The invention will be described with reference to portable manhole formwork, and particularly formwork of larger size which is moved using a lifting crane. However, the improvements to formwork need not be limited only to manhole formwork and may find application in other types of formwork where similar problems arise.

BACKGROUND ART Concrete structures such as manholes or pits are used to provide access to underground services such as stormwater, sewer, electrical, optical fibre and the like.

A pit is usually a small square or rectangular structure beneath the ground level that a person can get down or lean down into to carry out work. For instance, a gully or field pit usually has a grate or lid that allows water to enter into a storm water system. An electrical pit is one where a person can enter to carry out work on cables and the like. These pits can be as small as 0.45 X 0.45 X 0.900 mm. deep and up to 2000 X 2000 X 2000 mm. deep. These larger structures are more commonly referred to as concrete structures rather than pits.

A manhole is usually a round or oval structure that is widely used in storm water or sewerage systems. The manholes have rounded corners for better hydraulics and to prevent build-up of sediment. The manholes can range from a diameter of about 600 mm. up to a diameter of 3m or more and can have varying depths. These manholes are formed from concrete with the smaller manholes being formed in a factory and transported to site, while the larger manholes are made on site using manhole formwork.

Figure 1 illustrates a typical prior art manhole form which connects two pipes.

For on-site manufacture of manholes, the forms are formed from an inner form (see Figure 2), and an outer form (see Figure 3). The inner and the outer forms are made from curved form panels, each panel terminating in a flange or rib with the ribs abutting together and bolted together to create the circular form. This is well-known in the art. The forms have a finite length, and if a manhole form is unusually long, a number of forms are placed on top of each other. For this reason, both the top and the bottom horizontal ribs (see 15,16 Figure 3) of the forms should have a flush finished surface. Once the forms are correct located, wet or dry concrete is poured between the inner and the outer forms and left to cure. At the correct time, the forms may be"slipped" (that is pulled out while the concrete is still relatively wet and curing), or"stripped" (that is disassembled and removed once the concrete has cured).

The form panels need to be constructed from extremely strong material such as steel that is reinforced and braced with more steel in order to withstand the quite large pressures of vibrated wet concrete being poured between the forms. Therefore, these forms are considerably heavy. As well, when the forms are"slipped", the forms are pulled out while the concrete is still wet and there is considerable friction between the wet concrete and the formwork, which in turn requires a large lifting force (typically via a crane) to remove the forms.

In order to allow the inner and the outer forms to be moved and lifted by a crane, it is conventional that the forms are provided with an attached steel lifting lug (see for instance inwardly extending lugs 20 in Figure 2 and the outwardly extending lugs 20 in Figure 3). Generally, one steel lug is welded on each form panel so that a crane or other machine with chains and hooks can lift the forms.

There are many disadvantages with the current lifting techniques.

Firstly, forms with different diameters are formed from attachment of a different number of form panels. For instance, a 900mm diameter form may have three panels, while a 1.2m diameter form may have

four panels. Larger forms such as 2m diameter or more, and especially the outer forms (which have a larger diameter) can be formed from more than four panels.

This creates significant difficulties and dangers in lifting the forms by a crane. This is because the large weight of the form and especially the enormous loads applied when"slipping"a form from wet concrete, places enormous strain on the lifting chains and also on the formwork panels. It is extremely important to make sure that the length of chain from each lug to the lifting hook of the crane is the same on each form. If one of the chains is longer than the other chains, the form will be lifted essentially by the remaining chains, and conversely if one chain is shorter than the other chains, the form will be essentially lifted by a single chain. When this happens, the enormous loads will deform the form panels during the lifting process. Also, if the form is to be"slipped", damage to the resultant wet concrete can occur if the lifting is not conducted evenly around the form. The length of the chain from the lug to the hook should be measured and should equal a minimum distance to give a lifting angle of approximately 60°.

In practice, it is found that correct lifting of a manhole is usually not carried out, which can deform the formwork panels and/or damage the formed concrete manhole.

