AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): BLUESCOPE STEEL LIMITED Invention Title: "METHOD OF PRODUCING CLADDING SHEETS" The following statement is a full description of this invention, including the best method of performing it known to me/us: - 2 METHOD OF PRODUCING CLADDING SHEETS The present invention relates to building structures, such as roofs, from roll-formed steel cladding 5 sheets. In particular, the present invention relates to manufacturing roll-formed steel cladding sheets for building structures, such as roofs. 10 The current standard practice for building a roof from roll-formed steel cladding sheets, such as COLORBOND cladding sheets, includes the following steps: 15 (a) roll-forming steel strip to form the number of rectangular sheets of a standard size that are required to build the roof; (b) marking up and thereafter cutting a number 20 of the rectangular sheets into required shapes for building the roof; and (c) constructing the roof by attaching the remaining standard-size sheets and the cut sheets to a 25 roof frame. In order to construct a typical roof it is necessary to cut approximately 40% of the initial number of standard-size rectangular cladding sheets that are 30 required to build the roof. The cuts required range from straightforward cuts to produce one or more angled corners to more complex cuts to produce irregular shaped sheets. The practice of cutting rectangular cladding 35 sheets results in considerable waste of material and requires a considerable amount of time. 01-039.4 18 complete speci 28/09/09 - 3 In addition, occasionally it is necessary to lift rectangular cladding sheets onto roofs to mark up the sheets and then lower the sheets to the ground and cut the sheets into the required shapes. This practice is time 5 consuming and introduces a safety risk in terms of lifting the sheets onto the roof and then lowering the sheets from the roofs An object of the present invention is to provide 10 a method and an apparatus for producing roll-formed steel cladding sheets for building a roof that is more efficient and cost effective and safer than the above-described current standard practice. 15 According to one aspect of the present invention there is provided an apparatus for producing a plurality of cladding sheets for building a structure, which apparatus includes: 20 (a) a roll-forming line for roll-forming a flat strip, for example wrapped in a coil, into a roll-formed cladding sheet; (b) a marking assembly for defining a 25 configuration of separate cladding sheets that can be subsequently cut from the roll-formed strip that have the correct size and shape to be placed directly onto an underlying frame and thereafter assembled together to form the structure, the marking assembly including a plurality 30 of marking means that are fixed relative to the roll forming line and are individually operable to mark the roll-formed strip; and (c) a control means for controlling operation 35 of the marking means in response to a computer program that provides a series of independent marking operations for each marking means that is derived from data relating 01-039.418 complete speci 28/09/09 - 4 to the design of the structure for facilitating production of separate cladding sheets that have a correct size and shape to be placed directly onto an underlying frame and thereafter assembled together to form the structure. 5 The fixed marking means reduces overall space required for the marking apparatus in the roll-forming line. This is a considerable advantage over alternative moveable marking means which occupy more space in the 10 roll-forming line and which have higher equipment costs. Furthermore, controlling independent marking means via a common controller enables the marking means to be positioned relative to one another to correspond to 15 similar profile features of the roll-formed strip. Accordingly, common control of the marking means enables marking of the roll-formed strip at accurate positions that collectively define lines, curves or shapes. The line, curves or shapes can be used to facilitate 20 subsequent cutting of the roll-formed strip into separate cladding sheets. The roll-formed strip may be any suitable profile. For example, the roll-formed strip may be a 25 corrugated sheet having successive crests and the troughs when viewed in transverse section and one underlap side edge and one overlap side edge. The cladding sheet may also include one or more ribs separated by pans and one underlap side edge and one overlap side edge. 30 The marking means may be any suitable marking apparatus. One such suitable marking apparatus includes a 35 plurality of downwardly directed paint/ink injectors, for example in the form of single shot valves, positioned above a section of the roll-forming line, with each of the 01-039.418 completespeci 28/09/09 - 5 plurality of paint/ink injectors being individually operable in response to the programmed marking operations to discharge paint/ink onto the sheet to mark the configuration of separate cladding sheets while the roll 5 formed cladding sheet is being processed on the line. The marking may include dot patterns to indicate a line or series of lines for subsequent cutting. The lines may be marked transverse the roll-formed strip, at 10 any angle in relation to the roll-formed strip, and may also be curved or take any other required form. Preferably, the control means operates in the relation to the speed of the roll-formed strip such that 15 the predetermined shape can be marked out by the marking means. Another suitable marking assembly includes a plurality of indenters that are independently operable in 20 response to the programmed marking operations to deform the roll-formed strip to mark at least part of the perimeters of separate cladding sheets. In a preferred embodiment, the indenters mark the 25 roll-formed strip by forming a dimple. Accordingly, one form of indenter comprises a pair of two opposed rams that move toward and away from one another to deform the sheet between them. 30 An advantage of this preferred embodiment is that, in addition to marking roll-formed strip to define at least part of the outline of separate cladding sheets, the indenters may also be individually operated by the control means to introduce dimples adjacent to edges of 35 each separate sheet of roll-formed strip to avoid damage caused by stacking the strip sheets on top of one another. O1-039.418 complete speci 28/09109 - 6 Preferably, the indenters are arranged in an array that traverses the width of the roll-formed strip. 