AU701867B2 - Restrained lifting anchor for concrete pipes - Google Patents

Description

2 RESTRAINED LIFTING ANCHOR FOR CONCRETE PIPES The present invention relates to concrete pipes, and more particularly concrete pipes with lifting anchors embedded therein for engagement by lifting tools, devices or cranes, including mobile cranes.

It is known to produce concrete pipes with metal lifting anchors cast therein during the formation of the pipe. It is the practice to have the heads of the anchors which are to be engaged by the lifting tools, devices or cranes, received within cavities formed in the external wall of the pipe whereby none of the anchor protrudes beyond the external surface of the wall of the pipe. This practice arose in the building construction industry, where concrete components for forming slabs and walls incorporated such lifting anchors in cavities to enable the surface of the slab or wall member to be finished off by filling in the cavities and covering the lifting anchors embedded therein. In addition with anchors in cavities, their cooperation with the lifting tool, device or crane is S 20 such that the lifting forces are applied substantially axially of the lifting anchor with little, if any, lifting force component laterally of the anchor. The practice with concrete slabs or wall panels was automatically applied to concrete pipes and thus the reason why historically the 25 heads of lifting anchors embedded in the walls of concrete pipes also terminate within cavities formed in the wall of the pipe.

e However, in thin walled pipe the necessity to form cavities in the wall of the pipe reduces the depth to which the anchors can be embedded and as a consequence they are not able to carry the required load.

In our copending patent application no. 20039/95,and entitled Concrete Pipe With Lifting Anchors there is staff/enne/keep/PN4927 23.7 3 disclosed a concrete pipe with at least one lifting anchor embedded therein, one end portion of the anchor extending radially outwardly beyond the external circumferential surface of the pipe and having means for engagement by lifting means, with the remainder of the anchor extending radially inwardly of the pipe wall being embedded within the wall of the pipe and without the formation of a cavity in the wall of the pipe.

As concrete pipes are invariably buried in trenches no external surface finishing to cover the anchors for aesthetic purposes is necessary. Eliminating the cavities provides for an adequate strength of embedment, whilst the pipe design criteria can be modified to deal with the application of lifting force components laterally of the lifting anchors.

The embedded end of the anchor or anchors has an enlarged formation thereon which resisted radial :i disengagement of the anchor from its embedded position within the pipe wall.

20 However with concrete pipes having lifting o anchors either extending radially outwardly beyond the external circumferential surface of pipe or having their heads received within cavities, there is still a too possibility for the anchor to become disengaged, or tear 25 free, from the embedded position within the pipe wall.

too It is therefore an object of the present invention to provide a concrete pipe with at least one, preferably two, lifting anchors embedded therein, together with means to more securely restrain the inner end of the anchor within the wall of the concrete pipe.

The invention therefore envisages a concrete pipe staff/enne/keep/PN4927 23.7 4 with at least one lifting anchor embedded therein and having means at an outer end thereof for engagement by lifting means, wherein an inner embedded end of said anchor has an aperture therethrough for receiving a restraining cable, or the like, to also be embedded within the wall of the pipe and to restrain the end of the anchor securely within the wall of the pipe.

Preferably the ends of the restraining cable or the like, on either side of the inner end of the lifting anchor, are formed with eyelets whereby, during casting of the pipe, concrete will penetrate through said eyelets as :0 well as through the aperture through the lifting anchor to completely embed the restraining cable, or the like, in the concrete wall of the pipe.

Preferably the inner embedded end of the anchor is enlarged so as to further diminish the chances of the anchor disengaging or tearing free from its embedded 20 position within the wall of the pipe.

0: One preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view of part of the H:Leanne\Keap\60774.96.doc 9/12/98 5 wall of a concrete pipe at a position where a lifting anchor is embedded therein, Figure 2 is a cross-sectional view taken along line 2-2 of Figure 1, Figure 3 is a perspective view of the lifting anchor shown in Figures 1 and 2, Figure 4 is a cross-sectional view through part of a seam of a pipe mould used to cast a concrete pipe in accordance with the preferred embodiment of the invention and with the seam open, Figure 5 is a cross-sectional view similar to that of Figure 4, but with the seam closed, and Figure 6 is a side elevational view of the seam configurations of Figures 4 and 15 Referring to Figures 1 to 3 of the drawings, the V066 concrete pipe of this preferred embodiment of the present 600-0- invention has a steel lifting anchor 2 embedded therein during the formation of the pipe and having an external end portion 3 extending radially beyond the outer surface of 20 the pipe with a lifting head 4 formed on the end thereof to be engaged by a lifting tool, device or crane. The remaining portion 7 of the length of the anchor extends radially inwardly of the pipe wall to be embedded therein and carries on its inner embedded end an enlarged end 6, which serves to resist radial disengagement of the anchor from its embedded position within the pipe wall.

In accordance with the present invention the enlarged end 6 of the anchor has an aperture 6a therethrough which receives a restraining cable 100 staff/enne/keep/PN4927 23.7 6 positioned therethrough at a point midway along the length of the cable, and which, when the pipe is cast, is embedded within, and extends circumferentially within, the wall of the pipe. The opposite end portions of the cable are turned back on themselves and crimped by crimping bands 101 to form eyelets 102. During casting of the pipe concrete penetrates the eyelets 102 and the aperture 6a through the inner end of the lifting anchor to completely embed the restraining cable in the wall of the concrete pipe.

