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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 17852-1999 Geometrical tolerancing - Tolerancing of profile and the following main technical changes have been made with respect to GB/T 17852-1999:
——The application scope and interpretation of profile symbols are added;
——The following description of some symbols in GB/T 1182-2018, and explanation of the detailed labeling rules of these symbols in the profile tolerance are added;
——The default rules for profile tolerancing are added;
——Annex A is added to explain the definition rules of united feature;
——Annex B is added, including 16 application examples of profile specification.
This standard has been redrafted and modified in relation to ISO 1660: 2017 Geometrical product specifications (GPS) - Geometrical tolerancing - Profile tolerancing.
Technical differences between this standard and ISO 1660: 2017 are marked with perpendicular single line (|) in the outside page margin of the provisions concerned. The corresponding technical deviations and their causes are as follows:
——The adjustments of technical deviations are made for the normative references in this standard so as to adapt to the technical conditions of China. The adjustments are mainly reflected in clause 2 "Normative reference", which are detailed as follows:
ISO 1101: 2017 is replaced by GB/T 1182-2018, which is modified in relation to the international standard;
ISO 8015: 2011 is replaced by GB/T 4249-2018, which is modified in relation to the international standard;
ISO 5459: 2011 is replaced by GB/T 17851, which is modified in relation to the international standard;
ISO 17450-1 is replaced by GB/Z 24637.1, which is identical to the international standard;
ISO 16792 is replaced by GB/T 24734, which is not identical to the international standard.
In addition, the following editorial changes have been made in this standard:
——Table 1 in the introduction of ISO 1660: 2017 is deleted, and "Table 2~Table 4" in ISO 1660: 2017 are changed to "Table 1~Table 3".
This standard was proposed by and is under the jurisdiction of National Technical Committee 240 on Geometrical Product Specifications of Standardization Administration of China.
The previous edition of this standard is as follow:
——GB/T 17852-1999.
Geometrical product specifications (GPS) -
Geometrical tolerancing - Profile tolerancing
1 Scope
This standard gives the rules for geometrical specifications of integral and derived features.
This standard is applicable to the feature symbols of line profile and surface profile defined in GB/T 1182-2018.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 1182-2018 Geometrical product specifications (GPS) - Geometrical tolerancing - Tolerances of form, orientation, location and run-out (ISO 1101: 2017, MOD)
GB/T 4249-2018 Geometrical product specifications (GPS) - Fundamentals - Concepts, principles and rules (ISO 8015: 2011, MOD)
GB/T 17851 Geometrical product specifications (GPS) - Geometrical tolerancing - Datums and datum system (GB/T 17851-2010; ISO 5459: 1981, MOD)
GB/Z 24637.1 Geometrical product specifications (GPS) - General concepts - Part 1: Model for geometrical specification and verification (GB/Z 24637.1-2009; ISO/TS 17450-1: 2005, IDT)
GB/T 24734 Technical product documentation - Digital product definition data practices (GB/T 24734-2009; ISO 16792: 2006, NEQ)
ISO 17450-3 Geometrical product specifications (GPS) - General concepts - Part 3: Toleranced features
ISO 22432 Geometrical product specifications (GPS) - Features utilized in specification and verification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 1182-2018, GB/T 4249-2018, GB/T 17851, GB/Z 24637.1, ISO 17450-3 and ISO 22432 as well as the following apply.
3.1
profile tolerancing
geometrical tolerancing using the line profile symbol or the surface profile symbol
3.2
line profile
property of a line
3.3
surface profile
property of a surface
3.4
non-redundant degree of freedom
degree of freedom for which the tolerance zone is not invariant
4 Symbols
See Table 1 for symbols for geometrical characteristics.
Table 1 Symbols for geometrical characteristics
Line profile symbol
Surface profile symbol
These symbols shall be used in the characteristic section of the tolerance indicator, see GB/T 1182-2018, 8.2.
The nominal features, for which each symbol can be used, are given in Table 2.
Table 2 Valid geometrical characteristic symbol and nominal toleranced feature combinations
Toleranced feature
Integral straight line √
Derived straight line √
Integral non-straight line √
Derived non-straight line √
Integral flat surface √
Derived flat surface √
Integral non-flat surface √
Derived non-flat surface √
For straight lines and planes, there are other characteristic symbols that directly provide the information about the shape of the toleranced feature, e.g. flatness for planes and straightness for straight lines. The profile characteristic symbols may be used for straight lines and planes. However, in this case, to determine the nominal shape of the toleranced feature, it is necessary to verify that there is no indication that the feature is nominally non-flat or non-straight on the drawing or in the CAD model, as applicable.
Note: A nominally planar surface and a nominally curved surface with a large radius may both appear as a straight line on the drawing and the profile characteristic symbols may be used for both types of surfaces. However, if the surface is non-planar, it should be marked in the drawing, or given by explicit or default TED in CAD model. For the planar surface, there will be no such indication on a drawing. On a drawing, it is this indication or absence of indication that is used to determine the nominal shape of the feature in this case. In a CAD model, the model data are used to determine the nominal shape of the feature.
Additional symbols used in this document are given in Table 3 along with a reference to where they are defined.
