Patent Application
20240217137
The present invention relates to a recess former and anchor assembly and to a method of forming a recess around a lifting anchor or other embedded item cast into a concrete element, in particular for attachment to the reinforcement cages for the manufacture of concrete elements including concrete pipes and the like.
Pipes and tubes manufactured from concrete provide an economical solution for the transport of potable water, drainage and sewage for civil engineering applications. Concrete pipes require relatively thick walls to resist the internal and external pressures and are therefore heavy and in most cases, they need to be lifted, handled and placed using mechanical lifting equipment.
The simplest method of lifting concrete pipes is to tie a rope or sling around the pipe close to its centre of gravity. This method requires either that the pipe be rolled over the rope or that there be a gap under the pipe to enable the sling to be passed under the pipe. Importantly, the sling can only be removed when there is a gap or the pipe rolled away. This method of lifting can be acceptable for small diameter, relatively lightweight pipes but becomes increasingly difficult and dangerous with large, heavy pipes. Unless the sling is exactly on the centre of gravity the pipe does not lift such that it is maintained level during the lifting and handling movements.
The most common alternative method is to cast a hole in the pipe wall at the centre of gravity. Because the hole is moulded into the pipe at the time of manufacture it is more easily arranged on the centre of gravity and is repeatably and reliably located for all pipes produced in the mould.
For lifting the pipe, a loop-eye of a sling is passed through the hole and a bar inserted through the eye from within the bore of the pipe such that when tension is applied to the sling, the bar contacts the bore of the pipe and anchors the sling to the pipe.
A disadvantage of this method is that it requires close supervision to ensure that the bar is of the required strength and is placed in such a way as to prevent its accidental withdrawal from the eye of the sling during load reversals.
After lifting, the bar is removed from the eye of the sling which is then pulled back through the hole which must be plugged.
Both methods are slow and cumbersome and during lifting and handling the pipe is able to see-saw about the sling, presenting handling difficulties, especially when pipes are often transported over rough ground during installation and then installed in narrow trenches.
A further problem arises after the pipe has been laid in the trench. It must be jointed to the previously laid pipes. After the pipe has been laid with its nose close to the bell-mouth of the previously laid pipe, the nose of the pipe is winched into the bell-mouth, over the rubber seal by using a winch is connected between the previously laid pipes and the new pipe. During the winching operation the bedding must either be removed from around the joint area or else it is pushed by the pipe nose into the joint. Another issue is that the nose of the pipe must be lifted into the bell-mouth and if it is forced in then it can damage the pipe joint and prevent a seal being effected.
The trailing flange of the bell-mouth also disturbs the bedding which requires additional levelling and compaction. Incomplete compaction results in joint instability during service which deteriorates joint security and pipeline performance.
After the pipe is laid the hole must be plugged to prevent the ingress of ground water and fill materials which lie above the pipe. If the hole is left without being plugged, the ingress of water and fill not only increases the hydraulic load of the pipeline and the risk of blockage, but also leads to deterioration of the fill over the pipe which can result in failure of the structures lying above the pipe, e.g. road failure.
In most cases it is not possible to cast a through-hole in the pipe wall because the former for the hole cannot extend to the inside surface without interrupting the pipe manufacturing process. For this reason, a blind hole is formed and there is a web of concrete between the bottom of the hole and the inside wall of the pipe.
The web of concrete is commonly removed by inserting a chisel from the outside of the pipe and striking with a hammer to break the web. Unfortunately, this method results in a cone shaped chunk of concrete being broken from the bottom of the hole which has the effect of making a small aperture very much larger. This thins and weakens the concrete wall over a large diameter around the hole, damages the compact, smooth interior wall, reduces the distance to the steel reinforcing, and in some cases exposing the reinforcing to corrosion. The damaged holes become further damaged during lifting and placing and are a significant cause of pipe deterioration over time, particularly as ground waters enter the hole and corrode the reinforcing. The broken chunks of concrete, if not removed, add to the burden of detritus within the pipe system, reducing flow and increasing the risk for blockage.
What is required is a directly coupled lifting system which does not require a sling around the pipe or a hole in the pipe, thereby significantly improving pipe handling and laying efficiency and improving pipeline performance and integrity.
