NZ759986B2 - Lifting anchor - Google Patents

Abstract

anchor 1 is embedded in a concrete element to provide for the lifting of the element. An anchor 1 typically includes a head 3 at one end having a lifting eye 5 for releasable engagement with a lifting shackle assembly, and a body 11 extending in a longitudinal direction from the head 3 for embedding within the concrete element. During casting of a concrete element, concrete slurry can seep around the head 3 of the anchor and into the lifting eye 5 making it difficult for a ring clutch of a lifting assembly to access and lift the concrete element. The anchor 1 of the present invention has a head 3 which includes a centrally located main portion 17 in which the lifting eye 5 is formed, and a pair of wing portions 19 provided at opposite ends of the main portion 17, wherein the head 3 is of non-uniform thickness with the thickness of the wing portions 19 being less than the thickness of the main portion 17 such that a ledge 21 is provided between the main portion 17 and wing portions 19. The ledge 21 advantageously minimises the potential for concrete slurry during casting to seep into the lifting eye 5 from between side edges of the anchor head 3 and a removable void former in abutment with opposing faces of the anchor head 3. ing within the concrete element. During casting of a concrete element, concrete slurry can seep around the head 3 of the anchor and into the lifting eye 5 making it difficult for a ring clutch of a lifting assembly to access and lift the concrete element. The anchor 1 of the present invention has a head 3 which includes a centrally located main portion 17 in which the lifting eye 5 is formed, and a pair of wing portions 19 provided at opposite ends of the main portion 17, wherein the head 3 is of non-uniform thickness with the thickness of the wing portions 19 being less than the thickness of the main portion 17 such that a ledge 21 is provided between the main portion 17 and wing portions 19. The ledge 21 advantageously minimises the potential for concrete slurry during casting to seep into the lifting eye 5 from between side edges of the anchor head 3 and a removable void former in abutment with opposing faces of the anchor head 3.

Description

LIFTING ANCHOR FIELD OF THE INVENTION The invention relates to a lifting anchor that is adapted to be embedded in a concrete element such as a concrete panel, beam or column to provide a lifting attachment for the element.

BACKGROUND TO THE INVENTION Lifting anchors are commonly used in the lifting and handling of concrete pre-cast elements such as panels in the construction industry. Lifting anchors typically include a pair of generally parallel legs which are embedded in the concrete panel to provide anchorage. A head of the lifting anchor remains exposed in a recess formed in an edge of the panel. The head includes some form of eyelet to facilitate releasable engagement with a lifting shackle assembly associated with a crane to enable lifting of the panel.

It would be desirable to provide a lifting anchor of the above described general type which has one or more improved features.

Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material formed part of the prior art base or the common general knowledge in the relevant art on or before the priority date of the claims herein.

SUMMARY OF THE INVENTION In accordance with the invention, there is provided an anchor for embedding in a concrete element to provide for the lifting of the element. The 17734896_1 (GHMatters) P44399NZAU anchor including a head at one end having a lifting eye for releasable engagement with a lifting shackle assembly, and a body extending in a longitudinal direction from the head for embedding within the concrete element.

The lifting eye being formed in a centrally located main portion of the head, the head further including a pair of wing portions provided at opposite ends of the main portion, wherein the head is of non-uniform thickness with the thickness of the wing portions being less than the thickness of the main portion such that a ledge is provided between the main portion and wing portions.

There is also described an anchor for embedding in a concrete element to provide for the lifting of the element. The anchor including a head at one end having a lifting eye for releasable engagement with a ring clutch of a lifting shackle assembly, and a body extending in a longitudinal direction from the head for embedding within the concrete element. The head including upper edge having at least one abutment surface for abutting with a matching abutment surface of the ring clutch during lifting, wherein the abutment surface of the head slopes downwardly towards the lifting eye in a direction transverse to the longitudinal direction.

There is also described an anchor for embedding in a concrete element to provide for the lifting of the element. The anchor including a head at one end having a lifting eye for releasable engagement with a lifting shackle assembly, and a body extending from the head for embedding within the concrete element. The body including a tension bar aperture for receiving a tension bar, the aperture being dimensioned to provide a generally square configuration.

There is also described an anchor for embedding in a concrete element to provide for the lifting of the element. The anchor including a head at one end for releasable engagement with a lifting shackle assembly, and a body extending from the head for embedding within the concrete element. The body including at least one leg having an inner side edge and an outer side edge. The leg further including reinforcement ridging extending along at least a face of the 17734896_1 (GHMatters) P44399NZAU leg adjacent each side edge of the leg, wherein the reinforcement ridging provides the inner and outer side edges with a width greater than an intermediate region of the leg between the side edges.

