This standard specifies the product classification, technical requirements, test methods, inspection rules, packaging, marking, transportation and storage of torque wrenches. This standard applies to torque wrenches that control the tightening torque of screws and nuts. GB/T 15729-1995 General Technical Requirements for Torque Wrenches GB/T15729-1995 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
General technical conditions for torque wrenches
Torque wrench--General requirementsGB/T15729—1995
Technical conditions and test methods for hand-held torque wrenches
This standard is equivalent to the international standard ISO6789:1992 "Screw and nut assembly tools-test methods".
1 Subject content and scope of application
This standard specifies the product classification, technical requirements, test methods, inspection rules, packaging, marking, transportation and storage of torque wrenches. This standard is applicable to torque wrenches that control the tightening torque of screws and nuts. 2 Reference standards
GB/T230 Metal Rockwell hardness test method
GB2828 Batch inspection counting sampling procedure and sampling table (applicable to continuous batch inspection) GB2829 Periodic inspection counting sampling procedure and sampling table (applicable to the inspection of production process stability) GB/T4625 Assembly tool terminology for screws and nuts GB4955 Metal coating thickness measurement Anodic dissolution Coulometric method GB/T5305 Hand tool packaging, marking, transportation and storage GB5936 Test method for chemical protective layer of ferrous metals of light industrial products Immersion drip method 3 Product classification
Torque wrenches are divided into two categories: indicating type and preset type according to the provisions of GB4625. For details, see Appendix A (reference). 4 Technical requirements
4.1 Surface quality
4.1.1 The surface of the torque wrench should not have defects such as cracks, burrs, scars and rust spots. 4.1.2 The scale and value of the torque wrench should be clear and correct. 4.2 Surface treatment
4.2.1 The surface of the torque wrench can be electroplated, blackened or painted. 4.2.2 The coating thickness of electroplated parts should not be less than 8μm, and there should be no defects such as missing plating, bubbles, and shedding. 4.2.3 The blackened parts should have a uniform black oxide layer and should not have color discoloration and bottom exposure. 4.3 Structure and performance
4.3.1 The torque wrench should have a structure that can correct the indication error. 4.3.2 The torque adjustment mechanism of the preset torque wrench should be accurate and reliable. 4.3.3 The alarm device of the preset torque wrench must be able to clearly alarm when the preset torque is reached. 4.3.4 The ratchet of the preset torque wrench must be able to rotate flexibly. 4.3.5 The transmission method of the torque wrench should be able to reliably connect the sleeve. Approved by the State Bureau of Technical Supervision on October 24, 1995, 196
Implementation on July 1, 1996
4.4 Dimension series of transmission square
GB/T 15729—1995
The dimension series of transmission square of torque wrench shall be as specified in Table 1. Table 1
Maximum test torque, N·m
4.5 Hardness
The heat treatment hardness of the transmission square of torque wrench shall not be less than HRC39.4.6 Torque accuracy
Dimension of opposite sides of transmission square, mm
4.6.1 For indicating torque wrenches, the torque error of type A and type D is ±6%, and the torque error of type B, type C and type E is ±4%.4.6.2 For preset torque wrenches, the torque error of type A, type B and type C is ±4%, and the torque error of type D, type E and type F is ±6%.
4.7 Overload
The torque wrench should be able to withstand a load of 125% of its rated torque value (preset B and E types are its rated value) in its direction of use.
4.8 Durability
After the torque wrench is tightened 5000 times at its rated value in its direction of use, there should be no damage that affects its use. 5 Test method
5.1 Surface quality inspection
The surface quality of the torque wrench is inspected visually. 5.2 Surface treatment test
5.2.1 The coating thickness of the electroplated parts of the torque wrench is determined in accordance with the provisions of GB4955. 5.2.2 The blackened parts of the torque wrench are tested in accordance with the provisions of GB5936. 5.3 Structure and performance inspection
The structure and performance of the torque wrench are inspected by visual inspection and touch. 5.4 Hardness test
The hardness of the torque wrench transmission side sample shall be tested on the side of the transmission side in accordance with the provisions of GB230. 5.5 Torque accuracy test
5.5.1 The torque wrench shall be tested under the conditions of an ambient temperature of 25±5℃ and a relative humidity of no more than 85%. 5.5.2 The tolerance of the device used for torque accuracy test shall not be greater than ±1% of the indicated value. 5.5.3 The test steps for torque accuracy shall be in accordance with the following provisions: 5.5.3.1 The torque wrench for test shall be placed as specified in Figures 1 and 2, and a load F shall be applied to the center of the gripping part. The test device must be set to zero before the test.
