表面粗糙度的非相干光三角法测量研究

Research on Surface Roughness Measurement Using Incoherent Light Triangulation Method

激光三角法因其非接触、结构简单和工作距离大等优点在粗糙度测量中的应用越来越多,但激光测量易受散斑噪声影响,无法实现高精度的测量。对此提出一种非相干光三角法,采用非相干线光作为测量光源,避免了散斑噪声影响。搭建一套测量表面粗糙度的非相干光三角法系统,通过对比非相干光条纹图与激光条纹图的特点,研究了表面粗糙度参数的计算方法,完成了刨削和立铣不同粗糙度等级样块的测量,并增加触针法的测量结果作为参考标准。实验结果表明:非相干光三角法的测量结果与触针法结果接近,其中测量的轮廓算数平均偏差Ra的相对误差最大为11.3%,轮廓最大高度Rz的相对误差最大为16.9%。激光三角法在测量粗糙度值较大的样块▽3~▽5时误差较小,测量粗糙度值较小的样块▽6和▽7时误差激增,Ra和Rz的相对误差最大值都超过了100%;非相干光三角法的测量精度高于激光三角法。

Laser triangulation method is more and more used in roughness measurement because of its advantages of non-contact,simple structure and large working distance,but laser measurement is easy to be affected by speckle noise and cannot achieve high precision measurement.Therefore,an incoherent light triangulation method is proposed,which adopts incoherent line light as the measurement light source to avoid the influence of speckle noise.An incoherent light triangulation system for measuring surface roughness is developed.The characteristics of incoherent light stripe images and laser light stripe images are compared and analyzed.The calculation method of surface roughness parameters is studied.The measurements of planing and end milling specimens with different roughness grades are completed,and the measurement results of the stylus method are used as the reference standards.The results indicate that the measurement results of incoherent light triangulation method are similar to those of stylus method,in which the maximum relative error of arithmetic mean deviation Ra is 11.3%and that of maximum height of profile Rz is 16.9%.However,the measurement errors of the specimens 3 to 5 with large roughness values measured by laser triangulation method are small,but the measurement errors of the specimens 6 and V 7 with small roughness values are very large,and the maximum relative errors of Ra and Rz both exceed 100%.The measurement accuracy of incoherent light triangulation method is higher than that of laser triangulation method.