IE71919B1 - Method and apparatus for forming sheet metal - Google Patents

Abstract

An apparatus for manufacturing profiled sheet metal comprising a plurality of progressive passes for forming flat sheet metal into sinusoidal or corrugated profiled sheet material, each pass comprising an upper and lower roller, each roller having the desired profile provided thereon so that as the sheet is progressively formed through each pass, the required profile is formed at each pass and is replicated from the first pass to the final pass.

Description

METHOD AND APPARATUS FOR FORMING SHEET METAL The present invention relates to a method of and apparatus for manufacturing profiled sheet metal, particularly sheet steel having a sinusoidal profile, known also as corrugated sheeting. This sheeting is generally used for roofing material and can be used in flat roofs, sloped roofs or curved roofs, where the sheeting is curved about its transverse axis.

The standard period of a sinusoidal profile is 76.2mm or 3 inches, although this period can be different in different circumstances. Corrugated sheeting is specified with reference to the number of corrugations on a sheet and the standard period of the corrugation. Thus, an 8/3 sheet has 8 corrugations with a period of 3 inches. Likewise, 10/3 and 14/3 sheeting have 10 and 14 corrugations respectively at the same period.

In order to produce these corrugations, an elongate strip of sheet metal is passed through a series of rollers, each pass having an upper roller and a lower roller. In the prior art apparatus, the profile is formed initially with a single corrugation along the centre line of the sheet by a roller, and the other corrugations are progressively formed by sequentially passing the sheet through a series of rollers, each series being known as a pass. In the prior art apparatus, the corrugations are formed by a plurality of rings spaced along each roller at the desired period for the corrugations. Each roller has a semi-circular profile. The rings at the bottom and top rollers are offset with respect of one another, so that the corrugations approximate to a series of semi-circular formations joined by lines at an angle before the sheet is put through the final pass, where the rollers have the - 2 71 91 9 profile of the desired finished sinusoidal profile of the sheeting.

In the prior art apparatus as shown in Figure A, the initial passes consisted of rings of reduced diameter (initially 145 mm (5.7)) combined with spacers of greater width (initially 47 mm (1.83)). The diameter of the rings is increased with each pass while the corresponding spacer width is reduced (i.e. 147 mm (5.8) ring combined with 45 mm (1.79) spacer; 150 mm (5.9) ring with 44 mm (1.745) spacer; 152 mm (6.0) ring with 43 mm (1.705) spacer and then with 43 mm (1.685) spacer; 155 mm (6.1) ring with 42 mm (1.665) spacer; 157 mm (6.2) ring with 41 mm (1.625) spacer and then with 40 mm (1.580) spacer and then with 39 mm (1.540) spacer; finally 160 mm (6.3) ring with 38 mm (1.50) spacer).

The initial six corrugations are formed over the first five passes in this manner. The next three corrugations on either side of these are then formed on the following five passes with the first pass being used as an infeed guide and the twelfth being used as an edge corrugation pass.

The capacity of the machine in the prior art apparatus is therefore 12 corrugations including the cover laps giving a maximum of a 10/3 (10 number 3 corrugations of cover width) over the length of the machine.

The problems associated with the prior art method and apparatus is a low width tolerance of the sheeting which is in the order of +/- 8mm over 10 corrugations and a depth profile tolerance of +/- 1mm. As a result of this tolerance, the curving characteristics of the finished sheeting are quite poor. The material is curved by passing the sheet material through an arrangement of profiled rollers to form the curve about the transverse axis of the sheet. To compensate for this problem, the sheeting is manufactured from metal with a low yield stress to allow easy profiling of the material. However, the low yield stress creates problems for customers when erecting buildings as the softer material dents more readily during the erection process.

The object of the invention is to alleviate the above disadvantages of the prior art.

Accordingly, the invention provides an apparatus for manufacturing profiled sheet metal comprising a plurality of progressive passes for forming flat sheet metal into sinusoidal or corrugated profiled sheet material, each pass comprising an upper and lower roller, each roller having the sinusoidal or corrugated profile provided thereon so that as the sheet is progressively formed through each pass, the sinusoidal or corrugated profile is formed at each pass and is replicated from the first pass to the final pass.