5 Preferably, the indenters are arranged to coincide with similar profile features, such as ribs, pans, valleys or crests, of the roll-formed strip such that marking are formed on similar features of the roll formed strip. 10 Preferably, the indenters are arranged to from dimples that protrude from a weather-side of the roll formed strip. 15 The weather-side of a roll-formed strip is the side of the strip that is exposed to the weather when installed in a structure. Dimples protruding from the weather-side will 20 result in any rubbing being on an underside of the next sheet up in a stack of sheets. The underside is not viewable when a cladding sheet is installed in a structure. Rubbing on an underside of the cladding sheet is preferable because any rubbing typically will not be 25 visible on an installed roof, for example. Additionally, such orientation of dimples avoids fouling production line equipment, site equipment or sheets below in a stack. Furthermore, dimples protruding from the weather-side of the roll-formed sheet will be easily viewable for 30 subsequent cutting to form the separate cladding sheets and dirt and water will not collect in the dimple after installation. In an alternative form, the indenters are 35 arranged to from dimples that protrude from an underside of the roll-formed sheet. 01-039.418 complete speci 28/09/09 - 7 Underside or downward dimples can also be used to separated adjacent sheets in a stack and indicate a line or shape for cutting. Additionally, downward dimples can indicate the position of subsequent mechanical fasteners, 5 such as screws or nails. This is an important for preventing "tracking off" where a screw catches only a periphery of a roofing batten so that the cladding sheet is not properly fastened in that position. Moreover, using a suitably sized sealing washer will significantly reduce 10 any risk of dirt or water retention in the dimple. Preferably, the apparatus includes cutting means for cutting the roll-formed strip into predetermined lengths for stacking and transport to a building site. 15 According to the invention there is also provided a method of marking a roll-formed cladding sheet to define the configuration of a plurality of cladding sheets for building a structure, such as a roof, which includes the 20 steps of: (a) inputting data relating to the design of the structure into a computer program that translates the design data into a series of marking operations of a 25 marking assembly for marking the configuration of a plurality of smaller cladding sheets onto a roll-formed strip that can be subsequently cut to form separate cladding sheets that have the correct size and shape to be placed directly onto an underlying frame and thereafter 30 assembled together to form the structure, the marking assembly comprising; and (b) marking the roll-formed strip with the marking assembly in accordance with the marking operations 35 generated by the computer program, the marking assembly comprising a plurality of marking means that are fixed relative to a roll-forming line and are individually 01-039.418 complete spcci 28/09109 - 8 operable to mark the roll-formed strip, and defining the configuration of the plurality of cladding sheets by individually operating each marking means to mark the roll-formed strip. 5 Preferably this aspect of the invention further includes cutting the roll-formed strip on the marked configuration to form the plurality of smaller separate cladding sheets. 10 Preferably, the method includes cutting the roll formed strip into predetermined lengths for stacking and transport to a building site. 15 Preferably the method includes controlling the operation of the cutting assembly in response to the operation of the roll-forming line. Preferably the method includes marking the roll 20 formed strip while the roll-formed strip is being processed on a roll-forming line. Preferably the method includes controlling the operation of the marking assembly in response to the 25 operation of the roll-forming line. The marking assembly may be any suitable marking assembly. 30 Preferably the method includes marking each cut or marked cladding sheet to identify the sheet so that it can be differentiated by the marked identification from the other cladding sheets that are required to build the structure. 35 By way of example, the cladding sheets may be marked with consecutive numbers. 01-039.4 18 complctc speci 28/09/09 -9 Preferably the same identification marking system, such as consecutive numbers, is used to identify the cladding sheets and to mark the location of each 5 cladding sheet onto a plan of the structure. Preferably the method further includes packing the smaller separate cladding sheets in a predetermined order to facilitate subsequent assembling of the sheets to 10 build the structure. Preferably the method includes packing the cut smaller separate cladding sheets in a stack in reverse order so that the top cladding sheet in the stack is the 15 first sheet in the stack that is required for building the structure and each underlying sheet is the next sheet in the stack that is required for building the structure. Preferably the roll-formed cladding sheet is a 20 steel cladding sheet. One such suitable marking assembly includes an array of downwardly directed paint/ink injectors, for example in the form of single shot valves, positioned 25 above a section of the roll-forming line, with the paint/ink injectors being selectively operable in response to the programmed marking operations to discharge paint/ink onto the sheet to mark the perimeters of the smaller separate cladding sheets while the roll-formed 30 cladding sheet is being processed on the line. Another suitable marking assembly includes an array of indenters for forming dimples in the roll-formed strip. The indenters punch the roll-formed strip to form 35 localized deformation. Each indenter is controlled by a common control means. Additionally, each indenter is operated independently. Accordingly, the indenters can be 01-039.4 8 complete speci 28/09/09 - 10 used to form a series of dimples to define a line, series of line or a shape for indicating at least part of the perimeters of the separate cladding sheets. 