GB2101507A - Method and apparatus for bending corrugated sheet - Google Patents

Abstract

Apparatus for bending corrugated sheet transversely of the corrugations thereof comprises a fixed bottom tool 17 including a plurality of upwardly projecting elements 18 spaced apart across the width of the apparatus so that, in use, an element projects into each valley on the underside of a corrugated sheet 20 disposed over the tool with said corrugations extending transversely of the tool, each element 18 extending across a major part of each valley and being formed in its upper face with a channel 21 extending across the valley, the channels in all the elements being in line, and a single elongate top tool 22 extending across the width of the apparatus and having a continuous lower edge disposed vertically above and in line with said channel 21, and means for moving the top tool vertically up and down so that it may be moved downwardly to introduce said continuous lower edge thereof at least partly into the channels in the bottom element. The top tool 22 may be the conventional top tool of a normal press brake whereas the bottom tool is a simple replacement for the conventional bottom tool of such a machine. <IMAGE>

Description

SPECIFICATION Method and apparatus for bending corrugated sheet The invention relates to a method and apparatus for bending corrugated sheet and particularly corrugated sheet of the kind used in buildings and roofing and manufactured from precoated steel, galvanised steel, or painted or mill-finish aluminium.

The corrugations of such sheet may be of any suitable cross-sectional shape, a trapezoidal cross-section to the corrugations often being employed.

There are many circumstances where it is desirable to be able to bend corrugated sheet perpendicularly to the longitudinal direction of the corrugations. There have therefore been devised for this purpose fairly complex bending machines which impart a curvature to the corrugated sheet by forming a succession of closely spaced parallel bends transversely of the corrugations. However, such bending machines are complex and expensive and normally involve engaging the sheet between tools which, as well as being relatively reciprocating, are also indexed about the axis of the curvature as the successive bends are formed.

There are certain situations, however, where it is not required to put a substantially continuous curvature into the corrugated sheet and where the required shape may be obtained by forming a single bend, or perhaps only two or three spaced bends. The present invention therefore provides a method and apparatus for bending corrugated sheet which allows the sheet to be bent by using a conventional mechanical or hydraulic press brake or similar bending machine of the type which is commonly available in sheet metal fabricating works, so that the necessity of investing in an elaborate and specially designed bending machine is avoided.

According to the invention, there is provided apparatus for bending corrugated sheet transversely of the corrugations thereof comprising a fixed bottom tool including a plurality of upwardly projecting elements spaced apart across the width of the apparatus so that, in use, an element projects into each valley on the underside of a corrugated sheet disposed over the tool with said corrugations extending transversely of the tool, each element extending across a major part of each valley and being formed in its upper face with a channel extending across the valley, the channels in all the elements being in line, and a single elongate top tool extending across the width of the apparatus and having a continuous lower edge disposed vertically above and in line with said channel, and means for moving the top tool vertically up and down so that it may be moved downwardly to introduce said continuous lower edge thereof at least partly into the channels in the bottom element.

Thus, the top tool may be the conventional top tool of a normal press brake whereas the bottom tool, being fixed, is a simple-to-construct shaped replacement for the conventional bottom tool of such a machine.

The elements in the bottom tool may comprise separate segments spaced apart across the width of the apparatus, and the elements may be rectangular in configuration.

The lower edge of the top tool may be Vshaped in cross-section. Alternatively, the lower edge may be rounded. For example, the edge may be provided by a bead of generally circular crosssection formed on the lower edge of a generally plate-like element.

The channels in the aforesaid elements on the bottom tool may be rectangular in cross-section.

The invention also provides a method of bending corrugated sheet transversely of the corrugations thereof, comprising locating the sheet over a fixed bottom tool including a plurality of upwardly projecting elements spaced apart across the width of the sheet so that an element projects into each valley on the underside of the sheet, each element extending across a major part of each valley and being formed in its upper face with a channel extending across the valley, the channels in all the elements being in line, and moving downwardly into pressing engagement with the upper surface of the sheet the continuous lower edge of a single elongate top tool which extends across the width of the sheet with said lower edge vertically above and in line with said channels in the bottom tool, the downward movement of the top tool deforming portions of the crests of the corrugations downwardly into the channels in the bottom tool and thus forming a bend acrss the width of the sheet.

The method may comprise the further step of displacing the corrugated sheet longitudinally with respect to the tools, after forming said bend, and repeating operation of the tools to form a second bend, or further bends, across the sheet and generally parallel to the first said bend.

The invention also includes within its scope a corrugated sheet when bent by the apparatus or method referred to above.

The following is a more detailed description of embodiments of the invention, reference being made to the accompanying drawings in which: Figure 1 is a perspective view, partly broken away, of a piece of trapezoidal corrugated sheet bent to form a roofing ridge piece, Figure 2 is a diagrammatic view showing the tools of bending apparatus according to the invention, for forming the ridge piece of Figure 1, Figure 3 is a vertical section through the tools of Figure 2, Figure 4 is a vertical section through an alternative form of top tool, and Figure 5 shows the apparatus of Figures 2 and 3 in operation in bending a corrugated sheet.

Referring to Figure 1, the roof ridge piece 10 is designed to fit over the apex of a pitched roof formed mainly from generally planar sheets of trapezoidal section corrugated steel, the corrugations extending downwardly from the apex. The ridge piece is formed with a number of spaced bends extending transversely of the corrugations, two such bends 11 and 12 being shown in Figure 1. Each bend preferably bends the sheet through approximately 100 and thus where the apex angle of the roof is 1 500 three such bends will be required, the middle bend 12 being disposed at the highest point of the pitch roof.

