Patent Application
20120304554
This invention relates to a collar for a concrete panel lifting anchor and, more particularly but not exclusively, to a concrete panel lifting anchor formed of bent wire having a collar to provide clutch abutment surfaces.
It is known to lift a concrete panel by way of an anchor embedded within the concrete panel during casting of same. A typical anchor of this kind is formed from metal by cutting the anchor from a plate, and is cut so as to provide clutch abutment shoulders to limit rotation of a lifting clutch relative to the anchor. However, the applicant has identified that such typical anchors are relatively expensive to produce due to the cutting procedure, and that use of such typical anchors may be restrictive as the anchor must be located at or near a central plane of the panel. Lifting anchors fabricated by cutting plate material require a lot of energy to produce, and often have irregularities. Disadvantages also result from the anchors being cut from plate, as the anchors are typically planar and for correct orientation for lifting require legs of the anchor to extend across a large portion of the thickness of the concrete panel. Moreover, the applicant has identified that a significant amount of waste material is produced as a by-product in the manufacture of existing lifting anchors.
Examples of the invention seek to solve, or at least ameliorate, one or more disadvantages of previous lifting anchors.
In accordance with one aspect of the present invention, there is provided a collar for an anchor for use in lifting a concrete component, said anchor comprising a head portion engagable with a clutch of a lifting system, and a body portion for embedment with the concrete component, the collar including an attachment portion for attaching the collar to the head portion of the anchor, and an abutment portion adapted to provide a clutch abutment surface for limiting rotation of the clutch relative to the anchor.
Preferably, when the collar is fitted to the lifting anchor the abutment portion forms the clutch abutment surface as a shoulder adjacent the lifting anchor. More preferably, the clutch abutment surface is formed as a shoulder adjacent the head portion for limiting rotation of the clutch about an eye of the head portion. More preferably still, the abutment portion provides a shoulder adjacent each side of the head portion for limiting rotation of the clutch about the eye in both directions of rotation. The collar may include a gap between the shoulders which coincides with the eye of the head portion to allow passage of the clutch through the eye.
Preferably, the abutment portion is formed by an edge of the collar.
In a preferred form, the collar fits around the head portion, and is held to the head portion by way of a press fit.
Preferably, the collar is generally C-shaped.
In a preferred form, the collar includes at least one shear bar attached to the collar. More preferably, the shear bar engages in a groove of the collar. Preferably, the shear bar is welded to the collar. In one example, the shear bar is formed in a generally wave-like shape, with oscillations in a direction generally perpendicular to a central axis of the anchor when the collar is fitted to the anchor. More preferably, the collar includes a second shear bar, wherein a major axis of the second shear bar is generally parallel to a major axis of the first shear bar and is substantially a mirror image of the first shear bar when viewed from an end of the anchor.
In accordance with another aspect of the present invention, there is provided an anchor for use in lifting a concrete component, said anchor comprising a single length of wire bent to form a head portion engagable with a clutch of a lifting system, and a body portion for embedment with the concrete component, wherein the anchor has a collar to provide clutch abutment surfaces for limiting rotation of the clutch relative to the anchor, the collar being a collar as described above.
The invention is described, by way of non-limiting example only, with reference to the accompanying drawings in which:
With reference to
The anchor 10 comprises a single length of wire 14 bent to form a head portion 16 engagable with a clutch of a lifting system, and a body portion 18 for embedment with the concrete component 12. The wire 14 is bent such that opposed legs 20, 22 of the body portion 18 extend in a plane substantially perpendicular to a plane of the head portion 16. By virtue of the wire 14 being bent in this way, the anchor 10 is able to be arranged such that the opposed legs 20, 22 lie in a plane substantially parallel to a central plane of the concrete component 12, while the head portion 16 is oriented substantially perpendicularly to the central plane of the concrete component 12. Advantageously, this enables the anchor 10 to be located lower in the concrete component 12 to facilitate edge lifting of the concrete component 12, while facilitating a broad spread of the opposed legs 20, 22 within the concrete component 12.
