This test method is applicable to the inspection of the bending performance of circular cross-section conductors of copper, aluminum and their alloys with a nominal diameter of 0.8~20mm and special-shaped cross-section conductors with a nominal size a not greater than 20mm (such as tram wires). This test method is to wind the test piece around a test rod of a specified diameter for a specified number of turns and observe the changes on its surface. The winding method can be repeated winding or single winding. GB 4909.7-1985 Bare wire test method Winding test GB4909.7-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of ChinawwW.bzxz.Net
Test methods for bare wires
Mandrel winding test
UDC 621.816.14
GB4909.7—85
The provisions of this standard are consistent with the provisions of international standards IEC 207, 209 (1966) and international standard 1SO R958 (1969). 1 Scope of application
1.1 This test method is applicable to the inspection of the bending performance of circular cross-section conductors of copper, aluminum and their alloys with a nominal diameter of 0.8 to 20 mm and special-shaped cross-section conductors with a nominal size a not greater than 20 mm (such as tram wires). 1,2 This test method is to wind the test piece around a test rod of specified diameter for a specified number of times and observe the changes on its surface. The winding method can be repeated winding or single winding.
2 Test equipment
The winding test device is shown in Figure 1. The test rod should have sufficient rigidity and a polished surface. Figure 1 Schematic diagram of the winding test device
1—Clamp, 2—Test piece: 3—Test ladder 14—Guide block! 5—Test ladder seat, d—Test piece diameter
3 Test piece preparation
Two test pieces are cut from the test piece that has passed the surface inspection. The length of the test piece should meet the requirements of the specified number of winding turns and operation. 4 Test steps
4.1 Select the test rod according to the winding diameter specified in the product standard and tighten it on the seat. 4.2 Fix the assembled test rod in the fixture. The axis of the test rod and the center line of the clamp should coincide well. 4.3 Install the test piece and apply a tensile stress of no more than 5% of the tensile strength of the test piece to the free end of the test piece. 4.4 Start the test machine to wind the test piece.
Issued by the National Bureau of Standards on January 31, 1985
Implemented on December 1, 1985
GB 4909.7—85
4.4.1 The rotation speed should be stable, uniform and slow, and generally should not exceed 10 times/min. 4.4.2 The turns should be closely arranged, not overlapped, and close to the surface of the test rod. 4.4.3 Any winding method can be selected from the following methods, but it should be clearly stated in the product standard: Method A: The repeatedly wound test piece is tightly wound 8 times on a test rod of specified diameter, and unwound 6 times. When unwinding, the spiral part of the test piece should be unfolded into a straight shape, and then tightly wound on the test rod again. Method B: The once wound test piece is tightly wound 8 times on a test rod of specified diameter. 4.5 Check the surface of the test part of the test piece with normal vision and record it. 4.6 When the diameter of the test rod is equal to the nominal diameter of the test piece, manual winding is also allowed. First, bend the test piece into a U shape and clamp it into an "r" buckle, then manually wind one end of the test piece around the other end tightly, as shown in Figure 2. 5 Test results and calculations
The test results of each test piece shall comply with the provisions of the product standard. Figure 2 Self-winding
Additional instructions
This standard is proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard is under the jurisdiction of the Shanghai Cable Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Shanghai Cable Research Institute of the Ministry of Machinery Industry and others. The drafting persons in charge of this standard are Wu Musheng and Shen Jianhua.
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