Some standard content:
National Metrology Verification Regulation of the People's Republic of China JJG63—2007
Straight Edge
Promulgated on 2007-02-28,
Implementation on 2007-08-28
The General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China issued JJG63—2007
Verification Regulation of
Straight Edge
JJG63—2007
Replaces JJG63-1994
This regulation was approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on February 28, 2007, and came into effect on August 28, 2007.
Responsible unit: National Technical Committee for Metrology of Geometry and Engineering Parameters Drafting unit: Beijing Institute of Metrology and Testing Science This regulation is entrusted to the National Technical Committee for Metrology of Geometry and Engineering Parameters to be responsible for the interpretation of this regulation Drafting person:
JJG 63—2007
Ma Guiru (Beijing Institute of Metrology and Testing Science) Wu Xun (Beijing Institute of Metrology and Testing Science) 1
Scope·
References
3 Overview…
4 Metrological performance requirements
5 General technical requirements
5.1 Appearance
5.2 Surface quality
6 Control of measuring instruments
6.1 Verification conditions
Verification items·
Verification methods
Processing of verification results·
6.5 Verification cycle
JJG63—2007
Appendix A Evaluation of the uncertainty of the measurement results of the straightness of the working edge of the knife-edge ruler Appendix B Format of the verification certificate and the verification result notification (inside page) Formula (1)
1 Scope
JJG63—2007
Verification Procedure for Knife-Edge Rulers
This procedure is applicable to the initial verification, subsequent verification and in-use inspection of knife-edge rulers. 2
References
This procedure refers to the following documents:
JF1001—1998 General metrological terms and definitions JF1059—1999 Evaluation and expression of measurement uncertainty JF1094—2002 Technical specification for evaluation of measuring instrument characteristics JF1130—2005 Guide for evaluation of uncertainty in calibration of geometrical measuring equipment GB/T6091-2004 Knife-Edge Rulers
ISO/TS14253—2:1999
Geometrical Product specifications (GPS)-Inspection by measurement of workpieces and measuring equipment Part 2: Guide to the estimation of uncertainty in GPS measurement，in calibration of measuring equipment and in product verification (《Product geometrical quantity technical specifications (GPS) - measurement inspection of workpieces and measuring equipment Part 2: Guide to the estimation of uncertainty in GPS measurement，in calibration of measuring equipment and in product verification》)
When using this procedure, attention should be paid to using the current valid version of the above-mentioned references. 3 Overview
The knife-edge ruler is a measuring tool that uses the straightness of its working edge as the standard and uses the light gap method to compare and measure the straightness or flatness of the measured piece. Its type, schematic diagram of structural shape and length of the working edge are shown in Table 1. Table 1 Types, structural diagrams and working edge lengths of knife-edge rulers Type
Knife-edge ruler
Three-sided ruler
Four-sided ruler
Working edge length (mm)
75, 125, 175, 200,
225, 300, 400, 500
175, 200, 225, 300, 500
125, 175, 200,
225, 300, 400, 500
4 Metrology performance requirements
JJG63—2007
The maximum allowable error of the straightness of the working edge of a knife-edge ruler is shown in Table 2. Table 2 Maximum permissible error of straightness of the working edge of a knife-edge ruler Working edge length
Maximum permissible error of straightness
MPEs/μm
5 General technical requirements
5.1 Appearance
5.1.1 The knife-edge ruler shall be marked with dimensions, manufacturer’s name (or trademark) and factory number, etc. 5.1.2 The knife-edge ruler shall be equipped with an insulating shield, and the three-sided ruler and the four-sided ruler shall be equipped with a handle. 5.2 Surface quality
5.2.1 The working edge of the knife-edge ruler and the surface connected to it shall be free of rust, bruises, cracks and other defects that affect the measurement performance.
5.2.2 The knife-edge ruler shall be non-magnetic.
6 Control of measuring instruments
Control of measuring instruments includes initial verification, subsequent verification and in-use inspection. 6.1 Verification conditions
6.1.1 Environmental conditions
6.1.1.1 Verification room temperature: (20±5)℃. 6.1.1.2 The temperature equilibrium time of the knife-edge ruler in the verification room shall not be less than 2h. 6.1.2 Verification equipment
The main verification equipment is shown in Table 3.
6.2 Verification items
The verification items are shown in Table 3.
