National standard terms and meanings of surface roughness
(1) surface roughness sampling length L
sampling length is a length of reference line specified for judging and measuring surface roughness, which samples on the overall trend of the contour
(2) evaluation length of surface roughness ln
in all steel trade ecosystems,
due to the uneven processing surface to varying degrees, in order to fully and reasonably reflect the roughness characteristics of a certain surface, a section of surface length necessary for evaluation is specified, which includes one or several sampling lengths, called the evaluation length LN
(3) the center line of surface roughness contour m
the center line of contour m is the reference line for evaluating the value of surface roughness
evaluation parameters and values
the parameters of national surface roughness are composed of height parameters, spacing parameters and comprehensive parameters
there are three surface roughness height parameters:
(1) the arithmetic mean deviation of contour ra
the arithmetic mean value of the absolute value of contour offset within the sampling length L after yielding(2) the sum of the average value of the maximum contour peak height within the sampling length and the average value of the five maximum contour Valley depths
(3) the maximum height of the contour ry
within the sampling length, the distance between the contour peak line and the contour bottom line
there are two surface roughness spacing parameters:
(4) the average spacing of contour single peaks s
the projection length Si of the highest point of two adjacent contour single peaks on the centerline is called contour single peak spacing. Within the sampling length, the average value of contour single peak spacing is the average spacing of contour single peaks
(5) the average spacing of contour micro unevenness SM
contains a contour peak and a section of median length SMI of adjacent contour valleys, which is called contour micro unevenness spacing
surface roughness comprehensive parameter
but because the machine stability is closely related to the rigidity of the host machine and the rigidity of the sample during force control and deformation control (6) the contour is used for high-precision support length ratio TP
the contour support length ratio is the ratio of the contour support length NP to the sampling length L
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