Another disadvantage with the conventional lugs (see Figure 2 and Figure 3) is that they necessarily project outwardly or inwardly from the form panels. This makes the lugs a snag point for workers in the area. As well, the lugs can be damaged or bent which can create danger in the lifting of a manhole form. Another disadvantage is that the form panels cannot easily be nested or stacked together and Figures 4 and 5 illustrate the difficulties with nesting or stacking form panels when not in use and illustrate how the lugs interfere with the efficient stacking process.

Another disadvantage and danger with existing lugs is that the lugs must have a hole extending therethrough to allow the lugs to be attached to a chain hook. The chain hook has to be extremely robust and is usually of a fairly thick and blunt design. The lug, on the other hand, has to be kept as

small as possible (for instance to improve stacking and minimise snag points), and it is found that conventional lugs have an aperture of approximately 50mm in diameter. The chain hooks are often too rounded or blunt to properly pass through such a small opening and it is not uncommon for a worker to have to hold the hook in place while the machine operator begins to lift the manhole. This is a most unsafe practice and can be the cause of severe injuries. It is not possible to simply make the opening larger as this requires the lug to be made larger which intensifies the problems described above.

Another frustrating problem with existing form panels and particularly with manhole form panels is in the assembly of the form by joining the various panels to each other to complete the shape and diameter desired.

The form panels have peripheral steel ribs and when adjacent panels are placed together, the ribs abut. The ribs are provided with openings which align and bolts are passed through the openings to bolt the two panels together. There is considerable frustration experienced on site by the end user in assembling inner and outer manhole forms.

When the forms are fairly large and require attachment of four or more panels, the number of bolts which are required to be tightened is considerable. The bolts are finicky to use and are usually wet, slippery, coated in mud, and the like. It is common for the bolts to be stripped or damaged which results in incomplete or insufficient attachment of the panels together. If the panels are joined too loosely, the concrete pour and the subsequent vibration of the wet concrete will usually result in concrete fines finding its way into the various openings which can damage the formwork and/or the concrete manhole if the manhole form is slipped off. If insufficient bolts are used, the form panels can deform and be damaged during the concrete pour or subsequent removal of the forms.

It is also known to use pins and wedges to join form panels, but these are also extremely frustrating to use, as a large number of small pins needs to be hammered and placed up and down the ribs and in a confined area this can be extremely frustrating and aggravating and can result in

incomplete attachment of the panels together.

OBJECT OF THE INVENTION One form of the present invention is directed to a form panel which does not have a projecting lug and which is provided with its own length of lifting chain or similar line member. This does away with all the disadvantages of protruding lugs and the difficulties and dangers which occur if the lifting chains are of the wrong length.

Another form of the present invention is directed to a simple method by which form panels can be attached together without requiring a large number of bolts or pins to be used.

It is an object of the invention to provide a panel which may overcome the abovementioned disadvantages or provide the public with a useful or commercial choice.

In one form, the invention resides in a concrete form panel of the type which from time to time needs to be lifted by a crane, the panel having an anchor pin fixed thereto, and a length of lifting chain one end of which is non removably attached to the anchor pin and the other end of which is adapted to engage with a lifting hook of the crane.

In a more particular form, the invention resides in a concrete form panel of the type which needs to be lifted by a crane, the form panel having a main body portion, which may be curved, and having an upper peripheral rib which extends outwardly from the main body portion, an anchor pin which is fixed to the main body portion and which does not protrude from the peripheral rib, and a length of lifting chain, one end of which is non- removably attached to the anchor pin, and the other end of which is adapted to engage with a lifting hook of the crane.

In a more particular form, the invention resides in a panel as described above wherein the anchor pin forms part of an assembly which has a load sharing backing plate which is fixed to the panel and at an upper edge of the panel, the backing plate having a pair of spaced apart extending members between which the pin is located to space the pin away from the backing plate to allow the chain to be attached to the pin.