With reference to Figures 4, 5 and 6 of the drawings, there is shown part of a pipe mould formed from thin and therefore relatively flexible metallic material and defining a cylindrical mould cavity. The pipe mould has a longitudinally extending seam 10 whereby after a pipe is moulded and the concrete has cured the facing edges on either side of the seam can be drawn sufficiently away from each other whereby to release the mould from the pipe surface whereafter the moulded pipe can be axially removed from the mould.

20 When used to cast a pipe incorporating the preferred embodiment of the invention, the facing edges of the mould at the seam have flanges 11 and 12 carried thereby. One of the flanges 11 has a cavity 16 formed therein at the required position for the lifting anchor 2, 25 and usually two lifting anchors are provided at longitudinally spaced apart positions along the pipe wall.

A plug 14 of magnetic material is located in the cavity 16 at a position leaving a sufficient remaining length of cavity which will accommodate one side portion of the head 4 of the anchor. with the side of the length of the anchor abutting the face 15 of the flange 11 radially inwardly of the mould. The other flange 12 has an opening therethrough aligned with the cavity 16 to receive the other side of the head 4 of the anchor. A pair of locating stafflenne/keep/PN4927 23.7 7 bars 17 are provided on the faces of the flanges 11 and 12 radially outwardly of the mould, and which bars abut each other when the seam is closed as shown in Figure As a result of the above, the head of the anchor is firstly held in position by the magnetic plug when the seam is open and subsequently captured between the flanges 11 and 12 and the locating bars 17 when the seam is closed.

The position of all components relative to the head of the anchor sets the amount of the length of the anchor which will extend into the mould cavity and therefore the length of the anchor that will be embedded within the wall of the pipe and as a consequence the length thereof which will extend radially outwardly from the surface of the pipe, when the pipe is moulded.

The outer face of flange 11 adjacent the cavity 16 has a nut 18 attached thereto, such as by welding, and into which an adjusting bolt 21 is screwed in alignment with the cavity, and by screwing the bolt inwardly and outwardly of the cavity the position of the plug of 20 magnetic material within the cavity can be adjusted to allow the size of the remainder of the cavity to be adjusted to accommodate different sized heads for the anchor. A lock nut 19 is also provided to lock the bolt at any required position.

The anchor and restraining cable combination of the present invention is firstly orientated longitudinally of the mould seam and introduced through the seam, whereafter the combination is swung through 900 so as to extend circumferentially inside the mould and to be subsequently embedded within the pipe to extend circumferentially within the wall as shown in Figure i.

staff/enne/keeplPN4927 23-7 -8 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A concrete pipe with at least one lifting anchor embedded therein and having means at an outer end thereof for engagement by lifting means, wherein an inner embedded end of said anchor has an aperture therethrough for receiving a restraining cable, or the like, to also be embedded within the wall of the pipe and to restrain the end of the anchor securely within the wall of the pipe.

2. A concrete pipe as claimed in Claim 1, wherein the ends of the restraining cable, or the like, are formed with eyelets whereby, during casting of the pipe, concrete will penetrate through said eyelets to completely embed the restraining cable, or the like, in the concrete wall of the pipe.

3. A concrete pipe as claimed in Claim 1 or 2, wherein the aperture is so sized relative to the cable cross-sectional dimension that concrete will penetrate 20 through the aperture through the lifting anchor and around the cable.

4. A concrete pipe as claimed in any one of the preceding claims, wherein the inner embedded end of the anchor is enlarged.

A concrete pipe with lifting anchors embedded therein substantially as hereinbefore described with reference to the accompanying drawings.

6. A lifting anchor substantially as hereinbefore described with reference to the accompanying drawings.

H:\Leanne\Keep\60774.96.doc 9/12/98

Claims (2)

1. 7. The combination of a lifting anchor and a restraining cable substantially as hereinbefore described with reference to the accompanying drawings.
2. 8. A method of casting a combination of a lifting anchor and a restraining cable in the wall of a concrete pipe, substantially as hereinbefore described with reference to Figures 4 to 6 of the accompanying drawings. Dated this 9th day of December 1998 CSR HUMES PTY. LIMITED By their Patent Attorneys 15 GRIFFITH HACK Fellows Institute of Patent Attorneys of Australia o0 H:\Leanne\Keep\60774.96.doc 9/12/98 ABSTRACT A concrete pipe with lifting anchors embedded therein and having a lifting head at an outer end thereof for engagement by lifting means. The inner end (6) of the anchor is enlarged and has an aperture (6a) therethrough for receiving a restraining cable (100) also embedded within the wall of the pipe to restrain the end of the anchor securely within the wall of the pipe. Eyelets (102) are formed at the ends of the cable whereby concrete penetrates through the eyelets and the aperture (6a) to completely embed the cable in the concrete wall of the pipe. A method of casting the anchor and cable combination in the wall of a concrete pipe is also disclosed. *oo *ooo* o** staff/enne/keep/PN4927 23.7