AU2012101818A4

AU2012101818A4 - Concrete lifting anchors

Info

Publication number: AU2012101818A4
Application number: AU2012101818A
Authority: AU
Inventors: Andrew Barraclough
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 2011-12-20
Filing date: 2012-12-12
Publication date: 2013-01-24
Anticipated expiration: 2020-12-12
Also published as: AU2012261677A1; AU2012261677B2

Abstract

C:\DOCUME- \MELFAC- \LOCALS l\Temp\20121212l05340863ArnoDocSentl5320580.doc-12/12/21012 A lifting anchor assembly for incorporation into a concrete panel prior to casting, the assembly comprising an anchor having a head engageable by the body of a lifting clutch, a 5 void former engaged with the head of the anchor, and a cage engaged with the void former, the cage forming an enclosure which wraps around the void former and which, when the void former is removed following casting, is exposed to the surface of the concrete void thus formed for direct engagement with the body of the clutch, the cage also having legs to extend into the concrete to provide shear resistance during lifting with loading being 10 transferred between the clutch body and cage by the direct engagement between the clutch body and the adjacent part of the enclosure. 6a 6b 6 8a 8Figure 1 8c 8c 8d Figure 2 6a

Description

C:\DOCUME- \MELFAC- \LOCALS~ l\Temp\201 1212102l5257674ArnoDocSentl532055O.doc-12/12/21012 - 1 CONCRETE LIFTING ANCHORS The present invention relates to lifting anchors for incorporation into a concrete panel prior to casting in order to provide lifting points by which the panel can subsequently be lifted. 5 When panels are cast in a factory situation remote from the site of erection it is normal practice to incorporate edge lift anchors in which a head of the anchor is within a void opening onto an edge of the panel for engagement with a corresponding clutch of a lifting shackle. The edge lift anchors are used to lift the panel from the casting bed, to load the 10 panel onto a truck for transportation to site and then to lift the panel into its erected position. The present invention relates to an edge lift anchor having a particular applicability to relatively thin panels and which, with conventional anchors, can give rise to difficulties in 15 establishing the necessary shear capacity and which is required at the start of lifting when raising the cast panel from the horizontal orientation in which it is cast, to a generally vertical orientation. According to the present invention there is provided a lifting anchor assembly for 20 incorporation into a concrete panel prior to casting, the assembly comprising an anchor having a head engageable by the body of a lifting clutch, a void former engaged with the head of the anchor, and a cage engaged with the void former, the cage forming an enclosure which wraps around the void former and which, when the void former is removed following casting, is exposed to the surface of the concrete void thus formed for 25 direct engagement with the body of the clutch, the cage also having legs to extend into the concrete to provide shear resistance during lifting with loading being transferred between the clutch body and cage by the direct engagement between the clutch body and the adjacent part of the enclosure. 30 In a preferred embodiment the void former consists of two parts assembled to the anchor head and the enclosure of the cage retains the two parts in their assembled condition until C:\DOCUME- \MELFAC- \LOCALS~ l\Temp\201 1212102l5257674ArnoDocSentl532055O.doc-12/12/21012 -2 removal. Advantageously the anchor is of the type consisting of a stem having an enlarged foot portion at one end and an enlarged head at the other end for engagement by claws of the 5 lifting clutch. An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a perspective view of an anchor assembly consisting of an anchor, void 10 former and cage; Figure 2 is an underneath view corresponding to Figure 1; Figure 3 is a perspective view of the cage; Figure 4 is a plan view of the cage; Figure 5 shows schematically the anchor assembly in its installed condition; 15 Figure 6 shows schematically the co-operation between the cage and body of a lifting clutch applied after removal of the void former; and Figure 7 is a schematic section corresponding to Figure 6. With initial reference to Figures 1 and 2, the anchor in accordance with the preferred 20 embodiment of the invention is in the form of an assembly consisting of a lifting anchor of a conventional type consisting of a cylindrical stem 2 having an enlarged foot portion 4 and an enlarged head 5 (shown in Figure 7 only). An anchor of this type is marketed by Reid, a business unit of ITW Australia Pty Ltd, under the trade mark "Swiftlift". The anchor is designed for use with a lifting clutch of generally hemispherical form having 25 claws which engage beneath the head by rotation of the clutch body. The anchor assembly also consists of a removable void former 6 consisting of two half shells 6a, 6b engaged with the head of the anchor to form within the edge of the panel a void for receiving the body of the clutch, and a wire cage 8 assembled to the void former to hold the two shells 6a, 6b of the void former engaged with the head of the anchor. The cage 8 also provides 30 an important function in providing the required shear capacity by co-operation with the clutch at the commencement of lifting as will be explained.

