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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 13319-2003 Geometrical Product Specifications (GPS) - Geometrical tolerancing - Positional tolerancing. The following main technical changes have been made with respect to GB/T 13319-2003:
——Terms and definitions such as "pattern specification", "pattern feature", "tolerance zone pattern", "pattern characteristic", "theoretical exact feature pattern", "single indicator pattern specification", "multiple indicator pattern specification", "multi-level single indicator pattern specification", "internal constraint" and "external constraint" are added (see Clause 3);
——Definitions of symbols and specification modifiers are added (see Clause 4);
——Indication principle of tolerance indicator pattern specification based on specification modifiers is added (see Clause 5);
——The basic indication method of position tolerance and the marking method of composite position are deleted (see Clause 5 of Edition 2003).
This standard has been redrafted and modified in relation to ISO 5458: 2018 Geometrical product specifications (GPS) - Geometrical tolerancing - Pattern and combined geometrical specification.
Technical differences have been made with respect to ISO 5458: 2018, and corresponding technical differences and their reasons are as follows:
——The adjustments of technical changes 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 references", which are shown in the following:
? ISO 1101 is replaced by GB/T 1182, which is modified in relation to the international standard;
? ISO 8015 is replaced by GB/T 4249-2018, which is modified in relation to the international standard;
? ISO 17450-1 is replaced by GB/T 24637.1, which is modified in relation to the international standard;
? ISO 17450-2 is replaced by GB/T 24637.2, which is modified in relation to the international standard;
? ISO 22432 is replaced by GB/T 38760, which is modified in relation to the international standard;
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 13319-2003.
Geometrical product specifications (GPS) - Geometrical tolerancing -
Pattern and combined geometrical specification
1 Scope
This document establishes complementary rules to GB/T 1182 to be applied to pattern specifications and defines rules to combine individual specifications, for geometrical specifications e.g. using the symbols POSITION, SYMMETRY, LINE PROFILE and SURFACE PROFILE, as well as STRAIGHTNESS (in the case where the toleranced features are nominally coaxial) and FLATNESS (in the case where the toleranced features are nominally coplanar) as listed in Annex C.
These rules apply when a set of tolerance zones are grouped together with location or orientation constraints, through the use of the CZ, CZR or SIM modifiers.
This document does not cover the use of the pattern specifications when the least and maximum material requirement is applied (see GB/T 16671).
This document does not cover the establishment of common datum (see GB/T 17851) based on pattern features.
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 Geometrical product specifications (GPS) - Geometrical tolerancing - Tolerances of form, orientation, location and run-out (GB/T 1182-2018, ISO 1101: 2017, IDT)
GB/T 4249-2018 Geometrical product specifications (GPS) - Fundamentals - Concepts, principles and rules (ISO 8015: 2011, MOD)
GB/T 24637.1 Geometrical Product Specifications (GPS) - General concepts - Part 1: Model for geometrical specification and verification (GB/T 24637.1-2020, ISO 17450-1: 2011, MOD)
GB/T 24637.2 Geometrical product specifications (GPS) - General concepts - Part 2: Basic tenets, specifications, operators, uncertainties and ambiguities (GB/T 24637.2-2020, ISO 17450-2: 2012, MOD)
GB/T 38760 Geometrical product specifications (GPS) - Features utilized in specification and verification (GB/T 38760-2020, ISO 22432: 2011, MOD)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 1182, GB/T 4249, GB/T 24637-1, GB/T 24637-2, GB/T 38760 and the following apply.
3.1
pattern specification
combined requirement indicated by a set of geometrical specifications, and controlled by a tolerance zone pattern
Note 1: The geometrical features controlled by a pattern specification can be a set of compound features, united features or single features, which can be features of size (linear or angular).
Note 2: Table C.1 provides examples of pattern specifications.
Note 3: The set of pattern features controlled by a pattern specification does not define a united feature. A united feature can be a pattern feature, i.e. one of the members of the toleranced features controlled by a pattern specification.
3.2
pattern feature
geometrical feature which is a member of the set of single features controlled by a pattern specification
3.3
tolerance zone pattern
combination of more than one tolerance zone, having, without priority between them, constraints of orientation and location, or constraints of orientation
Note 1: A tolerance zone pattern is composed of several tolerance zones which can have different nominal geometries.
