Coupling and coupling method

Abstract

A coupler includes: a first fitting for mounting to a first externally-threaded reinforcement used in concrete construction, the first fitting including a first body having a first internal thread for threadedly inserting the first externally-threaded reinforcement into the first fitting, and a second fitting for mounting the first fitting to a second externally-threaded reinforcement used in concrete construction, the first fitting including a second body having a second internal thread for threadedly inserting the first externally-threaded reinforcement into the first fitting; the first accessory is provided with a second internal thread, and the thread pitch of the second internal thread is thinner than that of the first internal thread; and a plug for threaded connection into the second internal thread for abutting against an end portion of the twisted steel.

Description

Technical Field

[0001] The present invention relates to a coupling including a threaded connection device and to a method of coupling threaded reinforcement bars to form a mechanical connection such as may be used in concrete construction. Background Art

[0002] One form of rebar used in concrete construction includes a continuous coarse external thread. The thread not only serves to form a key connection between the rebar and the concrete, but also enables easy application of a series of complementary accessories to the rebar by engaging the mating threads of the accessories with the mating threads of the rebar. One such threaded rebar is sold by the Ramsetreid division of ITW Australia Pty Ltd., an associated entity of the applicant, under the trade mark "Reidbar". The threads on Reidbar rebar are fairly coarse and have a pitch ranging from 8 mm for a 12 mm diameter rebar to about 16.5 mm for a 32 mm diameter rebar.

[0003] Mainly for cost reasons, internally threaded fittings for mounting on the ends of threaded rebar (e.g. for coupling lengths of rebar in series) tend to be of cast construction, primarily cast iron, with the internal threads formed by sand cores during casting. The internal threads formed in this manner are not formed with the accuracy expected of conventional tapped threads, and furthermore, the external threads on the rebar itself are not formed with particularly high accuracy. As a result, there may not be a particularly tight engagement between the fitting and the rebar, and some slippage between the rebar and the fitting may occur when high loads are applied.

[0004] Slippage of a coupler on a threaded rebar can have serious consequences, and relevant construction standards require that slippage be limited and controlled. This can be difficult to achieve given the large tolerances involved in manufacturing coarse threaded rebar. While slippage can be avoided by filling the interior of the coupler with epoxy mastic, this measure increases the time and cost of installing the coupler to the rebar and is not accepted as a solution by some construction authorities. Other methods include machining metric threads or swaging sleeves on the ends of the rebar. These methods are time consuming, complex and expensive due to the processes and equipment required. Therefore, it is desirable to provide a coupler that can accommodate the loose tolerances of the rebar and minimize slippage of the coupler along the rebar within the required standards.

[0005] The applicant has also determined that existing methods and devices do not allow installation in some situations where the reinforcement cannot be rotated and / or where a gap between two elements must be bridged. It has been determined that it would be advantageous to provide a coupling that enables a coupling to be made between reinforcements in situations where rotation of the reinforcement is prevented or at least limited and that bridges the gap between the reinforcements to be coupled. Summary of the invention

[0006] According to the present invention, there is provided a coupling, the coupling comprising:

[0007] A first accessory, the first accessory being used to be mounted to a first externally threaded steel bar used in concrete construction, the first accessory comprising a first body having a first internal thread for threadably inserting the first externally threaded steel bar into the first accessory;

[0008] The first fitting has a second internal thread having a finer pitch than the first internal thread; and

[0009] A plug is used to be screwed into the second internal thread to abut against the end of the threaded steel bar.

[0010] Preferably, the plug is adapted to be tightened in said second internal thread for applying a preload to said end of said threaded steel bar. More preferably, the plug is frangible at a predetermined torque, which ensures the correct amount of preload. Even more preferably, the plug comprises an engagement structure for rotating the plug relative to the first fitting, and wherein the engagement structure is frangibly connected to the remainder of the plug.

[0011] In a preferred form, the plug has an external thread corresponding to said second internal thread of the first fitting.

[0012] Preferably, the plug includes a stopper to ensure the correct insertion depth of the plug relative to the first fitting, thereby allowing the plug to be tightened after the threaded steel bar is inserted for applying the preload. Alternatively, the plug may not necessarily have a stopper, and as an example, the stopper may be configured in such a way that it is not determined on which component or components the stopper is located. In addition, the stopper may also be fragile so as to be "overcome" to generate the preload.

[0013] Preferably, the connector further comprises:

[0014] A second accessory, the second accessory is used to be installed on a second externally threaded steel bar used in concrete construction, the second accessory comprises a second body, the second body has a first internal thread, and is used to threadably insert the second externally threaded steel bar into the second accessory;

[0015] The second fitting has a second internal thread having a finer pitch than the first internal thread; and

[0016] A second plug is used to be screwed into the second internal thread to abut against the end of the second externally threaded steel bar.

