ISO 12780-1:2011 幾何学的製品仕様（GPS）—真直度—パート1：用語, 語彙と真直度のパラメーター | ページ 6

3.1.1

真直度

直線の性質

3.1.2

通常は表面の

積分フィーチャーに関連付けられたフィーチャーの法線

3.1.3

真直度計画

関連する一体形体との交点が直線である平面

注記 1:デフォルトでは、真直度平面には表面の法線が含まれます。

3.2.1

extracted line

digital representation of the intersection of the real surface and the straightness plane

3.2.2

straightness profile

extracted line intentionally modified by a filter

Note 1 to entry: This is the profile to which the concepts and parameters of this part of ISO 12780 can be applied.

3.2.3

local straightness deviation

Δ S_l

deviation of a point on a straightness profile from the reference line, the deviation being normal to the reference line

Note 1 to entry: The deviation is negative if from the reference line the point lies in the direction of the material.

3.3.1

reference line

associated line fitting the straightness profile in accordance with specified conventions, to which the deviations from straightness and the straightness parameters are referred

3.3.1.1

minimum zone reference lines

two parallel lines in the straightness plane enclosing the straightness profile and having the least separation

3.3.1.1.1

outer minimum zone reference line

minimum zone reference line outside the material

3.3.1.1.2

inner minimum zone reference line

minimum zone reference line inside the material

3.3.1.1.3

mean minimum zone reference line

arithmetic mean line of the minimum zone reference lines

3.3.1.2

least squares reference line

line such that the sum of the squares of the local straightness deviations is a minimum

3.4.1

profile filter

filter operating on an open profile transmitting a range of sinusoidal undulations for which the ratio of output to input amplitude is defined while attenuating (i.e. reducing) the ratio for undulations lying outside the range at either or both ends

3.4.2

cut-off wavelength

cut-off wavelength of the filter applied to the extracted line

3.4.3

transmission band for straightness profiles

band of sinusoidal profile undulations which are transmitted by greater than a specified percentage by the filter, defined by the values of the upper and lower cut-off wavelengths

Note 1 to entry: The specified percentage is usually 50 %.

3.5.1

peak-to-valley straightness deviation

value of the largest positive local straightness deviation added to the absolute value of the largest negative local straightness deviation

Note 1 to entry: The peak-to-valley straightness deviation is defined for all reference lines.

Note 2 to entry: The peak-to-valley straightness deviation is the only parameter that is defined for minimum zone reference lines.

Note 3 to entry: The modifier GT is used in specifications to indicate that a form tolerance applies to the peak-to-valley deviation relative to the least squares reference element.

3.5.2

peak-to-reference straightness deviation

value of the largest positive local straightness deviation from the least squares reference line

Note 1 to entry: The peak-to-reference straightness deviation is only defined for least squares reference lines.

Note 2 to entry: The modifier GP is used in specifications to indicate that a form tolerance applies to the peak-to-reference deviation relative to the least squares reference element.

3.5.3

reference-to-valley straightness deviation

absolute value of the largest negative local straightness deviation from the least squares reference line

Note 1 to entry: The reference-to-valley straightness deviation is defined only for least squares reference lines.

Note 2 to entry: The modifier GV is used in specifications to indicate that a form tolerance applies to the reference-to-valley deviation relative to the least squares reference element.

3.5.4

root-mean-square straightness deviation

Δ S _rms

square root of the sum of the squares of the local straightness deviations from the least squares reference line

Note 1 to entry: The root-mean-square straightness deviation is only defined for least squares reference lines.

Note 2 to entry: The modifier GQ is used in specifications to indicate that a form tolerance applies to the root-mean-square deviation relative to the least squares reference element.