JJF 1189-2008 Calibration specification for length measuring instruments JJF1189-2008 Standard download decompression password: www.bzxz.net
This specification applies to the calibration of length measuring instruments.

This specification refers to the following documents:
JJF1001—1998 General metrological terms and definitions
JJF1059—1999 Evaluation and expression of measurement uncertainty
JJF1094—2002 Evaluation of measuring instrument characteristics
When using this calibration specification, attention should be paid to using the current valid versions of the above-mentioned referenced documents.
1 Scope (1)
2 References (1)
3 Overview (1) 4
Metrological characteristics (1)
4.1 Flatness of flat caps and fixed worktables of vertical length measuring instruments (1)
4.2 Indication variability (1)
4.3 Indication error (1)
4.4 Measurement repeatability (1)
4.5 Indication error of internal dimensions (1)
5 Calibration conditions (1)
5.1 Environmental conditions (1)
5.2 Main standards and supporting equipment (1)
6 Calibration method (2)
6.1 Flatness of flat caps and fixed worktables (2)
6.2 Indication variability (3)
6.3 Indication error (3)
6.4 Measurement repeatability (4)
6.5 Indication error of internal dimension (4)
7 Calibration results (4)
8 Recalibration time interval (5)
Appendix A Evaluation of uncertainty of measurement results (example) (6)
Appendix B Main technical parameters of typical length measuring instruments (8)
Appendix C Auxiliary calibration method when the indication range is >1100mm (9)

National Metrology Technical Specification of the People's Republic of China JF1189
Calibration Specification for Length Measurin2008-03-24Promulgated
Implementation on 2008-06-24
Promulgated by the General Administration of Quality Supervision, Inspection and Quarantine JJF1189—2008
Calibration Specification for Length Measuring Instrument
JJF1189—2008
Replaces JJG55—1984
This specification was approved by the General Administration of Quality Supervision, Inspection and Quarantine on March 24, 2008, and came into effect on June 24, 2008.
Responsible unit: National Technical Committee on Geometry and Length Metrology Main drafting unit: Jiangsu Institute of Metrology, China Institute of Metrology
This specification is entrusted to the National Technical Committee on Geometry and Length Metrology for interpretation. Main drafters of this specification:
JJF1189—2008
Wu Xueliang (Jiangsu Institute of Metrology) Wang Xiaofei (Jiangsu Institute of Metrology) Wang Weinong (China Institute of Metrology) Participating drafters:
Hu Qing (Guiyang Xintian Optoelectronic Technology Co., Ltd.) 2
References
Overview·
4 Metrological characteristics:
JJF1189-—2008
4.1 Variability of flatness indication of flat measuring cap and fixed worktable of vertical length measuring instrument
4.3 Indication error
4.4 Measurement repeatability
4.5 Indication error of internal measurement dimensions
5 Calibration conditions
5.1 Environmental conditions
5.2 Main standards and supporting equipment
6 Calibration method
Variability of flatness indication of flat measuring cap and fixed workbench
6.3 Indication error
Measurement repeatability
Indication error of internal measurement dimensions
Calibration results|| tt||Recalibration time interval
Appendix A
Evaluation of uncertainty of measurement results (example) Appendix B
Appendix C
Main technical parameters of typical length measuring instruments
Auxiliary calibration method when the indication range is 1100mm (1)
(1)
(3)
(6)
1 Scope
This specification applies to the calibration of length measuring instruments.
JJF1189—2008
Calibration specification for length measuring instrument
References
This specification refers to the following documents: SNOH
ONIHSE
JJF1001-1998General metrological terms and definitions》JJF1059—199
JJF1094-
Special specifications for measuring instruments. When measuring uncertainties, you should pay attention to the following when using this calibration
type length measuring instrument. The currently valid length measuring instrument is a combination of metallurgy, mechanics or opto-mechanical-electrical length measuring instrument. The structural type is a vertical length measuring instrument and a horizontal length measuring instrument. The base, measuring seat and measuring reading or display of the length measuring instrument are composed of 4 metrological characteristics of mechanical parts. The length measuring instrument is used to measure the length standard: the length of the continuous scale is directly measured or the comparison measurement method is used to measure the size of the gauge block, gauge, and smooth surface.
