Mold is the main process equipment of industrial production. The development of modern industrial products and the improvement of technical level, to a large extent, depends on the development level of die and mold industry. Since the Second World War, the improvement of automation level has made the rapid development of foreign mold. In recent years, the domestic mold industry has developed rapidly. With the development of die and mold industry, the number and specification of die spring are increasing. From the spring structure form, the development of international mold spring has gone through 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 ordinary spring can meet the requirements of the 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 cylindrical spiral die rose and applied. During this period, the automobile industry, chemical equipment, construction machinery, aircraft and railway locomotives were upgraded, and the development of plastic industry required to improve the working frequency and bearing capacity of the mold. Therefore, the bearing deformation characteristics and fatigue life of the original cylindrical cross-section spring were difficult to meet the requirements of the mold, so rubber and square cross-section mold appeared With spring.
3. From the end of 1960s to the middle of 1970s, the application and development stage of special section steel wire (rectangular, flat and s, D, S-shaped, etc.) die 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 instruments (testing and measuring instruments, etc.), the mold was required to develop in the direction of small size, high speed and multi position, which promoted the development of powerful die spring.
During this period, the large size (socket diameter more than 20) mold power spring has been widely used and popularized. There are three outstanding characteristics in this stage in the world: (1) the coverage of mold using strong spring is expanded. (2) The enterprise standard and national standard of die spring are worked out. (3) The types of special-shaped steel wire increased, such as rectangular, flat and s, D, s shape.
4. From the mid-1970s to the present, 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 mold. 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.
The above four stages are mainly divided according to the application and development of die spring in advanced industrial countries. At present, the domestic mold spring mainly uses circular cross-section ordinary cylindrical spiral spring and some rubber springs (about 90%). The application of special-shaped section steel wire die spring started in the 1980s. At present, the number and scope of application are slowly increasing
(1) It is used to replace the powerful spring on imported mould (mainly Japan and Germany) and imported equipment.
(2) Some farsighted mold designers, in the design, began to try.
(3) Because die spring belongs to labor-intensive products, its price is higher abroad. So. Foreign countries also buy small quantities of die springs from China for trial sale, and some foreign businessmen also replace these springs with “neutral” brand and sell them back to China. At present, the main export is light load, small size (socket diameter is 10-25) mold spring. To sum up, the special-shaped steel wire die spring is only in the initial stage of application in China.
1、 Application status
At present, steel wire cylindrical spiral compression spring, rubber (neoprene and polyurethane rubber) spring, nitrogen filled spring and disc spring with circular section or special section (square, rectangular, flat and s, D, s shape, etc.) are applied in different types of dies. But from the application scope and quantity analysis: the circular cross-section steel wire spiral spring is declining, the special-shaped cross-section steel wire, especially the flat and s, D, S-shaped steel wire cylindrical spiral spring is increasing, the rubber spring, especially the polyurethane rubber spring, tends to increase steadily, while the disc spring and nitrogen filled spring are still in the small batch trial stage, it seems that there is a certain market The comprehensive evaluation of its application prospect in terms of maintenance and economy is still to be discussed after practice.
2020-07-20