As the legs 20, 22 are spread outwardly from a central axis 24, the load applied to the anchor 10 is distributed through a larger region of the concrete component 12 than is possible with a typical concrete anchor having parallel legs. Accordingly, this reduces the likelihood of the concrete component 12 failing during lifting, as a large region of the concrete component 12 must fail for the anchor 10 to be torn out during lifting. Each of the legs 20, 22 may be formed with a wave-like configuration by incorporating a series of ripples to provide additional anchorage of the anchor 10 within the concrete component 12. Advantageously, the ripples inhibit withdrawal of the legs 20, 22 from the concrete, by applying compression to the concrete during lifting. As such, the opposed legs 20, 22 are able to provide the same function as ancillary tension bars which have been used in existing lifting anchors.
To achieve the perpendicular configuration, the head portion 16 in the example shown is twisted through an angle of 270 degrees relative to the body portion 18 about the central axis 24 of the anchor 10. In alternative anchors, to achieve a perpendicular configuration the head portion may be twisted through an angle of 90 degrees (or, more generally, an angle of 90+180x, where x is a non-negative integer) relative to the body portion 18 about the central axis 24 of the anchor 10. The central axis 24 is in the plane of the head portion 16. In this way, the plane of the head portion 16 is perpendicular to the plane of the body portion 18.
It will be understood that, in alternative examples, the body portion 18 may be rotated about the central axis 24 relative to the head portion 16 such that the plane of the body portion 18 is out of the plane of the head portion 16 by an angle other than 90 degrees. In particular alternatives, this angle may be approximately 60, 45, 30 or 15 degrees, as may be appropriate depending on the shape and/or orientation of the concrete component 12.
The anchor 10 may be used for lifting concrete panels with varying edge profile angles by, prior to embedment of the anchor 10 within the concrete panel, bending the head portion 16 out of the plane of the legs 20, 22 by a corresponding angle. This bending may be effected on site to suit the particular application. For example, where the edge profile of the concrete panel is angled at 15 degrees, the head portion 16 of the anchor is correspondingly bent upwards at an angle of 15 degrees relative to the plane of the legs 20, 22. Similarly, where the edge profile of the concrete panel is angled at 45 degrees, the head portion 16 of the anchor 10 is bent upwards to a corresponding angle of 45 degrees relative to the plane of the legs 20, 22. It will be understood that the angle to which the head portion is bent relative to the plane of the legs 20, 22 may vary between 0 and 90 degrees, however the most common angles of edge profiles are 9 degrees, 15 degrees, 22.5 degrees, 30 degrees and 45 degrees.
The anchor 10 includes a collar 26 adapted to fit around the head portion 16, as shown in
More specifically, the collar 26 includes an attachment portion 58 for attaching the collar 26 to the lifting anchor 10, and an abutment portion 60 adapted to provide a clutch abutment surface for limiting rotation of a clutch relative to the lifting anchor 10. The attachment portion 58 is arranged for attaching the collar 26 to the head portion 16 of the lifting anchor 10. When the collar 26 is fitted to the anchor 10, the clutch abutment surface is formed as an abutment shoulder 28 standing proud of each opposed surface or side of the head portion 16 for limiting rotation of the clutch about an eye 62 of the head portion 16, in both directions of rotation. The collar 26 may include a gap 64 between the shoulders 28 which coincides with the eye 62 of the head portion 16 to allow passage of the clutch through the eye 62.
The collar 26 is generally C-shaped, including a pair of clasps for coupling to those parts of the head portion defining the opposed surfaces or sides of the head portion 16, with a connecting strip 66 between the clasps. Each clasp terminates in a tab 68 which secures the collar 26 to the head portion 16 by way of a hard press fit. The abutment portion 60 is formed by an edge of the collar 26, at each of the clasps.
