Inter-lockable structural panel sets
The invention relates to inter-lockable structural panel sets consisting of panels and joining parts.
Demountable structural panels are known and used in the construction of lightweight structures such as aircraft, space structures, and advanced permanent or temporary buildings such as geodesic domes. The structural integrity of this type of structural form is dependent upon bolted or pinned connections at nodal positions of a skeletal structure.
US 4,309,852 describes a geodesic structural configuration where connection between neighbouring panels is dependent upon peripheral nodal connections. The method of connection employed has a relatively low load transmission capacity and leaves a gap between adjacent panels, which necessitate an additional external cover on the framework after the structure has been erected. The method of connection is complex to manufacture and seal and is dependent upon assembly and adjustment of a multitude of component parts within all of the individual subassemblies.
GB 2 115452 A describes a structural panel system, which is dependent upon extruded H-sections for joining protrusions of adjacent panels. The joints utilise an extruded connection, which can be inserted along a straight edge or made of two separate parts, which imposes limitations on the strength of construction method and makes the assembly slow and cumbersome, while requiring a separate means of weatherproofing. Furthermore, the structure is not designed to allow removal of individual panels once the structure has been assembled.
As a consequence of this complex design approach, high stress concentrations may occur at nodal connection points, which in turn lead to penalties such as a multitude of joining parts, complex production and assembly, high dead-weight and low structural and thermal efficiencies. It is an aim of the present invention to provide a structural means of connection, which can be used for erecting permanent or temporary structures of a type that is not made in a conventional manner and that will overcome the limitations mentioned above.
An alternative solution for the construction of lightweight structures, which are composed of modular, demountable and interlocking structural panels, is the main aim of this invention.
Accordingly, this invention provides for inter-lockable structural panel sets, consisting of at least two panels and at least two joining edge assemblies, characterized in that at least one edge of a first panel has two internal and vertically opposed tongues which butt against opposite tongues of an adjoining panel edge in the assembled position, wherein the two sets of tongues are joined internally by means of a set of retractable joining clamps, which are wedged upon the two sets of opposing tongues of both panel edges, and which may also have an internal seal at their joining faces, thereby affecting a structural and weather-tight sealed joint.
In one preferred embodiment of the opposing tongue and clamp arrangement, such tongues and clamps may be horizontally staggered for improving structural and mechanical properties of the section by way of increasing the cross sectional area between the tongues.
In another preferred embodiment of the opposing tongue and clamp arrangement, the clamp may be spring loaded and seated in a shuttle that transfers the clamps across from one joining edge assembly to the other.
The edge assemblies may be bonded or mechanically connected to a sandwich panel, for ease of panel manufacture. By such means, a quick and accurate method for production, assembly and sealing of structural panel sets, with a minimum of separate joining parts, can be attained. In particular, the tongue and clamp system provides accurate panel positioning, thereby eliminating the need for external means of alignment of major subassemblies. In particular, such an arrangement can accommodate different load capacities by way of varying the length of the joint to suit the anticipated applied load. Thus, load capacity may be altered at any time, by simply altering the clamps length. This is especially beneficial with multiple panel sets where several panels may be connected.
Such application may be found in the construction of a geodesic dome where arrays of hexagonal panels must join at highly precise angles. Several embodiments of the invention will be described solely by way of example and with reference to the accompanying drawings in which:
Fig. 1 shows a cross section of two adjoining panel edges of an inter- lockable structural panel set with joining clamps in the retracted position;
Fig. 2 shows a cross section of an edge of an inter-lockable structural panel set with joining clamps in the latched position;
Fig. 3 shows a cross section of an edge of an inter-lockable structural panel set with joining clamps in the locked position;
Fig. 4 shows a geodesic dome consisting of flat panel sets according to the invention;
Fig. 5 shows a cross section of an edge of an inter-lockable structural panel set in the retracted position where the shuttle also acts as a clamp carrier; Fig. 6 shows a cross section of an edge of an inter-lockable structural panel set in the locked position where the shuttle also acts as a clamp carrier.