One method of directly coupling a pipe is by casting an anchoring component into the pipe wall onto which may be attached an attachment device for connection to the hoisting system. Such lifting anchors are in widespread use for concrete elements. Such anchors are of a substantially elongate cylindrical or planar form and take the form of a free end shaped to connect to a connection device and another distal end which is shaped to form a mechanical interlock with the concrete in which it is embedded.
These lifting anchors are embedded in the concrete elements at the time of casting the concrete. When setting up the mould, the free end of the anchor which is shaped to attach to the lifting shackle is secured in a recess former. Most commonly the recess former is attached to the formwork or mould used to cast the concrete element. After the concrete has hardened and the mould or formwork is removed, the recess former is itself removed, leaving a recess in the surface of the concrete element such that the attachment end of the anchor is accessible.
There are special problems for casting such lifting anchors into the walls of pipes and other similar elements. The anchors must be capable of developing relatively high loads within the relatively thin walls of the pipe. Additionally, pipes are manufactured in closed or partially closed moulds which make the attachment of the anchor and its recess former difficult.
The mechanics of gripping the anchor and its recess former and their attachment to the mould or reinforcing to resist the significant centrifugal and other forces generated within the concrete during the pipe-making process makes the use of these anchors difficult for many pipe manufacturing processes.
Modern pipe making processes employ a stationary mould which is closed about a prepared reinforcement cage prior to being set into the pipe making machine.
The wall thickness as well as the distance between the outside diameter of the pipe and the reinforcing elements vary according to the design requirements for the strength of the pipes. In many cases a common mould is used for the manufacture of pipes with different wall thicknesses and different reinforcement configurations.
The concrete is cast by the pipe-making machine which flings or forces a relatively stiff mix of concrete through the reinforcement cage against the mould wall. This is commonly achieved by a rotating concrete spray head and/or internal rollers. The machine also incorporates a means of vibration of the mould assembly which continuously vibrates the concrete during the casting process to ensure the required degree of concrete compaction. The concrete flow, circumferential and differential motions between the concrete, reinforcement and mould give rise to complex forces generated within the concrete. Lifting anchors fastened directly to the reinforcement or the mould wall are therefore subject to significant dislodgement forces which generally precluded their utility. To overcome these problems some prior art applications have specially designed moulds fitted with mechanical means for rigidly locating lifting anchors in the moulds.
The capital cost and complication of mounting and dismounting anchors and recesses make the use of these types of anchors difficult for most modern and automated pipe making processes.
The genesis of the present invention is a desire to provide an improved recess former assembly for the economical installation of lifting anchors in pipes which can be adapted to modern pipe manufacturing processes without the need to modify existing moulds or install special mechanical equipment. Modern pipe making methods require a distance adjustable recess former assembly which can automatically adjust to the distance between the mould and the attachment point for the recess former assembly which is generally the steel reinforcement cage and which can take into consideration the variable pipe wall thickness and reinforcement configurations.
Safety standards require the use of safe lifting systems for the handling and installation of concrete pipes and pipe-like products. The economical installation of lifting anchors in pipes is expected to improve lifting safety and efficiency, reduce handling costs, provide an efficient method for laying the pipes and by the elimination of holes significantly improve pipe life, pipeline performance, stability and long-term reliability.
In accordance with a first aspect of the present invention there is disclosed a recess former assembly for creating a recess surrounding a cast in situ lifting element in a cast concrete element having a cast outer surface, said assembly comprising:
In accordance with a second aspect of the present invention there is disclosed a method of holding a recess former for creating a recess surrounding a cast in situ lifting element in a cast concrete element having a cast outer surface, said method comprising the steps of:
Preferably, in accordance with a first embodiment there is disclosed an assembly comprising a concrete lifting anchor with an elongate body with a first end shaped to provide a head for connection to an attachment device and second end shaped to provide mechanical interlock with the concrete into which the said anchor is embedded, a removable recess former for forming a recess in a concrete surface and which envelops the said anchor head, said recess former being shaped with an interior cavity to receive the said anchor head and an exterior shape which defines the form of the said recess in the said concrete surface to receive the said attachment device and a frame element made of metal or plastics materials which is interlocked to the said recess former and provided with means for attachment to a reinforcement cage, pre-formed from wires or similar elements cast within the concrete element.
