The strength of the spring steel wire varies according to the variety, standard and specification, and the tensile strength grade can be in the range of 1000-3000 MPa.
The diameter of the round spring steel wire is in the range of 0.08-20 mm.
The cross-sectional shape of spring steel wire is generally round, but also rectangular, square, oval and other shapes.The finished steel wire is generally delivered in rolls, or delivered in straight strips.
Different types of spring steel wires have different production methods, and the common characteristics are that they require certain strength, high toughness and good coil spring performance.
The crafting methods of various spring steel wires are as follows:
Raw spring steel wire process: (steel) wire rod-surface treatment-wire drawing (mattress wire can be used in this way)
Lead-quenched spring steel wire: Lead bath quenching is performed on the wire rod size or the intermediate specification of cold drawn, and then surface treatment and wire drawing.
Galvanized spring steel wire: usually hot-dipped or electroplated in the finished size, but also cold drawn to the specified size after pickling and hot-dipping the wire rod.
Surface treatment: Generally, pickling and phosphating are used to remove the iron oxide scale to form a phosphating film; a few are treated by mechanical methods. The purpose is to meet the requirements of the cold drawing process and obtain a smooth surface. For spring steel wires that require high fatigue life , Such as the valve spring wire, the wire rod should be peeled to reduce surface defects. If the steel mill can grind the billet, it will also help reduce defects.
Oil-quenched spring steel wire: Carbon steel or alloy steel can be used according to the needs, surface treatment and cold drawn to the finished size, and then quenched and tempered. This process is used more on steel wires for automobile suspension springs and valve springs, ordinary springs Of course it can also be used.
Wire drawing: The drawing process of the finished product has a great influence on the product performance. Generally, a larger total area reduction rate of about 90% (see area reduction rate) and a smaller pass reduction rate (about 10%- 20%) to ensure the toughness of the product. For high-strength spring steel wire, the outlet temperature of each pass of the steel wire should be controlled to be lower than 150 ℃ during drawing to prevent the steel wire from torsion cracks due to strain aging, which causes the wire to be scrapped.
The main defect. For this reason, good lubrication and sufficient cooling must be provided during drawing. The use of a smaller pass reduction and drawing speed can help reduce the temperature rise of the steel wire. Heat treatment: lead bath is commonly used for carbon steel spring steel wire The quenching process can obtain a very fine pearlite structure (sortenite), which is beneficial for improving deep drawing performance and spring performance. The alternative process of lead bath fluidized bed has not been promoted, and there are currently some small diameters.
Application. Alloy steel wire generally adopts annealing heat treatment to make the microstructure suitable for drawing deformation. The heat treatment of stainless steel wire adopts solution treatment, and the purpose is to improve the structure to meet the needs of drawing. The oil quenching process is used on the finished steel wire, and induction Heating or gas or oil heating furnace, the steel wire is heated to the austenitizing temperature for a period of time, and then tempered at a medium temperature after quenching. Although it is called oil quenching in name, it basically uses water quenching or water with polymer materials. Quenching.
Hardware springs can be divided into static springs and dynamic springs according to their operating conditions. Static springs refer to springs that have a limited number of vibrations during the service period, such as safety valve springs, spring washers, weighing pan springs, constant load springs, mechanical springs, watch hair springs, etc.
Refers to springs that have a vibration frequency of 1×106 or more during the service period, such as engine valve springs, vehicle suspension springs, anti-vibration springs, coupling springs, elevator buffer springs, etc. The selection of static springs mainly considers tensile strength and stability, dynamic When selecting spring materials, fatigue, relaxation and resonance performance are mainly considered.
Springs can be divided into three states according to the load conditions: light load, general load and heavy load. Light load refers to springs that bear static stress, low stress, and small deformation, such as springs for safety devices and springs for vibration absorption. Design The service life is 103~104 times.
General load refers to a common spring with a design life of 105~106 times and a vibration frequency of 300 times/min. Within the allowable stress range, the life is guaranteed 1×106 times. The lower the load stress, the longer the life.
Heavy load refers to springs that work for a long time and frequently vibrate. For example, valve springs, air hammers, presses, and hydraulic controller springs have high loads, often used at about 10% below the allowable stress, and their service life is greater than 1×106 Times, usually 107 times.