GOST R 50753-95 Helical cylindrical compression and tension springs made of special steels and alloys. General technical conditions / 50753 95

4.3 Marking

4.3.1 Springs are marked on tags by stamping, engraving or waterproof paint. The tag is attached to the spring or packaging area. For springs made of wire with a diameter of more than 5 mm, it is allowed to apply electrographic markings on one of the support turns.

4.3.2 Marking includes the following information:

— trademark of the manufacturer;

— month and year of issue;

— spring (batch) number;

— drawing number or symbol of the spring;

— by agreement between the customer and the manufacturer, other necessary information can be included in the marking.

Helical coil springs compression and extension

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Note. The specified endurance does not apply to extension spring hooks.

2. Spring discharges (according to GOST 13764-86)

Notes: 1. The maximum shear stress during torsion is given taking into account the curvature of the turns. 2. Rm -

tensile strength of spring materials

Increases in the difference τ3 ~ τ2 cause an increase in the endurance and durability of cyclic springs of all classes while simultaneously increasing the size of the units. A decrease in the differences τ3 - τ2 is accompanied by reverse changes in the service qualities and sizes of spaces in the mechanisms for placing springs. For class I springs, the design stresses and properties of the metal are regulated in such a way that when vmax /vk < 1, the specified endurance of the springs under the action of force F1 (spring force at preliminary deformation) of at least 0.2 F3 (spring force at maximum deformation) is ensured at all feasible locations and sizes of working sections on the force diagrams of the stress difference τ3 - τ2 and τ2 - τ1 (tangential stress during preliminary deformation). Class II cyclic springs with vmax /vk < 1, depending on the location and size of the working sections, can be subjected to conditions of both unlimited and limited endurance. Class III cyclic springs with all ratios vmax /vk and a relative inertial spring gap d of no more than 0.4 are characterized by limited endurance, since they are designed for extremely high tangential torsional stresses, to which, at vmax /vk > 1, contact stresses from the collision of the coils are added. All static springs that remain in a deformed state for a long time and are periodically loaded at a speed vmax / vk belong to class II. The introduced restrictions on design stresses and wire properties (see Table 2) ensure unlimited resistance of static springs with residual deformations of no more than 15% of the maximum deformation s3. The permissible residual deformations of static springs are regulated by the coordination of the spring forces at the working deformation s3 on the force diagrams, with an increase in the difference F3 - F2

helps reduce residual deformations. Technological means of regulating the endurance and resistance of springs are determined by the technical requirements documentation.

MATERIALS FOR SPRINGS

Carbon steel spring wire in accordance with GOST 9389-75. The standard applies to cold-drawn carbon steel wire used for the manufacture of cold-wound springs that are not quenched. The wire is manufactured: according to mechanical properties: grades A, B, C; classes 1, 2, 2A, 3 (recommendations for the use of spring wire depending on brands and classes are given in Table 3); by manufacturing accuracy: normal accuracy; increased precision P. Wire of classes 1, 2, 3 is manufactured with normal and increased accuracy, class 2A - with increased accuracy. The diameters of the wire and the weight of 1000 m of wire are indicated in the table. 4.

3. Recommendations for the use of spring wire according to GOST 9389-75

Note. Relative strength run-up index K

calculated using the formula K= Δsв/sв, where Δsв is the run-up of tensile strength in a batch, N/mm2; sв is the minimum value of tensile strength in a class, N/mm2

4. Wire diameters and theoretical weight of 1000 m of wire

The mechanical properties of the wire are given in table. 5. Examples of designations: Wire grade A, class 1, increased accuracy, diameter 1.20 mm:

Wire A-1-P-1, 20 GOST 9389-75

The same, brand B, class 3, normal accuracy, diameter 2.00 mm:

Wire B-3-2.00, GOST9389-75

Steel grade 65G. Increased tendency to form hardening cracks. They are used to reduce the cost of production for mass-produced products in cases where spring breakages do not cause disruption in the functioning of mechanism parts and replacing springs is not labor-intensive.

Steel grade 51HFA.

Increased heat resistance. Hardened to a hardness of no more than 53HRC. Due to its high elastic and viscous properties, it is the best material for class 1 springs. It is unsuitable for class 3 springs due to insufficient hardness.

Steel grades 60С2А, 60С2.

High elastic and viscous properties.
Increased tendency to graphitization and insufficient hardenability for sections d >
20 mm. Widely used for springs of classes 1 and 2. For springs of class 3 they are prescribed for vmax < 6 m/s.

Steel grade 65S2VA. High elastic properties and viscosity. Increased hardenability. Serves as the best material for class 3 springs. Used for vmax > 6 m/s.

Steel grade 60S2HFA. High hardenability, low tendency to grain growth and decarburization when heated (compared to 60C2A steel), increased toughness, heat resistance and cold resistance, good cyclic strength and relaxation resistance in a wide range of cyclic temperature changes. Preferred use in wire sections of 30 mm and above.

Steel grade 70SZA. Increased hardenability. Has a tendency to graphitize. Preferred use with wire diameters d

£20mm.
The substitute is steel 60S2N2A. Note.
The predominant practical use of springs made of 51KhFA steel is determined by the temperature range from - 180 to +250 °C, from 60S2KhFA steel from - 100 to +250 °C, from class 2A wire according to GOST 9389-75 from - 180 to +120 °C, from steels 65G, 70SZA, 60S2A, 65S2VA and from wire of class 1 according to GOST 9389-75 from - 60 to + 120 °C. In cases where springs are used at higher temperatures, it is recommended to take into account the temperature changes of the module.

Special steel alloy spring wire (according to GOST 14963-78)

. Designed for the manufacture of springs subjected to heat treatment (hardening and tempering) after winding.

The wire is divided: according to the manufacturing method and the quality of surface finishing into groups: with special surface finishing by removing the surface layer - A, B, C, D, E; without special surface finishing H; by manufacturing accuracy: normal accuracy; increased accuracy P; by purpose: for cold coil springs XN; for hot coil springs GN; according to mechanical properties, surface quality into classes: 1 - for springs for critical purposes; 2 - for general purpose springs.

Nominal wire diameters, mm: 0.5; 0.56; 0.60; 0.63; 0.71; 0.80; 0.90; 1.10; 1.20; 1.25; 1.30; 1.40; 1.50; 1.60; 1.80; 2.0; 2.20; 2.50; 2.80; 3.00; 3.20; 3.50; 3.80; 4.00; 4.20; 4.50; 4.80; 5.00; 5.50; 5.60; 6.00; 6.20; 6.30; 6.50; 7.00; 7.10; 7.50; 8.00; 8.50; 9.00; 9.50; 10.00; 11.00; 11.20; 11.50; 12.00; 12.50; 13.00; 14.00.

Wire of groups A, B, C, D should be made with a diameter of 1-14 mm, wire of groups E, H - with a diameter of 0.5-14.0 mm.

An example of the designation of wire made of steel grade 51HFA, with a special surface finish, polished, group A, increased accuracy, class 1 for cold coil springs, diameter 1.80 mm:

Wire 51ХFA-А-П-1-ХН-1.80 GOST 14963-78

Technical requirements. The wire must be made of steel grades 51KhFA, 60S2A, 65S2VA, 70SZA in accordance with GOST 14959-79. The tensile strength of wire for cold coil springs should be no more than 1029.5 MPa.

5. Mechanical properties of spring wire according to GOST 9389-75 as amended. 1990