Flat measuring cap and 3D
4.2 Indication variability
Measuring instrument with flat measuring cap
Indication variability
METROLOG
When using spherical measuring cap
4.3 Indication error
Measurement repeatability
Indication error of internal measured dimension
Calibration conditions
5.1 Environmental conditions
Ruler or grating, etc.) and
calibrators. The ambient temperature of thread gauges and precision
should generally be controlled within (20±3)℃, or in accordance with the provisions of relevant technical requirements. 5.2 Main standards and supporting equipment (see Table 1) Calibration items
Flatness of flat measuring cap and fixed workbench
Indication variability
Indication error
Measurement repeatability
Indication error of internal measurement dimensionwww.bzxz.net
Calibration method
JJF1189—2008
Table 1 Main standards and supporting equipment
Name of standard||tt| |Flat crystal
Standard ball
Laser interferometer system
Measuring range
$60mm, g100mm
Diameter<10mm
(0~1000）mm
(1~10）m
(0~1000）mm
$14mm, g30mm,
Check the appearance and confirm that there are no factors that affect the calibration metrological characteristics. Perform the instrument startup and preparation procedures as specified in the instrument instruction manual. Level 2
Accuracy level
2nd or 3rd grade
Better than 1.1μm/m
2nd or 3rd grade
U<0.5μm, k=2
The calibration method of vertical length gauge is the same as that of horizontal length gauge. In the following text, the calibration method of vertical length gauge is generally not described separately, but the fixed workbench is treated as a measuring cap. 6.1. Flatness of plane measuring cap and fixed workbench The flatness of plane measuring cap and fixed workbench is measured by light wave interference method using flat crystal (Figure 1a). Incident
(a) Interference fringe image
(b) Calculation of flatness
Figure 1 Schematic diagram of light wave interference principle
Before measurement, the flat crystal must be kept at a constant temperature for at least 1h. Place the flat crystal on the surface to be measured, and form a very small angle 6 with the surface to be measured, and illuminate it with a monochromatic light source. Adjust the angle between the flat crystal and the surface to be measured to form 3 to 4 interference fringes in the field of view. If the interference fringes are straight, parallel to each other, and evenly distributed, it means that the flatness of the surface to be measured is very good; if the interference fringes are curved (Figure 1b), it means that the flatness error AP is:
P=(a/6)×(a/2)
Where: α-the curvature of the interference fringes;
6. The distance between the two interference fringes;
λ-the wavelength of the light wave.
When the interference fringes are circularly symmetrical (as shown in Figure 2), estimate the number of interference fringes n observed, and take the product of the number of interference fringes n and the half-wavelength λ/2 of the light source used as the flatness error. Figure 2 shows symmetrical interference fringes in a circle
6.2 Indication variability
6.2.1 Indication variability when using a flat cap The indication variability of a flat cap is calibrated with a standard ball. Before calibration, a flat cap is installed on the measuring (axis) seat and the tailstock measuring rod. For instruments with a cap adjustment mechanism, this item does not need to be calibrated. Place a standard ball between the two flat caps, adjust the standard ball position so that the standard ball contacts the center position of the flat cap measuring surface, and measure the indication three times in succession: the standard ball is measured three times at a distance of 3 mm above, below, and 3 mm before and after the center position; the average of the three indications at each point is taken, and the difference between the maximum and minimum values ​​of the five averages is the indication variability of the flat cap.
6.2.2 Indication variability when using a spherical cap For instruments with a cap adjustment mechanism, this item does not need to be calibrated. The indication variability of a spherical cap is calibrated with a 10 mm gauge block. Before calibration, a spherical cap is installed on the measuring (axis) seat and the tailstock measuring rod.
