Geometrical product specifications (GPS)—Inspection by measurement of workpieces and measuring equipment—Part 4:Background on functional limits and specification limits in decision rules
other information
drafter:Kong Ming, Ming Cuixin, Hao Jianguo, Wang Weinong, Wang Jin, Zhu Yue, Zhao Jun, Zheng Peng
Drafting unit:China University of Metrology, China Machinery Productivity Promotion Center, Beijing Times Peak Technology Co., Ltd., China National Institute of Metrology, Hexagon Measurement Technology (Qingdao) Co., Ltd., Zhengzhou University
Focal point unit:National Technical Committee for Standardization of Product Geometry Technical Specifications (SAC/TC 240)
Proposing unit:National Technical Committee for Standardization of Product Geometry Technical Specifications (SAC/TC 240)
Publishing department:State Administration for Market Regulation National Standardization Administration
Some standard content:
ICS 17.040.01
National Standard of the People's Republic of China
GB/T18779.4—2020
Geometrical product specifications (GPS)-Inspection by measurement of workpieces and measuring equipment-Part 4: Background on functional limitsand specificationlimitsindecisionrules(ISO/TS 14253-4:2010.MOD)
Release on 2020-12-14
State Administration for Market Regulation
National Administration of Standardization
Implementation on 2021-07-01
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Normative references
Terms and definitions
Relationship between functional limit and specification limit
Determination of functional limit
Specification limit and method for determining specification limit based on functional limit Assumptions on the shape of functional degradation curve
Determination of specification limit
9 Other judgment rules.
Appendix A (informative) Relationship with GPS matrix model References
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GB/T 18779.4—2020
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GB/T 18779.4—2020
GB/T18779≤Product Technical Specification (GPS) Measurement Inspection of Workpieces and Measuring Equipment" is divided into 6 parts: Part 1: Rules for judging whether the inspection is qualified or unqualified according to the specification pool: Part 2: Guide for evaluating the uncertainty of GPS measurement in the calibration of measuring equipment and product inspection; Part 3: Guide for reaching an understanding of the expression of measurement uncertainty: Part 1: Basis for functional limits and specification limits in judgment rules: Part 5: Verification uncertainty of indicating measuring instruments: Part 6: General judgment rules for acceptance/rejection of instruments and parts. This part is Part 4 of GB/T18779
This part was drafted according to the rules given in GB/T1.1—2009. This part uses the redrafting method to modify 1S0/TS14253-4:2010≤Product Geometric Technical Specification (GPS) Measurement and inspection of workpieces and measuring equipment: Part 4: Basis of functional limits and specification limits in decision rules". The technical differences between this part and IS0/TS14253-4:2010 and the specific reasons are as follows: Regarding the normative reference documents, this part has made adjustments with technical differences to adapt to my country's technical conditions. The adjustments are reflected in the second competition "Normative Reference Documents" market, and the specific adjustments are as follows:. Replace 1S011253-[(see Chapter 3.4.2, 1.3.9.1) with equivalent international standards (3/T18779.1). This part has made the following editorial changes:
Appendix A has been rewritten according to the requirements of GB/T20308
32020.