[0017] Preferably, the second fitting is adapted to be threadedly connected to the first fitting. More preferably, the second fitting provides a male thread, the first fitting provides a female thread, and the male thread can be connected to the female thread.

[0018] Alternatively, the first fitting provides a first female thread, the second fitting provides a second female thread, and the coupler further comprises a male threaded stud having a first end for connecting to the first female thread and a second end for connecting to the second female thread.

[0019] It will be appreciated by those skilled in the art that while the preload principle may be used to connect two rebars, in other applications other items such as anchors or threaded connections to a steel structure may be connected to one rebar. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0021] Figure 1 A coupling according to a first example of the present invention is shown;

[0022] Figure 2 A coupling according to a second example of the present invention is shown;

[0023] Figure 3 Shows the installation Figure 1 and Figure 2 Connectors;

[0024] Figure 4 A first example coupler and a second example coupler are shown connected, and a Figure 2 Connectors;

[0025] Figure 5 Shows Figure 4 a perspective view of the coupling shown; and

[0026] Figure 6 A table including example pitch ranges and values ​​is shown. DETAILED DESCRIPTION

[0027] refer to Figures 1 to 6, shows a coupling 10, which includes a first fitting 12 for mounting to a first externally threaded rebar used in concrete construction. The first fitting 12 includes a first body 14 having a first internal thread 16 for threadably inserting the first externally threaded rebar into the first fitting 12. The first fitting 12 also has a second internal thread 18 having a finer pitch than the first internal thread 16.

[0028] The coupling 10 further comprises a plug 20 which is threaded into the second internal thread 18 for abutting against the end of the threaded steel bar.

[0029] The plug 20 is adapted to be tightened in the second internal thread for applying a preload to the end of the threaded steel bar. The plug 20 is fragile at the fragile connection 24 to ensure the correct amount of preload. Figure 3 As can be seen in FIG. 1 , the plug 20 includes an engagement structure 22 for rotating the plug 20 relative to the first fitting 12 , and the engagement structure 22 is frangibly connected to the remainder of the plug 20 via a frangible connection 24 .

[0030] The plug 20 has an external thread 26 which corresponds to the second internal thread 18 of the first fitting 12 .

[0031] The plug 20 includes a stopper 28 to ensure the correct insertion depth of the plug 20 relative to the first fitting 12, thereby allowing the plug 20 to be tightened after the threaded rebar is inserted for applying a preload. The stopper 28 ensures the correct position and ensures the torque transmission required to install the first fitting 12 on the threaded rebar.

[0032] In the example shown in the drawings, the coupler 10 further includes a second fitting 30 for mounting to a second externally threaded steel bar used in concrete construction. The second fitting 30 includes a second body 32 having a first internal thread 34 for threading the second externally threaded steel bar into the second fitting 30. The second fitting 30 has a second internal thread 36 having a finer pitch than the first internal thread 34. The second fitting 30 also includes a second plug 38 for threading into the second internal thread 36 for abutting against the end of the second externally threaded steel bar.

[0033] The second fitting 30 is adapted to be threadedly connected to the first fitting 12. In one example, the second fitting 30 provides a male thread 40 (see Figure 2 and Figure 3 ), the first fitting 12 provides a female thread 42, and the male thread 40 can be connected to the female thread 42, such as Figure 2 as shown in a cross-sectional view.

[0034] Alternatively, in Figure 1 In another example shown, the first fitting 12 provides a first female thread 42 , the second fitting 30 provides a second female thread 42 , and the coupling 10 further includes a male threaded stud 44 having a first end 46 for connecting to the first female thread 42 and a second end 48 for connecting to the second female thread 42 .

[0035] Examples

[0036] Figure 1 and Figure 2 Two different embodiments of the concept are shown - starting with the "top" assembly and then the coupler itself. Each figure is briefly described below:

[0037] 1. Figure 1 is a coupling in which the RH coupling and the LH coupling are the same component, namely the "female coupling" mounted on the Reidbar. The two halves of the coupling system are then connected with a short post 44 in the form of a length of threaded rod. This has the advantage that only one coupling type is installed on the Reidbar, regardless of which side of the coupling system the bar is used. However, in this arrangement, both the RH side coupling and the LH side coupling must include sufficient "fine thread" length to support both the "preload plug" and the actual load-bearing threaded member.

