(5) the development of spring steel wire
After more than 100 years of development, the technology of spring steel has experienced lead hardened to oil quenching, and now it develops to induction hardening. Coupled with the continuous innovation and improvement of technology and equipment, the quality of varieties is constantly updated. The newly developed valves have been developed by induction heating and tempering with spring steel wire. It has been proved that the plastic, toughness, relaxation, fracture toughness, delayed fracture resistance, fatigue life and so on are all compared with oil quenched and tempered steel because of the short induction heating time, small quenching microstructure and almost no decarburization layer on the surface of steel wire. The silk has a great improvement.
Another kind of superfine grain deformation heat treated steel wire has been applied in the field, and the superfine grain deformation heat treatment is a composite strengthening and toughening process combined with the combination of microstructure superfine and deformation heat treatment. It can not only improve the mechanical properties of steel wire, but also improve the surface quality of steel wire. The surface quality of the material has a great influence on the fatigue performance. In order to ensure the surface quality, the skinning process is applied to the materials with special requirements, and the surface layer is removed by 0.1mm. Eddy current testing is used for the defect of 0.5mm depth. The surface roughness of the wire drawing process can be reduced by electrolytic grinding to = (6.5~3.4) m.
(6) the development of stainless steel wire
In recent years, the production of stainless steel spring wire abroad has developed rapidly. The main varieties of domestic demand are 1Cr18Ni9 and 0Cr17Ni7AI.
The characteristics of advanced steel wire production process are that the wire strip is first peeled to remove the defects caused by hot processing on the surface. Except for the first solution treatment, the whole cold process will keep the bright surface.
With the development of the technology, the production process of non embroidered steel wire is further simplified, and the quality control of part of the metal products industry is simplified and converted to the requirement for the quality of the wire rod. After the wire drawing machine, clean the ball and wipe with water, remove the surface coating and residual lubricating film. Electrolysis acid washing, alkali neutralization, water washing and drying devices are installed before the heat treatment. The surface oil quality of the steel wire is thoroughly removed and the surface quality is improved.
(7) development of shape memory alloy
At present, there is a promising unidirectional shape memory alloy in spring, with the best performance of 50Ti and 50Ni. The spring made of shape memory alloy is telescopic under the action of temperature. It is mainly used in constant temperature, constant load and constant deformation control system. Because the spring is telescopic to actuate the actuating mechanism, the working stress of the spring varies greatly.
(8) the application of ceramics
The ceramic has high modulus of elasticity and low fracture strength, which is suitable for places where deformation is not large. Currently, heat-resistant, wear resistant, and insulating ceramics are being developed. Superplastic zinc alloys (SPZ) are used and have high strength at room temperature. In addition, high strength silicon nitride can withstand high temperatures up to 1000 degrees Celsius. But ceramic springs are not suitable for working under impact load.
(9) the application of fiber reinforced plastic in spring
Glass fiber reinforced plastic (GFRP) leaf spring has been widely used in Britain, the United States and Japan. In addition to the suspension suspension, it can also be used for special light vehicles, such as the longitudinal suspension of the car. A carbon fiber reinforced plastic (GFRP) suspension spring has been developed, which is 20% lighter than the metal leaf spring.