Table 3 Additional symbols used in this document
Description Symbol Reference
Combined zone CZ GB/T 1182-2018, 8.2.2.1.2
Separate zones SZ GB/T 1182-2018, 8.2.2.1.2
Unspecified offset linear tolerance zone OZ GB/T 1182-2018, 8.2.2.1.4.1
Specified offset tolerance zone UZ GB/T 1182-2018, 8.2.2.1.3
Unified feature UF GB/T 1182-2018, 3.9
Between GB/T 1182-2018, 9.1.4
Unspecified angular offset tolerance zone VA GB/T 1182-2018, 8.2.2.1.4.2
All around GB/T 1182-2018, 9.1.2
All over GB/T 1182-2018, 9.1.2
Collection plane indicator GB/T 1182-2018, clause 16
Intersection plane indicator GB/T 1182-2018, clause 13
Direction feature indicator GB/T 1182-2018, clause 15
Orientation constraint only ＞＜ ISO 5459: 2011, 7.4.2.8
5 Rules for profile tolerancing
5.1 General
For the basic rules for geometrical tolerancing, of which profile tolerancing is a part, see GB/T 1182.
When a drawing shall be used in conjunction with a CAD model, an unambiguous reference to the CAD model shall be made on the drawing and the CAD model shall comply with GB/T 24734.
According to the feature principle (see GB/T 4249-2018, 5.4), by default a profile specification applies to one complete single feature as defined in ISO 22432. It is the designer’s responsibility to select the features or parts of features to which a specification applies and either indicate that on a 2D drawing using appropriate symbology or define it in the CAD model.
According to the independency principle (see GB/T 4249-2018, 5.5), by default a profile specification that applies to more than one complete single feature as defined in ISO 22432, applies to those features independently. If it is desired that the profile specification applies to the features as if they were one, or with some constraint amongst the tolerance zones for the single features, it is the designer’s responsibility to either indicate this on a 2D drawing using appropriate symbology or define it in the CAD model.
The “all over” indication and the “all around” indication shall always be combined with UF, CZ or SZ, when used for geometrical tolerancing, to make it explicit whether the specification applies to a united feature, defines a combined zone or defines a set of separate zones, except when all the non-redundant degrees of freedom for all the tolerance zones are locked by reference to datums.
Notes:
1 The meaning of CZ and SZ is identical when the specification defines a set of tolerance zones for which all non-redundant degrees of freedom are locked by reference to datums.
2 In previous revisions of this standard, “all around” was used without any other indication. That made it ambiguous whether the specification applied to the features independently or the specification defined a combined zone. The requirement to always use UF, CZ or SZ is a failsafe indication.
5.2 Default rules for profile tolerancing
5.2.1 Rule A: Definition of the theoretically exact feature (TEF)
The theoretically exact feature (TEF) of the toleranced feature shall be defined with theoretically exact dimensions (TEDs) or be embedded in the CAD model. For a feature of size, the nominal shape of the TEF shall be defined, but the nominal size of the TEF may be undefined, see Figure 4b).
These TEDs may include:
——explicit TEDs;
——implicit TEDs;
——tables of values and interpolation algorithms;
——mathematical functions including splines and other formulae;
——reference to CAD model queries.
A TEF that appears to be a nominally straight line or a nominal plane on the drawing with no explicit indication to the contrary, shall be considered a nominally straight line or a nominal plane, respectively, defined by implicit TEDs.
The shape of a TEF that is nominally a circle, a cylinder, a sphere or a cone is implicitly defined.
The shape of a TEF that is nominally a torus is defined when the directrix size is defined by an explicit TED.
The size of a feature of size is undefined, and shall therefore be considered variable, unless it is defined by an explicit TED. The size of the generatrix of a torus is undefined, unless it is defined by an explicit TED. See rules F and G.
Note: The diameter of the median surface of the tolerance zone is fixed at the nominal size.
Figure 1 Surface profile specification for a sphere of defined nominal size, given by a TED
If the TEF of a feature is defined by a table with sets of coordinates, the interpolation algorithm for defining points between the given coordinates shall also be defined.
Notes:
1 There is no standardized way to indicate the interpolation algorithm.
2 A non-exhaustive list of interpolation algorithms includes:
——linear interpolation;
——cubic spline interpolation (with or without periodicity conditions);
——NURBS.
Example: The points are connected by straight lines.
When the TEF is embedded in the CAD model, it shall comply with GB/T 24734.
5.2.2 Rule B: Type of toleranced feature
The rules for indicating whether the toleranced feature is an integral feature or a derived feature are given in GB/T 1182-2018, clause 6.
When the characteristic symbol in the tolerance indicator is the surface profile symbol, the toleranced feature is an integral or derived surface.
When the characteristic symbol in the tolerance indicator is the line profile symbol, the toleranced feature is either
——the derived feature (see B.15 in Annex B);
——any line in the identified integral or derived surface, in a specified direction (see B.14); or
——one specified line in the identified integral or derived surface.
If the toleranced feature is one identified line in a surface, the location of this line shall be identified by TEDs.
If the toleranced feature is any line in the identified surface in a specified direction, then that direction shall be identified using an intersection plane indicator, see GB/T 1182-2018, clause 13.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols
5 Rules for profile tolerancing
Annex A (Informative) Compound features
Annex B (Informative) Illustration of the rules
Annex C (Informative) Former indicating methods
Annex D (Informative) Position in the GPS matrix
Bibliography
