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National Metrology Technical Specification of the People's Republic of China JJF1064-2000
Calibration Specification for Coordinate Measuring Machines
Promulgated on 2000—03—07
Implementation on 2000-07-01
Promulgated by the State Administration of Quality and Technical Supervision
JJF1064—2000
Calibration Specification for Coordinate Measuring Machines JJF1064-2000
Replaces JJG799—1992
This specification was approved by the State Administration of Quality and Technical Supervision on March 7, 2000, and came into effect on July 1, 2000.
Responsible unit: National Technical Committee for Geometric Measurement and Length Metrology Main drafting unit: China National Institute of Metrology Participating drafting unit: Qingdao Qianshao Langpu Measurement Technology Co., Ltd. China Aviation Precision Machinery Research Institute
Mechanical Science Research Institute
This specification is entrusted to the National Technical Committee for Geometric Measurement and Length Metrology to be responsible for interpreting this specification Main drafters:
Wang Weinong
Wang Zhengqiang
Participating drafters:
Zhu Zhixian
Peng Dongming
Li Xiaopei
JJF 1064--2000
(China National Institute of Metrology)
(China National Institute of Metrology)
(Qingdao Qianshao Langpu Measurement Technology Co., Ltd.) (China Aviation Precision Machinery Research Institute)
(Mechanical Science Research Institute)
References·
Terms and definitions
Metrological performance requirements
General technical requirements:
Calibration conditions
Calibration items and calibration methods
Recalibration time interval
J.JF1064-2000
Appendix A Additional calibration items for large coordinate measuring machines Appendix B
Examples of uncertainty assessment of measurement results
Appendix C
Redetermination of maximum permissible error
Appendix D
Appendix E
Appendix F
Contents of calibration certificate
Task-oriented calibration
Intermediate inspection
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JJF 1064—2000
Calibration specification for coordinate measuring machines
This specification applies to the calibration of coordinate measuring machines with orthogonal coordinate systems using contact probes. It does not include the calibration of rotary tables on coordinate measuring machines.
2 References
The clauses contained in the following documents constitute the clauses of this specification through reference in this specification. When this specification is published, the versions shown are valid. All standards, specifications or regulations will be revised, and the parties using this specification should explore the possibility of using the latest versions of the following documents. National Standard of the People's Republic of China GB/T16857.2—1997 eqV[ISO10362-2：1994 Coordinate metrology: Part 2: Performance evaluation of coordinate measuring machines Metrology verification procedures of the People's Republic of China JJG146-1994 Gauge blocks Metrology technical specification of the People's Republic of China JJF1001-1998 General metrological terms and definitions Technical specification of the People's Republic of China for metrology JF1059—1999 Evaluation and expression of uncertainty in measurement ISO/DIS 103601 Geometrical Product Specifications (GPS) Acceptance test and reverification test for coordinate measuring machine (CMM) tions-Part I: Terms and Defini-
EAL- G17 European cooperation for Accreditation of Laboralories Guideline: Calibra-lion of Coordinate Measuring Machine (First edition, January 1995) BS 6808: Coordinate Measuring Machines, Part 3. Code of Practice: 1989 VDI/VDE2617 Part 5: Accuracy of coordinate measuring machines-their checking
-Supervision by mechanical standards-Charaeteristic parameters and National Standard of the People's Republic of China GB/T 15481-1995 General requirements for the competence of calibration and inspection laboratories 3 Terms and definitions
3.1 Coordinate measuring machine
A measuring system that detects the three-dimensional coordinates of points on the surface of a workpiece by relative movement of the probe system and the workpiece. 3.2 Calibration of a coordinate measuring machine
A set of operations to determine, under specified conditions, the relationship between the value indicated by the coordinate measuring machine and the value reproduced by the corresponding standard.