Conveniently, each pass includes means for applying a half corrugation to each side of the formed corrugation at each pass, so as to reduce stress being introduced in the sheet metal at the subsequent pass.

Conveniently, the apparatus includes a non-sinusoidal tapered profiled outer tool operable to be applied to the outside of the sheet metal at each pass to curve it slightly and present it correctly orientated for the subsequent pass, thus preventinq buckling which would occur if the material were presented flat to the full form rollers Conveniently, intermediate the first pass and the final pass, at least one series of underbend pass rollers are located along the path so as to attempt to flatten the material and reduce any tendency for spring back in the material after the final formation of the corrugations.

The invention also provides a method of manufacturing profiled sheet metal comprising progressively forming flat sheet metal into sinusoidal or corrugated profiled sheet material through a plurality of passes, each pass comprising an upper and lower roller, with each roller having the sinusoidal or corrugated profile provided thereon, so that as the sheet is progressively formed through each pass, the sinusoidal or corrugated profile is formed at each pass and is replicated from the first pass to the final pass.

Conveniently, the method includes applying a half corrugation to each side of the formed corrugation at each pass, so as to reduce stress being introduced in the material at subsequent pass.

Preferably, the method also includes applying a non-sinusoidal profiled outer tool to the outside of the material at each pass so as to curve the material slightly and present it correctly orientated for the subsequent pass.

Advantageously, the method further includes underbending the progressively formed profile prior to final forming of the sheet so as to attempt to flatten the material and reduce any tendency for spring back in the material after the formation of the corrugations.

The invention will hereinafter be more particularly described with reference to the accompanying drawings which show, by way of example only, one set of rollers of a prior art apparatus, an embodiment of the apparatus according to the invention and examples of sheeting produced on the apparatus.

In the drawings :Figure A is a side view of the top and bottom rollers of the prior art apparatus; Figure 1 is a series of 16 side views showing the progressive development of the tooling for each pass; Figure 2 is a view on a larger scale of the rollers at pass 13 and pass 14 as shown in Figure 1; and Figures 3a, 3b and 3c are end views respectively of 8/3, 10/3 and 14/3 of sinusoidal profile sheeting.

In order to use higher grade material with a higher yield stress and tensile strength so as to produce a more durable product it is important to have a manufacturing process which holds the profile in place for each corrugation while the next is being formed. However, the difficulty of using a higher tensile strength material is that it has greater spring back, i.e. it tends to revert back to its flat shape.

Referring now to the drawings and initially to Figure 1, the rolling operation commences at Op 1 and is finished at Op 16. Each pass consists of a top roller 20 and a bottom roller 22 on which are located sinusoidal profile forming tools. At Op 1 can be seen forming tool 31 on the top roller 20 and two forming tools 32 on the bottom roll 22.

The apex of the tool 31 coincides with the valley formed between the forming tools 32 so that between them they can form one corrugation and two half corrugations. At the ends of each roller 20 and 22 are guides 40 and 42 which can be arranged to centre the sheet metal as it passes through Op 1 so that the first corrugation is formed along the centre line of the sheet.

The sheet then progresses to Op 2 which is the second pass, on the rollers 20, 22 of which are again one forming tool 31 and two forming tools 32, 22 respectively. At each side of the forming tool 31 is an outer tool 50, of non-sinusoidal profile, which curves the material slightly and presents it correctly orientated for the next pass Op 3. The non-sinusoidal forming tools 50 are on the lower roller 22. At each subsequent pass from Op 3 to Op 14, the tools 50 are alternatively on the bottom and top rollers. At Op 3, there are three forming tools 31 on the top roller 20 and two forming tools 32 on the bottom roller 22. There are no non-sinus rollers on the first and last passes - OP1 and OP16. The number of tools is progressively added to at each pass until the final pass at Op 16. Using the embodiment of the invention which is 16 pass roll forming line, it is possible to form a 14/3 profile corrugated sheet metal which according to conventional roll forming techniques would not be possible. The invention uses a gentle method of turning the material to orientate it correctly to the next pass.

