Service HotlineIn the manufacture of fasteners, the correct selection of fastener materials is an important part, because the performance of fasteners is closely related to its materials. If the material is improperly or incorrectly selected, the performance may not meet the requirements, the service life may be shortened, or even accidents or processing difficulties may occur, and the manufacturing cost will be high. Therefore, the selection of fastener materials is a very important link. Cold heading steel is a steel for fasteners with high interchangeability produced by cold heading forming process. Because it is formed by metal plastic processing at room temperature, each part has a large amount of deformation and a high deformation speed. Therefore, the performance requirements of cold heading steel raw materials are very strict. On the basis of long-term production practice and user research, combined with GB/T6478-2001 Technical Conditions for Cold Heading and Cold Extrusion Steel GB/T699-1999 High-Quality Carbon Structural Steel and target JISG3507-1991 Cold Heading Characteristics of Carbon Steel Wire Rod for Steel, taking the material requirements of grade 8.8 and grade 9.8 bolts and screws as an example, the determination of various chemical elements. If the C content is too high, the cold formability will be reduced; if it is too low, the mechanical properties of the parts cannot be met, so it is set at 0.25% - 0.55%. Mn can improve the permeability of steel, but adding too much will strengthen the matrix structure and affect the cold forming performance; when the part is quenched and tempered, it has the tendency to promote the growth of austenite grains, so it should be appropriately improved on the basis of international standards. 0.45 % - 0.80 %. Si can strengthen the ferrite and reduce the cold formability. SP is an impurity element, and their existence will cause segregation along the grain boundary, resulting in the embrittlement of the grain boundary and damage to the mechanical properties of the steel. It should be reduced as much as possible. B. The maximum value of boron content is 0.005%, because although boron element can significantly improve the permeability of steel, it will also increase the brittleness of steel. Excessive boron content is very unfavorable for workpieces such as bolts, screws and studs that require good comprehensive mechanical properties.
The shear strength of a metal material refers to the ability of the material to withstand shearing force, which refers to the strength of the external force perpendicular to the material axis and shearing the material. The test is usually to install the cylindrical pin into the specified fixture, and the gap between the supporting part and the loading part is required to be no more than 0.15mm, and then force is applied to test the shear strength of the material.
The hexagonal flange surface nut mainly includes a nut body, a flange surface is fixed at one end of the nut body, and a cap is fixed at the other end of the nut body. Has good sealing and corrosion resistance. The hexagonal flange surface nut mainly includes a nut body, a flange surface is fixed at one end of the nut body, and a cap is fixed at the other end of the nut body; since the cap is set on the nut body, it has the Better sealing can effectively prevent rain, moisture, dust and other harmful substances from immersing in the nut body, prevent the nut body from rusting, and greatly extend the service life of the hexagonal flange nut.
Flat gaskets are usually thin pieces of various shapes used to reduce friction, prevent leakage, isolate, prevent loosening, or distribute pressure. There are such components in many materials and structures. The existing flat washer has a simple structure design. After long-term use, the phenomenon of thinning of the thickness is likely to occur, which in turn leads to poor wear resistance of the flat washer.
In order to solve the problem of nut loosening, various self-locking nuts have appeared, which have complex structure, high production cost, inconvenient installation and unsatisfactory anti-loosening effect. At present, the never-loosening nuts produced in Japan are mostly used, mainly in the form of double nuts. Each nut is provided with an eccentric cam protrusion, and each nut is provided with a groove and an inclined plane to squeeze the cam protrusion of each nut. When pressing, the cam protrusion of the nut will move to a small radius along the slope of the nut, so that the nut will not loosen, but whether it is a nut or a nut, it is always under the action of eccentric force. In addition, various non-loose nuts designed by many manufacturers are to increase the friction between the nut and the fastening workpiece or increase the barb to achieve the purpose of never loosening, but the effect is not ideal.
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