Abstract: A corrugated sheet has a bend formed by one or more straight lines of impressions extending transversely across the corrugation valleys upwardly into the valleys and adjacent portions of the side walls between the valleys and the corrugation crests, and at the ends of the impressions the side walls have indents extending outwardly away from the impressions. The number of indents and impressions depends on the extent of the bend.

Abstract: The invention relates to a method and a device for bending sheet-metal sections. It is previously known to bend sectional sheets, but the known art involves certain problems to bring about a non-angular bend with a small radius and without damaging the sheet. According to the invention it is proposed for eliminating said problems, that in connection with the impressing of the sheet portions located closest to the bending axis the lateral portions (1c; 32c; 50c) of the sheet are subjected to an outwardly directed force (17; 39; 56) or prestressing in a plane through the impressions (34; 59), in order to form an outward bulging (40; 58) in the lateral portions (1c; 32c; 50c) and on the same side of the sheet as the impressions (34, 59).

Abstract: A corrugated metal sheet is incrementally bent perpendicularly with respect to its corrugations, by repeatedly transversely indenting upwardly the bottoms of the corrugation valleys so that the indentations extend in lines transversely across the sheet and extend into the corrugation sides which interconnect the valleys and ridges of the sheet. Each line of indentation causes the sheet to bend to some degree without detrimental stretching or drawing of the sheet.

Abstract: A corrugated metal sheet is incrementally bent perpendicularly with respect to its corrugations, by repeatedly transversely indenting upwardly the bottoms of the corrugation valleys so that the indentations extend in lines transversely across the sheet and extend into the corrugation sides which interconnect the valleys and ridges of the sheet. Each line of indentation causes the sheet to bend to some degree without detrimental stretching or drawing of the sheet.

Abstract: A corrugated roofing sheet has special elevations formed in the wave crest of the sheet, the elevations being contoured to increase the sheet's rigidity while permitting the elevations to function as a ladder. The elevations provide effective rigidfying while leaving the valleys of the sheet corrugations free for drainage.