C:\DOCUME- \MELFAC- \LOCALS~ l\Temp\201 1212102l5257674ArnoDocSentl532055O.doc-12/12/21012 -3 As shown in Figures 3 and 4, the cage 8 consists of two identical components of wire bent to shape and welded together at their points of intersection X to provide a wire enclosure 8a which wraps around the assembled void former to hold the two parts together, and legs 5 having a part 8b shaped to extend transversely across the thickness dimension of the panel and a part 8c angled to extend inwardly in the depth direction and which is usually the width direction as lifting from the casting bed normally takes place at the longer side of the panel. As shown, the part 8b is inwards inclined relative to the edge of the panel containing the void. The part 8c terminates in an inwardly directed transverse part 8d 10 extending substantially parallel to the edge of the panel containing the void. The installed condition of the anchor assembly following casting of the panel is shown schematically in Figure 5. The enclosure 8a which wraps around the void former 8 effectively forms a cradle which, 15 when the void former is removed from the anchor following casting, is exposed to the surface of the void thus formed and is directly engageable by the body of the clutch when seated in the void to engage the head of the anchor. At the commencement of lifting when the panel is being raised from the casting bed, the shear loading for the anchor assembly is provided by the direct engagement between the clutch body and the adjacent cradle part of 20 the cage, with the shear capacity being developed by the configuration of the legs which extend relatively deeply into the height dimension of the panel. This configuration develops a significant capacity in shear without requiring any other measures and is able to achieve this despite the panel being relatively thin. As the panel approaches its vertical orientation the load is predominantly a tensile load which is carried by the configuration of 25 the anchor. The co-operation between the clutch body 10 and the cage 8 at the commencement of lifting is illustrated schematically in Figures 6 and 7; the cross-section of Figure 7 also shows the co-operation between the clutch body 10 and head 5 of the anchor. 30 The anchor assembly consisting of anchor, cage, and void former, is supplied fully assembled. In the embodiment shown the stem 2 of the anchor carries a clip 20 designed C:\DOCUME- \MELFAC- \LOCALS~ l\Temp\20 1212102l5257674ArnoDocSent15320550.doc-12/12/2012 -4 to receive reinforcing bar 22 which is used to tie the anchor into the reinforcement of the panel.

Claims

1. A lifting anchor assembly for incorporation into a concrete panel prior to casting, the assembly comprising an anchor having a head engageable by the body of a lifting 5 clutch, a void former engaged with the head of the anchor, and a cage engaged with the void former, the cage forming an enclosure which wraps around the void former and which, when the void former is removed following casting, is exposed to the surface of the concrete void thus formed for direct engagement with the body of the clutch, the cage also having legs to extend into the concrete to provide shear resistance during lifting with 10 loading being transferred between the clutch body and cage by the direct engagement between the clutch body and the adjacent part of the enclosure.

2. An anchor assembly according to claim 1, wherein the void former consists of two parts assembled to the anchor head and the enclosure formed by the cage retains the two 15 parts in their assembled condition until removal.

3. An anchor assembly according to claim 1 or claim 2, wherein the anchor is of a type consisting of a stem having an enlarged foot portion at one end and an enlarged head at the other end for engagement by claws of the lifting clutch. 20

4. An anchor assembly according to any one of claims 1 to 3, wherein the enclosure which wraps around the void former forms, when the void former is removed following casting, a cradle for engagement with the body of the clutch. 25

5. An anchor assembly according to any one of claims 1 to 4, wherein the cage consists of two substantially identical components of wire rod bent into shape and welded together, each component having a part forming one half of the cage, and legs extending from each end of that part. 30

6. An anchor assembly according to claim 5, wherein each leg comprises a part ("the first part") configured to extend generally in the thickness dimension of the panel and a C:\DOCUME- \MELFAC- \LOCALS~ l\Temp\201212 12105326l9OArnoDocSentl5320570.doc-12/12/2012 -6 part ("the second part") configured to extend into the depth of the panel.

7. An anchor assembly according to claim 6, wherein the first part commences adjacent the cage, and the second part extends from an end of the first part remote from the 5 cage.

8. An anchor assembly according to claim 7, wherein each leg comprises a third part extending from a remote end of the second part and directed transversely thereto. 10

9. An anchor assembly according to claim 7 or claim 8, wherein the first part of the leg inclines relative to the edge of the panel containing the void.