AU2004200915A1 - A Beam and a Method of Forming Same - Google Patents

Description

S&F Ref: 647814

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Jennifer Marie Charlwood 9 Wollemi Place Dural New South Wales 2158 Australia Matthew Charlwood Spruson Ferguson St Martins Tower Level 31 Market Street Sydney NSW 2000 (CCN 3710000177) A Beam and a Method of Forming Same ASSOCIATED PROVISIONAL APPLICATION DETAILS [33] Country [31] Applic. No(s) AU 2003901140 AU 2003901609 [32] Application Date 13 Mar 2003 03 Apr 2003 The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5815c 1 A BEAM AND A METHOD OF FORMING SAME Technical Field The present invention relates to a beam and a method of forming same.

The invention has been primarily developed in relation to a light weight beam s suitable for home extensions and will be described hereinafter with reference to this application. However, it will be appreciated that the beam is not limited to this particular use and is also suitable for new building construction, renovations and scaffolding.

Background of the Invention A known light weight beam is marketed by BHP Company as FIRMLOK (Trade Mark). This beam is produced by crimping together two generally U-shaped, roll-formed, steel channels to form a closed rectangular beam.

The main disadvantage of this beam is it is produced in two stages, namely rollforming the two channels and then assembling and crimping them together. This is a complicated and relatively expensive process. Another disadvantage of this beam is that fasteners inserted between the opposing sides of the beam can cause the sides to bow together, which is unsightly.

Object of the Invention It is an object of the present invention to substantially overcome or at least ameliorate one or more of the above noted prior art disadvantages.

Summary of the Invention Accordingly, in a first aspect, the present invention provides a beam including: a metal outer skin formed into a closed shape; and an inner core formed from expanded foam material, wherein the outer surfaces of the inner core are bonded to the inner surfaces of the outer skin.

In one form, the outer skin closed shape is formed by folding, with opposed longitudinal edges of the outer skin most preferably being joined by a folded seam. In another form, the outer skin closed shape is formed by extruding.

In one embodiment the outer skin has a rectangular cross-section. In another embodiment, the outer skin has a round cross-section.

[R:\LIBD]03398.doc:caa In a second aspect, the present invention provides a method of forming a beam, the method including: forming a metal outer skin of a closed shape; and introducing an expandable foam material into the interior of the outer skin to form an inner core, whereby the outer surfaces of the inner core expand and bond to the inner surfaces of the outer skin.

Step is preferably performed by roll forming.

In one embodiment, step is performed by introducing the expandable foam material into the interior of the outer skin after it is fully closed. Step preferably includes: tilting the closed outer skin until its longitudinal axis is at an angle acute to vertical or is vertical; plugging its lower end; and injecting the foam material into its interior, most preferably at spaced apart locations.

In another embodiment, step is performed by introducing the expandable foam material into the interior of the outer skin prior to it being fully closed. Step (2) preferably includes continuously injecting the foam material into the interior of the outer skin in advance of the closing fold.

Alternatively, step is performed by extruding.

In a further embodiment, step is performed by introducing the expandable foam material into the interior of the outer skin after it is formed. Step preferably includes tilting the closed outer skin until its longitudinal axis is at an angle acute to vertical or is vertical; plugging its lower end; and progressively injecting the foam material into the interior beginning substantially adjacent the lower end and ending substantially adjacent its upper end.

Brief Description of the Drawings A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 a is a cross sectional end view of first embodiment of a beam according to the invention; [R:\LIBD]03398.doc:caa Fig. lb is an enlarged detailed view of a closing seam used in the beam shown in Fig. la; Fig. 2 is a cross sectional side view of the beam shown in Fig. la during manufacture; Fig. 3a is a cross sectional side view of a second embodiment of a beam according to the invention during manufacture; and Fig. 3b is a cross sectional end view of the completed beam shown in Fig. 3a.

Detailed Description of the Preferred Embodiments Referring firstly to Figs. la and ib, there is shown a beam 10 according to a first embodiment of the present invention. The beam 10 is formed from a 0.55mm thick sheet metal outer skin 12 which is folded into a rectangular cross-sectional closed shape having dimensions of 150mm by 55mm. The skin 12 is preferably formed from COLORBOND (Trade Mark) material, as marketed by BHP Company, which is available in numerous colours.

The beam 10 has a longitudinal seam 14 in one of its shorter sides. Both the forming into the rectangular shape and the closing seam 14 are produced using a rollformer configured in a manner similar to that used in making rainwater down pipes, except the seam 14 is placed in one of the shorter sides, not one of the longer. Such rollforming is well understood by persons skilled in the art.

The beam 10 also includes an inner core 16 formed from expanded foam material.

The foam material is preferably polyisocyanurate (PIR) foam which is similar to a standard polyurethane foam but which exhibits enhanced fire performance. The foam material is injected into the interior of the beam 10 in liquid form and expands until its outer surfaces contact, and bond with, the inner surfaces of the outer skin 12.

The adhesive bond formed between the outer surfaces of the inner core 16 and the inner surfaces of the outer skin 12 results in the beam 10 exhibiting surprisingly high levels of strength relative to its weight.

The beam 10 was tested against an equivalent size FIRMLOK F150-15 beam. In the test, a 4,800mm section of each beam was supported by its ends. An increasing load was then applied to the central 200mm of each beam. The beam 10 exhibited slightly higher levels of deflection than the FIRMLOK beam. For example, under a load of 150kg, the beam 10 flexed approximately 19mm as compared to the 13mm flexure of the FIRMLOK beam. However, whilst the beam 10 deflected slightly more it is important to note that the beam 10 is approximately 50% lighter than the correspondingly sized [R:\LIBD]03398.doc:caa 4 FIRMLOK beam. The beam 10 thus represents a substantial strength to weight improvement over an equivalent FIRMLOK beam. Further, the FIRMLOK beam exhibited a (lateral buckling) failure at 170kg whilst the beam 10 did not fail until a 230kg load (due to local crimping of the top flange).

