| 摘要 |
The invention concerns a device for producing at least a weakening groove in a sheet material, using at least a rotating biconical knurl (1). Said device is characterised in that the knurl has two truncated parts (2, 3) extending on either side of a large common base (X) located in a plane orthogonal to its axis of rotation, the angles ( alpha ) and ( beta ) formed by the generatrices (AB) and (AD) of said respective truncated parts (2, 3) with the large base (X) being different. The invention also concerns the grooved sheets and the sheet elements obtained by said device. |
