Calibration Specification for Micrometers for Measuring Inside Dimension
Some standard content:
National Metrology Technical Specification of the People's Republic of China JJF1091-2002
Calibration Specification for Micrometers for Measuring Inside Dimension2002-1104 Issued
Implementation on 2003-05-04
Issued by the General Administration of Quality Supervision, Inspection and Quarantine JJF1091—2002
Calibration Specification for
Micrometers for Measuring Inside DimensionJJF1091—2002
Replaces JJG378—1985
JJG23—1988
This specification was approved by the General Administration of Quality Supervision, Inspection and Quarantine on November 4, 2002, and came into effect on May 4, 2003.
Responsible unit: National Technical Committee on Geometry and Engineering Parameters Major drafting unit: Heilongjiang Metrology Verification and Testing Institute Participating drafting unit: Qinghai Measuring Tools and Blades Co., Ltd. The responsible unit is responsible for interpreting this specification
Main drafters of this specification:
Zhang Liping
Liang Yuhong
Ma Zhonghuan
Participating drafters:
Liu Wenbin
Zhang Hongling
Li Xuhui
JJF1091-2002
(Heilongjiang Metrology Verification and Testing Institute)
(Heilongjiang Metrology Verification and Testing Institute)
(Jilin Metrology Verification and Testing Institute)
(Heilongjiang Metrology Verification and Testing Institute)
(Qinghai Measuring Tools and Blades Co., Ltd.) (Heilongjiang Metrology Verification and Testing Institute)
Scope·
References·
Overview·
Metrological characteristics
Measuring force·
Grade width and width difference
JJF1091-2002
Distance from the end edge of the cone of the differential cylinder to the scaled surface of the fixed sleeve4.4
Relative position of the end face of the cone of the differential cylinder and the millimeter scale of the fixed sleeve4.5
Surface roughness of the measuring surface:
Arc radius and element line parallelism of the measuring claw measuring surface4.7Indication error,||tt ||4.8 Diameter deviation and diameter variation of the ring gauge used for calibration 5 Calibration conditions
5.1 Environmental conditions
5.2 Measuring standards and other equipment
6 Calibration items and calibration methods:
Grade width and width difference:
Distance from the end edge of the differential cylinder cone to the scaled surface of the fixed sleeve Relative position of the end face of the differential cylinder cone and the millimeter scale of the fixed sleeve 6.4
Surface roughness of the measuring surface
Arc radius and element line parallelism of the measuring surface of the measuring claws·…6.7 Indication error
6.8 Diameter deviation and diameter variation of the ring gauge used for calibration Expression of calibration results
8 Recalibration time interval||tt ||Appendix A
Analysis of measurement uncertainty of calibration results of indication error of internal micrometer Appendix B
Analysis of measurement uncertainty of calibration results of indication error of aperture micrometer Appendix C
Contents of calibration certificate
(4)
(4)
1 Scope
JJF1091—2002
Calibration specification for micrometers for measuring internal dimensions
This specification is applicable to the calibration of internal micrometers with a graduation value of 0.01mm and a measuring range of (5~150)mm and aperture micrometers (three-jaw internal micrometers) with graduation values of 0.005mm and 0.01mm and a measuring range of (6~200)mm.
References
This specification refers to the following documents:
GB/T6314—1986 Three-jaw internal micrometer JB/T10006—1999 Internal micrometer
JJF1001—1998 General metrological terms and definitions JJF1059-1999 Evaluation and expression of measurement uncertainty When using this specification, attention should be paid to the use of the current valid versions of the above-mentioned references. Overview
The internal micrometer is a measuring instrument with a spiral pair structure that converts rotary motion into linear motion. It is mainly used to measure internal dimensions. Its appearance structure is shown in Figure 1. Micrometer screw
Moving measuring jaws
Fixed measuring jaws
Locking device
Fixed sleeve
Differential force measuring device
Aperture micrometer is a measuring instrument that uses the rotation (or movement) of a threaded cone (or smooth cone) to push three measuring jaws to measure the aperture. Its appearance structure is shown in Figure 2. Internal micrometers are usually made into the following series (unit: mm): 5~30; 25~50; 50~75; 75~100; 100~125; 125~150. Aperture micrometers are usually made into the following series (unit: mm): 6~8: 8~10; 10~12; 11~1414~17; 17~20; 20~25; 25~30; 30~35; 35~40; 40~50; 50~60; 60~70; 70~80; 80~90; 90~100100~125; 125~150; 150~1
175; 175~200.