5 The indenters may also be used to form dimples adjacent an edge of the roll formed strip such that when sheets are cut from the roll-formed strip and stacked, the edges of the sheets are spaced apart by the dimples. This is particularly important for preventing shear burr in 10 staked sheets. Burrs formed by cutting of the roll-formed strip may rub and scratch adjacent sheets in a stack. Placement of the dimples adjacent a cut edge reduces the likelihood of damage to the stacked sheets. 15 In this form, the indenters reduce capital costs by avoiding the need for providing a marking assembly and separate sheet end protection. The indenters also remove the need to have other forms of sheet end protection, such as plastic insert and thereby reduce capital and labour 20 costs associated with using such protection and reduce material wastage through burr shear damage. Preferably, the method involves marking the roll formed strip on similar profile features, such as ribs, 25 pans, valleys or crests, of the roll-formed strip. Preferably, the method involved forming dimples that protrude from a weather-side of the roll-formed sheet. 30 Preferably, the method involved forming dimples that protrude from an underside of the roll-formed sheet. The roll-formed cladding sheet may be any 35 suitable profile. For example, the cladding sheet may be a corrugated sheet having successive crests and the troughs when viewed in transverse section and one underlap 0 1-039.418 complete speci 28/09/09 - 11 side edge and one overlap side edge. The cladding sheet may also include one or more ribs separated by pans and one underlap side edge and one overlap side edge. 5 There is a wide range of possible options for the computer program. The form of the computer program may take into account different factors or prioritise the factors differently depending on whether the overall objective of the program is to: 10 (a) minimise material waste (and therefore optimise the cutting/marking operations to minimise material waste); 15 (b) maximise production rate; (c) provide the best layout of cladding sheets for the structure (and therefore optimise the cutting/marking operations to optimise the layout of the 20 cladding sheets for the structure); or (d) a hybrid of two or more of the above options. The factors include, by way of example: 25 (a) the possible combinations of shapes of cladding sheets that can build a structure of a particular design; 30 (b) the possible arrangements of the cladding sheet shapes along the length of a roll-formed cladding sheet being processed on a roll-former line, and more particularly the interrelationship of different shapes of cladding sheets along the length of the cladding sheet 35 being processed on the line; (c) the roll-form profile and the dimensions of 01-039 418 complete speci 28/09/09 - 12 the roll-formed cladding sheet being processed on the roll-former line; (d) the interrelationship of (a), (b), and (c), 5 and the actual design of the structure and the impact of the direction of the prevailing weather on the selection process; (e) the operating capacity of the roll-forming 10 line; (f) the operating capacity of the cutting/marking assemblies, and more particularly the capacity of the assemblies to cut/mark different shapes of cladding sheets 15 and (g) transportation and materials handling factors (such as maximum length/width that can be packed and transported). 20 With regard to factor (d) above, it is relevant to note that in any given situation the best possible layout of cladding sheets for a particular structure is influenced by (a) the roll-form profile and the dimensions 25 of the roll-formed cladding sheet being processed on the roll-former line, (b) how the design of the cladding sheet "fits" in relation to the features of the structure design, and (c) the prevailing weather direction in relation to the structure and the effect of weather on the 30 cladding sheet. By way of example, in the case of a structure in the form of a hip roof, there are a number of different arrangements of standard size cladding sheets and cut cladding sheets that can be assembled together to form the hip. One possible consideration for selecting 35 one of the arrangements is the wastage associated with cutting or marking and then cutting the cladding sheets on a roll-former line. Another possible consideration is the 01-039.418 compleic speci 2809/09 - 13 direction of the prevailing weather and more particularly selecting the arrangements in which the cladding sheets are positioned so that the overlap side edges face away from the prevailing weather direction. 5 Preferably the computer program is capable of generating quotations to supply cladding sheets to build a structure. 10 The present invention is described further by way of example with reference to the accompanying drawings, in which: Figure 1 is a diagram that illustrates one 15 embodiment of an apparatus for producing a plurality of cladding sheets in accordance with the invention. Figure 2 is a schematic top view of part of a marking assembly of the apparatus in Figure 1. 20 The apparatus shown in Figure 1 comprises a standard roll-forming line that has been modified to include a perforation assembly for perforating a roll formed cladding sheet. 