Each bend is formed by deforming transverse ridges 13 across the bottom of each valley 14 of the corrugated sheet. The ends of the ridges 13 extend partly into the side walls 1 5 of the valleys and the ends of the ridges are surrounded by indentations 16 in the side walls 15, the indentations 16 being concave as viewed in Figure 1.

As previously mentioned, corrugated metal sheeting has hitherto been curved by forming a plurality of closely spaced parallel bends across the corrugations so as to give, as far as possible, the effect of a continuous curve. In the ridge piece shown in Figure 1, however, the bends are widely spaced and only a few bends are required, depending on the pitch angle of the roof. The present invention allows conventional sheet metal bending apparatus to be modified for the bending of corrugated sheet, rather than requiring specially designed bending apparatus of the kind used hitherto.

The modified form of the sheet metal bending apparatus is shown diagrammatically in Figures 2 and 3.

The apparatus comprises a bottom tool 17 which includes a number of upwardly projecting rectangular elements 18 spaced apart across the width of the apparatus. The width of each element 18, as viewed in Figure 2, is equal to or less than the spacing between adjacent corrugations 19 of the corrugated sheet 20, so that the corrugated sheet may rest on the elements 18 with the corrugations projecting downwardly into the spaces between adjacent elements.

As shown in Figure 3, each element 18 is formed in its upper face with a rectangular channel 21, the channels of all the elements 18 being in line across the width of the apparatus.

Disposed vertically above the channel 21 is a top tool 22 which, in the arrangement of Figure 3, has a lower edge 23 which is V-shaped in crosssection.

In operation, the corrugated sheet is placed over the bottom tool 17 as shown in Figure 2 and the top tool 22 is then forced downwardly, hydraulically or mechanically, into engagement with the sheet as shown in Figure 5. The crests 24 between adjacent corrugations are accordingly deformed downwardly into the channels 21, as shown in Figure 5, forming the ridges 13, the indentations 16 being formed automatically at the same time in the side walls of the corrugations.

The formation of the ridges 1 3 imparts a transverse bend to the sheet which, as previously mentioned, may be approximately 100. If one or more further bends are required, the sheet 20 is displaced longitudinally with respect to the tools, after the top tool 21 has been withdrawn, and the operation is repeated to form a further bend parallel to the first said bend.

It will be appreciated that the cross-sectional shape of each ridge 13 will depend to a large extent on the shape of the top tool 22, and Figure 4 shows an alternative form of top tool 25 where the lower edge of the tool is provided by a bead of generally circular cross-section formed on the lower edge of a generally plate-like element.

Although the invention is particularly applicable to forming ridge pieces for pitched roofs, it will be appreciated that the method and apparatus according to the invention may be used for forming any building component from corrugated sheet where bending of the sheet through a small angle is required.

Claims (10)

1. Apparatus for bending corrugated sheet transversely of the corrugations thereof comprising a fixed bottom tool including a plurality of upwardly projecting elements spaced apart across the width of the apparatus so that, in use, an element projects into each valley on the underside of a corrugated sheet disposed over the tool with said corrugations extending transversely of the tool, each element extending across a major part of each valley and being formed in its upper face with a channel extending across the valley, the channels in all the elements being in line, and a single elongate top tool extending across the width of the apparatus and having a continuous lower edge disposed vertically above and in line with said channel, and means for moving the top tool vertically up and down so that it may be moved downwardly to introduce said continuous lower edge thereof at least partly into the channels in the bottom element.

2. Apparatus according to claim 1 , wherein the elements in the bottom tool comprise separate segments spaced apart across the width of the apparatus.

3. Apparatus according to claim 1 or claim 2, wherein the elements are rectangular in configuration.

4. Apparatus according to any of claims 1 to 3, wherein the lower edge of the top tool is V-shaped in cross-section.

5. Apparatus according to any of claims 1 to 4, wherein the channels in the aforesaid elements on the bottom tool are rectangular in cross-section.

6. Apparatus for bending corrugated sheet substantially as hereinbefore described with reference to the accompanying drawings.

7. A method of bending corrugated sheet transversely of the corrugations thereof, comprising locating the sheet over a fixed bottom tool including a plurality of upwardly projecting elements spaced apart across the width of the sheet so that an element projects into each valley on the underside of the sheet, each element extending across a major part of each valley and being formed in its upper face with a channel extending across the valley, the channel in all the elements being in line, and moving downwardly into pressing engagement with the upper surface of the sheet the continuous lower edge of a single elongate top tool which extends across the width of the sheet with said lower edge vertically above and in line with said channels in the bottom tool, the downward movement of the top tool deforming portions of the crests of the corrugations downwardly into the channels in the bottom tool and thus forming a bend across the width of the sheet.

8. A method according to claim 7, comprising the further step of displacing the corrugated sheet Jongitudinally with respect to the tools, after forming said bend, and repeating operation of the tools to form a second bend, or further bends, across the sheet and generally parallel to the first said bend.

9. A method of bending corrugated sheet substantially as hereinbefore described with reference to the accompanying drawings.

10. Corrugated sheet when bent by the apparatus or method according to any of the preceding claims.