Preferably, in accordance with a second embodiment the said recess former is shaped with a lower surface dimensioned to receive the lifting device for attachment of the said lifting device to the said anchor head after the removal of the recess from the concrete element and an upper surface shaped to bear against the internal wall of the mould used to define the surface of the said concrete element
Preferably, in accordance with a third embodiment the said recess former includes an attachment means to enable it to be firmly but removably attached to the said frame element.
Preferably, in accordance with a fourth embodiment the said frame element includes an attachment means with which it may be fixed to the said reinforcement cage.
Preferably, in accordance with a fifth embodiment the said attachment means is configured to permit movement in a direction substantially parallel to the said body of the said anchor to provide a means of adjustment to accommodate a variable distance between the said reinforcement cage and the said mould wall such that the upper surface of the said recess former of the said assembly may be positioned adjacent to the said mould wall either before or during the concrete casting process.
Preferably, in accordance with a sixth embodiment the said adjustment means is configured such that after fixture of the said assembly to the said reinforcement cage the said distance adjustment may be achieved without external manual or mechanical intervention other than by either closure of the said mould around the said reinforcement cage or by the pressure of the concrete bearing against one or more elements of the said assembly.
Preferably, in accordance with a seventh embodiment the said attachment means are formed as slotted clips, shaped to permit movement in a direction parallel to the axis of the said anchor.
Preferably, in accordance with an eighth embodiment the said slotted clips are shaped with a first open end shaped to permit the entry of the said wires of the said reinforcement cage, and a second closed end spaced at some distance from the said first end and a longitudinal axis between the said first and second ends.
Preferably, in accordance with a ninth embodiment, one or more of the said slots of the said slotted clips may have a longitudinal axis which is formed at an angle to the axis of the said anchor over at least some part of the length of the slot.
Preferably, in accordance with a tenth embodiment, the said open ends of the said slots of the said slotted clips is shaped with a restricted slot width to provide a restraint against the escape of the said wires.
Preferably, in accordance with an eleventh embodiment, either the said first or second end of the said slots of the said slotted clips is shaped with an enlarged slot width to provide a means of initial positioning the said assembly on the said wires prior to closure of the said mould around the said reinforcement cage.
Preferably, in accordance with a twelfth embodiment the said frame element includes a spring actuated distance adjustment means which provides a means of accommodating a variable distance between the said upper surface of the said recess former of the said assembly and the said reinforcement cage.
Preferably, in accordance with a thirteenth embodiment the said recess former assembly is configured to contain a spring pressure release mechanism which can be actuated by pressure of the closure of the mould against a trigger arm or the body of the recess former or by contact pressure by concrete against some part of the spring release mechanism or by vibration of the assembly during the casting of the concrete.
Preferably, in accordance with a fourteenth embodiment there is disclosed a recess former assembly comprising a lifting anchor with a head, a removable recess former which envelops the said anchor head for forming a recess in a concrete surface and a frame element which is interlocked to the said recess former and provided with means for attachment to a reinforcement cage, pre-formed from wires or similar elements manufactured from metals or plastics materials cast within the concrete element and at least one separate clip attached to the said wires lying adjacent the said means of attachment which prevents movement of the said attachment in a direction parallel to the longitudinal axis of the said wires.
Preferably, in accordance with a fifteenth embodiment the said recess former may comprise a body hinged adjacent the said upper surface to enable it to be opened and closed by a pivotal movement about the anchor head. The said recess former may comprise multiple separable bodies which form a single body when fitted together.
Preferably, in accordance with a fifteenth embodiment there is disclosed a said removable recess former for the casting of a said anchor in a concrete element wherein the said recess former has a curved surface which lies adjacent to the curved surface of the mould for the said concrete element.
Preferably, in accordance with an sixteenth embodiment there is disclosed an assembly comprising a lifting anchor with a head, a removable recess former which envelops the said anchor head for forming a recess in a concrete surface and a frame element which is interlocked to the said recess former and provided with means for attachment to a reinforcement cage, pre-formed from wires or similar elements manufactured from metals or plastics materials cast within the concrete element in which the said concrete element is a pipe or a pipe-like element cast within a mould which has a curved surface.
