1、 Brief review of the development history of quenched tempered spring steel wire
Oil quenching tempering spring steel wire production technology originated in Europe, and its representative enterprise is Swedish gaffeten company. And Bekaert, Belgium. Soon the technology spread to Japan, and its representative enterprises are Kobe, Sumitomo, Gao Zhoubo, etc. In the early 1970s, China began to study its own oil quenching tempering spring steel wire production technology.
In the process of research on the production technology of oil quenched tempered spring steel wire in China, the engineering and technical personnel in the wire drawing workshop of the former Beijing special steel works and the teachers and students of the former Beijing Institute of iron and steel (Beijing University of science and Technology) have made outstanding contributions. In October 1974, the technology was successfully put into mass production in the wire drawing workshop of the former Beijing special steel plant, which opened a new chapter in the production of oil quenched tempered spring steel wire in China, and maintained the situation that the plant has been in the domestic market for nearly 20 years.
During this period, under the system of planned economy, some iron and steel enterprises have put this technology into trial production, but it has not been realized due to the problems of mechanism and technology. After the reform and opening up, especially in recent years, with the rapid development of automobile industry, motorcycle industry, diesel engine industry and machinery industry, China has gradually become the development trend of world processing base. And interest temptation makes all kinds of capital compete to enter the industry. More than a dozen oil quenched tempered spring steel wire manufacturers have emerged, such as Zhengzhou metal products research institute, pilot plant No.2, Henan Hebi, Zhengzhou Xinya, Tianjin Dihua, Tianjin Xinhao, Jiangsu Shenwang, Shanghai Sanlian, Hunan sipuling, Nanjing Dongwu, Zhejiang Haina, etc. And there are still domestic and foreign capital invested in the industry.
2、 Brief review of the development history of oil quenching tempering spring steel wire technology
In the research of oil quenching tempering spring steel wire production technology in China, the technical standards and process ideas of Sweden and Japan are mainly referred to. But in the early stage of research and development, due to the problems of technology, equipment, production efficiency and product cost, it took a detour. It was not until the late 1980s and early 1990s that the production process of oil quenched tempered spring steel wire in China was basically stable. According to the commonly used materials in China, the product stability is as follows: 50CrVA, 60Si2MnA, 65Mn, 70#, 82B, 55CrSi, sup12, sae9254, 55crsiv.
3、 A brief review of quality development history of oil quenched tempered spring steel wire in China
The quality of oil quenched tempered spring steel wire in China is not stable to basically meet the requirements of middle and low end spring products, and many quality problems are encountered. Some problems have been solved, and some problems still need to be further studied.
The problems that have been basically solved are as follows:
1. Brittle fracture of steel wire (natural fracture and wound spring fracture)
2. Problems caused by poor decarburization process
3. Crack problem (raw material problem, poor process)
4. Uneven size problem (poor processing)
5. Sickle bending problem (poor processing)
6. Dimensional accuracy
Although the above single problems have been basically solved in China. However, these problems still affect the comprehensive properties of oil quenched tempered spring steel wire. The specific performance is that the performance of steel wire strip is unstable, which leads to the increase of spring instability, especially the fatigue life of valve spring can not meet the specified requirements.
In order to narrow the quality gap between China’s oil quenched tempered spring steel wire and foreign products, it is necessary to further improve the cognitive level of this kind of product and increase the investment in research and development, technology and equipment. At the same time, strengthen the cooperation with raw material manufacturers. Ensure the product quality to a new level, otherwise we can only hover in the field of low-end spring products.
4、 Characteristics of oil quenched tempered spring steel wire
1. The ratio of yield to strength is high and the residual deformation of spring is small.
2. The performance of the strip is stable: the same disc difference is less than 75mpa, which is beneficial to coil spring and improve the fatigue life of spring.
3. Compared with the traditional spring production method, some procedures after winding the spring can be omitted.
4. The coil spring has high yield and can reduce the cost.
5、 Application scope of oil quenched tempered spring steel wire
Oil quenched tempered spring steel wire can not completely replace cold drawn spring steel wire. Especially the small size spring steel wire. Oil quenched tempered spring steel wire is developed for the anti fatigue performance of valve spring and suspension spring. In order to achieve the best effect, shot peening should be combined after the spring winding. Spring manufacturers should pay attention to the aging effect when storing this kind of steel wire. After winding the spring with this kind of steel wire, the following treatment should be carried out in time.
Avoid loss due to improper use. In recent years, with the improvement of the cognitive level of this kind of product, this kind of product is gradually applied to clutch spring and automobile rigging and other products. Whether the oil quenched tempered spring steel wire can fully meet the requirements of tension spring, torsion spring, special-shaped spring and the spring that needs coating needs to be further discussed.
6、 Brief analysis on market situation of oil quenched tempered spring steel wire
China will become the world’s processing base and the largest market in the world. Because of this, the market competition of oil quenched tempered spring steel wire will be more heated. Although some large spring factories use imported steel wire at present, there are some limitations due to delivery time, price and other issues, and most spring enterprises still choose to use steel wire from domestic enterprises. However, with the increase of domestic production enterprises, competition is bound to intensify, especially in May this year, the “giant Mac” factory jointly invested and built by a domestic enterprise and two Japanese enterprises in Shanghai was put into operation