Table 3 Verification items and main verification equipment
Verification items
Surface quality
Working edge straightness
Main verification equipment
Grinding surface ruler, third-level gauge block,
$80mm second-level flat crystal, 30mm straight
0.3m blade ruler
Note: "+" in the table indicates items to be inspected; "" indicates items that may not be inspected. 2
First verification
Subsequent verification
In-use inspection
6.3 Verification method
6.3.1 Appearance and surface quality
Visual observation.
6.3.2 Straightness of working edge
JJG63—2007
Use a ground flat ruler with an effective length not less than the length of the working edge of the knife-edge ruler to measure the straightness of the working edge of the knife-edge ruler by the gap method. The knife-edge ruler with a length of 175mm or less is measured by the direct method, and the knife-edge ruler with a length of 175mm or more is measured by the comparison method.
The device for measuring the straightness of the working edge of the knife-edge ruler is shown in Figure 1. Observation direction
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Figure 1 Knife-edge ruler measuring device
1-ground flat ruler; 2-knife-edge ruler to be measured; 3-frosted glass; 4-light box; 5-fluorescent tube; 6-platform; 7-support block Select the length of the ground flat ruler according to the length of the working edge of the knife-edge ruler to be measured. The ground surface ruler is supported by equal height blocks, and the support position is 2/9 of the length from both ends of the ground surface ruler. The light box is located behind the ground surface ruler. When measuring, gently contact the knife-edge ruler to be measured with the working surface of the ground surface ruler. Without applying pressure, swing the knife-edge ruler back and forth about 15° with the working edge of the knife-edge ruler as the axis, and carefully observe the size of the light-transmitting gap between its working edge and the working surface of the ground surface ruler.
When measuring a knife-edge ruler of 175mm or less, observe the light-transmitting gap. If there is no visible light gap or visible blue light, the straightness of its working edge is not greater than 1um; otherwise, the straightness of the working edge is greater than 1um. When measuring a knife-edge ruler of more than 175mm, the maximum gap of the light-transmitting gap is used as the measurement result, and its value can be determined by comparing with the standard gap.
If the uncertainty of the measurement result meets the 1/3 straightness requirement, other methods of measurement are allowed. For the blade ruler with a working edge length of 300mm or more, when measuring, the blade ruler should be held at a distance of 2/9 of the length from both ends and support most of the weight of the blade ruler. The standard gap consists of a Φ80mm secondary flat crystal, a third-level gauge block and a blade ruler with a straightness of no more than 0.3um within 30mm, as shown in Figure 2.
Figure 2 Schematic diagram of standard gap composition
1-gauge block; 2-blade ruler: 3-standard gap; 4-flat product 3
JJG63-2007
The dimensions of the third-level gauge blocks used to make up the standard gap are shown in Table 4. Table 4 Standard gap and corresponding gauge block dimensions
Standard gap (μm)
Gauge block dimensions (mm)
Note: Gauge blocks of other sizes are allowed to be used while ensuring the measurement uncertainty of the standard gap. 6.4 Handling of verification results
A verification certificate shall be issued to knife-edge rulers that meet the requirements of this regulation after verification. If it does not meet the requirements of this regulation, a verification result notice shall be issued, and the unqualified items shall be noted. 6.5 Verification cycle
The verification cycle of knife-edge rulers is 1 year.
