The physical classification of the metal spring

Springs can be divided into static reeds and dynamic reeds according to the operating state.

Static springs refer to springs with a limited number of vibrations during service, such as safety valve springs, spring pads, scale coil springs, fixed-load springs, mechanical springs, watch filaments, etc.

Dynamic spring refers to the number of times the service vibration of more than 1 x 106 times spring, such as engine valve springs, vehicle suspension reeds, shock-proof springs, coupling springs, elevator buffer springs and so on.

Static spring material selection mainly considers tensile strength and stability, dynamic spring selection mainly consider fatigue, relaxation and resonance performance.

According to the load condition, the spring can be divided into three states: light load, general load and heavy load. Light load refers to the static stress, low stress, less deformation of the spring, such as safety device sghes, absorption of vibration with spring. Design life 103 to 104 times.

General load refers to the design life of 105 to 106 times, in the vibration frequency of 300 times / min conditions used in the ordinary spring. In the range of permitted stress, the life is guaranteed 1 x 106 times, the lower the load stress, the longer the life.

Heavy load refers to a spring that works for long periods of time and vibrates frequently. Such as valve springs, air hammers, presses, hydraulic controller springs, its high load, often below the required stress of about 10% use, service life greater than 1 x 106 times, usually 107 times.

The selection principle of spring wire.

The principle of spring selection is: first to meet the functional requirements, followed by strength requirements, and finally to consider economics.

Carbon spring steel is a widely used and the largest amount of steel in spring steel. Steel contains 0.60% to 0.90% carbon and 0.3% to 1.20% manganese, no longer add other alloy elements, the cost of use is relatively low. Carbon spring wire by proper processing or heat treatment, can obtain a high tensile strength, sufficient toughness and good fatigue life.

However, the citability of carbon wire is low, anti-relaxation and corrosion resistance is poor, and the temperature coefficient of elastic modulus is large (up to 300 x 10-6/C), which is suitable for the manufacture of springs with a smaller cross-section and a lower operating temperature (120 degrees C).

Alloy spring steel generally contains 0.45% to 0.70% carbon and a certain amount of Si, Mn, Cr, V, W and B alloy elements. The addition of alloy elements improves the anti-relaxation properties of spring steel, improves the toughness of the steel, and significantly improves the quenchability and temperature of the steel, making it suitable for the manufacture of springs with larger cross-sections and higher temperatures.