| 摘要 |
The board has four edges designed as a combination of asymmetrical stage creases and a tapered with an asymmetrical groove spring. The thickness amounts to the 25 to 40 per cent of the entire slab thickness. An asymmetrical groove is between 75 to 60 per cent of the entire slab thickness. The groove has a depth of between 25 to 35 % of the depth of the crease. |
