AU2013204710A1 - Panel Lifting Device - Google Patents

Abstract

Abstract A lifting device for releasably attaching to a panel comprising a body having two opposing substantially planar surfaces arranged parallel and spaced apart from one another. At least one of the planar surfaces has one or more apertures therein, with each aperture being adapted for a fixture to be inserted there through and to fixedly secure to the panel. A suspension arm is also provided in connection with the body, having a first end proximally disposed to the body and being rotatably connected to a first planar surface of the body around an axis arranged substantially perpendicular to the planar surface. The suspension arm further has a second end distally disposed to the body and being releasably connected to at least one retractable element. Each retractable element is connected to a lifting apparatus located in an elevated position, and is configured to retract the element; I'Z Figure 1

Description

1 PANEL LIFTING DEVICE TECHNICAL FIELD The present invention relates to a device configured to be releasably 5 attached to a panel and a lifting apparatus, allowing the panel to be lifted by the apparatus. In particular, the invention relates to a bracket or a clamp connected to a lifting apparatus and used to retain and lift sizeable panels of building materials between positions in a construction site. 10 BACKGROUND TO THE INVENTION Devices for releasably engaging articles, such as panels are widely known. A common device is a clamp, which has been used in many industries for a significant length of time. Clamps are employed either as a temporary or permanent fastening to secure one item to another. Whilst clamps may vary 15 in features or form, the majority of clamps function on the principle of having at least one pair of jaws that are urged towards each other to grip one or more items between the jaws by a compressive force. This may be achieved by mechanical means, for example by using a screw thread to decrease the distance between jaws, or hydraulically, where rams or pistons 20 are employed to force the jaws towards each other. Many variants of clamp design exist, with commonplace examples including C-clamps, G-clamps, flooring clamps, bar clamps and spring clamps. Clamps are often developed for specific purposes, such as wheel clamps for car wheels, having a number of purpose related requirements. Similarly, 25 clamps are often developed for specific purposes in the construction industry, in particular, for instances where it is required that items are firmly gripped for connection to and lifting by automated lifting apparatus such as cranes. Such instances may include occasions where building 2 materials, such as large and heavy sheets or panels of material, are required to be lifted between the storeys of a building by lifting apparatus. The specifications for a clamp that is intended to grip and lift sizeable concrete panels between locations on a construction site must take a 5 number of factors into account. For example, concrete is an inherently heavy and brittle material, requiring the clamp to have substantial gripping capacity yet exert a limited gripping force in order to avoid being over tightened and cracking the panels. The location of panels before being lifted and the desired location after lifting may also be limited in terms of space 10 available to manoeuvre clamp and panel throughout the lifting process, the arrangement of the panels before lifting, e.g. being stacked in an orientation that is conventional to a certain site, and the desired arrangement of the panel after lifting, e.g. in an alternative orientation to that before being lifting to allow the panel to be installed on the 15 construction site. A number of solutions have been developed in the past to attempt to resolve some of the issues associated with lifting concrete panels. For example, United States patent no. 4398761, entitled "Device for lifting and tilting concrete panels" in the name of Hanson et al, discloses a clamp used 20 for hoisting and rotating concrete panels. Whilst the invention disclosed is adequate for its purpose, it is specified for a certain type of concrete panel, having specific dimensions and features such as grooves which mate with the clamp jaws, and is not suitable for gripping and lifting other types of concrete panels. The clamp also has a complex structure and significant 25 number of components, such as multiple cables to hoist and rotate the clamp and panel and hydraulic rams to force the jaws onto the surfaces of the panel; both of which would prove unnecessarily complicated and expensive for a number of applications. The disclosed clamp is specified to lift a panel from a single orientation, being the large face of the panel 30 parallel with the ground surface, and does not allow panels to be lifted from other positions. Furthermore, the clamp grips more than one side surface of 3 a panel to lift the panel, limiting the options of affixing the panel to a construction site along its side surfaces when being lifted. Accordingly, it would be useful to provide a solution that avoids or substantially alleviates any of the disadvantages present in the prior art, or 5 which provides an alternative to the prior art approaches. SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a lifting device for releasably attaching to a panel comprising: 10 a body having two opposing substantially planar surfaces arranged parallel and spaced apart from one another, at least one of the planar surfaces having one or more apertures therein, each aperture adapted for a fixture to be inserted there through and to fixedly secure to the panel; a suspension arm in connection with the body, the suspension arm having a 15 first end proximally disposed to the body and being rotatably connected to a first planar surface of the body around an axis arranged substantially perpendicular to the planar surface, the suspension arm further having a second end distally disposed to the body and being releasably connected to at least one retractable element; and 20 wherein each retractable element is connected to a lifting apparatus located in an elevated position, configured to retract the element. Preferably, the suspension arm is attached to a single retractable element. Preferably, the device is configured to be attached to a panel having front, rear and side surfaces, and wherein the distance between the opposed 25 planar surfaces is substantially the same as the distance between the front and rear surfaces of the panel.

