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 One 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 unwound from a coil to form a roll-formed profile and thereafter successively square cutting the ends of the roll-formed strip to form a plurality of rectangular sheets of a standard size that are required to build the roof; 20 (b) marking up and thereafter cutting the ends of a number of the rectangular sheets into required shapes for building the roof; and 25 (c) constructing the roof by attaching the remaining standard-size sheets and the cut sheets to a roof frame. In order to construct a typical roof it is 30 necessary to cut approximately 40% of the initial number of standard-size rectangular cladding sheets that are 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. 35 The practice of cutting rectangular cladding sheets results in considerable waste of material and 0 -039.417 complete speci 28/09/09 - 3 requires a considerable amount of time. In addition, occasionally it is necessary to 5 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 consuming and introduces a safety risk in terms of lifting the sheets onto the roof and then lowering the sheets from 10 the roofs Another practice for building a roof involves preparation of steel cladding by perforation of the cladding in a production line prior to delivery on site. 15 Perforations are formed in strip prior to roll-forming to form profiled steel cladding. The perforated cladding is finally prepared on site by removing outboard waste sections by subsequent breaking or cutting along a line of perforation. 20 Such perforation practices involve a linear punch in a frame that is rotatable about a vertical axis to provide a line of perforations at a desired angle relative to strip travel. The punch is sized to traverse the width 25 of the strip over a range of angles so that the rotatable movement of the frame enables lines of perforations to be formed at a variety of angles traversing the strip. However, the frame for forming such perforations 30 is significantly wider than the width of the flat feed strip to form low angle transverse perforations and moving the frame from one angle to another involves sweeping through a large volume about the production line. Accordingly, such practices occupy a considerable space on 35 the production line. Additionally, punches used in such practices may 01-039.417 complete spcci 28/09/09 - 4 be designed to provide perforations in similar features of the profile for particular angles. However, using the same punch at different angles causes the punch to align with and perforate non-similar profile features. For 5 example, perforations may be in valleys near the middle of a roll-formed strip, but on or near the crests in regions toward the edges. While the roll-formed strip is weaker along the line of perforation, considerable difficulty is experienced in bending and snapping roll-formed strip 10 where the non-perforated areas are on different features of the profile. In some cases, cutting on site, along the line of perforation, is required. Lines of perforation formed by such practices do 15 not make outboard sections readily severable and often still require cutting time and effort that is comparable with non-perforating practices. An object of the invention is to provide a method 20 and apparatus for producing roll-formed steel cladding sheets for building structures, such as roofs, that is more efficient and that occupies less production line space than the above-described practices. 25 According to the invention there is provided an apparatus for producing a plurality of cladding sheets for building a structure, which apparatus includes: (a) a roll-forming line for roll-forming a flat 30 strip, for example wrapped in a coil, into a roll-formed strip; (b) a perforating assembly for perforating the roll-formed strip to define a plurality of shaped cladding 35 sheets, the perforating assembly including a plurality of punches, each having a width less than the width of the roll formed strip and the punches are arranged to traverse 01-039.417 complete speci 28/09/09 - 5 at least part of the width of the roll-formed strip, the punches are individually configurable to a selected angle transverse the roll-formed strip and are individually operable to perforate the roll-formed strip; and 5 (c) a control means for controlling the configuration and operation of the punches in response to a computer program and for perforating the roll-formed strip to define a plurality of shaped cladding sheets. 10 The apparatus of the invention occupies a reduced space in comparison to the above-mentioned practices because the collective width of the arranged punches does not substantially exceed the width of the roll-formed 15 strip and because the punches can be positioned at an angle and operated sequentially to produce angled and shaped lines of perforation. This avoids the need for a single rotatable punch that occupies a much larger space. Accordingly, the invention provides a reduced space 20 assembly for perforating roll-formed strip at a range of angles. Additionally, individual configuration and operation of the punches enables complex shapes to be 25 formed, such as "arrow head" shapes required on roofing sheets near an apex of a hip roof. Preferably, the perforation assembly is fixed relative to the roll-forming line. 30 Preferably, each punch has a width that is approximately 0.5 to 5 times the pitch of a profile feature, such as a pan, rib, valley or crest, of the roll formed strip. 