In another form, the invention resides in a formwork panel of the type which from time to time needs to be lifted by a crane, the panel having a length of line member which is flexible and substantially inextensible, the line member being permanently attached to the panel and being engageable by the crane to enable the panel to be lifted by the line member.

In another form, the invention resides in a camping assembly to clamp two form panels together, each panel having a longitudinal flange which abut together when the panels are brought together, the assembly having an elongate locking channel which, in use, is fitted over the abutting flanges to lock the flanges together.

The form panel is typically of the larger and heavier type which cannot ordinarily be maneuvered by workers and requires lifting by a crane.

Typically, such panels are used in the assembly of a manhole form.

The panel can be formed from steel or other strong and rigid material. The panel is typically curved such that when adjacent panels are attached together, a cylindrical or oval form is formed. The panel has an upper edge, a lower edge, and a pair of longitudinal side edges. Typically, as illustrated in Figures 2 to 5, the upper edge of the panels are formed with horizontal ribs on the upper and lower edges and vertical ribs on each longitudinal side edge. These ribs are typically formed from steel. The ribs on the longitudinal side edges may have a series of spaced apart aligned openings through which bolts can pass to bolt adjacent panels together. The function of the ribs is to provide additional strength against deformation of each panel.

The panel has an anchor pin fixed thereto. The anchor pin may be in the form of a steel circular pin which is sufficiently thick to not deform under lifting loads. A steel pin with a diameter of between 10 to 20mm is suitable for many panels but of course sturdier pins may be required for larger panels.

In one form, the anchor pin is positioned adjacent the upper edge of the form panel and if the form panel is provided with a horizontal rib, the anchor pin may be positioned immediately below the horizontal rib.

In order to distribute the loads from the pin over a larger area of the form panel, the anchor pin can form part of an assembly. The assembly can have a load sharing backing plate which can be fixed (for instance welded) to the panel wall. The backing plate can be provided with a pair of spaced apart extending members between which the pin is located to space the pin away from the backing plate. The backing plate and the spaced apart extending members should be sufficient strong and sturdy to withstand the lifting loads.

In one form of the invention, the anchor pin is positioned such that it does not protrude from the outer edge of the upper horizontal rib. This is in distinction from prior art steel lugs which always project quite significantly from the horizontal rib and therefore makes stacking of the panels very difficult. By having the anchor pin within the confines of the width of the upper horizontal rib, the panels can be stacked much more economically and the anchor pin does not project and therefore is less susceptible to damage, snagging, and the like.

A length of lifting chain forms part of the panel. One end of the lifting chain is attached to the anchor pin in a non-removable fashion by which is meant that it cannot inadvertently come off the pin. In a suitable form, one link of the chain (typically the end link) extends about the anchor pin to non- removably attach the chain to the pin. Of course, other forms of attachments are envisaged which may allow the chain to be removed from the pin for maintenance and repair but will not allow the chain to inadvertently be removed from the pin. The chain should be strong enough to withstand the lifting forces and a steel linked chain can be used. The chain is designed to have a particular length and the advantage of this is that by having the length pre-determined, there is a reduced likelihood of the chains of adjacent locked together panels being of different length and therefore providing different stresses and strain to the form. The length of the chain can vary to suit but in one form the length is such that the length from the anchor pin to the hook should be such to give a lifting angle of approximately 60°.

The other end of the chain is adapted to engage with the lifting

hook of the crane or other type of lifting device. An advantage of the present arrangement is that this end can be formed with a quite large looped portion which will allow it to easily fit over even blunt hooks of the lifting chain. This does away with the need for a person to physically hold the chain onto the hook during the lifting process. The loop portion can be in the form of an enlarged link or other suitable arrangement.

In one form of the invention, the panel is provided with a storage area to store the lifting chain when not in use. The storage area can be in the form of a small steel sleeve or box in which the chain can be placed.

The lifting chain is to be construed broadly and may include other types of line members which are strong enough to lift the form. These may include steel cables, composite materials, and the like. In practice however, it is found that a linked chain is considered suitable for the present time. Another advantage with the linked chain is that the chain is moveable relative to the anchor pin and this minimises wear and tear on the chain.