3.3 Indication error of a coordinate measuring machine
The indication of a coordinate measuring machine minus the (conventional) true value of the measured quantity. 3.4 Measurement plan of coordinate measuring machine
When using coordinate measuring machine to measure a workpiece, the installation position of the workpiece in the measurement space, the probe configuration of the measuring machine, the number and distribution of detection points, the measurement method (such as point measurement, scanning measurement, centering measurement, etc.), environmental conditions, evaluation methods, etc. 3.5 Task-oriented calibration of coordinate measuring machine
Calibration of coordinate measuring machine under specified conditions according to specific measurement tasks and specific measurement plans.
3.6 Physical length standard
A physical standard measuring tool that can reproduce the length value between two points and can be traced back to the national benchmark 3.7 Indication error (E) of length measurement of coordinate measuring machine The difference between the indicated value and the true value of the distance between two points on the physical length standard measured by the coordinate measuring machine. 3.8 CMM axial length measurement indication error (E,) Length measurement indication error along the CMM motion axis. 3.9 Probing error (P)
Error determined by measuring the indication variation range of the standard ball radius using a CMM. The P value is applicable to the case where the standard ball is placed at any position in the CMM measurement space. 4 Overview
CMMs can be used to perform dynamic, motorized or automatic measurements on three-dimensional parts of various complex shapes. Through human-computer dialogue, all measurement data collection and data processing can be completed under computer control. The measurement objects of CMMs are diverse, and different measurement schemes can be used for a measured parameter. Due to the different measurement uncertainties at different points in the measurement space, different measurement schemes have different effects on the uncertainty of the measurement results. Therefore, the calibration of CMMs should be task-oriented calibration, and length measurement is a typical measurement task; the measurement results of probing errors provide the directional characteristic parameters of CMMs. The combination of length measurement indication error and detection error is an indicator for evaluating the performance of coordinate measuring machines. This specification is used as an approximate coordinate measuring machine calibration. For measurement tasks with special requirements, such as measurement tasks with high traceability requirements, task-oriented calibration should be used as much as possible. It can be carried out using the substitution method or error synthesis method (see Appendix E). 5 Metrological performance requirements
5.1. Maximum permissible indication error (MPE) of length measurement: The maximum permissible indication error (MPEE: in m) of length measurement is the maximum value of indication error allowed when the coordinate measuring machine performs length measurement, and can be expressed by any of the following three expressions: MPE = ±[(A + L/K) ≤ BI (Figure 1) MPEE = ± (A + L/K) (see Figure 2)
MPEe = ± B (see Figure 3)
Where: A is a constant term, μni, provided by the coordinate measuring machine manufacturer or determined by the user as required; L is the measured length, mm;
K is a dimensionless constant, provided by the coordinate measuring machine manufacturer or determined by the user as required; (1)
B is the maximum value of MPE, um, provided by the coordinate measuring machine manufacturer or determined by the user as required. 2
JJF 1064-2000
Note: The maximum permissible (length measurement indication detection) error given by the manufacturer is an indicator under specific conditions. Specific conditions include ambient temperature, probe configuration, etc. These specific conditions may not match the actual conditions of use. When the user determines the maximum allowable error, the user should also determine the conditions under which the indicator applies.
-A( +AR)
-B(-B)
MPE:(MPE)
-A(-A)
MPER(MPELI)
5.2 Maximum allowable indication error (MPE) for axial length measurement: B(B)
-B(-B)
MPE (MPE)
The maximum allowable indication error (MPEEL, in um) for axial length measurement is the maximum value of the indication error allowed when the coordinate measuring machine measures the length along the direction of the moving axis, expressed in any of the following three expressions: MPEE1 =±［(A ＋ L/K)≤ B] (Ghost Figure 1)MPE=±(A+L/K) (see Figure 2)
MPEE1=±B, (see Figure 3)
Where: A,—constant term, um, provided by the coordinate measuring machine manufacturer or determined by the user as needed; L--measured length, mm;
K, dimensionless constant, provided by the coordinate measuring machine manufacturer or determined by the user as needed; (4)
B--maximum value of MPEEi, um, provided by the coordinate measuring machine manufacturer or determined by the user as needed.