An embodiment of a method of producing the beam 10 will now be described with reference to Fig. 2. Firstly, the outer skin 12 of the beam is formed by roll-forming. An end 18 of the beam is then sealed with a removable plug 20. Two holes are then drilled approximately 2 meters and 4 meters from the plug 20 at the points indicated by arrows 22 and 24.

The beam 10 is then tilted until its longitudinal axis is at an angle acute to vertical.

Liquid expandable foam material is then injected through the hole 22 until it has filled and expanded past the hole 22. Additional liquid expandable foam material is then injected through the hole 24 until it has filled and expanded through the other end 26 of the beam When the foam material has expanded and set the plug 20 is removed and any excess foam material is trimmed from the beam end 26.

In addition to the strength to weight advantages described above, the beam 10 is also simpler and cheaper to produce than the FIRMLOK beams. Further, the foam inner core 16 resists bowing of the longer sides of the beam 10 when fasteners are inserted therethrough.

Referring to Figs. 3a and 3b there is shown a beam 30 according to a second embodiment of the present invention. The beam 30 is formed from an extruded aluminium outer skin 32, having a circular cross sectional closed shape. As with the first embodiment, the beam 30 also has an inner core 33 formed from expandable foam material.

The beam 30 is produced by initially sealing a lower end of the skin 32 with a removable plug 34. The skin is then oriented until its longitudinal axis is about vertical.

A hose 36 is then lowered into the interior of the skin 32 until its end 38 is adjacent the plug 34. Liquid expandable foam material 40 is then injected through the hose 36 into the interior of the skin 32, in the direction indicated by arrows 42. As the foam material expands to fill the skin 32, the hose 36 is progressively withdrawn from the skin 32, in the direction of arrow 44, until the entire interior of the skin 32 is filled. When the foam material 40 has expanded and set, the plug 34 is removed and the excess foam material is trimmed from the upper beam end.

[R:\LIB D]03 3 98.doc:caa In addition to the strength to weight advantages described above, the circular cross section beam 30 also exhibits enhanced flexibility, making it particularly suitable for structures subject to cyclonic conditions and/or for scaffolding structures.

Although the invention has been described with reference to preferred embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. For example, the beam can also be produced in other industry standard sizes such as 75mm by 50mm, 75mm by 100mm and 100mm by 100mm. Other types of expandable foam materials can also be used. The beam can also be produced by continuously injecting the foam material into the outer skin during the roll forming process, with the injecting nozzle positioned just in front of the closing seam.

The outer skin of the beam can also be folded into various shapes other than rectangular and can also be extruded in various cross sections other than circular.

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Claims (15)

1. A beam including: a metal outer skin formed into a closed shape; and an inner core formed from expanded foam material, wherein the outer surfaces of the inner core are bonded to the inner surfaces of the outer skin.

2. A beam as claimed in claim 1, wherein the outer skin closed shape is formed by folding.

3. A beam as claimed in claim 2, wherein opposed longitudinal edges of the outer skin are joined by a folded seam.

4. A beam as claimed in claim 1, wherein the outer skin closed shape is formed by extruding. A beam as claimed in any one of claims 1 to 4, wherein the outer skin has a rectangular cross-section.

6. A beam as claimed in any one of claims 1 to 4, wherein the outer skin has a round cross-section.

7. A method of forming a beam, the method including: forming a metal outer skin of a closed shape; and introducing an expandable foam material into the interior of the outer skin to form an inner core, whereby the outer surfaces of the inner core expand and bond to the inner surfaces of the outer skin.

8. The method as claimed in claim 7, wherein Step is performed by roll forming.

9. The method as claimed in claim 7 or 8, wherein Step is performed by introducing the expandable foam material into the interior of the outer skin after it is fully closed. [R:\LIBD]03398.doc:caa The method as claimed in claim 9, wherein Step includes: tilting the closed outer skin until its longitudinal axis is at an acute angle to vertical or is vertical; plugging its lower end; and injecting the foam material into its interior

11. The method as claimed in claim 10, wherein the foam material is injected at spaced apart locations.

12. The method as claimed in claim 7 or 8, wherein Step is performed by introducing the expandable foam material into the interior of the outer skin prior to it being fully closed.

13. The method as claimed in claim 12, wherein Step includes continuously injecting the foam material into the interior of the outer skin in advance of the closing fold.

14. The method as claimed in claim 7, wherein Step is performed by extruding. The method as claimed in claim 7 or 14, wherein Step is performed by introducing the expandable foam material into the interior of the outer skin after it is formed.

16. The method as claimed in claim 15, wherein Step includes tilting the closed outer skin until its longitudinal axis is at an acute angle to vertical or is vertical; plugging its lower end; and progressively injecting the foam material into the interior beginning substantially adjacent the lower end and ending substantially adjacent its upper end.

17. A beam substantially as described herein with reference to Figs. la to 2 or Figs. 3a and 3b of the accompanying drawings.

18. A method of forming a beam, the method substantially as described herein with reference to Figs. la to 2 or Figs. 3a and 3b of the accompanying drawings. Dated 3 March 2003 Jennifer Marie Charlwood Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON [R:\LIBD]03398.doc:caa