In another form of the invention, there is provided a clamping assembly to clamp two form panels together. The clamping assembly comprises an elongate locking channel which fits over the longitudinal side ribs (or abutting fanges) of adjacent panels to lock the flanges together. This arrangement does away with or at least minimises the need for a large number of nuts and bolts or pins and wedges to lock the panels together.

In one form, the abutting flanges present a beveled free edge to facilitate attachment of the locking channel. The locking channel therefore does not require beveled free edges the advantage of which will be described in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will be described with reference to the following drawings in which Figure 1 shows a typical prior art manhole interconnecting two pipes.

Figure 2 shows a typical inner manhole form which is widely available in the marketplace.

Figure 3 shows a typical outer manhole form which is widely available in the marketplace.

Figures 4 and 5 show the difficulty with nesting or stacking existing inner and outer manhole forms.

Figure 6 shows an outer formwork panel and illustrating the anchor pin and the length of lifting chain.

Figure 7 illustrates an inner formwork panel having the same anchor pin and lifting chain.

Figure 8 is a close-up plan view of the anchor pin.

Figure 9 is a close-up front elevation view of the anchor pin of Figure 8.

Figure 10 is a close-up side elevation view of the anchor pin of Figures 8 and 9.

Figure 11 shows clamping of two form panels together using an elongate locking channel.

Figure 12 shows another view of the attachment of Figure 11.

Figure 13 shows a plan view of the attachment of Figure 11 and Figure 12.

Figures 14-16 show a variation to the locking channel.

BEST MODE Referring to the drawings and initially to Figure 1, there is illustrated a manhole 10 of conventional design and formed from concrete and which is used to interconnect to adjacent pipes 11,12. Manhole 10 can be of various diameters (typically from 0.5 to 3m) and of various lengths (typically 1 to 3m).

Figure 2 illustrates a known prior art inner manhole form and Figure 3 illustrates a known prior art outer manhole form. The inner manhole form (Figure 2) in the embodiment is formed from three form panels 13A-3C each being identical and formed from strong steel plate. The panels are curved such that when attached together a cylindrical form is formed.

Similarly, the outer manhole form (Figure 3) is formed from four formwork panels 14A-14D of identical shape.

Better illustrated in Figure 3, each panel is reinforced by upper and lower horizontal ribs 15,16 and vertical longitudinal side ribs 17,18. The ribs are made-from steel plate and can have a width of between 10 to 50mm depending on the size of the form panel. Figure 3 shows how the various form panels are attached to each other with the longitudinal ribs 17,18 of each form panels abutting with similar ribs on an adjacent form panel and the ribs are bolted together via a number of bolts 19.

Each form panel (both for the inner form Figure 2 and the outer form Figure 3) is provided with a strong sturdy steel lug 20. Each lug is provided with an opening through which a hook of a linked chain can pass.

Figures 2 and 3 nicely illustrate the difficulties with conventional lifting of manholes. For instance, in Figure 2 the inner form has three panels, and is lifted by a lifting chain which has a central steel ring 21 which attaches to the lifting hook 22 of a crane. Attached to and extending from steel ring 21 are three lengths of chain link 23A-23C with each chain link terminating in a hook which passes through the opening in lug 20. The hooks are generally fairly blunt and do not always properly pass through the opening in lug 20. As well, once the inner form has been removed, the outer form needs to be removed and because the outer form has four form panels, the tendency is to simply attach the three chain links to three of the four lugs and to keep one lug free. When the outer (large and therefore heavier) form is removed, the unbalanced forces can cause warping or deformation of the form panels as the form panels are not being equally lifted.

The lugs 20 project substantially out from the upper horizontal rib 15 and this makes nesting and stacking of the form panels difficult (this being illustrated in Figure 4 and Figure 5).

