Cold rolled strips are widely employed in automobiles, home appliances and other industries, and their surface micromorphology affects the surface chromatic aberration of the strip steel. The strip steel surface with regularly distributed microstructure tends to exhibit alternative bright and dark fringes. When the microstructure is randomly distributed, the stripes caused by multi-beam interference will be weakened. The surface microstructure of the rolled strip corresponds to that of the roll surface. The disordered roll laser texturing technology features less pollution, a wide range of texturing roughness, and high surface hardness, which can reduce the surface chromatic aberration of the rolled strip and is expected to meet the growing demand for sound stamping performance and fine brightness after the painting of cold rolled sheet productions.

The laser texturing roller technology is presented for controlling the range of peak per inch (PPI) density and roughness of rolling rolls based on the offset phase difference of the random distribution. The formation mechanism of light and dark alternately stripes on the surface of rolled strip steel is analyzed using the multi-beam interference principle. By the ray tracing method, the random distribution phase difference generated by the offset of equally spaced convex microstructures is studied to weaken the interference fringes formed by single-wavelength reflected light on the surface of rolled strip steel, which thus eliminates Moiré fringes generated by multiple wavelengths. The reflected coherent irradiance is adopted to study the corresponding uniform distribution function characteristic parameters under different center spacing when the interference fringes are broken. Meanwhile, laser impact pit experiments are conducted on roll material samples to obtain the corresponding relationship between the textured pit morphology and laser impact conditions. The random deviation of the pit microstructure on the roll surface is the same as that of the convex microstructure on the rolling strip by attenuating“copying”. We utilize Matlab's pseudo-random number generator based on the linear congruence method to generate two sets of random arrays that obey the uniform distribution obtained from the simulation analysis. Disordered texturing is performed on the rolling roll material sample by laser impact, which is achieved by adopting deviation in the convex microstructure center distance following a uniform distribution by theoretical and simulation analysis.

When the center offset of the microstructure on the surface of the rolled strip steel obeys a uniform distribution function, the coherent irradiance disorder of the single wavelength reflected light of the microstructure is better (Fig. 2). When the interference fringes of the reflected light from the tabular microstructure are broken, different center spacing corresponds to various characteristic parameters of the uniform distribution function (Fig. 3).

By employing the uniform distribution function of pit center offset obtained from theoretical and simulation analysis, and the relationship between experimentally obtained laser parameters and pit morphology, the surface of a roll material sample with a roughness of 3.79 μm and PPI of 179 is experimentally realized as disordered laser texturing of the roll material sample in a small area of 10 mm×10 mm by laser texturing technology (Fig. 5).