Surface Roughness Measurement Technique Study Of Cold-Rolling Process

We researched the contactless and on-line measurement of the cold-rolling process in this paper. The conventional technique for the measurement of surface roughness is the stylus method that can't measure on-line. Therefore, contactless measurement technique is necessary for measuring moving objects. We derived the measurement from Beckmann's theory about the scattering of light on the rough surface and developed an optical instrument for the simultaneous measurement of the average surface roughness (Ra) and the number of peaks per inch (PPI). The instrument made use of the modern technology of laser, computer and the theory of statistics. Detectors received the intensity of light. Then it was converted and input computer. The computer showed the result. The measurement range depended on the incident angle and the wavelength of the laser used, and these were verified with the experiment. Parameters of the surface roughness measured by optical method are the same as the values measured by conventional stylus method, so it proved the optical measurement was reliable. Because the measurement is contactless and short data-processing time, the instrument has a wide application prospect.