GB/T15729-1995
Figure 1 Torque wrench in vertical state
Figure 2 Torque wrench in horizontal state
5.5.3.2 The load F must be applied steadily. 5.5.3.3 The whole test shall be carried out at 20%, 60% and 100% of the rated torque value of the torque wrench to be tested. 5.5.3.4 During the test, each test point shall be tested 5 times in succession, and the tolerance shall comply with the provisions of Article 4.6. 192
5.6 Overload test
GB/T 15729--1995
The torque wrench shall be subjected to the load specified in Article 4.7 according to its direction of use and maintained for 3 minutes. After unloading, the torque wrench shall not have any damage that affects its use.
5.7 Durability test
The torque wrench shall be tested at a rate of 10 to 20 times/min according to its direction of use in accordance with the provisions of Article 4.8. After the test, the torque wrench shall not have any damage that affects its use.
6 Inspection rules
The inspection of products is divided into acceptance inspection and type inspection. 6.1 Delivery inspection
6.1.1 Products must be inspected and qualified by the inspection department and accompanied by a certificate of conformity before they can leave the factory. 6.1.2 The ordering party may conduct random inspections on the products in accordance with the provisions of this standard. 6.1.3 The random inspection of products shall be carried out item by item using the secondary sampling plan specified in GB2828. 6.1.4 The classification of unqualified products, inspection items, qualified quality level AQL (number of unqualified products per 100 units of products) and inspection level IL shall be as specified in Table 2.
6.1.5 The judgment of whether the delivery inspection is qualified or not shall be carried out in accordance with Article 4.11 of GB2828. Table 2
Type inspection
Classification of nonconformities
Inspection items
Torque sugar content
Structure and performance
Surface treatment
Surface quality
Products shall be subject to type inspection if any of the following conditions are met: the product is finalized and put into production,
due to major changes in structure, materials, and processes, which may affect product performance; during normal production, it shall be conducted once every year; the product is discontinued for more than half a year before production is resumed; the superior quality supervision agency makes a request.
Qualified quality level AQL
6.2.2 The type inspection of products shall be conducted item by item using the one-time sampling plan specified in GB2829. Inspection level IL
6.2.3 The inspection items, nonconforming quality level RQL (number of nonconforming products per 100 units of products) and discrimination level DL of the product shall be as specified in Table 3.
6.2.4 The judgment of whether the type inspection is qualified or not shall be carried out in accordance with Article 4.11 of GB2829. 193
6.3 Re-inspection
Inspection items
Surface quality
Surface treatment
Structure and performance
Torque and precision
Durability
GB/T 15729 --- 1995
Unqualified quality level RQL
Discrimination level DI
The manufacturer shall replace the unqualified products found in the delivery inspection and the samples damaged by the test. The products rejected after inspection can be sorted or repaired by the manufacturer and resubmitted for acceptance. Packaging, marking, transportation and storage
The packaging, marking, transportation and storage of products shall be in accordance with the provisions of GB5305. 19.1
GB/T15729—1995
Appendix A
Classification of torque wrenches
(reference)
This appendix applies to the classification of torque wrenches and does not restrict the structure of torque wrenches. A1 The types of indicating torque wrenches are shown in Figures A1 to A5. Figure A1 Type A (pointer type)
Type B (dial type)Www.bzxZ.net
Type C (digital display type)
Figure A4 Type D (rotary handle pointer type)
GB/T15729—1995
Figure A5 Type E (rotary handle digital display type)
A2 The types of preset torque wrenches are shown in Figures A6 to A11. @o
Figure A6A type (adjustable with scale)
Type B (force-limited type)
Figure A8C type (adjustable without scale)
Figure A9D type (rotary handle with adjustable scale)
Figure A10E type (rotary handle force-limited type)
GB/T 15729--1995
Figure A11
Type F (rotary handle without adjustable scale)
The output torque range of the torque wrench shall be determined by the manufacturer according to the use requirements. Additional remarks:
This standard is proposed by China Light Industry General Association.
This standard is under the jurisdiction of the National Tool Hardware Standardization Center. This standard is drafted by Shanghai Tool Industry Research Institute. The main drafter of this standard is Lin Meide.
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