35 Preferably, each punch has a width that is approximately 0.5 to 3 times the pitch of a profile 01-039417 complete speci 28/09/09 -6 feature. Preferably, the punch width is approximately 2 times the pitch of the profile feature. 5 Preferably, the punches perforate the strip by a movement that is substantially normal to a general plane of the roll-formed strip to perform a punching operation. 10 Preferably, each punch is configurable about an axis that is normal to a general plane of the roll-formed strip. Preferably, the punches are arranged in an array 15 that traverses a longitudinal axis of the roll-formed strip. Preferably, the punches are staggered in the array and the control means accounts for the stagger. 20 Preferably, the array is perpendicular to the longitudinal axis of the roll-formed strip. 25 Preferably, the apparatus includes means for controlling movement of the roll-formed strip being processed and which means is controlled in response to the computer program. 30 Preferably, the centre of each punch is aligned to register with the same respective profile feature of the roll-formed strip. Alignment of the punches in this manner is 35 important for reducing effort required to separate sections of the roll-formed strip along the perforation line. It is anticipated that such arrangement of the 0 1-039.417 complete speci 28/09/09 punches enables sections to be separated simply by breaking the roll-formed strip along the perforation line and that cutting may be avoided. 5 The cladding sheet may be any 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 side edge and one overlap side edge. The cladding sheet may also include 10 one or more ribs separated by pans and one underlap side edge and one overlap side edge. Preferably, the computer program provides a series of perforating operations of the perforating 15 assembly that is derived from data relating to the design of the structure for producing separate smaller cladding sheets that have the correct size and shape to be placed directly onto an underlying frame and thereafter assembled together to form the structure. 20 The perforating assembly may include one or more cutters positioned in relation to the roll-forming line and operable to cut the roll-formed strip into predetermined lengths. 25 Preferably the roll-forming line includes an uncoiler for a coil of strip and a series of roll-forming stands for successively roll-forming strip unwound from 30 the uncoiler into a roll-formed profile. According to the present invention there is also provided a method of producing a plurality of roll-formed cladding sheets for building a structure, such as a roof, 35 which includes the steps of: (a) inputting data relating to the design of 01 -039.417 complete speci 28/09/09 the structure into a computer program that translates the design data into a series of perforating operations for individually controlling each of a plurality of punches, each punch having a width less than the width of the roll 5 formed strip and the punches are arranged transverse at least part of the width of the roll-formed strip, the plurality of punches comprises a perforating assembly for perforating strip having a roll-formed profile to define a plurality of shaped cladding sheets that have the correct 10 size and shape to be placed directly onto an underlying frame and assembled together to form the structure; and (b) perforating the roll-formed strip with a perforating assembly in accordance with the series of 15 perforating operations generated by a computer program and defining the plurality of shaped cladding sheets by (i) individually configuring each punch to an angle selected by the computer program transverse of the roll-formed strip and (ii) individually operating each punch to 20 perforate the roll-formed strip. Preferably the method described in the preceding paragraph further includes separating the shaped cladding sheets along formed perforation lines to form the 25 plurality of separate cladding sheets. Preferably the method includes perforating the roll-formed cladding sheet while the cladding sheet is being processed on a roll-forming line. 30 Preferably the method includes overlapping perforations formed by the punches to cut sections from the roll-formed strip to form one or more separate 35 cladding sheets. In this situation, the method can be used to 01-039417 completespeci 28/09/09 - 9 shape ends of cladding sheets that comprise the full width of the roll-formed strip. The perforating assembly may include one or more 5 cutters positioned in relation to the roll-forming line and operable to cut the roll-formed strip into predetermined lengths. Preferably, the punches are fixed relative to the 10 roll-forming line. Preferably, the punches are arranged in an array that traverses a longitudinal axis of the roll-formed strip. 15 Preferably the method includes marking the roll formed strip to define the perimeters of the separate cladding sheets using a marking assembly that is supported in relation to the roll-forming line to move in response 20 to programmed marking operations. The marking assembly may be any suitable marking assembly. 