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JJG 797-2013 English PDF (JJG797-2013)

JJG 797-2013 English PDF (JJG797-2013)

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JJG 797-2013: Verification Regulation of Calibration Instrument for Torque Wrenches

This Regulation applies to the initial verification, subsequent verification and usage inspection of electronic, mechanical and hydraulic calibration instrument for torque wrenches.
JJG 797-2013
JJG
National Metrological Verification Regulations
of the PEOPLE Republic of China
Calibration Instrument for Torque Wrenches
ISSUED ON. APRIL 27, 2013
IMPLEMENTED ON. OCTOBER 27, 2013
Issued by. General Administration of Quality Supervision, Inspection and Quarantine
Verification Regulation of
Calibration Instrument for Torque Wrenches
Replacing JJG 797-1992
Administration organization. National Technical Committee of Force Value and Hardness Measurement
Main Drafting organizations. National Institute of Metrology; and No.704 Institute of CSIC
Participating drafting organizations. Beijing Aerospace Measurement and Testing Technology Research Institute; and Hubei Provincial Institute of Measurement and Testing
National Technical Committee of Force Value and Hardness Measurement is entrusted to be responsible for the explanation of this Regulation.
Main drafters of this Regulation.
Meng Feng (National Institute of Metrology)
Zhang Zhimin (National Institute of Metrology)
Li Tao (No.704 Institute of CSIC)
Participating drafters.
Mei Hongwei (Beijing Aerospace Institute of Measurement and
Testing Technology)
Lin Jing (No.704 Institute of CSIC)
Hu Xiang (Hubei Provincial Institute of Measurement and Testing)
Table of Contents
Introduction ... 5
1 Scope ... 6
2 Terminology ... 6
2.1 Standard torque wrench ... 6
2.2 Average arm length ... 6
2.3 Minimum arm length ... 6
3 General introduction ... 6
4 Measuring performance requirements ... 7
5 General technical requirements ... 8
5.1 Appearance ... 8
5.2 Technical performance ... 8
5.3 Use and replacement of indication instrument ... 8
5.4 Indication instrument ... 9
6 Measuring instrument control ... 10
6.1 Verification condition ... 10
6.2 Verification item and verification method ... 11
6.3 Process of verification result ... 17
6.4 Verification period ... 18
Appendix A Content format of verification certificate and verification
results ... 19
Appendix B Verification record of calibration instrument for torque
wrenches ... 20
Appendix C Verification steps ... 22
Appendix D Arm length for reference and literature ... 23
Introduction
This regulation was formulated according to Germany and Japan's current verification method of calibration instrument for torque wrenches DKDR-3-8 and MIF 019, this Regulation replaces JJG 797-1992 "Calibration instrument for torque wrenches." The main technical changes are that it adds verification method of standard torque wrenches; VERIFY 0.3-grade and 0.5-grade
calibration instrument for torque wrenches, ADD indication value reproducibility under same arm length and indication value reproducibility under different arm length; ADD indication value reproducibility under different arm length for 1.0- grade calibration instrument for torque wrenches, and it cancels verification method for standard torque instrument.
Verification Regulation of
Calibration Instrument for Torque Wrenches
1 Scope
This Regulation applies to the initial verification, subsequent verification and usage inspection of electronic, mechanical and hydraulic calibration instrument for torque wrenches (hereinafter referred to as torque instrument).
2 Terminologies
2.1 Standard torque wrench
The torque wrench which has high accuracy and is used to conduct quantity- value transfer for calibration instrument for torque wrenches.
2.2 Average arm length
The average length of torque wrench?€?s arm, within a certain range.
2.3 Minimum arm length
The minimum length of torque wrench?€?s arm, within a certain range.
3 General introduction
Torque instruments are the instruments used to verify (calibrate) various types of manual torque wrenches. Torque instruments can be generally divided into mechanical, hydraulic and electronic types (it usually uses strain torque sensor) according to the working principle. It mainly includes two kinds according to the structure. one is the calibration instrument for torque wrench with a loading structure, another one is the calibration instrument for torque wrench without a loading structure.
Mechanical and hydraulic torque instruments coaxially concatenate the wrench of torque wrench to be verified AND the torsion elastomer of torque instrument. When imposing torque directly or indirectly on the tail section of torque wrench, specifications and user?€?s requirements.
5.3.2 Torque sensor and indication instrument shall support the use of each other. Generally, they shall not be replaced randomly. If they need to be replaced, the re-verification is needed.
5.4 Indication instrument
5.4.1 Analogue instrument
5.4.1.1 Scale and mark of each indication dial shall be clear, explicit and easy to read. The zero and maximum value of each scale shall be explicitly marked. 5.4.1.2 It shall have reset mechanism to indicate zero and holding mechanism of torque?€?s indication value.
5.4.1.3 The engraved lines on the dial shall be uniform, the width of pointer shall be approximately equal to the width of engraved lines. The resolution shall be determined according to the RATIO of the width of pointer AND the spacing (scale spacing) between the centers of 2 adjacent engraved lines. The
recommended ratio is 1/2, 1/5 and 1/10. When the scale spacing is not less than 1.25mm, 1/10 dial scale value may be estimated and read.
5.4.1.4 During the process of imposing torque, the pointer shall be smooth, and have no abnormal phenomenon such as impact and stagnation. Active pointer and passive pointer shall be coincide with the engraved lines of the dial, and be parallel to the surface of dial.
5.4.1.5 The friction of active pointer shall be able to make passive pointer stay in any position. When conducting verification with or without passive pointer, its relative error of indication value shall not exceed the relative error of indication value as specified by the corresponding accuracy grade. When the torque of fixed-value type torque wrench is suddenly removed, the amount of change of active pointer shall not be greater than 1/5 of the relative error of maximum torque indication value of the corresponding accuracy grade.
5.4.2 Digital instrument
5.4.2.1 The connection between torque sensor and indication device shall be reliable. And it shall have certain ability to resist to electromagnetic interference. 5.4.2.2 Each operation switch, button, knob and jack shall have words or symbols marked on it, and the operation shall be flexible and reliable. 5.4.2.3 The indication of figures shall be clear and accurate. And it shall have functions of continuation, peak holding and zero-adjustment.
5.4.2.4 The minimum figure increment shall be 1??10n, 2??10n or 5??10n, in which n is a positive integer, a negative integer or zero. Each grade shall includes zero and maximum value of its scale range. And it shall indicate the declining symbols of less-than zero position (for example, displayed by the symbol "+" or "-").
5.4.2.5 For those with function of digital signal output, the output data shall be consistent with the indication value.
5.4.2.6 When torque instrument is without loading, if the indication value change is not greater than 1 increment, then the resolution is 1 increment of the last significant figure displayed; if the indication value change is greater than one increment, then the resolution is the half of range of the indication value change.
6 Measurement instrument control
Measurement instrument control includes. the initial verification, subsequent verification and inspection when in use.
6.1 Verification condition
6.1.1 Environmental condition
According to the specification of torque instrument grade, verification of 0.3 grade and 0.5 grade shall be at room temperature of (20 + 5) ??C, verification of 1.0 grade and 2.0 grade shall be at room temperature of (20 + 10) ??C, and under the condition of a relative humidity not greater ...

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