[0038] 2. Figure 2 One layout is shown, including a "female" coupling and a "male" coupling. This eliminates the need for a screw to connect the two halves, and reduces the overall length, as the thread length required for the "preload plug" in the male half of the coupling is saved. However, this does result in the LH coupling and the RH coupling being different components.

[0039] 3. Figure 3 The bottom LH side shows the "female connector".

[0040] 4. Figure 3 The bottom RH side shows the "male connector".

[0041] Advantageously, these coupling arrangements allow for a situation where the preload on the Reidbar bar is created by the "fine pitch" thread rather than the coarser pitch Reidbar thread. In the case where the preload is created, i.e. when the "plug" ( Figures 1 to 3When the "plug" (green item in the figure) contacts the Reidbar (not shown), this is achieved by the pitch difference between the two threads: If torque is applied to the "plug" when all parts are in contact and the Reidbar is fixed, the torque will be transferred from the "plug" to the Reidbar via two paths: (a). Part of the torque will pass through the contact area between the end faces of the plug and the Reidbar. This torque will depend on friction, load and contact geometry. (b). Another part of the torque will be transferred through the "plug" thread into the coupling sleeve and through the sleeve to the Reidbar thread interface. Thus, the Reidbar thread and the "plug" thread will be subject to equal torque. Due to the pitch difference between the two threads, movement will preferably be in the fine thread, and thus, the load obtained in the joint will be a result of the mechanical advantage of the fine thread rather than the mechanical advantage of the Reidbar thread.

[0042] During installation of the coupler onto the rebar, it is necessary to control the plug position and torque transfer to the coupler sleeve before the "plug" makes contact with the Reidbar end face. This can be implemented in a number of ways. Figure 3 A stop in the form of a pin is shown that contacts the end face of the coupler sleeve. A properly sized pin will allow sufficient torque transfer to allow the sleeve to be threaded onto the Reidbar without the "plug" and the coupler sleeve rotating relative to each other. When the "plug" contacts the Reidbar, and the load, and therefore torque, increases, the pin will deflect and the "plug" will rotate relative to the sleeve. This same effect can be achieved in other ways, for example: a "low strength" thread locking adhesive (Loctite) on the "plug" threads or a shoulder with a wave washer to form a flexible joint between the "plug" and the sleeve.

[0043] The installation steps are outlined below.

[0044] Step One: Thread the Reidbar into the coupling until it rests against the inner shoulder.

[0045] Step Two: While supporting the coupling to prevent rotation, apply torque to the plug until the plug shears.

[0046] On site: Connect the two female couplings assembled to the Reidbar to the male threaded studs and tighten the joints.

[0047] If the stop described on page 6 is not present, installation involves the steps above. If the stop is present, installation steps are as follows:

[0048] 1.Fix the Reidbar to prevent rotation.

[0049] 2. Screw the coupling onto the Reidbar threads.

[0050] 3. To the "plug" ( Figure 3 , reference numeral 20 ) applies torque until the segment 24 shears off.

[0051] As will be appreciated from the above, examples of the present invention achieve a low torque solution by changing the preload thread from a rebar rolled thread to a finer pitch machined thread. The reduced torque required significantly improves ease of installation, reduces the cost of tools required to install the coupling, and allows for in-situ installation on the Reidbar.

[0052] exist Figure 1 In one embodiment shown, the two fittings in the coupling assembly are identical. The fittings have a plug (in Figures 1 to 5 ), the plug is threaded into the fine thread until the plug reaches a stop defined by a pin, which is the state when the coupling is delivered to the customer.

[0053] In an example, the coupler is assembled to the Reidbar as follows: the coupler is threaded onto the Reidbar by hand until the stop is reached, followed by tightening the hexagonal head until the frangible section shears off. The torque applied to the hexagonal head will initially be transmitted through the stop (pin) to ensure that the coupler is fully engaged on the rebar. At a predetermined torque, the stop will shear off and the plug will rotate in the fine thread and apply a preload to the rebar. When the assembly is properly preloaded, the frangible section will shear off. This embodiment helps to significantly reduce the required torque - in one specific embodiment, the torque required to obtain the correct preload drops from about 850Nm to about 200Nm.

[0054] When assembled in the field, the male stub is threaded into one fitting or the other, and the two are threaded together until the end faces touch.

[0055] Positive aspects:

[0056] -Because the fragile section is solid, the torque accuracy is better.

[0057] - The torque requirement is about 1 / 5 of that required to drive a coupling driven by a steel bar thread.

[0058] - Each bar size requires only one bar assembly process and socket size.

[0059] - Easier to manufacture than at least one previously proposed solution due to reduced internal geometric complexity.