5.3 Maximum allowable probing error (MPEp)
The maximum allowable probing error (MPEp, in um) is the maximum value allowed for the probing error of the coordinate measuring machine, and its value is provided by the coordinate measuring machine manufacturer or determined by the user as needed. General technical requirements
Manufacturer logo, model specification, factory number, (MC logo, etc. should be clear and complete. The coordinate measuring machine should move smoothly without noise caused by interference of parts. The range of motion reaches the specified value. Calibration conditions
7.1 Standards
7.1.1 Length measurement standards
Calibrated gauge blocks, step gauges or ball (hole) plates, etc. 7.1.2 Detection error measurement standards
Calibrated standard balls. The diameter is between 10mm and 50mm, and its shape error should be better than 1/5 of the maximum allowable detection error of the measured coordinate measuring machine,
JF 1064--200
This calibration should not use the ball provided with the machine for measuring the probe. 7.2 The uncertainty of the position measurement system of the laser interferometer should be less than 1/5 of the maximum allowable position indication error. 7.3 Environmental conditions
7.3.1 Environmental conditions requirements
Ambient temperature 20℃. The deviation of ambient temperature, the time gradient and spatial gradient of the change should be within the allowable range specified by the manufacturer
Ambient vibration should be within the allowable range specified by the manufacturer. 7.3.2 Measurement of environmental conditions
The laboratory ambient temperature should be recorded. Check during calibration The kitchen temperature record at the entrance should be kept. During the measurement process, the temperature change and overflow gradient of the coordinate measuring machine should be measured and recorded. The measuring points should be no less than 4 points, distributed in different directions and at different angles. 8 Calibration items and calibration methods
8.1 Calibration method for indication error of length measurement The calibration method for indication error of length measurement can be carried out by one of 8.2 to 8.3. 8.1.1 Probe configuration
The probe can be configured arbitrarily within the range specified by the manufacturer. The direction of the probe is generally not parallel to the direction of the motion axis. The configured probe is calibrated according to the operating specifications
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Correct auxiliary measurement standard
Measurement indicator
Home standard medicine is required for the work of the Rui, the measurement is set as the grid point interval standard instrument length 8.1.2.1 According to the diagonal length of the coordinate measuring machine measurement space, select the standard instrument length. A total of 5 length values are used, the maximum length is not less than 66% of the diagonal length of the measurement space, and the minimum length does not exceed 30mm: Other lengths should make the measurement length intervals basically uniform:
Place the standard in 7 different directions and (or) positions, and the direction of the standard placement should be to The length direction should include at least 105 spatial diagonal directions. Each measurement length should be measured 3 times in each direction and (or) position, and the length direction should be re-determined for each measurement. A total of 35 groups of 105 length measurement values are obtained. Note: In the calibration of non-automatic control coordinate measuring machines, the length direction can be determined only once in each direction or position of the measuring block. 8.1.2.2 When the maximum length of the standard pusher does not meet the requirements of 8.1.2.1, but is greater than 1/2 of the longest drive shaft length of the coordinate measuring machine, the number of directions and (or) positions measured by the standard should be appropriately increased, and the total number of directions and (or) positions should not exceed JJF 1064-2000. The number of directions in which the standard is placed in the spatial diagonal direction should be at least 1/2 of the total number, and the position should cover different parts of the coordinate measuring machine scale as much as possible.
8.1.2.3 When the maximum length of the standard is less than 1/2 of the length of the longest axis of the coordinate measuring machine, in addition to the measurement required by 8.1.2.2, the position indication error measurement of the three axes shall be supplemented by using a laser interferometer (see Appendix A).
8.1.3 Calibration of the indication error of length measurement by means of a ball (hole) plate Use the ball (hole) plate as the standard for measurement. Measure and record the characteristic point marks of each measuring element on the standard.
