公差与互换性国际标准07Chapter 4 roughness.docx

1、公差与互换性国际标准07Chapter 4 roughnessChapter 4 Roughness4.1 General terms and definitions surface profile: Profile that results from the intersection of the real surface by a specified plane. sampling length lr: Length in the direction of the X-axis used for identifying the irregularities characterizing t

2、he profile under evaluation. evaluation length ln：Length in the direction of the X-axis used for assessing the profile under evaluation. In general, evaluation length equal five sampling length. profile peak：An outwardly directed (from material to surrounding medium) portion of the assessed profile

3、connecting two adjacent points of the intersection of the profile with the X-axis. profile valley: An inwardly directed (from surrounding medium to material) portion of the assessed profile connecting two adjacent points of the intersection of the profile with the X-axis. ordinate value Z(x):Height

4、of the assessed profile at any position x. profile peak height Zp: Distance between the X-axis and the highest point of the profile peak. Rp is the largest profile peak height Zp within a sampling length . profile valley depth Zv: Distance between the X-axis and the lowest point of the profile valle

5、y. Rv is the largest profile valley depth Zv within a sampling length. profile element width Xs: Length of the X-axis segment intersecting with the profile element.4.2 Evaluation parameterAmplitude parameters Arithmetical mean deviation of the assessed profile Ra: Arithmetic mean of the absolute ord

6、inate values Z(x) within sampling length. Maximum height of profile Rz: Sum of height of the largest profile peak height Zp and the largest profile valley depth Zv within a sampling length.Spacing parameters Mean width of the profile elements RSm: Mean value of the profile element widths Xs within a

7、 sampling length.4.3 Graphical symbols for the indication of surface textureBasic graphical symbolThe basic graphical symbol shall consist of two straight lines of unequal length inclined at approximately 60 to the line representing the considered surface, as shown in Figure 4-1. The basic graphical

8、 symbol in Figure 4-1 should not be used alone (without complementary information).Expanded graphical symbols Removal of material required:If removal of material for example, by machining is required for obtaining the specified surface, a bar shall be added to the basic graphical symbol, as shown in

9、 Figure 4-2.The expanded graphical symbol in Figure 4-2 should not be used alone (without complementary information). Removal of material not permitted:If removal of material is not permitted for obtaining the specified surface, a circle shall be added to the basic graphical symbol, as shown in Figu

10、re 4-3. Complete graphical symbol When complementary requirements for surface texture characteristics have to be indicated, a line shall be added to the longer arm of any of the graphical symbols illustrated in Figures 4-1 to 4-3, as shown in Figure 4-4. For use in the written text of for example, r

11、eports or contracts the textual indication for Figure4-4, a) is APA1), for b) it is MRR2) and for c) NMR3).Marks: Any process allowed. Material removal required. No material removed.4.4 Composition of complete graphical symbol for surface textureGeneralIn order to ensure that a surface texture requi

12、rement is unambiguous, it may be necessary, in addition to the indication of both a surface texture parameter and its numerical value, to specify additional requirements (e.g. transmission band or sampling length, manufacturing process, surface lay and its orientation and possible machining allowanc

13、es). It may be necessary to set up requirements for several different surface texture parameters in order that the surface requirements ensure unambiguous functional properties of the surface.Rules for comparison of the measured values with the tolerance limits The surface texture of the workpiece u

14、nder inspection can appear homogeneous or be quite different over various areas. This can be seen by visual examination of the surface. In cases where the surface texture appears homogeneous, parameter values determined over the entire surface shall be used for comparison with the requirements speci

15、fied on the drawings or in the technical product documentation. If there are separate areas with obviously different surface texture, the parameter values which are determined on each area shall be used separately for comparison with the requirements specified on the drawings or in the technical pro

16、duct documentation. For requirements specified by the upper limit of the parameter, those separate areas of the surface shall be used which appear to have the maximum parameter value.The 16%-rule For requirements specified by the upper limit of a parameter, the surface is considered acceptable if no