There is also described an anchor for embedding in a concrete element to provide for the lifting of the element. The anchor including a head at one end for releasable engagement with a lifting shackle assembly, and a body extending from the head for embedding within the concrete element. The body including a pair of generally parallel legs, each leg having an inner side edge and an outer side edge, each leg further including opposed faces having reinforcement ridging extending on each of the opposed faces adjacent each side edge of the leg, wherein the reinforcement ridging provides the inner and outer side edges of each leg with a width greater than an intermediate region between the side edges.

There is also described an anchor for embedding in a concrete element to provide for the lifting of the element. The anchor including a head at one end for releasable engagement with a lifting shackle assembly, and a body extending from the head for embedding within the concrete element. The body including at least one leg extending in a longitudinal direction of the anchor, and a foot portion at a remote end of the leg for locking into the surrounding concrete.

The foot portion sloping downwardly away from an inner side edge of the leg at an obtuse angle relative to the leg. The foot portion including a free end section projecting upwardly at an acute angle relative to the leg.

To assist in further understanding the invention, reference will now be made to the accompanying drawings which illustrate preferred embodiments. It is to be appreciated that these embodiments are given by way of illustration only and that the invention is not be limited by these illustrations. 17734896_1 (GHMatters) P44399NZAU BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a lifting anchor in accordance with an embodiment of the invention; Figure 2 is a view illustrating a face of the anchor illustrated in Figure 1, the view from the opposite face of the anchor being identical; Figure 2A is a sectional view taken along line A-A in Figure 2; Figure 2B is a sectional view taken along line B-B in Figure 2; Figure 2C is a sectional view taken along line C-C in Figure 2; Figure 2D is a sectional view taken alone line D-D in Figure 2; Figure 3 is a view of the outer side edge of the anchor illustrated in Figure 1, the outer side edge on the opposite edge of the anchor being identical; Figure 4 is a fragmentary sectional enlarged view illustrating the engagement of an arcuate locking bolt and ring clutch body of a lifting clutch with a head of the anchor illustrated in Figure 1, and Figure 5 is a perspective view of the anchor illustrated in Figure 1 attached to a void former prior to casting of the anchor in a concrete element.

DESCRIPTION OF PREFERRED EMBODIMENTS With reference to the accompanying drawings there is shown a lifting anchor in accordance with an embodiment of the invention which incorporates a range of improved features over conventional lifting anchors commonly used in 17734896_1 (GHMatters) P44399NZAU the lifting of concrete pre-cast elements, such as panels, in the construction industry. The lifting anchor 1 includes a head 3 at one end having a lifting eye 5 with a central axis in an axial direction (x axis) for releasable engagement with a conventional ring clutch of a lifting shackle assembly. In this respect, a retractable arcuate locking bolt 9 projecting from a torus ring body 7 of the ring clutch is receivable within the lifting eye 5 of the anchor 1, as shown in Figure 4.

The lifting anchor 1 further includes a body 11 extending in a longitudinal direction (z axis) from the head 3 for embedding within an edge of the concrete element. The body 11 of the anchor 1 illustrated in the accompanying drawings includes a pair of parallel legs 13. While it is preferred to provide a pair of legs 3, there may be only one leg 13 depending upon the requirements of the particular anchor. A face of the anchor 1, as illustrated in Figure 2, lies in the Y-Z plane with the central axis of the lifting eye 5 being perpendicular to the Y-Z plane.

Prior to the casting of a concrete element, for example a concrete panel, lifting anchors are suitably positioned together with reinforcing elements in a mould or formwork. As illustrated in Figure 5, the head 3 of an anchor 1 is typically secured prior to casting in a removable void former 15. Void formers 15 are typically designed to abut against opposing faces of the anchor in order to prevent the ingress of concrete slurry into the region of the lifting eye 5 during casting. After the concrete has hardened, the void former 15 is removed leaving a recess in the edge of the concrete panel around the head 3 such that a ring clutch of a lifting shackle assembly can then access and engage the lifting eye 5 within the recess.

An anchor 1 in accordance with an embodiment of the invention includes the lifting eye 5 being formed in a centrally located main portion 17 of the head. The head 3 further includes a pair of winged portions 19 provided at opposite ends of the main portion 17. As can be seen from Figures 2B and 2C, the head 3 is advantageously of non-uniform thickness in the axial direction (x 17734896_1 (GHMatters) P44399NZAU axis) with the thickness of the winged portions 19 being preferably uniform, but less than the thickness of the main portion 17 such that a ledge 21 is provided between the main portion 17 and winged portions 19. The ledge 21 preferably lies substantially perpendicular to the main portion 17 and the wing portions 19.

