AU2009212994A1 - Roll forming process and feedstock for use in same - Google Patents

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): BLUESCOPE STEEL LIMITED Invention Title: "ROLL FORMING PROCESS AND FEEDSTOCK FOR USE IN SAME" The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 ROLL FORMING PROCESS AND FEEDSTOCK FOR USE IN SAME Field of the Invention 5 The present invention relates generally to roll forming processes including metal feedstock and to metal panels formed from such feedstock. The invention has been designed especially, but not exclusively, for roll formed cladding panels and is herein described in that context. However it is to be appreciated that the invention has broader application and is not limited to that particular use. 10 Background of the Invention Sheet metal panels are well known and used widely in roof and wall cladding. The panels are typically formed from feedstock of sheet metal strip which is supplied to 15 a roll former in a coil. The feedstock is fed through the roll former to profile the sheet to include stiffening ribs, corrugations or the like to increase its strength. The sheet is then cut at selected intervals to form panels. Edge regions of the panels are also often roll formed to allow adjacent panels to interlock along those regions. 20 Summary of the Invention According to a first aspect, the invention relates to a feedstock for a roll former, the feedstock being of laminate structure and comprising spaced apart first and second metal sheets, and an intermediate layer disposed between the sheets. 25 The feedstock of the present invention includes significant practical benefit. The feedstock with its composite construction forms profiled panel having better spanning capability than a single skin cladding panel with the same profile, and has better thermal characteristics. Furthermore, use of this feedstock in a roll former allows for the production of profiled composite panels which can be manufactured rapidly and 30 at a low cost compared to conventional profiled composite panels manufactured by a multi-stage operation. Preferably, the first and second sheet metal layers of the feedstock of the present invention comprise an outer and an inner surface with the outer surface of the layers forming opposite outer surfaces of the feedstock. In this way, the metal layers 35 form the skin of the feedstock. These metal skins may be coated such as with a protective coating of an alloy of aluminium and zinc and/or may have a pre-painted coated surface. Preferably, the thickness of the metal sheet is between 0.1-1mm and 3 more preferably about 0.2-0.5mm In a preferred form, the first and second sheet metal layers are bonded to the intermediate layer. In one form this bonding is through use of an adhesive which forms an additional layer between the intermediate layer and one or both of the sheet metal 5 layers. The adhesive may become effective at room temperature or on subjecting it to elevated temperatures. In an another form, the intermediate layer is fuse bonded directly to one or both of the sheet metal layers. This may be achieved by heating the feedstock to a temperature which causes the surface of the intermediate layer to become tacky and 10 fuse to the sheet metal layer which it is in contact with. Preferably, the intermediate layer is resilient so that it does not unduly deform under the roll forming operation. In a preferred form, on roll forming the feed stock, the intermediate layer is compressed as the sheet is profiled, but returns to its natural state after this processing 15 step. The advantage of this arrangement is that the profiled panel maintains a substantially uniform thickness. In an alternative form, the intermediate layer may be designed so that it does not return fully to its preformed state on roll forming so that the thickness of the panel varies across its width. In a particularly preferred form, the intermediate layer is formed as a foam and 20 more preferably as a closed cell plastic foam. Preferably the thickness of the plastic foam is in the range of 2-15mm and more preferably in the range of 5-10mm. With an intermediate layer of this thickness, the overall thickness of the feedstock is preferably in the range of 5-20mm. A further aspect of the invention comprises a profiled composite panel formed 25 from roll forming feedstock according to any form described above. In yet a further form, the invention relates to a method of forming a profiled composite panel comprising the step of providing feedstock as described in any form above; and roll forming the feedstock to form the profiled composite panel. In yet a further form, the invention relates to a method of forming a composite 30 panel, comprising the steps of feeding first and second sheet metal strips into a process line; simultaneously feeding an intermediate strip into the process line in an orientation so as to align and locate between the first and second metal sheet so as to form a layered structure; and bonding the intermediate strip to the first and second metal sheets. In one form, the intermediate strip is bonded to at least one of the first and 35 second metal sheets by an adhesive. In that arrangement, the adhesive is preferably applied prior to introducing the strips into the process line. In one form, when the strips are bonded by an adhesive, pressure is applied to 4 the layered structure so as to facilitate bonding of the first and second sheets into engagement with the intermediate strip. In addition, or alternatively, the adhesive is heated so as to aid or promote bonding of the first and second sheets to the intermediate strip. 5 In an alternative form, the intermediate strip is fuse bonded to the first and second metal sheets. Preferably in this arrangement, the layered structure is heated so as to cause the intermediate strip to at least partially melt so as to become tacky and fuse to the sheet metal layers which it is in contact with. In a preferred form, pressure is applied to the layered structure to aid bonding 10 of the first and second sheets with the intermediate layer. In one form, this pressure is applied by passing the layered structure through a pair of nip rollers. Preferably the composite panel is of a selected length and the method further comprises the step of cutting the bonded layered structure at selected intervals so as to form said composite panel of said selected length. 15 The advantage of the present invention is that the composite panel can be made rapidly at line speeds which are consistent with that of a conventional roll former. Typically the line speeds would be in the order of 10-50 metres/minute. In yet a further aspect, the invention relates to a method of forming feedstock for a roll former, the method comprises the steps of feeding first and second sheet metal 20 strips into a process line, simultaneously feeding an intermediate strip into the process line in an orientation so as to align and locate between the first and second metal sheets so as to form a layered structure; bonding the intermediate strip to the first and second metal sheets; and winding the bonded layered structure onto rolls so as to provide feedstock for a roll former. 25 In a preferred form, the intermediate strip is bonded to the metal sheets either by an adhesive of fusion bonding technique as described above. In yet a further aspect, the invention relates to a method of forming a profiled composite panel comprising the steps of: feeding first and second sheet metal strips into a process line, simultaneously feeding an intermediate strip into the process line in an 30 orientation so as to align and locate between the first and second metal sheets so as to form a layered structure; bonding the intermediate strip to the first and second sheets; and roll forming the bonded layered structure so as to form the profiled composite panel, wherein the bonded layered structure is formed and roll formed in a single pass. Preferably, the first and second sheet metals and the intermediate strip have a 35 structure as described above with respect to the feedstock of earlier aspects of the invention.

