Suzhou Zhaoneng Precision Spring Hardware Co., Ltd.
Address£ºNo. 161, Shilin Road, Suzhou High-tech Zone
The choice of spring material, should be based on the nature of the spring to bear the load, stress state, stress size, operating temperature, environmental media, service life, the requirements of the conductive magnetism, process performance, material sources and prices and other factors.
In determining the material cross-sectional shape and size, should be the preferred national standards and ministerial standards set by the series of sizes, try to avoid the use of non-standard series of specifications of the material.
Medium and small springs, especially helical tension springs, shall be given priority to reinforced steel wire, lead bath and other cold drawn steel wire and oil quenched and tempered steel wire, with high strength and good surface quality, fatigue performance is higher than ordinary hardening Tempering steel wire, simple processing, good technology, quality and stability.
Carbon spring wire and piano wire after cold drawn have a greater residual stress, after processing the spring, there is a large residual stress, size changes after tempering large, difficult to control the dimensional accuracy. Oil quenching and tempering steel wire is in the steel wire is drawn to the specified size after the modulation and strengthening treatment, there is no substantial residual stress, forming spring after low temperature tempering, the dimensional change is very small, better thermal stability than cold drawing Reinforced steel wire.
Large and medium-sized spring, for the load accuracy and stress should be used in cold drawn material or cold-drawn polished steel. For load accuracy and low stress spring, can choose hot-rolled steel.
Leaf spring generally use 55Si2Mn, 60Si2MnA, 55SiMnVB, 55SiMnMoV, 60CrMn, 60CrMnB and other brands of flat steel.
The material of the coil spring section, should be preferred circular cross-section. Square and rectangular cross-section material, strong bearing capacity, good impact resistance, but also allows the miniaturization of the spring, but the material source less. And the higher the price, in addition to special needs, the general try not to use this material. In recent years, the development of round steel wire rolling instead of trapezoidal wire, and achieved good results.
Working at high temperatures of the spring material, requires a good thermal stability, anti-relaxation or creep capacity, oxidation resistance, resistance to certain media corrosion.
Spring operating temperature increases, the elastic modulus of spring materials decreased, resulting in lower stiffness, load capacity smaller. Therefore, the spring at high temperature must understand the rate of change of elastic modulus (value), calculate the spring carrying capacity decline on the use of performance. In accordance with the provisions of GB1239, ordinary coil spring operating temperature exceeds 60 ¡æ, the shear modulus should be amended, the formula is: Gt = KtG where G - at room temperature elastic modulus; Gt - operating temperature t Kt - temperature correction coefficient selected according to Table 2-98.
In the low temperature of the spring material used should have good low temperature toughness. Carbon spring steel wire, piano wire and 1Cr18Ni9 austenitic stainless steel spring steel wire, copper alloy, nickel alloy has good low temperature toughness and strength.
At low temperatures, the brittleness of the material is very sensitive to surface defects, therefore, the surface quality of the material should be strictly required.
At low temperatures, the environment medium is much less corrosive to the material than in the greenhouse, while cadmium plating and galvanizing can cause cold brittle.
At low temperatures, the modulus of elasticity and the coefficient of expansion of the material change little, in the design can not be considered.
Spring steel spring, hardness (ie, strength) should be selected according to the spring bearing properties and the size of the stress may be. However, the relationship between the hardness and the plane strain fracture toughness is great.
From the curve, it can be seen that the plane strain fracture toughness (KIC) decreases with the increase of hardness. This means that in determining the hardness of the hardness of the spring should be based on the characteristics of the spring to meet the requirements of the premise, the lower the hardness of the spring some good.
Spring selection, we should pay attention to the hardenability of steel. The cross-section of the spring material is quenched and the degree of hardenability, a great relationship between the quality of the spring.
The spring itself as a conductor of the electrical spring or in the humidity change of the conditions, such as water (including sea water), water vapor spring working environment, the general choice of copper and gold materials.
In acid contact with other corrosive media under the work of the spring, the general choice of acid-resistant stainless steel or nickel alloy corrosion resistant materials. In the general environment of the use of medium conditions of the spring, the choice of ordinary spring steel, spring made after the surface of its anti-rust coating or plating (galvanized, cadmium, copper) method of corrosion.
In weighing instruments and instruments used in the spring, in order to meet the accuracy of temperature from the impact of the general choice of elastic modulus and expansion coefficient changes in a very small constant elastic alloy.
In the requirements of light, insulation, anti-collision, anti-rust and other special use of the spring, the choice of reinforced plastic. At present, the more suitable plastic spring, is epoxy resin, phenolic resin as the matrix, with glass fiber reinforced thermosetting reinforced plastic GFRP. Can also use anti-vibration rubber manufacturing various types of rubber spring.