AU2009201000B2 - Method and apparatus for roll-forming profiled metal sections - Google Patents

Abstract

- 20 This invention relates to a method and apparatus for forming a profiled metal section by cold forming a metal 5 strip. The formed profiled metal section includes a central web, flanges extending outwardly from respective edges of the web, and longitudinally extending channel shaped recesses in the web. The method involves forming the channel-shaped recesses in the final stages of forming 10 the profiled metal section. The apparatus comprises a series of rolling stages for forming the flanges and the channel-shaped recesses. The rolling stages for forming the channel-shaped recesses are positioned in the final rolling stages for forming the profiled metal section. N:\Melbourne\Casea\Patent\76000-76999\P76188.AU.1\Specis\P76188.AU.1 epec.doc 12/03/09 FIGURE 2 FIGURE 3 Uncoiled and Uncoiled and punched metal strip punched metal strip 34-~

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant: BLUESCOPE STEEL LIMITED Invention Title: METHOD AND APPARATUS FOR ROLL-FORMING PROFILED METAL SECTIONS The following statement is a full description of this invention, including the best method for performing it known to me/us: P76188.AU.1 Pat.Set Fing Applicallon 2009-3-12.doc (M) -2 METHOD AND APPRATUS FOR ROLL-FORMING PROFILED METAL SECTIONS Field of the invention 5 The present invention relates to an apparatus for and method of forming a profiled metal section from sheet metal strip. 10 The invention has been developed especially for roll forming metal profiles such as C-shaped and Z-shaped metal purlins and the invention is herein described in that context. The invention, however, has broader application and is not limited to that particular use. 15 Background of the invention Metal purlins are used extensively in constructing commercial buildings, such as factories and 20 warehouses, where large covered areas are required. Purlin sections are generally formed by roll forming metal strip to have a central longitudinal web and flanges extending outwardly from each edge of the web. 25 In constructing a building, costs are reduced by forming purlins to extend over greater spans, thereby bearing greater roofing loads. However, conventional purlin sections are limited in strength and tend to buckle 30 by way of torsional twisting of the web and by buckling of the web itself to form a curved shape. In order to reduce torsional buckling, lips are formed on the ends of the flanges to extend from the 35 flanges and to overlap the web. In some instances, return lips are formed on the lip and extend back toward the web. Nr\Melbourne\Casea\Patent\76000-76999\P76188.AU.1\Specis\P76188.AU.1 Bpec.doc 12/03/09 -3 International applications PCT/AU96/00051 and PCT/AU97/00053 disclose improved metal purlin sections which incorporate a web with outwardly extending flanges 5 along each edge of the web such that the metal purlin sections have the general from of C-shaped and Z-shaped sections. A lip and return lip are formed on the outer edge of the flanges. The sections include one or more channel-shaped recesses, also known as knurls or flutes, 10 extending longitudinally in the web. The content of the International applications is incorporated herein by this reference. 15 The form of the lip and return lip disclosed in each International application and the presence of the channel-shaped recesses causes a significant increase in stiffness of the purlin and, hence, increases the level of stress that marks the onset of local buckling. The result 20 is stronger purlins that are able to span greater distances, thereby reducing construction costs. The process for forming metal purlin sections with channel-shaped recesses involves incorporating the 25 channel-shaped recesses during initial roll-forming stages. This is because forming the recesses creates distortion in the strip that requires subsequent straightening to form a generally planar web. 30 However, the strip, stiffened by the channel shaped recesses, is harder to form into the C and Z-shaped profiles and, accordingly, requires greater rolling forces and additional rolling stages. As a consequence, roll forming machinery requires stronger motors to advance the 35 metal strip and therefore requires roll-forming machinery that is purpose-built for forming channel-shaped recesses. N:\Melbourne\CaeeB\Patent\76000-76999\P76188.AU.1\SpeciB\P76188.AU.1 spec.doc 12/03/09 - 4 Roll-forming purlins with channel-shaped recesses, therefore, is more costly than producing purlins without channel-shaped ribs. This is in part due to additional running costs, for example extra power costs 5 and extra bearing, drive chain and roller maintenance costs. It is also in part due to purpose-built roll formers, for producing purlins with channel-shaped recesses, costing approximately three times as much as conventional roll-forming machinery. 