This part is proposed and managed by the National Technical Committee for Standardization of Product Geometry Technical Specifications (SAC/TC240): Drafting units of this part: China University of Metrology, China Machinery Productivity Promotion Center, Beijing Times Peak Technology Co., Ltd., China Institute of Metrology, Hexagon Measurement Technology (Qingdao) Co., Ltd., Zhengzhou Renxue. The main drafters of this part: Kong Ming, Ming Cuixin, Hao Jianguo, Gong Wei Nong, Gong Jin, Zhu Yue, Zhao Jun, Zheng Peng, rKae erkAca-
GB/T18779.4—2020
This part of GB/T18779 is a geometric product specification (GPS) standard and will belong to the global GPS standard system (see GB/T20308). It affects parts C, D, E, F, and G in the GPS matrix model. For more details on the relationship between this part of GB/T18779 and other standards and the GPS matrix model, see Appendix A. Unless otherwise specified, the judgment rules given in GB/T18779.1 apply to ensure that the workpiece and measuring equipment are within the specification range and to avoid disputes over whether the workpiece and measuring equipment are within the specification range. In order for the judgment rules to work in a direct design manner, it is important to first provide proof of conformity. In other words, the user/buyer of the product in question always requires the manufacturer/supplier/entity of the product to provide proof of product conformity. If the subsequent incoming inspection proves to be unqualified, the uncertainty report can be checked in accordance with GB/T18779.3 to ensure its validity. If the conclusion is that both uncertainty reports are valid, then the only conclusion is that one or both of their measurement results are not representative of the measurement process in question. If for some reason the user of the product does not want the supplier to provide first evidence, but relies on incoming inspection, the user should seek to reduce the functional limit through the measurement uncertainty of the incoming inspection to achieve the agreed contract specification limit and negotiate with the supplier to reach an agreement. Another problem is dealers, who purchase products from manufacturers and then transfer parts to users: if If the distributor requires the product manufacturer to provide a certificate of conformity and then provides it to the user, the decision rules given in GB/T 18779.1 will not work correctly. If the distributor decides to provide the user with a certificate of conformity independently for some reason, a situation will arise where neither conformity nor nonconformity can be proven, so that the distributor can neither return the product according to the original specification nor resell the product. Therefore, this approach is not recommended. The decision rules in GB/T 18779.1 are also based on some assumptions. When these assumptions do not hold, these decision rules may not be economically optimal. This part of B/T 18779 outlines these assumptions and discusses why they are theoretically ideal assumptions. For workpieces, usually only the creator (designer) of the specification knows whether the assumptions hold. Therefore, any deviation from the decision rules of GB/T 18779.1 can only be proposed and documented by the owner of the specification. For measuring equipment, the specification can be based on standards written unilaterally by the equipment manufacturer or the buyer, or by the equipment manufacturer and the buyer in cooperation. If the specification is based on a national standard and that standard does not specify other judgment rules, the rules of GB/T18779.1 apply: In other cases, judgment rules can only be documented by the specification author. It should be recognized that both implicit and explicit judgment rules are part of the specification, and it should be further recognized that the issues involved in selecting the optimal set of judgment rules are complex. It is unrealistic to expect simple rules to apply to every situation. Parties should ensure that adequate technical resources are available before deviating from the decision rules of GB/T 18779.1. In such cases, the specification owner needs to be aware that other decision rules than those defined in GB/T 18779.1 are applicable and that a compilation support of this policy needs to be prepared and provided to trading partners (customers and/or suppliers) and referenced in the product technical documentation.
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1 Scope
Product Geometrical Technical Specification (GPS)
Measurement and inspection of workpieces and measuring equipment
Part 4: Basis of functional limits and specification limits in decision rules
GB/T 18779.4—2020
This part of GB/T 18779 specifies the main assumptions underlying the theoretical ideal decision rules in GB/T 18779.1. The reasons why these rules should be the default rules are given, as well as the factors that need to be considered before applying different judgment rules. This part applies to all specifications involved in the GPS general standard (see (13/T20308), that is, the standard compiled by SAC/TC240: including workpiece specifications (usually given in the form of specification limits) and measuring equipment specifications (usually given in the form of maximum allowable errors). 2 Normative references
The following documents are indispensable for the application of this document. For all references with a period II, only the version with a period II applies to this document: For all references without a date, the latest version (including all amendments) applies to this document: ([3/T【8779.! Technical Specifications for Product Geometric Quantity (GPS) T Measurement and Inspection of Parts and Measuring Equipment Part 1: Judgment Rules for Acceptance or Failure According to Specification Inspection (GB/T18779.12002.eqvIS)14253-1:1998) 3 Terms and Definitions
GB/T18779.1 The defined and following terms and definitions apply in this document 3.1
reverse engineering
reverse engineering
the design process of analyzing the shape, size and function of a finished workpiece or prototype and using this information to manufacture a similar product 3.2
product functional level productfunctional level the degree of perfection of product functions from an overall perspective 3.3
product attribute functional level productattributefunctional level the degree of perfection of product functions from a specific attribute Note: The overall product functional level depends on all product attribute functional levels. 3.4
