目的 为了比较用于平板板表面波纹度测量的三种滤波器的传输特性差异。方法 三种滤波器分别是JIS B 0610采用的2RC滤波器、SEP 1941采用的指数滤波器和ASME B46.1采用的高斯滤波器。采用频谱分析的方法比较了原始轮廓与不同滤波器得到的波纹度轮廓的频谱特性,计算对比不同滤波器得到的波纹度参数的差异。结果 三种滤波器的幅值特性没有振荡现象,但是高斯滤波器和指数滤波器的幅值下降速度更快。高斯滤波器和指数滤波器在截止波长处的幅值下降了50%,而2RC滤波器在截止波长处的幅值只下降了25%。从相位特性看,高斯滤波器和指数滤波器属于无相位移动滤波器,而2RC滤波器属于有相位移动的滤波器,在截止波长位置的相位移动约为1.05。在相同的截止波长下,指数滤波器与高斯滤波器的传输特性完全一致。进一步研究表明,采用2RC滤波器得到的波纹度参数Wa比采用高斯滤波器得到的波纹度参数Wa高0.1mm左右。结论 高斯滤波器和2RC滤波器都无法同时完全抑制截止波长范围以外的成分而完全保留截止波长范围之内的成分。

Objective To compare difference between transmission characteristics of the three filters used in waviness measurement on sheet surface. Methods Three different filters are 2RC filter, Gaussian filter and an exponential filter, respectively. Spectrums of waviness profiles calculated by different filters and primary profile were studied. Finally, the waviness parameters on sheet surface were figured out through different filters. Results With no oscillation, amplitude of the Gaussian filter and the exponential filter decrease more quickly than the 2RC filter. At the cut-off wavelength, amplitude of the Gaussian filter and the exponential filter decrease a half and that of the 2RC decreases a quarter. For phase characteristic, the Gaussian filter and the exponential filter belong to phase correct filters and the 2RC filter belong to no phase correct filter whose phase shift about 1.05 at the cut-off wavelength. It could be found that the transmission characteristics of Gaussian filter are exactly same as that of the exponential filter. Moreover, the waviness parameter filtered by the 2RC filter is bigger 0.1um than that filtered by the Gaussian filter. Conclusion Both the Gaussian filter and the 2RC filter could not exactly suppress component beyond scope defined by cut-off wavelength and remain component between the scope.