower insert section 205 and rear insert section 206 are removable from the static jaw 202 to allow for replacement insert sections to be inserted into the chuck to support differently sized terminations. The insert sections 205 and 206 are removable through removal of the engagement member 208 to allow for quick release and replacement of the insert sections and change of the terminations being supported. This allows for easy mass manufacture of multiple differently sized or shaped reinforcing bars with various terminations. Fig. 19 illustrates the chuck 200 set up for a different size of termination 300 with the associated insert sections 305 and 306 installed. The embodiment has been described as having a single static j aw and two moveable jaws. It will be clear to those skilled in the art that different jaw configurations would fall within the scope of the disclosure. Further, the embodiment has been described as having two insert sections. It will be clear that a single shaped insert section or more than two insert sections would be possible for a working embodiment and would fall within the scope of the disclosure. Further the engagement member 208 has been described as a single bolt. It will be clear that alternative engagement member configurations would be possible and would fall within the scope of the disclosure.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. Variations and modifications may be made to the parts previously described without departing from the spirit or ambit of the invention.

Claims

CLAIMS:

1. A termination for a reinforcing bar shaft, the termination having a body, at least one surface of the body incorporating an engagement face, the engagement face adapted to incorporate profiled formations arranged to interfit with a complementary shaped termination to resist movement in the longitudinal direction, and at least one datum located in a surface of the body.

2. A termination for a reinforcing bar shaft as defined in claim 1, wherein the at least one datum facilitates correct positioning of the profiled formations on the engagement face during manufacture.

3. A termination for a reinforcing bar shaft as defined in claim 1 or 2, wherein the at least one datum is positioned in a face other than the engagement face.

4. A termination for a reinforcing bar shaft as defined in claim 1 or 2, wherein the at least one datum is positioned in a rear face located opposite the engagement face.

5. A termination for a reinforcing bar shaft as defined in any of the preceding claims wherein the at least one datum extends into the surface of the body.

6. A termination for a reinforcing bar shaft as defined in any of the preceding claims wherein a datum surface of the at least one datum is positioned internal to a surface of the body.

7. A termination for a reinforcing bar shaft as defined in any of the preceding claims wherein the termination includes at least three said datums.

8. A termination for a reinforcing bar shaft as defined in any of the preceding claims wherein the body is defined by the engagement face, side faces and a rear face located opposite the engagement face and wherein the side faces taper outwardly from the engagement face to the rear face.

9. A termination for a reinforcing bar shaft as defined in claim 8, wherein the side faces taper between 5 degrees and 8 degrees.

10. A termination as defined in any preceding claim wherein a rear face of the termination disposed opposite the engagement face includes a recess therein.

11. A termination for a reinforcing bar shaft, the termination having a body, at least one surface of the body incorporating an engagement face, the engagement face adapted to incorporate profiled formations arranged to interfit with a complementary shaped termination to resist movement in the longitudinal direction, the termination further comprising a rear face opposite the engagement face including a recess therein.

12. A termination as defined in claim 10 or 11, wherein the recess extends longitudinally along the rear face and is deeper towards a first end than its opposite second end.

13. A method of manufacture of a termination comprising:

locating a termination blank for processing using at least one datum located on the termination; and

forming profiled formations on an engagement face of the termination blank when located in position with reference to the at least one datum.

14. Reinforcing comprising: a reinforcing bar extending along a portion of the length of the reinforcing; and a termination according to any one of claims 1 to 10 extending along an end portion of the reinforcing, the termination being permanently bonded to the reinforcing bar.

15. A chuck for supporting a termination for reinforcing, the chuck being configured to support the termination so as to facilitate a correct angle of connection between the termination and a reinforcing bar shaft during manufacture, the chuck comprising:

a static jaw; an insert section configured to be mounted on the static jaw and to contact a surface of the termination to support the termination in use; and

a plurality of moveable jaws configured to retain the termination in position with respect to the insert.

16. A chuck as defined in claim 12, wherein the termination has a profiled surface and the insert section is configured to contact the profiled surface in use.

17. A chuck as defined in claim 12 or 13, wherein the insert is configured to contact the termination in at least two locations on the surface.

18. A chuck as defined in any one of claims 12 to 14, wherein the insert section is removable.

19. A chuck as defined in any one of claims 12 to 15, wherein the insert section is mounted on the static jaw through a single releasable connector.

20. A chuck assembly for supporting a termination for a reinforcing bar shaft, the chuck assembly being configured to support the termination so as to facilitate a correct angle of connection between the termination and the reinforcing bar shaft during manufacture, the chuck assembly comprising a plurality of removable insert sections configured to be mounted on a static jaw of the chuck and, in use, to contact a surface of the termination to support the termination.

21. A chuck assembly as defined in claim 17, wherein the insert sections are variably sized and/or shaped to allow for the chuck assembly to support a variety of terminations.

22. A chuck assembly as defined in claim 17, wherein the assembly further comprises a plurality of moveable jaws configured to be moved to retain the termination in use.

23. A chuck assembly as defined in claim 17 or 18, wherein at least one of the removable insert sections is configured to contact a profiled surface of the termination in use.

24. A method of manufacturing a reinforcing bar having a shaft and a termination, the method comprising providing a chuck having a static jaw and a plurality of moveable jaws;

mounting an insert section on the static jaw;

locating the termination such that the insert section contacts a surface of the termination to support the termination during manufacture; moving the moveable jaws to retain the termination in position with respect to the chuck;

joining the shaft to the termination.

25. A method as defined in claim 21, wherein the step of joining comprises friction welding.

26. A method as defined in claim 21 or 22, further comprising the step of selecting the insert section to correspond with the size or shape of the termination.

27. A method as defined in any one of claims 21 to 23, wherein the step of locating the termination comprises locating the termination such that it contacts the insert section in at least two locations.