5 Brief Description of the Drawings It is convenient to hereinafter describe an embodiment of the invention with reference to the accompanying drawings. It is to be appreciated that the particularity of 5 the drawings and the related description is to be understood as not superseding the generality of the preceding broad description of the invention; In the drawings Figure 1 is a schematic view of a feedstock for a roll former; Figure 2 is a schematic view of a composite panel formed from the feedstock of Figure 1; and 10 Figure 3 is a process line for producing profiled composite panels. Referring to Figure 1, feedstock 10 for a roll former is disclosed and comprises first and second sheet metal strips (11, 12 respectively) and a foam core 13 which is disposed between the two sheet metal strips. In the illustrated form, the foam core is fuse bonded directly to the metal sheets 11, 12. The bond is caused by heating the foam 15 core so that it becomes tacky and fuses to the metal sheets. In an alternative form (not shown), adhesive layers may be incorporated between the metal sheet 11, 12 and the foam core to bond the layers together. The thickness of the metal strips is about 0.2mm. In the illustrated form, one of the strips 1 is designed to be the outwardly facing side of a cladding panel 20 20 formed from the feedstock 10 and includes a prepainted coated surface. One such suitable strip is produced by the applicant and sold under the trade mark COLORBOND@. The inner sheet metal layer 12 may also include a protective coating such as an alloy of aluminium and zinc. A suitable material is that sold by the applicant under the trade mark ZINCALUME@. 25 The foam core 1 3 is resilient and is typically formed from a closed cell plastic. The core has a thickness of between 5 and 10mm but may be larger if desired. Preferably the overall thickness of the feedstock is in the order of 5-20mm. The foam core is resilient so that it will not unduly deform on roll forming. Turning to Figure 2, a profiled cladding panel which is formed from roll 30 forming the feedstock 10. In the context of this specification, the term "profiled" relates to a panel which has been shaped to be other than planar. As illustrated in Figure 2, the panel 20 is roll formed into a corrugated profile having a series of alternating ridges 21 and valleys 22. The panel 20 is a composite structure formed from the metal sheets 11, 12 interconnected by the foam core 13. The 35 thickness of the panel 20 is substantially constant in cross-section as the foam core 13 has not unduly deformed as a result of the roll forming operation. The panel 20, which may be used for roofing, walling, fencing or for 6 architectural panels, has significant improvements over single skin panels. In particular it is able to span greater lengths and has improved thermal characteristics. Figure 3 illustrates schematically, a process line 50 for forming the panel 20. A feature of the process line 50 is that the layered feedstock 10 is both formed and roll 5 formed into the panel 20 in a single pass. The process line includes first and second metal coils (51, 52) and a foam coil 53. The sheet metal strips in the coils 51, 52 are fed into the process line 50 and simultaneously the foam strips from the coil 53 are also fed into the process line in an orientation so as to align and locate between the first and second metal strips. This 10 layered structure 54 is then fed into a heating unit 55 wherein it is heated so as to cause the foam 53 to partially melt so as to become tacky and bond to the metal in which it is contact with. Nip rollers 56 may be incorporated within the process line 50 to apply pressure to the layered structure so as to assist in bonding the elements together. Once the layered structure 54 is bonded it forms the feedstock 10 which then passes into a 15 conventional roll former 60. As will be appreciated by those skilled in the art, the feedstock 10 may be profiled into a vast range of shapes. After passing through the roll former the sheet is then cut at desired lengths to form the profiled composite panel 20. Typically the line speed of the process line is in the range of 10-50 metres/minute. As such, the profiled cladding panel 20 may be produced at 20 significantly greater speeds than that which was previously possible for composite panels. Further, the cost of manufacture is significantly reduced. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is 25 used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. It will be appreciated that variations and/or modifications may be made to the parts previously described without departing from the spirit or ambit of the invention. 30