workpiecefunctional levelworkpiecefunctional level evaluates the overall perfection of the product functions composed of the workpiece under consideration and a group of qualified workpieces. 3.5
workpiececharacteristicfunctional level evaluates the perfection of the product functions composed of the workpiece under consideration and a group of qualified workpieces from the specific attributes. These attributes are affected by the characteristics under consideration. Note: The overall workpiece functional level depends on the functional levels of all workpiece characteristics. 3.6
functional level of metrological characteristic evaluates the perfection of the measurement equipment composed of the metrological characteristic under consideration and a group of acceptable metrological characteristics from the specific attributes. These attributes are affected by the characteristics under consideration. 3.7
functionaldeteriorationcurve Graphical representation of the relationship between the functional level of a product and the value of a geometrical characteristic, the sum of geometrical characteristics or the functional level of a quantitative characteristic: Note: Generally speaking, the conversion from the active functional level of a product to the derived functional limits of a geometrical characteristic or a metrological characteristic is not perfect. The uncertainty of the functional description (see GIB/T 24637.2) quantifies this imperfection. 4 Relationship between functional limits and specification limits
4.1 Overview
The implementation guidelines for determining limits (the set of limit operations) determine the relationship between functional limits and the specified limits specified in the design drawings. In many cases, multiple workpieces, multiple elements and the characteristics of the elements on each workpiece have an impact on a given function. In order to ensure that the specification is relevant to the function, it is crucial to select the appropriate characteristics of the appropriate elements for the specification design: the specification maker has the responsibility to select the characteristics that are relevant to the function for the specification. Most functions depend on a single-sided specification limit. For example, the ability of a shaft to fit a given hole depends on the shaft diameter not being too large. For a matching hole, there is no lower limit to the diameter range of the shaft. The lower specification limit of this type of shaft diameter has a completely different function, for example, it stipulates that the fit between the shaft and the hole cannot be too loose, there cannot be leakage on the contact surface, or the strength of the shaft cannot be too low. 4.2 One-sided case
The theoretical assumptions used to define the basic rules in GPS, including the judgment rule defined in G3T187791, are that the specification is equal to the functional limit, and when the specification limit is not exceeded, the function of the workpiece is 100, and when the specification limit is exceeded, the function of the workpiece is 0%, as shown in Figure 1.
Description:
Functional level of workpiece feature:
Feature value:
- Workpiece qualified;
SL - Specification limit.
Note: For the upper specification limit, when the specific characteristic value is below the specification limit (SL), the function level of the workpiece is 100% (full function), and when it exceeds the specification limit, the function level of the workpiece is 0%. For the lower specification limit, the situation is similar. Figure 1 One-sided case where the specification limit is equal to the functional limit rrKaeerkca-
GB/T18779.4—2020
The actual degradation curve of the functional level of the lower part is different from that shown in Figure 1, as shown in Figure 2. This functional level curve can also represent the diameter of the shaft that matches the hole. When the shaft diameter becomes very large, the shaft cannot match the hole, and the functional curve degrades rapidly: A
Explanation:
1. The functional level of the part to be characterized;
Characteristic characteristics,
Note 1: The above example is an example of the upper functional limit where the kinetic energy of the lower part gradually degrades after the characteristic value of the characteristic functional level increases to exceed the wind range of 10. The situation of the lower functional limit is similar,
Note 2: The tail of the curve The part represents the situation where the parts can still fit by extrusion, or the diameter difference between the hole and the shaft still allows the hole and shaft to fit together, because the characteristic function of the fit depends on the difference between the two sizes, rather than the size of a single piece. Figure 2 One-sided situation of the workpiece function degradation curve For different functions of the workpiece, the degradation curve of its functional level will have different shapes and the degradation rate will also be different, as shown in Figure 3. 4
Description:
1 Functional level to be characterized:
One characteristic characteristic,
Note: For different functions, when a specific characteristic value is outside the area where all functions can be 10, the functional level of the workpiece will gradually decrease. Figure 3 One-sided situation of the degradation curve of different functions of the workpiece In the situation shown in Figures 2 and 3, it is necessary to make the functional limit meaningful. To define, a minimum acceptable functional level, as shown in Figure 4:
An example of this situation is the vibration of the turbine shaft: the vibration is caused by the imbalance of the turbine. For example, the imbalance may be caused by the straightness deviation of the turbine shaft, the roundness deviation of the turbine shaft and the weight deviation of the fan blades. When the vibration history is strong, the noise will increase and the life of the turbine will be reduced. The turbine design criteria include the requirement for its minimum life. It is impossible to manufacture a vibration-free turbine, and reducing the tolerance to limit the vibration will lead to an increase in manufacturing costs. Therefore, a reasonable vibration level that can ensure a reasonable product life should be determined during the design. This reasonable vibration level determines the component functional level X% in Figure 4. The specification of the turbine component can be obtained from this appropriate minimum functional level. Www.bzxZ.net
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GB/T18779.4—2020
Description:
A—Function level of workpiece feature;
Feature value:
1 piece qualified:
Lower function limit;
Upper function limit.
