| 摘要 |
Sheet metal is passed between a pair of cold forming rolls which form a plurality of projections at one face of the sheet. These projections stiffen the sheet. One roll has a plurality of rows of teeth (4, 5, 6) and the other roll has a number of mating formations (10, 11, 12) each having a length equal to the length of a row of teeth. As viewed along the axes of the rolls, the teeth and the formations have a profile which includes two involute curves. |