Preferably, in accordance with a seventeenth embodiment there is disclosed a concrete element which has a curved surface with a recess in said curved surface and an anchor having a head being embedded in said concrete element with said head located in said recess, wherein the top of said head is proximal with said curved surface.
Preferably, in accordance with an eighteenth embodiment there is disclosed a method of casting a concrete element which incorporates a reinforcement cage, and at least one anchor having a head and being embedded in the concrete of said concrete element with said head being located in a recess formed in a surface of said element, said method comprising the steps of:
Preferably, in accordance with a nineteenth aspect embodiment there is disclosed a method of casting a concrete element which incorporates a reinforcement cage, and at least one anchor having a head and being embedded in the concrete of said concrete element with said head being located in a recess formed in a surface of said element, said method comprising the steps of
Embodiments of the present invention will now be described with reference to the drawings in which:
Turning now to
The pipe 1 is lifted with a sling 21 with a loop-eye 22 which is inserted into the lifting hole 20 of the pipe and terminated in the bore 10 of the pipe by passing a bar 23 through the loop eye 22. When lifting by this method, the pipe 1 is unstable and may rotate about the lifting hole 20, shown by the arrows in
In addition a second wave-like disturbance 32 of the bedding 3 results from the tapered exterior surface of the bell-mouth of the second pipe 2 being thrust across the surface 30 of the bedding 3, leaving an uncontrolled depression 33 in its wake which requires filling and compaction.
It is apparent that the passage of the nose 16 of pipe 2 into the bell mouth 15 of pipe 1 and the final closure can be difficult to achieve and risks damage to the nose 16 of the pipe 2 being closed.
Complete perforation of the pipe wall 12 is achieved by introducing a chisel 25 or similar implement into the moulded well 24 and punching through to the bore of the pipe 10 using a hammer 26. A substantially cone-shaped piece of concrete 27 is broken from the bottom of the well 24 and falls into the bore 10 of the pipe 1, leaving a broken and uneven conical surface 28 in the inside surface 11 of the pipe, opening to the lifting hole 20.
This broken surface 28 and irregular hole 20 results in uncontrolled thinning and loss of strength of the pipe wall 12 in the vicinity of the lifting hole 20 and exposes the concrete and any reinforcement embedded therein to corrosion from ground waters infiltrating into the hole 20 or pipeline waters being forced out under pressure.
The two anchors shown in
A significant problem exists for the placement of the lifting anchors 60 with their recess formers 50 when pipes 1 are manufactured by the vertical casting method.
On the other hand, as shown in
It can therefore be appreciated that whilst it is possible to attach prior art recess formers 50 and their enclosed anchors 60 lifting anchors 60 directly to the mould 70 or the reinforcement cage 80, it is not generally practical for many pipe manufacturing methods, particularly vertical pipe manufacturing methods.
The recess former 50 is of a hemispherical shape formed in two halves 51A and 51B hinged in the centre 52 and separated by a transverse slot 56 which receives the attachment end 61 of a lifting anchor 60. The interior cavity 53 is shaped to receive the enlarged head 61 and lesser body 62 of lifting anchor 60 and restricts the anchor 60 from moving or being dislodged from the former 50 during casting of a concrete element.
A principal disadvantage of the prior art recess formers 50 is that they require mechanical attachment to the mould wall 70 to maintain a closing force to be applied to the recess former 50 to ensure complete closure of the two halves 51A, 51B about the anchor 60 so as to ensure that the anchor 60 does not move away from its optimum position within the recess former 50 during the spin casting operation in which the mould is rapidly rotated about the longitudinal axis of the pipe. Alternatively, for pipe making processes using roller compaction or vertical casting methods, aggressive vibration and/or shearing forces are applied to the concrete to ensure full compaction of the concrete prior to curing.
