1. DIN 603 product size standards: specify the content of basic product size; Products with threads also include the basic dimensions of threads, thread ending, shoulder distance, relief groove and chamfer, end dimensions of externally threaded parts, etc.
2. DIN 603 Standard for Technical Conditions of Products. Mainly includes product tolerance, mechanical properties, surface defects, surface treatment, product test standards and the corresponding specific provisions.
3. Standards for inspection, marking and packaging of screw products: specify the qualified quality level and sampling plan of spot check items when products leave the factory for acceptance, and the content of product marking methods and packaging requirements.
4. Standard Parts, DIN 603, Marking Method Standard for Screws and Screws: Specify the complete marking method and simplified marking method for products.
5. DIN 603 standards for other aspects: such as DIN 603 terminology standards, DIN 603 product weight standards, etc.
Judging from the stress characteristics, the Round Head Bolt exerts pre-tension and transfers external force by friction. Common bolt connection transfers shear force by bolt shear resistance and hole wall bearing pressure. The pretension force generated when tightening nuts is very small, and its influence can be ignored. Besides its high material strength, high-strength bolts also exert a large pretension force on bolts, causing extrusion force between connecting members, thus causing a large friction force perpendicular to the screw direction. Moreover, pretension force, slip resistance coefficient and steel type all directly affect the bearing capacity of high-strength bolts.
According to the stress characteristics, it can be divided into pressure-bearing type and friction type. The two calculation methods are different. The minimum specification of high-strength bolts is M12, and M16~M30 are commonly used. The performance of super-large bolts is unstable, so they should be carefully used in design.