[0060] Figure 6The pitch ranges of fine threads for each of the different Reidbar bar sizes and typical values ​​of the pitch of the fine threads are shown. In determining these ranges (particularly the lower limits), the environments in which these couplings are used and the common contaminants and handling patterns in such environments were taken into account. Very fine pitches (e.g. less than 1 mm) may be overly sensitive to dirt, grit and rough handling. Very coarse threads may require increased torque and therefore may reduce the advantages obtained from the present invention. These tabulated values ​​are considered to be the best known at this stage and may change.

[0061] Although various different embodiments of the present invention have been described above, it should be understood that these embodiments are presented by way of example only and not by way of limitation. It will be apparent to those skilled in the relevant art that various changes may be made to the form and details of the present invention without departing from the spirit and scope of the present invention. Therefore, the present invention should not be limited by any of the exemplary embodiments described above.

[0062] Reference in this specification to any prior publication (or information obtained therefrom) or any known matter is not and should not be taken as an acknowledgement or admission or any form of suggestion that the prior publication (or information obtained therefrom) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0063] Throughout the specification and the claims that follow, unless the context requires otherwise, the word "comprise" and variations thereof, will be understood to imply the inclusion of stated integers, steps, or groups of integers or steps but not the exclusion of any other integers or steps, or groups of integers or steps.

[0064] List of Reference Numerals

[0065] 10 Connector

[0066] 12 First Accessories

[0067] 14 The first ontology

[0068] 16 First internal thread

[0069] 18 Second internal thread

[0070] 20 Plug

[0071] 22 Joint structure

[0072] 24 Weak joint

[0073] 26 External thread

[0074] 28 Stopper

[0075] 30 Second Accessory

[0076] 32 Second Body

[0077] 34 First internal thread

[0078] 36 Second internal thread

[0079] 38 Second plug

[0080] 40 Male thread

[0081] 42 Female thread

[0082] 44 Male thread short column

[0083] 46 First End

[0084] 48 Second End

Claims

1. A connector, comprising: a first accessory, the first accessory being used to be mounted on a first externally threaded steel bar used in concrete construction, the first accessory comprising a first body having a first internal thread for threadably inserting the first externally threaded steel bar into the first accessory; The first accessory has a second internal thread, the pitch of the second internal thread being finer than the pitch of the first internal thread; as well as A plug is used to be threadedly connected into the second internal thread to abut the end of the threaded steel bar.

2. The coupling according to claim 1, wherein: The plug is adapted to be tightened in the second internal thread for applying a preload to the end of the threaded steel bar.

3. The coupling according to claim 2, wherein: The plug is frangible to ensure the correct amount of preload.

4. The coupling according to claim 2 or 3, wherein: The plug includes an engagement structure for rotating the plug relative to the first fitting, and wherein the engagement structure is frangibly connected to a remainder of the plug.

5. The coupling according to any one of claims 1 to 4, wherein: The plug has external threads corresponding to the second internal threads of the first fitting.

6. The coupling according to any one of claims 1 to 5, wherein: The plug includes a stopper to ensure a correct insertion depth of the plug relative to the first fitting, thereby allowing tightening of the plug after insertion of the threaded rebar for applying the preload.

7. The coupling according to any one of claims 1 to 6, wherein: The connector comprises: a second accessory, the second accessory being used to be mounted on a second externally threaded steel bar used in concrete construction, the second accessory comprising a second body having a first internal thread for threadably inserting the second externally threaded steel bar into the second accessory; The second fitting has a second internal thread, the pitch of the second internal thread being finer than the pitch of the first internal thread; and A second plug is used to be threadedly connected to the second internal thread to abut against the end of the second externally threaded steel bar.

8. The coupling according to claim 7, wherein: The second fitting is suitable for being threadedly connected with the first fitting.

9. The coupling according to claim 8, wherein: The second fitting provides a male thread, the first fitting provides a female thread, and the male thread is connectable to the female thread.

10. The coupling of claim 8, wherein: The first fitting provides a first female thread, the second fitting provides a second female thread, and the coupler further includes a male threaded stud having a first end for connecting to the first female thread and a second end for connecting to the second female thread.

11. A method of coupling threaded steel bars, the method comprising the step of using the coupling according to any one of claims 1 to 10.

12. A connection method comprising the following steps: Providing a first accessory, the first accessory comprising a first body, the first body having a first internal thread and a second internal thread, the pitch of the second internal thread being finer than the pitch of the first internal thread; installing the first fitting to a first externally threaded steel bar used in concrete construction, including the steps of threadably inserting the first externally threaded steel bar into the first internal thread; and A plug is threaded into the second internal thread to abut the end of the threaded rebar.

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