Claims (6)

1. A feedstock for a roll former, the feedstock being of laminate structure and comprising spaced apart first and second metal sheets, and an intermediate layer disposed between the sheets. 5

2. A profiled composite panel formed from roll forming feedstock according to claim 1.

3. A method of forming a profiled composite panel comprising the steps of: providing feedstock according to claim 1; and roll forming the feedstock to form the profiled composite panel. 10

4. A method of forming a composite panel, comprising the steps of: feeding first and second sheet metal strips into a process line; simultaneously feeding an intermediate strip into the process line in an orientation so as to align and locate between the first and second metal sheet so as to form a layered structure; and bonding the intermediate strip to the first and second metal sheets. 15

5. A method of forming feedstock for a roll former, the method comprises the steps of: feeding first and second sheet metal strips into a process line, simultaneously feeding an intermediate strip into the process line in an orientation so as to align and locate between the first and second metal sheets so as to form a layered structure; bonding the intermediate strip to the first and second metal sheets; and winding the 20 bonded layered structure onto rolls so as to provide feedstock for a roll former.

6. A method of forming a profiled composite panel comprising the steps of: feeding first and second sheet metal strips into a process line, simultaneously feeding an intermediate strip into the process line in an orientation so as to align and locate between the first and second metal sheets so as to form a layered structure; bonding the 25 intermediate strip to the first and second sheets; and roll forming the bonded layered structure so as to form the profiled composite panel, wherein the bonded layered structure is formed and roll formed in a single pass. 30 DATED THIS 2ND SEPTEMBER 2009 BLUESCOPE STEEL LIMITED