The prior art recess formers 50 are principally used for attachment to flat formwork and so the rear surface 57 of the recess former 50 is flat when the recess 50 is completely closed about the anchor 60. It is readily seen from
It can be seen from the diagram in
The force resisted by tearing the anchor from the pipe wall 12 is proportional to the embedment depth 91 and for any particular anchor it is always desirable to locate the bottom of the anchor 64 as deeply into the concrete as possible. Since the pipe wall thickness 12 varies considerably for a range of pipe diameters and according to the service conditions required of the pipe, for a given cover 92 there is a wide range of anchor lengths to achieve the optimum anchorage. In practice, it is neither practicable nor economic to manufacture such a range of anchor lengths and so standard length anchors are used for many different pipe sizes, and so the depth of anchorage 91 varies accordingly.
Ideally the head 63 of the anchor 60 should be located close to, or adjacent to, the inside surface 71 of the mould to permit a wider range of embedment depths 91 to maximise the pull out strength of the anchor 60 from the concrete element 1 according to wall thickness 90 and weight of the concrete element 1, for a given anchor embedment depth, Judicious choice of the embedment depth 91 minimises the inventory of anchors 60 required for the manufacture of a wide range of pipe dimensions and weights.
The inventor has determined that it would be desirable to allow the former 50 to be closed around the anchor head but not physically attached to the mould wall 70, thereby eliminating the need for attachment holes to be provided in the mould wall 70 and substantially eliminating the distance 93. This is not practically possible with the prior art recess formers 50 because the hinged halves 51A and 51B of the recess formers 50 shown in
There is a further significant disadvantage for the pipe manufacturer using prior art recess formers 50 with the bolt holes 73 in the mould wall 70 for the attachment of the recess 50. Sometimes the moulds 70 are used in combination with other mould sections to make different length pipes and other products where the location of the centre of gravity 42 shown in
Differential movement during the pipe making process between the anchors 60 and recess formers 50 in the mould 70 and the adjacent pipe reinforcing elements 80 leads to forces being transmitted to the anchors 60 and recess formers 50 which either prevent complete closure of the recess formers 50 about the anchor 60, or lead to dislodgement from the mould wall 71. Such forces commonly result from leverage developed between the anchor 60 and reinforcing 80 and/or movement during the setting up of the reinforcing 80 within the mould 70 and then during the aggressive processes involved with pouring, vibrating, compacting and/or spinning the concrete. These forces may prise open the recess former 50 during the casting process thereby creating spaces between the anchor 60 and the recess former 50 which permit the entry of cement laden waters, or cement paste, into the interior cavity 53 of the recess former 50.
These problems become more significant when the dimensions and mass of the pipe 1, reinforcing 80 and anchors 60 increase.
After the concrete has hardened, the mould 70 and recess former 50 are removed thereby exposing the attachment end of the anchor 60 inside the recess formed by the removal of the recess former 50.
When using prior art recess formers 50 as described above, cement which has flowed into spaces between the recess former 50 and the anchor 60 makes the connection of the lifting shackle, or other attachment device, difficult or impossible. This cement is extremely difficult to remove because the anchor 60 is located below the surface of the concrete 13. The removal of the hardened cement is impeded by the confining space of the walls of the recess formed in the concrete by the recess former 50.
Increasingly modern pipe-making plants manufacture pipes by the vertical casting process in which the pipe mould 70 is closed over a prepared reinforcement cage 80, both of which are aligned in the vertical direction. In some processes the mould 70 is hinged along one side to enable it to be opened and closed however in others the moulds are completely closed. It can be realised that it is not practically feasible to fix an anchor 60 and recess former 50 to the mould 70 because this would require penetration of the mould 70 by the fixing mechanism 72 otherwise the mould 70 could not be withdrawn from the cast pipe 1 after casting. Some prior art solutions to this problem involve the expensive and complicated addition of mechanical devices to the mould 70 for the insertion and withdrawal of a recess former 50 for placement of inserts 60. These solutions are not generally practical for retrofitting to existing manufacturing plant.
What is desirable is a method of casting a recess around the anchor, and of retaining the anchor tightly in its correct position in such a way that the integrity of the recess is not compromised during the casting process and which guarantees that after removal of the recess former that the attachment aperture will be clean and free of cement, or other fouling materials. Additionally, a recess former which may be closed around the head of the anchor, and which does not require an outside closing force to enable it to remain properly intact, would be of great benefit to modern production facilities where it is not desirable to damage the walls of the mould by drilling or other attachment means. Additionally, a recess arrangement is desirable which reliably locates the attachment end of the anchor against the inside surface of the mould to maximise embedment for a minimum range of standard anchor lengths and spaces the reinforcing at the desired distance from the outside and inside surfaces of the pipe.