4 The lifting device preferably has a receiving surface arranged substantially perpendicular to and extending between the opposed planar surfaces. A lifting device in accordance with claim 4, wherein when the receiving surface is in contact with a side surface of a panel that is larger or equal to 5 all other side surfaces, the axis of rotation of the suspension arm is positioned on the longitudinal line of symmetry of the front or rear surface of the panel. Preferably, a gripping material is secured to each planar surface, the gripping material having a high coefficient of friction. In one embodiment, 10 each planar surface preferably includes a textured region having a high coefficient of friction. Preferably, the suspension arm has at least one projection extending at an angle to the suspension arm and adapted to connect to a handle. Preferably, the projection is cylindrical and the handle has a complimentary 15 hollow tubular portion. Preferably, the suspension arm has an intermediary part rotatably connecting the suspension arm to the retractable element, the intermediary part being adapted to connect to a handle. Preferably, the intermediary part rotates around an axis arranged 20 substantially perpendicular to the axis around which the suspension arm rotates. Preferably, the retractable element is selected from one or more of the following: a chain, a rope, a cable, a cord.

5 BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 5 Figure 1 is a perspective view of a preferred embodiment of the invention attached to a side surface of a panel. Figure 2 is a perspective view of a preferred embodiment of the invention. Figure 3A is a perspective view of an alternative preferred embodiment of 10 the invention. Figure 3B is a side view of the embodiment shown in the previous Figure. Figure 4 is a perspective view of an alternative embodiment of the invention attached to a side surface of a panel. Figure 5 is a front view of an alternative embodiment of the invention 15 attached to a side surface of a panel. Figure 6 is a perspective view of the invention as shown in Figure 4. Figure 7 is a front view of the invention as described in the previous two Figures being hoisted. Figure 8 is a side view of the invention as described in the previous three 20 Figures being hoisted. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present invention relates to a lifting device adapted to be releasably attached to panels of material and be elevated by a lifting apparatus, such 25 as a winch, to enable the transport of panels between locations. In 6 particular, the invention is directed towards lifting rectangular concrete panels used in construction projects, having two large planar surfaces and four side surfaces, such as autoclaved aerated concrete (AAC) panels (such as those available under the "HEBEL" trade mark). The invention enables 5 the lifting of such panels between positions on a construction site, with one of these positions being at an elevated location. The invention discloses a lifting device that is simple in construction, aiming to provide a lightweight, durable and less expensive alternative than conventional lifting equipment, requiring only a single hoisting element to 10 provide lifting, such as a cable or chain. The device is able to be attached quickly to panels by unskilled labourers and configured to consistently lift panels stored at ground level on a long side surface, as is convention, to an elevated position, rotating the panels from a storage orientation to an instalment orientation, having the long side surface arranged vertically, in a 15 controlled and efficient manner The invention is particularly useful for lifting panels from a storage position, where the panels are typically stacked in an array on a long side surface and simultaneously lifting and rotating panels into a preferred orientation for installation or storage in a construction site. The preferred embodiment 20 is configured to be attached to or clamp a single side surface of a panel and, using a suspension arm connected to the device and a lifting apparatus, rotate the panel about its longitudinal centre of gravity axis during a lifting operation, on a plane parallel to the gripped or secured surfaces of the panel. This action is optimised so that when a panel 25 attached to the device of the present invention is elevated by the lifting apparatus, the opposite side surface to the side surface to which the device is attached may be affixed in its preferred installation location. This installation location will typically be adjacent to a previously installed panel. By lifting and rotating a panel in such a manner, the invention provides a 30 controlled method to manipulate a panel from a storage position to an installation position, allowing the panel to be immediately attached to a construction site on up to three side surfaces of the panel. The suspension 7 arm arrangement also avoids undesirable rocking of the panel during lifting, which can prove inconvenient and dangerous. To further improve the controllability of the movement of the panel once gripped and lifted, the invention also provides an adjustment handle, which 5 is able to be attached to the suspension arm and allows a user to accurately manually adjust the vertical or horizontal position of the panel, in many instances by a very small amount, and without needing to activate the lifting apparatus. This is particularly useful in situations such as where a panel has a glue joint with an adjacent panel or other construction element 10 and where the adhesion of the glue joint is improved by frictional movement, which can be provided by the panel being installed being rubbed against an adjacent panel to ensure a successful bond joint. It can also provide micro adjustments of the position of the panel to align fixing apertures or the like. 15 In Figure 1, a perspective view of a one aspect of the invention is shown attached to the side surface 2 of a panel 1, wherein the lifting device is configured as a clamp, the clamp having the two jaws 3, 4 gripping a front and rear surface 5, 6 of a panel. The jaws are pivotally connected by an axle 7 such that the jaws rotate around a first axis in relation to each other. 