Note: When using this specification for acceptance of coordinate measuring machines, the methods listed in this clause shall not be used to avoid conflicts with the corresponding national standards.
8.1.3.1 The maximum distance between the measuring elements on the standard shall not be less than 66% of the diagonal length of the coordinate measuring machine measurement space. The standard must be placed in at least two intersecting directions, intersecting a coordinate plane by 30° or 45° (Figure 4). O
(a) Standards are placed vertically, four directions and position sense (b) Standards are placed obliquely, two directions and position sense Figure 4 Standards are placed in at least two intersecting directions 8.1.3.2 When the maximum distance between the measuring elements on the standard does not meet 8.1.3.1, but is greater than 1/2 of the longest moving axis length of the coordinate measuring machine, the above measurements should be performed at multiple positions in the measurement space of the coordinate measuring machine, and the total number of measurements should not exceed 6.
8.1.3.3 When the maximum distance between the measuring elements on the standard is less than 1/2 of the longest moving axis length of the coordinate measuring machine, in addition to the measurements required by 8.1.3.2, the position error measurement of the three axes should be supplemented by using a laser interferometer (see Appendix A).
8.1.4 Indication error of axial length measurement
Select the length of the standard according to the measuring length of the corresponding axis of the coordinate measuring machine. A total of 5 length values are used, the maximum length s
..IF 1064--2000
is not less than 66% of the corresponding axis measurement length, and the minimum length does not exceed 30mm; other lengths should make the measurement length intervals basically even.
Each axis measures a position, which is specified by the CMM user or in the middle of the measurement space. The measurement method is the same as 8.1.2 or 8.1.3.
8.1.5 Processing of calibration results
Calculate the indicated errors E and E1n of the coordinate measuring machine for all length measurements. If the coordinate measuring machine is equipped with accessories for correcting systematic errors or with corresponding computer software, the indicated values of specific measurements (specific dimensions and specific configurations) can be corrected for systematic errors. When the user has the specified environmental conditions, no manual correction of the computer output results for temperature or other factors is allowed, except for the automatic correction of the original errors of the measuring machine data processing system.
The calibration value of the standard is used as the agreed true value of the measured length during the calculation. This value can only be corrected if the coordinate measuring machine software to be measured has a temperature correction function. If manual temperature input is required, it can only be entered before the measurement.
E and E1n can be shown in the error diagram; the diagram should also indicate the maximum permissible indicated error of the length measurement MPEe or MPEE10
8.2 Method for calibration of probing errors
8.2.1 Probe configuration
The probe can be configured arbitrarily within the manufacturer's limits. The probe direction is generally not parallel to the direction of the motion axis. Calibrate the configured probe according to the operating specifications. 8.2.2 Calibration process
Firmly install the standard sphere. Select 25 detection points on the standard push ball for detection, and record the coordinates of the 25 points. The detection points should be distributed as evenly as possible on the hemisphere. The orientation of the hemisphere can be selected by the user. The recommended detection point distribution is as follows:
1 point on the pole of the standard sphere;
4 points evenly distributed 30° below the pole;
8 points evenly distributed 60° below the pole and rotated 22.5° relative to the previous group; 12 points evenly distributed 90° below the pole and rotated 20° relative to the previous group. 8.2.3 Processing of calibration results
Use all 25 measured values to calculate the center of the least squares (Gaussian) sphere, and use the 25 measured values to calculate the radial distance r to the center of the sphere. P=rmax-rmin
8.3 Conformity assessment
For calibration results that meet the following conditions, an evaluation that meets the requirements can be given: The indication error E of length measurement is not greater than the maximum allowable indication error MPEE of length measurement: (7)
The indication error E of axial length measurement is not greater than the maximum allowable indication error MPE of axial length measurement: -The detection error P is not greater than the maximum allowable detection error MPEp. When using a gauge block or a step gauge to measure the indication error of length measurement, three measurements of each length in one direction 6
JF1064—2000
are a group. Only one data out of tolerance is allowed in each group of measurement data, and the total number of out-of-tolerance data shall not exceed 5% of the total number of measurements. For each group of out-of-tolerance measurements, 10 measurements are repeated. If the indication error is within the maximum allowable length measurement error, the result meets the requirements.