In this way buckling in the material is avoided while doing more work per pass than normal.

As explained previously, the use of higher tensile material presents the problem of increased spring-back which means the finished profile expands to form a wider sheet outside tolerance. To overcome this problem, the roll forming pass at Op 14 produces an underbend pass.

The forming tools 35 on the upper roll 20 and the forming tool 32 on the bottom roll 22 of Op 14 are of a smaller diameter than the tools used on the other passes. Shims 60 are placed between each tool 35 and each tool 36 so as to increase the distance between the tools 35 and 36.

Thus, in this particular example, the material is formed with an 18mm deep profile rather than the 19mm profile of the other passes, with a 77.2mm period rather than the standard 76.2mm period. After passing through Op 14, the material goes through two further passes at the standard profile through Op 15 and Op 16 which brings the material back to the finished 19mm deep and 76.2 period profile.

By passing the material through the underbend pass, the material has been cold worked to reduce stresses in the profile and thus does not spring back when removed from the apparatus.

Using the apparatus and method of the invention, it is thus possible to use considerably higher tensile grades of sheet metal than hitherto, thereby giving an increased load bearing capacity for the finished product over the softer material used in the prior art. Using the invention, it is possible to get very high tolerances, particularly +/- 2mm on cover width over 10 corrugations and +/- 0.25mm on the depth of the corrugations.

It will of course be understood that the invention is not limited to the specific details described herein, which ar given by way of example only, and that various modifications and alterations are possible within the scop of the invention as defined in the appended claims.

Claims (11)

1. An apparatus for manufacturing profiled sheet metal comprising a plurality of progressive passes for forming flat sheet metal into sinusoidal or corrugated profiled sheet material, each pass comprising an upper and lower roller, each roller having the sinusoidal or corrugated profile provided thereon so that as the sheet is progressively formed through each pass, the sinusoidal or corrugated profile is formed at each pass and is replicated from the first pass to the final pass.

2. An apparatus according to Claim 1, wherein each pass includes means for applying a half corrugation to each side of the formed corrugation at each pass, so as to reduce stress being introduced in the sheet metal at a subsequent pass.

3. An apparatus according to Claim 1 or Claim 2, including a non-sinusoidal tapered profiled outer tool operable to be applied to the outside of the sheet metal at each pass so as to curve the material slightly and present it correctly orientated for the subsequent pass, thus preventing buckling which would occur if the material were presented flat to the full form rollers.

4. An apparatus according to any one of the preceding claims, wherein intermediate the first pass and the final pass, at least one series of underbend pass rollers are located along the path so as to attempt to flatten the material and reduce any tendency for spring back in the material after the formation of the corrugations.

5. A method of manufacturing profiled sheet metal comprising progressively forming flat sheet metal into sinusoidal or corrugated profiled sheet material through a plurality of passes, each pass comprising an upper and lower roller, with each roller having the sinusoidal or corrugated profile provided thereon, so that as the sheet is progressively formed through each pass, the sinusoidal or corrugated profile is formed at each pass and is replicated from the first pass to the final pass.

6. A method according to Claim 5, including applying a half corrugation to each side of the formed corrugation at each pass, so as to reduce stress being introduced in the material at subseguent pass.

7. A method according to Claim 5 or Claim 6, including applying a non-sinusoidal profiled outer tool to the outside of the material at each pass so as to curve the material slightly and present it correctly orientated for the subsequent pass.

8. A method according to any one of Claims 5 to 7, including underbending the progressively formed profile prior to final forming of the sheet so as to attempt to flatten the material and reduce any tendency for spring back in the material after the formation of the corrugations.

9. Apparatus for manufacturing a profiled sheet material, substantially as herein described with reference to and as shown in Figures 1 and 2 of the accompanying drawings.

10. A method of manufacturing a profiled sheet material, substantially as herein described with reference to and as shown in Figures 1 and 2 of the accompanying drawings.

11. Profiled sheet material whenever manufactured by an apparatus as claimed in Claims 1 to 4 and 9 or by a method as claimed in any one of Claims 5 to 8 and 10.