25 one such suitable marking assembly includes an array 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 the paint/ink injectors being selectively operable in response 30 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 cladding sheet is being processed on the line. 35 Preferably the method includes controlling the operation of the perforating assembly in response to the operation of the roll-forming line. 01-039.417 complete speci 28/09/09 - 10 Preferably the method includes controlling the operation of the marking assembly in response to the operation of the roll-forming line. 5 Preferably the method includes marking or otherwise branding each perforated or marked cladding sheet to identify the sheet so that it can be differentiated by the marked identification from the other 10 cladding sheets that are required to build the structure. By way of example, the cladding sheets may be marked with consecutive numbers. 15 Preferably the same identification marking system, such as consecutive numbers, is used to identify the cladding sheets and to mark the location of each cladding sheet onto a plan of the structure. 20 Preferably the method further includes packing the separate cladding sheets in a predetermined order to facilitate subsequent assembling of the sheets to build the structure. 25 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 first sheet in the stack that is required for building the structure and each underlying sheet is the next sheet in 30 the stack that is required for building the structure. Preferably the roll-formed cladding sheet is a steel cladding sheet. 35 The roll-formed cladding sheet may have any suitable profile. For example, the cladding sheet may be a corrugated sheet having successive crests and the 01-039.417 complctcspcci 28/09/09 - 11 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. 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 10 objective of the program is to: (a) minimise material waste (and therefore optimise the cutting/marking operations to minimise material waste); 15 (b) maximise production rate (and therefore optimise the time required for the cutting/marking operations on the roll-formed strip); 20 (c) provide the best layout of cladding sheets for the structure (and therefore optimise the cutting/marking operations to optimise the layout of the cladding sheets for the structure); or 25 (d) a hybrid of two or more of the above options. The factors include, by way of example: (a) the possible combinations of shapes of 30 cladding sheets that can build a structure of a particular design; (b) the possible arrangements of the cladding sheet shapes along the length of a roll-formed strip being 35 processed on a roll-former line, and more particularly the interrelationship of different shapes of cladding sheets along the length of the strip being processed on the line; 01 -039.417 complete speci 28,09/09 - 12 (c) the roll-form profile and the dimensions of the roll-formed cladding sheet being processed on the roll-former line; 5 (d) the interrelationship of (a), (b), and (c), and the actual design of the structure and the impact of the direction of the prevailing weather on the selection process; 10 (e) the operating capacity of the roll-forming line; (f) the operating capacity of the cutting/marking 15 assemblies, and more particularly the capacity of the assemblies to perforate/mark different shapes of cladding sheets and (g) transportation and materials handling factors 20 (such as maximum length/width that can be packed and transported). With regard to factor (d) above, it is relevant to note that in any given situation the best possible 25 layout of cladding sheets for a particular structure is influenced by (a) the roll-form profile and the dimensions 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 30 design, and (c) the prevailing weather direction in relation to the structure and the effect of weather on the cladding sheet. By way of example, in the case of a structure in 35 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 01-039.417 complete speci 28/09/09 - 13 hip. One possible consideration for selecting 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 5 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. 10 Preferably the computer program is capable of generating quotations to supply cladding sheets to build a structure. The applicant has found in trials carried out 15 with an embodiment of the apparatus and method of the present invention that it is possible to reduce the labor time required to build roofs by between 20% and 50% and substantially reduce material waste. 20 The present invention is described further by way of example with reference to the accompanying drawings, in which: 25 Figure 1 is a diagram that illustrates one 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 30 perforation assembly of the apparatus in Figure 1. Figure 3 is an elevation of a punch in Figure 2 with a roll-formed strip shown in transverse section. 35 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 01-039.417 completespeci 28/09/09 - 14 formed cladding sheet. With reference to Figure 1, flat steel strip is unwound from a coil 5 and passed successively through a 5 series of roll-formers 7 that progressively roll a required profile in the strip. By way of example, the profile may comprise a series of lengthwise extending flat pans separated by upstanding ribs with side edge formations to allow adjacent subsequently formed cladding 10 sheets to be positioned in side by side overlapping relationship. The roll-formed strip 19 emerging from the 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 15 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 sheets emerging from the exit shear 13 are passed to a 20 sheet handling station 15 and are stacked or otherwise handled as required. The perforation assembly 11 is operable