The collar 26 includes a pair of shear bars 30, 32 attached to the collar 26. The shear bars 30, 32 extend generally perpendicularly to the central axis 24 and transverse to the plane of the body portion 18. These shear bars 30, 32 assist in preventing shear failure of the concrete component 12 during lifting, and provide improved anchorage of the anchor 10 within the concrete component 12. Each of the shear bars 30, 32 is formed in a generally wave-like shape, with lateral oscillations 34 in a direction generally perpendicular to the central axis 24 of the anchor 10. A second one of the shear bars 30 is located adjacent a first one of the shear bars 32, and is reversed such that the second shear bar 30 is substantially a mirror image of the first shear bar 32 when viewed from an end of the anchor 10. The shear bars 30, 32 may be positively held in place relative to the head portion 16 by engagement of the shear bars 30, 32 within grooves 36 formed in the collar 26. The grooves 36 formed on opposite sides of the collar 26 may be formed in a correspondingly offset configuration so as to positively locate the shear bars 30, 32 in the arrangement shown. Alternatively, the shear bars 30, 32 may be fixed relative to the head portion 16 by spot welding of the shear bars 30, 32 to the collar 26.
The applicant has determined that the collar 26 is particularly suited for use in providing a concrete component lifting anchor formed of bent rod or wire with clutch abutment surfaces for limiting rotation of a clutch relative to the lifting anchor. This is because there is not the same ability in providing anchors formed of bent wire with shoulders as there is with anchors cut from plate. However, it is possible for collars formed in accordance with other examples of the present invention to be used with anchors formed from plate, and such collars may provide various advantages over cut abutment shoulders. In particular, using a collar according to an example of the present invention provides the ability to interchange collars to change the size/shape of abutment shoulders, and provides a convenient way to attach shear bars to the anchor.
The collar 26 is preferably formed of metal, in particular from folded steel. In other examples, the collar may be formed from plastic.
Returning to the actual anchor itself, the length of wire or rod 14 from which the anchor 10 is formed from a one-piece elongate element shaped into the desired shape. More particularly, the anchor 10 is formed from a length of metal rod which is bent to form the anchor 10. The length of metal rod may be drawn from a coil. Advantageously, by virtue of the anchor 10 being formed from metal bar, material wastage is minimised, and the anchor 10 is manufactured in a particularly cost-effective manner.
In particular, the head portion 16 is formed by bending the metal rod around a forming piece (nor shown), the forming piece being a pin having a size corresponding to the size of a clutch portion to pass through the head portion 16. By virtue of this forming process, any variation in the dimensions (particularly the diameter) of the metal bar will not alter the size of the aperture in the head portion 16. Accordingly, it is possible to provide a superior tolerance for an effective, rigid coupling between the clutch and the anchor, thus avoiding a sloppy coupling between the anchor and the clutch. In other words, variation in the rod does not affect quality of engagement between the anchor and the clutch.
Also, by virtue of the anchor 10 being formed from round cross-section metal rod, there is a single point of contact between the clutch portion and the anchor 10, avoiding the problems associated with skewed prior art anchors cut from metal plate which tend to transfer undesirable forces to the concrete component 12.
With reference to
By virtue of the plane of the body portion 18 being coplanar with or substantially parallel to a central plane of the concrete component 12, it is possible for the body portion 18 to be located at or within a neutral axis of the concrete component 12 so as to avoid having the anchor embedded in regions of the concrete component 12 which are under high compression and/or tension during lifting. This may assist in avoiding failure of the concrete component 12 during lifting, and may enable lifting of concrete panels at a stage more premature (relative to the time of casting) than is required for lifting using existing concrete anchors.
Furthermore, the feature of the plane of the body portion 18 being coplanar with or substantially parallel to the central plane of the concrete component 12 enables the anchor to be used with concrete panels much thinner than is required for lifting using existing concrete anchors which extend transversely across a substantial portion of the thickness of the panel.
While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.
In particular, although the example anchor depicted in the drawings has an angle between the plane of the legs and the plane of the head portion of approximately 90 degrees, it will be understood that in alternative examples the angle between the plane of the legs and the plane of the head portion may take other values, for example 60, 45, 30 or 15 degrees. This angle may be dictated by the shape and/or orientation of the concrete component.
The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.
Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/AU2009/001541 | 11/25/2009 | WO | 00 | 5/23/2012 |