4 Metrological characteristics
4.1 Measuring force
Measuring melon
JJF1091-2002
Fixed sleeve differential cylinder force measuring device
4.1.1 The measuring force of the internal micrometer is (5~9)N. 4.1.2 The measuring force of the aperture micrometer is (10~35)N. 4.2 Scale width and width difference
The scale width of the fixed sleeve longitudinal scale and the scale on the differential barrel is (0.15~0.20)mm, and the scale width difference is within the range of (0~0.03)mm.
4.3 The distance from the end edge of the differential barrel cone to the scale surface of the fixed sleeve The distance from the end edge of the differential barrel cone to the scale surface of the fixed sleeve is within the range of (0~0.4)mm, see Figure 3a.
4.4 The relative position of the end face of the differential barrel cone and the millimeter scale of the fixed sleeve When the zero scale of the differential barrel is aligned with the longitudinal scale of the fixed sleeve, the end face of the differential barrel cone should be tangent to the right edge of the millimeter scale of the fixed sleeve. If not tangent, the pressure line is within the range of (0~0.05) mm, and the offline line is within the range of (0~0.1) mm.
4.5 Surface roughness of measuring surface
Surface roughness of measuring surface of measuring jaws R, 0.2um. 4.6 Arc radius and element line parallelism of measuring jaws measuring surface 4.6.1 The arc radius of the measuring surface of the measuring jaws for measuring internal dimensions on the micrometer is less than half of the measuring lower limit dimension. 4.6.2 The element line parallelism of the internal micrometer should be calibrated: the new one is within the range of (0~0.002) mm, and the one in use and after repair is within the range of (0~0.003) mm. 2
4.7 Indication error
JJF1091—2002
The indication error of measuring internal dimensions on the micrometer is within the range specified in Table 1. Table 1 Indication error of micrometer for measuring internal dimensions Name of calibrated scale
Aperture micrometer
Internal measuring micrometer
Measuring range
>40~100
>100~200
>50~100
>100~150
4.8 Indication error of ring gauge diameter deviation and diameter variation used for calibration
The diameter deviation and diameter variation of ring gauge used for measuring internal dimensions are within the range specified in Table 2. Table 2 Diameter deviation and diameter variation of ring gauges used for calibration of internal dimension micrometers Name of calibrated gauge
Internal measurement micrometer
Aperture micrometer
Nominal size of ring gauges used for calibration
50, 75
100, 125
6.8, 10, 14, 17, 25, 35
50, 70, 90
125, 175
Diameter deviation
Note: As calibration, it does not judge whether it is qualified or not. The above metrological characteristics are for reference only. Calibration conditions
5.1 Environmental conditions
Diameter variation
5.1.1 The internal dimension micrometer to be calibrated and the calibration equipment shall be kept at a room temperature of (20±5)℃ for not less than 4 hours for equilibrium.
5.1.2 The calibration ring gauge should be kept at a room temperature of (20±1)℃ for no less than 4 hours. 5.2 Measuring standards and other equipment
Measuring standards and other equipment are shown in Table 3.