20 Whilst the preferred embodiment has two opposable jaws for simplicity of construction, it is within the scope of invention that other multiples of opposing jaws may be provided according to the requirements of the clamp. The jaws 5, 6 are also connected by a ratchet mechanism 8 configured to urge the jaws towards one another. The ratchet mechanism also has a 25 fitting 9 for a tool, the fitting adapted to connect to a handle or other similar item to enable actuation of the mechanism. Alternatively, the ratchet may also have a tool or handle permanently attached to the clamp to allow actuation of the mechanism. The ratchet mechanism may be tightened or slackened by rotating the fitting, to either urge the jaws towards each other 30 and clamp an item or release the jaws to allow each jaw to rotate away from each other. It is preferable that the ratchet includes a torque-limited mechanism which may be set to a predefined torque value, according to the 8 properties of the panel, and that once the torque exerted on the ratchet exceeds that value, the ratchet mechanism disengages, preventing the clamp from being excessively tightened and potentially cracking the panel. The clamp has at least two panel gripping portions, one of which can be 5 seen 10 in Figure 1. In the preferred embodiment each panel gripping portion 10 is a substantially planer pad, pivotally connected to a jaw 3 such that the angle of the panel grip in relation to the jaw may adjust whilst the clamp is being tightened and the jaw is forced towards the panel. The device further includes a suspension arm 11 is pivotally connected to a 10 jaw 3 at a proximal end around an axis arranged substantially perpendicular to the jaw. The suspension arm is freely rotatable around the axis in a single plane such that when the clamp grips the surfaces of a panel, the arm 11 rotates on a plane parallel to the gripped surfaces 5, 6. The distal end of the suspension arm is adapted to connect to a retractable element, 15 such as a chain, cable, cord or rope which in turn is connected to a lifting apparatus, such as a winch or hoist, located in an elevated position. In the preferred embodiment shown this is by an aperture 12 through the body of the arm 11 which may receive a fitting or hook however other conventional connection means will be appreciated to be within the scope of the 20 invention. The suspension arm also comprises one or more protrusions 13 extending at an angle of less than 90 degrees from the main body of the arm adapted to fit inside a recess in a handle 14. When a clamp gripping a panel is lifted by a lifting apparatus and suspended by the suspension arm, the projection 13 and handle 14 allow a user to rotate the suspension arm 25 manually, causing the panel to move vertically and/or horizontally. This allows a user to perform delicate adjustments to the position of the panel to assist installation or accurately place the panel, without activating the lifting apparatus. In Figure 2 a perspective view of the invention as shown in the previous 30 figure is shown in isolation. The rear jaw 4 can also be seen to have a panel gripping region 14, similar to the panel gripping surface 10 pivotally connected to the front jaw 3. However, the grip 14 is preferably rigidly fixed 9 to the body of the jaw 4 and unable to rotate. Both gripping surfaces 10, 15 may have additional features to increase the friction between the clamp and the panel being gripped, such as a second material bonded to the surface of each having a high co-efficient of friction, such as an elastomer or rubber 5 compound. Each gripping surface may alternatively be etched or have a type of texture which also increases the co-efficient of friction of each surface. The front jaw 3 of the device can be seen to have an 'S' shaped profile, having a first section, or support section 31, joined to the axle 7, a second 10 section 32 arranged substantially perpendicular to the first and a third section 33 arranged substantially parallel to the first section. This arrangement, creates a receiving surface 34 on an underside of the second section 32 configured substantially perpendicular to the panel gripping surface 10. The receiving surface supports the device when the device is 15 rested on a side surface of a panel, prior to securing the device to the panel. This arrangement is optimised to locate the device in a correct orientation and position in relation to a panel, as such rectangular panels are typically stored on a construction site on the longer of the side surfaces on a floor and stacked in an array. Whilst the jaw 3 is shown in the 20 preferred embodiment, those skilled in the art will recognise that other arrangements having a receiving surface configured to be substantially perpendicular to the panel gripping surface of the jaw is within the scope of the invention. The third section 33 of the jaw 3 is dimensioned according to the panel the 25 clamp is intended to lift, being of a substantial enough length to position the axis around which the suspension arm 11 rotates on the longitudinal line of symmetry of the panel. This arrangement locates the point which the panel is lifted and rotated around is along the line of the centre of gravity of the panel, ensuring that regardless of the attachment point of the clamp to a 30 side surface, the panel will be lifted in line with its centre of gravity, automatically rotated to the preferred installation orientation. The optimised position of the lifting point also minimises undesirable swinging of the panel 10 during lifting and provides a smooth, controlled simultaneous lifting and rotating motion of the panel. This arrangement is only applicable to lifting panels of a square or rectangular configuration and when the receiving surface 34 is placed in contact with a side surface that is equal or longer 5 than all other side surfaces. In Figure 3A an alternative preferred embodiment of the invention is shown, configured as a bracket 50, the bracket having a body comprising at least two substantially parallel and planar surfaces 51, 52 and a receiving surface 53 extending between the two planar surfaces. The bracket also has a 10 suspension arm 54 rotatably connected to the bracket around an axis 55 arranged substantially perpendicular to one planar surface. The bracket functions in an identical manner as previously described, providing a device connected to a lifting apparatus and configured to be secured to a side surface of a panel, allowing the panel to be lifted by the lifting apparatus 15 and simultaneously rotated from a storage orientation to an installation orientation. In this embodiment, the bracket 50 is releasably attached to a panel by securing one or more fixtures through one or more fixture apertures 56 into