In 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 gasket side of the above-mentioned nut assembly is in contact with the mounting surface. When the nut is tightened, the gasket squeezes the outer cone surface to make it shrink, and the cone tip faces the same direction as the nut, thereby preventing the nut from tightening, so that the nut fixing effect is not good, and at the same time When multiple nuts need to be superimposed and fixed, two adjacent nuts cannot interact with each other, resulting in poor fixing effect.
Classification broadcast product series Product detailed classification Hexagon bolts (1) Hexagon bolts (1) Hexagon full teeth: GB5783/DIN933 (2) Hexagon half teeth; GB5782/DIN931 (3) Class B flange hexagon bolts: GB5787 (4) Joint bolts: GB798/DIN444 (5) Welding bolts for manual welding: GB902 square neck bolts (1) Half round head square neck bolts: GB14/DIN603 (2) Small half round head square neck bolts: GB12 (3) Half round head low square neck bolts: GB801 Remarks: Square neck bolts and carriage bolts Hexagon socket head cap screws (1) Hexagon socket head cap screws: GB70/DIN912 (2) Hexagon socket flat end set screws: BG70/DIN913 (3) Hexagon socket head set screws: GB78/DIN914 ( 4) Countersunk head socket head socket head set screw: GB79/DIN915 (5) Hexagon socket socket head set screw: GB80/DIN916 (6) Hexagon socket head countersunk head screw: DIN7991 (7) Hexagon socket head thin head screw: DIN7984 ( 8) Plug screw: ISO7379 machine screw (1) Slotted cylinder head screw: GB65/DIN84 (2) Slotted pan head screw: GB67/DIN85 (3) Slotted countersunk head screw: GB68/DIN963 (4) Slotted Large flat head screw (5) Cross recessed small pan head screw: GB823 (6) Cross recessed large flat head screw (7) Cross recessed pan head screw: GB818/DIN7985 (8) Cross recessed countersunk head screw: GB819/DIN965 (9 ) Cross recessed countersunk head screw: GB820/DIN966 thread and stud (2) Stud bolt-bm=1d: GB897/DIN938 (3) Stud bolt-bm=1.25d: GB898/DIN939 (4) Stud head Bolt-bm=1.5d: GB899 (5) Stud bolt-bm=2d: GB900 (1) Tooth bar: GB15389/DIN976 (6) Equal length stud: GB901/DIN976
In the process of completing the adjustment of the position of the object, the nut will move up and down with the entry and exit of the screw, and it cannot make a sound for people to perceive, and it cannot provide people with a position change distance through the action of rotation.
The screw rod in the ordinary T-slot nut is cuboid, so the T-slot nut can only be inserted into the nut from the end face of the T-slot, which makes it impossible to quickly complete the installation of the T-nut, which is inconvenient to use. Usefulness is greatly limited.
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