to perforate the roll-formed strip 19 to define the ends of 25 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 cladding sheets can be subsequently removed, for example 30 at a building site, to form cladding sheets with the required shape. The marking assembly 9 is operable to brand the roll-formed strip to uniquely identify each subsequently 35 defined cladding sheet. The above-described apparatus is controlled by 0 1-039 417 complete spcci 28/09/09 - 15 software that: (a) translates design data for a structure, such as a roof of a house, into a series of marking, 5 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 10 (b) drives the roll-forming line; (c) drives the marking, perforation and/or cutting assemblies 9, 11, 13 and marks, perforates and/or cuts the roll-formed strip 19 to form cladding sheets 15 having the required shapes. The operation of the marking, perforating and/or cutting assembly 9, 11, 13 is responsive to the requirements of the programmed series of marking, 20 perforating and/or cutting operations and the actual operation of the roll forming line at any given point in time, as monitored by the sensor 17. Depending on the type of end profile required for 25 a cladding sheet, the perforating and cutting assemblies 11, 13 may be operated. For example, in a number of 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 30 other situations it may be necessary to form angled, curved or composite cuts or perforations for defining the ends of the cladding sheets of the roll-formed strip. In these situations operation of the perforating assembly 11 is appropriate. In particular, the perforating assembly 35 11 is in the form of a plurality of punches 20 (Figure 2). The punches 20 are arranged in an array that 01-039.417 compcc speci 28/09/09 - 16 traverses the width of a roll-formed strip 19. As shown in Figure 2, the array comprises eight independent punches 20 each having a blade 21 that can be driven to perforate the roll-formed strip 19. Each blade 21 is mounted in a 5 fixed frame 23 that does not move relative to the roll forming line. Additionally, each blade 21 is configurable with suitable positioning means to a desired angle relative to a longitudinal axis of the roll-formed strip 19 and is independently controlled so the angle of some 10 blades 21 may be different to the angle of other blades 21 in order to form complex perforation lines in the roll formed strip. It will be appreciated, however, that the 15 perforating apparatus 11 may include more or less punches 20 than shown in Figure 2. Each punch 20 is linked to a control means that controls operation of the punches 20 in response to the 20 software. This is a significant advantage in view of conventional practices which typically utilise a single linear blade transverse to the roll-formed strip. The 25 single blade must be swept through angles in order to change a line of perforation. The punches 20 avoid the need for providing significant free space for the blade to sweep through by using individual blades 21 that are arranged across the full width of the roll-formed strip 30 19. The lines of perforation are formed by the punches 20 by sequentially operating blades 21 in response to strip 19 movement. This enables lines of perforation 35 to be formed across the full strip width or any part thereof by rotating each blade 21 to a desired angle and operating each punch at a specific time as the roll-formed 01-039.417 compIeC speci 28/09/09 - 17 strip 19 passes. Accordingly, by selecting appropriate blade 21 pitches and widths, perforations can be formed as a line 5 or lines across the roll-formed strip at almost any angle and the perforations may form a curve or other complex forms. The position of the punches 20 is selected to 10 coincide with a profile feature of the roll-formed strip 19. The profile feature might be any one of a pan, rib, valley or crest so that non-perforated areas between punched sections will generally be located on similar parts of the profile. For example, the non-perforated 15 areas may be located on the crests or in the valleys of a corrugated profile. This is important in terms of reducing effort required to separate a cladding sheet from the roll-formed strip 19 by bending and snapping along a line of perforation. 20 In contrast, conventional practices generally do not provide perforations in similar sections of a profile with the result that the non-perforated areas are difficult to bend and snap. For example, non-perforated 25 areas in both crests and valleys are difficult to break. The punches 20 are formed in a staggered array to enable overlap of adjacent blades 21. Such overlap enables the full width of the roll-formed strip to be cut 30 or perforated as required and along the lines that are oblique to the longitudinal axis of the roll-formed strip. In many cases, the line of perforation is 450 or slightly greater relative to a line perpendicular to the 35 direction of travel of the roll-formed strip 19. Punch 21 widths suitable for forming perforations and/or cuts at such angles are approximately r2 times the pitch of the 01-039417 complete speci 28/09/09 - 18 profile, i.e. crest to crest for a corrugated profile. This width ensures that some material remains uncut for perforations that are at angles slightly greater than 450*. If lower angle perforations are required, the punches 21 5 may be replaced with narrower punches as required. 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 10 invention. 01-039.417 complete speci 28/09/09