The ledge 21 advantageously minimises the potential for concrete slurry during the casting of the panel to seep into the lifting eye 5 from between the side edges of the anchor head 3 and the void former 15 by retarding flow. In this respect, as illustrated in Figure 1, the ledge 21 created between the main portion 17 and the winged portions 19 creates a diverging path 18 which concrete slurry must navigate in order to reach the eye 5 of the head 3.

The ledge 21 also advantageously provides the anchor head 3 with increased strength compared to a conventional flat faced anchor head 3. The anchor head 3 thereby has greater resistance to bending, particularly at any lift- load sling angle greater than 0°. In addition, the thickened main portion 17 relative to the winged portions 9 advantageously transfers loads more uniformly and symmetrically into the upper section of the anchor’s body 11.

With reference to Figures 1 and 4, an upper edge of the anchor 1 is provided by the top of the main portion 17 and the wing portions 19. At least one abutment surface 23 for abutting with a matching abutment surface 25 of the torus ring body 7 during lifting is provided in the upper edge. In a particularly preferred embodiment, an abutment surface 23 is provided in the upper edge of both winged portions 19. As best shown in Figure 2, the abutment surface 23 of each winged portion 19 slopes slightly downward towards the upper edge of the main portion 17 in a generally transverse direction (y axis) to the longitudinal direction (z axis) of the anchor 1. As a result, the abutment surfaces 23 are not parallel to the edge of the concrete panel in which the anchor 1 is located. An ear may also protrude from the upper outer corner of each wing portion 19.

As shown in Figure 4, the sloping abutment surfaces 23 in the top edge of the anchor 1 have corresponding matching abutment surfaces 25 in the 17734896_1 (GHMatters) P44399NZAU ring body 7. When the ring body 7 is slightly rotated about the central axis of the lifting eye 5 to take up any clearance between the respective abutment surfaces 23, 25, maximum surface contact is made between the anchor 1 and ring body 7.

The interface of the inclined abutment surface 23 with the matching abutment surface 25 of the ring body 7 advantageously focuses compressive load on the anchor head 3 in a longitudinal direction (z axis) perpendicular to the inclined abutment surface 23, down through the narrow winged portions 19 adjacent the thicker main portion 17. Accordingly, spalling of surrounding concrete is minimised during lifting by the wing portions 19 absorption of stresses away from the thicker main portion 17.

Immediately below the head 3 in an upper section of the anchor’s body 11 is a tension bar aperture 27 for receiving a tension bar. A tension bar is a metal bar which is bent in half to provide a generally V-shaped configuration.

Tension bars are widely used in the art and are positioned prior to casting of the concrete panel such that the bend contacts the walls of the tension bar aperture The tension bar aperture 27 in the present invention is preferably dimensioned to provide a generally square configuration for greater versatility in the positioning of the tension bar. In this respect, the tension bar aperture 27 is formed in the body 11 of the anchor 1 from a pair of arms 33 which project downwardly and continue from the main portion 17 of the head 3. The arms 33 preferably lie parallel to one another and are of equal length. The arms 33 are also reinforced with ridging 32 which provide the arms 33 with a generally dog- bone appearance in transverse cross-section with inner walls of the arms 33 providing vertical inner side walls 29 of the tension bar aperture 27. The body 11 further includes a cross member 26 having an upper wall which provides a bottom inner side wall of the tension bar aperture 27. The cross member 26 is also provided with reinforced ridging 34 which provides the cross member with a generally dog-bond appearance in transverse cross-section. An upper inner side 17734896_1 (GHMatters) P44399NZAU wall of the tension bar aperture 27 is provided by an underside of the main portion 17 of the head 1.

At each corner of the tension bar aperture 27 the inner side walls 29 are provided with a gusset 31 which protrudes radially inwards to provide an arcuate contact surface for the tension bar. The gussets 31 have a width, a in the axial direction (x axis) less than a width, W of the inner side walls 29 of the aperture 27 in the axial direction, as can be seen from Figure 2D. The inner gussets 31 together with the arms 33 of generally dog-bone profile advantageously assist to both transfer and contort shear load stress, thereby further maximising the shear load capacity of the anchor 1.

Below the cross member 26 is provided the pair of legs 13 which project downwardly in the longitudinal direction (z axis) parallel to one another.

Each leg 13 of the anchor 1 preferably has an inner side edge 35 and an outer side edge 37. Each leg 13 further includes reinforcement ridging 39 extending along at least a face of the leg 13 and adjacent each side edge of the leg 13.