10 Summary of the invention An object of the present invention is to provide an improved method and apparatus for roll-forming metal 15 strip with channel-shaped recesses. The present invention provides a method of forming a profiled metal section by cold forming a metal strip to include a central web, flanges extending 20 outwardly from respective edges of the web, lips and return lips extending from free edges of the respective flanges and longitudinally extending channel-shaped recesses in the web, the method comprising the steps of: 25 (a) passing the strip of metal through a series of rolling stages to form a web with outwardly extending flanges, lips and return lips; 30 (b) passing the formed strip through one or more rolling stages for forming one or more channel-shaped recesses in the web; and the flanges are preferably formed in a series of rolling 35 stages in which the angle of the flange relative to the web is increased incrementally until the flanges reach a final orientation relative to the web and step (b) occurs 5992775_1 (GHMatters) P76188.AU.1 LEANNE 26 Novernber 2014 - 5 after partially forming the flanges and prior to one or more final rolling stages in the series of rolling stages for forming the flanges 5 The advantage of this method is that strengthening of the web occurs after the web and the flanges have already been formed. Consequently, the number of rolling stages and the force required at each stage is reduced in respect of forming the web, flanges and lips. 10 Profiled metal sections of the type described in the International applications can be formed with a conventional roll-forming apparatus by adding a channel shaped recess roll stage or stages. The length of the 15 roll-forming apparatus, as a result is increased only by a small amount. Preferably, step (b) occurs before the lips or return lips overlap the web. 20 Step (b) may occur prior to two or three final rolling stages of forming the flanges. The applicant recognises that the distortion of 25 the web by forming channel-shaped recesses is removed by performing one or more further rolling stages to finalise orientation of the flanges relative to the web. Specifically, the applicant recognises that web distortion produced by forming channel-shaped recesses comprises 30 curvature in the web profile and the curvature is correctable by changing the orientation of the flanges relative to the web. Accordingly, the applicant selects to change the orientation of the flanges to their final orientation relative to the web after the channel-shaped 35 recesses are formed. 5992775_1 (GHMatters) P76188.AU.1 LEANNE 26 Novernber 2014 - 6 Additionally, forming the channel-shaped recesses between initial and final rolling stages of forming the flanges enables a relatively simple channel-shaped recess forming step to be adopted. Specifically, when the flanges 5 are arranged in their final orientation and the flanges include lips and/or return lips, the lips and/or return lips overlap the web and, consequently, restrict access by rollers for forming the channel-shaped recesses. A complex roller arrangement is required to place channel-shaped 10 recesses in the web once the flanges and lips are formed in their final orientations. Accordingly, the conventional approach has been to form channel-shaped recesses at an initial stage of the roll-forming process. 15 The applicant has recognised, however, the benefits in forming channel-shaped recesses at the final stages of the roll-forming process, include being able to retain a relatively straightforward channel-shaped recess forming roller arrangement by forming channel-shaped 20 recesses prior to finalising the orientation of the flanges having lips and return lips, i.e. before the lips and return lips overlap with the web. Preferably, step (a) involves sequentially 25 forming the lips and the flanges. Preferably, step (a) includes forming the return lips before forming the lips. 30 Preferably, the or each channel-shaped recess has a depth which is equal to 0.5 to 5 times the thickness of the metal strip. Preferably, the steps of forming lips and 35 partially forming flanges each comprise 6 rolling stages. 5992775_1 (GHMatters) P76188.AU.1 LEANNE 26 Novernber 2014 - 7 Preferably, the rolling stages for forming lips and for partially forming flanges are spaced apart by 200 to 400mm and are more preferably spaced apart 200 to 300mm. 5 Preferably, the rolling stages for partially forming flanges are spaced apart 300 to 500mm and more preferably are spaced apart 400 to 500mm. 10 Step (b) preferably comprises 2 stages for forming channel-shaped recesses in the web disposed between partially formed flanges. Preferably, step (b) comprises 3 stages for 15 finalising orientation of the flanges relative to the web. Preferably, each of the channel-shaped recess forming stages and each of the flange-finalising forming stages respectively are spaced apart 300 to 500mm, and 20 more preferably 400 to 500mm. The invention also provides a profiled metal product formed by the method according to the invention. 