It would also be desirable if the anchor and its recess could be attached to the reinforcing cages 80 prior to their introduction to the moulds, so that there is no need for special moulds or alterations to moulds or for the need to attach or remove elements from moulds. In other words, for a system which can be used with existing moulding equipment without the need for alteration, or additional major capital equipment.
There is a further complicating problem for the attachment of the recess former 60 and/or its anchor to the reinforcement cage which can be realised by reference to
If the recess former 50 and/or its enclosed anchor 60 were to be fixed to the cage 80, a wide range of fixings would be required to cater for the many different variations in distances Rd which vary according to the wall thickness and required Rd to meet the design strength requirements of the concrete element 1. Whilst the
Turning now to the preferred embodiment of the present invention shown in
The outer surface 178 of the recess former 150 is shaped to fit the inside surface 71 of the mould. In the preferred embodiment the surface 178 has a shape which is outwardly convex so as to fit closely against the inside wall 71 of a mould 70 for making a pipe (only part of which is illustrated in
A preferred embodiment of the assembly 200 has a recess former 150 fitted into and attached to a surrounding frame 180 preferably made of plastics material. The frame 180 has a substantially closed ring section 181 with an upper surface 181A and a lower surface 181B from which extend non-rigid arms 182 of an arcuate form which act as springs and which enable deflection in a direction normal to the surface 178 of the mould 70 by flexure of the arcuate arms 182 when pressure is applied to the upper surface 178 of the recess former 150. The arms 182 are terminated with one or more clips 183 for attachment of the frame 180 of the assembly 200 to the reinforcing wires 81 or 82 of the reinforcing cage 80, of the concrete element 1 prior to casting. A slot 184 is formed into each clip with an open entry shaped with a restriction 185 which is dimensioned to allow the clip 183 to be attached to the wire 81 but to prevent the frame 180 from disengagement once it has been clipped into position. This provides a useful means of retaining the assembly 200 in the optimum position relative to the wall of the pipe mould 70 during casting of the concrete pipe 1.
The slot 184 is dimensioned so as to minimise lateral movement but allow sliding engagement with the wire 81 to permit relative movement between the recess assembly 200 and the wire 81 in a direction along the slot 184, between the open end 188 and the closed end 189 of the slot 184. An enlarged section 187 (or multiple enlarged sections, not shown) can be formed at locations along the walls 186 of the slot 184 to provide preferred indexed positions of the recess assembly 200 relative to the wire 81. In
When the recess assembly is located with the enlarged section 187 of the slot 184 co-incident with the wire 81, the assembly 200 is held in a stable position and provides clearance Rd between the top surface 178 of the assembly 200 and the mould 70. This clearance Rd enables the mould to be closed over the reinforcement cage 80 without contacting and dislodging the assembly 200. The length of the slot 184 between the restrictions 185 at the open end 188 and the closed end 189 is equal to or greater than the distance Rd required for the movement of the recess assembly 200.
Turning now to
The assembly 200 is fixed to the reinforcing cage 80 and positioned in the correct orientation with respect to the mould wall 71 without actually fixing the assembly 200 to the mould 70. This has the benefit that the reinforcing cage 80 with the attached anchor assembly or assemblies can be manufactured separately and introduced as a completed assembly into the mould 70 prior to casting and also that any relative movement between the mould 70 and cage 80 during the casting process does not result in additional forces transmitted to and resisted by the anchor 60 or assembly 200.
It can be seen in
Further embodiments of the present invention are shown in
The embodiments shown in
The embodiments shown in
The clip 330 also has a notch or hook for engagement with the frame 181.
As seen in
Tension in the band 324 causes the clip 330 to rotate anticlockwise, thereby disengaging the notch 332 from the frame 181.
When both the trigger 320 and the trigger clip 330 become disengaged, the spring force P from the springs 182 causes the frame 181 and recess former 150 to translate until the surface 178 of the recess former 150 bears against the interior surface 71 of the mould 70.