The process of measuring the variability of indication is as follows:
a) Install a 10mm gauge block on the workbench, make the two spherical measuring caps contact the center of the measuring surface of the gauge block, adjust the workbench to find the turning point of the indication, and measure the indication of the gauge block 3 times: b) Remove the measuring (axis) seat, rotate a spherical measuring cap about 90°, and then make the measuring cap contact the center of the measuring surface of the gauge block, and directly measure the indication of the gauge block 3 times (without adjusting the workbench). Repeat step b) and measure a total of 4 groups of indications. Take the average of each group of 3 indications, and the difference between the maximum and minimum values ​​of the 4 averages is the indication variability when using the spherical measuring cap. 6.3 Indication error
For a length measuring instrument with an indication range of ≤1100mm, select 5 gauge blocks with a minimum length of 10mm and a maximum length of not less than 90% of the indication range. The sizes of the remaining gauge blocks should make the calibration points basically evenly spaced. For a length measuring instrument with an indication range of >1100mm, some auxiliary measurements are required. The measurement method is shown in Appendix C. Install spherical measuring caps on the measuring (axis) seat and the tailstock measuring rod and set the zero position. Select a group of gauge blocks according to the calibration points, install the gauge blocks on the workbench respectively, and measure the length of the gauge blocks. Measure each gauge block 3 times and record the indication of the length measuring instrument. The maximum difference between the indication of the length measuring instrument and the actual value of the gauge block at each calibration point is the indication error of the calibration point:
A;=max[(LL)-L]
Where: Li—the indication of the length measuring instrument measuring the i-th measurement of the i-th gauge block; L. ——the indication of the length measuring instrument when measuring zero position; (2)
-the reference value of the first gauge block;
JJF1189-2008
-the serial number of the gauge block, = 1, 2,, 5; j-the serial number of the measurement, j = 1, 2, 3. 6.4 Measurement repeatability
The experimental standard deviation of the indication of the group of values ​​is the range value of the 5 groups of indications divided by the range coefficient: Si
Where: R,—the range of the 3 indications of a certain calibration point, that is, the range between the maximum and minimum values. =1
a range coefficient, 3 measurements, take the combined sample standard deviation s, which is the repeatability calibration result: 1
6.5 Internal measurement dimension indication lesson
6.5.1 Use small measurement two internal measurement dimension indicators
According to the user manual:
Install on the workbench
Remove the $14mm
on the measuring (axis)
mm ring gauge. Adjust
Replace with a 30mm
small measuring hook. Read the gauge after the turning point of the value. Adjust the workbench to find its indication turning point
Repeat 3 times. The maximum value of the difference between the
value and the actual hole diameter difference is the difference between the two ring gauges.
In the formula: d3o and d14
d3oi and d14i
Am-maxka
mm ring gauge and
Use the length measuring instrument to measure the
value serial number,
6.5.2 Use the large measuring money to measure the inner dimension indication according to the user manual. Install $30 on the workbench and repeat 3 times.
After reading, repeat
the inner measurement
indication error of the small measuring hook.
mm ring gauge reference value;
Tail seat bag
14mm ring gauge to obtain the inner indication;
day measurement
. Adjust the workbench to its indication and dismantle the bureau gauge.
Read the value, repeat 3 times.
Remove the g30mm ring gauge and replace it with a 50.mm ring gauge. Adjust the workbench to find the turning point of the indication and then read the value, repeat CHIN
3 times.
The difference between the indications of the two ring gauges and the actual hole
The indication error of the inner dimension of the measuring hook.
Am=max[(dsoi-dso,)-(dso-dso)]Where: dso and d3o—
reference values ​​of the 50mm ring gauge and the g30mm ring gauge; dsoi and d3oi
Calibration result
-the indication obtained when using the length measuring instrument to measure the g50mm ring gauge and the g30mm ring gauge; a serial number of the measured value, i, j=1, 2, 3. (6)
A calibration certificate is issued for the calibrated length measuring instrument. The calibration certificate shall give the measurement results of each calibration item and the indication error 4
and the expanded uncertainty of the measurement results.