Table 3 Measuring standards and other equipment
Calibration items
Grade width and width difference
Main calibration instruments
2.5-level dynamometer
Tool microscope
Calibration items
JJF1091-2002
Table 3 (continued)
Distance from the end edge of the differential tube cone to the scaled surface of the fixed sleeve Relative position of the end face of the differential tube cone and the millimeter scale of the fixed sleeve Surface roughness of the measuring surface||tt ||Indication error of arc radius and element line parallelism of measuring claw measuring surface
Diameter deviation and diameter variation of ring gauge used for calibration 6 Calibration items and calibration methods
Main calibration instruments
2nd-grade feeler gauge or tool microscope
Surface roughness comparison sample
Lever micrometer or radius template
3rd-grade standard ring gauge or 5th-grade gauge block and gauge block accessories Horizontal optical gauge and 4th-grade gauge block or aperture measuring instrument First check the appearance and make sure there are no factors that affect the calibration characteristics before calibration. 6.1 Force measurement
Measure with a dynamometer with an accuracy level of 2.5. 6.1.1 Make the cylindrical measuring surface inside the scale contact with the flat probe of the dynamometer and measure its force value. 6.1.2 Measure at the upper and lower measurement limits of the aperture micrometer respectively. During measurement, the three jaws of the aperture micrometer should be subjected to force at the same time with the aid of a V-block, and then the force value should be measured, as shown in Figure 4. Dynamometer
Aperture micrometer
V-block
6.2 Graduation line width and width difference
Measured on a tool microscope. At least three evenly distributed graduations should be drawn for measurement on the differential cylinder and the fixed sleeve. The graduation line width difference is determined by the difference between the maximum and minimum values. 6.3 The distance from the end edge of the differential cylinder cone to the fixed sleeve graduation surface is measured on a tool microscope, or by comparison with a feeler gauge with a thickness of 0.4 mm. The measurement should be carried out at no less than three positions within one rotation of the differential cylinder. 6.4 Relative position of the end face of the differential cylinder cone and the millimeter scale of the fixed sleeve When the lower limit of measurement is adjusted correctly, rotate the differential cylinder to align its zero scale with the longitudinal scale of the fixed sleeve, and observe whether the end face of the differential cylinder cone is tangent to the right edge of the millimeter scale of the fixed sleeve. If not, rotate the differential cylinder to make it tangent, and read the offset of its zero scale to the longitudinal scale of the fixed sleeve according to the differential cylinder. The offset is the value of offline or press line, see Figure 5.
Offline 0.02mm
6.5 Surface roughness of measuring surface
Calibrate with surface roughness comparison sample.
JJF1091-2002
6.6 Arc radius and element line parallelism of measuring jaw measuring surface Press line 0.02mm
6.6.1 Measuring internal dimensions The arc radius of the measuring surface of the micrometer jaw is measured by the radius template using the light gap method. Only light gaps are allowed on both sides of the sample.
6.6.2 The parallelism of the element lines of the measuring surface of the internal micrometer jaws is measured with a lever micrometer. When measuring at both ends of the jaws, the difference in the size obtained is the element line parallelism. 6.7 Indication error
The indication error of each point is calculated as follows:
e=L,-L,
Where: L is the reading of a micrometer;
L,—the actual size of the standard ring gauge or gauge block. The indication error of the internal dimension micrometer is calibrated with a 3rd-class standard ring gauge that meets the requirements of Table 4, evenly distributed within the entire scale range of the fixed sleeve and the differential cylinder, and at least 5 points. It can also be calibrated with an internal dimension consisting of a 5th-class gauge block and gauge block accessories. When calibrating, the zero position should be calibrated first, and then the calibration should be carried out on the middle section of the ring gauge working surface. At least three positions should be evenly converted, and each position should be calibrated repeatedly (3~5) times, and the arithmetic mean should be taken as the measurement result. The calibration of the aperture micrometer with an extension rod should select at least one of each set of rulers and install the extension rod, and then calibrate according to the above method.
6.8 Diameter deviation and diameter variation of the calibration ring gauge The calibration ring gauge diameter is measured by comparison method on a horizontal optical gauge with the internal dimensions composed of 4 equal gauge blocks and gauge block accessories, or measured with an aperture measuring instrument with equal accuracy. The upper, middle and lower sections of the ring gauge should be measured, and each section should be measured in two mutually perpendicular diameter directions. The average value of the measured values of each section is taken as the actual size of the section, and the actual size of the middle section of the ring gauge is taken as the calibration result. The difference between the maximum and minimum values of the 6 measured dimensions is the diameter variation.
Name of calibrated ruler
Aperture micrometer
Internal micrometer
Measuring range
>20~40
>40~100
>100~200
>50~75
>75~100
>100~125
>125~150
JJF1 091—2002
Table 4 Standard ring gauge dimensions for calibrating internal dimension micrometers Measuring range of each ruler
Note: "A" in the table is the measuring lower limit dimension of the ruler. Calibration result expression
Standard push ring gauge dimensions
A,A+0.62,A+1.24,A+1.86,A+2
A,A+0.62,A+1.24,A+1.86,A+3||tt| |A,A+1.12,A+2.24,A+3.36,A+4.50,A+5A,A+1.12,A+3.24,A+5.36,A+7.50,A+10A,A+5.12,A+10.24,A+15.36,A+20.50,A+2510.12,15.24,20.36 ,26.50,3030.12,35.24,40 .36,46.50,5055.12,60.24，65.36,70.50，7580.12，85.24，90.36，95.50，100105.12，110.24,115.36，120.50，125130.12，135.24，140.36，145.50，150A calibration certificate is issued to the calibrated internal dimension micrometer. The contents of the calibration certificate are shown in Appendix C.