The further embodiments shown in embodiment shown in
The embodiment shown in
A second trigger clip 630 is attached to a second reinforcement wire 81 by a clip 631 (obscured) which is free to rotate about the reinforcement wire 81. The clip 630 has an arm 632 with an aperture 633 in a distal end 634 which lies below the level of the surface 178 of the recess former 150.
A drawbar 640 with a first end 641 with an attachment means 642 therein (shown as an aperture) passes over the attachment means 642 for connection to projecting arm 623 of the trigger 620. The drawbar 640 has a distal end shaped with a nose 646 which passes through, and is retained in, the aperture 633 of the second trigger clip 630.
The drawbar 640 passes through a channel formed in the surface 178 of the recess 150 such that it does not project from the surface 178. That is, the drawbar 640 is not proud of the surface 178.
As shown in
The embodiment shown in
The trigger arm 620 is formed with a clip 621 (partially obscured) one end for attachment to the reinforcement 81 and shaped so as to be freely rotatable about the reinforcement 81 and a projecting arm 623 on a distal end 624 for engagement with the edge 75 of the mould 70 (not shown).
The trigger 620 has a lateral arm 625 projecting from the arm 623 which has a nib 626 located at the distance E indicated by the arrows shown in
A second trigger clip 630 is attached to a second reinforcement wire 81 by a clip 631 (obscured) which is free to rotate about the reinforcement wire 81. The clip 630 has an arm 632 with an aperture 633 in a distal end 634 which lies below the level of the surface 178 of the recess former 150.
A drawbar 640 with a top surface 647 has a notch 648 in the top surface 647 located at a distance from a first end 641. The notch 648 provides a means for engagement and retention of the nib 626 of the trigger 620.
The drawbar 640 has a distal end 645 shaped with a nose 646 which passes through, and is retained by, the aperture 633 of the second trigger clip 630.
The drawbar 640 passes through a channel 650 formed in the surface 178 of the recess 150 such that the upper surface 647 of the drawbar 640 lies adjacent the surface 178 of the recess former 150.
The nose 646 of the drawbar 640 is engaged in the aperture 636 of the trigger 630. The position of the notch 648 in the drawbar 640 aligns with a line 649 which passes through the nib 626 of the trigger 620 at a distance E from the centre line CL of the wire 81. The spring force P referred to in
It will be understood from the foregoing explanations that when the end 75 of the mould 70 contacts the trigger arm 620 it causes it to rotate about the wire 81. This rotation is such that the nib 626 moves in an arcuate path around the centre CL of the wire 81, which is indicated as a circle of a broken line in
The distance E is selected to ensure that when the rotation of the trigger arm 620 causes the nib 626 to align with the centreline CL of the wire 81, the nib 626 has moved in a vertical direction sufficient to allow complete disengagement between the nib 626 of the trigger arm 620 and the notch 648 of the drawbar 640. Also that the distal end 645 of the drawbar 640 is restrained from further movement by contact with the recess former 150 and retained within the slot 650 in the upper surface 178 of the recess former 150. Disengagement of the trigger arm 620 from the drawbar 640 permits further unrestrained rotation of the trigger arm and ensures that the drawbar 640 is captured within the slot 650 of the recess former 150.
The trigger clip 720 has a lateral arm 725 into which is formed a projecting engagement pin 726 which connects to a drawbar 740 by passing through an aperture 741 formed in a first end 742 of the drawbar 740.
The drawbar 740 has a distal end 743 into which is formed a seat 744.
The distal end 743 is configured to bear upon the surface 176 of the frame 181 and is moveable a distance longitudinally without being obstructed by the outside of the frame 181.
A second trigger clip 730 is attached to a second reinforcement wire 81 by a clip 731 (obscured) which is free to rotate about the reinforcement wire 81. The clip 730 has an arm 732 with a notch 733 in a distal end 734 for engagement with the seat 744 of the pushrod or drawbar 740.
As shown in
The spring force in the springs 182 causes the frame 181 and recess former 150 move until the surface 178 of the recess former lies adjacent the surface 71 of the mould 70.