JJF1189-2008
When the user requires, the conformity judgment can be made based on the maximum allowable error of the metrological characteristics provided by the user, and the conclusion shall be listed in the calibration certificate. The expanded uncertainty of the measurement results shall be considered in the conformity judgment. 8
Recalibration interval
Under the condition of regular interim verification, the recommended recalibration interval is 1 year. OH
DNISTnd XE
Appendix A
A.1 Overview
JJF1189—2008
Evaluation of uncertainty of measurement results (example) When calibrating the indication error of the length measuring instrument, install the spherical measuring cap on the measuring (axis) seat and the tailstock measuring rod, adjust to achieve the best measurement state, and set the zero position. Move the measuring (axis) seat, install the gauge block of corresponding length on the workbench, align the center of the gauge block working surface with the spherical measuring cap, and adjust the workbench so that the gauge block working surface is perpendicular to the axis of the spherical measuring cap. Read the length gauge indication from the reading device. The deviation between the length gauge indication and the actual value of the gauge block is the length gauge indication error. The length change caused by the temperature of the gauge block is corrected.
A.2 Mathematical model
A: =(L, - Lo) - L
Where: △-calibration point indication error;
L calibration point indication;
Lo——zero point indication;
L-length of the gauge block under standard conditions.
A.3 Uncertainty evaluation of input quantity
A.3.1 Repeatability u(L,)
The source of standard uncertainty of input quantity L, is mainly the measurement repeatability of the length gauge, which can be obtained through multiple measurements and evaluated by Class A method.
Repeatability uses the data obtained during the field calibration process. In this example, s.=0.06um, then
u(L)=0.06um
A.3.2 Standard uncertainty u(L.) of input quantity L. A.3.2.13 The expanded uncertainty of the equal block is U=0.10μm+1×10-6L. When the length of the block is equal to 100mm, U=0.2um, and the block certificate gives the inclusion factor (k=2.8), then U_0.2um~0.07μm
u(Ls10o)=
A3.2.23 The thermal expansion coefficient of the equal block is α-(11.5 soil 1)×10-6℃-1. When there is an error in temperature measurement, it will cause the standard uncertainty u(L2). Assuming that the temperature measurement error does not exceed △, = 0.1℃, obeys uniform distribution, k = /3, then
u(L2) = L.4,: α/k = (100×10μm×11.5×10-6℃-1×0.1℃) //3~0.07μmA.3.2.3 Uncertainty of thermal expansion coefficient of gauge block, standard uncertainty u (L) caused when temperature deviates from standard temperature by 20C
The uncertainty of thermal expansion coefficient of gauge block is U. = 1X10-6℃C-1, obeys uniform distribution, then the inclusion factor k = /3 = 1.73, when the temperature deviates from standard temperature by 9-1℃: u(L) = LU. ·2/ k=(100×103μm×1×10-℃-1×1℃C)/1.73=0.06μm6
A.4 Combined standard uncertainty
A.4.1 Sensitivity coefficient
JJF1189—2008
L, sensitivity coefficient: cr=a./aL,=1
L. Sensitivity coefficient, c2=a;/aL. =—1L, sensitivity coefficient: C3=a,/aL=1
A.4.2 Summary of standard uncertainty
Standard uncertainty component u(z)
Calculation of combined standard uncertainty
Sources of uncertainty
Repeatability of measurement
Uncertainty of block length
Uncertainty of temperature measurement
Uncertainty of thermal expansion coefficient
The above quantities are independent of each other, so the combined standard uncertainty is: standard uncertainty/μm
u. =V0.062+0.07+0.072+0.06°μm=0.13umA.5 Expanded uncertainty
Take k=2, then
U=uc.k=0.13μm×2=0.26μm
Appendix B
Metrological characteristics
Flatness of flat measuring cap and fixed
Workbench
Variability of indication
JJF118 9--2008
Main technical parameters of typical length measuring instrument
Table B.1 Main technical parameters of typical length measuring instrument
Technical parameters
Flat measuring cap: 0.15μm
Worker Hshu
Indication error
Hsrrande
Inner measuring month
Note: L is the measurement
value error
Use spherical measuring cap: 0.2um
1um+5×10-L
(20 and a half
+ioxig
METROL
Environmental conditions
+3)C , 0.5℃/h
℃, 0.5℃/h
C, 0.2℃/h
(20±:
(20±1
(20±0.5)
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