| 摘要 |
A method of and apparatus for manufacturing a roofing of sheet metal, where a sheet in a first step is preformed so as by a first operation perpendicular to its surface extension, the sheet is provided with a contour of wave-shape and in a second step, is provided with step-shaped jags of a predetermined step height by means of a pressing tool, which comprises at least one first and one second pair of tools movable to and from each other, the preformed sheet being held down by each tool pair, whereafter the tool pairs are moved relative to each other through a distance corresponding to the step height, so that the sheet by the second operation which is in a direction perpendicular to the surface extension of the sheet and to said first cut is provided with a step-shaped portion across the wave-shaped sheet, whereafter as a third operational step, the preformed sheet is advanced through a predetermined adjusted distance, and thereafter the second operational step is repeated to make a next step in the sheet. The second tool pair, at the discharge end of the pressing tool, has a clamping force sufficient to prevent sliding movement between the sheet and the second tool pair. The first tool pair, at the feed end of the pressing tool, holds down the sheet with a lower clamping force so adjusted that sliding movement between the sheet and the tool surfaces of the first pair takes place when a tensile stress has been attained in the sheet by the relative movement of the tool pairs which is higher than the yield strength of the sheet. |