Appendix A
A.1 Overview
JJG63—2007
Uncertainty assessment of the straightness measurement results of the working edge of knife-edge rulers Through the uncertainty estimation of the straightness measurement results of the working edge of typical knife-edge rulers, according to the target uncertainty acceptance criterion U≤UI in JJF1130-2005 "Guidelines for the Uncertainty Assessment in the Calibration of Geometric Measurement Equipment", the scientificity, economy and feasibility of the technical requirements, measurement principles, measurement conditions, measurement methods and measurement procedures for the straightness of the working edge of knife-edge rulers proposed in this regulation are confirmed. A.2 Task and target uncertainty
A.2.1 Measurement task
Use the technical requirements, measurement principles, measurement conditions, measurement methods and measurement procedures confirmed by this procedure to measure the straightness of the working edges of 75mm, 225mm and 500mm knife-edge rulers. A.2.2 Target uncertainty U
According to the provisions of 5.3.1.4 of JJF10942002 "Technical Specifications for the Evaluation of Characteristics of Measuring Instruments", the ratio of the expanded uncertainty Uk=2) of the straightness of the working edge of the knife-edge ruler to the absolute value of its maximum allowable error MPEV should be less than or equal to 1:3, that is,
·MPEV
The target uncertainty U corresponding to the technical requirements of the procedure can be obtained from formula (A.1) (see Table A.1). Table A.1 Target uncertainty Ui
Knife-shaped ruler specifications L/mm
Maximum permissible straightness error MPEs/μm
A.3 Principle, method, procedure and conditions
A.3.1 Measurement principle
Contact type, direct measurement or measurement by comparison with a known standard gap. A.3.2 Measurement method
Target uncertainty Ut/μm
In front of the light box, take the straightness of the working surface of a ground flat ruler with an effective length not less than the working edge length of the measured knife-edge ruler as the standard, and measure the straightness of the working edge of the knife-edge ruler directly or by comparison with the standard gap. A.3.3 Measurement procedure
Use a ground flat ruler with an effective length not less than the working edge length of the knife-edge ruler as a standard device; - Use a Φ80mm secondary flat crystal, a third-level gauge block and a knife-edge ruler with a straightness within 30mm not greater than 0.3um to form a standard gap;
- Use a light box composed of fluorescent lamps and frosted glass as the light source; 5
JJG63—2007
Place the knife-edge ruler on the measuring device to measure the straightness of the working edge of the knife-edge ruler; - When measuring, the ground flat ruler is supported by equal height blocks, and the support position is 2/9 of the length from the two ends of the ground flat ruler; - When measuring, the knife-edge ruler is perpendicular to the working surface of the ground flat ruler, and no external force is applied, and it is gently swung back and forth by about 15°; - For a 500mm knife-edge ruler, when measuring, its hand-held position should be 2/9 of the length from the two ends. A.3.4 Measurement conditions
The ground surface ruler has been verified to meet the requirements of JJG740-2005 "Ground Surface Ruler"; the d80mm flat crystal has been verified to meet the requirements of the second-level flat crystal in JJG28--2000 "Flat Crystal"; the gauge block has been verified to meet the requirements of the third-level gauge block in JJG146--2003 "Gauge Block"; the actual size difference of the two 1mm gauge blocks that form the standard gap is less than 0.1um after measurement; the temperature of the calibration room is (20±5)℃;
- The ground surface ruler is placed in the calibration room for temperature balancing time of not less than 10h; the knife-edge ruler is placed in the calibration room for temperature balancing time of not less than 2h; the flat crystal and gauge block are placed in the calibration room for temperature balancing time of not less than 10h; the manufacturing material of the flat crystal is K. optical glass, and the ground surface ruler is made of steel; the operator is trained and is very familiar with the measurement process. A.4 Measuring device
The schematic diagram of the measuring device is shown in Figure A.1.
Observation direction
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Figure A.1 Schematic diagram of measuring device
1—Ground surface ruler; 2—Measured blade ruler: 3—Frosted glass; 4—Light box; 5—Fluorescent tube: 6—Platform: 7—Support block A.5 Mathematical model
The mathematical model obtained from the measurement principle is as follows: O=D+O++On+O+O+O
Where: or
Straightness error;
True straightness value;
Straightness of ground surface ruler;
Standard gap error;
Resolution error;
Surface roughness;
Error caused by temperature;
Error caused by deformation of ruler.
A.6 Uncertainty sources and explanations
Uncertainty sources and explanations are shown in Table A.2. JJG63-2007
Knife-edge ruler working edge straightness measurement uncertainty components sources and explanations No.
Uncertainty component name
Grinding surface flat ruler straightness
Flat crystal flatness
Knife-edge ruler straightness
Resolution error
Surface roughness
Grinding surface flat ruler deformation
A.7 Explanation and calculation of standard uncertainty components A.7.1p
Grinding surface flat ruler straightness
Due to the uncertainty of the knife-edge ruler position during measurement, the grinding surface flatness is taken as the limit value of its straightness. The length of the grinding surface ruler L<300mm, flatness: 0.15um; the length of the grinding surface ruler L≥500mm, flatness: 0.50μm. The measurement uncertainty of the third-level gauge block Ugg=0.1um+1×10-l, flatness: 0.05um (local)
Straightness: 0.30μm within 30mm
Caused by the human eye resolution error, the error limit is 0.20umThe influence of the working edge of the knife-edge ruler and the surface roughness of the grinding surface ruler on the measurement
The influence of temperature on the flat product, the grinding surface ruler, the gauge block and the knife-edge rulerThe influence of the deformation of the grinding surface ruler caused by the dead weight of the grinding surface ruler and the weight of the knife-edge ruler on the measurement.