8 Recalibration time interval
Depending on the usage of the calibrated internal dimension micrometer, the recalibration time interval shall be determined by the user. Appendix AbzxZ.net
JJF1091-2002
Analysis of measurement uncertainty of calibration results of indication error of internal micrometerA.1 Measurement method
The indication error of internal micrometer is calibrated with standard ring gauge. A.2 Mathematical model
The indication error of internal micrometer:
e=LL,+L,a.At,-L,a,At
Where:
L--indication of internal micrometer (under 20℃); L,--actual size of standard ring gauge (under 20℃); α, and α,--linear expansion coefficients of internal micrometer and ring gauge respectively; At and At,--values of internal micrometer and ring gauge deviating from reference temperature 20℃ respectively. A.3 Variance and sensitivity coefficient
Because △t and At come from the same thermometer and are related, the mathematical processing process is very complicated. Therefore, we use the following method to transform the correlation into the uncorrelation to simplify the mathematical processing process. Let.=α,-α.
LL,~L,
8, = At -At
α=α=α
At =At, =At
e = L - L, + L'α,At, -L'α,At, + L,'a,-At, -L,'α,At,=L.-L.+L.At..+Lα-o
C,=ae/a,=l; C2=aela,=-1
Cy=aela.=.At; ca=ael0o,=La
u，u2，u3，u represent the uncertainties of L, L,,,, respectively u=u? (e)=ui+uz+ (L·At)\uj+ (Lα)\uA.4 Standard uncertainty - list
Standard uncertainty see Table A.1.
A.5 Calculation of standard uncertainty components
A.5.1 Uncertainty components u and degrees of freedom v1 of measurement repeatability estimation When L=10.12mm, repeat the measurement 10 times at 10.12mm. The experimental standard deviation is obtained by Bessel's formula
s=0.42μm
u,=0.42//3=0.24μm
=n-1=9
When L=150mm, repeat the measurement 10 times at 50mm, and get the experimental standard deviation from Bessel formula
ui=0.74//3=0.43μm
V=-1=9
A.5.2 Uncertainty components u2 and v2(An) given by the standard ring gauge
Standard uncertainty components
Quantity u(α)
Standard uncertainty components
Quantity u(α)
Uncertainty source
Measurement repeatability
Uncertainty of standard ring gauge
Internal measurement Linear expansion coefficient difference between micrometer and
ring gauge
Temperature difference between internal micrometer and
ring gauge
Uncertainty source
Measurement repeatability
Uncertainty of standard ring gauge
Linear expansion coefficient difference between internal micrometer and
ring gauge
Temperature difference between internal micrometer and
ring gauge
JJF10912002
Standard uncertainty
Value u(x)
0.58×10*6
u.=0.64μm
L· At = 10.12
×10×5pm
Lα=10.12×
10×11.5×
10-°μm℃-1
Ven =57
Standard uncertainty
value u(x)
0.58×10-6
u.=1.1μm
L·At =150 ×
10°×5um℃
Lg=50×10
×11.5×10-6
Ve=107
Te,/u(x,)/μm
Ic;lu(x.)/μm
L=10.12mm
Degree of freedom
L=150mm
Degree of freedom
The uncertainty of the standard ring gauge is obtained by combining the uncertainty of the aperture measuring instrument and the uncertainty of the ring gauge, and its relative uncertainty is 10%. The uncertainty of the aperture measuring instrument is calculated according to the formula = (0.5+L/300+H/100)um, where the units of L and H are mm, and H is the depth of the ring gauge hole. The uncertainty of the ring gauge is 1um, h=2. When L=10.12mm, then H=10mm, U=0.63+=1.2um, uz=U/2=0.6μm, V=
x(10%)-2= 50
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