When P is greater than MPE, it is allowed to repeat all measurement processes including the preparation process once to obtain the P value. When the detection error is within the maximum allowable detection error, the result meets the requirements. For determining the new maximum allowable indication error, please refer to Appendix C. 9 Recalibration time interval
When the user regularly conducts intermediate inspections (see Appendix F); and the intermediate inspection results do not change suddenly, the recalibration time interval is recommended to be 1 year. When the intermediate inspection results change suddenly, the cause should be promptly identified, and the coordinate measuring machine failure should be eliminated before recalibration.
Appendix A
JJF1064--2000
Additional calibration items for large coordinate measuring machines When the maximum length of the standard pusher is less than 1/2 of the longest motion axis length of the coordinate measuring machine, in addition to the measurements required by 8.1.2 or 8.1.3 of this specification, the position indication error measurement of the three axes should be supplemented by a laser interferometer.
Figure A.1 is a coordinate measuring machine motion chain model. The motion axis of the coordinate measuring machine is the X axis close to the workpiece and the Z axis close to the probe. Using this model, the position indication error of 6 lines is measured in the measurement space, namely: one line is measured on both sides of the X-axis direction on the XY plane and the XZ plane; one line is measured on both sides of the Y-axis direction on the YZ plane; and one line is measured in the B-axis direction. Figure A.1 CMM kinematic chain model and position error measurement position Each line is measured evenly at 10 intervals along the entire length. Measure 3 times on the round trip. The zero point of the measurement is set at the starting position of the measurement, and the indication of the laser interferometer or laser interferometer shall not be reset during each measurement. The difference between the position coordinates displayed by the CMM and the indication of the laser interferometer is its position indication error. When the CMM is positioning the target point, the deviation in the measurement direction should be used as a correction value to correct the indication of the laser interferometer. When the CMM adopts computer error correction technology, the indication of the CMM should use the corrected value. The absolute value of the difference between the deviation of any point (point) and the deviation of the reference point (point i) should be within the maximum allowable position indication error range specified by the manufacturer.1. Coordinate measuring machine kinematic chain model and position error measurement position. Each line is evenly measured at 10 intervals along the entire length. Measure 3 times on the round trip. The zero point of the measurement is set at the starting position of the measurement, and the indication of the laser interferometer or laser interferometer shall not be reset during each measurement. The difference between the position coordinates displayed by the coordinate measuring machine and the indication of the laser interferometer is its position indication error. When the coordinate measuring machine is positioned, the deviation of the target point in the measurement direction should be used as a correction value to correct the indication of the laser interferometer. When the coordinate measuring machine uses computer error correction technology, the indication of the coordinate measuring machine should use the corrected value. The absolute value of the difference between the deviation of any point (point) and the deviation of the reference point (point i) should be within the maximum allowable position indication error range specified by the manufacturer.1. Coordinate measuring machine kinematic chain model and position error measurement position. Each line is evenly measured at 10 intervals along the entire length. Measure 3 times on the round trip. The zero point of the measurement is set at the starting position of the measurement, and the indication of the laser interferometer or laser interferometer shall not be reset during each measurement. The difference between the position coordinates displayed by the coordinate measuring machine and the indication of the laser interferometer is its position indication error. When the coordinate measuring machine is positioned, the deviation of the target point in the measurement direction should be used as a correction value to correct the indication of the laser interferometer. When the coordinate measuring machine uses computer error correction technology, the indication of the coordinate measuring machine should use the corrected value. The absolute value of the difference between the deviation of any point (point) and the deviation of the reference point (point i) should be within the maximum allowable position indication error range specified by the manufacturer.
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