With reference to Figure 2A, the reinforcement ridging 39 advantageously provides the inner and outer side edges 35, 37 with a width, b in the axial direction (x axis) greater than an intermediate region 41 of the leg 13 between the side edges 35, 37. The reinforcement ridging 39 of the legs 13 is also preferably a continuation of the reinforcement ridging provided on the cross member 26, thereby providing the legs 13 and cross member 26 with an overall U-shaped configuration.

The body 11 of the anchor 1 further includes a foot portion 43 at a remote end of each leg 13 for locking into the surrounding concrete. As best shown in Figure 1, the foot portion 43 projects from the inner side edge 35 in a transverse direction (y axis) generally perpendicular to the inner side edge 35 of the leg 13. Further, the foot portion 43 also preferably projects outwardly from both opposing faces of the leg 13 in the axial direction (x axis) perpendicular to the faces. The foot portion 43 slopes downwardly from the inner side edge 35 of 17734896_1 (GHMatters) P44399NZAU the leg 13 at an obtuse angle, α which is preferably between approximately 120 and 150° relative to the longitudinal direction (z axis) of the leg 13. The foot portion further includes a free end section projecting upwardly at an acute angle, β relative to the longitudinal direction (z axis) of the leg 13. In this regard, the acute angle is preferably between approximately 10 and 50° relative to the leg 13.

Further, the foot portion 43 preferably has a length in the transverse direction (y axis) perpendicular to the inner side edge 35 with the free end section 45 having a length which is preferably between approximately 10 and 50% of the overall length of the foot portion 43. As best shown in Figure 3, the foot portion 43 also preferably has a width in the axial direction (x axis) perpendicular to the faces which is approximately between 2-3 times greater than the width of the inner and outer side edges 35, 37 of the leg 13. The free end section 45 of the foot 43 provides a barbed-like feature which is designed to minimise outward stress into the concrete panel’s thickness with force applied to the free end section 45 minimising local stress, though focussing stress to the centre of the panel. 17734896_1 (GHMatters) P44399NZAU

Claims (13)

CLAIMS :

1. An anchor for embedding in a concrete element to provide for the lifting of the element, the anchor including a head at one end having a lifting eye for releasable engagement with a lifting shackle assembly, and a body extending in a longitudinal direction from the head for embedding within the concrete element, the lifting eye being formed in a centrally located main portion of the head, the head further including a pair of wing portions provided at opposite ends of the main portion, wherein the head is of non-uniform thickness with the thickness of the wing portions being less than the thickness of the main portion such that a ledge is provided between the main portion and wing portions.

2. An anchor as claimed in claim 1 wherein each wing portion includes an upper edge having an abutment surface for abutting with a matching abutment surface of the lifting shackle assembly during lifting of the concrete elements.

3. An anchor as claimed in claim 2 wherein the abutment surface of each wing portion slopes downwardly towards the centrally located main portion.

4. An anchor as claimed in any one of the preceding claims wherein the abutment surface of the head slopes downwardly towards the lifting eye in a direction transverse to the longitudinal direction.

5. An anchor as claimed in any one of the preceding claims wherein the body includes a tension bar aperture for receiving a tension bar, the aperture being dimensioned to provide a generally square configuration.

6. An anchor as claimed in claim 5 wherein inner side walls of the aperture are provided with a gusset at each corner of the aperture to provide arcuate contact surfaces for the tension bar. 17734896_1 (GHMatters) P44399NZAU

7. An anchor as claimed in claim 6 wherein the gussets have a width less than the inner side walls of the aperture.

8. An anchor as claimed in any one of the preceding claims wherein the body includes at least one leg and a foot portion at a remote end of the leg for locking into the surrounding concrete, the foot portion projecting from at least a face and inner side edge of the leg.

9. An anchor as claimed in claim 8 wherein the leg extends in a longitudinal direction of the anchor and the foot portion projects outwardly from opposing faces of the leg in a direction perpendicular to the faces and outwardly from the inner side edge in a direction generally perpendicular to the inner side edge.

10. An anchor as claimed in claim 9 wherein the foot portion slopes downwardly away from the inner side edge of the leg at an obtuse angle and includes a free end section projecting upwardly at an acute angle relative to the leg.

11. An anchor as claimed in claim 10 wherein the obtuse angle is between approximately 120° and 150° degrees and the acute angle is between approximately 10° and 50° degrees.

12. An anchor as claimed in claim 10 or 11 wherein the foot portion has a length in the direction perpendicular to the inner side edge with the free end section having a length which is between approximately 10 and 50% of the overall length of the foot portion.

13. An anchor as claimed in any one of claims 8-12 wherein the foot portion has a width in the direction perpendicular to the faces which is approximately 2-3 times greater that the width of the inner and outer side edges of the leg. 17734896_1 (GHMatters) P44399NZAU