Fig. 7 shows a cross section of an edge with multiple slots for several panel connections.
Fig. 1 shows a cross sectional view of two adjacent panel edges 1 and 2 with clamps 4, in the retracted position. In this configuration, a panel can be detached and withdrawn from surrounding panels since no protruding clamping parts 4 inhibit a vertical movement.
The edge extrusions 1 and 2 have an expanding and curved slot 3, for accommodating fibreglass sheets, 13, of a composite panel with foam core 14. The sheets are adhesively bonded and locked in the expanding slots 3, which prevent high stress concentration by virtue of the curvature at the edge of the slot. The faces of the slots are serrated for improved bonding strength.
Tongues, 9 and 9a, provide the structural means of connection between adjoining panel edges 1 and 2, with clamping parts 4, which rotate about hinges 8. A seal 5 is positioned in an inclined seal housing of the edge extrusion 1 , for providing a means of sealing the joint.
Shuttle 7, transmits axial movement to the spring-loaded plungers 6, which result in a rotational movement of the clamps 4. The curved heads of the plungers 6a, engage in the curved surfaces of clamp tails 4b, which are spring loaded for maintaining intermediate clamp positions by springs 12.
The horizontal movement of the shuttle 7 is achieved by rack 11 which is driven by spur gear 15 and vertical bolt headed shaft 10, thereby facilitating movement in both directions. In the retracted position, the clamping parts 4 are spring-loaded and will geometrically lock the clamping parts in the retracted position. Thus panel replacement can take place.
All tongues 9 and 9a have curved tips and wedged engagement surfaces. The curved tips prevent fouling during clamp latching while the wedged surfaces draw the neighbouring panels together, thereby aligning the tongues and making a structural connection.
The tongues 9 and 9a and clamps 4 have elastic coating for improving the weather-tightness of the joint.
The external surface of the seal housing 5 may be raised for the purpose of separating the boundary layer flow in this region. By such means the lift and drag forces on the external surfaces of a structure may be considerably reduced. This is especially important for buildings of rounded form, which are situated in areas prone to high winds.
Fig. 2 shows a cross sectional view of two panel edges in the latched position.
The clamping parts 4, are engaged with tongues 9 and 9a and the shuttle 7 maintains a geometric lock of the clamping parts 4, via the plungers 6, due to the spring forces 12. The curvature at the contact surfaces of clamp parts 4 and plunger surfaces 6b, also allows automatic latching under spring load 12, without the need to operate the rack 11. Thus, quick latching and alignment are achieved.
Fig. 3 shows two panel edges in the locked position. ln this position the rack 11 , is driven to the foremost position. A geometric and spring-loaded lock is maintained due to the additional curvature under the clamps 4. In this position, with the shuttle 7, plungers 6 and clamps 4 making contact, no movement of the clamps 4 is possible. Thus, full resistance to applied loads across the joint is achieved.
Fig. 4 shows a demountable geodesic dome as an example for the use of the structural panel sets according to the invention.
The use of demountable panels as described above, leads to several advantages. The method of joining by tongues and clamping parts allows the imposed loads on the dome to be distributed along most of the length of each panel edge, thereby eliminating load concentrations as found in current dome construction which depend upon a skeletal frame with nodal connections.
Fig. 5 shows a cross sectional view of a linear clamping system which consists of a central shuttle (16) with spring loaded plunger clamps
18, in the retracted position. A central shaft (19) provides horizontal movement. The tongues (17 and 17a) are wedge shaped with the wider section at the inner extremity.
Fig. 6 shows a cross sectional view of a linear clamping system in the clamped position. The plunger clamps (18) are wedged against the wedge shaped tongues (17 and 17a) and within the shuttle faces (16a and 16b), thus forming a structural lock, which resists vertical shear loads.
Fig. 7 shows a section of an extruded edge part with slots (20) for multiple panel connections.