This standard specifies the torsion test method for rivet contact wire. This standard is applicable to the inspection of the performance of rivet contact wire and other contact wire under plastic deformation when twisted in one-way alternating direction, and to show the metal's unevenness, surface defects and some internal defects. JB/T 7780.5-1995 Mechanical and physical properties test of rivet contact wire JB/T7780.5-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Test Methods for Mechanical and Physical Properties of Wire for Rivet Contacts Torsion Test Method for Wire for Rivet Contacts
1 Subject Content and Scope of Application
This standard specifies the torsion test method for wire for rivet contacts. JB/T 7780. 5—1995
This standard is applicable to the inspection of the performance of wire for rivet contacts and other wire for contacts under plastic deformation when twisted in one direction or alternating direction, and to show the unevenness of the metal, surface defects and some internal defects. 2 Test Principle
The torsion of metal wire is to twist the sample in one direction or alternating direction with the sample as the axis until the sample breaks or reaches the specified number of twists. 3 Sample
3.1 The sample should be cut from any part of the qualified wire after appearance inspection. If the relevant standards or the agreement between the two parties stipulate otherwise for the sampling location, it shall be implemented in accordance with the regulations.
3.2 The sample should be as straight as possible before the test. If necessary, the specimen can be straightened by hand or by hammering it against a wooden board. The specimen surface must not be damaged during the straightening process, and the specimen is not allowed to be twisted. 3.3 Unless otherwise specified, the gauge length between the test machine chucks is as shown in Table 1. Table 1
Nominal diameter of wire
>1 3~2. 5
>2. 5~5. 0
>5.0~8. 0
4 Test device
Gauge length between chucks
4.1 The chucks of the test machine should have sufficient hardness, and the positions of the two chucks should ensure that the axis of the specimen coincides with the torsion axis. mm
4.2 One of the two chucks must not rotate at all, but can move freely in the axial direction. The chuck must have a force-applying device to tighten the specimen. The other chuck can only rotate around the axis of the specimen.
4.3 The torsion speed of the testing machine should be adjustable and have a scale for measuring the gauge length between the two chucks. 5 Test steps
5.1 Unless otherwise specified, the test should be carried out at room temperature of 1035°C. 5.2 Clamp the specimen in the chuck of the testing machine so that its axis coincides with the axis of the chuck. In order to keep the specimen straight during the test, some form of tension should be applied. This tension should not be greater than 2% of the load corresponding to the nominal tensile strength of the wire. 5.3 During the test, unless otherwise specified in the relevant standards, the torsion speed should not exceed the values ​​listed in Table 2 for a given wire diameter. Approved by the Ministry of Machinery Industry on October 9, 1995
Implemented on January 1, 1996
Nominal diameter of wire
>1. 3~2. 5
>2. 5~5. 0
JB/T 7780. 5-1995
Maximum number of twists per minute
5.4 After the specimen is placed in the testing machine, the rotatable chuck rotates at a slow and uniform speed until the specimen breaks or reaches the specified number of twists.
5.5 One-way twisting is when one end of the specimen rotates in a fixed direction for a full circle (360°) as a twist, and alternating direction twisting is when the specimen rotates in any direction for a full circle (360°) as a twist. The alternating method shall be implemented in accordance with the relevant standards, and the number of twists in different directions shall be recorded separately.
5.6 When the number of twists of the specimen. When the fracture and surface conditions meet the requirements of the relevant technical conditions, the test is qualified, otherwise it is judged as unqualified. If the specimen breaks within 2d from the chuck and the specified number of torsion times is not reached, the test is invalid and the test should be repeated. 5.6.1 Fracture shape and defects of the specimen: flat, stepped, inclined, fan-shaped, perpendicular to the axis of the specimen, with cracks and shrinkage holes, etc.
5.6.2 Surface defects of the specimen: cracks, burrs, pores, inclusions, delamination and grooves, etc. 6 Test report
The test report may include the following content as needed: a) This standard number,
b) Specimen mark (such as material category, production batch number, etc.), specimen nominal diameter: bzxz.net
d) Specimen preparation (such as sample and straightening method, etc.), test conditions (such as gauge length, tension, etc.),
test results (torsion times, fracture and surface defects, etc.). Additional Notes:
This standard was proposed and managed by the Guilin Electric Science Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Guilin Electric Science Research Institute. The main drafter of this standard is Zhong Baoshu
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