The present invention does away with the need for projecting lugs and also overcomes the difficulties with the lifting chains. Referring to Figures 6 and 7, there is illustrated an outer form panel (Figure 6) and an inner form panel (Figure 7). Outer form panel 25 is similar to the prior art panels illustrated in Figure 3 in that it has upper and lower horizontal ribs 15, 16 and vertical longitudinal side ribs 17,18, these ribs formed from steel plate

and welded to the steel curved panel 25. For larger panels, a further central vertical steel rib 26 is welded to the form panel and between the upper and lower horizontal ribs 15,16. Similarly, the inner form panel 27 illustrated in Figure 7 has more or less identical ribs 15-18 and 26.

Each form panel 25,27, in the embodiment, is provided with its own length of lifting chain which is attached to an anchor pin. In Figure 6, the anchor pin 28 is provided to one side and adjacent vertical rib 26 and immediately below horizontal rib 15. In the embodiment, horizontal rib 15 has a cut-out portion (see Figure 6) to allow better access to anchor pin 28.

Figures 8,9 and 10 give close-up details of anchor pin 28. In Figure 8 (a plan view), there is illustrated top horizontal rib 15 extending at right angles outwardly from the form panel 25 (or inwardly from form panel 27). The cut- out portion 29 is more clearly evident and makes the anchor pin 28 clearly visible. Anchor pin 28 is a solid sturdy steel pin which does not deform under the lifting loads applied to it. Attached to anchor pin 28 is the last link 30 of a linked chain 31. (Figure 8 only shows one link 30 while Figure 9 shows two links and Figure 10 shows three links of the linked chain.) Link 30 extends about pin 28 but is not welded to the pin and therefore can freely rotate about the pin and can also slide along the pin but only within the pin confines. Pin 28, in the embodiment, forms part of an assembly which includes a strong steel backing plate 32 (better illustrated in Figure 9 and Figure 10) and which is welded to the remainder of the form panel 25. Extending from plate 32 are a pair of spaced apart extending members 33,34 which are provided with apertures to accept the ends of anchor pin 28. If desired, member 33 can be attached to rib 26 for additional support and both members 33,34 can be fixed to top rib 15 (see Figure 10) for additional support.

The other end of the chain 31 is provided with a large loop portion 36 (better illustrated in Figures 6 and 7) and this can attach very easily around the lifting hook 22 (see Figure 2) of a crane or similar member. The chain, when not in use, is housed within a housing 37 which can be formed from steel channel member and which functions to prevent the chain from

snagging when not in use.

It can be seen that the form panel, according to an embodiment of the invention, is provided with its own lifting chain which has a correct length and can be easily attached to a lifting hook. The anchor pin 28 and the chain and even the housing 37 does not extend past the width of top, bottom or side ribs 15-18. By having the attachment pin snugly below top rib 15, it is safe from damage, snagging, and the like. There is almost a zero error rate in attachment of the chains to a lifting hook which means that the manhole forms can now be safely lifted without damage to the forms, the formed concrete or without danger to operators.

These panels have advantages over existing panels including the lack of protrubances creating a safety hazard, the lack of protrubances to damage other panels when being stacked, each panel now having its own chain and link fixed to it, each panel and chain able to take an equal share loading of pressure, each differing size of assembled form having its own correct length of chain so not to deform it, each form having a chain long enough to be lifted at the correct degree of angle in relationship to the diameter of the form (typically 60°), each panel and chain able to be officially certified and tagged, the possibility of the anchor pins being removed and upgraded for maintenance or replacement. Reduction or elimination of chains and hooks being lost on site, assured positive capture of the chains on the main lifting hook, better stacking and nesting ability.

Another improvement to the form panels, according to an embodiment of the invention, is in the locking of adjacent panels together.

Figures 11-13 illustrate a new way of safely and securely locking adjacent form panels together without requiring extensive use of nuts, bolts, locking pins and wedges.

In Figure 11, there is illustrated a form panel having panel members 40,41 which are similar to that described previously and again having longitudinal side ribs 42,43 which abut together.

