Release time：2020-01-16 18:44 Browse：
In China, the outer hexagonal long screw in the extension screw as a common fastener is widely used in machinery, construction, automobile, aerospace and other fields. Its diverse standards and specifications not only meet the needs of different industries, but also reflect the maturity and development of China's fastener industry. This paper will discuss the domestic standard system of outer hexagonal long screws from many angles, including national standards, industry standards, international standards and special application standards.
1. National standard system
The national standards for outer hexagonal long screws are mainly formulated and released by the National Standardization Management Committee (SAC), the most representative of which are GB/T 5782-2016 "Hexagon head bolts A and B" and GB/T 5780-2016 "C Hexagon head bolts". These standards specify the requirements of the size, tolerances, materials, mechanical properties, surface treatment and other aspects of the outer hexagonal long screws to ensure the quality and interchangeability of the products.
- GB/T 5782-2016: This standard applies to Class A and B hexagon head bolts, covering a wide range of specifications from M6 to M64, for applications requiring higher strength and precision. The standard not only specifies the screw thread size and head size of the bolt, but also specifies the chemical composition, mechanical properties and surface treatment methods of the material, such as galvanizing and blackening.
- GB/T 5780-2016: This standard for class C hexagon head bolts, compared with class A and class B, its accuracy and strength requirements are slightly lower, but the cost is more economical, suitable for occasions with low precision requirements. The standard also contains the size of the bolts, tolerances, materials and other aspects of the provisions.
In addition, there are standards such as GB 838-1988 "Hexagonal head non-slipping screws", which provide detailed provisions for specific types of outer hexagonal screws.
Second, industry standards and special application standards
In addition to national standards, industries have also developed corresponding industry standards or special application standards according to their own needs. For example, in the aerospace field, there is a special fastener standard system, such as EN 3007-1996 "Aerospace - hexagonal head bolts, thin rods, long threads", etc. These standards put forward more stringent requirements on the material, strength, temperature resistance of bolts to meet the needs of extreme environments.
In the automotive industry, outer hexagonal long screws also need to meet specific industry standards, such as ISO 4014 and ISO 4016, which focus not only on the mechanical properties of bolts, but also on their compatibility and safety with other parts of the car.
3. International standards
With the in-depth development of globalization, China's outer hexagonal long screw standards are also gradually in line with international standards. For example, DIN (German industrial standards), ANSI (American National Standards Institute) and other international standards are also widely used in our country. The DIN 931 series standard is an international standard for hexagon head bolts, covering a variety of specifications from M1.6 to M64, and its precision and strength levels are also detailed, providing an important reference for China's fastener industry.
4. Special specifications and customized services
In addition to the above standard regulations, there are also a large number of special specifications of outer hexagonal long screws on the market, which are often customized according to the specific needs of customers. Customized services not only require manufacturers to have advanced production equipment and processes, but also need a professional technical team for design and development. Through customized services, customers can obtain fastener products that fully meet their requirements for use, improving the overall performance and reliability of the equipment.
V. Summary and outlook
In summary, the external hexagonal long screws in the domestic extension screws have a perfect standard system, including national standards, industry standards, international standards and special application standards. These standards not only guarantee the quality and interchangeability of products, but also provide diverse choices for different industries. In the future, with the progress of science and technology and the development of industry, the standard system of outer hexagonal long screws will be further improved and optimized to meet the needs of more complex and diversified use. At the same time, strengthening the integration and cooperation with international standards will also become an important direction to promote the development of China's fastener industry.