Note 2: A tolerance zone pattern can be established without external constraint or with orientation constraint and/or location constraint from a datum system.
3.4
pattern characteristic
geometrical characteristic controlled by a pattern specification
3.5
theoretical exact feature pattern
TEF pattern
combination of more than one TEF having, without priority between them, constraints of orientation and location, or constraints of orientation, used to establish the pattern characteristic
Note 1: A TEF pattern is composed of several TEFs which can have different nominal geometries and constrained between them, with respect to their relative location and/or orientation.
Note 2: A TEF pattern can be established without external constraint or with orientation constraint and/or location constraint from a datum system.
3.6
single indicator pattern specification
pattern specification, controlled by one tolerance indicator specification
3.7
multiple indicator pattern specification
pattern specification, controlled by more than one tolerance indicator specification
3.8
multi-level single indicator pattern specification
single indicator pattern specification applied to more than one group of toleranced features
3.9
internal constraint
location constraint and/or orientation constraint between the individual tolerance zones of the tolerance zone pattern
3.10
external constraint
location constraint and/or orientation constraint between a tolerance zone or tolerance zone pattern and a datum system
4 Symbols and specification modifiers
For the purposes of this document, the specification modifiers of Table 1 shall apply.
Rules for the presentation of graphical symbols shall be in accordance with Annex D.
Table 1 Specification modifiers
Applied to Symbol Description Internal constraint Modifier defined in
Toleranced feature UF Unified feature Not applicable GB/T 1182
Tolerance zone SZ Separate zones None 5.1
SIMi a, b Simultaneous requirement No. i Orientation and location constraints 5.4.4
CZ Combined zone Orientation and location constraints 5.4.3, 5.4.5 and GB/T 1182
Tolerance zone CZR Combined zone rotational only Orientation constraint only 5.4.3 and 5.4.5
a An identification number i can be associated to the modifier SIM. In this case there is no space between SIM and i.
b “SIM” in ISO 8785 is used for a family of “surface imperfection” parameters with indices (e.g. a, n, t, w, cd, ch, sh, n/A). The modifier simultaneous requirement (SIM) as indicated in this document shall not be confused with the indication of a surface imperfection parameter (e.g. SIM1 versus SIM t).
5 Principle
5.1 General
According to the feature principle (see 5.4 in GB/T 4249-2018), by default a geometric specification applies to one complete single feature defined in GB/T 38760. It is the designer’s responsibility to select the features or portions 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 independence principle (see also 5.5 in GB/T 4249-2018), by default a geometric specification that applies to more than one single feature applies to those features independently. The tolerance zone defined by one tolerance indicator or by several tolerance indicators shall be considered independently by default. This corresponds to the meaning of the modifier SZ. When the same geometrical specification is applied to several toleranced features, for all geometrical specifications other than position specifications, the indication of SZ modifier is redundant (see 5.3 for Rule A for position specification).
If it is required that the geometrical specification applies to the features simultaneously with some constraint between the tolerance zones, it is the designer’s responsibility to either indicate this on a 2D drawing or in the CAD model using appropriate pattern specifications.
In order to manage functional requirements for a set of features, they can be controlled simultaneously by means of a pattern specification, using tolerance zone pattern modifiers CZ, CZR or SIMn.
The use of the concept of “simultaneous requirement” transforms a set of more than one geometrical specification into a combined specification, i.e. a pattern specification.
There are two ways to create a tolerance zone pattern, either by using a single indicator pattern specification with the CZ or CZR modifier [see Figure 1a) and Rule C/E] or by using a multiple indicator pattern specification using SIM modifiers [see Figure 1b) and Rule D (5.4.4)].
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols and specification modifiers
5 Principle
Annex A (Informative) Former practice, important changes
Annex B (Informative) Differences between GB/T 13319-2003 and this standard
Annex C (Informative) Examples of pattern specifications
Annex D (Normative) Relations and dimensions of graphical symbols
Annex E (Informative) Concept diagram for pattern specification and relation with modifiers
Annex F (Informative) Relation to the GPS matrix model
Bibliography