In this embodiment, a steel locking channel 44 (best illustrated in plan view Figure 13) having a substantially U-shaped configuration, and not

being beveled at its free edges, is dimensioned to extend over ribs 42,43 and to lock the ribs together as the channel is pushed over the ribs. Once in place, a pair of securing pins 45,46 are tapped in place to lock the channel to the ribs 42,43 of each form panel 40,41.

To remove the locking channel, the pins are tapped out and the locking channel can be hammered downwardly and, if necessary, can be provided with a striking plate 47 to assist.

The bottom edge 48 of locking channel 44 is beveled. As well, ramped surfaces 49 are welded on each rib 42,43 and at the bottom of each rib.

To remove the locking channel, the securing pins 45,46 are tapped out and the channel can be hammered downwardly which will cause the beveled bottom edge 48 to ride up over the ramped faces 49 causing the bottom of the channel to become removed from ribs 42,43. Continued hammering can then progressively remove the channel or the channel can be pulled away from the remainder of the ribs.

To provide a good locking action, the free edge of each rib 42, 43 is beveled 50 (see Figure 13). The beveling allows the locking channel to tightly fit over the ribs as it is hammered onto the ribs. If the locking channel was beveled (see dotted outline 51), it would result in insufficient clamping at the most important clamping point which is as close as possible to the connection between ribs 42,43 and their respective form panel 40,41 (this part must be clamped tightly shut to prevent concrete from entering into any formed gap). Should locking channel 44 be beveled 51 (which it is not), it becomes apparent that the clamping action does not exist at this critical area.

On the other hand, by having the ribs 42,43 beveled at 50, and the locking channel not being beveled, it is found that the ribs can be clamped together very tightly at the position where the ribs contact the form panel.

Figures 14,15 and 16 illustrate a variation to the locking channel.

With manhole forms consisting of an outer form and an inner form in between which concrete is poured, once the concrete has set, the

outer form is quite easy to remove as the adjacent panels can be disconnected and simply removed. However, the inner form presents difficulties as the panels cannot be simply decoupled from each other as the surrounding set concrete manhole prevents this. Attempting to pull the inner manhole form out of the set concrete manhole is not always desirable.

Because of this, it is known to provide a key panel which is a narrower panel which can be initially knocked out to provide the desirable space to allow the rest of the inner form to be decoupled. Figure 15 illustrates a prior art arrangement consisting of four inner form panels 61 and a smaller key panel 60. When the poured concrete has set, key panel 60 can be tapped or hammered out to provide a gap which will then allow the remaining form panel 61 to be decoupled.

The key panel however introduces a separate panel into the form which comes with its inherent additional problem of fixing with nuts and bolts, pins and wedges etc. and locking the key panels in place. The key panel can also be deformed if the inner manhole form is"slipped"and not properly supported by the lifting chains.

Figure 14 illustrates a form of the invention which does away with the need for a separate key panel 60. In this arrangement, there is provided a locking channel 62 similar to that described above, but where the locking channel is provided with a key 63 which has a height greater than the height of the remainder of locking channel 62 such that the end of the key 63 can extend between adjacent form panels 61. The form panels are provided with the usual strengthening ribs 64 and the spacing between the key 63 and the side walls 65 of channel 62 is such to accept and tightly clamp together ribs 64. A locking pin 66 can then be inserted in the usual manner to hold the key locking channel to the forms. Figure 16 shows a side view of the locking channel of Figure 14.

Key 63 is automatically located into correct position as the key locking channel 62 is located and fixed in place about ribs 64. As with the previously described locking channel, a striking plate may be provided as well as a lower tapered portion to facilitate removal of the channel.

In use, after concrete is cured and set, channel 62 can be removed which results in a small gap forming between panels 61, the gap being sufficient to now allow the panels to be decoupled from each other in a straightforward manner. If the form is to be"slipped"while the concrete is still green, the channel 62 can simply remain in place.

It should be appreciated that various other changes and modifications can be made to the embodiments described without departing from the spirit and scope of the invention.