the panel. This alternative arrangement provides a secure, mechanical 20 engagement between the bracket and the panel, which in some instances, such as where a cost of clamp is prohibitive or it would prove quicker or more convenient to attach the lifting device in this manner, is advantageous. The planar surfaces are spaced apart a specific distance according to the panel the bracket is intended to attach to and lift, the 25 distance being slightly larger than the distance between the front and rear surfaces fo the panel, for example, this distance plus a tolerance of 5mm. This approach also offers a further advantage of providing a user located at the desired installation position with a number of fixtures to fix the panel in position with, once the fixtures securing the bracket to the panel are 30 removed. In the embodiment shown in Figure 3A, it is preferable that the bracket is formed from bent sheet metal in order to simplify the construction of the 11 bracket and reduce costs. This approach allows a wide range of brackets to be produced having different dimensions for different panels, easily and at low cost. However, in other instances, the bracket may be a cast or injection moulded item. 5 In Figure 3B a side view of the bracket 50 is shown, clearly illustrating the arrangement of the planar surfaces 51, 52 and the receiving surface 53. In the preferred embodiment, one planar surface 51 is substantially larger than the other, providing a single surface through which fixtures are secured into a panel, in order to reduce material required to manufacture 10 the panel and reduce the number of fixtures required to releasably attach the bracket to a panel. However, in other preferred embodiments the planar surfaces are substantially identical, providing an array of fixture apertures to allow both a front and rear surface of a panel to be secured to the bracket. In Figure 3B, two adjustment handle protrusions 57 can be seen 15 extending from the suspensions arm 54 in opposing direction, allowing an adjustment handle having a complimentary socket to be attached and the position of a panel lifted using the bracket to be adjusted. In Figure 4 an alternative embodiment of the invention is shown attached to a side surface 2 of a panel. The Figure illustrates an alternative suspension 20 arm arrangement 16, having an intermediary part 17 connecting the suspension arm to the lifting apparatus, the intermediary part being rotatably connected to the arm around an axis, preferably being substantially perpendicular to the axis that the arm rotates around in relation to the jaw 3. A handle 14 may also be connected to the part 17 to 25 enable micro adjustment of the position of the panel when suspended below a lifting apparatus. Regarding the operation of the clamp, Figure 5 shows the first stage of operation being a front view of an alternative embodiment of the invention resting on a side surface 2 of a panel, prior to the jaws being urged towards 30 one another and gripping the panel. The clamp is placed in contact with the side surface of the panel 2 by placing the receiving surface of the front jaw 3 on the side surface. The clamp is then secured to the panel by actuating 12 the ratchet mechanism 8 by rotating the handle 19 clockwise and anti clockwise, forcing the jaws towards the front 5 and rear surfaces of the panel. The panel gripping surfaces 10 contact the front and rear surfaces and due to the force of the ratchet mechanism, compress the opposite faces 5 of the panel, providing the necessary friction for the jaws to grip the panel when the clamp is lifted. A further alternative suspension arm 18 is shown without any features to allow manual adjustment of the panel when lifted. Figure 6 illustrates the second stage of operation wherein a retractable element, being a chain 20, which is attached to a lifting apparatus located in 10 an elevated position, is connected to the suspension arm 18 following the clamp being secured to the panel. In Figure 7 the invention is shown in the third stage of operation, in which the chain 20 is drawn towards the lifting apparatus, lifting the suspension arm 18 vertically upwards and in turn lifting an end of the panel 1, 15 dependent on the position of the clamp in relation to the axis of symmetry of the gripped surfaces that is transverse to the longitudinal axis. It can be seen that due to the length of the third section 33 of the jaw 3 being dimensioned according to the panel the clamp is intended to lift, the axis of rotation of the suspension arm 18 in relation to the clamp is substantially 20 located on the longitudinal line of symmetry of the panel. This arrangement ensures a smooth and controlled transition between the panels initial location on a side surface on a floor or the like, to an upright hoisted orientation, being lifted directly along its centre of gravity axis to minimise rocking of the panel and orientating the panel correctly for installation onto 25 a construction site. Furthermore, as the clamp is gripping a single side surface only, the opposite side surface is free to be prepared or aligned for fixing to the construction site. In Figure 8 the panel 1 is lifted above ground level and suspended by the suspension arm 18 below a lifting apparatus. Once in this position the panel 30 may be further transported, vertically or horizontally by the lifting apparatus to its desired location for storage or fixing. Due to the minimal encroachment on side surfaces, the panel may also be directly affixed in a 13 vertical orientation to an internal or external wall of a building whilst being connected to the clamp and lifting apparatus. In this specification, unless the context clearly indicates otherwise, the term "comprising" has the non-exclusive meaning of the word, in the sense of 5 "including at least" rather than the exclusive meaning in the sense of "consisting only of". The same applies with corresponding grammatical changes to other forms of the word such as "comprise", "comprises" and so on. It will be apparent that obvious variations or modifications may be made 10 which are in accordance with the spirit of the invention and which are intended to be part of the invention. Although the invention is described above with reference to specific embodiments, it will be appreciated by those skilled in the art that it is not limited to those embodiments and may be embodied in other forms. 15 INDUSTRIAL APPLICABILITY The invention can be utilised in the construction industry.