25 With reference to Figure 1, flat steel strip is unwound from a coil 5 and passed successively through a series of roll-formers 7 that progressively roll a required profile in the strip. By way of example, the 30 profile may comprise a series of lengthwise extending flat pans separated by upstanding ribs with side edge formations to allow adjacent subsequently formed cladding sheets to be positioned in side by side overlapping relationship. The roll-formed strip 19 emerging from the 35 last of the roll-formers is moved past a position sensor 17 for sensing the position of the strip 19, a marking assembly 9, a perforating assembly 11, and a cutting 01-039.418 compleespeci 28,09/09 - 14 assembly 13 in the form of an exit shear. These assemblies 9, 11, 13 are selectively operable to mark, perforate and/or cut the roll-formed strip to produce cladding sheets having required shapes. The cladding 5 sheets emerging from the exit shear 13 are passed to a sheet handling station 15 and are stacked or otherwise handled as required. The perforation assembly 11 is operable to 10 perforate the roll-formed strip 19 to define the ends of non-squared and squared cladding sheets. The perforated roll-formed strip 19 is subsequently square cut, typically by the exit shear 13, to leave a section outboard of the perforated ends of the strip. The outboard section of the 15 cladding sheets can be consequently removed, for example at a building site, to form cladding sheets with the required shape. The marking assembly 9 is operable to mark the 20 roll-formed strip to uniquely identify lines and shapes that define each cladding sheet. Subsequent cutting of the roll-formed strip 19 separates marked cladding sheets from the roll-formed strip. 25 The above-described apparatus is controlled by software that: (a) translates design data for a structure, such as a roof of a house, into a series of marking, 30 perforating and/or cutting operations of the marking, perforation and/or cutting assemblies 9, 11, 13 for marking, perforation and/or cutting roll-formed strip to form the cladding sheets; and 35 (b) drives the roll-forming line; (c) drives the marking, perforation and/or 01-039 418 complete speci 28/09/09 - 15 cutting assemblies 9, 11, 13 and marks, perforates and/or cuts the roll-formed strip 19 to form cladding sheets having the required shapes. 5 The operation of the marking, perforating and/or cutting assembly 9, 11, 13 is responsive to the requirements of the programmed series of marking, perforating and/or cutting operations and the actual operation of the roll forming line at any given point in 10 time, as monitored by the sensor 17. Depending on the type of end profile required for a cladding sheet, the perforating and cutting assemblies 11, 13 may be operated. For example, in a number of 15 situations it may only be necessary to square cut the ends of the roll-formed strip 19. In these situations, operation of the exit shear 13 may only be required. In other situations it may be necessary to form angled, curved or composite cuts or perforations for defining the 20 ends of the cladding sheets of the roll-formed strip. In these situations operation of the perforating assembly 11 is appropriate. The marking assembly 9 comprises, in one form, a 25 fixed array of single-valve printing heads 20 (Figure 2). Each printing head 20 is controlled by a common control system (not shown) to fire a small quantity of ink or paint at the surface of the roll-formed strip 19 to form a marking. Controlled firing of the printing heads 20 30 according to a series of instructions provided by a computer program enables the printing heads 20 to mark the roll-formed strip 19 sequentially to form lines, curves or shapes that define a configuration of separate cladding sheets. 35 By defining the separate cladding sheets on the roll-formed strip prior to delivery on site enables on 01-039.418 complete speci 28/09/09 - 16 site workers to cut cladding sheets to size and shape before lifting onto a roof. This avoids the need for lifting and measuring the sheets on the roof prior to cutting and reduces time for constructing a roof 5 considerably. In another form, the marking assembly 9 comprises an array of independent hydraulic or pneumatic rams in the same configuration of the printing heads 20 shown in 10 Figure 2. The rams are operable to deform the roll-formed strip to form dimples or recesses by localised deformation of the roll-formed strip. The rams are linked to a common control means and 15 are individually operable in the same manner described above in respect of the printing heads 20. The rams may be arranged in the roll-forming line above or below the roll-formed strip 19 to form dimples 20 that protrude, respectively, from a weather-side or an underside of the roll-formed strip 19. Although the marking assembly 9 is shown in Figure 1 between the position sensor 17 and the 25 perforation assembly 11, the marking assembly may be located before or after the exit shear 13 and preferably is located immediately before the exit shear 13. In such position, the marking assembly does not interfere with other operations for forming the roll-formed strip 19. 30 Additionally, in such position, the dimples can be located on most required locations on the roll-formed strip 19 and accurate control of the roll-formed strip 19 is maintained while the dimpling process is being carried out. 35 Many modifications may be made to the preferred embodiment of the present invention described above without departing from the spirit and scope of the present 01-039.418 complete speci 28/09/09 - 17 invention. In the claims which follow and in the preceding description of the invention, except where the context 5 requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is 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 10 features in various embodiments of the invention. 01-039 418 complete speci 28i09,09