| 摘要 |
PURPOSE:To decrease the frequencies when a star pattern arises in the press forming stage by specifying the range of surface roughness by using a method for roughening the surface of an Al sheet material by rolling rolls to improve press forming. CONSTITUTION:The surface roughness of the Al or Al alloy sheet is so adjusted that the length l measured in the directions at least parallel with the rolling direction and perpendicular thereto is 25.4mm, the max. peak-to-valley height Rmax (height of the highest peak M0) is >=3mu and the number of the peaks M having >=2mu height is >=15 pieces at the length l. The frequencies when the star pattern arises can be thereby decreased and the outlook of the Al and Al alloy sheets applied to the conspicuous part such as the exterior panel of an automobile is improved.
|