Claims (12)

1. A lifting device for releasably attaching to a panel comprising: a body having two opposing substantially planar surfaces arranged parallel and spaced apart from one another, at least one of the planar surfaces having one or more apertures therein, each aperture adapted for a fixture to be inserted there through and to fixedly secure to the panel; a suspension arm in connection with the body, the suspension arm having a first end proximally disposed to the body and being rotatably connected to a first planar surface of the body around an axis arranged substantially perpendicular to the planar surface, the suspension arm further having a second end distally disposed to the body and being releasably connected to at least one retractable element; and wherein each retractable element is connected to a lifting apparatus located in an elevated position, configured to retract the element.

2. A lifting device in accordance with claim 1, wherein the suspension arm is attached to a single retractable element.

3. A lifting device in accordance with claim 1, wherein the device is configured to be attached to a panel having front, rear and side surfaces, and wherein the distance between the opposed planar surfaces is substantially the same as the distance between the front and rear surfaces of the panel.

4. A lifting device in accordance with claim 3, having a receiving surface arranged substantially perpendicular to and extending between the opposed planar surfaces.

5. A lifting device in accordance with claim 4, wherein when the receiving surface is in contact with a side surface of a panel that is larger or 15 equal to all other side surfaces, the axis of rotation of the suspension arm is positioned on the longitudinal line of symmetry of the front or rear surface of the panel.

6. A lifting device in accordance with claim 1 wherein a gripping material is secured to each planar surface, the gripping material having a high coefficient of friction.

7. A lifting device in accordance with claim 1, wherein each planar surface includes a textured region having a high coefficient of friction.

8. A lifting device in accordance with claim 1, wherein the suspension arm has at least one projection extending at an angle to the suspension arm and adapted to connect to a handle.

9. A lifting device in accordance with claim 10, wherein the projection is cylindrical and the handle has a complimentary hollow tubular portion.

10. A lifting device in accordance with claim 1, wherein the suspension arm has an intermediary part rotatably connecting the suspension arm to the retractable element, the intermediary part being adapted to connect to a handle.

11. A lifting device in accordance with claim 10, wherein the intermediary part rotates around an axis arranged substantially perpendicular to the axis around which the suspension arm rotates.

12. A lifting device in accordance with claim 1, wherein the retractable element is selected from one or more of the following: a chain, a rope, a cable, a cord.