Modified Least Square Reference Line for Surface Roughness Evaluation

The least square reference line for surface roughness evaluation in GB/T 3505—2000 is a broken line with discontinuity points between two evaluation lengths.The least square reference line is modified.A smooth reference line for surface roughness evaluation is obtained by sliding and averaging the least square mean lines in the evaluation length.Through the sample and simulation analysis,the modified least square method can represent the slow-motion and continuous curves.The modified least square reference line is well consistent with ISO Gauss reference line and their evaluation results for surface roughness are the same.The advantages of the modified least square reference line,simple to calculate and practicable,is inherited from the least square reference line in use with small changes.Moreover,the evaluation reference is smooth and continuous without losing primary data in processing,and the discontinuity of the least square reference line in use is eliminated.