25 The invention also provides an apparatus for cold forming a metal strip to include a central web, flanges extending outwardly from respective edges of the web, lips and return lips extending from free edges of the respective flanges and longitudinally extending channel 30 shaped recesses in the web, the apparatus comprising a series of rolling stages for the flanges and the channel shaped recesses, wherein the rolling stages for forming the channel-shaped recesses are intermediate the rolling stages for forming the flanges. 35 Preferably, the apparatus includes 6 or more rolling stages for forming the flanges. 5992775_1 (GHMatters) P76188.AU.1 LEANNE 26 Novernber 2014 - 8 Preferably, the rolling stages for forming the channel-shaped recesses are positioned upstream of 3 final rolling stages for forming the flanges. 5 Preferably, each of the channel-shaped recess forming rolling stages and each of the final flange forming rolling stages are respectively spaced apart 300 to 500mm, and more preferably 400 to 500mm. 10 Preferably, the apparatus includes rolling stages for forming lips. Preferably, the apparatus includes rolling stages 15 for forming return lips. Preferably, the apparatus includes 6 rolling stages for forming lips. 20 Preferably, the apparatus includes 6 rolling 5992775_1 (GHMatters) P76188.AU.1 LEANNE 26 Novernber 2014 -9 stages for forming return lips. Preferably, the rolling stages for forming channel-shaped recess and the rolling stages for forming 5 flanges are the final stages in the apparatus. Brief description of the drawings An embodiment of the invention will now be 10 described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cross-section of a profiled metal purlin formed from a metal strip in accordance with the 15 invention; Figure 2 is a flowchart of a roll-forming process for incorporating channel-shaped recesses in the profiled metal purlin in Figure 1 and shows the profile of the 20 purlin at various roll-forming stages; and Figure 3 is a flowchart of a roll forming process in accordance with the invention for forming the profiled metal purlin in Figure 1 and shows the profile of the 25 metal purlin at various roll-forming stages. Description of an embodiment An example of a profiled metal product, in the 30 form of a purlin 10, that may be formed in accordance with the invention is illustrated in Figure 1. The purlin 10 is formed of steel strip and comprises a web 12 with parallel flanges 14 extending from 35 respective edges of the web 12. Each flange 14 includes a lip 16 inclined at an angle of approximately 600 relative to the flange 14 and a return lip 18 formed at an angle of N,\Melbourne\Caaes\Patent\76000-76999\P76188.AU.1\Specia\P76188.AU.1 spec.doc 12/03/09 - 10 approximately 85* relative to the lip 16 and such that the return lip 18 is directed back toward the web 12. The web 12 incorporates four channel-shaped 5 recesses, in the form of knurls. However, it will be appreciated that the channel-shaped recesses 20 may take other forms or profiles, such as flutes and may comprise more or less numbers of recesses. 10 One method of forming purlins 10 is shown in Figure 2 as comprising 34 separate rolling stages in four groups 30, 32, 34 and 36. Although not shown, the roll forming process 15 commences with uncoiling of strip from a coil and passing the strip through a punch for forming holes for fasteners to link the formed purlin 10 with roof beams of a building. 20 The punched strip passes through a group 30 of four rolling stages for forming channel-shaped recesses 20 in the strip. In this method the metal strip is 3mm thick and four channel-shaped recesses 20 are formed in the strip to a depth of at least 1.5mm. The four channel 25 recess forming stages are each spaced apart by 300mm. The metal strip then passes to a group 32 of six rolling stages that form return lips 18 along edges of the metal strip. The six stages in the group 32 are spaced 30 apart by 350mm. The metal strip then passes to a group 34 of six rolling stages that form lips 16 in the metal strip. The six stages in group 34 are spaced apart by 350mm. 35 The final stages of forming the purlin 10 involves passing the metal strip through a group 36 of Nc\Melbourne\Casea\Patent\76000-76999\P76188.AU.1\Speci\P76188.AU.1 apec.doc 12/03/09 - 11 eighteen rolling stages for orienting the flanges 14 to extend at a right angle to the web 12. The eighteen rolling stages in group 36 are spaced apart by 350mm. 5 The formed purlin 10 then passes to a roll out table for collection and storage prior to transport to a construction site. The roll-forming method shown in Figure 2 10 involves forming the channel-shaped recesses 20 as part of the initial stage of roll-forming the purlin 10 because