| 摘要 |
PURPOSE:To improve the image clarity of coated film of steel sheet by making power spectrum value in a specified region where is set on a frequency analysis curve that is obtained by Fourier transforming the profile curve of the surface of pretreatment steel sheet for painting below a specified value. CONSTITUTION:In the pretreatment steel sheet for painting which isn't corrected even with press forming and which has rugged zone in the wavelength region where the image clarity of coated film is checked on the surface, the wavelength region where the image clarity of coated film is checked is set in the range of 1.0-6.0mm wavelength of the frequency analysis curve that is obtained by Fourier transforming the profile curve of the surface of steel sheet. The sum of power spectrum in this wavelength region is taken <=0.5. In this way, because DOI value after painting can be made to raise, e.g. >=90, the image clarity of coated film of pretreatment steel sheet for painting can be improved. |