Note: Determine a minimum function level, and the function limit can be determined by the point where the function degenerates to this value. Figure 4 defines the one-sided case of the acceptable minimum functional level A
F1=UF1.2 UFt.1 UFl.3
Description:
Functional level of workpiece feature
Feature value:
1 piece is qualified;
Functional limit:
Function 1;
Function 2:
Function 3;
-Functional limit,
Figure 5 The same characteristic value determines the functional level of three functions B
Figure 5 shows the case where the same characteristic value determines the functional level of three functions, in which each function has an acceptable minimum functional level F%, F% or F%: for the corresponding characteristic value. Each of these acceptable minimum functional levels will determine an upper functional limit, namely LFL1, UFL2 and UFL3. The functional limit is determined by the most stringent limit among these functional limits, in this case UFL2.
and the functional limit is determined. As shown in Figure 1 or Figure 5, the specification limit can be placed before the functional limit. As shown in Figure 6, in principle, the specification limit can also be placed after the functional limit, but this is usually meaningless. In many cases, the company has a (written or unwritten) implementation method that specifies the relationship between specification limits and functional limits. KaeerkAca-
says:
"Functional level of part characteristics;
Feature value:
Part qualified;
Specification limit;
Functional limit.
GB/T 18779.4—2020
Note: For the upper functional limit (UFL), when the specific characteristic value is below the functional limit: the functional level of the part is 100% (full function). When the characteristic value is above the functional limit, the functional level is 6%. However, the specification limit is placed before the functional limit. The situation of the lower specification limit is similar. Figure 6 Specification limit before the functional limit One-sided case Two-sided case
Sometimes, in order to make the function of the workpiece acceptable, the characteristic is formed within a range. In this case, when the characteristic of the part is between the specification limits, the functional level of the workpiece is 100%, and when it is outside this range, its functional level is 0%, as shown in Figure 7, A
Explanation:
1 Functional level of the characteristic of the part;
Characteristic value:
Work.The part is qualified;
Lower specification limit:
「Specification limit
Note: When the specific characteristic value is between the lower specification limit and the upper specification limit: 1 The functional level of the part is 100% (full function). When the value is outside this range, the functional level of the workpiece is (%.
Figure 7 The double-sided situation where the specification limit is equal to the functional limit is shown in Figure 8. The degradation line of the lower functional level is different from the shape shown in Figure 7. Usually, the shape of the line is different at both ends 5
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Description:
T. Functional level of the workpiece to be tested:
- Characteristic value
Note: When a specific characteristic value is outside the area corresponding to the functional level of 1%, the function of the workpiece gradually degrades. At both ends of the area, the degradation rate is different.
Figure 8 Double-sided situation of workpiece functional level degradation In the case shown in Figure 8, in order to make the functional limit meaningful, it is necessary to define an acceptable minimum functional level, as shown in Figure 9. Al| |tt||Speaking:
Functional level of a component characteristic;
Characteristic value:
Component acceptance:
Lower functional limit:
Upper functional limit
Note: Determine a minimum functional level X, and the functional limit is determined by the point at which the functional curve degenerates to this value. Figure 9 Two-sided case defining the minimum acceptable functional level. The characteristic value may determine the functional level of several functions. In this case, as in the unilateral case, the overall functional limit is determined by all the "functional limits and the lower functional limit" The most stringent limit in the functional limit is determined. The functional limit is determined. As shown in Figure 9, the specification limit can be placed inside the functional limit, as shown in Figure 10. Principle 1 Specification limits can be placed outside the functional limit, but this is usually meaningless. For the situation described in Figure 6, the company may have a (written or unwritten) implementation policy to define the relationship between specification limits and functional limits, as shown in Figure 10, where the distance between the upper specification limit and the upper functional limit does not necessarily have to be equal to the distance between the lower specification limit and the lower functional limit.
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