forming of the flanges 14 before the channel-shaped recesses 12 results in the lips 16 and return lips 18 projecting into a space that rollers need to occupy for 15 forming the channel-shaped recesses 20 However, forming the channel-shaped recesses 20 as part of an initial stage of forming the profiled purlin 10 results in stiffening of the metal strip such that roll 20 forming the return lips 18, lips 16 and flanges 14 requires greater rolling forces and greater driving forces to drive the metal strip through roll-forming groups 32, 34 and 36. As a result, the roll forming method in Figure 2 requires more maintenance and more stages to cold-form 25 the stiffened strip and requires 90kW electric motors to drive the metal strip. A roll forming method in accordance with the invention is illustrated in Figure 3 and comprises 23 30 roll-forming stages in total and in 5 groups. As with the roll-forming method described above in respect of Figure 2, metal strip is uncoiled and punched and delivered to an initial group 40 of six roll 35 forming stages for forming return lips 18. The roll forming stages in group 40 are each spaced apart by 250mm. N,\Melbourne\Casee\Patent\76000-76999\P76188.AU.1\Speci\P76188.AU.1 spec.doc 12/03/09 - 12 The metal strip then passes to a second group 42 comprising six roll-forming stages for forming lips 16. The roll-forming stages are spaced apart by 250mm. 5 The metal strip then passes to a group 44 of six roll-forming stages for partially forming flanges 14 to an extent that the lips 16 and return lips 18 do not overlap the web 12 and, therefore, do not interfere with access to 10 the web 12 in subsequent web 12 rolling stages. The metal strip then passes to a group 46 of two roll-forming stages for forming channel-shaped recesses 20. Each stage in group 46 is spaced apart by 490mm. 15 The metal strip then passes to a final group 48 of three roll-forming stages for finalising orientation of the flanges to a position at a right angle to the web 12. The three stages in group 48 are spaced apart by 490mm. 20 The applicant has discovered that distortion of the web 12 in roll-forming group 46 by introducing channel-shaped recesses 20 is removed by finalising orientation of the flanges 40 in the final three roll 25 forming stages in group 48. This is a significant advance over the method described above in respect of Figure 2 because only three stages are required to remove distortion whereas the method in Figure 2 involves a further 28 stages after forming channel-shaped recesses 30 20. Although spacing between roll-forming stages is dependent upon the size of rollers and tension in the strip between stages, the applicant surprisingly 35 discovered that roll-forming purlins 10 is easier when channel-shaped recesses are incorporated into the metal strip after forming return lips, lips and flanges, i.e. in N,\Melbourne\Cases\Patent\76000-76999\P76188.AU.1\Specio\P76188.AU.1 spec.doc 12/03/09 - 13 the final stages of roll forming. Increased stiffness of the metal strip as a result of introducing channel-shaped recesses 20 in 5 initial stages of roll forming, for example in the method shown in Figure 2, necessitates increased rolling forces throughout the remainder of the roll-forming process. Accordingly, more expensive machinery, stronger driving motors and additional rolling stages are required to 10 manipulate the stiffened metal strip. In contrast, the roll-forming process shown in Figure 3, for example, involves forming return lips 18, lips 16 and flanges 14 prior to stiffening the metal strip 15 with channel-shaped recesses 20. Although the roll forming method shown in Figure 3 is in respect of metal strip having a thickness of 2.4 mm, the roll-forming method uses 30kW drive motors, i.e. drive motors with a power rating that is one-third of the power-rating of 20 motors required for the roll-forming method in Figure 2. The roll-forming method in accordance with the invention can be performed on existing machinery by simply incorporating an additional stage or stages for forming 25 channel-shaped recesses 20. Accordingly, capital costs associated with roll-forming method in Figure 3 are significantly less than the capital costs associated with the roll forming method in Figure 2. 30 Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other country. 35 Many modifications may be made to the preferred embodiment of the present invention as described above N:\Melbourne\Cases\Patent\76000-76999\P76188.AU.1\Specis\P76188.AU.1 spec.doc 12/03/09 - 14 without departing from the spirit and scope of the present invention. It will be understood that the term "comprises" 5 or its grammatical variants as used in this specification and claims is equivalent to the term "includes" and is not to be taken as excluding the presence of other features or elements. N3\Melbourne\Casee\Patent\76000-76999\P76188.AU.1\Specia\P76188.AU.1 apec.doc 12/03/09

