Application standards and scope of high-strength nuts

Application standards and scope of high-strength nuts

Application standards and scope of high-strength nuts

Reference standard for specifications of large hexagonal nuts

GB/T90-1985 Acceptance Inspection, Marking and Packaging of Fasteners (EQV ISO3269:1984)

GB/T196-1981 Ordinary thread, basic dimensions (diameter 1~600mm)

GB/T197-1981 General Purpose Threads, Tolerances and Fits (Diameter 1-355mm)

GB/T1237-2000 Fastener Marking Method (EQV ISO 8991:1986)

GB/T3098.2-2000 Mechanical Properties of Fasteners - Nuts, Coarse Thread (IDT ISO 898.2: 1992) GB/T3103.1-1982 (Confirmed in 1988) - Tolerances for Fasteners - Bolts, Screws, and Nuts (EQV ISO4759-1:1978) GB/T5267-1985 Electroplated Coatings for Threaded Fasteners

GB/T5276-1985 Fasteners - Dimensions, designations, and markings for bolts, screws, studs, and nuts (EQC ISO 225:1983) GB/T5779.2-2000 Fasteners - Surface defects - Nuts (IDT ISO 6157.2:1995)

GB/T6170-2000 L-type hexagonal nut (EQV ISO 4032:1999)

GB/T6938-1997 Fasteners - General technology Conditions for Bolts, Screws, Studs and Nuts (IDT ISO8992:1996) ISO10683:2000 Fasteners - Non electrolytic zinc powder coating

So where are high-strength nuts used?

Used in high-strength bolt sets, with a strength grade (after heat treatment) of 10, used in conjunction with grade 10.9 bolts.

There are differences in the mechanical properties and calculation methods between ordinary bolts and high-strength bolts. The force of high-strength bolts is first borne by applying a pre tension force P inside them, and then generating frictional resistance on the contact surface between the connected parts to withstand external loads, while ordinary bolts directly bear external loads. High strength bolt connection has the advantages of simple construction, good stress performance, detachable replacement, fatigue resistance, and non loosening under dynamic loads, making it a promising connection method.

High strength bolts use a special wrench to tighten the nut, causing the bolt to generate a huge and controlled pre tension. Through the nut and pad, the connected parts are also subjected to the same amount of pre pressure. Under the action of preload, a large frictional force will be generated along the surface of the connected component. Obviously, as long as the axial force is less than this frictional force, the component will not slip and the connection will not be damaged. This is the principle of high-strength bolt connection.

High strength bolt connections rely on the friction between the contact surfaces of the connecting components to prevent their mutual sliding. In order to have sufficient friction on the contact surfaces, it is necessary to increase the clamping force of the components and increase the friction coefficient of the contact surfaces of the components. The clamping force between components is achieved by applying pre tension to the bolts, so the bolts must be made of high-strength steel, which is why they are called high-strength bolt connections.