Class B Assessment
The straightness of the working surface of the ground flat ruler is the standard for measuring the straightness of the working edge of the knife-edge ruler. Due to the uncertainty of the position of the knife-edge ruler placed on the working surface of the ground flat ruler during the measurement process, considering that the straightness of the working surface of the ground flat ruler must be less than its flatness, we take the flatness of the working surface of the ground flat ruler as the maximum value of its straightness in the extreme case.
According to JJG740-2005 Ground Flat Ruler Verification Procedure, the maximum allowable error of the working surface flatness of the ground flat ruler with a length of L<300mm is a,=0.15μm; the maximum allowable error of the working surface flatness of the ground flat ruler with a length of L≥500mm is a2=0.50μm. The conservative estimate is a rectangular distribution, so the distribution factor is 6=0.6, so the uncertainty component ue introduced by the straightness of the grinding surface flat ruler is:
Grinding surface flat ruler length L<300mm, upl=a1b=0.15μm×0.6=0.09μm Grinding surface flat ruler length L≥500mm, up2=a2?b=0.50μm×0.6=0.30μm A.7.2u——Standard gap
Class B assessment
The standard gap is composed of flat crystal, gauge block and standard instrument. The uncertainty component uz introduced by the standard gap is mainly composed of the uncertainty components of the flatness of the flat crystal working surface ui, the center length of the three-equal gauge block u and the straightness of the standard instrument ud.
A.7.2.1uk—Gauge BlockbzxZ.net
JJG63—2007
Verification Certificate
According to the JJG146-2003 Gauge Block Verification Procedure, the measurement uncertainty of the center length of the three equal gauge blocks used to form the standard gap is Ugg=0.1um+1×10~'ln, which is estimated to be normally distributed, corresponding to the coverage factor k=2.576 of the 99% confidence interval. Therefore, the uncertainty component uk introduced by a 1mm gauge block is U0.1μm~0.039μm
unl==2.576
Three standard gauge blocks are needed to build a standard gap, so the uncertainty component u introduced by the gauge block is: u=/3uik=1.732×0.039μm~0.067μmA.7.2.2up
Flat crystal flatness
Class B assessment
$80mm secondary flat crystal working surface local flatness limit value a3=0.05um, estimated to be rectangular distribution, take distribution factor 6=0.6, so the uncertainty component u introduced by flat crystal flatness is: up = ag-b = 0.05μm×0.6= 0.03μmA.7.2.3uid——Straightness of knife edge ruler
Class B assessment
The limit value of straightness of knife edge ruler within 30mm is a4=0.30um, which is estimated to be rectangular distribution. The distribution factor b=0.6 is taken. The uncertainty component u of knife edge ruler straightness is: uja=a4·b=0.30μmx0.6=0.18μum. There is no correlation between the above three uncertainty components, so the uncertainty component ub introduced by the standard gap is:
un=Vui+up+ud
=0.067+0.032+0.18um
=0.19μum
A.7.3ub——Resolution error
Class B assessment
The measurement of the straightness of the working edge of the knife edge ruler mainly depends on the human eye's judgment of the size of the light gap formed by the standard device (see Figure A, 1a). This causes the human eye to distinguish the size of the light gap, which is related to the measurement conditions, the physiological condition of the measurement personnel and the measurement experience. Under normal circumstances, the range of the human eye's resolution error is about ±0.2μm, that is, as=0.2μm, which is conservatively estimated to be a U-shaped distribution with a distribution factor of 6=0.7. The uncertainty component ub caused by this is: ub=as-6=0.2×0.7μm=0.14μm
A.7.4ua—Surface roughness
Class B assessment
The surface roughness of the working edge of the knife edge directly affects the measurement of straightness. In order to control the influence of this factor on the measurement results, the national standard stipulates that the surface roughness of the working edge of the knife-edge ruler is R, = 0.05um, that is, α6 = 0.05um, estimated as a rectangular distribution, and the distribution factor 6 = 0.6, so the uncertainty component uer introduced by the surface roughness of the working edge of the knife-edge ruler is:
uci=a6·b=0.05μm×0.6=0.03μum The influence of the surface roughness of the working surface of the grinding surface flat ruler on the measurement, according to JJG7402005 grinding surface flat ruler verification regulations:
grinding surface flat ruler length L≤330mm, its working surface roughness Ra, = 0.025μm; 8
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