17、t more than 16% of all the measured values of the selected parameter, based upon an evaluation length, exceed the value specified on the drawings or in the technical product documentation. For requirements specified by the lower limit of a surface parameter, the surface is considered acceptable if n

18、ot more than 16% of all the measured values of the selected parameter, based upon an evaluation length, are less than the value specified on the drawings or in the technical product documentation. To designate the upper and the lower limits of the parameter, the symbol of the parameter shall be used

19、 without the “max.” index.The max.-rule For requirements specified by the maximum value of the parameter during inspection, none of the measured values of the parameter over the entire surface under inspection shall exceed the value specified on the drawings or in the technical product documentation

20、. To designate the maximum permissible value of the parameter, the “max.” index has to be added to the symbol of the parameter (for example Rz1max.).Position of complementary surface texture requirements The mandatory positions of the various surface texture requirements in the complete graphical sy

21、mbol are shown in Figure 4-5. The complementary surface texture requirements in the form of surface texture parameters, numerical values, and transmission band/sampling length,shall be located at the specific positions in the complete graphical symbol in accordance with the following.a) Position a S

22、ingle surface texture requirementIndicate the surface texture parameter designation, the numerical limit value and the transmission band/sampling length. To avoid misinterpretation, a double space (double blank) shall be inserted between the parameter designation and the limit value.Generally, the t

23、ransmission band or sampling length shall be indicated followed by an oblique stroke (/), followed by the surface texture parameter designation, followed by its numerical value using one text string.Example 1 0.0025-0.8/Rz 6.8 (example with transmission band indicated)Example 2 -0.8/Rz 6.8 (example

24、with only sampling length indicated)Especially for the motif method, the transmission band shall be indicated, followed by an oblique stroke (/), followed by the value of the evaluation length, followed by another oblique stroke, followed by the surface texture parameter designation, followed by its

25、 numerical value.b) Position a and b Two or more surface texture requirementsIndicate the first surface texture requirement at position “a” as in a). Indicate the second surface texture requirement at position “b”. If a third requirement or more is to be indicated, the graphical symbol is to be enla

26、rged accordingly in the vertical direction, to make room for more lines. The position “a” and “b” are to be moved upwards when the symbol is enlarged.c) Position c Manufacturing methodIndicate the manufacturing method, treatment, coatings or other requirements for the manufacturing process etc. To p

27、roduce the surface, for example, turned, ground, plated.The surface texture parameter value of an actual surface is strongly influenced by the detailed form of the profile curve. A parameter designation, parameter value and transmission band indicated solely as a surface texture requirement do not t

28、herefore necessarily result in an unambiguous function of the surface. It is consequently necessary in almost all cases to state the manufacturing process, as this process to some extent results in a particular detailed form of the profile curve.There may also be other reasons for finding it appropr

29、iate to indicate the process.The manufacturing process of the specified surface can be presented as text and added to the complete symbol as shown in Figures 4-6 and 4-7. Position d Surface lay and orientationIndicate the symbol of the required surface lay and the orientation, if any, of the surface

30、 lay, for example, “=”, “X”, “M”. The surface lay and direction of the lay emanating from the manufacturing process (e.g. traces left by tools) may be indicated in the complete symbol by using the symbols shown in Table 4-1 and illustrated by the example in Figure 4-8. The indication of surface lay

31、by the defined symbols (e.g. the perpendicularity symbol in Figure 4-8) is not applicable to textual indications.The direction of lay is the direction of the prevailing surface pattern, which is usually determined by the manufacturing process used.The symbols in Table 4.1 indicate the lay and direct

32、ion of lay in relation to the drawing plane containing the surface texture requirement.Table 4.1 Indication of surface layGraphicalsymbolInterpretation and exampleParallel to plane of projection of view in which symbol is usedPerpendicular to plane of projection of view in which symbol is usedXCrossed in two oblique directions relative to plane of projection of view in which s