Claims (20)

1. A method of forming a profiled metal section by 5 cold forming a metal strip to include a central web, flanges extending outwardly from respective edges of the web, lips and return lips extending from free edges of the respective flanges and longitudinally extending channel shaped recesses in the web, the method comprising the 10 steps of: (a) passing the strip of metal through a series of rolling stages to form a web with outwardly extending flanges, lips and 15 return lips; and (b) passing the formed strip through one or more rolling stages for forming one or more channel-shaped recesses in the web; and 20 wherein the flanges are formed in a series of rolling stages in which the angle of the flange relative to the web is increased incrementally until the flanges reach a final orientation relative to the web and step (b) occurs 25 after partially forming the flanges and prior to one or more final rolling stages in the series of rolling stages for forming the flanges.

2. A method as defined in claim 1, wherein step (b) 30 occurs before the lips or return lips overlap the web.

3. A method as defined in claim 1 or claim 2, wherein step (b) occurs prior to two or three final rolling stages of forming the flanges. 35 3. A method as defined in any one of the preceding claims, wherein step (a) involves sequentially forming the 5992775_1 (GHMatters) P76188.AU.1 LEANNE 26 Novernber 2014 - 16 lips and the flanges.

4. A method as defined in any one of the preceding claims, wherein step (a) includes forming the return lips 5 before forming the lips.

5. A method as defined in any one of the preceding claims, wherein the or each channel-shaped recess has a depth which is equal to 0.5 to 5 times the thickness of 10 the metal strip.

6. A method as defined in any one of the preceding claims, wherein the steps of forming lips and of partially forming flanges each comprise 6 rolling stages. 15

7. A method as defined in any one of the preceding claims, wherein the rolling stages are spaced apart by 200 to 400mm. 20

8. A method as defined in claim 13, wherein the rolling stages are spaced apart by 200 to 300mm.

9. A method as defined in any one of the preceding claims, wherein the rolling stages for partially forming 25 flanges and/or forming channel-shaped recesses and the flange-finalising stages are spaced apart 300 to 500mm.

10. A method as defined in any one of the preceding claims, wherein the rolling stages for partially forming 30 flanges and/or forming channel-shaped recesses and the flange-finalising stages are spaced apart 400 to 500mm.

11. A method as defined in any one of the preceding claims, wherein the method comprises 3 stages for 35 finalising orientation of the flanges relative to the web.

12. A profiled metal product formed by a method 5992775_1 (GHMatters) P76188.AU.1 LEANNE 26 Novernber 2014 - 17 according to any one of the preceding claims.

13. An apparatus for cold forming a metal strip to include a central web, flanges extending outwardly from 5 respective edges of the web, lips and return lips extending from free edges of the respective flanges and one or more longitudinally extending channel-shaped recesses in the web, the apparatus comprising a series of rolling stages for forming the flanges and one or more 10 rolling stages for forming the channel-shaped recesses, wherein the rolling stages for forming the channel-shaped recesses are intermediate the rolling stages for forming the flanges. 15

14. An apparatus as defined in claim 13, wherein the apparatus includes 6 or more rolling stages for forming the flanges.

15. An apparatus as defined in claim 14, wherein the 20 rolling stages for forming the channel-shaped recesses are positioned upstream of 3 final rolling stages for forming the flanges.

16. An apparatus as defined in claim 15, wherein 25 each of the channel-shaped recess-forming rolling stages and each of the final flange-forming rolling stages are respectively spaced apart 300 to 500mm.

17. An apparatus as defined in claim 16, wherein 30 each of the channel-shaped recess-forming rolling stages and each of the final flange-forming rolling stages are respectively spaced apart 400 to 500mm.

18. An apparatus as defined in any one of claims 13 35 to 17, wherein the apparatus includes 6 rolling stages for forming the lips. 5992775_1 (GHMatters) P76188.AU.1 LEANNE 26 Novernber 2014 - 18

19. An apparatus as defined in any one of claims 13 to 18, wherein the apparatus includes 6 rolling stages for forming the return lips. 5

20. An apparatus as defined in any one of claims 13 to 19, wherein the rolling stages for forming channel shaped recess and the rolling stages for forming flanges are the final stages in the apparatus. 10 5992775_1 (GHMatters) P76188.AU.1 LEANNE 26 Novernber 2014