The development of modern industrial products and the improvement of technical level depend largely on the development level of die and mold industry. Since the Second World War, the improvement of automation level has made the foreign mold develop rapidly. In recent years, the domestic mold industry has developed rapidly, The application quantity and specifications of die spring are also increasing. From the spring structure, the development of die spring in the world has experienced four stages
1. From the mid-1940s to the late 1950s, the main structural form of die spring was round cross-section steel wire ordinary cylindrical spiral spring. At this stage, the mold industry mainly served the motor vehicles, mining, machine tool and textile industries, which recovered rapidly after the war. There was no breakthrough in performance improvement, Therefore, the common spring can meet the requirements of die and mold. From the nearly 3000 papers on spring published in the United States, Britain, France, Japan, West Germany, the Soviet Union, Austria, Canada, Belgium and other countries from 1952 to 1962, there is no article on die spring
2. From the end of 1950’s to the end of 1960’s, rubber spring and powerful spring of square steel wire cylinder spiral die rose and applied. During this period, the automobile industry, chemical equipment, construction machinery, aircraft and railway locomotive were upgraded. The development of plastic industry required to improve the working frequency and bearing capacity of the molds, The bearing deformation characteristics and fatigue life of the original cylindrical cross-section spring are difficult to meet the requirements of the die, so rubber and square cross-section die spring appear
3. From the end of 1960s to the middle of 1970s, the application and development stage of special-shaped cross-section steel wire (rectangular, flat and s, D, S-shaped, etc.) mold spring was developed. During this period, due to the development of electronic equipment (computer, communication and audio products, etc.), optical equipment (camera, copier, etc.) and precision instrument (testing and measuring instrument, etc.) products, It is required that the die should be small, high speed and multi position
During this period, the large-size die spring with hole diameter more than 20 has been popularized and used. There are three outstanding characteristics in the world at this stage: (1) the coverage of the powerful spring used in the mold is expanded; (2) the enterprise standard and national standard of the mold power spring are compiled; (3) the types of special-shaped steel wire are increased, such as rectangular, flat and s, D, s shape
4. From the middle of 1970s to now, it is the development stage of small size (socket diameter is 10-20) special-shaped cross-section steel wire die spring, disc spring and nitrogen spring for die. This is mainly due to the development of small plastic mold and large stamping die
On this basis, the draft of international standard (ISO / DIS 1043) was compiled in 1990, which marks the transition of die spring from basic part to standard part and will be popularized in the world