Production of 12.9 grade high-strength socket head cup head screws 3/4 1/4-20

The history of screws was broadcast in 1986. Our country formulated a new standard for standard parts, which is commonly known as the new standard in the business. The most used ones are GB5780, GB5781, GB5782, GB5783, GB5784. GB5780 is a hexagonal head thick shank half-thread screw, its accuracy grade is C-grade product, which can be replaced by GB5782 (GB5782 is a hexagonal head thick shank full-thread screw, and its accuracy grade is grade A and B.) GB5781 is a hexagonal head full-thread screw. Threaded screw, the accuracy grade is C grade product. It can be replaced by GB5783 (GB5783 is a hexagonal head full-tooth screw, and its accuracy grades are A and B). GB5784 is a hexagon screw with thin rod and half teeth.

As the most common hardware, screws and nuts are widely used in construction and machinery fields. However, existing screws and nuts are easily corroded to varying degrees in the natural environment, especially the threads on screws and nuts are corroded After that, the whole screw and nut are useless, and people have to discard them, which will inevitably lead to a lot of waste of resources.

rivet with a simple structure includes a rivet cap, a rivet main rod, a rivet limit rod and a limit hole. The rivet main rod is provided with a limit hole inside, the rivet limit rod is located below the rivet main rod, the upper end side of the rivet limit rod is provided with a limit groove, the limit groove is connected with the lower end of the rivet main rod, and the groove surface of the limit groove is round. arc-shaped, the lower end side of the rivet limit rod is provided with four limit grooves, the cross section of the limit groove is in the shape of a right-angled trapezoid, the limit hole passes through the interior of the rivet limit rod and the rivet main rod, and one end of the limit hole The hole surface and the lower end surface of the rivet limit rod are on the same plane.

The flat washer is mainly used to reduce the pressure. When some parts are tightened with a large axial force, it is easy to press the washer into a dish shape. At this time, it can be solved by changing the material and increasing the hardness.

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