GOST 13813-68
GOST 13813−68 (ISO 7799−85) Metals. Test method for bending of sheets and strips thickness less then 4 mm (with Amendments No. 1, 2)
GOST 13813−68
(ISO 7799−85)
Group B09
INTERSTATE STANDARD
METALS
Test method for bending of sheets and strips thickness less then 4 mm
Metalls. Bend test for sheets and strips thickness less then 4 mm
Date of introduction 1969−01−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of ferrous metallurgy of the USSR
DEVELOPERS
I. I. Golikov, I. A. Balakina, L. T., Timoshok, E. D. Sokolov, E. A. Kurganova
2. APPROVED AND promulgated by the Committee of standards, measures and measuring devices under Council of Ministers of the USSR 25.06.68
3. The standard fully complies ST SEV 479−88, ISO 7799−85
4. INSTEAD OF OST 1688
5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
Item number |
| GOST 2789−73 |
2.2 |
6. Limitation of actions taken by Protocol No. 7−95 Interstate Council for standardization, Metrology and certification (ICS 11−95)
7. REPRINT (January 1999) with Amendments No. 1, 2 approved in March 1980, October 1989 (IUS 7−80, 1−90)
This standard specifies the test method for bending of sheets and strips thickness less then 4 mm at a temperature of 20°C.
The test is repeated bend up to 90 degrees from the rest position to one or the other side of the specimen of rectangular cross section secured to the terminals of the device.
The standard fully complies ST SEV 479−88, ISO 7799−85.
(Changed edition, Rev. N 2).
1. PREPARATION OF SAMPLES TO TEST
1.1. Place tenderloin pieces for samples, their number, the direction of the longitudinal axis of the sample relative to the workpiece, the magnitude of the gaps when cutting and machining should be specified in regulatory technical standards on the rules of selection of blanks and samples or products.
(Changed edition, Rev. N 2).
1.2. (Deleted, Rev. N 2).
1.3. The thickness of the samples should be equal to the thickness of the material being tested. In the manufacture of laminated samples retain surface or cover layer (Paluda, galvanizing, etc.).
1.4. Sample width should be equal to 20mm When width of strip less than 20 mm sample width should equal the width of the material as supplied.
For sheets and strips of Dynamo and transformer steel is allowed to carry out test on the sample width (30±0,2) mm.
(Changed edition, Rev. N 2).
1.5. (Deleted, Rev. N 1).
1.6. On the surface of the sample is not allowed for scale, scratches, cracks and dents.
The edge samples must be free of cracks and burrs.
Allowed rounding sharp longitudinal edges with a file.
If there are indications in the normative-technical documentation for steel allowed the amendment of the samples.
(Changed edition, Rev. N 2).
2. EQUIPMENT
2.1. The test bend is carried out on the device, whose scheme is shown in the drawing.
Drawing. A device for testing the bend
1 — the bending lever; 2 — lead and 3 — axis of rotation of the bending arm;
4 — supporting cylindrical rollers; 5 — replaceable jaws
(Changed edition, Rev. N 2).
2.2. Sponges and rollers of the device needs to be mixed and have a hardness not lower than HRC 61. The surface roughness of the rollers and jaws after machining should not be below <1,25 µm according to GOST 2789.
2.3. Rollers and sponge device is mounted so that the axis of the sample was placed in the same plane with the axis of the lever.
The axis of the rollers must be parallel to the plane passing through the axis of the specimen and the lever. A plane passing through the axis of the rollers must be perpendicular to the plane of the rolling axis of the sample.
2.2, 2.3. (Changed edition, Rev. N 1).
2.4. The gap between the test sample and the platen should not exceed 0.1 mm.
2.5. The distance from the upper generatrix of the rollers to the center of rotation of lever must be equal to (1±0,1) mm.
2.4, 2.5. (Changed edition, Rev. N 2).
2.6. The device should provide the bend angle of the sample at 90° ±3° left or right from the vertical.
2.7. The device should have a lever on the tensioner providing tension specimen stress of 2% of the nominal value of the time resistance
test of metal.
(Changed edition, Rev. N 2).
2.8. The design of the bending lever should provide the possibility of changing the distance in the range from 3 to 40 mm.
2.9. The device is recommended to equip the jaws with the rollers following radii: 1,0; 1,5; 2,0; 2,5; 3,0; 4,0; 5,0; 6,0; 7,5; 8,0; 10,0 mm.
3. TESTING
3.1. The sample is clamped in the jaws of the device perpendicular to the plane passing through the axis of the rollers. The upper end of the sample should pass through the groove in the leash, is fixed on the lever of the device (the original position). The length of the clamped end of the specimen shall not be less than the height of the jaws.
3.2. Moving the sample in the jaws when the test is not allowed.
3.3. The first bend is the bend at 90° from the vertical in any direction (right and left) and return to a vertical position; a second bend — bend 90° from vertical in the opposite direction and again return to the upright position, etc. (drawing) until the specimen breaks.
(Changed edition, Rev. N 1, 2).
3.4. Test bend produced such a rate that the heating of the sample did not affect the test results. The test speed should be uniform, not exceeding 60 bends per minute.
3.5. The radius of the rollers and the distance from the lower edge of the leash to the upper forming rollers installed in accordance with the requirements of normative-technical documentation for metal products. If such instructions do not exist in the standards, the parameters of the device determined depending on the thickness of the test metal on the table.
mm
The thickness of the material being tested |
The radius of the rollers |
The width of the groove the leash |
Distance | |
| To 0.15 |
1,0 |
0,2 |
5 |
0,25 |
| SV. 0.15 to 0.3 |
0,4 | |||
| SV. 0.3 to 0.5 |
2,5 |
0,6 |
10 | |
| SV. 0.5 to 0.1 |
4 |
1,1 |
15 | |
| «1.0 to 1.5 |
1,6 | |||
| SV. 1.5 to 2.0 |
6 |
2,2 |
20 | |
| «2.0 to 2.5 |
2,7 | |||
| «2.5 to 3.0 |
3,2 | |||
| SV. 3.0 to 3.5 |
8 |
3.7 V |
25 | |
| «3.5 to 4.0 |
4,2 | |||
(Changed edition, Rev. N 1, 2).
3.6. With the lack of rigidity of the sample allowed testing of the inflection pre-tensioned. The tension should not exceed 2% of the temporary resistance of the sample if the standards for sheets and strips not established other requirements.
(Changed edition, Rev. N 1).
4. DEFINITION OF TEST RESULTS
4.1. After the test, inspect the edges and outer surface at the point of bending. The test results are evaluated according to the following criteria:
a) to achieve a given number of kinks, without the appearance of cracks;
b) the number of kinks: up to the appearance of cracks on the sample; to promote cracked up half the width of the sample to the complete destruction of the sample.
The inflection point at which a crack or the specimen is destroyed before half the width, or the sample is completely destroyed, is not counted in the calculation.
Criteria for evaluating test results are specified in normative and technical documentation for metal products. In the absence of such instructions, the test is stopped at the crack.
4.2. In the test report indicate:
brand metal or labelling of samples;
the dimensions of the samples;
the radius of the rollers;
distance ;
the magnitude of the preload;
the results of the test.
4.1, 4.2. (Changed edition, Rev. N 1, 2).
The text of the document is verified by:
the official publication of the
M.: IPK Publishing house of standards, 1999
