Calibration regulation of torque wrenches
1 Scope
This procedure is applicable to the first calibration, subsequent calibration and in-service inspection of manual torque wrench, torque screwdriver and other tightening measuring instruments with torque measurement or control mechanism (hereinafter referred to as torque wrench).
2 Normative references
The following document is referenced in this regulation:
JJG 557-2011 Standard torque-meters
JJG 797-2013 Calibration instrument for torque wrenches
GB/T 3390.2-2004 Hand operated socket wrenches — Driving squares
GB/T 15729-2008 Hand torque tools — General requirements
For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
3 General
The torque wrench works by the principle of torque balance. According to the structure, torque wrench is generally classified into two forms: indicating type and preset type. Indicating type may be classified into pointer type and digital type. Preset type may be classified into scaled-adjustable type and fixed value type.
Torque wrench is mainly used to tighten bolts, nuts or screws, measure (or control) the torque value during tightening, so as to indirectly controlling the axial force consistency of connecting bolts (or screws) between solids.
4 Metrological performance requirements
Accuracy level classification and technical index of torque wrench shall meet the requirements of Table 1.
Introduction i
1 Scope
2 Normative references
3 General
4 Metrological performance requirements
5 General technical requirements
5.1 Appearance and accessories
5.2 Indicating and setting device
5.3 Operation adaptability
6 Control of metrological instruments
6.1 Calibration conditions
6.2 Calibration items and methods
6.3 Treatment of calibration results
6.4 Calibration period
Annex A Working principle diagram of torque wrench calibration with torque multiplier
Annex B Transmission torque and opposite side dimension of square tenon
Annex C Original record of torque wrench calibration
Annex D Inside page format of calibration certificate/calibration result notice