The foregoing describes only some embodiments of the present invention and modifications, obvious to those skilled in the concrete arts, can be made thereto without departing from the scope of the present invention. For example, the attachment means for the two recess parts 151A and 151B (
Similarly, the recess former 150 can take the form of the body with a cavity to contain the attachment end 61 of the anchor 60. The anchor 60 is retained within the recess 150 by any or all of a resilient sealing element, shaped retention collets, or magnetic means which are slidably engageable within the cavity of the recess body. These retention arrangements are configured so as to enable the body to be removed by pulling it from the attachment end 61 of the anchor 60 after the concrete has cured.
Furthermore, the recess former 150 need not have a spherical form. Instead, it can be shaped with tapered portions which can be removed from the hardened concrete. Similarly, the recess former can take the form of a number of separable bodies each of tapered shape which, when fitted together, enclose the attachment end 61 of the anchor. These tapered bodies are removable by withdrawal from the hardened concrete.
Similarly, the recess former 150 can be formed in one body which is hinged to enable it to be closed about the attachment end 61 of the anchor 60. Alternatively, the anchor 60 can be of a planar section and the attachment means for the lifting device effected by an aperture in the planar body. Similarly, the anchor 60 can be formed with an internal, or external, thread or other interlocking form for attachment of a compatible interlocking lifting device. Such an arrangement can include an internal thread to accept a bolt.
Furthermore, although the preferred embodiments relate to the manufacture of pipes, the description is equally applicable to other cast concrete elements where there is a variation in the distance between the reinforcement to which the recess former assembly is attached, and the concrete surface.
Other embodiments (not shown) of the assembly 200 with other means for attachment of the recess former 150 to the frame 180 and/or other means for effecting the spring elements 182, 182A, 190, 191 or other clipping arrangements 183 adapted to attach various configurations of the reinforcement cage 80 and its longitudinal reinforcing wires 82 and the radial wires 81, are possible.
It will be apparent that the general arrangement takes the form of a recess former assembly (200) for creating a recess surrounding a cast in situ lifting element (60) in a cast concrete pipe (1) having a cast outer surface. The assembly has a frame (180) having locating lugs (183) engageable with components (81) of a reinforcing cage (80) to be positioned within the mould (70). The engagement of the lugs with the reinforcing components locates the frame in a rest position spaced from the mould. A removable recess former (150) is releasably retained in the frame. A lifting element (60) is retained within the recess former and has an anchor portion (64) extending therefrom. A non-rigid interconnection (182, 182A, 190, 191) between the lugs and the frame to bias the frame and recess former to be urged towards the mould into an operative casting position in which at least a portion of the recess former substantially abuts the mould.
Preferably the non-rigid interconnection between the lugs and the frame takes the form of at least one flexible arm (182). Alternatively, the non-rigid interconnection between the lugs and the frame can take the form of a spring (182A). Preferably such a spring or the arm is moulded from a plastics material being the material from which the lugs on the frame are also moulded.
Preferably the locating lugs take the form of U-shaped bights (for example slot 184) formed by a pair of legs (183 having feet 185 which restrict the entrance to the slot 184). The bights or slots 184 can face either towards or away from the mould (70). In addition, the frame preferably additionally includes brake shoes (such as lateral restraint clips 195) which prevent the assembly sliding along the cage component (81). The reinforcing components of the cage preferably have a longitudinal axis and the bights (184) are located substantially normal to the longitudinal axis.
The movement from the rest position to the casting position is preferably assisted by the pressure of the flowable concrete being forced into and through the cage (80). Preferably the frame (180) is retained in its rest position by a releasable latch (for example the trigger 320 or 620). This releasable latch is released or triggered by movement of the mould (70) relative to the cage (80).
The general arrangement also uses a method of holding a recess former for creating a recess surrounding a cast in situ lifting element in a cast concrete element having a cast outer surface. This method uses the steps of:
The term “comprising” (and its grammatical variations) as used herein is used in the inclusive sense of “including” or “having” and not in the exclusive sense of “consisting only of”.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021902152 | Jul 2021 | AU | national |
| 2021902454 | Aug 2021 | AU | national |
| 2021902539 | Aug 2021 | AU | national |
| 2021902540 | Aug 2021 | AU | national |
| 2021903061 | Sep 2021 | AU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/AU2022/050723 | 7/11/2022 | WO |
